This role of M1 macrophages has been further confirmed in hypoxia-induced PAH animal models, where they serve as major sources of inflammatory chemokines, particularly C-C Motif Chemokine Ligand 2(CCL2) and C-X-C Motif Chemokine Ligand 10(CXCL10). This evidence concerns the gene CCL2 and pulmonary arterial hypertension.