Regulation Of Insulin Resistance Research Articles

Bone Marrow Mesenchymal Stem Cells-Derived Exosomal MiR-29b-3p Regulates Aging-Associated Insulin Resistance.

Insulin resistance is the major pathological characteristic of type 2 diabetes, and the elderly often develop insulin resistance. However, the deep-seated mechanisms for aging-related insulin resistance remain unclear. Here, we showed that nanosized exosomes released by bone marrow mesenchymal stem cells (BM-MSCs) of aged mice could be taken up by adipocytes, myocytes, and hepatocytes, resulting in insulin resistance both in vivo and in vitro. Using microRNA (miRNA) array assays, we found that the amount of miR-29b-3p was dramatically increased in exosomes released by BM-MSCs of aged mice. Mechanistically, SIRT1 (sirtuin 1) was identified to function as the downstream target of exosomal miR-29b-3p in regulating insulin resistance. Notably, utilizing an aptamer-mediated nanocomplex delivery system that down-regulated the level of miR-29b-3p in BM-MSCs-derived exosomes significantly ameliorated the insulin resistance of aged mice. Meanwhile, BM-MSCs-specific overexpression of miR-29b-3p induced insulin resistance in young mice. Taken together, these findings suggested that BM-MSCs-derived exosomal miR-29b-3p could modulate aging-related insulin resistance, which may serve as a potential therapeutic target for aging-associated insulin resistance.

Asymmetric dimethylarginine targets MAPK pathway to regulate insulin resistance in liver by activating inflammation factors.

Insulin resistance is associated with impaired glucose uptake and altered protein kinase B (Akt) signaling. Previous studies have suggested asymmetric dimethylarginine (ADMA) and inflammation are two distinguish factors that correlate with insulin resistance (IR). How ADMA and inflammation factors interact and synchronize in the regulation of IR in liver remain to be elucidated. In this study, we systematically investigated whether ADMA is involved in IR using primary hepatocytes, if yes, by via which molecular mechanism. Our results demonstrated that ADMA inhibits insulin sensitivity in a concentration-dependent manner by activating inflammation factors tumor necrosis factor (TNF)-α, interleukin (IL)-1, and IL-6 in primary hepatocytes. Further analysis revealed that mitogen-activated protein kinase (MAPK) signaling pathway act downstream of ADMA and inflammation factors, and inhibition of MAPK pathway rescued the IR. Furthermore, metformin effects has been found which could reverse ADMA-induced IR by suppressing MAPK signaling pathway. To our knowledge, we, for the first time, unveiled the complicated regulatory network and interactions among ADMA, inflammation, and MAPK signaling pathway, which advanced current research on the development and regulation of IR in liver. This study also certainly provided novel insights on comprehensive diagonistics roles of ADMA as a potential biomarker.

Dioscin attenuates high‑fat diet‑induced insulin resistance of adipose tissue through the IRS‑1/PI3K/Akt signaling pathway.

Insulin resistance, as a common metabolic disorder, may be caused by diet‑induced obesity. The aim of the present study is to investigate the effects of dioscin on regulating insulin resistance of adipose tissue induced by a high‑fat diet (HFD). An animal model was established successfully using C57BL/6J mice with high‑fat feeding, followed by treatment with 5, 10 and 20mg/kg dioscin through gavage for 18weeks, and randomly divided into a control group, a HFD model group and a dioscin group treated with 5, 10 and 20mg/kg/day dioscin for 12weeks. Histopathological changes in adipose tissues were examined using hematoxylin and eosin staining. Biochemical parameters of the serum were also monitored, including glucose, insulin, total triglyceride, homeostasis model assessment of insulin resistance (HOMA‑IR) and adipose insulin resistance (Adipo‑IR) levels. Expression of the mRNA and associated proteins of the insulin receptor substrate 1 (IRS‑1)/phosphoinositide 3‑kinase (PI3K)/protein kinase B (Akt) pathways were determined using reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) and western blot analysis, respectively. HOMA‑IR and Adipo‑IR values of mice fed with a HFD were significantly higher compared with those in the control group (P<0.01). However, dioscin administration significantly decreased HOMA‑IR and Adipo‑IR values in a dose‑dependent manner (P<0.05), suggesting the effects of dioscin on attenuating insulin resistance. RT‑qPCR results indicated that the associated genes of the IRS‑1/PI3K/Akt pathway were significantly downregulated by HFD compared with the control group (P<0.05), while dioscin significantly increased the expression of those genes compared with the control group (P<0.05). Similarly, the significant increase in phosphorylated (p‑)IRS‑1/IRS‑1 (P<0.05) and p‑Akt/Akt (P<0.05) values were substantially reversed by dioscin treatment. Dioscin pronouncedly mitigated insulin resistance in adipose tissues through the IRS‑1/PI3K/Akt pathway and has potential to be used as a novel therapeutic agent for the therapy of HFD‑induced insulin resistance in adipose tissue.

Emodin improves glucose metabolism by targeting microRNA-20b in insulin-resistant skeletal muscle

BackgroundEmerging evidence has indicated the therapeutic potential of emodin with its multiple pharmacological effects. PurposeTo evaluate role of emodin in regulating insulin resistance (IR) and to elucidate the underlying molecular mechanisms. Study design/MethodsFasting blood glucose (FBG) and lipid levels were measured before and after intragastric administration of emodin in type 2 diabetes mellitus (T2DM) rats. Glucose consumption was determined in L6 cells to investigate the effect of emodin on glucose metabolism. Expression of miR-20b and SMAD7 was quantified by real-time PCR for mRNAs or western blot analysis for proteins. ResultsEmodin ameliorated hyperglycemia and dyslipidemia in T2DM rats, and glucose metabolism in a concentration- and time-dependent manner. MiR-20b was markedly upregulated in the setting of IR and overexpression of miR-20b disrupted glucose metabolism by repressing SMAD7 in L6 cells. Knockdown of this miRNA produced the opposite effects. Emodin abolished the abnormal upregulation of miR-20b and indirectly upregulated SMAD7. ConclusionEmodin improves glucose metabolism to produce anti-IR effects, and downregulation of miR-20b thereby upregulation of SMAD7 is an underlying mechanism for the beneficial effects of emodin.

Gut Microbiome in Obesity, Metabolic Syndrome, and Diabetes.

Obesity and diabetes are worldwide epidemics. There is also a growing body of evidence relating the gut microbiome composition to insulin resistance. The purpose of this review is to delineate the studies linking gut microbiota to obesity, metabolic syndrome, and diabetes. Animal studies as well as proof of concept studies using fecal transplantation demonstrate the pivotal role of the gut microbiota in regulating insulin resistance states and inflammation. While we still need to standardize methodologies to study the microbiome, there is an abundance of evidence pointing to the link between gut microbiome, inflammation, and insulin resistance, and future studies should be aimed at identifying unifying mechanisms.

PO-029 Advances in research on hypoxia-mediated miRNAs affecting glucose metabolism

Objective This article reviews the role of miRNAs in promoting insulin sensitivity, controlling insulin synthesis, and regulating insulin resistance in hypoxia exercise, and discusses the relationship between miRNAs and glucose metabolism, and the mechanism of hypoxia-induced regulation of miRNAs in glucose metabolism. It provides a theoretical basis for better research on the prevention and treatment of disorders of glucose metabolism.&#x0D; Methods This paper uses the literature data method, collects a large number of documents and cites more than 90 articles for comprehensive statistical analysis to write this article, which provides researchers with relevant research directions.&#x0D; Results Studies have shown that miRNAs such as miR-138, miR-26b, miR-27a, miR-122, miR-802 and miR-143 have regulatory effects on obesity; some miRNAs such as miR-128, miR-7, miR-25, miR -92a, miR-375 and miR-15 family (miR-15a and miR-15b) and other miRNAs play an important role in regulating glycolipid metabolism, thereby maintaining a stable state of glycolipid metabolism. Expressions such as miR-802 and miR-143 are up-regulated in the liver of obese patients, resulting in impaired glucose tolerance.&#x0D; Conclusions By regulating the expression of target genes and maintaining the homeostasis of glucose metabolism, miRNAs can effectively improve or prevent obesity and disorders of glucose metabolism such as type 2 diabetes. Current studies have shown that miRNAs affect glucose metabolism from insulin sensitivity, insulin synthesis and insulin resistance. At the same time, studies have shown that exercise intervention can effectively improve glucose metabolism. However, the research on the metabolism of miRNAs in glucose metabolism during hypoxia is still insufficient. It is for further study. Studying the mechanism of the effects of miRNAs on glucose metabolism in hypoxic exercise can not only provide a theoretical basis for scientific hypoglycemic and weight control, but also can be used as an intervention for the prevention and control of diseases related to glucose metabolism disorders. In the future, drugs can regulate the expression of miRNAs, thereby providing a new therapeutic approach for the treatment of diseases caused by abnormal glucose and lipid metabolism.

The Causal Role of Mitochondrial Dynamics in Regulating Insulin Resistance in Diabetes: Link through Mitochondrial Reactive Oxygen Species.

Background Mitochondrial dynamics (mtDYN) has been proposed as a bridge between mitochondrial dysfunction and insulin resistance (IR), which is involved in the pathogenesis of type 2 diabetes (T2D). Our previous study has identified that mitochondrial DNA (mtDNA) haplogroup B4 is a T2D-susceptible genotype. Using transmitochondrial cybrid model, we have confirmed that haplogroup B4 contributes to cellular IR as well as a profission mtDYN, which can be reversed by antioxidant treatment. However, the causal relationship between mtDYN and cellular IR pertaining to T2D-susceptible haplogroup B4 remains unanswered. Methods To dissect the mechanisms between mtDYN and IR, knockdown or overexpression of MFN1, MFN2, DRP1, and FIS1 was performed using cybrid B4. We then examined the mitochondrial network and mitochondrial oxidative stress (mtROS) as well as insulin signaling IRS-AKT pathway and glucose transporters (GLUT) translocation to plasma membrane stimulated by insulin. We employed Drp1 inhibitor, mdivi-1, to interfere with endogenous expression of fission to validate the pharmacological effects on IR. Results Overexpression of MFN1 or MFN2 increased mitochondrial network and reduced mtROS, while knockdown had an opposing effect. In contrast, overexpression of DRP1 or FIS1 decreased mitochondrial network and increased mtROS, while knockdown had an opposing effect. Concomitant with the enhanced mitochondrial network, activation of the IRS1-AKT pathway and GLUT translocation stimulated by insulin were improved. On the contrary, suppression of mitochondrial network caused a reduction of the IRS1-AKT pathway and GLUT translocation stimulated by insulin. Pharmacologically inhibiting mitochondrial fission by the Drp1 inhibitor, mdivi-1, also rescued mitochondrial network, reduced mtROS, and improved insulin signaling of diabetes-susceptible cybrid cells. Conclusion Our results discovered the causal role of mtDYN proteins in regulating IR resulted from diabetes-susceptible mitochondrial haplogroup. The existence of a bidirectional interaction between mtDYN and mtROS plays an important role. Direct intervention to reverse profission in mtDYN provides a novel therapeutic strategy for IR and T2D.

Association between resistin and fibroblast growth factor 23 in patients with type 2 diabetes mellitus

Fibroblast growth factor 23 (FGF23) is associated with cardiovascular disease and all-cause mortality in patients with diabetes mellitus. Insulin resistance has recently been reported to increase FGF23 levels, and resistin is a peptide that mainly regulates insulin resistance. However, few studies have investigated the association between FGF23 and resistin. A total of 422 patients with diabetes mellitus were recruited for this cross-sectional study to examine the association between resistin and intact FGF23. The mean ( ± standard deviation) age was 63.1 ± 11.9 years, and the median HbA1c was 6.7% (range, 6.1–7.1%). The mean estimated glomerular filtration rate (eGFR) was 66.2 ± 23.1 mL/min/m2. Multiple regression analysis for resistin showed that logFGF23 (coefficient (Coef): 1.551; standard error (SE): 0.739; P = 0.036), C-peptide (Coef: 0.798; SE: 0.229; P = 0.001), ghrelin (Coef: 1.061; SE: 0.332; P = 0.001), intact parathyroid hormone (Coef: 0.022; SE: 0.099; P = 0.030), and eGFR (Coef: −0.091; SE: 0.017; P < 0.001) were all significantly associated with the resistin level. These associations were modified in patients with higher age, lower body mass index, and higher vitamin D levels. These results suggest that resistin is positively associated with serum FGF23 levels.

Serum miR-29a and miR-122 as Potential Biomarkers for Non-Alcoholic Fatty Liver Disease (NAFLD).

Non-Alcoholic Fatty Liver Disease (NAFLD) is an over accumulation of triglyceride in the liver without alcohol consumption. Its major cause is insulin resistance. Patients with NAFLD can develop liver fibrosis, cirrhosis and hepatocellular carcinoma (HCC). MicroRNAs (miRNAs) are non-coding RNAs that regulate post-transcriptional gene silencing. Previous research reported that miR-29 family (a, b and c) and miR-122 have an important role in regulating insulin resistance related to NAFLD. The purpose of this study was to investigate that miR-29 and miR-122 can be possible biomarkers for non-invasive diagnosis of NAFLD. Serum samples were collected from 58 NAFLD patients and 34 healthy controls. MiRNAs were extracted from serum by using microRNA purification kit followed by polyuridylation, reverse transcription and quantitative real-time PCR. Also, we analyzed the correlation between miR-29 and miR-122 and level of liver inflammation in NAFLD patients. We found that the serum miR-29a levels in NAFLD patients were significantly lower (P = 0.006) than the control group, while miR-29c levels were unchanged, and miR-29b levels were undetectable. However, we found that serum miR-122 levels in NAFLD patients were significantly higher (P < 0.001) than those found in the control group. For miR-29a, the area under curve (AUC) was 0.679 (P = 0.0065) with 60.87% sensitivity and 82.35% specificity. For miR-122, the AUC was 0.831 (P < 0.0001) with 75.00% sensitivity and 82.35% specificity. Interestingly, the levels of serum miR- 122 were significantly different between patients without steatohepatitis (NAS < 4) and steatohepatitis (NAS ≥ 4), indicating that the levels of miR-122 were related to the severity of NAFLD. The levels of miR-29a and miR-122 might be beneficial and compelling as possible biomarkers for non-invasive diagnosis of NAFLD.

Acid Sphingomyelinase Down-regulation Alleviates Vascular Endothelial Insulin Resistance in Diabetic Rats.

Insulin resistance in endothelial cells contributes to the development of cardiovascular disease in patients with type 2 diabetes. Acid sphingomyelinase (ASM) is a soluble glycoprotein which plays a vital role in the development and progression of various diseases such as cardiovascular and metabolic diseases. However, it remains unknown if ASM regulates insulin resistance in vascular endothelial cells in type 2 diabetes. ASM down-regulation with gene silencing and selective inhibitor amitriptyline was used in the rat aortic endothelial cells (RAECs) treated with palmitic acid (PA), a common saturated free fatty acid, which is thought to be the major cause of insulin resistance. It was shown that ASM down-regulation increased glucose uptake and glucose transporter-4 (Glut4) expression and reversed the phosphorylation of pIRS-1-ser307 and AKT-ser473 via ceramide, consequently resulting in the decrease of the production of endothelial nitric oxide synthase (eNOS) and nitric oxide in PA-induced RAECs. We further found that ASM down-regulation blocked the Nox2- and Nox4-dependent superoxide (O2 -· ) generation, which regulated glucose metabolism in RAECs during PA stimulation. In vivo, amitriptyline relieved the vasodilatory response to acetylcholine and restored the level of ceramide, Nox2 and Nox4 in the aorta endothelium of high-fat diet-fed rats following an injection of streptozotocin. Taken together, these results suggest that ASM down-regulation can improve endothelial insulin resistance which is attributed to inhibiting redox signalling in RAECs. Thus, these data support the idea that ASM is a promising clinical biomarker and potential therapeutic target for diabetic vascular complication.

Sex-Specific Role of Adipose-Derived Lipocalin-2 in Diet-Induced Obesity and Insulin Resistance

Lipocalin-2 (LCN2) is a 25-kDa secretory adipokine that is up regulated in adipose tissues of genetically obese animals and humans. LCN2 was also proposed to regulate insulin resistance (IR) in animal studies. Besides, we have shown adipose Lcn2 expression to be negatively regulated by estradiol using a mouse reference population of over ∼100 strains, the Hybrid Mouse Diversity Panel (HMDP). Recently, LCN2 has also been implicated in recruiting neutrophils to the liver in both alcoholic and nonalcoholic steatohepatitis. To further explore the causal role of LCN2 in diet-induced obesity and its metabolic complications, we carried out systems genetics analyses on multi-omics data collected from both males and females of HMDP fed a high fat/high sucrose (HF/HS) diet: Genotypes, 200,000 high-resolution SNPs; Phenotypes, obesity (fat mass, and weight of three visceral adipose depots), IR (fasting levels of glucose, insulin and HOMA-IR) and steatosis (liver triglyceride levels); and Transcriptomics, mRNA microarrays of adipose and liver tissues. Our analyses revealed female, but not male, adipose-derived LCN2 is mechanistically linked to deregulated adiposity and enhanced insulin resistance. To functionally validate the causal role of female adipose LCN2, we conditionally overexpressed either LCN2 or GFP in adipose tissues of mice of both sexes by adeno-associated viral vectors and subjected them to HF/HS diet. We demonstrated deregulated metabolic homeostasis: increased adiposity (fat mass), glucose intolerance (GTT) and insulin resistance (ITT and HOMA-IR) only in females. Follow-up ex vivo bioenergetics studies in both adipose and liver tissues demonstrated deregulated mitochondrial respiration (lowered in adipose; enhanced in liver) mediated by LCN2 overexpression only in females, thereby revealing mitochondrial dysfunction as one of the key mechanism(s) mediated by LCN2 in diet-induced obesity and its complications. Disclosure K. Chella Krishnan: None. S. Sabir: None. R. Floyd: None. D. Jayasekera: None. A. Lusis: None.

MRNA for Selenoprotein P, a Hepatokine, Binds RIG-I Protein and Inhibits the RIG-I-Mediated Type I Interferon Response

The liver is a multifunctional organ with roles in metabolism, detoxification, and the immune response. Liver secretory selenoprotein P (SeP), a hepatokine, causes insulin resistance in the liver and peripheral muscle. We showed hepatitis C virus (HCV) infection increased serum SeP levels, which may explain the increased risk of type 2 diabetes in patients with HCV infection. Increased SeP mRNA (SEPP1 mRNA) in hepatocytes inhibited type 1 interferon response by means of undefined unique mechanisms. We revealed SEPP1 mRNA directly bound to retinoic acidinducible gene I (RIG-I), a virus RNA sensor, and inhibited RIG-I activity. The robust induction of interferon-stimulated genes (>1000-fold) and repression of HCV replication (>10-fold) were observed in hepatocytes in which SEPP1 mRNA was knocked down. Clinically, high SeP serum levels were significantly associated with treatment failure of direct actingantivirals for HCV. Thus, SeP regulates insulin resistance and innate immunity, possibly inducing immune tolerance in the liver.

Adipocyte-Derived Exosomal MiR-27a Induces Insulin Resistance in Skeletal Muscle Through Repression of PPARγ.

The mechanism by which adipocyte-derived endocrine factors promote insulin resistance in skeletal muscle are not fully understood. MiR-27a is highly expressed in sera of obese individuals with prediabetes and T2DM, and mainly derived by adipose tissues. Thus, miR-27a secreted into circulation by adipose tissue may regulate insulin resistance in skeletal muscle.Methods: The association between miR-27a and insulin resistance in skeletal muscle was determined in obese children, high-fat diet-induced miR-27a knockdown obese mice, db/db mice and C2C12 cells overexpressing miR-27a. The crosstalk mediated by exosomal miR-27a between adipose tissue and skeletal muscle was determined in C2C12 cells incubated with conditioned medium prepared from palmitate-treated 3T3-L1 adipocytes.Results: We showed that serum miR-27a level correlated positively with obesity and insulin resistance in obese children, and that elevated serum miR-27a levels correlated with insulin resistance in leptin receptor-deficient db/db mice, and with obesity and insulin resistance in high-fat diet-fed C57BL/6J mice. MiR-27a released from adipocytes of high-fat diet-fed C57BL/6J mice was associated with triglyceride accumulation. MiR-27a derived from these adipocytes induced insulin resistance in C2C12 skeletal muscle cells through miR-27a-mediated repression of PPARγ and its downstream genes involved in the development of obesity.Conclusions: These results identify a novel crosstalk signaling pathway between adipose tissue and skeletal muscle in the development of insulin resistance, and indicate that adipose tissue-derived miR-27a may play a key role in the development of obesity-triggered insulin resistance in skeletal muscle.

Angiopoietin-like protein 8: An attractive biomarker for the evaluation of subjects with insulin resistance and related disorders.

Insulin resistance is prevalent worldwide and is associated with many metabolic diseases, in particular, type 2 diabetes mellitus (T2DM), obesity, nonalcoholic fatty liver disease (NAFLD), polycystic ovary syndrome (PCOS) and metabolic syndrome (MetS). Angiopoietin-like protein 8 (ANGPTL8), a newly-identified secreted protein composing of 198 amino acids, is enriched in the liver of human. Considering its promising potential for β-cell proliferation and therapeutic prospect for diabetes, ANGPTL8 has aroused extensive interests. However, a recent collaborative study confirmed that ANGPTL8 didn't stimulate dramatic β-cell regeneration. At present, a controversial scientific discussion on whether and how ANGPTL8 regulate insulin resistance has been ongoing. Interestingly, several in vitro and in vivo studies have suggested the complex roles of ANGPTL8 in insulin resistance. Data resulting from cross-sectional and longitudinal researches in human individuals involving the influence of ANGPTL8 on the development of insulin resistance were controversial. We therefore summarize currently clinical literature to exploit whether this exciting hormone could be applied for clinical application asa potential clinical biomarker to predict insulin resistance and related disorders.

Serum fatty acid-binding protein 4 (FABP4) concentration is associated with insulin resistance in peripheral tissues, A clinical study.

Type 2 diabetes mellitus (T2DM) is caused by insulin resistance and β cell dysfunction. In recent studies reported that several markers associated with insulin sensitivity in skeletal muscle, Adiponectin and other parameters, such as fatty acid-binding protein (FABP4), have been reported to regulate insulin resistance, but it remains unclear which factor mostly affects insulin resistance in T2DM. In this cross-sectional study, we evaluated the relationships between several kinds of biomarkers and insulin resistance, and insulin secretion in T2DM and healthy controls. We recruited 30 participants (12 T2DM and 18 non-diabetic healthy controls). Participants underwent a meal tolerance test during which plasma glucose, insulin and serum C-peptide immunoreactivity were measured. We performed a hyperinsulinemic-euglycemic clamp and measured the glucose-disposal rate (GDR). The fasting serum levels of adiponectin, insulin-like growth factor-1, irisin, autotaxin, FABP4 and interleukin-6 were measured by ELISA. We found a strong negative correlation between FABP4 concentration and GDR in T2DM (r = -0.657, p = 0.020). FABP4 also was positively correlated with insulin secretion during the meal tolerance test in T2DM (IRI (120): r = 0.604, p = 0.038) and was positively related to the insulinogenic index in non-DM subjects (r = 0.536, p = 0.022). Autotaxin was also related to GDR. However, there was no relationship with insulin secretion. We found that serum FABP4 concentration were associated with insulin resistance and secretion in T2DM. This suggests that FABP4 may play an important role in glucose homeostasis.

Resistive Training and Molecular Regulators of Vascular-Metabolic Risk in Chronic Stroke

Peroxisome proliferator-activated receptor (PPAR)-γ coactivator (PGC-1α) gene and Sirtuin-1 (SIRT-1) respond to physiological stimuli and regulate insulin resistance. Inflammatory markers tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), C-reactive protein (CRP), and the soluble forms of intracellular adhesion molecule (sICAM-1) and vascular CAM-1 (sVCAM-1) are associated with increased risk of diabetes and coronary heart disease. Resistive training (RT) reduces hyperinsulinemia and improves insulin action in chronic stroke. Yet, the molecular mechanisms for this are unknown. This study will determine the effects of RT on skeletal muscle PGC-1α and SIRT-1 mRNA expression and inflammatory and vascular markers. Stroke survivors (50-76 years) underwent a fasting blood draw for measurement of TNF-α, IL-6, CRP, serum amyloid A, sICAM-1, sVCAM-1, and bilateral vastus lateralis biopsies before and after RT. Participants were also assessed using bilateral multislice thigh computed tomography scans from the knee to the hip, a total body scan by dual-energy X-ray absorptiometry, and 1-repetition maximum strength testing. Subjects performed 2 sets of 3 lower extremity RT exercises 3 times per week for 12 weeks. Bilateral leg press and leg extension strength increased ~30-50% with RT (P < .001). Body weight, total body fat mass, and fat-free mass did not change. Thigh muscle area and volume increased in both legs (P < .05). Nonparetic muscle PGC-1α mRNA expression increased 14% (P < .05) after RT and SIRT-1 mRNA decreased 24% (P < .05) and 31% (P < .01) in paretic and nonparetic muscles. There were no significant changes in plasma inflammation with training. RT in chronic stroke induces changes in key skeletal muscle regulators of metabolism, without effecting circulating inflammation.

A variation in KCNQ1 gene is associated with repaglinide efficacy on insulin resistance in Chinese Type 2 Diabetes Mellitus Patients.

Repaglinide is an insulin secretagogue that often exhibits considerable interindividual variability in therapeutic efficacy. The current study was designed to investigate the impact of KCNQ1 genetic polymorphism on the efficacy of repaglinide and furthermore to identify the potential mechanism of action in patients with type 2 diabetes. A total of 305 patients and 200 healthy subjects were genotyped for the KCNQ1 rs2237892 polymorphism, and 82 patients with T2DM were randomized for the oral administration of repaglinide for 8 weeks. HepG2 cells were incubated with repaglinide in the absence or presence of a KCNQ1 inhibitor or the pcDNA3.1-hKCNQ1 plasmid, after which the levels of Akt, IRS-2 and PI(3)K were determined. Our data showed that repaglinide significantly decreased HOMA-IR in patients with T2DM. Furthermore, the level of HOMA-IR was significantly reduced in those patients with CT or TT genotypes than CC homozygotes. The KCNQ1 inhibitor enhanced repaglinide efficacy on insulin resistance, with IRS-2/PI(3)K/Akt signaling being up-regulated markedly. As in our clinical experiment, these data strongly suggest that KCNQ1 genetic polymorphism influences repaglinide response due to the pivotal role of KCNQ1 in regulating insulin resistance through the IRS-2/PI(3)K/Akt signaling pathway. This study was registered in the Chinese Clinical Trial Register on May 14, 2013. (No. ChiCTR-CCC13003536).

Abstract P340: Molecular Mechanisms of Fetuin-a-induced Vascular Dysfunction and Inflammation: Role of Oxidative Stress and Toll-like Receptor 4

Fetuin-A (FetA) is an endogenous agonist to toll-like receptor 4 (TLR4) and regulates insulin resistance and inflammation. FetA has been associated with endothelial dysfunction during metabolic diseases. Exact mechanisms whereby FetA influences vascular function in pathological conditions remain unknown, but we demonstrated that FetA regulates vascular function by Nox1 and TLR4 activation. Here we hypothesized that FetA, through changes in cell metabolism and activation of TLR4-Nox1 axis induces ROS formation and inflammation in hypertension. Normotensive (WKY) and hypertensive (SHRSP) vascular cells, as well as human microvascular endothelial cells, were stimulated with FetA (50 ng/mL). ROS production was measured by lucigenin and Amplex red, while gene expression was assessed by qPCR. FetA increased ROS production (131±49.2%), decreased H 2 O 2 intracellular levels (63±14%) and increased gene levels of IL6 (2 fold), IL1β (1 fold), RANTES (1 fold) and MMP2/9 (2 fold) in rat endothelial cells ( vs. veh, p&lt;0.05); all effects were blocked by TLR4 inhibitor (CLI095) and Nox1 inhibitor (ML171). FetA increased JNK (184±19%), but not p38 MAPK, activation in endothelial cells. In VSMCs, FetA-induced TLR4-dependent ROS generation was similar in WKY (136±9%) and SHRSP (144±14%) (p&lt;0.05 vs veh). However, while IL6 gene expression was increased by FetA in WKY (4 fold) and SHRSP (0.5 fold), IL-1β gene levels were only increased by FetA in SHRSP (1 fold) derived VSMCs (p&lt;0.05). CLI095 inhibited FetA effects on IL6 expression; however, TLR4 inhibition did not block FetA effects on IL-1β gene levels. In human endothelial cells, FetA increased ROS levels, was inhibited by CLI095 and a glucose-6-phosphate dehydrogenase (G6PD) inhibitor (6-aminonicotinamide), suggesting that FetA effects may be related to control of cell metabolism. In conclusion, FetA seems to regulate ROS and pro-inflammatory responses by TLR4, Nox1 and G6PD in endothelial cells. In VSMCs, FetA effects on oxidative stress and markers of cell injury are partially dependent on TLR4 activation and may involve other molecular partners.

Abstract 614: TRAIL Deletion in Mice Promotes Vascular Insulin Resistance

TNF-related apoptosis-inducing ligand (TRAIL) is protective in cardiovascular disease and diabetes; whether it regulates insulin resistance and inflammation in the vessel wall is unknown. Wildtype and Trail -/- mice were placed on a high fat diet (HFD) for 12 w. Plasma chemistries were assessed; glucose and insulin tolerance tests performed. Histological GLUT4 expression in skeletal muscle was assessed. Aortic inflammatory marker expression and downstream insulin signaling was also measured; myography was performed. In response to a HFD for 12 w, wildtype mice had increased aortic IL-1beta, MCP-1, IL-6, TNF-alpha and TRAIL mRNA, with reduced circulating TRAIL levels. Compared to 12 w HFD-fed wildtype mice, Trail -/- mice had significantly increased plasma glucose, insulin, and cholesterol levels. Insulin intolerance was worse with TRAIL deletion, with reduced GLUT4 expression and glucose uptake in skeletal muscle. In response to insulin, Trail -/- aortas displayed impaired vasorelaxation and reduced aortic p-Akt expression. Importantly, aortic insulin resistance was associated with &gt; 20-fold increased aortic mRNA expression for IL-1beta, IL-6, and TNF-alpha. We show that TRAIL protects against insulin resistance and type-2 diabetes, in part by regulating downstream insulin signals and inflammation in the vessel wall. These findings suggest that TRAIL may offer a novel therapeutic solution to combat inflammation and insulin resistance in diabetic vascular diseases.

1015 Triggering Receptor Expressed on Myeloid Cells-1 (TREM-1) Regulates Insulin Resistance in Morbidly Obese Population

1015 Triggering Receptor Expressed on Myeloid Cells-1 (TREM-1) Regulates Insulin Resistance in Morbidly Obese Population