Probiotic and Vitamin D Ameliorate TNBS-Induced Colitis by Targeting Mucosal Barrier and Neutrophil Infiltration

Probiotic and vitamin D supplements are widely studied in clinical and animal studies as potential treatments for inflammatory bowel disease. However, their potential synergistic or additive effect in ameliorating colitis development is still poorly understood. The aim of this study was to investigate the potential beneficial enhancement of combining a mixed-strain probiotic with vitamin D supplementation in a colitis animal model.

After 5 days of acclimation, C57BL/6 mice received Vivomixx probiotic (at least 1 × 10⁹ Colony-Forming Units) and/or vitamin D (5 IU/g) in drinking water and chow, respectively, for 7 days prior to intracolonic TNBS-induced colitis and until sacrifice. On day 10, animals were sacrificed, and colons were collected to assess colonic damage, cytokine and chemokine expression, total M1 macrophage phenotype, and neutrophil recruitment. Serum and fecal samples were collected to assess vitamin D levels and microbiome composition.

Administration of probiotic and vitamin D alone or combined decreased colonic damage and neutrophil recruitment and activity. This effect was associated with an increase in the active form of vitamin D in serum and mucosal barrier integrity. However, administration of probiotics and/or vitamin D did not modulate macrophage infiltration or the M1 pro-inflammatory phenotype.

These results suggest that combined probiotic and vitamin D supplementation attenuates TNBS-induced colitis by targeting neutrophil infiltration while enhancing the mucosal barrier. This alternative approach may offer protective potential for IBD management.