Myeloid atg5 deletion impairs n-3 PUFA-mediated atheroprotection

Dietary long-chain (≥20 carbons) n-3 polyunsaturated fatty acids (PUFAs) reduce atherosclerosis and enhance macrophage autophagy activation. How macrophage autophagy impacts atherosclerotic progression, particularly when comparing dietary n-3 PUFA supplementation vs. saturated fat feeding, is unknown. We generated myeloid-specific autophagy-deficient and control mice in the Ldlr−/− background by transplanting bone marrow from myeloid-specific autophagy-related (atg) 5 knockout mice and wild type controls into irradiated Ldlr−/− recipients. After 7 weeks for recovery from radiation, mice were fed an atherogenic diet containing 0.2% cholesterol and 20% calories as palm oil (PO diet), or 10% calories as PO plus 10% calories as fish oil (FO diet) for 16 weeks. Compared to PO, FO significantly reduced plasma cholesterol, triglyceride, hepatic neutral lipid, and aortic caspase-1 cleavage, but increased aortic efferocytosis, leading to attenuated atherosclerosis in Ldlr−/− mice receiving wild type bone marrow. Myeloid atg5 deletion had little impact on plasma lipid concentrations and hepatic neutral lipid content, regardless of diet. Myeloid atg5 deletion increased aortic caspase-1 cleavage, decreased aortic efferocytosis and worsened atherosclerosis only in the FO-fed Ldlr−/− mice. Deficient myeloid autophagy significantly attenuated FO-induced atheroprotection, suggesting that dietary n-3 PUFAs reduce atherosclerosis, in part, by activation of macrophage autophagy. [Display omitted] •Myeloid atg5 deletion worsens atherosclerosis in n-3 PUFA-fed mice.•Myeloid atg5 deletion increases aortic caspase-1 cleavage in n-3 PUFA-fed mice.•Myeloid atg5 deletion decreases aortic efferocytosis in n-3 PUFA-fed mice.