Gut microbiota regulates cardiac ischemic tolerance and aortic stiffness in obesity

Abstract

The gut microbiota has emerged as an important regulator of host physiology, with recent data suggesting a role in modulating cardiovascular health. The present study determined if gut microbial signatures could transfer cardiovascular risk phenotypes between lean and obese mice using cecal microbiota transplantation (CMT). Pooled cecal contents collected from obese leptin-deficient (Ob) mice or C57Bl/6j control (Con) mice were transplanted by oral gavage into cohorts of recipient Ob and Con mice maintained on identical low-fat diets for 8 wk (n = 9-11/group). Cardiovascular pathology was assessed as the degree of arterial stiffness (aortic pulse wave velocity) and myocardial infarct size following a 45/120 min ex vivo global cardiac ischemia-reperfusion protocol. Gut microbiota was characterized by 16S rDNA sequencing, along with measures of intestinal barrier function and cecal short-chain fatty acid (SCFA) composition. Following CMT, the gut microbiota of recipient mice was altered to resemble that of the donors. Ob CMT to Con mice increased arterial stiffness, left ventricular (LV) mass, and myocardial infarct size, which were associated with greater gut permeability and reduced cecal SCFA concentrations. Conversely, Con CMT to Ob mice increased cecal SCFA, reduced LV mass, and attenuated myocardial infarct size, with no effects on gut permeability or arterial stiffness. Collectively, these data demonstrate that obesity-related changes in the gut microbiota, independent of dietary manipulation, regulate hallmark measures of cardiovascular pathology in mice and highlight the potential of microbiota-targeted therapeutics for reducing cardiovascular pathology and risk in obesity.NEW & NOTEWORTHY These data are the first to demonstrate that cecal microbiota transplantation (CMT) can alter cardiovascular pathology in lean and obese mice independent from alterations in dietary intake. Myocardial infarct size was reduced in obese mice receiving lean CMT and worsened in lean mice receiving obese CMT. Lean mice receiving obese CMT also displayed increased aortic stiffness. These changes were accompanied by alterations in short-chain fatty acids and gut permeability.

Keywords: arterial stiffness; cecal transplant; ischemia-reperfusion; microbiota; obesity.

Fig. 1.

Gut permeability and aortic stiffness in donor mice and the effects of antibiotic administration on microbial suppression. Gut permeability was assessed as plasma FITC-dextran concentration 4 h after oral administration (A). Arterial stiffness was measured by in vivo aortic pulse wave velocity (aPWV; B). The effects of an antibiotic cocktail before transplantation on total gut bacteria (C). Con, C57 control mice; Ob, ob/ob mice; Abx, antibiotics; Data were analyzed via t tests and are expressed as means ± SE; n = 5–6/group; *P < 0.05 vs. Con or Pre-Abx.

Fig. 2.

Effects of microbiota transplantation on measures of microbial diversity. Alpha diversity was determined by Chao1 richness (A) and Shannon diversity (B). Nonmetric dimensional scaling (NMSD) biplot of mouse fecal microbial communities colored by recipient group. Distance measurements between samples (beta diversity) was determined at the species level by Bray-Curtis index (C). Con + Con, control mice receiving control microbiota; Con + Ob = control mice receiving obese microbiota; Ob + Con, obese mice receiving control microbiota; Ob + Ob, obese mice receiving obese microbiota. Data are expressed as means ± SE; n = 9–11/group. ^a,b,cP < 0.05, data with different superscript letters are significantly different.

Fig. 3.

Effects of microbiota transplantation on bacterial abundance at the phyla, class, and species level. Relative abundance of fecal bacteria at the phyla (A) and class (B) levels. Relative abundance of fecal Akkermansia muciniphila (C), Bacteroides spp. (D), and Oscillospira spp. (E). Con + Con, control mice receiving control microbiota; Con + Ob, control mice receiving obese microbiota; Ob + Con, obese mice receiving control microbiota; Ob + Ob, obese mice receiving obese microbiota. Data are expressed as means ± SE; n = 9–11/group. ^a,b,cP < 0.05, data with different superscript letters are significantly different.

Fig. 4.

Effects of microbiota transplantation on aortic pulse wave velocity (aPWV). The effects of microbiota transplantation on arterial stiffness as determined by aPWV (A), association of aPWV with Akkermansia muciniphila (B), and aortic collagen content following transplantation (C). Con + Con, control mice receiving control microbiota; Con + Ob, control mice receiving obese microbiota; Ob + Con, obese mice receiving control microbiota; Ob + Ob, obese mice receiving obese microbiota. Data in A and B were analyzed by two-way ANOVA and are expressed as means ± SE; data in B were determined using the Pearson correlation coefficient (B); n = 9–11/group. ^a,b,cP < 0.05, data with different superscript letters are significantly different.

Fig. 5.

Effect of microbiota transplantation on myocardial mass and ischemic tolerance. The effects of microbiota transplantation on whole heart mass (A), left ventricular (LV) mass (B), infarct size (C and D), and coronary flow (E and F). CMT, cecal microbiota transplantation; Adj. AUC, adjusted area under the curve; Con + Con, control mice receiving control microbiota; Con + Ob, control mice receiving obese microbiota; Ob + Con, obese mice receiving control microbiota; Ob + Ob, obese mice receiving obese microbiota. Data were analyzed by two-way ANOVA and are expressed as means ± SE; n = 9–11/group. ^a,b,cP < 0.05, data with different superscript letters are significantly different.

Fig. 6.

Effects of microbiota transplantation on LPS-binding protein (LBP), short-chain fatty acid (SCFA) production and gut permeability. The effects of microbiota transplantation on plasma LBP (A), cecal SCFA concentrations (B), and gut permeability as assessed by plasma FITC-dextran (C). Con + Con, control mice receiving control microbiota; Con + Ob, control mice receiving obese microbiota; Ob + Con, obese mice receiving control microbiota; Ob + Ob, obese mice receiving obese microbiota. Data were analyzed by 2-way ANOVA and are expressed as means ± SE; n = 9–11/group. ^a,b,cP < 0.05, data with different superscript letters are significantly different.