Resolvin D1 decreases abdominal aortic aneurysm formation by inhibiting NETosis in a mouse model

Abstract

Objectives: Resolvins have been shown to attenuate inflammation, while NETosis, the process of neutrophils releasing neutrophil extracellular traps (NETs), produces increased inflammation. It is hypothesized that treatment of animals with resolvin D1 (RvD1) would reduce abdominal aortic aneurysm (AAA) formation by inhibiting NETosis. Methods: Wild-type (WT) 8–12-week old C57BL/6 male mice (n=47) and apolipoproteinE deficient (ApoE-/) mice (n=20) were used in two models to demonstrate the effects of RvD1 on AAA growth. In the topical elastase AAA model, WT mice were divided into three groups: (1) Deactivated elastase control group: sham surgery was performed using deactivated elastase and mice were intravenously injected with phosphate buffered saline (PBS) once a day until harvest. (2) Elastase group: active elastase was used to induce AAA and mice were injected with PBS daily until harvest. (3) RvD1 treated group: AAA was induced and mice were injected with RvD1 daily until harvest. In the angiotensin II (Ang II) induced AAA model, ApoE−/− mice were fed high fat diet and implanted with osmotic infusion pumps containing Ang II (1000ng/kg/min). The Ang II model was divided into two groups: (1) Ang II control group: Ang II was delivered and mice were injected with PBS daily until harvest. (2) RvD1 treated group: Ang II was delivered and mice were injected with RvD1 daily until harvest. On postoperative days 3, 14, or 28, aortic and blood samples were collected for western blot, histology, cytokine array, enzyme-linked immunosorbent assay, and gelatin zymography after aortic diameter measurement. Results: Day 14 RvD1 treated group demonstrated 42% reduced AAA diameter compared to elastase group (p<0.001). On postoperative day 3, RvD1 treated group showed decreased levels of NETosis markers citrullinated histone H3 (p=0.04) and neutrophil elastase (p=0.002) compared to the Elastase group. Among important cytokines involved in AAA formation, interleukin (IL) 1β was down-regulated (p=0.02), while IL-10, a protective cytokine, was upregulated (p=0.01) in the RvD1 treated group. Active matrix metalloproteinase 2 (MMP2) also decreased in the RvD1 treated group (p= 0.03). The RvD1 treated group in the Ang II AAA model, a second model, demonstrated reduced AAA diameter compared to Ang II control group on day 28 (p<0.046). RvD1 treated group showed decreased levels of citrullinated histone H3 on day 3 (p=0.002). Cytokines INF-γ, IL-1β, CXCL-10, MCP-1, and RANTES were all decreased on day 28 (p<0.05). Conclusion: Resolvin D1-mediated inhibition of NETosis may represent a future medical treatment for the attenuation of AAA growth.

Effects of Omega-3 Fatty Acids on Immune Cells

“…However, Capo et al showed in 2015 that neutrophils extracted from the blood of sportsmen whose diet had been supplemented with DHA and EPA secreted lower amounts of IL-6 upon PMA stimulation [79]. A single report in 2018 investigated the effects of Resolvin D1 on NET production, i.e., in an abdominal aortic aneurysm mouse model Resolvin D1 decreased NET formation [80]. We were not able to find a single report investigating the effect of omega-3 fatty acids on neutrophil degranulation.…”

Time-Dependent Pathological Changes in Hypoperfusion-Induced Abdominal Aortic Aneurysm

“…Changes in these AAA-related factors are consistent with those observed in human AAA [ 27 , 42 , 43 ]. Neutrophil elastase, which is released by activated neutrophils, plays an important role in the development of AAA [ 64 , 65 ]. It reportedly regulates the formation of neutrophil extracellular traps (NETs) [ 66 ], which play a critical role in the neutrophil-mediated development of AAA [ 67 ].…”

Deficiency of immunoglobulin E protects mice from experimental abdominal aortic aneurysms

“…Among the inflammatory cells, neutrophils are among the most abundant cell types and the first cell population recruited to the site of injured aortic wall. 7,8 After infiltration and activation, neutrophils release pro-inflammatory molecules such as interleukin-6 (IL6), neutrophil-associated proteases and extracellular traps (NETs), matrix metalloproteinases (MMP) such as MMP-9, cysteinyl cathepsins, and myeloperoxidase to induce aortic wall inflammation, vascular cell apoptosis, and matrix degradation, [9][10][11][12][13] leading to aortic rupture. Depletion of circulating neutrophils by using anti-neutrophil antibody or targeting neutrophil recruitment required chemokines or adhesion molecules inhibited AAA development in aortic elastase perfusion or peri-aortic calcium phosphate injury-induced mouse AAA models, 7,8,14,15 supporting an important role of neutrophils in AAA formation.…”