COL18A1 and systemic sclerosis: The levels of 26 soluble serum factors (including anti-ETAR and anti-AT1R) were analyzed, of which 6 factors were significantly different in SSc-PH patients; Endostatin, sVCAM, and VEGF-D were significantly increased, whereas levels of PF4/CXCL4, sVEGFR2, and PDGF-AB-BB were significantly decreased compared with SSc patients without PH.