IL6 and pulmonary arterial hypertension: demonstrated that elevated blood concentrations of IL-6 are associated with pulmonary vascular remodeling in patients with PH; IL-6 may be released by PASMCs, serum IL-6 is associated with specific clinical phenotypes and outcomes in patients with PH, and IL-6 may become a potential therapeutic target for early disease diagnostic markers and treatment of PAH, including connective tissue diseases associated PAH (CTD-PAH) (21).