Gut Bacterium Worsens Heart Attack Damage by Destroying a Protective Hormone
After a heart attack, a gut microbe called B. acidifaciens blooms and uses its DPP4 enzyme to degrade protective GLP-1, worsening heart injury in mice.
Summary
Restoring blood flow after a heart attack can itself injure heart tissue, a problem called ischemia/reperfusion (I/R) injury. This mouse study points to the gut as a contributor. I/R lowered oxygen and raised lactate in the intestine, which favored growth of Bacteroides acidifaciens. This microbe makes its own dipeptidyl peptidase 4 (BaDPP4), an enzyme that breaks down protective peptides in plasma, including GLP-1, and so worsens cardiac damage. Fecal microbiota transplantation transferred the harmful effect. Daurisoline, a compound that inhibits microbial DPP4, reduced cardiac dysfunction in mice. In patients with acute myocardial infarction, B. acidifaciens abundance and BaDPP4 levels tracked with markers of cardiac damage. The findings outline a gut-heart axis and suggest a possible microbiota-directed cardioprotective strategy, though this remains preclinical and the patient data are correlational.
Detailed Summary
Ischemic heart disease remains a leading cause of death, and restoring blood flow after a heart attack can paradoxically kill additional heart cells. Few treatments target this ischemia/reperfusion (I/R) injury, so new mechanisms and drug targets are valuable.
Researchers used mouse I/R models and fecal microbiota transplantation to ask whether gut bacteria influence cardiac damage. They report that I/R causes intestinal hypoxia and raises luminal lactate. These changes selectively enrich Bacteroides acidifaciens, a gut bacterium.
The bacterium produces its own dipeptidyl peptidase 4 (BaDPP4). According to the abstract, this enzyme degrades cardioprotective peptides in plasma, including GLP-1, and thereby amplifies myocardial injury. Daurisoline, described as a microbial DPP4-specific inhibitor, reduced cardiac dysfunction in mice. In patients with acute myocardial infarction and I/R injury, B. acidifaciens abundance and BaDPP4 levels correlated with clinical markers of cardiac damage.
The work describes a hypoxia-lactate-BaDPP4 pathway linking the injured gut to the heart. It suggests that targeting microbial enzymes, rather than human DPP4 or the host alone, could offer a way to protect the heart during and after infarction. It also fits a broader view that gut microbes shape cardiovascular outcomes through their effects on circulating peptides.
Caveats: only the abstract was available, so details on sample sizes, effect sizes, and controls are unknown. The causal evidence comes from mice, and the human data are correlational. Whether daurisoline is selective, safe, and effective in people has not been shown, and results may not transfer to clinical care without trials.
Key Findings
- I/R-induced intestinal hypoxia and higher luminal lactate selectively enriched Bacteroides acidifaciens in the gut of mice.
- Fecal microbiota transplantation indicated the gut microbiota mediates the worsening of myocardial I/R injury.
- B. acidifaciens produces BaDPP4, which degrades plasma cardioprotective peptides such as GLP-1 and amplifies heart damage.
- Daurisoline, a microbial DPP4-specific inhibitor, mitigated cardiac dysfunction in the mouse model.
- In acute MI patients, B. acidifaciens abundance and BaDPP4 levels correlated with clinical markers of cardiac damage.
Methodology
The study combined murine cardiac I/R models, fecal microbiota transplantation, and pharmacological inhibition of microbial DPP4 with daurisoline. It also analyzed samples from acute myocardial infarction patients with I/R injury, correlating bacterial abundance and BaDPP4 levels with clinical injury markers.
Study Limitations
Only the abstract was reviewed, so sample sizes, statistics, and methodological detail are unavailable. Causal findings come from mouse models, and the human association with cardiac injury markers does not prove causation. Daurisoline's specificity, safety, and efficacy in humans remain untested, and the findings may not generalize across populations or microbiomes.
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