From experimental design to functional gene networks: DNA microarray contribution to skin ageing research

Skin biological responses to urban pollution in an ex vivo model

The skin epidermis is continuously exposed to external aggressions, including environmental pollution. The cosmetic industry must be able to offer dedicated products to fight the effects of pollutants on the skin. We set up an experimental model that exposed skin explants maintained in culture to a pollutant mixture. This mixture P representing urban pollution was designed on the basis of the French organization 'Air Parif' database. A chamber, called Pollubox®, was built to allow a controlled nebulization of P on the cultured human skin explants. We investigated ultrastructural morphology by transmission electron microscopy of high pressure frozen skin explants. A global transcriptomic analysis indicated that the pollutant mixture was able to induce relevant xenobiotic and antioxidant responses. Modulated detoxifying genes were further investigated by laser micro-dissection coupled to qPCR, and immunochemistry. Both approaches showed that P exposure correlated with overexpression of detoxifying genes and provoked skin physiological alterations down to the stratum basale. The model developed herein might be an efficient tool to study the effects of pollutants on skin as well as a powerful testing method to evaluate the efficacy of cosmetic products against pollution.

Purple tulip extract improves signs of skin aging through dermal structural modulation as shown by genomic, protein expression and skin appearance of volunteers studied

BACKGROUND

Purple tulip extract is a rich source of flavonoids which are powerful antioxidants and can hence be considered as an ideal candidate for use in skin care products.

AIMS

We aimed to evaluate the effects of purple tulip extract on skin quality and to determine its molecular modes of interaction.

METHODS

A pangenomic study on human skin fibroblasts was carried out to analyze multiple changes in gene expression. Ex vivo studies of human skin explants exposed to ultraviolet (UV) irradiation or H₂ O₂ were performed to assess modulations of protein expression. Finally, a clinical assay was carried out to evaluate the efficacy of purple tulip extract on skin appearance and condition of aged women.

RESULTS

Genetic modulation analyses led us to infer the induction of many biological functions including cell differentiation, proliferation, migration, inflammatory responses, and matrix remodeling. The ex vivo studies revealed an enhancement of the collagen network and increased expression of glycosaminoglycans (GAG), fibronectin, and collagen VI. Finally, the clinical study highlighted the potential anti-aging properties of the purple tulip extract which decreased the relaxation of the oval face and improved skin elasticity after 28 days of treatment. Significant reductions of the length and depth of the nasolabial wrinkles were also observed.

CONCLUSION

Our genomics data on the effect of purple tulip extract on the ex vivo UV-challenged skin showed that genes responsible for, among others, the upkeep of the skin, such as collagen induction, immune cell proliferation, and epidermal repair, were all up-regulated. More importantly, the clinical study corroborated these data by the visible and measurable effects of the topical purple tulip extract on the aged skin of 22 women, further demonstrating the beneficial impact of the extract on aged skin.

Personalized skincare: from molecular basis to clinical and commercial applications

Individual responses of human skin to the environmental stress are determined by differences in the anatomy and physiology that are closely linked to the genetic characteristics such as pigmentation. Ethnic skin phenotypes can be distinguished based on defined genotypic traits, structural organization and compartmentalized sensitivity to distinct extrinsic aging factors. These differences are not only responsible for the variation in skin performance after exposure to damaging conditions, but can also affect the mechanisms of drug absorption, sensitization and other longer term effects. The unique characteristics of the individual skin function and, particularly, of the ethnic skin type are currently considered to shape the future of clinical and pharmacologic interventions as a basis for personalized skincare. Individual approaches to skincare render a novel and actively growing area with a range of biomedical and commercial applications within cosmetics industry. In this review, we summarize the aspects of the molecular and clinical manifestations of the environmental stress on human skin and proposed protective mechanisms that are linked to ethnic differences and pathophysiology of extrinsic skin aging. We subsequently discuss the possible applications and translation of this knowledge into personalized skincare.