Review Article Immunogenetic Heterogeneity of Type 1 Diabetes in Japan

Type 1 diabetes is an organ-specific autoimmune disease characterized by T-cell mediated destruction of pancreatic ﾎｲ-cells . In Japanese population, the incidence of type 1 diabetes in children is very low compared to European countries. However, there are more patients with type 1 diabetes in adults, including latent autoimmune diabetes in adults (LADA). A variety of environmental and genetic factors are involved in the development of the disease. The human leukocyte antigen (HLA) class II genes (termed IDDM1) are the major genes associated with susceptibility to type 1 diabetes. HLA-DRB1*0405-DQB1*0401, HLA-DRB1* 0901-DQB1*0303 and HLA-DRB1*0802-DQB1*0302 are three major haplotypes in Japanese patients with type 1 diabetes. Other genetic factors reported in Japanese type 1 diabetes include the polymorphisms in insulin gene (IDDM2), CTLA-4 gene (IDDM12), MICA gene, Neuro D/Beta 2 gene, and IL-10 gene. The circulating autoantibodies to multiple islet autoantigens including GAD, insulin, and IA-2 are the important immunological features of type 1 diabetes. The prevalences of anti-islet autoantibodies in patients with Japanese type 1 diabetes are 60-70% for GAD autoantibodies, 45-50% for insulin autoantibodies (IAA), and 60-65% for IA-2 autoantibodies at disease onset, which are similar to those reported in Caucasian patients. With combinatorial analysis of these autoantibodies ninety percent of patients express at least one of these autoantibodies and are classified as immune-mediated type 1 diabetes. Although the majority of patients with type 1 diabetes are young, lean, and ketosisprone, there are number of patients with type 1 diabetes initially diagnosed as having type 2 diabetes at disease onset. These slow-onset diabetic patients with anti-islet autoantibodies often progress toward insulin-deficient state within several years after diagnosis. High level of GAD autoantibodies has a high predictive value for future insulin deficiency in slow-onset patients with type 1 diabetes. In conclusion, Japanese patients with type 1 diabetes are clinically heterogenous and the determination of immunological and genetic features are helpful to clarify the characteristics of the Japanese type 1 diabetic syndrome

Minor contribution of cytotoxic T lymphocyte antigen 4 and programmed cell death 1 ligand 1 in immune tolerance against mouse thyrotropin receptor in mice

We have previously shown that wild type (wt) mice exhibit susceptibility to immunization with human (h) thyrotropin receptor (TSHR), but resistance to mouse (m) TSHR, while TSHR knockout (KO) mice are susceptible to mTSHR, indicating the existence of robust immune tolerance against the mTSHR in wt mice. This tolerance may be mediated by either centrally or peripherally. We here explored the contribution of a peripheral arm of immune tolerance against the mTSHR by using antibodies to deplete regulatory T cells (Tregs), to antagonize co-inhibitory molecules and/or to stimulate co-stimulatory molecules. Antagonistic anti-co-inhibitory molecules, cytotoxic T lymphocyte antigen 4 (CTLA4) and programmed cell death 1 ligand 1 (PDL1), induced only low levels of anti-TSHR antibodies without induction of hyperthyroidism in a mouse Graves\u27model. In this experimental setting, antibody levels were significantly higher in THSR+/- mice than wt mice. However, agonistic anti-co-stimulatory molecules, CD40 and CD137, and Treg-depleting anti-CD25 antibodies showed no effect. All these data suggest that peripheral immune tolerance against the mTSHR may play a minor role, and imply the importance of central tolerance, in immune tolerance against mTSHR in mice. Additional studies on central tolerance to the mTSHR will be necessary for completely delineating the mechanisms for immune tolerance against mTSHR in mice

Clinical and genetic characteristics of autoimmune polyglandular syndrome type 3 variant in the Japanese population

Objective: Type 1 diabetes (T1D) iscommonlyassociated withautoimmunethyroid disease (AITD),and the occurrence of both T1D and AITD in a patient is defined as autoimmune polyglandular syndrome type 3 variant (APS3v). We aimed to clarify the differences in the clinical and genetic characteristics of APS3v patients and T1D patients without AITD [T1D/AITD(-)] in the Japanese population. Design/Patients: Our subjects were 54 APS3v patients and 143 T1D/AITD(-) patients who were consecutively diagnosed at Nagasaki University Hospital from 1983 to the present. Results: A remarkable female predominance, a slow and older age onset of T1D, and a higher prevalence of glutamic acid decarboxylase autoantibodies were observed in APS3v patients compared to T1D/AITD(-) patients. The older onset age of T1D in APS3v patients was associated with a higher proportion of slow-onset T1D. Among the two major susceptible human leukocyte antigen (HLA) class II haplotypes in Japanese T1D, DRB1*0405- DQB1*0401, but not DRB1*0901-DQB1*0303, was associated with APS3v patients. Furthermore, DRB1*0803-DQB1*0601 was not protective in patients with APS3v. The frequencies of the GG genotype in +49G>A and +6230G>A polymorphism in the CTLA4 gene were significantly higher in T1D/AITD(-) patients, but not in APS3v patients, compared to control subjects. Conclusions: In conclusion, we found notable differences in the clinical and genetic characteristics of APS3v patients and T1D/AITD(-) patients in the Japanese population, and the differences in the clinical characteristics between the two groups may reflect distinct genetic backgrounds including the HLA DRB1-DQB1 haplotypes and CTLA4 gene polymorphisms

Autoantibodies to insulin, insulinoma-associated antigen-2, and zinc transporter 8 improve the prediction of early insulin requirement in adult-onset autoimmune diabetes

Objective: The aim of this study was to indentify the predictive marker for early insulin requirement in adult-onset autoimmune diabetes in the Japanese populations.Design/Patients: We analyzed insulin autoantibodies (IAA), IA-2 autoantibodies (IA-2icA), and ZnT8 autoantibodies (ZnT8A) by radioimmunoassay in 47 Japanese patients with adult-onset autoimmune diabetes who were identified by native GAD autoantibody (nGADA) screening in ~3,000 non-insulin-requiring diabetes and in 302 nGADA-negative type 2 diabetes. Furthermore, GAD65 autoantibody-specific epitopes were also analyzed using GAD65/GAD67 chimeric constructs.Results: The prevalence of IAA, IA-2icA and ZnT8A in nGADA-positive patients was 26%, 15%, and 19%, respectively, which was significantly higher than that in nGADA-negative type 2 diabetes (2%, 2%, and 2%, P<0.0001). Among nGADA-positive patients, 38% had one or more of IAA, IA-2icA, or ZnT8A, and 15% had two or more of these autoantibodies, compared with none of the nGADA-negative patients (P<0.0001). Thirty-six % of nGADA-positive patients subsequently required insulin therapy, and high nGADA titer (log-rank P=0.003), middle epitope recognition of GAD65A (P=0.002), and the presence of one or more of IAA, IA-2icA, or ZnT8A (P=0.002) at diagnosis marked the risk for early requirement of insulin therapy. Multivariate logistic regression analysis showed the multiple islet autoantibodeis to be independently associated with the risk for insulin requirement (Odds ratio=13.77, 95%CI: 2.77-68.45, P=0.001).Conclusions: These results indicate that the determination of IAA, IA-2icA, and ZnT8A improves the prediction of a future insulin insufficiency in adult-onset autoimmune diabetes, which appears to be superior to GADA titer and GAD65A-specific epitopes

Humoral immune response to islet autoantigens in Japanese patients with type 1 diabetes.

In this study, we evaluated autoantibodies to IA-2 (IA-2As), glutamic acid decarboxylase 65 (GADAs), and islet cell antibodies (ICAs) in 233 patients with type 1 diabetes (M:F = 90:143, mean duration 4.0 +/- 6.7 yr) as a cross-sectional study. Of 233 patients with type 1 diabetes, IA-2A was detected in 58% of patients with duration within 2 weeks, 61% of patients with duration or=10 yr. These prevalences were similar to those of ICA, while the prevalence of GADA was not influenced by duration of diabetes with positivity of 63-74%. Thus, as the duration of diabetes became longer, the frequency of GADA(+)/IA-2A(-) patients increased and the frequency of GADA(+)/IA-2A(+) patients decreased. However, the frequency of GADA(-)/IA-2A(+) patients was not influenced by duration of diabetes. The prevalence of IA-2A was significantly higher in abrupt-onset group (68%, n= 79) compared to the slowly progressive group (23%, n= 22) in new-onset patients (P= 0.0001). However, there was no difference in the IA-2A frequency between these two groups (abrupt-onset 26%, n= 53 vs. slowly progressive 24%, n= 21) in patients with long-standing disease, suggesting that IA-2A positivity might persist in patients with slowly progressive type 1 diabetes. These results emphasize the heterogeneity of humoral autoimmunity to protein tyrosine phosphatase-like molecules, but not to GAD, in patients with type 1 diabetes

Association of the GCKR rs780094 polymorphism with metabolic traits including carotid intima-media thickness in Japanese community-dwelling men, but not in women

Background: The glucokinase regulator gene (GCKR) rs780094 has been shown to be strongly associated with some metabolic traits and atherosclerotic parameters, while the association between GCKR rs780094 and carotid intima-media thickness (CIMT) has not been fully investigated in the general population. The associations between the GCKR rs780094 genotype and metabolic traits including CIMT were examined in a Japanese community-dwelling population. Methods: A total of 2491 Japanese adults (907 men and 1584 women) who participated in a medical screening program for the general population from 29 to 94 years of age during 2008 to 2010 were enrolled. GCKR rs780094 was genotyped by the TaqMan polymerase chain reaction method, and associations with metabolic markers including CIMT were evaluated. Results: GCKR rs780094 AA genotype was significantly associated with higher TG (p < 0.001 vs. GG), lower HDL-C (p = 0.021 vs. GG), and lower HbA1c (p = 0.023 vs. GG). The AA genotype showed significantly thinner CIMT (p = 0.001 vs. GX). These associations were seen only in men. Conclusions: GCKR rs780094 was associated with TG, HDL-C, and HbA1c levels, as well as with CIMT in Japanese community-dwelling men, but not women

Combined insulin B:9-23 self-peptide and polyinosinic-polycytidylic acid accelerate insulitis but inhibit development of diabetes by increasing the proportion of CD4+Foxp3+ regulatory T cells in the islets in non-obese diabetic mice.

Insulin peptide B:9-23 is a major autoantigen in type 1 diabetes. Combined treatment with B:9-23 peptide and polyinosinic-polycytidylic acid (poly I:C), but neither alone, induce insulitis in normal BALB/c mice. In contrast, the combined treatment accelerated insulitis, but prevented diabetes in NOD mice. Our immunofluorescence study with anti-CD4/anti-Foxp3 revealed that the proportion of Foxp3 positive CD4(+)CD25(+) regulatory T cells (Tregs) was elevated in the islets of NOD mice treated with B:9-23 peptide and poly I:C, as compared to non-treated mice. Depletion of Tregs by anti-CD25 antibody hastened spontaneous development of diabetes in non-treated NOD mice, and abolished the protective effect of the combined treatment and conversely accelerated the onset of diabetes in the treated mice. These results indicate that poly I:C combined with B:9-23 peptide promotes infiltration of both pathogenic T cells and predominantly Tregs into the islets, thereby inhibiting progression from insulitis to overt diabetes in NOD mice

Leptin to high-molecular-weight adiponectin ratio is independently correlated with carotid intima-media thickness in men, but not in women.

BACKGROUND: The leptin:adiponectin ratio (L:A ratio) is an independent predictor of carotid intima-media thickness (CIMT). OBJECTIVE: To evaluate whether the leptin:high-molecular-weight adiponectin ratio (L:HA ratio) is associated with CIMT in the general population. METHODS: We investigated the relationship between the L:HA ratio and CIMT in 233 Japanese study participants (106 men and 127 women). RESULTS: After adjustment for confounding factors, CIMT was significantly correlated with the log L:HA ratio (beta = 0.11, p = 0.014) in men, whereas no correlation was observed in women (beta = 0.01, p = 0.50). Conclusion: The L:HA ratio is closely correlated with CIMT in men, but not in women

Predictive factors of efficacy of combination therapy with basal insulin and liraglutide in type 2 diabetes when switched from longstanding basal-bolus insulin: Association between the responses of β- and α-cells to GLP-1 stimulation and the glycaemic control at 6?months after switching therapy

Aims: To evaluate the glycaemic control of combination therapy with basal insulin and liraglutide, and to explore the factors predictive of efficacy in patients with type 2 diabetes when switched from longstanding basal-bolus insulin therapy. Methods: We studied 41 patients who switched from basal-bolus insulin therapy of more than 3 years to basal insulin/liraglutide combination therapy. Glycaemic control was evaluated at 6 months after switching therapy and used to subdivide the patients into good-responders (HbA1c <7.0% or 1.0% decrease) and poor-responders (the rest of participants). To evaluate the glucose-dependent insulin/glucagon responses without/with liraglutide, a 75-g oral glucose tolerance test (OGTT) was performed twice, before (1st-OGTT) and 2-days after (2nd-OGTT) liraglutide administration. Results: Twenty-eight patients (68.3%) were identified as good-responders. No differences were found in baseline characteristics including insulin/glucagon responses during 1st-OGTT between the groups. 2nd-OGTT revealed that paradoxical hyperglucagonemia were significantly improved in both groups, but significant increases in insulin secretory response were observed only in good-responders. Logistic regression analyses revealed that the improvement of the insulin-response during 2nd-OGTT compared to that during 1st-OGTT is associated with the good-responder. Conclusions: Enhancement of glucose-dependent insulin-response under liraglutide administration is a potential predictor of long-term glycaemic control after switching the therapies

Impaired early-phase suppression of glucagon secretion after glucose load is associated with insulin requirement during pregnancy in gestational diabetes

Aims/Introduction: The role of glucagon abnormality has recently been reported in type 2 diabetes; however, its role in gestational diabetes mellitus (GDM) is still unknown. The glucose intolerance in GDM is heterogeneous, and not all patients require insulin treatment during pregnancy. Here, we investigated whether glucagon abnormality is associated with the requirement for insulin treatment during pregnancy. Materials and Methods: A total of 49 pregnant women diagnosed with GDM were enrolled. They underwent a 75-g oral glucose tolerance test during mid-gestation, and we measured their plasma glucagon levels (by a new sandwich enzyme-linked immunosorbent assay) at fasting (0 min), and at 30, 60 and 120 min after glucose load in addition to the levels of plasma glucose and serum insulin. All participants underwent another oral glucose tolerance test at postpartum. Results: Of the 49 patients, 15 required insulin treatment (Insulin group) and 34 were treated with diet therapy alone until delivery (Diet group). The early-phase glucagon secretion after glucose load, as determined by the changes in glucagon from the baseline to 30 min, was paradoxically augmented during mid-gestation in the Insulin group, but not in the Diet group. The impaired glucagon suppression during mid-gestation in the Insulin group was not associated with insulin secretory/sensitivity indexes studied, and was ameliorated postpartum, although the plasma glucose levels remained higher in the Insulin group versus the Diet group. Conclusions: Impaired early-phase suppression of glucagon could be associated with the requirement for insulin treatment during pregnancy in patients with GDM