Aims/hypothesis: The aim of this study was to understand the role of CXC chemokine receptor 3 (CXCR3), a T-helper 1(Th1) type chemokine receptor, in the pathogenesis of type 1 diabetes.
Methods: We observed the incidence of diabetes in Cxcr3 homozygous knockout mice. We compared the expression pattern of various cytokines and chemokines and the frequency of FOXP3(+) cells in the pancreas and pancreatic lymph nodes from Cxcr3 ( -/- ) NOD mice and wild-type NOD mice. In addition, we observed the migration ability of CXCR3(+)CD4(+) cells to pancreatic islets upon adoptive transfer. Finally, we examined whether Cxcr3 (+) regulatory T cells (Tregs) actually suppressed the onset of diabetes in vivo.
Results: Cxcr3 ( -/- ) NOD mice developed spontaneous diabetes earlier than did wild-type NOD mice. In Cxcr3 ( -/- ) NOD mice, Tregs were more frequent in pancreatic lymph nodes and less frequent in pancreatic islets than in wild-type NOD mice. While transferred CXCR3(-)CD4(+) cells from wild-type NOD mice did not infiltrate pancreatic islets of NOD-severe combined immunodeficiency (SCID) mice, CXCR3(+)CD4(+) cells from the same mice migrated into the recipient islets and contained Forkhead box P3 (FOXP3) upon adoptive transfer. Moreover, CD4(+)CD25(+) cells from wild-type NOD mice suppressed and delayed the onset of diabetes compared with those from Cxcr3 ( -/- ) NOD mice in a cyclophosphamide-induced diabetes model system.
Conclusions/interpretation: The mechanism of accelerated diabetes onset in Cxcr3 ( -/- ) NOD mice was considered to be due to the lack of hybrid Tregs (CXCR3(+)FOXP3(+)CD4(+) cells), which could effectively migrate into and regulate Th1 inflammation in local lesions under Cxcr3 knockout conditions.