Tetragenococcus halophilus Alleviates Intestinal Inflammation in Mice by Altering Gut Microbiota and Regulating Dendritic Cell Activation via CD83

Ulcerative colitis (UC) is one of the major subtypes of inflammatory bowel disease with unknown etiology. Probiotics have recently been introduced as a treatment for UC. Tetragenococcus halophilus (T. halophilus) is a lactic acid-producing bacterium that survives in environments with high salt concentrations, though little is known about its immunomodulatory function as a probiotic. The purpose of this study is to determine whether T. halophilus exerts an anti-inflammatory effect on intestinal inflammation in mice. Colitis was induced in C57BL/6J mice by feeding 4% DSS in drinking water for 7 days. T. halophilus was orally administered with DSS. Anti-inflammatory functions were subsequently evaluated by flow cytometry, qRT-PCT, and ELISA. Gut microbial composition was analyzed by 16S rRNA metagenomic analysis. DSS-induced colitis mice treated with T. halophilus showed less weight loss and significantly suppressed colonic shortening compared to DSS-induced colitis mice. T. halophilus significantly reduced the frequency of the dendritic cell activation molecule CD83 in peripheral blood leukocytes and intestinal epithelial lymphocytes. Frequencies of CD8+NK1.1+ cells decreased in mice with colitis after T. halophilus treatment and IL-1β levels were also reduced. Alteration of gut microbiota was observed in mice with colitis after administration of T. halophilus. These results suggest T. halophilus is effective in alleviating DSS-induced colitis in mice by altering immune regulation and gut microbiome compositions.