Skin barrier function improver

Abstract

To provide a novel agent capable of reinforcing tight junctions to improve the barrier function of the skin.SOLUTION: The inventors have paid attention to short-chain fatty acids, which had been considered unsuitable for use in cosmetics and the like, and conducted extensive research and discovered that acetic acid, propionic acid, and lactic acid, which are short-chain fatty acids, lower transepidermal water loss (TEWL) in a three-dimensional skin model. This invention provides a skin barrier function improver containing short-chain fatty acids as an active ingredient.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an agent, composition and method for improving the barrier function of the skin. [Background technology]

[0002] The skin has a barrier function to protect the body from stresses such as dryness and the invasion of foreign substances. In the second layer of the granular layer just below the stratum corneum of the skin, there are tight junctions (intercellular adhesion structures) that bond cells together, and together with the stratum corneum, they are responsible for the skin's barrier function. It is known that when tight junctions become stronger, the skin's barrier function improves.

[0003] In normal human skin models, the pH of the stratum corneum is kept slightly acidic. In contrast, it has been reported that in human skin models with reduced tight junction function, the pH approaches neutrality. The stratum corneum is created and functions when the pH is kept slightly acidic. This suggests that when the function of tight junctions is reduced, the pH of the skin approaches neutrality, causing various abnormalities in the stratum corneum. Tight junctions are also important in preventing the loss of water in the body.

[0004] Thus, strengthening tight junctions is useful for enhancing the barrier function of the skin.

[0005] Patent Document 1 discloses an agent that enhances the expression of epidermal tight junction-associated factors as epidermal barrier function factors, while Patent Document 2 discloses an agent that enhances the expression of intercellular adhesion factors.

[0006] On the other hand, short-chain fatty acids are known to have an excellent effect on the intestinal environment. Short-chain fatty acids are organic acids such as butyric acid, propionic acid, acetic acid, and lactic acid, and are produced in the intestine by intestinal bacteria through fermentation and decomposition of indigestible carbohydrates.

[0007] Short-chain fatty acids produced in the intestine are known to lower the intestinal pH, increase good bacteria and decrease bad bacteria, improving the balance of the intestinal flora. Short-chain fatty acids are also known to contribute to preventing pathogenic infection by strengthening the barrier function of the intestinal epithelium, improving allergic inflammation, and promoting intestinal peristalsis.

[0008] Thus, although short-chain fatty acids are known to be highly useful in the intestines, little is known about their usefulness on the skin. In addition, short-chain fatty acids have a distinctive odor and are irritating and volatile, so their use in cosmetics and other products was thought to be difficult. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2022-149767 A [Patent Document 2] JP 2022-077456 A Summary of the Invention [Problem to be solved by the invention]

[0010] In order to improve the skin's barrier function, it is desirable to develop an effective ingredient that can strengthen tight junctions.

[0011] An object of the present invention is to provide a novel agent capable of strengthening tight junctions and improving the barrier function of the skin. [Means for solving the problem]

[0012] In order to solve the above problems, the present inventors focused on short-chain fatty acids, which were thought to be difficult to use in cosmetics. As a result of intensive research, the present inventors found that short-chain fatty acids, acetic acid, propionic acid and lactic acid, reduce the trans-epicellular water loss (TEWL) in a three-dimensional skin model. TEWL is used as an index of the barrier function of the skin, and a smaller value indicates a higher barrier function. In other words, the present inventors found that short-chain fatty acids have the effect of enhancing the barrier function of the skin.

[0013] The present inventors also found that short-chain fatty acids promote the expression of claudin 1, which is associated with tight junctions. The present inventors also found that short-chain fatty acids promote the expression of caspase-14, which is important for the barrier function of the skin. Furthermore, the present inventors found that short-chain fatty acids, which have been thought to be difficult to use in cosmetics, are non-irritating to the skin at low concentrations. From these findings, the present inventors found that short-chain fatty acids have the effect of improving the barrier function of the skin, and completed the present invention.

[0014] The present invention provides an agent for improving skin barrier function, which comprises a short-chain fatty acid as an active ingredient.

[0015] The present invention also provides a skin barrier function improving agent, wherein the short-chain fatty acid is one or more selected from the group consisting of acetic acid, propionic acid, lactic acid and butyric acid.

[0016] The present invention also provides a claudin-1 expression promoter comprising a short-chain fatty acid as an active ingredient.

[0017] The present invention also provides a caspase-14 expression promoter comprising a short-chain fatty acid as an active ingredient.

[0018] The present invention also provides a composition for improving skin barrier function, which contains a short-chain fatty acid as an active ingredient.

[0019] The present invention also provides a cosmetic preparation for application to the skin, comprising the above-mentioned composition for improving skin barrier function. Effect of the Invention

[0020] The short-chain fatty acid contained in the present invention can strengthen the tight junction of cells immediately below the stratum corneum of the skin, thereby improving the barrier function of the skin. The short-chain fatty acid contained in the present invention can also promote the expression of claudin 1 associated with tight junctions, and promote the expression of caspase-14, which is important for the barrier function of the skin. Therefore, the present invention can provide a novel agent that strengthens the tight junction and improves the barrier function of the skin by containing short-chain fatty acid. [Brief description of the drawings]

[0021] [Figure 1] Graph showing transpiration water loss (TEWL) after short-chain fatty acids were applied to a three-dimensional skin model and cultured for a certain period of time. [Diagram 2] Graph showing the expression level of claudin 1 in the presence of short-chain fatty acids. [Diagram 3] Graph showing cell viability (MTT) in the presence of short-chain fatty acids. [Figure 4] Graph showing the expression level of the inflammatory cytokine IL-1α in the presence of short-chain fatty acids. [Diagram 5] Graph showing the expression level of caspase-14 in the presence of short-chain fatty acids. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The present invention provides an agent for improving skin barrier function, which comprises a short-chain fatty acid as an active ingredient.

[0023] As used herein, the term "skin barrier function" refers to the inherent protective function of the skin. The skin barrier function includes, for example, moisture retention in the skin, prevention of dryness (loss of moisture) of the skin, and prevention of harmful substances such as viruses, bacteria, and allergens from entering the body. "Improvement of the skin barrier function" includes an increase or maintenance of the moisture content of the skin, inhibition of a decrease in the moisture content of the skin, a decrease in the amount of transepidermal water evaporation from the skin, and improvement or prevention of diseases or symptoms caused by a decrease in the skin barrier function. Diseases and symptoms caused by a decrease in the skin barrier function include, for example, rough skin, inflammation, itchiness, sensitive skin, dry skin, wrinkles, sagging, infections, eczema, dryness, irregular skin texture, decreased transparency, desquamation, and irregular skin flora.

[0024] As used herein, "amelioration" includes alleviation and relief of the disease or condition being improved, as well as inhibition of the progression of the disease or condition. As used herein, "prevention" includes inhibition and delay of the onset of the disease or condition being prevented.

[0025] As used herein, "improved skin barrier function" is not particularly limited, and can be demonstrated, for example, by suppression of transepidermal water loss (TEWL) of the skin. "Improved skin barrier function" can be demonstrated, for example, by suppression of TEWL of 30 g / m2 in a three-dimensional skin model. 2 h or less, preferably 28 g / m 2 ·h or less. The water loss from the skin can be measured, for example, using a common water loss meter.

[0026] The present invention also provides a claudin-1 expression promoter comprising a short-chain fatty acid as an active ingredient.

[0027] Claudin 1 is one of the proteins that make up the tight junctions (cell-to-cell adhesion structures) present in the second granular layer of the skin. Tight junctions are responsible for the barrier function of the skin by adhering cells together. Promoting the expression of claudin 1 strengthens the function of tight junctions and improves the barrier function of the skin.

[0028] The present invention also provides a caspase-14 expression promoter comprising a short-chain fatty acid as an active ingredient.

[0029] Caspase-14 is one of the enzymes important for the barrier and moisturizing functions of the skin. Caspase-14 degrades the epidermal filaggrin protein to generate natural moisturizing factor (NMF), which promotes the moisturizing function of the skin. Caspase-14 also promotes the maturation of the stratum corneum on the surface of the skin, forming a barrier function.

[0030] In this specification, "promoting expression" includes increasing expression of the target protein (gene), suppressing the decrease in expression, and increasing the amount of protein, etc. In the present invention, "promoting expression" can mean that the expression level of the protein (gene) is significantly increased when an expression promoter is used, for example, compared to a state in which the expression promoter is not used, such as increased by 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, 100% or more, or 200% or more.

[0031] Short-chain fatty acids are also called SCFAs (Short-chain fatty acids), and are fatty acids in which the number of carbon atoms in the alkyl portion of the chain of carbon atoms is 6 or less. The alkyl portion of the short-chain fatty acid may be substituted with any substituent. The optional substituent includes, for example, a hydroxyl group, a halogen, a ketone group, an oxo group, and an alkoxy group having 1 to 6 carbon atoms. The short-chain fatty acids include, for example, acetic acid, propionic acid, lactic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, caproic acid, isocaproic acid, succinic acid, methoxyacetic acid, ethoxyacetic acid, 3-methoxypropionic acid, methylbutyric acid, and dimethylbutyric acid. The short-chain fatty acid contained in the present invention may be one type or two or more types. In the present invention, the short-chain fatty acid may be, for example, one or two or more types selected from the group consisting of acetic acid, propionic acid, lactic acid, and butyric acid.

[0032] The agent of the present invention contains short-chain fatty acids, and therefore can lower the pH of the skin. By using the agent of the present invention, the pH of the skin can be lowered and maintained at a preferably weak acidic level, for example, pH 4.5 to 6.5, more preferably pH 5.0 to 6.0. The agent of the present invention can also promote the expression of claudin-1 associated with tight junctions, and can also promote the expression of caspase-14, which is important for the barrier function of the skin. Through these actions, the agent of the present invention can strengthen tight junctions and improve the barrier function of the skin.

[0033] The agent of the present invention is not particularly limited, and can be blended, for example, in pharmaceutical compositions, quasi-drug compositions, and cosmetics that are applied to the skin.The pharmaceutical compositions, quasi-drug compositions, and cosmetics that the agent of the present invention is blended in can be, for example, skin external medicines such as gels, creams, ointments, liquids, lotions, patches, packs, and aerosols; skin external quasi-drugs such as gels, creams, ointments, liquids, lotions, patches, packs, and aerosols; and cosmetics such as gels, creams, ointments, liquids, lotions, patches, packs, foundations, milky lotions, beauty essences, massage cosmetics, hand creams, body lotions, and body creams.

[0034] The present invention also provides a composition for improving the barrier function of the skin, which contains a short-chain fatty acid as an active ingredient. The composition for improving the barrier function of the skin of the present invention can be contained in medicines, quasi-drugs, or cosmetics applied to the skin, and can be contained in, for example, medicines for external application to the skin such as gels, creams, ointments, liquids, lotions, patches, packs, and aerosols; quasi-drugs for external application to the skin such as gels, creams, ointments, liquids, lotions, patches, packs, and aerosols; and cosmetics such as gels, creams, ointments, liquids, lotions, packs, foundations, emulsions, beauty essences, massage cosmetics, hand creams, body lotions, and body creams.

[0035] The composition for improving the skin barrier function of the present invention and the medicine, quasi-drug and cosmetic containing the same may contain a base and / or additive to obtain a desired dosage form. Such base and / or additive include, but are not limited to, aqueous bases such as water, lower alcohols and polyhydric alcohols; oil bases such as oils, mineral oils, waxes, ester oils, fatty acids, higher alcohols, cholesterol, fatty acid triglycerides, glyceryl tri-2-ethylhexanoate, cetyl 2-ethylhexanoate and silicone oils; and additives such as surfactants, thickeners, buffers, chelating agents, antioxidants, stabilizers, preservatives, antioxidants, pH adjusters, fragrances, refreshing agents, colorants, dispersants, fluidizing agents and wetting agents.

[0036] The composition for improving the skin barrier function of the present invention and the medicines, quasi-drugs and cosmetics containing the same may further contain ingredients that are usually blended into compositions for external use on the skin, provided that the effects of the present invention are not impaired. Such ingredients include, but are not limited to, antihistamines, anti-inflammatory agents, anti-aging agents, astringents, antioxidants, moisturizing agents, blood circulation promoters, antibacterial agents, germicides, drying agents, cooling agents, warming agents, cosmetic ingredients, vitamins and amino acids.

[0037] The blending ratio of the short-chain fatty acid in the agent, composition and cosmetic of the present invention is not particularly limited as long as it is a ratio that exhibits the effect of improving the barrier function of the skin, and can be, for example, 0.001% or more, preferably 0.005% or more. The blending ratio of the short-chain fatty acid in the agent and composition of the present invention is not particularly limited, and can be a ratio that does not irritate the skin, and can be, for example, 1% or less, preferably 0.1% or less.

[0038] The present invention also provides a method for improving the barrier function of the skin, comprising providing a short chain fatty acid to the skin.

[0039] As used herein, "applying" a short chain fatty acid to the skin includes contacting the short chain fatty acid with the skin, administering the short chain fatty acid to the skin, and applying the short chain fatty acid to the skin. In the present invention, skin includes not only human skin, but also the skin of non-human animals, such as non-human mammals such as mice, rats, rabbits, cats, dogs, cows, horses, and monkeys.

[0040] In the methods of the present invention, the short chain fatty acids can be in the form of an agent or composition as described above.

[0041] The method of the present invention can provide short-chain fatty acids to the skin, and therefore can lower the pH of the skin.The method of the present invention can also promote the expression of claudin 1 associated with tight junctions, and can promote the expression of caspase-14, which is important for the barrier function of the skin.The method of the present invention can strengthen the tight junctions and improve the barrier function of the skin through these actions. EXAMPLES

[0042] Example 1 The effect of short-chain fatty acids on transepidermal water loss (TEWL) was investigated. Acetic acid, propionic acid, and lactic acid were used as short-chain fatty acids. A three-dimensional skin model (EPI-MODEL) manufactured by Japan Tissue Engineering Co., Ltd. was used for the test.

[0043] Acetic acid, propionic acid, and lactic acid were each diluted to 2.5 mM with PBS before use. Acetic acid, propionic acid, and lactic acid were added to human 3D cultured epidermis and exposed for a certain period of time. The short-chain fatty acids were then removed, and the cells were further cultured, after which the transpiration water loss (TEWL) was measured.

[0044] The transpiration water loss (TEWL) was measured using a Tewameter TM300 (Courage+Khazaka Co., Ltd.) and PBS (Nissui Pharmaceutical Co., Ltd.) was used as a control.

[0045] The TEWL measurement results are shown in Figure 1 and Table 1. Acetic acid, propionic acid, and lactic acid each had a smaller TEWL value than the control.

[0046] [Table 1]

[0047] TEWL is used as an index of the barrier function of the skin, and the smaller the value, the higher the barrier function. The results of this example showed that the short-chain fatty acids acetic acid, propionic acid, and lactic acid have the effect of enhancing the barrier function of the skin.

[0048] Example 2 Tight junctions (cell-cell adhesion structures) that exist in the second granular layer of the skin and are also known as the second barrier are mainly composed of a membrane protein called claudin-1. We investigated the effect of short-chain fatty acids on tight junctions by examining their effect on the expression level of claudin-1.

[0049] Tests were performed using the short-chain fatty acids acetic acid (AA), propionic acid (PA), lactic acid (LA) and butyric acid (BA). The short-chain fatty acids acetic acid, propionic acid, lactic acid and butyric acid were diluted to 2.5 mM with PBS and added to epidermal keratinocytes (obtained from Kurabo Industries, Ltd.), and the expression level of claudin-1 in the presence of short-chain fatty acids was measured by Western blotting according to the standard protocol. The expression level in the control was calculated by setting the expression level in the control to 1 when PBS was used.

[0050] The expression level of claudin 1 in the presence of short-chain fatty acids is shown in Figure 2 and Table 2. It was shown that the expression level of claudin 1 was significantly increased in the presence of short-chain fatty acids, particularly acetic acid, propionic acid, or butyric acid, compared to the control. These results confirmed that short-chain fatty acids promote the expression of claudin 1, thereby strengthening tight junctions and enhancing the skin barrier function.

[0051] [Table 2]

[0052] Example 3 The skin irritation of short-chain fatty acids was evaluated. The short-chain fatty acids acetic acid, propionic acid, lactic acid, and butyric acid were used to measure cell viability (MTT) and the expression level of the inflammatory cytokine IL-1α using epidermal keratinocytes (Kurabo).

[0053] Acetic acid, propionic acid, lactic acid and butyric acid were diluted to 5 mM or 2.5 mM with PBS. After culturing the three-dimensional skin model (EPI-MODEL) at 37°C for about 16 hours, acetic acid, propionic acid, lactic acid and butyric acid were added. After removing the samples and culturing further, cell viability (MTT) and expression of inflammatory cytokine IL-1α were measured.

[0054] Cell viability (MTT) was measured by performing an MTT assay according to a standard protocol. The expression level of IL-1α was measured by performing an ELISA method according to a standard protocol. The case where PBS was used was the control (non-skin irritant), and the case where 1% SDS was used was the positive control (PC; skin irritant). The MTT was calculated assuming the measurement result in the control as 100. The expression level of IL-1α was calculated as the amount of IL-1α protein.

[0055] The MTT in the presence of short-chain fatty acids is shown in Figure 3, and the expression level of IL-1α is shown in Figure 4. Even in the presence of short-chain fatty acids, the expression levels of MTT and IL-1α were almost the same as in the control. These results indicate that short-chain fatty acids are non-irritating to the skin at the low concentrations tested.

[0056] Example 4 Caspase-14 is one of the enzymes important for the barrier function and moisturizing function of the skin. Caspase-14 is an enzyme responsible for the formation of the stratum corneum on the surface of the skin. It is known that a decrease in caspase-14 can lead to skin disorders such as rough skin.

[0057] The effect of short-chain fatty acids on the expression of caspase-14 was examined. The short-chain fatty acids acetic acid, propionic acid, lactic acid, and butyric acid were diluted to 2.5 mM with PBS and added to epidermal keratinocytes (obtained from Kurabo Industries, Ltd.), and the expression level of caspase-14 was measured by Western blotting according to the standard protocol. The expression level in the control was set to 1 when PBS was used, and the expression level was calculated.

[0058] The expression level of caspase-14 in the presence of short-chain fatty acids is shown in Figure 5 and Table 3. It was shown that the expression level of caspase-14 was significantly increased in the presence of short-chain fatty acids, particularly acetic acid, propionic acid, or butyric acid, compared to the control. These results confirmed that short-chain fatty acids enhance the skin barrier function by promoting the expression of caspase-14.

[0059] [Table 3]

[0060] These results indicate that short-chain fatty acids have the effect of improving the barrier function of the skin. [Industrial Applicability]

[0061] INDUSTRIAL APPLICABILITY The present invention can provide an agent and composition for improving the barrier function of the skin, and can be suitably used in pharmaceuticals, cosmetics, and the like.

Claims

1. A skin barrier function improver that contains short-chain fatty acids as active ingredients.

2. 2. The skin barrier function improving agent according to claim 1, wherein the short-chain fatty acid is one or more selected from the group consisting of acetic acid, propionic acid, lactic acid and butyric acid.

3. A claudin 1 expression promoter containing short-chain fatty acids as active ingredients.

4. A caspase-14 expression promoter containing short-chain fatty acids as an active ingredient.

5. A composition for improving the skin's barrier function, comprising a short-chain fatty acid as an active ingredient.

6. A cosmetic preparation for application to the skin, comprising the composition for improving skin barrier function according to claim 5.

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