Application of S100A9 in treatment or detection of diabetic cardiomyopathy

Abstract

The invention relates to the field of biological medicine, in particular to application of S100A9 in treatment or detection of diabetic cardiomyopathy. The research finds that the expression of S100A9 in the heart tissue of a diabetic cardiomyopathy mouse is obviously increased. Overexpression of the S100A9 can aggravate myocardial injury and cardiac dysfunction, and inhibition of expression or activity of the S100A9 can improve illness conditions. Both the S100A9 inhibitor paquinimod and the macrophage scavenger chlorophosphonate liposome can reduce the concentration of S100A9 in serum, relieve cardiac enlargement and myocardial fibrosis and recover the left ventricular ejection fraction. In addition, the S100A9 can be used as a marker for detecting the diabetic cardiomyopathy, and related detection products can reflect the severity of the illness state by detecting the expression quantity of the S100A9 in tissue cells or body fluid. The invention provides a new target spot, medicine and detection means for treatment and detection of diabetic cardiomyopathy.

Description

Technical Field

[0001] The present invention relates to the field of biomedical technologies, and particularly to an application of S100A9 in the treatment or detection of diabetic cardiomyopathy. Background Art

[0002] Diabetes, as a global public health problem, is spreading at an alarming rate. According to authoritative predictions, the number of global diabetes patients will soar to 600 million by 2035. Behind this figure is a huge health burden and socio-economic pressure. Diabetic cardiomyopathy (DCM), as a specific complication of diabetes, seriously threatens the life and health of patients and is one of the important causes of heart failure. Deeply exploring the pathogenesis of DCM and finding effective treatment strategies have become key issues that urgently need to be overcome in the medical field.

[0003] Currently, the academic community generally believes that the pathogenesis of DCM is intricate and involves multiple aspects such as insulin resistance, oxidative stress, chronic inflammation, and mitochondrial dysfunction. Among them, chronic low-grade immune inflammation runs through the entire course of DCM and is regarded as one of the important characteristics. However, the interaction between macrophages and cardiomyocytes and its underlying molecular mechanism remain largely unclear. Macrophages, as an important part of the immune system, play a key role in the inflammatory response. The abnormal interaction between them and cardiomyocytes is very likely to be an important factor promoting the progression of DCM. If this relationship can be clarified, it will open up a new direction for the treatment of DCM.

[0004] S100A9 (calcium-binding protein A9), as an inflammatory mediator of innate immunity, has attracted much attention in the field of cardiovascular disease research in recent years. In diseases such as atherosclerosis and myocardial infarction, S100A9 has been proven to have a pro-inflammatory effect and can exacerbate the deterioration of the disease. Existing studies have shown that the S100A8 / A9 heterodimer (calprotectin) can have an adverse effect on myocardial contractile function by activating the RAGE receptor. Unfortunately, the specific mechanism of action of S100A9 in DCM has not been fully explored, which has to a certain extent restricted the development of precision treatment for DCM.

[0005] From the perspective of the current treatment situation, the existing treatment methods for DCM mainly focus on metabolic regulation and inflammation inhibition. Although these methods can relieve symptoms to a certain extent, due to the lack of precise intervention on specific molecular targets, the treatment effects are often unsatisfactory. For example, some drugs targeting inflammation inhibition may cause a series of adverse reactions while reducing the inflammation level, affecting the quality of life and long-term prognosis of patients. In addition, due to the complexity of the pathogenesis of DCM, a single treatment method is difficult to fundamentally block the disease process. Therefore, there is an urgent need for a specific intervention strategy that can target the key pathogenesis links of DCM to improve the treatment effect and the prognosis of patients.

[0006] In summary, revealing the mechanism of action of S100A9 in DCM not only helps us to deeply understand the pathogenesis of DCM, but also provides a theoretical basis for the development of targeted therapeutic methods. This has important clinical significance for improving the treatment level of DCM, reducing the mortality rate of patients, and improving the quality of life of patients. Based on such a background, the present invention is committed to exploring the application of S100A9 in the treatment or detection of diabetic cardiomyopathy, with a view to bringing new breakthroughs in this field. Summary of the Invention

[0007] In view of this, the purpose of the present invention is to provide an application of S100A9 in the treatment or detection of diabetic cardiomyopathy.

[0008] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] The present invention provides an application of S100A9 as a target in the preparation of a drug for treating diabetic cardiomyopathy or improving cardiac dysfunction in diabetic cardiomyopathy.

[0010] The present invention also provides an application of an S100A9 inhibitor in the preparation of a drug for treating diabetic cardiomyopathy or improving cardiac dysfunction in diabetic cardiomyopathy.

[0011] The present invention also provides an application of a macrophage scavenger in the preparation of a drug for treating diabetic cardiomyopathy or improving cardiac dysfunction in diabetic cardiomyopathy.

[0012] The present invention also provides an application of S100A9 as a biomarker in the preparation of a product for detecting diabetic cardiomyopathy. Among them, the product includes one of a chip and a kit, and is used to detect the expression level of S100A9 in tissue cells or body fluids. The severity of diabetic cardiomyopathy can be reflected by the S100A9 level. Preferably, the tissue cells include at least one of cardiomyocytes, macrophages, liver, brain, and kidney. The body fluids include at least one of serum, urine, and cerebrospinal fluid.

[0013] As a further optimized scheme of the present invention, the drug is used to treat diabetic cardiomyopathy by reducing the expression content of S100A9 or reducing the activity of S100A9.

[0014] As a further optimized scheme of the present invention, the administration method of the drug includes at least one of oral administration, intravenous injection, and intraperitoneal injection.

[0015] As a further optimized scheme of the present invention, the drug is any pharmaceutically acceptable dosage form, including at least one of tablets, capsules, injections, granules, suspensions, and solutions.

[0016] As a further optimized solution of the present invention, the cardiac dysfunction includes at least one of cardiac enlargement and myocardial fibrosis.

[0017] As a further optimized solution of the present invention, the S100A9 inhibitor includes pexidartinib.

[0018] As a further optimized solution of the present invention, the macrophage scavenger includes clodronate liposomes.

[0019] The present invention focuses on the application of S100A9 in the treatment or detection of diabetic cardiomyopathy. Through a variety of experimental models and detection methods, it demonstrates significant technical effects in many aspects:

[0020] 1. Using single-cell transcriptome analysis technology, immunofluorescence staining, and Western blot analysis, the present invention found that the mRNA and protein expression of S100A9 in the heart tissue of diabetic cardiomyopathy mice increased significantly, and were significantly elevated in both cardiomyocytes and macrophages. This indicates that S100A9 is closely related to the occurrence and development of diabetic cardiomyopathy, providing a theoretical basis for subsequent use of it as a therapeutic target and detection marker.

[0021] 2. The present invention constructed a cardiac-specific S100A9 overexpression mouse model. The results showed that overexpression of S100A9 in the hearts of diabetic cardiomyopathy mice led to a significant increase in heart volume, exacerbation of cardiac fibrosis, a decrease in left ventricular ejection fraction (LVEF), and a negative correlation with serum S100A9 levels. This further proves that overexpression of S100A9 is closely related to cardiac dysfunction in diabetic myocardial injury, and conversely illustrates the potential significance of inhibiting S100A9 expression or activity in improving cardiac function.

[0022] 3. The present invention treated diabetic cardiomyopathy mice with the S100A9 inhibitor pexidartinib (PAQ) and found that PAQ treatment could significantly reduce the serum S100A9 concentration in diabetic cardiomyopathy mice, significantly relieve cardiac enlargement and myocardial fibrosis, significantly restore the left ventricular ejection fraction (LVEF), and was negatively correlated with serum S100A9 levels. This indicates that inhibition of S100A9 can improve cardiac dysfunction in diabetic cardiomyopathy, providing an effective drug intervention strategy for the treatment of diabetic cardiomyopathy.

[0023] 4. The present invention uses clodronate liposomes to eliminate macrophages in diabetic cardiomyopathy mice. After one month of treatment, the left ventricular ejection fraction (LVEF) of the mice is significantly improved, which is negatively correlated with the serum S100A9 level. The number of F4 / 80+CCR2+S100A9+ macrophages in the heart is significantly reduced, and cardiac enlargement and myocardial fibrosis are restored. This indicates that the elimination of macrophages has a significant improvement effect on the cardiac function of diabetic cardiomyopathy, revealing the important role of macrophages in the development of diabetic cardiomyopathy and the feasibility of intervening macrophages to treat diabetic cardiomyopathy.

[0024] 5. By using S100a9 flox / flox in Lyz2-Cre mice to knockout S100A9 in macrophages, it is found that the cardiac function of macrophages-specific S100A9 knockout mice is significantly improved, the left ventricular ejection fraction (LVEF) is significantly restored, which is negatively correlated with the serum S100A9 level, the degree of myocardial fibrosis is significantly reduced, and the number of F4 / 80 + CCR2 + S100A9 + macrophages in the heart is reduced, and the inflammatory response is inhibited. It shows that the knockout of macrophages-specific S100A9 can effectively improve the cardiac dysfunction of diabetic cardiomyopathy, further clarifying the key role of S100A9 in the process of macrophages affecting diabetic cardiomyopathy.

[0025] 6. The present invention uses S100A9 as a marker for preparing products for detecting diabetic cardiomyopathy, such as chips and kits, which can detect the expression level of S100A9 in tissue cells (including cardiomyocytes, macrophages, liver, brain, kidneys, etc.) or body fluids (including serum, urine, cerebrospinal fluid, etc.). The severity of diabetic cardiomyopathy is reflected by the S100A9 level, providing a new detection method for the early diagnosis and disease monitoring of diabetic cardiomyopathy. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0027] Figure 1 Verification of the expression of S100A9 in diabetic cardiomyopathy; wherein, Figure 1 a shows the expression of S100A9 in the heart tissue of diabetic cardiomyopathy mice analyzed by single-cell transcriptome analysis technology; Figure 1b shows the localization of S100A9, cardiomyocyte marker α-actinin, and myeloid cell marker CD11b in diabetic heart tissue. Figure 1 c represents the protein and mRNA expression levels of S100A9 in the heart tissue of diabetic cardiomyopathy mice.

[0028] Figure 2 shows the effect of S100A9 overexpression on the cardiac function of diabetic cardiomyopathy mice; among them, Figure 2 a shows the cardiac-specific overexpression of S100A9 in diabetic cardiomyopathy mice by tail vein injection of adeno-associated virus (AAV9-S100a9 / AAV9-GFP), Figure 2 b shows the morphological changes in the heart after S100A9 overexpression in diabetic cardiomyopathy mice, Figure 2 c shows the changes in left ventricular ejection fraction (LVEF) after S100A9 overexpression in diabetic cardiomyopathy mice, Figure 2 d is a scatter plot of the correlation between left ventricular ejection fraction (LVEF) and serum S100A9.

[0029] Figure 3 shows the effect of S100A9 inhibitor on the cardiac function of diabetic cardiomyopathy mice; among them, Figure 3 a shows the effect of S100A9 inhibitor Paquinimod (PAQ) on the serum S100A9 concentration in diabetic cardiomyopathy mice, Figure 3 b shows the morphological changes in the heart after PAQ treatment, Figure 3 c shows the changes in left ventricular ejection fraction (LVEF) after PAQ treatment, Figure 3 d is a scatter plot of the correlation between left ventricular ejection fraction (LVEF) and serum S100A9.

[0030] Figure 4 shows the effect of macrophage depletion on the cardiac function of diabetic cardiomyopathy mice; among them, Figure 4 A shows the changes in left ventricular ejection fraction (LVEF) after depleting macrophages in diabetic cardiomyopathy mice using clodronate liposomes, Figure 4 b is a scatter plot of the correlation between left ventricular ejection fraction (LVEF) and serum S100A9 after clodronate liposome treatment, Figure 4 c is F4 / 80 in the heart + CCR2 + S100A9 + immunofluorescence staining of macrophages, Figure 4 d shows the morphological changes in the heart after clodronate liposome treatment, Figure 4 e shows the effect of clodronate liposome treatment on the levels of various inflammatory factors in the serum of diabetic cardiomyopathy mice.

[0031] Figure 5 To investigate the effect of macrophage-specific S100A9 conditional knockout on cardiac function in diabetic cardiomyopathy mice. Among them, Figure 5 a represents S100a9 with macrophage-specific S100A9 conditionally knocked out flox / flox After simulating diabetic cardiomyopathy in Lyz2-Cre mice by STZ injection and high-fat diet, the S100A9 protein level in bone marrow-derived macrophages (BMDM) was detected. Figure 5 b shows the change in left ventricular ejection fraction (LVEF) in the knockout mice. Figure 5 c is the scatter plot of the correlation between left ventricular ejection fraction (LVEF) and serum S100A9 in the knockout mice. Figure 5 d shows the morphological changes in the hearts of the knockout mice. Figure 5 e is F4 / 80 + CCR2 + S100A9 + Immunofluorescence staining of macrophages. Figure 5 f shows the effect of S100A9 knockout on the levels of various inflammatory factors in the serum of diabetic cardiomyopathy mice. Specific implementation manner

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. For those not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturer are followed. For reagents or instruments without indicating the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0033] 1. Construction of diabetic cardiomyopathy mouse model

[0034] All the mice used in this experiment were constructed on the genetic background of C57BL strain mice. db / db mice are spontaneous diabetic cardiomyopathy mice constructed by homozygous mutation of the Leptin receptor (Lepr) under the genetic background of C57BL / BKS mice. Male C57BL / 6J (6 weeks old), db / bks (8 weeks old) and db / db (8 weeks old) mice were all purchased from Jicuiyaokang Laboratory Animal Technology Co., Ltd. (Beijing, China), and all the mice were housed in the Laboratory Animal Center of Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology (SPF level). All mice underwent a two-week purification and adaptation period before the experiment, with free access to food and water every day, a normal 12-hour light-dark cycle, and the room temperature maintained at 26 °C. The SD rats and neonatal mice experiments involved in this experiment were all acute treatment experiments (extracting tissues and peripheral blood mononuclear cells, primary cardiomyocytes), and the male SD rats (8 weeks old) and neonatal mice (within 3 days) used were all purchased from Jicuiyaokang Laboratory Animal Technology Co., Ltd. (Beijing, China). All animal experiments involved in this study were reviewed and approved by the Ethics Review Committee of Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology (Approval No.: 2953).

[0035] Streptozocin-high-fat diet combined-induced diabetic cardiomyopathy mouse model (STZ-HFD model): After a two-week adaptation period, male 6-week-old C57BL / 6J mice were fed a high-fat diet (60% fat; D12492, ResearchDiets, USA) for 6 weeks, and then intraperitoneally injected with streptozocin (STZ; Sigma-Aldrich Technology, Germany). STZ was dissolved in citrate buffer (C1013, pH 4.5, Solarbio, China), prepared freshly before use, stored on ice bath, and continuously injected at a low dose of 50 mg / kg per day for 5 days. After STZ injection, the mice were in a state of polydipsia and polyuria, and it was necessary to ensure sufficient daily water supply and change the bedding in time. Control mice were intraperitoneally injected with an equal volume of citrate buffer. Five days after STZ injection, the random blood glucose of the mice was measured by the tail clipping method. The mice in the diabetic cardiomyopathy group continued to be fed a high-fat diet, and the control group mice were supplied with a normal diet. Subsequently, a small animal ultrasound machine was used to perform transthoracic echocardiography to monitor the cardiac function of the mice to confirm the successful establishment of the diabetic cardiomyopathy model. After the cardiac function test, the mice were sacrificed by intraperitoneal injection of sodium pentobarbital (100 mg / kg) to collect tissues and sera for subsequent experiments.

[0036] db / db Spontaneously Diabetic Cardiomyopathy Mouse Model (db / db Model): Leptin receptor deficiency leads to the development of hyperinsulinemia within 2 weeks after birth, progresses to obesity within 3 - 4 weeks, and shows diabetic phenotypes after 8 - 10 weeks. After a two - week adaptation period, male 8 - week - old db / db mice and corresponding - age db / bks mice had their random blood glucose measured using the tail - snipping method. Both groups of mice were continued to be fed a normal diet, and then a small - animal ultrasound machine was used to perform transthoracic echocardiography to monitor the cardiac function of the mice, confirming the successful establishment of the diabetic cardiomyopathy model. After the cardiac function test, the mice were sacrificed by intraperitoneal injection of sodium pentobarbital (100 mg / kg) to collect tissues and sera for subsequent experiments.

[0037] Figure 1 For the expression verification of S100A9 in diabetic cardiomyopathy. Through single - cell transcriptome analysis technology, the expression of S100A9 in the cardiac tissues of diabetic cardiomyopathy mice was detected ( Figure 1 a). The results showed that compared with normal control mice, the mRNA and protein expressions of S100A9 in the cardiac tissues of diabetic cardiomyopathy mice were significantly increased. Further verification was carried out by immunofluorescence staining ( Figure 1 b), and S100A9 was co - localized with the cardiomyocyte marker α - actinin and the myeloid cell marker CD11b in the diabetic heart tissues, indicating that S100A9 was significantly increased in both cardiomyocytes and macrophages. Further Western blot analysis also confirmed that the protein expression level of S100A9 in diabetic cardiac tissues was significantly higher than that in the control group ( Figure 1 c), showing that S100A9 was closely related to the occurrence and development of diabetic cardiomyopathy.

[0038] 2. Construction of a Mouse Model with Cardiac - Specific Overexpression of S100A9

[0039] 1×10¹¹ v.g. of AAV9 - cTNT - S100a9 (generated by Shanghai OBiOTechnology, abbreviated as AAV9 - S100a9) was injected via the tail vein, while control mice were injected with AAV9 - cTNT - GFP (generated by Shanghai OBiOTechnology, abbreviated as AAV9 - GFP). Adeno - associated virus was injected into db / bks and db / db mice twice at 10 weeks and 18 weeks respectively.

[0040] Figure 2 For the effect of S100A9 overexpression on the cardiac function of diabetic cardiomyopathy mice. Cardiac - specific overexpression of S100A9 in diabetic cardiomyopathy mice was achieved by injecting adeno - associated virus (AAV9 - S100a9 / AAV9 - GFP) via the tail vein ( Figure 2a). The results showed that overexpression of S100A9 in the hearts of diabetic cardiomyopathy mice led to a significant increase in heart volume and exacerbation of cardiac fibrosis ( Figure 2 b). Detection by echocardiography revealed a decrease in the left ventricular ejection fraction (LVEF) in diabetic cardiomyopathy mice ( Figure 2 c), and it was negatively correlated with the level of serum S100A9 ( Figure 2 d), indicating that overexpression of S100A9 was closely related to cardiac dysfunction in diabetic myocardial injury.

[0041] 3. Application of S100A9 inhibitor in diabetic cardiomyopathy mice

[0042] In the STZ-HFD model group, starting from the 15th week, and in the db / db model group, starting from the 12th week, paquinimod (10 mg / kg, paquinimod, PAQ) drug intervention was given. The drug was administered once a day by oral gavage for a total of 10 weeks.

[0043] The S100A9 inhibitor Paquinimod was used to treat diabetic cardiomyopathy mice for 10 weeks ( Figure 3 a). The results showed that PAQ treatment could significantly reduce the concentration of serum S100A9 in diabetic cardiomyopathy mice ( Figure 3 a), and significantly relieve the phenomena of heart enlargement and myocardial fibrosis in diabetic cardiomyopathy mice ( Figure 3 b). At the same time, the left ventricular ejection fraction (LVEF) of diabetic cardiomyopathy mice was significantly restored ( Figure 3 c), and it was negatively correlated with the serum S100A9 level ( Figure 3 d). The above results indicated that inhibition of S100A9 could improve cardiac dysfunction in diabetic cardiomyopathy.

[0044] 4. Construction of macrophage-depleted mouse model

[0045] To eliminate macrophages, diabetic cardiomyopathy mice (STZ+HFD) were randomly assigned to receive intraperitoneal injection of 100 μL of 5 mg / mL clodronate liposomes (40337ES08, Yeasen Biotechnology, Shanghai) or the same amount of control liposomes (PBS) (40338ES08, Yeasen). During the study period, each group was injected with such drugs four times.

[0046] Clodronate liposomes were used to deplete macrophages in diabetic cardiomyopathy mice ( Figure 4 a). After one month of treatment, echocardiography results showed that the left ventricular ejection fraction (LVEF) of diabetic cardiomyopathy mice was significantly improved ( Figure 4 a), and it was negatively correlated with the serum S100A9 level ( Figure 4b). F4 / 80 in the hearts of diabetic cardiomyopathy mice + CCR2 + S100A9 + The number of macrophages was significantly reduced ( Figure 4 c). The cardiac enlargement and myocardial fibrosis in diabetic cardiomyopathy mice were also restored after macrophage depletion ( Figure 4 d), and the expression of various inflammatory factors in the serum decreased ( Figure 4 e), indicating that the inflammatory response in the heart was also inhibited. The above results suggest that macrophage depletion has a significant improvement effect on the cardiac function of diabetic cardiomyopathy.

[0047] 5. Construction of macrophage-specific S100A9 knockout mouse model

[0048] S100a9 flox / flox Mice (NM-CKO-226344) and Lyz2-Cre mice (NMX-KI-192007) were purchased from Shanghai Model Organisms Center, Inc. Macrophage-specific S100A9 gene knockout mice (S100a9flox / floxLyz2-Cre) were obtained by mating S100a9 flox / flox with Lyz2-Cre mice. S100a9 flox / flox Lyz2-Cre and control mice (S100a9 flox / flox ) were modeled with diabetes by STZ injection and high-fat diet.

[0049] By using S100a9 flox / flox Lyz2-Cre mice, S100A9 in macrophages was knocked out in diabetic cardiomyopathy mice ( Figure 5 a). It was found that the cardiac function of macrophage-specific S100A9 knockout mice was significantly improved. Echocardiography showed that the left ventricular ejection fraction (LVEF) of macrophage-specific S100A9 knockout mice was significantly restored ( Figure 5 b), and it was negatively correlated with the serum S100A9 level ( Figure 5 c), and the degree of myocardial fibrosis in the heart was also significantly reduced ( Figure 5 d). Meanwhile, the number of F4 / 80 + CCR2 + S100A9 + macrophages in the hearts of macrophage-specific S100A9 knockout mice was reduced ( Figure 5 e), and the expression of various inflammatory factors in the serum decreased ( Figure 5 f), indicating that the inflammatory response in the heart was also inhibited. The above results suggest that knockout of macrophage-specific S100A9 can effectively improve cardiac dysfunction in diabetic cardiomyopathy.

[0050] 6. Cardiac function assessment

[0051] The cardiac function of mice was evaluated using a VINNO6VET (VINNO Technology, Suzhou, China) small animal ultrasound machine. The baseline cardiac function of mice was measured after a 2-week adaptation period to exclude baseline deviation. At the same time, transthoracic echocardiography was performed again at the end point of drug intervention to evaluate the modeling and drug intervention effects. Mice were anesthetized with isoflurane gas mixed with air at a flow rate of 3 - 4 L / min through a face mask. A flow rate of 3% isoflurane was used for induction of anesthesia, and a flow rate of 1 - 1.5% isoflurane was used for maintenance of anesthesia. The heart rate of mice was maintained between 350 - 450 beats per minute.

[0052] Left ventricular related parameters of mice were measured in the left ventricular short-axis section, including left ventricular end-systolic diameter (LVIDs), left ventricular end-diastolic diameter (LVIDd), left ventricular posterior wall end-systolic thickness (LVPWs), left ventricular posterior wall end-diastolic thickness (LVPWd), interventricular septum end-systolic thickness (IVSs), and interventricular septum end-diastolic thickness (IVSd). Left ventricular end-systolic volume (LVESV), left ventricular end-diastolic volume (LVEDV), left ventricular ejection fraction (LVEF), and left ventricular fractional shortening (LVFS) were automatically calculated based on the measured parameters. The peak velocity E of early left ventricular diastolic blood flow, the peak velocity A of late left ventricular diastolic blood flow, the peak velocity e' of early diastolic mitral annulus root, the E-wave deceleration time (EDT), and the isovolumic relaxation time (IVRT) were measured in the four-chamber view. The above cardiac parameters were measured after at least 3 independent cardiac cycles were stable. The echocardiography operator was unaware of the grouping of mice.

[0053] 7. Detection of biochemical indicators

[0054] Detection of serum S100A9 level: The concentration of S100A9 in mouse serum was detected using a mouse S100A9 ELISA kit (EK1152, Boster).

[0055] Detection of inflammatory factors: Multiple serum inflammatory factors were detected using an ABplex mouse 20-Plex panel ELISA kit (RK04394, Abclonal) or an ABplex mouse 15-Plex panel ELISA kit (RK05203, Abclonal).

[0056] The above are only the preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be regarded as a limitation of the present invention. The protection scope of the present invention should be defined by the scope of the claims. For those of ordinary skill in the art in this technical field, without departing from the spirit and scope of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as within the protection scope of the present invention.

Claims

1. Application of S100A9 as a target in the preparation of drugs for treating diabetic cardiomyopathy or improving cardiac dysfunction caused by diabetic cardiomyopathy.

2. Use of S100A9 inhibitors in the preparation of drugs for treating diabetic cardiomyopathy or improving cardiac dysfunction caused by diabetic cardiomyopathy.

3. Use of macrophage scavengers in the preparation of drugs for treating diabetic cardiomyopathy or improving cardiac dysfunction caused by diabetic cardiomyopathy.

4. Application of S100A9 as a marker in the preparation of products for detecting diabetic cardiomyopathy.

5. The use according to any one of claims 1 to 3, characterized in that: The drug is used for treating diabetic cardiomyopathy by reducing the expression content of S100A9 or reducing the activity of S100A9.

6. The use according to any one of claims 1 to 3, characterized in that: The administration method of the drug includes at least one of oral administration, intravenous injection and intraperitoneal injection.

7. The use according to any one of claims 1 to 3, characterized in that: The drug is in any pharmaceutically acceptable dosage form, including at least one of tablets, capsules, injections, granules, suspensions and solutions.

8. The use according to any one of claims 1 to 3, characterized in that: The cardiac dysfunction includes at least one of cardiac enlargement and myocardial fibrosis.

9. The use according to claim 2, characterized in that: The S100A9 inhibitors include paquinimod.

10. The use according to claim 3, characterized in that: The macrophage depleting agent includes liposome clodronate.

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