Claudin‐1 responsiveness through modulation of the inflammatory status in the Caco‐2 model epithelium.

Abstract

The use of hydrocortisone in association with indomethacin is a known risk factor for spontaneous intestinal perforation (SIP) in extremely low birthweight infants. While hypoxia, inflammation, and hydrocortisone have been found to independently alter both tight junction functionality and formation, the concomitant effects of inflammation, hydrocortisone, and indomethacin have yet to be well defined. Through the use of the Caco‐2‐BBe cell line as an in vitro model of the intestinal epithelial barrier, we tested the effects of the pro‐inflammatory agents TNF and IFNγ and the anti‐inflammatory agents indomethacin and hydrocortisone on barrier integrity and tight junction protein expression. Confocal imaging and cellular ATP analysis after 24 and 48 hours of exposure to the inflammatory agents both showed no significant changes in cellular proliferation or ATP synthesis, respectively. Western blot analysis found that claudin‐1 protein expression and localization is affected by inflammatory cytokines. Live cell confocal imaging of eGFP‐claudin‐1 Caco‐2 cells found that addition of pro‐inflammatory agents or the addition of anti‐inflammatory agents resulted in rapid dynamic junctional reorganization. When both the pro‐ and anti‐inflammatory agents were added, this pattern of reorganization was also seen. However, the concomitant effects of the combined pro‐ and anti‐inflammatory agents resulted in a profound inability to recapitulate its original claudin‐1 configuration. The lack of an effect on cellular proliferation and ATP synthesis paired with the alterations in claudin‐1 protein levels and localization suggests that claudin‐1 may be a potential target in better understanding the progression of spontaneous intestinal perforation.Competing Interest StatementAll authors have indicated they have no potential conflicts of interest to disclose. The view(s) expressed herein are those of the author(s) and do not reflect the official policy or position of Brooke Army Medical Center, the U.S. Army Medical Department, the U.S. Army Office of the Surgeon General, the Department of the Air Force and Army, Department of Defense or the U.S. Government.Support or Funding InformationTrinity University Biology Department