Integrating gut microbiota and vitamin D Axis: a combined approach for colitis management

Inflammatory Bowel Diseases (IBD) either Crohn’s disease or Ulcerative colitis are debilitating disorders that affect the gastrointestinal tract with chronic inflammation. The etiology of the disease is still unknown but vitamin D deficiency and gut dysbiosis has been observed as contributing factors. Therefore, the objective: of this research was to demonstrate the possible synergistic potential of vitamin D and probiotic in a model of colitis using 2 routes of administration: via water ad libitum or pipette feeding. Evaluating this model are critical since they can differ in successful probiotic colonization and therapeutic effect. For the Methodology: male and female C57BL/6 mice were divided into 5 groups (n=10-16/group): Healthy control, Colitis + Vehicle, Colitis + Probiotic, Colitis + Vitamin D and Colitis + Probiotic + Vitamin D. Animals received 7 days of pretreatment with a multi-strain probiotic in drinking water or by pipette feeding. High vitamin D (5IU/g) was administered in food. On day 7, animals were lightly anesthetized with ether and colitis induction was done by intracolonic administration of 0.1mL of 4mg trinitrobenzene sulfonic acid in 30% ethanol. Animals were sacrificed 3 days post colitis induction and colonic tissue was collected to assess macroscopic and histological microscopic colonic damage. In addition, colonic samples were stained to assess for pro-inflammatory macrophage infiltration (M1) and occludin tight junctions, while cytokines IL-6 and IL-10 were measured by RT-PCR. Treatment delivery was verified with serum samples to measure vitamin D (1,25OH) and fecal samples for the probiotic strain S. thermophilus. Results: indicate that administration of probiotic and vitamin D combined or alone decreased macroscopic colonic damage (p<0.05). However, only co-administration of probiotic and vitamin D decreases microscopic damage and proinflammatory cytokine IL-6 when administered by drinking water (p<0.05). In addition, administration of probiotic via drinking water increased occludin tight junctions (p<0.05) but failed when administered by pipette feeding. Additionally, increased levels of S. thermophilus was observed in animals receiving probiotic (p<0.01). Animals receiving probiotic with vitamin D had increased serum 1,25(OH) levels when administered by drinking water. However, administration of probiotic and/or vitamin D did not decrease M1 proinflammatory macrophage infiltration via either route tested. In Conclusion: these findings suggest that the combination of probiotics and vitamin D, particularly when administered via drinking water, holds promise as a therapeutic strategy for improving mucosal integrity and modulating inflammatory responses in colitis. This work was supported by RISE (R25GM082406), G-RISE (T32GM144896), PRI MD Summer Program and Porter Physiology Development Fellowship. This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.