Analysis of gut microbiota characteristics in osteoarthritis patients.

OBJECTIVE: Osteoarthritis (OA) is a chronic and debilitating disease that represents a leading cause of disability among middle-aged and elderly individuals. With the aging population, the incidence of OA and its associated socioeconomic burden is increasing; however, the underlying pathogenesis remains unclear. Based on the "gut-bone axis" theory, this study systematically characterized the gut microbiota of patients with OA to identify potential biological targets for clinical diagnosis and treatment. METHODS: Fecal samples from 32 OA patients and 26 healthy controls were analyzed for gut bacterial and fungal microbiota using 16S rRNA and ITS high-throughput sequencing. ELISA measured serum levels of inflammatory biomarkers. Spearman's rank correlation coefficient was used to assess relationships between gut microbiota and inflammatory markers. Random forest and receiver operating characteristic (ROC) analyses were applied to identify characteristic microbial taxa associated with OA. RESULTS: Serum levels of the inflammatory factors LPS, IL-1β, IL-6, and IL-10 were significantly elevated in OA patients. Both alpha diversity and overall composition of the gut bacterial and fungal microbiota were altered in OA patients. At the phylum level, the abundance of Proteobacteria increased significantly, whereas that of Firmicutes and Bacteroidota decreased markedly. At the genus level, the abundances of Escherichia-Shigella and the Ruminococcus gnavus group were significantly increased, while those of Bacteroides, the Eubacterium halli group, Subdoligranulum, and Faecalibacterium were significantly decreased. Regarding gut fungi, the phyla Ascomycota and Basidiomycota were significantly enriched in OA patients. At the genus level, Saccharomyces and Aureobasidium were significantly more abundant, whereas Aspergillus, Exophiala, and Kurtzmaniella were significantly reduced. Cross-kingdom network analysis revealed weakened interactions between gut bacteria and fungi in OA patients, disrupting the overall ecological balance of the gut microbiome. Random forest and ROC analyses indicated that the combination of the Eubacterium coprostanoligenes group, Subdoligranulum, the Ruminococcus gauvreauii group, Malassezia, and Aspergillus exhibited strong diagnostic potential for OA. These microbial changes were closely correlated with inflammatory markers. CONCLUSION: OA patients present with both elevated serum inflammatory factors and gut microbial dysbiosis, and significant associations exist between specific microbiota and inflammatory markers. While these findings suggest that certain gut microbes could serve as potential diagnostic biomarkers for OA, further validation is necessary to confirm their clinical applicability.