Secreted Phospholipase PLA2G2D Contributes to Metabolic Health by Mobilizing ω3 Polyunsaturated Fatty Acids in WAT

Abstract

Polyunsaturated fatty acids (PUFAs) confer health benefits by preventing inflammation and obesity and by increasing thermogenesis in brown and beige adipocytes. As well as being supplied exogenously as nutrients, PUFAs are largely stored in membrane glycerophospholipids and released by phospholipase A₂s (PLA₂s). However, the molecular identity of the PLA₂ subtype(s) that supplies endogenous PUFAs for metabolic homeostasis remains unclear. Here we show that PLA2G2D, a secreted PLA₂ isoform, is constitutively expressed in M2-type macrophages in white adipose tissue (WAT) and shows a reciprocal correlation with obesity. Studies using global and macrophage-specific Pla2g2d-deficient mice reveal that PLA2G2D increases energy expenditure and thermogenesis by facilitating adipocyte browning, thereby ameliorating diet-induced obesity, insulin resistance, and WAT inflammation. Mechanistically, PLA2G2D constitutively supplies a pool of PUFAs, ω3 in particular, in WAT. Thus, our present findings underscore the contribution of the macrophage-driven PLA2G2D-ω3 PUFA axis to metabolic health.

Keywords: beige adipocyte; inflammation; lipidomics; macrophage; metabolic health; obesity; phospholipase A(2); polyunsaturated fatty acid; thermogenesis.