Emollients in Atopic Skin Care K.Pytkowska, J.Arct, S.Majewski Academy of Cosmetics and Health Care, Warsaw, Poland

Skin in AD Impaired barrier function Inflammation Secondary factors deteriorating barrier condition Main factor influencig bad epidermal barrier condition are: Changes of s.c. lipids composition Disorders of epidermal cell differentiation mutation of fillagrin encoding gene – low NMF level, changes of s.c. pH

Skin in AD Disturbances in lipid composition and intercellular cement organization Disturbances of pro-lipids in s.g. lamellar bodies Disturbances of enzymatic processes in s.g.-s.c . borderline region Improper formation of corneocyte envelope Atypical s.c. lipids composition– changes in fatty acids profile, lower ceramide level „Rigid” gel phase dominates in s.c. cement, loose corneocyte packing

Skin care in AD Washing Solutions: Hard water indirectly disturb the barrier Mechanism: exscessive use of surfactants („more effective washing”) Solutions: Elimination of SLES from cleansing products dedicated to the atopic skin care Increase of refattening agents concentration in cleansing products Addition of starch or other HMW hydrophiles to the formulation or bath

Atopic skin care – most frequent guidelines Avoiding soap in favour of syndets with acidic pH Avoiding washing formulations based on surfactants in favour of cleansing emollients

The most frequent guidelines Regeneration of the epidermal barrier using emollients , and the emollients are most often selected by a trial and error method. Avoiding cosmetics of strong occlusivity (continuous occlusion) Continuous occlusion Impairs regeneration of damaged epidermal barrier (ceramide synthesis inhibition) Increase of the skin surface pH (mechanism - ?, multi-factor probably) Mogą sprzyjać rozwojowi patogenów No clinical trials evaluating the influence of physicochemical form and/or lipid level.

Emollients and the epidermal barrier Effects: Decrease of TEWL Itch suppression (stress reduction, avoiding excoriation etc.) Mechanism of action Complementation or modification of the natural lipid barriers of the skin Superficially In the s.c. cement Biological activity leading to the normalizing of the barrier restoration EFAs and some other PUFAs and their derivatives, some sphingolipids

Emollients and the epidermal barrier Evaluation of barrier regeneration process Models: SLS barrier damage (washing out of superficial lipids, selective sterol extraction, SLS – s.c. lipids interactions, in vivo - often inflammation) Acethone barrier damage (washing out of superficial lipids, partial s.c. lipid extraction)

Emollients and the epidermal barrier Evaluation of the barrier recovery Results: Hydrocarbons– recovery enhancement (via water content recovery, probably) Sterols improve barrier condition after SLS damage Pseudoceramides – direct s.c. cement restoration (no biological effect) So called „physiological lipids” (CER:CHOL:FFA=3:1:1, ) – restoration of normal pathway of recovery after acute barrier damage, penetration and recovery of lamellar bodies lipid composition is possible – direct and indirect activity

EFA cosmetic activity Physicochemical activity Biological activity Direct influence on the structure of s.c. intercellular cement LA supplementation in AD skin Biological activity Eicosanoid synthesis PPAR activation

EFA in AD Oral supplementation N-6 EFA: barrier function restoration or no significant effect N-3 EFA: very slight effect or no effect Topical application (emulsions containing up to 20% EFA-rich oils) Efficient AD suppression Better effect or no significant difference vs. „regular”, no EFA-containing emollients

„Regular” emollients and other cosmetics Petrolatum-, „physiological lipids”-, nanolipid- and humectant-based emulsions were evaluated Most frequently evaluated parameters: Skin condition (flakiness, redness) Subjective parameters (itching), SCORAD or similar indexes Self-evaluation of skin condition TEWL, electrical parameters (indirect moisturization evaluation), superficial lipid level – less frequently Emollient-rich and humectant-rich emulsions improve skin condition in AD No significant difference in TEWL reduction after a long-term application

„Regular” emollients and other cosmetics Product groups Studies Urea-containing products Loden 2001 (25) , Loden 2002 (26) Glycerine-containing emulsions Loden 2001 (25), Loden 2002 (26), Matsumoto 2005 (27), Breternitz 2008 (28), Kikuchi 2008 (29) Hydrophilic anti-inflammatory ingredient containing emulsions Patrizi 2008 (30) Moisturising emulsions containing hydrophilic moisturising ingredients Vilaplana 1992 (31), Tabata 2000 (32), Loden 2003 (33), Matsumoto 2007 (34) w/o emulsions Lucky 1997 (35) “Physiological lipids”-containing emollients Mao-Qiang 1995 (22), Chamlin 2001 (36) , Berardesca 2001 (37), Sugarman 2008 (38) Emulsions with siloxanes Hagstromer 2006 (39),

„Regular” emollients and other cosmetics Normalization of barrier function and water content in epidermis is of the greatest importance for therapeutic effect Good effects: Glicerin – prevents s.c. lipid phase transition in the low-humidity conditions, hygroscopicity, osmotic activity Wet wrapping – decrease of water gradient Synthetic semi-permeable membranes decreasing TEWL – evaluated in the SLS damaged barrier model

Future developement Conscious linking both: direct- and indirect-active (biologically active) raw materials in the formulation. Increase of hydrophilic raw materials significance Better sensory parameters o/w emulsions as preferred ones „Light” emollients „Nanolipids” containing formulations

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