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Glutathione S-transferase M1 modulates allergen-induced NF-?B activation in asthmatic airway epithelium.

ABSTRACT: Glutathione S-transferase M1 (GSTM1) is a phase II enzyme and regulator of inflammatory signaling in airway epithelial cells. We have found upregulation of neutrophilic airway inflammation in atopic asthmatics expressing GSTM1 gene (GSTM1+) compared to GSTM1null asthmatics. We hypothesized that GSTM1 modulates NF-?B activation in bronchial epithelium in atopic asthmatics. We determined regulation of allergen-induced NF-?B activation in bronchial epithelium by GSTM1 in human atopic asthmatics in vivo.Endobronchial biopsies and bronchoalveolar lavage fluid samples were collected from 13 GSTM1+ and 12 GSTM1null human atopic asthmatics at baseline and 24 h after segmental allergen challenge. A quantitative analysis of NF-?B activation in airway epithelium was accomplished using a polyclonal antibody against the phosphorylated p65 component of NF-?B. Elastase-positive neutrophils in the bronchial wall were quantified.Postallergen neutrophilia in airway subepithelium and epithelial lining fluid was greater in GSTM1+ compared to GSTM1null asthmatics. Airway eosinophilia was similar in GSTM1+ and GSTM1null asthmatics. Allergen-provoked NF-?B induction in bronchial epithelium was significantly greater in GSTM1+ compared to GSTM1null asthmatics. Activation of NF-?B activation in airway epithelial cells correlated with interleukin-8 concentrations and absolute neutrophil numbers in bronchoalveolar lavage fluid in GSTM1+ but not GSTM1null asthmatics.Allergen-induced neutrophilic airway inflammation in GSTM1+ asthmatics is associated with NF-?B activation in airway epithelial cells in vivo. These novel data provide a potential mechanism of the genomic link between GSTM1 polymorphism and airway neutrophilia in atopic asthma.

SUBMITTER: Polosukhin VV

PROVIDER: S-EPMC4317365 | biostudies-literature | 2014 Dec

REPOSITORIES: biostudies-literature

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Glutathione S-transferase M1 modulates allergen-induced NF-κB activation in asthmatic airway epithelium.

Polosukhin V V VV Polosukhin I V IV Hoskins A A Han W W Abdolrasulnia R R Blackwell T S TS Dworski R R

Allergy 20141001 12

<h4>Background</h4>Glutathione S-transferase M1 (GSTM1) is a phase II enzyme and regulator of inflammatory signaling in airway epithelial cells. We have found upregulation of neutrophilic airway inflammation in atopic asthmatics expressing GSTM1 gene (GSTM1+) compared to GSTM1null asthmatics. We hypothesized that GSTM1 modulates NF-κB activation in bronchial epithelium in atopic asthmatics. We determined regulation of allergen-induced NF-κB activation in bronchial epithelium by GSTM1 in human at ...[more]

PMID: 25118837

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Project description:RationaleAsthma is a heterogeneous lung disorder characterized by airway inflammation and airway dysfunction, manifesting as hyperresponsiveness and obstruction. Glutathione S-transferase M1 (GSTM1) is a multifunctional phase II enzyme and regulator of stress-activated cellular signaling relevant to asthma pathobiology. A common homozygous deletion polymorphism of the GSTM1 gene eliminates enzyme activity.ObjectivesTo determine the effect of GSTM1 on airway inflammation and reactivity in adults with established atopic asthma in vivo.MethodsNineteen GSTM1 wild-type and eighteen GSTM1-null individuals with mild atopic asthma underwent methacholine and inhaled allergen challenges, and endobronchial allergen provocations through a bronchoscope.Measurements and main resultsThe influx of inflammatory cells, panels of cytokines and chemokines linked to asthmatic inflammation, F(2)-isoprostanes (markers of oxidative stress), and IgE were measured in bronchoalveolar lavage fluid at baseline and 24 hours after allergen instillation. Individuals with asthma with the GSTM1 wild-type genotype had greater baseline and allergen-provoked airway neutrophilia and concentrations of myeloperoxidase than GSTM1-null patients. In contrast, the eosinophilic inflammation was unaffected by GSTM1. The allergen-stimulated generation of acute-stress and proneutrophilic mediators, tumor necrosis factor-α, CXCL-8, IL-1β, and IL-6, was also greater in the GSTM1 wild-type patients. Moreover, post-allergen airway concentrations of IgE and neutrophil-generated mediators, matrix metalloproteinase-9, B-cell activating factor, transforming growth factor-β1, and elastase were higher in GSTM1 wild-type individuals with asthma. Total airway IgE correlated with B-cell activating factor concentrations. In contrast, levels of F(2)-isoprostane were comparable in both groups. Finally, GSTM1 wild-type individuals with asthma required lower threshold concentrations of allergen to produce bronchoconstriction.ConclusionsThe functional GSTM1 genotype promotes neutrophilic airway inflammation in humans with atopic asthma in vivo.

Project description:Glutathione S-transferase P1 is a Phase II cytoprotective and detoxifying enzyme that is widely expressed in human airways. The glutathione S-transferase P1 Ile105Val polymorphism has been linked with atopic disorders and asthma. Yet, little remains known about the regulation of allergic inflammation by glutathione S-transferase P1 in human asthmatics.To establish the effect of the glutathione S-transferase P1 Ile105Val polymorphism on allergen-induced airway inflammation and oxidant stress, and non-specific bronchial hyperresponsiveness to methacholine and reactivity to specific allergen in mild human atopic asthmatics in vivo.Five Val(105)/Val(105) , twelve Val(105)/Ile(105) and twenty Ile(105)/Ile(105) mild atopic asthmatics underwent methacholine challenge, inhaled allergen challenge and endobronchial allergen provocation through a bronchoscope. A panel of inflammatory cytokines and chemokines, F2 -isoprostanes and isofuranes, markers of oxidative stress, thromboxane B2 and immunoglobulin E were measured in bronchoalveolar lavage fluid at baseline and 24 h after allergen instillation.Asthmatics with glutathione S-transferase P1 Val(105)/Val(105) compared with asthmatics with the glutathione S-transferase P1 Val(105)/Ile(105) and Ile(105)/Ile(105) had greater generation of acute phase cytokines (TNF-?, IL-6, CXCL8), IL-12, CCL11, thromboxane B2 and immunoglobulin E at 24 h after local allergen challenge. The GSTP1 genotype had no effect on airway hyperresponsiveness to methacholine and the reactivity to specific allergen.The glutathione S-transferase P1 Ile105Val polymorphism markedly modifies allergen-provoked airway inflammation in atopic asthmatics in vivo. Modulation of the biochemical milieu in response to allergen provides a mechanistic explanation for regulatory effects of glutathione S-transferase P1 polymorphism on airway pathophysiology, and may guide improvement of future therapeutic methods in human atopic asthmatics. These findings must me confirmed in a larger study population of asthmatics with various ethnicities.

Project description:Asthma is an inflammatory condition for which anti-inflammatory glucocorticoids are the standard of care. However, similar efficacy has not been shown for agents targeting inflammatory cells and pathways. This suggests a noninflammatory cell contributor (e.g., epithelium) to asthmatic inflammation. Herein, we sought to define the intrinsic and glucocorticoid-affected properties of asthmatic airway epithelium compared with normal epithelium. Human primary differentiated normal and asthmatic airway epithelia were cultured in glucocorticoid-free medium beginning at -48 hours. They were pulsed with dexamethasone (20 nM) or vehicle for 2 hours at -26, -2, +22, and +46 hours. Cultures were mechanically scrape-wounded at 0 hours and exposed continuously to bromodeoxyuridine (BrdU). Cytokine secretions were analyzed using cytometric bead assays. Wound regeneration/mitosis was analyzed by microscopy and flow cytometry. Quiescent normal (n = 3) and asthmatic (n = 6) epithelia showed similar minimal inflammatory cytokine secretion and mitotic indices. After wounding, asthmatic epithelia secreted more basolateral TGF-?1, IL-10, IL-13, and IL-1? (P < 0.05) and regenerated less efficiently than normal epithelia (+48 h wound area reduction = [mean ± SEM] 50.2 ± 7.5% versus 78.6 ± 7.7%; P = 0.02). Asthmatic epithelia showed 40% fewer BrdU(+) cells at +48 hours (0.32 ± 0.05% versus 0.56 ± 0.07% of total cells; P = 0.03), and those cells were more dyssynchronously distributed along the cell cycle (52 ± 10, 25 ± 4, 23 ± 7% for G1/G0, S, and G2/M, respectively) than normal epithelia (71 ± 1, 12 ± 2, and 17 ± 2% for G1/G0, S, and G2/M, respectively). Dexamethasone pulses improved asthmatic epithelial inflammation and regeneration/mitosis. In summary, we show that inflammatory/fibrogenic cytokine secretions are correlated with dyssynchronous mitosis upon injury. Intermittent glucocorticoids simultaneously decreased epithelial cytokine secretions and resynchronized mitosis. These data, generated in an airway model lacking inflammatory cells, support the concept that epithelium contributes to asthmatic inflammation.

Dataset Information

Glutathione S-transferase M1 modulates allergen-induced NF-?B activation in asthmatic airway epithelium.

Publications

Glutathione S-transferase M1 modulates allergen-induced NF-κB activation in asthmatic airway epithelium.

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