Purification, identification and functional characterization of an immunomodulatory protein from Pleurotus eryngii

Dietary intake of whole king oyster mushroom (Pleurotus eryngii) attenuated obesity via ameliorating lipid metabolism and alleviating gut microbiota dysbiosis

There is a growing interest in employing whole food-based strategies to prevent chronic diseases, owing to the potential synergistic interactions among various bioactive components found within whole foods. The current research aimed to determine inhibitory effects of the whole edible mushroom Pleurotus eryngii (WPE) on high-fat diet (HFD)-induced obesity in mice. Our results showed that dietary intake of WPE significantly inhibited the abnormal gain of body weight and adipose tissue weight, improved glucose tolerance, and ameliorated the serum biochemical parameters in HFD-fed mice. The histological analysis illustrated that the severity of non-alcoholic fatty liver induced by HFD was significantly reduced by WPE. Oral intake of WPE profoundly modulated the mRNA levels of hepatic genes involved in lipid metabolism and also increased the level of short-chain fatty acids in the mouse cecum. Moreover, WPE alleviated the HFD-induced gut microbiota dysbiosis, increasing the abundance of beneficial bacteria (Akkermansia, Lactobacillus, Bifidobacterium, and Sutteralla), and decreasing the harmful ones (rc4-4, Dorea, Coprococcus, Oscillospira, and Ruminococcus). These findings presented new evidence supporting that WPE could be used as a whole food-based strategy to protect against obesity and obesity-driven health problems.

Flammulina velutipes polysaccharides regulate lipid metabolism disorders in HFD-fed mice via bile acids metabolism

Our recent study demonstrated that the dynamic changes of gut microbiota mediated by Flammulina velutipes polysaccharide (FVP) could effectively regulate the lipid metabolism in high fat diet-fed (HFD-fed) obese mice model. In this paper, further research was carried out by examining the bile acid (BAs) profiles, as well as the BAs metabolic pathways changes in obese mice. Furthermore, the regulatory effect of BAs on lipid metabolism was verified by 3 T3-L1 preadipocyte differentiation model. The FVP administration resulted in lower BAs content in plasma of obese mice. From the qRT-PCR analysis, FVP could relieve cholestasis in obese mice through altering the BAs metabolic pathways, changing the related genes expressions in mice liver and ileum. The cholic acid (CA), chenodeoxycholic acid (CDCA), hyodeoxycholic acid (HDCA) and ursodeoxycholic acid (UDCA) were selected in cell experiment which all reduced the intracellular triglyceride content and increased the expression of AMPKα1 in 3 T3-L1 adipocytes. Furthermore, CA and CDCA were found increased the expression of PPARα. In combination with our previous research, we further confirmed in this paper that the changes of BAs metabolism caused by FVP showed a positive effect on lipid metabolism, both in obese mice and 3 T3-L1 adipocytes.

Impact of pH on the Formation and Properties of Whey Protein Coronas around TiO2 Nanoparticles

In aqueous media, titanium dioxide (TiO₂) nanoparticles can interact with proteins in their environment and form a protein corona. The pH of the aqueous media affects the structure and properties of the protein corona, and currently there is a lack of understanding of the effects of pH on the characteristics of protein coronas. In this study, we examined the impact of pH (2-11) on the structural and physicochemical properties of whey protein coronas formed around TiO₂ nanoparticles. The pH of the solution influenced the structure of whey protein molecules, especially around their isoelectric point. Thermogravimetric and quartz crystal microbalance analyses showed that the adsorption capacity of the whey proteins was the largest at their isoelectric points and the lowest under highly acidic or alkaline conditions. The majority of the proteins were tightly bound to the nanoparticle surfaces, forming a hard corona. The influence of solution pH on protein corona properties was mainly attributed to its impact on the electrostatic forces in the system, which impacted the protein conformation and interactions. This study provides useful insights into the influence of pH on the formation and properties of protein coronas around inorganic nanoparticles, which may be important for understanding the gastrointestinal and environmental fates.

Antioxidant Activity of Polysaccharides from the Edible Mushroom Pleurotus eryngii

In this study the antioxidant and neuroprotective activity of an enriched polysaccharide fraction (EPF) obtained from the fruiting body of cultivated P. eryngii was evaluated. Proximate composition (moisture, proteins, fat, carbohydrates and ash) was determined using the AOAC procedures. The EPF was extracted by using, in sequence, hot water and alkaline extractions followed by deproteinization and precipitation with cold ethanol. Total α- and β-glucans were quantified using the Megazyme International Kit. The results showed that this procedure allows a high yield of polysaccharides with a higher content of (1-3; 1-6)-β-D-glucans. The antioxidant activity of EPF was detected from the total reducing power, DPPH, superoxide, hydroxyl and nitric oxide radical scavenging activities. The EPF was found to scavenge DPPH, superoxide, hydroxyl and nitric oxide radicals with a IC50 values of 0.52 ± 0.02, 1.15 ± 0.09, 0.89 ± 0.04 and 2.83 ± 0.16 mg/mL, respectively. As assessed by the MTT assay, the EPF was biocompatible for DI-TNC1 cells in the range of 0.006-1 mg/mL and, at concentrations ranging from 0.05 to 0.2 mg/mL, significantly counteracted H₂O₂-induced reactive oxygen species production. This study demonstrated that polysaccharides extracted from P. eryngii might be used as functional food to potentiate the antioxidant defenses and to reduce oxidative stress.

Dietary Turmeric Consumption Alleviates Ulcerative Colitis via Restoring Tryptophan Metabolism and Alleviating Gut Microbiota Dysbiosis in Mice

This study was designed to first verify the protective capacity of turmeric powder (TP) as a traditional cooking spice against dextran sulfate sodium (DSS)-induced intestinal inflammation and intestine microbiota imbalance. The DSS-induced mice were fed a standard rodent chow supplemented with or without TP (8%) for 37 days. The results indicated that the pathological phenotype, gut barrier disruption, and colon inflammation of DSS-induced mice were significantly improved through supplementation of TP. In addition, 16S rRNA-based microbiota or targeted metabolomics analysis indicated that TP ameliorated intestinal microbiota dysbiosis caused by DSS and particularly enhanced the abundances of probiotics correlated with tryptophan metabolism, such as Lactobacillus and Bifidobacterium, where the cecal tryptophan was metabolized to indole-3-propionic acid and indole-3-acetic acid. Consumption of TP markedly enhanced the expression levels of colonic aromatic hydrocarbon receptors and further increased the expressions of intestinal tight junction proteins and interleukin-22 in the colitis mice. Collectively, these findings manifest the protective actions of dietary TP consumption against ulcerative colitis via restoring the intestinal microbiota disorders, promoting microbial metabolism, and improving intestinal barrier damage.

Genoprotective activity of the Pleurotus eryngii mushrooms following their in vitro and in vivo fermentation by fecal microbiota

Pleurotus eryngii mushrooms are commercially cultivated and widely consumed due to their organoleptic properties, and the low caloric and high nutritional value. In addition, they contain various biologically active and health-promoting compounds; very recently, their genoprotective effect in Caco-2 cells after their fermentation by the human fecal microbiota was also documented. In the current study, the effect of P. eryngii pre- and post-fermentation supernatants in micronuclei formation was evaluated in human lymphocytes. In addition, the genoprotective properties of increasing concentrations of aqueous extracts from P. eryngii mushrooms (150, 300, 600 mg/kg) against the cyclophosphamide-induced DNA damage were studied in young and elderly female and male mice in bone marrow and whole blood cells. The ability of the highest dose (600 mg/kg) to regulate the main cellular signaling pathways was also evaluated in gut and liver tissues of female animals by quantifying the mRNA expression of NrF2, Nfkβ, DNMT1, and IL-22 genes. P. eryngii post-fermentation, but not pre-fermentation, supernatants were able to protect human lymphocytes from the mitomycin C-induced DNA damage in a dose-dependent manner. Similarly, genoprotection was also observed in bone marrow cells of mice treated by gavage with P. eryngii extract. The effect was observed in all the experimental groups of mice (young and elderly, male and female) and was more potent in young female mice. Overexpression of all genes examined was observed in both tissues, mainly among the elderly animals. In conclusion, P. eryngii mushrooms were shown to maintain genome integrity through protecting cells from genotoxic insults. These beneficial effects can be attributed to their antioxidant and immunomodulatory properties, as well as their ability to regulate the cell's epigenetic mechanisms and maintain cell homeostasis.

Antioxidant and Immunostimulatory Activities of Fermented Sour Soybean Milk Added With Polypeptides From Pleurotus eryngii

The improved quality of sour soybean milk by adding polypeptide from Pleurotus eryngii was investigated in this study, and the immunomodulatory effect of sour soybean milk fermented with polypeptides from P. eryngii was also evaluated in immunosuppressed mice induced by cyclophosphamide. Results showed the physicochemical property of sour soybean milk fermented with small-molecular-weight polypeptide (<3 kDa) were superior to the others including the decrease of pH, and increase of acidity, water-holding capacity and lactic acid bacteria count. The animal experiment demonstrated that sour soybean milk with polypeptide could effectively reverse the decreasing trend of thymus/spleen index and hematological parameters, enhance murine immune functions including serum hemolysin and splenic lymphocyte proliferation, and inhibit oxidative stress. In addition, sour soybean milk fermented with polypeptide could increase the diversity of intestinal flora, and increase the abundances of Firmicutes, Bacteroides, and Lactobacillus. Taken together, it could provide a theoretical basis for developing an immunomodulatory agent or functional food additives with antioxidant activity.

Structural characterization and immunomodulatory activity of a mannan from Helvella leucopus

A new polysaccharide fraction HLP-1 (2.55 × 10⁵ Da) was obtained from the fruiting bodies of Helvella leucopus. Structural characterization of HLP-1 was elucidated by infrared spectroscopy, monosaccharide composition analysis, methylation analysis, nuclear magnetic resonance spectroscopy, scanning electron microscopy and Congo red assay. HLP-1 was a mannan with a backbone of →6)-α-D-Manp(1 → 4)- α-D-Manp(1 → 6)-α-D-Manp(1 → 3)-α-D-Manp(1 → 4)-α-D-Manp(1 → 3)-α-D-Manp(1→, which branched at the O-6 position and terminated with T-β-D-Manp. Moreover, HLP-1 could significantly improve the proliferation and neutral red phagocytosis of RAW264.7. Besides, HLP-1 could stimulate the production of nitric oxide (NO), ROS, tumor necrosis factor-α (TNF-α), interleukin-1 beta (IL-1β) and interleukin-6 (IL-6). HLP-1 induced macrophage activation via NF-κB signal pathway. These findings indicated that HLP-1 was a potential immune enhancement agent applied in functional foods.

A Novel Mechanism of Macrophage Activation by the Natural Yolkin Polypeptide Complex from Egg Yolk

Ageing is accompanied by the inevitable changes in the function of the immune system. It provides increased susceptibility to chronic infections that have a negative impact on the quality of life of older people. Therefore, rejuvenating the aged immunity has become an important research and therapeutic goal. Yolkin, a polypeptide complex isolated from hen egg yolks, possesses immunoregulatory and neuroprotective activity. Considering that macrophages play a key role in pathogen recognition and antigen presentation, we evaluated the impact of yolkin on the phenotype and function of mouse bone marrow-derived macrophages of the BMDM cell line. We determined yolkin bioavailability and the surface co-expression of CD80/CD86 using flow cytometry and IL-6, IL-10, TGF-β and iNOS mRNA expression via real-time PCR. Additionally, the impact of yolkin on the regulation of cytokine expression by MAPK and PI3K/Akt kinases was determined. The stimulation of cells with yolkin induced significant changes in cell morphology and an increase in CD80/CD86 expression. Using pharmaceutical inhibitors of ERK, JNK and PI3K/Akt, we have shown that yolkin is able to activate these kinases to control cytokine mRNA expression. Our results suggest that yolkin is a good regulator of macrophage activity, priming mainly the M1 phenotype. Therefore, it is believed that yolkin possesses significant therapeutic potential and represents a promising possibility for the development of novel immunomodulatory medicine.

Proteomic Research on the Antitumor Properties of Medicinal Mushrooms

Medicinal mushrooms are increasingly being recognized as an important therapeutic modality in complementary oncology. Until now, more than 800 mushroom species have been known to possess significant pharmacological properties, of which antitumor and immunomodulatory properties have been the most researched. Besides a number of medicinal mushroom preparations being used as dietary supplements and nutraceuticals, several isolates from mushrooms have been used as official antitumor drugs in clinical settings for several decades. Various proteomic approaches allow for the identification of a large number of differentially regulated proteins serendipitously, thereby providing an important platform for a discovery of new potential therapeutic targets and approaches as well as biomarkers of malignant disease. This review is focused on the current state of proteomic research into antitumor mechanisms of some of the most researched medicinal mushroom species, including Phellinus linteus, Ganoderma lucidum, Auricularia auricula, Agrocybe aegerita, Grifola frondosa, and Lentinus edodes, as whole body extracts or various isolates, as well as of complex extract mixtures.

Gut microbiota-dependent catabolites of tryptophan play a predominant role in the protective effects of turmeric polysaccharides against DSS-induced ulcerative colitis

Gut barrier dysfunction is triggered by gut microbiota dysbiosis that is closely associated with ulcerative colitis. Recently, more attention has been devoted to the ability of the non-digestively colon-targeted plant polysaccharides to regulate the function and composition of the intestinal microbiota. Here, we first studied the prophylactic capacity of turmeric polysaccharides (TPS) to ameliorate dextran sulfate sodium (DSS)-induced gut microbiota imbalance. The results revealed that TPS administration could greatly improve the pathological phenotype, gut barrier disruption and colon inflammation in colitis mice. Besides, targeted metabolomics or 16S rRNA-based microbiota analysis demonstrated that TPS alleviated gut microbiota dysbiosis caused by DSS, especially increasing the abundance of probiotics associated with tryptophan metabolism, such as Lactobacillus and Clostridia-UCG-014, where the cecal tryptophan catabolite indole-3-acetic acid (IAA) and its ligand aryl hydrocarbon receptor (AhR) expressions were sharply increased by TPS treatment in colitis mice. Expectedly, TPS was found to exert its gut barrier functions through the activation of AhR to upregulate epithelial tight junction proteins. These findings highlight the protective effects of TPS against ulcerative colitis by modulating the gut microbiota and improving microbial metabolites and gut barrier function.

Isolation, purification and identification of immunologically active peptides from Hericium erinaceus

Biologically active peptides released by proteins are important in regulating immunity. The purpose of this study was to isolate and purify an immunologically active peptide from Hericium erinaceus (H. erinaceus) and to explore its effect on cytokine secretion and differentiation of macrophages. An active peptide with an amino acid sequence, Lys-Ser-Pro-Leu-Tyr (KSPLY) was obtained from H. erinaceus protein by ultrafiltration combined with multistage chromatography separation and identification technology. Subsequently, it was confirmed that the synthetic peptide KSPLY had a good immunomodulatory activity at a concentration of 100 μmol/L and could promote the secretion of NO, IL-1β, IL-6 and TNF-α by macrophages. The effects of KSPLY on M1 macrophages and M2 macrophages were also studied. Results showed that KSPLY inhibited the secretion of NO and IL-6 by M1 macrophages and promoted the tendency of M2 macrophages to transform to M1 macrophages. Therefore, it can be concluded that KSPLY is an effective immunomodulatory peptide that may be beneficial in cancer treatment and human health improvement.

Mushroom-Derived Bioactive Molecules as Immunotherapeutic Agents: A Review

Mushrooms with enhanced medicinal properties focus on finding such compounds that could modulate the human body's immune systems. Mushrooms have antimicrobial, antidiabetic, antiviral, hepatoprotective, antitumor, and immunomodulatory properties due to the presence of various bioactive components. β-glucans are the major constituent of the mushroom cell wall and play a significant role in their biological activity. This review described the techniques used in the extraction of the active ingredients from the mushroom. We highlighted the structure of the bioactive polysaccharides present in the mushrooms. Therapeutic applications of different mushrooms were also described. It is interesting to note that mushrooms have the potential sources of many bioactive products that can regulate immunity. Thus, the development of functional medicinal food based on the mushroom is vital for human welfare.

Characterization of the Immunomodulatory Mechanism of a Pleurotus eryngii Protein by Isobaric Tags for Relative and Absolute Quantitation Proteomics

PEP 1b is a novel immunoregulatory protein isolated from Pleurotus eryngii, a popular edible mushroom. In this study, isobaric tags for relative and absolute quantitation (iTRAQ) approach and bioinformatics analysis were used to characterize the PEP-1b-induced proteome alterations in Raw 264.7 macrophage cells, to comprehensively excavate the molecular mechanisms involved in the immunoregulatory effects of PEP 1b. In comparison to the control group, PEP 1b treatment significantly changed the expression of 292 proteins, including 191 upregulated and 101 downregulated proteins. Bioinformatics analysis showed that PEP-1b-regulated proteins were involved in 437 biological process domains, 131 cellular component domains, and 90 molecular function domains. Moreover, PEP 1b played the role of immunomodulator by mainly modulating the Rap1 signaling pathway, Wnt signaling pathway, Ras signaling pathway, and PI3K-Akt signaling pathway. Interestingly, PEP 1b regulated the proteins involved in the immune system, signal transduction, and transport processes, which were related to the immunoregulatory effects of PEP 1b. The western blotting analysis confirmed that the immune-boosting activities of PEP 1b were associated with modulating the expression of Sqstm1, Cox2, Rap1b, and Pyk2. The current research provided a comprehensive understanding of the immunoregulatory effects and molecular mechanisms involved in the PEP 1b supplementation.

Current Understanding of the Structure and Function of Fungal Immunomodulatory Proteins

Fungal immunomodulatory proteins (FIPs) are a group of proteins found in fungi, which are extensively studied for their immunomodulatory activity. Currently, more than 38 types of FIPs have been described. Based on their conserved structure and protein identity, FIPs can be classified into five subgroups: Fve-type FIPs (Pfam PF09259), Cerato-type FIPs (Pfam PF07249), PCP-like FIPs, TFP-like FIPs, and unclassified FIPs. Among the five subgroups, Fve-type FIPs are the most studied for their hemagglutinating, immunomodulating, and anti-cancer properties. In general, these small proteins consist of 110–125 amino acids, with a molecular weight of ~13 kDa. The other four subgroups are relatively less studied, but also show a noticeable influence on immune cells. In this review, we summarized the protein modifications, 3-dimensional structures and bioactivities of all types of FIPs. Moreover, structure-function relationship of FIPs has been discussed, including relationship between carbohydrate binding module and hemagglutination, correlation of oligomerization and cytokine induction, relevance of glycosylation and lymphocyte activation. This summary and discussion may help gain comprehensive understanding of FIPs' working mechanisms and scope future studies.

Anticancer potentiality and mode of action of low-carbohydrate proteins and peptides from mushrooms

Severe side effects of chemotherapy as well as drug resistance highlight the ongoing need to discover novel natural bioactive compounds with anticancer potentiality. Mushroom-derived proteins are among the naturally occurring compounds that have been the subject of a body of research on their potentiality in cancer therapy. The greatest attention in relevant review articles has been paid to well-known mushroom-derived glycoproteins such as lectins and protein-bound polysaccharide complexes such as polysaccharide-K (PSK) or krestin and polysaccharopeptide (PSP), which contain substantial amounts of carbohydrates (50-90%). These complex compounds exert their anticancer activity mainly by binding to cell membranes leading to extrinsic (death receptor) apoptosis or intrinsic (mitochondrial) apoptotic pathways. However, several other research studies have reported pure, well-characterized, proteins or peptides from mushrooms, which are carbohydrate-free or have very low amounts of carbohydrate. These proteins may fall into four categories including fungal immunomodulatory proteins, ubiquitin-like proteins, enzymes, and unclassified proteins. Well-defined chemical structure, elucidated full amino acid or N-terminal sequences, purity, and having some distinct and specific pathways compared to glycoproteins have made these low-carbohydrate proteins attractive for cancer research. The aim of this review was therefore to improve the current understanding of mushroom-derived low-carbohydrate proteins and to consolidate the existing knowledge of the most promising mushroom species from which low-carbohydrate proteins have been derived, characterized, and examined for their anticancer activity. In addition, molecular targets and mechanisms of action of these proteins have been discussed. Key points • Mushroom-derived low-carbohydrate proteins lack or have low carbohydrate. • Low-carbohydrate proteins show potent anticancer activities in vitro and in vivo. • There are specific pathways for low-carbohydrate proteins to inhibit cancer cells.

Effects of a β-type glycosidic polysaccharide from Flammulina velutipes on anti-inflammation and gut microbiota modulation in colitis mice

Using the Flammulina velutipes polysaccharide (FVP) extracted from our previous study, herein, we investigated the improvement of this β-type glycosidic polysaccharide in alleviating dextran sodium sulfate-induced ulcerative colitis (UC) in mice.

Physicochemical and functional properties of a protein isolate from maca (Lepidium meyenii) and the secondary structure and immunomodulatory activity of its major protein component

Maca protein isolate (MPI) was extracted from maca root, and its physicochemical and functional properties, and the secondary structure and immunomodulatory activity of its major protein component, MMP, were investigated. The MPI lacked essential amino acids compared with soybean protein isolate (SPI) and casein, but was rich in cysteine and proline. The MPI had rich free sulfhydryl (20.6 μmol g-1), and its surface hydrophobicity (H0, 812.4), oil absorption capacity (7.4 g g-1), foaming capacity (100%) and emulsifying activity (58.2 m2 g-1) were higher than that of SPI. However, the thermal stability (Td, 87.4 °C), foaming stability (75%) and emulsifying stability (26.3 min) of the MPI were weaker than that of the SPI. MMP was a pentamer with a molecular weight of 22 kDa and rich in β-sheets. MMP could significantly enhance the phagocytic capacity and promote the NO, TNF-α and IL-6 secretion of RAW 264.7 cells, involving toll-like receptor 4 and complement receptor 3 mainly.

Purification and Characterization of a Novel Pentadecapeptide from Protein Hydrolysates of Cyclina sinensis and Its Immunomodulatory Effects on RAW264.7 Cells

In the present study, peptide fractions of Cyclina sinensis hydrolysates, with molecular weight (MW) < 3 kDa and highest relative proliferation rate of murine macrophage cell line RAW 264.7, were purified by a series of chromatographic purification methods, to obtain peptide fractions with immunomodulatory activity. The amino acid sequence of the peptide was identified to be Arg-Val-Ala-Pro-Glu-Glu-His-Pro-Val-Glu-Gly-Arg-Tyr-Leu-Val (RVAPEEHPVEGRYLV) with MW of 1750.81 Da, and the novel pentadecapeptide (named SCSP) was synthesized for subsequent immunomodulatory activity experiments. Results showed the SCSP enhanced macrophage phagocytosis, increased productions of nitric oxide (NO), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β), and up-regulated the protein level of inducible nitric oxide synthase (iNOS), nuclear factor κB (NF-κB), and NOD-like receptor protein 3 (NLRP3) in RAW 264.7 cells. Furthermore, the expression of inhibitor of nuclear factor κB-α (IκB-α) was down-regulated. These findings suggest that SCSP might stimulate macrophage activities by activating the NF-κB signaling pathway and can be used as a potential immunomodulatory agent in functional food or medicine.