Dynamic compression alters NFkappaB activation and IkappaB-alpha expression in IL-1beta-stimulated chondrocyte/agarose constructs

Objective and design  Determine the effect of IL-1β and dynamic compression on NFκB activation and IκB-α gene expression in chondrocyte/agarose constructs.Methods  Constructs were cultured under free-swelling conditions or subjected to dynamic compression for up to 360 min with IL-1β and/or PDTC (inhibits NFκB activation). Nuclear translocation of NFκB-p65 was analysed by immunofluoresence microscopy. Gene expression of IκB-α, iNOS, IL-1β and IL-4 was assessed by real-time qPCR.Results  Nuclear translocation of NFκB-p65 was concomitant with an increase in nuclear fluorescence intensity which reached maximum values at 60 min with IL-1β (p < 0.001). Dynamic compression or PDTC reduced nuclear fluorescence and NFκB nuclear translocation in cytokine-treated constructs (p < 0.001 and p < 0.01 respectively). IL-1β increased IκB-α expression (p < 0.001) at 60 min and either induced iNOS (p < 0.001) and IL-1β (p < 0.01) or inhibited IL-4 (p < 0.05) expression at 360 min. These time-dependent events were partially reversed by dynamic compression or PDTC (p < 0.01) with IL-1β. Co-stimulation by dynamic compression and PDTC favoured suppression (IκB-α, iNOS, IL-1β) or induction (IL-4) of gene expression.Conclusions  NFκB is one of the key players in the mechanical and inflammatory pathways, and its inhibition by a biophysical/therapeutic approach could be a strategy for attenuating the catabolic response in osteoarthritis.