TLR4 and inflammatory bowel disease: Upregulation of MD-2/TLR4 may also result from stimulation of ligands other than LPS, and, furthermore, interferon gamma (IFN-g) and tumor necrosis factor alpha (TNF-a), which play significant roles in triggering IBD, have been found to upregulate intestinal epithelial TLR4 expression in vitro [47, 48].