Potential Drug Combinations to Reduce Cardiovascular Disease Burden in Diabetes

Cellular interplay between cardiomyocytes and non-myocytes in diabetic cardiomyopathy

Patients with Type 2 diabetes mellitus (T2DM) frequently exhibit a distinctive cardiac phenotype known as diabetic cardiomyopathy. Cardiac complications associated with T2DM include cardiac inflammation, hypertrophy, fibrosis and diastolic dysfunction in the early stages of the disease, which can progress to systolic dysfunction and heart failure. Effective therapeutic options for diabetic cardiomyopathy are limited and often have conflicting results. The lack of effective treatments for diabetic cardiomyopathy is due in part, to our poor understanding of the disease development and progression, as well as a lack of robust and valid preclinical human models that can accurately recapitulate the pathophysiology of the human heart. In addition to cardiomyocytes, the heart contains a heterogeneous population of non-myocytes including fibroblasts, vascular cells, autonomic neurons and immune cells. These cardiac non-myocytes play important roles in cardiac homeostasis and disease, yet the effect of hyperglycaemia and hyperlipidaemia on these cell types are often overlooked in preclinical models of diabetic cardiomyopathy. The advent of human induced pluripotent stem cells provides a new paradigm in which to model diabetic cardiomyopathy as they can be differentiated into all cell types in the human heart. This review will discuss the roles of cardiac non-myocytes and their dynamic intercellular interactions in the pathogenesis of diabetic cardiomyopathy. We will also discuss the use of sodium-glucose cotransporter 2 inhibitors as a therapy for diabetic cardiomyopathy and their known impacts on non-myocytes. These developments will no doubt facilitate the discovery of novel treatment targets for preventing the onset and progression of diabetic cardiomyopathy.

Dapagliflozin exerts anti-inflammatory effects via inhibition of LPS-induced TLR-4 overexpression and NF-κB activation in human endothelial cells and differentiated macrophages

Evidence has demonstrated that a new class of anti-diabetic drugs, sodium-glucose co-transporter 2 (SGLT2) inhibitors, could exert beneficial effects on atherosclerotic complications of diabetes. Atherosclerosis is widely accepted as an inflammatory disease. Therefore, we aimed to assess the direct anti-inflammatory effects of SGLT2 inhibitors dapagliflozin (DAPA) on two cell types involved in the process of atherogenesis. Human umbilical vein endothelial cells (HUVECs) and macrophages were exposed to DAPA and lipopolysaccharide (LPS 20 ng/mL) for 24 h under normal (5.5 mmol/L, NG) or high glucose (25 mmol/L, HG) conditions. Then, levels of TLR-4/p-NF-κB, inflammatory cytokines, inflammation-related miR-146a and miR-155 as well as alteration in the ratio of M1/M2 macrophage polarization was assessed. DAPA (0.5 μM) could significantly attenuate LPS-induced TLR-4 overexpression (23.9% and 33.1% under NG and HG conditions in HUVECs and 53.3% and 52.4% under NG and HG states in macrophages, respectively). NF-κB p65 phosphorylation was also significantly decreased to 30.1% under NG condition in HUVECs and 51.9% and 34.5% under NG and HG states in macrophages by 0.5 μM DAPA. Moreover, DAPA elevated expression levels of anti-inflammatory miR-146a, while values of miR-155 decreased in those cells. DAPA also caused a shift from inflammatory M1 macrophages toward M2-dominant macrophages. These data suggest that regardless of glucose concentrations, DAPA could exert direct anti-inflammatory effects, at least partly, by inhibiting the expression of TLR-4 and activation of NF-κB along with the secretion of pro-inflammatory mediators.

Modulation of Insulin Resistance, Dyslipidemia and Serum Metabolome in iNOS Knockout Mice following Treatment with Nitrite, Metformin, Pioglitazone, and a Combination of Ampicillin and Neomycin

Oxidative and nitrosative stress plays a pivotal role in the incidence of metabolic disorders. Studies from this lab and others in iNOS-/- mice have demonstrated occurrence of insulin resistance (IR), hyperglycemia and dyslipidemia highlighting the importance of optimal redox balance. The present study evaluates role of nitrite, L-arginine, antidiabetics (metformin, pioglitazone) and antibiotics (ampicillin-neomycin combination, metronidazole) on metabolic perturbations observed in iNOS-/- mice. The animals were monitored for glucose tolerance (IPGTT), IR (insulin, HOMA-IR, QUICKI), circulating lipids and serum metabolomics (LC-MS). Hyperglycemia, hyperinsulinemia and IR were rescued by nitrite, antidiabetics, and antibiotics treatments in iNOS-/- mice. Glucose intolerance was improved with nitrite, metformin and pioglitazone treatment, while ampicillin-neomycin combination normalised the glucose utilization in iNOS-/- mice. Increased serum phosphatidylethanolamine lipids in iNOS-/- mice were reversed by metformin, pioglitazone and ampicillin-neomycin; dyslipidemia was however marginally improved by nitrite treatment. The metabolic improvements were associated with changes in selected serum metabolites-purines, ceramide, 10-hydroxydecanoate, glucosaminate, diosmetin, sebacic acid, 3-nitrotyrosine and cysteamine. Bacterial metabolites-hippurate, indole-3-ethanol; IR marker-aminoadipate and oxidative stress marker-ophthalmate were reduced by pioglitazone and ampicillin-neomycin, but not by nitrite and metformin treatment. Results obtained in the present study suggest a crucial role of gut microbiota in the metabolic perturbations observed in iNOS-/- mice.

Rice bran triterpenoids improve postprandial hyperglycemia in healthy male adults: a randomized, double-blind, placebo-controlled study

Background

Compared to white rice, brown rice induces a lower glycemic response in healthy and diabetic humans. This effect is partly attributed to the higher amounts of water- or oil-soluble bran components and dietary fiber in brown rice. We hypothesized that dietary supplementation with oil-soluble rice bran triterpenoids (RBTs; triterpene alcohol and sterol prepared from rice bran) might reduce the incidence of postprandial hyperglycemia in healthy humans.

Objective

We examined the acute effects of a single RBT-supplemented meal on the postprandial blood glucose responses of healthy male adults in a double-blind, randomized, placebo-controlled, crossover trial.

Design

Nineteen subjects consumed a test meal containing either placebo- or RBT-supplemented olive oil. Blood biomarkers were evaluated in a fasting state and up to 240 min postprandially.

Results

Compared to the placebo-supplemented meal, the RBT-supplemented meal significantly suppressed the increase in postprandial blood glucose level. A subclass analysis revealed that RBT-supplemented oil significantly reduced blood glucose increases in subjects with higher postprandial blood glucose elevations. Postprandial increases in blood insulin, glucose-dependent insulinotropic peptide (GIP), and glucagon-like peptide-1 (GLP-1) levels did not differ between the groups.

Conclusion

These results suggest that RBT consumption improves postprandial hyperglycemia in healthy humans, especially those with higher postprandial glucose increases.

Mechanism of YLTZ on glycolipid metabolism based on UPLC/TOF/MS metabolomics

Type 2 diabetes mellitus (T2DM) is a metabolic disease characterized by dysfunction of glycolipid metabolism. YLTZ is used to treat hyperlipidemia, yet its hypolipidemic and hypoglycemic mechanism on T2DM are unknown. Thus, UPLC/TOF/MS was applied in this study to identify the potential bio-markers, and deduce the possible metabolic pathways. According to bio-indexes, the increased blood lipid levels, including TC, TG, LDL and FA, and the decreased HDL, the elevated glucose, reduced insulin level and impaired OGTT were observed in diabetic rat model. While YLTZ can decrease the lipid levels and glucose content, as well as increased insulin standards and improve OGTT. After data from UPLC/TOF/MS processed, 17 metabolites were obtained, including phospholipids (LPCs, PCs and PGP (18:1)), beta-oxidation production (HAA, VAG and CNE) and precursors (THA), bile acid (CA, CDCA and IDCA), hydrolysate of TG (MG (22:4)), glycometabolism (G6P), cholesterol-driven synthetics (ADO) and production of arachidonate acid (THETA). As a result, YLTZ was able to reduce LPCs, PCs, PGP (18:1), HAA, VAG, CNE, CA, ADO and THETA, as well as enhance MG (22:4) and G6P. After analyzing results, several metabolic pathways were deduced, which containing, cholesterol synthesis and elimination, FA beta-oxidation, TG hydrolysis, phospholipids synthesis, glycolysis, gluconeogenesis and inflammation. Consequently, YLTZ performed to prohibit the FA beta-oxidation, synthesis of cholesterol and phospholipids, gluconeogenesis and inflammation level, as well as promote TG hydrolysis, glycolysis and blood circulation. Hence, applying metabonomics in TCM research can uncover its pharmacological edges, elucidating comprehensively that YLTZ has capacity of hypolipidemic, hypoglycemic and promoting blood circulation, matching the effect of removing blood stasis, eliminating phlegm and dampness.

Effects of immediate-release niacin and dietary fatty acids on acute insulin and lipid status in individuals with metabolic syndrome

BACKGROUND

The nature of dietary fats profoundly affects postprandial hypertriglyceridemia and glucose homeostasis. Niacin is a potent lipid-lowering agent. However, limited data exist on postprandial triglycerides and glycemic control following co-administration of high-fat meals with a single dose of niacin in subjects with metabolic syndrome (MetS). The aim of the study was to explore whether a fat challenge containing predominantly saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs) or MUFAs plus omega-3 long-chain polyunsaturated (LCPUFAs) fatty acids together with a single dose of immediate-release niacin have a relevant role in postprandial insulin and lipid status in subjects with MetS.

RESULTS

In a randomized crossover within-subject design, 16 men with MetS were given a single dose of immediate-release niacin (2 g) and ∼15 cal kg^-1 body weight meals containing either SFAs, MUFAs, MUFAs plus omega-3 LCPUFAs or no fat. At baseline and hourly over 6 h, plasma glucose, insulin, C-peptide, triglycerides, free fatty acids (FFAs), total cholesterol, and both high- and low-density lipoprotein cholesterol were assessed. Co-administered with niacin, high-fat meals significantly increased the postprandial concentrations of glucose, insulin, C-peptide, triglycerides, FFAs and postprandial indices of β-cell function. However, postprandial indices of insulin sensitivity were significantly decreased. These effects were significantly attenuated with MUFAs or MUFAs plus omega-3 LCPUFAs when compared with SFAs.

CONCLUSION

In the setting of niacin co-administration and compared to dietary SFAs, MUFAs limit the postprandial insulin, triglyceride and FFA excursions, and improve postprandial glucose homeostasis in MetS. © 2017 Society of Chemical Industry.

Fenofibrate decreases the bone quality by down regulating Runx2 in high-fat-diet induced Type 2 diabetes mellitus mouse model

Background

This study is to investigate the effect of fenofibrate on the bone quality of Type 2 diabetes mellitus (T2DM) mouse model.

Methods

T2DM mouse model was induced by high-fat-diet, and the mice were treated with fenofibrate (100 mg/kg) (DIO-FENO) or PBS (DIO-PBS) for 4 weeks. The bone microstructure and biomechanical properties of femora were analyzed by micro-CT and 3-Point bending test. The protein expression was detected by immunohistochemical staining and Western blot. The cell apoptosis was evaluated by TUNEL staining. The Bcl2, caspase 3, and osteoblast marker genes were detected by RT-qPCR.

Results

The biomechanical properties of bones from DIO-FENO group were significantly lower than those in the control and DIO-PBS groups. Besides, the trabecular number was lower than those of the other groups, though the cortical porosity was decreased compared with that of DIO-PBS group because of the increase of apoptotic cells. The expression of osteocalcin and collagen I were decreased after treatment with fenofibrate in T2DM mice. Moreover, the cell viability was decreased after treated with different concentrations of fenofibrate, and the expression of Runx2 decreased after treated with high dose of fenofibrate.

Conclusion

Fenofibrate decreases the bone quality of T2DM mice through decreasing the expression of collagen I and osteocalcin, which may be resulted from the down regulation of Runx2 expression.

A mini-network balance model for evaluating the progression of cardiovascular complications in Goto-Kakizaki rats

Cardiovascular complications represent a leading cause of mortality in patients with type 2 diabetes mellitus (T2DM). During such complicated progression, subtle variations in the cardiovascular risk (CVR)-related biomarkers have been used to identify cardiovascular disease at the incipient stage. In this study we attempt to integrally characterize the progression of cardiovascular complications and to assess the beneficial effects of metformin combined with salvianolic acid A (Sal A), in Goto-Kakizaki (GK) rats with spontaneous T2DM. The rats were treated with metformin (200 mg·kg^-1·d^-1, ig) alone or in combination with Sal A (1 mg·kg^-1·d^-1, ip) at ages from 8 to 22 weeks. During the treatment, the levels of asymmetric dimethylarginine, L-arginine, superoxide dismutase, malondialdehyde, glucose, high density lipoprotein and low density lipoprotein were assessed. Based on alterations in these biomarkers, a mini-network balance model was established using matrixes and vectors. Radar charts were created to visually depict the disruption of CVR-related modules (endothelial function, oxidative stress, glycation and lipid profiles). The description for the progression of cardiovascular disorder was quantitatively represented by u, the dynamic parameter of the model. The modeling results suggested that untreated GK rats tended to have more severe cardiovascular complications than the treatment groups. Metformin monotherapy retarded disease deterioration, whereas the combination treatment ameliorated the disease progression via restoring the balance. The current study, which focused on the balance of the mini-network and interactions among CVR-related modules, proposes a novel method for evaluating the progression of cardiovascular complications in T2DM as well as a more beneficial intervention strategy.