Histamine-releasing factor and immunoglobulins in asthma and allergy

Potential of histamine release factor for the utilization as a universal vaccine antigen against poultry red mites, tropical fowl mites, and northern fowl mites

Poultry red mites (PRMs, Dermanyssus gallinae), tropical fowl mites (TFMs, Ornithonyssus bursa), and northern fowl mites (NFMs, Ornithonyssus sylviarum) are hematophagous mites that are distributed worldwide which pose a serious challenge to the poultry industry and negatively impact poultry production and welfare. Vaccines represent a promising approach for controlling avian mites, and the identification of antigens with broad efficacy against multiple avian mite species is advantageous for vaccine control. This study aimed to identify histamine release factor (HRF), which was previously reported as a candidate vaccine antigen against PRMs, from TFMs and NFMs and to analyze its cross-reactivity and acaricidal effects on different avian mite species. The deduced amino acid sequences of the HRFs identified in the TFMs and NFMs were highly homologous to those of the PRMs. We generated recombinant HRF (rHRF) of TFMs, NFMs, and PRMs, and immune plasma against each rHRF was produced by immunization with each antigen. The immune plasma contained antibodies specific to each antigen and showed cross-reactivity with rHRFs from different avian mites. Moreover, PRM nymphs (protonymphs) artificially fed each immune plasma showed higher mortality rates than those fed the control plasma. These results suggest that HRFs can be used as candidate antigens for a universal vaccine with broad efficacy across avian mites.

The multifaceted potential of TPT1 as biomarker and therapeutic target

Tumor Protein Translationally-Controlled 1 (TPT1) is a highly conserved gene found across eukaryotic species. The protein encoded by TPT1 is ubiquitously expressed both intracellularly and extracellularly across various tissues, and its levels are influenced by various external factors. TPT1 interacts with several key proteins, including p53, MCL1, and immunoglobulins, highlighting its crucial role in cellular processes. The dysregulation of TPT1 expression has been documented in a wide range of diseases, indicating its potential as a valuable biomarker. Additionally, targeting TPT1 presents a promising approach for treating and preventing various conditions. This review will assess the potential of TPT1 as a biomarker and evaluate the effectiveness of current strategies designed to inhibit TPT1 in disease contexts.

Hispidulin Alleviates Mast Cell-Mediated Allergic Airway Inflammation through FcεR1 and Nrf2/HO-1 Signaling Pathway

Allergic asthma is a type 2 immune-response-mediated chronic respiratory disease. Mast cell activation influences the pathogenesis and exacerbation of allergic asthma. Therefore, the development of mast cell-targeting pharmacotherapy is important for managing allergic airway inflammation. We investigated the efficacy of hispidulin (HPD), natural flavone, in a mast-cell-mediated ovalbumin (OVA)-induced allergic airway inflammation model. HPD alleviated symptoms of allergic asthma and decreased the levels of immunoglobulin (Ig) E, type 2 inflammation, immune cell infiltration, and mast cell activation in the lung. Furthermore, in vivo analysis confirmed the efficacy of HPD through the evaluation of IgE-mediated allergic responses in a mast cell line. HPD treatment inhibited mast cell degranulation through inhibition of the FcεR1 signaling pathway and suppressed the expression of inflammatory cytokines (TNF-α, IL-4, IL-6, and IL-13) through suppression of the NF-κB signaling pathway. The antioxidant effects of HPD in activated mast cells were identified through modulation of antioxidant enzymes and the Nrf2/HO-1 signaling pathway. In conclusion, HPD may be a potential therapeutic candidate for allergic airway inflammation of asthma and acts by suppressing mast cell activation and oxidative stress.

Identification and characterization of a novel nematode pan allergen (NPA) from Wuchereria bancrofti and their potential role in human filarial tropical pulmonary eosinophilia (TPE)

BACKGROUND

Tropical pulmonary eosinophilia (TPE) is a chronic respiratory syndrome associated with Lymphatic Filariasis (LF), a tropical parasitic infection of the human, transmitted by mosquitoes. The larval form of LF (microfilariae) are trapped in the lungs of TPE subjects have a major role in initiating the TPE syndrome. To date, there are no reports on the potential allergen that is responsible for generating parasite-specific IgE in TPE.

METHODOLOGY/PRINCIPAL FINDINGS

In this project, we screened a cDNA expression library of the microfilarial stages of Wuchereria bancrofti with monoclonal IgE antibodies prepared from subjects with clinical filarial infections. Our studies identified a novel molecule that showed significant sequence similarity to an allergen. A blast analysis showed the presence of similar proteins in a number of nematodes parasites. Thus, we named this molecule as Nematode Pan Allergen (NPA). Subsequent functional analysis showed that NPA is a potent allergen that can cause release of histamine from mast cells, induce secretion of proinflammatory cytokines from alveolar macrophages and promote accumulation of eosinophils in the tissue, all of which occur in TPE lungs.

CONCLUSIONS/SIGNIFICANCE

Based on our results, we conclude that the NPA protein secreted by the microfilariae of W. bancrofti may play a significant role in the pathology of TPE syndrome in LF infected individuals. Further studies on this molecule can help design an approach to neutralize the NPA in an attempt to reduce the pathology associated with TPE in LF infected subjects.

Inhibitors of dimerized translationally controlled tumor protein, a histamine releasing factor, may serve as anti-allergic drug candidates

It has been established that translationally controlled tumor protein (TCTP), also called histamine releasing factor (HRF), exhibits cytokine-like activities associated with initiation of allergic responses only after forming dimers (dTCTP). Agents that inhibit dTCTP by preventing its dimerization or otherwise block its function, also block development of allergic reactions, thereby serving as potential drugs to treat allergic diseases. Several lines of evidence have proven that peptides and antibodies that specifically inhibit the interactions between dTCTP and either its putative receptor or immunoglobulins exhibit significant in vivo efficacy as potential anti-inflammatory agents in murine models of allergic inflammatory diseases. This review highlights the development of several inhibitors targeting dTCTP and discusses how they affect the pathophysiologic processes of allergic and inflammatory diseases in several animal models and offers new perspectives on anti-allergic drug discovery.

Oleanolic Acid Acetate Inhibits Mast Cell Activation in Ovalbumin-Induced Allergic Airway Inflammation

PURPOSE

Asthma is a complex, heterogeneous chronic inflammatory airway disease with multiple phenotypes. There has been a great progress in managing asthma, but there are still unmet needs for developing uncontrolled asthma treatments. The present study aimed to determine the effectiveness of oleanolic acid acetate (OAA) from Vigna angularis against allergic airway inflammation and the underlying mechanism of action with a focus on mast cells.

METHODS

To investigate the effect of OAA in allergic airway inflammation, we used the ovalbumin (OVA)-sensitized and challenged mice. To examine allergic airway inflammation associated with immune responses of mast cell activation in vitro, various types of mast cells were used. Systemic and cutaneous anaphylaxis models were used for mast cell-mediated hyper-responsiveness in vivo.

RESULTS

OAA reduced OVA-induced airway inflammatory responses such as bronchospasm, increase of immune cell infiltration and serum immunoglobulin E and G₁ levels. Especially, OAA decreased the mast cell infiltration, and β-hexosaminidase release as a mast cell activation marker in the bronchoalveolar lavage fluid. OAA inhibited mast cell degranulation in mast cell line (RBL-2H3) and primary cells (rat peritoneal mast cell and mouse bone marrow-derived mast cell). Mechanistically, OAA suppressed intracellular signaling pathways including the phosphorylation of phospholipase Cγ and nuclear factor-κB, resulting from the suppression of intracellular calcium influx and pro-inflammatory cytokine expression. Further, oral administration of OAA attenuated mast cell-mediated systemic and cutaneous anaphylaxis.

CONCLUSIONS

Our study showed that OAA can inhibit mast cell-mediated allergic reaction. Consequently, the application of OAA to mast cells for the allergic airway inflammation facilitate a new direction of treating allergic asthma.

Histamine-Releasing Factor Is a Novel Alarmin Induced by House Dust Mite Allergen, Cytokines, and Cell Death

Histamine-releasing factor (HRF) is a multifunctional protein with fundamental intracellular functions controlling cell survival and proliferation. HRF is also secreted during allergic reactions and promotes IgE-mediated activation of mast cells and basophils. In this study, we investigated HRF secretion and its relevance to airway inflammation. HRF monomers were constitutively secreted from BEAS-2B human bronchial epithelial cells (HBECs) and converted to oligomers over the course of culture. Stimulation with house dust mite (HDM) extract increased HRF secretion substantially. Several cytokines involved in asthma pathogenesis showed moderate effects on HRF secretion but dramatically enhanced HDM-induced HRF secretion. HDM-induced HRF secretion from BEAS-2B cells and normal HBECs proceeded via TLR2. Consistent with this, multiple TLR2 ligands, including Der p 2, Der p 5, Der p 13, and Der p 21, induced HRF secretion. Der p 10 (tropomyosin) also promoted HRF secretion. Cell death or incubation with adenosine and ATP, compounds released upon cell death, also enhanced HRF secretion. Furthermore, intranasal administration of recombinant HRF elicited robust airway inflammation in HDM-sensitized mice in an FcεRI-dependent manner. Therefore, we conclude that HRF is a novel alarmin that promotes allergic airway inflammation.

Allergic Inflammation Caused by Dimerized Translationally Controlled Tumor Protein is Attenuated by Cardamonin

We demonstrated in our previous reports that dimeric form of translationally controlled tumor protein (dTCTP) initiates a variety of allergic phenomena. In the present study, we examined whether and how dTCTP's role in allergic inflammation can be modulated or negated. The possible potential of cardamonin as an anti-allergic agent was assessed by ELISA using BEAS-2B cells and OVA-challenged allergic mouse model. The interaction between cardamonin and dTCTP was confirmed by SPR assay. Cardamonin was found to reduce the secretion of IL-8 caused by dTCTP in BEAS-2B cells by interacting with dTCTP. This interaction between dTCTP and cardamonin was confirmed through kinetic analysis (K_D = 4.72 ± 0.07 μM). Also, cardamonin reduced the migration of various inflammatory cells in the bronchoalveolar lavage fluid (BALF), inhibited OVA specific IgE secretion and bronchial remodeling. In addition, cardamonin was observed to have an anti-allergic response by inhibiting the activity of NF-κB. Cardamonin exerts anti-allergic anti-inflammatory effect by inhibiting dTCTP, suggesting that it may be useful in the therapy of allergic diseases.

Sagittaria trifolia tuber: bioconstituents, processing, products, and health benefits

Sagittaria trifolia is an aquatic plant that is distributed worldwide. The edible tuber part of S. trifolia is a very common and popular vegetable in China. The aim of the present review is to discuss the discovery of nutraceuticals from S. trifolia tuber by reviewing its major constituents, food processing, food products, and health-promoting benefits. Sagittaria trifolia tuber comprises a series of nutritional and bioactive constituents, including dietary fibers, amino acids, minerals, starches, non-starch polysaccharides, diterpenoids, colchicine, phenols, and organic acids. Food processing affects its flavor, biocomponents, and bioactivity. Numerous S. trifolia tuber-based food products and nutraceuticals have been developed, but new categories of products and the anticipated functions still need to be explored. The non-starch polysaccharides could be the central ingredients that contribute to the plant's antioxidant, hepatoprotective, hypoglycemic, lipid-regulating, and immunostimulatory properties. Of these, antioxidant and hepatoprotective effects have been thoroughly investigated. Procedures for the extraction and purification of polysaccharides influence their health-promoting actions. Overall, S. trifolia tuber is an underutilized aquatic vegetable species that is an emerging subject for nutraceutical research. © 2020 Society of Chemical Industry.

Food allergy severity predictions based on cellular in vitro tests

INTRODUCTION

Food allergy is increasing in prevalence and the severity of allergic reactions is unpredictable. Identifying food-allergic patients at high risk of severe reactions would allow us to offer a personalized and improved management for these patients.

AREAS COVERED

We review the evidence for using the levels of specific IgE, the nature of the allergen, and cellular tests to identify patients at high risk of developing severe allergic reactions to foods.

EXPERT OPINION

The evidence about whether the quantity of allergen-specific IgE reflects the severity of allergic reactions to foods is conflicting, with some positive and some negative studies. For some foods, specific IgE to individual components (e.g. Ara h 2 in peanut) can provide additional information. However, more important than the quantity of IgE is possibly the quality of IgE, which can be captured by individual measurements of affinity/avidity, diversity, and specific activity, but is best measured overall using the basophil and mast cell activation tests, which assess the function of IgE in its ability to induce cell activation, degranulation, and mediator release. Biomarkers look at a single aspect of the allergic response and should be interpreted in the broader clinical context for each individual patient assessed.

Dysregulation of TCTP in Biological Processes and Diseases

Translationally controlled tumor protein (TCTP), also called histamine releasing factor (HRF) or fortilin, is a multifunctional protein present in almost all eukaryotic organisms. TCTP is involved in a range of basic cell biological processes, such as promotion of growth and development, or cellular defense in response to biological stresses. Cellular TCTP levels are highly regulated in response to a variety of physiological signals, and regulatory mechanism at various levels have been elucidated. Given the importance of TCTP in maintaining cellular homeostasis, it is not surprising that dysregulation of this protein is associated with a range of disease processes. Here, we review recent progress that has been made in the characterisation of the basic biological functions of TCTP, in the description of mechanisms involved in regulating its cellular levels and in the understanding of dysregulation of TCTP, as it occurs in disease processes such as cancer.

AGK2 ameliorates mast cell-mediated allergic airway inflammation and fibrosis by inhibiting FcεRI/TGF-β signaling pathway

Asthma is characterized by airway hyperresponsiveness and allergic inflammation, detrimentally affecting the patients' quality of life. The development of new drugs for the treatment of asthma is warranted to alleviate these issues. Recent studies have demonstrated that sirtuin2 (SIRT2) aggravates asthmatic inflammation by up-regulation of T-helper type 2 responses and macrophage polarization. However, effects of SIRT2 on mast cell activation remain obscure. In this study, we investigated the effects of AGK2, an inhibitor for SIRT2, on mast cell-mediated allergic airway inflammation. Pre-treatment with AGK2 inhibited degranulation of mast cells by suppressing the FcεRI signaling pathway and intracellular calcium influx. The expression of pro-inflammatory cytokines, such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-4, IL-5, IL-6, and IL-8, was inhibited via regulation of transcription factors such as NF-κB and NRF2. These effects of AGK2 were verified in passive cutaneous anaphylaxis and acute lung injury animal models. AGK2 attenuated Evans blue pigmentation by inhibiting mast cell activation and lung barrier dysfunction by inhibiting inflammatory responses in these animal models. In the ovalbumin (OVA)-induced allergic airway inflammation murine model, AGK2 alleviated allergic asthma symptoms such as lung histological changes (immune cell and mast cell infiltration, collagen deposition, and α-smooth muscle actin expression) and serum immunoglobulins (Ig) levels (IgE, OVA-specific IgE, IgG1, and IgG2a). Moreover, AGK2 reduced the levels of pro-inflammatory cytokines (TNF-α, IL-1β, IL-4, IL-5, and IL-6) and inflammatory mediators (myeloperoxidase, eosinophil peroxidase, and tumor growth factor-α) in the bronchoalveolar lavage fluid and lung tissues. In addition, the anti-fibrotic effects of AGK2 were verified using lung epithelial cells and TGF-β/Smad reporter stable cells. In conclusion, our findings suggest that SIRT2 plays a role in mast cell-mediated airway inflammatory disease. Therefore, AGK2 is a good potential candidate for treating allergic asthma and lung inflammation.

Cynanchum atratum Ameliorates Airway Inflammation via Maintaining Alveolar Barrier and Regulating Mast Cell-Mediated Inflammatory Responses

Asthma is a common allergic airway inflammatory disease, characterized by abnormal breathing due to bronchial inflammation. Asthma aggravates the patient's quality of life and needs continuous pharmacological treatment. Therefore, discovery of drugs for the treatment of asthma is an important area of human health. The aim of the present study was to evaluate whether Cynanchum atratum extract (CAE) modulates the asthma-like allergic airway inflammation and to study its possible mechanism of action using ovalbumin (OVA)-induced airway inflammation and lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice, as well as a mast cell-based in vitro model. The histological analysis showed that CAE reduced the airway constriction and immune cell infiltration. CAE also inhibited release of β-hexosaminidase and expression of inflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-4, and IL-5 in bronchoalveolar lavage fluid and lung tissues. In addition, CAE reduced the OVA-specific immunoglobulin (Ig) E, total IgE, IgG1, and IgG2a levels in the serum. In the LPS-induced ALI model, CAE suppressed the LPS-induced lung barrier dysfunction and the release of proinflammatory cytokines. Because allergic airway inflammatory responses are associated with the activation of mast cells, RBL-2H3 cells were used to evaluate the underlying mechanism of CAE effects. In RBL-2H3 cells, CAE down-regulated release of β-hexosaminidase and histamine by reducing the intracellular calcium influx. In addition, CAE suppressed the expression of proinflammatory cytokines by inhibiting nuclear translocation of nuclear factor-κB. Taken together, our findings suggest that CAE may help in the prevention or treatment of airway inflammatory diseases.

TCTP from Loxosceles Intermedia (Brown Spider) Venom Contributes to the Allergic and Inflammatory Response of Cutaneous Loxoscelism

LiTCTP is a toxin from the Translationally Controlled Tumor Protein (TCTP) family identified in Loxosceles brown spider venoms. These proteins are known as histamine-releasing factors (HRF). TCTPs participate in allergic and anaphylactic reactions, which suggest their potential role as therapeutic targets. The histaminergic effect of TCTP is related to its pro-inflammatory functions. An initial characterization of LiTCTP in animal models showed that this toxin can increase the microvascular permeability of skin vessels and induce paw edema in a dose-dependent manner. We evaluated the role of LiTCTP in vitro and in vivo in the inflammatory and allergic aspects that undergo the biological responses observed in Loxoscelism, the clinical condition after an accident with Loxosceles spiders. Our results showed LiTCTP recombinant toxin (LiRecTCTP) as an essential synergistic factor for the dermonecrotic toxin actions (LiRecDT1, known as the main toxin in the pathophysiology of Loxoscelism), revealing its contribution to the exacerbated inflammatory response clinically observed in envenomated patients.

Dimerized, Not Monomeric, Translationally Controlled Tumor Protein Induces Basophil Activation and Mast Cell Degranulation in Chronic Urticaria

Translationally controlled tumor protein (TCTP) is also known as histamine releasing factor as it has the ability to activate mast cells. To investigate the role of TCTP in the pathogenesis of chronic spontaneous urticaria (CSU), we evaluated serum level of TCTP and effect of TCTP on basophil and mast cell degranulation. TCTP levels in the sera from 116 CSU patients and 70 normal healthy controls (NCs) were measured by ELISA. CD203c expression on basophils from CSU patients and β-hexosaminidase release from Laboratory of Allergic Disease 2 mast cells were measured upon stimulation monomeric and dimeric TCTP. Non-reducing Western blot analysis was used for detecting dimeric TCTP. No difference was observed in serum TCTP levels between CSU patients and NCs (p=0.676). However, dimeric TCTP intensity on Western blot was stronger in CSU patients than in NCs. TCTP levels were higher in patients with severe CSU (p=0.049) and with IgG positivity to FcɛRIα (p=0.038). A significant positive correlation was observed between TCTP and eosinophil cationic protein levels (Spearman's rho=0.341; p=0.001). Both basophil and mast cell degranulation were significantly increased after stimulation with dimeric TCTP, but not with monomic TCTP. The ability of TCTP to activate basophil and mast cells is dependent on dimerization, suggesting that the inhibition of TCTP dimerization can be a therapeutic option for CSU. Association between TCTP levels and the presence of IgG to high affinity Fc epsilon receptor I alpha subunit in CSU patients indicates that autoimmune mechanisms may be involved in the dimerization of TCTP.

Paeonol inhibits the development of 1‑chloro‑2,4‑dinitrobenzene‑induced atopic dermatitis via mast and T cells in BALB/c mice

Our previous studies suggested that paeonol, the active constituent of the traditional Chinese medicine Cortex Moutan, may be an effective treatment for inflammatory disorders. In the present study, the therapeutic potential of paeonol on atopic dermatitis (AD) was investigated using animal and cell experiments. AD‑like lesions were induced by repeated application of 1‑chloro‑2,4‑dinitrobenzene (DNCB) to the shaved dorsal skin of BALB/c mice, and P815 cells were used for in vitro assays. The skin lesions, serum and spleens of the mice were analyzed using lesion severity scoring, histological analysis, flow cytometry, reverse transcription‑quantitative polymerase chain reaction, western blotting and ELISA, in order to investigate the anti‑AD effects of paeonol. In addition, western blotting and ELISA were conducted for in vitro analysis of P815 cells. The results demonstrated that oral administration of paeonol inhibited the development of DNCB‑induced AD‑like lesions in the BALB/c mice by reducing severity of the lesions, epidermal thickness and mast cell infiltration; this was accompanied by reduced levels of immunoglobulin E and inflammatory cytokines [interleukin (IL)‑4, histamine, IL‑13, IL‑31 and thymic stromal lymphopoietin], along with regulation of the T helper (Th) cell subset (Th1/Th2) ratio. Application of paeonol also reduced the protein expression levels of phosphorylated (p)‑p38 and p‑extracellular signal‑regulated kinase (ERK) in skin lesions. In vitro, paeonol reduced the expression levels of tumor necrosis factor‑α and histamine in P815 cells, and inhibited p38/ERK/mitogen‑activated protein kinase signaling. The present findings indicated that paeonol may relieve dermatitis by acting on cluster of differentiation 4+ T and mast cells; therefore, paeonol may represent a potential therapeutic strategy for the treatment of allergic inflammatory conditions via immunoregulation.

Approaches to target IgE antibodies in allergic diseases

IgE is the antibody isotype found at the lowest concentration in the circulation. However IgE can undeniably play an important role in mediating allergic reactions; best exemplified by the clinical benefits of anti-IgE monoclonal antibody (omalizumab) therapy for some allergic diseases. This review will describe our current understanding of the interactions between IgE and its main receptors FcεRI and CD23 (FcεRII). We will review the known and potential functions of IgE in health and disease: in particular, its detrimental roles in allergic diseases and chronic spontaneous urticaria, and its protective functions in host defense against parasites and venoms. Finally, we will present an overview of the drugs that are in clinical development or have therapeutic potential for IgE-mediated allergic diseases.

The effect of PU.1 knockdown on gene expression and function of mast cells

PU.1 is a hematopoietic cell-specific transcription factor. In the current study, we investigated the role of PU.1 in the gene expression and the function of mouse mast cells (MCs) in vitro and in vivo. When PU.1 siRNA was introduced into bone marrow-derived MCs (BMMCs), IgE-mediated activation was reduced, and the Syk and FcεRIβ mRNA levels were significantly decreased. As the regulatory mechanism of the Syk gene is largely unknown, we performed promoter analysis and found that PU.1 transactivated the Syk promoter through direct binding to a cis-element in the 5′-untranslated region. The involvement of PU.1 in the Syk promoter was also observed in mouse dendritic cells and human MCs, suggesting that the relationship between PU.1 and Syk is common in mammals and in hematopoietic lineages. When antigen was administrated intravenously after the transfusion of siRNA-transfected BMMCs in the mouse footpad, the footpad thickening was significantly suppressed by PU.1 knockdown. Finally, administration of the immunomodulator pomalidomide suppressed passive systemic anaphylaxis of mice. Taken together, these results indicate that PU.1 knockdown might be an efficacious strategy for the prevention of MC-mediated allergic diseases.

Crystal structures of murine and human Histamine-Releasing Factor (HRF/TCTP) and a model for HRF dimerisation in mast cell activation

In allergic disease, mast cell activation is conventionally triggered by allergen-mediated cross-linking of receptor-bound IgE on the cell surface. In addition to its diverse range of intracellular roles in apoptosis, cell proliferation and cancer, Histamine-Releasing Factor (HRF) also activates mast cells and basophils. A subset of IgE antibodies bind HRF through their Fab regions, and two IgE binding sites on HRF have been mapped. HRF can form dimers, and a disulphide-linked dimer is critical for activity. The current model for the activity of HRF in mast cell activation involves cross-linking of receptor-bound IgE by dimeric HRF, mediated by HRF/Fab interactions. HRF crystal and solution structures have provided little insight into either the formation of disulphide-linked HRF dimers or the ability of HRF to activate mast cells. We report the first crystal structure of murine HRF (mHRF) to 4.0Å resolution, revealing a conserved fold. We also solved the structure of human HRF (hHRF) in two new crystal forms, one at the highest resolution (1.4Å) yet reported. The high resolution hHRF structure reveals a disulphide-linked dimer, in which the two molecules are closely associated, and provides a model for the role of both human and murine HRF in mast cell activation.

Histamine-releasing factor enhances food allergy

Food allergy occurs due to IgE- and mast cell-dependent intestinal inflammation. Previously, we showed that histamine-releasing factor (HRF), a multifunctional protein secreted during allergy, interacts with a subset of IgE molecules and that the HRF dimer activates mast cells in an HRF-reactive IgE-dependent manner. In this study, we investigated whether HRF plays any role in food allergy. Specifically, we determined that prophylactic and therapeutic administration of HRF inhibitors that block HRF-IgE interactions reduces the incidence of diarrhea and mastocytosis in a murine model of food allergy. Food allergy-associated intestinal inflammation was accompanied by increased secretion of the HRF dimer into the intestine in response to proinflammatory, Th2, and epithelial-derived cytokines and HRF-reactive IgE levels at the elicitation phase. Consistent with these data, patients with egg allergy had higher blood levels of HRF-reactive IgE compared with individuals that were not hypersensitive. Successful oral immunotherapy in egg-allergy patients and food-allergic mice reduced HRF-reactive IgE levels, thereby suggesting a pathological role for HRF in food allergy. Together, these results suggest that antigen and HRF dimer amplify intestinal inflammation by synergistically activating mast cells and indicate that HRF has potential as a therapeutic target in food allergy.

Histamine-releasing factor: a promising therapeutic target for food allergy

The prevalence of food allergies has been increasing at an alarming rate over the last few decades. Despite the dramatic increase in disease prevalence, the development of effective therapies has not kept pace. In this issue of the JCI, Ando et al. provide a causal link between histamine-releasing factor (HRF) interactions with IgE and food allergy in a murine model. Successful oral immunotherapy of both egg-allergic human patients and food-allergic mice was associated with sustained suppression of HRF-reactive IgE levels. These results support a role for HRF-IgE interactions in the amplification of intestinal inflammation and suggest HRF as a therapeutic target in food allergy.

Histamine Release from Mast Cells and Basophils

Mast cells and basophils represent the most relevant source of histamine in the immune system. Histamine is stored in cytoplasmic granules along with other amines (e.g., serotonin), proteases, proteoglycans, cytokines/chemokines, and angiogenic factors and rapidly released upon triggering with a variety of stimuli. Moreover, mast cell and basophil histamine release is regulated by several activating and inhibitory receptors. The engagement of different receptors can trigger different modalities of histamine release and degranulation. Histamine released from mast cells and basophils exerts its biological activities by activating four G protein-coupled receptors, namely H1R, H2R, H3R (expressed mainly in the brain), and the recently identified H4R. While H1R and H2R activation accounts mainly for some mast cell- and basophil-mediated allergic disorders, the selective expression of H4R on immune cells is uncovering new roles for histamine (possibly derived from mast cells and basophils) in allergic, inflammatory, and autoimmune disorders. Thus, the in-depth knowledge of mast cell and basophil histamine release and its biologic effects is poised to uncover new therapeutic avenues for a wide spectrum of disorders.

Fortilin: A Potential Target for the Prevention and Treatment of Human Diseases

Fortilin is a highly conserved 172-amino-acid polypeptide found in the cytosol, nucleus, mitochondria, extracellular space, and circulating blood. It is a multifunctional protein that protects cells against apoptosis, promotes cell growth and cell cycle progression, binds calcium (Ca²⁺) and has antipathogen activities. Its role in the pathogenesis of human and animal diseases is also diverse. Fortilin facilitates the development of atherosclerosis, contributes to both systemic and pulmonary arterial hypertension, participates in the development of cancers, and worsens diabetic nephropathy. It is important for the adaptive expansion of pancreatic β-cells in response to obesity and increased insulin requirement, for the regeneration of liver after hepatectomy, and for protection of the liver against alcohol- and ER stress-induced injury. Fortilin is a viable surrogate marker for in vivo apoptosis, and it plays a key role in embryo and organ development in vertebrates. In fish and shrimp, fortilin participates in host defense against bacterial and viral pathogens. Further translational research could prove fortilin to be a viable molecular target for treatment of various human diseases including and not limited to atherosclerosis, hypertension, certain tumors, diabetes mellitus, diabetic nephropathy, hepatic injury, and aberrant immunity and host defense.

Fifty years later: Emerging functions of IgE antibodies in host defense, immune regulation, and allergic diseases

Fifty years ago, after a long search, IgE emerged as the circulating factor responsible for triggering allergic reactions. Its extremely low concentration in plasma created significant hurdles for scientists working to reveal its identity. We now know that IgE levels are invariably increased in patients affected by atopic conditions and that IgE provides the critical link between the antigen recognition role of the adaptive immune system and the effector functions of mast cells and basophils at mucosal and cutaneous sites of environmental exposure. This review discusses the established mechanisms of action of IgE in pathologic immediate hypersensitivity, as well as its multifaceted roles in protective immunity, control of mast cell homeostasis, and its more recently revealed immunomodulatory functions.

Relación de los mecanismos inmunológicos del asma y la contaminación ambiental

Introducción. Se calcula que más de 300 millones de personas alrededor del mundo padecen asma y se estima que para el año 2025 esta cifra se incremente a 400 millones debido a los contaminantes criterio. Sin embargo, dadas sus limitaciones, los estudios epidemiológicos son controversiales sobre la contaminación y el desarrollo de asma.Objetivos. Describir las diferencias y similitudes de la respuesta inmunológica de pacientes asmáticos y los modelos animales de asma alérgica después de la exposición a contaminantes criterio y elementos biológicos, para así identificar los factores inmunológicos relacionados con el desarrollo de asma.Materiales y método. Se realizó una búsqueda sistemática en las bases de datos sobre asma y los diferentes contaminantes criterio.Resultados. La respuesta Th2 es activada por la inhalación de ozono, dióxido de nitrógeno, azufre y la exposición aguda a material particulado, mientras que el contacto con ciertos tipos de pólenes y glucanos y la exposición crónica de partículas incrementa la respuesta Th1, la cual inhibe a la respuesta Th2 produciendo un “efecto protector”.Conclusiones. La respuesta Th1 podría causar baja o nula asociación entre la exposición a contaminación y el desarrollo de asma en las diferentes ciudades, adicionando de esta manera otra limitación a los estudios epidemiológicos.

Structural Insights into TCTP and Its Interactions with Ligands and Proteins

The 19-24 kDa Translationally Controlled Tumor Protein (TCTP) is involved in a wide range of molecular interactions with biological and nonbiological partners of various chemical compositions such as proteins, peptides, nucleic acids, carbohydrates, or small molecules. TCTP is therefore an important and versatile binding platform. Many of these protein-protein interactions have been validated, albeit only few received an in-depth structural characterization. In this chapter, we will focus on the structural analysis of TCTP and we will review the available literature regarding its interaction network from a structural perspective.

2-Hydroxy-3-methoxybenzoic acid attenuates mast cell-mediated allergic reaction in mice via modulation of the FcεRI signaling pathway

Mast cells are important effector cells in immunoglobulin (Ig) E-mediated allergic reactions such as asthma, atopic dermatitis and rhinitis. Vanillic acid, a natural product, has shown anti-oxidant and anti-inflammatory activities. In the present study, we investigated the anti-allergic inflammatory effects of ortho-vanillic acid (2-hydroxy-3-methoxybenzoic acid, o-VA) that was a derivative of vanillic acid isolated from Amomum xanthioides. In mouse anaphylaxis models, oral administration of o-VA (2, 10, 50 mg/kg) dose-dependently attenuated ovalbumin-induced active systemic anaphylaxis and IgE-mediated cutaneous allergic reactions such as hypothermia, histamine release, IgE production and vasodilation; administration of o-VA also suppressed the mast cell degranulator compound 48/80-induced anaphylaxis. In cultured mast cell line RBL-2H3 and isolated rat peritoneal mast cells in vitro, pretreatment with o-VA (1-100 μmol/L) dose-dependently inhibited DNP-HSA-induced degranulation of mast cells by decreasing the intracellular free calcium level, and suppressed the expression of pro-inflammatory cytokines TNF-α and IL-4. Pretreatment of RBL-2H3 cells with o-VA suppressed DNP-HSA-induced phosphorylation of Lyn, Syk, Akt, and the nuclear translocation of nuclear factor-κB. In conclusion, o-VA suppresses the mast cell-mediated allergic inflammatory response by blocking the signaling pathways downstream of high affinity IgE receptor (FcεRI) on the surface of mast cells.

Probiotics enhance the effect of allergy immunotherapy on regulating antigen specific B cell activity in asthma patients

Immune regulatory system dysfunction plays a role in the pathogenesis of asthma. The therapeutic effect of allergic asthma is to be improved. The immune regulatory function of probiotics has been recognized. This study tests a hypothesis that Clostridium butyricum (CB) enhances the effect of allergen specific immunotherapy (AIT) on asthma. In this study patients with allergic asthma were treated with AIT or/and CB for six months. The therapeutic effect and IgE production of the patients were observed. The results showed that administration with AIT alone alleviated the asthma symptoms; but the serum levels of interleukin (IL)-4, IL-5, IL-13 and specific IgE were not altered, which was markedly improved by the administration with CB plus AIT. Such effects were maintained only for two months in the patients treated with AIT alone; but maintained more than 12 months in those patients treated with both AIT and CB. CB facilitated AIT to induce IL-10⁺ B cells (B10 cells) in asthma patients. AIT/CB therapy converted antigen specific B cells to antigen specific regulatory B cells. Butyrate modulated the gene transcription of IgE and IL-10 in the allergen specific B cells. In conclusion, administration of CB can enhance the therapeutic effect of AIT in the treatment of allergic asthma via facilitating generation of B10 cells.

From IgE to Omalizumab

IgE is the least abundant Ig isotype, yet it plays a critical role in allergic reactions and host protection from helminth infection. Although IgE was discovered 50 years ago, the ultimate evidence for its role in human allergic diseases was obtained by the efficacy of anti-IgE therapy in many clinical trials on asthma and other allergic diseases. Beginning from the discovery of IgE 50 y ago, followed by studies of IgE receptors and activation mechanisms, this review provides a historic perspective of allergy research that has led to the development of anti-IgE therapy and other strategies targeting IgE and its receptors. Current IgE studies toward future precision medicine are also reviewed.

What we know about nonsteroidal anti-inflammatory drug hypersensitivity

Nonsteroidal anti-inf lammatory drugs (NSAIDs) are widely prescribed for the treatment of inflammatory diseases, but their use is frequently related to hypersensitivity reactions. This review outlines our current knowledge of NSAID hypersensitivity (NHS) with regard to its pathogenic, molecular, and genetic mechanisms, as well as diagnosis and treatment. The presentation of NHS varies from a local (skin and/or airways) reaction to systemic reactions, including anaphylaxis. At the molecular level, NHS reactions can be classified as cross-reactive (mediated by cyclooxygenase inhibition) or selective (specific activation of immunoglobulin E antibodies or T cells). Genetic polymorphisms and epigenetic factors have been shown to be closely associated with NHS, and may be useful as predictive markers. To diagnose NHS, inhalation or oral challenge tests are applied, with the exclusion of any cross-reactive NSAIDs. For patients diagnosed with NHS, absolute avoidance of NSAIDs/aspirin is essential, and pharmacological treatment, including biologics, is often used to control their respiratory and cutaneous symptoms. Finally, desensitization is recommended only for selected patients with NHS. However, further research is required to develop new diagnostic methods and more effective treatments against NHS.

Prognostic Factors for Chronic Spontaneous Urticaria: A 6-Month Prospective Observational Study

Purpose

Chronic urticaria (CU) has a substantial impact on the quality of life. Little clinical data on the prognosis of CU has been reported. This study aimed to investigate the control status and remission rate of CU and to explore potential predictors of good responses to the treatment during a 6-month treatment period.

Methods

A total of 75 patients with chronic spontaneous urticaria (CSU) were enrolled from 3 university hospitals in Korea. Urticaria control state was classified into 2 groups: group I (remission and well-controlled) and group II (partly and uncontrolled). CU-specific quality of life (CU-QoL) and the urticaria activity score (UAS) were measured before and after the treatment. Autologous serum skin test (ASST), and anti-nuclear and anti-thyroid antibodies were measured at the enrollment into the study. Aspirin intolerance was confirmed by an oral provocation test.

Results

Of 59 patients completing the study, 21 (35.6%) arrived at well-controlled status and only 2 (3.4%) achieved remission, whereas 26 (44.1%) remained at partly controlled status and 10 (16.9%) were at uncontrolled status. Mean changes in CU-QoL (36.5±2.7 vs 20.6±4.3, P=0.017) and UAS (-7.9±0.8 vs -3.0±1.0, P=0.001) were significantly different between groups I and II. The presence of serum autoantibodies and aspirin intolerance had no influence on the control of urticaria in this study. However, ASST positivity was identified as a significant predictor of CU control in multivariate analysis (OR=6.106, P=0.017).

Conclusions

The proportion of CSU patients that achieved remission or a well-controlled state was 39% for the 6 months of stepwise treatment. Longer observations are necessary to assess the exact prognosis of CSU. ASST results may be a useful parameter for predicting a better response to treatment and both UAS and CU-QoL are helpful to monitor therapeutic response.

Androctonus australis hector venom contributes to the interaction between neuropeptides and mast cells in pulmonary hyperresponsiveness

Lung injury and respiratory distress syndrome are frequent symptoms observed in the most severe cases of scorpion envenomation. The uncontrolled transmigration of leukocyte cells into the lung interstitium and alveolar space and pulmonary edema may be the cause of death. Mast cells can release various inflammatory mediators known to be involved in the development of lung edema following scorpion venom injection. The present study was designed to determine the evidence of neurokinin 1 (NK1) receptor and the involvement of mast cell activation to induce pulmonary edema and to increase vascular permeability after Androctonus australis hector (Aah) venom administration. To this end, mast cells were depleted using compound 48/80 (C48/80). Furthermore, the involvement of tachykinin NK1 receptors expressed on mast cell membranes was elucidated by their blocking with an antagonist. On the other hand, the ability of Aah venom to increase vascular permeability and to induce edema was also assessed by measuring the amount of Evans blue dye (EBD) extravasation in bronchoalveolar lavage (BAL) fluid and in the lungs of mice. Pulmonary edema, as assessed by the levels of EBD extravasation, was completely inhibited in compound 48/80-treated animals. Depletion by stimuli non-immunological C48/80 component markedly reduced induced inflammatory response following the venom administration. The mast cells seem to play an important role in the development of lung injury and the increase of vascular permeability in mice following the subcutaneous administration of Aah scorpion venom through the NK1 receptor.

Key mediators in the immunopathogenesis of allergic asthma

Asthma is described as a chronic inflammatory disorder of the conducting airways. It is characterized by reversible airway obstruction, eosinophil and Th2 infiltration, airway hyper-responsiveness and airway remodeling. Our findings to date have largely been dependent on work done using animal models, which have been instrumental in broadening our understanding of the mechanism of the disease. However, using animals to model a uniquely human disease is not without its drawbacks. This review aims to examine some of the key mediators and cells of allergic asthma learned from animal models and shed some light on emerging mediators in the pathogenesis allergic airway inflammation in acute and chronic asthma.