Overexpression of Dual oxidase 2 (Duox2) occurs as an early event in both human inflammatory bowel disease and mouse models of colitis, and has been associated with dysbiosis. We have previously shown that mice bearing constitutive activation of toll-like receptor 4 (TLR4) in intestinal epithelial cells (IECs) (villin-TLR4) have altered microbial populations, increased cytokine expression, and increased Nox1 and Duox2 expression. Villin-TLR4 mice develop spontaneous duodenal tumors. Here, we test whether TLR4-mediated induction of Nox1 and Duox2 is dependent on luminal microbiota.