Introduction: Infections are a common cause of post-stroke morbidity and mortality. Recent studies suggest that gut microbiota are a major source of post-stroke infection. Gut mucus layers are a major area of communication between gut microbiota and host immune cells. To our knowledge there have been no studies evaluating the role of colonic epithelial mucins, where most of the gut bacteria reside, after ischemic stroke. Hypothesis: Epithelial mucin plays a protective role in stroke-induced colonic disruption. Methods: Mice were subjected to either sham or 60-minute middle cerebral artery occlusion (MCAO). Neurological deficit score (NDS) and levels of lipopolysaccharide-binding protein (LBP) in plasma were assessed at day 7 after stroke. Mice were sacrificed at day 7 after stroke and colonic epithelial cells (ECs) were isolated for a gene expression study. Tissues were used for histology and bacterial in situ hybridization. Fecal samples were collected for 16S sequencing and IgA ELISA. Results: Young female mice had lower NDS and LBP levels, with intact colonic structures (n=4/group, P <0.05). Young mice ECs significantly increased 1) regenerating islet-derived protein (Reg) family-specific antimicrobial proteins in males (24.3, 21.3 and 2.5 fold change in Reg3β, -γ and -4, respectively) and 2) mucin genes in females (1.8 and 1.4 fold change in Muc2 and -4, respectively, n=4-5/group, P <0.05). Young ovariectomized mice switched their protective strategies from enhanced expression of mucin genes to a “male-like” pattern in which Reg genes were increased after stroke (n=3-5/group, P <0.05). Aged mice failed to express these sex-specific genes after stroke. Interestingly, after stroke, bacteria from young female but not male mice were found at a farther distance from the colonic epithelium secondary to intact mucus layers. Finally, young female mice increased mucin-regulating Akkermansia bacteria and IgA in the feces after stroke (n=4/group, P <0.05). Conclusions: Our data demonstrates that 1) stroke provokes a colonic epithelial response and 2) mucin is critical for colonic protection in stroke. In conclusion, mucin should be considered as a novel target to improve post-stroke recovery as well as an important element in maintaining colonic structure.