S100A9 and endothelial dysfunction: Our group have previously shown that various immune cells and inflammatory factors, including IL‐17, IL‐33, Th17 cells, and macrophages, are involved in endothelial dysfunction and vascular remodeling of PH.[11, 12, 13] Furthermore, our analysis of transcriptomic and proteomic data showed that the common differentially expressed genes and proteins were primarily focused on inflammation‐ and immunity‐related molecules, in which S100A9 is one of the most significantly expressed molecules among them.