IL6 and systemic sclerosis: To our knowledge, our analyses demonstrate for the first time that the tissue PC are not only associated with SSc disease at baseline but may also carry prognostic information to help predict clinical progression, and mechanistically link tissue PC levels to endogenous IL-6 activity—a relationship long suspected based on in vitro and preclinical observations but not previously demonstrated in human disease via a rigorously controlled, double blind randomized clinical trial setting with a selective IL-6 inhibitor.