[Action of an extract of Vanda coerulea on the senescence of skin fibroblasts]. / Action d'un extrait de Vanda coerulea sur la sénescence de fibroblastes cutanés.

The family of the orchids to date is poorly studied as a potential source of molecules with biological activity. The phytochemical analysis of extracts of Vanda coerulea stems (Orchidaceae), the isolation and the purification of the secondary metabolites realized by CLHP followed with high-resolution mass spectrometry and mono and two-dimensional nuclear magnetic resonance made it possible to identify the joint presence in an orchid of three stilbenoïds i.e, imbricatin, methoxycoelonin and gigantol. By flow cytometry, it is shown that the replicative senescence of human normal skin fibroblasts involves a reduction in the number of cells in phase S. A proteins chips technology dedicated to cell cycle proteins makes it possible to correlate this decrease of the number of cells in phase S to a decrease in cyclin E and cyclin dependant kinase 2, cdk2. The treatment by an ethanolic extract of stems of Vanda coerulea titrated in the three stilbenoids restores the percentage at an equivalent rate to that of young cells and the rate of cyclin E and, cdk2, thus bringing a beginning of explanation of their mechanism. These activities let predict an interesting potential as active ingredients to fight against the visible signs of cutaneous ageing.

Elastokine-mediated up-regulation of MT1-MMP is triggered by nitric oxide in endothelial cells.

Membrane-type I matrix metalloproteinase (MT1-MMP) has been previously reported to be up-regulated in human microvascular endothelial cell-1 line (HMEC) by elastin-derived peptides (elastokines). The aim of the present study was to identify the signaling pathways responsible for this effect. We showed that elastokines such as (VGVAPG)(3) peptide and kappa elastin induced nitric oxide (NO) production in a time-, concentration- and receptor-dependent manner as it could be abolished by lactose and a receptor-derived competitive peptide. As evidenced by the use of NO synthase inhibitors, elastokine-mediated up-regulation of MT1-MMP and pseudotube formation on Matrigel required NO production through activation of the PI(3)-kinase/Akt/NO synthase and NO/cGMP/Erk1/2 pathways. Elastokines induced both PI(3)-kinase p110gamma sub-unit, Akt and Erk1/2 activation, as shown by a transient increase in phospho-Akt and phospho-Erk1/2, reaching a maximum after 5 and 15 min incubation, respectively. Inhibitors of PI(3)-kinase and MEK1/2 suppressed elastokine-mediated MT1-MMP expression at both the mRNA and protein levels, and decreased the ability of elastokines to accelerate pseudotube formation. Besides, elastokines mediated a time- and concentration-dependent increase of cGMP, suggesting a link between NO and MT1-MMP expression. This was validated by the use of a guanylyl cyclase inhibitor, a NO donor and a cGMP analog. The guanylyl cyclase inhibitor abolished the stimulatory effect of elastokines on MT1-MMP expression. Inversely, the cGMP analog, mimicked the effect of both elastokines and NO donor in a concentration- and time-dependent manner. Overall, our results demonstrated that such elastokine properties through NO and MT1-MMP may be of importance in the context of tumour progression.