Probiotic Bacteria Reduce Inflammation in Mice

A study exploring how "probiotic” bacteria such as those found in yogurt actually work has revealed that irradiated probiotics performed as well as live bacteria in reducing inflammation in mice.

The study also showed that purified probiotic bacterial DNA alone can reduce inflammation in mice with experimentally induced colitis. Investigators found that probiotic DNA acts in a specific way by activating a defined element within the innate immune system. An immune system protein called TLR9 is a pivotal player in the chemical signaling chain that slows inflammation. In a series of experiments, the researchers found that probiotic DNA exerts its effects through TLR9. In fact, mice without the gene for TLR9 protein cannot benefit from probiotics, either living or irradiated, or from probiotic DNA.

These new insights suggest new therapeutic possibilities. For example, purified probiotic DNA or irradiated probiotics may be safer than viable preparations and could be used by people with compromised immune systems. Prior to this research, probiotics were thought to mediate their effects through some kind of nonspecific action. Probiotics have shown promise for treating such inflammatory bowel diseases (IBDs) as Crohn's disease in addition to ulcerative colitis.

The study was led by Eyal Raz, M.D., of the University of California, San Diego (USA), supported by the U.S. National Institute of Allergy and Infectious Diseases (NIAID).




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