In vitro study of intracellular IL‐1β production and β1 integrins expression in stimulated chondrocytes – Effect of rhein

Abstract

The purpose of the present study was to investigate the intracellular IL‐1β production and β1 integrins (α4/β1 and α5/β1) expression on chondrocytes.

Chondroytes monolayer (human chondrosarcoma cell line HEM‐C55) were incubated for 12, 24 and 48 hours in the presence of Tumor Necrosis Factor‐α (TNF‐α, Sigma, France) or recombinant human IL‐1α (rh‐IL1α, Becton Dickinson, France). After direct immunolabelling, cells were either analyzed on FACScan flow cytometer (Becton Dickinson, France), or observed under an epi‐fluorescence inverted microscope equipped with the CellScan EPR^TM optical scanning acquisition system (IPLab‐Scanalytics, USA). We found that the IL‐1β mean fluorescence intensity in flow cytometry and in 3D microscopy was increased in the presence of TNF‐α or rh‐IL‐1α, and α4/β1 or α5/β1 expression was higher on stimulated cells than on control cells.

On the other hand, we have evaluated the in vitro effects of rhein (10⁻⁵ M, Negma, France), an active metabolite of diacerein, on the intracellular IL‐1β and β1 integrins expressed by stimulated or no‐stimulated chondrocytes. The results indicated that rhein leads to a reduction of IL‐1β synthesis whereas a weak decrease of β1 integrins receptors expression is observed.

From this study, it seems that rhein partially reduce cytokine‐induced intracellular IL‐1β production, and it has a weak action on α4/β1 or α5/β1 receptors.