The multi-faceted role of allergen exposure to the local airway mucosa

Neuropeptide S and its receptor aggravated asthma via TFEB dependent autophagy in bronchial epithelial cells

BACKGROUND

Asthma is a prevalent respiratory disorder with limited treatment strategy. Neuropeptide S (NPS) is a highly conserved peptide via binding to its receptor NPSR, a susceptibility gene for asthma from genomics studies. However, little is known about the role of NPS-NPSR in the pathogenesis of asthma. This study was performed to determine the effect and underlying mechanism of NPS-NPSR on asthma.

METHODS

NPSR knockdown was verified to affect asthma through autophagy by transcriptome sequencing and molecular biology experiments in animal models. Silencing of transcription factor EB in a bronchial epithelial cell line and validation of NPS-NPSR activation of autophagy dependent on transcription factor EB.

RESULTS

Our results showed that NPSR expression was markedly increased in asthmatic humans and mice, mainly localized in bronchial epithelial cells. Using ovalbumin (OVA) and papain-induced asthma mouse models, NPSR-deficient mice exhibited significantly alleviated asthma, with reduced small airway lesions and inflammatory infiltration compared with wild-type mice. OVA and papain promoted TFEB-mediated autophagy with increased ATG5 and LC3 II expression, and NPS effectively regulated the activation of TFEB and autophagy. In turn, specific TFEB knockdown could restore the effect of exogenous NPS and its receptor antagonist on the autophagy and cytokines secretion in bronchial epithelial cells. Furthermore, Prkcg may be the key upstream targeting of the TFEB-autophagy pathway involved in asthma.

CONCLUSIONS

NPS-NPSR exacerbated asthma by regulating the TFEB-autophagy axis in airway epithelial injury, which may be a potential target for asthma therapy.

The extracellular serine protease from Staphylococcus epidermidis elicits a type 2-biased immune response in atopic dermatitis patients

Background

Atopic dermatitis (AD) is a chronic, relapsing inflammatory skin disease with skin barrier defects and a misdirected type 2 immune response against harmless antigens. The skin microbiome in AD is characterized by a reduction in microbial diversity with a dominance of staphylococci, including Staphylococcus epidermidis (S. epidermidis).

Objective

To assess whether S. epidermidis antigens play a role in AD, we screened for candidate allergens and studied the T cell and humoral immune response against the extracellular serine protease (Esp).

Methods

To identify candidate allergens, we analyzed the binding of human serum IgG4, as a surrogate of IgE, to S. epidermidis extracellular proteins using 2-dimensional immunoblotting and mass spectrometry. We then measured serum IgE and IgG1 binding to recombinant Esp by ELISA in healthy and AD individuals. We also stimulated T cells from AD patients and control subjects with Esp and measured the secreted cytokines. Finally, we analyzed the proteolytic activity of Esp against IL-33 and determined the cleavage sites by mass spectrometry.

Results

We identified Esp as the dominant candidate allergen of S. epidermidis. Esp-specific IgE was present in human serum; AD patients had higher concentrations than controls. T cells reacting to Esp were detectable in both AD patients and healthy controls. The T cell response in healthy adults was characterized by IL-17, IL-22, IFN-γ, and IL-10, whereas the AD patients' T cells lacked IL-17 production and released only low amounts of IL-22, IFN-γ, and IL-10. In contrast, Th2 cytokine release was higher in T cells from AD patients than from healthy controls. Mature Esp cleaved and activated the alarmin IL-33.

Conclusion

The extracellular serine protease Esp of S. epidermidis can activate IL-33. As an antigen, Esp elicits a type 2-biased antibody and T cell response in AD patients. This suggests that S. epidermidis can aggravate AD through the allergenic properties of Esp.

Developments in the Management of Severe Asthma in Children and Adolescents: Focus on Dupilumab and Tezepelumab

Severe asthma in children and adolescents exerts a substantial health, financial, and societal burden. Severe asthma is a heterogeneous condition with multiple clinical phenotypes and underlying inflammatory patterns that might be different in individual patients. Various add-on treatments have been developed to treat severe asthma, including monoclonal antibodies (biologics) targeting inflammatory mediators. Biologics that are currently approved to treat children (≥ 6 years of age) or adolescents (≥ 12 years of age) with severe asthma include: anti-immunoglobulin E (omalizumab), anti-interleukin (IL)-5 (mepolizumab), anti-IL5 receptor (benralizumab), anti-IL4/IL13 receptor (dupilumab), and antithymic stromal lymphopoietin (TSLP) (tezepelumab). However, access to these targeted treatments varies across countries and relies on few and crude indicators. There is a need for better treatment stratification to guide which children might benefit from these treatments. In this narrative review we will assess the most recent developments in the treatment of severe pediatric asthma, as well as potential biomarkers to assess treatment efficacy for this patient population.

New insights into the pathophysiology and therapeutic targets of asthma and comorbid chronic rhinosinusitis with or without nasal polyposis

Asthma and chronic rhinosinusitis with nasal polyps (CRSwNP) or without (CRSsNP) are chronic respiratory diseases. These two disorders often co-exist based on common anatomical, immunological, histopathological, and pathophysiological basis. Usually, asthma with comorbid CRSwNP is driven by type 2 (T2) inflammation which predisposes to more severe, often intractable, disease. In the past two decades, innovative technologies and detection techniques in combination with newly introduced targeted therapies helped shape our understanding of the immunological pathways underlying inflammatory airway diseases and to further identify several distinct clinical and inflammatory subsets to enhance the development of more effective personalized treatments. Presently, a number of targeted biologics has shown clinical efficacy in patients with refractory T2 airway inflammation, including anti-IgE (omalizumab), anti-IL-5 (mepolizumab, reslizumab)/anti-IL5R (benralizumab), anti-IL-4R-α (anti-IL-4/IL-13, dupilumab), and anti-TSLP (tezepelumab). In non-type-2 endotypes, no targeted biologics have consistently shown clinical efficacy so far. Presently, multiple therapeutical targets are being explored including cytokines, membrane molecules and intracellular signalling pathways to further expand current treatment options for severe asthma with and without comorbid CRSwNP. In this review, we discuss existing biologics, those under development and share some views on new horizons.

Oral Mucosa as a Potential Site for Diagnosis and Treatment of Allergic and Autoimmune Diseases

Most prevalent food allergies during early childhood are caused by foods with a high allergenic protein content, such as milk, egg, nuts, or fish. In older subjects, some respiratory allergies progressively lead to food-induced allergic reactions, which can be severe, such as urticaria or asthma. Oral mucosa remodeling has been recently proven to be a feature of severe allergic phenotypes and autoimmune diseases. This remodeling process includes epithelial barrier disruption and the release of inflammatory signals. Although little is known about the immune processes taking place in the oral mucosa, there are a few reports describing the oral mucosa-associated immune system. In this review, we will provide an overview of the recent knowledge about the role of the oral mucosa in food-induced allergic reactions, as well as in severe respiratory allergies or food-induced autoimmune diseases, such as celiac disease.

Induction of IL-10-producing type 2 innate lymphoid cells by allergen immunotherapy is associated with clinical response

The role of innate immune cells in allergen immunotherapy that confers immune tolerance to the sensitizing allergen is unclear. Here, we report a role of interleukin-10-producing type 2 innate lymphoid cells (IL-10⁺ ILC2s) in modulating grass-pollen allergy. We demonstrate that KLRG1⁺ but not KLRG1^- ILC2 produced IL-10 upon activation with IL-33 and retinoic acid. These cells attenuated Th responses and maintained epithelial cell integrity. IL-10⁺ KLRG1⁺ ILC2s were lower in patients with grass-pollen allergy when compared to healthy subjects. In a prospective, double-blind, placebo-controlled trial, we demonstrated that the competence of ILC2 to produce IL-10 was restored in patients who received grass-pollen sublingual immunotherapy. The underpinning mechanisms were associated with the modification of retinol metabolic pathway, cytokine-cytokine receptor interaction, and JAK-STAT signaling pathways in the ILCs. Altogether, our findings underscore the contribution of IL-10⁺ ILC2s in the disease-modifying effect by allergen immunotherapy.

IgE autoantibodies and autoreactive T cells and their role in children and adults with atopic dermatitis

The pathophysiology of atopic dermatitis (AD) is highly complex and understanding of disease endotypes may improve disease management. Immunoglobulins E (IgE) against human skin epitopes (IgE autoantibodies) are thought to play a role in disease progression and prolongation. These antibodies have been described in patients with severe and chronic AD, suggesting a progression from allergic inflammation to severe autoimmune processes against the skin. This review provides a summary of the current knowledge and gaps on IgE autoreactivity and self-reactive T cells in children and adults with AD based on a systematic search. Currently, the clinical relevance and the pathomechanism of IgE autoantibodies in AD needs to be further investigated. Additionally, it is unknown whether the presence of IgE autoantibodies in patients with AD is an epiphenomenon or a disease endotype. However, increased knowledge on the clinical relevance and the pathophysiologic role of IgE autoantibodies and self-reactive T cells in AD can have consequences for diagnosis and treatment. Responses to the current available treatments can be used for better understanding of the pathways and may shed new lights on the treatment options for patients with AD and autoreactivity against skin epitopes. To conclude, IgE autoantibodies and self-reactive T cells can contribute to the pathophysiology of AD based on the body of evidence in literature. However, many questions remain open. Future studies on autoreactivity in AD should especially focus on the clinical relevance, the contribution to the disease progression and chronicity on cellular level, the onset and therapeutic strategies.

Protease-Activated Receptor-2 Decreased Zonula Occlidens-1 and Claudin-1 Expression and Induced Epithelial Barrier Dysfunction in Allergic Rhinitis

BACKGROUND

Protease-activated receptor-2 (PAR-2)-modulated tight junctions (TJs) have been suggested to be involved in the pathogenesis of chronic inflammatory diseases. However, immunopathogenesis remains to be investigated among patients with allergic rhinitis (AR).

OBJECTIVE

This study sought to investigate the role of PAR-2 in the modulation of epithelial barrier function and the expression of TJs in the nasal mucosa of AR patients.

METHODS

The expression of TJs and PAR-2 of the nasal mucosa in AR patients and control subjects by immunohistochemistry, quantitative real-time polymerase chain reaction (qRT-PCR), and western blotting. In vitro, Primary human nasal epithelial cells (pHNECs) of AR patients were stimulated by Der p1 to analyze the correlation between PAR-2 and TJs expression. Der p1-induced pHNECs were treated with the PAR-2 agonist SLIGRL-NH2 and antagonist FSLLRY-NH2. Fluorescein isothiocyanate-dextran 4 kDa detection was employed as an indicator of epithelial permeability.

RESULTS

Lower expression levels of TJs in the nasal epithelium of AR patients were observed in comparison with that in control subjects. The PAR-2 level was markedly increased following treatment with 1,000 ng/mL of Der p1 for 24 hours in a cellular model of AR. The expression of PAR-2 was increased in Der p1-induced pHNECs of AR patients and correlated inversely with zonula occlidens (ZO)-1 and claudin-1. Treatment with Der p1 further downregulated TJs expression and promoted an increased epithelial permeability in Der p1-induced pHNECs.

CONCLUSIONS

PAR-2 could downregulate the expression of ZO-1 and claudin-1, which is involved in epithelial barrier dysfunction in AR.

Particulate Matter 2.5 Causes Deficiency in Barrier Integrity in Human Nasal Epithelial Cells

Purpose

The effect of air pollution-related particulate matter (PM) on epithelial barrier function and tight junction (TJ) expression in human nasal mucosa has not been studied to date. This study therefore aimed to assess the direct impact of PM with an aerodynamic diameter less than 2.5 μm (PM2.5) on the barrier function and TJ molecular expression of human nasal epithelial cells.

Methods

Air-liquid interface cultures were established with epithelial cells derived from noninflammatory nasal mucosal tissue collected from patients undergoing paranasal sinus surgery. Confluent cultures were exposed to 50 or 100 µg/mL PM2.5 for up to 72 hours, and assessed for 1) epithelial barrier integrity as measured by transepithelial resistance (TER) and permeability of fluorescein isothiocyanate (FITC) 4 kDa; 2) expression of TJs using real-time quantitative polymerase chain reaction and immunofluorescence staining, and 3) proinflammatory cytokines by luminometric bead array or enzyme-linked immunosorbent assay.

Results

Compared to control medium, 50 and/or 100 µg/mL PM2.5-treatment 1) significantly decreased TER and increased FITC permeability, which could not be restored by budesonide pretreatment; 2) significantly decreased the expression of claudin-1 messenger RNA, claudin-1, occludin and ZO-1 protein; and 3) significantly increased production of the cytokines interleukin-8, TIMP metallopeptidase inhibitor 1 and thymic stromal lymphopoietin.

Conclusions

Exposure to PM2.5 may lead to loss of barrier function in human nasal epithelium through decreased expression of TJ proteins and increased release of proinflammatory cytokines. These results suggest an important mechanism of susceptibility to rhinitis and rhinosinusitis in highly PM2.5-polluted areas.

Tight junction, mucin, and inflammasome-related molecules are differentially expressed in eosinophilic, mixed, and neutrophilic experimental asthma in mice

BACKGROUND

Asthma is a chronic respiratory disease with marked clinical and pathophysiological heterogeneity. Specific pathways are thought to be involved in the pathomechanisms of different inflammatory phenotypes of asthma; however, direct in vivo comparison has not been performed.

METHODS

We developed mouse models representing three different phenotypes of allergic airway inflammation-eosinophilic, mixed, and neutrophilic asthma via different methods of house dust mite sensitization and challenge. Transcriptomic analysis of the lungs, followed by the RT-PCR, western blot, and confocal microscopy, was performed. Primary human bronchial epithelial cells cultured in air-liquid interface were used to study the mechanisms revealed in the in vivo models.

RESULTS

By whole-genome transcriptome profiling of the lung, we found that airway tight junction (TJ), mucin, and inflammasome-related genes are differentially expressed in these distinct phenotypes. Further analysis of proteins from these families revealed that Zo-1 and Cldn18 were downregulated in all phenotypes, while increased Cldn4 expression was characteristic for neutrophilic airway inflammation. Mucins Clca1 (Gob5) and Muc5ac were upregulated in eosinophilic and even more in neutrophilic phenotype. Increased expression of inflammasome-related molecules such as Nlrp3, Nlrc4, Casp-1, and IL-1β was characteristic for neutrophilic asthma. In addition, we showed that inflammasome/Th17/neutrophilic axis cytokine-IL-1β-may transiently impair epithelial barrier function, while IL-1β and IL-17 increase mucin expressions in primary human bronchial epithelial cells.

CONCLUSION

Our findings suggest that differential expression of TJ, mucin, and inflammasome-related molecules in distinct inflammatory phenotypes of asthma may be linked to pathophysiology and might reflect the differences observed in the clinic.

Profilin-mediated food-induced allergic reactions are associated with oral epithelial remodeling

BACKGROUND

In areas of high exposure to grass pollen, allergic patients are frequently sensitized to profilin, and some experience severe profilin-mediated food-induced reactions. This specific population of patients is ideal to study the relationship between respiratory and food allergies.

OBJECTIVE

We sought to determine the role of oral mucosal epithelial barrier integrity in profilin-mediated allergic reactions.

METHODS

Thirty-eight patients with profilin allergy stratified into mild or severe according to their clinical history and response to a profilin challenge test and 6 nonallergic subjects were recruited. Oral mucosal biopsies were used for measurement of CD11c, CD3, CD4, tryptase, claudin-1, occludin, E-cadherin, and vascular endothelial growth factor A levels; Masson trichrome staining; and POSTN, IL33, TPSAB, TPSB, and CMA gene expression analysis by using quantitative RT-PCR. Blood samples were used for basophil activation tests.

RESULTS

Distinct features of the group with severe allergy included the following: (1) impaired epithelial integrity with reduced expression of claudin-1, occludin, and E-cadherin and decreased numbers of epithelial cells, which is indicative of acanthosis, higher collagen deposition, and angiogenesis; (2) inflammatory immune response in the mucosa, with an increased number of CD11c⁺ and CD4⁺ infiltrates and increased expression of the cytokine genes POSTN and IL33; and (3) a 10-fold increased sensitivity of basophils to profilin.

CONCLUSIONS

Patients with profilin allergy present with significant damage to the oral mucosal epithelial barrier, which might allow profilin penetration into the oral mucosa and induction of local inflammation. Additionally, severely allergic patients presented with increased sensitivity of effector cells.

Emerging roles of innate lymphoid cells in inflammatory diseases: Clinical implications

Innate lymphoid cells (ILC) represent a group of lymphocytes that lack specific antigen receptors and are relatively rare as compared to adaptive lymphocytes. ILCs play important roles in allergic and nonallergic inflammatory diseases due to their location at barrier surfaces within the airways, gut, and skin, and they respond to cytokines produced by activated cells in their local environment. Innate lymphoid cells contribute to the immune response by the release of cytokines and other mediators, forming a link between innate and adaptive immunity. In recent years, these cells have been extensively characterized and their role in animal models of disease has been investigated. Data to translate the relevance of ILCs in human pathology, and the potential role of ILCs in diagnosis, as biomarkers and/or as future treatment targets are also emerging. This review, produced by a task force of the Immunology Section of the European Academy of Allergy and Clinical Immunology (EAACI), encompassing clinicians and researchers, highlights the role of ILCs in human allergic and nonallergic diseases in the airways, gastrointestinal tract, and skin, with a focus on new insights into clinical implications, therapeutic options, and future research opportunities.

Effect of O3 and NO2 atmospheric pollutants on Platanus x acerifolia pollen: Immunochemical and spectroscopic analysis

In the present study, the effects of two important oxidizing atmospheric pollutants (O₃ and NO₂) on the allergenic properties and chemical composition of Platanus x acerifolia pollen were studied. Pollen samples were subjected to O₃ and/or NO₂ under in vitro conditions for 6h at atmospheric concentration levels (O₃: 0.061ppm; NO₂: 0.025ppm and the mixture of O₃ and NO₂: 0.060 and 0.031ppm respectively). Immunoblotting (using Pla a 1 and Pla a 2 antibodies), infrared and X-ray photoelectron spectroscopy techniques were used. Immunochemical analysis showed that pollen allergenicity changes were different according to the pollutant tested (gas or mixture of gasses) and that the same pollutant gas may interact in a different manner with each specific allergen. The spectroscopy results showed modifications in the FTIR spectral features of bands assigned to proteins, lipids, and polysaccharides of the pollen exposed to the pollutants, as well as in the XPS spectra high-resolution components C 1s, N 1s, and O 1s. This indicates that while airborne, the pollen wall suffers further modifications of its components induced by air pollution, which can compromise the pollen function.

Air Pollution and Climate Change Effects on Allergies in the Anthropocene: Abundance, Interaction, and Modification of Allergens and Adjuvants

Air pollution and climate change are potential drivers for the increasing burden of allergic diseases. The molecular mechanisms by which air pollutants and climate parameters may influence allergic diseases, however, are complex and elusive. This article provides an overview of physical, chemical and biological interactions between air pollution, climate change, allergens, adjuvants and the immune system, addressing how these interactions may promote the development of allergies. We reviewed and synthesized key findings from atmospheric, climate, and biomedical research. The current state of knowledge, open questions, and future research perspectives are outlined and discussed. The Anthropocene, as the present era of globally pervasive anthropogenic influence on planet Earth and, thus, on the human environment, is characterized by a strong increase of carbon dioxide, ozone, nitrogen oxides, and combustion- or traffic-related particulate matter in the atmosphere. These environmental factors can enhance the abundance and induce chemical modifications of allergens, increase oxidative stress in the human body, and skew the immune system toward allergic reactions. In particular, air pollutants can act as adjuvants and alter the immunogenicity of allergenic proteins, while climate change affects the atmospheric abundance and human exposure to bioaerosols and aeroallergens. To fully understand and effectively mitigate the adverse effects of air pollution and climate change on allergic diseases, several challenges remain to be resolved. Among these are the identification and quantification of immunochemical reaction pathways involving allergens and adjuvants under relevant environmental and physiological conditions.

Impaired barrier function in patients with house dust mite-induced allergic rhinitis is accompanied by decreased occludin and zonula occludens-1 expression

BACKGROUND

Tight junction (TJ) defects have recently been associated with asthma and chronic rhinosinusitis. The expression, function, and regulation of nasal epithelial TJs remain unknown in patients with allergic rhinitis (AR).

OBJECTIVE

We investigated the expression, function, and regulation of TJs in the nasal epithelium of patients with house dust mite (HDM)-induced AR and in an HDM-induced murine model of allergic airway disease.

METHODS

Air-liquid interface cultures of primary nasal epithelial cells of control subjects and patients with HDM-induced AR were used for measuring transepithelial resistance and passage to fluorescein isothiocyanate-dextran 4 kDa (FD4). Ex vivo transtissue resistance and FD4 permeability of nasal mucosal explants were measured. TJ expression was evaluated by using real-time quantitative PCR and immunofluorescence. In addition, the effects of IL-4, IFN-γ, and fluticasone propionate (FP) on nasal epithelial cells were investigated in vitro. An HDM murine model was used to study the effects of allergic inflammation and FP treatment on transmucosal passage of FD4 in vivo.

RESULTS

A decreased resistance in vitro and ex vivo was found in patients with HDM-induced AR, with increased FD4 permeability and reduced occludin and zonula occludens-1 expression. AR symptoms correlated inversely with resistance in patients with HDM-induced AR. In vitro IL-4 decreased transepithelial resistance and increased FD4 permeability, whereas IFN-γ had no effect. FP prevented IL-4-induced barrier dysfunction in vitro. In an HDM murine model FP prevented the allergen-induced increased mucosal permeability.

CONCLUSION

We found impaired nasal epithelial barrier function in patients with HDM-induced AR, with lower occludin and zonula occludens-1 expression. IL-4 disrupted epithelial integrity in vitro, and FP restored barrier function. Better understanding of nasal barrier regulation might lead to a better understanding and treatment of AR.

Latest developments in allergic rhinitis in Allergy for clinicians and researchers

Research efforts in allergic rhinitis have always been intense. Over the past 3 years, numerous breakthroughs in basic science and clinical research have been made, augmenting our understanding of this condition that afflicts a significant proportion of the global population. New epidemiological findings, novel insights into the molecular and cellular mechanisms of allergy, enhancement of current developmental theories, new concepts of the goals and endpoints of management, and latest therapeutic modalities that includes the harnessing of information technology and big data are some areas where important advances were made. We attempt to bring you a summary of the key research advances made in the field of allergic rhinitis from 2013 to 2015.

Expression of Toll-like receptors in nasal epithelium in allergic rhinitis

Toll‐like receptors (TLRs) are important in barrier homeostasis, but their role in airborne allergies is not fully understood. The aim was to evaluate baseline and allergen‐induced expression of TLR proteins in nasal epithelium during allergic rhinitis. Nineteen otherwise healthy non‐smoking volunteers both allergic to birch pollen and non‐allergic controls were enrolled. We took nasal biopsies before and after off‐seasonal intranasal birch pollen or diluent challenge. The expression of epithelial TLR1‐7, TLR9‐10, and MyD88 proteins was immunohistochemically evaluated from the nasal biopsies. The TLR1‐3 and TLR5‐10 mRNAs were observed by RNA‐microarray. Baseline epithelial expression of TLR proteins was wide and identical in controls and atopics. After off‐seasonal intranasal birch pollen challenge, a negative change in the expression score of TLR1 and TLR6 proteins was detected in the atopic group. TLR mRNA expression was not affected by birch pollen challenge. Nasal epithelium seems to express all known TLRs. The mechanisms by which TLR1, and TLR6 proteins could affect pollen allergen transport need further studies.

Ligand Recognition of the Major Birch Pollen Allergen Bet v 1 is Isoform Dependent

Each spring millions of patients suffer from allergies when birch pollen is released into the air. In most cases, the major pollen allergen Bet v 1 is the elicitor of the allergy symptoms. Bet v 1 comes in a variety of isoforms that share virtually identical conformations, but their relative concentrations are plant-specific. Glycosylated flavonoids, such as quercetin-3-O-sophoroside, are the physiological ligands of Bet v 1, and here we found that three isoforms differing in their allergenic potential also show an individual, highly specific binding behaviour for the different ligands. This specificity is driven by the sugar moieties of the ligands rather than the flavonols. While the influence of the ligands on the allergenicity of the Bet v 1 isoforms may be limited, the isoform and ligand mixtures add up to a complex and thus individual fingerprint of the pollen. We suggest that this mixture is not only acting as an effective chemical sunscreen for pollen DNA, but may also play an important role in recognition processes during pollination.

Clinical and laboratory studies of the fate of intranasal allergen

BACKGROUND

The precise way in which allergen is handled by the nose is unknown. The objective of this study was to determine recovery of Der p 1 allergen following nasal administration and to determine whether Der p 1 can be detected in nasal biopsies after natural exposure and nasal challenge to allergen.

METHODS

(1) 20 nonatopic non-rhinitics were challenged with Der p 1 and recovery was measured by ELISA in the nasal wash, nasal mucus and induced sputum up to 30 minutes. Particulate charcoal (<40 μm) served as control. (2) In 8 subjects (5 atopics), 30 to 60 minutes after challenge histological localisation of Der p 1 in the nasal mucosal epithelium, subepithelial mucous glands and lamina propria was performed. Co-localisation of Der p 1 with macrophages and IgE-positive cells was undertaken.

RESULTS

(1) Less than 25% of total allergen was retrievable after aqueous or particulate challenge, most from the nasal mucus during 1-5 min after the challenge. The median of carbon particles recovered was 9%. (2) Prechallenge Der p 1 staining was associated with the epithelium and subepithelial mucous glands. After challenge there was a trend for greater Der p 1 deposition in atopics, but both atopics and nonatopics showed increases in the number of Der p 1 stained cells and stained tissue compartments. In atopics, increased eosinophils, macrophages and IgE positive cells co-localized with Der p 1 staining.

CONCLUSIONS

Der p 1 allergen is detected in nasal tissue independent of atopic status after natural exposure. After challenge the nose effectively retains allergen, which remains mucosally associated; in atopics there is greater Der p 1 deposition and inflammatory response than in nonatopics. These results support the hypothesis that nasal mucus and tissue act as a reservoir for the inhaled Der p 1 allergen leading to a persistent allergic inflammatory response in susceptible individuals.

Infection with Rhinovirus Facilitates Allergen Penetration Across a Respiratory Epithelial Cell Layer

BACKGROUND

Rhinovirus infections are a major risk factor for asthma exacerbations. We sought to investigate in an in vitro system whether infection with human rhinovirus reduces the integrity and barrier function of a respiratory epithelial cell layer and thus may influence allergen penetration.

METHODS

We cultured the human bronchial epithelial cell line 16HBE14o- in a transwell culture system as a surrogate of respiratory epithelium. The cell monolayer was infected with human rhinovirus 14 at 2 different doses. The extent and effects of transepithelial allergen penetration were assessed using transepithelial resistance measurements and a panel of (125)I-labeled purified recombinant respiratory allergens (rBet v 1, rBet v 2, and rPhl p 5).

RESULTS

Infection of respiratory cell monolayers with human rhinovirus decreased transepithelial resistance and induced a pronounced increase in allergen penetration.

CONCLUSIONS

Our results indicate that infection with rhinovirus damages the respiratory epithelial barrier and allows allergens to penetrate more efficiently into the subepithelial tissues where they may cause increased allergic inflammation.

IL-5, IL-8 and MMP -9 levels in exhaled breath condensate of atopic and nonatopic asthmatic children

RATIONALE

Asthma is a heterogeneous disease, and a great majority of pediatric patients with asthma demonstrate atopic characteristics and develop a Th2 type cytokine response. Nonatopic asthma, on the other hand, is seen more rarely.

METHODS

In this study, levels of IL-5, IL-8 and MMP-9 were measured in exhaled breath condensate (EBC) of the subjects to demonstrate the extent of tissue damage as well as eosinophilic and neutrophilic inflammation in children with atopic and nonatopic asthma. A total of 37 children with atopic asthma and 37 children with nonatopic asthma were enrolled in the study. Patients who exhibited protease positive aeroallergen (House dust mite, mould mix, olea, grass mix) sensitivity in allergen skin prick test were included in the atopic asthma group. To evaluate the EBC, the fluid content of the breath was collected by having the patients exhale into an EBC device, after which the IL-5, IL-8 and MMP-9 levels were assayed using the ELISA method.

RESULTS

The atopic asthmatics exhibited significantly higher IL-5 levels in their EBC samples than the nonatopic asthmatics (0.271 [0.198-0.489] pg/ml and 0.198 [0.125-0.344] pg/ml, respectively, p = 0.04), while no significant differences were observed in the levels of IL-8 and MMP-9 in the EBC samples of the atopic and nonatopic asthmatics.

CONCLUSIONS

IL-5 levels, as a marker of eosinophilic inflammation, were demonstrated to be higher in the children with atopic asthma when compared to those with nonatopic asthma in EBC. The fact that no significant difference was apparent in the IL-8 levels between the groups suggests that it is the severity of the disease rather than the atopic state that plays an important role in IL-8 levels. Since no difference was recorded between the groups in terms of MMP-9 levels, lung damage in asthma sufferers seems to develop independent of atopia.

Molecular mechanisms of nasal epithelium in rhinitis and rhinosinusitis

Allergic rhinitis, nonallergic rhinitis, and chronic rhinosinusitis are multifactorial upper airway diseases with high prevalence. Several genetic and environmental factors are proposed to predispose to the pathogenesis of the inflammatory upper airway diseases. Still, the molecular mechanisms leading toward the onset and progression of upper airway diseases are largely unknown. The upper airway epithelium has an important role in sensing the environment and regulating the inhaled air. As such, it links environmental insults to the host immunity. Human sinonasal epithelium serves as an excellent target for observing induced early-phase events, in vivo, and with a systems biological perspective. Actually, increasing number of investigations have provided evidence that altered homeostasis in the sinonasal epithelium might be important in the chronic upper airway inflammation.

EGR-1 and DUSP-1 are important negative regulators of pro-allergic responses in airway epithelium

BACKGROUND

Primary nasal epithelium of house dust mite allergic individuals is in a permanently activated inflammatory transcriptional state.

OBJECTIVE

To investigate whether a deregulated expression of EGR-1 and/or DUSP-1, two potential negative regulators of pro-inflammatory responses, could contribute to the activation of the inflammatory state.

METHODS

We silenced the expression of EGR-1 or DUSP-1 in the airway epithelial cell line NCI-H292. The cell lines were stimulated in a 24-h time course with the house dust mite allergen or poly(I:C). RNA expression profiles of cytokines were established using q-PCR and protein levels were determined in supernatants with ELISA.

RESULTS

The shRNA-mediated gene silencing reduced expression levels of EGR-1 by 92% (p<0.0001) and of DUSP-1 by 76% (p<0.0001). Both mutant cells lines showed an increased and prolonged response to the HDM allergen. The mRNA induction of IL-6 was 4.6 fold (p=0.02) and 2.4 fold higher (p=0.01) in the EGR-1 and DUSP-1 knock-down, respectively when compared to the induced levels in the control cell line. For IL-8, the induction levels were 4.6 fold (p=0.01) and 13.0 (p=0.001) fold higher. The outcome was largely similar, yet not identical at the secreted protein levels. Furthermore, steroids were able to suppress the poly(I:C) induced cytokine levels by 70-95%.

CONCLUSIONS

Deregulation of EGR-1 and/or DUSP-1 in nasal epithelium could be responsible for the prolonged activated transcriptional state observed in vivo in allergic disease. This could have clinical consequences as cytokine levels after the steroid treatment in EGR-1 or DUSP-1 knock-down remained higher than in the control cell line.

The contribution of biotechnology toward progress in diagnosis, management, and treatment of allergic diseases

'Biotechnology' has been intuitively used by humans since thousands of years for the production of foods, beverages, and drugs based on the experience without any scientific background. However, the golden era of this discipline emerged only during the second half of the last century. Incredible progresses have been achieved on all fields starting from the industrialization of the production of foods to the discovery of antibiotics, the decipherment of the genetic code, and rational approaches to understand and define the status we now call 'healthy'. The extremely complex interactions between genetic background, life style, and environmental factors influencing our continuously increasing life span have become more and more evident and steadily generate new questions which are only partly answered. Here, we try to summarize the contribution of biotechnology to our understanding, control, and cure of IgE-mediated allergic diseases. We are aware that a review of such a vast topic can never cover all aspects of the progress achieved in the different fields.

Synergy between TLR-2 and TLR-3 signaling in primary human nasal epithelial cells

INTRODUCTION

Although we have a detailed understanding of how single microbial derived triggers activate specialized Toll-like receptors (TLR) on airway epithelial cells, we know little of how these receptors react in a more complex environment. In everyday life, nasal epithelial cells are exposed to multiple TLR agonists, therefore we explored whether exposure to one trigger could affect the responsiveness to another TLR trigger.

METHODS

Primary nasal epithelium from healthy individuals and the bronchial epithelium cell line NCI-H292 were exposed in vitro to different TLR specific agonists. The effect on the expression of different TLRs was determined using the q-PCR. We also evaluated the effect of TLR-3 stimulation on TLR-2, functionally using ELISA to determine levels of secreted mediators.

RESULTS

Stimulation of airway epithelial cells with a specific TLR agonist affects gene expression of other TLRs. In primary nasal epithelium, poly(I:C) challenge results in an up-regulation of the TLR-1, TLR-2, and TLR-3 genes and reduction of expression of TLR-5. Poly(I:C) induced activation of TLR-2 contributes to stronger cell responses to a TLR-2 agonist and regulation of these synergistic responses may take place at the mRNA level of IL-6 and IL-8. The effect of TLR-3 stimulation on TLR-2 functionality and most of the effects on the expression of other TLRs could be replicated in NCI-H292. Poly(I:C) failed to up-regulate TLR-1 and showed an additional up-regulation of TLR-4.

CONCLUSION

Our data suggest that to better understand TLR mediated innate responses we need to consider the impact of the presence of multiple triggers.

Allergic sensitization and the environment: latest update

The prevalence of asthma and other allergic diseases is still increasing both in developed and developing countries. Allergic sensitization against common inhalant allergens is common and, although not sufficient, a necessary step in the development of allergic diseases. Despite a small number of proteins from certain plants and animals being common allergens in humans, we still do not fully understand who will develop sensitization and to which allergens. Environmental exposure to these allergens is essential for the development of sensitization, but what has emerged clearly in the literature in the recent years is that the adjuvants to which an individual is exposed at the same time as the allergen are probably an equally important determinant of the immune response to the allergen. These adjuvants act on all steps in the development of sensitization from modifying epithelial barriers, to facilitating antigen presentation, to driving T-cell responses, to altering mast cell and basophil hyperreactivity. The adjuvants come from biogenic sources, including microbes and the plants and animals that produce the allergens, and from man-made sources (anthropogenic), including unintended by-products of combustion and chemicals now ubiquitous in modern life. As we better understand how individuals are exposed to these adjuvants and how the exposure influences the likelihood of an allergic response, we may be able to design individual and community-level interventions that will reverse the increase in allergic disease prevalence, but we are not there yet.

Clinical view on the importance of dendritic cells in asthma

Allergic asthma is characterized by airway hyperresponsiveness and inflammation and may lead to airway remodeling in uncontrolled cases. Genetic predisposition to an atopic phenotype plays a major component in the pathophysiology of asthma. However, with tremendous role of epigenetic factors and environmental stimuli in precipitating an immune response, the underlying pathophysiological mechanisms are complicated. Dendritic cells are principal antigen-presenting cells and initiators of the immune response in allergic asthma. Their phenotype, guided by multiple factors may dictate the immune reaction to an allergic or tolerogenic response. Involvement of the local cytokine milieu, microbiome and interplay between immune cells add dimension to the fate of immune response. In addition to allergen exposure, these factors modulate DC phenotype and function. In this article, integration of many factors and pathways associated with the recruitment and activation of DCs in the pathophysiology of allergic asthma is presented in a clinical and translational manner.

Silencing of poly(ADP-ribose) polymerase-1 suppresses hyperstretch-induced expression of inflammatory cytokines in vitro

In addition to biochemical stimuli, physical forces also play a critical role in regulating the structure, function, and metabolism of the lung. Hyperstretch can induce the inflammatory responses in asthma, but the mechanism remains unclear. Poly(ADP-ribose) polymerase-1 (PARP-1) is a nuclear enzyme that can regulate a variety of inflammatory cytokines expression. In the present study, we aimed to investigate the role and mechanism of PARP-1 in mechanical stretch-induced inflammation in human bronchial epithelial cells (HBEpiCs). HBEpiCs were simulated by mechanical stretch and cells under static were used as the control. PARP-1 expression was interfered by small interfering RNA. Oxidative stress was evaluated by DHE staining. DNA damage was assessed by comet assay. The results showed that interleukin-8 (IL-8) and vascular cell adhesion molecule-1 (VCAM-1) expression were regulated by hyperstretch in a time-dependent manner. Hyperstretch could increase PARP-1 expression and activity by inducing superoxide production and DNA damage. Silencing of PARP-1 attenuated hyperstretch-induced IL-8 and VCAM-1 up-regulation as well as monocytes adhesion, which were related to the inhibition of nuclear factor-kappa B (NF-κB) translocation. Our study showed that hyperstretch could induce inflammatory response and superoxide production as well as DNA damage in HBEpiCs. PARP-1 silencing decreased IL-8 and VCAM-1 expression, partly through inhibition of NF-κB translocation. PARP-1 played a fundamental role in hyperstretch-induced inflammation. PARP-1 silencing could be used as a potential therapeutic approach to reverse bronchial epithelial inflammation in asthma.

Secret of the major birch pollen allergen Bet v 1: identification of the physiological ligand

The major birch pollen allergen Bet v 1 is the main elicitor of airborne type I allergies and belongs to the PR-10 family (pathogenesis-related proteins 10). Bet v 1 is the most extensively studied allergen, and is well characterized at a biochemical and immunological level; however, its physiological function remains elusive. In the present study, we identify Q3OS (quercetin-3-O-sophoroside) as the natural ligand of Bet v 1. We isolated Q3OS bound to Bet v 1 from mature birch pollen and confirmed its binding by reconstitution of the Bet v 1-Q3OS complex. Fluorescence and UV-visible spectroscopy experiments, as well as HSQC (heteronuclear single-quantum coherence) titration, and the comparison with model compounds, such as quercetin, indicated the specificity of Q3OS binding. Elucidation of the binding site by NMR combined with a computational model resulted in a more detailed understanding and shed light on the physiological function of Bet v 1. We postulate that the binding of Q3OS to Bet v 1 plays an important, but as yet unclear, role during the inflammation response and Bet v 1 recognition by IgE.

High degree of overlap between responses to a virus and to the house dust mite allergen in airway epithelial cells

BACKGROUND

Airway epithelium is widely considered to play an active role in immune responses through its ability to detect changes in the environment and to generate a microenvironment for immune competent cells. Therefore, besides its role as a physical barrier, epithelium affects the outcome of the immune response by the production of various pro-inflammatory mediators.

METHODS

We stimulated airway epithelial cells with viral double stranded RNA analogue poly(I:C) or with house dust mite in a time course of 24 hours. In order to determine cytokines production by stimulated cells, we performed multiplex enzyme linked immunosorbant assay (ELISA).

RESULTS

We demonstrate that the temporal pattern of the genes that respond to virus exposure in airway epithelium resembles to a significant degree their pattern of response to HDM. The gene expression pattern of EGR1, DUSP1, FOSL1, JUN, MYC, and IL6 is rather similar after viral (poly(I:C)) and HDM exposure. However, both triggers also induce a specific response (e.g. ATF3, FOS, and NFKB1). We confirmed these data by showing that epithelial cells produce a variety of similar mediators in response to both poly(I:C) and HDM challenge (IL1-RA, IL-17, IFN-α and MIP1-α), sometimes with a quantitative difference in response (IL2-R, IL-6, IL-8, MCP-1, MIG, and HGF). Interestingly, only four mediators (IL-12, IP-10, RANTES and VEGF) where up-regulated specifically by poly(I:C) and not by HDM. Additionally, we report that pre-exposure to HDM deregulates production of cytokines and mediators in response to poly(I:C).

CONCLUSIONS

Epithelial cells responses to the HDM-allergen and a virus strongly resemble both in gene expression and in protein level explaining why these two responses may affect each other.

Changes in the IgE-reacting protein profiles of Acer negundo, Platanus x acerifolia and Quercus robur pollen in response to ozone treatment

This study aims to investigate the effects of O3 in protein content and immunoglobulin E (IgE)-binding profiles of Acer negundo, Platanus x acerifolia and Quercus robur pollen. Pollen was exposed to O3 in an environmental chamber, at half, equal and four times the limit value for the human health protection in Europe. Pollen total soluble protein was determined with Coomassie Protein Assay Reagent, and the antigenic and allergenic properties were investigated by SDS-PAGE and immunological techniques using patients' sera. O3 exposure affected total soluble protein content and some protein species within the SDS-PAGE protein profiles. Most of the sera revealed increased IgE reactivity to proteins of A. negundo and Q. robur pollen exposed to the pollutant compared with the non-exposed one, while the opposite was observed in P. x acerifolia pollen. So, the modifications seem to be species dependent, but do not necessarily imply that increase allergenicity would occur in atopic individuals.

The impact of allergic rhinitis and asthma on human nasal and bronchial epithelial gene expression

Background

The link between upper and lower airways in patients with both asthma and allergic rhinitis is still poorly understood. As the biological complexity of these disorders can be captured by gene expression profiling we hypothesized that the clinical expression of rhinitis and/or asthma is related to differential gene expression between upper and lower airways epithelium.

Objective

Defining gene expression profiles of primary nasal and bronchial epithelial cells from the same individuals and examining the impact of allergic rhinitis with and without concomitant allergic asthma on expression profiles.

Methods

This cross-sectional study included 18 subjects (6 allergic asthma and allergic rhinitis; 6 allergic rhinitis; 6 healthy controls). The estimated false discovery rate comparing 6 subjects per group was approximately 5%. RNA was extracted from isolated and cultured epithelial cells from bronchial brushings and nasal biopsies, and analyzed by microarray (Affymetrix U133+ PM Genechip Array). Data were analysed using R and Bioconductor Limma package. For gene ontology GeneSpring GX12 was used.

Results

The study was successfully completed by 17 subjects (6 allergic asthma and allergic rhinitis; 5 allergic rhinitis; 6 healthy controls). Using correction for multiple testing, 1988 genes were differentially expressed between healthy lower and upper airway epithelium, whereas in allergic rhinitis with or without asthma this was only 40 and 301 genes, respectively. Genes influenced by allergic rhinitis with or without asthma were linked to lung development, remodeling, regulation of peptidases and normal epithelial barrier functions.

Conclusions

Differences in epithelial gene expression between the upper and lower airway epithelium, as observed in healthy subjects, largely disappear in patients with allergic rhinitis with or without asthma, whilst new differences emerge. The present data identify several pathways and genes that might be potential targets for future drug development.

Nasal hyper-reactivity is a common feature in both allergic and nonallergic rhinitis

BACKGROUND

Nasal hyper-reactivity is an increased sensitivity of the nasal mucosa to various nonspecific stimuli. Both allergic rhinitis (AR) and nonallergic rhinitis (NAR) patients can elicit nasal hyper-reactivity symptoms. Differences in the prevalence or type of nasal hyper-reactivity in AR and NAR patients are largely unknown. In this study, we quantitatively and qualitatively assessed nasal hyper-reactivity in AR and NAR.

METHODS

In the first part, an analysis of a prospectively collected database was performed to reveal patient-reported symptoms of hyper-reactivity. In the second part, cold dry air provocation (CDA) was performed as a hyper-reactivity measure in AR and NAR patients and healthy controls, and symptoms scores, nasal secretions and peak nasal inspiratory flow were measured. Comparisons were made between AR and NAR patients in both studies.

RESULTS

The database analysis revealed high hyper-reactivity prevalence in AR (63.4%) and NAR (66.9%). There were no differences between AR and NAR in terms of the number or type of hyper-reactivity stimuli. Hyper-reactivity to physical stimuli did not exclude a response to chemical stimuli, or vice versa. CDA provocation resulted in a significant increase in rhinitis symptoms and the amount of nasal secretions in AR and NAR patients, but not in controls.

CONCLUSIONS

We found no quantitative or qualitative differences in nasal hyper-reactivity between AR and NAR patients. It is not possible to differentiate NAR subpopulations based on physical or chemical stimuli.

Human antimicrobial peptide LL-37 modulates proinflammatory responses induced by cytokine milieus and double-stranded RNA in human keratinocytes

Epidermal keratinocytes produce proinflammatory cytokines/chemokines upon stimulation with cytokine milieus and Toll-like receptor ligands, which are considered to reflect epidermal environments in inflamed skin. The human antimicrobial peptide LL-37, besides having microbicidal functions, plays multiple roles as a "host defense peptide" in the immune system. Here, we examined the effect of LL-37 on proinflammatory responses induced by double-stranded RNA (dsRNA) and cytokines in primary human keratinocytes. LL-37 inhibited dsRNA-induced production of thymic stromal lymphopoietin (TSLP), CCL5/RANTES, CXCL10/IP-10, and CXCL8/IL-8, which was attributable to interaction between LL-37 and dsRNA, although LL-37 upregulated CXCL8 expression at an earlier time point (8 h). LL-37 inhibited the increase of CXCL10 and CCL5 induced by TNF-α- and/or IFN-γ but enhanced that of CXCL8. LL-37 and Th17 cytokines (IL-17 and IL-22) synergistically upregulated the expression of CXCL8 and IL-6. LL-37 showed the effects above at a high concentration (25 μg/ml, 5.6 μM). We also examined effects of a peptide with a scrambled LL-37 sequence, which has been frequently used as a negative control, and those of another peptide with the reversed LL-37 sequence, activities of which have not been well investigated. Interestingly, the reversed LL-37 had effects similar to LL-37 but the scrambled LL-37 did not. The modulation by LL-37 of the keratinocyte proinflammatory responses induced by cytokine milieus and dsRNA suggests novel roles for LL-37 in skin inflammation such as the promotion of IL17/IL-22/IL-6-associated psoriasis and suppression of TSLP-associated atopic dermatitis.