PF4 and interstitial lung disease: SSc-ILD prognostic biomarkers included, in addition to the above biomarkers, surfactant protein-D (SP-D), surfactant protein-A (SP-A), chitinase-3-like protein 1 (YKL-40), matrix metalloproteinases 12 (MMP12), tissue inhibitor of metalloproteinase-1 (TIMP-1), 16-kDa Clara cell secretory protein (CC16), (Tenascin C), C-C motif chemokine ligand 2 and 8 (CCL2 and CCL18), interleukins 6 and 2 (IL-6 and IL-2), C reactive protein (CRP), C-X-C motif chemokine ligand 4 and 10 (CXCL4 and CXCL10), and fractalkine (CX3CL1) (193).