IL17A and rheumatoid arthritis: This requirement of T cell activation has already been described, as membranes from T cells previously activated with leukophytohaemagglutinin and phorbol myristate acetate were able to induce MMP-1 and PGE2 production in dermal and synovial fibroblasts46 and type II collagen stimulated T cells induced the production of IL-17, TNF-α and IL-18 while cocultured with RA synovial fibroblasts.21 Of note, the presence of T cells increased collagen 3 proportion, which is one of the pathological features of tendinopathy and that results in a tendon with inferior biomechanics.1