Objective:

To compare gut and oral microbiome profiles in patients with acute ischemic stroke (AIS) versus healthy controls, and to identify specific microbial patterns and predicted functional changes associated with AIS.

Background:

Although the microbiome has been implicated in metabolic and cardiovascular diseases, its role in AIS remains underexplored. As immune and inflammatory processes are central to stroke pathophysiology, microbiome alterations may play a contributing role. Clarifying these changes may reveal novel therapeutic targets.

Design/Methods:

Fifty-four AIS patients were enrolled, and stool and saliva samples were collected within one week of admission. Saliva was obtained via self-expectoration (n=44) or oral swab (n=10). Forty healthy controls with no cerebrovascular disease and normal brain MRI/MRA within the past year were included. Microbial DNA was extracted and analyzed using 16S rRNA gene sequencing. Diversity and taxonomic profiles were evaluated using QIIME 2, and with Linear discriminant analysis Effect Size (LEfSe) was used for differential abundance and predicted functional analysis.

Results:

AIS patients demonstrated significantly higher alpha diversity in stool samples compared to controls (p=0.001), indicating increased microbial richness. Saliva samples, however, showed decreased microbial richness in AIS (p=0.024). Beta diversity analysis revealed distinct microbial community structures between AIS patients and controls, especially at the genus level in stool (p=0.001). LEfSe analysis identified several bacterial taxa enriched in AIS patients' stool, while saliva samples from AIS patients exhibited a higher number of depleted taxa. Notably, the AIS microbiome showed reduced functional capabilities related to beneficial metabolic processes including Proteobacteria, Gammaproteobacteria, Enterobacteriaceae, and Shigella, etc. These findings highlight a potential link between microbiome dysbiosis and the pathophysiology of AIS.

Conclusions:

AIS patients demonstrate significant gut and oral microbiome dysbiosis, with altered diversity, taxonomic composition, and functional potential. These findings support a possible mechanistic role for the microbiome in AIS and its utility as a biomarker or therapeutic target.