TGFB1 and systemic sclerosis: Given that TGF-β1 is a major pro-fibrotic cytokine both in liver and lung fibrosis but also in SSc (Wei et al., 2010; Lafyatis, 2014; Frangogiannis, 2020), we hypothesized that this may lie upstream of Gremlin-1 regulation and thus predicted that TGF-β1 stimulation would lead to elevated Gremlin-1.