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Barrier function


The barrier function is ensured by the epidermis. It keeps the skin hydrated, especially by avoiding its evaporation, and protects the skin from external aggressions.

Keratinocytes: main actors of the barrier function

During their differentiation, keratinocytes will produce various constituents to ensure the barrier function of the skin.

The keratinocytes of the spinous layer and of the granular layer are connected to each other by desmosomes which gives them a thorny appearance. This great cohesion gives them a very strong mechanical resistance.

In keratinocytes of the granular layer, there are keratohyaline granules which contain profilaggrin, and Odland’s lamellar bodies which are loaded with lipids.

The keratinocytes of the stratum corneum, called corneocytes, have reached their final level of differentiation. They no longer have nuclei or organelles but are loaded with keratin filament embedded in filaggrin to form a fibrous matrix.

In the most superficial layers, filaggrin is proteolyzed into amino acids and urocanic acid. Amino acids form the NMF (Natural Moisturizing Factor). Urocanic acid absorbs UV. The Odland’s lamellar bodiesin the keratinocytes of the granular layer will unload their lipids (cholesterol, ceramides, etc.) in the intercellular space thus ensuring a ensure good cohesion between corneocytes, a good impermeability and to regulate desquamation.

The association between the tight cohesion of the keratinocytes of the spinous and granular layers, as well as the hydrophobic layer formed by the lipids and the corneocytes constitutes a true barrier of protection: the barrier function.


  • Ensuring hydratation and protection to the skin
  • Preventing dehydration
  • Protecting skin against environmental agressions


To meet these expectations, Exsymol has developed actives capable of maintaining the barrier function, strengthening or restoring it in the event of an intense stress.

Step 1: Maintaining a good barrier function

Ensuring a good keratinocyte differentiation

By stimulating keratinocyte proliferation and differentiation, a good barrier function is ensured because of a thicker epidermis.



A healthy DEJ greatly decreases water evaporation

A damaged dermal-epidermal junction is responsible for dehydration due to water evaporation.

Ensuring the integrity of the DEJ thus ensures a good barrier function.


The nerve cells within the epidermis participate in the barrier function

Nerve cells play a key role in cell communication. In the epidermis, they promote the keratinocyte proliferation and differentiation.

Ensuring the survival of the epidermal nerve cells thus ensures a good barrier function.


Step 2: Strengthening the barrier function

Applying a protective film at the surface of the skin

Covering the skin with a hygrophilic film will greatly reduce trans-epidermal water loss. Three molecules are perfectly suited for this role:

  • Hyaluronic acid
  • Panthenol
  • Vitamin E




Step 3: Restoring the barrier function

Some stresses can greatly damage the barrier function:

  • Delipidation (chemical peels, acetone …)
  • Strong dehydration (alcohol, temperatures …)
Acetone will cause a severe delipidation and will strongly inhibit the expression of aquaporin (in green), marker of the barrier function

Exsymol offers actives capable of restoring a damaged barrier function.

Delipidation deprives the skin of its first defensive barrier

A peel or exposure to acetone will remove the lipid layer on the surface of the skin which will significantly reduce the barrier function.



Exposure to a high temperature or to alcohol will create severe dehydration that will affect the barrier function

Forced dehydration causes a fall in the barrier function. By maintaining a good hydration of the skin, it also maintains its barrier function.


Inflammation degrades the barrier function

Some pro-inflammatory stress (shaving, waxing …) lead to dehydration due to an alteration of the barrier function. By reducing inflammation, an optimal barrier function is ensured

D.S.B. C



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