DEXAMETHASONE PREVENTS LIPOPOLYSACCHARIDE-INDUCED EPITHELIAL BARRIER DYSFUNCTION IN RAT ILEUM

Inflammatory mediators have been postulated as elementary inducing factors to the disruption of the intestinal tight junctions (TJ) and consequently, gut permeability and bacterial translocation. Corticosteroids are considered the mainstay in the treatment of septic shock; however, the impact of this therapy on the intestinal epithelial barrier dysfunction during septic shock remains unknown. Our aims were to demonstrate the role of low dexamethasone (DEX) doses in modulation of the inflammatory response, as well as the expression and the arrangement of TJ proteins in endotoxemic rats. One hour before the endotoxemia induction by lipopolysaccharide (LPS) administration, rats were pretreated with DEX at two low-doses (0.1 and 1.0 mg/kg). The parameters assessed included intestinal permeability, bacterial translocation, cytokines production, histology injury, localization, and expression of TJ proteins. Endotoxemic rats displayed intestinal epithelial barrier dysfunction, characterized by increased permeability and bacterial translocation, TJ disruption (opening and changes to its constituent proteins expression) and hyperactivation of the inflammatory response. On the other hand, the pretreatment with DEX attenuated the systemic and mucosal production of inflammatory mediators and also reverted the LPS-induced ileal injuries, increasing the expression of occludin and claudin-1, but also reducing claudin-2. Moreover, the histological damages and the morphology of the TJ were preserved by the DEX administration, therefore reducing their LPS-induced opening. The present study sheds light on the fact that early DEX treatment breaks the vicious cycle of local gut inflammation and barrier dysfunction in endotoxemia, especially preserving an essential structure of this monolayer epithelium, the TJ.