Delta-tocotrienol 13′-Carboxychromanol, a Vitamin E Metabolite, Interacts With Gut Microbes As Indicated by Its Anti-colitis Synergy With a Lactic Acid Bacterium in Mice

Ulcerative colitis (UC) is an inflammatory colonic disease and microbial dysbiosis is one of its risk factors. We recently showed that delta-tocotrienol 13’-carboxychromanol (dTE-13’), a metabolite of the natural vitamin E form dTE, inhibited colitis-associated tumorigenesis in mice, modulated their gut microbes and increased the relative abundance of a lactic acid bacterium. Interestingly, a subspecies of this bacterium named Lactococcus lactis subsp. cremori (L. cremoris), has been reported to attenuate UC in mice. Therefore, we reasoned that combining dTE-13’ with L. cremoris may offer synergistic protection against UC in mice. We fed male balb/c mice with either 0.04% (w/w) dTE-13’ in diet, or 5 × 108 CFU L. cremoris through gavage or a combination of both for 7 days. Then we induced UC in these mice by adding 2% dextran sulfate sodium to their drinking water. All treatments continued along with UC for an additional 9 days till animal sacrifice. To assess the anti-UC effects of the combination, we evaluated mice's colitis symptoms, colonic tissue damage, and cytokine levels. To further understand the role of gut microbes underlying the anti-UC effects of the combination, we processed fecal samples to analyze changes in microbial composition, and level of dTE-13’ metabolites, and performed in vitro anaerobic incubation using mouse's cecum microbes. Compared to the controls, dTE-13’ + L. cremoris offered superior protection against UC as indicated by milder clinical symptoms, less tissue damage and decreased colonic inflammation, while neither dTE-13’ nor L. cremoris alone showed significant benefits. Mechanistically, combination rendered gut microbes resistant to UC-induced microbial dysbiosis and increased the fecal level of a reduced dTE-13’ metabolite. Preliminary observations from the anaerobic study suggested that gut microbes pre-selected by dTE-13’ in the animal study were capable of reducing the compound, and L. cremoris appeared to promote the microbiota-mediated metabolism. Our study demonstrated the benefits of dTE-13’ + L. cremoris against colitis. It offered a new perspective of developing anti-UC therapies by combining dietary compounds with bacteria, and presented the first evidence that gut microbes can metabolize dTE-13’, a metabolite of vitamin E. Purdue Center for Cancer Research.