IL-34 promotes foam cell formation by enhancing CD36 expression through p38 MAPK pathway.

Atherosclerosis is characterized as a chronic inflammatory disease and macrophage-derived foam cells play a central role during the pathologic processes. A newly discovered cytokine interleukin-34 (IL-34) is closely associated with various inflammatory and autoimmune diseases. Expression of IL-34 in obesity, inflammatory bowel disease (IBD), rheumatoid arthritis (RA), lupus nephritis and coronary artery diseases (CAD) are significantly elevated. However, the role of IL-34 in atherosclerosis remains unknown. In our present study, we found that IL-34 treatment markedly increased the uptake of oxLDL, intracellular total and esterified cholesterol content but not cholesterol efflux, subsequently promoted foam cell formation through up-regulating CD36 expression via p38 MAPK signal pathway in bone marrow derived macrophages (BMDMs). Furthermore, treatment with IL-34 significantly elevated the oxLDL-induced up-regulation of pro-inflammatory cytokines. Our results conclude that IL-34 facilitates foam cell formation by increasing CD36-mediated lipid uptake and suggest a potential new risk biomarker for atherosclerosis.