Immune function decline suppressant and method for suppressing immune function decline

Abstract

To provide novel agents for suppressing decreased immune function that can be taken inexpensively, safely, and daily and effectively improve decreased immune function caused by aging and the like.SOLUTION: The present invention provides an agent for suppressing decreased immune function, which contains wheat bran and is used to promote the production of immunoglobulin A. The agent of the present invention is preferably used, for example, to promote the production of immunoglobulin A in a state in which immunoglobulin A secretion is reduced. Furthermore, the present invention provides an agent for suppressing decreased immune function, which contains wheat bran and is used to suppress the production of interleukin-6. In these agents, preferably the wheat bran is heat-treated wheat bran.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an agent for suppressing immune function decline and a method for suppressing immune function decline.

[0002] Immunoglobulin A (also known as "immunoglobulin A antibody"; hereafter referred to simply as "IgA") is mainly present in serum and on mucosal surfaces. Mucous membranes are constantly in contact with various foreign substances, including pathogenic viruses and bacteria. Therefore, secretory IgA secreted on mucosal surfaces plays a very important role in maintaining the homeostasis of mucosal surfaces by preventing pathogens from adhering and settling on mucosal epithelial cells and neutralizing toxins and enzymes produced by pathogens. IgA is mainly secreted in gut-associated lymphoid tissues, including Peyer's patches, and mucosal-associated lymphoid tissues, where it acts as a stimulator of IgM. + IgA is produced by IgA-producing cells differentiated from B cells through class switching induced by activation-induced cytidine deaminase (AID). The IgA production pathway is broadly divided into two pathways: the T cell-dependent pathway and the T cell-independent pathway, depending on whether or not T cells are involved in the B cell class switching process. T cell-dependent IgA is stimulated by follicular T cells and follicular dendritic cells present in germinal centers such as Peyer's patches, and produces IgM. + Class-switched IgA from B cells + B cells differentiate into antibody-producing cells, produce IgA, and bind specifically and strongly to the antigen. On the other hand, T cell-independent IgA is stimulated by innate immune cells such as dendritic cells and macrophages present in the intestinal mucosa lamina propria and produces IgM. + Class-switched IgA from B cells + B cells differentiate into IgA-producing cells, produce IgA (Non-Patent Document 1), and bind to various unspecified antigens. These IgA antibodies are taken up by epithelial cells when polymeric IgA antibodies bind to the polymeric IgR (pIgR) expressed on the basement membrane of epithelial cells via the J chain, and are then secreted to the mucosal surface via endoplasmic reticulum transport. IgA is steadily produced in the T cell-independent pathway. Therefore, if IgA production through the T cell-independent pathway can be improved, it is thought that immune function will be improved by increasing the probability of immediately eliminating new antigens against which adaptive immunity has not yet been established when they come into contact with the mucosal surface.

[0003] Meanwhile, interleukin-6 (IL-6) is produced by cells such as T cells and macrophages and is one of the cytokines that regulate humoral immunity. IL-6 is involved in various physiological phenomena and the mechanisms of inflammation and immune diseases. IL-6 is a cytokine that plays an important role in hematopoiesis and inflammatory responses, and exhibits physiological effects such as promoting the differentiation of B cells into antibody-producing cells. It is also known to be secreted by activated dendritic cells, suppress the activity of regulatory T cells, and promote differentiation into Th17 cells, a T cell subset.

[0004] It is known that immune function declines due to aging, fatigue, etc., and an example of this decline is a known decrease in IgA production due to aging, fatigue, etc. In general, when immune function declines, infections are more likely to occur and become more severe. It is known that when immune function declines, inflammatory cytokines such as IL-6 increase. In particular, it is thought that a vicious cycle of immune function decline and persistent infections occurs with aging, leading to a chronic increase in inflammatory cytokines such as IL-6, which leads to chronic inflammation (Non-Patent Document 2). Therefore, if there is a composition that promotes IgA production in a state where immune function is impaired due to aging or other factors, it is believed to be particularly effective in preventing or ameliorating infectious diseases. Furthermore, an immune function decline suppressant that suppresses IL-6 production in a state where immune function is impaired due to aging or other factors is believed to be able to effectively prevent or ameliorate inflammation, particularly chronic inflammation. An immune function decline suppressant that can suppress IL-6 production in a state where immune function is impaired is excellent in its immune function suppression function, and is believed to be able to effectively prevent or ameliorate inflammation, such as the above-mentioned chronic inflammation, and to more effectively suppress, for example, the decline in function of body tissues and the decline in immune function caused by such inflammation.

[0005] Up until now, various substances have been reported to promote immunoglobulin A production or suppress interleukin-6 production (Patent Documents 1 to 6). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-57174 [Patent Document 2] Re-tabled publication 2012 / 029367 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-189304 [Patent Document 4] Japanese Patent Application Publication No. 2017-126 [Patent Document 5] International Publication No. 2016 / 195088 [Patent Document 6] Japanese Patent Application Laid-Open No. 2007-269636 [Non-patent literature]

[0007] [Non-Patent Document 1] Japanese Society of Enterobacteriaceae / (formerly) Japan Bifidobacteria Center Glossary "Secretory IgA" https: / / bifidus-fund.jp / keyword / kw059.shtml, retrieved March 30, 2021 [Non-patent document 2] Journal of the Japanese Society on Thrombosis and Hemostasis, Vol. 26, No. 3, 2015, pp. 297-301 Summary of the Invention [Problem to be solved by the invention]

[0008] As described above, components that promote IgA production in conditions where immune function is impaired, such as aging, are thought to be particularly effective in preventing or ameliorating infectious diseases, while components that suppress IL-6 production in conditions where immune function is impaired, such as aging, are thought to be particularly effective in preventing or ameliorating inflammation, such as chronic inflammation. However, conventional IgA production promoters and IL-6 production inhibitors have problems such as being too expensive for daily intake and having concerns about their adverse health effects.

[0009] Therefore, an object of the present invention is to provide a novel agent for suppressing immune function decline that is inexpensive, safe, can be taken on a daily basis, and can effectively improve the decline in immune function due to aging or the like. [Means for solving the problem]

[0010] As a result of extensive research, the inventors of the present invention have surprisingly found that oral intake of wheat bran can effectively promote the production of IgA secreted into the intestinal mucosa and can effectively suppress the production of IL-6 secreted from spleen cells in conditions where immune function is weakened due to aging or other factors.

[0011] The present invention is based on the above findings and provides an immunosuppressant containing wheat bran, which is used to promote IgA production.

[0012] The present invention also provides the agent for suppressing a decline in immune function, which is used to promote IgA production in a state where IgA secretion is reduced.

[0013] The present invention also provides an agent for suppressing decreased immune function, which contains wheat bran and is used to suppress IL-6 production.

[0014] The present invention also provides an agent for suppressing decreased immune function, which contains wheat bran and is used to promote IgA production and suppress IL-6 production.

[0015] The present invention also provides an agent for suppressing decreased immune function, which contains wheat bran and is used to suppress IL-6 production in conditions where IgA secretion is reduced.

[0016] Furthermore, the present invention provides a method for suppressing a decline in immune function by promoting IgA production using wheat bran.

[0017] Furthermore, the present invention provides a method for suppressing a decline in immune function, which uses wheat bran to promote IgA production and suppress IL-6 production.

[0018] The present invention also provides an agent for enhancing the expression of polymeric Ig receptor (pIgR) in intestinal epithelial cells, which agent contains wheat bran. [Effects of the Invention]

[0019] The present invention provides a safe and inexpensive immune function decline suppressant and a method for suppressing immune function decline that can be taken orally on a daily basis and that can effectively suppress immune function decline associated with aging, etc., as indicated by a decrease in IgA secretion, etc. Furthermore, the present invention can provide an immune function decline suppressant and a method for suppressing immune function decline that are safe and inexpensive, can be taken orally on a daily basis, and can effectively prevent or ameliorate inflammation by suppressing IL-6 production in conditions where immune function declines due to aging or other factors, thereby having excellent suppressive capabilities for immune function decline. Furthermore, the present invention can provide an agent that can effectively promote IgA production and intraluminal secretion through enhanced expression of polymeric Ig receptor (pIgR) in intestinal epithelial cells. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a graph showing the change in fecal IgA secretion levels in the wheat bran-containing diet group and the control diet group. [Figure 2] FIG. 2 is a graph showing the amount of IL-6 secreted (relative to the control) when stimulated with 1.5 μM antigen in the wheat bran-containing diet intake group and the control diet intake group. [Figure 3] FIG. 3 is a graph showing the amount of IL-6 secreted (relative to the control) when stimulated with 7.5 μM antigen in the wheat bran-containing diet intake group and the control diet intake group. [Figure 4]FIG. 4 is a graph showing that providing wheat bran to cells (HT-29 cells) increases the expression of pIgR. DETAILED DESCRIPTION OF THE INVENTION

[0021] The present invention will be described below. Hereinafter, the agent for suppressing immune function decline and the agent for enhancing pIgR expression of the present invention will also be collectively referred to as "the agent of the present invention."

[0022] The agent of the present invention contains wheat bran. Wheat bran, also known as wheat bran, generally refers to a fraction containing the outer skin (also called the epidermis) separated from the endosperm and germ of wheat seeds. Wheat bran is primarily composed of the outer skin of wheat grains. Wheat bran can be the residue from wheat grains obtained by removing the endosperm during the general wheat flour manufacturing process, or the residue from which the germ has been further removed. Wheat bran may be derived from either red wheat or white wheat, but wheat bran derived from red wheat is preferred because it has many distinctive flavors and can be continuously ingested in large amounts, which enhances the effects of the present invention.

[0023] Wheat bran contains a large amount of dietary fiber. It is preferable that the wheat bran used in the present invention contains mostly insoluble dietary fiber, as this facilitates physical stimulation of the intestinal tract. The amount of insoluble dietary fiber in wheat bran is, for example, preferably 15 to 60% by mass, more preferably 20 to 55% by mass, and particularly preferably 20 to 50% by mass, based on the dry mass of the wheat bran. The amount of insoluble dietary fiber in wheat bran can be measured by the enzymatic gravimetric method (Prosky's modified method) (AOAC 991.43). Furthermore, in the present invention, the proportion of insoluble dietary fiber in the dietary fiber is preferably 50% by mass or more, particularly preferably 80% by mass or more, from the viewpoints of intestinal regulation and anti-metabolic syndrome. For example, in wheat bran, it is preferable that 50% by mass or more of the arabinoxylan constituting it is insoluble dietary fiber, for reasons such as intestinal regulation, and preferably 80% by mass or more. The amount of dietary fiber can be measured by the enzymatic-gravimetric method (modified Prosky method) (AOAC 991.43). The amount of arabinoxylan can be measured by measuring arabinose, xylose, and galactose using high-performance liquid chromatography after acid hydrolysis and substituting the results into the following formula: Arabinoxylan content = 0.88 x (arabinose + xylose + 0.7 x galactose)

[0024] The wheat bran used in the present invention is preferably heat-treated, as this can inactivate enzyme activity and improve processing suitability using wheat bran. Heat treatments include dry heat treatment and moist heat treatment, but dry heat treatment allows for treatment at higher temperatures than moist heat treatment and is expected to be effective in removing the bitterness unique to wheat bran. As a result, this leads to continuous consumption of large amounts of wheat bran, which is preferable because it can enhance the effects of the present invention. When dry heat treatment is used as the heat treatment, the wheat bran is preferably heated to a product temperature of 100 to 180°C, more preferably 120 to 160°C, and the treatment is preferably carried out for 0 to 120 minutes, more preferably 1 to 60 minutes, for example.

[0025] When moist heat treatment is used as the heat treatment, an example of the method is to keep the wheat bran in a sealed container into which steam is introduced so that the product temperature is preferably 80 to 130°C, more preferably 85 to 110°C, for preferably 1 to 300 seconds, more preferably 1 to 60 seconds.

[0026] The form of wheat bran is not particularly limited, and may be flake, granular, powder, or the like. The particle size of wheat bran is not particularly limited, but is preferably 10 μm to 10 mm inclusive, for example, in terms of availability. The particle size of wheat bran can be measured, for example, using a Microtrac MT3000 II series (Microtrac Bell Corporation). It is more preferable that the wheat bran is crushed to the above particle size and then subjected to the above heat treatment.

[0027] The agent of the present invention is used to suppress immune function decline in mammals. Mammals include, in addition to humans, dogs, cats, mice, rats, rabbits, cows, horses, monkeys, etc. In other words, the agent for suppressing immune function decline of the present invention can be applied not only to humans, but also to pets (companions), livestock, etc. In the present invention, wheat bran can be applied to mammals in general for medical or non-medical purposes.

[0028] In the present invention, "immune dysfunction" refers to a decline in immune function due to aging, stress, strenuous exercise, insomnia, fatigue, trauma, disease, etc., compared to a state without causes of immune dysfunction (e.g., youth or health). Furthermore, "a state in which immune dysfunction is occurring" refers to a state in which immune function is about to decline, is currently declining, or has already declined due to aging, stress, strenuous exercise, insomnia, fatigue, trauma, disease, etc., compared to a state without causes of immune dysfunction (e.g., youth or health). In the present invention, suppressing immune dysfunction may involve either prevention or amelioration of immune dysfunction. Examples of immune dysfunction include a decline in the production and secretion of antibodies such as IgA due to aging, stress, strenuous exercise, insomnia, fatigue, trauma, disease, etc. Aging is generally considered to refer to a decline in physiological function associated with aging. Examples of IgA secretion include IgA secretion from mucosal surfaces such as the buccal mucosa, gastric mucosa, intestinal mucosa, olfactory epithelium, oral mucosa, and endometrial mucosa. For example, the amount of IgA secreted into the intestinal lumen can be quantified by, but is not limited to, the amount of IgA in feces using ELISA or other methods. The degree of immune dysfunction is not particularly limited, but examples include a decrease in IgA secretion compared to baseline. Here, the baseline state refers to a healthy state before the cause of immune dysfunction, such as stress or fatigue. In the case of an aging state, the baseline state refers to a healthy state during adolescence (e.g., in humans, in their 20s). For example, in the Examples described below, in the control diet group, the IgA secretion (fecal concentration) of mice aged 24 to 28 weeks, which corresponds to middle age (e.g., in humans, after their 30s), was reduced to 75% or less compared to the IgA secretion (fecal concentration) of mice aged 12 weeks, which corresponds to adolescence. However, such a significant decrease was effectively suppressed in the wheat bran-containing diet group. Thus, the present invention can promote IgA production in a state of immune dysfunction in which IgA secretion is significantly reduced to 75% or less from baseline, thereby effectively preventing or ameliorating immune dysfunction. Furthermore, the agent of the present invention can effectively prevent or improve a relatively long-term decline in immune function due to aging and the like.

[0029] The agent of the present invention can promote the secretion of immunoglobulin A onto mucosa (e.g., buccal mucosa, gastric mucosa, intestinal mucosa, olfactory epithelium, oral mucosa, endometrium, etc., preferably intestinal mucosa). This activates mucosal immunity and enhances resistance to pathogen infections such as viruses and bacteria, and poisonings caused by their toxins. From this perspective, wheat bran, the active ingredient of the agent of the present invention, is useful as an active ingredient of an agent for suppressing a decline in immune function in mucosa (e.g., buccal mucosa, gastric mucosa, intestinal mucosa, olfactory epithelium, oral mucosa, endometrium, etc., preferably intestinal mucosa). Furthermore, the agent of the present invention can be useful as an active ingredient of an agent for suppressing a decline in intestinal immune function.

[0030] In particular, the agent of the present invention preferably improves the production of IgA produced without antigenic stimulation. Examples of IgA produced without antigenic stimulation include IgA produced via a T cell-independent IgA production pathway. IgA production via a production pathway not dependent on antigenic stimulation occurs regularly. Furthermore, IgA produced via a production pathway not dependent on antigenic stimulation, unlike IgA produced via a T cell-dependent IgA production pathway, nonspecifically binds to a variety of antigens. Therefore, when a new antigen comes into contact with the mucosa, IgA produced via the T cell-independent IgA production pathway can immediately eliminate the antigen without undergoing a new immune sensitization process, thereby improving immune function. Therefore, the agent of the present invention can be used to improve defense against infectious diseases, including emerging diseases (e.g., infectious diseases caused by new pathogens to which adaptive immunity has not been established), or to maintain homeostasis of the intestinal environment, such as the intestinal flora.

[0031] Furthermore, the agent of the present invention can effectively suppress IL-6 production. In particular, the agent of the present invention can effectively suppress IL-6 production in conditions of impaired immune function, such as aging, stress, strenuous exercise, insomnia, fatigue, trauma, and illness, thereby effectively suppressing inflammation, such as chronic inflammation. The agent of the present invention can effectively suppress IL-6 production in, for example, spleen cells. Examples of inflammation that can be prevented or ameliorated by suppressing IL-6 production in the present invention include autoimmune diseases such as colitis, enteritis, and rheumatoid arthritis, neuroinflammation such as Alzheimer's disease, periodontal disease, and arteriosclerosis. For example, in the Examples described below, the IgA secretion (fecal concentration) of mice aged 28 weeks, which corresponds to middle age (e.g., late 30s or later in humans), was reduced to 75% or less compared to that of mice aged 12 weeks, which corresponds to adolescence, in the control diet group, but such a significant decrease was effectively suppressed in the wheat bran-containing diet group. Thus, the present invention can suppress IL-6 production in a state of immunocompromised function where IgA secretion is significantly reduced to 75% or less compared to baseline, and can effectively prevent or ameliorate inflammation associated with immunocompromised function. Furthermore, the agent of the present invention can effectively prevent or ameliorate inflammation associated with a relatively long-term decline in immune function, such as that caused by aging.

[0032] The agent of the present invention can also be used as an agent for enhancing the expression of polymeric Ig receptor (pIgR) in intestinal epithelial cells.

[0033] The agent of the present invention can be used as a pharmaceutical, quasi-drug, or food for mammals, or for producing such. The term "food" as used herein encompasses food in general, including general foods including so-called health foods, as well as functional foods such as foods for specified health uses and foods with nutrient functions as defined by the Ministry of Health, Labor, and Welfare's Food with Health Function Claims System, supplements, and even livestock feed and pet food fed to animals. The agent of the present invention contains wheat bran as an active ingredient and can be used as a pharmaceutical, quasi-drug, or food labeled to suppress immune function decline.

[0034] When the agent of the present invention is used as a pharmaceutical or quasi-drug, it may contain wheat bran alone as an active ingredient, or may further contain a pharmaceutically acceptable carrier. Alternatively, it may further contain other active ingredients or pharmacological ingredients to the extent that the wheat bran's effects of suppressing immune function decline, increasing IgA production or IL-6 production, and enhancing pIgR expression are not impaired. Examples of such carriers include excipients, coating agents, binders, bulking agents, disintegrants, surfactants, lubricants, diluents, dispersants, buffers, osmotic pressure adjusters, pH adjusters, emulsifiers, preservatives, stabilizers, antioxidants, colorants, UV absorbers, moisturizers, thickeners, activity enhancers, anti-inflammatory agents, disinfectants, flavorings, and odor enhancers.

[0035] When the agent of the present invention is used as a pharmaceutical or quasi-drug, it can be administered in any dosage form.The dosage form may be oral or parenteral.For example, oral dosage forms include solid dosage forms such as tablets, coated tablets, granules, powders, and capsules, and liquid dosage forms such as elixirs, syrups, and suspensions.Parenteral dosage forms include injections, infusions, transdermal, transmucosal, nasal, enteral, inhalation, suppositories, boluses, patches, etc.Among these, oral dosage forms are preferred.

[0036] When the agent of the present invention is used as a food, it may contain wheat bran alone as an active ingredient, or may further contain various additives used in the production of pharmaceuticals, quasi-drugs, and foods, so long as the effect of wheat bran in suppressing immune function decline is not impaired. Examples of such additives include various oils and fats, herbal medicines, amino acids, polyhydric alcohols, natural polymers, vitamins, dietary fiber, surfactants, purified water, excipients, stabilizers, pH adjusters, antioxidants, sweeteners, taste-providing components, acidulants such as organic acids, stabilizers, flavors, colorants, fragrances, etc.

[0037] When the wheat bran of the present invention is used as a food, its form is not particularly limited, and examples of its form include solid, semi-solid, or liquid forms, such as tablets, pills, capsules, liquids, syrups, powders, granules, etc. Specific food forms include breads, noodles, jelly foods, various snacks, baked goods, cakes, chocolates, gum, candies, tablets, capsules, soups, dairy products, frozen foods, instant foods, supplements, other processed foods, and ingredients thereof.

[0038] The wheat bran content in the agent of the present invention is not particularly limited and can be adjusted as appropriate depending on the dosage form, symptoms, age, and sex of the target (mammal), etc. However, when targeting humans, the intake amount of wheat bran in the agent of the present invention is typically preferably 5g or more, and 8g or more is particularly preferred, per adult per day in dry mass. The upper limit is preferably, for example, 50g or less to avoid side effects, and 45g or less is particularly preferred. The proportion of wheat bran in the agent of the present invention is not particularly limited and may be, for example, 1% by mass or more, 3% by mass or more, 30% by mass or more, or 50% by mass or more. The agent of the present invention can be taken orally on a daily basis, for example, for two weeks or more. Oral intake may be every day, or on one or more days within a week.

[0039] The present invention includes the following: <1> ~ <5> This includes the following forms: <1> A method for suppressing a decline in immune function by ingesting wheat bran into a living body for non-medical purposes such as maintaining health and beauty, thereby promoting the production of immunoglobulin A. <2> It is used for non-medical purposes such as maintaining health and beauty, and to promote the production of immunoglobulin A when immunoglobulin A secretion is reduced. <1> The immune function suppressant described in <3> A method for suppressing decline in immune function by having the living body ingest wheat bran for non-medical purposes such as maintaining health and beauty, thereby suppressing the production of interleukin 6. <4> A method for suppressing a decline in immune function by having a living body ingest wheat bran for non-medical purposes such as maintaining health and beauty, thereby promoting the production of immunoglobulin A and suppressing the production of interleukin 6. <5> A method for suppressing a decline in immune function by having a living body ingest wheat bran for non-medical purposes such as maintaining health or beauty, thereby suppressing the production of interleukin 6 when the secretion of immunoglobulin A is reduced. [Example]

[0040] The present invention will be described below based on examples, but the present invention is not limited to the following examples.

[0041] Example 1 (Implementation method) This study was conducted in fiscal year 2017 (from April 1, 2017, to March 31, 2018). DO11.10 female mice (10-12 weeks old) were fed an NMF diet (manufactured by Oriental Yeast Co., Ltd.) and given AIN-93M purified diet (manufactured by Oriental Yeast Co., Ltd.) ad libitum for one week. After that, feces were collected and fecal IgA levels were measured using a commercially available mouse IgA measurement kit (Bethyl Laboratories, Inc., product name IgA, Mouse, ELISA Quantitation Set). Based on the IgA levels obtained, the mice were divided into two groups of six mice each (11 weeks) to avoid significant differences between groups. After allowing each group to freely consume the AIN-93M purified diet for another week (12 weeks), the group receiving the AIN-93M purified diet was designated the control group (control diet group), and the group receiving the modified AIN-93M purified diet, which contained 5% (w / w) heat-treated red wheat bran instead of the cellulose powder contained in the AIN-93M purified diet, was designated the test group (bran-containing diet group). The dietary composition for each group is shown in Table 1 below.

[0042] [Table 1]

[0043] Feces were then collected every two weeks (weeks 14, 16, 18, 20, 22, 24, 26, and 28) over the 16-week period, and fecal IgA levels (ng / mg feces) were measured. The wheat bran was dry-heat treated at 120-150°C for 60 minutes. The wheat bran used had an average particle size within the above range. As mentioned above, the wheat bran used was derived from red wheat. The insoluble dietary fiber content of the wheat bran used (wheat bran after heat treatment) was 33% by mass, and the proportion of insoluble dietary fiber in the dietary fiber was 89.5% by mass. The mean values ​​of fecal IgA levels (ng / mg feces) obtained each week and their standard deviations are shown in FIG.

[0044] After the end of the study (28 weeks), spleen cells were collected from each mouse immediately after the end of the administration period using standard methods. The spleens were ground in a dish containing 2 ml of basal medium (RPMI1640 medium), placed in a 15 ml conical tube containing 6 ml of basal medium, suspended thoroughly, and allowed to stand for 1 minute. The fraction containing floating cells was transferred to the conical tube and centrifuged at approximately 300 G at 4°C to form a pellet. The pellet was resuspended in 4 ml of culture medium (Sigma-Aldrich) containing 10% by volume of fetal calf serum (FCS). 3 x 10 cells were placed in each well. 5 The cells were placed in 300 μl of culture medium per well, and the antigen ovalbumin was added at concentrations of 1.5 μM and 7.5 μM relative to the amount of medium in the well. The cells were cultured in an incubator at 37°C and 5% CO2 by volume to induce an antigen-specific immune response. 72 hours after addition, the amount of interleukin-6 produced in the culture supernatant was compared. Interleukin-6 was assessed using a commercially available cytokine assay kit (eBioscience). The amount of interleukin-6 was expressed relative to the average value produced by spleen cells from mice fed the control diet, which was set at 100%. The results are shown in Figures 2 and 3.

[0045] Two-tailed Student's analysis showed a significant difference (p<0.05) in fecal IgA levels between the control diet and bran diet groups at 18, 20, 22, and 26 weeks (Figure 1). As shown in Figure 1, IgA secretion levels in mice fed the control diet decreased from 12 to 16 weeks of age, and further decreased from 17 weeks of age onward. On the other hand, the wheat bran-containing diet group showed a significant suppression of the aging-related decline in IgA secretion levels.

[0046] Here, DO11.10 female mice are mice (also called TCR transgenic mice) in which most of their T cells express a T cell receptor (TCR) that responds to a specific antigen, and have significantly lower immune responsiveness to antigens other than the specific antigen. Therefore, by rearing TCR transgenic mice in an environment where they are not exposed to the specific antigen, the amount of antibodies steadily produced without antigenic stimulation can be stably quantified. In the above test, DO11.10 female mice were reared in an environment where they were not exposed to specific antigens such as ovalbumin, so the IgA secretion levels shown in Figure 1 are the amount of IgA secretion steadily produced without antigenic stimulation.

[0047] Furthermore, a two-tailed Student's analysis confirmed a significant difference (p<0.01) between the control diet group and the bran-containing diet group for the IL-6 levels shown in Figures 2 and 3, regardless of whether the antigen dose was 1.5 μM or 7.5 μM. As shown, IL-6 production at 28 weeks of age, which corresponds to middle age, was significantly suppressed in the bran-containing diet group compared to the control diet group.

[0048] Example 2 (Implementation method) The wheat bran used below was the same as in Example 1. That is, it was subjected to dry heat treatment at 120 to 150°C for 60 minutes. The wheat bran used had a particle size of 10 μm to 10 mm. The wheat bran used was derived from red wheat. The amount of insoluble dietary fiber in the wheat bran used (wheat bran after heat treatment) was 33% by mass, and the proportion of insoluble dietary fiber in the dietary fiber was 89.5% by mass. One gram of wheat bran was mixed with methanol-washed sea sand and extracted with acetic acid-acidified methanol (volume ratio: methanol 90: water 9.5: acetic acid 0.5) at 80°C for four cycles using an accelerated solvent extractor (ASE-350, Thermo Fisher Scientific). After evaporating the solvent under reduced pressure, the wheat bran extract was redissolved in 1 ml of DMSO and diluted 200-fold with E-MEM medium without FCS to prepare a sample. A negative control was prepared by diluting DMSO 200-fold with E-MEM medium without FCS. HT-29 cells (ECA: UK Health Security Agency, KAC Co., Ltd.) were suspended in E-MEM medium containing 10% FCS by volume, and 3.0 × 10 5 Cells were seeded into a 12-well plate at 100 cells / well. Two days after seeding, the cells were washed twice with Hanks(-) and 1 ml of the above sample was added to each well. After 48 hours, the culture supernatant was collected, and the cell surface was washed twice with PBS(-) or Hanks(-). RIPA lysis buffer (ATTO, 1 ml of RIPA lysis buffer was mixed with 10 μl of inhibitor, ice-cooled) was added to each well in 0.3 ml portions and allowed to stand on ice for 15 minutes. The cells were then transferred to a centrifuge tube and centrifuged at 17,000 xg for 5-10 minutes, after which the supernatant was collected in a new tube. pIgR in the supernatant was measured by ELISA (Human pIgR ELISA Pair Set, SinoBiological). A 96-well plate was loaded with 100 μL of primary antibody solution per well and incubated overnight at 4°C. After aspiration, the plate was washed twice with 300 μL of washing solution per well. 300 μL of blocking solution was added and incubated for 1 hour. After aspiration and washing, the plate was washed again. 100 μL of the supernatant was added per well and incubated for 2 hours, followed by washing. 100 μL of secondary antibody solution was added per well and incubated for 1 hour, followed by washing. 200 μL of reaction substrate solution was added per well and incubated for 20 minutes at room temperature. 50 μL of stop solution was added, and the absorbance at 450 nm was measured. Additionally, various concentrations of standard substance solutions were prepared in place of the supernatant, and added to the wells. A calibration curve was created from the results to quantify pIgR expression. The total protein content of the centrifuged supernatant was measured and corrected for pIgR per protein content for evaluation. The results are shown in Figure 4. For the negative control, the expression level was calculated by taking the pIgR per protein content measured in the same manner as 100%.

[0049] When wheat bran extract was evaluated in this cell test, it was confirmed that it increased the expression level of pIgR. HT-29 cells are commonly used as a model of intestinal epithelial cells. It is known that dimeric IgA produced in the lamina propria binds to pIgR expressed in epithelial cells, is transported intracellularly, and is secreted into the lumen. Therefore, it is thought that ingestion of wheat bran increased the expression of pIgR in intestinal epithelial cells, promoted the intraluminal secretion of IgA, and increased IgA secretion.

Claims

1. An immune function suppressant containing wheat bran, which is used to suppress a decrease in the secretion of immunoglobulin A and to suppress the production of interleukin 6 protein in the presence of an antigen.

2. An immune function decline suppressant as described in claim 1, used to increase the amount of immunoglobulin A secreted through promoting the expression of polymeric Ig receptor (pIgR).

3. 3. The agent for suppressing a decline in immune function according to claim 1, which is used to promote the production of immunoglobulin A in a state in which the secretion of immunoglobulin A is reduced, and to suppress the production of interleukin-6 protein in the presence of an antigen.

4. The immune function decline suppressant according to any one of claims 1 to 3, wherein the wheat bran is heat-treated.

5. An immune function decline suppressant described in any one of claims 1 to 4, wherein the wheat bran has been subjected to dry heat treatment at 100 to 180°C for 1 to 120 minutes, or wet heat treatment at 80 to 130°C for 1 to 300 seconds.

6. An immune function decline suppressant described in any one of claims 1 to 5, wherein the wheat bran is in the form of flakes, granules or powder with a particle size of 10 μm or more and 10 mm or less.

7. An immune function decline suppressant described in any one of claims 1 to 6, which suppresses the production of IL-6 in the spleen.

8. A method for suppressing a decline in immune function (excluding medical procedures for humans) by using wheat bran to increase immunoglobulin A secretion and suppress the production of interleukin 6 protein in the presence of an antigen.

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