From the Research
Introduction to Skin Layers
The skin is composed of several layers, with the epidermis being the outermost layer, followed by the dermis, and finally the hypodermis. The epidermis itself is divided into several sublayers, including the stratum corneum, stratum granulosum, stratum spinosum, and stratum basale.
Conditions Affecting the Skin Layers
Atopic Dermatitis
Atopic dermatitis is a condition that affects the skin's barrier function, particularly in the stratum corneum [(1,2,3,4)]. The depletion of lipids in the stratum corneum, including ceramides, free fatty acids, and cholesterol, leads to a compromised skin barrier. This allows environmental allergens to penetrate the skin, triggering an immune response and inflammation.
Psoriasis
Psoriasis is another condition that affects the skin's barrier function, with changes in the lipid composition and epidermal differentiation leading to a disturbed skin barrier [(1,2,4)]. The stratum corneum is particularly affected, with an abnormal lipid profile and impaired barrier function.
Treatment and Management
Topical Therapies
Topical therapies, such as moisturizers and lipid substitutes, can help repair the skin's barrier function in conditions like atopic dermatitis and psoriasis [(1,3)]. These therapies aim to replenish the depleted lipids in the stratum corneum and improve the skin's natural barrier function.
Systemic Therapies
Systemic therapies, such as immunomodulators and biologics, may also be used to manage conditions like atopic dermatitis and psoriasis [(2,4)]. These therapies target the underlying inflammatory processes and can help reduce symptoms and improve skin barrier function.
Differentials and Caveats
Filaggrin Mutations
Filaggrin mutations can affect the skin's barrier function, particularly in individuals with atopic dermatitis [(3,4)]. Filaggrin is a protein that helps aggregate keratin filaments and is involved in the formation of the cornified envelope.
Ageing
Ageing can also affect the skin's barrier function, with changes in the skin's structure and immune composition leading to decreased barrier immunity 5. This can increase the risk of skin infections and cancer in older adults.
Conclusion
In conclusion, conditions like atopic dermatitis and psoriasis affect the skin's barrier function, particularly in the stratum corneum. Understanding the underlying mechanisms and using targeted therapies can help improve skin barrier function and manage these conditions.