IL17A and rheumatoid arthritis: On the other hand, the in vitro studies revealed a reduction of Th1/Th17 phenotype CD4+ T lymphocyte expansion, pro-inflammatory cytokines (IL-1β, IL-6, IFN-γ and IL-17) and MMP-1/3 production in the knee joint tissue and RA synovial fibroblasts, through the downregulation of IKKα/β, ΙκBα and NF-κB [88].