IL6 and systemic sclerosis: In the present study, we further investigated the specific role of some critical molecules associated with MSC immunosuppressive properties and hypothesized that MSC defective for interleukine-1 receptor-antagonist (IL1RA), interleukine-6 (IL6) or inducible nitric-oxide (NO)-synthase (iNOS) would be less effective in reducing fibrosis in SSc.