Association between IL-18 gene promoter polymorphisms and CTLA-4 gene 49A/G polymorphism in Japanese patients with type 1 diabetes.

Interleukin-18 (IL-18) is a potent proinflammatory cytokine which is strongly associated with the development of diabetes in NOD mice. To test the putative involvement of IL-18 gene polymorphism in predisposition to human type 1 diabetes, the SNPs at position -607 (C/A) and -137 (G/C) in the promoter region of IL-18 gene were analyzed by sequence-specific PCR in 116 patients with type 1 diabetes and 114 normal controls. A linkage disequilibrium found only three of the four possible haplotypes defined by these SNPs. The distribution of the IL-18 gene genotypes at position -607 was significantly different between patients with type 1 diabetes and normal controls (P=0.023). Furthermore, there was a significant increase in haplotype 1 (-607C/-137G) in the patients compared with controls (P=0.006). The association study of the susceptible CTLA-4 genotype (GG at nucleotide position 49 in exon 1) or HLA-DR4-DQB1*0401 and type 1 diabetes showed that the predisposing IL-18 gene haplotype modulates the risk on CTLA-4 GG genotype, but not on HLA-DR4-DQB1*0401 haplotype. Among subjects carrying the CTLA-4 GG genotype, the frequency of IL-18 haplotype 1 in patients with type 1 diabetes was significantly higher than that in controls (91% vs. 71%, P=0.012). However, IL-18 haplotype 1 was not frequent in patients who do not exhibit the CTLA-4 high-risk genotype. These results suggest that the IL-18 gene polymorphism is associated with a type 1 diabetes susceptibility, and there might be a gene-gene interaction between IL-18 gene with susceptible CTLA-4 gene.

In vivo expression of B:9-23 peptide/I-A(g7) complex may abrogate the inhibition of diabetes induced by RGD-fiber-mutant adenovirus in NOD mice.

Insulin B chain peptide B:9-23 given to NOD mice decreases the development of diabetes, and phase II trials of an altered peptide ligand of B:9-23 are under way in humans. We have created a gene for the NOD MHC class II beta chain, covalently linked to the B:9-23 peptide. B lymphoma cells transfected with the gene stimulated NOD islet-derived B:9-23 reactive T cell clones in vitro. In this study, we generated an RGD-fiber-mutant adenovirus vector encoding the covalent B:9-23 peptide/I-A(g7) gene (Ad-RGD-B:9-23) to test whether in vivo expression of the gene could protect NOD mice from diabetes. NOD female mice were injected intramuscularly with 5 x 10(8) PFU of Ad-RGD-B:9-23 and empty RGD-adenovirus vector. A single administration of the empty vector did not alter the expression of insulin autoantibodies, but delayed the onset of diabetes in NOD mice. In contrast, Ad-RGD-B:9-23 immunization induced an early expression of insulin autoantibodies, but did not change the disease occurrence compared to control NOD mice. Our results suggest that adenovirus infection could confer protection from diabetes in NOD mice. The in vivo expression of covalent B:9-23 peptide/class II complex by adenovirus gene transfer might activate anti-insulin autoimmunity, resulting in abrogation of the inhibition of diabetes induced by an RGD-fiber-mutant adenovirus vector.

Interleukin-10 gene promoter region polymorphisms in patients with type 1 diabetes and autoimmune thyroid disease.

Type 1 diabetes is a heterogeneous autoimmune disease and is frequently associated with other organ-specific autoimmune diseases, including autoimmune thyroid disease (AITD). Type 1 diabetic patients with AITD are known to show distinct clinical and immunological features from patients without AITD. This study investigated whether interleukin-10 (IL-10) gene promoter region polymorphisms are associated with susceptibility to type 1 diabetes and AITD. The frequency of -1082G/A, -819C/T, and -592C/A polymorphisms was analyzed in 54 type 1 diabetic patients with AITD, 74 type 1 diabetic patients without AITD, 124 nondiabetic patients with AITD, and 107 healthy subjects in a case-control study. No significant differences on the allele and genotype frequencies of three polymorphisms were found not only in type 1 diabetic patients with AITD compared with normal controls, but also between nondiabetic patients with AITD and healthy controls. The distribution of IL-10 gene haplotypes was also similar between both patient groups and normal controls. These results suggest that IL-10 gene promoter region polymorphisms are not associated with genetic susceptibility to type 1 diabetes and AITD.

Association of interleukin-18 gene promoter polymorphisms in type 1 diabetes and autoimmune thyroid disease.

Type 1 diabetes is a heterogeneous autoimmune disease and is often associated with other organ-specific autoimmune diseases, including autoimmune thyroid disease (AITD). IL-18 is a potent proinflammatory cytokine capable of inducing IFN-gamma production that is associated with the development of type 1 diabetes and AITD. The gene for IL-18 is located near Idd2 and has been reported to be associated with a susceptibility to type 1 diabetes. To test the putative involvement of IL-18 gene polymorphism in predisposition to type 1 diabetes and AITD, we conducted a case-control study in Japanese population. The SNPs at position -607 (C/A) and -137 (G/C) in the promoter region of the IL-18 gene were analyzed by sequence-specific PCR in 74 nondiabetic patients with AITD, 47 type 1 diabetic patients with AITD, and 114 normal controls. There was no significant increase in the genotype and allele frequencies not only in nondiabetic patients with AITD compared with normal controls, but also in type 1 diabetic patients with AITD compared with normal controls. The distribution of IL-18 gene haplotypes was also similar between both patient groups and normal controls. These results suggest that polymorphisms of the IL-18 gene are not associated with a susceptibility to AITD and type 1 diabetes coexistent with AITD in Japanese population.

Epitope analysis of GAD65 autoantibodies in Japanese patients with autoimmune diabetes.

Type 1 diabetes is an organ-specific autoimmune disease characterized by T cell-mediated destruction of pancreatic beta 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). 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, 90% of patients express at least one of these autoantibodies and are classified as type 1A diabetes. Although the majority of patients with type 1 diabetes are young, lean, and ketosis-prone, there are a number of patients with type 1 diabetes initially diagnosed as having type 2 diabetes at disease onset called LADA. These patients with LADA often progress toward an insulin-deficient state within several years after diagnosis. High levels of GAD autoantibodies have a high predictive value for future insulin deficiency in LADA. Further, epitope analysis of GAD65 autoantibodies may be helpful to predict future insulin dependency in LADA patients. In conclusion, Japanese patients with type 1 diabetes are clinically heterogeneous and the determination of immunological features are helpful to clarify the characteristics of the Japanese type 1 diabetic syndrome.

Intracerebroventricular administration of insulin and glucose inhibits the anorectic action of leptin in rats.

Obese individuals with glucose intolerance present with high serum levels of glucose, insulin, and leptin. These substances are potent inhibitors of feeding in the brain. Obese subjects still present with over-feeding despite elevation of the above factors. To elucidate the mechanism of this paradox, the effects of insulin and glucose on the anorectic action of leptin in the hypothalamus were examined. Adult male Sprague-Dawley rats (weighing 285-320 g) were pretreated with intracerebroventricular injection of insulin, glucose, or saline, followed by leptin (7.5 microg) or phosphate-buffered saline (PBS) injection into the third cerebral ventricle (icv). The cumulative food intakes were measured 24 hr after leptin icv. The tyrosine phosphorylation of signal transducer and activator transcription factor 3 (STAT3) in the hypothalamus was determined by Western blotting. In rats pretreated with saline and stimulated with leptin (saline/LEPTIN group), food intake diminished to about 50% of that of the saline/PBS group (P < 0.005). Food intake in the insulin/LEPTIN group was significantly higher compared with the saline/LEPTIN group (P < 0.005) and reached the level seen in the saline/PBS group. Similar data were obtained in glucose pretreatment experiments. Insulin and glucose icv resulted in reduction of leptin-induced STAT3 tyrosine phosphorylation compared with saline. Infusion of insulin and glucose icv did not alter peripheral blood glucose levels in all groups. High insulin or glucose levels in the brain could result in leptin resistance as manifested by food intake, which is probably due to the attenuation of STAT3 phosphorylation downstream the leptin receptor.

Stromal-cell derived factor-1 chemokine gene variant is associated with type 1 diabetes age at onset in Japanese population.

Stromal-cell derived factor-1 (SDF-1) is a powerful chemokine that upregulates T-cell migration and activation. The gene for SDF-1 is located near type 1 diabetes susceptibility locus IDDM10, suggesting a contribution by SDF-1 to the induction of diabetes. Recently the role of SDF-1 gene polymorphism in the clinical presentation of type 1 diabetes in French population has been reported. To test the putative involvement of SDF-1 gene polymorphism in predisposition to or clinical heterogeneity of type 1 diabetes in Japanese population, we conducted the case-control study. The SDF1-3'A variant (801 G to A in the 3'-untranslated region) was determined by the polymerase chain reaction-restriction fragment length polymorphism technique in 184 patients with abrupt-onset type 1 diabetes and 106 healthy control subjects. No significant difference in allele and genotype frequencies of SDF1-3'A variant was found between type 1 diabetic patients and healthy controls. However, the SDF1-3'A variant was strongly associated with early-onset diabetes in a recessive model (AA versus AG + GG, p = 0.017). The mean age-at-onset in patients carrying SDF1-3'AA genotype was significantly younger than that in patients with SDF1-3' AG or GG genotype (p = 0.028). The frequencies of SDF1-3' A variant were significantly increased in HLA-DR4/9 patients compared with non-DR4/9 patients (p = 0.008). These results suggest that the SDF-1 gene polymorphism is associated with the age-at-onset of type 1 diabetes in Japanese population.

Vanadate enhances leptin-induced activation of JAK/STAT pathway in CHO cells.

Leptin, the product of the ob gene, is an adipocyte-derived hormone that plays a key role in the control of food intake and energy expenditure. Leptin acts through receptors that belong to a member of the class I cytokine receptor family. It has been demonstrated that the SH2 domain-containing tyrosine phosphatase 2 (SHP-2) negatively regulates STAT3-mediated transcriptional activation through long form leptin receptor (OBRb). Vanadate has been shown to be a potent and selective inhibitor of PTPase activity in vitro. In this study, we have demonstrated that vanadate increases leptin-induced JAK2 and STAT3 phosphorylation in CHO cells expressing OBRb. The increased leptin-dependent luciferase activity of SOCS3 gene was also seen in vanadate-treated cell. Furthermore, vanadate reversed the inhibitory effects of SOCS3 on leptin-induced STAT3 phosphorylation. The present findings suggest that PTP inhibitors including vanadate and vanadate-derived compounds could be used as a therapeutic agent in the treatment of obesity.

Genetic association between interleukin-10 gene promoter region polymorphisms and type 1 diabetes age-at-onset.

This study investigated whether interleukin-10 (IL-10) gene promoter region polymorphisms are associated with susceptibility to or clinical presentation of type 1 diabetes. The frequency of -1082G/A, -819C/T, and -592C/A polymorphisms was analyzed in 128 Japanese patients with type 1 diabetes and in 107 healthy control subjects in a case-controlled study. The allelic and haplotypic frequencies of the IL-10 gene promoter region polymorphisms were similar in patients with type 1 diabetes and in control subjects. However, the -819T and -592A allele were associated with adult-onset (>18 years) of the disease (p = 0.037). Furthermore, the frequency of ATA haplotype was increased in adult-onset patients than that in early-onset patients (< or =18 years; p = 0.037). Among the genotypes comprising ATA haplotype, the frequency of ATA/ATA was significantly higher in adult-onset patients than in early-onset patients (p = 0.004). These results suggest that the IL-10 gene promoter polymorphisms are associated with the age-at-onset in Japanese patients with type 1 diabetes.