Evaluation of molecules or extracts modulating seborrhea and its consequences, using normal human culture of sebocytes and keratinocytes, skin explants models and in vivo methods: a case study.

Skin produces sebum through sebocytes. Hyper-seborrhea creates conditions for the development of inflamed cutaneous alterations through bacteria colonization triggering dead cell accumulation and pro-inflammatory mediator release. Study of sebum production, its modulation, and its consequences requires complementary in vitro models in order to evaluate the effect of molecules on cell metabolisms. Clinical studies need to be performed to confirm in vitro results. Effects of phenylpropanoids, obtained by elicitation and purification from plant cell culture of Syringa vulgaris (CCSV), were studied on sebocytes, keratinocytes, and explants, all derived from normal human skins. Normal human sebocytes (NHSs) expressed markers such as cytokeratin-7, cytokeratin-4, and perilipin-2 (PLIN-2) (1); the latter being colocalized with lipid droplets. Lipid droplets clearly appeared and their size increased rapidly when lipogenic agents were used. NHS, normal human keratinocytes (NHK), and explants reacted to presence of bacterial fragments which trigger pre-inflammatory mediator release. CCSV reduced lipid storage and release of pre-inflammatory mediators in NHS, NHK and explants. CCSV also reduced P. acnes growth and triggered beta-defensin-2 and cathelicidin synthesis by NHS, two natural antimicrobial peptides. On volunteers, sebum production, inflamed blemishes, and retentional lesions were significantly reduced after 1 month treatment with CCSV.