Fig. 2

Perivascular inflammation in PH. In PH, perivascular inflammation is a complex process triggered by various factors, including hypoxia, injury, infection, chronic pathological states, and autoimmune reactions. These factors activate a variety of immune cells, including neutrophils, macrophages, mast cells, and T lymphocytes, which drive inflammatory responses and pulmonary vascular remodeling through the secretion of inflammatory factors. Proteases and ROS released by neutrophils may directly damage the vascular endothelium, leading to endothelial dysfunction. Macrophages release pro-inflammatory factors in the early stages of inflammation and may shift to M2 macrophages that secrete anti-inflammatory factors to suppress inflammation in the later stages. Mast cells exacerbate inflammation by secreting vasoactive substances and release proteases that promote vascular remodeling. T lymphocytes play a key role in regulating immune responses, including Th cells and Treg. Th cells promote inflammation and vascular remodeling, while Treg cells inhibit excessive immune responses and inflammation by secreting anti-inflammatory cytokines such as IL-10 and TGF-β, maintaining immune tolerance