P076 Abnormal rock activity in CD4+ T cells upregulates IL-21 production and promotes type 1 diabetes in NOD mice

Abstract

Introduction Aberrant production of IL-21 by CD4 + T cells play important role in the development of type 1 diabetes (T1D) in NOD mice. The pathogenic effects of IL-21 are partly due to its ability to promote the generation of T-helper 17 cells. We previously showed that transcription factor Interferon Regulatory Factor (IRF4) is critical for the production of IL-21 and IL-17. Additionally, we demonstrated that the serine-threonine kinase ROCK2 phosphorylates IRF4 and regulates its ability to control IL-17 and IL-21 production. Methods Purified CD4 + T cells from NOD and control mice were stimulated in vitro in presence or absence of a ROCK inhibitor and ROCK2 activity was assayed by invitro kinase assay. Additionally, production of IL-21 and IL-17 was measured in the culture supernatant by ELISA. NOD mice were fed ROCK inhibitor (Fasudil) in drinking water starting 10 weeks of age and evaluated for the development of diabetes over a period of 12 weeks. Results Here we report that CD4 + T cells from NOD mice have hyper-active ROCK2. Consequently, ROCK inhibition corrects the aberrant IRF4 function in these cells and diminishes the level of IL-21 and IL-17. Importantly, in vivo administration of a ROCK inhibitor (Fasudil) ameliorates disease development in NOD mice. Conclusion These studies thus support the idea that ROCK2 is inappropriately activated in NOD CD4 + T cells and that inhibition of ROCK kinases could represent worthwhile therapeutic targets for the treatment of T1D.