The weak rate of sphingolipid biosynthesis shown by basal keratinocytes isolated from aged vs. young donors is fully rejuvenated after treatment with peptides of a potato hydrolysate

Synopsis A new study was carried out to bring more information on the effect of the potato proteins ferment. Basal keratinocytes obtained from freshly excised skin samples of two groups of five donors, a young one (25–36-year-old) and an aged one (59–70-year-old) were established in culture. The results showed a downward trend in the content of all lipid fractions in untreated keratinocytes of aged donors when compared with young ones. We found major differences in the response of keratinocytes to potato proteins ferment treatment between young and old donors. Whereas the lipid content of cells from young donors increased either moderately or actually decreased in some cases in comparison with the untreated controls, the lipid biosynthesis was strongly stimulated in aged donors’ keratinocytes whose lipid contents globally became close to those found in young donors. However, the changes elicited by potato proteins ferment treatment were not seen at the same extent for all lipid classes. Cholesterol content increased up to three-fold and alpha-hydroxy fatty acids were augmented up to seven-fold, whereas the increase in normal fatty acids was quite moderate. In sphingolipids labelled by incubation of keratinocytes in culture medium containing [14C]-serine, ceramides and glucosylceramides in cells from aged donors showed the highest uptake of radioactivity, with somewhat less incorporation in sphingomyelin and gangliosides. Therefore, it seems that potato proteins ferment has a much more potent stimulatory activity on the lipid biosynthesis of basal keratinocytes of aged donors, thereby normalizing the cellular lipid content that obviously decreases along with ageing. Although our results were obtained only with basal keratinocytes in this study, potato proteins ferment could be beneficial to maintain an efficient skin barrier in ageing people, provided that the peptides can get through to the basal membrane upon topical application. Resume Une nouvelle etude a ete effectuee pour obtenir davantage d’informations sur l’effet de l’hydrolysat de pomme de terre. Des keratinocytes basaux ont eteetablis en culture a partir d’echantillons de peaux fraichement prelevees sur deux groupes de 5 donneurs, un jeune (25 a 36 ans) et un âge (59 a 70 ans). Les resultats ont montre une tendance a la baisse du contenu cellulaire des keratinocytes non traites pour toutes les fractions lipidiques chez les donneurs âges compares aux jeunes donneurs. Nous avons trouve des differences majeures entre les donneurs jeunes et âges dans la reponse de leurs keratinocytes au traitement par l’hydrolysat de pomme de terre. Alors que le contenu lipidique des cellules des donneurs jeunes a augmente moderement ou a meme diminue dans quelques cas par rapport aux controles non traites, la biosynthese des lipides a ete fortement stimulee dans les keratinocytes de donneurs âges dont les contenus lipidiques sont devenus proches de ceux des donneurs jeunes. Le cholesterol a augmente jusqu’a trois fois et les acides gras alpha-hydroxyles ont ete multiplies jusqu’a sept fois, alors que l’augmentation des acides gras normaux a ete tres moderee. Avec la [14C]-serine, les ceramides et les glucosylceramides des cellules de donneurs âges ont montre l’incorporation de radioactivite la plus elevee, avec plutot moins d’incorporation dans la sphingomyeline et les gangliosides. Par consequent, il semble que L’hydrolysat de pomme de terre ait une activite stimulante sur la biosynthese lipidique beaucoup plus puissante sur des keratinocytes de donneurs âges, normalisant ainsi le contenu cellulaire en lipides qui diminue comme nous le montrons de maniere evidente avec l’âge. Bien que nos resultats soient limites aux keratinocytes basaux L’hydrolysat de pomme de terre pourrait avoir un effet benefique pour maintenir une barriere cutanee efficace chez les personnes âgees, pour autant que les peptides puissent atteindre la membrane basale apres application topique.