Myeloid P2Y2 receptor promotes acute inflammation but is dispensable for chronic high-fat diet-induced metabolic dysfunction

The purinergic receptor P2Y2 binds ATP to control chemotaxis of myeloid cells, and global P2Y2 receptor knockout mice are protected in models of acute inflammation. Chronic inflammation mediated by macrophages and other immune cells in adipose tissue contributes to the development of insulin resistance. Here, we investigate whether mice lacking P2Y2 receptors on myeloid cells are protected against acute and chronic inflammation. Wild-type mice were transplanted with either wild-type or P2Y2 receptor null bone marrow and treated with a sublethal dose of endotoxin as a model of acute inflammation, or fed a high-fat diet to induce obesity and insulin resistance as a model of chronic inflammation. P2Y2^−/− chimeric mice were protected against acute inflammation. However, high-fat diet feeding induced comparable inflammation and insulin resistance in both WT and P2Y2^−/− chimeric mice. Of note, confocal microscopy revealed significantly fewer crown-like structures, assemblies of macrophages around adipocytes, in P2Y2^−/− chimeric mice compared to WT chimeric mice. We conclude that P2Y2 receptors on myeloid cells are important in mediating acute inflammation but are dispensable for the development of whole body insulin resistance in diet-induced obese mice.