Objective To explore the effects of lipoxinA4 on expression of cyclooxygenase-2 (COX-2) and prostaglandin E2 (PGE2) in rat primary lung fibroblast cells (LF) after lipopolysaccharide (LPS) challenge.Methods Primary lung fibroblast cells were incubated with various concentrations (0.1,1,10 μg/mL) of LPS for different lengths of time (3,6,9 h).Then primary lung fibroblast cells were still incubated in DMEM medium containing LPS in the presence or absence of lipoxinA4.After incubation,the supematant of medium was collected and the level of PGE2 was detected by using ELISA.The cells were harvested,and COX-2 protein was analyzed by Western blot.Results The model of acute inflammation in fibroblasts was well established by administering 1 μg/mL LPS in fibroblasts for 6 hours.Induction of COX-2 protein by LPS was inhibited by lipoxinA4.The levels of PGE2 in control group,LPS group and LPS + LipoxinA4 group were 55.84 pg/mL,411.73 pg/mL and 307.07 pg/mL,respectively,and there was a significantdifference between LPS group and LPS + LipoxinA4 group (P ＜0.01).Conclusion LipoxinA4 down-regulates the expression of the COX-2 induced by LPS in primary lung fibroblast cells and consequently inhibits the production of PGE2 in a dose dependent manner.