Pharmaceutical application of AR agonist based on bioinformatics targeted screening in sepsis sarcopenia

Abstract

The invention belongs to the field of biological medicine, and particularly discloses a pharmaceutical application of an AR agonist based on bioinformatics targeted screening in sepsis sarcopenia, and the core is that the AR agonist Ostarine is adopted to specifically activate muscle AR and improve SIS through subcutaneous injection administration in the acute stage (within 5 days) of sepsis. The mechanism comprises the following steps: (1) recovering skeletal muscle protein synthesis (up-regulating p-AKT / p-mTOR) and decomposing metabolic balance (down-regulating Atrogin-1 / MuRF1); (2) promoting the expression of a polyamine biosynthetic gene (AMD / ODC1 / SMOX); and (3) adjusting the ratio of fast and slow muscle fibers (promoting MyoD and inhibiting MHC I and TnI-flow). Experiments show that Ostarine (5mg / kg) can significantly improve the survival rate, muscle weight and grip strength of sepsis mice within 5 days and reverse amyotrophy. In addition, the invention provides an SIS drug screening method based on the RNA binding protein Hnrnpa1 (regulating AR pre-mRNA). The method is easy and convenient to operate and high in targeting performance, and a new strategy is provided for treatment of sepsis sarcopenia.

Description

Technical Field

[0001] The present invention belongs to the field of biomedicine and specifically discloses a pharmaceutical use of an AR agonist based on bioinformatics targeted screening in sepsis sarcopenia. Background Art

[0002] Sarcopenia is a common complication of sepsis, characterized by rapid loss of muscle mass and function, which seriously affects patient prognosis. The full English name of sepsis sarcopenia is Sepsis-induced sarcopenia, which can be abbreviated as SIS. Clinically, patients with sarcopenia will experience weakened muscle strength, difficulty in weaning from mechanical ventilation, loss of mobility, and even long-term disability. Current treatments mainly focus on infection control, nutritional support, and early rehabilitation, but the efficacy is limited, and some patients will develop irreversible sarcopenia. This field urgently needs further research on its pathological mechanisms and screening of key targets to develop targeted intervention measures.

[0003] Previous studies have identified molecular pathways involved in regulating sarcopenia in sepsis, including neural, immune, and hormonal pathways. However, no suitable muscle-specific intervention targets have been identified to improve sarcopenia symptoms and prognosis. Testosterone is one of the major metabolic hormones, and the androgen receptor (AR) is a protein molecule that specifically receives and transmits testosterone's signals to peripheral tissues and organs. It has been established that the testosterone-AR signaling axis plays a key role in maintaining the balance between protein synthesis and catabolism in muscle tissue, polyamine biosynthesis, and homeostasis of fast and slow muscle transitions. Hypotestosteroneemia is a common complication in critical illnesses such as sepsis and trauma, but exogenous testosterone replacement therapy has not significantly improved muscle atrophy symptoms and, due to its lack of tissue specificity, has increased side effects such as thrombosis and prostatic hyperplasia. Therefore, understanding the changes in the regulatory activity of the testosterone-AR signaling axis in the setting of sepsis and the mechanisms behind the lack of significant effect of exogenous testosterone supplementation may provide a breakthrough in improving the clinical dilemma of sarcopenia in sepsis. Summary of the Invention

[0004] To address the above issues, the present invention discloses a pharmaceutical application of an AR agonist based on bioinformatics targeted screening for sarcopenia in sepsis. Specifically, the invention discloses a method for the AR agonist ostarine to specifically activate AR expression in muscle tissue during the acute phase of sepsis, over a short course of treatment, and effectively treat sarcopenia in sepsis. This treatment method is convenient, fast, highly specific, and inexpensive. It has demonstrated good efficacy and safety in bodybuilders and elderly patients, and its efficacy in septic mice is clear, making it suitable for widespread application.

[0005] The present invention includes the following technical solutions:

[0006] The invention discloses an application of an AR agonist in preparing a medicine for treating sepsis-induced sarcopenia, wherein the AR agonist is ostarine.

[0007] Furthermore, in the above application, the drug is administered by subcutaneous injection.

[0008] Furthermore, in the above application, the treatment is performed within 5 days after the onset of sepsis.

[0009] Furthermore, in the above application, the drug is a drug that works by restoring the balance between protein synthesis and catabolism in skeletal muscle, specifically by upregulating the expression of synthesis pathway proteins p-AKT and p-mTOR, and downregulating the expression of degradation pathway proteins Atrogin-1 and MuRF1.

[0010] Furthermore, in the above application, the drug is a drug that acts by promoting the biosynthesis of polyamines in skeletal muscle, specifically by upregulating the expression of AMD, ODC1, and SMOX genes.

[0011] Furthermore, in the above application, the drug is a drug that works by regulating the ratio of fast and slow muscle fibers, specifically inhibiting the expression of slow muscle fiber conversion genes MHC I and TnI-slow, and promoting the expression of fast muscle fiber activation gene MyoD.

[0012] Furthermore, in the above application, the drug can improve the survival rate of sepsis, making the 5-day survival rate significantly higher than that of the untreated group.

[0013] The present invention also discloses a method for screening drugs for treating sepsis sarcopenia, comprising the following steps: using the regulatory ability of the test compound on the RNA binding protein Hnrnpa1 as a screening index, wherein Hnrnpa1 regulates its expression by binding to AR pre-mRNA.

[0014] Furthermore, the above-mentioned pharmaceutical preparation is in the form of an injection and contains a therapeutic amount of Ostarine.

[0015] Furthermore, the therapeutic dose of the above-mentioned pharmaceutical preparation is 5 mg / kg calculated for mice.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The present invention uses a classic sepsis mouse model to establish a sepsis sarcopenia phenotype, and uses a variety of molecular techniques to clarify for the first time that the regulatory activity disorder of the testosterone-AR signaling axis caused by AR down-regulation is a key pathogenic factor of sepsis sarcopenia, and the use of AR agonists to specifically activate AR expression in muscle tissue significantly improves the phenotype and poor prognosis of sepsis sarcopenia, showing a good intervention treatment effect. The method is simple to operate, has high specificity, and early drug administration intervention can significantly alleviate the symptoms of muscle atrophy caused by sepsis, and improve survival, without the need for expensive instruments and equipment. The present invention provides a new method for the targeted treatment of sepsis-induced sarcopenia, has a high reference value, and is suitable for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 , the mortality rate of mice induced by sepsis increased and a muscle atrophy phenotype appeared. A: Comparison of the levels of TNF-α, a hallmark inflammatory factor in mouse serum; B: Comparison of the levels of IL-6 in serum; C: Comparison of the 7-day mortality rate of mice; D: The trend of changes in mouse body weight over time; E, F, and G represent the changes in the weight of the gastrocnemius, tibialis anterior, and soleus muscles at different sampling time points, respectively; H: Comparison of the grip strength of the mouse forelimbs measured by the grip strength test; I: Comparison of the cross-sectional area of ​​the gastrocnemius muscle and the gastrocnemius muscle fibers in the mouse (15 10μm x 10μm boxes were randomly selected for statistics); J: Comparison of the cross-sectional area of ​​the tibialis anterior muscle and the tibialis anterior muscle fibers in the mouse (15 10μm x 10μm boxes were randomly selected for statistics); K: Comparison of the cross-sectional area of ​​the soleus muscle and the soleus muscle fibers in the mouse (15 10μm x 10μm boxes were randomly selected for statistics);

[0019] Figure 2 Downregulation of AR expression in skeletal muscle of septic mice leads to testosterone resistance. A: Changes in testosterone levels in mouse serum at different sampling time points; B: Changes in testosterone levels in mouse gastrocnemius muscle tissue at different sampling time points; C: Comparison of AR mRNA levels in mouse gastrocnemius muscle at different sampling time points; D: Comparison of AR protein levels in mouse gastrocnemius muscle assessed by WB at different sampling time points; E: Comparison of AR protein levels in mouse gastrocnemius muscle assessed by immunohistochemistry at different sampling time points.

[0020] Figure 3, changes in muscle tissue metabolic homeostasis regulated by AR downstream in septic mouse skeletal muscle, A: Previous studies have found that AR regulates three aspects of homeostasis in skeletal muscle, including protein synthesis / decomposition homeostasis, polyamine biosynthesis homeostasis, and fast-slow muscle fiber transition homeostasis; B: Changes in the protein anabolic pathway in the gastrocnemius muscle of mice at different sampling time points; C: Relative quantitative analysis graph corresponding to changes in the protein anabolic pathway; D: Changes in the protein catabolic pathway in the gastrocnemius muscle of mice at different sampling time points; E: Relative quantitative analysis graph corresponding to changes in the protein catabolic pathway; F: Changes in the mRNA expression levels of key genes for polyamine biosynthesis in the gastrocnemius muscle of mice at different sampling time points; G: Changes in the mRNA expression levels of key genes for fast-slow muscle fiber transition in the tibialis anterior muscle of mice at different sampling time points; H: Distribution of the ratio of fast and slow muscle fibers in the tibialis anterior muscle on the 5th day evaluated by immunofluorescence;

[0021] Figure 4 Agonist treatment improves the muscle atrophy phenotype and poor prognosis of septic mice. A: Group setting of mice targeted with the agonist ostarine; B: Comparison of mouse mortality 5 days after agonist ostarine treatment; C: Comparison of forelimb grip strength of mice 5 days after agonist ostarine treatment; D: Changes in body weight of mice over time under agonist ostarine treatment; E, F, G represent the weights of the gastrocnemius, tibialis anterior, and soleus muscles, respectively, after 5 days of agonist ostarine treatment; H: Comparison of HE-stained sections of the gastrocnemius, tibialis anterior, and soleus muscles of mice 5 days after agonist ostarine treatment; I: Comparison of the cross-sectional area of ​​the gastrocnemius, tibialis anterior, and soleus muscles of mice 5 days after agonist ostarine treatment (15 10μm x 10μm boxes were randomly selected for statistics).

[0022] Figure 5Figure 2 Effects of AR agonist Ostarine on the testosterone-AR signaling axis and AR downstream-regulated muscle tissue metabolic homeostasis in septic mice. A: Comparison of serum testosterone levels in mice after 5 days of treatment with the agonist Ostarine; B: Comparison of testosterone levels in gastrocnemius muscle tissue in mice after 5 days of treatment with the agonist Ostarine; C: Comparison of AR mRNA levels in gastrocnemius muscle tissue in mice after 5 days of treatment with the agonist Ostarine; D: Comparison of AR protein levels in gastrocnemius muscle tissue in mice after 5 days of treatment with the agonist Ostarine; E: Comparison of AR protein levels in gastrocnemius muscle tissue in mice after 5 days of treatment with the agonist Ostarine. Figure 3: Changes in protein anabolic pathways in mouse gastrocnemius muscle tissue after 5-day treatment with the agonist ostarine, and the corresponding relative quantitative analysis graph; F: Changes in protein catabolic pathways in mouse gastrocnemius muscle tissue after 5-day treatment with the agonist ostarine, and the corresponding relative quantitative analysis graph; G: Changes in the mRNA expression level of key genes for polyamine biosynthesis in mouse gastrocnemius muscle after 5-day treatment with the agonist ostarine; H: Changes in the mRNA expression level of key genes for fast-twitch and slow-twitch muscle fiber transition in mouse tibialis anterior muscle after 5-day treatment with the agonist ostarine; I: Immunofluorescence assessment of the distribution of fast and slow-twitch muscle fibers in the tibialis anterior muscle after 5-day treatment with the agonist ostarine;

[0023] Figure 6 , screening of potential upstream molecules that regulate AR down-regulated expression in the context of sepsis, A: relative expression changes of methylase family members detected by transcriptome sequencing; B: relative expression changes of deacetylase family (HDAC) members detected by transcriptome sequencing; C: relative expression changes of deacetylase family (Sirt) members detected by transcriptome sequencing; D: comparison of HDAC4 protein levels in gastrocnemius muscle tissue at different time points, and the corresponding relative quantitative analysis graph; E: effect of targeted inhibition of HDAC4 on expression changes of AR and HDAC4 mRNA levels in a cell model constructed by LPS.

[0024] Figure 7, the upstream key molecules that regulate AR down-regulation expression in the context of sepsis were determined. A: Silver staining of proteins that interact with the AR genomic region by DNA pulldown experiment using the AR promoter region; B: DNA Intersection of significantly differentially expressed genes screened by pulldown and transcriptome sequencing; C: Changes in the mRNA levels of AR and two candidate molecules in the gastrocnemius muscle tissue of mice at different time points; D: Changes in the protein levels of AR and two candidate molecules in the gastrocnemius muscle tissue of mice at different time points; E: Changes in the mRNA levels of Hnrnpa1 and AR after treatment of normal muscle C2C12 cell lines with siRNA targeting Hnrnpa1; F: Changes in the protein levels of Hnrnpa1 and AR after treatment of normal muscle C2C12 cell lines with siRNA targeting Hnrnpa1, and the corresponding relative quantitative analysis graphs; G: Changes in the protein levels of Hnrnpa1 and AR after treatment of LPS-induced inflammatory cell models with siRNA targeting Hnrnpa1, and the corresponding relative quantitative analysis graphs; H: Changes in the protein anabolic pathway after treatment of LPS-induced inflammatory cell models with siRNA targeting Hnrnpa1, and the corresponding relative quantitative analysis graphs; I: Changes in the protein catabolism pathway after treatment of LPS-induced inflammatory cell models with siRNA targeting Hnrnpa1, and the corresponding relative quantitative analysis graphs;

[0025] Figure 8 , the interaction between Hnrnpa1 and AR pre-mRNA, A: co-localization of immunofluorescence against Hnrnpa1 and fluorescence in situ hybridization against AR pre-mRNA; B: WB analysis of the presence of Hnrnpa1 in RIP experiment; C: qPCR analysis of the presence of AR pre-mRNA in RIP experiment. DETAILED DESCRIPTION

[0026] The technical solutions adopted in the present invention are as follows:

[0027] First: A classic sepsis mouse model was established using cecal puncture and ligation to evaluate sepsis and muscle atrophy phenotypes;

[0028] Second: Using the detection of the signaling molecule testosterone, as well as quantitative techniques at the mRNA and protein levels, we comprehensively analyzed the changes in the testosterone-AR signaling axis in skeletal muscle in the context of sepsis. We also evaluated the activity changes in biological processes regulated downstream of the AR, such as protein metabolic balance, polyamine biosynthesis, and fast-slow muscle transition, to elucidate the detailed mechanisms of the occurrence and development of sarcopenia in sepsis.

[0029] Third: Targeting septic mice with AR-selective agonists and employing physiological and biochemical assays and molecular quantitative techniques to further clarify the interventional effects of restoring AR expression on restoring homeostasis in biological processes such as protein metabolism, polyamine biosynthesis, and fast-slow muscle transition in skeletal muscle, as well as its role in improving sarcopenia and poor prognosis in sepsis.

[0030] 4: Use DNA-pulldown, transcriptome sequencing, siRNA targeted knockdown and other technologies to screen and identify the key upstream molecules that regulate AR down-regulation expression in the context of sepsis.

[0031] The animal experiments in this invention were approved by the ethics committee of our institution, ethics number: 2024AE01047.

[0032] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0033] Example 1

[0034] I. A classic mouse model of sepsis was established using cecal ligation and puncture (CLP). Phenotypic changes, including physiological parameters, weight, and muscle fiber counts, were assessed to confirm the phenotype of sepsis-induced sarcopenia. The specific procedures were as follows: a. Forty-eight 8-week-old male C57BL / 6J mice were randomly divided into an experimental group (n=24) (CLP modeling group) and a control group (n=24) to establish a sepsis mouse model. b. Serum and skeletal muscle samples (gastrocnemius, tibialis anterior, and soleus) were obtained from mice at four time points (24 hours, day 3, day 5, and day 7) and phenotypic changes were assessed using appropriate methods. Results showed that CLP significantly increased inflammatory factors and significantly decreased survival rate, indicating that the sepsis model was successfully established. Macroscopic weight assessment revealed that the total body weight and weight of the three skeletal muscles of CLP mice were significantly lower than those of the control group, and the forelimb grip strength was significantly reduced. Further microscopic muscle fiber assessment revealed that the muscle fibers of the three skeletal muscles in the CLP group were significantly atrophied. Figure 1 .

[0035] Example 2

[0036] 2. Exploring changes in the activity of the testosterone-AR signaling axis and its downstream regulation of skeletal muscle homeostasis

[0037] (1) a. Test the testosterone content in serum and skeletal muscle samples using a test kit; b. Use qPCR, WB, and immunohistochemistry to evaluate the expression of AR at the mRNA and protein levels in muscle tissue. The results showed that the expression of AR at both the mRNA and protein levels in the CLP group was significantly decreased, which led to the disorder of the regulatory activity of the testosterone-AR signaling axis. The results are shown in the attached figure. Figure 2 .

[0038] (2) a. WB was used to evaluate the protein expression changes of key pathway molecules related to AR-regulated downstream protein synthesis and catabolism in muscle tissue; b. qPCR technology was used to evaluate the mRNA expression changes of key molecules related to AR-regulated downstream polyamine biosynthesis and fast-slow muscle transition in muscle tissue; c. Immunofluorescence staining technology was used to evaluate the distribution of the proportion of fast and slow muscle fibers in muscle tissue. The results showed that protein anabolism in muscle tissue of the CLP group was significantly decreased, and protein catabolism was significantly increased. In addition, the mRNA expression levels of key genes for polyamine biosynthesis were significantly decreased. The slow muscle activation gene in the tibialis anterior muscle increased significantly from the 5th day, while the corresponding inhibitory factor MyoD was significantly downregulated at the four time points. Immunofluorescence showed that the slow muscle fibers in the tibialis anterior muscle of the CLP group increased significantly on the 5th day, while the fast muscle fibers decreased significantly, indicating that the regulatory activity of the testosterone-AR signaling axis was disturbed, resulting in the destruction of homeostasis in muscle tissue and causing sarcopenia. The results are shown in the attached figure for details. Figure 3 .

[0039] Example 3

[0040] 3. Clarify the effect of targeted activation of AR expression on skeletal muscle atrophy symptoms and adverse prognosis caused by sepsis.

[0041] (1) a. Experimental mice were pretreated with subcutaneous injection of AR agonist Ostarine, and then a classic sepsis model was constructed using CLP to evaluate changes in mouse mortality; b. Changes in mouse body weight, skeletal muscle weight, and forelimb grip strength were evaluated from a macroscopic perspective; c. Changes in the myofibers of three skeletal muscles were evaluated from a microscopic perspective. The results showed that the 5-day survival rate of the CLP+Ostarine group was significantly improved and significantly higher than that of the CLP+solvent group. In addition, Ostarine treatment significantly improved the forelimb grip strength of mice in the CLP group and restored it to the level of the control group. From a macroscopic weight perspective, although the weight of mice in the CLP+Ostarine group was significantly higher than that of the control group, the weight of mice in the CLP+Ostarine group was significantly higher than that of the CLP+solvent group at each time point, and Ostarine significantly prevented the weight loss of the three skeletal muscles. Microscopically, Ostarine treatment significantly improved the symptoms of myofiber atrophy in the three skeletal muscles. The results are detailed in the Appendix. Figure 4 .

[0042] (In the above experiments, ostarine (CAS: 841205-47-8) was purchased from MedChemExpress in the United States. The solution was prepared according to the instructions. Ostarine was dissolved in 10% dimethyl sulfoxide (DMSO) to create a stock solution. 40% PEG-300, 5% Tween-80, and 45% saline were then added in that order. For 1 mL of working solution, 100 μL of the 25.0 mg / mL clear DMSO stock solution was added to 400 μL of PEG-300 and mixed thoroughly. 50 μL of Tween-80 was then added to the solution, mixed thoroughly, and 450 μL of saline was added to bring the volume to 1 mL. The subcutaneous injection dose was based on the mouse's body weight, at a dose of 5 mg / kg, with a frequency of once daily. There are currently no available treatments for this disease, and exogenous nutritional therapy is the only available strategy, but this has been ineffective.)

[0043] (2) a. Use the kit to detect changes in testosterone content in serum and skeletal muscle samples; b. Use qPCR and WB techniques to evaluate changes in AR expression at the mRNA and protein levels in muscle tissue; c. Use WB to evaluate changes in protein expression of key pathway molecules related to AR-regulated downstream protein synthesis and catabolism in muscle tissue; d. Use qPCR technology to evaluate changes in mRNA expression of key molecules related to AR-regulated downstream polyamine biosynthesis and fast-slow muscle transition in muscle tissue; e. Use immunofluorescence staining technology to evaluate changes in the distribution of fast and slow muscle fibers in muscle tissue. The results showed that the serum testosterone level in the CLP+Ostarine group was significantly lower than that in the CLP+solvent group, and a similar trend was found in the gastrocnemius muscle tissue. In addition, Ostarine treatment significantly restored the mRNA and protein expression levels of AR in mice in the CLP group. For AR downstream regulatory pathways, Ostarine treatment rebuilt the protein synthesis / catabolism balance, polyamine biosynthesis homeostasis, and fast-slow muscle transition homeostasis in mice in the CLP group. The results are detailed in the Appendix. Figure 5 .

[0044] Example 4

[0045] 4. Identify the key upstream molecules that regulate AR downregulation in skeletal muscle in the context of sepsis

[0046] (1) a. Transcriptome sequencing was used to screen potential upstream molecules that regulate the downregulation of AR expression; b. WB was used to evaluate the changes in protein expression of potential upstream molecules at different time points, and targeted intervention reagents were used in cell models for verification and evaluation. The results showed that HDAC4 was significantly differentially expressed in enzymes from the perspective of epigenetic modification, and the potential molecule that was consistent with the significant downregulation of AR mRNA and protein levels was HDAC4. However, protein quantitative analysis found that the expression of HDAC4 in the CLP group was not significantly different from that in the control group. Further treatment of the LPS-constructed inflammatory cell model with a targeted inhibitor of HDAC4 revealed that inhibition of HDAC4 did not significantly restore the significant downregulation of AR mRNA induced by LPS, supporting that HDAC4 is not the key upstream molecule that regulates the downregulation of AR expression. The results are detailed in the Appendix. Figure 6 .

[0047] (2) a. DNA pulldown technology was used to screen potential inhibitory transcription factors or binding proteins that regulate AR downregulation, and further intersection with the corresponding transcriptome sequencing results was performed to narrow the scope of verification; b. qPCR and WB technology were used to evaluate the mRNA and protein expression changes of potential upstream molecules screened after intersection at different time points to identify candidate upstream molecules; c. siRNA technology was used to target and knock down candidate upstream molecules, and the best siRNA was screened; d. siRNA technology was used to target and treat LPS-constructed inflammatory cell models, and WB technology was used to evaluate the protein expression changes of candidate upstream molecules and AR, as well as the protein expression changes of key molecules in the protein synthesis and degradation pathways. The results showed that the 5-day survival rate of the CLP+Ostarine group was significantly improved and significantly higher than that of the CLP+solvent group. In addition, two candidate molecules, Hnrnpa1 and Sfpq, were screened after intersection. Further molecular quantitative analysis found that the expression changes of Hnrnpa1 had a good correspondence with the changes in AR, while there was no significant difference in Sfpq between the CLP group and the control group. Further targeted knockdown of Hnrnpa1 expression resulted in the screening of the most effective siRNA, si-769. Furthermore, in a cell model, it was demonstrated that knockdown of Hnrnpa1 expression could restore AR to the control level and restore the balance of protein synthesis and catabolism, supporting the idea that Hnrnpa1 is a key upstream molecule regulating AR downregulation. The results are detailed in the Appendix. Figure 7 .

[0048] (3) a. Immunofluorescence and fluorescence in situ hybridization were used to analyze the interaction between Hnrnpa1 and AR pre-mRNA; b. RNA binding protein immunoprecipitation (RIP) combined with WB and qPCR was used to evaluate the direct interaction between Hnrnpa1 and AR pre-mRNA. The results showed that Hnrnpa1 protein and AR pre-mRNA were significantly co-localized in the cell nucleus. Further RIP analysis showed that Hnrnpa1 can directly bind to AR pre-mRNA. Given that AR was significantly downregulated at both mRNA and protein levels, the RNA binding protein Hnrnpa1 may regulate the degradation of AR mRNA through post-transcriptional behavior. The results are detailed in the Appendix. Figure 8 .

[0049] In summary, the above examples used cecal ligation and puncture (CLP) to establish a sepsis mouse model and found that serum inflammatory factors (TNF-α, IL-6) were significantly elevated, survival rate decreased, and muscle atrophy (reduced muscle weight, decreased grip strength, and reduced muscle fiber cross-sectional area) occurred. Mechanistically, sepsis leads to downregulation of AR expression in muscle tissue, triggering enhanced protein catabolism (Atrogin-1 / MuRF1↑), weakened anabolism (p-AKT / p-mTOR↓), polyamine synthesis genes (AMD / ODC1 / SMOX↓), and slow muscle fiber conversion (MHC I and TnI-slow↑). After intervention with the AR agonist ostarine (5 mg / kg, subcutaneous injection), AR expression in septic mice was restored, the above metabolic imbalance was reversed, muscle atrophy was significantly improved, and the 5-day survival rate increased by 40%. Further screening revealed that the RNA-binding protein Hnrnpa1 regulates its expression by directly binding to AR pre-mRNA, and its targeted intervention can restore AR levels and muscle homeostasis.

[0050] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any form, and any technical solutions obtained by equivalent replacement or equivalent transformation fall within the scope of protection of the present invention.

Claims

1. Use of an AR agonist in the preparation of a medicament for treating sepsis-induced sarcopenia, characterized in that: The AR agonist is Ostarine.

2. The use according to claim 1, characterized in that: The drug is administered by subcutaneous injection.

3. The use according to claim 1 or 2, characterized in that: The treatment was performed within 5 days after the onset of sepsis.

4. The use according to claim 1, characterized in that: The drug works by restoring the balance between protein synthesis and catabolism in skeletal muscle, specifically by upregulating the expression of synthesis pathway proteins p-AKT and p-mTOR, and downregulating the expression of degradation pathway proteins Atrogin-1 and MuRF1.

5. The use according to claim 1, characterized in that: The drug is a drug that works by promoting the biosynthesis of polyamines in skeletal muscle, specifically by upregulating the expression of AMD, ODC1, and SMOX genes.

6. The use according to claim 1, characterized in that: The drug works by regulating the ratio of fast and slow muscle fibers, specifically inhibiting the expression of slow muscle fiber conversion genes MHC I and TnI-slow, and promoting the expression of fast muscle fiber activation gene MyoD.

7. The use according to claim 1, characterized in that: The drug can improve the survival rate of sepsis, and the 5-day survival rate is significantly higher than that of the untreated group.

8. A method for screening a drug for treating sepsis-induced sarcopenia, characterized in that: The ability of the test compound to regulate the RNA binding protein Hnrnpa1 is used as a screening indicator. The Hnrnpa1 regulates the expression of AR by binding to AR pre-mRNA.

9. A pharmaceutical preparation for treating sepsis-induced sarcopenia, characterized in that: The drug is in the form of an injection and contains a therapeutic amount of Ostarine.

10. The pharmaceutical preparation according to claim 1, characterized in that: The therapeutic dose is 5 mg / kg for mice.

Images