Abstract 492: Resolvin D2 Inhibits Murine Abdominal Aortic Aneurysm and Increases M2 Macrophage Differentiation

Abstract

Objectives: Macrophages are critical to abdominal aortic aneurysm (AAA) formation; however, the role of anti-inflammatory M2 macrophages is not known. Resolvins have been shown to play a protective role in neointimal hyperplasia; however, their role in AAA has not been established. We hypothesized that treatment with Resolvin D2 (RvD2) attenuates murine AAA formation through alterations in macrophage polarization and cytokine expression. Methods: Male C57/B6 mice (n=9/group) of 8-12 weeks of age received RvD2 (100 ng/kg/treatment) or vehicle only every third day beginning three days prior to abdominal aortic perfusion with elastase. Aortas were harvested 14 days following elastase perfusion. Cytokine analysis (n=5/group) or confocal microscopy (n=4/group) was performed. Cytokine profiles were analyzed using a murine antibody array. To determine the effect of RvD2 on macrophage polarization, confocal staining for macrophages (Mac2), M1 (MCP-1) and M2 (Arg-1) macrophage subtypes, α-actin and 4',6-diamidino-2-phenylindole (DAPI) was utilized. Results: Mean aortic dilation was 96.23 % (± 13.07 %) for vehicle treated and 56.58% (± 9.69%) for RvD2 treated mice (p<0.0001). Pro-inflammatory cytokines CXCL-10, IL-1β, TIMP-1 and MCP-1 were significantly elevated in control as compared to RvD2 treated animals. Confocal histology demonstrated a prevalence of M2 macrophages within the aortic media in mice treated with RvD2 (Figure 1). Conclusions: Resolvin D2 exhibits a potent protective effect against experimental AAA formation. Treatment with RvD2 significantly influences macrophage polarization and decreases several important pro-inflammatory cytokines. Resolvins and the alteration of macrophage polarization represent potential future targets for prevention of AAA.