Collagen (see box below) is thought to be produced by keratinocytes, rather than fibroblasts, as previously thought. These two cells are present in the different layers of the skin, particularly in the epidermis, the superficial part of the skin, as well as in the structure of the dermis, the layer just below. This discovery was made by researchers from different Japanese universities and published in the journal Nature Communications.
Scientists have studied the skin of the axolotl, also known as the Mexican salamander (because it comes from the Xochimilco and Chalco lakes in Mexico) to understand the mechanisms of collagen formation. Why does this small freshwater aquatic amphibian ? “Firstly because he is very cute, but more seriously because his skin is transparent and has great regenerative capacity.”, explains to Science and Future Akira Satoh, researcher at Okayama University (Japan) and co-author of the study.
What is collagen?
THE collagen is a structural protein, whose function is to give tissues resistance to stretching. Collagen is also a major player in tissue healing, particularly in the skin. However, especially with age, the skin can become distant or loose, forming wrinkles, or it can form a scar following trauma. Indeed, dermal collagen cannot be restored to its original fine structure once damaged.
Indeed, the research team used fluorescent products, visible through the animal's skin, to study collagen formation. This type of work is made more complicated by the presence of hair or greater opacity on mammalian skin. This is why the axolotl, with its highly transparent skin, seemed the best choice to the researchers.
Read also: Collagen: Deciphering its essential role in the health of our skin
Fibroblasts are not useless, however.
Thus, they noticed that, contrary to what was previously believed, keratinocytes, cells constituting 85% of the epidermis, produced the collagen of the axolotl's skin. Fibroblasts, cells present in the skin and participating in its structure, only play, according to this study, “a role in modifying and strengthening existing collagen fibers created by keratinocytes”, says Akira Satoh.
Additionally, the researchers subsequently conducted similar experiments on other animals, such as mice, zebrafish, and chickens, to see if they would obtain similar results. Indeed, in these three animals, collagen production also comes from keratinocytes, before being modified and reinforced by fibroblasts.
However, the researcher points out that the production of this structural protein by keratinocytes stops at the birth of mammals. Thus, fibroblasts take over at a given moment, but they do not know how to produce highly organized collagen fibers and produce them in a rather random manner. Dr. Satoh demonstrates this difference quite simply: he explains that " The mouse embryo has collagen-producing keratinocytes, so it has the ability to heal without scarring, whereas adults or infants, whose collagen fibers are produced by fibroblasts, do not have it, or at least not as much.
Read also: The benefits of marine collagen for the skin
Current skin care " have a wrong target"
But what does this discovery mean for us in concrete terms? If the same observation is made for humans as for axolotls or mice, it could well be that current skin care products " have a wrong target (fibroblasts, editor's note) and should instead focus on keratinocytes", or that, according to the doctor, people taking food supplements such as marine collagen to have beautiful skin or to slow down skin aging " may one day have the possibility of applying a cream to their skin, acting directly on the keratinocytes".
Furthermore, according to Akira Satoh, “We must therefore focus on the right cells in order to offer skin treatments, anti-aging creams or others, whose effect will be to activate the producers of quality collagen.”Finally, it is important to point out that this work can also be useful in the development of creams to improve tissue healing by once again boosting the production of collagen by keratinocytes.
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