IL4 and systemic sclerosis: There is an extensive amount of literature (mainly adult studies) supporting a TH2 cellular and associated cytokine predominance in SSc, with peripheral blood and tissue derived IL-4 and IL-13, and more recently identified TH2 associated cytokines, IL-33, IL-34, and IL-35 (62, 63), correlating with the degree of skin and lung fibrosis and disease burden (50, 51, 57, 64–67).