Systemic Multifocal Epithelial Inflammations Associated with PBC‐like Bile Duct Damage in Chronic Colitis–Harboring TCRα^−/−×AIM^−/− Mice

<jats:p><jats:bold><jats:sc>Abstract: </jats:sc></jats:bold> <jats:bold>Autoimmune disorder and associated multifocal organ inflammations such as dry gland syndrome are occasionally observed; however, their etiologies are not clearly understood. We previously reported that chronic colitis–harboring TCRα<jats:sup>−/−</jats:sup>×AIM<jats:sup>−/−</jats:sup> mice show primary biliary cirrhosis (PBC)‐like bile duct damage in the liver. Gram‐positive bacterial infection is one of the candidates for the pathogenesis of PBC. We also reported that the bacterial cell wall component lipoteichoic acid (LTA) was detected at the sites of inflammation around damaged bile ducts in PBC patients. On the basis of these facts, we hypothesized that LTA might affect the pathogenesis of bile duct damage in the livers of TCRα<jats:sup>−/−</jats:sup>×AIM<jats:sup>−/−</jats:sup> mice. LTA was detected not only in the portal area with inflammation in the liver but also throughout the gastrointestinal tract, from the stomach to the colon, and especially in the epithelium at sites of inflammation. In addition, LTA was detected around both pancreatic ducts with inflammation and at the distal renal tubules with inflammation in TCRα<jats:sup>−/−</jats:sup>×AIM<jats:sup>−/−</jats:sup> mice. Furthermore, in the liver, pancreas, kidney, and colon, fibrous stroma were detected at the sites of LTA‐positive inflammation foci. Bacterial LTA might affect the pathogenesis of epithelial inflammation followed by fibrosis in systemic multifocal epithelial inflammations in chronic colitis–harboring TCRα<jats:sup>−/−</jats:sup>×AIM<jats:sup>−/−</jats:sup> mice with PBC‐like bile duct damage.</jats:bold> </jats:p>