Effects of 15-deoxy-∆¹²,¹⁴-prostaglandin J₂ on the production of IL-8 and the expression of Toll-like receptor 2 in human primary keratinocytes stimulated with lipopolysaccharide.

15-deoxy-∆(12,14)-prostaglandin J(2) (15d-PGJ(2)) is an anti-inflammatory prostaglandin that plays a role in promoting the resolution of inflammation. We investigated the effects of 15d-PGJ(2) on the production of IL-8 and on the expression of Toll-like receptors (TLRs) 2 in human primary keratinocytes stimulated with lipopolysaccharide (LPS). Cell proliferation was analyzed using the MTT assay, TLR2 and -4 mRNA expression was detected by RT-PCR, and IL-8 production and NF-κB p65 activities were determined by ELISA. LPS and 15d-PGJ(2) did not influence the proliferation rate at low concentrations (0.5 and 2.0 μM) in keratinocytes, and showed toxicity at high concentrations (5.0 μM). LPS, compared with control, induced the expression of TLR2 mRNA, increased IL-8 production, and enhanced NF-κB activity. 15d-PGJ(2) decreased TLR2 mRNA, increased IL-8 production, and suppressed NF-κB activity. Costimulation with LPS and 15d-PGJ(2), compared with LPS stimulation alone, decreased TLR2 mRNA (1.8-fold), increased IL-8 production (1.8-fold at 0.5 μM and 3.7-fold at 2.0 μM), and inhibited NF-κB activity (3.3-fold at 0.5 μM and 5.1-fold at 2.0 μM). TLR4 mRNA was not expressed in primary keratinocytes. These results suggest that 15d-PGJ(2) suppresses TLR2 expression and that it up-regulates the production of IL-8 by inhibiting the NF-κB signaling pathway in primary keratinocytes. Thus, 15d-PGJ(2) can have both anti- and pro-inflammatory effects, and 15d-PGJ(2)-mediated IL-8 up-regulation is related to the mitogen-activated protein kinase (MAPK) and NF-κB signaling pathways.