Methods to Assess the Protective Efficacy of Emollients against Climatic and Chemical Aggressors

Abstract

Exposure to harsh environmental conditions, such as cold and dry climate and chemicals can have an abrasive effect on skin. Skin care products containing ingredients that avert these noxious effects by reinforcement of the barrier function can be tested using in vivo models. The objective is to use in vivo models to assess the efficacy of emollients in protecting skin against climatic and chemical insults. A first model used a stream of cooled air to mimic cold wind. A second used sodium lauryl sulfate (SLS) under patch as chemical aggressor. In the model with simulated wind exposure, the untreated exposed area had a significant decrease in hydration. In contrast, application of an emollient caused a significant increase in hydration that was maintained after wind exposure. In the second model with SLS exposure, application of a barrier cream before SLS patch significantly reduced the dehydrating effect of SLS with a significant difference in variation between both areas. Application of the cream reduced TEWL, indicative of a physical reinforcement of the skin barrier. The two presented test methods, done under standardized conditions, can be used for evaluation of protective effect of emollient, by reinforcing the barrier function against experimentally induced skin dehydration.

The effects of season and weather on healthcare utilization among patients with atopic dermatitis

“…Experimentally, subjective itch intensity is higher among both AD and non‐AD individuals after topical histamine challenge in lower temperatures . Similarly, both ambient and skin temperatures have been shown to correlate with transepidermal water loss and skin hydration . Our results suggest that lower temperature results in clinical flares among AD patients.…”

Influence of exposure to summer environments on skin properties

“…reported that during skiing, low temperatures lead to shrunken capillaries, skin redness decreases and the changes in cheeks are more especially pronounced compared with those in the dorsal hand. Moreover, several studies concluded that low temperatures result in decreased hydration levels and TEWL . Another investigation related to low humidity reported that such conditions decrease hydration levels, skin elasticity, and TEWL during prolonged exposure, and increase fine wrinkles, TEWL, and irritation during short periods of exposure …”

“…Moreover, several studies concluded that low temperatures result in decreased hydration levels and TEWL. [8][9][10] Another investigation related to low humidity reported that such conditions decrease hydration levels, skin elasticity, and TEWL during prolonged exposure, and increase fine wrinkles, TEWL, and irritation during short periods of exposure. 8,[11][12][13][14] In this study, we performed the first trial to investigate changes in the properties of human skin in response to exposure to an actual summer environment (hot) and aimed to investigate the impact of exposure to an outdoor environment during summer on skin properties, such as skin hydration levels, sebum secretion, TEWL, pH, and greasiness of the face (forehead and cheek) and forearm regions; The specific test sites that represent the skin characteristics of T zone (high sebum-secreting area such as forehead and nose), U zone (low sebum-secreting area such as cheeks) and body site were selected for the measurements.…”

4-Hexyl-1,3-phenylenediol, a nuclear factor-κB inhibitor, improves photodamaged skin and clinical signs of ageing in a double-blinded, randomized controlled trial

“…These conclusions are supported by two additional double-blind, placebo-controlled studies, which have been recently presented and concluded that 4-hexyl-1,3-phenylenediol significantly improved photodamaged skin and clinical signs of ageing. 37,38 Taken together, these data demonstrate that 4-hexyl-1,3-phenylenediol reduced the signs of skin ageing, while improving overall skin health, by inhibiting the NF-jB pathway and restoring the production of skin ECM proteins to a normal level.…”