Surprisingly, pretreatment with the neutralizing anti-IL-21 antibody of IFN-γ+IL-17+Th17 cells before incubation with dermal fibroblasts resulted in the downregulation of α-SMA and COL1A1 mRNA, suggesting a contribution from IL-21 in SSc fibrogenesis [34]. This evidence concerns the gene ACTA1 and systemic sclerosis.