Formyl peptide receptors (FPRs), which are seven-membrane
G-protein coupled receptors, recognize chemotactic signals to protect hosts from pathogenic
infections and mediate inflammatory responses in the body. There are three
isoforms of FPRs in humans-FPR1, FPR2, and FPR3-and they bind to N-formyl
peptides, except FPR3, and to various endogenous agonists. Among FPR family members, FPR2 has a lower affinity for N-formyl
peptides than FPR1 and binds with a wide range of endogenous or exogenous agonists. Thus, FPR2 is considered the most ambiguous member. Accumulating evidence has shown that FPR2 is involved in the host's defense against
bacterial infection and
inflammation in
liver diseases, such as
nonalcoholic fatty liver disease,
liver fibrosis, and
liver cancer, suggesting the pathophysiological relevance of FPR2 to the liver. However, FPR2 has been shown to promote or suppress
inflammation, depending on the type of FPR2-expressing cell and FPR2-bound
ligands in the liver. Therefore, it is important to understand FPR2's function per se and to elucidate the mechanism underlying
immunomodulation initiated by
ligand-activated FPR2 before suggesting FPR2 as a novel therapeutic agent for
liver diseases. In this review, up-to-date knowledge of FPR2, with general information on the FPR family, is provided. We shed light on the dual action of FPR2 in the liver and discuss the hepatoprotective roles of FPR2 itself and FPR2 agonists in mediating anti-inflammatory responses.