Previous studies reported that enhancement of parasympathetic activity significantly alleviated pulmonary perivascular inflammation and reversed pulmonary artery remodeling by down-regulating the levels of the proinflammatory cytokines IL-6, IL-1b, TNF-α, and MCP-1 in the lung tissue of rats with MCT-induced PAH (14, 15). Here, CCL2 is linked to pulmonary arterial hypertension.