Intestinal microbiota determine severity of myocardial infarction in rats

Abstract

Signals from the intestinal microbiota are important for normal host physiology; alteration of the microbiota (dysbiosis) is associated with multiple disease states. We determined the effect of antibiotic-induced intestinal dysbiosis on circulating cytokine levels and severity of ischemia/reperfusion injury in the heart. Treatment of Dahl S rats with a minimally absorbed antibiotic vancomycin, in the drinking water, decreased circulating leptin levels by 38%, resulted in smaller myocardial infarcts (27% reduction), and improved recovery of postischemic mechanical function (35%) as compared with untreated controls. Vancomycin altered the abundance of intestinal bacteria and fungi, measured by 16S and 18S ribosomal DNA quantity. Pretreatment with leptin (0.12 μg/kg i.v.) 24 h before ischemia/reperfusion abolished cardioprotection produced by vancomycin treatment. Dahl S rats fed the commercially available probiotic product Goodbelly, which contains the leptin-suppressing bacteria Lactobacillus plantarum 299v, also resulted in decreased circulating leptin levels by 41%, smaller myocardial infarcts (29% reduction), and greater recovery of postischemic mechanical function (23%). Pretreatment with leptin (0.12 μg/kg i.v.) abolished cardioprotection produced by Goodbelly. This proof-of-concept study is the first to identify a mechanistic link between changes in intestinal microbiota and myocardial infarction and demonstrates that a probiotic supplement can reduce myocardial infarct size.

Figures

Figure 1.

Microbial populations in the feces of vancomycin-treated rats. Vancomycin administered orally (60 mg/kg/d) by addition to the drinking water altered abundance of microbial species present in feces and reduced total microbial numbers. The x-axis labels represent 3 microbial taxa, bacteria (black), fungi (green), and archaea (red). L. plantarum is part of the Bacilli class of bacteria. ND, not detected. Data are means ± sd; n = 6/group. *P < 0.01 vs. d 0.

Figure 2.

Antibiotic administration and myocardial infarction. A) Vancomycin added to the drinking water (60 mg/kg/d) reduced IS in vivo. B) Antibiotic added directly to the coronary circulation of isolated hearts did not reduce IS in vitro. C) Antibiotic added to the drinking water (60 mg/kg/d) and then excluded from the coronary circulation of isolated hearts reduced IS. Data are means ± sd; n = 6/group. LV, left ventricle. Reduction in IS was similar for in vitro and in vivo studies (A, C). *P < 0.01 vs. control.

Figure 3.

Vancomycin treatment confers cardioprotection within 48 h, and the effect is lost by 72 h after cessation of treatment. Vancomycin was added to the drinking water (60 mg/kg/d) before heart excision for ischemia/reperfusion studies. Food and (vancomycin) water were fed ad libitum to all rats. Data are means ± sd; n = 4. *P < 0.05 vs. control.

Figure 4.

Intestinal microbiota mediate cardioprotection via leptin. A) Quantified changes in 11 of 23 cytokines. B) Leptin reconstitution reversed cardioprotection by vancomycin. Rats were treated with leptin (0.12 μg/kg i.v.) at 24 and 12 h before myocardial ischemia/reperfusion. Data are means ± sd; n = 6/group. *P < 0.05 vs. control.

Figure 5.

Goodbelly juice decreased leptin and protected against myocardial infarction. Dahl S rats were treated with Goodbelly (15 ml/rat/d) for 14 d before blood leptin analysis and myocardial ischemia/reperfusion. A) Goodbelly reduced myocardial infarction that was reversed by leptin reconstitution (0.12 μg/kg at 24 and 12 h before ischemia). B) Leptin levels in blood were decreased following Goodbelly treatment. C) L. plantarum levels increased in feces of Goodbelly-treated rats using quantitative PCR of 16S rRNA. Limit of detection for L. plantarum is 3 log10/g feces. Data are means ± sd; n = 6/group. *P < 0.01 vs. control.

Figure 6.

Goodbelly treatment protected against myocardial infarction and decreased leptin levels. Dahl S rats were treated with either Goodbelly (15 ml/rat/d, ∼1.5×109 L. plantarum/rat/d), irradiated (35 kGy) Goodbelly, or vehicle (water, 92.8 mg/ml glucose, 42.2 μg/ml NaCl, 464 μg/ml KCl, and 4 mg albumin) for 14 d or injected with 0.12 μg/kg leptin at 24 and 12 h, or both, before heart excision for ischemia/reperfusion studies. A) IS of the hearts of treated rats. B) Blood plasma of rats in A was collected immediately before ischemia/reperfusion and analyzed for leptin levels. Data are means ± sd; n = 6. *P < 0.02, +P < 0.01 vs. control.