Fibrosis In Diabetic Cardiomyopathy Research Articles

Tinglu Yixin granule inhibited fibroblast-myofibroblast transdifferentiation to ameliorate myocardial fibrosis in diabetic mice

Ethnopharmacological relevanceMyocardial fibrosis is one of the pathological characteristics of advanced diabetic cardiomyopathy (DCM) and serves as the strong evidence of poor prognosis. Among them, the transdifferentiation of cardiac fibroblasts (CFs) may play a crucial role in the development of myocardial fibrosis in DCM. Tinglu Yixin granule (TLYXG) has been clinically used for many years and can significantly improve cardiac function of patients with DCM. However, the effect of TLYXG on myocardial fibrosis in DCM remains unknown, and the underlying mechanisms of its efficacy have yet to be fully understood. Aim of the studyThis study aimed to investigate the impact and underlying mechanism of TLYXG on myocardial fibrosis in diabetes mice. Materials and methodsThe bioactive compounds in TLYXG were identified using ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). The potential mechanism of TLYXG in treating DCM was predicted using network pharmacology combined with molecular docking and protein-protein docking. The mice model of type 2 diabetes were established by intraperitoneal injection of streptozotocin (STZ) and the high-fat diet (HFD). Indicators of pancreatic islet function, lipids, oxidative stress, and inflammatory factors were tested using kits. Cardiac function was assessed in diabetic mice using echocardiography. Histologic staining was performed to evaluate myocardial hypertrophy and fibrosis. Mechanistically, the hypothesis was tested through rescue experiments. The expression levels of transient receptor potential channel 6 (TRPC6), transforming growth factor-β1 (TGF-β1), collagen I (COL-I) and alpha-smooth muscle actin (α-SMA), along with the mRNA and phosphorylation levels of SMAD family member 3 (Smad3) and protein 38 mitogen-activated protein kinase (p38 MAPK), were assessed using quantitative RT-qPCR, western blot, immunohistochemistry, and immunofluorescence. Neonatal lactating mice were used to extract primary CFs for vitro experiments. Scratch and transwell assays were conducted to assess CFs migration and invasion abilities. Western blot and immunofluorescence were used to evaluate the expression levels of CFs transdifferentiation markers COL-I and α-SMA. ResultsA total of 168 active ingredients were detected in TLYXG based on UPLC-MS and databases. Network pharmacology indicated that TLYXG could improve DCM through inflammatory mediator regulation of TRP channels, TGF-beta signaling pathway, and MAPK signaling pathway. ELISA results showed that TLYXG could ameliorate metabolic levels, inflammation, and oxidative stress in diabetic mice. Echocardiography suggested that TLYXG improved cardiac systolic and diastolic dysfunction in diabetic mice. Histological analysis revealed that TLYXG alleviated myocardial fibrosis in diabetes mice. Additionally, molecular docking analysis indicated strong binding activity between the main active ingredients of TLYXG and TRPC6 of the TRP family. At the molecular level, TLYXG reduced the mRNA and protein expression levels of TRPC6 and TGF-β1 and inhibited the mRNA and phosphorylation levels of Smad3 and p38 MAPK. Furthermore, TLYXG inhibited CFs migration and invasion, and reduced the expression levels of the CFs transdifferentiation markers COL-I and α-SMA. ConclusionTLYXG inhibited the proliferation, migration, invasion and transdifferentiation of CFs by suppressing TGF-β1/Smad3/p38 MAPK signaling through down-regulation of TRPC6, thereby ameliorating myocardial fibrosis in diabetes mice.

Cannabinoid 2 Receptor Activation Protects against Diabetic Cardiomyopathy through Inhibition of AGE/RAGE-Induced Oxidative Stress, Fibrosis, and Inflammasome Activation.

Oxidative stress, fibrosis, and inflammasome activation from advanced glycation end product (AGE)-receptor of advanced glycation end product (RAGE) interaction contribute to diabetic cardiomyopathy (DCM) formation and progression. Our study revealed the impact of β-caryophyllene (BCP) on activating cannabinoid type 2 receptors (CB2Rs) against diabetic complication, mainly cardiomyopathy and investigated the underlying cell signaling pathways in mice. The murine model of DCM was developed by feeding a high-fat diet with streptozotocin injections. After the development of diabetes, the animals received a 12-week oral BCP treatment at a dose of 50 mg/kg/body weight. BCP treatment showed significant improvement in glucose tolerance and insulin resistance and enhanced serum insulin levels in diabetic animals. BCP treatment effectively reversed the heart remodeling and restored the phosphorylated troponin I and sarcoplasmic/endoplasmic reticulum Ca2+ ATPase 2a expression. Ultrastructural examination showed reduced myocardial cell injury in DCM mice treated with BCP. The preserved myocytes were found to be associated with reduced expression of AGE/RAGE in DCM mice hearts. BCP treatment mitigated oxidative stress by inhibiting expression of NADPH oxidase 4 and activating phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/nuclear factor erythroid 2-related factor 2 (Nrf2) signaling. Also, BCP suppressed cardiac fibrosis and endothelial-to-mesenchymal transition in DCM mice by inhibiting transforming growth factor β (TGF-β)/suppressor of mothers against decapentaplegic (Smad) signaling. Further, BCP treatment suppressed nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3) inflammasome activation in DCM mice and alleviated cellular injury to the pancreatic tissues evidenced by significant elevation of the number of insulin-positive cells. To demonstrate a CB2R-dependent mechanism of BCP, another group of DCM mice were pretreated with AM630, a CB2R antagonist. AM630 was observed to abrogate the beneficial effects of BCP in DCM mice. Taken together, BCP demonstrated the potential to protect the myocardium and pancreas of DCM mice mediating CB2R-dependent mechanisms. SIGNIFICANCE STATEMENT: BCP, a CB2R agonist, shows protection against DCM. BCP attenuates oxidative stress, inflammation, and fibrosis in DCM via activating CB2Rs. BCP mediating CB2R activation favorably modulates AGE/RAGE, PI3K/AKT/Nrf2β and TGF-β/Smad and (NLRP3) inflammasome in diabetic cardiomyopathy.

Early detection of cardiac fibrosis in diabetic mice by targeting myocardiopathy and matrix metalloproteinase 2

Early detection of myocardial fibrosis in diabetic cardiomyopathy (DCM) has significant clinical implications for diabetes management. In this study, we identified matrix metalloproteinase 2 (MMP2) as a potential biomarker for early fibrosis detection. Based on this finding, we designed a dual-targeting nanoparticle CHP-SPIO-ab MMP2 to specifically target myocardiopathy and MMP2, enabling sensitive fibrosis detection using magnetic resonance imaging (MRI). Our results demonstrate that collagen hyperplasia (early fiber formation) begins to develop in diabetic mice at 12 weeks old, with observable fibrosis occurring at 16 weeks old. Additionally, MMP2 expression significantly up-regulates around collagen starting from 12 weeks of age. T2 MRI analysis revealed significant T2% enhancement in the hearts of 12-week-old diabetic mice following administration of the CHP-SPIO-ab MMP2 probe, indicating noninvasive detection of fiber formation. Furthermore, after fibrosis treatment, a reduction in T2% signal was observed in the hearts of 16-week-old diabetic mice. These findings were supported by Sirius red and Prussian blue staining techniques. Overall, our study presents a promising strategy for early identification of myocardial fibrosis. Statement of significanceMyocardial damage typically exhibits irreversibility, underscoring the paramount importance of early fibrosis diagnosis. However, the clinical used T1 mapping for fibrosis detection still exhibits limitations in terms of sensitivity. Therefore, it is imperative to develop highly sensitive strategies for early cardiac fibrosis detection. Here, we investigated the development of myocardial fibrosis in diabetic mice, and designed a highly sensitive probe that specifically targets cardiomyopathy and high expression of MMP2 for the early diagnosis of fibrosis. The probe enables non-invasive detection of abnormalities through MRI imaging as soon as fiber deposition appear, which can be detected earlier than T1 mapping. This advancement holds great potential for clinical diagnosis of myocardial fibrosis using cardiac magnetic resonance.

CircRNA_012164/MicroRNA-9-5p axis mediates cardiac fibrosis in diabetic cardiomyopathy.

Noncoding RNAs play a part in many chronic diseases and interact with each other to regulate gene expression. MicroRNA-9-5p (miR9) has been thought to be a potential inhibitor of diabetic cardiomyopathy. Here we examined the role of miR9 in regulating cardiac fibrosis in the context of diabetic cardiomyopathy. We further expanded our studies through investigation of a regulatory circularRNA, circRNA_012164, on the action of miR9. We showed at both the in vivo and in vitro level that glucose induced downregulation of miR9 and upregulation of circRNA_012164 resulted in the subsequent upregulation of downstream fibrotic genes. Further, knockdown of circRNA_012164 shows protective effects in cardiac endothelial cells and reverses increased transcription of genes associated with fibrosis and fibroblast proliferation through a regulatory axis with miR9. This study presents a novel regulatory axis involving noncoding RNA that is evidently important in the development of cardiac fibrosis in diabetic cardiomyopathy.

Salvianolic acid B ameliorates myocardial fibrosis in diabetic cardiomyopathy by deubiquitinating Smad7

BackgroundSalvianolic acid B (Sal B), a water-soluble phenolic compound derived from Salvia miltiorrhiza Bunge, is commonly used in Traditional Chinese Medicine to treat cardiovascular disease. In our previous study, Sal B protected against myocardial fibrosis induced by diabetic cardiomyopathy (DCM). This study aimed to investigate the ameliorative effects and potential mechanisms of Sal B in mitigating myocardial fibrosis induced by DCM.MethodsVarious methods were used to investigate the effects of Sal B on myocardial fibrosis induced by DCM in vivo and in vitro. These methods included blood glucose measurement, echocardiography, HE staining, Masson’s trichrome staining, Sirius red staining, cell proliferation assessment, determination of hydroxyproline levels, immunohistochemical staining, evaluation of fibrosis-related protein expression (Collagen-I, Collagen-III, TGF-β1, p-Smad3, Smad3, Smad7, and α-smooth muscle actin), analysis of Smad7 gene expression, and analysis of Smad7 ubiquitin modification.ResultsThe animal test results indicated that Sal B significantly improved cardiac function, inhibited collagen deposition and phenotypic transformation, and ameliorated myocardial fibrosis in DCM by upregulating Smad7, thereby inhibiting the TGF-β1 signaling pathway. In addition, cell experiments demonstrated that Sal B significantly inhibited the proliferation, migration, phenotypic transformation, and collagen secretion of cardiac fibroblasts (CFs) induced by high glucose (HG). Sal B significantly decreased the ubiquitination of Smad7 and stabilized the protein expression of Smad7, thereby increasing the protein expression of Smad7 in CFs and inhibiting the TGF-β1 signaling pathway, which may be the potential mechanism by which Sal B mitigates myocardial fibrosis induced by DCM.ConclusionThis study revealed that Sal B can improve myocardial fibrosis in DCM by deubiquitinating Smad7, stabilizing the protein expression of Smad7, and blocking the TGF-β1 signaling pathway.

The CREG1-FBXO27-LAMP2 axis alleviates diabetic cardiomyopathy by promoting autophagy in cardiomyocytes

Autophagy plays an important role in the development of diabetic cardiomyopathy. Cellular repressor of E1A-stimulated genes 1 (CREG1) is an important myocardial protective factor. The aim of this study was to investigate the effects and mechanisms of CREG1 in diabetic cardiomyopathy. Male C57BL/6 J mice, Creg1 transgenic mice and cardiac-specific knockout mice were used to establish a type 2 diabetes model. Small animal ultrasound, Masson’s staining and western blotting were used to evaluate cardiac function, myocardial fibrosis and autophagy. Neonatal mouse cardiomyocytes (NMCMs) were stimulated with palmitate, and the effects of CREG1 on NMCMs autophagy were examined. CREG1 deficiency exacerbated cardiac dysfunction, cardiac hypertrophy and fibrosis in mice with diabetic cardiomyopathy, which was accompanied by exacerbated autophagy dysfunction. CREG1 overexpression improved cardiac function and ameliorated cardiac hypertrophy and fibrosis in diabetic cardiomyopathy by improving autophagy. CREG1 protein expression was decreased in palmitate-induced NMCMs. CREG1 knockdown exacerbated cardiomyocyte hypertrophy and inhibited autophagy. CREG1 overexpression inhibited cardiomyocyte hypertrophy and improved autophagy. LAMP2 overexpression reversed the effect of CREG1 knockdown on palmitate-induced inhibition of cardiomyocyte autophagy. CREG1 inhibited LAMP2 protein degradation by inhibiting the protein expression of F-box protein 27 (FBXO27). Our findings indicate new roles of CREG1 in the development of diabetic cardiomyopathy.

NPRC deletion attenuates cardiac fibrosis in diabetic mice by activating PKA/PKG and inhibiting TGF-β1/Smad pathways.

Cardiac fibrosis plays a key role in the progression of diabetic cardiomyopathy (DCM). Previous studies demonstrated the cardioprotective effects of natriuretic peptides. However, the effects of natriuretic peptide receptor C (NPRC) on cardiac fibrosis in DCM remains unknown. Here, we observed that myocardial NPRC expression was increased in mice and patients with DCM. NPRC-/- diabetic mice showed alleviated cardiac fibrosis, as well as improved cardiac function and remodeling. NPRC knockdown in both cardiac fibroblasts and cardiomyocytes decreased collagen synthesis and proliferation of cardiac fibroblasts. RNA sequencing identified that NPRC deletion up-regulated the expression of TGF-β-induced factor homeobox 1 (TGIF1), which inhibited the phosphorylation of Smad2/3. Furthermore, TGIF1 up-regulation was mediated by the activation of cAMP/PKA and cGMP/PKG signaling induced by NPRC deletion. These findings suggest that NPRC deletion attenuated cardiac fibrosis and improved cardiac remodeling and function in diabetic mice, providing a promising approach to the treatment of diabetic cardiac fibrosis.

The Role of Cardiac Fibrosis in Diabetic Cardiomyopathy: From Pathophysiology to Clinical Diagnostic Tools.

Diabetes mellitus (DM) is a chronic metabolic disorder characterized by hyperglycemia due to inadequate insulin secretion, resistance, or both. The cardiovascular complications of DM are the leading cause of morbidity and mortality in diabetic patients. There are three major types of pathophysiologic cardiac remodeling including coronary artery atherosclerosis, cardiac autonomic neuropathy, and DM cardiomyopathy in patients with DM. DM cardiomyopathy is a distinct cardiomyopathy characterized by myocardial dysfunction in the absence of coronary artery disease, hypertension, and valvular heart disease. Cardiac fibrosis, defined as the excessive deposition of extracellular matrix (ECM) proteins, is a hallmark of DM cardiomyopathy. The pathophysiology of cardiac fibrosis in DM cardiomyopathy is complex and involves multiple cellular and molecular mechanisms. Cardiac fibrosis contributes to the development of heart failure with preserved ejection fraction (HFpEF), which increases mortality and the incidence of hospitalizations. As medical technology advances, the severity of cardiac fibrosis in DM cardiomyopathy can be evaluated by non-invasive imaging modalities such as echocardiography, heart computed tomography (CT), cardiac magnetic resonance imaging (MRI), and nuclear imaging. In this review article, we will discuss the pathophysiology of cardiac fibrosis in DM cardiomyopathy, non-invasive imaging modalities to evaluate the severity of cardiac fibrosis, and therapeutic strategies for DM cardiomyopathy.

Single-cell RNA-seq of heart reveals intercellular communication drivers of myocardial fibrosis in diabetic cardiomyopathy.

Myocardial fibrosis is the characteristic pathology of diabetes-induced cardiomyopathy. Therefore, an in-depth study of cardiac heterogeneity and cell-to-cell interactions can help elucidate the pathogenesis of diabetic myocardial fibrosis and identify treatment targets for the treatment of this disease. In this study, we investigated intercellular communication drivers of myocardial fibrosis in mouse heart with high-fat-diet/streptozotocin-induced diabetes at single-cell resolution. Intercellular and protein-protein interaction networks of fibroblasts and macrophages, endothelial cells, as well as fibroblasts and epicardial cells revealed critical changes in ligand-receptor interactions such as Pdgf(s)-Pdgfra and Efemp1-Egfr, which promote the development of a profibrotic microenvironment during the progression of and confirmed that the specific inhibition of the Pdgfra axis could significantly improve diabetic myocardial fibrosis. We also identified phenotypically distinct Hrchi and Postnhi fibroblast subpopulations associated with pathological extracellular matrix remodeling, of which the Hrchi fibroblasts were found to be the most profibrogenic under diabetic conditions. Finally, we validated the role of the Itgb1 hub gene-mediated intercellular communication drivers of diabetic myocardial fibrosis in Hrchi fibroblasts, and confirmed the results through AAV9-mediated Itgb1 knockdown in the heart of diabetic mice. In summary, cardiac cell mapping provides novel insights into intercellular communication drivers involved in pathological extracellular matrix remodeling during diabetic myocardial fibrosis.

Central role of cardiac fibroblasts in myocardial fibrosis of diabetic cardiomyopathy.

Diabetic cardiomyopathy (DCM), a main cardiovascular complication of diabetes, can eventually develop into heart failure and affect the prognosis of patients. Myocardial fibrosis is the main factor causing ventricular wall stiffness and heart failure in DCM. Early control of myocardial fibrosis in DCM is of great significance to prevent or postpone the progression of DCM to heart failure. A growing body of evidence suggests that cardiomyocytes, immunocytes, and endothelial cells involve fibrogenic actions, however, cardiac fibroblasts, the main participants in collagen production, are situated in the most central position in cardiac fibrosis. In this review, we systematically elaborate the source and physiological role of myocardial fibroblasts in the context of DCM, and we also discuss the potential action and mechanism of cardiac fibroblasts in promoting fibrosis, so as to provide guidance for formulating strategies for prevention and treatment of cardiac fibrosis in DCM.

N-glycosylation-mediated CD147 accumulation induces cardiac fibrosis in the diabetic heart through ALK5 activation.

Emerging evidence has implicated the important role of fibrosis in diabetic cardiomyopathy (DCM), while the underlying mechanism remains unclear. Considering the distinct and overlapping roles of Cluster of Differentiation 147 (CD147) in the pathogenesis of fibrotic diseases, we aim to investigate the role of CD147 in the fibrosis of DCM and explore its underlying mechanism. AAV9-mediated cardiac-specific CD147 silencing attenuated cardiac fibrosis and cardiac function in diabetic mice. CD147 knockdown significantly inhibited high glucose (HG)-induced activation of CFs. Mechanistically, CD147 directly bound to type I transcription growth factor β (TGF-β) receptor I (ALK5), promoting ALK5 activation and endocytosis to induce SMAD2/3 phosphorylation and nuclear translocation. In addition, HG prevented the ubiquitin-proteasome-dependent degradation of CD147 by promoting GNT-V-mediated N-glycosylation. As a result, cardiac-specific CD147 overexpression in control mice mimicked diabetes-induced cardiac fibrosis, aggravating cardiac function. Importantly, CD147 was also upregulated in serum and myocardial specimens from patients with diabetes compared with non-diabetes, accompanied by echocardiographic indices of cardiac dysfunction and excessive collagen deposition. Our study provides the first evidence that CD147 acts as a pivotal factor to promote diabetic cardiac fibrosis, and may contribute to the development of future CD147-based therapeutic strategies for DCM.

Unveiling the Vital Role of Long Non-Coding RNAs in Cardiac Oxidative Stress, Cell Death, and Fibrosis in Diabetic Cardiomyopathy.

Diabetes mellitus is a burdensome public health problem. Diabetic cardiomyopathy (DCM) is a major cause of mortality and morbidity in diabetes patients. The pathogenesis of DCM is multifactorial and involves metabolic abnormalities, the accumulation of advanced glycation end products, myocardial cell death, oxidative stress, inflammation, microangiopathy, and cardiac fibrosis. Evidence suggests that various types of cardiomyocyte death act simultaneously as terminal pathways in DCM. Long non-coding RNAs (lncRNAs) are a class of RNA transcripts with lengths greater than 200 nucleotides and no apparent coding potential. Emerging studies have shown the critical role of lncRNAs in the pathogenesis of DCM, along with the development of molecular biology technologies. Therefore, we summarize specific lncRNAs that mainly regulate multiple modes of cardiomyopathy death, oxidative stress, and cardiac fibrosis and provide valuable insights into diagnostic and therapeutic biomarkers and strategies for DCM.

LncRNA TUG1 Exacerbates Myocardial Fibrosis in Diabetic Cardiomyopathy by Modulating the microRNA-145a-5p/Cfl2 Axis.

Nowadays, there is limited prevention and treatment for myocardial fibrosis in diabetic cardiomyopathy (DCM). Our study aimed to depict the mechanism of the lncRNA TUG1/miR-145a-5p/Cfl2 axis in DCM and to provide a molecular basis for the study of this disease. Male C57BL/6J mice were intraperitoneally injected with streptozotocin to establish DCM mouse models. The expression levels of lncRNA TUG1, miR-145a-5p, and Cfl2 in myocardial tissues of mice were tested by RT-qPCR or Western blot. Cardiac function was assessed by echocardiography. The contents of Ang-II, TNF-α, and IL-1β were measured using ELISA. The histopathological observation was performed by HE staining and Masson staining. The expression levels of myocardial fibrosis-related genes COL1A1, MMP2, and FN1 were determined by RT-qPCR. In addition, bioinformatics website, RIP assay, pull-down assay, and luciferase activity assay were conducted to verify the relationships of lncRNA TUG1, miR-145a-5p, and Cfl2. In the DCM mouse model, lncRNA TUG1 and Cfl2 expression levels were upregulated and miR-145a-5p expression was downregulated. Downregulation of lncRNA TUG1 improved cardiac function and myocardial fibrosis; decreased COL1A1, MMP2, and FN1 expression levels; as well as TNF-α, IL-1β, and Ang-II contents in myocardial tissues of DCM mice. Upregulation of miR-145a-5p showed the same trend as downregulation of lncRNA TUG1. In addition, upregulating miR-145a-5p reversed the promotion roles of lncRNA TUG1 on myocardial fibrosis in DCM mice, and upregulating Cfl2 compromised the improvement effect of downregulated lncRNA TUG1 on myocardial fibrosis in DCM mice. Mechanistically, there was a binding site between lncRNA TUG1 and miR-145a-5p, and miR-145a-5p had a targeting relationship with Cfl2. This study highlights that lncRNA TUG1 sponges miR-145a-5p to aggravate myocardial fibrosis in DCM mice by promoting Cfl2.

LncRNA Airn alleviates diabetic cardiac fibrosis by inhibiting activation of cardiac fibroblasts via a m6A-IMP2-p53 axis

BackgroundCardiac fibrosis is a leading cause of cardiac dysfunction in patients with diabetes. However, the underlying mechanisms of cardiac fibrosis remain unclear. This study aimed to investigate the role of the long non-coding RNA (LncRNA) Airn in the pathogenesis of cardiac fibrosis in diabetic cardiomyopathy (DCM) and its underlying mechanism.MethodsDiabetes mellitus (DM) was induced in mice by streptozotocin injection. An intramyocardial adeno-associated virus (AAV) was used to manipulate Airn expression. The functional significance and underlying mechanisms in DCM fibrosis were investigated both in vitro and in vivo.ResultsDiabetic hearts showed a significant impairment in cardiac function, accompanied by obviously increased cardiac fibrosis. Interestingly, lncRNA Airn expression was significantly decreased in both diabetic hearts and high glucose (HG)-treated cardiac fibroblasts (CFs). AAV-mediated Airn reconstitution prevented cardiac fibrosis and the development of DCM, while Airn knockdown induced cardiac fibrosis phenotyping DCM. As in vitro, Airn reversed HG-induced fibroblast-myofibroblast transition, aberrant CFs proliferation and section of collagen I. In contrast, Airn knockdown mimicked a HG-induced CFs phenotype. Mechanistically, we identified that Airn exerts anti-fibrotic effects by directly binding to insulin-like growth factor 2 mRNA-binding protein 2 (IMP2) and further prevents its ubiquitination-dependent degradation. Moreover, we revealed that Airn/IMP2 protected p53 mRNA from degradation in m6A manner, leading to CF cell cycle arrest and reduced cardiac fibrosis. As a result, ablation of p53 blunted the inhibitory effects of Airn on fibroblast activation and cardiac fibrosis.ConclusionsOur study demonstrated for the first time that Airn prevented the development of cardiac fibrosis in diabetic heart via IMP2-p53 axis in an m6A dependent manner. LncRNA Airn could be a promising therapeutic target for cardiac fibrosis in DCM.Graphical abstract

Abstract 10586: CREG1-FBXO27-LAMP2 Axis Promotes Autophagy Function of Cardiomyocytes and Alleviates Diabetic Cardiomyopathy

Introduction: Diabetic cardiomyopathy is a chronic complication of diabetes in the absence of coronary artery disease, arterial hypertension and valvular disease. Autophagy plays an important role in the development of diabetic cardiomyopathy. Cellular repressor of E1A-stimulated genes 1 (CREG1) is an important myocardial protective factor. The aim of this study was to investigate the effects and mechanisms of CREG1 in diabetic cardiomyopathy. Methods: Male C57BL/6J mice, CREG1 transgenic mice, and CREG1 cardiac-specific knockout mice were used to establish a type 2 diabetic model. Small animal ultrasound, Masson’s staining, and western blotting were used to evaluate cardiac function, myocardial fibrosis and autophagy. Neonatal mouse cardiomyocytes (NMCMs) were isolated and cultured. NMCMs were infected with CREG1- overexpressing adenovirus or small interfering RNA, followed by stimulation with palmitic acid (PA), real-time PCR, western blotting and immunofluorescence staining were used. Results: CREG1 protein expression was decreased in the myocardium of diabetic cardiomyopathy. CREG1 deficiency in the heart aggravated cardiac dysfunction, cardiac hypertrophy, and fibrosis in mice with diabetic cardiomyopathy, accompanied by aggravated autophagy dysfunction. CREG1 overexpression improved cardiac function and ameliorated cardiac hypertrophy and fibrosis in diabetic cardiomyopathy, by improving autophagy. CREG1 protein expression was decreased in PA-stimulated NMCMs. CREG1 knockdown aggravated cardiomyocyte hypertrophy and inhibited autophagy, which were reversed by resveratrol treatment. Conversely, CREG1 overexpression inhibited cardiomyocyte hypertrophy and improved autophagy, which were reversed by chloroquine or bafilomycin A1 treatment. Overexpression of LAMP2 reversed the effect of CREG1 knockdown on the PA-induced inhibition of cardiomyocyte autophagy. CREG1 inhibited the LAMP2 protein degradation by inhibiting the expression of F-box protein 27 (FBXO27). Conclusions: CREG1-FBXO27-LAMP2 axis alleviated diabetic cardiomyopathy by promoting cardiomyocyte autophagy. Our findings might help clarify new roles of CREG1 in the development of diabetic cardiomyopathy.

Endothelial derived miRNA-9 mediated cardiac fibrosis in diabetes and its regulation by ZFAS1.

Diabetic cardiomyopathy (DCM) is one of the most prevalent causes of morbidity and mortality in diabetic patients. Hyperglycemia induces increased expression/deposition of extracellular matrix (ECM) proteins including fibronectin (FN) and collagen (Col) and plays an important role in fibrosis in diabetic cardiomyopathy (DCM). The roles of RNAs including microRNA (miRNA) and long non-coding RNAs (lncRNA) have begun to be understood in many conditions. In this study, we investigated the role of a specific miRNA, miR-9, and its interactions with lncRNA ZFAS1 in mediating fibrosis in DCM. Treatment with 25 mM glucose (HG) decreased miR-9 expression and increased expressions of ZFAS1, ECM proteins and inflammatory markers, compared to 5 mM glucose (NG) in the HCMECs by using qRT-PCR. Glucose-induced upregulation of ECM proteins can be prevented by ZFAS1 siRNA or miR-9 mimic transfection. Luciferase assay was confirmed miR-9 binding to FN 3’-UTR. miR-9 expression can be regulated by ZFAS1 through polycomb repressive complex 2 (PRC2) components using RNA immunoprecipitation (RIP) and chromatin immunoprecipitation (ChIP) assays. In the in vivo experiment, hyperglycemia-induced the ECM production can be prevented by the miR-9 overexpression in the fibrosis in DCM. These studies showed a novel glucose-induced molecular mechanism in which ZFAS1 participates in the transcriptional regulation of ECM protein production in diabetes through miR-9.

ADAM17 knockdown mitigates while ADAM17 overexpression aggravates cardiac fibrosis and dysfunction via regulating ACE2 shedding and myofibroblast transformation.

A disintegrin and metalloprotease domain family protein 17 (ADAM17) is a new member of renin-angiotensin system (RAS) but its role in the pathogenesis of diabetic cardiomyopathy (DCM) is obscure. To test the hypothesis that ADAM17 knockdown mitigates while ADAM17 overexpression aggravates cardiac fibrosis via regulating ACE2 shedding and myofibroblast transformation in diabetic mice, ADAM17 gene was knocked down and overexpressed by means of adenovirus-mediated short-hairpin RNA (shRNA) and adenovirus vector carrying ADAM17 cDNA, respectively, in a mouse model of DCM. Two-dimensional and Doppler echocardiography, histopathology and immunohistochemistry were performed in all mice and in vitro experiments conducted in primary cardiofibroblasts. The results showed that ADAM17 knockdown ameliorated while ADAM17 overexpression worsened cardiac dysfunction and cardiac fibrosis in diabetic mice. In addition, ADAM17 knockdown increased ACE2 while reduced AT1R expression in diabetic hearts. Mechanistically, ADAM17 knockdown decreased while ADAM17 overexpression increased cardiac fibroblast-to-myofibroblast transformation through regulation of TGF-β1/Smad3 signaling pathway. In conclusion, ADAM17 knockdown attenuates while ADAM17 overexpression aggravates cardiac fibrosis via regulating ACE2 shedding and myofibroblast transformation through TGF-β1/Smad3 signaling pathway in diabetic mice. Targeting ADAM17 may provide a promising approach to the prevention and treatment of cardiac fibrosis in DCM.

HDAC1 Promotes Myocardial Fibrosis in Diabetic Cardiomyopathy by Inhibiting BMP-7 Transcription Through Histone Deacetylation.

Diabetic cardiomyopathy (DCM) constitutes a primary cause of mortality in diabetic patients. Histone deacetylase (HDAC) inhibition can alleviate diabetes-associated myocardial injury. This study investigated the mechanism of HDAC1 on myocardial fibrosis (MF) in DCM. A murine model of DCM was established by a high-fat diet and streptozotocin injection. The bodyweight, blood glucose, serum insulin, and cardiac function of mice were analyzed. Lentivirus-packaged sh-HDAC1 was injected into DCM mice and high glucose (HG)-induced cardiac fibroblasts (CFs). The pathological structure of the myocardium and the level of myocardial fibrosis were observed by histological staining. HDAC1 expression in mouse myocardial tissues and CFs was determined. Collagen I, collagen III, alpha-smooth muscle actin (α-SMA), and vimentin levels in CFs were detected, and CF proliferation was tested. HDAC activity and histone acetylation levels in tissues and cells were measured. Bone morphogenetic protein-7 (BMP-7) expression in myocardial tissues and CFs was determined. Functional rescue experiments were conducted to confirm the effects of histone acetylation and BMP-7 on myocardial fibrosis. DCM mice showed decreased bodyweight, elevated blood glucose and serum insulin, and cardiac dysfunction. Elevated HDAC1 and reduced BMP-7 expressions were detected in DCM mice and HG-induced CFs. HDAC1 repressed BMP-7 transcription through deacetylation. HDAC1 silencing alleviated MF, reduced CF proliferation and decreased collagen I, -III, α-SMA, and vimentin levels. However, reducing histone acetylation level or BMP-7 downregulation reversed the effects of HDAC1 silencing on CF fibrosis. HDAC1 repressed BMP-7 transcription by enhancing histone deacetylation, thereby promoting MF and aggravating DCM.

Co-administration of hydrogen and metformin exerts cardioprotective effects by inhibiting pyroptosis and fibrosis in diabetic cardiomyopathy

Hydrogen is a novel medical gas with several properties, including anti-oxidative, anti-inflammatory, anti-apoptotic, anti-allergic, and energy metabolism stimulating properties. Hydrogen therapy has been proven effective in the treatment of myocardial ischemia, myocardial infarction, and ischemia-reperfusion injury. Diabetic cardiomyopathy (DCM) is a serious cardiovascular complication of long-term chronic diabetes that is linked to increased heart failure and arrhythmia morbidity. The effect of hydrogen on the pathogenesis of DCM is yet to be determined. Metformin is a well-known pharmacological agent for the treatment of diabetes; however, the application of large doses of the drug is limited by its side effects. Therefore, this highlights the importance of developing novel therapies against DCM. In this regard, we investigated the effect of hydrogen on DCM and the mechanisms that underlie it. Furthermore, we also assessed the efficacy of co-administration of metformin and hydrogen. In this study, we found that hydrogen improved cardiac dysfunction and abnormal morphological structure in streptozotocin-induced diabetic mice. As a mechanism, it was confirmed that hydrogen mediated its action by reducing pyroptosis via inhibition of the AMPK/mTOR/NLRP3 signaling pathway and ameliorating fibrosis via inhibition of the TGF-β1/Smad signaling pathway. Furthermore, our findings suggested that co-administration of hydrogen and metformin shows potent protective effects, as evidenced by increased survival rates, reduced fasting blood glucose, and decreased cell injury when compared to a single application of metformin. In conclusion, our study demonstrated that hydrogen inhalation attenuates DCM by reducing pyroptosis and fibrosis and that hydrogen can be combined with metformin to exhibit a more potent cardioprotective effect in DCM.

Mechanism of Yangxinshi Intervention on Cardiac Fibrosis in Diabetic Cardiomyopathy Based on Network Pharmacology

Background Cardiac fibrosis (CF) is major myocardial change in diabetic cardiomyopathy (DCM). Yangxinshi as a Chinese medicine formula is used to treat cardiovascular diseases. However, the exact effective mechanism of Yangxinshi on CF is still uncertain. Hence, based on the pharmacological network, predicting the active components, potential targets and pathways of Yangxinshi on diabetic fibrosis require to be further studied. Materials and Methods By using Cytoscape 3.6.0 Bisogenet plug-in, the active components of Yangxinshi were obtained and screened through TCMSP, and the PPI network of DCM-CF was constructed and then screened by CytoNCA plug-in. GO analysis and KEGG pathway enrichment analysis were carried out by Cluego plug-in. Combined with the results of network pharmacological analysis, cells in vitro were performed to verify the CF stimulated with high glucose or intervence with Yangxinshi, and the expressions of Cbl-b, p-smad2, and α-SMA were detected. Results Yangxinshi might play a key role in reversing cardiac fibrosis in individuals with DCM by regulating the signal pathway of CBL and promoted the expression of Cbl-b and inhibited the expression of p-smad2 and α-SMA, verifying some predictive work via network pharmacology. Conclusion Based on network pharmacology, this study demonstrates that the beneficial effect of Yangxinshi on CF is related to the Cbl-b/smad2 pathway, providing an idea for the therapeutic effect of Yangxinshi on cardiac fibrosis in DCM.