FIP-fve stimulates interferon-gamma production via modulation of calcium release and PKC-alpha activation

Systematic Characterization of the Group 2 House Dust Mite Allergen in Dermatophagoides microceras

Background

Allergic asthma, a chronic airway inflammatory disease, is a critical public health problem. Indoor house dust mites (HDMs) could cause allergic asthma. The prevalence of sensitization to Dermatophagoides microceras (Der m) was approximately 80% and is related to the immunoglobulin E crossing-reactivity of mites belonging to the same genus, Dermatophagoides pteronyssinus (Der p) and Dermatophagoides farina (Der f). However, studies on Der m are scant.

Methods

We used integrated OMICs approaches to identify and characterize the group 2 mite allergen-like protein in Der m (Der m 2). We established a Der m 2-induced allergic asthma mouse model and treated the mice with a fungal immunomodulatory protein (FIP-fve) isolated from Flammulina veluptipes to evaluate the allergenicity of Der m 2 and the immunomodulatory effects of FIP-fve.

Results

By performing de novo draft genome assembly and comparative genome analysis, we identified the putative 144-amino acid Der m 2 in silico and further confirmed its existence through liquid chromatography–tandem mass spectrometry. Der m 2 is a lipopolysaccharides (LPS)-binding protein. Thus, we examined the LPS-binding activity of recombinant Der m 2 by performing molecular docking analysis, co-immunoprecipitation (Co-IP), and a pull-down assay. Der m 2 elicited the production of pro-inflammatory cytokines, interleukin (IL)-6, and IL-8 in BEAS-2B cells, a human bronchial epithelial cell line, and induced airway hyperresponsiveness in mice. Furthermore, in mice sensitized with Der m 2, the administration of FIP-fve in either the earlier stage or the late stage, FIP-fve alleviated allergic asthma by moderating airway inflammation and remodeling.

Conclusions

Der m 2 induced inflammatory responses in cell and mouse models. FIP-fve alleviated inflammation in Der m 2-induced asthma in mice by exerting an immunomodulatory effect.

Functional evaluation of a recombinant fungal immunomodulatory protein from L. rhinocerus produced in P. pastoris and E. coli host expression systems

Fungal immunomodulatory proteins (FIPs) are bioactive proteins with immunomodulatory properties. We previously reported the heterologous production in Escherichia coli of FIP-Lrh from Tiger milk mushroom (Lignosus rhinocerus) with potent cytotoxic effect on cancer cell lines. However, protein produced in E. coli lacks post-translational modifications and may be contaminated with lipopolysaccharide (LPS) endotoxin. Therefore, in this study, yFIP-Lrh produced in Pichia pastoris was functionally compared with eFIP-Lrh produced in E. coli. Expression construct of FIP-Lrh cDNA in pPICZα was generated, transformed into P. pastoris X-33 and Mut⁺ transformants were verified by colony PCR. Induction with 0.5% or 1% methanol resulted in a secreted 13.6 kDa yFIP-Lrh which was subsequently purified and verified using LCMS/MS analysis. Size exclusion chromatography confirmed eFIP-Lrh as a homodimer whereas the larger size of yFIP-Lrh may indicate post-translational modification despite negative for glycoproteins staining. At lower concentration (4-8 μg/mL), yFIP-Lrh induced significantly higher Th1 (IFN-γ, TNF-α) and Th2 (IL-6, IL-4, IL-5, IL-13) cytokines production in mice splenocytes, whereas 16 μg/mL eFIP-Lrh induced significantly higher pro-inflammatory cytokines (TNF-α, IL-6, IL-10), possibly due to higher residual LPS endotoxin (0.082 EU/mL) in eFIP-Lrh compared to negligible level in yFIP-Lrh (0.001 EU/mL). Furthermore, yFIP-Lrh showed higher cytotoxic effect on MCF-7 and HeLa cancer cells. Since both recombinant proteins of FIP-Lrh have the same peptide sequence, besides glycosylation, other post-translational modifications in yFIP-Lrh may account for its enhanced immunomodulatory and anti-proliferative activities. In conclusion, P. pastoris is preferred over E. coli for production of a functionally active yFIP-Lrh devoid of endotoxin contamination. KEY POINTS: • FIP-Lrh can induced production of Th1 and Th2 cytokines by mouse splenocytes. • Higher cytotoxic effect on cancer cells observed for yeast compared to E. coli produced FIP-Lrh. • P. pastoris allows production of an endotoxin-free and functionally active recombinant FIP-Lrh.

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.

D-Methionine Ameliorates Cisplatin-Induced Muscle Atrophy via Inhibition of Muscle Degradation Pathway

Cisplatin induces anorexia, weight loss, loss of adipose tissue, skeletal muscle atrophy, and serious adverse effects that can cause premature termination of chemotherapy. The aim of this study was to use an animal model to assess cisplatin therapy (3 cycles) with and without d-methionine to investigate its protective effects on cisplatin-induced anorexia and skeletal muscle wasting. Wistar rats were divided into 3 groups and treated as follows: saline as control (group 1), intraperitoneal cisplatin once a week for 3 weeks (group 2), and intraperitoneal cisplatin once a week for 3 weeks plus oral administration of d-methionine (group 3). Tissue somatic index (TSI), gastric emptying index (GEI), and feeding efficiency were measured. Both hepatic lipid metabolism and muscle atrophy-related gene expressions and C2C12 myotubes were determined by polymerase chain reaction. Micro-computed tomography (micro-CT) was used to conduct assessment of bone microarchitecture indices. Pathological changes of the gastric mucosa were assessed by hematoxylin and eosin staining after euthanizing the animals. d-Methionine increased food intake, weight gain, gastric emptying, and feeding efficiency, as well as decrease stomach contents, after cisplatin injections. Cisplatin caused shortening of myofibers. Cisplatin-induced muscle mass wasting was mediated by the elevation of mRNA expressions of MAFbx and MuRF-1 in ubiquitin ligases in muscle tissue homogenate. The mRNA expressions of MyoD and myogenin, markers of muscle differentiation, declined following cisplatin administration. The administration of d-methionine not only led to significant improvements in myofiber diameter and cross-sectional fiber areas but also reversed muscle atrophy-related gene expression. However, there were no significant changes in stomach histology or microarchitecture of trabecular bone among the study groups. The results indicate that d-methionine has an appetite-enhancing effect and ameliorates cisplatin-induced adipose and muscle tissue loss during cisplatin-based chemotherapy.

Golden Needle Mushroom: A Culinary Medicine with Evidenced-Based Biological Activities and Health Promoting Properties

Flammulina velutipes (enoki, velvet shank, golden needle mushroom or winter mushroom), one of the main edible mushrooms on the market, has long been recognized for its nutritional value and delicious taste. In recent decades, research has expanded beyond detailing its nutritional composition and delved into the biological activities and potential health benefits of its constituents. Many bioactive constituents from a range of families have been isolated from different parts of the mushroom, including carbohydrates, protein, lipids, glycoproteins, phenols, and sesquiterpenes. These compounds have been demonstrated to exhibit various biological activities, such as antitumour and anticancer activities, anti-atherosclerotic and thrombosis inhibition activity, antihypertensive and cholesterol lowering effects, anti-aging and antioxidant properties, ability to aid with restoring memory and overcoming learning deficits, anti-inflammatory, immunomodulatory, anti-bacterial, ribosome inactivation and melanosis inhibition. This review aims to consolidate the information concerning the phytochemistry and biological activities of various compounds isolated from F. velutipes to demonstrate that this mushroom is not only a great source of nutrients but also possesses tremendous potential in pharmaceutical drug development.

Characterisation of a New Fungal Immunomodulatory Protein from Tiger Milk mushroom, Lignosus rhinocerotis

Lignosus rhinocerotis (Tiger milk mushroom) is an important folk medicine for indigenous peoples in Southeast Asia. We previously reported its de novo assembled 34.3 Mb genome encoding a repertoire of proteins including a putative bioactive fungal immunomodulatory protein. Here we report the cDNA of this new member (FIP-Lrh) with a homology range of 54–64% to FIPs from other mushroom species, the closest is with FIP-glu (LZ-8) (64%) from Ganoderma lucidum. The FIP-Lrh of 112 amino acids (12.59 kDa) has a relatively hydrophobic N-terminal. Its predicted 3-dimensional model has identical folding patterns to FIP-fve and contains a partially conserved and more positively charged carbohydrates binding pocket. Docking predictions of FIP-Lrh on 14 glycans commonly found on cellular surfaces showed the best binding energy of −3.98 kcal/mol to N-acetylgalactosamine and N-acetylglucosamine. Overexpression of a 14.9 kDa soluble 6xHisFIP-Lrh was achieved in pET-28a(+)/BL21 and the purified recombinant protein was sequence verified by LC-MS/MS (QTOF) analysis. The ability to haemagglutinate both mouse and human blood at concentration ≥0.34 μM, further demonstrated its lectin nature. In addition, the cytotoxic effect of 6xHisFIP-Lrh on MCF-7, HeLa and A549 cancer cell lines was detected at IC₅₀ of 0.34 μM, 0.58 μM and 0.60 μM, respectively.

Recombinant expression of a novel fungal immunomodulatory protein with human tumor cell antiproliferative activity from Nectria haematococca

To our best knowledge, all of the fungal immunomodulatory proteins (FIPs) have been successfully extracted and identified in Basidomycetes, with only the exception of FIP from ascomycete Nectria haematococca (FIP-nha) discovered through homology alignment most recently. In this work, a gene encoding FIP-nha was synthesized and recombinantly expressed in an Escherichia coli expression system. SDS-PAGE and MALDI-MS analyses of recombinant FIP-nha (rFIP-nha) indicated that the gene was successfully expressed. The yield of the bioactive FIP-nha protein was 42.7 mg/L. In vitro assays of biological activity indicated that the rFIP-nha caused hemagglutination of human and rabbit red blood cells, significantly stimulated mouse spleen lymphocyte proliferation, and enhanced expression of interleukin-2 (IL-2) released from mouse splenocytes, revealing a strong antitumor effect against HL60, HepG2 and MGC823. Through this work, we constructed a rapid and efficient method of FIP production, and suggested that FIP-nha is a valuable candidate for use in future medical care and pharmaceutical products.

Alleviation of Dermatophagoides microceras-induced allergy by an immunomodulatory protein, FIP-fve, from Flammulina velutipes in mice

Asthma is a major public health concern. Its greatest risk factor is house dust mite (HDM). Dermatophagoides microceras (Der m) is a type of HDM, and in central Taiwan, there is approximately 80% prevalence of sensitization to Der m. FIP-fve is a fungal immunomodulatory protein (FIP) isolated from the fungus Flammulina velutipes, and exhibits anti-inflammatory properties. To investigate whether FIP-fve affects Der m-induced asthma and inflammation, we evaluated hyper-responsiveness (AHR), pathological changes, and cytokines in mice. We demonstrated that oral FIP-fve decreased Der m-induced airway AHR, airway inflammation, cell infiltration, and expression of cytokines in the bronchoalveolar lavage fluid of Balb/c mice. The results of this study suggest that FIP-fve suppresses asthma, inflammation, and respiratory pathogenesis stimulated by Der m. FIP-fve is able to maintain immunomodulatory activity even in simulated gastric fluid and intestinal fluid. FIP-fve could be a safe and stable agent for suppression of allergic asthma.

Interruption of lung cancer cell migration and proliferation by fungal immunomodulatory protein FIP-fve from Flammulina velutipes

FIP-fve is an immunomodulatory protein isolated from Flammulina velutipes that possesses anti-inflammatory and immunomodulatory activities. However, little is known about its anticancer effects. It is suppressed cell proliferation of A549 lung cancer cells on MTT assay following 48 h treatment of FIP-fve. FIP-fve treatment also resulted in cell cycle arrest but not apoptosis on flow cytometry. This immunomodulatory protein was observed to increase p53 expression, as well as the expression of its downstream gene p21, on Western blot. FIP-fve inhibited migration of A549 cells on wound healing assay and decreased filopodia fiber formation on labeling with Texas Red-X phalloidin. To confirm the effect of FIP-fve on the role of Rac1 in filopodia formation, we investigated the activity of Rac1 in A549 cells following FIP-fve treatment. FIP-fve inhibited EGF-induced activation of Rac1. We demonstrated that FIP-fve decreases RACGAP1 mRNA and protein levels on RT-PCR and Western blot. In addition, the reporter activity of RACGAP1 was reduced by FIP-fve on RacGAP1 promoter assay. Silencing of RacGAP1 decreased cell migration, and overexpression of RacGAP1 increased cell migration in A549 cells. In conclusion, FIP-fve inhibits lung cancer cell migration via RacGAP1 and suppresses the proliferation of A549 via p53 activation pathway.

Characterization of a novel maitake (Grifola frondosa) protein that activates natural killer and dendritic cells and enhances antitumor immunity in mice

Grifola frondosa, also known as maitake, is a culinary mushroom with immune-enhancing and antitumor effects. Numerous studies have investigated the activity of maitake polysaccharide extracts, but studies of maitake proteins are scarce. In this study, we purified and characterized a new G. frondosa protein, GFP, from maitake fruiting bodies. GFP is a nonglucan heterodimeric 83 kDa protein that consists of two 41 kDa subunits. GFP induced interferon-γ secretion by murine splenocytes and natural killer cells and activated the maturation of bone marrow-derived dendritic cells (BMDCs) via a TLR4-dependent mechanism. GFP-treated BMDCs promoted a Th1 response and exhibited significant antitumor activity when transferred into tumor-bearing mice. In conclusion, we are the first to reveal the critical role of GFP in modulating the immune response and to link the immune-enhancing effects of maitake to its antitumor activities.

High-Yield Production in Escherichia coli of Fungal Immunomodulatory Protein Isolated from Flammulina velutipes and Its Bioactivity Assay in Vivo

A fungal immunomodulatory protein isolated from Flammulina velutipes (FIP-fve) has structural similarity to the variable region of the immunoglobulin heavy chain. In the present study, the recombinant bioactive FIP-fve protein with a His-tag in N-terminal of recombinant protein was expressed in transetta (DE3) at a high level under the optimized culturing conditions of 0.2 mM IPTG and 28 °C. The efficiency of the purification was improved with additional ultrasonication to the process of lysozyme lysis. The yield of the bioactive FIP-fve protein with 97.1% purity reached 29.1 mg/L with a large quantity for industrial applications. Enzyme-linked immunosorbent assay showed a maximum increase in interleukin-2 (IL-2) and gamma interferon (IFN-γ) for the mice serum group of 5 mg/kg body mass (p < 0.01) with three doses of His-FIP-fve. However, the production of IL-4 had no apparent difference compared to the control.

Effect of the fungal immunomodulatory protein FIP-fve on airway inflammation and cytokine production in mouse asthma model

The allergy is dependent on the balance between Th1 and Th2. The fungal immunodulatory protein (FIP-fve) was isolated from Flammulina velutipes. FIP-fve has been demonstrated to skew the response to Th1 cytokine production. We investigated whether oral administrations of FIP-fve inhibited allergen (OVA)-induced chronic airway inflammation in the mouse asthma model. After intranasal challenge with OVA, the airway inflammation and hyperresponsiveness were determined by bronchoalveolar lavage fluid (BALF) analysis and ELISA assay. Both pre-treated and post-treated with FIP-fve suppressed the airway hyperresponsiveness by methacholine challenge and significantly decreased the number of infiltrating inflammatory cells and Th2 cytokines in bronchoalveolar lavage fluid (BALF) and serum compared with the OVA sensitized mice. In addition, FIP-fve reduced OVA-specific IgE levels in serum. FIP-fve markedly alleviated the OVA-induced airway hyperresponsiveness (AHR) to inhaled methacholine. Based on lung histopathological studies using hematoxylin and Liu's staining, FIP-fve inhibited inflammatory cell infiltration compared with the OVA-sensitized mice. Oral FIP-fve had an anti-inflammatory effect on OVA-induced airway inflammations and might posses the potential for alternative therapy for allergic airway diseases.

IFN-γ induction on carbohydrate binding module of fungal immunomodulatory protein in human peripheral mononuclear cells

FIP-fve is a protein that is isolated from Flammulina velutipes . Its known immunomodulatory activities are elicitation of the production of type II interferon from human peripheral mononuclear cells (hPBMCs) and hemagglutination. How the target receptors mediate activation of FIP-fve-induced immunomodulatory effects remains to be elucidated. This study postulates the three-dimensional structures to determine whether the carbohydrate binding module family 34 (CBM-34) on FIP-fve is conserved to site N of Thermoactinomyces vulgaris R-47 α-amylase I. Experimental site-directed mutagenesis data as well as ligand-specific binding competition assay are adopted to identify the key residues W24, T28, D34, T90, I91, and W111 of FIP-fve that participate in binding to polysaccharides that are linked to the membrane of immune cells. Treatments of hPBMCs with tunicamycin and deglycosylation enzymes that removed the carbohydrate moieties reduced the secretion of IFN-γ induction from hPBMCs. In conclusion, the experiments herein demonstrated the ligand-binding CBM-34 on FIP-fve and ligand-like glycoproteins on the surface of hPBMCs must be required to induce physiological immunomodulatory effects.

Recent status and prospects of the fungal immunomodulatory protein family

With the exception of polysaccharides and triterpenes/triterpenoids compounds, fungal immunomodulatory protein (FIP), a small molecule protein, is also an important bioactive component with immune regulating activity. It plays a significant role in immunomodulating. The objective of this paper was to review the latest advances in various aspects of research on FIPs, including their basic components and structural character, characters of diversity, gene cloning and expression, and their biological function, etc. In addition, prospects of utilization value and the exploitation foreground of FIPs were also discussed. The review will provide a useful reference for further research, development, and utilizations of FIPs.