LAUSR

The commonly used antimicrobial compound triclosan increases colonic inflammation and colon cancer in mice. Triclosan triggers inflammation Antimicrobials are ubiquitous in manufactured products beyond hand soap and exist in the environment as pollutants. Triclosan exposure is practically unavoidable in the United States, but little is known how ingestion may affect our health. Yang and colleagues used mouse models of colitis and colon cancer to see how brief exposures of triclosan could affect inflammation. They observed that triclosan altered mouse gut microbiota and increased inflammation in a TLR4-dependent manner. Triclosan increased the severity of colitis symptoms and spurred colitis-associated colon cancer cell growth. Although the study is limited to mouse models, this work suggests that the effects of triclosan on human health should be examined more closely. Triclosan (TCS) is a high-volume chemical used as an antimicrobial ingredient in more than 2000 consumer products, such as toothpaste, cosmetics, kitchenware, and toys. We report that brief exposure to TCS, at relatively low doses, causes low-grade colonic inflammation, increases colitis, and exacerbates colitis-associated colon cancer in mice. Exposure to TCS alters gut microbiota in mice, and its proinflammatory effect is attenuated in germ-free mice. In addition, TCS treatment increases activation of Toll-like receptor 4 (TLR4) signaling in vivo and fails to promote colitis in Tlr4−/− mice. Together, our results demonstrate that this widely used antimicrobial ingredient could have adverse effects on colonic inflammation and associated colon tumorigenesis through modulation of the gut microbiota and TLR4 signaling. Together, these results highlight the need to reassess the effects of TCS on human health and potentially update policies regulating the use of this widely used antimicrobial.