Multi-strain bacterial combination mitigates pelvic irradiation-induced gut damage by preserving gut integrity, inhibiting inflammation and apoptosis.

Pelvic irradiation effectively treats pelvic malignancies, but its side effects can be challenging, causing intestinal damage. Alterations in the gut environment can disrupt the microbiota balance, affecting key microbial communities essential for maintaining gut health. Because the gut microbiota helps maintain gut health, bacterial supplementation may reduce radiation-induced gut toxicity. This study explores the mechanism by which a multi-strain bacterial combination comprising Lactobacillus, Bifidobacterium, and Streptococcus mitigates pelvic irradiation-induced gut toxicity. Male Sprague–Dawley rats were orally administered a multi-strain bacterial combination throughout the study period or after radiation exposure. Changes in intestinal morphology, integrity, fibrosis, inflammation, and apoptosis were assessed. The prophylactic-therapeutic administration of the bacterial combination effectively preserved villus height, crypt depth, goblet cell count, and overall gut barrier integrity. Furthermore, prophylactic treatment significantly reduced radiation-induced fibrosis, inflammation, and the expression of apoptotic markers in both the jejunum and colon. In contrast, therapeutic bacterial combination treatment was less effective, suggesting that preventive administration is more beneficial in mitigating radiation-induced gastrointestinal damage. Thus, this study underscores the efficacy of pre-radiation bacterial supplementation in protecting the gut from radiation injury, with potential implications for improved patient quality of life.