J. Golden1, P. Kavarian1, L. Illingworth1, J. Uppuluri1, O. Escobar1, M. Isani1, C. Gayer1, A. Grishin1, H. Ford1 1Children’s Hospital Los Angeles,Pediatric Surgery,Los Angeles, CA, USA
Introduction: Cyclooxygenase-2 (COX-2) and prostaglandin E2 (PGE2) are inflammatory mediators that have been implicated in sepsis, inflammation, and intestinal barrier breakdown. Previous work in our lab has shown that COX-2 can be upregulated by its end-product PGE2 in enterocytes. We have identified pro-inflammatory prostanoid receptor, EP2, as a key mediator in this feedback loop leading to upregulation of COX-2 during inflammation. Therefore, we hypothesized that EP2 inhibition would protect against induction of COX-2 and intestinal barrier breakdown in experimental peritonitis.
Methods: Following IACUC approval, C57/Bl6 mice underwent sham operation as a control or cecal ligation and puncture (CLP) to induce experimental peritonitis. Mice were injected intraperitoneally with or without 10mg/kg EP2 receptor antagonist PF-04418948 at time of operation and were orally gavaged with fluorescein isothiocyanate (FITC)-dextran 8 hours later. All mice were sacrificed 12 hours following sham or CLP. Blood samples were analyzed for FITC-dextran to determine intestinal barrier breakdown and terminal ileum was analyzed for COX-2 expression.
Results: CLP led to increased serum FITC-dextran levels and higher intestinal COX-2 mRNA and protein expression compared with sham. PF-04418948 attenuated serum FITC-dextran levels and intestinal barrier breakdown from 4.2±0.8 to 2.0±0.5 fold change from sham (p<0.05) in mice who underwent CLP. PF-04418948 decreased COX-2 mRNA levels in terminal ileal samples from 25±19 to 9±3.3 fold compared with sham mice. Additionally, COX-2 protein levels in terminal ileal samples decreased from 1.8±0.1 to 1.2±0.1 fold sham levels (p<0.05) in CLP mice who received PF-04418948.
Conclusion: EP2 receptor inhibition protects against intestinal barrier breakdown following cecal ligation and puncture and may inhibit the positive feedback induction of COX-2 via PGE2 activation of EP2. This suggests that EP2 receptor specific inhibition may have important therapeutic implications in the treatment of inflammation and gut-origin sepsis.