The role of endothelium in the pathogenesis of diabetic microangiopathy

NF-ĸB axis in diabetic neuropathy, cardiomyopathy and nephropathy: A roadmap from molecular intervention to therapeutic strategies

Diabetes mellitus (DM) is a metabolic illness defined by elevated blood glucose levels, mediating various tissue alterations, including the dysfunction of vital organs. Diabetes mellitus (DM) can lead to many consequences that specifically affect the brain, heart, and kidneys. These issues are known as neuropathy, cardiomyopathy, and nephropathy, respectively. Inflammation is acknowledged as a pivotal biological mechanism that contributes to the development of various diabetes consequences. NF-κB modulates inflammation and the immune system at the cellular level. Its abnormal regulation has been identified in several clinical situations, including cancer, inflammatory bowel illnesses, cardiovascular diseases, and Diabetes Mellitus (DM). The purpose of this review is to evaluate the potential impact of NF-κB on complications associated with DM. Enhanced NF-κB activity promotes inflammation, resulting in cellular harm and compromised organ performance. Phytochemicals, which are therapeutic molecules, can potentially decline the NF-κB level, therefore alleviating inflammation and the progression of problems correlated with DM. More importantly, the regulation of NF-κB can be influenced by various factors, such as TLR4 in DM. Highlighting these factors can facilitate the development of novel therapies in the future.

Yes-Associated Protein and Transcriptional Coactivator with PDZ-Binding Motif in Cardiovascular Diseases

Yes-associated protein (YAP, also known as YAP1) and its paralogue TAZ (with a PDZ-binding motif) are transcriptional coactivators that switch between the cytoplasm and nucleus and regulate the organ size and tissue homeostasis. This review focuses on the research progress on YAP/TAZ signaling proteins in myocardial infarction, cardiac remodeling, hypertension and coronary heart disease, cardiomyopathy, and aortic disease. Based on preclinical studies on YAP/TAZ signaling proteins in cellular/animal models and clinical patients, the potential roles of YAP/TAZ proteins in some cardiovascular diseases (CVDs) are summarized.

Endothelial Dysfunction and Diabetic Cardiomyopathy

The cardiovascular complications contribute to a majority of diabetes associated morbidity and mortality, accounting for 44% of death in those patients with type 1 diabetes mellitus (DM) and 52% of deaths in type 2 DM. Diabetes elicits cardiovascular dysfunction through 2 major mechanisms: ischemic and non-ischemic. Non-ischemic injury is usually under-recognized although common in DM patients, and also a pathogenic factor of heart failure in those diabetic individuals complicated with ischemic heart disease. Diabetic cardiomyopathy (DCM) is defined as a heart disease in which the myocardium is structurally and functionally abnormal in the absence of coronary artery disease, hypertensive, valvular, or congenital heart disorders in diabetic patients, theoretically caused by non-ischemic injury solely. Current therapeutic strategies targeting DCM mainly address the increased blood glucose levels, however, the effects on heart function are disappointed. Accumulating data indicate endothelial dysfunction plays a critical role in the initiation and development of DCM. Hyperglycemia, hyperinsulinemia, and insulin resistance cause the damages of endothelial function, including barrier dysfunction, impaired nitric oxide (NO) activity, excessive reactive oxygen species (ROS) production, oxidative stress, and inflammatory dysregulation. In turn, endothelial dysfunction promotes impaired myocardial metabolism, intracellular Ca²⁺ mishandling, endoplasmic reticulum (ER) stress, mitochondrial defect, accumulation of advanced glycation end products, and extracellular matrix (ECM) deposit, leads to cardiac stiffness, fibrosis, and remodeling, eventually results in cardiac diastolic dysfunction, systolic dysfunction, and heart failure. While endothelial dysfunction is closely related to cardiac dysfunction and heart failure seen in DCM, clinical strategies for restoring endothelial function are still missing. This review summarizes the timely findings related to the effects of endothelial dysfunction on the disorder of myocardium as well as cardiac function, provides mechanical insights in pathogenesis and pathophysiology of DCM developing, and highlights potential therapeutic targets.

Is diabetes a hypercoagulable state? A critical appraisal

Diabetes mellitus (DM), a chronic disease with an increasing incidence and prevalence worldwide, is an established risk factor for arterial cardiovascular, cerebrovascular and peripheral vascular diseases including acute myocardial infarction, stroke and peripheral artery disease. On the other hand, its role as independent risk factor for venous thromboembolism (VTE) and for cardioembolic stroke or systemic embolism (SE) in patients with atrial fibrillation (AF) is more conflicting. Venous and arterial thromboses have traditionally been regarded as separate diseases, but recent studies have documented an association between these vascular complications. Cardiovascular risk factors may contribute to unprovoked VTE, and VTE may be an early symptomatic event in patients at high cardiovascular risk, including diabetic patients. Compelling evidences suggest that DM is associated with a higher risk of development and progression of AF. Furthermore, in AF patients with a coexisting DM the risk of cardioembolic stroke/SE appeared increased. Thus, DM has been included as one of the items of the CHADS2 score and of the subsequent CHA2DS2-VASc score that have been developed to assess the arterial tromboembolic risk of AF patients. Such a high incidence of thromboembolic events observed in these clinical subsets may be attributable to the DM-related prothrombotic state due to a number of changes in primary and secondary hemostasis. Although of potential clinical interest, unfortunately, to date, no study has properly evaluated the effects of drugs used to control blood glucose levels on the risk of venous thromboembolism and arterial cardioembolic events in patients with DM.

Effects of Momordica charantia L. on the blood rheological properties in diabetic patients

An evaluation of the rheological properties and the effects of Momordica. charantia L. (M. charantia) nanoparticles and polyethylene glycol (PEG) microspheres adsorbed with M. charantia nanoparticles on the blood of hyperglycemic patients is presented. Blood samples were collected according to glycemic status: normoglycemic (N = 56) and hyperglycemic (N = 26). General and hematological characteristics were determined. Blood rheological parameters were determined at room temperature and under a temperature scan. We determined the effects on whole blood viscosity of treatment with an extract of M. charantia, PEG, or PEG microspheres adsorbed with plant extract. The viscosity of the blood of hyperglycemic patients is greater than that of normoglycemic patients. Nanoparticles of M. charantia extracts lowered blood viscosity at equivalent rates in normo- and hyperglycemic individuals. PEG microspheres did not reduce blood viscosity in hyperglycemic individuals. However, PEG microspheres adsorbed with nanofraction extracts of M. charantia reduced blood viscosity. These data suggest that the effects of diabetes on the viscosity of the blood should be considered. The use of a nanoparticles extract of M. charantia and its adsorption on PEG microspheres may represent an alternative for the control and treatment of blood disorders in diabetic patients.

Effect of Indian herbal hypoglycemic agents on antioxidant capacity and trace elements content in diabetic rats

In the present investigation we report the protective potential of some herbal hypoglycemic agents on antioxidant status and levels of metal ions in streptozotocin-induced diabetic rats. Furthermore, in vitro antioxidant activity of the herbs was also evaluated. Induction of diabetes mellitus in rats caused an increase in blood lipid peroxide levels that was associated with the reduced activity of red blood cell (RBC) antioxidant enzymes--namely, superoxide dismutase, catalase, glutathione reductase, and glutathione peroxidase--along with depletion of plasma reduced glutathione (GSH) and copper, zinc, iron, magnesium, and selenium levels. Oral treatment of diabetic rats with Allium sativum, Azadirachta indica, Momordica charantia, and Ocimum sanctum extracts (500 mg/kg of body weight) not only lowered the blood glucose level but also inhibited the formation of lipid peroxides, reactivated the antioxidant enzymes, and restored levels of GSH and metals in the above-mentioned model. The herbal extracts (50-500 microg) inhibited the generation of superoxide anions (O(2)(-.)) in both enzymatic and nonenzymatic in vitro systems. These preparations also inhibited the ferrous-sodium ascorbate-induced formation of lipid peroxides in RBCs. The in vivo and in vitro protective effects of the above-mentioned herbal drugs were also compared with that of glibenclamide. On the basis of our results, we conclude that the above-mentioned herbal plants not only possess hypoglycemic properties, but they also decrease oxidative load in diabetes mellitus. Therefore, we propose that long-term use of such agents might help in the prevention of diabetes-associated complications. However, the extrapolation of these results to humans needs further in-depth study.

Chronic inhibition of p38MAPK improves cardiac and endothelial function in experimental diabetes mellitus

To investigate the influence of p38 mitogen activated kinase (p38MAPK) on the development of diabetic cardiac and endothelial dysfunction, we assessed left ventricular and vascular function as well as inflammatory markers in diabetic rats after chronic pharmacological inhibition of p38MAPK. Diabetes mellitus was induced in rats by a single injection of streptozotocin. Rats were treated with the p38MAPK inhibitor SB 239063 (40 mg/kg/day, p.o.) or vehicle. 48 days after diabetes mellitus-induction, left ventricular function and vascular function were assessed in vivo by TIP-catheter and the autoperfused hindlimb, respectively. Cell adhesion molecules staining was quantified immunohistochemically in the heart and quadriceps muscle, respectively, as well as cardiac phosphorylation of p38MAPK by Western blot analysis. Treated and untreated diabetic groups displayed similar severe hyperglycemia. Left ventricular and endothelial function were impaired in the untreated diabetic group compared to controls (dp/dtmax: -40%, dp/dtmin: +49%, maximal vasodilatation: -57%; P < 0.05) associated with significantly increased cardiac (3-fold) and peripheral cell adhesion molecules staining, respectively. Treatment of diabetic rats with SB 239063 led to a significant reduction of diabetes-induced enhancement of p38MAPK phosphorylation associated with improved left ventricular function (dp/dtmax: +39%, dp/dtmin: +47%; P < 0.05) and peripheral endothelial function (maximal vasodilatation: +71%; P < 0.05) under diabetic conditions. This was associated with reduced cardiac and peripheral inflammation indexed by reduced adhesion molecules content. Pharmacological inhibition of p38MAPK is sufficient to mitigate the development of diabetic cardiac and endothelial dysfunction despite of hyperglycemia. Our data suggest that the anti-inflammatory properties due to p38MAPK inhibition contribute to these beneficial cardiovascular effects.

Vascular endothelial dysfunction in diabetic cardiomyopathy: pathogenesis and potential treatment targets

Cardiovascular complications account for significant morbidity and mortality in the diabetic population. Diabetic cardiomyopathy, a prominent cardiovascular complication, has been recognized as a microvascular disease that may lead to heart failure. Pathogenesis of diabetic cardiomyopathy involves vascular endothelial cell dysfunction, as well as myocyte necrosis. Clinical trials have identified hyperglycemia as the key determinant in the development of chronic diabetic complications. Sustained hyperglycemia induces several biochemical changes including increased non-enzymatic glycation, sorbitol-myoinositol-mediated changes, redox potential alterations, and protein kinase C (PKC) activation, all of which have been implicated in diabetic cardiomyopathy. Other contributing metabolic abnormalities may include defective glucose transport, increased myocyte fatty acid uptake, and dysmetabolism. These biochemical changes manifest as hemodynamic alterations and structural changes that include capillary basement membrane (BM) thickening, interstitial fibrosis, and myocyte hypertrophy and necrosis. Diabetes-mediated biochemical anomalies show cross-interaction and complex interplay culminating in the activation of several intracellular signaling molecules. Studies in both animal and human diabetes have shown alteration of several factors including vasoactive molecules that may be instrumental in mediating structural and functional deficits at both the early and the late stages of the disease. In this review, we will highlight some of the important vascular changes leading to diabetic cardiomyopathy and discuss the emerging potential therapeutic interventions.

Diabetes and advanced glycation endproducts

Bio-reactive advanced glycation endproducts (AGE) alter the structure and function of molecules in biological systems and increase oxidative stress. These adverse effects of both exogenous and endogenously derived AGE have been implicated in the pathogenesis of diabetic complications and changes associated with ageing including atherosclerosis, renal, eye and neurological disease. Specific AGE receptors and nonreceptor mechanisms contribute to these processes but also assist in the removal and degradation of AGE. The final disposal of AGE depends on renal clearance. Promising pharmacologic strategies to prevent AGE formation, reduce AGE toxicity, and/or inactivate AGE are under investigation.

The pathomorphological alterations of endocardial endothelium in experimental diabetes and diabetes associated with hyperlipidemia

The structural alterations of endocardial endothelial cells of the heart right atrium and left ventricle were investigated in Golden Syrian hamsters subjected to streptozotocin-induced diabetes and to a combination of diabetes and diet-induced hyperlipidemia. Animals were examined at time intervals ranging from 2 weeks to 6 months. Anionic sites of the endothelial plasmalemma were visualized by in situ perfusion of cationized ferritin. The results indicated that: (a) both atrial and ventricular endocardial endothelium are affected in streptozotocin-induced diabetes: endothelium converts from continuous into a fenestrated type, (b) although the anionic charge of the plasmalemma decreased in advanced diabetes, the newly formed fenestrae highly bound cationized ferritin, (c) combined diabetes and hyperlipidemia induced more severe alterations of endocardial endothelium: new permeable endothelial structures were formed (transendothelial channels, open intercellular junctions, fused plasmalemmal vesicles), and the cells became particularly enriched in cytoskeleton (intermediate filaments and microtubules), (d) the thick subendocardial layer of connective tissue contained, in the combined experimental model, macrophage derived foam cells indicative for the occurrence of alterations of atherosclerotic type.