Hematopoietic AMPK β1 reduces mouse adipose tissue macrophage inflammation and insulin resistance in obesity

Individuals who are obese are frequently insulin resistant, putting them at increased risk of developing type 2 diabetes and its associated adverse health conditions. The accumulation in adipose tissue of macrophages in an inflammatory state is a hallmark of obesity-induced insulin resistance. Here, we reveal a role for AMPK beta 1 in protecting macrophages from inflammation under high lipid exposure. Genetic deletion of the AMPK beta 1 subunit in mice (referred to herein as beta 1(-/-) mice) reduced macrophage AMPK activity, acetyl-CoA carboxylase phosphorylation, and mitochondrial content, resulting in reduced rates of fatty acid oxidation. beta 1-/- macrophages displayed increased levels of diacylglycerol and markers of inflammation, effects that were reproduced in WT macrophages by inhibiting fatty acid oxidation and, conversely, prevented by pharmacological activatnon of AMPK beta 1-containing complexes. The effect of AMPK beta 1 loss in macrophages was tested in vivo by transplantation of bone marrow from WT or beta 1(-/-) mice into WT recipients. When challenged with a high-fat diet, mice that received beta 1(-/-) bone marrow displayed enhanced adipose tissue macrophage inflammation and liver insulin resistance compared with animals that received WT bone marrow. Thus, activation of AMPK beta 1 and increasing fatty acid oxidation in macrophages may represent a new therapeutic approach for the treatment of insulin resistance.