Cardioprotective Effect of Decorin in Type 2 Diabetes

Homeostatic Role of Decorin in Right Ventricular Pressure Overload and Pulmonary Hypertension Induced Remodeling

Right ventricular (RV) pressure loading induces RV profibrotic signaling and fibrosis associated with RV dysfunction. RV decorin protein levels are decreased in patients with chronic RV pressure loading. RV decorin protein levels are also decreased in 4 animal models of mechanical RV pressure loading and pulmonary arterial hypertension. Human cardiac fibroblasts overexpressing decorin show diminished collagen-1 secretion in response to mechanical or chemical profibrotic stress while decorin knockout human cardiac fibroblasts show increased collagen-1 secretion in response to stress. Downregulation of decorin may play a key role in upregulating transforming growth factor-β1 profibrotic signaling and fibrosis that contribute to RV dysfunction in RV pressure loading.

The Function of Myostatin in Ameliorating Bone Metabolism Abnormalities in Individuals with Type 2 Diabetes Mellitus by Exercise

PURPOSE

The molecular mechanisms involved in bone metabolism abnormalities in individuals with type 2 diabetes mellitus (T2DM) are a prominent area of investigation within the life sciences field. Myostatin (MSTN), a member of the TGF-β superfamily, serves as a critical negative regulator of skeletal muscle growth and bone metabolism. Current research on the exercise-mediated regulation of MSTN expression predominantly focuses on its role in skeletal muscle. However, due to the intricate and multifaceted mechanical and biochemical interactions between muscle and bone, the precise mechanisms by which exercise modulates MSTN to enhance bone metabolic disorders in T2DM necessitate additional exploration. The objective of this review is to systematically synthesize and evaluate the role of MSTN in the development of bone metabolism disorders associated with T2DM and elucidate the underlying mechanisms influenced by exercise interventions, aiming to offer novel insights and theoretical recommendations for enhancing bone health through physical activity.

METHODS

Relevant articles in Chinese and English up to July 2024 were selected using specific search terms and databases (PubMed, CNKI, Web of Science); 147 studies were finally included after evaluation, and the reference lists were checked for other relevant research.

RESULTS

Myostatin's heightened expression in the bone and skeletal muscle of individuals with T2DM can impede various pathways, such as PI3K/AKT/mTOR and Wnt/β-catenin, hindering osteoblast differentiation and bone mineralization. Additionally, it can stimulate osteoclast differentiation and bone resorption capacity by facilitating Smad2-dependent NFATc1 nuclear translocation and PI3K/AKT/AP-1-mediated pro-inflammatory factor expression pathways, thereby contributing to bone metabolism disorders. Physical exercise plays a crucial role in ameliorating bone metabolism abnormalities in individuals with T2DM. Exercise can activate pathways like Wnt/GSK-3β/β-catenin, thereby suppressing myostatin and downstream Smads, CCL20/CCR6, and Nox4 target gene expression, fostering bone formation, inhibiting bone resorption, and enhancing bone metabolism in T2DM.

CONCLUSION

In the context of T2DM, MSTN has been shown to exacerbate bone metabolic disorders by inhibiting the differentiation of osteoblasts and the process of bone mineralization while simultaneously promoting the differentiation and activity of osteoclasts. Exercise interventions have demonstrated efficacy in downregulating MSTN expression, disrupting its downstream signaling pathways, and enhancing bone metabolism.

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.

The role of serine/threonine protein kinases in cardiovascular disease and potential therapeutic methods

Protein phosphorylation is an important link in a variety of signaling pathways, and most of the important life processes in cells involve protein phosphorylation. Based on the amino acid residues of phosphorylated proteins, protein kinases can be categorized into the following families: serine/threonine protein kinases, tyrosine-specific protein kinases, histidine-specific protein kinases, tryptophan kinases, and aspartate/glutamyl protein kinases. Of all the protein kinases, most are serine/threonine kinases, where serine/threonine protein kinases are protein kinases that catalyze the phosphorylation of serine or threonine residues on target proteins using ATP as a phosphate donor. The current socially accepted classification of serine/threonine kinases is to divide them into seven major groups: protein kinase A, G, C (AGC), CMGC, Calmodulin-dependent protein kinase (CAMK), Casein kinase (CK1), STE, Tyrosine kinase (TKL) and others. After decades of research, a preliminary understanding of the specific classification and respective functions of serine/threonine kinases has entered a new period of exploration. In this paper, we review the literature of the previous years and introduce the specific signaling pathways and related therapeutic modalities played by each of the small protein kinases in the serine/threonine protein kinase family, respectively, in some common cardiovascular system diseases such as heart failure, myocardial infarction, ischemia-reperfusion injury, and diabetic cardiomyopathy. To a certain extent, the current research results, including molecular mechanisms and therapeutic methods, are fully summarized and a systematic report is made for the prevention and treatment of cardiovascular diseases in the future.

Protein glycosylation in cardiovascular health and disease

Protein glycosylation, which involves the attachment of carbohydrates to proteins, is one of the most abundant protein co-translational and post-translational modifications. Advances in technology have substantially increased our knowledge of the biosynthetic pathways involved in protein glycosylation, as well as how changes in glycosylation can affect cell function. In addition, our understanding of the role of protein glycosylation in disease processes is growing, particularly in the context of immune system function, infectious diseases, neurodegeneration and cancer. Several decades ago, cell surface glycoproteins were found to have an important role in regulating ion transport across the cardiac sarcolemma. However, with very few exceptions, our understanding of how changes in protein glycosylation influence cardiovascular (patho)physiology remains remarkably limited. Therefore, in this Review, we aim to provide an overview of N-linked and O-linked protein glycosylation, including intracellular O-linked N-acetylglucosamine protein modification. We discuss our current understanding of how all forms of protein glycosylation contribute to normal cardiovascular function and their roles in cardiovascular disease. Finally, we highlight potential gaps in our knowledge about the effects of protein glycosylation on the heart and vascular system, highlighting areas for future research.

The Proteoglycans Biglycan and Decorin Protect Cardiac Cells against Irradiation-Induced Cell Death by Inhibiting Apoptosis

Radiation-induced heart disease (RIHD), a common side effect of chest irradiation, is a primary cause of mortality among patients surviving thoracic cancer. Thus, the development of novel, clinically applicable cardioprotective agents which can alleviate the harmful effects of irradiation on the heart is of great importance in the field of experimental oncocardiology. Biglycan and decorin are structurally related small leucine-rich proteoglycans which have been reported to exert cardioprotective properties in certain cardiovascular pathologies. Therefore, in the present study we aimed to examine if biglycan or decorin can reduce radiation-induced damage of cardiomyocytes. A single dose of 10 Gray irradiation was applied to induce radiation-induced cell damage in H9c2 cardiomyoblasts, followed by treatment with either biglycan or decorin at various concentrations. Measurement of cell viability revealed that both proteoglycans improved the survival of cardiac cells post-irradiation. The cardiocytoprotective effect of both biglycan and decorin involved the alleviation of radiation-induced proapoptotic mechanisms by retaining the progression of apoptotic membrane blebbing and lowering the number of apoptotic cell nuclei and DNA double-strand breaks. Our findings provide evidence that these natural proteoglycans may exert protection against radiation-induced damage of cardiac cells.

Chitosan Versus Dapagliflozin in a Diabetic Cardiomyopathy Mouse Model

Diabetes mellitus is a metabolic disorder with global economic implications that can lead to complications such as diabetic cardiomyopathy. The aim of this study was to compare the effects of chitosan versus dapagliflozin in mouse diabetic cardiomyopathy. We used 32 C57Bl/6 male mice aged between 8 and 10 weeks, which were randomly divided into Control-without diabetes mellitus (DM), type 1 DM (T1DM), T1DM + Chitosan, and T1DM + Dapapgliflozin groups. We induced diabetes with streptozotocin and treated the animals for 12 weeks. The analysis showed a reduction in intramyocardial fibrosis in the T1DM + Dapapgliflozin compared to T1DM animals. In T1DM + CHIT, a reduction in intramyocardial fibrosis was observed although, accordingly, there was also no significant decrease in blood glucose. The level of oxidative stress was reduced in the groups of treated animals compared to T1DM. All these observed changes in the structure and function of hearts were highlighted in the echocardiographic examination. In the treated groups, there was delayed appearance of left ventricular (LV) hypertrophy, a slight decrease in the ejection fraction of the LV, and an improved diastolic profile. The results demonstrate that chitosan has promising effects on diabetic cardiomyopathy that are comparable to the beneficial effects of dapagliflozin.

Targeted Proteomics Reveals Functional Targets for Early Diabetes Susceptibility in Young Adults

BACKGROUND

The circulating proteome may encode early pathways of diabetes susceptibility in young adults for surveillance and intervention. Here, we define proteomic correlates of tissue phenotypes and diabetes in young adults.

METHODS

We used penalized models and principal components analysis to generate parsimonious proteomic signatures of diabetes susceptibility based on phenotypes and on diabetes diagnosis across 184 proteins in >2000 young adults in the CARDIA (Coronary Artery Risk Development in Young Adults study; mean age, 32 years; 44% women; 43% Black; mean body mass index, 25.6±4.9 kg/m2), with validation against diabetes in >1800 individuals in the FHS (Framingham Heart Study) and WHI (Women's Health Initiative).

RESULTS

In 184 proteins in >2000 young adults in CARDIA, we identified 2 proteotypes of diabetes susceptibility-a proinflammatory fat proteotype (visceral fat, liver fat, inflammatory biomarkers) and a muscularity proteotype (muscle mass), linked to diabetes in CARDIA and WHI/FHS. These proteotypes specified broad mechanisms of early diabetes pathogenesis, including transorgan communication, hepatic and skeletal muscle stress responses, vascular inflammation and hemostasis, fibrosis, and renal injury. Using human adipose tissue single cell/nuclear RNA-seq, we demonstrate expression at transcriptional level for implicated proteins across adipocytes and nonadipocyte cell types (eg, fibroadipogenic precursors, immune and vascular cells). Using functional assays in human adipose tissue, we demonstrate the association of expression of genes encoding these implicated proteins with adipose tissue metabolism, inflammation, and insulin resistance.

CONCLUSIONS

A multifaceted discovery effort uniting proteomics, underlying clinical susceptibility phenotypes, and tissue expression patterns may uncover potentially novel functional biomarkers of early diabetes susceptibility in young adults for future mechanistic evaluation.

Mechanism Exploration on the Immunoregulation of Allogeneic Heart Transplantation Rejection in Rats With Exosome miRNA and Proteins From Overexpressed IDO1 BMSCs

Immunoregulation and indoleamine 2,3-dioxygenase 1 (IDO1) play pivotal roles in the rejection of allogeneic organ transplantation. This study aims to elucidate the immune-related functional mechanisms of exosomes (Exos) derived from bone marrow-derived mesenchymal stem cells (BMSCs) overexpressing IDO1 in the context of allogeneic heart transplantation (HTx) rejection. A rat model of allogeneic HTx was established. Exos were extracted after transfection with oe-IDO1 and oe-NC from rat BMSCs. Exos were administered via the caudal vein for treatment. The survival of rats was analyzed, and reverse transcription qualitative PCR (RT-qPCR) and immunohistochemistry (IHC) were employed to detect the expression of related genes. Histopathological examination was conducted using hematoxylin and eosin (HE) staining, and flow cytometry was utilized to analyze T-cell apoptosis. Proteomics and RNA-seq analyses were performed on Exos. The data were subjected to functional enrichment analysis using the R language. A protein interaction network was constructed using the STRING database, and miRWalk, TargetScan, and miRDB databases predicted the target genes, differentially expressed miRNAs, and transcription factors (TFs). Exos from BMSCs overexpressing IDO1 prolonged the survival time of rats undergoing allogeneic HTx. These Exos reduced inflammatory cell infiltration, mitigated myocardial damage, induced CD4 T-cell apoptosis, and alleviated transplantation rejection. The correlation between Exos from BMSCs overexpressing IDO1 and immune regulation was profound. Notably, 13 immune-related differential proteins (Anxa1, Anxa2, C3, Ctsb, Hp, Il1rap, Ntn1, Ptx3, Thbs1, Hspa1b, Vegfc, Dcn, and Ptpn11) and 10 significantly different miRNAs were identified. Finally, six key immune proteins related to IDO1 were identified through common enrichment pathways, including Thbs1, Dcn, Ptpn11, Hspa1b, Il1rap, and Vegfc. Thirteen TFs of IDO1-related key miRNAs were obtained, and a TF-miRNA-mRNA-proteins regulatory network was constructed. Exosome miRNA derived from BMSCs overexpressing IDO1 may influence T-cell activation and regulate HTx rejection by interacting with mRNA.

Decorin Concentrations in Aqueous Humor of Patients with Diabetic Retinopathy

Diabetic retinopathy (DR) is a microvascular complication of diabetes in the retina. Chronic hyperglycemia damages retinal microvasculature embedded into the extracellular matrix (ECM), causing fluid leakage and ischemic retinal neovascularization. Current treatment strategies include intravitreal anti-vascular endothelial growth factor (VEGF) or steroidal injections, laser photocoagulation, or vitrectomy in severe cases. However, treatment may require multiple modalities or repeat treatments due to variable response. Though DR management has achieved great success, improved, long-lasting, and predictable treatments are needed, including new biomarkers and therapeutic approaches. Small-leucine rich proteoglycans, such as decorin, constitute an integral component of retinal endothelial ECM. Therefore, any damage to microvasculature can trigger its antifibrotic and antiangiogenic response against retinal vascular pathologies, including DR. We conducted a cross-sectional study to examine the association between aqueous humor (AH) decorin levels, if any, and severity of DR. A total of 82 subjects (26 control, 56 DR) were recruited. AH was collected and decorin concentrations were measured using an enzyme-linked immunosorbent assay (ELISA). Decorin was significantly increased in the AH of DR subjects compared to controls (p = 0.0034). AH decorin levels were increased in severe DR groups in ETDRS and Gloucestershire classifications. Decorin concentrations also displayed a significant association with visual acuity (LogMAR) measurements. In conclusion, aqueous humor decorin concentrations were found elevated in DR subjects, possibly due to a compensatory response to the retinal microvascular changes during hyperglycemia.

Heart failure in diabetes

Heart failure and cardiovascular disorders represent the leading cause of death in diabetic patients. Here we present a systematic review of the main mechanisms underlying the development of diabetic cardiomyopathy. We also provide an excursus on the relative contribution of cardiomyocytes, fibroblasts, endothelial and smooth muscle cells to the pathophysiology of heart failure in diabetes. After having described the preclinical tools currently available to dissect the mechanisms of this complex disease, we conclude with a section on the most recent updates of the literature on clinical management.

Regulation of decorin by ursolic acid protects against non-alcoholic steatohepatitis

Non-alcoholic steatohepatitis (NASH) has become a global health issue, which poses additional financial burden to public health care. However, no specific pharmacological therapy is recommended in current guidelines. Ursolic acid (UA) has been proven to perform multiple biological activities, thereby having a broad application prospect in healthcare field. Thus, this current research was conducted to investigate the protective mechanisms of UA on NASH. Integrative genomic analyses were performed to identify characteristic genes for NASH, and human proteomics chip was applied to seek out differentially binding proteins for UA. The combining bioinformatic analyses revealed 529 and 502 differentially expressed genes for NASH and UA, respectively. And further enrichment analyses indicated that IGF-IR signaling pathway was intimately involved in the therapeutic effects of UA on NASH. Experimental studies displayed that UA up-regulated the decorin expression to activate IGF-IR signaling as well as to inhibit HIF-1 signaling, resulting in alleviation on metabolic dysfunction, liver steatosis, inflammation and hypoxia in high-fat-fed mice. And additionally, these results were confirmed by lipotoxic and decorin-interference cell model. Taken together, we found that UA could regulate IGF-IR and HIF-1 signaling pathways via decorin to provide dual protective functions on metabolic dysfunction and liver hypoxia, and therefore turned to be an effective option for the treatment of NASH.

Cellular mechanisms and recommended drug-based therapeutic options in diabetic cardiomyopathy

Diabetes mellitus (DM) is associated with a specific cardiac phenotype characterized by structural and functional alterations. This so-called diabetic cardiomyopathy (DM CM) is clinically relevant as patients with DM show high incidence of heart failure. Mechanistically, several parameters interact on the cardiomyocyte level leading to increased inflammation, apoptosis, reactive oxygen species and altered calcium signaling. This in turn provokes functional myocardial changes that might inter alia play into the worsened clinical outcome in DM patients. Therefore, efficient therapeutic options are urgently needed. This review focuses on mechanistic effects of currently recommended antidiabetic treatment and heart failure therapy for DM CM.

A functional outside-in signaling network of proteoglycans and matrix molecules regulating autophagy

Proteoglycans and selected extracellular matrix constituents are emerging as intrinsic and critical regulators of evolutionarily conversed, intracellular catabolic pathways. Often, these secreted molecules evoke sustained autophagy in a variety of cell types, tissues, and model systems. The unique properties of proteoglycans have ushered in a paradigmatic shift to broaden our understanding of matrix-mediated signaling cascades. The dynamic cellular pathway controlling autophagy is now linked to an equally dynamic and fluid signaling network embedded in a complex meshwork of matrix molecules. A rapidly emerging field of research encompasses multiple matrix-derived candidates, representing a menagerie of soluble matrix constituents including decorin, biglycan, endorepellin, endostatin, collagen VI and plasminogen kringle 5. These matrix constituents are pro-autophagic and simultaneously anti-angiogenic. In contrast, perlecan, laminin α2 chain, and lumican have anti-autophagic functions. Mechanistically, each matrix constituent linked to intracellular catabolic events engages a specific cell surface receptor that often converges on a common core of the autophagic machinery including AMPK, Peg3 and Beclin 1. We consider this matrix-evoked autophagy as non-canonical given that it occurs in an allosteric manner and is independent of nutrient availability or prevailing bioenergetics control. We propose that matrix-regulated autophagy is an important outside-in signaling mechanism for proper tissue homeostasis that could be therapeutically leveraged to combat a variety of diseases.