Relationship between lip skin biophysical and biochemical characteristics with corneocyte unevenness ratio as a new parameter to assess the severity of lip scaling

Abstract

Objective Lip skin dryness and chapping are major concerns related to lip skin care in many populations. The distinctive features of lip skin, such as the low water‐holding capacity and weak skin barrier, are strongly associated with these problems; however, few studies have examined lip skin characteristics and the mechanisms underlying these issues. This study was conducted to identify the biophysical properties of dry lip skin and molecular targets affecting lip skin physiology. Methods Skin hydration, transepidermal water loss and lip skin scaling were evaluated in 40 female subjects. Skin scaling was assessed as a percentage area divided into five categories (G0, G1, G2, G3 and G4) according to the thickness level of tape‐stripped corneocytes. The activities and amounts of proteases, cathepsin D and bleomycin hydrolase were measured as markers for the desquamation process and skin hydration, respectively. Results Skin hydration showed a significantly positive correlation with the percentage area of evenly thin corneocytes (G0) and negative correlations with the percentage areas of slightly thick to severely thick corneocytes (G1‐G4). The corneocyte unevenness ratio (CUR) was calculated by dividing the sum of the G1, G2, G3 and G4 values with the G0 value. The CUR was significantly negatively correlated with skin hydration, suggesting that CUR is a new parameter representing the severity of lip scaling. Subjects with lower hydration and higher CUR had higher bleomycin hydrolase activity and lower cathepsin D activity, respectively, than subjects with higher hydration and lower CUR. Conclusion Our study revealed a correlation between lip skin hydration and severity of lip scaling and verified the association of protease activity with the hydration and chapping state of lip skin. These observations provide a basis for further studies of the persistent problem of lip skin dryness and chapping.

Low-flux electron diffraction study on the intercellular lipid organization in the human lip stratum corneum

“…The frequent appearance of ICLs with low crystallinity may cause chapping of the lips triggered by dehydration of the lip SC, since water content is negatively correlated with lip roughness [11,12].…”

“…Morphological and functional inadequacies of lip SC are believed to make the lip more prone to severe chapping, resulting in hard-to-cure multilayer desquamation, cracking, and bleeding. Moreover, the water content is lower in chapped lips than in healthy lips, and there is a negative correlation between lip SC hydration and the severity of chapping [11][12][13].…”

Exfoliative Cheilitis More than an Aesthetic Problem: Case Report

“…A correlation between vermilion hydration and the severity of its desquamation has been reported (18), since it has unique characteristics because it is found on the border of the mucous membrane and facial skin (19). Unlike the skin of the rest of the body, it comprises a thin stratum corneum, has no hair or sweat glands, has a greater transepidermal water loss and a lower water content than the skin of the cheeks (20).…”

The smile and emotional expression: practical application of a lip and perioral assessment scale

“…46 Other issues relating to lip skin quality, such as dryness and flaking, can occur at any age and may be more related to physical (high transepidermal water loss) and environmental (cold, wind) factors than aging. 47…”