Kuanfeng Xu

UCP2 −866G/A and Ala55Val, and UCP3 −55C/T polymorphisms in association with type 2 diabetes susceptibility: a meta-analysis study

Aims/hypothesisA meta-analysis was performed to assess the association between the UCP2 −866G/A, UCP2 Ala55Val and UCP3 −55C/T polymorphisms and type 2 diabetes susceptibility.MethodsA literature-based search was conducted to identify all relevant studies. The fixed or random effect pooled measure was calculated mainly at the allele level to determine heterogeneity bias among studies. Further analyses were performed that stratified for ethnicity.ResultsWe examined 17 publications. Stratified analysis for ethnicity and sensitivity analysis revealed that there was no heterogeneity between studies for these variants. Using an additive model, no significant association of the UCP2 −866G/A polymorphism with type 2 diabetes risk was observed, either in participants of Asian (OR 1.05, 95% CI 0.96, 1.16) or of European (OR 1.03, 95% CI 0.99, 1.07) descent. Neither the UCP2 Ala55Val nor the UCP3 −55C/T polymorphism showed any significant association with type 2 diabetes risk in Europeans (OR 1.04, 95% CI 0.98, 1.09 for Ala55Val; OR 1.04, 95% CI 1.00, 1.09 for −55C/T). In contrast, a statistically significant association was observed for both polymorphisms in participants of Asian descent (OR 1.23, 95% CI 1.12, 1.36 for Ala55Val; OR 1.15, 95% CI 1.03, 1.28 for −55C/T).Conclusions/interpretationOur meta-analysis suggests that the UCP2 −866G/A polymorphism is unlikely to be associated with increased type 2 diabetes risk in the populations investigated. In contrast, our results indicate that the UCP2 Ala55Val and UCP3 −55C/T polymorphisms may indeed be risk factors for susceptibility to type 2 diabetes in individuals of Asian descent, but not in individuals of European descent. This conclusion warrants confirmation by further studies.

UCP2 -866G/A, Ala55Val and UCP3 -55C/T Polymorphisms in Association with Obesity Susceptibility — A Meta-Analysis Study

Aims/hypothesis Variants of UCP2 and UCP3 genes have been reported to be associated with obesity, but the available data on the relationship are inconsistent. A meta-analysis was performed to determine whether there are any associations between the UCP2 -866G/A, Ala55Val, and UCP3 -55C/T polymorphisms and obesity susceptibility. Methods The PubMed, Embase, Web of Science and CNKI, CBMdisc databases were searched for all relevant case-control studies. The fixed or random effect pooled measure was determined on the bias of heterogeneity test among studies. Publication bias was examined by the modified Beggs and Eggers test. Results Twenty-two published articles with thirty-two outcomes were included in the meta-analysis: 12 studies with a total of 7,390 cases and 9,860 controls were analyzed for UCP2 -866G/A polymorphism with obesity, 9 studies with 1,483 cases and 2,067 controls for UCP2 Ala55Val and 8 studies with 2,180 cases and 2,514 controls for UCP3 -55C/T polymorphism. Using an additive model, the UCP2 -866G/A polymorphism showed no significant association with obesity risk in Asians (REM ORu200a=u200a0.81, 95% CI: 0.65–1.01). In contrast, a statistically significant association was observed in subjects of European descent (FEM ORu200a=u200a1.06, 95% CI: 1.01–1.12). But neither the UCP2 Ala55Val nor the UCP3 -55C/T polymorphism showed any significant association with obesity risk in either subjects of Asian (REM ORu200a=u200a0.84, 95% CI: 0.67–1.06 for Ala55Val; REM ORu200a=u200a0.94, 95% CI: 0.55–1.28 for -55C/T) or of European descent (REM ORu200a=u200a1.04, 95% CI: 0.80-1.36 for Ala55Val; FEM ORu200a=u200a1.08, 95% CI: 0.97–1.20 for -55C/T). Conclusions and Interpretation Our meta-analysis revealed that the UCP2 -866G/A polymorphism may be a risk factor for susceptibility to obesity in subjects of European descent, but not in individuals of Asian descent. And our results did not support the association between UCP2 Ala55Val, UCP3 -55C/T polymorphisms and obesity in the populations investigated. This conclusion warrants confirmation by further studies.

Association between rs13266634 C/T polymorphisms of solute carrier family 30 member 8 (SLC30A8) and type 2 diabetes, impaired glucose tolerance, type 1 diabetes—A meta-analysis

AIMSnTo investigate the association of solute carrier family 30 member 8 (SLC30A8) rs13266634 C/T polymorphism with type 2 diabetes (T2DM), impaired glucose tolerance (IGT), and type 1 diabetes (T1DM).nnnMETHODSnWe searched all the publications about the association between SLC30A8 and diabetes from PubMed, and evaluated the association between SLC30A8 rs13266634 C/T polymorphism and T2DM, IGT and T1DM, respectively, by meta-analysis of all the validated studies. Allelic and genotypic comparisons between cases and controls were evaluated.nnnRESULTSnThirty six studies were included in the meta-analysis: 31 studies were analysed for rs13266634 C/T polymorphism with T2DM, 3 studies with IGT and 4 studies with T1DM. The pooled odds ratios (ORs) for allelic and genotypic comparisons (including additive model, co-dominant model, dominant model and recessive model) showed that rs13266634 C/T polymorphism was significantly associated with increased T2DM risk: OR=1.15, 95% confidence interval (CI)=1.13-1.17, P<0.001, P(heterogeneity)=0.041, OR=1.34, 95% CI=1.26-1.41, P<0.001, P(heterogeneity)=0.908, OR=1.20, 95% CI=1.16-1.24, P<0.001, P(heterogeneity)=0.699, and OR=1.23, 95% CI=1.17-1.30, P<0.001, P(heterogeneity)=0.801, respectively. In subgroup analyses, we found that rs13266634 C/T polymorphism was associated with T2DM risk both in Asian and European subgroup (P<0.001), but not in African (P>0.05). And the pooled odds ratio (OR) for allelic frequency comparison showed that rs13266634 C/T polymorphism was also significantly associated with IGT: OR=1.15, 95% CI=1.06-1.26, P<0.001, P(heterogeneity)=0.364. Meanwhile, our meta-analysis did not suggest that rs13266634 C/T polymorphism was associated with T1DM risk (P>0.05): OR=1.02, 95% CI=0.98-1.06, P=0.328, P(heterogeneity)=0.488 for allelic frequency comparison.nnnCONCLUSIONSnOur meta-analysis results revealed the significant association between rs13266634 C/T polymorphism and T2DM and IGT, but did not support the association between this polymorphism and T1DM.

Fat Mass and Obesity-Associated Gene Enhances Oxidative Stress and Lipogenesis in Nonalcoholic Fatty Liver Disease

Background and AimNonalcoholic fatty liver disease (NAFLD) is strongly associated with obesity, hyperlipidemia, and type 2 diabetes mellitus. Several studies have found that fat mass and the obesity-associated (FTO) gene is linked to obesity. The aim of this work is to investigate the expression and function of FTO in liver with lipid metabolism diseases.MethodsWe investigated the basal FTO expression in an NAFLD rat model and compared it with control subjects. The function of FTO in lipid metabolism was further studied in L02 cells through overexpression experiments.ResultsA significant increase in FTO mRNA and protein levels was found in the NAFLD group. In addition, the FTO levels were positively associated with malondialdehyde and superoxide dismutase concentrations. FTO overexpression in L02 cells enhanced lipogenesis and oxidative stress.ConclusionsThis study demonstrates that increased FTO levels in the liver are involved in oxidative stress and lipid deposition, which characterize NAFLD.

IFIH1 gene polymorphisms in type 1 diabetes: genetic association analysis and genotype-phenotype correlation in Chinese Han population

The evaluation of susceptibility loci is an important addition to the current predictive and screening models in type 1 diabetes of Chinese Han population. Therefore, the aim of this study is to provide evidence for the association between type 1 diabetes and two polymorphisms (rs3747517, rs1990760) from interferon induced with helicase C domain 1 (IFIH1). Here, 464 Type 1 diabetespatients and 465 control subjects were genotyped for these 2 polymorphisms. The results indicated that the allelic frequencies of rs3747517 revealed a strong association with type 1 diabetes risk (P < 0.001); yet, no significant association was observed on rs1990760(P = 0.76). Furthermore, IFIH1 rs3747517 polymorphism had no influence on the positive rates of pancreatic auto-antibodies, and both of the polymorphisms had no interaction with HLA class I-linked risk or phenotypes. In conclusion, IFIH1 rs3747517, but not rs1990760 polymorphism, plays an important role in type 1 diabetes risk in Chinese Han population.

Associations between two polymorphisms (FokI and BsmI) of vitamin D receptor gene and type 1 diabetes mellitus in Asian population: a meta-analysis.

Background Vitamin D receptor (VDR) gene polymorphisms are possibly involved in the development of type 1 diabetes mellitus (T1DM). However, the results to date have been inconclusive. We performed a meta-analysis to examine the association between 2 polymorphisms (FokI and BsmI) of the VDR gene and T1DM in the Asian population. Methods Literature was retrieved from PubMed, Web of Science, CBM, Embase and Chinese databases. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using a random or fixed effect model. Results In total, 20 papers (BsmI: 13 studies; FokI: 13 studies) were included. In contrast to the FokI polymorphism, the BsmI polymorphism was associated with an increased risk of T1DM in the Asian population (ORu200a=u200a1.47, 95% CIu200a=u200a1.13–1.91, Pu200a=u200a0.004 for B vs. b). Upon stratification by regional geography, an increased risk of T1DM in association with the BsmI polymorphism was observed in the East Asian population (ORu200a=u200a1.97, 95% CIu200a=u200a1.38–2.83, P<0.001 for B vs. b), whereas the FokI polymorphism was associated with an increased risk of T1DM in the West Asian population (ORu200a=u200a1.45, 95% CIu200a=u200a1.12–1.88, Pu200a=u200a0.004 for F vs. f). Conclusions Our meta-analysis suggests that the BsmI polymorphism may be a risk factor for susceptibility to T1DM in the East Asian population, and the FokI polymorphism is associated with an increased risk of T1DM in the West Asian population. However, because the study size was limited, further studies are essential to confirm our results.

Effects of islet neogenesis-associated protein pentadecapeptide on cell mass and insulin secretion of pancreatic β-cells

Objective: To explore the effects of islet neogenesis-associated protein pentadecapeptide (INGAP-PP) on proliferation and secretion function of β-cells. Methods: Islets of adult Sprague Dawley rats were isolated by colla-genase digestion and treated with 10 µg/ml INGAP-PP, after 12, 24, 48 h, glucose-stimulated insulin secretion (GSIS) and acridine orange/propidium iodide (AO/PI) staining were used to detect the secretion function and cell viability. The INS-1 cells were treated with 0, 1, 10, 25, 50, 100, 250, and 500 µg/ml INGAP-PP for 24 or 48 h, MTT cell proliferation assay was adopted to survey the dose-response relationship between INGAP-PP and cell proliferation. The mRNA expression of roliferating cell nuclear antigen (PCNA), Cyclin D1, Cdk4, P27, p38MAPK, and JNK in INS-1 cells were examined by RT-PCR, and the protein expression of PCNA was examined by Western blot. The statistical significance was determined by Student’s t-test or one-way analysis of variance. Results: The insulin secreted by islets and the cell viability were increased by INGAP-PP. MTT indicated a dose-response relationship between INGAP-PP and quantity of INS-1 cells, and treatment for 48 h had a stronger effect on cell proliferation than the 24 h. INGAP-PP up-regulated the mRNA expression of PCNA, Cyclin D1, Cdk4 and down-regulated P27, p38MAPK, and JNK. Moreover, the protein expression of PCNA was up-regulated by 45% after INGAP-PP exposure for 48 h. Conclusions: INGAP-PP increased the insulin secretion, enhanced the proliferation and might reduce apoptosis of β-cells. The mechanism may contribute to the changed expression of some genes related to cell cycle.

Characterization of immune response to novel HLA-A2-restricted epitopes from zinc transporter 8 in type 1 diabetes.

OBJECTIVEnZnT8-specific CD8+ T cells in human type 1 diabetes (T1D) have been reported recently, although the results from different laboratories are inconsistent. We aimed to characterize these ZnT8 specific CD8+ T cells and validate assays to screen peptide libraries.nnnMETHODSnWe screened HLA-A2-restricted T cell candidate peptides of ZnT8 with different methods including computer algorithms, MHC-peptide binding and dissociation assays in T2 cell line, identification in HLA-A2 transgenic (Tg) mice and in vivo CTL assays. Then ELISpot assay was used to measure peptide-reactive T cell responses in 49 HLA-A2-restricted T1D patients.nnnRESULTSnWe demonstrated that ZnT8(107-116)(115), ZnT8(110-118), and ZnT8(177-186) were novel HLA-A*0201-restricted CTL epitopes in T1D patients. ZnT8(107-116)(115), ZnT8(115-123), ZnT8(153-161), ZnT8(177-186) and ZnT8(291-300) represent potentially major biomarkers for T1D. T cell responses against these epitopes showed different distributions between recently diagnosed and long-standing patients. Furthermore, they displayed discriminating performance among different ethnicities. We also compared the performance of the epitope identification strategies used herein. The epitopes which exhibited strong immunogenicity in HLA-A2 Tg mice were also well recognized by T1D patients.nnnCONCLUSIONSnThe differences in autoimmune T cell responses among T1D individuals may open new avenues toward T1D prediction and prevention. It also provides efficient strategies for immune intervention.

Prediction of HLA class I-restricted T-cell epitopes of islet autoantigen combined with binding and dissociation assays.

Identification of cognate peptides recognized by human leucocyte antigen (HLA)/T cell receptor (TCR) complex provides insight into the pathogenic process of type 1 diabetes (T1D). We hypothesize that HLA-binding assays alone are inadequate metrics for the affinity of peptides. Zinc transporter-8 (ZnT8) has emerged in recent years as a novel, major, human autoantigen. Therefore, we aim to identify the HLA-A2-restricted ZnT8 epitopes using both binding and dissociation assays. HLA class I peptide affinity algorithms were used to predict candidate ZnT8 peptides that bind to HLA-A2. We analyzed 15 reported epitopes of seven β-cell candidate autoantigens and eight predicted candidate ZnT8 peptides using binding and dissociation assays. Using IFN-γ ELISpot assay, we tested peripheral blood mononuclear cells (PBMCs) from recent-onset T1D patients and healthy controls for reactivity to seven reported epitopes and eight candidate ZnT8 peptides directly ex vivo. We found five of seven recently reported epitopes in Chinese T1D patients. Of the eight predicted ZnT8 peptides, ZnT8153–161 had a strong binding affinity and the lowest dissociation rate to HLA-A*0201. We identified it as a novel HLA-A*0201-restricted T-cell epitope in three of eight T1D patients. We conclude that ZnT8153–161 is a novel HLA-A*0201-restricted T-cell epitope. We did not observe a significant correlation (P = 0.3, R = − 0.5) between cytotoxic T cell (CTL) response and peptide/HLA*0201 complex stability. However, selection of peptides based on affinity and their dissociation rate may be helpful for the identification of candidate CTL epitopes. Thus, we can minimize the number of experiments for the identification of T-cell epitopes from interesting antigens.

Multipeptide-coupled nanoparticles induce tolerance in ‘humanised’ HLA-transgenic mice and inhibit diabetogenic CD8+ T cell responses in type 1 diabetes

Aims/hypothesisInduction of antigen-specific immunological tolerance may provide an attractive immunotherapy in the NOD mouse model but the conditions that lead to the successful translation to human type 1 diabetes are limited. In this study, we covalently linked 500xa0nm carboxylated polystyrene beads (PSB) with a mixture of immunodominant HLA-A*02:01-restricted epitopes (peptides-PSB) that may have high clinical relevance in humans as they promote immune tolerance; we then investigated the effect of the nanoparticle–peptide complexes on T cell tolerance.MethodsPSB-coupled mixtures of HLA-A*02:01-restricted epitopes were administered to HHD II mice via intravenous injection. The effects on delaying the course of the disease were verified in NOD.β2mnull HHD mice. The diabetogenic HLA-A*02:01-restricted cytotoxic lymphocyte (CTL) responses to treatment with peptides-PSB were validated in individuals with type 1 diabetes.ResultsWe showed that peptides-PSB could induce antigen-specific tolerance in HHD II mice. The protective immunological mechanisms were mediated through the function of CD4+CD25+ regulatory T cells, suppressive T cell activation and T cell anergy. Furthermore, the peptides-PSB induced an activation and accumulation of regulatory T cells and CD11c+ dendritic cells through a rapid production of CD169+ macrophage-derived C-C motif chemokine 22 (CCL22). Peptides-PSB also prevented diabetes in ‘humanised’ NOD.β2mnull HHD mice and suppressed pathogenic CTL responses in people with type 1 diabetes.Conclusions/interpretationOur findings demonstrate for the first time the potential for using multipeptide-PSB complexes to induce T cell tolerance and halt the autoimmune process. These findings represent a promising platform for an antigen-specific tolerance strategy in type 1 diabetes and highlight a mechanism through which metallophilic macrophages mediate the early cell–cell interactions required for peptides-PSB-induced immune tolerance.