15ΔPGJ2 (15-deoxy-Δ12,14-prostaglandin J2,) represses mPGES (microsomal PGE synthase) expression and PGE2 (prostaglandin E2) production. A) Human chondrocytes were treated in serum free conditions with 3 μM 15ΔPGJ2 for two hours before being incubated with 100 U/ml IL-1α for 24 hours in the presence of 15ΔPGJ2. Cell lysates were subjected to immunoblot analysis using anti mPGES polyclonal antibodies. Actin was blotted as an internal control; B) Quantitation of mPGES inhibition by5ΔPGJ2 treatment. Quantitation of the inhibition by 15ΔPGJ2 was obtained by the densitometric analysis of three Western blots from three different primary cultures; to show the repression by 15ΔPGJ2 the % value referred to the value in IL-1 induced cells (100%) is calculated. Average ± standard deviation is shown. C) PGE2 production. Conditioned media collected from human chondrocytes were analyzed for prostaglandin E2 content by a competitive immunoassay using the prostaglandin E2 EIA kit Monoclonal. Two experiments were performed in triplicate dishes, each one assayed in triplicate. One representative experiment is shown. Concentrations are expressed in pg/ml. 15ΔPGJ2, 15-deoxy-Δ12,14-prostaglandin J2,; COX-2, cyclooxygenase-2; DGDG, digalactosyldiacylglycerol; IL-1, interleukin-1; IL-6, interleukin-6; IL-8, interleukin-8; MGDG, monogalactosyldiacylglycerol; mPGES, microsomal PGE synthase; NF-kB, nuclear factor-kappaB; P1, cell passage number1; p38, p38 mitogen activated protein kinase; PGE2, prostaglandin E2; TNFα, tumor necrosis factor alpha.
Ulivi et al. Arthritis Research & Therapy 2011 13:R92 doi:10.1186/ar3367