Cerebrovascular Accident is a Major Comorbidity of AHRUS: The Pathogenic Role of Gut Dysbiosis-Induced CD8+ T Cell Infiltration

Acute hemorrhagic rectal ulcer syndrome (AHRUS) is a critical emergency frequently comorbid with cerebrovascular accident (CVA), though their pathogenic relationship remains unclear. We analyzed clinical data and conducted a meta-analysis, finding a 75% CVA co-occurrence rate among AHRUS patients. Using a middle cerebral artery occlusion (MCAO) mouse model, we demonstrated that CVA directly induces severe rectal mucosal injury. Integrated RNA-seq and 16S rRNA sequencing revealed that MCAO-induced gut dysbiosis shifts the rectal immune microenvironment toward an adaptive response. This was characterized by significant CD8+ T cell infiltration and upregulation of chemokines like CCL5, CCL20, contrasting with the innate-dominated response in sham controls. Correlation analysis confirmed that this specific dysbiosis pattern promotes rectal inflammation and CD8+ T cell recruitment. Our findings establish CVA as an independent pathogenic factor for AHRUS and highlight a brain-gut-immune axis mechanism where microbiota-driven CD8+ T cell infiltration mediates mucosal damage. This study suggests that targeting gut microbiota or adaptive immunity may offer novel strategies for preventing AHRUS following stroke.