TNF and systemic sclerosis: Agonists such as TGFβ [3,63,64], PDGF [20,65], IL-4 [66], IL-13 [4,66], IFNα [67], S1P [68], and TNFα [69] are present in the skin, sera, and bronchoalveolar fluid of SSc patients, while cell types such as M2 macrophages [43,45] and TH2 cells [70] have also been described.