IL13 and systemic sclerosis: Moreover, the increase in IL-13 mRNA levels induced by TGF-β observed in patients with SSc (Fig. 3c, left panel) was partially reversed in the presence of SIS3, and, conversely, the decrease in IL-13 mRNA levels induced by TGF-β in PBLs from healthy donors and Jurkat T cells was totally reversed (Fig. 3c, right panels).