Immunomodulatory effect of protease hydrolysates from ovotransferrin

Strategies for mapping protein hydrolysate profiles and pharmacokinetics based on non-targeted proteomics combining skyline-aided quantitative techniques

Numerous works have been focused on the bioactivities of protein hydrolysates (PHs) and their application in food or drug formulations, but their composition and pharmacokinetics have never been addressed due to their complex constitutes, short half-life, extremely low concentrations and lack of authentic standards. The present study aims to develop systematic analytical strategy and technical platform with optimized sample preparation, separation and detection protocols for PHs. Lineal peptides (LPs), extraction of the spleen of healthy pigs or calves, were used as cases. First, solvents with polarity gradients were used to globally extract peptides of LP from biological matrix. Non-targeted proteomics based on a high-resolution MS system was used to establish a reliable qualitative analysis workflow for PHs. Based on the developed approach, 247 unique peptides were identified using NanoLC-Orbitrap-MS/MS, and then further verified on the MicroLC-Q-TOF/MS system. In the quantitative analysis workflow, Skyline software was used to predict and optimize the LC-MS/MS detection parameters of LPs followed by investigating the linearity and precision of the developed analytical assay. Note worthily, we innovatively prepared calibration curves by sequential dilution of LP solution to overcome the bottleneck of lacking authentic standards and complex PH composition. All the peptides exhibited good linearity and precision in biological matrix. The established qualitative and quantitative assays were successfully applied to study the distribution characteristics of LPs in mice, and would be conductive to systematically map the profile and pharmacokinetics of peptides in various PHs in vivo and in vitro.

Recent Advances in Applications of Bioactive Egg Compounds in Nonfood Sectors

Egg, a highly nutritious food, contains high-quality proteins, vitamins, and minerals. This food has been reported for its potential pharmacological properties, including antibacterial, anti-cancer, anti-inflammatory, angiotensin-converting enzyme (ACE) inhibition, immunomodulatory effects, and use in tissue engineering applications. The significance of eggs and their components in disease prevention and treatment is worth more attention. Eggs not only have been known as a "functional food" to combat diseases and facilitate the promotion of optimal health, but also have numerous industrial applications. The current review focuses on different perceptions and non-food applications of eggs, including cosmetics. The versatility of eggs from an industrial perspective makes them a potential candidate for further exploration of several novel components.

Ovotransferrin exerts bidirectional immunomodulatory activities via TLR4-mediated signal transduction pathways in RAW264.7 cells

The immune regulation function of ovotransferrin (OVT) explored using the RAW264.7 was induced by lipopolysaccharide (LPS) as vitro model in this study. The results showed that RAW264.7 cultured with OVT (200 μg/ml) alone not only enhanced the phagocytic activity and the production and expression of inflammatory factors, but also expression of toll-like receptor 4 (TLR4) gene was significantly promoted by OVT. OVT (50 μg/ml) significantly inhibited the secretion and expression of inflammatory factors in LPS-stimulated RAW264.7, but CD14 and TLR4 genes expressions were no obvious effects. Inflammatory cytokines and NO secreted by OVT-induced macrophages pretreated with inhibitors of TLR4 were down-regulated. We further verified the effects of OVT on inflammatory signaling pathway-related proteins through immunofluorescence and western blotting, MyD88, TLR4 and the phosphorylation of IκBα and p65 were significantly promoted by OVT, but there was no significant effects on the phosphorylation of IRF3. OVT promoted the phosphorylation of ERK and p38 in RAW264.7 and inhibited the phosphorylated expression of MAPK in LPS-mediated inflammation. These results indicated that OVT had the bidirectional immunoregulatory function through TLR4-mediated NF-κB/MAPK signaling pathway, that is, anti-inflammatory effect of low concentration and immune-enhancing activity of high concentration were showed. That provides a theoretical utilization for the development and utilization of OVT.

Enzymatic Hydrolysis of Ovotransferrin and the Functional Properties of Its Hydrolysates

Bioactive peptides have great potentials as nutraceutical and pharmaceutical agents that can improve human health. The objectives of this research were to produce functional peptides from ovotransferrin, a major egg white protein, using single enzyme treatments, and to analyze the properties of the hydrolysates produced. Lyophilized ovotransferrin was dissolved in distilled water at 20 mg/mL, treated with protease, elastase, papain, trypsin, or α-chymotrypsin at 1% (w/v) level of substrate, and incubated for 0–24 h at the optimal temperature of each enzyme (protease 55°C, papain 37°C, elastase 25°C, trypsin 37°C, α-chymotrypsin 37°C). The hydrolysates were tested for antioxidant, metal-chelating, and antimicrobial activities. Protease, papain, trypsin, and α-chymotrypsin hydrolyzed ovotransferrin relatively well after 3 h of incubation, but it took 24 h with elastase to reach a similar degree of hydrolysis. The hydrolysates obtained after 3 h of incubation with protease, papain, trypsin, α-chymotrypsin, and after 24 h with elastase were selected as the best products to analyze their functional properties. None of the hydrolysates exhibited antioxidant properties in the oil emulsion nor antimicrobial property at 20 mg/mL concentration. However, ovotransferrin with α-chymotrypsin and with elastase had higher Fe³⁺-chelating activities (1.06±0.88%, 1.25±0.24%) than the native ovotransferrin (0.46±0.60%). Overall, the results indicated that the single-enzyme treatments of ovotransferrin were not effective to produce peptides with antioxidant, antimicrobial, or Fe³⁺-chelating activity. Further research on the effects of enzyme combinations may be needed.

Functional properties of ovotransferrin from chicken egg white and its derived peptides: a review

With emerging trends in the food and pharmaceutical industries, potential applications of egg-derived bioactive compounds were recognized. Ovotransferrin is a major egg white functional protein responsible for multiple bioactivities. The objectives of this review are to provide scientific evidence of the functional properties of chicken ovotransferrin and its derived peptides and to identify future research approaches and applications. Various easy, economical, and non-toxic methods have been reported to produce ovotransferrin with high yield and purity, and chemical and enzymatic approaches have been employed to release bioactive peptides. The native ovotransferrin is known to have antimicrobial, antioxidant, anticancer, and immunomodulatory activities. The peptides produced from ovotransferrin also are reported to have antioxidant, antimicrobial, antihypertensive, and anticancer properties. However, little or no application of these compounds in the food and pharmaceutical areas is available yet. Therefore, the practical application of OTF in nutraceutical and pharmaceutical areas are among the emerging areas of research.

Molecular action mechanism of anti-inflammatory hydrolysates obtained from brewers' spent grain

BACKGROUND

Brewers' spent grain (BSG) is a relevant, protein-rich by-product of the brewing process. Protein hydrolysates from different sources exert immune-regulatory actions activating toll-like receptors (TLRs), nuclear factor kappa B (NFκB), and mitogen-activated protein kinases (MAPKs). Effects of gastrointestinal digestion have been poorly studied. Here, we studied the immune-regulatory effect of BSG hydrolysates, and their in-vitro-digested products, on rat splenocytes, macrophages, and T lymphocytes RESULTS: In primary cultures of rat spleen cells, BSG hydrolysates induced interleukin 10 and tumor necrosis factor production in basal conditions. Under stimulation with lipopolysaccharide or concanavalin A, hydrolysates further induced interleukin 10 production. Tumor necrosis factor and interferon-γ were inhibited in lipopolysaccharide- and concanavalin-A-stimulated cells respectively. In vitro gastrointestinal digestion attenuated the observed effects. Splenic macrophages and T lymphocytes behaved in a similar fashion. In spleen cells from TLR2^-/- and TLR4^-/- mice, immune-regulatory effects were greatly reduced or abrogated. The study of signal transduction pathways indicated a major involvement of NFκB, and the contribution of MAPKs p38, c-Jun N-terminal kinase, and extracellular signal-regulated kinases 1 and 2.

CONCLUSION

BSG hydrolysates, like those obtained from other food sources, regulate the immune response, involving TLR2 and TLR4 and the activation of NFκB and MAPKs, an effect partly maintained after in vitro gastrointestinal digestion. Our data support the hypothesis of a shared, rather unspecific, mechanism of action of protein hydrolysates. © 2020 Society of Chemical Industry.

Multi-Omics Analysis of the Effects of Egg Ovotransferrin on the Gut Environment in Mice: Mucosal Gene Expression, Microbiota Composition, and Intestinal Structural Homeostasis

SCOPE

Egg ovotransferrin (OVT) is considered a functional food ingredient for its various bioactivities. The objective of this work is to explore the potential biological activity of OVT on the gut health.

METHODS AND RESULTS

Both young (3 week old) and adult (8 week old) mouse models are utilized in this research. Each group receives a standard diet containing either OVT (experimental group) or distilled water (control group) for a 14 day period. Transcriptome and 16S rDNA sequencing analyses are applied to characterize the gene expression in colonic epithelial cells and gut microbiota composition. In the young groups, OVT suppresses the genes correlated with lipid metabolism and signal transduction. The regulated genes in the adult groups encompass various biological processes, including lipid metabolism, signal transduction, endocrine system, and others. OVT increases the proportion of some beneficial bacteria significantly, especially Akkermansia, and inhibits some harmful bacteria. Furthermore, OVT affects mucosal morphology positively via increasing the crypt depth. OVT also increases the expression of tight junction protein occludin by 3.0- and 5.2-folds in young and adult groups, respectively.

CONCLUSION

OVT exhibits some beneficial effects on the gut environment. These positive findings provide new insight into the understanding of OVT as an excellent functional ingredient.

Ovotransferrin ameliorates the dysbiosis of immunomodulatory function and intestinal microbiota induced by cyclophosphamide

In this study, the regulative effects of ovotransferrin (OVT) on immunomodulatory function and intestinal microbial dysbiosis in a mouse model injected with cyclophosphamide (CP) were investigated. The immunomodulatory effect of OVT was determined by enzyme-linked immune sorbent assay (ELISA). Gut microbial composition was determined by high-throughput sequencing of the V3-V4 region of the 16S rDNA gene. The changes in the relative abundance of the dominant microbiota were analyzed at different taxonomic levels. The results showed that OVT alleviated the immune dysfunction caused by CP. OVT improved the spleen and thymus indices and enhanced the secretion of tumor necrosis factor alpha (TNF-α), interleukin-10 (IL-10), and immunoglobulin A (IgA). In addition, OVT increased the indexes of Shannon and Simpson, suggesting the enhancement of the diversity and richness of intestinal microflora. The relative abundance of Lachnospiraceae_NK4A136_group was also increased. However, the relative abundance of Helicobacter and Desulfovibrio was significantly decreased. These results indicated that OVT, a food-derived functional component, has effects on immune regulation in the organism and ameliorates the gut microbiota disorders induced by CP, which provides a potential therapeutic utilization of avian eggs by targeting the gut microbiome.

The Golden Egg: Nutritional Value, Bioactivities, and Emerging Benefits for Human Health

Egg is an encapsulated source of macro and micronutrients that meet all requirements to support embryonic development until hatching. The perfect balance and diversity in its nutrients along with its high digestibility and its affordable price has put the egg in the spotlight as a basic food for humans. However, egg still has to face many years of nutritionist recommendations aiming at restricting egg consumption to limit cardiovascular diseases incidence. Most experimental, clinical, and epidemiologic studies concluded that there was no evidence of a correlation between dietary cholesterol brought by eggs and an increase in plasma total-cholesterol. Egg remains a food product of high nutritional quality for adults including elderly people and children and is extensively consumed worldwide. In parallel, there is compelling evidence that egg also contains many and still-unexplored bioactive compounds, which may be of high interest in preventing/curing diseases. This review will give an overview of (1) the main nutritional characteristics of chicken egg, (2) emerging data related to egg bioactive compounds, and (3) some factors affecting egg composition including a comparison of nutritional value between eggs from various domestic species.

Ovotransferrin enhances intestinal immune response in cyclophosphamide-induced immunosuppressed mice

Ovotransferrin (OVT), a glycoprotein from avian egg, which has a variety of biological activities and immunomodulatory effects. The purpose of this research was to demonstrate the effect of OVT on intestinal immunomodulatory function which used a mouse model of cyclophosphamide (CP) induced intestinal immunosuppression and injury by intraperitoneal injection of 80 mg/kg. Effects of OVT on intestinal immunomodulatory function in CP-induced immunosuppression mice were detected by flow cytometry, real-time quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, and western blot. Results showed that OVT effectively increased the major histocompatibility complex class II (MHC-II) and cluster of differentiation 83 (CD83) levels to enhance intestinal dendritic cells (DCs) maturation and promoted the expression of cytokines and gene of tumor necrosis factor alpha (TNF-α), interferon-γ (IFN-γ), interleukin-4 (IL-4) and interleukin-10 (IL-10). Furthermore, the imbalance ratio of the Th1 and Th2 in the intestine was regulated to produce an immune response and the expression of immunoglobulin A (IgA) and secretory immunoglobulin A (sIgA) were increased to promote humoral immunity by OVT-treated. Meanwhile, cyclophosphamide treatment induces activation of p38 MAPK, c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) to causes intestinal damage and blockage of p38 MAPK, JNK and ERK activation contributed to the effect of OVT on the repair of intestinal damage. These results indicated that OVT may have immunomodulatory function and could be potential functional factor to regulate body intestinal immunity.