Humidity-regulated CLCA2 protects the epidermis from hyperosmotic stress

Area of Science:

• Dermatology
• Molecular Biology
• Biochemistry

Background:

• Low environmental humidity exacerbates atopic dermatitis (AD) symptoms.
• The precise mechanisms linking humidity to skin barrier function and AD pathogenesis remain incompletely understood.

Purpose of the Study:

• To investigate the molecular mechanisms by which environmental humidity influences skin inflammation and epidermal integrity.
• To identify key proteins regulated by humidity in the skin and elucidate their role in atopic dermatitis.

Main Methods:

• Utilized a mouse model of atopic dermatitis-like skin disease.
• Performed quantitative proteomics analysis on epidermal lysates from mice under varying humidity conditions.
• Investigated the expression and function of CLCA2 in human AD patient epidermis, organotypic skin cultures, and cultured keratinocytes.

Main Results:

• Increased environmental humidity ameliorated cutaneous inflammation and epidermal abnormalities in AD-like mice.
• Quantitative proteomics identified chloride channel accessory 3A2 (CLCA3A2) as a humidity-regulated protein in mouse epidermis.
• The human homolog, CLCA2, was upregulated in AD patient epidermis and under dry/hyperosmotic conditions, mediated by p38/JNK-ATF2 signaling.
• CLCA2 knockdown impaired keratinocyte cell-cell adhesion and increased apoptosis under hyperosmotic stress.

Conclusions:

• High environmental humidity confers a protective effect against atopic dermatitis by modulating epidermal protein expression.
• CLCA2 upregulation serves as a protective mechanism for keratinocytes against hyperosmotic stress-induced damage.
• These findings provide a mechanistic link between environmental humidity and atopic dermatitis, highlighting CLCA2 as a potential therapeutic target.