The update of prostaglandin E2 receptor subtype 4 (EP4) in inflammatory diseases

Inflammation is a defensive response of the organism to stimuli and is crucial for maintaining the stability of the internal environment. However, abnormal inflammatory responses, including over-activation or hypo-responsiveness, are among the major factors causing numerous diseases. Among all prostaglandin substances, PGE 2 is one of the common lipid mediators produced by the catalysis of arachidonic acid (AA) by cyclooxygenase (COX). Through autocrine or paracrine secretion, PGE 2 acts on four receptor subtypes ( i.e. , EP1, EP2, EP3, and EP4) and participates in various physiological and pathophysiological processes, commonly including fever, pain, and inflammation. Among them, EP4 is deeply researched and mediates many effects of PGE 2 , such as fever, pain, inflammation, blood pressure regulation, water-salt metabolism, and tumorigenesis. In particular, the mechanism of action and potential therapeutic value of EP4 in inflammatory diseases have been research hotspots for years. Here, we summarize the function of the PGE 2 –EP4 signaling in inflammation and related inflammatory diseases.