Resumen de Potential synergies between matrix proteins and soluble factors on resorption and proteinase activities
A.V. Rousselle, C. Damiens, E. Grimaud, Y. Fortun, M. Padrines, N. Passuti, D. Heymann
Human growth hormone (GH) has recently been found to stimulate osteoclastic resorption, cysteineproteinase and metalloproteinase activities (MMP-2 and MMP-9) in vitro via insulin-like growth factor-I (lGF-I) produced by stromal cells. The present study inve tigated the effects of two extracellular matrix components (vitronectin and type-I collagen) on hGHand hIGF-1-stimulated osteoclastic re orption and proteinase activities in a rabbit bone cell model. After 4 day of rabbit bone cell culture on dentin slices with vitronectin coating, hGH and hIGF-1 stimul ated bone resorption and hlGF-1 upmodulated cysteine-proteinase activities. MMP-2 expression (but not resorption , cathepsin or MMP-9 activities) was upmodulated by hGH and hIGF-1 on dentin slices coated with type I collagen as compared to those without coating. Then, vitronectin was synergistic with hIGF-1 in the regulation of cysteine-prote in ase production whereas collagen howed synergy with hGH and hIGF-1 in the regulation of MMP-2 production. Anti-avID tota lly abolished the effect of hGH and hIGF-1 on metalloproteinase relea e, but had no influence on cathepsin release. The results suggest that cysteine-p roteinase modulation is not mediated by avl33 integrin (strongly expressed on osteoclastic surface) whereas the resorption process and metalloproteinase modulation are clearly · mediated by this integrin. Our finding about the collagen coating also suggests that hGH- and hIGF-1-stimulated MMP-2 activ it y are mediated, along with aviD integrin, by another adhesion molecule.
