In PAH patients (60) and in PH-LHD rat models (61, 81), IL-6 contributes to PA remodeling by inducing medial wall thickening via SMC proliferation and muscularization of the distal pulmonary arterial tree due to migration of SMCs into precapillary arterioles (60, 61, 81) (Table 2; Figure 2), potentially affecting arterial compliance by increased wall thickening. Here, IL6 is linked to pulmonary arterial hypertension.