Indeed, a recent report found that IL-13 levels were associated with the severity of restrictive lung disease in SSc patients with early disease (19, 31), while IL-33 induces migration of Th2 lymphocytes and enhances Th2 cytokine production, such as IL-4, IL-5, and IL-13 in vitro (6), thus contributing to the production of collagen by fibroblasts (32) and the activation of pro-inflammatory pathways, such as NF-kappaB. This evidence concerns the gene IL4 and systemic sclerosis.