Model Of Chronic Allergic Asthma Research Articles

A methanolic extract of Eclipta prostrata (L.) L. decreases inflammation in a murine model of chronic allergic asthma via inhibition of the NF-kappa-B pathway

Ethnopharmacological relevanceEclipta prostrata (L.) L. is a medicinal plant used by many ethnic groups in Brazil to treat respiratory diseases, hepatitis and the bites of venomous animals. A methanolic extract of E. prostrata (MEEP), the major components of which are wedelolactone (WED) and demethylwedelolactone (DMW), exhibited anti-inflammatory activity in acute asthma models but the effects on lung inflammation and the mechanisms of action of MEEP in a chronic asthma model are not known. Aim of the studyTo study the effects of MEEP in vivo using a chronic ovalbumin (OVA)-induced allergic asthma model in mice. Materials and methodsThe identities of WED and DMW in MEEP were confirmed and the concentrations determined by liquid chromatography and tandem mass spectrometry. Male Balb/c mice were sensitized and challenged with OVA and experimental animals were treated with MEEP (100, 250 or 500 mg/kg) while control animals were treated with dexamethasone (2 mg/kg) or normal saline. Bronchial hyperresponsiveness, total and differential cell counts in bronchoalveolar lavage (BAL), and the production of Th2 cytokines in lung homogenates were assessed. Lung inflammation and mucus production were evaluated by histological analysis while nuclear factor kappa-B (NF-κB) activation was assessed immunohistochemically. ResultsConcentrations of WED and DMW in MEEP were 5.12% and 1.04%, respectively. Treatments with MEEP (250 or 500 mg/kg) significantly decreased bronchial hyperresponsiveness, reduced total cell and eosinophil counts in BAL and IL-4 concentrations in lung homogenate, and inhibited NF-κB activation. Treatment with MEEP at 500 mg/kg reduced the level of IL-5 in lung homogenates but did not decrease IL-13 concentration or mucus production. ConclusionsMEEP attenuated bronchial hyperresponsiveness and decreased lung and airway inflammation in a chronic asthma model in mice. The mechanism of action involves inhibition of NF-κB activation, most likely associated with the presence of the coumestans WED and DMW. These results support the ethnopharmacological evidence for the use of E. prostrata against asthma and other respiratory inflammatory diseases.

Ketone body augmentation decreases methacholine hyperresponsiveness in mouse models of allergic asthma.

Individuals with allergic asthma exhibit lung inflammation and remodeling accompanied by methacholine hyperresponsiveness manifesting in proximal airway narrowing and distal lung tissue collapsibility, and they can present with a range of mild-to-severe disease amenable or resistant to therapeutic intervention, respectively. There remains a need for alternatives or complements to existing treatments that could control the physiologic manifestations of allergic asthma. Our aim was to examine the hypothesis that because ketone bodies elicit anti-inflammatory activity and are effective in mitigating the methacholine hyperresponsiveness associated with obese asthma, increasing systemic concentrations of ketone bodies would diminish pathologic outcomes in asthma-relevant cell types and in mouse models of allergic asthma. We explored the effects of ketone bodies on allergic asthma-relevant cell types (macrophages, airway epithelial cells, CD4 T cells, and bronchial smooth muscle cells) in vitro as well as in vivo by using preclinical models representative of several endotypes of allergic asthma to determine whether promotion of ketosis through feeding a ketogenic diet or providing a ketone precursor or a ketone ester dietary supplement could affect immune and inflammatory parameters as well as methacholine hyperresponsiveness. In a dose-dependent manner, the ketone bodies acetoacetate and β-hydroxybutyrate (BHB) decreased proinflammatory cytokine secretion from mouse macrophages and airway epithelial cells, decreased house dust mite (HDM) extract-induced IL-8 secretion from human airway epithelial cells, and decreased cytokine production from polyclonally and HDM-activated T cells. Feeding a ketogenic diet, providing a ketone body precursor, or supplementing the diet with a ketone ester increased serum BHB concentrations and decreased methacholine hyperresponsiveness in several acute HDM sensitization and challenge models of allergic asthma. A ketogenic diet or ketone ester supplementation decreased methacholine hyperresponsiveness in an HDM rechallenge model of chronic allergic asthma. Ketone ester supplementation synergized with corticosteroid treatment to decrease methacholine hyperresponsiveness in an HDM-driven model of mixed-granulocytic severe asthma. HDM-induced morphologic changes in bronchial smooth muscle cells were inhibited in a dose-dependent manner by BHB, as was HDM protease activity. Increasing systemic BHB concentrations through dietary interventions could provide symptom relief for several endotypes of allergic asthmatic individuals through effects on multiple asthma-relevant cells.

Effects of human adipose tissue- and bone marrow-derived mesenchymal stem cells on airway inflammation and remodeling in a murine model of chronic asthma

It is challenging to overcome difficult-to-treat asthma, and cell-based therapies are attracting increasing interest. We assessed the effects of mesenchymal stem cell (MSC) treatments using a murine model of chronic ovalbumin (OVA)-challenged asthma. We developed a murine model of chronic allergic asthma using OVA sensitization and challenge. Human adipose-derived MSCs (hADSCs) or human bone marrow-derived MSCs (hBMSCs) were administered. We measured the levels of resistin-like molecule-β (RELM-β). We also measured RELM-β in asthma patients and normal controls. OVA-challenged mice exhibited increased airway hyper-responsiveness, inflammation, and remodeling. hBMSC treatment remarkably decreased airway hyper-responsiveness but hADSC treatment did not. Both MSCs alleviated airway inflammation, but hBMSCs tended to have a more significant effect. hBMSC treatment reduced Th2-cytokine levels but hADSC treatment did not. Both treatments reduced airway remodeling. The RELM-β level decreased in the OVA-challenged control group, but increased in both treatment groups. We found that the serum level of RELM-β was lower in asthma patients than controls. MSC treatments alleviated the airway inflammation, hyper-responsiveness, and remodeling associated with chronic asthma. hBMSCs were more effective than hADSCs. The RELM-β levels increased in both treatment groups; the RELM-β level may serve as a biomarker of MSC treatment efficacy.

Montelukast Sodium Formulation Containing Green Tea Extract to Reduce the Oxidative Stress in Guinea Pig Model of Chronic Allergic Asthma.

The rationale of this study is that, treatment of asthmatic Guinea pig with combined administration of Montelukast sodium and Green Tea Extract (GTE) as a single capsule will mitigate the inflammatory injury in the airways and weaken the asthmatic response. Recent patents for the treatment of asthma researched a polyphenolic alternatives for antiasthmatic combination therapy, especially for those patients who remains unresponsive or poorly responsive for current asthma therapy (US7232585B2). Synergistic activity of green tea polyphenols and therapeutic, prophylatic agents are also reported in some recent patents (US20120172423A1, US20150320696A1). The present work is therefore aimed, to study the effect of Montelukast Sodium capsules coformulated with GTE on oxidative stress markers including Malondialdehyde (MDA), Glutathione (GSH) in different organs and Oxygen Radical Absorbance Capacity (ORAC) assay in plasma. Guinea pigs were placed in histamine chamber and exposed to an aerosol challenge of 0.2% w/v histamine dihydrochloride in distilled water using pressurized air driven nebulizer at a pressure of 0.05 MPa-0.106 MPa for one week. After that, they were divided in to four groups of three each; control, asthmatic control, asthmatic treated with marketed preparation and asthmatic received developed capsules. After oral administration of formulations for three days, pigs were scarificed and oxidative stress markers level including cytoarchitectural manifestation in tissues was studied. In comparison with the healthy control group, MDA level of the asthmatic animal liver and lung was found to be elevated as 0.059 ± 0.031(p < 0.002) and 0.802 ± 0.310 (p < 0.005) respectively, whereas GSH level was declined as 13.223 ± 1.485 (p < 0.0001) in liver and 3.037 ± 0.282 (p < 0.0004) in lung tissues. TAC of asthmatic animal plasma was low as 2.132 ± 0.986 mM Trolox Eq/L (p < 0.009). The level of these biomarkers reverts back towards normal after treatment with marketed and developed formulation, although treatment with developed formulation was more efficacious since it was coformulated with GTE, which acts as an adjuvant for the management of inflammatory disease like asthma. It is contemplated that, use of GTE as an adjuvant to anti leukotriene drug played a significant role in asthma management by reducing oxidant injury. Since, studies in animals do not directly translate to human biology, further multi-control studies with better sampled patient population and more number of patients are needed.

Thymic stromal lymphopoietin contribution to the recruitment of circulating fibrocytes to the lung in a mouse model of chronic allergic asthma

ABSTRACTObjective: Fibrocyte localization to the airways and thymic stromal lymphopoietin (TSLP) overexpression in the lung are features of severe asthma. The aim of this study was to determine whether TSLP contributes to fibrocyte trafficking and airway remodeling in a mouse model of allergic asthma. Methods: We established a chronic asthma animal model by administering house dust mite (HDM) extracts intranasally for up to 5 consecutive weeks. Mouse anti-TSLP monoclonal antibody (mAb) was given intraperitoneally starting the 4th week. Fluorescence-labeled CD34/collagen I (Col I)-dual-positive fibrocytes were examined by confocal microscopy. The level of TGF-β1 in the bronchoalveolar lavage (BAL) fluid was determined by ELISA. Results: We found significantly increased levels of TSLP and TGF-β1 in the lung of the mice subjected to repeated allergen exposure, which was accompanied by increased number of fibrocytes in the sub-epithelial zone and the BAL fluid. However, blocking TSLP markedly decreased the production of TGF-β1, reduced the number of fibrocytes and subsequently prevented alterations of both airway and vascular structures. Conclusions: Our data suggested that TSLP might function in airway remodeling by promoting circulating fibrocyte recruitment to the lung in the mice subjected to chronic allergen exposure. These results provide a better rationale for targeting the interaction between TSLP and fibrocytes as a therapeutic approach for chronic allergic asthma.

IL-10 and regulatory T cells cooperate in allergen-specific immunotherapy to ameliorate allergic asthma.

Human studies demonstrated that allergen-specific immunotherapy (IT) represents an effective treatment for allergic diseases. IT involves repeated administration of the sensitizing allergen, indicating a crucial contribution of T cells to its medicinal benefit. However, the underlying mechanisms of IT, especially in a chronic disease, are far from being definitive. In the current study, we sought to elucidate the suppressive mechanisms of IT in a mouse model of chronic allergic asthma. OVA-sensitized mice were challenged with OVA or PBS for 4 wk. After development of chronic airway inflammation, mice received OVA-specific IT or placebo alternately to airway challenge for 3 wk. To analyze the T cell-mediated mechanisms underlying IT in vivo, we elaborated the role of T-bet-expressing Th1 cells, T cell-derived IL-10, and Ag-specific thymic as well as peripherally induced Foxp3(+) regulatory T (Treg) cells. IT ameliorated airway hyperresponsiveness and airway inflammation in a chronic asthma model. Of note, IT even resulted in a regression of structural changes in the airways following chronic inhaled allergen exposure. Concomitantly, IT induced Th1 cells, Foxp3(+), and IL-10-producing Treg cells. Detailed analyses revealed that thymic Treg cells crucially contribute to the effectiveness of IT by promoting IL-10 production in Foxp3-negative T cells. Together with the peripherally induced Ag-specific Foxp3(+) Treg cells, thymic Foxp3(+) Treg cells orchestrate the curative mechanisms of IT. Taken together, we demonstrate that IT is effective in a chronic allergic disease and dependent on IL-10 and thymic as well as peripherally induced Ag-specific Treg cells.

Pericytes contribute to airway remodeling in a mouse model of chronic allergic asthma

Myofibroblast accumulation, subepithelial fibrosis, and vascular remodeling are complicating features of chronic asthma, but the mechanisms are not clear. Platelet-derived growth factors (PDGFs) regulate the fate and function of various mesenchymal cells and have been implicated as mediators of lung fibrosis. However, it is not known whether PDGF-BB signaling via PDGFRβ, which is critical for the recruitment of pericytes to blood vessels, plays a role in airway remodeling in chronic asthma. In the present study, we used a selective PDGFRβ inhibitor (CP-673451) to investigate the role of PDGFRβ signaling in the development of airway remodeling and lung dysfunction in an established mouse model of house dust mite-induced chronic allergic asthma. Unexpectedly, we found that pharmacological inhibition of PDGFRβ signaling in the context of chronic aeroallergen exposure led to exacerbated lung dysfunction and airway smooth muscle thickening. Further studies revealed that the inflammatory response to aeroallergen challenge in mice was associated with decreased PDGF-BB expression and the loss of pericytes from the airway microvasculature. In parallel, cells positive for pericyte markers accumulated in the subepithelial region of chronically inflamed airways. This process was exacerbated in animals treated with CP-673451. The results indicate that perturbed PDGF-BB/PDGFRβ signaling and pericyte accumulation in the airway wall may contribute to airway remodeling in chronic allergic asthma.

Long-term evaluation of mesenchymal stem cell therapy in a feline model of chronic allergic asthma.

Mesenchymal stem cells (MSCs) decrease airway eosinophilia, airway hyperresponsiveness (AHR), and remodelling in murine models of acutely induced asthma. We hypothesized that MSCs would diminish these hallmark features in a chronic feline asthma model. To document effects of allogeneic, adipose-derived MSCs on airway inflammation, AHR, and remodelling over time and investigate mechanisms by which MSCs alter local and systemic immunologic responses in chronic experimental feline allergic asthma. Cats with chronic, experimentally induced asthma received six intravenous infusions of MSCs (0.36-2.5 × 10E7 MSCs/infusion) or placebo bimonthly at the time of study enrollment. Cats were evaluated at baseline and longitudinally for 1 year. Outcome measures included: bronchoalveolar lavage fluid cytology to assess airway eosinophilia, pulmonary mechanics and clinical scoring to assess AHR, and thoracic computed tomographic (CT) scans to assess structural changes (airway remodelling). CT scans were evaluated using a scoring system for lung attenuation (LA) and bronchial wall thickening (BWT). To assess mechanisms of MSC action, immunologic assays including allergen-specific IgE, cellular IL-10 production, and allergen-specific lymphocyte proliferation were performed. There were no differences between treatment groups or over time with respect to airway eosinophilia or AHR. However, significantly lower LA and BWT scores were noted in CT images of MSC-treated animals compared to placebo-treated cats at month 8 of the study (LA P = 0.0311; BWT P = 0.0489). No differences were noted between groups in the immunologic assays. When administered after development of chronic allergic feline asthma, MSCs failed to reduce airway inflammation and AHR. However, repeated administration of MSCs at the start of study did reduce computed tomographic measures of airway remodelling by month 8, although the effect was not sustained at month 12. Further study of MSC therapy including repeated MSC administration is warranted to assess impact on remodelling in chronic asthma.

DNA nanoparticle-mediated thymulin gene therapy prevents airway remodeling in experimental allergic asthma

Thymulin has been shown to present anti-inflammatory and anti-fibrotic properties in experimental lung diseases. We hypothesized that a biologically active thymulin analog gene, methionine serum thymus factor, delivered by highly compacted DNA nanoparticles may prevent lung inflammation and remodeling in a mouse model of allergic asthma. The DNA nanoparticles are composed of a single molecule of plasmid DNA compacted with block copolymers of poly-L-lysine and polyethylene glycol (CK30PEG), which have been found safe in a human phase I/II clinical trial. Thymulin plasmids were detected in the lungs of ovalbumin-challenged asthmatic mice up to 27days after administration of DNA nanoparticles carrying thymulin plasmids. A single dose of DNA nanoparticles carrying thymulin plasmids prevented lung inflammation, collagen deposition and smooth muscle hypertrophy in the lungs of a murine model of ovalbumin-challenged allergic asthma, leading to improved lung mechanics. In the present model of chronic allergic asthma, highly compacted DNA nanoparticles using thymulin analog gene modulated the inflammatory and remodeling processes improving lung mechanics.

Anesthesia Literature Review

Anesthesia Literature Review

Interferon-&amp;gamma; , Pulmonary Macrophages and Airway Responsiveness in Asthma

Asthma is increasingly being recognised as involving not only allergic inflammatory mechanisms but also a variety of other cell types and cytokines. While the role of interferon-γ(IFN-γ) in asthma remains controversial, it has been proposed to contribute to the pathogenesis of both chronic stable asthma and acute severe asthma. We have shown that in a model of chronic allergic asthma in mice, airway hyper-responsiveness (AHR) is independent of various Th2 cytokines and their signalling pathways, but is dependent on IFN-γ. In a model of an allergen-induced acute exacerbation of chronic asthma, we have demonstrated that activation of pulmonary macrophages may play a critical role in driving the inflammatory response. Furthermore, we have demonstrated that IFN-γ stimulation of macrophages can lead to steroidresistant airway inflammation and AHR via the production of interleukin-27. These findings strengthen the notion that the pathogenesis of the lesions of asthma, and especially of AHR, involves both Th2 and Th1 cytokines, as well as interaction between the allergic response and the innate host defence system. Targeting the effects of IFN-γ on pulmonary macrophages may be particularly relevant to the treatment of steroid-resistant acute exacerbations of asthma.

The Tyrosine Kinase Inhibitor Masitinib Blunts Airway Inflammation and Improves Associated Lung Mechanics in a Feline Model of Chronic Allergic Asthma

Background: Blockade of tyrosine kinase signaling by masitinib, a c-kit/PDGF receptor tyrosine kinase inhibitor, can modulate allergic airway inflammation, but effects on lung mechanics have not been well characterized. We hypothesized masitinib would decrease airway eosinophilia and consequently improve pulmonary mechanics in a feline allergic asthma model. Methods: Asthma was induced in 12 cats using Bermuda grass allergen (BGA). Cats received 50 mg/day oral masitinib or placebo. Bronchoalveolar lavage fluid (BALF) was analyzed for eosinophils, total protein (TP) and BGA-specific IgE. Ventilator-acquired mechanics after methacholine (MCh) challenge determined MCh concentration needed to increase baseline airway resistance by 200% (EC₂₀₀R_aw), positive end expiratory occlusion pressure (PEEP) and end inspiratory breath hold pressure (P_plat). An inverse correlate of respiratory system compliance P_plat-PEEP was also calculated. Data were analyzed using the Wilcoxon test, with one-tailed significance set at p < 0.1. Results: After 4 weeks, percent eosinophils in BALF was lower in masitinib-treated cats (7 ± 9%) versus controls (30 ± 27%, p = 0.023). BALF TP significantly differed (p = 0.047) between groups, decreasing with masitinib and increasing with placebo. BALF BGA-specific IgE was unaffected by masitinib. Both groups showed an improvement in EC₂₀₀R_aw (masitinib, p = 0.015; control, p = 0.078) but no significant change in PEEP after 4 weeks. Masitinib-treated cats demonstrated decreased P_plat (p = 0.033) and P_plat-PEEP (p = 0.075) at week 4, suggesting an improvement in respiratory compliance. Conclusions: Masitinib reduced BALF eosinophilia and TP, indicating improved airway inflammation and edema, and improved P_plat and P_plat-PEEP, suggesting benefit to respiratory compliance influenced by airway inflammation/edema. Masitinib deserves further study in humans with chronic allergic asthma.

Anesthetic Management of Myasthenia Gravis: COPD and Asthma Patient

Abstract Introduction Conduction of general anesthesia and perioperative management of the patients with compromised lung functions and myasthenia gravis, presented for major abdominal surgery, pos...

Airway remodeling in murine asthma correlates with a defect in PGE2 synthesis by lung fibroblasts.

Asthma is a chronic lung disease characterized by local inflammation that can result in structural alterations termed airway remodeling. One component of airway remodeling involves fibroblast accumulation and activation, resulting in deposition of collagen I around small bronchi. Prostaglandin E(2) (PGE(2)) is the main eicosanoid lipid mediator produced by lung fibroblasts, and it exerts diverse anti-fibrotic actions. Dysregulation of the PGE(2) synthesis/response axis has been identified in human pulmonary fibrotic diseases and implicated in the pathogenesis of animal models of lung parenchymal fibrosis. Here we investigated the relationship between the fibroblast PGE(2) axis and airway fibrosis in an animal model of chronic allergic asthma. Airway fibrosis increased progressively as the number of airway challenges with antigen increased from 3 to 7 to 12. Compared with cells from control lungs, fibroblasts grown from the lungs of asthmatic animals, regardless of challenge number, exhibited no defect in the ability of PGE(2) or its analogs to inhibit cellular proliferation and collagen I expression. This correlated with intact expression of the EP(2) receptor, which is pivotal for PGE(2) responsiveness. However, cytokine-induced upregulation of PGE(2) biosynthesis as well as expression of cyclooxygenase-2 (COX-2) and microsomal PGE synthase-1 declined with increasing numbers of antigen challenges. In addition, treatment with the COX-2-selective inhibitor nimesulide potentiated the degree of airway fibrosis following repeated allergen challenge. Because endogenous COX-2-derived PGE(2) acts as a brake on airway fibrosis, the inability of fibroblasts to upregulate PGE(2) generation in the inflammatory milieu presented by repeated allergen exposure could contribute to the airway remodeling and fibrosis observed in chronic asthma.

Blocking Cyclophilins in the Chronic Phase of Asthma Reduces the Persistence of Leukocytes and Disease Reactivation

Allergic asthma is characterized by acute influxes of proinflammatory leukocytes in response to allergen stimulation, followed by quiescent (chronic) periods between allergen challenges, during which sustained, low-level inflammation is evident. These chronic phases of disease are thought to be mediated by populations of leukocytes persisting within airways and tissues. The lack of any in situ proliferation by these cells, along with their limited lifespan, suggests that a continual recruitment of leukocytes from the circulation is needed to maintain disease chronicity. The mechanisms regulating this persistent recruitment of leukocytes are unknown. Although classic leukocyte-attracting chemokines are highly elevated after acute allergen challenge, they return to baseline levels within 24 hours, and remain close to undetectable during the chronic phase. In the present study, we investigated whether an alternative family of chemoattractants, namely, extracellular cyclophilins, might instead play a role in regulating the recruitment and persistence of leukocytes during chronic asthma, because their production is known to be more sustained during inflammatory responses. Using a new murine model of chronic allergic asthma, elevated concentrations of extracellular cyclophilin A, but not classic chemokines, were indeed detected during the chronic phase of asthma. Furthermore, blocking the activity of cyclophilins during this phase reduced the number of persisting leukocytes by up to 80%. This reduction was also associated with a significant inhibition of acute disease reactivation upon subsequent allergen challenge. These findings suggest that blocking the function of cyclophilins during the chronic phase of asthma may provide a novel therapeutic strategy for regulating disease chronicity and severity.

Different strains of mice present distinct lung tissue mechanics and extracellular matrix composition in a model of chronic allergic asthma

The impact of genetic factors on asthma is well recognized but poorly understood. We tested the hypothesis that different mouse strains present different lung tissue strip mechanics in a model of chronic allergic asthma and that these mechanical differences may be potentially related to changes of extracellular matrix composition and/or contractile elements in lung parenchyma. Oscillatory mechanics were analysed before and after acetylcholine (ACh) in C57BL/10, BALB/c, and A/J mice, subjected or not to ovalbumin sensitization and challenge. In controls, tissue elastance (E) and resistance (R), collagen and elastic fibres' content, and alpha-actin were higher in A/J compared to BALB/c mice, which, in turn, were more elevated than in C57BL/10. A similar response pattern was observed in ovalbumin-challenged animals irrespective of mouse strain. E and R augmented more in ovalbumin-challenged A/J [E: 22%, R: 18%] than C57BL/10 mice [E: 9.4%, R: 11%] after ACh In conclusion, lung parenchyma remodelled differently yielding distinct in vitro mechanics according to mouse strain.

Lung Mechanics and Histology During Sevoflurane Anesthesia in a Model of Chronic Allergic Asthma

There are no studies examining the effects of sevoflurane on a chronically inflamed and remodeled airway, such as that found in asthma. In the present study, we sought to define the respiratory effects of sevoflurane in a model of chronic allergic asthma. For this purpose, pulmonary mechanics were studied and lung morphometry analyzed to determine whether the physiological modifications reflected underlying morphological changes. Thirty-six BALB/c mice (20-25 g) were randomly divided into four groups. In OVA groups, mice were sensitized with ovalbumin and exposed to repeated ovalbumin challenges. In SAL groups, mice received saline using the same protocol. Twenty-four hours after the last challenge, the animals were anesthetized with pentobarbital sodium (PENTO, 20 mg/kg i.p.) or sevoflurane (SEVO, 1 MAC). Lung static elastance (Est), resistive ([DELTA]P1) and viscoelastic/inhomogeneous ([DELTA]P2) pressure decreases were analyzed by an end-inflation occlusion method. Lungs were fixed and stained for histological analysis. Animals in the OVASEVO group showed lower [DELTA]P1 (38%), [DELTA]P2 (24%), and Est (22%) than animals in the OVAPENTO group. Histology demonstrated greater airway dilation (16%) and a lower degree of alveolar collapse (25%) in the OVASEVO compared with OVAPENTO group. [DELTA]P1 was lower (35%) and airway diameters larger (12%) in the SALSEVO compared with SALPENTO group. Sevoflurane anesthesia acted both at airway level and lung periphery reducing ([DELTA]P1 and [DELTA]P2 pressures, and Est in chronic allergic asthma.

Vascular Remodeling Is Airway Generation-Specific in a Primate Model of Chronic Asthma

Changes in the density of bronchial vessels have been proposed as a part of airway remodeling that occurs in chronic asthma. Using an established nonhuman primate model of chronic allergic asthma, we evaluated changes in vascular density as well as the contribution of bronchial epithelium to produce vascular endothelial growth factor (VEGF). Eight juvenile rhesus macaques were divided into two groups of four. One group was exposed to 11 cycles of aerosolized house dust mite allergen (HDMA), whereas the other was exposed to filtered air. Bronchial wall vasculature was identified using an immunohistochemical approach, and vascular density was quantified stereologically. A semiquantitative polymerase chain reaction approach was used to estimate VEGF splice variant gene expression at discrete airway generations. Cell culture of primary tracheal epithelial cells with varying concentrations of HDMA was used to quantify the direct contribution of the epithelium to VEGF production. Bronchial vascular density was increased at mid- to lower airway generations, which was independent of changes in the interstitial compartment. The VEGF121 splice variant was significantly increased at lower airway generations. VEGF protein increased in a dose-dependant fashion in vitro primarily by an increase in VEGF121 gene expression. This study highlights that increased vascular density in an animal model of chronic allergic asthma is airway generation specific and associated with a unique increase of VEGF splice variant gene expression. Airway epithelium is the likely source for increased VEGF.

Separation of bronchoconstriction from increased ventilatory drive in a nonhuman primate model of chronic allergic asthma

The relationship between allergen-induced ventilatory drive and bronchoconstriction was investigated in dust mite-sensitive cynomolgus macaques periodically exposed to low doses of aerosolized antigen for up to 5.5 yr. Initially, the animals responded to aerosolized dust mite allergen at a concentration of 350 arbitrary units (AU)/ml with simultaneous increases in lung resistance (RL) and respiratory rate (RR). With time, RL and RR became differentially sensitive to allergen provocation. At the end of the study period, aerosolized allergen at a concentration of 15 AU/ml doubled RR without increasing RL. When mechanically ventilated to maintain tidal volume, higher concentrations of allergen could be delivered, and RL increased. Inhaled disodium cromoglycate and intravenous diphenhydramine attenuated the increase in RR, indicating that allergen-induced release of histamine and activation of H(1) receptors mediated the response. Inhaled beta-adrenergic agonists attenuated the RR response to dust mite and to direct histamine provocation. These results demonstrate that chronic periodic allergen challenge increases the allergic sensitivity of histamine-dependent reflexes controlling ventilatory drive. Activation of these reflexes is independent of overt bronchoconstriction, but can be inhibited by beta-adrenergic agonists, indicating that beta-adrenergic agonists exert their effect independent of bronchodilation.

Effects of ciclesonide and fluticasone propionate on allergen-induced airway inflammation and remodeling features

Several topical corticosteroids are available as anti-inflammatory treatment for asthma. Their comparative effects on allergic inflammation and airway remodeling are unclear. We compared the effects of ciclesonide with those of fluticasone propionate in a Brown Norway rat model of chronic allergic asthma. Rats sensitized and exposed to ovalbumin (OVA) were treated with dry powder vehicle, ciclesonide, or fluticasone (0.01, 0.03, and 0.1 mg/kg administered intratracheally) 24 hours and 1 hour before each of 6 OVA exposures. In a second protocol we administered 0.1 mg/kg ciclesonide or fluticasone only after the third OVA exposure. Ciclesonide at all doses inhibited the allergen-induced increase in airway eosinophils and T cells, reduced goblet cell hyperplasia, and decreased 5-bromo-2'-deoxyuridine-immunoreactive airway smooth muscle (ASM) and epithelial cells. At 0.03 and 0.1 mg/kg ciclesonide, bronchial hyperresponsiveness (BHR) was also inhibited. Fluticasone did not attenuate allergen-induced BHR, despite inhibiting airway eosinophils and T cells, goblet cell hyperplasia, and 5-bromo-2'-deoxyuridine-immunoreactive ASM and epithelial cells. Fluticasone (0.1 mg/kg) caused a significant reduction in body weight (9%) compared with ciclesonide (0.1 mg/kg). Ciclesonide did not change plasma corticosterone levels, whereas fluticasone (0.1 mg/kg) reduced them. In the second protocol both fluticasone and ciclesonide inhibited BHR, bronchial inflammation, goblet cell hyperplasia, and ASM proliferation. Ciclesonide potently inhibited chronic allergic inflammation, remodeling, and BHR without having an effect on body weight and the hypothalamic-pituitary-adrenal axis. Fluticasone prevented airway inflammation but not BHR, but both fluticasone and ciclesonide are effective at reversal of BHR, inflammation, and remodeling features.