A new study reveals that the composition of gut bacteria can directly determine the severity of sepsis, with specific microbes priming the immune system to overreact.
Key Findings
- A specific bacterial group worsens sepsis: A study published in Nature Communications on April 30 identified a gut bacterial group, Muribaculaceae, and a member bacterium Sangeribacter muris KT1-3, that can worsen sepsis by excessively sensitizing immune cells.
- Genetically identical mice, different outcomes: Researchers at the Korea Research Institute of Bioscience and Biotechnology (KRIBB) and Chungbuk National University observed that genetically identical mice showed different infection outcomes depending on their gut microbiota composition.
- Hyperinflammation linked to specific bacteria: Mice with enriched Muribaculaceae developed severe hyperinflammatory sepsis after exposure to Acinetobacter baumannii, while those without such enrichment had milder symptoms.
- How the bacteria trigger overreaction: The bacterium produces metabolites that prime immune cells beyond normal activation thresholds, causing exaggerated inflammatory reactions to pathogens.
- Microbiota transplants confirm causality: Fecal microbiota transplantation experiments confirmed that transferring gut microbes from severe-infection mice to resistant mice decreased survival rates, while transferring healthier microbiota improved outcomes.
Implications
- Sepsis severity is not just about the pathogen: The study suggests sepsis severity is determined not only by pathogen virulence but also by gut microbiota composition.
- New strategies for prediction and prevention: These findings may enable microbiome-based strategies for predicting sepsis susceptibility and reducing infection risk through microbiota modulation.
- Relevance for antibiotic-resistant infections: The approach could be particularly relevant for infections caused by antibiotic-resistant bacteria.
Statement from the Lead Investigator
Dr. Hwi-Won Seo, lead investigator, stated: "This study demonstrates that gut microbiota can fundamentally alter the intensity of immune responses and thereby determine infection outcomes. We expect these findings to contribute to the future development of microbiome-based technologies for infection prediction and immune regulation."
Background
- What is sepsis? Sepsis is a severe condition where the body's immune system overreacts to infection, causing widespread inflammation and organ damage.
- About the research team: The Korea Research Institute of Bioscience and Biotechnology (KRIBB) is a government-funded national research institute in South Korea.
- Funding: The research was supported by the Ministry of Science and ICT and KRIBB major research programs.