Among eight serum cytokines, chemokines, and growth factors (IL-6, IL-8, IL-10, CCL2, CXCL10, CX3CL1, FGF-2, and VEGF), only IL-6 was found to be an independent predictor of the DLco decline in both SSc-ILD and idiopathic pulmonary fibrosis [73]. This evidence concerns the gene CX3CL1 and systemic sclerosis.