Prophylactic administration of probiotic strains Weizmannia coagulans and Saccharomyces boulardii attenuates early dysplastic changes in an AOM/DSS-induced mouse model

BACKGROUND: Colorectal dysplasia represents an early stage of colorectal carcinogenesis and is closely associated with chronic inflammation and altered microRNA (miRNA) expression. Probiotic strains such as Weizmannia coagulans (formerly Bacillus coagulans) and Saccharomyces boulardii possess anti-inflammatory properties and may influence host miRNA expression, suggesting their potential as prophylactic agents against inflammation-associated colorectal dysplasia. METHODS: Mice received prophylactic oral administration of Weizmannia coagulans or Saccharomyces boulardii beginning one week before azoxymethane/dextran sulfate sodium (AOM/DSS) induction and continuing throughout the experimental period. Histopathological examination, TNF-α immunohistochemistry, serum pro-inflammatory cytokine measurements, and miRNA expression profiling using reverse transcription quantitative polymerase chain reaction (RT-qPCR) were performed to evaluate the prophylactic effects of both probiotic strains. RESULTS: Prophylactic administration of both probiotic strains significantly attenuated early dysplastic alterations and inflammatory cell infiltration compared with the AOM/DSS group (p < 0.05). These histopathological improvements were accompanied by significantly lower serum levels of the pro-inflammatory cytokines IL-6 and IL-1β, together with reduced TNF-α immunoreactivity (p < 0.05). In addition, probiotic pretreatment attenuated the altered miRNA expression profile induced by AOM/DSS. Compared with the model group, expression of miR-122-5p, miR-29b-5p, and miR-15b-5p was significantly reduced, whereas miR-98-5p, miR-202-5p, miR-21-5p, and let-7i-5p showed increased expression and were associated with miRNA expression patterns that more closely resembled those of the control group (p < 0.01). CONCLUSION: Prophylactic administration of Weizmannia coagulans and Saccharomyces boulardii reduced inflammation-associated early dysplastic changes while preserving normal miRNA expression patterns in an AOM/DSS-induced murine model. These findings support the potential of probiotic prophylaxis as an early preventive strategy against colorectal dysplasia and provide a foundation for future studies investigating its clinical applicability.