The Potential Role of Undercarboxylated Osteocalcin Upregulation in Microvascular Insufficiency in a Rat Model of Diabetic Cardiomyopathy

Undercarboxylated Osteocalcin: A Promising Target for Early Diagnosis of Cardiovascular and Glycemic Disorders in Patients with Metabolic Syndrome: A Pilot Study

Lifestyle changes are causing an exponential increase in the prevalence of obesity and metabolic syndrome (MetS) worldwide. The most frequent complications of these are the development of diabetes (T2D) and cardiovascular disease (CVD). Accurate tools are needed to classify the cardiovascular risk (CVR) in the MetS population. In recent years, numerous biomarkers of bone metabolism have been associated with CVR. The aim of this study was to determine the levels of undercarboxylated osteocalcin (ucOC) in a cohort of patients with MetS and to analyse its association with MetS parameters and CVR as well as with T2D prevalence. A longitudinal study was conducted in which a MetS population was followed for one year. Weight change, adherence to the Mediterranean diet (MedDiet), ucOC levels, MetS parameters and CVR were analysed and CVR was calculated using different scores. Our results showed a decrease of CVR associated with a better adherence to the MetDiet resulting in higher HDL-C and ucOC levels though the improvement of MetS risk factors. This bone protein appeared as a potential biomarker to classify CVR in the MetS population, especially for MetS patients without prevalent T2D. Furthermore, ucOC serum levels could be good predictors of T2D prevalence.

The Role of Bone-Derived Hormones in Glucose Metabolism, Diabetic Kidney Disease, and Cardiovascular Disorders

Bone contributes to supporting the body, protecting the central nervous system and other organs, hematopoiesis, the regulation of mineral metabolism (mainly calcium and phosphate), and assists in respiration. Bone has many functions in the body. Recently, it was revealed that bone also works as an endocrine organ and secretes several systemic humoral factors, including fibroblast growth factor 23 (FGF23), osteocalcin (OC), sclerostin, and lipocalin 2. Bone can communicate with other organs via these hormones. In particular, it has been reported that these bone-derived hormones are involved in glucose metabolism and diabetic complications. Some functions of these bone-derived hormones can become useful biomarkers that predict the incidence of diabetes and the progression of diabetic complications. Furthermore, other functions are considered to be targets for the prevention or treatment of diabetes and its complications. As is well known, diabetes is now a worldwide health problem, and many efforts have been made to treat diabetes. Thus, further investigations of the endocrine system through bone-derived hormones may provide us with new perspectives on the prediction, prevention, and treatment of diabetes. In this review, we summarize the role of bone-derived hormones in glucose metabolism, diabetic kidney disease, and cardiovascular disorders.

Role of circulating molecules in age-related cardiovascular and metabolic disorders

Studies analyzing heterochronic parabiosis mice models showed that molecules in the blood of young mice rejuvenate aged mice. Therefore, blood-based therapies have become one of the therapeutic approaches to be considered for age-related diseases. Blood includes numerous biologically active molecules such as proteins, metabolites, hormones, miRNAs, etc. and accumulating evidence indicates some of these change their concentration with chronological aging or age-related disorders. The level of some circulating molecules showed a negative or positive correlation with all-cause mortality, cardiovascular events, or metabolic disorders. Through analyses of clinical/translation/basic research, some molecules were focused on as therapeutic targets. One approach is the supplementation of circulating anti-aging molecules. Favorable results in preclinical studies let some molecules to be tested in humans. These showed beneficial or neutral results, and some were inconsistent. Studies with rodents and humans indicate circulating molecules can be recognized as biomarkers or therapeutic targets mediating their pro-aging or anti-aging effects. Characterization of these molecules with aging, testing their biological effects, and finding mimetics of young systemic milieu continue to be an interesting and important research topic to be explored.

Anthocyanin Protects Cardiac Function and Cardiac Fibroblasts From High-Glucose Induced Inflammation and Myocardial Fibrosis by Inhibiting IL-17

Diabetic cardiomyopathy (DCM) is one of the major causes of death in diabetic patients. Its pathogenesis involves inflammation and fibrosis that damages the heart tissue and impairs cardiac function. Interleukin (IL)-17, a pro-inflammatory cytokine that plays an important role in a variety of chronic inflammatory processes can serve as an attractive therapeutic target. Anthocyanin, a water-soluble natural pigment, possesses impressive anti-inflammatory activity. However, its role in DCM is unclear. Hence, we investigated the protective effect of anthocyanin on the cardiovascular complications of diabetes using a mouse type 1 diabetes mellitus model induced by streptozotocin. Cardiac function and structural alterations in diabetic mice were tested by echocardiography, hematoxylin and eosin staining, and Masson trichrome staining. Immunohistochemistry was performed to evaluate the distribution and deposition of IL-17 and collagen I and III from the left ventricular tissues of diabetic mice. Cell viability was measured using the methyl thiazolyl tetrazolium assay. Protein levels of IL-17, tumor necrosis factor α, IL-1β, and IL-6 were determined using enzyme-linked immunosorbent assay. IL-17 and collagen I and III were detected by western blotting and immunofluorescence, and their mRNA levels were quantified using quantitative reverse transcription PCR. We observed that anthocyanin lowered blood glucose, improved cardiac function, and alleviated inflammation and fibrosis in the heart tissue of diabetic mice. Meanwhile, anthocyanin reduced the expression of IL-17 in high-glucose-treated cardiac fibroblasts and exhibited an anti-inflammatory effect. Deposition of collagen I and III was also decreased by anthocyanin, suggesting that anthocyanin contributes to alleviating myocardial fibrosis. In summary, anthocyanin could protect cardiac function and inhibit IL-17-related inflammation and fibrosis, which indicates its therapeutic potential in the treatment of diabetes mellitus-related complications.

Polydatin and polydatin-loaded chitosan nanoparticles attenuate diabetic cardiomyopathy in rats

Hyperglycemia is associated with impairment of heart function. The current study aimed to investigate the ameliorative effect of polydatin-loaded chitosan nanoparticles (PD-CSNPs), polydatin (PD) and metformin (MET) on diabetic cardiomyopathy in rats. Rats divided into six groups; normal-control, diabetic-control, diabetic + CSNPs (diabetic rats treated with 50 mg/kg blank chitosan nanoparticles), diabetic + PD-CSNPs (diabetic rats treated with PD-CSNPs equivalent to 50 mg/kg of polydatin), diabetic + PD (diabetic rats given 50 mg/kg polydatin), diabetic + MET (diabetic rats given 100 mg/kg metformin), orally and daily for 4 weeks. Treatment of diabetic rats with PD-CSNPs, PD and MET showed a significant reduction in the values of glucose and glycosylated hemoglobin with improvement in heart function biomarkers through decreasing serum creatine kinase and creatine kinase myocardial band activities compared to diabetic control. The treatment agents also suppressed the elevated lipid peroxidation product, increased values of glutathione content, superoxide dismutase, superoxide peroxidase, and catalase activities in the heart of diabetic treated rats. Furthermore, PD-CSNPs, PD and MET decreased heart tissue levels of a pro-inflammatory cytokine; tumor necrosis factor-alpha and nuclear factor-kappa β, upregulation of heart gene expressions; nuclear factor erythroid 2-related factor 2 and heme oxygenase-1. Histological and ultrastructural examinations revealed the ameliorative effect of PD-CSNPs, PD and MET against the harmful of diabetic cardiomyopathy by reducing the cardiac fibers, necrotic cardiac myocytes, inflammatory cell infiltration, and the arrangement of the myofibrils and intercalated discs. In conclusion, the new formula of PD-CSNPs was more effective than PD and MET in amelioration the diabetic cardiomyopathy through its antioxidant, anti-inflammatory and prolonged-release properties.

Roles of bone-derived hormones in type 2 diabetes and cardiovascular pathophysiology

Background

Emerging evidence demonstrates that bone is an endocrine organ capable of influencing multiple physiological and pathological processes through the secretion of hormones. Recent research suggests complex crosstalk between the bone and other metabolic and cardiovascular tissues. It was uncovered that three of these bone-derived hormones—osteocalcin, lipocalin 2, and sclerostin—are involved in the endocrine regulations of cardiometabolic health and play vital roles in the pathophysiological process of developing cardiometabolic syndromes such as type 2 diabetes and cardiovascular disease. Chronic low-grade inflammation is one of the hallmarks of cardiometabolic diseases and a major contributor to disease progression. Novel evidence also implicates important roles of bone-derived hormones in the regulation of chronic inflammation.

Scope of review

In this review, we provide a detailed overview of the physiological and pathological roles of osteocalcin, lipocalin 2, and sclerostin in cardiometabolic health regulation and disease development, with a focus on the modulation of chronic inflammation.

Major conclusions

Evidence supports that osteocalcin has a protective role in cardiometabolic health, and an increase of lipocalin 2 contributes to the development of cardiometabolic diseases partly via pro-inflammatory effects. The roles of sclerostin appear to be complicated: It exerts pro-adiposity and pro-insulin resistance effects in type 2 diabetes and has an anti-calcification effect during cardiovascular disease. A better understanding of the actions of these bone-derived hormones in the pathophysiology of cardiometabolic diseases will provide crucial insights to help further research develop new therapeutic strategies to treat these diseases.

LncRNA MALAT1 regulates diabetic cardiac fibroblasts through the Hippo-YAP signaling pathway

Diabetic cardiomyopathy (DCM) is a major diabetes-related microvascular disease. LncRNA MALAT1 is widely expressed in cardiomyocytes responding to hypoxia and high levels of glucose (high glucose). In this study, cardiac fibroblasts (CFs) were transfected with si-MALAT1 and exposed to high glucose. CFs in the high glucose groups were treated with 30 mmol/L glucose, and the control CFs were treated with 5.5 mmol/L glucose. The expression of MALAT1 in the nucleus and cytoplasm of CFs was detected. The biological behavior of CFs, as well as collagen production, activity of the Hippo-YAP pathway, and nuclear localization of YAP were measured. Mouse models of DCM were established to observe the pathological changes to myocardium and determine the levels of collagen I, Bax, and Bcl-2. The interaction between MALAT1 and YAP was analyzed, and CREB expression in the high-glucose treated CFs was detected. MALAT1 was upregulated in high-glucose CFs and located in the nucleus. High-glucose increased collagen production, inflammation, cell proliferation, cell invasiveness, and phosphorylation of MST1 and LATS1, and also promoted nuclear translocation of YAP. These trends in high-glucose treated CFs and the DCM mice were reversed by transfection with si-MALAT1. MALAT1 positively regulated the nuclear translocation of YAP by binding to CREB. CREB levels were increased in the high-glucose CFs, but decreased after silencing MALAT1. These results indicate that si-MALAT1 reduces inflammation and collagen accumulation in high-glucose CFs and DCM mice via the Hippo-YAP pathway and CREB.

Circulating Undercarboxylated Osteocalcin as Estimator of Cardiovascular and Type 2 Diabetes Risk in Metabolic Syndrome Patients

Undercarboxylated osteocalcin (ucOC) could be a biomarker of glucose disturbances and cardiovascular risk. Our study aimed to determine the association between serum levels of ucOC and cardiovascular risk in metabolic syndrome (MetS) patients and to analyse its potential role as estimator of type 2 diabetes (T2D) risk in this population. This cross-sectional study included 235 patients with MetS, 53.2% women, aged 55–75 years. Circulating ucOC levels were measured by ELISA. Cardiovascular risk was determined as Z-score of the diagnostic criteria for MetS (CV-ZS). Linear regression model was performed to analyse the association between circulating ucOC and CV-ZS. A receiver operating curve (ROC) was performed to analyse the usefulness of ucOC as T2D risk estimator. Patients above the CV-ZS median showed significant lower ucOC levels. We found an inverse association between ucOC levels and CV-ZS in MetS patients without T2D. Patients with ucOC levels below the 25^th percentile showed worse cardiometabolic profile and higher cardiovascular and T2D risk. The area under the curve performed better when ucOC levels were included along with the classic T2D risk factors. The measurement of circulating ucOC could be a useful tool to identify increased cardiovascular and T2D risk in MetS patients without T2D.