Emerging concepts: mast cell involvement in allergic diseases

Diagnostic and prognostic significance of mast cell markers in HIV/AIDS: Current insights and future directions

Human immunodeficiency virus (HIV) infection continues to pose significant global health challenges, necessitating advancements in diagnostic and prognostic approaches to optimize disease management. While primarily recognized for their roles in allergic responses, mast cells have emerged as potential markers with diagnostic and prognostic significance in the context of HIV/AIDS. This paper aims to synthesize current insights and delineate future directions regarding the utility of mast cell markers in diagnosing HIV infection, predicting disease progression, and guiding therapeutic strategies. Mast cells, equipped with distinct markers such as tryptase, chymase, carboxypeptidase A3, and c-kit/CD117 receptors, exhibit tissue-specific expression patterns that offer potential as diagnostic indicators for HIV infection. Understanding the dynamics of these markers in different tissues and body fluids holds promise for accurate HIV diagnosis, disease staging, and monitoring treatment responses. Moreover, the prognostic significance of mast cell markers in HIV/AIDS lies in their potential to predict disease progression, immune dysregulation, and clinical outcomes. The integration of mast cell markers into clinical applications offers promising avenues for refining diagnostic assays, patient monitoring protocols, and therapeutic strategies in HIV/AIDS. Future research directions involve the development of novel diagnostic tools and targeted therapies based on mast cell-specific markers, potentially revolutionizing clinical practice and enhancing patient care in the management of HIV/AIDS. Continued investigations into mast cell markers' diagnostic and prognostic implications hold immense potential to advance our understanding and improve outcomes in HIV/AIDS management.

Intranasal Morphology Transformation Nanomedicines for Long-Term Intervention of Allergic Rhinitis

Intranasal administration has been widely explored as a potential treatment for allergic rhinitis, and improving intranasal penetration and retention of drugs is a challenging requirement to further improve efficacy. Delivery strategies of nanocarriers that enhance mucosal adhesion or mucus penetration have been proposed to improve nasal drug delivery; however, delivery efficiency remains limited by excessive pulmonary deposition and nonspecific cell phagocytosis. In this work, a "nasal in situ assembly" strategy was presented to construct intranasal morphology transformation nanomedicines with enhanced effective drug concentration for long-term intervention of allergic rhinitis. The polymer-polypeptide nanomedicine (PHCK) with a CCR3 antagonistic peptide (C) and a pH-responsive polyethylene glycol (H) was developed, encapsulating ketotifen (KT). PHCK nanoparticles displayed nasal mucosa permeability and transformed to nanofibers in the acidic environment of the nasal cavity, realizing responsive burst release of KT simultaneously. The fibrotic reassembly reduced the cellular internalization of nanomedicine and increased the CCR3 blockade on the eosinophil (EOS) membranes. Both in vitro and in vivo data indicated that PHCK achieved improved drug accumulation and retention in the nasal cavity and decreased pulmonary deposition, then effectively inhibited mast cell degranulation and EOS chemotaxis. This study demonstrates that the "nasal in situ assembly" strategy can improve drug delivery efficiency upon nasal responsive morphologic transformation, providing exploratory perspectives for nasal delivery platforms establishment and boosting therapeutic effect of allergic rhinitis.

The Role of Immune Cells in the Pathogenesis of Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a devastating disease of unknown etiology with limited treatment options. The role of the immune system in IPF has received increasing attention. Uncontrolled immune responses drive the onset and progression of IPF. This article provides an overview of the role of innate immune cells (including macrophages, neutrophils, mast cells, eosinophils, dendritic cells, nature killer cells, nature kill cells and γδ T cells) and adaptive immune cells (including Th1 cells, Th2 cells, Th9 cells, Th17 cells, Th22 cells, cytotoxic T cells, B lymphocytes and Treg cells) in IPF. In addition, we review the current status of pharmacological treatments for IPF and new developments in immunotherapy. A deeper comprehension of the immune system's function in IPF may contribute to the development of targeted immunomodulatory therapies that can alter the course of the disease.

CKBA suppresses mast cell activation via ERK signaling pathway in murine atopic dermatitis

Atopic dermatitis (AD) is a common inflammatory skin disorder. Mast cells play an important role in AD because they regulate allergic reactions and inflammatory responses. However, whether and how the modulation of mast cell activity affects AD has not been determined. In this study, we aimed to determine the effects and mechanisms of 3-O-cyclohexanecarbonyl-11-keto-β-boswellic acid (CKBA). This natural compound derivative alleviates skin inflammation by inhibiting mast cell activation and maintaining skin barrier homeostasis in AD. CKBA markedly reduced serum IgE levels and alleviated skin inflammation in calcipotriol (MC903)-induced AD mouse model. CKBA also restrained mast cell degranulation both in vitro and in vivo. RNA-seq analysis revealed that CKBA downregulated the extracellular signal-regulated kinase (ERK) signaling in BM-derived mast cells activated by anti-2,4-dinitrophenol/2,4-dinitrophenol-human serum albumin. We proved that CKBA suppressed mast cell activation via ERK signaling using the ERK activator (t-butyl hydroquinone) and inhibitor (selumetinib; AZD6244) in AD. Thus, CKBA suppressed mast cell activation in AD via the ERK signaling pathway and could be a therapeutic candidate drug for AD.

Discovery of a traditional Chinese herbal combination for the treatment of atopic dermatitis: saposhnikoviae radix, astragali radix and cnidium monnieri

Atopic dermatitis (AD) is a skin disease characterized by pruritus. The present study aimed to discover a herbal combination with anti-allergic and anti-inflammatory activities to treat AD. First, the anti-allergic and anti-inflammatory activities of herbs were evaluated by RBL-2H3 degranulation and HaCaT inflammatory models. Subsequently, the optimal proportion of herbs was determined by uniform design-response surface methodology. The effectiveness and synergistic mechanism was further verified. Cnidium monnieri (CM) suppressed β-hexosaminidase (β-HEX) release, saposhnikoviae radix (SR), astragali radix (AR), and CM inhibited the release of IL-8 and MCP-1. The optimal proportion of herbs was SR∶AR∶CM = 1: 2: 1. The in vivo experiments results indicated that the topical application of combination at high (2 ×) and low (1 ×) doses improved dermatitis score and epidermal thickness, and attenuated mast cell infiltration. Network pharmacology and molecular biology further clarified that the combination resisted AD by regulating the MAPK, JAK signaling pathways, and the downstream cytokines such as IL-6, IL-1β, IL-8, IL-10, and MCP-1. Overall, the herbal combination could inhibit inflammation and allergy, improving AD-like symptoms. The present study discovers a promising herbal combination, worthy of further development as a therapeutic drug for AD.

Molecular Mechanisms of Neurogenic Inflammation of the Skin

The skin, including the hypodermis, is the largest body organ and is in constant contact with the environment. Neurogenic inflammation is the result of the activity of nerve endings and mediators (neuropeptides secreted by nerve endings in the development of the inflammatory reaction in the skin), as well as interactions with other cells such as keratinocytes, Langerhans cells, endothelial cells and mast cells. The activation of TRPV-ion channels results in an increase in calcitonin gene-related peptide (CGRP) and substance P, induces the release of other pro-inflammatory mediators and contributes to the maintenance of cutaneous neurogenic inflammation (CNI) in diseases such as psoriasis, atopic dermatitis, prurigo and rosacea. Immune cells present in the skin (mononuclear cells, dendritic cells and mast cells) also express TRPV1, and their activation directly affects their function. The activation of TRPV1 channels mediates communication between sensory nerve endings and skin immune cells, increasing the release of inflammatory mediators (cytokines and neuropeptides). Understanding the molecular mechanisms underlying the generation, activation and modulation of neuropeptide and neurotransmitter receptors in cutaneous cells can aid in the development of effective treatments for inflammatory skin disorders.

Bicalutamide, an androgen receptor antagonist, effectively alleviate allergic rhinitis via suppression of PI3K-PKB activity

OBJECTIVES

To investigate the therapeutic effect of Bicalutamide, an androgen receptor antagonist on the onset and development of allergic rhinitis in an animal model.

METHODS

40 male BALB/c mice were randomly divided into five groups (eight mice per group). Aluminum hydroxide powder was used as an adjuvant, combined with Ovalbumin (OVA) to establish the mouse model of allergic rhinitis via ultrasonic nebulization of OVA to stimulate the nasal cavity. Mice in Bica#1 group were intraperitoneally injected with 0.02 mg Bicalutamide/0.5 ml of normal saline daily for 7 consecutive days; mice in Bica#2 group were administered 0.02 mg Bicalutamide/0.5 ml of normal saline via intraperitoneal injection for 5 consecutive days, and then the same amount of normal saline was injected intraperitoneally for 2 consecutive days. Enzyme-linked immunosorbent assay was adopted to detect the serological levels of IgE, IL-4, and IL-6 production. Eosinophil infiltration was observed under microscope after hematoxylin and eosin staining of nasal mucosa. Quantitative PCR and Western blot were employed for determination of histamine receptors mRNA expression and PI3K/PKB associated protein levels, respectively.

RESULTS

Histological analysis shown that allergic lesion was induced after OVA sensitization. Intraperitoneal injection with 0.02 mg Bicalutamide daily for 7 consecutive days significantly reduced the allergic lesion; however, mice injected with the same amount of normal saline at the same time demonstrated no allergic rhinitis symptoms. In addition, there was a significant reduction in eosinophils number in Bicalutamide treated mice (n = 8) compared to the OVA group (n = 8) (OVA: 19.6 ± 5.3 vs. Bica#1: 7.7 ± 0.8 vs. Bica#2: 9.4 ± 1.2, both p < 0.01). Furthermore, ELISA results revealed that the serological levels of IgE (OVA: 17.3 ± 1.7 µg/ml vs. Bica#1: 9.2 ± 0.6 vs. Bica#2: 10.4 ± 2.3, both p < 0.05), IL-4 (OVA: 164.3 ± 5.1 pg/ml vs. Bica#1: 110.2 ± 3.1 vs. Bica#2: 115.3 ± 4.1, both p < 0.05) and IL-6 (OVA: 167.3 ± 3.7 pg/ml vs. Bica#1: 117.5 ± 6.5 vs. Bica#2: 114.8 ± 2.4, both p < 0.05) were significantly decreased after two different dosage of Bicalutamide treatment. Similarly, histamine receptors in mast cells were significantly reduced after two different dosage of Bicalutamide treatment. More importantly, p-PKB protein was notably reduced after two different dosage of Bicalutamide treatment compared to the OVA group, mTOR protein levels were also down regulated after two different dosage of Bicalutamide treatment.

CONCLUSIONS

Our data demonstrated that androgen receptor antagonist Bicalutamide can significantly alleviate allergic rhinitis lesion in the animal model. PI3K/PKB activity in mast cells was suppressed after Bicalutamide injection. Our results provide important implication in allergic rhinitis prevention and treatment.

Cannabinoid receptors in the inflammatory cells of canine atopic dermatitis

Background

Atopic dermatitis (AD) is one of the most common cutaneous inflammatory and pruritic diseases in dogs. Considering its multifactorial nature, AD can be a challenging disease to manage, and the therapeutic strategy must often be multimodal. In recent years, research has been moving toward the use of natural products which have beneficial effects on inflammation and itching, and no side effects. Cannabinoid receptors have been demonstrated to be expressed in healthy and diseased skin; therefore, one of the potential alternative therapeutic targets for investigating AD is the endocannabinoid system (ECS).

Objective

To immunohistochemically investigate the expression of the cannabinoid receptor type 2 (CB2R), and the cannabinoid-related receptors G protein-coupled receptor 55 (GPR55), transient receptor potential vanilloid 1 (TRPV1) and ankyrin 1 (TRPA1) in mast cells (MCs), macrophages, dendritic cells (DCs), T cells, and neutrophils of the skin of dogs with AD.

Animals

Samples of skin tissues were collected from eight dogs with AD (AD-dogs).

Materials and methods

The immunofluorescent stained cryosections of the skins of 8 dogs with AD having antibodies against CB2R, GPR55, TRPV1, TRPA1 were semiquantitatively evaluated. The inflammatory cells were identified using antibodies against tryptase (mast cells), ionized calcium binding adaptor molecule 1 (IBA1) (macrophages/DCs), CD3 (T cells), and calprotectin (neutrophils). The proportions of MCs, macrophages/DCs, T cells, and neutrophils expressing CB2R, GPR55, TRPV1 and TRPA1 were evaluated.

Results

The cells of the inflammatory infiltrate showed immunoreactivity (IR) for all or for some of the cannabinoid and cannabinoid-related receptors studied. In particular, MCs and macrophages/DCs showed CB2R-, GPR55-, TRPA1-, and TRPV1-IR; T cells showed CB2R-, GPR55- and TRPA1-IR, and neutrophils expressed GPR55-IR. Co-localization studies indicated that CB2R-IR was co-expressed with TRPV1-, TRPA1-, and GPR55-IR in different cellular elements of the dermis of the AD-dogs.

Conclusions and clinical importance

Cannabinoid receptor 2, and cannabinoid-related receptors GPR55, TRPV1 and TRPA1 were widely expressed in the inflammatory infiltrate of the AD-dogs. Based on the present findings, the ECS could be considered to be a potential therapeutic target for dogs with AD, and may mitigate itch and inflammation.

Trifuhalol A Suppresses Allergic Inflammation through Dual Inhibition of TAK1 and MK2 Mediated by IgE and IL-33

The activation and degranulation of immune cells play a pivotal role in allergic inflammation, a pathological condition that includes anaphylaxis, pruritus, and allergic march-related diseases. In this study, trifuhalol A, a phlorotannin isolated from Agarum cribrosum, inhibited the degranulation of immune cells and the biosynthesis of IL-33 and IgE in differentiated B cells and keratinocytes, respectively. Additionally, trifuhalol A suppressed the IL-33 and IgE-mediated activation of RBL-2H3 cells through the regulation of the TAK1 and MK2 pathways. Hence, the effect of trifuhalol A on allergic inflammation was evaluated using a Compound 48/80-induced systemic anaphylaxis mouse model and a house dust mite (HDM)-induced atopic dermatitis (AD) mouse model. Trifuhalol A alleviated anaphylactic death and pruritus, which appeared as an early-phase reaction to allergic inflammation in the Compound 48/80-induced systemic anaphylaxis model. In addition, trifuhalol A improved symptoms such as itching, edema, erythema, and hyperkeratinization in HDM-induced AD mice as a late-phase reaction. Moreover, the expression of IL-33 and thymic stromal lymphopoietin, inflammatory cytokines secreted from activated keratinocytes, was significantly reduced by trifuhalol A administration, resulting in the reduced infiltration of immune cells into the skin and a reduction in the blood levels of IgE and IL-4. In summarizing the above results, these results confirm that trifuhalol A is a potential therapeutic candidate for the regulation of allergic inflammation.

Angelica Yinzi alleviates 1-chloro-2,4-dinitrobenzene-induced atopic dermatitis by inhibiting activation of NLRP3 inflammasome and down-regulating the MAPKs/NF-kB signaling pathway

Background

Atopic dermatitis (AD), characterized by eczema as a chronic pruritic inflammatory skin disease, has become a serious health problem with recurrent clinical episodes. However, current clinical treatments have limited relief and are accompanied by adverse effects. Therefore, there is a necessity to develop new effective drugs for AD treatment. Angelica Yinzi (AYZ) is a classic ancient prescription for nourishing blood, moistening dryness, dispelling wind, and relieving itching. However, its mechanism for alleviating atopic dermatitis remains unknown. Therefore, this study aimed at determining the effects of AYZ and its potential mechanism in alleviating AD-like symptoms.

Methods

In the present study, we used 1-chloro-2,4-dinitrobenzene (DNCB) to establish a mouse model of atopic dermatitis, where DNCB readily penetrates the epidermis to cause inflammation. Histopathological analysis was performed to examine the thickening of dorsal skin and infiltration in the inflammatory and mast cells in C57BL/6 mice. Additionally, the immunoglobulin E (IgE) levels in serum were determined by enzyme-linked immunosorbent assay (ELISA) kits. The IL-1β and TNF-α expression were detected using qRT-PCR. Next, the Western blotting and immunohistochemistry assays were performed to assess the contribution of MAPKs/NF-κB signaling pathways and the NLRP3 inflammasome in AD responses.

Results

Histopathological examination revealed that AYZ reduced the epidermal thickness of AD-like lesioned skin and repressed the infiltration of mast cells into AD-like lesioned skin. AYZ significantly decreased the phosphorylation of p38 MAPK, JNK, ERK and NF-κB and downregulated serum IgE levels and IL-1β and TNF-α mRNA levels. Additionally, the NLRP3, ASC, Caspase-1, and IL-1β expression in dorsal skin were effectively down-regulated following AYZ treatment (p < 0.05 and p < 0.01).

Conclusion

These findings revealed that AYZ effectively suppressed AD-induced skin inflammation by inhibiting the activation of the NLRP3 inflammasome and the MAPKs/NF-kB signaling. Therefore, AYZ is a potential therapeutic agent against AD in the clinical setting.

Terpenes and terpenoids as main bioactive compounds of essential oils, their roles in human health and potential application as natural food preservatives

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Terpenes and terpenoids are the main bioactive compounds of essential oils (EOs).

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EOs and their major constituents confer several biological activities.

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EOs are potential as natural food preservatives.

Essential oils (EOs) are volatile and concentrated liquids extracted from different parts of plants. Bioactive compounds found in EOs, especially terpenes and terpenoids possess a wide range of biological activities including anticancer, antimicrobial, anti-inflammatory, antioxidant, and antiallergic. Available literature confirms that EOs exhibit antimicrobial and food preservative properties that are considered as a real potential application in food industry. Hence, the purpose of this review is to present an overview of current knowledge of EOs for application in pharmaceutical and medical industries as well as their potential as food preservatives in food industry.

1-Iodohexadecane Alleviates 2,4-Dinitrochlorobenzene-Induced Atopic Dermatitis in Mice: Possible Involvements of the Skin Barrier and Mast Cell SNARE Proteins

Atopic dermatitis (AD) is a chronic inflammatory dermal disease with symptoms that include inflammation, itching, and dry skin. 1-Iodohexadecane is known as a component of Chrysanthemum boreale essential oil that has an inhibitory effect on AD-like lesions. However, its effects on AD-related pathological events have not been investigated. Here, we explored the effects of 1-iodohexadecane on AD lesion-related in vitro and in vivo responses and the mechanism involved using human keratinocytes (HaCaT cells), mast cells (RBL-2H3 cells), and a 2,4-dinitrochlorobenzene (DNCB)-induced mouse model (male BALB/c) of AD. Protein analyses were performed by immunoblotting or immunohistochemistry. In RBL-2H3 cells, 1-iodohexadecane inhibited immunoglobulin E-induced releases of histamine and β-hexosaminidase and the expression of VAMP8 protein (vesicle-associated membrane proteins 8; a soluble N-ethylmaleimide-sensitive factor attachment protein receptor [SNARE] protein). In HaCaT cells, 1-iodohexadecane enhanced filaggrin and loricrin expressions; in DNCB-treated mice, it improved AD-like skin lesions, reduced epidermal thickness, mast cell infiltration, and increased filaggrin and loricrin expressions (skin barrier proteins). In addition, 1-iodohexadecane reduced the β-hexosaminidase level in the serum of DNCB-applied mice. These results suggest that 1-iodohexadecane may ameliorate AD lesion severity by disrupting SNARE protein-linked degranulation and/or by enhancing the expressions of skin barrier-related proteins, and that 1-iodohexadecane has therapeutic potential for the treatment of AD.

Dendritic cell immunoreceptor drives atopic dermatitis by modulating oxidized CaMKII-involved mast cell activation

Allergens have been identified as potential triggers in patients with atopic dermatitis (AD). AD patients are highly sensitive to cockroach allergen. The underlying mechanism, however, remains undetermined. Here, we established a cockroach allergen-induced AD-like mouse model and demonstrated that repeated exposure to cockroach allergen led to aggravated mouse skin inflammation, characterized by increased type 2 immunity, type 2 innate lymphoid cells (ILC2s), and mast cells. Increased skin mast cells were also observed in AD patients. AD mice with mast cell-deficient mice (kitW-sh/W-sh) showed diminished skin inflammation, suggesting that mast cells are required in allergen-induced skin inflammation. Furthermore, dendritic cell immuno-receptor (DCIR) is up-regulated in skin mast cells of AD patients and mediates allergen binding and uptake. DCIR-/- mice or reconstituted kitW-sh/W-sh mice with DCIR-/- mast cells showed a significant reduction in AD-like inflammation. Both in vitro and in vivo analyses demonstrated that DCIR-/- mast cells had reduced IgE-mediated mast cell activation and passive cutaneous anaphylaxis. Mechanistically, DCIR regulates allergen-induced IgE-mediated mast cell ROS generation and oxidation of calmodulin kinase II (ox-CaMKII). ROS-resistant CaMKII (MM-VVδ) prevents allergen-induced mast cell activation and inflammatory mediator release. Our study reveals a previously unrecognized DCIR-ROS-CaMKII axis that controls allergen-induced mast cell activation and AD-like inflammation.

MrgprX2 regulates mast cell degranulation through PI3K/AKT and PLCγ signaling in pseudo-allergic reactions

The G protein-coupled receptor MrgprX2 in mast cells is known to be a crucial receptor for pseudo-allergic reactions. MrgprX2 activation leads to elevated intracellular calcium levels and mast cell degranulation, but the underlying mechanism remains to be elucidated. Herein, we investigated the role of the phosphatidylinositol 3 kinase (PI3K)/serum-threonine kinase (AKT) signaling pathway and phospholipase C gamma (PLCγ) in mast cell degranulation mediated by MrgprX2 in LAD2 human-derived mast cells. The results showed that phosphorylated AKT (p-AKT) and PLCγ up-regulation were accompanied by an increase in intracellular calcium following activation of MrgprX2 by Compound 48/80, an inducer of mast cell degranulation. In contrast, p-AKT and PLCγ were down-regulated and intracellular calcium levels decreased after MrgprX2 knockdown. Mast cell degranulation was clearly suppressed; however, inhibiting PI3K and PLCγ phosphorylation did not influence MrgprX2 expression. The increase in calcium concentration was suppressed and mast cell degranulation was weakened. Furthermore, by inhibiting PI3K and PLCγ phosphorylation in animals, the allergic symptoms caused by C48/80 were obviously reduced. We deduced that during the mast cell degranulation observed in pseudoallergic reactions, MrgprX2 regulated intracellular calcium levels via the PI3K/AKT and PLCγ pathways.

A TCM formula VYAC ameliorates DNCB-induced atopic dermatitis via blocking mast cell degranulation and suppressing NF-κB pathway

ETHNOPHARMACOLOGICAL RELEVANCE

A Traditional Chinese Medicine (TCM) formula (VYAC) consists of three herbs including Viola yedoensis Makino, herb (Violaceae, Viola), Sophora flavescens Aiton, root (Fabaceae, Sophora) and Dictamnus dasycarpus Turcz, root and rhizome (Rutaceae, Dictamnus), has been traditionally prescribed to treat various skin diseases in clinic.

AIM OF THE STUDY

This study aims to investigate the therapeutic effects of VYAC on the 2,4-dinitrobenzene (DNCB) induced atopic dermatitis (AD)-like mice and to explore the underlying mechanisms.

MATERIALS AND METHODS

VYAC was extracted with 70 % aqueous ethanol and lyophilized powder was used. AD-like mice were challenged by DNCB, VYAC (150 and 300 mg/kg) were oral administration daily from day 7 to day 28. At the end of experiment, the clinical scores were recorded, serum and skin in the dorsal were isolated to evaluate the therapeutic effects of VYAC. RBL-2H3 cells were stimulated with C48/80 for degranulation and plasmids expressing constitutively active form of Syk (Silence or overexpression) were transfected into RBL-2H3 cells to explore the underlying mechanisms in vitro.

RESULTS

VYAC significantly ameliorated the cardinal symptoms in the DNCB-induced AD-like mice by repairing the skin barrier function, inhibiting mast cells infiltration, restraining the serum IgE and histamine release and decreasing TNF-α, IL-4 as well as Syk mRNA level in dorsal skin and alleviating inflammation. Besides, VYAC significantly blocked RBL-2H3 cells degranulation, reduced β-hexosaminidase and histamine release, and suppressed NF-κB pathway. What's more, the degranulation of RBL-2H3 was reduced after Syk silence and increased after Syk overexpression.

CONCLUSION

Our findings clearly suggested that VYAC treat AD through inhibiting the inflammatory mediator productions and blocking mast cell degranulation via suppressing Syk mediated NF-κB pathway.

Abnormalities in Gut Microbiota and Metabolism in Patients With Chronic Spontaneous Urticaria

Background

Increasing evidence suggests that the gut microbiome plays a role in the pathogenesis of allergy and autoimmunity. The association between abnormalities in the gut microbiota and chronic spontaneous urticaria (CSU) remains largely undefined.

Methods

Fecal samples were obtained from 39 patients with CSU and 40 healthy controls (HCs). 16S ribosomal RNA (rRNA) gene sequencing (39 patients with CSU and 40 HCs) and untargeted metabolomics (12 patients with CSU and 12 HCs) were performed to analyze the compositional and metabolic alterations of the gut microbiome in CSU patients and HCs.

Results

The 16S rRNA gene sequencing results showed a significant difference in the β-diversity of the gut microbiota, presented as the Jaccard distance, between CSU patients and HCs. No significant differences were found in the α-diversity of the gut microbiota between patients and HCs. At the phylum level, the major bacteria in the gut microbiome of patients with CSU were Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria. At the genus level, Lactobacillus, Turicibacter, and Lachnobacterium were significantly increased and Phascolarctobacterium was decreased in patients with CSU. PICRUSt and correlation analysis indicated that Lactobacillus, Turicibacter, and Phascolarctobacterium were positively related to G protein-coupled receptors. Metabolomic analysis showed that α-mangostin and glycyrrhizic acid were upregulated and that 3-indolepropionic acid, xanthine, and isobutyric acid were downregulated in patients with CSU. Correlation analysis between the intestinal microbiota and metabolites suggested that there was a positive correlation between Lachnobacterium and α-mangostin.

Conclusions

This study suggests that disturbances in the gut microbiome composition and metabolites and their crosstalk or interaction may participate in the pathogenesis of CSU.

FAK inhibitor PF-431396 suppresses IgE-mediated mast cell activation and allergic inflammation in mice

Mast cells (MCs) initiate and maintain allergic inflammation. Upon being stimulated with immunoglobulin (Ig)E and antigen (Ag), MCs exhibit FcεRI (high-affinity IgE) receptor-mediated degranulation, cytokine secretion, and increased focal adhesion kinase (FAK) activity. The aims of this study were to examine mechanisms of FAK regulation in IgE-mediated MC activation and the effects of FAK inhibition on MC-mediated allergic responses. FAK activity was manipulated with short hairpin RNA (shRNA) knockdown, FAK overexpression, and the FAK inhibitor PF-431396 (PF). Gene expression and kinase activation were analyzed with quantitative molecular biology assays. PF effects were tested in the passive cutaneous anaphylaxis (PCA), active systemic anaphylaxis (ASA), and allergic conjunctivitis (AC) mouse models. Our results showed that FAK overexpression increased IgE-mediated degranulation and reduced the dexamethasone inhibitory effect on MCs activation. The FAK inhibitor PF diminished MC release of β-hexosaminidase (β-hex), histamine, and inflammatory cytokines, via a mechanism that involves MAPK and NF-κB signaling pathways. CaMKII was identified as a robust FAK-associating protein. Inhibition of CaMKII activation by KN-93 suppressed FAK activity and its downstream pathway. PF attenuated inflammatory responses in our PCA and ASA models, and relieved signs of allergic disease in AC model mice. In conclusions, MC degranulation and production of inflammatory mediators in allergic disease may be consequent to FcεRI crosslinking inducing CaMKII-mediated activation of FAK activity. FAK inhibition may represent a new MC-suppressing treatment strategy for the treatment of allergic diseases.

Small nucleolar RNA networks are up-regulated during human anaphylaxis

BACKGROUND

Anaphylaxis is a severe, potentially life-threatening allergic reaction driven primarily by the activation of mast cells. We still fail to understand factors underlying reaction severity. Furthermore, there is currently no reliable diagnostic test to confirm anaphylaxis in the emergency department (ED).

OBJECTIVE

This study sought to explore gene expression changes associated with anaphylaxis severity in peripheral blood leucocytes and evaluate biomarker potential.

METHODS

Microarray analysis (total RNA) was performed using peripheral blood samples from ED patients with moderate (n = 6) or severe (n = 12) anaphylaxis and sepsis (n = 20) at presentation (T0) and one hour later (T1). Results were compared between groups and healthy controls (n = 10 and n = 11 matched to anaphylaxis and sepsis patients, respectively). Changes in gene expression were determined using R programming language, and pathway analysis applied to explore biological processes and pathways associated with genes. Differentially expressed genes were validated in an independent cohort of anaphylaxis (n = 30) and sepsis (n = 20) patients, and healthy controls (n = 10), using quantitative reverse transcription-polymerase chain reaction (qRT-PCR).

RESULTS

Significant up-regulation of small nucleolar RNAs (snoRNAs) was demonstrated in anaphylaxis compared to sepsis patients in the microarray cohort, at T0 and T1. qRT-PCR analysis of the validation cohort showed five genes: SNORD61, SNORD8, SNORD69, SNORD119 and HIST1H1D to be significantly up-regulated (adjusted p < 0.05) in severe anaphylaxis compared to sepsis. Seven genes (SNORD61, SNORD8, SCARNA21, SNORD69, SNORD110, SNORD119 and SNORD59A) were significantly up-regulated (adjusted p < 0.05) in severe anaphylaxis compared to healthy controls.

CONCLUSION

This study demonstrates for the first time the unique involvement of snoRNAs in the pathogenesis of anaphylaxis and suggests they are not a general feature of systemic inflammation. Further investigation of snoRNA expression in anaphylaxis could provide insights into disease pathogenesis.

CLINICAL RELEVANCE

SnoRNAs are up-regulated during acute anaphylaxis in humans and could potentially be used as biomarkers of severe anaphylaxis.

Salvinorin A inhibits ovalbumin-stimulated allergic rhinitis and RBL-2H3 cells degranulation

Allergic rhinitis (AR) is a long-term noncommunicable inflammatory disease of the nasal mucosa mediated by immunoglobulin E and is mainly caused by exposure of genetically susceptible individuals to environmental allergens. Mast cells contribute to the pathogenesis of allergic and nonallergic inflammatory diseases. Salvinorin A has been previously shown to inhibit leukotriene production and mast cell degranulation to suppress airway hyperresponsiveness caused by sensitization; thus, we hypothesized that salvinorin A has an anti-AR effect. We tested this hypothesis using monoclonal anti-2,4,6-dinitrophenyl immunoglobulin E/human serum albumin-induced rat basophilic leukemia cells (RBL-2H3 cells) and ovalbumin (OVA)-induced AR in mice as in vivo and in vitro AR models, respectively. The expression levels of histamine, β-hexosaminidase, interleukin-4 and tumor necrosis factor-α were decreased by salvinorin A in vitro. Granule release and F-actin organization were also suppressed by salvinorin A. Furthermore, salvinorin A inhibited OVA-induced features of AR in mice, including nasal rubbing and sneezing, as well as increased OVA-specific immunoglobulin E, histamine, tumor necrosis factor-α and interleukin-4 levels. In addition, salvinorin A decreased the phosphorylation of phosphoinositide 3-kinase/Akt in vitro and in vivo. Our work suggests that salvinorin A suppresses AR caused by sensitization by inhibiting the inflammatory responses of mast cells; thus, salvinorin A may have potential for treatment of AR.

Stress and Nasal Allergy: Corticotropin-Releasing Hormone Stimulates Mast Cell Degranulation and Proliferation in Human Nasal Mucosa

Psychological stress exacerbates mast cell (MC)-dependent inflammation, including nasal allergy, but the underlying mechanisms are not thoroughly understood. Because the key stress-mediating neurohormone, corticotropin-releasing hormone (CRH), induces human skin MC degranulation, we hypothesized that CRH may be a key player in stress-aggravated nasal allergy. In the current study, we probed this hypothesis in human nasal mucosa MCs (hM-MCs) in situ using nasal polyp organ culture and tested whether CRH is required for murine M-MC activation by perceived stress in vivo. CRH stimulation significantly increased the number of hM-MCs, stimulated both their degranulation and proliferation ex vivo, and increased stem cell factor (SCF) expression in human nasal mucosa epithelium. CRH also sensitized hM-MCs to further CRH stimulation and promoted a pro-inflammatory hM-MC phenotype. The CRH-induced increase in hM-MCs was mitigated by co-administration of CRH receptor type 1 (CRH-R1)-specific antagonist antalarmin, CRH-R1 small interfering RNA (siRNA), or SCF-neutralizing antibody. In vivo, restraint stress significantly increased the number and degranulation of murine M-MCs compared with sham-stressed mice. This effect was mitigated by intranasal antalarmin. Our data suggest that CRH is a major activator of hM-MC in nasal mucosa, in part via promoting SCF production, and that CRH-R1 antagonists such as antalarmin are promising candidate therapeutics for nasal mucosa neuroinflammation induced by perceived stress.

Critical Care Management of the Patient With Anaphylaxis: A Concise Definitive Review

OBJECTIVES

Anaphylaxis is a rapidly progressive life-threatening syndrome manifesting as pruritus, urticaria, angioedema, bronchospasm and shock. The goal of this synthetic review is to provide a practical, updated approach to the evaluation and management of this disorder and associated complications.

DATA SOURCES

A MEDLINE search was conducted with the MeSH of anaphylaxis, anaphylactic reaction, anaphylactic shock, refractory anaphylaxis and subheadings of diagnosis, classification, epidemiology, complications and pharmacology. The level of evidence supporting an intervention was evaluated based on the availability of randomized studies, expert opinion, case studies, reviews, practice parameters and other databases (including Cochrane).

STUDY SELECTION

Selected publications describing anaphylaxis, clinical trials, diagnosis, mechanisms, risk factors and management were retrieved (reviews, guidelines, clinical trials, case series) and their bibliographies were also reviewed to identify relevant publications.

DATA EXTRACTION

Data from the relevant publications were reviewed, summarized and the information synthesized.

DATA SYNTHESIS

This is a synthetic review and the data obtained from a literature review was utilized to describe current trends in the diagnosis and management of the patient with anaphylaxis with a special emphasis on newer evolving concepts of anaphylaxis endotypes and phenotypes, management of refractory anaphylaxis in the ICU setting and review of therapeutic options for the elderly patient, or the complicated patient with severe cardiorespiratory complications. Most of the recommendations come from practice parameters, case studies or expert opinions, with a dearth of randomized trials to support specific interventions.

CONCLUSION

Anaphylaxis is a rapidly progressive life-threatening disorder. The critical care physician needs to be familiar with the diagnosis, differential diagnosis, evaluation, and management of anaphylaxis. Skilled intervention in ICUs may be required for the patient with complicated, severe, or refractory anaphylaxis.

Sputum mast cell/basophil gene expression relates to inflammatory and clinical features of severe asthma

BACKGROUND

Mast cells (MCs) and basophils are important in asthma pathophysiology, however direct measurement is difficult, and clinical and inflammatory associations in severe asthma are poorly understood. Transcriptomic hallmarks of MCs/basophils may allow their measurement in sputum using gene expression.

OBJECTIVES

This study sought to develop and validate a sputum MC/basophil gene signature and investigate its relationship to inflammatory and clinical characteristics of severe asthma.

METHODS

A total of 134 candidate MC/basophil genes (identified by the Immunological Genome Project Consortium) were screened in sputum microarray for differential expression among control subjects (n = 18), patients with eosinophilic (n = 29), and patients with noneosinophilic asthma (n = 30). Candidate genes were validated by confirming correlation of gene expression with flow cytometry-quantified sputum MCs and basophils in a separate asthma cohort (n = 20). The validated gene signature was measured in a severe asthma cohort (n = 81), and inflammatory and clinical associations were tested.

RESULTS

Through microarray screening and subsequent validation, we found quantitative PCR gene expression of 8 targets correlated with sputum MCs/basophils: TPSAB1/TPSB2, CPA3, ENO2, GATA2, KIT, GPR56, HDC, SOCS2. In severe asthma, MC/basophil genes were associated with eosinophilic airway inflammation (GATA2, TPSB2, CPA3, GPR56, HDC, SOCS2), blood eosinophils (TPSB2, CPA3, GATA2, SOCS2, FCER1A, HDC), fractional exhaled NO (GATA2, SOCS2), decreased lung function (KIT, ENO2), and moderate exacerbation history (GATA2, SOCS2).

CONCLUSIONS

Quantitative PCR-based measures reflect varying sputum MC/basophil abundance, demonstrating associations of MCs/basophils with eosinophilic inflammation, spirometry and exacerbation history in severe asthma.

TRPA1 deficiency alleviates inflammation of atopic dermatitis by reducing macrophage infiltration

AIMS

The aim of this study was to investigate the role of TRPA1 in the pathogenesis of AD.

MAIN METHODS

The experimental atopic dermatitis (AD)-like skin lesions were established using 2,4-dinitrochlorobenzene (DNCB). Mice were divided into three groups: TRPA1^-/- and WT groups were treated with DNCB dissolved in a 3:1 mixture of acetone and olive oil; the negative control group was treated with 3:1 mixture of acetone and olive oil without DNCB. The treatment lasted for 21 days, after which the animals were sacrificed and their blood, ears and dorsal skin tissue samples were collected for analysis.

KEY FINDINGS

Lower dermatitis score, ear thickness, pruritus score, and epidermal hyperplasia were observed in mice in TRPA1^-/- mice compared to the WT group. Besides, lower dermal mast cell infiltration, proinflammatory cytokines, Th2 cytokines and the infiltration of macrophages were observed in the TRPA1^-/- mice compared to the WT group. Furthermore, we demonstrated that TRPA1 antagonist HC-030031 could alleviate AD-like symptoms and reduce the degree of epidermal hyperplasia in mice.

SIGNIFICANCE

TRPA1 has a crucial role during the AD pathogenesis in mice, thus may be used as a potential new target for treating patients with chronic skin inflammatory disease.

Histamine Induced Production of Chemokine CXCL8 Through H1R/PLC and NF-κB Signaling Pathways in Nasal Fibroblasts

Background and Objectives: Histamine has been suggested to play an important role during allergic and inflammatory reactions, affecting allergic rhinitis and chronic rhinosinusitis. CXCL8 is a pro-inflammatory chemokine and a critical factor that causes many airway inflammatory diseases including allergic rhinitis and chronic rhinosinusitis.Materials and Method: Histamine cytotoxicity was measured by MTT assay. Real-time polymerase chain reaction was used to identify histamine type 1 receptor in nasal fibroblasts. The fibroblasts were then treated with histamine with or without a histamine type 1 receptor antagonist and the CXCL8 protein was assessed using an enzyme-linked immunosorbent assay (ELISA). The downstream signaling molecules, including phospholipase C and phospho-p50, were evaluated by western blot and immunofluorescent staining.Results: Histamine had no significant cytotoxic effect until the concentration reached 1,000 μM. Histamine type 1 receptor mRNA was expressed in nasal fibroblasts. CXCL8 protein expression level was significantly increased following histamine stimulation. However, the expression level of CXCL8 decreased when phospholipase C was inhibited by U73122. Histamine increased phospho-p50 expression as seen in western blot results. The BAY11-7082, NF-κB inhibitor significantly reduced CXCL8 production in histamine-stimulated nasal fibroblasts.Conclusion: Histamine can induce the production of NF-κB controlled-chemokine CXCL8 by nasal fibroblasts, which supports a role for histamine in upper airway inflammatory diseases.

Adult chronic rhinosinusitis

Chronic rhinosinusitis (CRS) occurs in >10% of the adult population in Europe and the USA and can be differentiated into CRS without nasal polyps and CRS with nasal polyps (CRSwNP). Both phenotypes are characterized by a high disease burden and an overlapping spectrum of symptoms, with facial pain and loss of smell being the most differentiating. Great progress has been made in the understanding of CRS pathophysiology: from the epithelium and epithelial-mesenchymal transition to innate and adaptive immunity pathways and, finally, on the role of eosinophils and Staphylococcus aureus in the persistence of disease. Although clinical manifestations and diagnostic tools (including nasal endoscopy and imaging) have undergone major changes over the past few years, management (including pharmacotherapy, surgery and biologics) has experienced enormous progress based on the growing knowledge of key mediators in severe CRSwNP. The introduction of endotyping has led to a differentiation of 'tailored' surgical approaches, focusing on the mucosal concept in those with severe CRSwNP and on the identification of patients eligible for extended surgery and possibly biologics in the future.

CCR3-shRNA promotes apoptosis and inhibits chemotaxis and degranulation of mouse mast cells

Mast cells (MCs) are the major effector cells of allergic rhinitis (AR). The present study aimed to investigate the effects of C-C chemokine receptor type 3 (CCR3) on the proliferation, apoptosis, chemotaxis and activated degranulation of mouse MCs. Mouse bone marrow-derived MCs were cultured in vitro, purified and identified using toluidine blue staining and flow cytometry. Three different CCR3-short hairpin (shRNA) lentiviral vectors were constructed and transfected into MCs, and the mRNA and protein expression levels of CCR3 were assessed by reverse transcription-quantitative PCR and western blotting. Proliferation and apoptosis of the MCs were measured using Cell Counting kit-8 (CCK-8) assays and flow cytometry, respectively. MC chemotaxis was assessed by Transwell assay and quantified using flow cytometry. The activation of MC degranulation was examined using ELISAs. The results demonstrated that MCs were appropriately isolated, and identified that CCR3-shRNA2 presented the higher knockdown effect among the three shRNAs tested. Following 96 h of transfection, the results of CCK-8 and flow cytometry assays demonstrated that CCR3-shRNA2 inhibited MC proliferation and promoted MC apoptosis. The results from the Transwell assay indicated that CCR3-shRNA2 restrained MC chemotaxis, whereas ELISA results demonstrated that CCR3-shRNA2 suppressed MC degranulation. In conclusion, CCR3-shRNA2 effectively downregulated CCR3 mRNA and protein expression levels in mouse MCs. In addition, CCR3-shRNA2 promoted MC apoptosis and suppressed the proliferation, chemotaxis and degranulation of mouse MCs, suggesting that CCR3-shRNA2 may serve as a therapeutic tool for the treatment of allergic rhinitis.

Tofacitinib suppresses mast cell degranulation and attenuates experimental allergic conjunctivitis

BACKGROUND

Allergic conjunctivitis (AC), a common eye inflammation that affects patients' health and quality of life, is still a therapeutic challenge for ophthalmologists. Tofacitinib, a new Janus kinase (JAK) inhibitor, has been successfully used in the treatment of several disorders. Nonetheless, its effect in AC and the potential anti-allergic mechanisms are still unclear. The objective of the current study was to explore the roles of tofacitinib in preventing AC and elucidate the potential underlying mechanisms.

METHODS

Tofacitinib was used topically in BALB/c mice with experimental allergic conjunctivitis (EAC). Ocular allergic symptoms and biological modifications were examined. To assess the anti-allergic mechanisms of tofacitinib, RBL-2H3 cells and HUVECs were cultured in vitro. The inhibitory effects and mechanisms of tofacitinib were studied and measured by real-time quantitative PCR, ELISA, western blot analysis, and flow cytometry.

RESULTS

Topical administration of tofacitinib reduced the clinical symptoms of OVA-induced EAC, with a substantial mitigation in inflammatory cell infiltration, histamine release, and TNF-α mRNA as well as IL-4 mRNA expression. In vitro, tofacitinib repressed the degranulation and cytokine production in RBL-2H3 cells and reduced histamine-induced vascular hyperpermeability. The underlying mechanism might involve the downregulation of phosphorylation of JAK3/STATs signaling molecules in RBL-2H3 cells and HUVECs.

CONCLUSIONS

Our findings provide evidence that tofacitinib prevented EAC by targeting the JAK3/STATs pathway. We recommend the use of tofacitinib as an innovative approach for the treatment of AC.

Mast Cell Biology at Molecular Level: a Comprehensive Review

Mast cells (MCs) are portions of the innate and adaptive immune system derived from bone marrow (BM) progenitors that are rich in cytoplasmic granules. MC maturation, phenotype, and function are determined by their microenvironment. MCs accumulate at inflammatory sites associated with atopy, wound healing, and malignancies. They interact with the external environment and are predominantly located in close proximity of blood vessels and sensory nerves. MCs are key initiators and modulators of allergic, anaphylactic, and other inflammatory reactions, by induction of vasodilation, promoting of vascular permeability, recruitment of inflammatory cells, facilitation of adaptive immune responses, and modulation of angiogenesis, and fibrosis. They express a wide range of receptors, e.g., for IgE (FcεRI), IgG (FcγR), stem cell factor (SCF) (KIT receptor or CD117), complement (including C5aR), and cytokines, that upon activation trigger various signaling pathways. The final consequence of such ligand receptor-based activation of MCs is the release of a broad array of mediators which are classified in three categories. While some mediators are preformed and remain stored in granules such as heparin, histamine, and enzymes mainly chymase and tryptase, others are de novo synthesized only after activation including LTB4, LTD4, PDG2, and PAF, and the cytokines IL-10, IL-8, IL-5, IL-3, IL-1, GM-CSF, TGF-β, VEGF, and TNF-α. Depending on the stimulus, MCs calibrate their pattern of mediator release, modulate the amplification of allergic inflammation, and are involved in the resolution of the immune responses. Here, we review recent findings and reports that help to understand the MC biology, pathology, and physiology of diseases with MC involvement.

The Role of Mast Cells in IgE-Independent Lung Diseases

Mast cells (MCs) are granular cells of the innate immune system which develop from CD34+/CD117+ progenitors and play a role in orchestrating adaptive immune responses. They have a well-known role in allergic reactions following immunoglobulin (Ig)E-mediated activation of the cell-surface expressed IgE high-affinity receptor (FcεRI). MCs can also respond to various other stimuli due to the expression of a variety of receptors including toll-like receptors (TLRs), immunoglobulin (IgG) receptors (FcγR), complement receptors such as C5a (CD88) expressed by skin MCs, neuropeptides receptors including nerve growth factor receptor, (NGFR), cytokines receptors such as (IL)-1R and IL-3R, and chemokines receptors including CCR-1 and CCR-3. MCs release three groups of mediators upon degranulation differentiated according to their chemical composition, storage, and time to release. These include preformed mediators (mainly histamine, tryptase, and chymase), de novo synthesized mediators such as prostaglandin (PG)D2, leukotriene (LT)B4 and LTD4, and cytokines including IL-1β, IL-3, tumor necrosis factor (TNF)α, and transforming growth factor(TGF)-β. Emerging evidence indicates a role for IgE-independent MC activation in the late-stage asthmatic response as well as in non-allergic airway diseases including chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), and lung cancer. MC infiltration/activation has been reported in some, but not all, studies of lung cancer. MC-derived TNF-α possesses tumor-suppressive activity while IL-1β supports tumor progression and metastasis. In IPF lungs, an increase in density of tryptase- and chymase-positive MCs (MCTC) and overexpression of TGF-β support the fibrosis progression. MC-derived chymase activates latent TGF-β that induces the differentiation of fibroblasts to matrix-producing myofibroblasts. In summary, increasing evidence highlights a critical role of MCs in non-allergic diseases that may indicate new approaches for therapy.

Nppb Neurons Are Sensors of Mast Cell-Induced Itch

Itch is an unpleasant skin sensation that can be triggered by exposure to many chemicals, including those released by mast cells. The natriuretic polypeptide b (Nppb)-expressing class of sensory neurons, when activated, elicits scratching responses in mice, but it is unclear which itch-inducing agents stimulate these cells and the receptors involved. Here, we identify receptors expressed by Nppb neurons and demonstrate the functional importance of these receptors as sensors of endogenous pruritogens released by mast cells. Our search for receptors in Nppb neurons reveals that they express leukotriene, serotonin, and sphingosine-1-phosphate receptors. Targeted cell ablation, calcium imaging of primary sensory neurons, and conditional receptor knockout studies demonstrate that these receptors induce itch by the direct stimulation of Nppb neurons and neurotransmission through the canonical gastrin-releasing peptide (GRP)-dependent spinal cord itch pathway. Together, our results define a molecular and cellular pathway for mast cell-induced itch.

Epithelial cells expressed IL-33 to promote degranulation of mast cells through inhibition on ST2/PI3K/mTOR-mediated autophagy in allergic rhinitis

Nasal epithelial cells are the first barrier against allergen infiltration in allergic rhinitis (AR), and the relationship between nasal epithelial cells and mast cell-mediated hypersensitivity remains unclear. This study aimed to investigate the possible association between allergen-challenged nasal epithelial cells (AR-HNEpC) and mast cell degranulation in AR. Our data revealed that calcium influx and degranulation were increased in AR-HNEpC-co-cultured mast cells. Expression of IL-33, a factor that binds to ST2 receptors on mast cells and regulates their degranulation, was elevated in AR-HNEpC. Blocking IL-33/ST2 pathway activated autophagy and inhibited degranulation and inflammatory factor release in mast cells. Furthermore, PI3K/mTOR was increased in IL-33-treated mast cells. Inhibition on PI3K/mTOR pathway enhanced autophagy and inhibited degranulation. Analysis using an in vivo AR model supported the above findings. In conclusion, IL-33 from epithelial cells promotes degranulation of mast cells in AR through inhibition on ST2/PI3K/mTOR-mediated autophagy, which provides a potential therapeutic target for the disease.Abbreviations: AR: allergic rhinitis; IL: interleukin; TNF-α: tumor necrosis factor-alpha; INF-γ: interferon-gamma; HNEpC: human nasal epithelial cell line; ATCC: American Type Culture Collection; C48/80: compound 48/80; 3-MA: 3-methyladenine; qPCR: quantitative PCR; AR-HNEpC: dust mite allergen-treated nasal epithelial cells; IgE: immunoglobulin E; Atg7: autophagy-related gene 7.

Aurora kinase inhibitor tozasertib suppresses mast cell activation in vitro and in vivo

BACKGROUND AND PURPOSE

Mast cells are important in allergic reactions. Here, we assessed the anti-allergic effects of the anti-cancer drug tozasertib specifically regarding regulatory effects on mast cell activation.

EXPERIMENTAL APPROACH

Tozasertib effects on mast cell degranulation were determined by measuring β-hexosaminidase and histamine release and by assessing morphological changes in RBL-2H3 and mouse bone marrow-derived mast cells (BMMCs) stimulated with mouse anti-dinitrophenyl (DNP)-IgE/DNP-human serum albumin or human LAD2 cells activated with phorbol-12-myristate 13-acetate plus calcium ionophore (PMACI). Western blots were performed to detect the expression of molecules involved in NF-κB, MAPK, and Aurora kinase signalling. in vivo anti-allergic effects of tozasertib were determined in the murine IgE-mediated passive cutaneous anaphylaxis (PCA) and ovalbumin (OVA)-induced active systemic anaphylaxis (ASA) models.

KEY RESULTS

Tozasertib treatment decreased high-affinity IgE receptor (FcεRI) or PMACI-mediated degranulation in RBL-2H3 cells and in BMMCs or LAD2 cells as shown by β-hexosaminidase or histamine levels. Similarly, tozasertib prevented morphological changes in mast cells, such as particle release and F-actin reorganization. In addition, tozasertib markedly decreased expression of phosphorylated (p)-NF-κB p65, p-Erk1/2, p-p38, and p-Aurora A/B, indicating that tozasertib can inhibit the signalling pathway mediating mast cell activation. Tozasertib attenuated IgE/Ag-induced PCA dose-dependently, as shown by reduced Evans blue staining. Similarly, tozasertib reduced body temperature levels and serum histamine levels in OVA-challenged ASA mice.

CONCLUSION AND IMPLICATIONS

The Aurora kinase inhibitor tozasertib suppressed mast cell activation in vitro and in vivo. Tozasertib may be a potential drug, targeting mast cell activation, to treat allergic diseases or mastocytosis.

Imidacloprid exposure suppresses cytokine production and neutrophil infiltration in TLR2-dependent activation of RBL-2H3 cells and skin inflammation of BALB/c mice

Imidacloprid suppressed TNF-α and IL-6 production and neutrophil infiltration, without altering mast cell degranulation.

IL-33 mediated amplification of allergic response in human mast cells

Context: IL-33 is a pro-inflammatory cytokine that is involved in the development of chronic inflammatory diseases and the initiation of allergic inflammation in response to pathogens and acts an alarmin.Objective: Present study aims to explore the IL-33 mediated effects of histamine induced allergic inflammation in human mast cells.Materials and methods: In this study, cord blood derived CD34+ mast cells and HMC-1 cells were primed with IL-33 followed by the stimulation with histamine. We investigated the functional activation of mast cell by intracellular calcium release using calcium mobilization assay, release of granular content using degranulation assay, profiling of various inflammatory and regulatory cytokines as well as chemokines by Luminex Bioplex assay and its signaling mechanisms involved using western blot analysis.Results: In our study, we found that the IL-33 acts as a mediator in the allergic inflammation induced by the histamine. IL-33 potentiates the release of intracellular calcium and degranulation content in human mast cells. Also, it enhances the production of Th2, Th1 cytokines and chemokines and down-regulates the production of regulatory cytokine. Furthermore, it enhanced the phosphorylation of the signaling molecules such as ERK, Akt, and NFκB in activated mast cells. Therefore, IL-33 acts as a potent activator of mast cells and it can elicit inflammatory response synergistically with histamine.Conclusions: Taken together, IL-33 acts as a potent mediator by inducing the inflammatory response in activated mast cells, hence increasing their responsiveness to antigens and amplifying the allergic response.

Asthma biologics: Comparing trial designs, patient cohorts and study results

OBJECTIVE

Five biologic therapies have FDA-approved indications for difficult-to-control asthma. The clinical trials that proved the efficacy and safety of these biologics were often similar in their inclusion criteria, study designs, and endpoints. Many of these trials have been reanalyzed post hoc to identify subsets of subjects considered to be enhanced responders. As a result, keeping up with the literature and deciding on the most appropriate biologic for our patients has become increasingly difficult. This review summarizes and compares trial designs, patient cohorts, and study results of the major trials involving these therapies.

DATA SOURCES

Included are basic science articles, online Food and Drug Administration (FDA) applications, and all the published reports of phase II and phase III clinical trials for FDA-approved asthma biologics.

STUDY SELECTIONS

Included are the major phase II and phase III clinical trials of 5 asthma biologics.

RESULTS

Because of variations in inclusion criteria and natural variations in enrolled cohorts, the baseline clinical traits and severity of study populations in asthma biologic trials differed significantly, which is important because baseline annualized exacerbation rates and blood eosinophilia are both strong predictors of a biologic's success. Notwithstanding, the trial results, when considered together, can help guide care providers in choosing the most appropriate biologic for our patients.

CONCLUSION

Understanding the details and differences in asthma biologic trial designs, patient cohorts, and in study results will help care providers make more informed decisions when choosing a biologic. We are hopeful this review will serve as a reference to care providers for this purpose.

Mast Cell-Mediated Orchestration of the Immune Responses in Human Allergic Asthma: Current Insights

Improving the lung function after experimental allergen challenge by blocking of mast cell (MC) mediators and the capability of MC mediators (including histamine, prostaglandin (PG) D2, and leukotriene (LT) C4) in induction of mucosal edema, bronchoconstriction, and mucus secretion provide evidence that MCs play a key role in pathophysiology of asthma. In asthma, the number of MCs increases in the airways and infiltration of MCs in a variety of anatomical sites including the epithelium, the submucosal glands, and the smooth muscle bundles occurs. MC localization within the ASM is accompanied with the hypertrophy and hyperplasia of the layer, and smooth muscle dysfunction that is mainly observed in forms of bronchial hyperresponsiveness, and variable airflow obstruction. Owing to the expression of a wide range of surface receptors and releasing various cytoplasmic mediators, MCs orchestrate the pathologic events of the disease. MC-released preformed mediators including chymase, tryptase, and histamine and de novo synthesized mediators such as PGD2, LTC4, and LTE4 in addition of cytokines mainly TGFβ1, TSLP, IL-33, IL-4, and IL-13 participate in pathogenesis of asthma. The release of MC mediators and MC/airway cell interactions during remodeling phase of asthma results in persistent cellular and structural changes in the airway wall mainly epithelial cell shedding, goblet cell hyperplasia, hypertrophy of ASM bundles, fibrosis in subepithelial region, abnormal deposition of extracellular matrix (ECM), increased tissue vascularity, and basement membrane thickening. We will review the current knowledge regarding the participation of MCs in each stage of asthma pathophysiology including the releasing mediators and their mechanism of action, expression of receptors by which they respond to stimuli, and finally the pharmaceutical products designed based on the strategy of blocking MC activation and mediator release.

Expression Analysis of Serotonin Receptors, Serotonin Transporter and l-Amino Acid Decarboxylase in the Mouse Sphenopalatine Ganglion by RT-PCR, Northern Blot Analysis and In Situ Hybridization

The sphenopalatine ganglion (SPG) is a gathering of the cell bodies of parasympathetic fibers that dominate the nasal gland, lacrimal gland and cerebral blood vessels. The SPG controls nasal secretions, tears, and the dilation of cerebral blood vessels. However, it is unclear how serotonin regulates SPG functions. In this study, we investigated the expression of genes involved in the serotonergic system in the mouse SPG. We examined the mRNA expression levels of 5-HT_1A, 5-HT_1B, 5-HT_1D, 5-HT_1F, 5-HT_2A, 5-HT_2B, 5-HT_2C, 5-HT_3A, 5-HT_3B, 5-HT₄, 5-HT_5A, 5-HT_5B, 5-HT₆ and 5-HT₇ receptors, as well as serotonin transporter, tryptophan hydroxylases 1 and 2, and L-amino acid decarboxylase (AADC) by RT-PCR. It revealed that the 5-HT_3A and 5-HT_3B ionotropic receptors and AADC were likely to be highly expressed in the SPG, as measured by RT-PCR. We next performed in situ hybridization on the SPG to examine the expression of these three genes at the cellular level after validating the specificity of each cRNA probe by northern blotting. The 5-HT_3A receptor, 5-HT_3B receptor, and AADC were expressed in 96.5% ± 1.0%, 29.7% ± 10.7%, and 57.4% ± 2.9% of neuronal cell bodies in the SPG, respectively, indicating that the 5-HT_3A receptor was virtually expressed in all SPG neurons. Our results on the expression of these critical serotonin system genes in the parasympathetic SPG provide insight into the pathogenetics of rhinitis, conjunctivitis and headache. Furthermore, our findings suggest that targeting the 5-HT_3A receptor might have therapeutic potential in the treatment of these ailments.

Mast cell degranulation impairs pneumococcus clearance in mice via IL-6 dependent and TNF-α independent mechanisms

Background

Mast cells participate in immune responses by releasing potent immune system modifiers via degranulation. Due to currently reported controversial roles of mast cells in Streptococcus pneumoniae infections, this study aimed to determine the role and mechanism of mast cells in clearing S. pneumoniae in mice.

Methods

In vivo mouse model of mast cell degranulation established by administration of C48/80 was evaluated for the influences of mast cell degranulation on bacterial colonization and inflammation. In vitro model was established to observe the influences of mast cell degranulation on phagocytic and bactericidal functions of neutrophils and macrophages. IL-6 null and TNF-α null mice on the C57BL/6 background were used to investigate the effects of inflammatory factors released by mast cell degranulation on bacterial clearance.

Results

Mast cell degranulation increased IL-6 and TNF-α levels and immune cell numbers in nasal lavage fluid, and inhibited the bactericidal function of macrophages and neutrophils in vitro. It decreased the number of neutrophils and macrophages recruited to respiratory tract after S. pneumoniae challenge and inhibited the clearance of S. pneumoniae in mice. After pretreatment with C48/80, S. pneumoniae loads were significantly lower in IL-6 null mice than in wild type mice, while no differences were observed between TNF-α null and wild type mice.

Conclusions

Mast cell degranulation can cause inflammation and impair immune cell recruitment to respiratory tract after S. pneumoniae challenge. Products of mast cell degranulation including IL-6 decreased the bactericidal function of neutrophils and macrophages. Through these mechanisms, mast cell degranulation inhibited clearance of S. pneumoniae in mice.

Anaphylactic Degranulation of Mast Cells: Focus on Compound Exocytosis

Anaphylaxis is a notorious type 2 immune response which may result in a systemic response and lead to death. A precondition for the unfolding of the anaphylactic shock is the secretion of inflammatory mediators from mast cells in response to an allergen, mostly through activation of the cells via the IgE-dependent pathway. While mast cells are specialized secretory cells that can secrete through a variety of exocytic modes, the most predominant mode exerted by the mast cell during anaphylaxis is compound exocytosis-a specialized form of regulated exocytosis where secretory granules fuse to one another. Here, we review the modes of regulated exocytosis in the mast cell and focus on compound exocytosis. We review historical landmarks in the research of compound exocytosis in mast cells and the methods available for investigating compound exocytosis. We also review the molecular mechanisms reported to underlie compound exocytosis in mast cells and expand further with reviewing key findings from other cell types. Finally, we discuss the possible reasons for the mast cell to utilize compound exocytosis during anaphylaxis, the conflicting evidence in different mast cell models, and the open questions in the field which remain to be answered.

Interactions between polycyclic aromatic hydrocarbons and epoxide hydrolase 1 play roles in asthma

Asthma, as one of the most common chronic diseases in children and adults, is a consequence of complex gene-environment interactions. Polycyclic aromatic hydrocarbons (PAHs), as a group of widespread environmental organic pollutants, are involved in the development, triggering and pathologic changes of asthma. Various previous studies reported the critical roles of PAHs in immune changes, oxidative stress and environment-gene interactions of asthma. EPHX1 (the gene of epoxide hydrolase 1, an enzyme mediating human PAH metabolism) had a possible association with asthma by influencing PAH metabolism. This review summarized that (1) the roles of PAHs in asthma-work as risk factors; (2) the possible mechanisms involved in PAH-related asthma-through immunologic and oxidative stress changes; (3) the interactions between PAHs and EPHX1 involved in asthma-enzymatic activity of epoxide hydrolase 1, which affected by EPHX1 genotypes/SNPs/diplotypes, could influence human PAH metabolism and people's vulnerability to PAH exposure. This review provided a better understanding of the above interactions and underlying mechanisms for asthma which help to raise public's concern on PAH control and develop strategies for individual asthma primary prevention.

[Seasonal allergic conjunctivitis]

Seasonal allergic conjunctivitis (SAC) is a frequent disease, which is often associated with allergic rhinitis and subsequently manifested as allergic rhinoconjunctivitis. In contrast to other types of chronic allergic conjunctivitis, the course of SAC is not sight-threatening. Pathogenetically, the underlying cause of SAC is an immunoglobulin E (IgE) mediated, Th2-driven type 1 hypersensitivity reaction. Clinically it presents with itching, light-red conjunctival injection as well as chemosis that exceeds the extent of conjunctival injection. The goals of treatment are relief of acute signs and symptoms, control of the underlying inflammatory process and utilization of preventive options. Dually effective local therapeutics combine the advantages of rapid action with a relatively long-lasting effect by a two-fold active approach. Specific immunotherapy is useful in selected patients.

Berberine suppresses IL-33-induced inflammatory responses in mast cells by inactivating NF-κB and p38 signaling

Berberine (BBR) possesses many pharmacological characteristics including anti-inflammation, anti-allergy, anti-angiogenesis and anti-tumor. However, the effects and mechanisms of BBR on IL-33-induced mast cell inflammatory responses are kept unknown. To investigate these, rat peritoneal mast cells (RPMCs) were isolated from the peritoneal cavity and cultured with BBR treatment in combination IL-33 stimulation. Firstly, cytotoxic effect of BBR on RPMCs was detected by MTT assay. Then, IL-33-induced cytokine production and the expression of ST2 receptor, were evaluated by ELISA and real-time PCR, respectively. In addition, NF-κB and MAPK signaling involved in IL-33-mediated mast cell activation were assessed by Western blot, which also was confirmed using the signal transduction inhibitors. Simultaneously, the effect of BBR on IL-33-activated enhancement of IgE-mediated mast cell responses was analyzed. Lastly, SD rats were used to explore the effect of BBR on IL-33-induced inflammation in vivo. BBR treatment significantly reduced IL-33-stimulated cytokine production in RPMCs, such as IL-6, TNF-α, IL-13 and MCP-1, but had little effect in ST2 expression. BBR modulated IL-33 signaling via suppressing IL-33-induced NF-ΚB transcription and p38 phosphorylation, but not ERK and JNK. Additionally, BBR also hampered the combined effects of IL-33 and IgE-mediated mast cell activation. Decreased cytokine production followed BBR treatment in vitro was consistent with that in vivo, where BBR injection i.p. into rats obviously inhibited IL-33-induced plasma cytokine levels. These findings demonstrated that BBR suppressed IL-33-mediated inflammation in mast cells by inactivating NF-κB and p38 signaling, suggesting its potential application for the treatment of allergic inflammation.