A healthy gut microbiome may play a crucial role in protecting against severe sepsis, according to new research linking specific gut bacteria to enhanced inflammatory responses.
Sepsis, a potentially life-threatening condition, may be more prevalent in certain individuals due to underlying issues in the gut. Researchers from the Korea Research Institute of Bioscience and Biotechnology’s Infectious Disease Research Center conducted a study using female mouse models to explore the varying outcomes of sepsis among genetically similar subjects with differing gut microbiomes. The findings were published in the journal Nature.
In their study, the researchers infected the mice with Acinetobacter baumannii, a resilient bacterium known to cause sepsis. They compared groups of mice that exhibited higher and lower survival rates, focusing on differences in their gut microbiomes, bacterial concentrations in their blood and organs, and other cellular markers.
The results revealed that while some mice shared genetic similarities, those with poorer survival rates had a significantly higher concentration of Muribaculaceae bacteria in their gut. Specifically, these bacteria constituted approximately 28% of the microbiome in mice with lower survival rates, compared to just 0.15% in those that survived better.
Additionally, the mice that fared worse exhibited an early and pronounced inflammatory response, which subsequently led to increased bacterial presence in their blood, lungs, and spleen. This suggests that the composition of the microbiome may influence the immune system’s reactivity, according to the researchers.
Among the findings, one strain of bacteria, Sangeribacter muris KT1-3, was notably prevalent in the microbiomes of mice with poorer survival outcomes. When housed with KT1-3 mice, those that typically survived at higher rates experienced a dramatic drop in survival, plummeting to just 10%. This particular strain appeared to exacerbate inflammation during infections, thereby intensifying the severity of sepsis.
These insights indicate that the gut microbiome may provide critical signals regarding the immune system’s potential reaction prior to an infection. Dr. Andrew Fleming, section chief of Infectious Diseases & Immunology at NYU Langone Hospital, Brooklyn, noted that it has been “known for years” that gut bacteria and their toxins can enter the bloodstream during sepsis, worsening the inflammatory response to the initial infection.
Dr. Fleming, who was not involved in the study, explained that this process is particularly significant in cases of septic shock, where the intestinal wall becomes more permeable, allowing bacterial products to leak into the bloodstream. He described the interactions between the gut microbiome and the immune system as “complex and variable from person to person.”
However, he emphasized that there is increasing evidence that a diverse and healthy gut microbiome can offer protective benefits against severe sepsis. Conversely, a dysregulated microbiome, such as one significantly altered by antibiotics, can impair or exacerbate the immune response during sepsis.
Dr. Fleming likened the gut microbiome to a “living organ,” akin to the heart, kidneys, or liver, each serving multiple functions to maintain overall health. He pointed out that an unhealthy microbiome can have detrimental effects across various health issues, including the body’s response to infections.
Despite the importance of gut health, Dr. Fleming noted that there are currently fewer readily available tests to assess microbiome health compared to other organs. He urged individuals to consider their gut microbiome and take steps to maintain its health.
Antibiotic use poses significant challenges to microbiome diversity. Dr. Fleming highlighted that up to 80% of adults in the U.S. receive antibiotic prescriptions annually, with an estimated 30% deemed unnecessary, according to the CDC. He warned that antibiotics can deplete microbiome diversity, creating opportunities for harmful bacteria from the environment to thrive.
He stressed the need for a more critical approach to antibiotic use to preserve gut health and mitigate the spread of antibiotic resistance. While the study’s findings provide an intriguing foundation for further research, Dr. Fleming acknowledged some limitations. For instance, Sangeribacter muris is not typically found in humans, making it challenging to directly extrapolate the study’s findings to human subjects.
Dr. Fleming advocated for well-designed clinical trials to investigate how similar gut microbiome effects may manifest in sepsis among humans. Despite the limitations, he supports the hypothesis that maintaining a healthy gut microbiome can help regulate the immune system and reduce the risk of severe sepsis, according to Fox News.