Neutrophils are an important cellular source of proinflammatory mediators, whose regulation may be of potential benefit for the treatment of a number of inflammatory diseases. However, the mechanisms of lipopolysaccharide (LPS)-induced neutrophil activation and its regulation by anti-inflammatory cytokines have not yet been fully elucidated. Recent studies have revealed that mitogen-activated protein kinases (MAPK) play a crucial role in the generation of proinflammatory mediators in some cell types. Therefore, we conducted this study to determine whether MAPK activation could be involved in prostaglandin E2 (PGE2) production and cyclooxygenase (COX)-2 expression in LPS-stimulated human neutrophils. PD98059 (MEK1 inhibitor) and SB203580 (p38MAPK inhibitor) reduced PGE2 production as well as COX-2 expression in LPS-stimulated neutrophils. In addition, both extracellular signal-regulated protein kinase (ERK) and p38MAPK were phosphorylated and activated in time- and dose-dependent manners. Since we previously showed that IL-10 and IL-4 similarly inhibited COX-2 expression in LPS-stimulated neutrophils, we next tested the effects of IL-10 and IL-4 on the phosphorylation and activation of both kinases. IL-10 inhibited the phosphorylation and activation of p38MAPK, but not ERK. In addition, IL-4 caused a marginal inhibition in the activation of p38MAPK. Taken together, these results suggest that both ERK and p38MAPK pathways are involved in LPS-induced COX-2 expression and PGE2 production in neutrophils, and IL-10 and IL-4 inhibit neutrophil prostanoid synthesis by down-regulating the activation of p38MAPK.
All Science Journal Classification (ASJC) codes
- Immunology and Allergy