Human leukocytes selectively convert 4 S ,5 S -epoxy-resolvin to resolvin D3, resolvin D4, and a cys-resolvin isomer

Significance The resolution of the acute inflammatory response is an active, highly organized process essential for tissue regeneration, wound healing, and the return to homeostasis that involves specialized proresolving mediators (SPMs). The elucidation of mediators that play roles in these processes is of general interest since many widely occurring diseases display unresolved inflammation in their pathobiology. Here, we document the pivotal role of 4 S ,5 S -epoxy-resolvin as an intermediate in the biosynthesis of resolvin D3 and resolvin D4 and identified a unique cysteinyl-resolvin isomer that is biosynthesized in a cell type–specific manner. Results from cell- and model organism–based systems each defined the potent bioactivity of the cysteinyl-resolvin isomer.