Blueberry extract for the treatment of ischemic stroke through regulating the gut microbiota and kynurenine metabolism

Background: and purpose Although the gut microbiota and its metabolites have significant protective effects against ischemic stroke(IS), the exact mechanism has yet to be fully elucidated. In this study,the function of intestinal microecology-kynurenine metabolism has been explored in IS rats and patients,which could help us deeply to understand the role of microbiota in the gut-brain axis. Experimental approach Combined serum metabolomics and 16S rRNA gene sequencing were used to reveal the distinctive changes between the gut microbiota and metabolites in rats with or without blueberry extract.Fecal microbiota transplantation(FMT) was employed to validate the protective role of gut microbiota in IS. Furthermore, the interaction between Prevotella and IS was also confirmed in patients. Key results A positive correlation between Prevotella and kynurenine (KYN) was obtained in IS rats. Although the study highlighted that KYN and its metabolites were strongly activated, the 5-HT pathway was not significantly altered.An intervention with Prevotella also significantly improved stroke symptoms by enhancing intestinal barrier function and attenuating the inflammatory response and decreased KYN levels in IS rats.FMT provided more evidences to support that the beneficial effects of blueberry extract on IS involved gut bacteria,especially Prevotella, which have been confirmed by microbiological analyses conducted on IS patients.Moreover, blueberry extract led to significant changes in kynurenic acid,tryptophan and indoleamine 2,3-dioxygenase protein through the interaction with Prevotella. Conclusion and implications Our study demonstrates for the first time that Prevotella and kynurenine metabolism play important roles in brain-gut signaling.And blueberry extract could modulate “intestinal microecology-kynurenine metabolism” to improve IS.