The importance of skin barrier function

Abstract

The prevalence of atopic eczema and other dry skin conditions is increasing, suggesting that environmental factors are of major importance in its aetiology. The stratum corneum provides the epidermal barrier to water loss from the skin. This barrier is analogous to a brick wall, with the corneocytes acting as the bricks and the lamellar lipids as the mortar. This barrier permits the retention of water within the corneocytes and as a result they swell up preventing the formation of cracks between them. Derangements of the epidermal barrier are central to the development of all dry skin conditions, in particular atopic eczema and contact dermatitis. Changes in the epidermal lipids in atopic eczema result in water loss from the stratum corneum. Cracks develop allowing the penetration of irritants and allergens which trigger the development of eczematous lesions. The use of any soap product removes further lipids from the stratum corneum and causes further deterioration of the epidermal barrier. Emollients provide an oily film over the surface of the skin which traps water, swelling the stratum corneum and closing the cracks, thus restoring the epidermal barrier. To have maximum effect, a complete emollient therapy regimen consisting of an emollient cream/ointment, an emollient bath oil, and an emollient soap substitute should be used. We are now starting to understand why emollients are such effective therapy. However, despite their efficacy, emollients remain a very under-used therapy in the community. Improved patient education and an appreciation of the importance of cosmetic acceptability to the patient will enhance the use, and thereby the efficacy, of emollients.

Key Words:

• Atopic eczema
• Epidermal barrier
• Complete emollient therapy