<i>Lactobacillus fermentum</i> V3 ameliorates colitis-associated tumorigenesis by modulating the gut microbiome.

Abstract

<i>Lactobacillus</i> spp., a common probiotic used as a dietary supplement, is good for the digestive system. However, its anti-cancer activity still remains unclear. In this study, we aim to examine the effect of <i>Lactobacillus fermentum</i>, <i>Lactobacillus acidophilus</i> and <i>Lactobacillus rhamnosus</i> on azoxymethane/dextran sulfate sodium (AOM/DSS)-induced colitis-associated cancer. Male ICR mice were injected with 10 mg/kg AOM and 2.5% DSS via drinking water, and then fed with different <i>Lactobacillus</i> (1 × 10⁸ CFU/day) for 14 weeks. The colonic tissues were collected for biomedical analysis, and gut microbiota profiling was detected by next generation high-throughput sequencing comparing to the 16S rRNA gene. We found that pretreatment with <i>Lactobacillus fermentum</i> (Lac.ferm) significantly inhibits colonic tumor formation (<i>P</i> < 0.05) and markedly decreases pro-inflammatory cytokines in AOM/DSS-induced mice. Furthermore, 16S rRNA sequencing data showed that Lac.ferm altered the composition of gut microbiota by reducing the percentage of <i>Bacteroides</i>. Moreover, linear discriminant analysis scores revealed that <i>Lactobacillus fermentum</i> within phylum <i>Firmicutes</i> was the prominent species existing in the Lac.ferm-treated group. Overall, the above findings suggest that dietary Lac.ferm could modulate the gut microbial community, which might be beneficial to alleviating colon cancer progression.