Abstract 17293: Hyperglycemia Enhances Pro-Inflammatory Properties of Macrophage-Derived Exosomes to Drive Hematopoiesis in Apolipoprotein E-Deficient Mouse

Abstract

Introduction: Macrophage-derived exosomes have emerged as important mediators in cell-to-cell communication by influencing inflammatory signaling and the immune function. Hypothesis: We aimed to explore whether hyperglycemia can enhance intercellular communication between mature macrophages and hematopoietic progenitors via exosomes to promote inflammation and diabetic atherosclerosis. Methods: Bone marrow derived macrophages (BMDM) from C57BL/6 mice were cultured with normal (5.5 mM) or high glucose concentrations (25 mM). Exosomes were isolated by cushioned-density gradient ultracentrifugation method followed by nanoparticle tracking and western blot analysis. Inflammatory properties of high glucose exosomes (BMDM-HG-exo) or normoglycemic exosomes (BMDM-NG-exo) were tested in vitro by exposing them to naïve BMDM. The capacity for BMDM-derived exosomes to alter systemic and vascular inflammation were next tested by infusing 25-30 weeks-old ApoE -/- mice fed a chow diet with exosomes three times a week, for four weeks. Results: Our data show that BMDM-HG-exo can stimulate the expression of inflammatory cytokines and generate reactive oxygen species in recipient cultured BMDM. Furthermore, our findings show that intraperitoneally injected exosomes distribute to numerous organs and tissues including the bone marrow and the spleen. HG-exo enhance the expansion of multipotent and lineage committed hematopoietic progenitors in the spleen, leading to an enhanced atherosclerotic progression. Conclusions: We identify that exosomes derived from cultured BMDM exposed to high glucose have the capacity to exert inflammatory signaling in vitro , and in vivo. Our findings suggest that exosomes produced by macrophages exposed to hyperglycemia could represent an unsuspected source of inflammation to accelerate atherosclerosis in diabetes.