Harnessing gut microbiota for brain health: protective role of Hungatella hathewayi for post-mTBI cognitive impairment

Cognitive impairment (CI) following mild traumatic brain injury (mTBI) poses a clinical challenge, with emerging evidence implicating gut microbiota. This study found that mTBI patients who developed CI exhibited decreased Hungatella hathewayi, while those without CI showed an increase. Microbiota transplantation in mTBI rats revealed that higher Hungatella hathewayi levels enriched beneficial, short-chain fatty acid (SCFA) -producing bacteria and reduced harmful ones. Elevated Hungatella hathewayi improved performance in the Morris water maze and novel object recognition tests, indicating enhanced spatial learning and memory. It also reduced gut and brain inflammation, shown by lower TNF-α and IL-6 mRNA expression, and promoted M2 microglia polarization in the peri-lesional cortex. Metabolomics identified increased fecal and serum butyrate, a SCFA with anti-neuroinflammatory properties. Thus, Hungatella hathewayi may mitigate Post-mTBI CI by boosting butyrate production, which alleviates intestinal inflammation, shifts microglia toward the protective M2 phenotype, reduces neuroinflammation, and supports neuroprotection, ultimately lowering CI risk after mTBI. This study was registered with the Chinese Clinical Trial Registry (ChiCTR) on May 31, 2023 (Registration number: ChiCTR2300072000, URL: https://www.chictr.org.cn/showproj.html?proj=197867 ).