The gut microbiota dysbiosis in ischemic stroke: a systematic review and meta-analysis of microbial diversity and taxonomic alterations.

OBJECTIVE: Clinical and epidemiological evidence suggests a link between gut microbiota and ischemic stroke severity as well as outcomes, yet inconsistent findings and unclear mechanisms underscore the need for a systematic synthesis. METHODS: We systematically reviewed and meta-analyzed observational studies linking gut microbiota to ischemic stroke, following PRISMA guidelines. The search covered PubMed, Embase, and the Cochrane Library, with animal studies and in vitro studies excluded. Two reviewers independently screened the literature, extracted data, and assessed study quality via the Newcastle-Ottawa Scale. We conducted random-effects meta-analyses using RevMan 5.3. Heterogeneity was quantified with the I 2 statistic, and publication bias was assessed. Subgroup analyses were conducted to examine influential factors. RESULTS: From 17,281 initially identified records, 59 studies involving 7,463 patients were included in the final analysis. Although α-diversity measures-including Shannon, Chao1, ACE, Simpson index, and observed species richness-did not differ significantly between ischemic stroke patients and controls (all p > 0.05), subgroup analyses indicated that observed species richness (95% CI [-0.80, -0.13], p = 0.006) was notably altered in patients with cognitive impairment, and the Chao1 index (95% CI [0.01, 0.37], p = 0.04) was significantly changed in those with mood disorders. Microbial composition analysis revealed no significant differences at the phylum level. However, at the family level, stroke patients exhibited a higher abundance of Enterobacteriaceae and lower levels of Lachnospiraceae and Prevotellaceae. At the genus level, these patients exhibited higher levels of Pseudomonas and Streptococcus, along with reduced abundances of Akkermansia, Bacteroides, Coprococcus, and Roseburia. CONCLUSION: Ischemic stroke is characterized by taxonomic gut dysbiosis, whereas a decrease in α-diversity is observed only in patients who also develop cognitive impairment and mood disorders after stroke. Future multi-omics and large cohort studies should establish causality between gut microbiota and ischemic stroke, identifying therapeutic targets. SYSTEMATIC REVIEW REGISTRATION: https://www.crd.york.ac.uk/PROSPERO/view/CRD42024506656, Identifier: CRD42024506656.