Th17 Cells in Immunopathogenesis and treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by the sequestration of various leukocyte subpopulations within both the developing pannus and synovial space. The chronic nature of this disease results in inflammation of multiple joints, with subsequent destruction of the joint cartilage and erosion of bone. Identification of T helper (Th)17 cells led to breaking the dichotomy of the Th1/Th2 axis in immunopathogenesis of autoimmune diseases such as RA, and its experimental model, collagen-induced arthritis (CIA). Th17 cells produce cytokines, including interleukin (IL)-17, IL-6, IL-21, IL-22 and tumor necrosis factor (TNF)-α, with pro-inflammatory effects, which appear to have a role in immunopathogenesis of RA. Regarding the wide ranging production of pro-inflammatory cytokines and chemokines by Th17 cells, it is expected that Th17 cell could be a potent pathogenic factor in disease immunopathophysiology. Thus the identification of effector mechanisms used by Th17 cells in induction of disease lesions may open new prospects for designing a new therapeutic strategy for treatment of RA.

Cytokine expression and the role of Thl7 cells in mice colitis

BACKGROUND/AIMS

To explore the expression and mechanism of Thl7 cells and cytokines in mice model with 2,4,6-trinitrobenzenesulphonic acid (TNBS)-induced inflammatory bowel disease (IBD).

METHODOLOGY

ELISA assay was used to detect the expression of Th17 cytokine IL-17 and Thl cytokines IFN-y in colon tissues. Western blot assay was applied to detect IL-17 expression in peripheral blood mononuclear cells (PBMC), spleen mononuclear cells (SMC), mesenteric lymph node cells and colon tissue of colitic mice. RT-PCR assay was used to detect the effect of anti-IL-17 antibody application on TNF-a, IFN-y and IL-6 mRNA levels in SMCs from colitic mice.

RESULTS

Th17 cytokine IL-17 and Thl cytokines IFN-y were both expressed at high level in TNBS-induced colitic mice. In addition, the expression of Thl7 cytokine appeared earlier than the Thl cytokine. IL-17 levels in SMCs, mesenteric lymph node cells and colon tissue of the disease model group had significant differences compared with normal control group (p<0.01), while the IL-17 level in PBMCs of the disease model group had no significant difference (p>0.05) to control group. After application of 10 ug/mL anti-IL-7 antibody, the TNF-ct, IL-6 and IFN-y mRNA levels in SMCs of the model group showed no significant difference from that of no antibody group (p>0.05).

CONCLUSIONS

Both Th17 cells and Thl cells involved in TNBS-induced IBD and the role of Thl17 cells may be through inducing the secretion of pro-inflammatory cytokines.