Atopy Causes: Skin Barrier Function and pH Conditioning
Table of Contents
The topic of pH in the skin alone could fill an entire book. The skin is known to function best in a slightly acidic state. Let's take a closer look.
pH Gradient of the Epidermis
A pH gradient is formed within the epidermal layers. Specifically, the SC layer is highly refined to be close to slightly acidic, while the layers beneath it are closer to pH 7.
Image source: Desquamation: It Is Almost All About Proteases
The pink-colored structures are corneodesmosomal proteins that adhere keratinocytes to each other. Their distribution also varies by layer, making the regulation of epidermal differentiation crucial.
Intercellular Connections of Keratinocytes and Desquamation
The intercellular connections of keratinocytes, known as desmosomes, and the proteins involved, physically hold the cells tightly together. Incidentally, when these desmosome bonds break, causing keratinocytes to shed, this process is called desquamation (the shedding of dead skin cells).
Content source: Wohlrab, J., Gebert, A., & Neubert, R. H. H. (2018). Lipids in the Skin and pH. Current Problems in Dermatology, 64–70. doi:10.1159/000489519
Upon closer examination of the SC layer, it's evident that various enzymes have different optimal pH ranges for activation. Changes in pH act as a trigger for enzyme activity, allowing them to function under appropriate conditions.
Role of Kallikrein
Kallikrein plays a role in dissolving the desmosomes between keratinocytes, leading to their shedding. Excessive activation can lead to weakening of the skin barrier.
Danby, S. G., & Cork, M. J. (2018). pH in Atopic Dermatitis. Current Problems in Dermatology, 95–107. doi:10.1159/000489523
Consequences of Increased pH
Situations where pH increases due to various causes can be categorized into four groups:
- Antimicrobial defense is inhibited.
- Skin barrier function is compromised.
- Inflammation occurs.
- Itching develops.
pH Changes in Atopic Patients
According to studies comparing pH in atopic patients with normal skin, it can be observed that pH is elevated in atopic patients. This leads to a weakened skin barrier and a recurring chronic inflammatory course.
Summary
- From the skin's deeper layers towards the stratum corneum, pH exhibits a gradient across layers and is very precisely regulated.
- When the precision of skin pH regulation decreases, it typically manifests as an increase in pH.
- This leads to the exacerbation and recurrence of various skin symptoms.
- Use mildly acidic cleansers, toners, etc.