Collagen and elastin: the proteins synonymous with flexibility and firmness.

Elastin is a proteinsecreted by fibroblasts, the primary cells of connective tissue. As a reminder, connective tissue is a supportive tissue; the dermis, the deep layer of the skin, is a connective tissue unlike the epidermis, the more superficial layer, which is an epithelial tissue.

Elastin is a major protein component of tissues found in the skin, but also in the lungs, arteries, bladder, elastic ligaments, and cartilage. Elastin is synthesized from a soluble precursor called tropoelastin through the cross-linking of lysine residues by lysyl oxidases. Following this, elastin is composed of soluble tropoelastin, residues of glycine, valine, proline, and modified alanine.

The role of elastin is to allow various elements of the body to maintain their shape even after being stretched. It thus enables the skin to return to its initial state very quickly after being stretched, pricked, or pinched. Thanks to elastin, the skin is perfectly stretchable with improved tonicity.

With an equal diameter, elastin is five times more elastic than arubber band !

Nevertheless, the production of elastin by fibroblasts ceases at puberty. Even though elastin proteins are resilient and hard to degrade, certain enzymes called elastases, also secreted by fibroblasts, are capable of cleaving them and making them less effective. The skin then loses its elasticity and wrinkles deepen.

Elastin, as it is, exists as a cosmetic active ingredient; it is derived from the marine environment, thus referred to asmarine elastin even though the INCI name remains ELASTIN. However, products containing it are very rare on the market. Instead, we find treatments containing elastin-boosting actives like the "Calcium 2-ketogluconate". Elastin is more prevalent in dietary supplements even though its effectiveness on the skin after ingestion of such a compound is a subject of scientific debate.

Naturally present in the body, collagen is the most abundant protein in the human body: it accounts for about 25% of the proteins found in the body. Produced by fibroblasts, it provides a mechanical resistance to stretching and a structure to many of the body's connective tissues, which is why collagen is found, among other places, in the skin, muscles, bones, ligaments, tendons, hair...

There exist 28 types of collagen with different properties depending on where it is located, of which type I is the major component of the extracellular matrix of the dermis, representing 80 to 90% of the total collagen. It is characterized by three polypeptide chains organized in a helical manner, each composed of a thousand amino acids linked together by disulfide bridges to form patterns (called sequences). Glycine is the most represented amino acid, but it is also rich in proline and hydroxyproline.

Collagen holds significant importance for the skin. Present in the form of fibers, it ensures tissue regeneration, provides high elasticity, imparts flexibility and resistance, and acts as a binder between skin cells, which helps to maintain its structure. The issue is that as the years pass, collagen synthesis slows down. This loss can begin around the age of 25, and the body can lose approximately 1% of collagen per year, and gradually up to 25% per year. Thus, by the age of 80, we have lost 75% of collagen compared to young adults. Moreover, over the years, collagen fibers become rigid, fragmented, and disorganized.

These phenomena promote the appearance of wrinkles, loss of firmness and elasticity in tissues, and sagging of the skin. On the other hand, a lack of collagen in the skin leads to an irregular skin texture: the skin loses its radiance and the complexion becomes less uniform. Unprotected exposure to UV rays, smoking, air pollution, not to mention the role of diet with glycation (the binding of sugars to collagen) leading to a stiffening of this protein, all contribute to this premature degradation of collagen.

To slow down skin aging, the external supply of collagen can be beneficial. Therefore, it can be used in cosmetics to compensate for the decrease in production associated with aging, and thus help to reduce the depth of wrinkles and improve the appearance of the skin.

Caution! Generally, the collagen used in cosmetology is of animal origin: it is either extracted from beef or pork cartilage, or from the skin, bones, and scales of fish. The INCI name provides no indication of the collagen's source. Therefore, it is necessary to approach the manufacturer to know its origin. The one used in our wrinkle and firmness loss serum is of plant origin: it consists of plant fragments of type I collagen that mimic human collagen and has been transiently generated through wild plants. The Nicotiana benthamiana is the one used to serve as a support. To do this, a synthetic fragment of human type I collagen was cloned and transcribed in vitro, before being inserted into the cytoplasm of the plant cells.