A New Combination of Bifidobacterium bifidum and Lactococcus lactis Strains with Synergistic Effects Alleviates Colitis-Associated Colorectal Cancer

Chronic inflammation is a factor in the development of cancer, and probiotics play a role in preventing or treating inflammation as an adjuvant therapy. To investigate potential probiotics for the prevention of colitis-associated colorectal cancer (CAC), Bifidobacterium bifidum H3-R2 and Lactococcus lactis KLDS4.0325 were used to examine the effects on colon cancer cells and in an inflammation-related cancer animal model. The results revealed that B. bifidum H3-R2 in combination with L. lactis KLDS4.0325 caused apoptosis in colon cancer cells by increasing caspase-3 and caspase-9 protein levels, enhancing Bax expression, and lowering Bcl-2 expression. In addition, the combination of the two strains relieved the tissue damage; reduced proinflammatory cytokines, myeloperoxidase (MPO) activity, and hypoxia-inducible factor 1-alpha (HIF-1 alpha) level; upregulated anti-inflammatory cytokines; increased colonic tight junction protein expression; regulated intestinal homeostasis by inhibiting NLRP3 inflammasome signaling pathway; and improved the imbalance of gut microbiota in animal models. Moreover, the combination of the two strains had a greater preventive impact than each strain alone. These findings are supportive of clinical studies and product development of multi-strain probiotic preparations for diseases associated with colitis.