Differential Expression of Prostaglandin E2 Receptors in Porcine Kidney Transplants

Andrew Harner, Y. Wang, Xuexiu Fang, Todd D. Merchen, Philip B. Cox, Sam Ho, Daniel T Kleven, Thomas Thompson, N. Stanley Nahman

Research output: Contribution to journalArticlepeer-review


Background: Acute rejection of a kidney allograft results from adaptive immune responses and marked inflammation. The eicosanoid prostaglandin E2 (PGE2) modulates the inflammatory response, is generated by cyclooxygenase 2 (COX-2), and binds to 1 of the 4 G protein-coupled E prostanoid cell surface receptors (EP1-4). Receptor activation results in in proinflammatory (EP1 and EP3) or anti-inflammatory (EP2 and EP4) responses. We theorized that expression of the components of the COX-PGE2-EP signaling pathway correlates with acute rejection in a porcine model of allogeneic renal transplantation. Method: COX-2 enzyme and EP receptor protein expression were quantitated with western blotting and immunohistochemistry from allotransplants (n = 18) and autotransplants (n = 5). Linear regression analysis was used to correlate EP receptor expression with the Banff category of rejection. Results: Pigs with advanced rejection demonstrated significant increases in serum PGE2 metabolites, while pigs with less rejection demonstrated higher tissue concentrations of PGE2 metabolites. A significant negative correlation between COX-2 expression and Banff category of rejection (R = −0.877) was shown. Rejection decreased expression of EP2 and EP4. For both receptors, there was a significant negative correlation with the extent of rejection (R = −0.760 and R = −0.891 for EP2 and EP4, respectively). Rejection had no effect on the proinflammatory receptors EP1 and EP3. Conclusion: Downregulation of COX-2 and the anti-inflammatory EP2 and EP4 receptors is associated with acute rejection in unmatched pig kidney transplants, suggesting that the COX-2-PGE2-EP pathway may modulate inflammation in this model. Enhancing EP2 and/or EP4 activity may offer novel therapeutic approaches to controlling the inflammation of acute allograft rejection.

Original languageEnglish (US)
Pages (from-to)2124-2131
Number of pages8
JournalTransplantation Proceedings
Issue number6
StatePublished - Jul 1 2019

ASJC Scopus subject areas

  • Surgery
  • Transplantation

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