Does an atopic constitution exist?

Let's begin by discussing the skin barrier. What is most importantly discussed regarding the skin barrier is the epidermal barrier, and among that, the stratum corneum, or SC barrier. As you all well know, from the basal layer, the lowest layer of the epidermis, keratinocytes gradually differentiate, flatten, and solidify the physical barrier with their characteristic mortar and brick-like structure.

While skin diseases often originate from internal conditions, restoring the skin's own function is also very important.

Appropriate sweat secretion is important for the composition of the skin barrier, but various other factors are also involved.

• skin pH
• normal flora
• lipid production and emollient effect
• tight junction
• desquamation process

Today, we'll delve into filaggrin, which is considered quite important among these factors.

Role of Filaggrin

It is known to provide physical support, enabling keratinocytes to align tightly like a brick wall. At the final stage of keratinocyte differentiation, this filaggrin breaks down into free amino acids. These free amino acids are collectively referred to as natural moisturizing factors, or NMF.

When NMF is insufficient, the skin cannot retain moisture, leading to increased transepidermal water loss (TEWL), easily dry skin, and a weakened skin barrier. The term NMF, frequently used in skincare cosmetic advertisements, originates from this context.

Filaggrin and Atopic Dermatitis

Many studies are being conducted on the importance of filaggrin, particularly in atopic dermatitis, to the extent that it's difficult to discuss atopic dermatitis without mentioning filaggrin. Research indicates that in atopic dermatitis, decreased skin barrier function is coupled with insufficient filaggrin production. Furthermore, there are genetic differences in filaggrin production.

This refers to variations in the genes involved in filaggrin production. If you look at the diagram above, the number of filaggrin repeats produced varies from 10 to 12 repeats depending on the individual. This means some individuals produce 12 repeats at once, while others produce 10.

Conclusion

1. Remember filaggrin, which plays a crucial role in the skin barrier, especially within the epidermal barrier.
2. Filaggrin is important in itself, but its breakdown products also act as natural moisturizing factors (NMF).
3. The ability to produce filaggrin varies due to genetic mutations, and these differences are linked to the likelihood of skin conditions like atopy.
4. An atopic predisposition exists (?)