Propionate Alleviates Abdominal Aortic Aneurysm by Modulating Colonic Regulatory T-Cell Expansion and Recirculation

JACC Basic Transl Sci. 2022 Aug 31;7(9):934-947. doi: 10.1016/j.jacbts.2022.05.001. eCollection 2022 Sep.

Abstract

Emerging evidence supports that intestinal microbial metabolite short-chain fatty acids (SCFAs) increase the pool of regulatory T cells (Tregs) in the colonic lamina propria (cLP) and protect against nonintestinal inflammatory diseases, such as atherosclerosis and post-infarction myocardial inflammation. However, whether and how SCFAs protect the inflamed aortas of subjects with abdominal aortic aneurysm (AAA) remains unclear. Here, the authors revealed the protective effect of SCFAs on AAA in mice and the expansion of Tregs in the cLP, and propionate exerted Treg-dependent protection against AAA by promoting the recirculation of cLP-Tregs through colonic draining lymph nodes (dLNs) to the inflamed aorta.

Keywords: AAA, abdominal aortic aneurysm; ANOVA, analysis of variance; CCR, C-C chemokine receptor; DEREG, depletion of regulatory T cell; DT, diphtheria toxin; EVG, Elastica van Gieson; IgG, immunoglobulin G; MMP, matrix metalloproteinase; PBS, phosphate-buffered saline; SCFA, short-chain fatty acid; SI-LP, small intestinal lamina propria; SPF, specific pathogen-free; Treg, regulatory T cell; abdominal aortic aneurysm; cLP, colonic lamina propria; colonic regulatory T cell; dLN, draining lymph node; phC, photoconversion; propionate; recirculation; short-chain fatty acids.