Abstract 184: Hyperglycemia Enhances Pro-inflammatory Properties of Macrophage-derived Exosomes to Drive Hematopoiesis in Apolipoprotein E-deficient Mouse

Abstract

Background and Purpose: Diabetes is recognized to enhance the frequency and severity of atherosclerosis and cardiovascular disease. Recent studies have shown that hyperglycemia is associated with enhanced hematopoiesis and macrophage accumulation in atherosclerotic lesions. We explored whether high glucose concentrations 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 (5mM) or high glucose concentrations (25mM). Exosomes were isolated with our cushioned-density gradient ultracentrifugation method followed by nanoparticle tracking and western blot analysis. Pro-inflammatory properties of high glucose exosomes (HGexo) were tested in vitro by exposing them to BMDM cultured in normal low glucose. 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 3 x 10 10 exosomes three times a week, for four weeks. Results: Our data show that HGexo can stimulate the expression of inflammatory cytokines (IL-6, IL-1ß) as well as NADPH oxidases (Nox-1 and Nox-4) in cultured BMDM. Furthermore, our findings show that intraperitoneally injected exosomes distribute to numerous organs and tissues including the bone marrow and the spleen. Lastly, HGexo enhance the expansion of multipotent and lineage committed hematopoietic progenitors. Conclusions: We identify that exosomes derived from cultured BMDM exposed to high glucose have the capacity to exert intercellular communication 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.