Abstract
AIMS/INTRODUCTION: Linagliptin is a selective dipeptidyl peptidase (DPP)-4 inhibitor capable of successfully regulating blood glucose levels. The cardiovascular protective effects of several DPP-4 inhibitors have been shown in preclinical studies; however, the detailed influence of DPP-4 inhibitors on diabetic pathological alterations in cardiac tissue has not yet been elucidated. MATERIALS AND METHODS: We combined laboratory-based experiments and bioinformatics techniques to identify suitable candidate targets with significant biological pathways. Mice with streptozotocin-induced insulin deficiency diabetic model were utilized for in vivo experiments. Mice were euthanized at 24 weeks after the induction of diabetes; linagliptin intervention was carried out for 4 weeks before euthanasia. Microarray analysis of heart samples was carried out. RESULTS: Mice with streptozotocin-induced diabetes, but not control mice, showed cardiac fibrosis with an endothelial-mesenchymal transition program, and myocardial fiber and sarcomere disruption; linagliptin alleviated these diabetes-associated pathological alterations without altering blood glucose levels. Bioinformatics analysis utilizing a microarray dataset identified 10 hub genes that were confirmed to have human disease relevance by Gene Expression Omnibus analysis. Among these hub genes, we focused on the Sox9-necroptosis axis as a therapeutic target in diabetic hearts. Indeed, diabetic mice showed the induction of necroptosis-associated genes and the phosphorylation of RIP3 and mixed lineage kinase domain-like protein. CONCLUSIONS: Linagliptin showed excellent heart protection in mice with streptozotocin-induced diabetes associated with alterations in human disease-relevant hub genes. Further investigation is required to determine why DPP-4 inhibitors do not show similar superior organ-protective effects in the clinical setting.