Moisturizers are used in various types of dry skin disorders, but also by people with healthy skin. It is not unusual that use of moisturizers is continued for weeks, months, or even years. A number of moisturizers have been shown to improve the skin barrier function, while others to deteriorate it, but the reason for observed effects remains unknown. Further understanding of the mechanism by which long-term treatment with moisturizers influences the skin barrier would have clinical implications, as barrier-deteriorating creams may enhance penetration of allergens or irritants and predispose to dry skin and eczema, while barrier-improving ones could reduce many problems. The present research combined non-invasive techniques with analyses of skin biopsies, allowing studies of the epidermis at molecular and cellular level. Test moisturizers were examined on healthy human volunteers for their effect on the skin barrier, with regard to such factors as pH, lipid type, and presence of a humectant, as well as complexity of the product…
Contents
Introduction
The structure and barrier function of the skin
Skin structure
Stratum corneum as the skin barrier
Intercellular lipids of the stratum corneum
Enzymes and non-enzymatic regulatory proteins of the skin barrier
Corneocyte formation
Desquamation
Formation of extracellular lipid matrix of stratum corneum
Nuclear hormone receptors and lipoxygenases
Skin pH
Moisturizers and the skin barrier
Chemistry of moisturizers
Methods used for evaluation of the skin barrier function
Aim of the research
Materials and Methods
Volunteers
Test moisturizers
Experimental design
Paper I
Paper II
Papers III and IV
Evaluations
Calculations and statistics
Results
Paper I
Paper II
Paper III
Paper IV
Discussion and conclusions
Choice of test moisturizers
Effect of 7-week use of test preparations on the skin barrier
Possible explanations of observed effects
Lipids
Water
Emulsifiers and polymers
Humectants
Occlusion
pH
Molecular changes induced by Hydrocarbon and Complex creams
Effect of Hydrocarbon cream on the skin barrier
Nuclear receptors and lipoxygenases
Enzymes and proteins involved in keratinocyte differentiation and desquamation
Conclusions
Future perspectives
Acknowledgments
References
Author: Buraczewska, Izabela
Source: Uppsala University Library
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