Collagen Peptides and <i>Saccharomyces boulardii</i> <scp>CNCM</scp> I‐745 Attenuate Acetic Acid‐Induced Colitis in Rats by Modulating Inflammation and Barrier Permeability

Ulcerative colitis (UC) is an inflammatory bowel disease characterized by recurrent episodes of inflammation and tissue damage, with limited treatment options. This study aimed to investigate the effects of collagen peptides and <i>Saccharomyces boulardii</i> on acetic acid (AA)-induced colitis. Thirty-six male Sprague-Dawley rats were randomly divided into the following four groups: normal control (NC), colitis control (CC), collagen peptide (CP; 0.6 g/kg/day), and <i>S. boulardii</i> (SB; 250 mg/day). Colitis was induced by an intrarectal administration of AA in all groups except NC, and treatments were administered daily for 7 days. The therapeutic effects were evaluated by assessing the disease activity index (DAI), colon mass index, macroscopic and microscopic tissue damage, histopathological changes, zonula occludens (ZO)-1 protein expression, and myeloperoxidase (MPO) activity. The results showed that CP and SB treatments substantially alleviated DAI scores (<i>p <</i> 0.05) and reduced the colon mass index. Colon macroscopic and microscopic damages improved compared to the CC group (<i>p <</i> 0.01). Histologically, both treatments reduced inflammatory cell infiltration, crypt damage, and ulceration, with CP showing a slightly more pronounced effect. Immunohistochemical analysis revealed significant restoration of ZO-1 protein expression in the treated groups, indicating improvement in intestinal barrier integrity (<i>p <</i> 0.01). Furthermore, MPO activity was reduced in both CP and SB groups, significantly in the SB group (<i>p <</i> 0.01). These findings are consistent with previous studies that highlight the anti-inflammatory and barrier-enhancing effects of collagen peptides and probiotics in UC models.