Figure 3

MGDG (monogalactosyldiacylglycerol) represses p38 (p38 Mitogen Activated Protein Kinase), involved in IL-6 (Interleukin-6) and IL-8 (Interleukin-8) production. A) Inhibition of IL-6 and IL-8 synthesis by the p38 inhibitor SB 203580. Human chondrocytes were treated with 10 μM SB203580 for two hours before being supplemented with 100 U/ml IL-1α for 20 hours in the presence of SB203580. Conditioned media were collected and IL-6 and IL-8 synthesis was analyzed by Western blot; B) Quantitation of the inhibition by the MGDG of the IL-6 and IL-8 synthesis. The average of the densitometric analysis of five western blots performed in five independent experiments on four different primary cultures is presented. To show the repression by SB203580 the % value referred to the value in IL-1α induced cells (100%) is calculated. C) MGDG inhibition of p38 phosphorylation. Human chondrocytes were treated with 100 U/ml IL-1α in the absence and the presence of 20 μM MGDG for 60 minutes. Phosphorylation of p38 and native inactive protein levels were assayed using the FACE p38 Kit. The average of two independent experiments performed in triplicate are shown. The number of cells in each well was determined using Crystal Violet according to the manufacturer's instructions. To show the repression by MGDG the % value referred to the value in IL-1α induced cells (100%) is calculated. 15ΔPGJ2, 15-deoxy-Δ^12,14-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.