Critical amino acid variants in HLA-DRB1 allotypes in the development of Graves' disease and Hashimoto's thyroiditis in the Japanese population.

The effects of amino acid variants encoded by human leukocyte antigen (HLA) class II on the development of Graves' disease (GD) and Hashimoto's thyroiditis (HT) have not been fully elucidated. We investigated the HLA-DRB1 genes of 243 GD patients and 82 HT patients in the Japanese population and compared the frequencies of HLA-DRB1 alleles and HLA-DRB1 amino acid variants between these patients and the Japanese populations previously reported by another institution. The frequencies of HLA-DRB1*04:05 and -DRB1*14:03 alleles were significantly higher and those of HLA-DRB1*01:01 and -DRB1*15:02 alleles were lower in GD patients than in controls. The frequencies of HLA-DRB1*08:03 and -DRB1*09:01 alleles were significantly higher and that of the HLA-DRB1*13:02 allele was lower in HT patients than in controls. A blind association analysis with all amino acid positions identified DRß9 and DRß31 for GD and DRß9, DRß13, and DRß21 for HT. The frequency of Glu-9 was significantly higher and that of Cys-9 was lower in GD patients than in controls. The frequencies of Lys-9 and Phe-13 were significantly higher in HT patients than in controls. DRß9 and DRß13 could be critical amino acid positions in the development of GD and HT.

Dipeptidyl peptidase-4 inhibition prevents nonalcoholic steatohepatitis-associated liver fibrosis and tumor development in mice independently of its anti-diabetic effects.

Nonalcoholic steatohepatitis (NASH) is a hepatic phenotype of the metabolic syndrome, and increases the risk of cirrhosis and hepatocellular carcinoma (HCC). Although increasing evidence points to the therapeutic implications of certain types of anti-diabetic agents in NASH, it remains to be elucidated whether their effects on NASH are independent of their effects on diabetes. Genetically obese melanocortin 4 receptor-deficient (MC4R-KO) mice fed Western diet are a murine model that sequentially develops hepatic steatosis, NASH, and HCC in the presence of obesity and insulin resistance. In this study, we investigated the effect of the dipeptidyl peptidase-4 (DPP-4) inhibitor anagliptin on NASH and HCC development in MC4R-KO mice. Anagliptin treatment effectively prevented inflammation, fibrosis, and carcinogenesis in the liver of MC4R-KO mice. Interestingly, anagliptin only marginally affected body weight, systemic glucose and lipid metabolism, and hepatic steatosis. Histological data and gene expression analysis suggest that anagliptin treatment targets macrophage activation in the liver during the progression from simple steatosis to NASH. As a molecular mechanism underlying anagliptin action, we showed that glucagon-like peptide-1 suppressed proinflammatory and profibrotic phenotypes of macrophages in vitro. This study highlights the glucose metabolism-independent effects of anagliptin on NASH and HCC development.