Condensation of Soy Protein Peptides Contributes to Sequester Bile Acids and Mitigate LPS-Induced Inflammation.

Soy protein is widely known to have serum triglyceride (TG) and cholesterol-lowering effects associated with a reduced risk of cardiovascular disease. Recent studies highlighted that the extension region (ER) domain of soy 7S globulin (ß-conglycinin) is a key component responsible for the serum TG-lowering effect via modulation of bile acid (BA) homeostasis. Here, we studied the sequestration of BAs by ER peptides during intestinal digestion in vitro and assessed the anti-inflammatory effects of ER peptides using Caco-2/HT29-MTX/RAW264.7 triple-cell cocultures as an intestine cell model. Results show that ER peptides, which share characteristics of intrinsically disordered regions (IDRs), are capable of forming peptide condensates and exhibit the capability to sequester BA-containing colloidal structures during intestinal digestion in vitro. Moreover, BAs enhance the penetration of peptide condensates within the mucus layer, enabling ER peptides to mitigate lipopolysaccharide (LPS)-induced gut inflammation. These results provide a possible explanation for the molecular mechanisms underlying the modulation of BA homeostasis by soybean proteins.

Extension Region Domain of Soybean 7S Globulin Contributes to Serum Triglyceride-Lowering Effect via Modulation of Bile Acids Homeostasis.

SCOPE: Soybean 7S globulin (ß-conglycinin), a major soybean storage protein, has been demonstrated to exert remarkable triglyceride (TG) and cholesterol-lowering effects, yet the underlying mechanism remains controversial. METHODS AND RESULTS: A comparative investigation is performed to assess the contribution of different structural domains of soybean 7S globulin, including core region (CR) and extension region (ER) domains, to biological effects of soybean 7S globulin using a high-fat diet rat model. The results show that ER domain mainly contributes to the serum TG-lowering effect of soybean 7S globulin, but not for CR domain. Metabolomics analysis reveals that oral administration of ER peptides obviously influences the metabolic profiling of serum bile acids (BAs), as well as significantly increased the fecal excretion of total BAs. Meanwhile, ER peptides supplementation reshapes the composition of gut microbiota and impacts the gut microbiota-dependent biotransformation of BAs which indicate by a significantly increased secondary BAs concentration in fecal samples. These results highlight that TG-lowering effects of ER peptides mainly stem from their modulation of BAs homeostasis. CONCLUSION: Oral administration of ER peptides can effectively lower serum TG level by regulating BAs metabolism. ER peptides have potential to be used as a candidate pharmaceutical for the intervention of dyslipidemia.

Bile Acid Profile Influences Digestion Resistance and Antigenicity of Soybean 7S Protein.

Soybean 7S storage protein (ß-conglycinin) is the most important allergen, exhibits resistance in gastrointestinal (GI) digestion, and causes allergies in humans and animals. A previous study has demonstrated that 7S proteins contained innate amyloid aggregates, but the fate of these specific protein aggregates in intestinal digestion and correlation to allergenicity are unclear. In this study, via a modified INFOGEST static in vitro digestion and IgE binding test, we illustrate that the survived amyloid aggregates of soybean 7S protein in GI digestion might be dominant IgE epitopes of soybean protein in humans. The impact of conjugated primary bile acid salt (BS) profile on digestion resistance and immunogenicity of soybean protein is assessed, regarding the binding affinity of BS to protein aggregates with consideration of the BS composition and the physiologically relevant colloidal structure. The results show that chenodeoxycholate-containing colloidal structures exhibit high affinity and unfolding capacity to protein amyloid aggregates, promoting proteolysis by pancreatic enzymes and thus mitigating the antigenicity of soybean protein. This study presents a novel understanding of bile acid profile and colloidal structure influence on the digestibility and antigenicity of dietary proteins. It should be helpful to design in vitro digestion protocol and accurately replicate physiologically relevant digestion conditions.

Interaction of Pyrogallol-Containing Polyphenols with Mucin Reinforces Intestinal Mucus Barrier Properties.

High consumption of polyphenol-rich green tea, coffee, fruits, and vegetables is associated with a low risk of human chronic diseases. Recent studies highlight the relevance of polyphenol-mediated gut microbiota modulation and its impact on mucus barrier. Herein, we study the direct interaction of epicatechin (EC), epigallocatechin gallate (EGCG), and tannic acid (TA) with intestinal mucin by isothermal titration calorimetry and multiple particle tracking and the impact on mucus barrier using ex vivo mucus and Caco-2/HT29-MTX cocultures. Results show that pyrogallol-containing polyphenols EGCG and TA exhibit strong binding to intestinal mucin and reinforce mucus barrier, whereas EC does not. ECGG and TA also mitigate gliadin-mediated cytotoxicity and inflammation. The chemical binding of EGCG and TA to the nucleophilic thiol groups of mucins shows their roles as cross-linkers of mucin networks. These results bring a novel understanding of the health benefits of polyphenols and provide support for the consumption of pyrogallol-containing beverages like green tea as a potential dietary therapy for gluten-related disorders.

Digestion Resistance of Soybean 7S Protein and Its Implications for Reinforcing the Gastric Mucus Barrier.

Previous studies have found that soybean protein, especially soybean 7S protein (ß-conglycinin), exhibits digestion resistance, but the mechanism of digestion resistance and its implications for human health are still unclear. Here, we show that the extracted soybean 7S protein contains both oligomer globulins and amyloid aggregates, while the gastric digested soybean 7S protein only contains amyloid aggregates and thus exhibits digestion resistance. An animal experiment shows that un-digestible soybean 7S protein effectively prevents aspirin-induced acute gastric mucosa damage. The impacts of un-digestible soybean 7S protein on gastric mucus barrier properties are investigated using quartz crystal microbalance with dissipation (QCM-D), Langmuir monolayer, and multiple particle tracking (MPT). Results show that these un-digestible protein aggregates can penetrate into gastric mucus, increase the viscosity and compactness of the mucin layer, and reinforce the gastric mucus barrier properties. The findings are helpful to understand that high consumption of non-fermented soybean foods is associated with a decreased risk of gastric cancer.

Undigestible Gliadin Peptide Nanoparticles Penetrate Mucus and Reduce Mucus Production Driven by Intestinal Epithelial Cell Damage.

Wheat protein is the most consumed plant protein in our diet, and there is an increased prevalence of wheat/gluten intolerance and adherence to a gluten-free diet in many countries. Despite the known immunodominant effect of undigested gliadin peptides responsible for gluten-related intolerance, it remains unclear if and how gliadin peptides self-assemble into ordered nanostructures during gastrointestinal digestion, as well as their biological impact on the mucus barrier function. In this study, we purified undigestible gliadin peptide nanoparticles (UGPNs) by ultracentrifugation and characterized their structural and physiochemical properties. The results demonstrate that the UGPNs are self-assembled nanostructures generated by cationic amino acids (Lys and Arg)-capped surfactant-like peptides (SLPs), mainly derived from γ-gliadin and α-gliadin. SLPs trigger the concentration-dependent self-assembly driven by ß-sheet conformational transitions above their critical aggregation concentration (cac, ∼0.1 mg/mL). UGPNs can easily penetrate the mucus layer in Caco-2/HT29-MTX cocultures with a high Papp value (∼5.7 × 10-6 cm/s) and reduce the production and thickness of the mucus layer driven by intestinal epithelial cell damage. Isothermal titration calorimetry and Langmuir monolayer studies indicate that the self-assembled state of UGPNs significantly affects their binding to DPPC/DOPE lipid membrane models. These results highlight the relevance of the self-assembly of gliadin peptides as a trigger of mucosal inflammation-related wheat/gluten intolerance.

Salt reduction in bread via enrichment of dietary fiber containing sodium and calcium.

The high intake of sodium and low intake of dietary fiber are two major dietary risk factors for preventable deaths worldwide, highlighting the need and implementations for developing health foods with low-salt/high-dietary fibers. Bread as a staple food contributes about 25% to the daily intake of sodium in many countries, and salt reduction in bread still remains a great technical challenge. In this study, we developed a simple method to reformulate the white bread in terms of reducing salt contents via dietary fiber fortification, while maintaining the taste and texture qualities. Low molecular weight water-extractable arabinoxylans (LMW-WEAX) as a soluble dietary fiber was first hydrated in salt water before dough mixing, leading to an inhomogeneous spatial distribution of sodium in bread and accelerating the release of sodium ions from crumbs, allowing 20% salt reduction in bread without impacting the salt perception. Data from the moisture content, crumb structure, water distribution, dough rheology and bread texture properties suggest that the pre-hydrated incorporation of LMW-WEAX mitigates the detrimental effect of dietary fiber on the dough and bread quality. The modulation of Ca2+ on the permeability of Na+ through the mucus layer and implication in salt enhancement of the bread were investigated. Results show that the pre-hydrated incorporation of WEAX containing Na+ and Ca2+ (1.0%) makes it possible to reduce 30% salt content in breads, which have implications in the large-scale production of low-salt/high-dietary fiber bread.

Glycated fish protein supplementation modulated gut microbiota composition and reduced inflammation but increased accumulation of advanced glycation end products in high-fat diet fed rats.

This study first investigates how the intake level of glycated fish protein (GP), enriched with Amadori products, affects gut health by modifying the fermentation of gut microbiota and accumulation of advanced glycation end products (AGEs) in rats fed a high-fat diet. Hyperlipidemic rats were fed a fish protein (FP) control diet, 6% low-level GP (L-GP) diet, and 12% high-level GP (H-GP) diet for four weeks. Compared to the FP diet, the GP diet greatly changed the pattern of protein fermentation and reduced inflammation markers and blood lipids, but increased the AGE plasma accumulation and fecal excretion. Furthermore, the GP supplementation significantly decreased Ruminiclostridium_6 and Desulfovibrio (p < 0.05), and the L-GP diet showed more effects on the increase of butyrate-producing Ruminococcus_1 and Roseburia, while the H-GP diet considerably decreased Helicobacter and Lachnospiraceae_NK4A136_group. Correlation-type principal-component analysis (PCA) clearly indicated that these biological effects of intake of GP were related to the modulation of gut microbiota composition and fermentation metabolite profiles. Overall, the low intake level of glycated fish protein may have a more beneficial effect on gut health.

Modulation of Gut Microbiota by Soybean 7S Globulin Peptide That Involved Lipopolysaccharide-Peptide Interaction.

Soybean protein exhibits nutritional significance for the control of metabolic syndrome, and evidence suggests that gut microbiota are implicated in the control of metabolic disorders. This study aimed to investigate the modulation of pepsin-released peptides of soybean 7S globulin on gut microbiota and possible association between changes of gut microbiota composition and lipopolysaccharide (LPS)-peptide interaction. In vitro fermentation experiments showed that the extension region (ER) fragments of soybean 7S globulin selectively suppressed proinflammatory Gram-negative bacteria. ER peptides also promoted the highest production of short-chain fatty acids (SCFAs), which were associated with increase of the relative abundance of Lachnospiraceae and Lactobacillaceae. Isothermal titration calorimetry (ITC) and Langmuir monolayer studies demonstrated that ER peptides exhibited high affinity to LPS in the presence of Ca2+ and developed into ß-sheet-rich aggregate structures, thus weakening the stability of LPS monolayers. This finding supplies a possible explanation for improvement of the effects of soybean 7S globulin on metabolic disease.

A Software Defined Radio Evaluation Platform for WBAN Systems.

In recent years, the Wireless Body Area Network (WBAN) concept has attracted significant academic and industrial attention. WBAN specifies a network dedicated to collecting personal biomedical data from advanced sensors that are then used for health and lifestyle purposes. In 2012, the 802.15.6 WBAN standard was released by the Institute of Electrical and Electronics Engineers (IEEE), which regulates and specifies the configurations of WBAN. Compared to the prevailing wireless communication technologies such as Bluetooth and ZigBee, the WBAN standard has the advantages of ultra-low power consumption, high reliability, and high-security protection while transmitting sensitive personal data. Based on the standard specification, several implementations have been published. However, in terms of evaluation, different designs were implemented in proprietary evaluation environments, which may lead to unfair comparison. In this paper, a Software-Defined Radio (SDR) evaluation platform for WBAN systems is proposed to evaluate the RF channel specified in the IEEE 802.15.6 standard. A narrowband communication protocol demonstration with a security scheme in WBAN has been performed to successfully validate the design in the proposed evaluation platform.

Glycation of fish protein impacts its fermentation metabolites and gut microbiota during in vitro human colonic fermentation.

The aim of this study was to investigate the fermentation properties of fish protein (FP) glycated with glucose at two different heating time (24 h and 48 h, 50 °C, GFP24 and GFP48), using an in vitro batch fermentation model of human distal colon. The heated fish protein in absent of glucose was also as controls. The lower glycation extent of fish protein, with a lower browning intensity and bound sugar, enhanced the production of acetate and propionate. The formation of indole and ammonia was inhibited by the glycation of fish protein, but less affected by its glycation extent. Compared to FP, the glycation of fish protein significantly increased (p < .05) the relative abundance of genera Lactococcus for GFP24 (47%) and GFP48 (71%), whereas decreased dominant genera Bacteroides for GFP24 (32%) and GFP48 (23%). Compared to GFP24, GFP48 indicated significantly higher relative abundance of Holdemania, Streptococcus, Enterococcus and Lactobacillus, and lower amounts of Parabacteroides (p < .05). In the meantime, the heated treatments in the absent of glucose resulted in the increase of some genera Dialister, Arobacter, Clostridium_sensu_stricto_1, Phascolarctobacterium and Veillonella, and also ammonia production. Furthermore, the correlation analysis confirmed that the glycation of fish protein for the decrease of ammonia and indole production was associated with the changes of some proteolytic bacteria genera, including Bacteroides, Dialister and Parabacteroides. Thus, the glycated fish protein rich in Amadori products greatly change the profiles of fermentation metabolite and gut microbiota, and these changes can have a potential impact on host health.

Modifications in gut microbiota and fermentation metabolites in the hindgut of rats after the consumption of galactooligosaccharide glycated with a fish peptide.

The aim of this research was to investigate the impact of a diet containing galactooligosaccharide (GOS)-fish peptide (FP) conjugates prepared via Maillard reaction on the colonic fermentation properties and the composition of gut microbiota in Sprague-Dawley rats. The rats were fed the GOS diet, FP diet, GOS and FP mixture (GOS/FP) diet, GOS glycated with FP (80 °C for 120 min, G-GOS/FP) diet, or control (CK) diet for three weeks. Compared to the GOS/FP diet, the G-GOS/FP diet greatly changed the pattern of SCFA production in the hindgut of rats, by increasing the total SCFA (44%), butyrate (55%) and propionate (1.23-fold) levels in the proximal colon, and the butyrate levels (74%) in the distal colon, and decreased the production of ammonia in feces (P < 0.05). The G-GOS/FP altered the colonic microbiota by increasing (P < 0.05) the relative abundance of Anaerovibrio (7.43-fold) and Prevotella-9 (2.47-fold), and by decreasing (P < 0.05) the relative abundance of Alloprevotella (0.57-fold) and Holdemanella (0.64-fold), and showed a similar relative abundance of Bifidobacterium, when compared with GOS/FP. The GOS/FP diet increased the number of Lactobacillus and the intensity of fermentation in the cecum, but the G-GOS/FP diet and GOS diet did not have these effects, showing that the glycation clearly altered the fermentability of the fish peptide. It is concluded that the glycation-induced modification of GOS by mild thermal treatments showed its fermentation persistence in the colon of the host, and improved some prebiotic activities of GOS. These results may provide new strategies for oligosaccharides in combination with peptides to modulate the intestinal environment to promote human health.

Effect of different cooking conditions on the profiles of Maillard reaction products and nutrient composition of hairtail (Thichiurus lepturus) fillets.

Much attention has been given to investigate the formation of Maillard reaction products in thermal processing food due to potential health risks. This study aimed to the profiles of Maillard reaction products (MRPs) and changes of nutrient composition in hairtail (Thichiurus lepturus) fillets prepared by three cooking method: boiling, baking and frying. The Nε-carboxymethyllysine (CML) level ranged from non-detectable to 4.24mg/100g protein and furosine ranged from 4.25 to 20.95mg/100g protein. The levels of CML and furosine in boiled hairtail fillets were much lower than baked and fried ones. The formation of CML was only affected by the cooking method. The changes of the lipid and moisture content, and thiobarbituric acid-reactive substances (TBARS) content in cooked hairtail fillet had different effects on the formation of different stages of Maillard reaction. Furosine level significantly correlated with absorbance in 420nm (r=0.74, p<0.05) and 280nm (r=0.73, p<0.05) and fluorescence Intensity (FI) (r=0.65, p<0.05), but did not correlate with CML. The CML level linearly correlated with the moisture (r=0.79, p<0.01) and lipid content (r=0.73, p<0.05), and the formation of TBARS value (r=0.92, p<0.01), but did not correlate with the FI. Overall, the findings may help to better control the cooking conditions of hairtail meat based on the profiles of MRPs.

Chemical characterization of the glycated myofibrillar proteins from grass carp (Ctenopharyngodon idella) and their impacts on the human gut microbiota in vitro fermentation.

In this study, the chemical characterization of glycoconjugates of myofibrillar proteins from grass carp conjugated with glucose via Maillard reaction for up to 24 h of dry-heating was investigated, and their impacts on the microbial community in vitro human fecal fermentation were firstly evaluated by high-throughput sequencing technologies. The glycation greatly increased the furosine levels in glycoconjugates, which reached the maximum level (2.87 ± 0.08 mg per 100 mg protein) for 9 h of heating, and resulted in the structural changes of myofibrillar proteins based on the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Fourier transform infrared spectroscopy (FTIR) analysis. Size-exclusion chromatography (SEC) analysis of digested glycoconjugates showed that the gradually increased proportion between 1423 Da (bacitracin)-12 588 Da (cytochrome C) with the prolongation of heating time, suggesting that glycation decreased the digestibility of myofibrillar proteins. Furthermore, glycoconjugates with a higher level of Amadori products and lower browning intensity enhanced fecal microbiota diversity based on species-level phylotypes. The production of butyrate in fermentation of digested glycoconjugates was affected by the glycation extent of myofibrillar proteins, and significantly and positively correlated with Mitsuokella, Lachnospiraceae_UCG-004, Sutterella, Salinimicrobium, Fodinibius and Nitriliruptor (p < 0.05), but negatively correlated with Enterococcus, Dorea (p < 0.05), Escherichia-Shigella and Phascolarctobacterium (p < 0.01). Our findings demonstrated that the glycation of myofibrillar proteins could have potentially positive effects to intestinal health.

Antioxidant balance and accumulation of advanced glycation end products after the consumption of standard diets including Maillard reaction products from silver carp peptides.

The aim of this research was to investigate the accumulation and excretion of AGEs including fluorescent compounds and N-ε-carboxymethyllysine (CML) in streptozotocin-induced diabetes C57BL/6J mice fed on a diet containing Maillard reaction products (MRPs) from a silver carp peptide-glucose model system at different heating temperatures for the first time, and analyze the relationship between their in vitro antioxidant activity based on DPPH and ORAC assays and in vivo oxidative stress. The in vitro antioxidant activity of MRPs positively correlated with their AGEs level and molecular weight distribution. However, the opposite results were found by malondialdehyde (MDA) and super oxide dismutase (SOD) assays that MRPs from a higher heating temperature could aggravate the oxidative stress of diabetic mice. CML accumulation in serum was aggravated, but changes of MRPs in diets hardly affected CML accumulation in the kidney and liver. Therefore, the high AGEs levels from a diet containing peptide MRPs have negative effects on the oxidative stress of diabetic mice.