FR2974370A1 - Characterization of skin pigment spot apparent in human, comprises comparing expression levels, in skin sample form spot and unwounded adjacent skin, of dermal gene e.g. TGFBR2 involved in transforming growth factor-beta-SMAD signalization - Google Patents

Abstract

Method of characterization of skin pigment spot apparent or suspected in a human, comprises comparing expression levels, in skin samples form the spot and unwounded adjacent skin, of at least a dermal gene involved in transforming growth factor (TGF)-beta -SMAD signalization, where the gene is TGFBR2, TGFB1, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A, SMAD7 or SOSTDC1. Independent claims are included for: (1) a method of evaluating the efficacy of a treatment of skin pigment spots comprising comparing expression levels, in skin samples form the spot and unwounded adjacent skin after such a spot, before and after treatment, of at least a dermal gene involved in the transforming growth factor (TGF)-beta -SMAD signalization; (2) an in vitro method for evaluating the efficacy of a treatment of skin pigment spots, comprising comparing, before and after treatment, the level of expression in a representative cellular model of the skin, of at least one dermal gene involved in the path of the TGF-beta - SMAD or the level of expression or activity of the expression product of the selected gene; (3) cosmetic method of treatment or prevention of skin pigment spot of non-pathological human skin comprising modulating the level of expression or activity of the gene involved in the TGF-beta -SMAD signalization, where the modulation is effected through the use of an antisense molecule, an small interfering (si)RNA, a microRNA, salvianolic acid B or an extract of Wen-pi-tang-Hab-Wu-ling-san; (4) use of a modulator of the expression level or activity of the expression product of the gene, for cosmetic applications in the treatment of non-pathological skin pigment spots, where the modulator is an antisense molecule, siRNA, a microRNA, demineralized bone powder, pioglitazone, 4-[2-(3-fluoro-4-trifluoromethyl-phenyl)-4-methyl-thiazol-5- ylmethylsulfanyl]- 2-methyl-phenoxy-acetic acid (GW0742), cristata, flavonoid, fenofibrate, oxymatrine, salvianolic acid B, 4-[4-(1,3-benzodioxol-5-yl)- 5-(pyridin-2-yl)-1H-imidazol-2-yl]benzamide (SB-431542), an extract of Wen-pi-tang-Hab-Wu-ling-san, 3-deoxyglucosone (precursor of glycation end product), N-acetyl-seryl-aspartyl-lysyl-proline or tetrandrine; and (5) a modulator of the expression level or activity of the expression product of the deraml gene. ACTIVITY : Dermatological. MECHANISM OF ACTION : Gene expression modulator.

Description

The present invention is in the cosmetic field, it relates to the skin. It fits more generally in the context of the characterization of the pigmentary spots of the skin and the treatment of these spots.

The color of the skin is mainly due to the presence of a pigment, melanin in the epidermis. Melanin is synthesized by specific dendritic cells located in the basal layer of the epidermis, the melanocytes. Melanogenesis takes place in organelles, melanosomes which, loaded with melanin, are transferred to neighboring epidermal cells, the keratinocytes, via the dendrites. The color of the skin, or constitutive pigmentation varies according to the individuals depending on the amount of melanin produced as well as the chemical nature of melanins. Melanins are macromolecules formed from tyrosine (eumelanin) or tyrosine and cysteine (pheomelanin). Synthesis mechanisms involve enzymes, the main ones being tyrosinase and tyrosinase-associated protein (Tyrp-1). Naturally, the pigmentation of the skin is stimulated by the exposure to the sun, it is the phenomenon of tanning.

There are however situations where the pigmentation process is impaired, and which can lead to pigmentation defects, hypopigmentations (vitiligo, albinism) or conversely to an excess of pigmentation, hyperpigmentations. Among the benign hyperpigmentary disorders, characterized by an abnormal accumulation (excluding tanning) of melanin, mention may be made of actinic lentigo, melasma, acne pigment sequelae, post-inflammatory pigmentation, prairie dermatitis, pigmentation related to the plant poison ivy or the benign dychromics of the face. The actinic lentigo, also called senile or solar lentigo, senile spot, age spot, or commonly referred to as "senile dirt", "cemetery daisies" or "cemetery flowers", is by far the most common pigmentary lesions. This type of lesion appears on areas of the skin that have been photoexposed, such as the face, back of the hands, upper limbs and especially the dorsal forearm, back, and especially the upper back. They usually affect individuals from the age of 40. Macroscopically, the actinic lentigines are represented by benign pigmented macules of brown color more or less dark, whose edges are clear but irregular. Of very variable size, they can extend from a few millimeters to more than two centimeters. Despite its high frequency, few studies have been published on the physiology and pathogenesis of actinic lentigines. On the basis of the rare existing histological studies, it is known that there is an increase in the overall epidermal melanic load and more particularly in the basal layer. There is also an elongation of the epidermal ridges that can take a club-shaped appearance in the papillary dermis [Montagna 1980, ber Rahman 1996, Andersen 1997, Cario-Andre 20041. Finally, there may be anastomoses between adjacent ridges giving an appearance bridge or network.

Incontinence pigmentosa with presence of melanin and melanophages may also exist in the dermis. Current treatments: Benign skin disorders are generally considered unsightly. Due to the proven association between the appearance of actinic lentigines and chronic exposure to the sun, the prevention of their appearance usually involves the topical application of so-called photoprotective products such as sunscreens. In the case of "curative" treatments, many processes, mainly for cosmetic purposes, have therefore been developed in order to try to eliminate them or reduce their presence. The elimination or reduction of the presence of these disorders is usually based on the application of depigmenting treatments, based on the reduction of melanin synthesis activity in melanocytes. Depigmenting molecules interfere with one or more stages of melanogenesis. One of the main products used to date is the inhibition of tyrosinase, one of the key enzymes in the melanogenesis process. The purpose of these treatments is to reduce or even stop the synthesis of pigment.

The main known depigmenting substances are hydroquinone and its derivatives, kojic acid, arbutin, iminophenols, ascorbic acid and its derivatives, the combination of carnitine and quinone, amino phenol derivatives, and benzothiazole derivatives, natural extracts, corticosteroids, etc. Exfoliants are often also associated with these active agents to increase desquamation, and thus to eliminate more easily the melanin present in the stratum corneum. Another method of non-cosmetic treatment is to destroy the lesions by physical or chemical means using lasers or peels. However, these are fairly cumbersome procedures that do not address the etiology of the disorder. In the majority of cases, actinic lentigines reappear some time after treatment.

In addition, there are major disadvantages to existing treatments. The depigmenting substances may exhibit in particular a certain instability, a low efficiency at low concentration, a biological activity affecting other functions, toxic or allergenic properties.

In addition, because they do not target the root cause that caused the dysregulation of pigmentation, there is a great heterogeneity of response to different depigmenting treatments. Thus, for a given treatment, administered, for example, topically, a given benign skin pigment disorder, such as an actinic lentigo or melasma, may subside or disappear, while another will not evolve. This variability can be observed between lesions in different individuals but also in the same individual, between different lesions. There are therefore mild skin pigment disorders for which no topical treatment is effective today.

There is therefore a need to find more effective and more harmless treatments for this type of lesion. For this, it is necessary to identify the molecular deregulation and functional dysfunction that may exist in this type of pigment disorder in order to identify new targets and select assets to correct these defects.

In the prior art, concerning the treatment of pigment spots and more particularly of actinic lentigines, it is described the stimulation at the genomic or protein level of molecules which are closely associated with melanocytes and melanogenesis (melanogenesis enzymes, melanosome protein , key paracrine factors of melanogenesis). It is found in the epidermis or dermis for the following proteins: Tyrosinase, TRP1, DCT, Pmel-17, POMC, ET1, ETBR, SCF, c-KIT, KGF, KGFR, Hepatocyte growth factor (HGF), MIA, TRPM1, Melan-A, Pink eye dilution, P53 and IL1a. In addition, other studies describe molecular or cellular changes in solar or senile lentigo by gene or protein expression analyzes. However, from these different studies, there is no general mechanism or functional dysfunction underlying the appearance of pigment spots. No prior art document has reliably demonstrated molecular dysregulations or functional dysfunctions that may exist in this type of pigment disorder, beyond molecules closely associated with melanocytes and melanogenesis.

The present inventors have demonstrated for the first time the involvement of dermal genes linked to the extracellular matrix and to the dermal-epidermal junction in the pigmentary disorders resulting in pigmentary spots on the skin, and more particularly the implication of genes linked to the TGF-beta signaling pathway - SMAD. The extracellular matrix provides a structural role in the skin thanks to its ability to provide support and cohesion of tissues and cells and thanks to its mechanical properties which allow it to resist tensile stress (especially because of the presence of collagens), compression (especially because of the presence of proteoglycans). It plays an important biological role because it is also a major player in the regulation of epidermal and dermal homeostasis. Thanks, among other things, to its reservoir properties of growth factors and cytokines, it is involved in morphogenesis, proliferation, cell differentiation and tissue repair. The dermal-epidermal junction (DDE) is performed by the basement membrane which consists of an extracellular matrix leaflet and which separates the epidermis from the dermis. It constitutes a barrier of permeability and regulates the exchange of molecules, in particular nutrients, between the two tissues. It provides a function of attachment and anchoring of the epidermis to the underlying matrix and structural cohesion of the epithelium. It also plays an important role in the regulation of differentiation, and the migration of epidermal cells as well as the morphogenesis stages of the epidermis.

Transforming Growth Factor beta (TGF-3) controls proliferation, cell differentiation, and other functions in most cells. It plays a role in immunity, cancer. Some cells secrete TGF-3, and also have receptors for TGF- (3) Smads make up the TGF-3 signaling pathway, allowing signal transduction when TGF- (3 binds to membrane receptors. The cellular responses induced by this pathway can vary for the same cellular type depending on the cellular context.This is a very dynamic signaling system.In the canonical pathway, TGF-β3 binds to a type II membrane receptor which forms a bidimeric complex with a second type I receptor A type III receptor (betaglycan) aids this binding process by capturing TGFbeta and presenting it to the bidimeric receptor complex The TGF-3-bound receptor II, phosphorylates the receptor of type I which propagates the signal by phosphorylating in turn cytosolic proteins, Smad (Smad 2 and 3) .The Smad regulated by the type I receptor (R-Smad) then bind to a common Smad, Smad 4 for co This complex then enters the cell nucleus where it acts as a transcription factor for multiple genes, and leads to an activation or repression response. Specific type I receptors, activated by other ligands such as various BMPs (bone morphogenic proteins), activate the signaling pathway via other Smad (1, 5, 8). In general, activation of the pathway also leads to the stimulation of inhibitory Smad such as Smad 6 and 7 which provide negative feedback control.

Among the target genes of the TGFbeta pathway are numerous genes encoding extracellular matrix molecules, including for example collagens, elastin, fibronectin, thrombospondins which predominantly play a structural role, and simultaneously, for Matrix remodeling proteins that participate in the renewal and degradation of the molecules of the matrix. This pathway also has a stimulatory or inhibitory action in the production of numerous growth factors and cytokines by dermal cells.

For the first time, it has been shown by the present inventors that certain genes related to the extracellular matrix and more particularly to the TGF- (3-SMAD) signaling pathway, have significantly different levels of transcription between healthy skin and the skin resulting from a pigment spot, thus highlighting the link between dysregulation of TGF-13 signaling - SMAD within the extracellular matrix and modulation of pigmentation inducing the appearance of pigment spots.

It may be thought that the increase or decrease of some proteins involved in these different pathways, either TGFBeta-dependent or BMP-dependent, may lead to increased and / or aberrant signaling that may interfere with dermal, junctional homeostasis and globally epidermal level.

Therefore, without being bound by any theory, the expression modifications of different genes linked to this signaling pathway within the dermis led the inventors to think that the deregulation of these genes, sign of a modification of the whole dermal compartment, disturbs the homeostasis of the epidermis and generates important modifications, in particular of the histological architecture of the epidermis in the pigmentary spots (elongation of the epidermal ridges in the dermis, for example). As a result, the epidermal melanic charge is increased and gives rise to pigment spots.

The present invention relates to a molecular signature representative of the differences in gene expression existing between the skin resulting from pigment spot and the adjacent healthy skin, and to the various applications and methods making use of the knowledge of this signature, in particular for modulating pigmentation. skin, in the cosmetic treatment of pigment spots or to even out the complexion or to homogenize the color of the skin. This signature consists of the following 9 genes: TGFBR2 (transforming growth factor receptor beta [70180kDa]), TGFBI (induced transforming growth factor beta, 68 kDa), BMP2 (bone morphogenic protein 2), SMAD3 (member 3 of SMAD family), THBS2 (thrombospondin 2), TGFBR3 (beta-transforming growth factor receptor III), SEMA5A (sema domain, 7 thrombospondin repeats, semaphorin 5A), SMAD7 (SMAD family member 7) and SOSTDC1 (protein 1 containing a sclerostine domain). Said genes are human genes so called. The inventors have in fact demonstrated the significant and reproducible modulation of the level of expression of these genes between skin resulting from pigment spot and the corresponding healthy skin. Moreover, the modulation of these 9 genes within hyperpigmentary spots tends to increase the TGF-beta-SMAD signaling. The present invention relates in particular according to a first aspect to a method for characterizing a cutaneous pigment spot. Such a method makes it possible inter alia to confirm the nature of the pigment spot in the case where the latter is already apparent, for example visually to the naked eye. The method also makes it possible to predict the appearance of a stain, when the stain is not yet observed but only suspected, or to conclude that a skin is prone to the formation of skin spots, or prone to skin defects. pigmentation, for example when no stain is still apparent.

The skin pigment spots concerned are hyperpigmentary spots, or so-called hyperpigmented spots, corresponding to an excess of pigment, or hypopigmentary spots, or even hypo-pigmented, corresponding to pigmentation defects. Hypopigmentations that can be envisaged in the context of the present invention include vitiligo and albinism. Benign hyperpigmentary disorders that can be envisaged in the context of the invention, characterized by an abnormal accumulation (excluding tanning) of melanin, are, for example, actinic lentigo, melasma, acne pigment sequelae, post-inflammatory pigmentation, dermatitis of meadows, the pigmentation linked to the plant poison ivy or the benign dyschromias of the face. The pigment spots according to the present invention also include defects, imperfections or irregularities of pigmentation rendering the complexion uneven, or the color of the skin not homogeneous. The pigment spots in question are preferentially pigmented spots on human skin. However, the disorders in the extracellular matrix and the TGF- (3-SMAD) signaling pathway in the dermis demonstrated by the present inventors being quite general, similar methods can be envisaged for others. In this case, the different methods, uses or compositions according to the invention will be implemented with the genes of the species considered, which are orthologous to the human genes of the invention. comparing the levels of expression within the skin resulting from said stain and within the non-damaged skin, preferably adjacent, of the same individual, of at least one dermal gene linked to the TGF-β signaling pathway. SMAD selected from the list consisting of TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A, SMAD7 and SOSTDC1 genes TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A, SMAD7 and SOSTDCI genes are . Nes of the invention They share a role in the signaling pathway TGF43 - SMAD.

Furthermore, said genes of the invention are called dermal genes because they are genes that are predominantly expressed in the dermis and give rise to characteristic proteins of the dermal compartment or of the dermal-epidermal junction as to its face. dermal; and in contrast to, for example, keratinocyte proteins, intracellular proteins or epidermal proteins in particular. The levels of expression of at least one of the genes of the invention are measured at the level of the skin resulting from a known or suspected spot, and at the level of the adjacent skin which has not been injured. Preferably, the levels are measured on skin samples taken within the spot and within an adjacent non-injured area. The samples are, for example, skin biopsies. Biopsies of a few millimeters in diameter are sufficient, for example a biopsy of 2 mm, or 3 mm in diameter. One can also consider the total excision of a lesion.

The non-lesioned area is preferably an adjacent area as close as possible to the spot but at a distance sufficient for the sample taken to contain no cells likely to belong to the pigment spot. Preferably, the non-injured adjacent area is an area having light and sun exposure comparable to the area of the pigment spot. Alternatively, the non-injured area may come from a symmetrical zone on the other part of the subject, having a perfectly identical location; for example in the case of a stain on the left hand, the uninjured area may be the corresponding area on the right hand. In this case, the non-injured area is not strictly speaking an adjacent area. The term "non-injured" means an area which does not have a pigment spot or pigment irregularity, preferably a zone that is homogeneous in terms of pigmentation.

Since the non-lesion area serves as a reference, it should in all cases be as comparable as possible to the area of the spot, but devoid of any pigment defect. By level of expression of a gene, it is preferentially understood, in the present description, the level of transcription of said gene. However, its level of expression can also be translated by its level of translation, assuming that it is a gene coding for a protein. This is the case for the genes of the invention. Concerning the evaluation of the transcription level of the chosen gene, it can be carried out by various means well known to those skilled in the art, directly or after reverse transcription. The level of transcription can in particular be evaluated by the use of commercially available RNA chips or microarrays for this purpose. A possible evaluation method is described in the experimental part. It is important to note also that the method according to the invention involves the comparison of the levels of expression of at least one of the genes of the invention. As a result, it may be sufficient to quantitatively or qualitatively assess the difference between the two levels of expression, without individually evaluating and quantifying each level of expression. The expression levels of at least one of the genes of the invention may be evaluated by reference or after normalization with the level of expression of other genes, the level of expression of which is assumed to be substantially identical within the stain and in the area of non-injured skin chosen. Such genes for normalization are well known to those skilled in the art and may depend on the area of the body where the stain is located. By way of example, the following genes may be cited as being capable of serving for the normalization of the expression levels of the genes of the invention, coding for: L13a ribosomal protein (RPL13A), beta-2-microglobulin (B2M ), ribosomal protein S9 (RPS9), ribosomal protein S28 (RPS28) and Glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The method according to the invention is preferably carried out in vitro or ex vivo. According to one embodiment of the method of the invention, the pigment spot is a non-pathological, benign spot, especially as opposed to pathological lesions such as naevi; it may be an irregularity in the pigmentation of the skin. Preferably, a method according to the invention comprises comparing the expression levels of at least two distinct genes among the genes of the invention, preferably at least three distinct genes, or even five distinct genes. It is also conceivable to compare expression levels of at least 6 genes, or even at least 8 distinct genes or 9 genes of the invention. When two genes are chosen, they are preferably selected from the lists of the following 6 preferred genes: TGFBR2, TGFBI, BMP2, SMAD3, THBS2 and TGFBR3. For example, the genes selected may be TGFBR2 and TGFBI, or TGFBR2 and BMP2, or TGFBI and BMP2, or TGFBR2 and TGFBR3. All two by two combinations of the 6 preferred genes are preferred combinations for the practice of the invention. Similarly, all combinations involving one of the 6 preferred genes and one of the other 8 genes of the invention are particularly preferred. For the combinations of 3 genes, the following combinations are especially envisaged; TGFBR2, TGFBI and BMP2; TGFBR2, TGFBI and SMAD3; TGFBR2, TGFBI and TGFBR3; SMAD3, SEMA5A and SMAD7; TGFBR2, BMP2 and SOSTDC1; and TGFBI, BMP2 and SMAD3. Possible combinations of 5 genes according to the present invention include the following combinations: TGFBR2, TGFBI, BMP2, SMAD3 and THBS2; TGFBR2, TGFBI, BMP2, SMAD3 and TGFBR3; and TGFBR2, TGFBI, BMP2, THBS2 and TGFBR3. A particular combination is that comprising the genes TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A and SMAD7, which have in common that they are modulated in the same way, in particular to be overexpressed in hyperpigmentary spots. Other combinations are also conceivable within the meaning of the present invention, in particular combinations comprising at least one gene from TGFBR2, TGFBI, THBS2 and TGFBR3; and at least one of SMAD3, SEMA5A and SMAD7. The 9 genes of the invention have the common point of belonging to the TGF-f3-SMAD signaling pathway and of being cooperatively modulated at the level of pigment spots, that is to say that the TGFBR2 genes, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A and SMAD7, which are positively involved in this signaling pathway, are all modulated in the same direction and are modulated in the opposite direction of the SOSTDCI gene which is a BMP antagonist. and therefore negatively involved in this signaling pathway. Any of the preferred specific gene combinations or subgroups related to this aspect of the invention are also preferred for the other aspects of the invention. The implementation of the method according to the invention leads to the conclusion that the supposed or observed spot is a hyperpigmentary spot if the level of expression is higher in the skin resulting from the stain, or in the skin sample resulting from the stain, relative to the level in the adjacent uninjured skin, or in the adjacent uninjured skin sample, if the gene is selected from TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMASA and SMAD7, and - inferior in the stained skin, or in the skin sample from the stain, relative to the level in the adjacent uninjured skin, or in the adjacent skin sample, if the selected gene is SOSTDC1.

Indeed, the present inventors have demonstrated the overexpression of the genes TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A and SMAD7 in the skin resulting from hyperpigmentary stain, in particular actinic lentigo, relative to the level of expression in adjacent skin uninjured. They also demonstrated the subexpression of the SOSTDCI gene in the skin resulting from hyperpigmentary stain, notably actinic lentigo, with respect to the level of expression in the adjacent non-injured skin. Conversely, the implementation of the method according to the invention leads to the conclusion that the supposed or observed spot is a hypopigmentation spot if the level of expression is: - lower in the skin resulting from the stain, or in the skin sample from the stain, relative to the level in the adjacent uninjured skin, or in the adjacent skin sample not damaged, if the gene is selected from TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A and SMAD7, and - higher in the stained skin, or in the stained skin sample, relative to the level in the adjacent uninjured skin, or in the adjacent non-injured skin sample , if the selected gene is SOSTDC1.

By higher or lower is meant a difference in expression levels that is statistically significant, superior to noise, and reproducible. For example, the difference in level of expression is at least 10%, that is, if the level of expression of a gene of the invention in the non-injured skin is set at 1, the modulation rate is at least 1.1 for a gene overexpressed in the lesion skin and at most 0.9 for a gene that is under-expressed in the lesional skin. Preferably, the method according to the invention is implemented with at least two genes, one belonging to the category of genes overexpressed in hyperpigmentary spots, and under-expressed in hypopigmentary spots, and the other being the SOSTDCI gene modulated to the reverse of the first in pigment spots. Preferably, the method is implemented with at least three genes: two genes chosen from TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A and SMAD7 and the SOSTDCI gene, modulated in contrast to the first two in the spots pigmentary.

Preferably, in the context of this method of characterization, the level of expression of one of the genes of the invention is compared within the skin of a Caucasian-type individual. Preferably, said individual is at least forty years old, preferably at least fifty years, or even sixty years old. The individual considered, in the context of the present invention, is preferably female. As previously detailed, the level of expression of one or more genes of the invention can be compared within the skin sample of said individual. Furthermore, the present inventors have also demonstrated the differential modulation of other dermal genes between skin from a pigment spot and from the non-damaged skin, preferably adjacent. The inventors have in particular demonstrated the modulation of the following dermal genes, linked to the extracellular matrix: - genes EFEMP1, ECM1, ASPN, HS3ST6, PAPLN, CHSY1 and FLRT2 encoding proteins of the family of proteoglycans and extracellular glycoproteins; - genes MXRA5, LYZ, CTSL2, PLAU and TIMP1 coding for proteins related to matrix remodeling; - LEPRELI genes, PLOD2, COL6A3 and CRTAP coding for collagens, components of the extracellular matrix, and more particularly filamentous collagens of the stroma and for molecules associated with the biosynthesis and assembly of collagens; LAMC1, LAMB3 and LAMA3 genes encoding laminins, adhesive proteins of the extracellular matrix; FRAS1, MATN2 and DST genes encoding matrix proteins associated with the zone of the basement membrane; ITGA2, ITGAV and ITGBI genes encoding integrins involved in cell binding to the extracellular matrix; ACTN1 gene encoding actin, a component of the extracellular matrix.

Therefore, the method of characterization according to the present invention also comprises the comparison of the levels of expression within the skin resulting from said stain and within the non-damaged skin, preferably adjacent, of at least one linked dermal gene. to the TGF-6-SMAD signaling pathway chosen from the list consisting of the genes TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A, SMAD7 and SOSTDC1 and at least one second gene chosen from the list of the following genes: EFEMP1, ECM1, ASPN, HS3ST6, PAPLN, CHSY1, FLRT2, MXRA5, LYZ, CTSL2, PLAU, TIMP1, FRAS1, LEPRELI, MATN2, DST, PLOD2, ITGA2, COL6A3, CRTAP, LAMC1, LAMB3, LAMA3, ITGAV, ITGB1 and ACTNI; for example, the second gene is chosen from the list of the following genes EFEMPI, ECM1, ASPN, HS3ST6, PAPLN, CHSY1, FLRT2 or from the list of the following genes: MXRA5, LYZ, CTSL2, PLAU and TIMP1, or else among the following genes: FRAS1, LEPREL1, MATN2, DST, PLOD2, ITGA2, COL6A3, CRTAP, LAMC1, LAMB3, LAMA3, ITGAV, ITGBI and ACTN1. Preferred genes within the second list of dermal genes are the EFEMPI, ECM1, ASPN, HS3ST6, PAPLN and CHSYI genes, the MXRA5, LYZ, CTSL2, PLAU and TIMP1 genes as well as the FRAS1, LEPREL1, MATN2, DST genes, PLOD2 and ITGA2. Preferably, the second gene is chosen from the EFEMP1, ECM1, ASPN, HS3ST6, PAPLN, CHSY1 and FLRT2 genes, and preferably from the EFEMP1, ECM1, ASPN, HS3ST6, PAPLN and CHSY1 genes. Alternatively, the second gene is selected from the genes MXRA5, LYZ, CTSL2, PLAU and TIMP1. According to yet another embodiment, the second gene is chosen from the genes FRAS1, LEPRELI, MATN2, DST, PLOD2, ITGA2, COL6A3, CRTAP, LAMCI, LAMB3, LAMA3, ITGAV, ITGBI and ACTN1, and preferentially among the FRAS1 genes. , LEPRELI, MATN2, DST, PLOD2 and ITGA2. Alternatively, the second gene can be chosen from LEPRELI, PLOD2, COL6A3 and CRTAP, or from LAMC1, LAMB3 and LAMA3, or from FRAS1, MATN2 and DST, or else from ITGA2, ITGAV and ITGB1, or else be ACTN1. According to one particular embodiment, the method comprises the comparison of the expression levels of at least 3 distinct genes, one chosen from the genes TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A, SMAD7 and SOSTDC1. a second one selected from the EFEMPI, ECM1, ASPN, HS3ST6, PAPLN, CHSY1 and FLRT2 genes and a third one selected from the MXRA5, LYZ, CTSL2, PLAU and TIMP1 genes. According to yet another embodiment, the method comprises the comparison of at least 4 distinct genes, the first three being chosen as described above and the fourth in the list consisting of FRAS1, LEPREL1, MATN2, DST, PLOD2, ITGA2, COL6A3. , CRTAP, LAMC1, LAMB3, LAMA3, ITGAV, ITGB1 and ACTN1.

All of the gene combinations described above are also preferred combinations within the scope of other aspects of the invention. If an additional gene, or more, is selected from the genes EFEMPI, ECM1, ASPN, HS3ST6, PAPLN, CHSY1, FLRT2, MXRA5, LYZ, CTSL2, PLAU, TIMPI, FRAS1, LEPREL1, MATN2, DST, PLOD2, ITGA2, COL6A3 , CRTAP, LAMC1, LAMB3, LAMA3, ITGAV, ITGBI and ACTN1, then the characterization method leads to confirm a hyperpigmentary spot if the level of expression is higher in the skin resulting from the stain, or in the skin sample. of the stain, relative to the level in the adjacent uninjured skin, or in the uninjured adjacent skin sample, if the gene is selected from EFEMP1, ASPN, PAPLN, CHSY1, MXRA5, LYZ, PLAU, TIMP1, FRAS1, LEPREL1, MATN2, DST, ITGA2, COL6A3, CRTAP, LAMC1, LAMB3, LAMA3, ITGAV, ITGB1 and ACTN1, and inferior in the skin from the stain, or in the skin sample from the stain, relative to the level in the adjacent uninjured skin, or in the adjacent skin sample not damaged, if the gene is selected from HS3ST6, FLRT2, ECM1, PLOD2 and CTSL2. Conversely, the evaluation method confirms a hypopigmentation spot if the level of expression is: - lower in the skin resulting from the stain, or in the skin sample resulting from the stain, compared with at the level in the adjacent uninjured skin, or in the uninjured adjacent skin sample, if the gene is selected from EFEMP1, ASPN, PAPLN, CHSY1, MXRA5, LYZ, PLAU, TIMP1, FRAS1, LEPREL1, MATN2, DST, ITGA2, COL6A3, CRTAP, LAMC1, LAMB3, LAMA3,] TGAV, ITGB1 and ACTN1, and higher in the stained skin, or in the skin sample from the stain, relative to the level in the adjacent non-injured skin , or in the adjacent uninjured skin sample, if the gene is selected from HS3ST6, FLRT2, ECM1, PLOD2 and CTSL2. The method described is also a test method for predicting the formation of cutaneous spots in a subject. According to this embodiment, the level of expression of at least one, and preferably more than one, gene of the invention is compared in a skin sample, to its level of expression in normal skin. A significant modulation of the level of expression with respect to the normal skin makes it possible to conclude that the skin of the test subject is prone to the formation of cutaneous spots.

By normal skin, it may be either the skin of the same subject, in a body area notoriously devoid of spots, for example areas not exposed to solar radiation, or areas not prone to the formation of pigment spots. It can also be the average level of expression of said genes, in the skin of people without stains and preferably having the same type of skin as the test subject. The normalization genes described above may be used to normalize the expression levels of the genes of the invention.

The present invention also relates, in a second aspect, to a method for evaluating the effectiveness of a treatment of pigmentary spots or irregularities, using the signature demonstrated by the inventors. The evaluated treatment can be a treatment aiming at the attenuation of pigment spot or any other modulation of the pigmentation, in particular to standardize the complexion, to homogenize the color of the skin or to fight against the dyschromias. According to a first implementation, this evaluation method comprises a step of comparing the levels of expression in the skin resulting from a pigment spot, before and after treatment, of at least one dermal gene chosen from the genes of the invention, namely TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A, SMAD7 and SOSTDC1. According to this evaluation method, the comparison of the expression levels of the selected gene or genes is carried out within the skin resulting from a pigment spot, or within a corresponding sample, before and after treatment. . There is therefore no comparison to a level of expression within healthy non-injured skin. As for the characterization method according to the first aspect of the invention, the expression levels are advantageously standardized using the expression levels of the genes encoding the ribosomal protein L13a (RPL13A), beta-2-microglobulin (B2M), ribosomal protein S9 (RPS9), ribosomal protein S28 (RPS28) and Glyceraldehyde-3-phosphate dehydrogenase (GAPDH). By the evaluation method as described, a given treatment is considered effective for the treatment of a hyperpigmentary spot if the level of expression is: - lower after treatment compared to the level of expression before treatment, if the gene is selected from TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A and SMAD7, and - higher after treatment compared to the level of expression before treatment, if the selected gene is SOSTDCI.

Conversely, by the evaluation method of the invention, a given treatment is considered effective for the treatment of hypopigmentation spots when the level of expression is: higher after treatment compared to the level of expression before treatment, if the gene is selected from TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A and SMAD7, and lower after treatment compared to the level of expression before treatment, if the selected gene is SOSTDC1. Treatment will be considered as no effect if the expression levels of the selected gene, before and after treatment, are substantially identical, or if the differences observed are not significant. When the expression levels of more than one gene are compared, the treatment is considered effective for the treatment of a spot or pigment irregularity if, for the majority of the genes tested, and preferably for the all genes tested, taken individually, the treatment is considered effective. For the other genes selected, the treatment should preferably be without effect, but not have the opposite effect. According to another embodiment, the method for evaluating the efficacy of a treatment of cutaneous pigment spots includes the characterization of a spot or pigment irregularity according to the method of the invention, before and after treatment, and the comparison differences in expression levels observed between the damaged skin of the pigment spot or irregularity and the healthy skin. According to this implementation of the evaluation of the efficacy of a treatment, the treatment is considered effective if the difference between the levels of expression of the gene (s) selected in the lesioned skin resulting from the blemish. relative to healthy skin, preferably adjacent, is less after treatment than it was before treatment. When the expression levels of more than one gene are compared, it is preferably concluded that the treatment is effective when for the majority of the genes chosen, and preferably for the chosen set of genes taken individually, we can conclude that an effective treatment. Preferably, the comparison of the expression levels of the selected gene or genes is performed on skin samples taken from the pigment spot. The treatment considered, evaluated by the method of the invention, is not limited to a particular type of treatment. It may be a treatment with a chemical molecule, an active agent, a natural extract, in particular an essential oil, a nucleic acid, in particular an RNAi, a protein complex or any other molecule or combination of molecules. It can also be a treatment by a physical means or waves, including electromagnetic waves. This is preferably a topical treatment, but it is also contemplated to evaluate the efficacy of oral, injection, or any other means of administration. The tested treatment can aim to attenuate or make disappear a cutaneous spot, to modulate the pigmentation of the skin, to standardize the complexion, to homogenize the color of the skin or to attenuate the dyschromias. Particularly preferred treatments in the context of this invention are cosmetic treatments, more particularly cosmetic topical treatments. In this case, the pigment spot considered is a patches or non-pathological pigment irregularity, for example it is an actinic, solar or senile lentigo. By the methods of the invention, it is also possible to evaluate the effectiveness of the combination of several treatments. It is indeed possible to evaluate combinations that best restore the expression levels of one, more or all of the genes of the invention, as expressed in non-damaged skin. By the evaluation methods described above, it is possible to evaluate the efficacy of a new treatment envisaged, or to quantify or qualify the effectiveness of existing treatments against age spots, whether they are hyperpigmentary or hypopigmentation. In this way, it is also possible to envisage combinations of treatments that can be particularly effective, synergistic or complementary. As explained for the characterization methods according to the first aspect of the invention, it is preferably compared the expression levels of more than one gene, preferably at least two, three, five, six, eight or of the 9 genes of the invention.

Particularly preferred genes or gene combinations have already been explained with respect to the first aspect of the invention; the same genes or combinations are preferred in this aspect. In particular, it is particularly preferred that the gene selected be one of the TGFBR2, TGFBI, BMP2, SMAD3, THBS2 and TGFBR3 genes, and any two to two or three to three of the genes in this list are particularly preferred. . Moreover, because of the complementary results obtained by the inventors concerning other dermal genes whose level of expression is modulated within the pigment spot, the evaluation methods as described are preferably carried out with at least one a gene chosen from the genes TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A, SMAD7 and SOSTDC1, and even preferably from the genes TGFBR2, TGFBI, BMP2, SMAD3, THBS2 and TGFBR3, and at least one second gene chosen from genes EFEMP1, ECM1, ASPN, HS3ST6, PAPLN, CHSYI, FLRT2, MXRA5, LYZ, CTSL2, PLAU, TIMP1, FRAS1, LEPREL1, MATN2, DST, PLOD2, ITGA2, COL6A3, CRTAP, LAMC1, LAMB3, LAMA3, ITGAV, ITGB1 and ACTN1. Alternatively, the second gene may be chosen from the EFEMP1, ECM1, ASPN, HS3ST6, PAPLN, CHSY1 or FLRT2 genes, or among the MXRA5, LYZ, CTSL2, PLAU and TIMP1 genes or among the FRAS1, LEPREL1, MATN2, DST genes. , PLOD2, ITGA2, COL6A3, CRTAP, LAMC1, LAMB3, LAMA3, ITGAV, 1TGB1 and ACTN1.

Preferred genes within the dermal genes EFEMPI, ECM1, ASPN, HS3ST6, PAPLN, CHSY1, FLRT2 are the EFEMP1, ECM1, ASPN, HS3ST6, PAPLN and CHSY1 genes. Preferred genes within the FRAS1, LEPRELI, MATN2, DST, PLOD2, ITGA2, COL6A3, CRTAP, LAMC1, LAMB3, LAMA3, ITGAV, ITGBI and ACTNI dermal genes are the FRAS1, LEPRELI, MATN2, DST, PLOD2 and ITGA2 genes.

If an additional gene, or more, is selected from the genes EFEMP1, ECMI, ASPN, HS3ST6, PAPLN, CHSY1, FLRT2, MXRA5, LYZ, CTSL2, PLAU, TIMP1, FRAS1, LEPREL1, MATN2, DST, PLOD2, ITGA2, COL6A3 , CRTAP, LAMCI, LAMB3, LAMA3, ITGAV, ITGB1 and ACTN1, so the evaluation method leads to consider an effective treatment for the treatment of hyperpigmentary spots if the level of expression is lower after treatment compared to the level of expression before treatment, if the gene is selected from EFEMPI, ASPN, PAPLN, CHSY1, MXRA5, LYZ, PLAU, TIMPI, FRAS1, LEPREL1, MATN2, DST, ITGA2, COL6A3, CRTAP, LAMCI, LAMB3, LAMA3, ITGAV, ITGBI and ACTN1 and higher after treatment versus expression level before treatment, if the gene is selected from HS3ST6, FLRT2, ECMI, PLOD2 and CTSL2. Conversely, the evaluation method leads to consider an effective treatment for the treatment of hypopigmentation spots if the level of expression is: higher after treatment compared to the level of expression before treatment, if the gene is chosen among EFEMPI, ASPN, PAPLN, CHSY1, MXRA5, LYZ, PLAU, TIMP1, FRASI, LEPREL1, MATN2, DST, ITGA2, COL6A3, CRTAP, LAMC1, LAMB3, LAMA3, ITGAV, 1TGB1 and ACTN1 and - lower after treatment compared at the expression level before treatment, if the gene is selected from HS3ST6, FLRT2, ECM1, PLOD2 and CTSL2. The skin sample preferably comes from a human being of Caucasian type, preferably at least forty years old, preferably at least fifty years old, or even at least sixty years old. Preferably, in the context of the present invention and in particular for the evaluation method described, it concerns the treatment of hyperpigmentary spots, and most preferably of actinic, solar or senile lentigines. The method for evaluating the efficacy of a treatment according to the present invention is preferably carried out in vitro or ex vivo. It can also be implemented in vivo. It is desirable that the skin sample before treatment and after treatment is taken from the same pigment spot, or else a very close pigment spot if the size of the stain makes it difficult to obtain samples beforehand. and after treatment. The present invention also relates to an in vitro method for evaluating the efficacy of a treatment of pigment spots; such a method comprises comparing, before and after treatment, the level of expression in a cell model representative of the skin, of at least one dermal gene linked to the TGF-beta-SMAD signaling pathway selected from the list consisting of genes TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A, SMAD7 and SOSTDC1, or the level of expression or activity of the expression product of said selected gene. The cellular model can be of any type considered appropriate by those skilled in the art. it may be in particular mono or co-cultured cell models, or three-dimensional models of reconstructed skin, or skin ex-vivo cultured. There are also cell models representative of pigment spots, more particularly of actinic lentigines, which can be used in the context of this method. Such cell models do not need to mimic pigment spots (or lentigo) in their entirety but must mimic biological events, morphological or pigmentary characteristics observed in pigmented spots, especially the lentigo. Such in vitro models are well known to those skilled in the art. According to a preferred implementation of the in vitro method described above, it comprises the comparison of the expression levels of at least two genes, preferably at least three, five or six genes of the invention, as explained for the other evaluation methods according to the invention. Particularly preferred genes are the TGFBR2, TGFBI, BMP2, SMAD3, THBS2 and TGFBR3 genes. Likewise, as explained for the other evaluation methods, they are preferably used with at least two genes, one being selected from the genes TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A, SMAD7. and SOSTDC1, and preferably among the genes TGFBR2, TGFBI, BMP2, SMAD3, THBS2 and TGFBR3, and the second being selected from the genes EFEMP1, ECM1, ASPN, HS3ST6, PAPLN, CHSY1, FLRT2, MXRA5, LYZ, CTSL2, PLAU. , TIMP1, FRAS1, LEPREL1, MATN2, DST, PLOD2, ITGA2, COL6A3, CRTAP, LAMC1, LAMB3, LAMAS, ITGAV, ITGB1 and ACTN1, preferably among the EFEMPI, ECM1, ASPN, HS3ST6, PAPLN and CHSY1 genes. and FLRT2 or among its genes MXRA5, LYZ, CTSL2, PLAU and TIMP1, or even among the genes FRASI, LEPREL1, MATN2, DST, PLOD2 and ITGA2.

All the specific gene combinations described with respect to other aspects of the invention are also preferred in this aspect. In addition, by means of these evaluation methods, it is possible to promote a treatment with consumers, by highlighting the results obtained with this treatment in the efficacy evaluation methods described in the present invention. The present invention therefore also provides a method for recommending a product by signaling its effect in a test protocol consisting of a method of evaluating the efficacy as described above. The invention therefore also relates to a method for the promotion of a cosmetic product or cosmetic treatment consisting in reporting an efficacy, action or property of said product or treatment, demonstrated by at least one method operated as described above. Such promotion of the product can be done by any communication channel. It may be made by the seller, directly on the point of sale, by radio and television, particularly in the context of commercials. It may also be done through the press, or through any other document, especially for advertising purposes (prospectus). It can also be done via the Internet, or any other appropriate computer network. It may also be made directly on the product, in particular on its packaging or on any explanatory note that may be associated with it. The present invention also relates to a method for screening molecules for the treatment of cutaneous pigment spots comprising the implementation of one of the evaluation methods described above for determining the effectiveness of a treatment based on this molecule.

According to another aspect, the present invention also relates to a cosmetic method for the treatment or prevention of non-pathological cutaneous spot or skin irregularity of the skin, comprising the modulation of the level of expression or the activity of a linked dermal gene. to the TGF-β3-SMAD signaling pathway, wherein said gene is selected from the list consisting of TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A, SMAD'7 and SOSTDC1 genes. Non-pathological skin pigment spots are benign spots, the removal of which is desirable only for aesthetic reasons and not for therapeutic reasons. Pigmentation irregularities include imperfections at the pigment level rendering the complexion uneven or the color of the skin uneven. The present inventors have shown the important role of genes of the invention within the dermis at the level of pigment spots, and in particular the link between dysregulation of the level of expression of these genes and appearance of pigment spots. As a result, suspending or reducing the modulation of these genes may make it possible to reduce or abolish the deregulation observed and thus make it possible to restore a situation at the level of the extracellular matrix that is compatible with the absence of a pigment spot, with therefore a uniform complexion and homogeneous skin color. For the same reasons as explained with regard to the other aspects of the invention, it is preferable to choose more than one gene within the genes of the invention, for example at least two genes, at least three, five, six , eight. According to one embodiment, the purpose of the cosmetic method is to modulate the level of expression of the entirety of the genes of the invention. The cosmetic method according to the invention aims to restore expression levels close to those observed in healthy skin, adjacent for example of a pigment spot. Particularly preferred genes are the TGFBR2, TGFBI, BMP2, SMAD3, THBS2 and TGFBR3 genes. According to a preferred embodiment, said pigment spot is a hyperpigmentary spot, for example an actinic, senile or solar lentigo. In such a case, the modulation sought in the cosmetic methods according to the invention is a total, partial or temporary inhibition of the expression of at least one gene selected from the genes TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A and SMAD7 or an increase, possibly temporary, of the expression of the SOSTDC1 gene. Preferably, the inhibition is not a total but partial inhibition tending to reduce the level of expression of the chosen gene without, however, completely inhibiting its expression. According to another embodiment, said pigment spot is a hypopigmentary spot. In such a case, the modulation sought is inverse to the previous situation, in particular such a method is intended to increase the expression of at least one gene chosen from the genes TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A. and SMAD7, or to inhibit or decrease the level of expression of the SOSTDCI gene. By increasing or decreasing the level of expression, it is included increasing or decreasing the level of transcription of said genes, and increasing or decreasing the level of translation of said genes, as well as increasing or decreasing the level of transcription. activity of the proteins encoded by these genes. Preferably, concomitantly with the modulation of the level of expression sought for one of the genes of the invention, a cosmetic method according to the invention preferably also comprises the modulation of at least one other dermal gene, chosen from the genes EFEMP1, ECM1, ASPN, HS3ST6, PAPLN, CHSY1, FLRT2, MXRA5, LYZ, CTSL2, PLAU, TIMP1, FRAS1, LEPREL1, MATN2, DST, PLOD2, ITGA2, COL6A3, CRTAP, LAMC1, LAMB3, LAMAS, ITGAV, 1TGB1 and ACTN1. Preferred genes within this second list of dermal genes are the EFEMPI, ECM1, ASPN, HS3ST6, PAPLN and CHSY1 genes; the genes MXRA5, LYZ, CTSL2, PLAU and TIMPI and the genes FRAS1, LEPREL1, MATN2, DST, PLOD2 and ITGA2. The applied modulations, if it concerns the treatment of a hyperpigmentary spot, are the decrease of the level of expression for the genes EFEMP1, ASPN, PAPLN, CHSY1, MXRA5, LYZ, PLAU, TIMP1, FRAS1, LEPRELI, MATN2, DST, 1TGA2, COL6A3, CRTAP, LAMC1, LAMB3, LAMAS, ITGAV, ITGB1 and ACTNI and the increase of the level of expression for the genes ECM1, HS3ST6, FLRT2, PLOD2 and CTSL2. In the case of hypopigmentary spot treatment, the applied modulations are reversed. A cosmetic method according to the present invention thus comprises the application of a product, in particular chemical molecule, natural extract, active agent, nucleic acids, peptides, or a treatment modulating the level of expression or the activity of the product of expression of at least one of the dermal genes of the invention. If it is a product, it is preferably applied topically. Preferably, the modulation is effected by using a modulator of one of the genes of the invention. Such modulators are described in Example 3 and Table 3. For example, a cosmetic method according to the invention will advantageously comprise the application of a compound chosen from the demineralized bone powder (DBP), Pioglitazone, GW0742, Flavonoid Cristata L, Fenofibrate, Oxymatrin, Salvianolic acid B, SB-431542, Wen-pi-tang-Hab-Wu-ling-san extract, 3-deoxyglucosone ( Glycation end product precursor), Tetrandrin and N-acetyl-serylaspartyl-lysyl-proline (Ac-SDKP), or even among the associations of at least two of these modulators. Moreover, a cosmetic method according to the invention is advantageously used after the characterization of the pigment spot that it is desired to treat by a method according to the first aspect. Indeed, this first step makes it possible to characterize the spot and thus to detect the genes whose level of expression is strongly modulated between the zone of the spot and an uninjured zone, preferably adjacent. It is then possible to adapt a treatment which makes it possible to act on the gene or genes of the invention which are modulated differentially within this spot, by specifically applying modulators for said genes.

Whatever the treatment considered, the cosmetic method according to the invention may also comprise the application of one or more additional active compounds intended to enhance the desired effects, for example, any substance described as a depigmenting agent, keratolytic and / or desquamating agents. antioxidants, UV chemical or physical sunscreens, anti-inflammatory and / or soothing agents, deoxyribonucleic acids and their derivatives. The cosmetic method according to the present invention is also applicable in the case of the prevention of the appearance of pigment spots or other irregularities of the complexion or the color of the skin, and in particular of hyperpigmented spots such as the actinic lentigo. Indeed, the various data obtained by the inventors and detailed in the experimental part reveal that the damage to the extracellular matrix and to the TGF-E3-SMAD signaling pathway, through the genes identified by the inventors are likely to occur upstream, before the appearance of spots. It may be thought that the sequence of biological events in hyperpigmentary spots may be as follows: 1) alteration of the dermis (due to the modulation of the expression of the genes identified in this application) which leads to 2) modification of the epidermis with epidermal crest formation in the dermis which leads to 3) an increase in the length of the dermo-epidermal junction and the formation of complex networks leading to 4) an increase in the melanic charge The present invention also relates to the use of a modulator of the expression level or the activity of the expression product of at least one dermal gene chosen from the list consisting of the TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A, SMAD7 and SOSTDC1 genes, for a cosmetic application in the treatment of non-pathological skin pigment spots or more generally in the modulation of skin pigmentation. For the treatment of hyperpigmentary spots, the modulator that is used is an inhibitor of at least one gene selected from TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A and SMAD7, or an activator of the SOSTDC1 gene. Preferably, the inhibitor is a partial inhibitor leading to the decrease in the level of expression or the decrease in the activity of the expression product of said gene, without completely abolishing the expression or activity of this gene. . Conversely, for the treatment of hypopigmentary spots, the modulator used is an activator of at least one gene selected from TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A and SMAD7, or a inhibitor of the SOSTDC1 gene. Examples of inhibitors or activators already known and characterized are disclosed in Example 3 of the experimental part. Such modulators may especially be salvianolic acid B and Wen-pi-tang-Hab-Wu-ling-san extract, for use in the cosmetic treatment of hyperpigmentary spots. Well known modulators are also antisense molecules, siRNAs, and microRNAs. Preferred modulators in the context of the present invention are in particular demineralized bone powder (DBP), Pioglitazone, GW0742, Cristata L flavonoid, Fenofibrate, Oxymatrine, salvianolic acid B, SB-431542, a Wen-pi-tang-Hab-Wu-ling-san extract, 3-deoxyglucosone (Glycation end product precursor), Tetrandrine or N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP). It is also conceivable to use a combination of at least two of these modulators. Modulators as described can be used in the cosmetic methods according to the invention in combination with modulators of the EFEMPI, ECM1, ASPN, HS3ST6, PAPLN, CHSY1 and FLRT2 genes, or modulators of the MXRA5, LYZ genes, CTSL2, PLAU and TIMP1 or even modulators of FRASI, LEPRELI, MATN2, DST, PLOD2, ITGA2, COL6A3, CRTAP, LAMC1, LAMB3, LAMA3, ITGAV, ITGB1 andACTNI genes. Preferred gene combinations have already been described. Modulators can be used in combination with other products, actives or excipients. Preferably, they are packaged in a form suitable for topical application, for example in the form of ointment, cream or ointment.

The various implementations detailed in the section relating to the cosmetic methods according to the invention are applicable to the uses for the cosmetic applications described above. The modulators according to the invention can be used in particular in cosmetic applications in order to standardize the complexion, to homogenize the color of the skin or to combat dyschromias. Furthermore, according to another aspect, the present invention relates to modulators of the expression level or the activity of the expression product of at least one dermal gene chosen from the genes TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3. , SEMA5A, SMAD7 and SOSTDCI, for application in the treatment of cutaneous pigment spots, for example in the context of therapeutic treatments. Said spots may be hyperpigmentary spots, or hypopigmentary spots. Preferred modulators have already been described for the other aspects of the invention. They may be associated with other products, actives or excipients. Preferably they are packaged in a form suitable for topical application, for example in the form of ointment, cream or ointment. In the various methods and applications according to the present invention, the pigment spots considered are preferably hyperpigmentary spots and most preferably actinic, solar or senile lentigines. The methods and applications according to the invention are based on the identification by the inventors of a signature of such pigment spots. This signature is characterized in that it can be constituted by all of the list or a part of the genes mentioned. The present invention also relates to the use of this signature as a new method of selection and prediction of actinic lentigo through deficiencies in its biological functions. This new method is based on studying the level of expression of all or part of the genes described in the present invention in a hyperpigmented lesion versus an adjacent non-injured skin. This invention is also part of the treatment of the actinic lentigo, through the use of these genes as a molecular signature of the differences in gene expression existing between a lesion and the adjacent healthy skin. This signature is also an obvious advantage to determine the choice of the appropriate treatment and to measure the effect of a product (active, molecule, natural extract), but also of a process (light, injection, orally) which is beneficial on the skin. The present invention indeed makes it possible to evaluate the efficacy of a product or process intended to treat the actinic lentigo by modulating at the level of the lesion the expression of all or part of the genes described so that their profile of expression is close to that of healthy skin.

The invention also consists in a method of screening inhibition or prevention factors of actinic lentigines. It consists in evaluating compounds on their ability to inhibit or increase the expression of the genes mentioned and / or the expression or the activity of the protein products of said genes and to select them as factors to prevent, or treat the actinic lentigo. The verification of the effectiveness of the compounds can be carried out on mono or co-cultured cell models, or tri-dimensional models of reconstructed skin, or skin ex vivo, or in vivo. The subject of the invention is also the use of compounds modulating the expression of the genes identified among the biomarkers of the actinic lentigo, to prevent or correct the lesion in order to find a normal state of the skin, that is to say to recover an expression close to the expression of healthy non-injured skin. In particular, compounds acting on the proteins identified to prevent or treat pigmentary dyschromias (hyperpigmentation or hypopigmentation) have never been proposed. Such compounds exist and are reported in Table 3 of Example 3. The agents chosen are, in particular, negative modulators of proteins overexpressed by the TGF-13-SMAD signaling pathway or positive modulators of the under-expressed proteins. Among the negative modulators of the proteins of the TGF-β-SMAD signaling pathway, synthetic inhibitors and / or secretion and / or activator of the degradation of the proteins found overexpressed in the lentigo can be mentioned. Conversely, among the positive modulators, mention may be made of synthetic stimulants, secretion inducers or inhibitors of the degradation of proteins expressed in the lentigo.

Experimental part: Example 1: Transcriptional study A comparative study of the gene expression profile of the skin resulting from an injury of actinic lentigo (PL) and adjacent non-injured skin (PN) was performed. The aim of this study is to identify relevant, reproducible and significant markers reflecting the alterations associated with actinic lentigo formation, in order to use them as targets for effective treatments, or as biomarkers for analyzing efficacy. a given treatment. Briefly, 15 healthy female volunteers were recruited to participate in a full genome transcriptomic study (Affymetrix chips). For each volunteer, an actinic lentigo lesion was diagnosed on the back of the hand and the diagnosis of actinic lentigo was verified by epiluminescence. This examination allows 1 °) to verify the clinical diagnosis of the lesion (actinic lentigo exclusively) according to the pattern criteria of the dermal-epidermal junction (pigmented network structure, "fingerprint-like structure") to differentiate ephelides (absence of pigmented network structure, homogeneous pigmentation and areas of "moth-eaten edges") and flat seborrheic keratoses (multiple milia-like cysts or pseudocysts, areas of "moth-eaten edges", pseudofollicular openings and fingerprint-like patterns) [Menzies et al ; Stolz et al; Marghoob et al] 2 °) to delineate homogeneous areas in terms of structure / pattern within these lesions where cutaneous biopsies will be made, 3 °) to establish a phenotypic score based on a quantitative image analysis with the specific software that was developed on Matlae (SQA software, CMLA, ENS Cachan, UMR CNRS 8536). A 3mm biopsy centered on the lesion was performed as well as a biopsy of identical size on an adjacent non-injured skin area. The total RNAs of these samples were extracted and amplified. Probes were generated for hybridization on Affymetrix chips. Gene expression profiles were generated for each of the biopsies (2 biopsies per volunteer), and a comparative analysis was performed between PN and PL by volunteer and on all volunteers. The statistically differentially expressed genes (geometric mean of patients) were compiled into lists and grouped by functional families. Surprisingly and unexpectedly, the inventors found a differential expression for several hundred genes between PN and PL. A list of 437 genes has been constructed and represents a broad molecular signature of the actinic lentigo lesion. Of the 437 genes identified, 169 genes were positively regulated ("upregulated") in the "actinic lentigo" lesion compared to healthy skin while 269 genes were downregulated in the actinic lentigo ("regulated clowns"). ). All these genes have been subdivided into several functional families. Among the functional families or biological processes identified, the inventors have surprisingly found a family of genes reflecting at the molecular level a dysfunction of the extracellular matrix and the dermo-epidermal junction in the actinic lentigo. These genes, grouped in this functional family named "Extracellular matrix" have never been previously described as associated with the actinic lentigo and are listed below and in Tables 1 and 2: - 24 - Over-expressed genes in the actinic lentigo compared to healthy skin TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A, SMAD7, EFEMP1, ASPN, PAPLN, CHSY1, MXRA5, LYZ, PLAU, TIMP1, FRAS1, LEPREL1, MATN2, DST, ITGA2, COL6A3, CRTAP, LAMC1, LAMR3, LAMA3, ITGAV, ITGBI and ACTN1.

Under-expressed genes in actinic lentigo compared to healthy skin SOSTDC1, ECM1, HS3ST6, FLRT2, CTSL2 and PLOD2.

These genes encode components of the dermis or proteins involved in the synthesis of extracellular matrix components, related to the renewal or remodeling of this conjunctive matrix, as well as genes encoding matrix proteins associated with the dermal-epidermal junction and the area of the basement membrane. This family also contains genes related to the TGFbeta pathway involved in the synthesis of extracellular matrix components. The genes of this family are mainly expressed in the actinic lentigo. This family of genes is quite original in a pigment disorder and implies a preponderant role of the stroma in the actinic lentigo.

Table 1: list of genes of the "extracellular matrix" family found overexpressed in the actinic lentigo Subfamily Denominated name Full name Pathway I function nation accession modulation THBS2 NM_003247 thrombospondin 2 3.41 transforming growth factor, beta-TGFBI NM 000358 induced, 68kDa 2.22 BMP2 NM_001200 mud morphogenetic protein 2 2.03 SMAD3 NM_005902 SMAD family member 3 1.76 Transforming growth factor, beta TGFb! SMAD TGFBR3 NM_ 003243 receptor Ill 1.68 D50683 transforming growth factor, beta TGFBR2 NM_001024847 receptor II (70 / 80kDa) 1.61 N M_003242 week tomorrow, seven thrombospondin SEMA5A NM_003966 repeats (semaphorin) 1.56 (semaphorin 5A, semaphorin F) SMAD7 NM_005904 SMAD family member 7 1,52 -25- Subfamily Denomination-Name Full name Rate of Path I function nation accession modulation LEPREL1 NM 018192 leprecan-like 1 2,64 Collagen COL6A3 NM_004369 collagen, type VI, alpha 3 1,90 ## EQU1 ## , 64 integrin, alpha 2 (CD49B, alpha 2 1TGA2 NM 002203 subunit of VLA-2 receptor) 1.62 Integrins NM_001145000 ITGAV NM-001144999 integrin, alpha V (vitronectin receptor), 1.62 N M_002210 ITGB1 NM_133376 integrin, beta 1 1.55 MXRA5 NM_015419 matrix-remodeling associated 5 2.40 LYZ remodeling NM_000239 lysozyme (renal amyloidosis) 2.33 TIMPI matrix NM_003254 TIMP metallopeptidase inhibitor 1 2.26 PLAU NM_002658 plasminogen activator, urokinase 1.81 NM_001039348 EGF-containing fibulin-like EFEMp1 NM_001039349 extracellular matrix protein 1 3.86 NM_004105 (FIBULIN 3) and ASPN NM-017680 Asporin 2.77 and extracellular glycoprotein papilin, proteoglycan-like sulfated NM 1 73462 2.51 '$ 1 - glycoprotein CHSY1 NM_014918 carbohydrate (chondroitin) synthase 1 1.50 membrane FRASI NM_025074 Fraser syndrome 1 4 , 59 basal MATN2 NM_002380 matrilin 2 2,61 -26- Subfamily Denomination-Name Full name Rate of path / function nation accession modulation NM_001723 DST Dystonin = BPAG1 2 '24 NM 015548 NM_001130005 Actin ACTN1 NM_001130004 actinie, alpha 1 1.58 NM_001102 Table 2: list of genes of the "extracellular matrix" family found under-expressed in the actinic lentigo Subfamily Deno- Full Name of the number of path / function mination accession modulation HS3ST6 proteoglycans NM_001009606 heparan sulfate (glucosamine) 3-0- 0.44 sulfotransferase 6 PLOD2 collagens NM_000935 procollagen-lysine, 2-oxoglutarate 0.45 NM_1 82943 5-dioxygenase 2 FLRT2 proteoglycans NM_013231 fibronectin leucine rich 0.47 transmembrane protein 2 CTSL2 remodeling NM_001333 cathepsin L2 (MEC peptidase 0.54 matrix Degradation) Proteoglycans ECM1 1J65932 extracellular matrix protein 1 0.54 N M_004425 N M_022664 TGFb 1 SMAD SOSTDC NM_015464 sclerostin domain containing 1 0.62 1 (ectodin, BMP antagonist) Example 2: material and methods 15 volunteers, women, phototypes 11 to IV, aged 50 to 70 years were selected. 10 The actinic lentigines are chosen on the back of the hand, minimum size 3mm. They are characterized by Epiluminescence. The various advantages of the characterization by epiluminsecence are presented in example 1. Two biopsies of 3 mm in diameter are made on one of the hands of each patient. For each volunteer, one of the biopsies corresponds to the actinic lentigo lesion (PL) and the other to an adjacent zone of non-lesional skin (PN) (also verified in epiluminescence). The 3mm biopsies are placed, from the time of sampling, into RNA later (Qiagen reference 76106) from 16 to 24 h at 4 ° C. The following day the samples are placed at -20 ° C until the homogenization and extraction steps. Upon thawing, the samples are cut with a scalpel to facilitate homogenization, before transfer to the lysis buffer. The homogenization is carried out with a potter (Fisher Labosi ref A6391000) with RNase free polypropylene pistons (Fisher Labosi ref A1419753) allowing direct homogenization 5 in the 1.5m1 Eppendorf tubes. The RNA was extracted with the RNeasy micro kits (Qiagen ref: 74004) following the instructions of the supplier. The quantification of the RNAs is carried out by a ribogreen assay (Molecular Probes ref R11490). The quality is validated with an Agilent 2100 bioassay analyzer that gives the ratio of 28S ribosomal RNA intensities over 18S as well as an RNA Integrity Number (RIN) that accounts for RNA degradation. Good RNA has a ratio> 1.5 and a RIN> 7. A reverse transcriptase (RT) reaction is performed to obtain the corresponding cDNAs. Two probes per sample were synthesized from 50 ng of RNAs with an amplification step. The cDNAs are labeled with fluorochromes and hybridized on affymetric DNA chips to reveal the level of expression of all the genes in the human genome. (Affymetrix U133A 2.0 U133A 2.0 type biochips containing 54,000 probes, allowing the study of the expression of 47,000 transcripts, including 38,500 characterized genes). Affymetrix Microarray suite (Mas 5.0) allows to obtain for each transcript, a detection signal. After revelation of specific hybridizations and processing of raw data (extraction, subtraction of background, normalization), gene expression is compared between healthy skin and injured skin. 2 Affymetrix HG_U133 Plus 2 chips were hybridized by samples. The quality of the hybridization was carried out by the AffyPLM method (Bolstad et al., 2005) and by the PCA (Principal Component Analysis) method.

Patients are retained for further analysis only if the 2 Affymetrix chips have a correct hybridization quality. For the present study, 13 of the original 15 patients could be analyzed. The realization of a transcriptomic profile of the healthy skin and the skin corresponding to the actinic lentigo made it possible to generate lists of genes differentially expressed in the two situations, and to identify biomarkers of the actinic lentigo. The lists are generated as an expression ratio between PL (damaged skin) versus PN (normal skin). The ratio representing the geometric mean of the 13 patients is retained.

Generating Differentially Expressed Gene Lists Between Blemished Skin and Healthy Skin 35 Steps: Affymetrix Identifier Filter (ProbeSets): Only ProbeSets that are present in the two replicates of at least one biopsy are retained. After this filter 23,968 ProbeSets are retained. -28- - Suppression of the patient effect: In order to suppress the patient effect observed in the results of the differential analyzes, the expression of each ProbeSet was divided by the geometric mean of the 4 ProbeSets values corresponding to the 4 chips. - Differential analysis: it was generated by grouping the lists obtained by 2 methods, cNMF analysis (consensus Non Negative Matrix Factorization (Lee and Seung (1999), Brunet et al (2004), Fogel et al (2007) , Fogel et al. (2008)), which identified 2638 ProbeSets (1521 induced and 1117 repressed) and the Partial Least Squares Regression (PLS) method that identified 610 ProbeSets modulated. The union of the 2 lists made it possible to obtain a list of 3248 ProbeSets. - Modulation filter: for induced genes, selection of ProbeSets with a geometric mean of the 13 folds corrected (FC)? 1.5: list of 562 induced ProbeSets. For repressed genes, selection of ProbeSets with a geometric mean of 13 folds corrected FC <_ 0.67: list of 807 ProbeSets repressed. In total: 562 + 807 1369 ProbeSets modulated, ie 1007 ProbeSets after elimination of duplicates (1002 approach cNMF + 5 PLS approach) - Filter on 13 patients: visualization of modulations of 1007 ProbeSets in the form of histograms and selection of modulated ProbeSets in the same meaning in the 13 patients. Final list of 132 ProbeSets that differentiate lesional biopsies from non-lesional biopsies and are modulated in the same direction in the 13 patients in the study. - Analysis of the list of 1007 Probe sets o Filter on the P value (<0.00001) In order to retain only the most discriminating genes, we applied to the list of 1002 ProbeSets a filter on the P-value, P 5 0.00001 . After this new 827 ProbeSets filter to which are added the 5 ProbeSets resulting from the PLS approach of 832 ProbeSets list After searching for annotations, elimination of non-annotated genes and elimination of duplicates, a list of 437 genes differentially expressed between PL and PN a been established. 169 genes are over-expressed in the LA and 269 are under-expressed.

With the help of tools, Gene ontology, PubMed, Scopus the functions of the genes are sought and the genes are classified by functional families.

Example 3 Modulators There are known compounds for modulating in the desired sense the deregulated proteins in the lentigo. For the family of genes / proteins of the extracellular matrix, mention may be made of: fibrates, for example fenofibrate which decreases the expression of SMAD3, alkaloids including the oxymatrine which decreases SMAD3, or polyphenols such as for example the acid salvianolic B which decreases SMAD3 and TGFBR2, 2974370 - 29 - - natural extracts including medicinal herbs such as Wen-pi-tang-hab-wuling-san which decreases SMAD3, - compounds of the imidazole family antagonists of TGF-3R1 such as SB-431542 which decreases SMAD3, 5 - some miRNAs, notably miR183 and miR29b which decrease 1TGB1, - urokinase-type plasminogen activator (uPA) inhibitors such as paminobenzamidine or B428-subtituted benzo [bjthiophene-2- carboxamodine which decrease the activity of PLAU, - compounds of the family of phenylacetates such as NaPA which decreases expression of PLAU, - compounds of the chemical family of thiazolidinediones including for example pioglitazone which d iminue BMP2 and COL6A3; compounds of the chemical family of thiazoles including, for example, GW-0742 which decreases the expression of BMP2, compounds of the tetrazole family such as Valsartan which decreases TIMP1.

Regarding the PLOD2 enzyme protein of the extracellular family sub expressed in lentigo, the following compounds can be used to restore its level: compounds of the family of quinazolines such as Vandetanib (ZD64745 5) which increase PLOD2.

Other types of modulators may also be employed to allow correction of the expression / amount or activity of the deregulated proteins. There may be mentioned: nucleic acids (preferably antisense RNA or RNAi), neutralizing antibody, electrical, light, mechanical or thermal means. For example, low intensity pulsed ultrasound (LIPUS) may be used to increase the amount or activity of PLOD2. Conversely, in the case of hypopigmentary stain, preferred modulators will be those increasing the level of expression or activity of the proteins originating from the TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A, SMAD7 and EFEMP1 genes. ASPN, PAPLN, CHSY1, MXRA5, LYZ, PLAU, TIMP1, FRAS1, LEPREL1, MATN2, DST, LTGA2, COL6A3, CRTAP, LAMC1, LAMB3, LAMA3, 1TGAV, ITGBI and ACTN1 and those decreasing the level of expression or activity of proteins from the SOSTDC1, ECM1, HS3ST6, FLRT2, CTSL2 and PLOD2 genes. Examples of such modulators are also listed in Table 3. Table 3. LIST OF GENE MODULATORS INVOLVED IN ACTINIC LENTIGO Subfamily 1 Name Gnoprotein modulator Function sense TGFB / TGFBI modulation, transforming growth factor Bone powder demineralized bone powder (DBP) Increases SMAD R- ~ nduced 68kDa expression TGFBI BMP2, bone morphogenetic Pioglitazone Decreases expr. SMAD protein2 GW0742 Decreases expr. Cristata L flavonoid increases expr. TGFB / SMAD3, SMAD family member3 Fenofibrate Decreases SMAD expression Decreases phosphorylation Oxymatrine Salvianolic Acid B (Sal B), component of Danshen (a traditional Chinese herb used for chronic kidney disease) antioxidant and cellular protection. SB-431542 (a specific TRR-1 kinase inhibitor) Wen-pi-tang-Hab-Wu-ling-san (WHW) extract TGFBI TGFBR2, transforming growth Salvianolic acid B (SA-B) Decreases SMAD factor, p receptor II (70180kDa) TGFBI SMAD7 expression, SMAD family member 7 Oxymatrine increases SMAD expression 3-deoxyglucosone (Advanced glycation endproduct precursor) Tetrandrin N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) Collagen COL6A3, collagen, type VI, alpha 3 Pioglitazone Decreases Integral expression ITGBI, integrin, beta miR-183, miR-29b Decreases expression LYZ remodeling, lysozyme (renal amyloidosis) Pituitary adenylate cyclase-activating polypeptide (PACAP) Increases matrix PACAP38 expression -31 - Subfamily / Name Modulator gene / protein Functional sense modulating TIMP1 remodeling, Valsartan (angiotensin II type 1 receptor blocker ARB) Decreases matrix expression metallopeptidase in hi bitor 1 Plant extract of Lupinus albus LU10 Demineralized bone powder owder, DBP) Increases Express. PLAU remodeling, plasminogen activator, Sodium phenylacetate (NaPA) decreases matrix expression urokinase P-aminobenzamidine (Urokinase-type plasminogen activator (uPA) decreases inhibitor activity): B428 4, B392 -substituted benzo [b] thiophene-2-carboxamidines (Urokinase- plasminogen activator (uPA) inhibitor Thienopyridine SR 25989 (Angiogenesis inhibitor) esterified derivative of Increases ticlopidine, Notoginsenoside R1 expression (from PANAX notoginseng) Assimilated ASPN, Asporin letrozole, anastrozole Increases Protéoglycan expression Membrane MATN2, matrilin 2 vitamin K2 menaquinone Increases basal expression Collagen PLOD2, beta-aminopropionitrile (bAPN) Decreases expression procollagen-lysine, 2-oxoglutarate 5-dioxygenase 2 Low-intensity pulsed ultrasound (LIPUS) low-intensity pulsed ultrasound Increases expression / activity Vandetanib (ZD6474 5) Remodeling CTSL2, cathepsin L2 Derived phenylalanine decreases matrix activity

Claims (15)

REVENDICATIONS1. Method of characterizing a pigment spot CLAIMS1. A method of characterizing an apparent or suspected skin pigment spot in a human, including comparing levels of expression, in 2. Skin samples from said stain and adjacent non-injured skin, of at least one dermal gene involved in the TGF-β-SMAD signaling pathway chosen from the list consisting of the genes TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A, SMAD7 and SOSTDCI. 2. The method of claim 1 comprising comparing the expression levels of at least two distinct genes, preferably at least five distinct genes selected from said list. 3. The method according to claim 1, wherein said gene is selected from the list consisting of TGFBR2, TGFBI, BMP2, SMAD3, THBS2 and TGFBR3 genes. The method of claim 1, wherein said stain is confirmed as a hyperpigmental spot when the level of expression is a. in the skin sample from the stain in relation to level 20 in the uninjured adjacent skin sample, if the gene is selected from TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A and SMAD7, and b . lower in the skin sample from the stain relative to the level in the adjacent skin sample not damaged, if the selected gene is SOSTDCI. 25 5. Method according to claim 1, wherein said pigment spot is an actinic, senile or solar lentigo. 6. A method of evaluating the efficacy of a skin pigment stain treatment, comprising comparing the levels of expression in a skin sample from such stain, before and after treatment, of at least one dermal gene involved in the TGF-α-SMAD signaling pathway selected from the list consisting of TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A, SMAD7 and SOSTDCI genes. 35 The method according to claim 6, wherein said treatment is considered effective for the treatment of hyperpigmentary stains when the level of expression is: lower after treatment compared to the level of expression before treatment, if the gene is selected from TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A and SMAD7, and higher after treatment compared to the level of expression before treatment, if the selected gene is SOSTDCI. ; and is considered effective for the treatment of hypopigmentary spots when the level of expression is: higher after treatment compared to the level of expression before treatment, if the gene is selected from TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A and SMAD7, and lower after treatment compared to the level of expression before treatment, if the selected gene is SOSTDC1. 8. In vitro method for evaluating the efficacy of a treatment of cutaneous pigment spots, comprising comparing, before and after treatment, the level of expression in a representative cell model of the skin, of at least one gene dermal involved in the TGF-β-SMAD signaling pathway selected from the list consisting of TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A, SMAD7 and SOSTDCI genes, or the level of expression or activity of the expression product of said selected gene. 9. Cosmetic method for the treatment or prevention of non-pathological skin pigment spot in human skin, comprising modulating the level of expression or activity of a dermal gene involved in the TGF-fl-SMAD signaling pathway wherein said gene is selected from the list consisting of TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A, SMAD7 and SOSTDCI and wherein said modulation is effected through the use of an antisense molecule, a siRNA , a microRNA, salvianolic acid B or a Wen-pi-tang-Hab-Wu-ling-san extract. The method of claim 9, wherein said method comprises modulating at least two genes, preferably at least five distinct genes, selected from the list consisting of TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3 genes, SEMA5A, SMAD7 and SOSTDC1. 11. The method of claim 9, wherein said pigment spot is a hyperpigmentary spot, preferably an actinic, senile or solar lentigo, and wherein said modulation is an inhibition if the gene is selected from TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A and SMAD7; and an increase in expression level or activity if the selected gene is SOSTDC1. 12. Use of a modulator of the level of expression or the activity of the expression product of at least one dermal gene chosen from the list made up of the genes FR 11 53533 B09402 CA / CS August 2011 2974370 - 34 - TGFBR2 , TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A, SMAD7 and SOSTDCI, for a cosmetic application in the treatment of non-pathological skin pigment spots, wherein said modulator is selected from an antisense molecule, a siRNA, a microRNA, the powder Demineralized bone powder (DBP) demineralized bone (DBP), Pioglitazone, GW0742, Flavonoid Cristata L, Fenofibrate, Oxymatrine, Salvianolic acid B, SB-431542, Wen-pi-tang-Hab extract -Wu-ling-san, 3-deoxyglucosone (Glycation end product precursor), Tetrandrin and N-acetylseryl-aspartyl-lysyl-proline (Ac-SDKP). 10 13. Use according to claim 12, wherein said modulator is a combination of at least two modulators selected from the demineralized bone powder (DBP), Pioglitazone, GW0742, the flavonoid Cristata L, the Fenofibrate, the Oxymatrin, salvianolic acid B, SB-431542, Wen-pi-tang-Hab-Wuling-san extract, 3-deoxyglucosone (end-product glycation precursor), Tetrandrin 15 and N-acetyl- seryl-aspartyl-lysyl-proline (Ac-SDKP). 14. Modulator of the expression level or the activity of the expression product of at least one dermal gene chosen from the list consisting of the TGFBR2, TGFBI, BMP2, SMAD3, THBS2, TGFBR3, SEMA5A, SMAD7 and SOSTDCI genes, for an application in the treatment of cutaneous pigment spots, wherein said modulator is selected from an antisense molecule, a siRNA, a microRNA, demineralized bone powder (DBP), Pioglitazone, GW0742, Cristata L flavonoid Fenofibrate, Oxymatrin, salvianolic acid B, SB-431542, Wen-pitang-Hab-Wu-ling-san extract, 3-deoxyglucosone (Glycation end product precursor), Tetrandrine and N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP). 15. The modulator according to claim 14, selected from demineralized bone powder (DBP), Pioglitazone, GW0742, Cristata L flavonoid, Fenofibrate, Oxymatrine, salvianolic acid B, SB-431542. , an extract from Wen-pung-Hab-Wu-ling-san, 3-deoxyglucosone (end product glycation precursor), Tetrandrin and N-acetyl-seryl-aspartyl-lysyl-proline (Ac-1). SDKP). FR 11 53533 B09402 CA / CS August 2011