Anti-inflammatory Effect of Water-soluble Soy Isoflavones with Aging and the Murine Gut Microbiome
Kenji WATANABE1, Yuka KAMEI1, Ikuo KIMURA2 and Mitsuo MARUYAMA*1, 3
1Department of Mechanism of Aging, National Center for Geriatrics and Gerontology (NCGG), Aichi 474-8511
2Department of Applied Biological Science, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8538
3Department of Aging Research, Nagoya University Graduate School of Medicine, Nagoya 466-8550
ABSTRACT
Soy isoflavones are beneficial to health and are deeply involved in our diet. They are known to have anti-inflammatory and antioxidant effects, and are also effective in alleviating various symptoms related to lifestyle-associated diseases such as hypercholesterolemia and atherosclerosis. Furthermore, soybean isoflavone aglycone is a phytoestrogen, and is associated with the maintenance of endocrine function, especially for age-related diseases such as osteoporosis and postmenopausal syndrome in women. Based on previous studies, we have shown that water-soluble soy isoflavone (Soyaflavone HG, manufactured by Fuji Oil Co., Ltd.) has an anti- inflammatory effect when pre-administered in a model mouse for inflammatory bowel disease. It has also been reported to change the Firmicutes/Bacteroidetes (F/B) ratio of the intestinal microflora in young wild-type mice significantly. Here we investigate the effect of drinking Soyaflavone HG naturally on age-dependent changes in the intestinal microbiota as well as several organs and tissues in aged 24-month-old mice. C57BL/6N (male, 2 and 23-24 months old) mice were orally administered Soyaflavone HG (60 mg/kg/day) for 4 weeks. Various organs and feces were collected, and the tissues and intestinal bacterial gene sequences were analyzed. No obvious age-dependent alterations in the intestinal microflora were observed at the phylum level analysis. However, detailed analysis revealed that Akkermansia muciniphila species showed an age-dependent increase with Soyaflavone HG treatment. Analysis of tissue sections from the large intestine revealed that goblet cells, which secrete mucosal components and generally decrease with age, were maintained due to Soyaflavone HG administration. These results suggest that Soyaflavone HG plays a beneficial role in intestinal barrier function for maintaining homeostasis in the large intestine by increasing the A. muciniphila species, known to be involved in inflammation. Interestingly, we also revealed that Soyaflavone HG had an alleviating effect on age-dependent bone loss. Thus, Soyaflavone HG has potential effects on the intestinal environment and maintenance of homeostasis during physiological aging as well as on the inflammation induction model. Soy Protein Research, Japan 23, 1-9, 2020.
Key words : water-soluble soy isoflavone, murine physiological aging, intestinal microbiota
Investigation of Preventive Effects of Plant Proteins, Including Soy Protein Isolate, against Non-alcoholic Fatty Liver Disease
Hiroshi INOUE*1 and Takanori IDA2
1Metabolism and Nutrition Research Unit, Innovative Integrated Bio-Research Core, Institute for Frontier Science Initiative, Kanazawa University, Ishikawa 920-8641
2Division of Searching and Identification of Bioactive Peptides, Department of Bioactive Peptides, Frontier Science Research Center, University of Miyazaki 889-2192
ABSTRACT
Plant proteins are expected to prevent nonalcoholic fatty liver disease (NAFLD). Indeed, intake of soy protein isolate (SPI) or mung bean protein isolate (MPI) decreased hepatic triglyceride (TG) accumulation in rodents. Beta-conglycinin and 8S globulin have been reported to play an important role in the hepatic TG- reducing effect of SPI and MPI, respectively. However, because each protein is very large, with a molecular weight of approximately 150 kDa, and has no direct contact with hepatocytes, the precise mechanism of action remains to be elucidated. Here, we investigated the mechanism of hepatic TG-reduction by SPI and MPI. First, we performed a mouse experiment with a 4-week administration of casein, SPI, or MPI as a source of dietary protein along with a 60% high-fat diet. In mice administered with SPI and MPI, hepatic TG concentration and lipogenic enzyme gene expression decreased. Second, we measured the gene expression of fatty acid synthase (Fasn) in primary hepatocytes following treatment with enzymatically digested proteins, viz., MPI and casein peptides. Hepatocytes treated with MPI peptide showed lower levels of Fasn expression than in hepatocytes treated with casein peptide. Subsequently, we divided MPI peptide into fractions by solid-phase extraction and gel-filtration, and found that some fractions decreased Fasn expression. These findings indicate that SPI and MPI decrease hepatic TG concentration by reducing hepatic lipogenic gene expression. Furthermore, peptides produced during MPI digestion and absorption exert a reducing effect on hepatic lipogenesis. Soy Protein Research, Japan 23, 10-16, 2020.Soy Protein Research, Japan 23, 10-16, 2020.
Key words : NAFLD, mung bean protein isolate, SPI, lipogenesis
A Soybean Ortholog of the Membrane Transporter Involved in Water Use Efficiency
Takashi KUROMORI*, Eriko SUGIMOTO and Kazuo SHINOZAKI
RIKEN, Center for Sustainable Resource Science, Gene Discovery Research Group, Saitama 351-0198
ABSTRACT
It is important to apply our understanding of plant science to address sustainable development goals (SDGs). For example, due to climate change, cultivated land will be affected, and the use of water is becoming a serious global problem. Abscisic acid (ABA) is an ordinary phytohormone, described as a stress hormone responsible for coping with various environmental stresses in plants. Under the systemic distribution of stress signals, ABA may be a mobile molecule within the plant. Recently, ABA transport systems in plants have been investigated, and several types of ABA transporters have been reported. We previously found that AtABCG25 is a membrane transporter related to ABA intercellular transport in Arabidopsis thaliana. We also observed that AtABCG25 expression enhanced water- use efficiency in this model plant. However, the presence of AtABCG25 orthologs in different plant species has not been analyzed extensively. Here, we identified and carried out the functional characterization of an ortholog of AtABCG25 in Glycine max (soybean), viz. as GmABCG25. We tested the ABA transport activity of GmABCG25 and examined ABA-related phenotypes of GmABCG25-expressing Arabidopsis plants. Results suggest that GmABCG25 is a possible functional homolog of AtABCG25. Regulating intercellular ABA signaling using such ABA transporters may represent a novel strategy for the breeding of commercially important crops. Soy Protein Research, Japan 23, 17-21, 2020.
Key words : ABC transporter, abscisic acid, Glycine max, phytohormone, water use efficiency
Molecular Analysis of Secondary Aerenchyma Formation in Soybean
Hirokazu TAKAHASHI*
Laboratory of Plant Genetics and Breeding, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601
ABSTRACT
Internal aeration is important for the adaptation of plants to oxygen-deficient conditions. In soybean (Glycine max), secondary aerenchyma, which plays an important role in oxygen transport from the shoot to the roots, differentiates newly from the phellogen (secondary meristem), providing porous secondary tissue in the hypocotyls or roots under flooded conditions. Cellular dedifferentiation and redifferentiation occur during secondary aerenchyma formation. However, the molecular mechanisms for these processes are largely unclear. Here, we performed tissue-specific RNA sequencing using laser microdissection to identify the genes related to cellular dedifferentiation and redifferentiation. On the basis of gene expression patterns, we classified genes into 9 clusters. First, we focused on the cluster that included genes specifically expressed in phellogen. We found that this cluster includes many cell cycle-related genes. 5-ethynyl-2’-deoxyuridine (EdU), which is an analog of thymidine and is incorporated into the DNA of proliferating cells, was detected only in phellogen, suggesting that cell division occurs only in the phellogen. This result was consistent with the clustering analysis of RNA- sequencing. In addition to the cell division-related genes, genes related to xylem differentiation were also classified into the same cluster. This result suggested that regulatory mechanisms involved in secondary aerenchyma formation are similar to that of xylem differentiation. Soy Protein Research, Japan 23, 22-27, 2020.
Key words : soybean, hypocotyl, secondary aerenchyma, laser microdissection.
Utilization of the Diversity of Gene Resource in Glycine Max for Improvement of Soybean Flavor During the Food Processing
Takao KOEDUKA*
Division of Agricultural Sciences, Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Yamaguchi 753-8515
ABSTRACT
The characteristic taste and flavor of soybean seeds are thought to be important for the quality and processing suitability of soyfoods. Thus, if we can estimate and regulate the contents and compositions of soybean flavors, it would be useful for increasing the usage and consumption of soyfoods. However, there are few reports on the generation of volatile compounds during the processing of soybean seeds, especially those derived from the accumulated volatile glycosides in soybean seeds. In this study, we established a method to measure the volatile profiles after glycoside hydrolysis of soybean powders, and conducted volatile analysis for 173 lines of the worldwide and Japanese Glycine max core collection. We observed that some lines contain monoterpenes, including sabinene, (+)-4-carene, γ-terpinene, and terpinen-4-ol, unlike the common soybean cultivar "Fukuyutaka", which is produced most extensively in Japan. In future studies, genetic traits involved in the molecular mechanism of monoterpene production in soybean seeds will be investigated. Soy Protein Research, Japan 23, 28-34, 2020.
Key words : flavor, volatile glycoside, terpenes, food processing, glycoside hydrolysis
Characterization of Soybean Plants with Lipoxygenase Gene Mutated by Genome Editing
Tetsuya YAMADA*
Graduate School of Agriculture, Hokkaido University, Sapporo 060-8589
ABSTRACT
Soybean-mutant lox3, possessing a mutant allele in the Lox3 locus, was generated by site-directed mutagenesis using the CRISPR/Cas9 system. To evaluate the effect of a decrease in LOX3 activity in the seeds, the germination ability of lox3 was examined under temperature stress. lox3 seeds showed earlier germination than the wild-type seeds under all temperature conditions. The difference became clearer as the temperature increased. Subsequently, as a simulation of long-term storage of seeds, aging treatment was performed by exposing the seeds to a high temperature and humid conditions. Although most of the wild-type seeds did not germinate after the aging treatment, approximately 80% of the lox3 seeds did. This indicates that the decrease in LOX3 activity resulted in increased tolerance to long- term storage of seeds. To elucidate the physiological mechanism, the content of malondialdehyde (MDA), which is often used to evaluate lipid peroxidation, was measured in seeds after the aging treatment. MDA content in lox3 samples was lower than the wild-type samples. This result suggests that lipid peroxidation was decreased in lox3 seeds. To evaluate the gene expression level, transcriptome analysis was conducted between the lox3 and wild-type samples. Transcriptome analysis revealed that the expression of stress-response genes was increased in the wild-type seeds. This indicates that the wild-type seeds are more severely stressed than the lox3 seeds. Thus, we demonstrated that decrease in LOX activity in seeds may maintain the germination ability even under high-temperature stress or long- term storage of seeds. Soy Protein Research, Japan 23, 35-40, 2020.
Key words : Glycine max, mutant, lipoxygenase, germination, lipid peroxidation
Screening and Utilization of Soybean Mutants in ISOFLAVONE SYNTHASE (IFS) Genes
Takanori YOSHIKAWA*
Graduate School of Agriculture Plant Breeding Kyoto Univ, Kyoto 606-8502
ABSTRACT
Soybean isoflavones possess potential health benefits such as reduction in menopausal symptoms, and prevention of cancer and cardiovascular disease. Numerous studies have attempted to reveal these effects on human health. However, the physiological functions of isoflavones in plants are not fully understood. In the present study, reverse genetic screening was performed for mutants of ISOFLAVONE SYNTHASE (IFS) genes by TILLING, using EMS treatment lines of soybean variety “Fukuyutaka”, for investigating the physiological functions of isoflavones in soybean plants. Twenty-six mutants for IFS1 and 10 mutants for IFS2 were obtained from around 1,500 bulked DNA samples, which obtained from a population of 6,000 to 9,000 EMS treatment lines. Sequence analysis revealed that all the obtained mutations were single nucleotide substitutions, and most of them (88.9%) were GA/CT substitutions. Of these, 44.4% and 55.6% were homozygous and heterozygous mutations, respectively. Interestingly, only heterozygous mutations were detected for IFS2, although both types of mutations were detected for IFS1. Further studies will investigate isoflavone contents and composition in the IFS mutants, and will reveal the physiological functions of isoflavones in soybean development. Soy Protein Research, Japan 23, 41-45, 2020.
Key words : soybean, isoflavone, EMS, TILLING, IFS
Gene Mining for Candidate Transcription Factors that Regulate Soyasaponin Content in Soybean
Hikaru SEKI*, Misako KITAMURA, Takahiro SETOGUCHI and Hayato SUZUKI
Division of Advanced Science and Biotechnology, Graduate School of Engineering, Osaka University, Osaka 565-0871
ABSTRACT
Many oleanane-type triterpenoid saponins, called soyasaponins, have been isolated and characterized from soybean seeds. Recent studies have identified various enzymes, including cytochrome P450 monooxygenases and UDP-dependent glycosyltransferases, required for the biosynthesis of soyasaponins in soybean. However, the regulatory mechanisms that control their expression remain unknown. Previously, we identified a transcription factor (GubHLH3), belonging to subclade IVa of basic helix-loop-helix (bHLH) proteins, that directs soyasaponin biosynthesis in the medicinal legume Glycyrrhiza uralensis (licorice). This transcription factor could help us understand the conserved mechanisms regulating saponin biosynthesis in legumes. To test the hypothesis that bHLH-mediated signaling is conserved in legumes, we investigated the function of GubHLH3 as a regulator of saponin biosynthesis in soybean. We generated transgenic soybean hairy roots overexpressing GubHLH3. RNA-seq analysis of GubHLH3-overexpressing (GubHLH3-OX) soybean roots confirmed that the expression levels of soyasaponin biosynthetic genes were increased in the GubHLH3-OX lines compared with the control lines. These results suggest that the mechanism regulating soyasaponin biosynthesis is similar in licorice and soybean. To identify a functional ortholog of GubHLH3 from soybean, we performed homology searches against a soybean gene database, and identified two putative orthologs belonging to subclade IVa of bHLH proteins. To obtain additional candidate GubHLH3 orthologs, we performed gene co-expression analysis using known genes encoding soyasaponin biosyntheticenzymes as guide genes. This analysis identified two additional candidate GubHLH3 orthologs belonging to subclade IVa of bHLH proteins. Functional analysis of these candidate transcription factors is needed. Soy Protein Research, Japan 23, 46-51, 2020.
Key words : words : saponin, biosynthesis, cytochrome P450 monooxygenase (CYP), UDP- dependent glycosyltransferase (UGT), bHLH-type transcription factor
Food Ink Development of Soy Protein Isolate for Food 3D Printing
Makoto TAKEMASA*
Tokyo Denki University, Graduate School of Science and Engineering Life Sciences and Engineering, Saitama 350-0394
ABSTRACT
Soy protein isolate (SPI) was used to develop edible paste ink as a ‘Food Ink’, especially as protein ink for food 3D printing. Aqueous dispersion of soybean protein was prepared at various concentrations ranging from 15 to 30% to print 3D objects containing relatively high protein concentrations comparable to real meats, such as beef, pork, and chicken. Protein energy malnutrition (PEM) is often found in the elderly, and food containing a relatively large amount of protein is probably useful for them. After some improvements in both the food ink and paste extruder, SPI slurry-based food ink at 25% (w/w) can be used to print 3D food objects. This protein content is higher than that of real meats, such as beef, pork, and chicken, which ranges from 15 to 23%. Using the above SPI-based food ink, we successfully printed a steak-shaped object using SPI ink and fat ink, and sushi using SPI and carbohydrate ink. Soy Protein Research, Japan 23, 52-56, 2020.
Key words : food 3D printing, soy protein isolate (SPI), food ink, PEM, rheology
The Effect of β-conglycinin Intake Combined with Exercise on Induction of Brown-like Adipocyte Formation
Takanori TSUDA*
College of Bioscience and Biotechnology, Graduate School of Bioscience and Biotechnology, Chubu University, Aichi 487-8501
ABSTRACT
Induction of beige adipocytes in white adipose tissue (WAT) is a potential therapeutic target for the treatment of obesity and related disorders owing to the ability of these cells to release excess energy via induction of thermogenesis associated with uncoupling protein 1. The soy protein β-conglycinin (β-CG) has serum lipid-lowering and anti-obesity effects. Exercise (Ex) causes various benefits to overall metabolic health. In recent years, there have also been a number of reports showing that Ex training results in the induction of brown-like adipocytes formation in WAT. Considering this background and previous findings, we hypothesized that the combination of β-CG intake and Ex significantly induces brown-like adipocyte formation in WAT. We first examined whether intake of β-CG induces the formation of brown-like adipocytes in mice. H&E staining of inguinal WAT (iWAT) from the 20% β-CG group showed significant multilocular adipocytes, which implied that the morphological characteristics of brown-like adipocytes were not observed in the 10% β-CG group. We subsequently examined whether intake of 10% β-CG diet combined with Ex significantly induced the formation of beige adipocytes in the iWAT in mice. H&E staining of iWAT from the Ex + 10% β-CG group showed distinct multilocular adipocytes. Further, UCP1 protein expression in iWAT was increased in the Ex + 10% β-CG group compared with only Ex. Soy Protein Research, Japan 23, 57-61, 2020.
Key words : brown-like adipocyte, β-conglycinin, exercise, uncoupling protein 1
Functional Analysis of Soy Isoflavones in Skeletal Muscle Cells
Yasutomi KAMEI*
Laboratory of Molecular Nutrition, Graduate School of Life and Environment Sciences, Kyoto Prefectural University, Kyoto 606-8522
ABSTRACT
Peroxisome proliferator-activated receptor gamma co-activator-1β (PGC-1β) is a transcriptional co-activator of nuclear receptors such as the estrogen receptor- related receptor (ERR). In mice, transgenic overexpression of PGC-1β in several tissues, including the skeletal muscle, increases the expression of medium-chain acyl-CoA dehydrogenase (MCAD), which is an ERR target and a pivotal enzyme in mitochondrial fatty acid β-oxidation. Transgenic mice are hyperphagic, have elevated energy expenditure, and are resistant to high-fat diet-induced obesity. Therefore, PGC-1β is a promising target for developing functional foods to counter obesity. In this study, we screened various food-derived and natural compounds using a reporter assay system to measure the transcriptional activity of PGC-1 β. Soy-derived isoflavones, viz., genistein and daidzein, and several resveratrols activated PGC-1β. Genistein, daidzein, and trans-oxyresveratrol activated ERR- responsive element-mediated reporter activity in the presence of PGC-1β. Stable overexpression of PGC-1β in C2C12 myoblasts increased the expression of MCAD, an important enzyme in fatty acid β-oxidation. Genistein and daidzein increased MCAD mRNA levels and mitochondrial content in PGC-1β-expressing C2C12 cells. These compounds also activated ERR/PGC-1β complex-mediated gene expression. Thus, our findings may be a practical foundation for developing functional foods targeting obesity. Soy Protein Research, Japan 23, 62-68, 2020.
Key words : PGC-1β, muscle cells, isoflavone, ERR, mitochondria
Soy Protein Intake Improves Ketogenic Diet- and Muscle Atrophy-caused Hypothermia during Active Phase of Mice
Reiko NAKAO*, Ayane YAMAMOTO, Yuki SATO and Takeshi NIKAWA
Department of Nutritional Physiology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503
ABSTRACT
The homeostatic mechanism and circadian clock system regulate core body temperature (Tb) within a narrow range in homeothermic animals. Brown adipose tissue (BAT) is an important site for the production of heat through non-shivering thermogenesis (NST) during long exposures to cold. Recent studies have reported that skeletal muscles function not only in shivering (muscle contraction)-induced thermogenesis, but also in NST in response to exposure to cold. Diet is also a potent regulator of Tb. We previously reported that feeding ketogenic diets (KD), which are high in fat, low in carbohydrates, and simulate the metabolic effects of starvation, caused hypothermia during the active phase of the day in mice subjected to denervation-caused muscle atrophy. This finding suggests that the thermogenic function of skeletal muscles is essential to retain Tb under poor nutritional status. In the present study, we aimed to evaluate the effect of soy protein intake on hypothermia caused by KD and muscle atrophy in mice. Casein-containing KD was replaced with KD containing soy protein isolate (KD-SPro) or soy peptides (KD- SPep). Denervated mice were fed with casein-containing KD, KD-SPro, or KD-SPep for 10 days. Casein-containing KD diet caused hypothermia in the first half of the active phase. KD-SPro and KD-SPep diets retained the Tb to a level similar to that in normal diet. Conversely, soy protein intake did not increase locomotor activity and expression of genes associated with thermogenesis in skeletal muscles and BAT. These findings indicate that soy protein intake could promote thermogenesis in poor nutritional status without affecting the activity and expression of genes thatare known to contribute to thermogenesis in skeletal muscles and BAT. Soy Protein Research, Japan 23, 69-75, 2020.
Key words : ketogenic diet, circadian rhythm, thermogenesis, muscle atrophy, soy protein
Soy Protein-Susceptible Indigenous Gut Bacteria (SP-SIB)
- Does the Increase or Decrease of It Contribute to Host Health? -
Takashi KUDA*
Laboratory of Food Microbiology, Department of Food Science and Technology, Tokyo University of Marine Science and Technology, Tokyo 108-8477
ABSTRACT
The gut microbiome of mammals, such as humans and laboratory animals, has been found to contain hundreds of species and approximately 11 log cells/g of bacteria. Changes in the composition of the diet, including dietary fibers, lipids, and proteins, affect the gut microbiome rapidly. These microorganisms, along with their metabolites, are considered to have significant effects on the host’s health. In this study, in order to detect protein-susceptible gut indigenous bacteria (P-SIB), ICR mice were fed a high-sucrose diet containing 20% (w/w) milk casein (MC), egg white (EW), or soy protein (SP) for 14 days. The cecal microbiome was examined by 16S rDNA amplicon sequencing using a next-generation MiSeq system. Principal coordinate analysis of the operational taxonomic units revealed that the microbiomes differed among the three groups. Typical SIB found in the MC-fed group were Bacteroides acidifaciens-, B. sartorii-, Eisenbergiella sp., and Lachnospiraceae sp.-like, in the EW-fed group were Lactobacillus murinus and
Enterococcus faecium/avium-like, and in the SP-fed group were Muribaculaceae sp.-like bacteria. We also found that a few Lachnospiraceae sp.- and Clostridium disporicum -like bacteria were suppressed in EW-fed mice. Of the P-SIB detected, B. acidifaciens, L. murinus, En. faecium, and En. avium could be isolated and identified using BL agar and 16S rDNA BLAST search, respectively. However, the strictly obligate anaerobes, such as Clostridium sp. and Muribaculaceae sp., could not be isolated. In future studies, these bacteria may also be isolated from the identified
P-SIB. Soy Protein Research, Japan 23, 76-83, 2020.
Key words : gut microbiome, soy protein, milk casein, egg protein
Clarification of Inhibitory Mechanism of Microenvironment Formation by Soybean Components Targeting Tight Junction Proteins
Akira IKARI*
Laboratory of Biochemistry, Department of Biopharmaceutical Sciences, Gifu Pharmaceutical University, Gifu 501-1196
ABSTRACT
Claudins (CLDN) are components of tight junctions (TJs) in epithelial and endothelial cells. We have reported that CLDN2 is highly expressed in lung adenocarcinoma tissues, and contributes to chemoresistance. Here, the effects of soybean components, including cyanidin 3-glucoside (Cya3-G), cyanidin (Cya), and pelargonidin 3-glucoside (Pel3-G), were examined using human lung adenocarcinoma A549 cells. It was observed that Cya3-G and Cya decreased the expression of CLDN2, whereas Pel3-G had no effect. mRNA level and promoter activity of CLDN2 were decreased by Cya3-G, indicating that Cya3-G may inhibit the transcriptional activity of CLDN2. In addition, the stability of CLDN2 was reduced by Cya3-G. The reduction of CLDN2 was rescued by chloroquine, a lysosome inhibitor, but not by MG132, a proteasome inhibitor. These results suggest that Cya3-G promotes the degradation of CLDN2 in the lysosome. Next, we investigated the effect of Cya3-G on barrier function. Paracellular flux of lucifer yellow, a hydrophilic fluorescent dye, was enhanced by Cya3-G. In spheroid cells, Cya3-G enhanced the accumulation and toxicity of doxorubicin, a cytotoxic anticancer drug. These results indicate that Cya3-G may exaggerate chemosensitivity mediated by a decrease in the TJ barrier, and may be useful in preventing malignancy of lung adenocarcinoma. Soy Protein Research, Japan 23, 84-89, 2020.
Key words : chemosensitivity, claudin-2, cyanidin, lung adenocarcinoma, spheroid
Potential Effects of Soy Isoflavone Genistein on the Neuroinflammation and Depression-related Behaviors in a Mouse Model of Social Defeat Stress
Risako FUJIKAWA and Shozo JINNO*
Department of Anatomy and Neuroscience, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582
ABSTRACT
Social stress is considered a major cause of depressive disorder in humans. Recently, the resident-intruder paradigm of social defeat (SD) has been standardized as a rodent model of depression. This animal model can exhibit depression- like social avoidance behavior, a typical symptom of human depression. In this study, we analyzed the potential effect of soy isoflavone genistein on depression- related behaviors and neuroinflammation in a mouse model of SD stress. Time spent in a closed arm in the elevated plus maze (EPM) test and that spent in an avoidance zone in the social interaction (SI) test were increased by exposure to SD stress for 10 days. Results of the EPM and SI tests were not altered by subsequent administration of genistein for 14 days. In contrast, in the forced swim test, immobility was increased by SD stress, and decreased by subsequent genistein administration. The numerical densities of microglia, the resident immune cells in the brain, were increased by SD stress in the stratum pyramidale of the hippocampus, and decreased by genistein. The number of nodes and ends, and total lengths of microglial processes in the hippocampus were decreased by SD stress, and increased by genistein. Finally, we examined the potential alterations in adult hippocampal neurogenesis by SD stress and genistein, as recent studies have suggested that neuroinflammation induced by social stress may suppress the production of new neurons. The spatial densities of immature neurons were decreased by SD stress, and increased by genistein, whereas those of neural stem cells and astrocytes were not affected by SD stress or genistein. Our findings suggest that soy isoflavone genistein may, in part, alleviate depression-related behaviors and neuroinflammation caused by SD stress. Soy Protein Research, Japan 23, 90-98, 2020.
Key words : social stress, depression, hippocampus, neuroinflammation, microglia, adult neurogenesis
Effects of sMAM on Hepatic Fat Accumulation and Fecal Bile Acid Excretion in Mice Fed a High Fat Diet
Miki IGARASHI*, Akiho NAKATANI and Ikuo KIMURA
Laboratory of Nutrition and Metabolism, Department of Applied Biological Science, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509
ABSTRACT
Soybean protein isolate (SPI) has been reported to modulate hepatic lipid metabolism in animals and humans. Our group previously found that SPI intake reduced hepatic triacylglycerol accumulation, and affected the fecal secondary/ primary bile acid (BA) ratio, which may lead to dramatic changes in the gut microbiome. In addition, other groups reported that peptide products from industrial enzymatic digestion of soybean protein interacted with bile acids and stimulated fecal sterol excretion. Therefore, in this study, we investigated how SPI- originated microbiota-accessible macropeptide (sMAM), a residual fraction from an industrial enzymatic digestion of soy protein, affects hepatic lipid accumulation, bile acid excretion, and gut microbiome using a C57BL/6 mouse model fed with high-fat diet for 4 weeks, with or without sMAM or SPI supplementation. The sMAM and SPI diets suppressed triacylglycerol accumulation in the liver compared with the casein diet. In addition, sMAM reduced cholesterol accumulation in the liver. Fecal BA excretion was increased by sMAM diet compared to the SPI diet, although both SPI and sMAM modulated the secondary/primary BA ratio in a similar way. Interestingly, sMAM induced an expansion of certain microbiota at the family level, which may be involved in BA metabolism; however, it was clearly independent of the SPI diet. These findings collectively indicate that sMAM can reduce hepatic fat accumulation, rather than SPI, induced by microbiota-driven changes in BA metabolism and excretion of BAs in feces. Soy Protein Research, Japan 23, 99-105, 2020.
Key words : SPI, sMAM, bile acids, microbiome, fatty liver
Comprehensive Studies on Structure-activity Relationship of Peptides to Modulate Ghrelin Signal Aiming at Development of Anti-aging Soy Materials
Kousaku OHINATA* and Ken SHIMIZU
Graduate School of Agriculture, Kyoto University, Kyoto 611-0011
ABSTRACT
Recently, we reported that chymotrypsin-digested β-conglycinin, a major soybean seed storage protein, increases ghrelin sensitivity. Our goal was to find novel peptides that stimulate ghrelin sensitivity from the digest based on comprehensive peptide analysis of the digest and structural-relationship of ghrelin sensitivity- stimulating peptides. Using a 336-dipeptide library, we revealed that the structure of N-terminal Ser is important to stimulate ghrelin sensitivity. The Ser-Tyr (SY) sequence is often observed in the primary structure of β-conglycinin, and a dipeptide SY also stimulates ghrelin sensitivity. Candidates were obtained by focusing on the SY sequence and referring to comprehensive peptide analysis of the chymotrypsin digest. Of these synthetic candidates, we found that two novel peptides present in the digest stimulate ghrelin sensitivity. This is the first example of a ghrelin sensitivity-enhancing peptide derived from food proteins. Soy Protein Research, Japan 23, 106-110, 2020.
Key words : β-conglycinin, peptide, ghrelin sensitivity, anorexia of aging, anti-aging
Verification of Anti-inflammatory and Renal Function-suppressing Effects of Low-fat Soy Milk Intake in Elderly People
Miki TOMOE*1, Ai YAMAMOTO1, Tamaki SHINTOMI1 and Mitutaka KOHNO2
1Department of Nutrition, Faculty of Home Economics, Kyushu Women's University, Fukuoka 807-8586
2FUJI OIL HOLDINGS INC., Osaka 598-8540
ABSTRACT
In this study, "low-fat soy milk" (Fuji Oil Co., Ltd.) was added to meals (miso soup) for two months, for elderly people over 70 years of age. We investigated the nutritional status improvement and anti-inflammatory effects of low-fat soy milk intake. This study was conducted from September to December 2014 with 17 elderly people, living in carehouses, as subjects. During the test meal intake period, 85 mL of low-fat soy milk was added to miso soup for breakfast. Body measurement, simple nutritional status assessment (MNA®-SF), food intake survey, and blood biochemistry test were selected as the evaluation parameters. The experiments were conducted with the approval of the Kyushu Women's University Ethics Review Committee. MNA®-SF showed significantly higher levels during the intake period of 8 weeks than during the post-observation period, indicating the maintenance of nutritional status. Protein intake increased significantly during the intake periods of 4 and 8 weeks. The estimated glomerular filtration rate was not significantly different in the intake periods of 4 and 8 weeks compared to the previous observation period. TNF-α was significantly lower in the intake period of 8 weeks than in the previous and subsequent observation periods. Ingestion of low- fat soy milk enabled protein administration to elderly people over 70 years of age without burdening the kidney, and was thought to contribute to the maintenance of nutritional status and the anti-inflammatory effect of TNF-α. Soy Protein Research, Japan 23, 111-117, 2020.
Key words : low-fat soymilk, nutritional status, renal function, TNF-α
Effects of Equol on Metabolic Syndrome
Atsushi TAKAHASHI*1, Nobuo TANJI2, Yukio ANZAI2, Hiromichi IMAIZUMI1, Masashi FUJITA1, Manabu HAYASHI1, Kazumichi ABE1 and Hiromasa OHIRA1
1Department of Gastroenterology, Fukushima Medical School of Medicine, Fukushima 960-1295
2Department of Gastroenterology, Watari Hospital, Fukushima 960-8141
ABSTRACT
Objective: Equol, a metabolite of soy isoflavones, has been found to have favorable effects on glycolipid metabolism. Therefore, this study aimed to elucidate the effects of equol on metabolic syndrome or metabolic factors such as visceral obesity, hypertension, dyslipidemia, hyperglycemia, and fatty liver in menopausal women. Methods: Subjects were women in their 50s-60s, who underwent a health checkup at Watari Hospital between February 2018 and January 2019. Two groups (equol producers and non-producers) were compared using the χ2 test and the Mann-Whitney U-test for continuous variables. Associations between equol and metabolic factors were estimated using logistic regression analysis adjusted for lifestyle factors. Results: Among the 389 subjects, 107 (27.5%) were equol producers. Body mass index was significantly lower in equol producers than in non-producers (21.4 vs. 22.2 kg/m2, p = 0.013). Frequencies of visceral obesity (6.5% vs. 20.2%, p = 0.002) and fatty liver (22.4% vs. 36.5%, p = 0.012) were also lower in equol producers than in non-producers. Multivariable logistic regression analysis showed that equol production was significantly associated with visceral obesity, regardless of lifestyle factors (odds ratio 0.312, 95% confidence interval 0.128-0.765, p = 0.011). Conclusion: Equol was found to be associated with visceral obesity in menopausal women. Soy Protein Research, Japan 23, 118-122, 2020.
Key words : equol, metabolic syndrome, visceral obesity, menopausal women
Soy Consumption and Cardiovascular Mortality: a Cohort Study of 0.5 Million Chinese
Jiayi DONG*
Public Health, Department of Social Medicine, Osaka University Graduate School of Medicine, Osaka 565-0871
ABSTRACT
Intervention studies have shown that soy treatment improves blood pressure and blood lipids, indicating that soy intake may have a potential role in the prevention of cardiovascular disease. We aimed to investigate the prospective association of soy intake with death from cardiovascular disease in a Chinese population. A total of 0.5 million men and women, aged 30-79 years, were enrolled between January 2004 and 2008. Dietary intakes during the 12 months preceding study enrollment were assessed using a food frequency questionnaire. The hazard ratio of cardiovascular mortality associated with soy intake was obtained by Cox proportional hazards regression. Demographic information, histories of diseases, socioeconomic status, lifestyles, and dietary habits were used for covariate adjustments. The current analysis included 487,199 individuals who were free of cancer and cardiovascular disease at baseline. Compared with those who never or rarely consumed soy foods, individuals who consumed soy foods every day had a significantly lower risk of cardiovascular mortality. Subgroup analyses according to age and sex yielded similar results. In conclusion, soy consumption was associated with a lower risk of cardiovascular mortality in a Chinese population. Soy Protein Research, Japan 23, 123- 126, 2020.
Key words : soy, cardiovascular disease, mortality, prospective cohort, Chinese
The Mechanisms that Regulate Protein Preference
Tsutomu SASAKI*
Laboratory of Nutrition Chemistry, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502
ABSTRACT
Protein intake is known to be regulated independently from caloric intake. However, the precise mechanisms that regulate protein intake and protein preference remain elusive. Fibroblast growth factor 21 (FGF21) is a hepatokine secreted following various metabolic stresses. We previously reported that FGF21, which is secreted upon the ingestion of simple sugars, regulates simple sugar preference. Plasma FGF21 levels are also increased upon protein deprivation. Therefore, we hypothesized that FGF21 may regulate protein intake and protein preference. To test this hypothesis, we fed various diets containing different amounts of protein and different protein sources to mice, either under 1-food access or 2-food choices. Subsequently, we analyzed the effects of diet on plasma FGF21 levels and diet preferences. After the diet was switched from a normal chow diet (NC) to a low-protein diet (LPD), the plasma FGF21 level increased steadily for 3 to 48 h, peaking at 48 h. There was no further increase in plasma FGF21 level after 4 days compared to 2 days. After the 2-day LPD feeding, the increased plasma FGF21 level was normalized by 3-h high-protein diet (HPD) feeding, which took 24 h by NC feeding. There was no difference in HPD production by casein or soy extract. When diet choices were offered, mice preferred casein-based HPD over soy extract-based HPD, regardless of 2-day LPD feeding. Because plasma FGF21 levels changed within 3 h after the change in protein content of the diet, we plan to assess the correlation between FGF21 and protein preference within the 3-h time window in the future. Soy Protein Research, Japan 23, 127-131, 2020.
Key words : appetite, feeding behavior, FGF21, food choice, protein preference
Analysis of Aspergillus Oryzae Soybean Peptide Transporters Involved in Protease Production
Mizuki TANAKA*
Biomolecular Engineering Laboratory, School of Food and Nutritional Science, University of Shizuoka, Shizuoka 422-8526
ABSTRACT
The uptake of di/tripeptides in eukaryotes is mediated by the proton-dependent oligopeptide transporter (POT) family of proteins, currently poorly characterized for filamentous fungi. In this study, three POT family transporters, designated PotA, PotB, and PotC, were identified in Aspergillus oryzae, a filamentous fungus that produces a variety of proteolytic enzymes. All transporters were able to enhance di/tripeptide uptake in POT-deficient yeast. Comparison of growth for deletion mutants of these transporter genes suggested that PotB and PotC are responsible for di/tripeptide uptake in A. oryzae. PotA, which had the highest sequence similarity to major yeast POT (Ptr2), contributed little to the uptake. Nitrogen starvation induced potB and potC expression, but not potA expression. When Leu– Gly, Gly–Pro, and Gly–Glu were provided as nitrogen sources, potA expression was induced only by Leu–Gly, and potC expression was induced by Gly–Pro. potB expression alone was strongly suppressed by Gly–Glu. Disruption and overexpression of PrtR, a transcription factor that regulates proteolytic genes, suggested that PrtR is involved in the regulation of potA and potB, but not in potC expression. Expression levels of potC and alkaline protease, alpA, were dramatically reduced by disruption of ubrA, an ortholog of yeast ubiquitin ligase UBR1 responsible for
PTR2 expression. potA and potB expressions were only slightly affected by ubrA disruption. Thus, it may be stated that expression of individual POT genes in A. oryzae is likely controlled by different regulatory mechanisms. Soy Protein Research, Japan 23, 132-137, 2020.
Key words : Aspergillus oryzae , peptide transporter, proteolytic gene, gene regulation, transcription factor, ubiquitin ligase
The Elucidation of Regulation Mechanism in Coumestrol Biosynthesis
Kai UCHIDA*
RIKEN Center for Sustainable Resource Science, Yokohama 230-0045
ABSTRACT
Coumestrol is produced in leguminous plants such as soybean, and shows higher estrogen-like activity than isoflavones in mammals. Coumestrol is accumulated in roots, and it has been reported that its accumulation is increased by drought stress. To date, little is known about the physiological function of coumestrol and its biosynthetic regulation in plants. In this study, we carried out omics analysis of drought stress-treated soybean to elucidate the biosynthetic regulatory mechanism of coumestrol. Soybean (cv. Enrei and Fukuyutaka) seeds were sown in petri dishes containing water, and cultivated for 3 weeks. Drought stress treatment was carried out by transferring the seedlings into new sheets without water for 24 h. Soybean plants were sampled after separation into upper (leaves and stems) and bottom (roots) parts, followed by widely targeted metabolome analysis using LC-QqQ-MS and transcriptome analysis with RNA sequencing. Metabolome analysis revealed that drought stress increased the accumulation of coumestrol and isoflavone aglycones mainly in the roots, and decreased the accumulation of isoflavone glycosides in all parts. This result indicates that drought stress led to sugar hydrolysis of isoflavonoid glycosides. Drought stress induced an increase or decrease in the expression of enzymatic genes associated with isoflavonoids. Although drought stress induced accumulation of coumestrol, expression of isoflav- 3-ene synthase, which is a key enzyme in coumestrol biosynthesis, was dramatically reduced. These results suggest that drought stress increases coumestrol content by sugar hydrolysis, and decreases the expression of genes involved in coumestrol biosynthesis. Soy Protein Research, Japan 23, 138-143, 2020.
Key words : coumestrol, isoflavone, drought stress, omics analysis
Soybean Products Recognition Mechanism in Stored-grain Pest, Tribolium Castaneum
Shingo KIKUTA*
College of Agriculture, Ibaraki University, Ibaraki 300-0393
ABSTRACT
Red flour beetle Tribolium castaneum (Herbst) is a destructive, cosmopolitan pest in stored houses. The beetles feed on various foods such as wheat flour, chocolate, dry fruits, cereals and soybean flours. It remains unknown the effect of soybean flours and secondary metabolites derived from the soybean. The dietary intake of T. castaneum adult beetles was suppressed under the diets in the presence of soybean flours compared with that of wheat flours. I next tried to identify the gustatory repellents contained in soybean flour. It is known that isoflavones contained in soybean flour affect insect feeding. The survivals of the beetle in the presence of genistein, one of the flavonoids, significantly decreased, indicating that genistein acts as lethality against the beetles. Using the cultured cells derived from T. castaneum embryos, the lethal activity was also observed. It is known that isoflavones contained in soybean flour affect the feeding of insects. Food consumption by the beetles decreased significantly in the presence of genistein. Genistein receptors could not be identified by analysis using the Xenopus oocyte expression system. When isoflavones were added to the cultured cells Tc81 established from the T. castaneum embryos, the inhibitions of cell growth and proliferation under genistein additions. The results indicate that genistein affects Tc81 cells. Genistein candidate receptors may express in the Tc81 cells. Reduced pesticide use for insect control will be ideal in the recent tendency. Since genistein is a natural compound contained in soybean, it is expected to be used as a pest control agent for the stored-grain pests. Soy Protein Research, Japan 23, 144-149, 2020.
Key words : red flour beetle, cultured cell, genistein, cytotoxicity, biopesticide
Gas Phase CD Spectroscopy of Soy Protein in the Single Molecular Level
Hiroya ASAMI*, Akihiro KITAZAKI and Jun-ya KOHNO
Department of Chemistry, Faculty of Science, Gakushuin University, Tokyo 171-8588
ABSTRACT
Soy protein has a main component, glycinin (m/z = ca. 360,000), which consists of a hexamer of A and B subunits. In general, X-ray crystallography and NMR spectroscopy are considered to be effective tools for the structural analysis of such large biomolecules. However, it is difficult to obtain the structural information of an isolated molecule because of the presence of the solvent. Isolated structural information, analogous to a single molecular structure, is important for understanding the fundamental properties of a substance in physical chemistry and biochemistry. In this study, we measured the mass spectrum of glycinin for the observation of its isolated ions. The mass spectrum indicated the existence of divalent glycinin ions and three types of glycinin subunits, assignable to A, B, and AB complex. Furthermore, we also measured the photoelectron detachment yield (PDY) and gas-phase circular dichroism (CD) spectra of isolated glycinin and its subunits ions, generated by IR-laser ablation of droplet beam. The PDY spectrum indicated characteristic absorptions related to skeletal peptide bonds (197-200-and 208 nm), with a significant absorption of the negative-charged side chain of acidic amino acids (192 nm). The gas-phase CD spectrum indicated four negative bands at 195, 198, 204, and 207 nm. This spectral feature corresponds well with that of the CD spectrum in the aqueous solution, which has already been assigned to the β-sheet and random coil structures of glycinin. Hence, the four negative bands observed in this study can also be assigned to these secondary structures. Soy Protein Research, Japan 23, 150-154, 2020.
Key words : CD spectroscopy, glycinin, gas phase, deep UV, droplet
Development of the Method for Structural Analysis of Soybean Seed Storage Protein by Small Angle Neutron Scattering
Aya OKUDA*
Institute for Integrated Radiation and Nuclear Science, Kyoto University, Osaka 590-0494
ABSTRACT
The major seed storage proteins of soybean, viz., glycinin and β-conglycinin, possess processing characteristics by forming aggregates and gels due to disulfide bonds and intermolecular interactions. It is believed that different structures are formed and various physical properties are exhibited depending on the physical and chemical conditions during processing. Therefore, the relationship between the structural and physical properties is revealed, allowing the deployment of new food processing techniques using soybean protein. Small-angle scattering is suitable for the analysis of nanoscale structures that contribute to the physical properties. Notably, we employ contrast-matching small-angle neutron scattering (SANS), in which the specific structures are isotope-labeled and selectively analyzed by utilizing the great difference of the neutron scattering length density between light hydrogen and deuterium. In this study, we aimed to develop a method for the structural analysis of soybean seed storage proteins using this method. For scattering experiments, large amounts of contaminant-free and monodisperse proteins are required. Thus, the optimal culture conditions in heavy water M9 medium for obtaining large amounts of deuterated protein using the E. coli expression system of glycinin and β-conglycinin was examined. In addition, the purification processes were optimized to obtain high-quality proteins which were suitable for scattering experiments. For selective measurement in contrast- matching SANS, accurate control of the deuteration rate of recombinant proteins is essential. Since it is necessary to measure the deuteration rate accurately, we established a rigorous method for measurement of the deuteration rate using mass spectrometry by utilizing the mass difference between light hydrogen and deuterium. Soy Protein Research, Japan 23, 155-158, 2020.
Key words : soybean seed storage protein, glycinin, β-conglycinin, small-angle neutron scattering (SANS), protein deuteration
Identification of Human Olfactory Receptor Sensing n-Hexanal, the Causative Compound of Grassy Smell in Soybean Products
Yuko TERADA*1, Kayano SATO1, Sakura TSUCHIYA2, Kohei KODUKA2, Shogo NAKANO1, Sohei ITO1 and Keisuke ITO1
1School of Food and Nutritional Sciences, University of Shizuoka, Shizuoka 422-8526
2Graduate Program in Food and Nutritional Sciences, Graduate School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka, Shizuoka 422-8526
ABSTRACT
n-Hexanal, a causative compound of unpleasant grassy smell, is a major problem when soy products are used in the food industry. In the present study, we aimed to identify odorant receptors for n-hexanal from 389 human olfactory receptors, and explore odor masking agents for n-hexanal from food compounds. We first established a human olfactory receptor assay system using HEK cells that ectopically express the olfactory receptor, Gαolf, and cAMP-sensitive luciferase. We next constructed our original molecular phylogenetic tree comprising of the 389 olfactory receptors based on sequential homology of their substrate-binding pockets. The 389 receptors were classified into five large groups in the phylogenetic tree. We selected 17 receptors as representatives of each group and examined their responses to n-hexanal. Among them, OR2W1 was activated by n-hexanal in a concentration-dependent manner, whereas the other receptors did not show any response to n-hexanal. EC50 and response threshold of n-hexanal on OR2W1 were calculated as 100μM and 30μM, respectively. In the next experiment, we screened odor masking agents for n-hexanal from food compounds using the olfactory receptor assay system and human sensory evaluation. α-Pinene, a fresh odorant contained in rosemary and pepper, was found to attenuate the OR2W1 response by n-hexanal in the receptor assay system. Furthermore, α-pinene effectively masked the unpleasant grassy smell of n-hexanal in sensory evaluation. Therefore, α-pinene is a promising candidate as an odor-masking agent for n-hexanal. Soy Protein Research, Japan 23, 159-164, 2020.
Key words : soybean, grassy smell, n-hexanal, olfactory receptor, OR2W1
Mechanism of Female-specific Anorectic Effect of the Microbial-derived Isoflavone Metabolite Equol
-Identification of the Active Metabolites of Equol-
Mina FUJITANI*, Akira YASHIKI, Haruka SUZUKI and Taro KISHIDA
Laboratory of Nutrition Science, Division of Applied bioscience, Graduate School of Agriculture, Ehime University, Matsuyama 790-8566
ABSTRACT
We previously reported that equol produced by the intestinal microbiota after ingestion of its precursor daidzein, an isoflavone present in soy, decreases food intake, specifically in female rats. Furthermore, we have shown that dietary daidzein induces accumulation of equol metabolites in enterohepatic circulation, and the major metabolites were equol 4’-O-glucuronide and equol 7-O-sulfate. We performed a procedure in which bile taken from female donor rats, fed a daidzein diet, was infused into the duodenum in other female rats fed a control diet. The bile infusion significantly decreased food intake in female rats, suggesting that equol metabolites in the bile of female rats induced an anorectic effect. In the present study, we measured the bile concentrations of total equol metabolites, equol 4’-O-glucuronide, and equol 7-O-sulfate in male, female, and ovariectomized rats fed a diet containing daidzein, using liquid chromatography-mass spectrometry. Bile concentrations of total equol metabolites and equol 4’-O-glucuronide of female rats were significantly higher than those of male rats. There were no significant differences between sexes in the bile equol 7-O-sulfate concentration. The major equol metabolite in male rats was equol 7-O-sulfate, whereas equol 4’-O-glucuronide was predominant in female rats. Ovariectomy did not affect the bile concentrations of total equol metabolites, equol 4’-O-glucuronide, or equol 7-O-sulfate significantly. Although further studies are needed, it can be speculated that equol 4’-O-glucuronide may be involved in the female-specific anorectic effect. Soy Protein Research, Japan 23, 165-169, 2020.
Key words : soy isoflavone, daidzein, equol, conjugate, appetite, enterohepatic circulation
Elucidation of the Anti-inflammatory Effect of Soy Isoflavones by Innate Lymphoid Cells in Visceral Adipose Tissue
Takuro OKAMURA*
Department of Endocrinology and Metabolism, Kyoto Prefectural University of Medicine, Kyoto 602-8566
ABSTRACT
In Japan, the number of type 2 diabetes patients has been increasing due to the westernization of diet, especially the increase in simple carbohydrate and fatty acid intake. Innate lymphoid cells (ILCs) have been implicated in the development of chronic inflammation. ILC2 promotes beiging of white adipose tissue and controls obesity. In this study, we investigated the anti-inflammatory effect of isoflavones in visceral adipose tissue using animal models. Isoflavones are administered to wild-type mice, in which 7-week-old female wild-type mice are ovariectomized and reared from 8 to 14 weeks of age. Mice were divided into four groups: normal diet (ND) ± isoflavones, and high-fat high-sucrose diet (HFHSD) ± isoflavones. Gene expression analysis in visceral adipose tissue by RT-PCR showed that isoflavones significantly reduced the expression of proinflammatory cytokines and lipid metabolism-related genes. Flow cytometric analysis of immune cells in visceral adipose tissue showed that isoflavones markedly increased ILC2s in both ND and HFHSD groups, and decreased the M1/M2 macrophage ratio in the HFHSD group. Furthermore, the expression of Ucp-1, which is seen to beige in white adipose tissue, was significantly increased in both ND and HFHSD groups upon isoflavone- treatment. In conclusion, we found that isoflavone administration improved visceral fat obesity by shifting the innate immunity within visceral fat to anti-inflammatory effects. Soy Protein Research, Japan 23.
Key words : Isoflavone, innate immunity, innate lymphoid cells, adipose tissue
The Effect of Soy Protein Intake on the Decrease in Muscle and Satellite Cell by Energy Restriction in Young Female Rats
Yuki AIKAWA*1, Yusuke WAKASUGI2, Takahiro NARUKAWA2, Makoto OHTSUKI2,3 and Nobuaki SASAI2
1Department of Science of Living, Tsu City Collge, Mie 514-0112
2Faculty of Health Science, Suzuka University of Medical Science 510-0293
3Faculty of Nutrition University of Kochi 781-8515
ABSTRACT
This study aimed to assess the effect of soy protein intake on the decrease in muscle and satellite cells by energy restriction in young female rats. Female Sprague Dawley rats (n = 32, 7 weeks old) were divided into four groups: ad libitum intake and casein diet (Cas); ad libitum intake and soy diet (Soy); energy restriction and casein diet (ER-Cas); and energy restriction and soy diet (ER-Soy). The experimental period was 10.5 weeks. The energy restriction groups were fed a 40% restricted energy diet. Energy restriction caused low body and abdominal fat weight. Conversely, soy protein had no effect on body weight. There was a significant interaction between energy restriction and soy protein on plantaris muscle weight. Soy protein induced high plantaris muscle mass under adequate energy intake, but low plantaris muscle mass under energy restriction. There was no significant effect of energy restriction or soy protein on serum estradiol; however, energy restriction caused low uterus weight. Soy protein induced low serum IGF-I levels under energy restriction alone. There was no significant interaction between energy restriction and soy protein on the plantaris muscle cross-sectional area. However, plantaris muscle in the Soy group was the largest and that in the ER-Soy group was the smallest. Further investigation of satellite cells is necessary because we could not assess it. In conclusion, our study suggests that soy protein induces high muscle mass under adequate energy intake, but low muscle mass under energy restriction. Soy Protein Research, Japan 23, 177-181, 2020.
Key words : muscle, soy protein, menstrual function, lean body
The Association between Intake of Soy and Isoflavones and Hyperuricemia and Renal Function in Japanese Male Workers: a Longitudinal Study
Mariko NAKAMOTO*1, Sarasa MORI1, Akimitsu OKOJI1, Emi SHUTO1, Akiko NAKAMOTO1, Akiko HATA2, Nanako AKI2, Yosuke SHIKAMA2,3, Yukiko BANDO2, Takako ICHIHARA4, Takako MINAGAWA5, Ayako TAMURA5, Yumi KUWAMURA6, Makoto FUNAKI2 and Tohru SAKAI1
1Department of Public Health and Applied Nutrition, Institute of Biomedical Sciences, the University of Tokushima Graduate School, Tokushima 770-8503
2Clinical Research Center for Diabetes, Tokushima University Hospital, Tokushima 770-8503
3National Center for Geriatrics and Gerontology, Research Institute, Department of Oral Disease Research, Aichi 474-8511
4Department of Nursing, Faculty of Medicine, Kagawa University, Kagawa 761-0793
5Department of Medical Treatment Recovery Care Nursing, Institute of Biomedical Sciences, the University of Tokushima Graduate School, Tokushima 770-8503
6Department of Women's Health Nursing, the University of Tokushima Graduate School of Biomedical Sciences, Tokushima 770-8503
ABSTRACT
Objectives: This study aimed to examine the association between the intake of soy products and isoflavones, and renal function and hyperuricemia in Japanese male workers. Methods: We analyzed 510 eligible Japanese male workers aged 21- 60 years. The intake of soy products and isoflavones was assessed using a self- administered questionnaire. Hyperuricemia was defined as > 7 mg/dL in serum uric acid and/or a medical history of hyperuricemia or gout. Multiple logistic regression analyses were performed to evaluate the associations between soy products and isoflavone intake, and the incidence of hyperuricemia. A generalized linear model was used to evaluate associations between the intake of soy products and isoflavones, and renal function. Results: Intake of fermented soy products, especially miso, showed significant inverse dose-response relationships with the incidence of hyperuricemia. The fourth quartile for fermented soy products or miso had an adjusted odds ratio (OR) of 0.37 (95% confidence interval (CI): 0.14- 0.94) or 0.28 (95% CI: 0.11-0.73) compared to the reference group (first quartile). These associations were also similar after adjustment for confounding factors, other dietary factors, and serum uric acid levels at baseline. However, no significant association between the intake of non-fermented soy products, total soy products, or total isoflavones and the incidence of hyperuricemia was observed. There was no significant association between the intake of soy products or isoflavones and renal function. Conclusions: Intake of fermented soy products, especially miso, might decrease the risk of hyperuricemia in Japanese male workers. Soy Protein Research, Japan 23, 182-191, 2020.
Key words : soy, isoflavones, hyperuricemia, Japanese workers, a longitudinal study
The Timing Effects of Soy Protein Isolate Intake on Mice Gut Microbiota
Hiroyuki SASAKI*
School of advanced science and engineering, Waseda University, Tokyo 162-8480
ABSTRACT
Soy protein isolate intake is known to cause changes in gut microbiota. Although there are some reports about the effect of soy protein isolate intake on gut microbiota, the effective timing of intake has not been investigated. In this study, we examined the effect of soy protein isolate intake timing on gut microbiota. Mice were fed twice a day, in the morning and evening. The mice were divided into three groups: 1. Mice that were fed only casein protein; 2. Mice that were fed soy protein isolate in the morning; and 3. Mice that were fed soy protein isolate in the evening. Mice were housed under each experimental condition for two weeks, and then sacrificed at three points, i.e., before morning feeding, four hours after morning feeding, and four hours after evening feeding). We measured cecal pH, and collected cecal contents and feces. Short-chain fatty acids (SCFA) were measured by gas chromatography from cecal contents, and 16S rRNA was extracted from feces and for analyzing microbiota composition using a next-generation sequencer. Cecal pH was lower and SCFA was higher in the morning soy protein isolate intake group than that in the evening intake group. In addition, microbiota composition was significantly changed in the morning soy protein isolate intake group than in the evening intake group. Therefore, soy protein isolate intake in the morning may have relatively stronger effects on the microbiota than that in the evening. Soy Protein Research, Japan 23, 192-198, 2020.
Key words : microbiota, chrono-nutrients, feeding timing, circadian