Yufei Xiang

Frequency, Immunogenetics, and Clinical Characteristics of Latent Autoimmune Diabetes in China (LADA China Study): A Nationwide, Multicenter, Clinic-Based Cross-Sectional Study

Adult non–insulin requiring diabetes includes latent autoimmune diabetes of adults (LADA), distinguished from type 2 diabetes by the presence of islet autoantibodies. LADA China determined the characteristics of Chinese LADA. This nationwide, multicenter, clinic-based cross-sectional study was conducted in 46 university-affiliated hospitals in 25 Chinese cities. All 4,880 ketosis-free diabetic patients (<1 year postdiagnosis, without insulin therapy for >6 months, aged ≥30 years) had GAD antibody (GADA) and HLA-DQ genotype measured centrally with clinical data collected locally. GADA-positive subjects were classified as LADA. Of the patients, 5.9% were GADA positive with LADA. LADA showed a north-south gradient. Compared with GADA-negative type 2 diabetes, LADA patients were leaner, with lower fasting C-peptide and less metabolic syndrome. Patients with high GADA titers are phenotypically different from those with low GADA titers, while only a higher HDL distinguished the latter from those with type 2 diabetes. HLA diabetes–susceptible haplotypes were more frequent in LADA, even in those with low-titer GADA. HLA diabetes-protective haplotypes were less frequent in LADA. Our study implicates universal immunogenetic effects, with some ethnic differences, in adult-onset autoimmune diabetes. Autoantibody positivity and titer could be important for LADA risk stratification and accurate therapeutic choice in clinical practice.

Dipeptidyl Peptidase 4 Inhibitor Sitagliptin Maintains β-Cell Function in Patients With Recent-Onset Latent Autoimmune Diabetes in Adults: One Year Prospective Study

CONTEXT Dipeptidyl peptidase 4 (DPP-4) inhibitors have been widely used in type 2 diabetes. An important unanswered question concerns the effect of DPP-4 inhibition on β-cell function in patients with autoimmune diabetes. OBJECTIVE The objective of the study was to investigate the effects of the DPP-4 inhibitor on β-cell function in patients with recent-onset latent autoimmune diabetes in adults (LADA). DESIGN AND SETTING This study was an open-label, randomized-controlled study conducted in the Department of Endocrinology at the Second Xiangya Hospital. PATIENTS AND INTERVENTION Thirty recently diagnosed LADA patients were randomized 1:1 to receive insulin therapy with 100 mg/d sitagliptin (group A, n = 15) or without sitagliptin (group B, n = 15) for 12 months. MAIN OUTCOME MEASURES Fasting and 2-hour postprandial blood samples were obtained at baseline and after 3, 6, 9, and 12 months of treatment to determine blood glucose, glycosylated hemoglobin, and C-peptide levels. RESULTS There were no differences in the clinical baseline data between the two groups. During the 12 months of follow-up, there were no significant differences in glucose and glycosylated hemoglobin levels between the two groups. At 12 months, fasting C-peptide (FCP), 2-hour postprandial C-peptide (CP), and ΔCP (ΔCP = 2 h CP-FCP) levels were not different in group A (P > .05) compared with baseline, whereas in group B the levels of FCP, 2-hour CP and ΔCP were significantly decreased compared with baseline (P < .05). Levels of 2-hour CP were higher in group A than group B at 12 months (P < .05). CONCLUSIONS LADA patients treated with sitagliptin and insulin maintained β-cell function by comparison with insulin alone.

IL-10-conditioned dendritic cells prevent autoimmune diabetes in NOD and humanized HLA-DQ8/RIP-B7.1 mice

This study was to determine whether BMDCs cultured in the presence of IL-10 (G/10-DCs) could promote T cell tolerance and prevent autoimmune diabetes in two different animal models of T1D. Our results showed that G/10-DCs suppressed both insulitis and spontaneous diabetes in NOD and HLA-DQ8/RIP-B7.1 mice. The suppression was likely to be mediated by T cells, as we found that regulatory CD4(+)CD25(+)Foxp3(+) cells were significantly increased in G/10-DC treated animals. In vivo, the G/10-DCs inhibited diabetogenic T cell proliferation; in vitro, they had reduced expression of costimulatory molecules and produced little IL-12/23 p40 or IL-6 but a large amount of IL-10 when compared with DCs matured in the presence of IL-4 (G/4-DC). We conclude that IL-10-treated DCs are tolerogenic and induce islet-directed immune tolerance, which was likely to be mediated by T regulatory cells. This non-antigen-specific DC-based approach offers potential for a new therapeutic intervention in T1D.

Alteration of Regulatory T Cells in Type 1 Diabetes Mellitus: A Comprehensive Review

Type 1 diabetes mellitus (T1DM) is a T cell-mediated autoimmune disease characterized by the destruction of pancreatic β cells. Numerous studies have demonstrated the key role of CD4+CD25+FoxP3+ regulatory T cells (Tregs) in the development of T1DM. However, the changes in Treg expression and function as well as the regulation of these activities are not clearly elucidated. Most studies on the role of Tregs in T1DM were performed on peripheral blood rather than pancreas or pancreatic lymph nodes. Tissue-based studies are more difficult to perform, and there is a lack of histological data to support the role of Tregs in T1DM. In spite of this, strategies to increase Treg cell number and/or function have been viewed as potential therapeutic approaches in treating T1DM, and several clinical trials using these strategies have already emerged. Notably, many trials fail to demonstrate clinical response even when Treg treatment successfully boosts Tregs. In view of this, whether a failure of Tregs does exist and contribute to the development of T1DM and whether more Tregs would be clinically beneficial to patients should be carefully taken into consideration before applying Tregs as treatments in T1DM.

Latent Autoimmune Diabetes in Adults With Low-Titer GAD Antibodies: Similar Disease Progression With Type 2 Diabetes: A Nationwide, Multicenter Prospective Study (LADA China Study 3)

OBJECTIVE This study investigated the relationship between GAD autoantibody (GADA) titers and changing of β-cell function in patients with latent autoimmune diabetes in adults (LADA). RESEARCH DESIGN AND METHODS This 3-year prospective study enrolled 95 subjects from 15 Chinese cities including 25 high-titer (GADA ≥180 units/mL) LADA patients, 42 low-titer (GADA <180 units/mL) LADA patients, and 28 type 2 diabetic patients, the latter two groups as controls of similar age, sex, and BMI. Clinical characteristics were determined annually, including glycosylated hemoglobin (HbA1c), fasting C-peptide (FCP), and 2-h postprandial C-peptide (PCP). RESULTS Despite similar initial FCP and PCP, FCP and PCP both decreased more in subjects with high GADA titer (FCP from mean 0.49 nmol/L at entry to 0.13 nmol/L at the third year; P < 0.05) than with low GADA titer (FCP from mean 0.48 to 0.38 nmol/L) and type 2 diabetes (FCP from mean 0.47 to 0.36 nmol/L); the latter two groups being similar. After 3 years, residual β-cell function (FCP >0.2 nmol/L) was detected in only 42% with an initial high GADA titer compared with 90% with a low GADA titer and 97% with type 2 diabetes (P < 0.01 for both). GADA positivity at the third year persisted more in subjects with initially high GADA (92%) than with low GADA (26%) titers (P < 0.01). CONCLUSIONS In selected LADA patients, initial GADA titers identified subjects with different degrees of persistent autoimmunity and disease progression. LADA patients with a low GADA titer had metabolic phenotypes and loss of β-cell function similar to type 2 diabetic patients.

Heterogeneity of Altered Cytokine Levels Across the Clinical Spectrum of Diabetes in China

OBJECTIVE To determine the relationship between selected cytokines and diabetes in Chinese subjects. RESEARCH DESIGN AND METHODS Adult patients with recent-onset type 1 diabetes (n = 53), latent autoimmune diabetes in adults (LADA) (n = 250), and type 2 diabetes (n = 285) from multiple centers were compared with normal subjects (n = 196). We centrally tested serum GAD antibodies (GADAs), interleukin-6 (IL-6), lipocalin 2 (LCN2), high-sensitivity C-reactive protein (hs-CRP), and adiponectin. RESULTS After adjustment for age, sex, and BMI, all diabetes types had increased IL-6 and LCN2 (P < 0.01), and all four cytokines were increased in LADA (P < 0.01). In type 1 diabetes, adiponectin but not hs-CRP was increased (P < 0.01), whereas in type 2 diabetes, hs-CRP but not adiponectin was increased (P < 0.01). Adiponectin was correlated positively with GADA titer and negatively with hs-CRP (P < 0.01 for both). CONCLUSIONS In China, inflammatory markers are increased in all three major types of diabetes, but probably for different reasons, even in autoimmune diabetes.

The Dual Effects of B Cell Depletion on Antigen-Specific T Cells in BDC2.5NOD Mice

B cells play a critical role in the pathogenesis of autoimmune diabetes. To investigate the mechanisms by which B cell depletion therapy attenuates islet β cell loss and particularly to examine the effect of B cells on both diabetogenic and regulatory Ag-specific T cells, we generated a transgenic BDC2.5NOD mouse expressing human CD20 on B cells. This allowed us to deplete B cells for defined time periods and investigate the effect of B cell depletion on Ag-specific BDC2.5 T cells. We depleted B cells with anti-human CD20 Ab using a multiple injection protocol. We studied two time points, before and after B cell regeneration, to examine the effect on BDC2.5 T cell phenotype and functions that included antigenic response, cytokine profile, diabetogenicity, and suppressive function of regulatory T (Treg) cells. We found unexpectedly that B cell depletion induced transient aggressive behavior in BDC2.5 diabetogenic T cells and reduction in Treg cell number and function during the depletion period. However, after B cell reconstitution, we found that more regenerated B cells, particularly in the CD1d− fraction, expressed immune regulatory function. Our results suggest that the regenerated B cells are likely to be responsible for the therapeutic effect after B cell depletion. Our preclinical study also provides direct evidence that B cells regulate both pathogenic and Treg cell function, and this knowledge could explain the increased T cell responses to islet Ag after rituximab therapy in diabetic patients in a recent report and will be useful in design of future clinical protocols.

Altered Peripheral B-Lymphocyte Subsets in Type 1 Diabetes and Latent Autoimmune Diabetes in Adults

OBJECTIVE B lymphocytes play an important role in the immunopathogenesis of autoimmune diabetes. We hypothesized that the altered B-cell subset phenotype is associated with autoimmune diabetes. RESEARCH DESIGN AND METHODS Patients with type 1 diabetes (T1D) (n = 81), latent autoimmune diabetes in adults (LADA) (n = 82), or type 2 diabetes (T2D) (n = 95) and healthy control subjects (n = 218) with normal glucose tolerance (NGT) were recruited. We determined the percentage of circulating B-lymphocyte subsets, including CD19+CD23−CD21+ (marginal zone B [MZB]), CD19+CD23+CD21− (follicular B [FoB]), and CD19+CD5+CD1dhi (interleukin-10–producing regulatory B [B10]) cells by flow cytometry. RESULTS Patients with T1D or LADA had increased percentages of MZB cells and decreased percentages of FoB cells compared with healthy control subjects with NGT and patients with T2D. Moreover, patients with T1D showed the lowest frequency of B10 cells compared with patients with LADA or T2D, whereas healthy control subjects expressed the highest frequency of B10 cells. Of note, the frequency of MZB cells was negatively associated and the frequency of FoB cells was positively associated with fasting C-peptide (FCP). The frequency of B10 cells was positively correlated with FCP and negatively correlated with hemoglobin A1c. CONCLUSIONS The data show that patients with T1D or LADA express an altered frequency of B-cell subsets, which is associated with islet function and glycemia. These findings suggest that B lymphocytes may be involved in loss of self-tolerance and β-cell destruction and could be used as a biomarker and potential target for immunological intervention.

Zinc transporter 8 autoantibody (ZnT8A) could help differentiate latent autoimmune diabetes in adults (LADA) from phenotypic type 2 diabetes mellitus

The ZnT8A is an independent marker for diagnosis of type 1 diabetes mellitus. We investigated the distribution and clinical features of ZnT8A positive latent autoimmune diabetes in adult (LADA) patients to explore the potential diagnostic application.

Exendin-4 Protects Mitochondria from Reactive Oxygen Species Induced Apoptosis in Pancreatic Beta Cells

Objective Mitochondrial oxidative stress is the basis for pancreatic β-cell apoptosis and a common pathway for numerous types of damage, including glucotoxicity and lipotoxicity. We cultivated mice pancreatic β-cell tumor Min6 cell lines in vitro and observed pancreatic β-cell apoptosis and changes in mitochondrial function before and after the addition of Exendin-4. Based on these observations, we discuss the protective role of Exendin-4 against mitochondrial oxidative damage and its relationship with Ca2+-independent phospholipase A2. Methods We established a pancreatic β-cell oxidative stress damage model using Min6 cell lines cultured in vitro with tert-buty1 hydroperoxide and hydrogen peroxide. We then added Exendin-4 to observe changes in the rate of cell apoptosis (Annexin-V-FITC-PI staining flow cytometry and DNA ladder). We detected the activity of the caspase 3 and 8 apoptotic factors, measured the mitochondrial membrane potential losses and reactive oxygen species production levels, and detected the expression of cytochrome c and Smac/DLAMO in the cytosol and mitochondria, mitochondrial Ca2-independent phospholipase A2 and Ca2+-independent phospholipase A2 mRNA. Results The time-concentration curve showed that different percentages of apoptosis occurred at different time-concentrations in tert-buty1 hydroperoxide- and hydrogen peroxide-induced Min6 cells. Incubation with 100 µmol/l of Exendin-4 for 48 hours reduced the Min6 cell apoptosis rate (p<0.05). The mitochondrial membrane potential loss and total reactive oxygen species levels decreased (p<0.05), and the release of cytochrome c and Smac/DLAMO from the mitochondria was reduced. The study also showed that Ca2+-independent phospholipase A2 activity was positively related to Exendin-4 activity. Conclusion Exendin-4 reduces Min6 cell oxidative damage and the cell apoptosis rate, which may be related to Ca2-independent phospholipase A2.