Application of cardiac macrophage USP9X as intervention target to preparation of medicine for treating ischemic heart disease, polypeptide P7 and application of polypeptide P7

Abstract

The invention relates to the technical field of disease treatment, in particular to application of cardiac macrophage USP9X serving as an intervention target to preparation of medicine for treating ischemic heart disease, polypeptide P7 and application of the polypeptide P7. The invention finds that the expression of Ubiquitin specific peptidase 9X-Linked, USP9X coupled with deubiquitinase X chromosome of heart macrophage is reduced in the first three days (inflammation period) after myocardial infarction, and the inhibition of USP9X promotes the macrophage to be transformed into proinflammatory type, and finally causes poor ventricular remodeling, so that the USP9X can be used as an intervention target of ischemic heart disease, and then polypeptide is screened, and the application of the USP9X in the treatment of ischemic heart disease is realized. The degradation of USP9X after myocardial infarction is effectively inhibited, so that the excessive inflammatory response of macrophages after myocardial infarction is relieved.

Description

Technical Field

[0001] The present invention relates to the technical field of disease treatment, and particularly to the application of cardiac macrophage USP9X as an intervention target in the preparation of drugs for treating ischemic heart disease, polypeptide P7 and its application. Background Art

[0002] Ischemic heart disease, especially acute myocardial infarction (AMI), is one of the main causes of death in the global population. Although with the progress of treatment strategies such as cardiac revascularization, the acute mortality of acute myocardial infarction has decreased, the number of people developing heart failure has increased steadily. Ventricular pathological remodeling is the main pathological basis of heart failure after myocardial infarction and an important factor for judging prognosis. Currently, there are still few clinically available methods for improving ventricular pathological remodeling.

[0003] The excessive inflammatory response of some macrophages in the acute phase after myocardial infarction will lead to an increase in infarct area and deterioration of cardiac function, resulting in heart failure. Therefore, inhibiting macrophage inflammatory response and promoting inflammation resolution are potential measures to prevent pathological remodeling after myocardial infarction. Existing treatment methods have limitations in alleviating inflammation and pathological remodeling, and new effective treatment strategies need to be developed.

[0004] Polypeptides are bioactive molecules formed by the connection of two or more amino acids through peptide bonds. They are ubiquitous in nature and organisms and play a key role in life activities. Polypeptide drugs have attracted great attention in the field of drug development due to their advantages such as low dosage, strong specificity, significant efficacy, small side effects, easy synthesis and customization, and have been actively explored in multiple stages such as laboratory research, animal experiments, and clinical trials.

[0005] Therefore, developing a polypeptide drug that blocks the recognition of USP9X by HSC70 can effectively inhibit the degradation of USP9X after myocardial infarction, thereby reducing the excessive inflammatory response of macrophages after myocardial infarction, which has important research value and application prospects. Summary of the Invention

[0006] To solve the above problems, the present invention provides the application of cardiac macrophage USP9X as an intervention target in the preparation of drugs for treating ischemic heart disease, the polypeptide P7 and its application. The present invention discovers that the deubiquitinase of cardiac macrophages, ubiquitin specific peptidase 9X-linked (USP9X), is down-regulated in the first three days (inflammatory phase) after myocardial infarction. The inhibition of USP9X promotes the transformation of macrophages into a pro-inflammatory type, ultimately leading to adverse ventricular remodeling. Therefore, it can be used as an intervention target for ischemic heart disease, and then polypeptides are screened to effectively inhibit the degradation of USP9X after myocardial infarction, thereby reducing the excessive inflammatory response of macrophages after myocardial infarction.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] The present invention provides the application of cardiac macrophage USP9X as an intervention target in the preparation of drugs for treating ischemic heart disease.

[0009] The present invention also provides a polypeptide P7, and the amino acid sequence of the polypeptide P7 is shown as YGRKKRRQRRR-DLKRQ.

[0010] The present invention also provides the application of the polypeptide P7 described in the above technical solution in the preparation of drugs for inhibiting the degradation of cardiac macrophage USP9X.

[0011] Preferably, the peptide P7 inhibits the degradation of cardiac macrophage USP9X after myocardial infarction.

[0012] The present invention also provides the application of the polypeptide P7 described in the above technical solution in the preparation of drugs for reducing the binding of cardiac macrophage USP9X to HSC70.

[0013] The present invention also provides the application of the polypeptide P7 described in the above technical solution in the preparation of drugs for treating ischemic heart disease.

[0014] The present invention also provides a drug for treating ischemic heart disease, comprising the polypeptide P7 described in the above technical solution.

[0015] Preferably, the drug further comprises a pharmaceutically acceptable carrier and / or excipient.

[0016] Preferably, the drug is a pharmaceutical preparation administered by injection, oral administration, nasal mucosa, lung, rectum, oral mucosa or skin.

[0017] Preferably, the injection includes intramyocardial injection, intradermal injection, subcutaneous injection, intramuscular injection or intravenous injection.

[0018] Chaperone-mediated autophagy degradation (CMA) can specifically degrade target proteins: Target proteins carrying the KFERQ sequence are recognized by the chaperone HSC70 and transported to the lysosome for degradation through the lysosome-associated membrane protein 2A receptor. The present invention discovers that the increased acetylation level of macrophage USP9X after myocardial infarction causes the exposure of the KFERQ sequence, making it easily recognized by the chaperone HSC70 for chaperone-mediated autophagy degradation.

[0019] The present invention discovers the degradation mechanism of macrophage USP9X: The increased acetylation level of macrophage USP9X after myocardial infarction causes the exposure of the KFERQ sequence, making it easily recognized by the chaperone HSC70 for autophagy degradation.

[0020] The polypeptide P7 provided by the present invention has good cell penetration, can efficiently enter target cells, and has no obvious toxic and side effects within the effective dose range; it can effectively inhibit the degradation of USP9X in macrophages in the acute phase after myocardial infarction, thereby inhibiting the inflammatory response; it can effectively inhibit the pathological remodeling after myocardial infarction and improve cardiac function.

[0021] The expression of USP9X in cardiac macrophages decreases during the inflammatory period after myocardial infarction. The inhibition of USP9X promotes the inflammatory response of macrophages and aggravates pathological cardiac remodeling.

[0022] The present invention explains the degradation mechanism of macrophage USP9X: After myocardial infarction, the 2414 site of USP9X is acetylated during the acute inflammatory phase to form the KFERQ sequence, making it easily recognized by the chaperone protein HSC70, and HSC70 mediates the entry of USP9X into the lysosome for degradation.

[0023] The amino acid sequence of the polypeptide P7 provided by the present invention is YGRKKRRQRRR-DLKRQ, that is, a cell-penetrating peptide conjugated with the KFERQ sequence after acetylation at the 2414 site of USP9X, which can promote the absorption of the polypeptide by cells and competitively inhibit the recognition of acetylated USP9X by HSC70.

[0024] The polypeptide of the present invention has the function of inhibiting the inflammatory response of macrophages after myocardial infarction. This polypeptide can inhibit the degradation of USP9X in macrophages after myocardial infarction, thereby inhibiting the inflammatory response of macrophages and effectively reducing the pathological remodeling after myocardial infarction. Secondly, the polypeptide of the present invention can enter target cells and has no obvious toxic and side effects within the effective dose range.

[0025] The beneficial effects of the present invention:

[0026] (1) The polypeptide of the present invention can enter macrophages, competitively inhibit the recognition of USP9X by the chaperone protein HSC70, reduce the degradation of USP9X in the inflammatory response, and has no obvious toxic and side effects within the effective dose range; it can effectively inhibit the inflammatory response of macrophages, thereby improving pathological remodeling after myocardial infarction.

[0027] (2) The present invention provides new drugs and treatment regimens for the clinical treatment of ischemic heart disease, which is of great significance for improving the clinical treatment effect of ischemic heart disease and the quality of life of patients. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments.

[0029] Figure 1 Expression changes and effects of USP9X in cardiac macrophages after myocardial infarction; wherein A shows the expression changes of USP9X in cardiac macrophages at different time points after myocardial infarction detected by flow cytometry, and B shows the qPCR results of the promotion of the expression of inflammation-related genes in macrophages by USP9X knockout;

[0030] Figure 2 Effects of USP9X knockout in macrophages on cardiac fibrosis and cardiac function after myocardial infarction; wherein, A is a representative Sirius red staining map of the heart sections of mice with USP9X knockout in macrophages after myocardial infarction; B is the change in cardiac function of mice with USP9X knockout in macrophages after myocardial infarction;

[0031] Figure 3 Mechanism of the downregulation of USP9X in the inflammatory response after myocardial infarction; wherein, A shows that the degradation of USP9X in macrophages can be blocked by knocking down HSC70 under inflammatory conditions; B indicates an increase in the interaction between macrophage USP9X and HSC70 under inflammatory conditions; C is the predicted classical / putatively modified and activated potential KFERQ-like sequence of USP9X; D is the result of an increase in the acetylation level of USP9X in the inflammatory response;

[0032] Figure 4 Polypeptide sequences capable of inhibiting the degradation of USP9X in the inflammatory response of macrophages; wherein, A is a polypeptide sequence capable of competing with the KFERQ-like sequence of acetylated and activated USP9X for binding to HSC70, and all polypeptides are conjugated with the cell-penetrating peptide YGRKKRRQRRR at the N-terminus to promote the absorption of the polypeptide by cells; B is the screening result of the inhibition of USP9X degradation by polypeptide P7;

[0033] Figure 5 HPLC purification result of polypeptide P7;

[0034] Figure 6Mass spectrometry identification results of polypeptide P7;

[0035] Figure 7 Effect of polypeptide P7 on binding to HSC70 in vitro: A is a picture of the co-localization of polypeptide P7 labeled with Rhodamine B fluorescence and HSC70 enriched in primary mouse macrophages; B is the in vitro verification result of polypeptide P7 competing with USP9X for binding to HSC70;

[0036] Figure 8 Effect of polypeptide P7 on inhibiting USP9X degradation in vivo; among them, A is the flow cytometry result of polypeptide P7 inhibiting USP9X degradation in macrophages on the third day after myocardial infarction; B is the result of polypeptide P7 reducing the expression of inflammatory genes after myocardial infarction;

[0037] Figure 9 Improvement of cardiac fibrosis and cardiac function by intraperitoneal injection of polypeptide P7 into myocardial infarction mice every 2 days; among them, A is a representative picture of Sirius red staining of the heart after polypeptide P7 injection; B is the improvement of cardiac function after polypeptide P7 injection;

[0038] Figure 10 Evaluation of the toxic and side effects of polypeptide P7 on mice; among them, A is a morphological change diagram of the liver, kidney, and small intestine; B is the effect of polypeptide treatment on serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (BUN), and creatinine (Cr); Detailed implementation mode

[0039] The present invention provides the application of cardiac macrophage USP9X as an intervention target in the preparation of drugs for treating ischemic heart disease.

[0040] The present invention also provides a polypeptide P7, and the amino acid sequence of the polypeptide P7 is (SEQ ID No.1): YGRKKRRQRRR-DLKRQ. The present invention has no special limitation on the preparation method of the polypeptide P7, and those skilled in the art can synthesize it according to the conventional polypeptide synthesis method. In the present invention, the YGRKKRRQRRR promotes the absorption of the polypeptide by cells, and DLKRQ mimics the KFERQ-like sequence formed after acetylation of the DLKRK fragment of USP9X, and can competitively inhibit the recognition of this sequence by HSC70, reducing the autophagic degradation of USP9X.

[0041] The present invention also provides the application of the polypeptide P7 described in the above technical solution in the preparation of drugs for inhibiting the degradation of cardiac macrophage USP9X. In the present invention, the peptide P7 preferably inhibits the degradation of USP9X in cardiac macrophages after myocardial infarction.

[0042] The present invention also provides the use of the polypeptide P7 described in the above technical solution in the preparation of a drug for reducing the binding of USP9X and HSC70 in cardiac macrophages.

[0043] The present invention also provides the use of the polypeptide P7 described in the above technical solution in the preparation of a drug for treating ischemic heart disease.

[0044] The present invention also provides a drug for treating ischemic heart disease, comprising the polypeptide P7 described in the above technical solution. In the present invention, the drug preferably further comprises a pharmaceutically acceptable carrier and / or excipient. In the present invention, the drug is preferably a pharmaceutical preparation administered by injection, oral administration, nasal mucosa, lung, rectum, oral mucosa or skin. In the present invention, the injection preferably includes intramyocardial injection, intradermal injection, subcutaneous injection, intramuscular injection or intravenous injection.

[0045] To further illustrate the present invention, the present invention will be described in detail below with reference to embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0046] Example 1

[0047] Expression changes and effects of USP9X in cardiac macrophages after myocardial infarction

[0048] Wild-type mice were subjected to myocardial infarction surgery. The hearts of the mice on the 0th day, 3rd day, and 7th day after myocardial infarction were digested respectively, and the expression of USP9X in cardiac macrophages was analyzed by flow cytometry. Figure 1 Figure A shows that the expression of USP9X in mouse cardiac macrophages decreased in the first 3 days after myocardial infarction and recovered on the 7th day, demonstrating that macrophage USP9X plays a role in the inflammatory response after myocardial infarction.

[0049] The bone marrow of USP9X myeloid knockout mice and their littermate control mice was isolated, induced with 10 ng / ml M-CSF for 7 days, and the expression of pro-inflammatory and anti-inflammatory genes in macrophages after TLR4 activation was observed. Figure 1 Figure B shows that after stimulation with LPS (an agonist of TLR4), the inhibition of USP9X promoted the expression of pro-inflammatory genes (including Il1b, Il6, and Nos2) and weakened the expression of anti-inflammatory genes Arg1 and Il10.

[0050] Example 2

[0051] Effect of macrophage knockout of USP9X on cardiac fibrosis and cardiac function after myocardial infarction

[0052] Take 8-week-old USP9X flox / flox 、USP9X flox / flox LysM creMice were subjected to myocardial infarction modeling and then randomly divided into two groups of 10 each. Echocardiographic systolic function was evaluated before modeling and 3 days after modeling to ensure no difference in baseline cardiac function between the two groups. Then, echocardiography was performed on days 7, 14, and 28 after myocardial infarction. After 28 days, samples were taken, as Figure 2 shown in A, which is the Sirius red staining map of representative cardiac sections of the two groups of mice. It can be seen that the area of the infarct fibrosis region in the USP9X macrophage knockout group is larger than that in the control group.

[0053] As Figure 2 shown in B, on days 7, 14, and 28 after myocardial infarction, the left ventricular ejection fraction in the USP9X macrophage knockout group is lower and statistically different from that in the control group, indicating worse left ventricular cardiac function.

[0054] Example 3

[0055] Mechanism of downregulation of USP9X in the inflammatory response after myocardial infarction

[0056] Hspa8 (HSC70) is a key molecule in chaperone-mediated autophagy, which can recognize the KFERQ sequence of target substrates, form a chaperone-protein complex, and the complex is delivered to lysosomes for degradation. Bone marrow-derived macrophages were divided into three groups, one group was untreated, and the other two groups were stimulated with LPS, and HSC70 was knocked down in one of the groups. As Figure 3 shown in A, knocking down HSC70 can inhibit the degradation of USP9X in the inflammatory response.

[0057] Total proteins of macrophages treated or untreated with LPS were extracted and immunoprecipitated using an antibody against HSC70. As Figure 3 shown in B, the binding of USP9X and HSC70 increases in the inflammatory response.

[0058] Proteins that can be recognized by HSC70 generally have the KFERQ sequence, and the characteristics of the KFERQ sequence are: (1) flanked by glutamine (Q); (2) containing one or two positively charged amino acids, such as lysine (K) and arginine (R); (3) containing one or two hydrophobic amino acids, such as leucine (L), isoleucine (I), valine (V) or phenylalanine (F); (4) containing negatively charged amino acids such as glutamate (E) and aspartate (D). Proteins can also generate KFERQ-like sequences through post-translational modifications. For example, phosphorylation of serine (S), threonine (T) or tyrosine (Y) is similar to negatively charged amino acids; the property of acetylated lysine (K) is similar to that of glutamine (Q), etc. Predicted by KFERQ finder software v0.8, USP9X has KFERQ sequences, including 2 classical KFERQ sequences, 7 acetylated-activated KFERQ-like sequences and 3 phosphorylation-activated KFERQ-like sequences (such as Figure 3 shown in C).

[0059] Extract the total proteins of macrophages treated or untreated with LPS and perform immunoprecipitation using an antibody against USP9X. As Figure 3 shown in D, the acetylation modification of USP9X increases during the inflammatory response, and the phosphorylation modification remains unchanged, suggesting that the acetylation of USP9X may generate KFERQ-like sequences that can be recognized by HSC70, increasing the autophagic degradation of USP9X.

[0060] Example 4

[0061] Screening of polypeptides: As Figure 4 shown in A, synthesize polypeptides from 7 acetylation-activated KFERQ-like sequences on USP9X to enable them to compete with acetylated USP9X and inhibit the binding and degradation of USP9X by HSC70. To further increase the cell penetration of the polypeptides so that they can enter the cells to play a role, the present invention further optimized the design of these polypeptide sequences, that is, the N-terminus was linked with the transmembrane peptide YGRKKRRQRRR. Isolate mouse bone marrow-derived macrophages, and treat them with LPS and the above 7 polypeptides respectively at the same time. As Figure 4 shown in B, the polypeptide P7, namely YGRKKRRQRRR-DLKRQ, can inhibit the degradation of USP9X mediated by LPS, proving that under inflammatory activation, the 2414 site of macrophage USP9X can be acetylated to generate KFERQ-like sequences, which are recognized by HSC70 for degradation, while the polypeptide DLKRQ can competitively inhibit the degradation of USP9X.

[0062] Example 5

[0063] HPLC purification results and MS identification results of polypeptide P7

[0064] The polypeptide was synthesized by a conventional polypeptide synthesis method in the art and purified and identified by high performance liquid chromatography (HPLC) and mass spectrometry (MS). The results are shown in Figure 5 and 6 respectively. After purification by HPLC, the purity of the sample was detected to be 97.41%, and the molecular weight was 2200.5 as identified by MS without error.

[0065] Example 6

[0066] Effect of polypeptide P7 entering target cells and binding to HSC70

[0067] Macrophages derived from mouse bone marrow were isolated. In the experimental group, polypeptide P7 labeled with Rhodamine B fluorescence was added to the culture medium (final concentration of polypeptide was 20 μM), and in the control group, only normal saline was added. Both were cultured for 2 hours. The culture supernatant was discarded, and the cells were washed twice with PBS buffer, fixed with 4% paraformaldehyde at room temperature for 10 minutes, permeabilized, blocked, and then incubated overnight with anti-HSC70 primary antibody. The next day, the cells were washed three times with PBS buffer, incubated with fluorescent secondary antibody at room temperature for 1 hour, and after washing off the secondary antibody, the cells were mounted with a mounting medium containing DAPI nuclear dye, and fluorescence was observed and photographed under a laser confocal microscope. As shown in A of Figure 7 , in the control group, only the morphology of the nuclei positive for DAPI nuclear dye in blue and HSC70 in green were visible; while in the group with the fluorescently labeled polypeptide, significant red Rhodamine B fluorescence signals were observed to aggregate in macrophages and co-localize with HSC70. It is suggested that the polypeptide can penetrate the cell membrane and enter the target cells to bind to HSC70 only after 2 hours of co-culture.

[0068] Macrophages derived from mouse bone marrow were isolated and randomly divided into four groups. One group was not treated, and three groups were stimulated with LPS. At the same time, two of the three groups were treated with control peptide or polypeptide P7 respectively. After 24 hours, the cells were collected and immunoprecipitated with an antibody against USP9X. As shown in B of Figure 7 , polypeptide P7 rather than the control peptide could reduce the binding of USP9X to HSC70.

[0069] Example 7

[0070] Effect of polypeptide P7 on inhibiting USP9X degradation in vivo

[0071] Eight-week-old C57 mice were subjected to myocardial infarction surgery or sham surgery, and then randomly divided into two groups with 5 mice in each group. One group was intraperitoneally injected with polypeptide P7 (20 mg / kg) after modeling, and the control group was injected with the same dose of control peptide. After 3 days, the samples were taken, the heart was digested, and the expression of USP9X in cardiac macrophages was analyzed by flow cytometry as shown in Figure 8As shown in Figure A, the inhibitory part of USP9X was reversed after the injection of polypeptide P7 in myocardial infarction mice.

[0072] Eight-week-old C57 mice were subjected to myocardial infarction surgery and then randomly divided into three groups. Two of the groups were given injections of control peptide or polypeptide P7, as Figure 8 shown in Figure B, polypeptide P7, rather than the control peptide, was able to effectively reduce the expression of cardiac inflammatory genes (Il1, Il6, Nos2, Tnf, Ccl2) three days after myocardial infarction and increase the expression of anti-inflammatory genes (Arg1).

[0073] Example 8

[0074] Evaluation of cardiac fibrosis and cardiac function after injection of polypeptide P7 in myocardial infarction mice

[0075] Eight-week-old C57 mice were subjected to myocardial infarction modeling and then randomly divided into three groups of 7 mice each. Two of the groups were intraperitoneally injected with control peptide or polypeptide P7 (20 mg / kg) three times a week. Echocardiographic systolic function was evaluated before and three days after modeling to ensure that there was no difference in baseline cardiac function between the two groups. Then, echocardiography was performed on days 7, 14, and 28 after myocardial infarction. Four weeks after modeling, the samples were taken. The hearts were placed in 30% sucrose solution for 1 day and then embedded in OCT. Then, frozen sections with a thickness of 6 μm were made, starting from the apex of the heart. Sections were collected when a circular tissue structure appeared, and one section was collected every 500 μm. Six layers were collected from each heart. Then, Sirius red staining was performed, and the proportion of the infarcted fibrotic area was statistically analyzed using ImageJ software.

[0076] As Figure 9 shown in Figure A, representative gross heart images and Sirius red staining images of each layer separated by 500 μm for the three groups of mice are shown. It can be seen that the area of the infarcted fibrotic region in the polypeptide P7 injection group is smaller than that in the normal saline group and the control peptide group. The statistical chart of Sirius red staining indicates that the proportion of the infarcted fibrotic region in the polypeptide P7 injection group is lower and statistically different compared to the normal saline group and the control peptide group.

[0077] As Figure 9 shown in Figure B, on days 7, 14, and 28 after myocardial infarction, the cardiac function of the polypeptide P7 injection group is better than that of the normal saline group and the control peptide group.

[0078] Example 9

[0079] Evaluation of the toxic and side effects of polypeptide P7 on mice by HE staining and blood biochemical detection

[0080] When the mice in Example 8 were sacrificed 28 days after myocardial infarction modeling and after the polypeptide treatment was completed, the kidneys, livers and small intestines of the mice were taken, fixed, dehydrated, embedded, and paraffin sections with a thickness of 4 μm were made. After dewaxing the sections, HE staining was performed using an automatic staining machine, and after sealing with neutral balsam, photographs were taken using a Leica upright microscope. At the same time, the mouse blood was collected into 1.5 ml EP tubes, allowed to stand at room temperature for 2 hours until the blood coagulated, then centrifuged at 4 °C and 3000 rpm for 10 min to obtain the upper serum, and the levels of creatinine (Cr), blood urea nitrogen (BUN), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured by ELISA.

[0081] As Figure 10 shown in A, there were no pathological changes (such as vacuolation, pigment deposition, cell necrosis and inflammatory cell infiltration) in the livers, kidneys and small intestines of the control peptide, polypeptide P7 treatment group and control group mice, suggesting that polypeptide P7 has no obvious toxic and side effects on mice at the effective treatment dose and has good biosafety.

[0082] As Figure 10 shown in B, there were no significant differences in the values of creatinine (Cr), blood urea nitrogen (BUN), serum alanine aminotransferase (ALT) and serum aspartate aminotransferase (AST) among the control peptide, polypeptide P7 treatment group and control group mice. It is suggested that polypeptide P7 has no effect on the liver and kidney functions of mice at the effective anti-treatment dose and has good biosafety.

[0083] The present invention relates to the field of biomedicine, and discloses a polypeptide and its application in the preparation of drugs for treating ischemic heart disease. The amino acid sequence of the polypeptide of the present invention is YGRKKRRQRRR-DLKRQ. The polypeptide of the present invention has good cell penetration and no obvious toxic and side effects within the effective dose range; it can effectively inhibit the degradation of USP9X in cardiac macrophages after myocardial infarction, thereby inhibiting the cardiac inflammatory response, effectively inhibiting cardiac fibrosis and improving cardiac function. It provides new drugs and regimens for the clinical treatment of ischemic heart disease and is of great significance for improving the quality of life of patients.

[0084] Although the above embodiments have made a detailed description of the present invention, they are only a part of the embodiments of the present invention, not all of them. People can also obtain other embodiments according to these embodiments without creative efforts, and these embodiments all belong to the protection scope of the present invention.

Claims

1. Application of cardiac macrophage USP9X as an intervention target in the preparation of drugs for the treatment of ischemic heart disease.

2. A polypeptide P7, characterized in that: The amino acid sequence of the polypeptide P7 is YGRKKRRQRRR-DLKRQ.

3. Use of the polypeptide P7 according to claim 2 in the preparation of a drug for inhibiting the degradation of cardiac macrophage USP9X.

4. The use according to claim 3, characterized in that: The peptide P7 inhibits the degradation of USP9X in cardiac macrophages after myocardial infarction.

5. Use of the polypeptide P7 according to claim 2 in the preparation of a drug for reducing the binding of cardiac macrophages USP9X and HSC70.

6. Use of the polypeptide P7 according to claim 2 in the preparation of a drug for treating ischemic heart disease.

7. A drug for treating ischemic heart disease, comprising the polypeptide P7 according to claim 2.

8. The drug according to claim 7, characterized in that The drug further comprises a pharmaceutically acceptable carrier and / or excipient.

9. The drug according to claim 7, characterized in that The drug is a pharmaceutical preparation that is administered by injection, oral administration, nasal mucosa, lung, rectum, oral mucosa or skin.

10. The drug according to claim 9, characterized in that The injection includes intramyocardial injection, intradermal injection, subcutaneous injection, intramuscular injection or intravenous injection.

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