Dynamic compression alters NFkappaB activation and IkappaB-alpha expression in IL-1beta-stimulated chondrocyte/agarose constructs.
OBJECTIVE
Determine the effect of IL-1beta and dynamic compression on NFkappaB activation and IkappaB-alpha 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-1beta and/or PDTC (inhibits NFkappaB activation). Nuclear translocation of NFkappaB-p65 was analysed by immunofluoresence microscopy. Gene expression of IkappaB-alpha, iNOS, IL-1beta and IL-4 was assessed by real-time qPCR.


RESULTS
Nuclear translocation of NFkappaB-p65 was concomitant with an increase in nuclear fluorescence intensity which reached maximum values at 60 min with IL-1beta (p < 0.001). Dynamic compression or PDTC reduced nuclear fluorescence and NFkappaB nuclear translocation in cytokine-treated constructs (p < 0.001 and p < 0.01 respectively). IL-1beta increased IkappaB-alpha expression (p < 0.001) at 60 min and either induced iNOS (p < 0.001) and IL-1beta (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-1beta. Co-stimulation by dynamic compression and PDTC favoured suppression (IkappaB-alpha, iNOS, IL-1beta) or induction (IL-4) of gene expression.


CONCLUSIONS
NFkappaB 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.
Akanji
O O
OO
Queen Mary University of London, UK.
Sakthithasan
P
P
Salter
D M
DM
Chowdhury
T T
TT
D000818:Animals; D001696:Biomechanical Phenomena; D002417:Cattle; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D020672:I-kappa B Proteins / Q000378:metabolism*; D053583:Interleukin-1beta / Q000494:pharmacology*; D023421:Models, Animal; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism*; D012685:Sepharose; D015398:Signal Transduction; D013314:Stress, Mechanical
D020672:I-kappa B Proteins; D053583:Interleukin-1beta; D016328:NF-kappa B; D000072000:NF-KappaB Inhibitor alpha; D012685:Sepharose