Quantitative assessment of lactate and progerin production in normal human cutaneous cells during normal ageing: effect of an Alaria esculenta extract.

Anti-ageing products are of a great importance in cosmetic fields. However, even if numerous strategies have been proposed to fight against skin ageing or to minimize its aesthetic impact since the beginning of the 'scientific cosmetology' era, the products basing their efficacy on the observation of pathological situations are rare. The most obvious pathology linked to the ageing of skin (notably) consists in the Hutchinson-Gilford Progeria Syndrome (HGPS), a rare disorder characterized by accelerated ageing and early death. In this disease the lamin A, a protein participating (with others lamins) in the formation of the nuclear lamina and implicated in nuclear stability, chromatin structure and gene expression, is present in a truncated version called progerin. In this study, we have examined the lactate and the progerin production of human normal cutaneous cells issued from subjects of different ages. Using a sensitive and specific progerin ELISA assay developed in house, we so provide the first quantitative demonstration of an increased progerin expression and lactate production in skin during ageing. Moreover, we have also demonstrated that in the selected experimental conditions, it was possible to down-regulate the progerin production of aged cells by using an algae extract. As this extract, an Alaria esculenta extract, could be used in cosmetic formulations, we suggest that a better understanding of the skin pathologies could be a useful tool in developing efficient active compounds, attractive for but not limited to cosmetic purposes.

SECMA 1, a mitogenic hexapeptide from Ulva algeae modulates the production of proteoglycans and glycosaminoglycans in human foreskin fibroblast.

SECMA 1 is a polypeptide purified from a green algeae of the Ulva species by several gel chromatographies, showing the following sequence (Glu-Asp-Arg-Leu-Lys-Pro). In order to determine the effect of SECMA 1 on human skin fibroblasts extracellular matrix, proteoglycans (PGs) and glycosaminoglycans (GAGs) were assayed after 24 h incubation of 20 day-old foreskin fibroblasts at the 2nd passage. The results revealed that most of [35S]sulphate was associated with fibroblast membranes, which contained (67%) of the total de novo synthesized sulphated PGs, in two distinct forms: one hydrophilic (39%), and one hydrophobic (28%). The remaining 'matrix' retained 5% of proteoglycans. The remaining 35S-label may represent the free label in the cytosol. After 24 h incubation of skin fibroblasts with different concentrations of SECMA 1 (2, 4 and 10 micrograms/ml), the [35S]sulphate incorporation into PGs of Salt-extract, sodium deoxycholate (DOC) extract and Guanidine hydrochloride (GuA-HCl)-extract was increased significantly (P < 0.005) with 4 micrograms/ml, as compared to untreated control. The most effective concentration (4 micrograms/ml) increased the different [35S]sulphate PGs extracts (NaCl, DOC and GuA-HCl) by respectively (66; 17 and 75%). The relative contents of iduronic and glucuronic acid in the GAG produced by skin fibroblasts were estimated. No effect of SECMA 1 on the incorporation of [35S]sulphate into Heparan sulphate was found. The incorporation of [35S]sulphate into (chondroïtine sulphate + heparan sulphate) and (chondroïtine sulphate + dermatan sulphate) was increased by respectively 37% and 11% by SECMA 1 (4 micrograms/ml).