Abstract 19: Deletion of Myeloid GSK3α Attenuates Atherosclerosis and Promotes an M2 Macrophage Phenotype

Objective: Glycogen synthase kinase (GSK)-3α/β has been implicated in the pathogenesis of diseases including diabetes, cancer, Alzheimer’s and atherosclerosis. The tissue and homolog specific functions of GSK3α and β in atherosclerosis are unknown. This study examines the effect of hepatocyte or myeloid cell specific deletion of GSK3α or GSK3β on atherosclerosis in LDLR-/- mice. Approach and results: We ablated GSK3α or GSK3β expression in hepatic or myeloid cells of LDLR-/- mice and mice were fed a high fat diet for 10 weeks. GSK3α or GSK3β deficiency in hepatic or myeloid cells did not affect metabolic parameters, including plasma lipid levels. Hepatic deletion of GSK3α or GSK3β did not affect the development of atherosclerosis or hepatic lipid content. Myeloid deletion of GSK3α, but not GSK3β, reduced atherosclerotic lesion volume as well as lesion complexity. Mice lacking GSK3α in myeloid cells had a less inflammatory and more anti-inflammatory plasma cytokine profile. Macrophages within atherosclerotic lesions of myeloid GSK3α deficient mice, but not GSK3β deficient mice, displayed reduced expression of markers associated with M1 macrophage polarization and enhanced expression of the M2 markers. Finally, bone marrow derived macrophages were isolated and differentiated into classical M1 macrophages or alternative M2 macrophages in vitro. GSK3α deletion, but not GSK3β deletion, attenuated the expression of genes associated with M1 polarization while promoting the expression of genes associated with M2 polarization. Mechanistically, GSK3α regulated macrophage polarization by modulating the phosphorylation and activation of STAT transcription factors. Conclusions: Our findings suggest that deletion of myeloid GSK3α attenuates the progression of atherosclerosis by regulating STAT activation and promoting an M2 macrophage phenotype.