TLR4 and fibrosis: To assess the role of TLR4 and elucidate the mechanisms responsible for intestinal fibrosis, the transcription levels of TNF-α, IL-12p40, and transforming growth factor-β (TGF-β) were investigated in LPS-treated peritoneal macrophages from TLR4−/− and wild-type mice (Fig. 3A–C).