Fig. 2.

The main pathological changes of pulmonary artery (PA) during endoplasmic reticulum (ER) stress reaction. ER stress can be induced by multiple adverse physiologic conditions. When ER stress occurs, ECs and SMCs in the PA play an extremely important role. In addition to hypertrophy, hyperplasia and apoptosis resistance, PASMCs also release inflammatory mediators. PAECs are in a dysfunctional state: in the early stage of PH, apoptosis of ECs increased, and in the later period, excessive proliferation occurred. These pathological processes will lead to the generation of microthrombi, persistent pulmonary vasoconstriction, and pulmonary vascular remodeling, eventually leading to PH and even death. PASMCs: pulmonary artery smooth muscle cells; PAECs: pulmonary artery endothelial cells.