Upregulation of IL-32γ in endothelial cells promotes macrophage recruitment and inflammatory progression in atherosclerosis.

Atherosclerosis is characterized by chronic vascular inflammation involving endothelial dysfunction and macrophage-mediated inflammatory responses. However, the molecular mechanisms linking these processes remain incompletely understood. This study investigates the role of interleukin-32γ (IL-32γ) in mediating endothelial-macrophage interactions during atherosclerosis progression. IL-32 isoform expression was analyzed in peripheral blood samples from atherosclerosis patients and healthy controls. Human endothelial cells were treated with oxidized low-density lipoprotein (Ox-LDL) with or without NF-κB inhibitor. Endothelial-macrophage interactions were studied using Transwell co-culture systems with THP-1-derived macrophages. Macrophage polarization was assessed by flow cytometry, qRT-PCR, and ELISA. The direct effects of IL-32γ were evaluated using recombinant protein with or without p38 MAPK inhibitor. In vivo studies employed ApoE-/- mice fed a Western diet and administered with IL-32γ alone or with p38 inhibitor. IL-32γ was significantly upregulated in atherosclerosis patients. Ox-LDL induced IL-32γ expression in endothelial cells through NF-κB activation, concurrent with endothelial dysfunction. Ox-LDL-treated endothelial cells promoted M1 macrophage polarization and migration, effects attenuated by either NF-κB inhibition or IL-32γ neutralization. Treatment with recombinant IL-32γ induced M1 polarization through p38 MAPK signaling. In ApoE-/- mouse model, IL-32γ administration accelerated atherosclerotic plaque formation and macrophage infiltration, while p38 inhibition reversed these effects. IL-32γ serves as a crucial mediator between Ox-LDL-induced endothelial dysfunction and macrophage-mediated inflammatory responses in atherosclerosis. Endothelial-derived IL-32γ promotes M1 macrophage polarization through p38 MAPK signaling, accelerating disease progression. These findings identify IL-32γ as a potential therapeutic target for atherosclerotic cardiovascular disease.