Objectives: To explore roles of NKG2D in interactions of CD4 + T cells and dendritic cells (DCs) in juvenile idiopathic arthritis (JIA) patients Methods: Peripheral blood from active JIA patients and healthy controls were used for flow cytometry assessments of NKG2D +CD4 + T cells and expressions of MICA and MICB on DCs. NKG2D genetically modified CD4 + T cells resulted from transfection with lentiviral vectors harboring NKG2D and NKG2D siRNA. ELISA measured supernatant cytokines in co-cultured CD4 + T cells and DCs. CD4 + T cell subgroups, MICA and MICB expression on DCs was determined by flow cytometry and transcription factors by real-time PCR. Results: All JIA patients had significantly higher content of CD4 +NKG2D + T cells compared to healthy controls (P < 0.01). Expression of NKG2D on CD4 + T cells, and MICA and MICB on DCs were significantly greater in articular JIA than systemic JIA (P < 0.05). NKG2D induced IL-12 and suppressed IL-10 and TGF-β from CD4 + T cells, increased IFN-γ + CD4+ T and IL-17 + CD4 + T cells, RORc and T-bet, but reduced CD25 + Foxp3 + CD4 + T cells, IL-4 + CD4 + T cells, Foxp3, and GATA3 in JIA patients (P<0.05). NKG2D increased IL-12 and T-bet by CD4 + T cells in healthy controls (P<0.05). NKG2D decreased IL-10 and increased CD83, MICA, and MICB of DCs via interaction with CD4 + T cells in JIA and control patients (P<0.05). Conclusions: NKG2D regulates differentiation of CD4 + T cells directly and the maturation of DCs indirectly. Targeting NKG2D may be a potential therapy for JIA.

Background: TYK2 deficiency is a rare Primary immunodeficiency disease caused by loss of function mutations of TYK2 gene, which is initially proposed as a subset of Hyper IgE syndrome (HIES). However, accumulating evidence suggest TYK2 deficient patients do not necessarily present with HIES characteristics, indicating a vacuum of knowledge on the exact roles of TYK2 in human immune system. Method: Pathogenic effects of patients were confirmed by qRT-PCR, western blot and protein stability assays. The responses to cytokines including IFN-α/β/γ, IL-6, IL-10, IL12 and IL-23 of peripheral blood mononuclear cells (PBMCs) from these patients were detected by western blot, qRT-PCR and flow cytometry. The differentiation of T and B cells were detected by flow cytometry. Results: We describe five more TYK2 deficient cases presenting with or without hyper IgE levels, atopy and distinct pathogen infection profile, which are caused by novel TYK2 mutations. These mutations were all found by high throughout sequencing and confirmed by Sanger sequencing. The patients showed heterogenous responses to various cytokine treatments, including IFN-α/β/γ, IL-6, IL-10, IL12 and IL-23. The homeostasis of lymphocytes is also disrupted. Conclusion: Based on our findings, we propose that TYK2 works as a multi-tasker in orchestrating various cytokines signaling pathways, differentially combined defects of which account for the expressed clinical manifestations.