In detail, in the smooth muscle cell layer of the MCT-induced PAH rat pulmonary small artery, C3a could promote subsequent inflammasome NLRP3 activation and release proinflammatory cytokines (IL-1β and IL-18) resulting in vascular remodeling and finally pulmonary arteriole obstruction. This evidence concerns the gene NLRP3 and pulmonary arterial hypertension.