Abstract 593: A Novel PGE2 Receptor 4-Selective Agonist Suppresses Acute Rejection via Inflammatory Factor Regulation in Murine Cardiac Allografts
Background: PGE2 exerts an anti-inflammatory action by ligation of the PGE2 receptor subtype EP4 among the four of the receptor subtypes in inflammatory diseases. Because little is known about the effect of EP4R in transplantation, we examined the anti-inflammatory effect of EP4 using the murine cardiac transplantation model.
Methods and Results: We developed a novel EP4 selective agonist, EP4RAG, and performed subcutaneous injection of EP4RAG (3mg/kg) into recipient mice. We demonstrated that EP4RAG treatment prolonged graft survival (13.5+/−1.4 days, P<0.05, n=7) compared to that of the vehicle treated group (7.3+/−0.2 days, n=7). Allografts were harvested on day 7 for pathological and molecular examination. While the vehicle treated group showed severe myocardial cell infiltrations (38.4+/−2.5 %, n=10), the EP4RAG treated group attenuated the development (16.7+/−3.4 %, P<0.05, n=8). EP4RAG suppressed various inflammatory factors such as cytokines (e.g. IFN-g, IL-6), chemokines (e.g. IP-10, MIP-1) and adhesion molecules (e.g. ICAM-1) compared to the vehicle treated group in mRNA and protein levels. In vitro assay, we demonstrated that EP4RAG suppressed T lymphocyte proliferation (0.067+/−0.001 OD, P<0.05) compared to the control group (0.105+/−0.003 OD) by MLR. We also showed that EP4 mainly attenuated the activation of macrophages by co-culture. EP4RAG inhibited the activation of NF-kB compared to the control group in macrophages with IL-1beta stimulation.
Conclusions: An EP4R agonist, EP4RAG is potent for the suppression of acute rejection through proinflammatory factor regulation.