A groundbreaking study by researchers at Florida State University’s Gut Biome Lab has revealed a possible link between an infection caused by gut bacteria and the progression of Alzheimer’s disease.
The research showed that the bacteria Klebsiella pneumoniae -; a common bacterium notorious for causing hospital-acquired infections -; can migrate from the intestines to the bloodstream and ultimately to the brain. This bacterial invasion can lead to increased inflammation in the brain and impair cognitive functions, similar to symptoms seen in Alzheimer’s patients. The work has been published in The Journal of Infectious Diseases.
Hospital admissions and intensive care unit stays, combined with antibiotic exposure, can lead to a further decrease in microbiome diversity, placing older adults at high risk not only for digestive problems, but also for extra-intestinal pathologies such as neurodegenerative disorders due to a dysregulation of the gut-brain. ash.”
Ravinder Nagpal, assistant professor in the FSU College of Education, Health, and Human Sciences and director of the Gut Biome Lab
The study is the first to demonstrate a direct link between the two K. pneumonia infection and the pathology of Alzheimer’s, fueling the emerging field investigating how infectious agents can cause or exacerbate Alzheimer’s disease. It also paves the way for future research into the treatment of harmful infectious agents in vulnerable populations, such as the elderly or people recovering from sepsis.
The research shows that when antibiotics disrupt the intestines, this can lead not only to problems in the intestines, but also to the brain. Using a preclinical mouse model, researchers showed that antibiotic exposure affects the diversity of gut bacteria and causes an imbalance in the microbiome, which promotes bacterial proliferation. K. pneumonia by creating a favorable niche.
When this happens, K. pneumonia can enter the bloodstream from the intestines by passing through the intestinal wall and ultimately reaching the brain, triggering neuroinflammation and neurocognitive disorders.
The findings highlight the potential risk posed by hospital-acquired infections K. pneumonia may play a role in the development of neurodegenerative diseases.
“Nosocomial and septic infections are among the risk factors that may increase the predisposition to future neuroinflammatory and neurocognitive disorders, especially in older adults,” Nagpal said.
The study highlights the need for innovative therapeutic approaches to combat the rising prevalence of Alzheimer’s disease, in addition to existing amyloid and tau protein therapies. Further research could provide insight into preventive strategies aimed at controlling hospital-acquired pathogens and maintaining cognitive health in aging populations.
The research was funded by the Infectious Diseases Society of America and the Florida Department of Health.
The article was co-authored by graduate researchers Ian Park, Saurabh Kadyan, and Nathaniel Hochuli of the FSU College of Education, Health, and Human Sciences. Other contributors included Hazel K. Stiebeling, Gloria Salazar Professor; Associate Professor of Psychology and Neuroscience Aaron Wilber; University of Florida researchers Orlando Laitano, Paramita Chakrabarty and Philip A. Efron; and Wake Forest University School of Medicine Associate Professor M. Ammar Zafar.
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Magazine reference:
Park, G., et al. (2024). An enteric bacterial infection causes neuroinflammation and neurobehavioral disorders in 3xTg-AD transgenic mice. The Journal of Infectious Diseases. doi.org/10.1093/infdis/jiae165.