The RORγt-CCR6-CCL20 axis augments Th17 cells invasion into the synovia of rheumatoid arthritis patients.

OBJECTIVES: To clarify the pathogenic role of transcription factor expression of CD4 + T helper (Th) cell subsets in the development of rheumatoid arthritis (RA).

METHODS: We collected CD4 + T cells from peripheral blood mononuclear cells (PBMCs) and synovial fluid mononuclear cells (SFMCs) by magnetic cell sorting. The proportion of Th cell subsets were classified from cell surface markers (CD45RA, CXCR5, CXCR3, CCR6) and the expression of their transcription factors (T-bet, GATA3, RORγt) were analyzed by flow cytometry before and at 24 weeks after anti-rheumatic treatment. Chemotaxis assays quantified migratory ability.

RESULTS: The expression of CCR6 and RORγt in Th17 cells from PBMC of RA patients was significantly higher than in healthy control volunteers and osteoarthritis patients. The proportion of Th17 cells in SFMCs of RA patients was significantly higher than that in PBMCs. Chemotaxis assays revealed that the migration index of Th17 cells towards CCL20 was remarkably enhanced in RA patients. The expression of CCR6 and RORγt in Th17 cells at 24 weeks post-therapeutic intervention was significantly decreased compared to before treatment.

CONCLUSION: The high expression of RORγt might facilitate the migration of Th17 cells to inflamed joints via the enhanced expression of CCR6 and contribute to the pathology of RA.