The Effect of Hypoxia Inducible Factor -1 Alpha and Vascular Endothelial Growth Factor Level in Type 2 Diabetes Microvascular Complications and Development.

Background: Angiogenesis in diabetic patients is often caused by hyperglycemia induced by hypoxia. Objective: The aim of this study was to analyze the serum level of Hypoxia Inducible Factor -1α (HIF-1α) and Vascular Endothelial Growth Factor (VEGF) between March until Desember 2020. Methods: This is a cross-sectional analytic methods, 135 patients with Type 2 Diabetes 48 samples with Microvascular complication and 87 samples with non-microvascular complication were recruited from the various primary health care centers in Medan city and surrounding areas in North Sumatera. VEGF levels and HIF-1α tested were done with ELISA methods in the laboratory of Medical Faculty, Universitas Sumatera Utara. Statistical analysis was performed using the IBM SPSS Statistics version 24. The significance level was set up to 0.005. Results: The median HIF-1 levels in patients with microvascular complications were lower than those without microvascular complications, with a range of HIF-1α values in non-complicated samples (0.02-13.96) ng/ml and a range of HIF-1α values in vascular complications (0.52- 8.87) mg/dL. There was a significant difference in HIF-1α levels in patients with Type-2 DM with complications compared to those without complications (p<0.05). Median VEGF levels were higher in complicated Type-2 DM. There was no difference in VEGF levels in patients with Type-2 DM with complications compared to those without complications (p > 0.005). Conclusion: HIF-1α and VEGF levels showed the development in vascularity. With the higher level of HIF-1α, an increase in VEGF levels were found, indicating the angiogenesis is occurring. Although complications have not yet occurred, it is predicted that high VEGF values will cause vascular complications in the future.

Elevated levels of interleukin-12/23p40 may serve as a potential indicator of dysfunctional heart rate variability in type 2 diabetes.

BACKGROUND: Systemic inflammatory processes plausibly contribute to the development of cardiovascular complications, causing increased morbidity and mortality in type 2 diabetes. Circulating inflammatory markers, i.e., interleukin (IL)-6 and tumour necrosis factor-α, are associated with neurocardiac measures. We examined a broad panel of various inflammatory and inflammation-related serum markers to obtain more detailed insight into the possible neuro-immune interaction between cardiovascular regulation and systemic level of inflammation. METHODS: Serum samples from 100 participants with type 2 diabetes were analysed. Heart rate variability, cardiovascular autonomic reflex tests, and cardiac vagal tone tests were performed based on electrocardiographic readings. Data regarding covariates (demographic-, diabetes-, and cardiovascular risk factors) were registered. RESULTS: Increased serum levels of IL-12/IL-23p40 (p < 0.01) and intercellular adhesion molecule (ICAM)-1 (p < 0.007) were associated with diminished heart rate variability measures. After all adjustments, the associations between IL-12/23p40, SDANN and VLF persisted (p = 0.001). Additionally, serum levels of vascular endothelial growth factor (VEGF)-C were associated with response to standing (p = 0.005). DISCUSSION: The few but robust associations between neurocardiac regulation and serum markers found in this study suggest systemic changes in proinflammatory, endothelial, and lymphatic function, which collectively impacts the systemic cardiovascular function. Our results warrant further exploration of IL-12/IL-23p40, ICAM-1, and VEGF-C as possible cardiovascular biomarkers in T2D that may support future decisions regarding treatment strategies for improved patient care.

N-Acetyl Cysteine, Selenium, and Ascorbic Acid Rescue Diabetic Cardiac Hypertrophy via Mitochondrial-Associated Redox Regulators.

Metabolic disorders often lead to cardiac complications. Metabolic deregulations during diabetic conditions are linked to mitochondrial dysfunctions, which are the key contributing factors in cardiac hypertrophy. However, the underlying mechanisms involved in diabetes-induced cardiac hypertrophy are poorly understood. In the current study, we initially established a diabetic rat model by alloxan-administration, which was validated by peripheral glucose measurement. Diabetic rats displayed myocardial stiffness and fibrosis, changes in heart weight/body weight, heart weight/tibia length ratios, and enhanced size of myocytes, which altogether demonstrated the establishment of diabetic cardiac hypertrophy (DCH). Furthermore, we examined the expression of genes associated with mitochondrial signaling impairment. Our data show that the expression of PGC-1α, cytochrome c, MFN-2, and Drp-1 was deregulated. Mitochondrial-signaling impairment was further validated by redox-system dysregulation, which showed a significant increase in ROS and thiobarbituric acid reactive substances, both in serum and heart tissue, whereas the superoxide dismutase, catalase, and glutathione levels were decreased. Additionally, the expression levels of pro-apoptotic gene PUMA and stress marker GATA-4 genes were elevated, whereas ARC, PPARα, and Bcl-2 expression levels were decreased in the heart tissues of diabetic rats. Importantly, these alloxan-induced impairments were rescued by N-acetyl cysteine, ascorbic acid, and selenium treatment. This was demonstrated by the amelioration of myocardial stiffness, fibrosis, mitochondrial gene expression, lipid profile, restoration of myocyte size, reduced oxidative stress, and the activation of enzymes associated with antioxidant activities. Altogether, these data indicate that the improvement of mitochondrial dysfunction by protective agents such as N-acetyl cysteine, selenium, and ascorbic acid could rescue diabetes-associated cardiac complications, including DCH.

FNDC5/Irisin attenuates diabetic cardiomyopathy in a type 2 diabetes mouse model by activation of integrin αV/ß5-AKT signaling and reduction of oxidative/nitrosative stress.

Irisin, the cleaved form of the fibronectin type III domain containing 5 (FNDC5) protein, is involved in metabolism and inflammation. Recent findings indicated that irisin participated in cardiovascular physiology and pathology. In this study, we investigated the effects of FNDC5/irisin on diabetic cardiomyopathy (DCM) in type 2 diabetic db/db mice. Downregulation of myocardial FNDC5/irisin protein expression and plasma irisin levels was observed in db/db mice compared to db/+ controls. Moreover, echocardiography revealed that db/db mice exhibited normal cardiac systolic function and impaired diastolic function. Adverse structural remodeling, including cardiomyocyte apoptosis, myocardial fibrosis, and cardiac hypertrophy were observed in the hearts of db/db mice. Sixteen-week-old db/db mice were intramyocardially injected with adenovirus encoding FNDC5 or treated with recombinant human irisin via a peritoneal implant osmotic pump for 4 weeks. Both overexpression of myocardial FNDC5 and exogenous irisin administration attenuated diastolic dysfunction and cardiac structural remodeling in db/db mice. Results from in vitro studies revealed that FNDC5/irisin protein expression was decreased in high glucose (HG)/high fat (HF)-treated cardiomyocytes. Increased levels of inducible nitric oxide synthase (iNOS), NADPH oxidase 2 (NOX2), 3-nitrotyrosine (3-NT), reactive oxygen species (ROS), and peroxynitrite (ONOO-) in HG/HF-treated H9C2 cells provided evidence of oxidative/nitrosative stress, which was alleviated by treatment with FNDC5/irisin. Moreover, the mitochondria membrane potential (ΔΨm) was decreased and cytochrome C was released from mitochondria with increased levels of cleaved caspase-3 in HG/HF-treated H9C2 cells, indicating the presence of mitochondria-dependent apoptosis, which was partially reversed by FNDC5/irisin treatment. Mechanistic studies showed that activation of integrin αVß5-AKT signaling and attenuation of oxidative/nitrosative stress were responsible for the cardioprotective effects of FNDC5/irisin. Therefore, FNDC5/irisin mediates cardioprotection in DCM by inhibiting myocardial apoptosis, myocardial fibrosis, and cardiac hypertrophy. These findings implicate that FNDC5/irisin as a potential therapeutic intervention for DCM, especially in type 2 diabetes mellitus (T2DM).

Metformin impairs homing ability and efficacy of mesenchymal stem cells for cardiac repair in streptozotocin-induced diabetic cardiomyopathy in rats.

Bone marrow-derived mesenchymal stem cells (BM-MSCs) have demonstrated potential in treating diabetic cardiomyopathy. However, patients with diabetes are on multiple drugs and there is a lack of understanding of how transplanted stem cells would respond in presence of such drugs. Metformin is an AMP kinase (AMPK) activator, the widest used antidiabetic drug. In this study, we investigated the effect of metformin on the efficacy of stem cell therapy in a diabetic cardiomyopathy animal model using streptozotocin (STZ) in male Wistar rats. To comprehend the effect of metformin on the efficacy of BM-MSCs, we transplanted BM-MSCs (1 million cells/rat) with or without metformin. Our data demonstrate that transplantation of BM-MSCs prevented cardiac fibrosis and promoted angiogenesis in diabetic hearts. However, metformin supplementation downregulated BM-MSC-mediated cardioprotection. Interestingly, both BM-MSCs and metformin treatment individually improved cardiac function with no synergistic effect of metformin supplementation along with BM-MSCs. Investigating the mechanisms of loss of efficacy of BM-MSCs in the presence of metformin, we found that metformin treatment impairs homing of implanted BM-MSCs in the heart and leads to poor survival of transplanted cells. Furthermore, our data demonstrate that metformin-mediated activation of AMPK is responsible for poor homing and survival of BM-MSCs in the diabetic heart. Hence, the current study confirms that a conflict arises between metformin and BM-MSCs for treating diabetic cardiomyopathy. Approximately 10% of the world population is diabetic to which metformin is prescribed very commonly. Hence, future cell replacement therapies in combination with AMPK inhibitors may be more effective for patients with diabetes.NEW & NOTEWORTHY Metformin treatment reduces the efficacy of mesenchymal stem cell therapy for cardiac repair during diabetic cardiomyopathy. Stem cell therapy in diabetics may be more effective in combination with AMPK inhibitors.

Myocardial glucotoxicity: Mechanisms and potential therapeutic targets.

Besides coronary artery disease, which remains the main cause of heart failure in patients with diabetes, factors independent of coronary artery disease are involved in the development of heart failure in the onset of what is called diabetic cardiomyopathy. Among them, hyperglycaemia - a hallmark of type 2 diabetes - has both acute and chronic deleterious effects on myocardial function, and clearly participates in the establishment of diabetic cardiomyopathy. In the present review, we summarize the cellular and tissular events that occur in a heart exposed to hyperglycaemia, and depict the complex molecular mechanisms proposed to be involved in glucotoxicity. Finally, from a more translational perspective, different therapeutic strategies targeting hyperglycaemia-mediated molecular mechanisms will be detailed.

Fibroblast growth factor-23 is associated with imaging markers of diabetic cardiomyopathy and anti-diabetic therapeutics.

BACKGROUND: The biomarker fibroblast growth factor-23 (FGF-23) has been associated with increased cardiovascular morbidity and mortality in both patients with and without type 2 diabetes. The aim of this study was to evaluate the relationship between FGF-23 and cardiac structure, function and perfusion in patients with type 2 diabetes and normal or mildly impaired kidney function. Furthermore, to investigate the association between FGF-23, anti-diabetes therapy and the classic complications and risk factors associated with type 2 diabetes. METHODS: In this cross-sectional study, 246 patients with type 2 diabetes underwent echocardiography and advanced cardiac magnetic resonance imaging to assess left ventricular (LV) structure and function. In addition, myocardial blood flow (MBF) during rest and pharmacological stress (adenosine 140 µg/kg/min) were evaluated in 183 of the patients. Patients with eGFR < 60 ml/min/1.73 m2 were excluded. RESULTS: Median (Q1-Q3) FGF-23 was 74 (58-91) ng/L. Patients with FGF-23 above the median had lower MBF during stress (2.3 ± 0.9 vs. 2.7 ± 0.9 ml/min/g, P = 0.001) and lower overall myocardial perfusion reserve (MPR) (2.7 ± 0.8 vs. 3.3 ± 1.1, P < 0.001). LV mass (143 ± 40 vs. 138 ± 36 g, P = 0.04) and E/e* (8.5 ± 3.2 vs. 7.6 ± 2.7, P = 0.04) were higher in patients with FGF-23 above the median. In a linear model adjusted for age, sex, eGFR and hypertension, increasing FGF-23 was associated with decreased MPR (P < 0.01, R2 = 0.11) and increased E/e* (P < 0.01, R2 = 0.07). FGF-23 was lower in patients receiving glucagon like peptide-1 (GLP-1) analogues (71 (57-86) vs. 80 (60-98) ng/L, P = 0.01) than in those who did not receive GLP-1 analogues. CONCLUSIONS: In patients with type 2 diabetes and normal or mildly impaired kidney function, increased levels of FGF-23 are associated with impaired cardiac diastolic function and decreased MPR, caused by a decrease in maximal MBF during stress. Use of GLP-1 analogues is associated with decreased levels of FGF-23. Clinical trial registration https://www.clinicaltrials.gov . Unique identifier: NCT02684331. Date of registration: February 18, 2016.

Sustaining Circulating Regulatory T Cell Subset Contributes to the Therapeutic Effect of Paroxetine on Mice With Diabetic Cardiomyopathy.

BACKGROUND: G protein coupled receptor kinase 2 (GRK2) inhibitor, paroxetine, has been approved to ameliorate diabetic cardiomyopathy (DCM). GRK2 is also involved in regulating T cell functions; the potential modifications of paroxetine on the immune response to DCM is unclear.Methods and Results:DCM mouse was induced by high-fat diet (HFD) feeding. A remarkable reduction in the regulatory T (Treg) cell subset in DCM mouse was found by flow cytometry, with impaired cardiac function evaluated by echocardiography. The inhibited Treg differentiation was attributable to insulin chronic stimulation in a GRK2-PI3K-Akt signaling-dependent manner. The selective GRK2 inhibitor, paroxetine, rescued Treg differentiation in vitro and in vivo. Furthermore, heart function, as well as the activation of excitation-contraction coupling proteins such as phospholamban (PLB) and troponin I (TnI) was effectively promoted in paroxetine-treated DCM mice compared with vehicle-treated DCM mice. Blockade of FoxP3 expression sufficiently inhibited the proportion of Treg cells, abolished the protective effect of paroxetine on heart function as well as PLB and TnI activation in HFD-fed mice. Neither paroxetine nor carvedilol could effectively ameliorate the metabolic disorder of HFD mice. CONCLUSIONS: The impaired systolic heart function of DCM mice was effectively improved by paroxetine therapy, partially through restoring the population of circulating Treg cells by targeting the GRK2-PI3K-Akt pathway.

The association between bacterial infections and the risk of coronary heart disease in type 1 diabetes.

BACKGROUND: Diabetes increases the risk of infections and coronary heart disease (CHD). Whether infections increase the risk of CHD and how this applies to individuals with diabetes is unclear. OBJECTIVES: To investigate the association between bacterial infections and the risk of CHD in type 1 diabetes. METHODS: Individuals with type 1 diabetes (n = 3781) were recruited from the Finnish Diabetic Nephropathy Study (FinnDiane), a prospective follow-up study. CHD was defined as incident events: fatal or nonfatal myocardial infarction, coronary artery bypass surgery or percutaneous coronary intervention, identified through national hospital discharge register data. Infections were identified through national register data on all antibiotic purchases from outpatient care. Register data were available from 1 January 1995 to 31 December 2015. Bacterial lipopolysaccharide (LPS) activity was measured from serum samples at baseline. Data on traditional risk factors for CHD were collected during baseline and consecutive visits. RESULTS: Individuals with an incident CHD event (n = 370) had a higher mean number of antibiotic purchases per follow-up year compared to those without incident CHD (1.34 [95% CI: 1.16-1.52], versus 0.79 [0.76-0.82], P < 0.001), as well as higher levels of LPS activity (0.64 [0.60-0.67], versus 0.58 EU mL-1 [0.57-0.59], P < 0.001). In multivariable-adjusted Cox proportional hazards models, the mean number of antibiotic purchases per follow-up year was an independent risk factor for incident CHD (HR 1.21, 95% CI: 1.14-1.29, P < 0.0001). High LPS activity was a risk factor for incident CHD (HR 1.93 [1.34-2.78], P < 0.001) after adjusting for static confounders. CONCLUSION: Bacterial infections are associated with an increased risk of incident CHD in individuals with type 1 diabetes.

Acupuncture Reduces Hypertrophy and Cardiac Fibrosis, and Improves Heart Function in Mice with Diabetic Cardiomyopathy.

PURPOSE: To assess the effects of electro-acupuncture (EA) on glycemic control, myocardial inflammation, and the progression of diabetic cardiomyopathy in mice with type 2 diabetes. METHODS: Db/Db mice received EA at PC6+ST36 (DM-Acu), non-acupoint simulation (DM-Sham), or no treatment (DM). EA was applied for 30 min per day, 5 days a week for 4 weeks. Heart function was assessed by echocardiography. Myocardium was assessed by RT-PCR, immunoblotting, and histology. Serum TNF-α, IL-1α, IL-1ß, IL-6, and IL-8 were measured. RESULTS: DM-Acu, but not DM-Sham, reduced fasting blood glucose without affecting body weight. DM decreased systolic function. DM-Acu, but not DM-Sham, attenuated the decrease in systolic function. Heart weight was significantly smaller in the DM-Acu than in the DM and DM-Sham groups. Percent fibrosis and apoptosis were reduced in the DM-Acu, but not the DM-Sham, group. Serum levels of IL-1α, IL-1ß, IL-6, IL-8, ICAM-1, MCP-1, and TNF-α were significantly lower in the DM-Acu than in the DM or DM-Sham groups. Protein levels of P-Akt and P-AMPK and mRNA levels of phosphoinositide-3-kinase regulatory subunit 6 (PIK3r6) were significantly higher in the DM-Acu group. Myocardial mRNA and protein levels of insulin-like growth factor 1 receptor (IGF1R) were significantly lower in the DM and DM-Sham groups compared with the DM-Acu group. CONCLUSIONS: EA reduced serum glucose; prevented DM-induced hypertrophy and deterioration of systolic function, inflammation, and fibrosis; and restored IGF1R, P-Akt, and P-AMPK levels in mice with type 2 diabetes mellitus.

Autophagy-dependent and -independent modulation of oxidative and organellar stress in the diabetic heart by glucose-lowering drugs.

Autophagy is a lysosome-dependent intracellular degradative pathway, which mediates the cellular adaptation to nutrient and oxygen depletion as well as to oxidative and endoplasmic reticulum stress. The molecular mechanisms that stimulate autophagy include the activation of energy deprivation sensors, sirtuin-1 (SIRT1) and adenosine monophosphate-activated protein kinase (AMPK). These enzymes not only promote organellar integrity directly, but they also enhance autophagic flux, which leads to the removal of dysfunctional mitochondria and peroxisomes. Type 2 diabetes is characterized by suppression of SIRT1 and AMPK signaling as well as an impairment of autophagy; these derangements contribute to an increase in oxidative stress and the development of cardiomyopathy. Antihyperglycemic drugs that signal through insulin may further suppress autophagy and worsen heart failure. In contrast, metformin and SGLT2 inhibitors activate SIRT1 and/or AMPK and promote autophagic flux to varying degrees in cardiomyocytes, which may explain their benefits in experimental cardiomyopathy. However, metformin and SGLT2 inhibitors differ meaningfully in the molecular mechanisms that underlie their effects on the heart. Whereas metformin primarily acts as an agonist of AMPK, SGLT2 inhibitors induce a fasting-like state that is accompanied by ketogenesis, a biomarker of enhanced SIRT1 signaling. Preferential SIRT1 activation may also explain the ability of SGLT2 inhibitors to stimulate erythropoiesis and reduce uric acid (a biomarker of oxidative stress)-effects that are not seen with metformin. Changes in both hematocrit and serum urate are the most important predictors of the ability of SGLT2 inhibitors to reduce the risk of cardiovascular death and hospitalization for heart failure in large-scale trials. Metformin and SGLT2 inhibitors may also differ in their ability to mitigate diabetes-related increases in intracellular sodium concentration and its adverse effects on mitochondrial functional integrity. Differences in the actions of SGLT2 inhibitors and metformin may reflect the distinctive molecular pathways that explain differences in the cardioprotective effects of these drugs.

Attenuation of diabetic cardiomyopathy by relying on kirenol to suppress inflammation in a diabetic rat model.

Diabetic cardiomyopathy is characterized by diabetes-induced myocardial abnormalities, accompanied by inflammatory response and alterations in inflammation-related signalling pathways. Kirenol, isolated from Herba Siegesbeckiae, has potent anti-inflammatory properties. In this study, we aimed to investigate the cardioprotective effect of kirenol against DCM and underlying the potential mechanisms in a type 2 diabetes mellitus model. Kirenol treatment significantly decreased high glucose-induced cardiofibroblasts proliferation and increased the cardiomyocytes viability, prevented the loss of mitochondrial membrane potential and further attenuated cardiomyocytes apoptosis, accompanied by a reduction in apoptosis-related protein expression. Kirenol gavage could affect the expression of pro-inflammatory cytokines in a dose-dependent manner but not lower lipid profiles, and only decrease fasting plasma glucose, fasting plasma insulin and mean HbA1c levels in high-dose kirenol-treated group at some time-points. Left ventricular dysfunction, hypertrophy, fibrosis and cell apoptosis, as structural and functional abnormalities, were ameliorated by kirenol administration. Moreover, in diabetic hearts, oral kirenol significantly attenuated activation of mitogen-activated protein kinase subfamily and nuclear translocation of NF-κB and Smad2/3 and decreased phosphorylation of IκBα and both fibrosis-related and apoptosis-related proteins. In an Electrophoretic mobility shift assay, the binding activities of NF-κB, Smad3/4, SP1 and AP-1 in the nucleus of diabetic myocardium were significantly down-regulated by kirenol treatment. Additionally, high dose significantly enhanced myocardial Akt phosphorylation without intraperitoneal injection of insulin. Kirenol may have potent cardioprotective effects on treating for the established diabetic cardiomyopathy, which involves the inhibition of inflammation and fibrosis-related signalling pathways and is independent of lowering hyperglycaemia, hyperinsulinemia and lipid profiles.

Effect of liraglutide on cardiac function in patients with type 2 diabetes mellitus: randomized placebo-controlled trial.

BACKGROUND: Liraglutide is an antidiabetic agent with cardioprotective effect. The purpose of this study is to test efficacy of liraglutide to improve diabetic cardiomyopathy in patients with diabetes mellitus type 2 (DM2) without cardiovascular disease. METHODS: Patients with DM2 were randomly assigned to receive liraglutide 1.8 mg/day or placebo in this double-blind trial of 26 weeks. Primary outcome measures were LV diastolic function (early (E) and late (A) transmitral peak flow rate, E/A ratio, early deceleration peak (Edec), early peak mitral annular septal tissue velocity (Ea) and estimated LV filling pressure (E/Ea), and systolic function (stroke volume, ejection fraction, cardiac output, cardiac index and peak ejection rate) assessed with CMR. Intention-to-treat analysis of between-group differences was performed using ANCOVA. Mean estimated treatment differences (95% confidence intervals) are reported. RESULTS: 23 patients were randomized to liraglutide and 26 to placebo. As compared with placebo, liraglutide significantly reduced E (- 56 mL/s (- 91 to - 21)), E/A ratio (- 0.17 (- 0.27 to - 0.06)), Edec (- 0.9 mL/s2 * 10-3 (- 1.3 to - 0.2)) and E/Ea (- 1.8 (- 3.0 to - 0.6)), without affecting A (3 mL/s (- 35 to 41)) and Ea (0.4 cm/s (- 0.9 to 1.4)). Liraglutide reduced stroke volume (- 9 mL (- 16 to - 2)) and ejection fraction (- 3% (- 6 to - 0.1)), but did not change cardiac output (- 0.4 L/min (- 0.9 to 0.2)), cardiac index (- 0.1 L/min/m2 (- 0.4 to 0.1)) and peak ejection rate (- 46 mL/s (- 95 to 3)). CONCLUSIONS: Liraglutide reduced early LV diastolic filling and LV filling pressure, thereby unloading the left ventricle. LV systolic function reduced and remained within normal range. Future studies are needed to investigate if liraglutide-induced left ventricular unloading slows progression of diabetic cardiomyopathy into symptomatic stages. Trial registration ClinicalTrials.gov: NCT01761318.

LncRNA TINCR is downregulated in diabetic cardiomyopathy and relates to cardiomyocyte apoptosis.

OBJECTIVE: LncRNA TINCR has been reported to be involved in cardiac hypertrophy, while its involvement in diabetic cardiomyopathy is unknown. MATERIALS AND METHODS: In this study, myocardial biopsy and serum collected from patients with diabetic cardiomyopathy, diabetic patients without cardiopathy and healthy controls, and the expression of TINCR in those tissues was detected by quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR). ROC curve analysis was performed to evaluate the diagnostic value of TINCR expression for diabetic cardiomyopathy. Human cardiomyocyte cells (Cat# 12440053, Thermo Fisher Scientific) were treated with high glucose, and the expression of TINCR was detected by qRT-PCR. TINCR expression was transfected into cardiomyocyte cells and cell apoptosis under high glucose treated was detected by cell apoptosis assay. RESULTS: We found that TINCR expression level in myocardial biopsy and serum was significantly lower in patients with diabetic cardiomyopathy than in diabetic patients without cardiopathy and healthy controls, while no significant differences were found between diabetic patients without cardiopathy and healthy controls. TINCR expression level can be used to effective diagnose diabetic cardiomyopathy. High glucose treatment showed no significant effects on the expression of TINCR in human cardiomyocyte cells, and TINCR overexpression inhibited apoptosis of cardiomyocytes under high glucose treatment. CONCLUSION: Therefore, we conclude that lncRNA TINCR is downregulated in diabetic cardiomyopathy and it can inhibit cardiomyocyte apoptosis.

Sitagliptin attenuates myocardial apoptosis via activating LKB-1/AMPK/Akt pathway and suppressing the activity of GSK-3ß and p38α/MAPK in a rat model of diabetic cardiomyopathy.

The present study aimed to investigate the protective effect of sitagliptin, a dipeptidyl peptidase-4 inhibitor, on diabetic cardiomyopathy (DCM)-associated apoptosis and if this effect is mediated via modulating the activity of the survival kinases; AMP-activated protein kinase (AMPK) and Akt & the apoptotic kinases; glycogen synthase kinase-3 ß (GSK-3ß) and p38 mitogen-activated protein kinase (p38MAPK). Diabetes was induced by a single intraperitoneal injection of streptozotocin (55 mg/kg). Diabetic rats were treated with sitagliptin (10 mg/kg/day, p.o.) and metformin (200 mg/kg/day, p.o. as positive control) for six weeks. Chronic hyperglycemia resulted in elevation of serum cardiac biomarkers reflecting cardiac damage which was supported by H&E stain. The mRNA levels of collagen types I and III were augmented reflecting cardiac fibrosis and hypertrophy which was supported by Masson trichome stain and enhanced phosphorylation of p38MAPK. Cardiac protein levels of cleaved casapse-3, BAX were elevated, whereas, the levels of Bcl-2 and p-BAD were reduced indicating cardiac apoptosis which could be attributed to the diabetes-induced reduced phosphorylation of Akt and AMPK with concomitant augmented activation of GSK-3ß and p38MAPK. Protein levels of liver kinase B-1, the upstream kinase of AMPK were also supressed. Sitagliptin administration alleviated the decreased phosphorylation of AMPK and Akt, inactivated the GSK-3ß and p38 AMPK, therefore, attenuating the apoptosis and hypertrophy induced by hyperglycemia in the diabetic heart. In conclusion, sitagliptin exhibits valuable therapeutic potential in the management of DCM by attenuating apoptosis. The underlying mechanism may involve the modulating activity of AMPK, Akt, GSK-3ß and p38MAPK.

High Fat Diet Upregulates Fatty Acid Oxidation and Ketogenesis via Intervention of PPAR-γ.

BACKGROUND/AIMS: Systemic hyperlipidemia and intracellular lipid accumulation induced by chronic high fat diet (HFD) leads to enhanced fatty acid oxidation (FAO) and ketogenesis. The present study was aimed to determine whether activation of peroxisome proliferator-activated receptor-γ (PPAR-γ) by surplus free fatty acids (FA) in hyperlipidemic condition, has a positive feedback regulation over FAO and ketogenic enzymes controlling lipotoxicity and cardiac apoptosis. METHODS: 8 weeks old C57BL/6 wild type (WT) or PPAR-γ-/- mice were challenged with 16 weeks 60% HFD to induce obesity mediated type 2 diabetes mellitus (T2DM) and diabetic cardiomyopathy. Treatment course was followed by echocardiographic measurements, glycemic and lipid profiling, immunoblot, qPCR and immunohistochemistry (IHC) analysis of PPAR-γ and following mitochondrial metabolic enzymes 3-hydroxy-3-methylglutaryl-CoA synthase (HMGCS2), mitochondrial ß- hydroxy butyrate dehydrogenase (BDH1) and pyruvate dehydrogenase kinase isoform 4 (PDK4). In vivo model was translated in vitro, with neonatal rat cardiomyocytes (NRCM) treated with PPAR-γ agonist/antagonist and PPAR-γ overexpression adenovirus in presence of palmitic acid (PA). Apoptosis was determined in vivo from left ventricular heart by TUNEL assay and immunoblot analysis. RESULTS: We found exaggerated circulating ketone bodies production and expressions of the related mitochondrial enzymes HMGCS2, BDH1 and PDK4 in HFD-induced diabetic hearts and in PA-treated NRCM. As a mechanistic approach we found HFD mediated activation of PPAR-γ is associated with the above-mentioned mitochondrial enzymes. HFD-fed PPAR-γ-/-mice display decreased hyperglycemia, hyperlipidemia associated with increased insulin responsiveness as compared to HFD-fed WT mice PPAR-γ-/-HFD mice demonstrated a more robust functional recovery after diabetes induction, as well as significantly reduced myocyte apoptosis and improved cardiac function. CONCLUSIONS: PPAR-γ has been described previously to regulate lipid metabolism and adipogenesis. The present study suggests for the first time that increased PPAR-γ expression by HFD is responsible for cardiac dysfunction via upregulation of mitochondrial enzymes HMGCS2, BDH1 and PDK4. Targeting PPAR-γ and its downstream mitochondrial enzymes will provide novel strategies in preventing metabolic and myocardial dysfunction in diabetes mellitus.

Cardiac effects of fish oil in a rat model of streptozotocin-induced diabetes.

BACKGROUND AND AIMS: Fish oil (FO) is rich in omega-3 polyunsaturated fatty acids, which have cardio-protective effects. This study aims to evaluate effects of FO in a rat model of streptozotocin (STZ) induced diabetes. METHODS AND RESULTS: Adults male Wistar rats were assigned to control (4 µl corn oil/g corn oil given by oral gavage), FO (4 µl Menhaden FO/g body weight given by oral gavage), diabetes (DM, 35 mg/kg STZ single intraperitoneal injection, corn oil), and DM + FO groups for 8 weeks. Plasma and cardiac biomarkers of oxidative stress, inflammation, and fibrosis were evaluated. STZ-induced diabetes as indicated by the significant increase in serum levels of glucose and percentage of glycated hemoglobins. FO reduced plasma arachidonic acid (AA) percentage and ratio of AA: docosahexaenoic acid (DHA). Plasma and cardiac levels of total nitrite, endothelin -1 (ET-1), and myeloperoxidase (MPO) increased in the DM group, whereas cardiac activities of catalase and superoxide dismutase (SOD) decreased. FO reduced cardiac nitrite and MPO, and plasma ET-1 levels. FO increased cardiac glutathione, catalase and SOD activities. Levels of thiobarbituric acid substances increased in the FO and DM groups with significant synergism in the DM + FO group. FO prevented cardiac fibrosis associated with DM and decreased cardiac transforming growth factor beta-1and p38 MAP kinases. Cardiac levels of matrix metalloproteinase -2 were significantly elevated in FO and DM + FO groups. CONCLUSIONS: FO decreased plasma and cardiac oxidative stress, inflammation and myocardial fibrosis. FO could be used in diabetes to reduce risk and burden of CVDs.

Prophylactic mechanisms of Cucumis melo var. flexuosus and Phoenix dactylifera fruit extracts against diabetic cardiomyopathy in streptozotocin induced diabetic rats.

The aim of this investigation was to study the antidiabetic impact of Cucumis melo var. flexuosus and/or Phoenix dactylifera fruit aqueous extracts and their mechanisms in repressing diabetes induced cardio-myopathy in diabetic rats. Type 2 diabetes was promoted in rats by a single intraperitoneal injection of streptozotocin (30mg/kg body wight). C. flexuosus and P. dactylifera extracts (200mg/kg body weight, each) were ingested to diabetic rats daily for a month. The results showed that ingestion of either plant extract or their combination to diabetic rats significantly diminished the glucose level and boosted the insulin concentration in the blood. The plant extracts markedly ameliorated the serum inflammatory molecules, tumor necrosis factor (TNF-α) and C -reactive protein (CRP), as well as the alteration in the cardiac malondialdehyde (MDA) and glutathione peroxidase (GPx). The extracts attenuated the increase in cardiac apoptosis enzyme (caspase -3) and the oxidative DNA fragmentation. Treating diabetic rats with plant extracts also scaled down the serum cardiac function enzyme, creatine phosphokinase-MB (CPK-MB). The biochemical results were confirmed by histopathological examination. This study has proven that both the plant extracts particularly their combination have potential hypoglycemic effect and could attenuate cardiomyopathy in diabetic rats.

Mitochondrial Dysfunction in Diabetic Cardiomyopathy: Effect of Mesenchymal Stem Cell with PPAR-γ Agonist or Exendin-4.

Therapy targeting mitochondria may provide novel ways to treat diabetes and its complications. Bone marrow-derived mesenchymal stem cells (MSCs), the peroxisome proliferator-activated receptor gamma (PPAR-γ) agonists and exendin-4; an analog of glucagon-like peptide-1 have shown cardioprotective properties in many cardiac injury models. So, we evaluated their effects in diabetic cardiomyopathy (DCM) in relation to mitochondrial dysfunction. This work included seven groups of adult male albino rats: the control group, the non-treated diabetic group, and the treated diabetic groups: one group was treated with MSCs only, the second with pioglitazone only, the third with MSCs and pioglitazone, the forth with exendin-4 only and the fifth with MSCs and exendin-4. All treatments were started after 6 weeks from induction of diabetes and continued for the next 4 weeks. Blood samples were collected for assessment of glucose, insulin, and cardiac enzymes. Hearts were removed and used for isolated heart studies, and gene expression of: myocyte enhancer factor-2 (Mef2), peroxisome proliferator-activated receptor gamma coactivator1-alpha (PGC1α), nuclear factor kappa B (NFKB) and autophagic markers: light chain 3 (LC3) and beclin by real-time reverse transcription-polymerase chain reaction. The cardiac mitochondrial protein levels of cardiolipin and uncoupler protein 2 (UCP2) were assessed by ELISA and western blot technique, respectively. Treated groups showed significant improvement in left ventricular function associated with improvement in the cardiac injury and myopathic markers compared to the non treated diabetic group. NFKB was down-regulated while cardiolipin, PGC1α, LC.3 and beclin were up-regulated in all treated groups. These data suggest that the cardioprotective effects of MSCs, exendin-4 or pioglitazone based on their ability to improve mitochondrial functions through targeting inflammatory and autophagy signaling. The co- administration of pioglitazone or exendin-4 with MSCs showed significant superior improvement compared with MSCs alone, indicating the ability to use them in supporting cardioprotective effects of MSCs.