HILPDA uncouples lipid storage in adipose tissue macrophages from inflammation and metabolic dysregulation

Obesity promotes accumulation of lipid-laden macrophages in adipose tissue. Here, we determined the role of macrophage lipid accumulation in the development of obesity-induced adipose tissue inflammation, using mice with myeloid-specific deficiency of the lipid-inducible HILPDA protein. HILPDA deficiency in bone marrow-derived macrophages markedly reduced intracellular lipid levels and accumulation of fluorescently-labeled fatty acids in lipid droplets. Decreased lipid storage in HILPDA-deficient macrophages could be almost completely rescued by inhibition of adipose triglyceride lipase (ATGL) and was associated with increased oxidative metabolism. In diet-induced obese mice, HILPDA deficiency did not alter inflammatory or metabolic parameters, despite markedly reducing lipid storage in adipose tissue macrophages. Our data indicate that HILPDA is a lipid-induced physiological inhibitor of ATGL-mediated lipolysis that uncouples lipid storage in adipose tissue macrophages from inflammation and metabolic dysregulation. Overall, our data question the importance of lipid storage in adipose tissue macrophages in obesity-induced inflammation and metabolic dysregulation.