Nanwei Tong

PPARδ Activation Rescues Pancreatic β-Cell Line INS-1E from Palmitate-Induced Endoplasmic Reticulum Stress through Enhanced Fatty Acid Oxidation

One of the key factors responsible for the development of type 2 diabetes is the loss of functional pancreatic β cells. This occurs due to a chronic exposure to a high fatty acid environment. ER stress is caused by an accumulation of irreversible misfold or unfold protein: these trigger the death of functional pancreatic β cells. PPARδ is an orphan nuclear receptor. It plays a pivotal role in regulating the metabolism of dietary lipids and fats. However, the correlation between PPARδ of fatty acids and ER stress of pancreatic β cells is not quite clear till date. Here, we show that PPARδ attenuates palmitate-induced ER stress of pancreatic β cells. On the other hand, PPARδ agonist inhibits both abnormal changes in ER structure and activation of signaling cascade, which is downstream ER stress. Further, we illustrate that PPARδ attenuates palmitate-induced ER stress by promoting fatty acid oxidation through treatment with etomoxir, an inhibitor of fatty acid oxidation. It dramatically abolishes PPARδ-mediated inhibition of ER stress. Finally, we show that PPARδ could protect pancreatic β cells from palmitate-induced cell death and dysfunction of insulin secretion. Our work elucidates the protective effect of PPARδ on the fatty-acid-induced toxicity of pancreatic β cells.

Modified High-Sucrose Diet-Induced Abdominally Obese and Normal-Weight Rats Developed High Plasma Free Fatty Acid and Insulin Resistance

Introduction. Metabolically obese but normal-weight (MONW) individuals have metabolic features of overt obesity, and abdominal adiposity is common in them. Animal models of MONW individuals are lacking. We aimed to develop an abdominally obese and normal-weight (AONW) rat model. Methods and Results. Young male Sprague-Dawley rats were fed chow or a modified high-sucrose (HS) diet for 20 weeks. The HS diet induced increased visceral adipose tissue without increased body weight, reduced glucose disposal rates, and increased hepatic glucose output during the hyperinsulinemic-euglycemic clamp, increased plasma glucose during the intraperitoneal glucose tolerance test, and increased plasma free fatty acids. Hepatic lipidosis and hepatocyte mitochondria swelling were found in HS rats through light microscopy and transmission electron microscopy; similar impairments were not observed in muscle. RT-PCR showed that mRNA expression of uncoupling protein 3 and peroxisome proliferator-activated receptor-gamma coactivator 1α increased in muscle of HS rats, while expression of mitochondrial transcription factor A, glucose transporter type 4, and insulin receptor substrate-1 did not change significantly. Conclusion. AONW rats developed metabolic disorders seen in MONW individuals. Steatosis, mitochondrial morphologic changes, and insulin resistance were more serious in liver than in muscle. Genes involved in fatty acid metabolism and mitochondrial function changed in less impaired muscle.

Cardiovascular effects of dipeptidyl peptidase-4 inhibitor in diabetic patients with and without established cardiovascular disease: a meta-analysis and systematic review

ABSTRACT Objectives: We aim to conduct a meta-analysis, by stratifying diabetic patients with or without clinical cardiovascular diseases (CVD), to explore whether there are different cardiovascular effects of dipeptidyl peptidase-4 inhibitors (DPP-4is) on these two different classes of diabetic patients. Methods: We searchedMedline,Embase, theCochrane Libraryand ClinicalTrials.gov for relevant randomized controlled trials (RCTs). The included trials are divided into CVD (+) trials (subjects with established CVD), and CVD (-) trials (subjects with no CVD). We use all-cause mortality and cardiovascular outcomes as primary endpoints. Results: (1) Three CVD (+) trials were included and 36,895 subjects were enrolled with a mean follow-up duration of 127.1 weeks. The pooled results showed that DPP-4is treatment, compared with the placebo, did not significantly affect all-cause mortality (RR, 1.03; 95% CI, 0.95 to 1.11), cardiovascular death (1.01, 0.91 to 1.12), myocardial infarction (0.98, 0.88 to 1.08) or stroke (1.02, 0.88 to 1.18) in diabetic patients with coexisting CVD history; however, it significantly increased the risk of heart failure (1.14, 1.01 to 1.27) in this population. 2) Thirty-five CVD (-) trials were included, and 29,600 patients were enrolled with a mean follow-up duration of 77.8 weeks. The analysis comparing DPP-4is with the placebo control showed that DPP-4is treatment did not significantly affect the risk of all-cause mortality or cardiovascular outcomes in diabetic patients free of CVD history. However, when compared with the active control, the pooling data showed that DPP-4is had a significant reduction on the risk of stroke (0.58, 0.34 to 0.99) but did not significantly affect the risk of all-cause mortality and other cardiovascular outcomes. Conclusion: DPP-4is may have no cardiovascular protective effects in diabetic patients with coexisting CVD, while there is a lack of definitive evidence supporting the cardiovascular benefits of DPP-4is treatment among diabetic patients free of CVD history.

Differences between Western and Asian type 2 diabetes patients in the incidence of vascular complications and mortality: A systematic review of randomized controlled trials on lowering blood glucose.

Differences exist between Western and Asian people with type 2 diabetes (T2D). The aim of the present systematic review was to determine whether there are differences in chronic diabetic vascular complications (CDVCs) and mortality between Western and Asian patients with T2D.

Acarbose Monotherapy and Type 2 Diabetes Prevention in Eastern and Western Prediabetes: An Ethnicity-specific Meta-analysis

PURPOSE Acarbose is effective in delaying or preventing the progression of prediabetes to type 2 diabetes mellitus (T2DM). The aim of this study was to assess differences in the preventive effects of acarbose in Eastern and Western populations with prediabetes. METHODS We performed a systematic search of databases and reference lists of clinical trials conducted through August 2013. Randomized controlled trials of acarbose alone, with a minimum intervention duration of 3 years and which provided data on T2DM incidence, were included for analysis. Analyses were conducted by using Review Manager version 5.1 software. FINDINGS Eight randomized controlled trials with 2628 participants were included. Acarbose decreased the occurrence of T2DM (number needed to treat [NNT], 6.7). Compared with the control (placebo and/or lifestyle intervention), the incidence of T2DM was significantly lower in the Eastern group (NNT, 5.9) than in the Western group (NNT, 11.1) (P < 0.0001, I(2) = 94.7%). At the end of follow-up, reversal of prediabetes to normal glucose tolerance was more likely in the Eastern group (NNT, 4.3) than in the Western group (NNT, 25) (P = 0.004, I(2) = 92%). Among those remaining prediabetic, there was no significant difference between the subtotal estimates for the subgroups (P = 0.17, I(2) = 46.5%). There was no positive correlation between preventive effect and dose, and no difference in studies with varying follow-up durations within and across either ethnic group. IMPLICATIONS The preventive effect of acarbose on the development of diabetes seems superior in Eastern populations with prediabetes compared with Western populations.

The association of visceral adipose tissue and subcutaneous adipose tissue with metabolic risk factors in a large population of Chinese adults.

Abdominal visceral (VAT) and subcutaneous (SAT) adipose tissues contribute to obesity, but may have different cardiometabolic risk profiles. We examined and compared the associations of abdominal VAT and SAT with metabolic risk factors in a large cohort of Chinese adults.

Efficacy and safety of glucagon-like peptide-1 receptor agonists in non-alcoholic fatty liver disease: A systematic review and meta-analysis.

BACKGROUND AND OBJECTIVE New drugs are urgently needed for the treatment of non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH). The aim of this meta-analysis was to evaluate the efficacy and safety of glucagon-like peptide-1 receptor agonists (GLP-1RAs) in NAFLD/NASH. METHODS We searched the MEDLINE, Embase, and Cochrane Library Central to identify randomized controlled trials (RCTs) and observational studies that compared GLP-1RAs with a control treatment or baseline values with respect to efficacy and safety in patients with NAFLD/NASH. Mean differences (MDs) with 95% confidence intervals (CIs) and odds ratios (ORs) were pooled using a random-effect model. RESULTS Six studies were eligible and included. Among the 329 NAFLD/NASH patients included in these studies, 277 patients had type 2 diabetes (T2D). GLP-1RA treatment produced significant reductions relative to baseline in liver histology scores for steatosis (MD, 0.80; 95% CI, 0.49 to 1.11), lobular inflammation (MD, 0.22; 95% CI, 0.00 to 0.45), hepatocellular ballooning (MD, 0.41; 95% CI, 0.15 to 0.67) and fibrosis (MD, 0.35; 95% CI, 0.00 to 0.70). Compared with placebo and positive agents, GLP-1RAs significantly reduced gamma-glutamyl transpeptidase (GGT) levels (MD, 13.8 U/L; 95% CI, 7.4 to 20.3; P<0.001). The reported major adverse events associated with GLP-1RA treatment included mild to moderate gastrointestinal discomfort that resolved within a few weeks. CONCLUSIONS Our study suggests that in NASH patients, particularly patients with diabetes, GLP-1RAs may improve liver histology and reduce aminotransferase levels from baseline. Benefits of GLP-1RAs are considered to outweigh the risks in NAFLD/NASH patients with or without diabetes.

Efficacy and safety of dulaglutide in patients with type 2 diabetes: a meta-analysis and systematic review

A meta-analysis was conducted to assess the clinical efficacy and safety of dulaglutide in patients with type 2 diabetes mellitus (T2DM). Medline, Embase, Cochrane Library and www. clinicaltrials. gov (up to February 15th, 2015) were searched. Randomized controlled trials comparing dulaglutide to other drugs for T2DM were collected. Twelve RCTs were included, and the overall bias was low. As the monotherapy, compared with control (placebo, metformin and liraglutide), dulaglutide resulted in a significant reduction in HbA1c (WMD, −0.68%; 95% CI, −0.95 to −0.40), FPG (WMD, −0.90 mmol/L; 95% CI, −1.28 to −0.52), a similar risk of hypoglycemia (7.8% vs. 10.6%), less body weight loss (WMD, 0.51 kg; 95% CI, 0.27 to 0.75). As an add-on intervention with oral antihyperglycemic medication (OAM) and insulin, compared with control (placebo, sitagliptin, exenatide, liraglutide and glargine), dulaglutide lowered HbA1c (WMD, −0.51%; 95% CI, −0.68 to −0.35) and body weight significantly (WMD, −1.30 kg, 95% CI, −1.85 to −1.02) notably, and elicited a similar reduction in FPG (WMD, −0.19 mmol/L; 95% CI, −1.20 to 0.82), an similar incidence of hypoglycemia (24.5% vs. 24.5%). This meta-analysis revealed the use of dulaglutide as a monotherapy or an add-on to OAM and lispro appeared to be effective and safe for adults with T2DM.

Effects on All-cause Mortality and Cardiovascular Outcomes in Patients With Type 2 Diabetes by Comparing Insulin With Oral Hypoglycemic Agent Therapy: A Meta-analysis of Randomized Controlled Trials

PURPOSE Retrospective, case-control studies and prospective randomized controlled trials (RCTs) on insulin treatment for diabetic patients yielded contradictory mortality and cardiovascular outcomes. We aimed to evaluate the effects of insulin versus oral hypoglycemic agents (OHAs) on all-cause mortality and cardiovascular outcomes in patients with type 2 diabetes (T2D). METHODS We searched Medline, Embase, Cochrane Central Register of Controlled Trials, Chinese Biological Medicine Database, China National Knowledge Infrastructure, Chinese Technical Periodicals, and Wanfang Data, up to July 10, 2015, for RCTs on insulin and OHAs that assessed all-cause mortality and/or cardiovascular death as primary end points. We derived pooled risk ratios (RRs) as summary statistics. RESULTS Three trials were included in which 7649 patients received insulin and 8322 received OHAs, with mean (SD) diabetes duration of 5.0 (6.2) and 4.4 (5.9) years, respectively. Insulin did not differ from OHAs in all-cause mortality (RR = 1.00; 95% CI, 0.93-1.07), cardiovascular death (RR = 1.00; 95% CI, 0.91-1.09), myocardial infarction (RR = 1.04; 95% CI, 0.93-1.16), angina (RR = 0.97; 95% CI, 0.88-1.06), sudden death (RR = 1.02; 95% CI, 0.66-1.56), or stroke (RR = 1.01; 95% CI, 0.88-1.15). Insulin reduced the risk of heart failure compared with OHAs (RR = 0.87; 95% CI, 0.75-0.99). In the subgroup of secondary prevention of cardiovascular diseases (CVDs) or very high risk of CVDs, insulin did not differ from OHAs in all-cause mortality (RR = 0.99; 95% CI, 0.92-1.07), cardiovascular death (RR = 0.99; 95% CI, 0.90-1.09), myocardial infarction (RR = 1.01; 95% CI, 0.88-1.15), heart failure (RR = 0.69; 95% CI, 0.34-1.40), or stroke (RR = 1.05; 95% CI, 0.90-1.21). IMPLICATIONS Insulin did not provide a clear benefit over OHAs in all-cause mortality or cardiovascular outcomes in the patients with T2D. Insulin therapy has many shortcomings, including inconvenience (injection, strict blood glucose monitoring), hypoglycemia, and obvious weight gain. Thus, we conclude that no robust evidence supports the active use of insulin for this population at present.

Efficacy and safety of sodium-glucose cotransporter 2 inhibitors in patients with type 2 diabetes and moderate renal function impairment: A systematic review and meta-analysis

AIMS A systematic review and meta-analysis was conducted to evaluate the clinical efficacy and safety of sodium-glucose cotransporter 2 (SGLT2) inhibitors in patients with type 2 diabetes (T2D) and moderate renal function impairment. METHODS Embase, Medline, and Cochrane Central were searched, and randomized controlled trials comparing SGLT2 inhibitors to placebos and other drugs for T2D were collected. RESULTS Seven RCTs with a total of 3307 participants were included, and the overall bias was low. In the patients with T2D and moderate renal function impairment (30 ml/min/1.73 m2 ≤ estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m2) compared with the placebo, SGLT2 inhibitors improved HbA1c significantly (WMD, -0.23%; 95% CI: -0.38 to -0.08), presented a lower incidence of hypoglycemia (30.1% vs. 34.6%; RR, 0.85; 95% CI: 0.76 to 0.96), led to the reduction of eGFR (WMD, -1.74 ml/min/1.73 m2; 95% CI: -3.45 to -0.03), resulted in an obvious reduction in body weight (WMD, -1.45 kg; 95% CI: -2.01 to -0.89), and presented a similar risk of urinary tract infection and genital infection. CONCLUSIONS SGLT2 inhibitors are safe, but mildly reduce the HbA1c level. The clinical significance of SGLT2 inhibitors in the target population was limited.