Blockade of α4 Integrin Signaling Ameliorates the Metabolic Consequences of High-Fat Diet–Induced Obesity

OBJECTIVE—Many prevalent diseases of advanced societies, such as obesity-induced type 2 diabetes, are linked to indolent mononuclear cell–dependent inflammation. We previously proposed that blockade of α4 integrin signaling can inhibit inflammation while limiting mechanism-based toxicities of loss of α4 function. Thus, we hypothesized that mice bearing an α4(Y991A) mutation, which blocks signaling, would be protected from development of high-fat diet–induced insulin resistance. RESEARCH DESIGN AND METHODS—Six- to eight-week-old wild-type and α4(Y991A) C57Bl/6 male mice were placed on either a high-fat diet that derived 60% calories from lipids or a chow diet. Metabolic testing was performed after 16–22 weeks of diet. RESULTS—α4(Y991A) mice were protected from development of high-fat diet–induced insulin resistance. This protection was conferred on wild-type mice by α4(Y991A) bone marrow transplantation. In the reverse experiment, wild-type bone marrow renders high-fat diet–fed α4(Y991A) acceptor animals insulin resistant. Furthermore, fat-fed α4(Y991A) mice showed a dramatic reduction of monocyte/macrophages in adipose tissue. This reduction was due to reduced monocyte/macrophage migration rather than reduced monocyte chemoattractant protein-1 production. CONCLUSIONS—α4 integrins contribute to the development of HFD-induced insulin resistance by mediating the trafficking of monocytes into adipose tissue; hence, blockade of α4 integrin signaling can prevent the development of obesity-induced insulin resistance.