Background The role of IgE in patients with severe asthma is not fully understood. Objective We sought to investigate whether IgE to Staphylococcus aureus enterotoxins might be relevant to disease ...severity in adult asthmatic patients. Methods Specific IgE antibody concentrations in serum against enterotoxins, grass pollen (GP), and house dust mite allergens and total IgE levels were measured in adult cohorts of 69 control subjects, 152 patients with nonsevere asthma, and 166 patients with severe asthma. Severe asthma was defined as inadequately controlled disease despite high-dose inhaled corticosteroids plus at least 2 other controller therapies, including oral steroids. Results Enterotoxin IgE positivity was significantly greater in patients with severe asthma (59.6%) than in healthy control subjects (13%, P < .001). Twenty-one percent of patients with severe asthma with enterotoxin IgE were considered nonatopic. Logistic regression analyses demonstrated significantly increased risks for enterotoxin IgE–positive subjects to have any asthma (OR, 7.25; 95% CI, 2.7-19.1) or severe asthma (OR, 11.09; 95% CI, 4.1-29.6) versus enterotoxin IgE–negative subjects. The presence of GP or house dust mite IgE antibodies was not associated with either significantly increased risk for asthma or severity. Oral steroid use and hospitalizations were significantly increased in patients with enterotoxin IgE and nonatopic asthma. GP IgE was associated with a higher FEV1 percent predicted value, and enterotoxin IgE was associated with a lower FEV1 percent predicted value. Conclusions Staphylococcal enterotoxin IgE antibodies, but not IgE against inhalant allergens, are risk factors for asthma severity. We hypothesize that the presence of enterotoxin IgE in serum indicates the involvement of staphylococcal superantigens in the pathophysiology of patients with severe asthma.
Defective epithelial barrier function in asthma Xiao, Chang, PhD; Puddicombe, Sarah M., PhD; Field, Sarah, PhD ...
Journal of allergy and clinical immunology,
09/2011, Letnik:
128, Številka:
3
Journal Article
Recenzirano
Background Asthma is a complex disease involving gene and environment interactions. Although atopy is a strong predisposing risk factor for asthma, local tissue susceptibilities are required for ...disease expression. The bronchial epithelium forms the interface with the external environment and is pivotally involved in controlling tissue homeostasis through provision of a physical barrier controlled by tight junction (TJ) complexes. Objectives To explain the link between environment exposures and airway vulnerability, we hypothesized that epithelial TJs are abnormal in asthma, leading to increased susceptibility to environmental agents. Methods Localization of TJs in bronchial biopsies and differentiated epithelial cultures was assessed by electron microscopy or immunostaining. Baseline permeability and the effect of cigarette smoke and growth factor were assessed by measurement of transepithelial electrical resistance and passage of fluorescently labeled dextrans. Results By using immunostaining, we found that bronchial biopsies from asthmatic subjects displayed patchy disruption of TJs. In differentiated bronchial epithelial cultures, TJ formation and transepithelial electrical resistance were significantly lower ( P < .05) in cultures from asthmatic donors (n = 43) than from normal controls (n = 40) and inversely correlated with macromolecular permeability. Cultures from asthmatic donors were also more sensitive to disruption by cigarette smoke extract. Epidermal growth factor enhanced basal TJ formation in cultures from asthmatic subjects ( P < .01) and protected against cigarette smoke–induced barrier disruption ( P < .01). Conclusions Our results show that the bronchial epithelial barrier in asthma is compromised. This defect may facilitate the passage of allergens and other agents into the airway tissue, leading to immune activation and may thus contribute to the end organ expression of asthma.
Microbes and asthma: Opportunities for intervention Smits, Hermelijn H., PhD; Hiemstra, Pieter S., PhD; Prazeres da Costa, Clarissa, MD, PhD ...
Journal of allergy and clinical immunology,
03/2016, Letnik:
137, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The worldwide incidence and prevalence of asthma continues to increase. Asthma is now understood as an umbrella term for different phenotypes or endotypes, which arise through different ...pathophysiologic pathways. Understanding the many factors contributing to development of the disease is important for the identification of novel therapeutic targets for the treatment of certain asthma phenotypes. The hygiene hypothesis has been formulated to explain the increasing prevalence of allergic disease, including asthma. This hypothesis postulates that decreased exposure at a young age to certain infectious agents as a result of improved hygiene, increased antibiotic use and vaccination, and changes in lifestyle and dietary habits is associated with changes in the immune system, which predispose subjects to allergy. Many microbes, during their coevolution with human subjects, developed mechanisms to manipulate the human immune system and to increase their chances of survival. Improving models of asthma, as well as choosing adequate end points in clinical trials, will lead to a more complete understanding of the underlying mechanisms, thus providing an opportunity to devise primary and secondary interventions at the same time as identifying new molecular targets for treatment. This article reports the discussion and conclusion of a workshop under the auspices of the Netherlands Lung Foundation to extend our understanding of how modulation of the immune system by bacterial, parasitic, and viral infections might affect the development of asthma and to map out future lines of investigation.
Background Surfactant protein D (SP-D) is an essential component of the innate immune defense against pathogens within the airways. SP-D also regulates allergic inflammation and promotes the removal ...of apoptotic cells. SP-D dysregulation is evident in several pulmonary diseases. Our aim was to investigate whether airway and serum levels of SP-D are altered in treatment-resistant severe asthma. Methods SP-D concentrations were measured in matched serum and BAL samples collected from 10 healthy control subjects (HC) and 50 patients with asthma (22 with mild asthma MA and 28 with severe asthma SA). These samples were also evaluated by using Western blot analysis to investigate variations in SP-D size. Results SP-D levels in BAL samples were significantly lower in SA compared with HC and MA ( P < .001) and inversely correlated with BAL eosinophil cationic protein concentrations in SA ( P < .01). Serum SP-D was significantly increased in SA compared with HC and MA ( P < .001), and BAL/serum ratios were significantly lower in SA compared with HC and MA ( P < .001). Reduced SP-D levels in BAL samples, with concomitant increases in serum in SA, were associated with degraded fragments of SP-D in the serum and increased BAL neutrophil counts and lipopolysaccharide levels. Conclusions These findings suggest defective innate immunity within the airways in SA, as reflected by low BAL SP-D concentrations and altered bacterial presence with airway neutrophilia. Furthermore, BAL SP-D leakage into the serum in patients with SA may provide a peripheral blood biomarker, reflecting increased epithelial damage and/or epithelial permeability within the peripheral airways.
Background A disintegrin and metalloprotease 33 (ADAM33) polymorphism is strongly associated with asthma and bronchial hyperresponsiveness. Although considered to be a mesenchymal cell–specific gene, ...recent reports have suggested epithelial expression of ADAM33 in patients with severe asthma. Objectives Because dysregulated expression of ADAM33 can contribute to disease pathogenesis, we characterized the mechanism or mechanisms that control its transcription and investigated ADAM33 expression in bronchial biopsy specimens and brushings from healthy and asthmatic subjects. Methods The ADAM33 promoter and CpG island methylation were analyzed by using bioinformatics, luciferase reporters, and bisulfite sequencing of genomic DNA. Epithelial-mesenchymal transition was induced by using TGF-β1. ADAM33 mRNA was scrutinized in bronchial biopsy specimens and brushings by using reverse transcriptase–quantitative polymerase chain reaction, melt-curve analysis, and direct sequencing. Results The predicted ADAM33 promoter (−550 to +87) had promoter transcriptional activity. Bisulfite sequencing showed that the predicted promoter CpG island (−362 to +80) was hypermethylated in epithelial cells but hypomethylated in ADAM33-expressing fibroblasts. Treatment of epithelial cells with 5-aza-deoxycytidine caused demethylation of the CpG island and induced ADAM33 expression. In contrast, phenotypic transformation of epithelial cells through a TGF-β–induced epithelial-mesenchymal transition was insufficient to induce ADAM33 expression. ADAM33 mRNA was confirmed in bronchial biopsy specimens, but no validated signal was detected in bronchial brushings from healthy or asthmatic subjects. Conclusion The ADAM33 gene contains a regulatory CpG island within its promoter, the methylation status of which tightly controls its expression in a cell type–specific manner. ADAM33 repression is a stable feature of airway epithelial cells, irrespective of disease.
Background Asthma is a chronic inflammatory disease involving diverse cells and mediators whose interconnectivity and relationships to asthma severity are unclear. Objective We performed a ...comprehensive assessment of TH 17 cells, regulatory T cells, mucosal-associated invariant T (MAIT) cells, other T-cell subsets, and granulocyte mediators in asthmatic patients. Methods Sixty patients with mild-to-severe asthma and 24 control subjects underwent detailed clinical assessment and provided induced sputum, endobronchial biopsy, bronchoalveolar lavage, and blood samples. Adaptive and invariant T-cell subsets, cytokines, mast cells, and basophil mediators were analyzed. Results Significant heterogeneity of T-cell phenotypes was observed, with levels of IL-13–secreting T cells and type 2 cytokines increased at some, but not all, asthma severities. TH 17 cells and γδ-17 cells, proposed drivers of neutrophilic inflammation, were not strongly associated with asthma, even in severe neutrophilic forms. MAIT cell frequencies were strikingly reduced in both blood and lung tissue in relation to corticosteroid therapy and vitamin D levels, especially in patients with severe asthma in whom bronchoalveolar lavage regulatory T-cell numbers were also reduced. Bayesian network analysis identified complex relationships between pathobiologic and clinical parameters. Topological data analysis identified 6 novel clusters that are associated with diverse underlying disease mechanisms, with increased mast cell mediator levels in patients with severe asthma both in its atopic (type 2 cytokine–high) and nonatopic forms. Conclusion The evidence for a role for TH 17 cells in patients with severe asthma is limited. Severe asthma is associated with a striking deficiency of MAIT cells and high mast cell mediator levels. This study provides proof of concept for disease mechanistic networks in asthmatic patients with clusters that could inform the development of new therapies.
Background Disease heterogeneity in patients with severe asthma and its relationship to inflammatory mechanisms remain poorly understood. Objective We aimed to identify and replicate ...clinicopathologic endotypes based on analysis of blood and sputum parameters in asthmatic patients. Methods One hundred ninety-four asthmatic patients and 21 control subjects recruited from 2 separate centers underwent detailed clinical assessment, sputum induction, and phlebotomy. One hundred three clinical, physiologic, and inflammatory parameters were analyzed by using topological data analysis and Bayesian network analysis. Results Severe asthma was associated with anxiety and depression, obesity, sinonasal symptoms, decreased quality of life, and inflammatory changes, including increased sputum chitinase 3–like protein 1 (YKL-40) and matrix metalloproteinase (MMP) 1, 3, 8, and 12 levels. Topological data analysis identified 6 clinicopathobiologic clusters replicated in both geographic cohorts: young, mild paucigranulocytic; older, sinonasal disease; obese, high MMP levels; steroid resistant TH 2 mediated, eosinophilic; mixed granulocytic with severe obstruction; and neutrophilic, low periostin levels, severe obstruction. Sputum IL-5 levels were increased in patients with severe particularly eosinophilic forms, whereas IL-13 was suppressed and IL-17 levels did not differ between clusters. Bayesian network analysis separated clinical features from intricately connected inflammatory pathways. YKL-40 levels strongly correlated with neutrophilic asthma and levels of myeloperoxidase, IL-8, IL-6, and IL-6 soluble receptor. MMP1, MMP3, MMP8, and MMP12 levels were associated with severe asthma and were correlated positively with sputum IL-5 levels but negatively with IL-13 levels. Conclusion In 2 distinct cohorts we have identified and replicated 6 clinicopathobiologic clusters based on blood and induced sputum measures. Our data underline a disconnect between clinical features and underlying inflammation, suggest IL-5 production is relatively steroid insensitive, and highlight the expression of YKL-40 in patients with neutrophilic inflammation and the expression of MMPs in patients with severe asthma.
Background Because TNF-α is increased in severe asthma, we hypothesized that TNF-α contributes to barrier dysfunction and cell activation in bronchial epithelial cells. We further hypothesized that ...src-family kinase inhibition would improve barrier function in healthy cells in the presence of TNF-α and directly in cultures of severe asthmatic cells where the barrier is disrupted. Objectives We assessed the effect of TNF-α, with or without src-family kinase inhibitor SU6656, on barrier properties and cytokine release in differentiated human bronchial epithelial cultures. Further, we tested the effect of SU6656 on differentiated primary cultures from severe asthma. Methods Barrier properties of differentiated human bronchial epithelial air-liquid interface cultures from healthy subjects and subjects with severe asthma were assessed with transepithelial electrical resistance and fluorescent dextran passage. Proteins were detected by immunostaining or Western blot analysis and cytokines by immunoassay. Mechanisms were investigated with src kinase and other inhibitors. Results TNF-α lowered transepithelial electrical resistance and increased fluorescent dextran permeability, caused loss of occludin and claudins from tight junctions with redistribution of p120 catenin and E-cadherin from adherens junctions, and also increased endogenous TNF-α, IL-6, IL-1β, IL-8, thymic stromal lymphoprotein, and pro–matrix metalloprotease 9 release. SU6656 reduced TNF-α–mediated paracellular permeability changes, restored occludin, p120, and E-cadherin and lowered autocrine TNF-α release. Importantly, SU6656 improved the barrier properties of severe asthmatic air-liquid interface cultures. Redistribution of E-cadherin and p120 was observed in bronchial biopsies from severe asthmatic airways. Conclusions Inhibiting TNF-α or src kinases may be a therapeutic option to normalize barrier integrity and cytokine release in airway diseases associated with barrier dysfunction.
Background Tissue factor (TF), a primary initiator of blood coagulation, also plays a pivotal role in angiogenesis. TF expression in the airways is associated with asthma, a disease characterized in ...part by subepithelial angiogenesis. Objectives To determine potential sources of TF and the mechanisms of its availability in the lung microenvironment. Methods Normal human bronchial epithelial cells grown in air-liquid interface culture were subjected to a compressive stress of 30 cm H2 O; this is comparable to that generated in the airway epithelium during bronchoconstriction in asthma. Conditioned media and cells were harvested to measure TF mRNA and TF protein. We also tested bronchoalveolar lavage fluid and airway biopsies from asthmatic patients and healthy controls for TF. Results TF mRNA was upregulated 2.2-fold after 3 hours of stress compared with unstressed cells. Intracellular and secreted TF proteins were enhanced 1.6-fold and more than 50-fold, respectively, compared with those of control cells after the onset of compression. The amount of TF in the bronchoalveolar lavage fluid from patients with asthma was found at mean concentrations that were 5 times greater than those of healthy controls. Immunohistochemical staining of endobronchial biopsies identified epithelial localization of TF with increased expression in asthma. Exosomes isolated from the conditioned media of normal human bronchial epithelial cells and the bronchoalveolar lavage fluid of asthmatic subjects by ultracentrifugation contained TF. Conclusions Our in vitro and in vivo studies show that mechanically stressed bronchial epithelial cells are a source of secreted TF and that exosomes are potentially a key carrier of the TF signal.
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