Indian Journal of Dermatology
ORIGINAL ARTICLE
Year
: 2006  |  Volume : 51  |  Issue : 4  |  Page : 297--298

Water barrier function: A cosmetic approach


Sanjay Rathi 
 143, Hill Cart Road, Siliguri - 734 001, India

Correspondence Address:
Sanjay Rathi
143, Hill Cart Road, Siliguri - 734 001
India




How to cite this article:
Rathi S. Water barrier function: A cosmetic approach.Indian J Dermatol 2006;51:297-298


How to cite this URL:
Rathi S. Water barrier function: A cosmetic approach. Indian J Dermatol [serial online] 2006 [cited 2021 Dec 6 ];51:297-298
Available from: https://www.e-ijd.org/text.asp?2006/51/4/297/30304


Full Text

The skin acts as a two-way barrier to prevent inward and outward passage of water and electrolytes. It is known that the key elements for water barrier function in skin are provided by the structure of the stratum corneum (SC). Efficacy of SC as a barrier depends on cornified material of keratinocytes and the intercellular material particularly lipid. A two compartment model of the SC as a barrier is currently accepted which includes protein rich- cells and the corneocytes; they are embedded within a continuous lipid rich matrix. Intercellular lipids play an important role in the prevention of trans-epidermal water loss (TEWL). In SC, ceramides are the major lipid constituents and along with neutral lipids, they form broad laminated intercellular sheets, which act as barriers to our environment. Impairment of the water barrier function is responsible for dry and scaly appearance, which dermatologists commonly come across. To keep skin soft and pliable 20-35% of water in SC is needed. That means impairment of water barrier function is a consistent feature in dermatological pathologies like atopic dermatitis, eczema, ichthyosis, etc. and cosmetic skin problems like dry, sensitive, ageing skin, etc.[1],[2]

Yet there are many factors that are responsible for barrier malfunction and are ill-understood. Once the epidermal barrier has been damaged, there must be transmission of signals to the intracellular machinery to initiate repairs. Remoisturization of the skin occurs in four steps: 1) initiation of barrier repair, 2) alteration of surface cutaneous moisture coefficient, 3) onset of dermo-epidermal moisture diffusion and 4) synthesis of intercellular lipids.[3]

The physiologic signal initiating barrier repair through lipid synthesis is TEWL and loss of 1% is sufficient for its synthesis. Hence, TEWL is a valuable parameter in the assessment of barrier function of the SC, usually to predict irritancy of a substance or to contribute to the assessment of clinical disorders. Various methods have been used, but an open chamber gradient-estimation method in the form of evaporimeter is preferred. Many irritants such as detergents and solvents, damage the skin by impairing the barrier function of SC and TEWL measurement has been reported to be more sensitive in assessing such irritancy effects than visual scoring, laser Doppler flowmetry, colorimetry and skin thickness by ultrasound A scan.[2]

Earlier it was thought that moisturizing creams and barrier lipid-containing products might be able to restore altered water barrier function or to decrease skin susceptibility to irritant stimuli. These products are mostly called barrier creams. But the exact definition of barrier cream is not clear in literature. Sometimes it refers to skin products with a high concentration of silicon or moisturizers, (often water-in-oil base, in-order to provide a hydrating and shielding effect on the outer skin layer). But it is now known that when SC is extremely hydrated due to occlusion or prolonged contact with moisturizers, a corresponding swelling of the barrier lipids leading to barrier function impairment may occur. That is why Vapor-impermeable dressing does not produce the expected burst in lipid synthesis because TEWL drops to 0.[4],[5]

To know the efficacy of these products few points may be taken under consideration - a) it should be in a cosmetically acceptable and stable form, suitable to incorporate skin lipids and release them after topical application, b) the efficacy of barrier lipid containing products should be experimentally proved correctly.

With more and more research and understanding of the barrier function of SC the development of stable dermatocosmetic preparations will lead to the development of efficient barrier lipid containing products in the near future. TEWL is currently an important tool to determine, not only protective and preventive properties of products; but also to indicate the effectiveness of topical skin treatment in the case of an abnormal barrier function or barrier restoration.

References

1Archer CB. Functions of the skin. In : Burns T, Breathnach S, Cox N, Griffiths C, editors. Rook's Text book of Dermatology. 7th ed. Blackwell Science: Oxford; 2004. p. 4.1-4.12.
2Roseeuw D, De Paepe K. Water barrier function: What's new? J Eur Acad Dermatol Venereol 2000;14:243-4.
3Jackson EM. Moisturizer: What's in them? How do they work? Am J Contact Dermatol 1992;3:162-8.
4Friberg SE, Ma Z. Stratum corneum lipids, petrolatum and white oils. Cosmet Toilet 1993;107:55-9.
5Draelos ZD. Therapeutic moisturizers. Dermatol Clin 2000;18:597-607.