Tight junction formation accelerating agent containing glutamic acid or sodium salt thereof

Abstract

To provide a novel tight junction formation accelerating agent.SOLUTION: The present invention provides a tight junction formation accelerating agent containing glutamic acid or a sodium salt thereof.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a promoter of tight junction formation. [Background technology]

[0002] The skin, especially the epidermis, is known to have a barrier function. This barrier function prevents excessive water loss from the body and the invasion of foreign substances such as bacteria from the outside. A decrease in this barrier function is thought to be a cause of rough skin and dermatitis (xerosis and atopic dermatitis).

[0003] The epidermis is the outermost membrane of the skin, approximately 0.1 to 0.2 mm thick. New cells (keratinocytes) are constantly being born in the basal layer of the epidermis. These keratinocytes differentiate and progress through the spinous layer, granular layer, and stratum corneum to become corneocytes, which are finally exfoliated as dandruff. This process is called turnover. The epidermis undergoes turnover in a cycle of approximately one month.

[0004] During the turnover process, a cornified envelope (CE), primarily composed of keratin fibers, is formed to encase keratinocytes. The CE is formed when multiple CE precursor proteins produced in keratinocytes as they differentiate are crosslinked and insolubilized by the enzyme transglutaminase. Such CE is essential for the function of a healthy stratum corneum. Therefore, the formation and maturation of CE play an important role in improving skin barrier function.

[0005] It is also known that fluids and substances that pass through the epidermis pass through two pathways: the transcellular pathway, which is mediated by transport proteins on the cell membrane, and the paracellular pathway, which is mediated through the intercellular spaces.

[0006] Tight junctions are intercellular adhesion mechanisms (one of the intercellular bonds) that seal the spaces between cells in the cell sheet of the granular layer, controlling the transport of fluids and substances in the intercellular spaces. Tight junctions have various skin barrier functions depending on the physiological functions of the epidermis, and the skin barrier function of tight junctions can also be said to be the permeability of the paracellular pathway.

[0007] Known examples of tight junction formation promoters that are effective in improving skin barrier function include cactus fruit extract obtained from the fruit of a plant belonging to the genus Opuntia of the Cactaceae family (Patent Document 1), ambergris alba extract, acteoside, isoacteoside (Patent Document 2), and various ceramides (Patent Document 3). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent Publication No. 2012-121871 [Patent Document 2] Patent Publication No. 2023-110910 [Patent Document 3] Patent Publication No. 2023-158912 [Non-patent literature]

[0009] [Non-Patent Document 1] Wang et al., J Nutr. 2015, 145(1), 25-31 Summary of the Invention [Problem to be solved by the invention]

[0010] An object of the present invention is to provide a novel agent for promoting tight junction formation. [Means for solving the problem]

[0011] The present inventors screened various substances that are expected to have the effect of promoting tight junction formation, and found that glutamic acid exhibits such an effect of promoting tight junction formation, leading to the completion of the present invention.

[0012] Therefore, the present application includes the following inventions. [1] A tight junction formation promoter comprising glutamic acid or its sodium salt. [2] The tight junction formation promoter of [1], which promotes the formation of tight junctions in the epidermis. [3] A tight junction formation promoter of [1] or [2] that improves the epidermal barrier function. [4] A tight junction formation promoter according to any one of [1] to [3], which promotes the formation of tight junctions by promoting the expression of claudin in cells. [Effects of the Invention]

[0013] The tight junction formation promoter of the present invention enhances the barrier function of the epidermis by promoting the formation of tight junctions in the skin, and as a result is expected to increase resistance to stresses such as inflammation and, preferably, external stimuli such as ultraviolet radiation, thermal stimuli (heating and cooling), chemical agent stimuli, osmotic stimuli, and oxidative stimuli. [Brief explanation of the drawings]

[0014] [Figure 1] These results indicate that monosodium glutamate promotes claudin expression by promoting CLDN4 expression and functions as a promoter of tight junction formation. [Figure 2] This shows that monosodium glutamate enhances epidermal barrier function. DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention provides a tight junction formation promoter comprising glutamic acid or its sodium salt. It is completely unknown that glutamic acid or its sodium salt is involved in the formation of tight junctions. Although there are reports that glutamine enhances the expression of tight junction proteins in the intestine (Non-Patent Document 1), there are no reports of its involvement in the epidermis. In any case, there is no knowledge whatsoever about the role of glutamic acid or sodium glutamate in tight junctions.

[0016] Tight junctions exist in a band-like structure around cells, sealing the gaps between adjacent cells and maintaining a continuous connection between cells. Tight junctions, which exist in the granular layer of the epidermis and connect cells to each other, prevent water and substances from passing through the intercellular spaces and play an important role in maintaining the barrier function. Furthermore, research into the presence and function of proteins that make up tight junctions, such as occludin and claudins 1, 4, and 7, primarily in the granular layer of the epidermis, has progressed, and more detailed mechanisms of skin barrier function are being elucidated. The state of tight junctions can also be indirectly examined by examining the presence or absence or enhancement of the expression of these tight junction-constituting proteins, such as claudins. As shown in the Examples, the tight junction formation promoter of the present invention exhibits its tight junction formation-promoting function by promoting the expression of claudin-4 and / or claudin-7 in epidermal keratinocytes.

[0017] The tight junction formation promoter of the present invention can be suitably used in cosmetics, pharmaceuticals, quasi-drugs, and foods and beverages, taking advantage of its excellent effect of promoting tight junction formation.

[0018] Cosmetics containing the tight junction formation promoter of the present invention can be used, for example, in skin care cosmetics such as lotions, emulsions, creams, serums, and pack cosmetics, makeup cosmetics such as foundations, concealers, makeup bases, lipsticks, blushers, eye shadows, and eyeliners, sunscreen cosmetics, etc. Examples of the formulation of cosmetics include water-based, oil-based, soluble, and emulsion-based (O / W, W / O, W / O / W, and O / W / O) types.

[0019] Cosmetics containing the tight junction formation promoter of the present invention can contain, in addition to the tight junction formation promoter of the present invention, one or more components that can be freely selected and used in conventional cosmetics. For example, moisturizers, antioxidants, oily ingredients, UV absorbers, surfactants, thickeners, alcohols, powder ingredients, colorants, aqueous ingredients, water, various skin nutrients, whitening agents, anti-aging agents, anti-inflammatory agents, chelating agents, etc. can be appropriately blended as needed.

[0020] In cosmetics containing the tight junction formation promoter of the present invention, the content of the tight junction formation promoter is not particularly limited and can be freely set depending on the purpose. For example, the content of glutamic acid or its sodium salt in the cosmetic is, for example, preferably 0.01 mM mass% or more as a lower limit, more preferably 0.1 mM mass% or more, and particularly preferably 1 mM mass% or more. The upper limit is preferably 1000 mM or less, more preferably 100 mM or less, and particularly preferably 10 mM or less.

[0021] The tight junction formation promoter of the present invention can be suitably used in pharmaceuticals, quasi-drugs, and food and beverage products, taking advantage of its excellent tight junction formation-promoting effect. Pharmaceuticals and quasi-drugs can be formulated into a desired dosage form depending on the administration method, such as oral administration or parenteral administration, and the dosage form is not particularly limited. For oral administration of pharmaceuticals, the promoter can be formulated into solid preparations such as powders, granules, tablets, lozenges, and capsules; or liquid preparations such as solutions, syrups, suspensions, and emulsions. For parenteral administration, the promoter can be formulated into, for example, topical skin preparations, suppositories, vaginal tablets, inhalants, nasal drops, and injections. For quasi-drugs, the promoter can be formulated into, for example, powders, granules, tablets, lozenges, capsules, liquid preparations, syrups, topical skin preparations, ointments, aerosols, and the like. For pharmaceuticals and quasi-drugs, it is particularly preferable to formulate them into the dosage form of topical skin preparations. Examples of topical skin preparations include topical liquids, topical gels, creams, ointments, sprays, liniments, lotions, poultices, plasters, sprays, aerosols, and patches. Food and drink products may be in any form, including frozen foods, powdered foods, sheet foods, bottled foods, canned foods, retort pouch foods, capsule foods, and tablet foods, as well as processed forms such as natural liquid foods, semi-digested nutritional foods, elemental nutritional foods, and drinks containing proteins, sugars, fats, trace elements, vitamins, emulsifiers, flavorings, and the like. The types of foods and drinks are not particularly limited, and examples include candy, chewing gum, and beverages.

[0022] The drugs, quasi-drugs, and foods and beverages containing the tight junction formation promoter of the present invention can contain one or more pharmacologically acceptable additives.For example, when the drugs and quasi-drugs of the present invention are used as external preparations for skin, they can contain all additives that are commonly used in the fields of pharmaceutical preparations and quasi-drug preparations, such as bases, surfactants, preservatives, emulsifiers, colorants, odorants, fragrances, stabilizers, antiseptics, antioxidants, lubricants, solubilizers, and suspending agents.

[0023] In pharmaceuticals, quasi-drugs, and foods and beverages containing the tight junction formation promoter of the present invention, the content of the tight junction formation promoter is not particularly limited and can be freely set depending on the purpose. For example, the content of glutamic acid or its sodium salt in cosmetics is, for example, preferably 0.01 mM mass% or more as a lower limit, more preferably 0.1 mM mass% or more, and particularly preferably 1 mM mass% or more. The upper limit is preferably 1000 mM or less, more preferably 100 mM or less, and particularly preferably 10 mM or less.

[0024] The tight junction formation promoter of the present invention may mean, for example, an increase in tight junction formation 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, 200% or more, 300% or more, 400% or more, or 500% or more compared to the absence of the tight junction formation promoter of the present invention.

[0025] All documents mentioned herein are incorporated by reference in their entirety.

[0026] The following examples of the present invention are for illustrative purposes only and do not limit the technical scope of the present invention. The technical scope of the present invention is limited only by the claims. The present invention may be modified, for example, by adding, deleting, or substituting components of the present invention, provided that the modifications do not depart from the spirit of the present invention. [Example]

[0027] The present invention will be described in more detail below with reference to examples, but these examples are not intended to limit the present invention in any way.

[0028] Experiment 1: Effects of various compounds on the expression of tight junction component proteins Experimental method: Western blotting Normal human epidermal keratinocytes (NHEK) were cultured in a 6-well plate using KGM-Gold containing supplements. TMCells were seeded in medium (Lonza Verviers, Belgium) and incubated for 9 days. The medium was then changed to a calcium concentration of 1.3 mM and cultured for 4 days. After that, they were cultured for 16 days in a mixed medium supplemented with 1 ng / mL growth-promoting factors. Then, medium containing various compounds (1.3 mM calcium + 1 ng / mL growth-promoting factors) was added and treated for 24 hours. After treatment, cells were washed twice with serum-free α-MEM medium, electrophoresis sample buffer was added, and cells were harvested using a cell scraper. The samples were sonicated, subjected to SDS-page, and then Western blotting. Detection was performed using an antibody against the tight junction component protein claudin 4 (CLDN4). β-Actin was used as an internal standard. The results are shown in Figure 1. These results suggest that monosodium glutamate promotes claudin expression by promoting CLDN4 expression, and functions as a promoter of tight junction formation.

[0029] Experiment 2: Effects of various compounds on barrier function Experimental method: Permeation assay Normal human epidermal keratinocytes (NHEK) were placed in the upper chamber of a collagen-coated 24-well plate, and supplemented with KGM-Gold TM The cells were seeded in 100μL HBSS (Hank's Balanced Salt Solution) containing various compounds and 2μM FITC-dextran and incubated for 11 days. The medium was then changed to a calcium concentration of 1.3mM and cultured for 2 days. The medium in the upper chamber was then removed and dried, and the medium in the lower chamber was replaced every two days for 12 days. Then, 100μL of HBSS (Hank's Balanced Salt Solution) containing various compounds and 2μM FITC-dextran was added to the upper chamber. The cells were then incubated in an incubator for 3 hours, after which the HBSS was removed. After 24 hours, 100μL of the medium in the lower chamber was sampled, and the FITC fluorescence intensity was measured using a fluorescent plate reader.

[0030] The results are shown in Figure 2. Monosodium glutamate, which was suggested to function as a promoter of tight junction formation, was shown to reduce the amount of dextran permeation compared to the control (medium). This indicates that monosodium glutamate functions as a promoter of tight junction formation and strengthens the epidermal barrier function. [Industrial Applicability]

[0031] Glutamic acid and monosodium glutamate can promote the formation of tight junctions, and therefore can be used in cosmetics, pharmaceuticals, quasi-drugs, and foods, making them useful in the cosmetics, medical, and food industries.

Claims

1. A tight junction formation promoter comprising glutamic acid or its sodium salt.

2. The tight junction formation promoter according to claim 1, which promotes the formation of tight junctions in the epidermis.

3. The tight junction formation promoter according to claim 1, which improves the barrier function of the epidermis.

4. The tight junction formation promoter according to claim 1, which promotes the formation of tight junctions by promoting claudin expression in cells.

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