Figure 9.

Cytosolic phospholipase A₂ (cPLA₂) activation, cyclooxygenase 2 (COX-2) activation, prostaglandin E₂ (PGE₂) induction and EP4 receptor are involved in the anti-inflammatory effect of docosahexaenoic acid (DHA) or GW9508 in human primary monocyte-derived macrophages. (a–c) Human primary monocyte-derived macrophages were pre-treated or not with cytosolic phospholipase A₂ (cPLA₂) inhibitor (5 μm) (a) or COX-2 inhibitor (3 μm) (b) or EP2 inhibitor (3 μm), or EP4 inhibitor (2 μm) (c) for 1 hr, then stimulated with DHA or GW9508 (100 μm) for 1 hr and finally stimulated with lipopolysaccharide (LPS) (10 ng/ml) for 6 hr. Cell culture supernatants were collected and assayed for interlukin-6 (IL-6) secretion. Data are presented as the mean ± SEM (n = 3) of IL-6 secretion (pg/ml) and are representative of the results from three different donors. *P < 0·05 as indicated, as assessed by analysis of variance with Holm–Sidak post hoc test. ND = non-detectable. (d) Human primary monocyte-derived macrophages were pre-treated with 100 nm PGE₂ for 1 hr, and then stimulated with 10 ng/ml LPS for 6 hr. Cell culture supernatants were assayed for IL-6 secretion. Data are shown as the mean ± SEM (n = 3) of IL-6 secretion (pg/ml) and are representative of data from three different donors. ^##P < 0·01 as indicated, as assessed by Student's t-test. (e) Determination of cell viability. Human primary monocyte-derived macrophages were stimulated with 100 μm DHA or GW9508 or vehicle for 7 hr. Data are shown as the mean ± SEM of percentage of absorbance of the formazan product at 490 nm of DHA- or GW9508-treated cells as compared with that of vehicle control with four replicates. The data shown are representative results from three different donors.