Prevention or treatment of fibrotic diseases

Abstract

The present invention provides a technique for identifying marker proteins of myofibroblasts and preventing or treating fibrotic diseases. The present invention relates to a preventive or therapeutic agent for fibrotic diseases, which contains a GPR176 inhibitor as an active ingredient.

Description

[Technical field]

[0001] The present invention relates to a pharmaceutical composition for preventing or treating a fibrotic disease. In particular, the present invention relates to a substance and a nucleic acid molecule for preventing or treating a fibrotic disease, as well as a method for screening the same and a kit therefor. [Background technology]

[0002] Fibrosis is a state in which extracellular matrices such as collagen are excessively produced in biological tissues. Fibrosis is known to cause the deterioration of pathological conditions in various organs such as the heart, liver, kidneys, and lungs. However, there are few effective therapeutic agents for fibrotic diseases, and their development is required.

[0003] It is known that tissue fibrosis is carried out by a group of cells called myofibroblasts, which produce collagen, etc. It is also known that myofibroblasts are hardly present when tissues are normal, but are generated by the differentiation of various cells in response to inflammation.

[0004] Conventionally, proteins such as α-Smooth Muscle Actin (α-SMA) are known as markers for myofibroblasts (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2004-81122 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, α-SMA is not strictly a myofibroblast-specific marker protein in terms of cell specificity and timing of expression, as it is strongly expressed in vascular smooth muscle, etc. For this reason, the identification of myofibroblast marker proteins in the strict sense is a bottleneck in myofibroblast research.

[0007] An object of the present invention is to provide a technique for identifying marker proteins of myofibroblasts and preventing or treating fibrotic diseases. [Means for solving the problem]

[0008] G Protein-Coupled Receptor 176 (hereafter referred to as GPR176) is registered as one of the orphan receptors in NCBI (https: / / www.ncbi.nlm.nih.gov / gene / ?term=GPR176). So far, GPR176 has only been identified as a Gz-coupled orphan G protein-coupled receptor that sets the pace of circadian behavior (NATURE COMMUNICATIONS | 7:10583 | DOI: 10.1038 / ncomms10583 | Published 17 Feb 2016). The present inventors have conducted extensive research aimed at preventing or treating fibrotic diseases and have found that GPR176 is closely related to organ fibrosis. As a result of further research, they have found that inhibition or suppression of the expression and function of GPR176 reduces or prevents fibrosis, thereby completing the present invention.

[0009] That is, the present invention includes the following aspects. <Pharmaceutical composition for preventing or treating fibrotic diseases> [1] a pharmaceutical composition for preventing or treating a fibrotic disease, comprising an inhibitor of G protein-coupled receptor 176 (GPR176) as an active ingredient; [2] The pharmaceutical composition according to [1], wherein the GPR176 inhibitor is an inhibitor of GPR176 expression or an inhibitor of GPR176 function; [3] [2] The pharmaceutical composition according to [2], wherein the GPR176 inhibitor is an inhibitor of GPR176 expression; [4] The pharmaceutical composition according to [2], wherein the inhibitor of GPR176 expression is a substance that inhibits the expression of a gene or nucleic acid represented by any one of the following (a) to (c): (a) a GPR176 gene as shown in any one of SEQ ID NOs: 2, 4, or 6 in the sequence listing; (b) a nucleic acid comprising a base sequence in which one or several bases are deleted, substituted or added in the GPR176 gene shown in any one of SEQ ID NOs: 2, 4 and 6 in the sequence listing; (c) a nucleic acid that hybridizes under stringent conditions with a nucleotide sequence complementary to the GPR176 gene shown in any one of SEQ ID NOs: 2, 4, and 6 in the sequence listing; [5] The pharmaceutical composition according to [4], wherein the substance that inhibits the expression of a gene or nucleic acid is selected from the group consisting of siRNA, antisense and ribozyme; [6] [2] The pharmaceutical composition according to [2], wherein the GPR176 inhibitor is an inhibitor of GPR176 function; [7] The pharmaceutical composition according to [6], wherein the inhibitor of GPR176 function is a substance that specifically binds to GPR176 protein; [8] The pharmaceutical composition according to [7], wherein the substance that specifically binds to the GPR176 protein is selected from the group consisting of an antibody, an antibody fragment, and an aptamer; [9] The pharmaceutical composition according to [8], wherein the antibody fragment is selected from the group consisting of Fv, Fab and scFv; <Nucleic acids, etc.>

[10] (a) a GPR176 gene as shown in any one of SEQ ID NOs: 2, 4, or 6 in the sequence listing; (b) a nucleic acid comprising a base sequence in which one or several bases are deleted, substituted or added in the GPR176 gene shown in any one of SEQ ID NOs: 2, 4 and 6 in the sequence listing; (c) a nucleic acid that hybridizes under stringent conditions with a base sequence complementary to the GPR176 gene shown in any one of SEQ ID NOs: 2, 4, and 6 in the sequence listing; a nucleic acid selected from the group consisting of siRNA, antisense and ribozyme, which inhibits the expression of

[11]

[10] A vector comprising the gene or nucleic acid according to claim 1.

[12]

[11] A cell comprising the vector described in claim 1. <Screening method>

[13] (a) a GPR176 gene as shown in any one of SEQ ID NOs: 2, 4, 6, or 8 in the sequence listing; (b) a nucleic acid comprising a base sequence in which one or several bases are deleted, substituted or added in the GPR176 gene shown in any one of SEQ ID NOs: 2, 4, 6 and 8 in the sequence listing; (c) a method for screening for a substance that inhibits GPR176, comprising using a nucleic acid that hybridizes under stringent conditions with a base sequence complementary to the GPR176 gene shown in any one of SEQ ID NOs: 2, 4, 6, and 8 in the sequence listing, or a cell into which the nucleic acid or a nucleic acid has been introduced, and confirming that expression of the gene or nucleic acid is inhibited;

[14] (1) preparing a candidate compound; (2) (a) a GPR176 gene as shown in any one of SEQ ID NOs: 2, 4, 6, or 8 in the sequence listing; (b) a nucleic acid comprising a base sequence in which one or several bases are deleted, substituted or added in the GPR176 gene shown in any one of SEQ ID NOs: 2, 4, 6 and 8 in the sequence listing; (c) contacting the candidate compound with a cell having a gene or a nucleic acid that hybridizes under stringent conditions to a base sequence complementary to the GPR176 gene shown in any one of SEQ ID NOs: 2, 4, 6, and 8 in the sequence listing; (3) The method of

[13] for screening for an inhibitor of GPR176, comprising determining whether the candidate compound suppresses the expression of the gene or nucleic acid;

[15] The method according to

[13] or

[14] , using the GPR176 gene shown in any one of SEQ ID NOs: 2, 4, or 6 in the sequence listing;

[16] A method for screening for a substance that inhibits the function of a GPR176 protein having an amino acid sequence shown in any one of SEQ ID NOs: 1, 3, 5 and 7 in the sequence listing, or a mutant GPR176 protein having a substitution, deletion or addition of one or several amino acid residues in said GPR176 protein, said mutant GPR176 protein having activity equivalent to that of said GPR176 protein;

[17] (1) preparing a candidate compound; (2) contacting the candidate compound with a GPR176 protein having an amino acid sequence shown in any one of SEQ ID NOs: 1, 3, 5, or 7 in the sequence listing, or a mutant GPR176 protein having one or more amino acid residues substituted, deleted, or added in the GPR176 protein and having an activity equivalent to that of the GPR176 protein, or a cell expressing the GPR176 protein or the mutant GPR176 protein; (3) A method for screening a substance that inhibits the function of GPR176 protein, comprising determining whether or not the candidate compound inhibits the function of the GPR176 protein or the mutant GPR176 protein;

[18] The method according to

[16] or

[17] , which uses a GPR176 protein having an amino acid sequence shown in any one of SEQ ID NOs: 1, 3 or 5 in the sequence listing, or a mutant GPR176 protein having a substitution, deletion or addition of one or several amino acid residues in the GPR176 protein, and which has an activity equivalent to that of the GPR176 protein;

[19] A method for screening for a preventive or therapeutic agent for a fibrotic disease, comprising the steps of culturing myofibroblasts in the presence of a candidate compound, quantifying the expression level of GPR176 gene mRNA or GPR176 protein in the cultured myofibroblasts, and determining that the candidate compound is a preventive or therapeutic agent for a fibrotic disease when the quantified expression level of GPR176 gene mRNA or GPR176 protein is decreased compared to a control; <Biomarkers, etc.>

[20] A method for determining the severity of a fibrotic disease, comprising: (a10) measuring the amount of GPR176 in myofibroblasts of the subject (test biomarker amount); (b10) comparing the amount of the test biomarker with the amount of GPR176 in myofibroblasts of a healthy subject (a control biomarker amount); and (c10) a method for determining that a subject has a fibrotic disease that becomes severe when the amount of the test biomarker is greater than the amount of the control biomarker; [twenty one] A biomarker that can determine the severity of fibrotic diseases is GPR176 in myofibroblasts; <Kit> [twenty two] A kit for detecting myofibroblasts, comprising a primer set for amplifying GPR176 cDNA, a probe that specifically hybridizes to GPR176 mRNA, or a substance that specifically binds to GPR176 protein. Effect of the Invention

[0010] According to the present invention, it is possible to provide a technique for identifying a marker protein of myofibroblasts and preventing or treating a fibrotic disease. [Brief description of the drawings]

[0011] [Figure 1] Figure 1A is a graph showing the results of measuring the mRNA expression levels of GPR176 in cardiac tissues of myocardial infarction model mice and control mice, and Figure 1B is a graph showing the results of measuring the mRNA expression levels of α-SMA in cardiac tissues of myocardial infarction model mice and control mice.

[0012] [Figure 2A] Figure 2A is a photograph showing the results of in situ hybridization assay evaluating GPR176 mRNA in heart sections from WT (wild-type) mice 7 days after sham or myocardial infarction. Nuclei were counterstained with hematoxylin. The black arrow indicates GPR176 mRNA. Scale bar: 50 μm. [Figure 2B] Figure 2B shows the gate settings for FACS to sort hematopoietic cells (Hem) and myofibroblasts (Myo) from the heart after myocardial infarction. Cells including hematopoietic cells and myofibroblasts were isolated from the heart of WT mice on day 3 after myocardial infarction. The isolated cells were immediately stained with anti-PDGFR-α and anti-CD45 antibodies and analyzed by FACS. [Figure 2C] Figure 2C is a graph showing the mRNA expression levels of the indicated genes (Cd68, Acta2, and Col1a1) in cells sorted as hematopoietic cells (Hem) and myofibroblasts (Myo). Cd68 and Col1a1 / Acta2 were used as markers for macrophages and myofibroblasts, respectively. n = 3. GAPDH was used as an internal control. *P < 0.05, **P < 0.01, ***P < 0.001, unpaired two-tailed Student's t test. [Figure 2D]Figure 2D is a graph showing the mRNA expression levels of GPR176 in cells sorted as hematopoietic cells (Hem) and myofibroblasts (Myo). n = 3. GAPDH was used as an internal control. *P < 0.05, **P < 0.01, ***P < 0.001, unpaired two-tailed Student's t test. [Figure 2E] FIG. 2E is a schematic diagram showing cell sorting from myocardial infarction-treated hearts using MACS. [Figure 2F] Figure 2F is a graph showing the mRNA expression levels of the indicated genes (Cd68, Acta2, and Col1a1) in cells sorted as hematopoietic cells (Hem) and myofibroblasts (Myo). Cd68 and Col1a1 / Acta2 were used as markers for macrophages and myofibroblasts, respectively. n = 5. GAPDH was used as an internal control. *P < 0.05, **P < 0.01, ***P < 0.001, unpaired two-tailed Student's t test. [Figure 2G] Figure 2G is a graph showing the mRNA expression levels of GPR176 in cells sorted as hematopoietic cells (Hem) and myofibroblasts (Myo). n = 5. GAPDH was used as an internal control. *P < 0.05, **P < 0.01, ***P < 0.001, unpaired two-tailed Student's t test.

[0013] [Diagram 3] 3A to 3C are fluorescent micrographs showing the results of in situ hybridization (GPR176 mRNA) and immunostaining (α-SMA).

[0014] [Figure 4]Figure 4A is a photograph showing the results of picrosirius red staining of paraffin-embedded ventricular sections from wild-type (WT) and GPR176 KO mice on day 28 after myocardial infarction treatment. Scale bar, 1 mm. Figure 4B: Graph showing quantitative data of collagen volume fraction (CVF) of WT and GPR176 KO mice on day 28 after myocardial infarction treatment. CVF was determined by quantifying the collagen deposition area. WT; n = 6, GPR176 KO; n = 6. Error bars represent the mean ± SEM. Figure 4B: *P < 0.05, unpaired two-tailed Student's t-test.

[0015] [Diagram 5] Figure 5 shows that GPR176 deficiency improves cardiac function after infarction. Figure 5A: Graph showing the results of echocardiographic analysis of the hearts of wild-type (WT) and GPR176 KO mice 28 days after myocardial infarction. HR; heart rate, IVSTd; diastolic interventricular septum thickness, LVIDd; left ventricular end-diastolic internal diameter, LVID; left ventricular end-systolic internal diameter, LVPWd; left ventricular posterior wall diastole, EF; ejection fraction, FS; left ventricular fractional shortening. WT-Sh (sham); n = 18, KO-Sh (sham); n = 16, WT-MI (infarction); n = 12, GPR176 KO-MI (infarction); n = 9. Error bars represent the mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001, unpaired two-tailed Student's t-test. (B) Graphs showing heart to body weight ratios and lung to body weight ratios in WT and GPR176 KO mice 28 days after myocardial infarction. WT-Sh (sham); n = 18, KO-Sh (sham); n = 16, WT-MI (infarction); n = 12, GPR176 KO-MI (infarction); n = 9. Error bars represent mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001, unpaired two-tailed Student's t test.

[0016] [Figure 6]Figure 6 shows that GPR176 deficiency reduces fibrosis after myocardial infarction. Figure 6A, B: Graphs showing the mRNA expression levels of fibrosis-related factors (Ctgf, Postn, and Fn1) (A) and cardiac hypertrophy genes (Igf1, Nppa, and Nppb) (B) in the hearts of WT and GPR176 KO mice 7 days after myocardial infarction. GAPDH was used as an internal control. WT-Sh (sham treatment); n = 5, WT-In (infarction treatment); n = 5, GPR176 KO-Sh (sham treatment); n = 4, GPR176 KO infarction treatment; n = 5. Error bars represent the mean ± SEM. "Sh" indicates the sham treatment group, "In" indicates the infarcted part of the heart 7 days after myocardial infarction, and "Re" indicates the part of the heart distant from the infarcted part 7 days after myocardial infarction. *P<0.05, **P<0.01, ***P<0.001, unpaired two-tailed Student's t-test.

[0017] [Figure 7A] Figure 7A is a graph showing the sorting of CD45(-)Thy1.2(+) cell fractions from WT mice. In the figure, "WT" represents the results for wild-type mice, and "myofibroblast" represents a cell population containing myofibroblasts. "Viability Dye" is a dye used to determine cell death. [Figure 7B] Figure 7B is a graph showing the sorting of CD45(-)Thy1.2(+) cell fractions from GPR176 knockout mice. In the figure, "GPR176 KO" represents the results for GPR176 knockout mice, and "myofibroblast" represents the results for a cell population containing myofibroblasts. "Viability Dye" is a dye for determining dead cells.

[0018] [Figure 8]Figure 8 is a graph showing the results of measuring the expression levels of fibrosis-related factors in each cell fraction. Figure 8A shows the results of measuring the expression levels of the Acta2 gene, B shows the results of the Col1a1 gene, C shows the results of the Ctgf gene, and D shows the results of the Postn gene. In the figure, "WT" indicates the results for wild-type mice, and "KO" indicates the results for GPR176 knockout mice. The expression levels of each gene are shown as relative values ​​to the expression level of the GAPDH gene.

[0019] [Figure 9A] Figure 9A shows a schematic diagram of the myofibroblast-specific GPR176-deficient mice used. Myofibroblast-specific GPR176-deficient mice were generated by crossing a mouse expressing Cre (a DNA recombinase enzyme) downstream of the periostin gene promoter with a genetically modified mouse in which exon 2 of GPR176 was sandwiched between LoxP sequences (a target sequence for Cre recombinase). [Figure 9B] FIG. 9B is a graph showing the mRNA expression levels of fibrosis-related factors (Ctgf, Postn, and Fn1) in the hearts of Ctrl (control) and myofibroblast-specific GPR176 KO mice 7 days after myocardial infarction. "Sh" indicates the sham group, "In" indicates the infarcted part of the heart 7 days after myocardial infarction, and "Re" indicates the part of the heart remote from the infarcted part 7 days after myocardial infarction. GAPDH was used as an internal control. Ctrl-Sh (sham); n = 8, Ctrl-In (infarct); n = 6, GPR176 cKO-Sh (sham); n = 7, GPR176 cKO-In (infarct); n = 7. Error bars represent the mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001, unpaired two-tailed Student's t test. [Figure 9C]FIG. 9C is a graph showing the mRNA expression levels of cardiac hypertrophy genes (Igf1, Nppa, and Nppb) in the hearts of Ctrl (control) and myofibroblast-specific GPR176 KO mice 7 days after myocardial infarction. "Sh" indicates the sham group, "In" indicates the infarcted portion of the heart 7 days after myocardial infarction, and "Re" indicates the portion of the heart remote from the infarcted portion 7 days after myocardial infarction. GAPDH was used as an internal control. Ctrl-Sh (sham); n = 8, Ctrl-In (infarct); n = 6, GPR176 cKO-Sh (sham); n = 7, GPR176 cKO-In (infarct); n = 7. Error bars represent the mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001, unpaired two-tailed Student's t test. [Figure 9D] Figure 9D shows Kaplan-Meier survival curves in Ctrl and GPR176 cKO mice 28 days after infarction. Differences between Ctrl-MI and GPR176 cKO-MI were assessed by log-rank test. Ctrl; n = 20, GPR176 KO; n = 20. [Figure 9E] Figure 9E is a photograph showing picrosirius red staining of paraffin-embedded ventricular sections from Ctrl and GPR176 cKO mice 28 days after infarction. Scale bar, 1 mm. [Figure 9F] (F) Quantitative data of collagen volume fraction (CVF) in Ctrl and GPR176 cKO mice at 28 days after infarction: Ctrl-Sh (sham); n = 12, GPR176 cKO-Sh (sham); n = 8, Ctrl-MI (infarction); n = 9, cKO-MI (infarction); n = 10. Error bars represent mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001, unpaired two-tailed Student's t test.

[0020] [Figure 10A]FIG. 10A is a graph showing the results of echocardiographic analysis of the hearts of Ctrl and GPR176 cKO mice 28 days after infarction. HR; heart rate, IVSTd; interventricular septum thickness in diastole, LVIDd; left ventricular end-diastolic internal diameter, LVID; left ventricular end-systolic internal diameter, LVPWd; left ventricular posterior wall in diastole, EF; ejection fraction, FS; fractional shortening. Ctrl-Sh (sham); n = 13, GPR176 cKO-Sh (sham); n = 8 Ctrl-MI (infarction); n = 15, GPR176 cKO-MI (infarction); n = 14. Error bars represent the mean ± SEM. *P < 0.05, NS not significant, unpaired two-tailed Student's t test. [Figure 10B] (B) Heart to body weight ratios and lung to body weight ratios in infarcted hearts of Ctrl and GPR176 cKO mice at 28 days after infarction. Ctrl-Sh (sham); n = 13, GPR176 cKO-Sh (sham); n = 8, Ctrl-MI (infarcted); n = 15, GPR176 cKO-MI (infarcted); n = 14. Error bars represent mean ± SEM. *P < 0.05, NS not significant, unpaired two-tailed Student's t test.

[0021] [Figure 11A] Figure 11A is a graph showing the results of measuring the expression levels of marker molecules for myofibroblasts, hepatocytes, and macrophages in each cell fraction (HC: hepatocyte, KC: Kupffer cell, HSC: hepatic stemate cell) of the liver of mice with liver damage caused by carbon tetrachloride administration. The expression levels of the genes α-SMA (Acta2), Col1a1 (Col1a1), Cyp7a1 (Cyp7a1), and CD68 (Cd68) are shown as relative values ​​to the expression level of the GAPDH gene. [Figure 11B]Fig. 11B is a graph showing the results of measuring the expression level of GPR176 in each cell fraction (HC: hepatocyte, KC: Kupffer cell, HSC: hepatic stellate cell) of the liver of mice with hepatic damage caused by carbon tetrachloride administration. The expression level is shown as a relative value to the expression level of the GAPDH gene.

[0022] [Figure 12A] Figure 12A shows the results of quantifying the expression of α-SMA in the liver of mice from the control group not administered carbon tetrachloride (n = 4 - 6), the group administered carbon tetrachloride for 4 weeks (n = 6), and the group administered carbon tetrachloride for 4 weeks and then stopped administration and reared for 4 weeks (n = 5) by real-time RT-PCR. In the figure, "Control" shows the results of the control group, "CCl4" shows the results of the group administered carbon tetrachloride for 4 weeks, and "After administration stopped" shows the results of the group administered carbon tetrachloride for 4 weeks and then stopped administration and reared for 4 weeks. *** P < 0.001, unpaired two-tailed Student's t test. [Figure 12B] Figure 12B is a graph showing the results of quantifying the expression level of GPR176 in the liver of mice from the control group (n = 4 - 6) not administered carbon tetrachloride (CCl4), the group administered carbon tetrachloride for 4 weeks (n = 6), and the group administered carbon tetrachloride for 4 weeks and then stopped administration and reared for 4 weeks (n = 5) by real-time RT-PCR. In the figure, "Control" shows the results of the control group, "CCl4" shows the results of the group administered carbon tetrachloride for 4 weeks, and "After administration stopped" shows the results of the group administered carbon tetrachloride for 4 weeks and then stopped administration and reared for 4 weeks. *** P < 0.001, unpaired two-tailed Student's t test.

[0023] [Figure 13A] Figure 13A is a graph showing the results of quantifying the expression level of COl1a1 in the liver of control mice fed a normal diet (n = 5) and NASH model mice fed a diet designed to produce NASH (n = 5) by real-time RT-PCR. *** P < 0.001, unpaired two-tailed Student's t test. [Figure 13B] Figure 13B is a graph showing the results of quantifying the expression level of GPR176 in the liver of control mice fed a normal diet (n = 5) and NASH model mice fed a diet designed to produce NASH (n = 5) by real-time RT-PCR. *** P < 0.001, unpaired two-tailed Student's t test.

[0024] [Figure 14A] FIG. 14A shows a schematic diagram for inducing pulmonary fibrosis in mice by intratracheal administration of bleomycin. [Figure 14B] FIG. 14B is a graph showing the mRNA expression levels of fibrosis-related factors (Acta2, Ctgf, and Postn) in the lungs of saline- or BLM-treated mice. 18S rRNA was used as an internal control. Saline; n = 6, BLM; n = 8. Error bars represent the mean ± SEM. ** P < 0.01, *** P < 0.001, unpaired two-tailed Student's t test. [Figure 14C] Figure 14C is a graph showing the mRNA expression levels of GPR176 in the lungs of saline or BLM-treated mice. 18S rRNA was used as an internal control. Saline; n = 6, BLM; n = 8. Error bars represent the mean ± SEM. **P < 0.01, ***P < 0.001, unpaired two-tailed Student's t-test. [Figure 14D] FIG. 14D is a schematic diagram showing how mice are subjected to unilateral ureteral obstruction (UUO) to induce renal fibrosis. [Figure 14E] Figure 14E is a graph showing the mRNA expression levels of renal fibrosis-related factors (Acta2, Col1a1, Ctgf) in sham- or UUO-treated mice. GAPDH was used as an internal control. Sham; n = 5, UUO; n = 5. Error bars represent the mean ± SEM. ** P < 0.01, *** P < 0.001, unpaired two-tailed Student's t test. [Figure 14F]Figure 14F is a graph showing renal GPR176 mRNA expression levels in sham- or UUO-treated mice. GAPDH was used as an internal control. Sham; n = 5, UUO; n = 5. Error bars represent mean ± SEM. **P < 0.01, ***P < 0.001, unpaired two-tailed Student's t test.

[0025] [Figure 15] Figure 15 shows that GPR176 is expressed in myofibroblasts even during pulmonary fibrosis. Figure 15A: Photographs showing the results of detecting GPR176 mRNA in lung sections from WT (wild-type) mice 7 days after BLM administration by in situ hybridization (left) and immunostaining with anti-αSMA antibody (center). The "Merge" on the right is a superposition of the two. Figures 15B, C, and D: Photographs showing the results of detecting GPR176 mRNA in lung sections from WT mice 7 days after BLM administration by in situ hybridization (left) and immunostaining with anti-αSMA (B), CD31 (C), and CD45 antibodies (D) (center). The "Merge" on the right is a superposition of the two. Scale bar; 50 μm.

[0026] [Figure 16A] Figure 16A is a graph showing the mRNA expression levels of GPR176, fibrosis-related factors (Ctgf, Postn, Fn1, and Tgfb2), and cardiac hypertrophy gene (Igf1) in cardiac myofibroblasts treated with siRNA against GPR176. 18S rRNA was used as an internal control. n = 7-8. Error bars represent the mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001, unpaired two-tailed Student's t test. [Figure 16B]FIG. 16B is a graph showing the mRNA expression levels of GPR176, fibrosis-related factors (Ctgf, Postn, Fn1, and Tgfb2), and hypertrophy gene (Igf1) in cardiac fibroblasts overexpressing GPR176. 18S rRNA was used as an internal control. n = 4. Error bars represent the mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001, unpaired two-tailed Student's t test.

[0027] [Figure 17] Figure 17 is a photograph showing that cells expressing GPR176 mRNA in the border (peri-infarct area) or infarct (infarct region) of mouse hearts after myocardial infarction treatment express α-SMA, and a graph quantifying the percentage of GPR176-positive cells expressing α-SMA in the border (peri-infarct area) or infarct (infarct region).

[0028] [Figure 18A] Figure 18A is a set of photographs showing the detection of GPR176 mRNA and Postn mRNA by in situ hybridization (left, center) and the results of immunostaining with anti-αSMA antibody in myofibroblasts isolated from mouse hearts 3 days after infarction treatment. [Figure 18B] Figure 18B is a photograph showing detection of GPR176 mRNA by in situ hybridization (left) and immunostaining with anti-CD68 antibody (center) in blood cell [CD45 positive cell] isolated from a mouse 3 days after infarction treatment. The "Merge" on the right is a superposition of the two. [Figure 18C] Figure 18C is a graph quantifying the percentage of cells that are GPR176 mRNA positive among marker positive [αSMA positive, Postn positive, or CD68 positive] cells. Data was averaged from 5 hearts, each quantified over 100 cells. [Figure 18D]Figure 18D is a graph quantifying the percentage of cells that were αSMA positive among GPR176 mRNA positive cells. Data was averaged from 5 hearts, with over 100 cells quantified each. [Figure 18E] Figure 18E is a graph quantification of Postn mRNA positive cells among GPR176 mRNA positive cells. Data was averaged from 5 hearts, each quantified over 100 cells.

[0029] [Figure 19A] FIG. 19A shows a method for isolating myofibroblasts [CD45(-), CD31(-), CD326(-) cells] and blood cells [CD45(+) cells] using MACS from WT mice 7 days after BLM treatment. [Figure 19B] Figure 19B is a photograph showing the results of in situ hybridization detection of GPR176 mRNA expression in myofibroblasts [CD45(-), CD31(-), CD326(-) cells] isolated from mouse lungs 7 days after BLM treatment, and immunostaining with anti-αSMA antibody (center). [Figure 19C] Figure 19C is a photograph showing the expression of GPR176 mRNA in blood cells [CD45(+) cells] isolated from mouse lungs 7 days after BLM treatment, detected by in situ hybridization (left) and immunostained with anti-CD68 antibody (center). [Figure 19D] Figure 19D is a graph quantifying the percentage of cells that are GPR176 mRNA positive among αSMA positive or CD68 positive cells. Data was averaged from 5 hearts, with over 100 cells quantified each. [Figure 19E] Figure 19E is a graph quantifying the percentage of cells that are αSMA positive among GPR176 mRNA positive cells. Data was averaged from 5 hearts, with over 100 cells quantified each.

[0030] [Figure 20]Figure 20 shows that GPR176 is also specifically expressed in myofibroblasts in the human heart. Figure 20A: Photographs showing the results of detecting the expression of GPR176 mRNA (second from the left: GPR176) in a heart section from a patient without myocardial infarction by in situ hybridization and the results of immunostaining with an anti-αSMA antibody (second from the right: αSMA). Bright field is a photograph showing the results of bright field observation. Figure 20B: Photographs showing the results of detecting the expression of GPR176 mRNA (second from the left: GPR176) in a heart section from a patient with myocardial infarction by in situ hybridization and the results of immunostaining with an anti-αSMA antibody (second from the right: αSMA). The arrow indicates GPR176 mRNA. Scale bar; 20 μm

[0031] [Figure 21] Figure 21 shows that most tdTomato-labeled cells in the heart of GPR176 reporter mice after myocardial infarction treatment are myofibroblasts. Figure 21A: Schematic diagram of the mouse strain used. A genetically modified mouse with Cre knocked in downstream of the GPR176 promoter was generated, and this mouse was crossed with a Rosa26-tdTomato mouse (Jackson Laboratory Stock No: 007914) to generate a reporter mouse in which GPR176-expressing cells are labeled by tdTomato. Figure 21B: Photographs showing images of infarcted heart sections stained for GPR176 (far left), αSMA (second from the left), and CD68 (center) labeled by tdTomato. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] <Preventive or therapeutic agent for fibrotic diseases> In one embodiment, the present invention comprises: GA pharmaceutical composition for preventing or treating fibrotic diseases is provided, which contains an inhibitor of protein-coupled receptor 176 (GPR176), specifically an inhibitor of GPR176 expression or an inhibitor of GPR176 function as an active ingredient. In the present invention, GPR176 includes human GPR176 and mouse GPR176, and further includes variants thereof. The amino acid sequences and nucleic acid sequences of variant 1, variant 2, and variant 3 of human GPR176 are shown in SEQ ID NOs: 1 and 2 of the sequence listing for variant 1, SEQ ID NOs: 3 and 4 of the sequence listing for variant 2, and SEQ ID NOs: 5 and 6 of the sequence listing for variant 3, respectively. The amino acid sequence and nucleic acid sequence of mouse GPR176 are shown in SEQ ID NOs: 7 and 8 of the sequence listing, respectively. As described later in the Examples, GPR176 is a myofibroblast-specific membrane surface marker molecule and a molecule that promotes fibrosis. Therefore, an inhibitor of GPR176 can be used to prevent or treat fibrotic diseases.

[0033] In the present invention, fibrosis refers to a phenomenon in which substances called extracellular matrix such as collagen fibers (collagen) increase in the skin or internal organs, resulting in the skin or internal organs becoming hard, and is also called "sclerosis." In the present invention, fibrotic diseases refer to cardiac fibrosis, liver fibrosis, kidney fibrosis, pulmonary fibrosis, systemic sclerosis, and skin sclerosis.

[0034] In the present invention, "inhibition" in "inhibitor" refers to a process that inhibits or suppresses GPR176 expression or GPR176 function, thereby (1) delaying the onset of GPR176 activity; (2) slowing or stopping the progression, worsening or aggravation of symptoms of GPR176 activity; (3) bringing about relief of symptoms of GPR176 activity; or (4) making it possible to cure symptoms of GPR176 activity.

[0035] In the present invention, examples of inhibitors of GPR176 expression include substances that inhibit the expression of a gene or nucleic acid shown in any of the following (a) to (c): (a) a GPR176 gene as shown in any one of SEQ ID NOs: 2, 4, or 6 in the sequence listing; (b) a nucleic acid comprising a base sequence in which one or several bases are deleted, substituted or added in the GPR176 gene shown in any one of SEQ ID NOs: 2, 4 and 6 in the sequence listing; (c) A nucleic acid that hybridizes under stringent conditions with a base sequence complementary to the GPR176 gene shown in any one of SEQ ID NOs: 2, 4 and 6 in the sequence listing.

[0036] In the present invention, in an embodiment in which the expression of a gene or nucleic acid is inhibited, the gene or nucleic acid (hereinafter sometimes referred to as "target nucleic acid") may be any of the following: the GPR176 gene shown in any of the base sequences set forth in SEQ ID NO: 2, 4, or 6, which has been discovered by the present inventors to be a myofibroblast-specific membrane surface marker molecule and a molecule that promotes fibrosis; a nucleic acid containing a base sequence in which one or several bases have been deleted, substituted, or added in a nucleic acid containing a base sequence in any of SEQ ID NO: 2, 4, or 6 in the sequence listing; or a nucleic acid that hybridizes under stringent conditions with a base sequence complementary to a nucleic acid containing a base sequence in any of SEQ ID NO: 2, 4, or 6 in the sequence listing, and which has a base sequence that encodes a protein represented by the amino acid sequence set forth in SEQ ID NO: 1, or a protein having the same function as said protein. Preferably, the GPR176 gene shown in any of SEQ ID NO: 2, 4, or 6 in the sequence listing.

[0037] In the present invention, the mRNA may be any mRNA encoded by a target nucleic acid or one that encodes a protein encoded by a target nucleic acid, preferably an mRNA encoded by the GPR176 gene.

[0038] The target nucleic acid of the present invention can be obtained as follows. First, mRNA is extracted from human cells or tissues that produce GPR176 protein, such as human myofibroblasts, by a known method. Cells or tissues capable of producing GPR176 protein can be identified by Northern blotting using a nucleic acid having a base sequence encoding GPR176 protein or a part thereof, or Western blotting using an antibody specific to GPR176 protein. In the present invention, the extraction method can be a guanidine thiocyanate hot phenol method, a guanidine thiocyanate-guanidine hydrochloric acid method, or the like, and preferably a guanidine thiocyanate cesium chloride method. In the present invention, purification of mRNA can be performed according to a conventional method, and can be performed by, for example, adsorbing and eluting mRNA extracted by a known method from human cells or tissues that produce GPR176 protein, such as human breast cancer tissue, onto an oligo(dT) cellulose column, purifying it, or fractionating mRNA by sucrose density gradient centrifugation, or the like. Alternatively, commercially available extracted mRNA may be used without extracting mRNA.

[0039] In one embodiment of the present invention, the inhibitor of GPR176 expression is preferably selected from the group consisting of siRNA, antisense and ribozyme.

[0040] The ribozyme of the present invention means an RNA molecule that specifically cleaves other single-stranded RNA molecules by a mechanism similar to that of DNA restriction endonucleases. By appropriately modifying the nucleic acid sequence of RNA using known techniques, a ribozyme that recognizes and cleaves a specific base sequence in a single-stranded RNA can be produced (Science, 239, p. 1412-1416, 1988).

[0041] The siRNA of the present invention refers to double-stranded RNA that suppresses the expression of a target nucleic acid, and means "RNAi agent", "short interfering RNA", "short interfering nucleic acid", "siNA", and is a nucleic acid molecule that can inhibit or down-regulate gene expression or viral replication through sequence-specific RNA interference (RNAi) or gene silencing. It may be composed of RNA alone or may be a fusion of DNA and RNA. For example, siRNA having the RNA sequences shown in SEQ ID NOs: 9 and 10 in the sequence table can be mentioned. The siRNA can be prepared according to a conventional method from the target nucleic acid and information obtained by searching the NCBI database. In designing siRNA oligonucleotides, a sequence with a GC content as close as possible to 50% is selected from the coding region of the mRNA encoded by the target nucleic acid. The GC content is ideally between 45% and 55%. Avoid the region of 50 to 100 nucleotides near the AUG start codon or the region of 50 to 100 nucleotides near the termination codon, and select 19 nucleotides following AA (adenine-adenine), and add dTdT (deoxythymine-deoxythymine) as an overhang to the 3' end of this sense strand 19 nucleotide. The overhang can be selected from RNA oligos or RNA / DNA chimeric oligos. Thymine (TT) or uracil (UU) is usually used as a two-base overhang, but other overhangs can also be used. However, making the siRNA end blunt, making only the 5' end an overhang, or changing the length of the overhang may affect the RNAi effect. The base sequence of the nucleotide should avoid sequences with three or more consecutive guanosines or cytosines, and it is necessary to confirm that there is no homology with any other genes. The antisense strand is the complementary strand of the sense 19 nucleotides, and dTdT is added to the 3' end. Based on the base sequence designed in this way, the sense and antisense strands are synthesized using a DNA / RNA synthesizer. The synthesized sense and antisense strands are purified using a NAP-10 column or similar, concentrated and dried, and then dissolved again in a buffer and heated to anneal them into double-stranded siRNA.In addition to the method of preparing siRNA using a DNA / RNA synthesizer, it is also possible to incorporate the siRNA target sequence of the present invention together with a loop sequence into an expression vector, express it in a cell, and suppress the expression of the target nucleic acid. It is also possible to express the sense strand and the antisense strand of the siRNA target sequence of the present invention separately in a cell, and hybridize them in the cell to form siRNA to suppress the expression of the target nucleic acid. Furthermore, it is also possible to introduce a long dsRNA containing the siRNA target sequence of the present invention into a cell, cleave it in the cell to form siRNA, and suppress the expression of the target nucleic acid.

[0042] Since the siRNA of the present invention inhibits the expression of the target nucleic acid (GPR176 gene), it can be used as a substance that regulates the expression of the target nucleic acid, as a fibrosis inhibitor, and as a pharmaceutical composition for preventing or treating fibrosis diseases. Examples of such siRNA include siRNAs having the RNA sequences shown in SEQ ID NOs: 9 and 10 in the sequence listing.

[0043] The nucleic acid having antisense sequence of the present invention is a nucleic acid having a base sequence that suppresses the expression of target nucleic acid, and is prepared according to a conventional method.First, select the target candidate site of the mRNA encoded by the target nucleic acid, and as the selection method, the mRNA higher-order structure prediction method based on energy calculation (Methods in Enzymol., 180, p. 262, 1989; Ann. Rev. Biophys. Biophys. Chem., 17, p. 167, 1988), the random oligo / RNase H method (Nucleic Acid Res., 25, p. 5010, 1997), the reverse transcriptase method (Nature Biotech, 15, p. 537, 1997), the fluorescent nucleic acid probe method (Nucleic Acid Res., 27, p. 2387, 1999), the FRET method (Biochemistry, 31, p. 12055, 1992) and the like can be used. Next, the sequence of the antisense oligonucleotide is determined from the selected candidate region of the mRNA. At this time, the chain length of the antisense oligonucleotide is generally 15-30 mer, and the antisense oligonucleotide itself is designed not to form a double strand or a self-stem-loop structure, and a sequence with four or more consecutive Gs is avoided because it is likely to interact with proteins, and the "CpG" sequence in the antisense oligonucleotide is avoided because it binds to the receptor of B cells. The structure of the antisense oligonucleotide can be selected from phosphate-linked types (natural type, phosphorothioate type, methylphosphonate type, phosphoramidate type, 2'-O-methyl type) and non-phosphate types (morpholidate type, polyamide nucleic acid). In addition, it is possible to introduce peptides or cholesterol to increase cell permeability, or to give crosslinking ability by introducing alkylating agents or photocrosslinking agents. The antisense oligonucleotide designed in this way is prepared by a DNA synthesizer or the like, and purified by reverse phase HPLC, ion exchange HPLC, gel electrophoresis, ethanol precipitation, etc.

[0044] The nucleic acid having the antisense sequence of the present invention inhibits the expression of the target nucleic acid (GPR176 gene), and therefore can be used as a substance that regulates the expression of the target nucleic acid, as a fibrosis inhibitor, and ultimately as a pharmaceutical composition for preventing or treating fibrotic diseases.

[0045] In one embodiment of the present invention, the pharmaceutical composition of the present invention includes an inhibitor of GPR176 function. The inhibitor of GPR176 function includes a substance that specifically binds to GPR176 protein. In the present invention, the substance that specifically binds to GPR176 protein includes one selected from the group consisting of an antibody, an antibody fragment, and an aptamer.

[0046] In an embodiment in which fibrosis is inhibited by inhibiting the function of a protein encoded by a target nucleic acid, the protein (hereinafter referred to as "target protein") is a protein having an amino acid sequence encoded by a target nucleic acid, including a protein having the amino acid sequence set forth in SEQ ID NO: 1, as well as a protein having an amino acid sequence in which 1 to 10, preferably 1 to 7, and more preferably 1 to 5 amino acids have been substituted, deleted or inserted in the amino acid sequence, and which, like the GPR176 protein shown in the amino acid sequence set forth in SEQ ID NO: 1, is involved in the proliferation mechanism of cancer cells or at least its presence is involved in the fibrosis mechanism.

[0047] In the present invention, the antibody includes, for example, polyclonal antibodies, monoclonal antibodies, chimeric antibodies, and humanized antibodies. Examples of antibodies include full-length antibodies, single-chain molecules, bifunctional molecules, scFvs, diabodies, single domain antibodies (VHHs), chimeric antibodies, and immunoadhesins. "Antibody fragments" include Fv, Fv', Fab, Fab', and F(ab')2 fragments. "Antibody", as it relates to the present invention, means a polypeptide that contains one or more regions that bind to an epitope of an antigen of interest.

[0048] "Antibody fragments" can be obtained by treating antibodies with enzymes, for example, proteases such as papain and pepsin (see Morimoto et al., J. Biochem. Biophys. Methods (1992) 24: 107-17; Brennan et al., Science (1985) 229: 81). Alternatively, they can be produced by genetic recombination based on the amino acid sequence of the antibody fragment.

[0049] Minibodies having a structure obtained by modifying an "antibody fragment" can be constructed using antibody fragments obtained by enzymatic treatment or genetic recombination. Alternatively, a gene encoding the entire minibody can be constructed and introduced into an expression vector, which can then be expressed in a suitable host cell (see, e.g., Co et al., J. Immunol. (1994) 152: 2968-76; Better and Horwitz, Methods Enzymol. (1989) 178: 476-96; Pluckthun and Skerra, Methods Enzymol.(1989) 178: 497-515; Lamoyi, Methods Enzymol. (1986) 121: 652-63; Rousseaux et al., Methods Enzymol. (1986) 121: 663-9; Bird and Walker, Trends Biotechnol. (1991) 9: 132-7).

[0050] An "scFv" is a single-chain polypeptide in which two variable regions are linked, if necessary, via a linker or the like. The two variable regions contained in an scFv are usually one heavy chain variable region (VH) and one light chain variable region (VL), but may be two VHs or two VLs. In general, an scFv polypeptide contains a linker between the VH and VL regions, thereby forming a pair of VH and VL necessary for antigen binding. In general, in order to form a pair between VH and VL within the same molecule, the linker linking VH and VL is generally a peptide linker having a length of 10 amino acids or more. However, the linker of the scFV in the present invention is not limited to such a peptide linker as long as it does not interfere with the formation of the scFv. For a general overview of scFv, see Pluckthun, The Pharmacology of Monoclonal Antibody, Vol. 113 (Rosenburg and Moore ed., Springer Verlag, NY, pp. 269-315 (1994)).

[0051] In the present invention, an aptamer is a nucleic acid or peptide molecule that binds to a specific target molecule. Aptamers are usually created by selecting them from a large random sequence pool, but natural aptamers are also present in riboswitches. Aptamers can be used as macromolecular drugs for both basic research and clinical purposes. Aptamers can be combined with ribozymes that self-cleave in the presence of their target molecule. More specifically, aptamers can be classified as nucleic acid aptamers, such as DNA or RNA aptamers, or peptide aptamers. The former are usually composed of (usually short) strands of oligonucleotides, while the latter are preferably composed of short variable peptide domains attached at both ends to a protein scaffold. Nucleic acid aptamers are in principle nucleic acid species engineered through repeated rounds of in vitro selection or equivalent SELEX (systematic evolution of ligands by exponential enrichment) to bind to a variety of molecular targets including small molecules, proteins, nucleic acids, and even cells, tissues, and the organisms themselves. Peptide aptamers are usually peptides or proteins designed to interfere with other protein interactions within cells. They consist of a variable peptide loop attached to both ends of a protein scaffold. This double structural constraint greatly increases the binding affinity of peptide aptamers to levels comparable to those of antibodies (nanomolar range). The variable peptide loop typically contains 10-20 amino acids, and the scaffold can be any protein with good solubility properties. Currently, the bacterial protein thioredoxin-A is the most commonly used scaffold protein, which in the wild-type protein is a variable peptide loop inserted into the redox active site, which is a -Cys-Gly-Pro-Cys-loop, and the two cysteines in the side chains can form disulfide bridges.A selection of peptide aptamers can be made using different systems, the most widely used currently being the yeast two-hybrid system.

[0052] Aptamers offer utility for biotechnology and therapeutic applications because they offer molecular recognition properties comparable to commonly used biomolecules, particularly antibodies. In addition to their differential recognition, aptamers offer advantages over antibodies because they can be fully engineered in vitro, are easily produced by chemical synthesis, have desirable storage properties, and induce little or no immunogenicity in therapeutic applications. Unmodified aptamers are primarily subject to nuclease degradation and clearance from the body by the kidney as a result of the inherently low molecular weight of aptamers. Number They are rapidly cleared from the bloodstream, with half-lives of minutes to hours. Applications of unmodified aptamers are currently focused on treating transient conditions such as blood clotting, or treating organs such as the eye where localized delivery is possible. This rapid clearance is advantageous for applications such as in vivo diagnostic imaging. Several modifications, such as 2'-fluorine substituted pyrimidines, polyethylene glycol (PEG) linkages, fusions with albumin or other half-life extending proteins, etc., are available that can increase the half-life of aptamers to days or even weeks.

[0053] Briefly, a GPR176 inhibitor may be, for example, a substance that suppresses the expression of GPR176 at the mRNA level or protein level, or it may be an antagonist to GPR176, or it may be a substance that inhibits the activity of GPR176.

[0054] Antagonists for GPR176 include substances that do not activate GPR176, and substances that inhibit the binding of ligands to GPR176, among substances that specifically bind to GPR176.

[0055] Examples of substances that specifically bind to GPR176 include antibodies, antibody fragments, aptamers, etc. Examples of antibody fragments include Fv, Fab, scFv, etc. The above-mentioned antibodies or antibody fragments may be polyclonal or monoclonal. Examples of aptamers include nucleic acid aptamers, peptide aptamers, etc.

[0056] The applications of antibodies, antibody fragments, and aptamers, which are specific binding substances for GPR176, include the following: Drug-loaded antibodies or GPR176-neutralizing antibodies can be used to treat fibrosis. Fluorescently or radiolabeled antibodies can be used to detect and diagnose myofibroblasts and fibrotic sites. Furthermore, antibody-drug conjugate technology can be used to specifically kill myofibroblasts that express GPR176 and can cause fibrosis.

[0057] As used herein, "treatment" refers to a method or process intended to (1) delay the onset of a fibrotic disease or condition; (2) slow or halt the progression, worsening or deterioration of the symptoms of a fibrotic disease or condition; (3) bring about the amelioration of the symptoms of a fibrotic disease or condition; or (4) cure a fibrotic disease or condition. Treatment may be administered prior to the onset of the disease or condition as a preventative measure, or alternatively, treatment may be administered after initiation of the disease.

[0058] As used herein, "prevention" means preventing the onset of a fibrotic disease or condition.

[0059] In the present invention, the pharmaceutical composition generally means a drug for treating or preventing a disease, or for testing or diagnosing a disease.

[0060] The pharmaceutical composition of the present invention can be formulated by a method known to those skilled in the art. For example, it can be used parenterally in the form of a sterile solution or suspension injection with water or other pharma- ceutically acceptable liquid. For example, it can be formulated by appropriately combining with a pharmacologically acceptable carrier or medium, specifically, sterile water, physiological saline, vegetable oil, emulsifier, suspending agent, surfactant, stabilizer, flavoring agent, excipient, vehicle, preservative, binder, etc., and mixing in a unit dose form required for generally accepted pharmaceutical practice. The amount of active ingredient in these preparations is set so that an appropriate volume within the indicated range is obtained.

[0061] Sterile compositions for injection can be formulated according to conventional preparations using vehicles such as distilled water for injection.

[0062] Examples of the aqueous solution for injection include isotonic solutions containing physiological saline, glucose, and other auxiliary agents (e.g., D-sorbitol, D-mannose, D-mannitol, sodium chloride). Appropriate solubilizing agents such as alcohol (e.g., ethanol), polyalcohol (e.g., propylene glycol, polyethylene glycol), and nonionic surfactants (e.g., polysorbate 80(TM), HCO-50, etc.) may be used in combination.

[0063] The oily liquid may be sesame oil or soybean oil, and may be used in combination with benzyl benzoate and / or benzyl alcohol as a solubilizing agent. It may also be combined with a buffer (e.g., phosphate buffer and sodium acetate buffer), a soothing agent (e.g., procaine hydrochloride), a stabilizer (e.g., benzyl alcohol and phenol), and an antioxidant. The prepared injection solution is usually filled into a suitable ampule.

[0064] The pharmaceutical composition of the present invention is preferably administered parenterally. For example, it can be an injection type, a nasal administration type, a pulmonary administration type, or a transdermal administration type. For example, it can be administered systemically or locally by intravenous injection, intramuscular injection, intraperitoneal injection, subcutaneous injection, etc.

[0065] The administration method can be appropriately selected depending on the age and symptoms of the patient. The dosage of the pharmaceutical composition containing the polypeptide can be set, for example, in the range of 0.0001 mg to 1000 mg per kg of body weight per administration. Alternatively, for example, the dosage can be set to 0.001 to 100,000 mg per patient, but the present invention is not necessarily limited to these numerical values. The dosage and administration method vary depending on the patient's body weight, age, symptoms, etc., but a person skilled in the art can set an appropriate dosage and administration method taking these conditions into consideration.

[0066] In another aspect, the present invention provides a method for preventing or treating a fibrotic disease, comprising the steps of: G The present invention relates to a method comprising administering an effective amount of an inhibitor of protein-coupled receptor 176 (GPR176), specifically an inhibitor of GPR176 expression or an inhibitor of GPR176 function, to a patient in need of such treatment.

[0067] Further, in another aspect, the present invention relates to a method for preventing or treating a fibrotic disease, comprising administering to said patient a composition comprising the composition of the present invention. G The present invention relates to inhibitors of protein-coupled receptor 176 (GPR176), in particular inhibitors of GPR176 expression or inhibitors of GPR176 function. As a further aspect, the present invention relates to a method for producing a medicament for preventing or treating a fibrotic disease, comprising administering to said patient a compound of the present invention. G The present invention relates to the use of inhibitors of protein-coupled receptor 176 (GPR176), in particular inhibitors of GPR176 expression or inhibitors of GPR176 function.

[0068] <Nucleic acid molecules, etc.> In another embodiment, the present invention comprises: (a) a GPR176 gene as shown in any one of SEQ ID NOs: 2, 4, or 6 in the sequence listing; (b) a nucleic acid comprising a base sequence in which one or several bases are deleted, substituted or added in the GPR176 gene shown in any one of SEQ ID NOs: 2, 4 and 6 in the sequence listing; (c) a nucleic acid that hybridizes under stringent conditions with a base sequence complementary to the GPR176 gene shown in any one of SEQ ID NOs: 2, 4, and 6 in the sequence listing; The present invention provides a nucleic acid molecule selected from the group consisting of siRNA, antisense and ribozyme, which inhibits the expression of a target nucleic acid (GPR176 gene). As described above, the nucleic acid molecule selected from the group consisting of siRNA, antisense and ribozyme of the present invention inhibits the expression of a target nucleic acid (GPR176 gene), and therefore can be used as a substance that regulates the expression of a target nucleic acid, as a fibrosis inhibitor, and ultimately as a pharmaceutical composition for preventing or treating fibrosis diseases.

[0069] Preferably, the nucleic acid molecule of the present invention is introduced into a gene therapy vector. Although gene therapy often refers to a treatment for genetic disorders, in the present invention, it means a treatment for preventing or treating fibrotic diseases or for suppressing the progression of fibrotic diseases. In the present invention, gene therapy may include inserting a copy of a gene in vivo into the cells of a patient with a fibrotic disease. Gene therapy may also include silencing a gene. Genetic recombination may also be used in ex vivo gene therapy. For example, human stem cells, immune cells or cancer cells may be genetically modified for various applications. The cells may be modified to induce differentiation, transdifferentiation or reprogramming. The cells may also be modified to serve as a vehicle for delivering therapeutic proteins.

[0070] The present invention further provides a cell comprising the vector of the present invention. The cell of the present invention can be used in cell therapy for preventing or treating a fibrotic disease, or inhibiting the progression of a fibrotic disease.

[0071] <Screening method> In another embodiment, the present invention provides a method for screening for a GPR176 inhibitor by confirming that expression of the gene or nucleic acid is inhibited, the method comprising using a gene or nucleic acid represented by any one of the following (a) to (c), or a cell into which the gene or nucleic acid has been introduced: (a) a GPR176 gene as shown in any one of SEQ ID NOs: 2, 4, 6, or 8 in the sequence listing; (b) a nucleic acid comprising a base sequence in which one or several bases are deleted, substituted or added in the GPR176 gene shown in any one of SEQ ID NOs: 2, 4, 6 and 8 in the sequence listing; (c) A nucleic acid that hybridizes under stringent conditions with a base sequence complementary to the GPR176 gene shown in any one of SEQ ID NOs: 2, 4, 6 and 8 in the sequence listing. SEQ ID NOs: 2, 4 and 6 in the sequence listing are the base sequences of the human GPR176 gene, and SEQ ID NO: 8 is the base sequence of the mouse GPR gene. In the method of screening for a GPR176 inhibitor of the present invention, either the human GPR176 gene or the mouse GPR176 gene can be used. The human GPR176 gene is preferred.

[0072] The isolated gene or nucleic acid can be incorporated into a suitable vector to transform eukaryotic and prokaryotic host cells. Furthermore, by introducing a suitable promoter and a sequence involved in expression into these vectors, it is possible to express the mRNA or protein encoded by the target nucleic acid in each host cell. In the present invention, a plasmid or a phage vector such as a lambda system can be used as the vector, into which the target nucleic acid is inserted. The plasmid may be either a self-replicating plasmid containing a transcription promoter region or a plasmid that can be incorporated into the chromosome of an animal cell. As an expression vector for vertebrate cells that can be used in the present invention, one having a promoter, an RNA splice site, a polyadenylation site, a transcription termination sequence, etc., usually located upstream of the gene to be expressed, may be used, and this may further have a replication origin if necessary. Examples of such expression vectors include, but are not limited to, pSV2dhfr having an SV40 early promoter (Mol. Cell. Biol., 1, p.854-864, 1981), pEF-BOS having a human elongation factor promoter (Nucleic Acids Res., 18, p.5322, 1990), and pCEP4 (Invitrogen) having a cytomegalovirus promoter. For example, eukaryotic host cells include cells of vertebrates, insects, yeast, etc., and examples of vertebrate cells include, but are not limited to, monkey cells such as COS cells (Cell, 23, p.175-182, 1981), dihydrofolate reductase-deficient strains of Chinese hamster ovary cells (CHO) (Proc. Natl. Acad. Sci. USA, 77, p.4216-4220, 1980), human embryonic kidney-derived HEK293 cells, and 293-EBNA cells (Invitrogen) in which the EBNA-1 gene of Epstein-Barr virus has been introduced into the HEK293 cells.

[0073] Inhibition of gene or nucleic acid expression can typically be confirmed using real-time polymerase chain reaction (PCR) or DNA microarray method.

[0074] More specifically, the screening method of the present invention comprises: (1) preparing a candidate compound; (2) (a) a GPR176 gene as shown in any one of SEQ ID NOs: 2, 4, 6, or 8 in the sequence listing; (b) a nucleic acid comprising a base sequence in which one or several bases are deleted, substituted or added in the GPR176 gene shown in any one of SEQ ID NOs: 2, 4, 6 and 8 in the sequence listing; (c) contacting the candidate compound with a cell having a gene or a nucleic acid that hybridizes under stringent conditions to a base sequence complementary to the GPR176 gene shown in any one of SEQ ID NOs: 2, 4, 6, and 8 in the sequence listing; (3) A method for screening for a GPR176 inhibitor, comprising determining whether or not the candidate compound suppresses the expression of the gene or nucleic acid.

[0075] The following various methods can be used to select a line transfected with the target nucleic acid from the cells obtained as described above, including a method of directly confirming the presence of the nucleic acid and a method of selecting a line expressing mRNA. In step (3), "determining whether the candidate compound suppresses the expression of the gene or nucleic acid" can be performed using, for example, the method described in Foster et al., 2019, Cell 179, 895-908.

[0076] Screening methods using synthetic oligonucleotide probes An oligonucleotide corresponding to the target nucleic acid is synthesized. This can be either a nucleotide sequence derived using codon usage, or a multiple nucleotide sequence combining possible nucleotide sequences, and in the latter case, inosine can be included to reduce the number of types. This is used as a probe (labeled with 32P or 33P) to hybridize with a nitrocellulose filter on which the DNA of the transformant has been denatured and fixed, and the resulting positive strains are screened and selected.

[0077] Screening methods using probes generated by polymerase chain reaction (PCR) Sense and antisense primer oligonucleotides corresponding to a part of the target nucleic acid are synthesized, and these are combined to perform PCR (Science, 239, p. 487-491, 1988) to amplify the target nucleic acid. The template DNA used here can be cDNA synthesized by reverse transcription from mRNA of cells that produce the drug discovery target molecule, or genomic DNA. The DNA fragments prepared in this way are labeled with 32P or 33P, and used as probes to perform colony hybridization or plaque hybridization to select strains that have the desired target nucleic acid.

[0078] In yet another embodiment, the present invention relates to a method for screening for a substance that inhibits the function of GPR176 protein, characterized in that it uses a GPR176 protein having an amino acid sequence as set forth in any one of SEQ ID NOs: 1, 3, 5 or 7 in the sequence listing, or a mutant GPR176 protein having a substitution, deletion or addition of one or several amino acid residues in the GPR176 protein having an amino acid sequence as set forth in any one of SEQ ID NOs: 1, 3, 5 or 7 in the sequence listing, and the mutant GPR176 protein has activity equivalent to that of the GPR176 protein, more specifically, (1) preparing a candidate compound; (2) contacting the candidate compound with a GPR176 protein having an amino acid sequence shown in any one of SEQ ID NOs: 1, 3, 5, or 7 in the sequence listing, or a mutant GPR176 protein having one or more amino acid residues substituted, deleted, or added in the GPR176 protein and having an activity equivalent to that of the GPR176 protein, or a cell expressing the GPR176 protein or the mutant GPR176 protein; (3) The present invention provides a method for screening a substance that inhibits the function of GPR176 protein, which comprises determining whether or not the candidate compound inhibits the function of the GPR176 protein or the mutant GPR176 protein. SEQ ID NOs: 1, 3 and 5 in the sequence listing are the amino acid sequences of human GPR176 protein, and SEQ ID NO: 7 is the amino acid sequence of mouse GPR protein. In the method of screening for a GPR176 inhibitor of the present invention, either human GPR176 protein or mouse GPR176 protein can be used. Human GPR176 protein is preferred.

[0079] By expressing a target protein by fusing it in frame with a marker protein, it becomes possible to confirm the expression, confirm the intracellular localization, purify it, and the like. Examples of marker proteins include FLAG epitope, hexa-histidine tag, hemagglutinin tag, myc epitope, and the like. In addition, by inserting a specific amino acid sequence recognized by a protease such as enterokinase, factor Xa, or thrombin between the amino acid sequences of the marker protein and the target protein, it is possible to cleave and remove the marker protein portion with these proteases. For example, there is a report of linking a muscarinic acetylcholine receptor and a hexa-histidine tag with a thrombin recognition sequence (J. Biochem., 120, p. 1232-1238, 1996). Transformed cells in which a base sequence encoding these marker proteins and a target nucleic acid are fused in frame with each other into a vector can be used for screening a substance that regulates the function of the target nucleic acid or the target protein.

[0080] More specifically, the screening method of the present invention provides a method for screening for a preventive or therapeutic agent for a fibrotic disease, comprising the steps of culturing myofibroblasts in the presence of a candidate compound, quantifying the expression level of GPR176 gene mRNA or GPR176 protein in the cultured myofibroblasts, and determining that the candidate compound is a preventive or therapeutic agent for a fibrotic disease if the quantified expression level of GPR176 gene mRNA or GPR176 protein is reduced compared to a control.

[0081] As the candidate compound, for example, a compound library or the like can be used. As the control, for example, myofibroblasts cultured in the absence of the candidate compound can be used. The mRNA of the GPR176 gene can be quantified, for example, by microarray analysis or real-time RT-PCR. The expression level of the GPR176 protein can be quantified, for example, by analysis using a protein chip or by Western blotting.

[0082] <Biomarkers, etc.> In another aspect, the present invention provides a method for determining the severity of a fibrotic disease, comprising the steps of: (a10) measuring the amount of GPR176 in myofibroblasts of the subject (test biomarker amount); (b10) comparing the amount of the test biomarker with the amount of GPR176 in myofibroblasts of a healthy subject (a control biomarker amount); and (c10) A method for determining that a subject has a fibrotic disease that becomes severe when the amount of a test biomarker is greater than the amount of a control biomarker. In this regard, in yet another aspect, the present invention provides a biomarker that is GPR176 in myofibroblasts, which can determine the severity of fibrotic diseases. Furthermore, the present invention provides the use of GPR176 as a biomarker that can determine the severity of fibrotic diseases.

[0083] The present inventors have found that GPR176 is a myofibroblast-specific membrane surface marker molecule, a molecule that promotes fibrosis, and is associated with fibrotic diseases, particularly severe fibrotic diseases. By using the method, biomarker, and GPR176 of the present invention, the severity of a subject can be determined in advance, making it possible to predict patients whose fibrotic diseases will become severe, which is beneficial for preventing fibrotic diseases.

[0084] The amount of GPR176 in myofibroblasts can be measured by immunological methods if an antibody against GPR176 is available. For example, it can be measured by ELISA method well known to those skilled in the art. Detection of mRNA for GPR176 can be performed, for example, by RNA scope method (Advanced Cell Diagnostics), which is a type of highly sensitive in situ hybridization. In the RNA scope method, if the mRNA of a target molecule is expressed, it can be detected in a dot shape by using a probe specific to the molecule. RNA can also be collected from myofibroblasts and measured by real-time RT-PCR method.

[0085] The subject's myofibroblasts are collected by biopsy and the amount of GPR176 is measured.

[0086] <Myofibroblast detection kit> In an embodiment, the present invention provides a kit for detecting myofibroblasts, comprising a primer set for amplifying GPR176 cDNA, a probe that specifically hybridizes to GPR176 mRNA, or a substance that specifically binds to GPR176 protein.

[0087] As described later in the Examples, the inventors have clarified that GPR176 is hardly expressed in the heart, liver, and kidney of a living body under normal conditions, and that its expression increases significantly only when the respective organs become fibrotic. They have also clarified that the expression of GPR176 is specific to myofibroblasts, which carry out fibrosis. Therefore, GPR176 is a novel myofibroblast-specific marker protein.

[0088] In the kit of this embodiment, the primer set is not particularly limited as long as it can amplify the cDNA of the GPR176 gene of the animal species to be diagnosed. Furthermore, the probe that specifically hybridizes to the mRNA of GPR176 is not particularly limited as long as it specifically hybridizes to the mRNA of the GPR176 gene. The probe may be immobilized on a carrier to form a DNA microarray or the like. Furthermore, the specific binding substance is the same as that described above. The specific binding substance may be immobilized on a carrier to form a protein chip or the like.

[0089] Proteins such as α-SMA and periostin have been used as markers for myofibroblasts, the cells that initiate fibrosis. However, these are all intracellular proteins. In other words, no cell membrane proteins specifically expressed in myofibroblasts were known.

[0090] In contrast, as described later in the Examples, GPR176 is a cell membrane protein that is not expressed in cells of origin and whose expression increases upon differentiation into myofibroblasts. Because GPR176 is a cell membrane protein, it is possible to invasively or non-invasively visualize myofibroblasts, for example, by labeling an antibody specific to GPR176 with a fluorescent or radioisotope.

[0091] <Other embodiments> Since GPR176 is a cell membrane protein, it is possible to deliver drugs specifically to myofibroblasts, for example, by using an antibody specific to GPR176.

[0092] All references cited in this specification, including publications, patent documents, and the like, are hereby incorporated by reference in this specification to the same extent as if each was individually specifically incorporated by reference and specifically set forth in its entirety.

[0093] The present invention will be described in more detail below with reference to examples. However, it should be noted that these do not limit the scope of the present invention and are merely illustrative. EXAMPLES

[0094] Example 1 Microarray analysis using myocardial infarction model mice We used microarray analysis to search for cell membrane proteins involved in fibrosis. Specifically, we performed microarray analysis using cardiac tissues excised from myocardial infarction model mice in which the left anterior descending coronary artery of the mouse heart was ligated with suture, and cardiac tissues excised from sham-treated mice as controls, to search for cell membrane proteins whose expression levels were significantly increased only in the myocardial infarction treatment group. Furthermore, we selected proteins that were significantly expressed in myofibroblasts. As a result, we found GPR176, an orphan receptor whose function had previously been unknown, as a cell membrane protein involved in fibrosis.

[0095] Example 2 Expression of GPR176 in a mouse model of myocardial infarction The expression of GPR176 was confirmed using myocardial infarction model mice. Specifically, using the same myocardial infarction model mice (n = 5 to 6) as in Example 1, the expression level of GPR176 in the heart tissue immediately after the myocardial infarction treatment (after day 0), and 3, 7, and 28 days later was quantified by real-time RT-PCR. As a control, the expression level of GPR176 mRNA in the heart tissue of sham-treated mice (n = 3 to 4) immediately after the treatment (after day 0), and 3, 7, and 28 days later was quantified by real-time RT-PCR.

[0096] 1A is a graph showing the results of measuring the mRNA expression level of GPR176 in cardiac tissues of myocardial infarction model mice and control mice. As a result, it was revealed that GPR176 is not expressed in normal hearts, and the expression level increases significantly, peaking on the 7th day after myocardial infarction treatment.

[0097] In addition, using the same samples as above, the expression level of α-SMA, known as a marker of myofibroblasts responsible for organ fibrosis, was measured. Figure 1B is a graph showing the results of measuring the expression level of α-SMA in the cardiac tissue of myocardial infarction model mice and control mice. As a result, it was revealed that the transition of the expression level of α-SMA was very similar to the transition of the expression level of GPR176.

[0098] These results support the involvement of GPR176 in fibrosis.

[0099] Example 3 Expression of GPR176 in myofibroblasts We investigated which cells express GPR176. Since there is no antibody capable of immunostaining for GPR176, we used a method called RNA scope (Advanced Cell Diagnostics) to detect GPR176 mRNA on mouse heart sections. RNA scope is a type of ultrasensitive in situ hybridization method, and if the mRNA of the target molecule is expressed, it is detected as a dot by using a probe specific to that molecule (Wang, F. et al., J. Mol. Diagnostics 14, 22-29 (2012)). First, we examined the expression of GPR176 mRNA in the sham-treated heart, but no signal was detected (Figure 2A). In other words, it was revealed that GPR176 is not expressed in cardiomyocytes, resident fibroblasts, endothelial cells, etc. in the heart at steady state. On the other hand, when we examined the expression of GPR176 mRNA in the heart on the 7th day after infarction treatment, when the expression level of GPR176 reaches its peak, we were able to detect many positive signals in the interstitium of the tissue (Figure 2A right, black arrow). After myocardial infarction, various blood cells such as macrophages, neutrophils, and T cells, as well as myofibroblasts differentiated from various cells, are newly present in the cardiac interstitium (Davis, J. & Molkentin, JD,. J. Mol. Cell. Cardiol. 70, 9-18 (2014); Liehn, EA, Postea, O., Curaj, A. & Marx, N., J. Am. Coll. Cardiol. 58, 2357-2362 (2011)). Therefore, it is thought that GPR176 is expressed in blood cells or myofibroblasts present in the cardiac interstitium after myocardial infarction.

[0100] We therefore isolated cell fractions containing hematopoietic cells or myofibroblasts from the hearts of mice after myocardial infarction using the expression of CD45 (a membrane surface marker molecule for hematopoietic cells) or PDGFRα (a membrane surface marker molecule for all fibroblasts, including myofibroblasts) as an indicator, and compared the expression levels of GPR176 in these cell groups. Specifically, the hearts were digested with collagenase solution 3 days after infarction to isolate cells, and then hematopoietic cells [CD45(+)PDGFR-α(-) cells] and cell fractions containing myofibroblasts [CD45(-)PDGFR-α(+) cells] were collected using FACS AriaIII (Takeda, N. et al., J. Clin. Invest. 120, 254-265 (2010).) (Figure 2B). First, we used a dead cell dye and SSC-A to select live cells, then gated with FSC-H and FSC-W and SSC-H and SSC-W to exclude doublet cells. CD45(-)PDGFR-α(+) cells (fibroblasts including myofibroblasts) and CD45(+)PDGFR-α(-) cells (hemocytes) were separately collected, and RNA was extracted from each cell fraction. We used real-time RT-PCR to examine whether the cell fractions collected in this way were of high purity. When we examined the expression of CD68, a macrophage marker, we found that CD68 (Cd68) was expressed only in the hematopoietic cell (Hem) fraction (Figure 2C). On the other hand, the expression of α-SMA (Acta2), a marker molecule for myofibroblasts, was high in the cell fraction containing myofibroblasts (Myo) [CD45(-)PDGFR-α(+) cells] (Figure 2C). Furthermore, Col1a1 (Col1a1) expression was high in the fraction containing myofibroblasts [CD45(-)PDGFR-α(+) cells] (Figure 2C). These results confirmed that sorting was performed properly. Furthermore, when the expression level of GPR176 in each fraction was measured, it was found that GPR176 was hardly expressed in blood cells (Hem), but was strongly expressed in the cell fraction containing myofibroblasts (Myo) (Figure 2D).However, in recent years, it has been reported that the expression level of PDGFRα, a surface marker of all fibroblasts, decreases with differentiation into myofibroblasts (Kanisicak, O. et al., Nat. Commun. 7, 1-14 (2016)), and it was considered that PDGFRα-positive cells may be a subpopulation of myofibroblasts. Therefore, we performed the separation of myofibroblast fractions by negative sorting of CD45(-) and CD31(-), which is used to separate fibroblast fractions including myofibroblasts (Kanisicak, O. et al., Nat. Commun. 7, 1-14 (2016)), and re-examined the results (Figure 2E). Cells were isolated by enzyme treatment, cultured overnight, and non-adherent cells were removed. Then, CD45(-)CD31(-) cells (fibroblasts including myofibroblasts: Myo) and CD45(+) cells (hemocytes: Hem) were separated using MACS, and RNA was extracted from each cell. As in the previous experiment, the expression of Cd68, Acta2, and Col1a1 was examined using real-time RT-PCR, and it was confirmed that each cell fraction was properly separated (Figure 2F). Then, the expression level of GPR176 in each fraction was measured, and it was confirmed that GPR176 was highly expressed in myofibroblasts [CD45(-)CD31(-) cells] (Figure 2G). Overall, Figure 2 shows that GPR176 is highly expressed in myofibroblasts.

[0101] Example 4 Comparison of GPR176 and α-SMA Using mouse heart sections, we simultaneously performed in situ hybridization to detect GPR176 mRNA and immunostaining with α-SMA antibody (ThermoFisher Scientific), a marker molecule for myofibroblasts.

[0102] Figures 3A to 3C are fluorescent micrographs showing the results of the study. The scale bar is 50 μm. Figure 3A is a photograph showing the results of detecting GPR176 mRNA, Figure 3B is a photograph showing the results of detecting α-SMA, and Figure 3C is a photograph merging Figures 3A and B. In Figures 3A to 3C, the white arrow indicates the position where α-SMA was detected, the black arrow indicates the position where GPR176 mRNA was detected, and "bv" indicates blood vessels.

[0103] As a result, GPR176 mRNA signals were observed in α-SMA-positive myofibroblasts. While α-SMA is a marker molecule for myofibroblasts, it is also known to be highly expressed in vascular smooth muscle cells. In fact, as shown in Figures 3A-C, when observed in a field that included both myofibroblasts and vascular smooth muscle cells, the vascular smooth muscle cells arranged in a ring shape around the blood vessels expressed extremely strong α-SMA, and the signal intensity was stronger than that in myofibroblasts.

[0104] Interestingly, almost no GPR176 mRNA signal was observed in α-SMA-positive vascular smooth muscle cells. Therefore, unlike α-SMA, GPR176 is not expressed in vascular smooth muscle cells, but is specifically expressed only in myofibroblasts. This indicates that GPR176 is a truly myofibroblast-specific marker molecule that is superior to α-SMA as a marker molecule for myofibroblasts.

[0105] Example 5 Effect of GPR176 deficiency on collagen accumulation after myocardial infarction We generated GPR176 knockout mice and examined the effect of GPR176 deficiency on collagen accumulation after myocardial infarction. GPR176 knockout mice showed no significant phenotypic changes compared to wild-type control mice under normal conditions. Furthermore, GPR176 knockout mice showed no difference in cardiac function under normal conditions compared to wild-type control mice.

[0106] Next, GPR176 knockout mice (n = 6) and wild-type control mice (n = 6) were subjected to myocardial infarction treatment similar to that described in Example 2, and the hearts were removed 28 days after the myocardial infarction treatment, and the degree of cardiac fibrosis in each group was evaluated by staining with picrosirius red, which stains collagen.

[0107] Figure 4A is a photograph showing the results of picrosirius red staining of cardiac tissue sections from wild-type mice (WT) and GPR176 knockout mice (GPR176 KO). Figure 4B is a graph that quantifies the results of Figure 4A. As a result, it was revealed that fibrosis after myocardial infarction treatment was significantly reduced in GPR176 knockout mice compared to control mice.

[0108] These results indicate that GPR176 is a protein that promotes fibrosis, and that neutralizing antibodies or inhibitors against GPR176 could be new anti-fibrotic drugs.

[0109] Example 6 Effects of GPR176 deficiency on cardiac function after myocardial infarction Fibrosis reduces cardiac function. For example, it has been reported that cardiac function after myocardial infarction in periostin KO mice improves when fibrosis is suppressed (Oka, T. et al., Circ. Res. 101, 313-321 (2007)). Since fibrosis after infarction was suppressed in GPR176KO mice, we investigated whether cardiac function improved with the suppression of fibrosis in GPR176KO mice. Cardiac function was morphologically measured by echocardiography in the hearts of wild-type (WT) and GPR176KO mice 28 days after infarction. As a result, the left ventricular systolic diameter (LVIDs), left ventricular ejection fraction (EF), and left ventricular fractional shortening (FS) were significantly improved in GPR176KO mice compared with WT mice (Figure 5A). In correlation with these results, we also measured the heart weight (HW / BW) and lung weight (LW / BW) after infarction and found that the weight increase after infarction was significantly reduced in GPR176KO mice compared to WT mice (Figure 5B). These results demonstrated that GPR176 is a molecule that promotes fibrosis and deteriorates cardiac function after myocardial infarction.

[0110] Example 7 GPR176 deficiency suppresses the expression of fibrosis-related factors after myocardial infarction Since GPR176 promoted fibrosis in in vitro experiments, we created GPR176KO mice to examine whether GPR176 is involved in fibrosis at the individual level. First, we measured the expression levels of fibrosis-related factors in the hearts of wild-type (WT: control) mice and GPR176KO mice 7 days after infarction, when GPR176 expression is at its maximum. Measurements were performed by real-time RT-PCR using total RNA extracted from the sham-treated ventricle (Sh) and the infarcted (In) or infarcted area (Re) of the infarcted heart. As a result, it was confirmed that the expression levels of the profibrotic factors CTGF (Ctgf), fibronectin (Fn1), and periostin (Postn) were significantly increased by infarction in both WT and KO mice (Figure 6A). However, the induction of their expression was significantly attenuated in GPR176KO mice compared to WT mice (Figure 6A). As mentioned above, myofibroblasts not only perform fibrosis, but also produce humoral factors and other substances that affect the hypertrophy of cardiomyocytes after myocardial infarction or during cardiac hypertrophy caused by hypertension. Therefore, we investigated the effect of GPR176 deficiency in myofibroblasts on the expression of these humoral factors and on the hypertrophy of cardiomyocytes after infarction. Specifically, the expression levels of cardiac hypertrophy marker molecules ANP (Nppa) and BNP (Nppb) and the cardiac hypertrophy-promoting factor IGF-1 (Igf1) were measured in the hearts 7 days after infarction. As a result, the expression levels of all of these markers were significantly increased by infarction, and the increase in expression was significantly attenuated in GPR176KO mice (Figure 6B). From these results, it is thought that the deficiency of GPR176 suppresses IGF-1 production from myofibroblasts and suppresses the hypertrophy of cardiomyocytes. From these results, it is thought that GPR176 may promote fibrosis through the induction of fibrosis-related factors, as well as promote cardiac hypertrophy after myocardial infarction, thereby worsening the pathology.

[0111] Example 8 In vivo studies Since the expression of GPR176 in myofibroblasts is thought to promote fibrosis in vivo, we investigated whether the expression of fibrosis-related factors was actually decreased in myofibroblasts from GPR176 knockout mice. Cells were isolated from the hearts of two wild-type (WT) and two GPR176 knockout mice on the third day after myocardial infarction treatment by collagenase treatment, and immediately stained with antibodies (Biolegend) against CD45, a marker molecule for blood cells, and Thy1.2, a marker molecule for all fibroblasts. Next, the CD45(-)Thy1.2(+) cell fraction, including myofibroblasts, was sorted using a cell sorter (model "FACSAria", BD Biosciences).

[0112] 7A and B are graphs showing the sorting of CD45(-)Thy1.2(+) cell fractions from wild-type mice and GPR176 knockout mice.

[0113] Next, we compared the expression levels of fibrosis-related factors in CD45(-)Thy1.2(+) cell fractions collected from wild-type and GPR176 knockout mice. The expression levels were measured by real-time RT-PCR. The "Viability Dye" used to determine cell death was specifically Fixable viability dye eFluor780, obtained from eBiosciences.

[0114] FIG. 8 is a graph showing the results of measuring the expression levels of fibrosis-associated factors. As a result, the expression levels of fibrosis-related factors such as α-SMA (Acta2), Col1a1 (Col1a1), CTGF (Ctgf), and periostin (Postn) were generally decreased in GPR176 knockout mice, suggesting that GPR176 expressed by myofibroblasts may promote the expression of fibrosis-related factors after myocardial infarction.

[0115] Example 9 Myofibroblast-specific deficiency of GPR176 suppresses expression of fibrosis-related factors after myocardial infarction Example 1 - 8In this study, we demonstrated that GPR176 is specifically expressed in myofibroblasts and promotes fibrosis after myocardial infarction. To support these results, we crossed Postn-cre mice18, which express Cre recombinase specifically in myofibroblasts and are often used in cardiac myofibroblast research, with GPR176flox / flox mice to generate mice lacking GPR176 specifically in myofibroblasts, Postn-cre; GPR176flox / flox mice (Figure 9A). We then examined whether fibrosis after myocardial infarction was suppressed in these mice. We used Postn+ / +;GPR176flox / flox mice as control (Ctrl) mice (hereafter, Ctrl mice) and Postn+ / cre;GPR176flox / flox mice as GPR176 conditional knockout (cKO) mice (hereafter, GPR176cKO mice) for the experiment.

[0116] First, we measured the expression of fibrosis-related factors in the hearts of Ctrl mice and GPR176cKO mice 7 days after infarction, in the same manner as in the study using GPR176-deficient mice. The measurement was performed by real-time RT-PCR using total RNA extracted from the sham-treated ventricle (Sh) and the infarcted (In) or infarcted area (Re) of the infarcted heart. As a result, the expression levels of the fibrosis-promoting factors CTGF (Ctgf), fibronectin (Fn1), and periostin (Postn) were significantly increased by infarction in both Ctrl and cKO mice (Figure 9B). However, the induction of their expression was significantly attenuated in GPR176cKO mice compared to Ctrl mice (Figure 9B). In addition, the expression levels of the cardiac hypertrophy markers ANP (Nppa) and BNP (Nppb) and the cardiac hypertrophy-promoting factor IGF-1 (Igf1) were significantly increased by myocardial infarction in both Ctrl and cKO mice (Figure 9C). However, the induction of IGF1 (Igf1) expression was significantly attenuated in GPR176cKO mice compared to Ctrl mice, and the expression of ANP (Nppa) and BNP (Nppb) tended to decrease in cKO mice (Figure 9B). These results indicate that GPR176 promotes the induction of fibrosis-related factors in myofibroblasts and contributes to cardiac fibrosis.

[0117] Example 10 Myofibroblast-specific deficiency of GPR176 suppresses fibrosis after myocardial infarction Since the expression of fibrosis-related factors after myocardial infarction was also decreased in mice lacking GPR176 specifically in myofibroblasts, we investigated the effect of myofibroblast-specific GPR176 deficiency on survival rate and progression of fibrosis after myocardial infarction. Ctrl mice and GPR176cKO mice were subjected to myocardial infarction and survival rates were examined 28 days after the procedure. As a result, no difference in survival rate was observed between Ctrl mice and GPR176cKO mice (Figure 9D).

[0118] Next, we performed picrosirius red staining, which stains collagen red, in the hearts of Ctrl and GPR176cKO mice 28 days after infarction, to evaluate the extent of fibrosis after infarction (Figure 9E). Figure 9F shows the quantification of collagen volume fraction (CVF). CVF was determined by counting the collagen deposition area. The results revealed that GPR176cKO mice had significantly reduced collagen accumulation compared to Ctrl mice. Overall, Figure 9 shows that myofibroblast-specific GPR176 deficiency attenuates fibrosis after myocardial infarction. These results suggest that the function of GPR176 in promoting the expression of fibrosis-related factors and aggravating fibrosis is likely mediated through myofibroblasts.

[0119] Example 11 Myofibroblast-specific deficiency of GPR176 suppresses fibrosis after myocardial infarction Since fibrosis after myocardial infarction treatment was suppressed in GPR176cKO mice, we investigated whether improvement in cardiac function associated with the suppression of fibrosis was observed in GPR176cKO mice. Specifically, cardiac function was morphologically measured by echocardiography in the hearts of Ctrl and GPR176cKO mice 28 days after myocardial infarction. As a result, significant improvements in left ventricular ejection fraction (EF) and left ventricular fractional shortening (FS) were observed in cKO mice, as in mice with a systemic GPR176 deficiency (Figure 10A). Furthermore, cardiac weight (HW / BW) and lung weight (LW / BW) were measured after infarction, but no significant difference was observed in the weight increase after infarction between Ctrl and cKO mice (Figure 10B). Overall, Figure 10 shows that myofibroblast-specific GPR176 deficiency improves cardiac function after infarction. These results demonstrated that GPR176 expressed in myofibroblasts contributes to promoting fibrosis in vivo.

[0120] Example 12 Liver studies We investigated whether myofibroblasts express GPR176 significantly even in pathological conditions of the liver. In the liver, myofibroblasts are called hepatic stellate cells (HSCs). Hepatic stellate cells overproduce extracellular matrix proteins such as collagen and cause fibrosis. We therefore compared the expression levels of GPR176 in hepatic stellate cells (HSCs), hepatocytes (HCs), which compose the liver, and Kupffer cells (KCs), which are resident macrophages in the liver.

[0121] Specifically, the livers of mice administered carbon tetrachloride were treated with collagenase, and the cells were dispersed. Then, the HSC, HC, and KC cell fractions were collected by centrifugation and MACS magnetic cell separation.

[0122] Next, the expression levels of marker molecules for myofibroblasts, hepatocytes, and macrophages in each cell fraction were measured by real-time RT-PCR. The results are shown in Figure 11A.

[0123] Figure 11A shows that the myofibroblast marker molecules α-SMA (Acta2) and Col1a1 (Col1a1) are prominently expressed only in the hepatic stellate cell (HSC) fraction. In addition, it was confirmed that the hepatocyte marker molecule Cyp7a1 (Cyp7a1) is prominently expressed only in the hepatocyte (HC) fraction. In addition, it was confirmed that the macrophage marker CD68 (Cd68) is prominently expressed only in the Kupffer cell (KC) fraction. From these results, it was confirmed that the separation of each cell was performed appropriately.

[0124] Therefore, the expression level of GPR176 was measured using the same cell samples. Figure 11B is a graph showing the results of measuring the expression level of GPR176. The expression level of the gene is shown as a relative value to the expression level of the GAPDH gene.

[0125] As a result, it was revealed that GPR176 is significantly expressed in hepatic stellate cells (HSCs).Accordingly, GPR176 is highly expressed in hepatic stellate cells (myofibroblasts), which are the cells that initiate fibrosis, even during liver fibrosis, and it was confirmed that GPR176 is closely involved in the pathology of liver fibrosis.

[0126] Example 13 Expression of GPR176 in a mouse model of liver fibrosis We investigated whether increased expression of GPR176 is observed in liver fibrosis. It is known that liver fibrosis is induced in mice by administration of carbon tetrachloride for 4 weeks, and liver fibrosis disappears when the administration of carbon tetrachloride is discontinued and the mice are kept for 4 weeks. Therefore, we investigated the expression levels of α-SMA and GPR176 using this liver fibrosis model.

[0127] FIG. 12A is a graph showing the results of quantifying the expression level of α-SMA in the liver by real-time RT-PCR for the following mice: a control group not administered carbon tetrachloride (n = 4 to 6), a group administered carbon tetrachloride for 4 weeks (n = 6), and a group administered carbon tetrachloride for 4 weeks followed by cessation of administration and then housing the mice for 4 weeks (n = 5).

[0128] Figure 12B is a graph showing the results of quantifying the expression level of GPR176 in the liver of mice from the control group (n = 4 - 6) that did not receive carbon tetrachloride (CCl4), the group that received carbon tetrachloride for 4 weeks (n = 6), and the group that received carbon tetrachloride for 4 weeks and then discontinued the administration and was then kept for 4 weeks (n = 5), using real-time RT-PCR.

[0129] As a result, it was revealed that the expression levels of α-SMA and GPR176 were significantly increased by the administration of carbon tetrachloride. In addition, it was revealed that the expression levels of α-SMA and GPR176 were decreased when the administration of carbon tetrachloride was discontinued and the mice were kept for four weeks after the administration. These results demonstrated that GPR176 is also involved in the pathology of fibrosis in the liver.

[0130] Example 14 Expression of GPR176 in a mouse model of nonalcoholic steatohepatitis It is known that C57BL / 6J mice develop a non-alcoholic steatohepatitis (NASH) model when fed "A06071302 (60Kcal%fat)" (a very high fat, choline-deficient, methionine-reduced diet (Research Diets)) for five weeks.

[0131] Using this model mouse, we investigated the expression level of GPR176 in NASH-like pathology. For comparison, we also investigated the expression level of COl1a1, a marker for NASH, by measuring the expression level using real-time RT-PCR.

[0132] Figure 13A is a graph showing the results of quantifying the expression level of COl1a1 in the liver of control mice fed a normal diet (n = 5) and NASH model mice fed a diet for producing NASH (n = 5) by real-time RT-PCR. Figure 13B is a graph showing the results of quantifying the expression level of GPR176 in the liver of control mice fed a normal diet (n = 5) and NASH model mice fed a diet for producing NASH (n = 5) by real-time RT-PCR.

[0133] As a result, it was revealed that the expression levels of COl1a1 and GPR176 were significantly increased in NASH model mice, indicating that GPR176 is involved in liver fibrosis in NASH-like pathology.

[0134] Example 15 GPR176 expression is increased during pulmonary and renal fibrosis Organ fibrosis is observed not only in the heart but also in various other organs such as the kidney, liver, and lungs. Therefore, we investigated whether the expression level of GPR176 increases in fibrotic conditions in organs other than the heart. Idiopathic pulmonary fibrosis, a pulmonary fibrosis disease, is said to result in approximately half of deaths within 2 to 5 years of diagnosis (Carrington, R., Jordan, S., Pitchford, SC & Page, CP, Pulm. Pharmacol. Therauptics 51, 73-78 (2018)), and the development of new treatments is urgently needed. Bleomycin (BLM) is a chemotherapy drug used to treat several neoplastic diseases, including lymphoma, head and neck squamous cell carcinoma, testicular cancer, and ovarian cancer. In the presence of iron and oxygen, BLM generates reactive oxygen species (ROS) and reactive nitrogen species (RNS). These cause DNA strand breaks, which induce acute interstitial and intraalveolar inflammation, thereby inducing fibrosis. The BLM-administered pulmonary fibrosis model is the most widely used method for studying pulmonary fibrosis in animal models30 (Bleomycin in the setting of lung fibrosis induction: From biological mechanisms to counteractions. PMID: 25959210 https: / / www.ncbi.nlm.nih.gov / pubmed / 25959210).

[0135] To investigate the expression of GPR176 during pulmonary fibrosis, we attempted to create a pulmonary fibrosis model by administering BLM once via the trachea (Fig. 14A). The expression levels of fibrosis-related factors in the lungs 14 days after BLM administration were measured by real-time RT-PCR. The expression levels of Acta2, Col1a1, and Ctgf were significantly increased in the bleomycin-administered group compared with the control saline-administered group, confirming that pulmonary fibrosis was induced appropriately by BLM administration (Fig. 14B). The expression levels of GPR176 were measured using the same samples, and a significant increase in GPR176 expression was observed in the BLM-administered group (Fig. 14C). This suggests that GPR176 may be involved in fibrosis not only in the heart but also in the lungs.

[0136] On the other hand, chronic renal failure is seen in about half of adults over 70 years old, and fibrosis occurs during the pathology, contributing to kidney dysfunction31 (Humphreys, BD Mechanisms of Renal Fibrosis. (2018). https: / / www.ncbi.nlm.nih.gov / pubmed / 29068765). Therefore, as with lung fibrosis, research on kidney fibrosis is being actively conducted. Unilateral ureteral obstruction (UUO) is a procedure in which one ureter is ligated to inhibit urine excretion, which induces hemodynamic changes due to mechanical stretching such as tubular dilatation and interstitial dilatation, apoptosis of epithelial tubular cells, and inflammation due to oxidative stress, leading to fibrosis in the renal interstitium (Martinez-Klimova, E., Aparicio-Trejo, OE, Tapia, E. & Pedraza-Chaverri, J., Biomolecules 9, (2019)). To investigate the expression of GPR176 during renal fibrosis pathology, we attempted to create a renal fibrosis model using UUO (Figure 14D). Renal fibrosis was induced by ligation of the right ureter. Sham-operated rats were used as controls. The expression levels of fibrosis-related factors in the kidneys 7 days after UUO treatment were measured by real-time RT-PCR. The expression levels of α-SMA (Acta2), a marker molecule for myofibroblasts, and Col1a1 (Col1a1) and CTGF (Ctgf), marker molecules for fibrosis, were significantly increased in the UUO group compared to the sham treatment group, confirming that fibrosis had been induced (Figure 14E). The expression levels of GPR176 were measured using the same samples, and it was revealed that the expression levels were significantly increased in the kidneys of the UUO group compared to the sham treatment group (Figure 14F). Overall, Figure 14 shows that the expression levels of GPR176 are also increased during pulmonary and renal fibrotic pathology. These results suggest that GPR176 may be involved in fibrosis not only in the heart but also in other organs, including the lungs and kidneys.

[0137] Example 16 GPR176 is expressed in myofibroblasts during pulmonary fibrosis We investigated whether GPR176 is expressed in myofibroblasts in the lungs, as in the heart. First, we detected GPR176 mRNA in normal lungs by in situ hybridization. As in the heart, no GPR176 expression was observed in normal lung tissue (Fig. 15A). Next, we simultaneously detected GPR176 mRNA by in situ hybridization and immunostained using antibodies against various cell markers in lung sections from mice in which fibrosis was induced by administration of BLM. GPR176 signals were hardly detected in CD31-positive endothelial cells or CD45-positive blood cells, but were detected only in αSMA-positive myofibroblasts.

[0138] Example 17 GPR176 promotes the expression of fibrosis-related factors in myofibroblasts Since GPR176 is strongly expressed in myofibroblasts, we investigated whether GPR176 regulates the expression of fibrosis-related factors in myofibroblasts. First, siRNA against GPR176 (siGPR176) was introduced into myofibroblasts isolated from mouse hearts after myocardial infarction treatment, and real-time RT-PCR was used to examine whether the expression levels of fibrosis-related factors changed when GPR176 was knocked down. In detail, myofibroblasts were isolated from infarcted hearts of WT mice on the third day after infarction treatment, and then siRNA against GPR176 was transfected into the isolated myofibroblasts. 96 hours after transfection, total RNA extracted from these cells was subjected to real-time RT-PCR. When the expression level of GPR176 was measured, it was confirmed that GPR176 mRNA expression was reduced in myofibroblasts treated with siRNA against GPR176. It was confirmed that the expression was suppressed to about 30% by the introduction of siGPR176 (Figure 16A). Under these conditions, the expression levels of the profibrotic factors CTGF (Ctgf), fibronectin (Fn1), periostin (Postn), and TGF-β2 (Tgfb2) were significantly decreased in the siGPR176-transfected group (Fig. 16A).

[0139] Control siRNA was Silencer TM Select Negative Control No. 1 siRNA #4390843 sequence was used (ThermoFischer). siRNA against GPR176 was Silencer TM Select siRNA #117673, the sequences of which are sense: GAUAUUUCCUGAUAAGUAUtt (sequence number 9 in the sequence listing), antisense: AUACUUAUCAGGAAAUAUCcc (sequence number 10 in the sequence listing) (ThermoFischer).

[0140] Myofibroblasts not only initiate fibrosis, but also produce humoral factors and affect the hypertrophy of cardiomyocytes after myocardial infarction or during cardiac hypertrophy caused by hypertension (Takeda, N. & Manabe, I., Int. J. Inflam. 2011, 1-13 (2011)). Therefore, we investigated the effect of knockdown of GPR176 in myofibroblasts on the expression of these humoral factors. Specifically, we investigated the expression of IGF-1 (Igf1), a factor that acts on cardiomyocytes and causes cardiac hypertrophy, and found that its expression was significantly reduced in the siGPR176-transfected group (Figure 16A).

[0141] Next, we overexpressed GPR176 using a retrovirus in myofibroblasts isolated from mouse hearts after myocardial infarction, and evaluated by real-time RT-PCR whether the expression of fibrosis-related factors increased, in contrast to knockdown. In detail, myofibroblasts were isolated from infarcted hearts of WT mice on the third day after infarction, and then the isolated myofibroblasts were infected with the GPR176 retrovirus. 48 hours after infection, total RNA extracted from these cells was subjected to real-time RT-PCR. As a result, the expression levels of the fibrosis-promoting factors CTGF (Ctgf), periostin (Postn), and TGF-β2 (Tgfb2) were significantly increased by overexpression of GPR176 (Figure 16B). In addition, the expression level of fibronectin (Fn1) tended to increase by overexpression of GPR176 (Figure 16B). Furthermore, the expression level of IGF-1 (Igf1), a cardiac hypertrophy-promoting factor, was significantly increased by GPR176 overexpression (Figure 16B). Overall, Figure 16 shows that GPR176 promotes the expression of fibrosis-related factors in myofibroblasts. These results of GPR176 knockdown and overexpression experiments in myofibroblasts demonstrated that GPR176 expressed in myofibroblasts is a molecule that promotes fibrosis.

[0142] Example 18 We investigated in detail whether cells expressing GPR176 also express α-SMA. GPR176 mRNA was detected on mouse heart sections using the in situ hybridization technique. In the in situ hybridization technique, if the mRNA of the target molecule is expressed, it can be detected in the form of dots by using a probe specific to that molecule. Co-detection of GPR176 mRNA and α-SMA protein was performed on mouse heart sections 7 days after myocardial infarction treatment. As a result, it was revealed that almost all GPR176-positive cells in the border and infarct regions of the mouse heart expressed α-SMA. The results are shown in Figure 17. For each section, the proportion of α-SMA expression in GPR176-positive cells and GPR176 expression in α-SMA-positive cells were quantified in 12 fields (total of 24 fields) on one side in the border zone and 11 fields in the infarct region. Data from three independent sections were averaged and expressed as mean ± standard error. The scale bar is 20 μm.

[0143] Example 19 Relationship between GPR176 expressing cells and existing myofibroblast marker expressing cells in the heart To examine the validity of GPR176 as a marker for myofibroblasts, we compared the expression of GPR176 with that of existing myofibroblast markers. Although αSMA has been widely used as a marker for myofibroblasts, a molecule called periostin (Postn) has been reported as a more specific marker for the heart in recent years (Kanisicak, O. et al., Nat. Commun. 7, 1-14 (2016)). Therefore, we used myofibroblasts [CD45(-), CD31(-) cells] isolated from the hearts of infarcted mice to detect GPR176mRNA and Postn mRNA by in situ hybridization and simultaneously perform immunostaining with αSMA antibody to examine their expression (Figure 18A). Specifically, we quantified the number of GPR176mRNA-positive cells in αSMA-positive cells and Postn-positive cells, and the number of αSMA-positive cells or Postn-positive cells in GPR176mRNA-positive cells. We also quantified the number of GPR176mRNA-positive cells in αSMA-positive cells and Postn-positive cells. As a result, about 99% of the cells positive for each marker were GPR176mRNA positive cells (FIG. 18C). Therefore, it was revealed that most of the existing myofibroblast marker-expressing cells expressed GPR176mRNA.

[0144] On the other hand, for each marker, the proportion of marker-positive cells in GPR176 mRNA-positive cells was approximately 98% (Fig. 18D, E). Therefore, it was revealed that most of the GPR176 mRNA-positive cells were myofibroblast marker-positive cells. A similar study was also performed in blood cells [CD45-positive cells] (Fig. 18B), but almost no GPR176 mRNA-positive cells were observed (Fig. 18C). Overall, Fig. 18 shows that the expression of GPR176 is highly correlated with the expression of existing myofibroblast markers (α-SMA and periostin) in the heart. Therefore, GPR176-expressing cells were almost identical to existing myofibroblast marker-expressing cells, suggesting that GPR176 could be a marker for true myofibroblasts.

[0145] Example 20 GPR176 expressing cells are similar to the cells expressing existing myofibroblast markers in the lungs. Next, to examine whether GPR176 is a valid marker for myofibroblasts not only in the heart but also in the lung, myofibroblasts [CD45(-), CD31(-), CD326(-) cells] were isolated from the lungs of mice administered BLM (Figure 19A). As in the heart study, GPR176 mRNA was detected by in situ hybridization and immunostained with αSMA antibody to examine their colocalization (Figure 19B). First, the number of GPR176 mRNA positive cells in αSMA positive cells was quantified. As a result, it was revealed that approximately 97% of αSMA positive cells were GPR176 positive cells (Figure 19D). Conversely, the number of αSMA positive cells in GPR176 positive cells was quantified in the same way, and it was revealed that 98% of GPR176 positive cells were αSMA positive cells (Figure 19E). These results suggest that GPR176 may be a marker receptor for myofibroblasts not only in the heart but also in the lung. In addition, a similar study was performed on blood cells [CD45 positive cells], but GPR176 mRNA positive cells were hardly observed (Fig. 19B, D). Overall, Fig. 19 shows that GPR176 expressing cells are almost identical to α-SMA expressing cells, an existing myofibroblast marker, in the lung. Therefore, GPR176 is expressed in almost all pulmonary myofibroblasts, suggesting that it could be a marker for true myofibroblasts in the lung as well.

[0146] Example 21 GPR176 is specifically expressed in myofibroblasts in the human heart To investigate whether GPR176 is expressed in myofibroblasts not only in mice but also in humans, we simultaneously performed in situ hybridization to detect GPR176 mRNA and immunostaining with an antibody against αSMA in cardiac sections from patients with and without myocardial infarction. As a result, almost no GPR176 signal was observed in cardiac sections from patients without myocardial infarction (Figure 20A). On the other hand, GPR176 signals were observed in αSMA-positive myofibroblasts in cardiac sections from patients with myocardial infarction (Figure 20B). Therefore, it was revealed that GPR176 is not expressed in the heart without fibrosis not only in mice but also in human hearts, but is expressed in myofibroblasts that appear during fibrosis.

[0147] Example 22 The majority of labeled cells in the hearts of GPR176 reporter mice after infarction are myofibroblasts Since GPR176 could be a novel marker for myofibroblasts in various organs, including the heart, we generated a genetically modified mouse, GPR176-cre mouse, in which Cre was knocked in downstream of the GPR176 promoter. By crossing this mouse with a Rosa26-tdTomato mouse (Swonger, JM, Liu, JS, Ivey, MJ & Tallquist, MD, Differentiation 92, 66-83 (2016)), we generated a GPR176 reporter mouse in which GPR176-expressing cells are labeled by tdTomato (Figure 21A). We performed an infarction procedure on this mouse, and examined tdTomato-labeled cells in heart sections on the third day by immunohistochemical staining. As a result, tdTomato-labeled cells were found in the interstitium. Furthermore, it was confirmed that most of them were αSMA-positive, whereas CD68, a marker for monocytes and macrophages, was negative (Figure 21B). [Industrial Applicability]

[0148] According to the present invention, it is possible to provide a technique for identifying a marker protein of myofibroblasts and preventing or treating a fibrotic disease.

Claims

1. A pharmaceutical composition for preventing or treating a fibrotic disease, comprising an inhibitor of G protein-coupled receptor 176 (GPR176) as an active ingredient, Inhibitors of GPR176 a pharmaceutical composition comprising a substance that inhibits the expression of a gene or a nucleic acid represented by any one of the following (a) to (c), the substance being selected from the group consisting of an siRNA, an antisense and a ribozyme, the target nucleic acid being the gene or the nucleic acid represented by any one of the following (a) to (c): (a) the GPR176 gene shown in any one of SEQ ID NOs: 2, 4, and 6 in the sequence listing; (b) a nucleic acid comprising a base sequence in which one or several bases have been deleted, substituted or added in the GPR176 gene shown in any one of SEQ ID NOs: 2, 4 and 6 in the sequence listing; (c) A nucleic acid that hybridizes under stringent conditions with a base sequence complementary to the GPR176 gene shown in any one of SEQ ID NOs: 2, 4 and 6 in the sequence listing.

2. A pharmaceutical composition for preventing or treating a fibrotic disease, comprising an inhibitor of G protein-coupled receptor 176 (GPR176) as an active ingredient, The pharmaceutical composition, wherein the GPR176 inhibitor is selected from the group consisting of antibodies and antibody fragments against GPR176 protein.

3. The pharmaceutical composition described in claim 2, wherein the antibody fragment is selected from the group consisting of Fv, Fab and scFv.

4. A method for screening for a preventive or therapeutic agent for a fibrotic disease, comprising the steps of culturing myofibroblasts in the presence of a candidate compound, quantifying the expression level of GPR176 gene mRNA or GPR176 protein in the cultured myofibroblasts, and determining that the candidate compound is a preventive or therapeutic agent for a fibrotic disease if the quantified expression level of GPR176 gene mRNA or GPR176 protein is reduced compared to a control.

5. A method for determining the severity of a fibrotic disease, comprising: (a10) measuring the amount of GPR176 (test biomarker amount) in the collected myofibroblasts of the subject; (b10) comparing the amount of the test biomarker with the amount of GPR176 (control biomarker amount) in myofibroblasts collected from a healthy subject; and (c10) determining that the fibrotic disease is aggravated when the amount of the test biomarker is greater than the amount of the control biomarker; The method includes:

6. A biomarker, GPR176 in myofibroblasts, that can determine the severity of fibrotic diseases.

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