Figure 4.

Over-release of prostaglandin E2 (PGE₂) in compressed costal cartilage explants is the result of mechanical stress. (a) Implication of the mechanoreceptor integrin α5β1 in PGE₂ over-release in compressed cartilage explants. Mouse costal cartilage explants treated with either the β1 non-blocking antibody VMA1997 or the α5β1 blocking antibody AB1950 at 2.5 μg/ml were compressed (C) or not compressed (NC) for 4 h. Results are normalized to the mean not-compressed control (cont) value. Data are the mean ± SEM of 2 independent experiments with n = 2/group/experiments, analyzed in duplicate. ***p < 0.001 versus control NC, *p < 0.05 versus control C. (b) Increased PGE₂ release in compressed costal cartilage explants is not due to the cytokine IL-1. Mouse costal cartilage explants treated with the IL-1 receptor antagonist (IL1-Ra) at 100 ng/ml were compressed (C) or not compressed (NC) for 4 h. Results are normalized to the mean not compressed control value. Data are the mean ± SEM of 2 independent experiment with n = 2/group/experiments, analyzed in duplicate. *p < 0.05 versus control NC.