Oleate protects macrophages from palmitate-induced apoptosis through the downregulation of CD36 expression

In obese patients, free fatty acids ectopically accumulated in non-adipose tissues cause cell death. Saturated fatty acids are more deleterious to non-adipose cells, and supplementation with monounsaturated fatty acids has been proposed to rescue cells from saturated fatty acid-induced cytotoxicity; however, the mechanisms are not well understood. To understand the cytoprotective role of monounsaturated fatty acids in lipotoxic cell death of macrophages, we investigated the antagonizing effect of oleate and the underlying mechanisms in palmitate-treated RAW264.7 cells. Palmitate strongly induced apoptosis in macrophages by increasing CD36 expression, which was identified to mediate both endoplasmic reticulum stress and the generation of reactive oxygen species. Co-treatment with oleate significantly reduced CD36 expression and its downstream signaling pathways of apoptosis in palmitate-treated cells. These findings provide a novel mechanism by which oleate protects macrophages from palmitate-induced lipotoxicity.