Effects of IGF-1 or/and PDGF-bb on IL-1β-induced inhibition of signaling proteins expression in chondrocytes.

<p>To evaluate the effects of IGF-1 and/or PDGF-bb on IL-1β-induced inhibition of MAPK signaling proteins in chondrocytes, whole cell lysates were probed with antibodies to Shc, Erk1/2 and SOX-9. Primary chondrocytes were either stimulated with 10 ng/ml IL-1β, 10 ng/ml PDGF-bb, 10 ng/ml IGF-1 or combination of both growth factor (5 ng/ml each) or pre-treated for 12 h with 10 ng/ml PDGF-bb, 10 ng/ml IGF-1 or combination of both (5 ng/ml each) followed by 10 ng/ml IL-1β for 24. Untreated cultures showed high expression of Shc, Erk1/2, and SOX-9, while IL-1β alone resulted in inhibition of Erk1/2, Shc as well as SOX-9 production. However, pre-treatment of cultures with IGF-1 or/and PDGF-bb inhibited the adverse effects of IL-1β and chondrocytes produced large amounts of Shc, Erk1/2 and SOX-9 at levels similar to control cultures. The results were confirmed by quantitative densitometry.