GPR18 and infection: Resolvins of the D-series are derived from docosahexaenoic acid (DHA) and include RvD2 (7S,16R,17S-trihydroxy-4Z,8E,10Z,12E,14E,19Z-DHA), which binds to the cell surface receptor GPR18/DRV2 providing significant protection in infection-induced inflammation (19).