A novel model for equine recurrent airway obstruction

Department of Comparative Biomedical Sciences, Louisiana State University, Baton Rouge, Louisiana, United States
Veterinary Immunology and Immunopathology (Impact Factor: 1.54). 10/2002; 87(3-4):385-9. DOI: 10.1016/S0165-2427(02)00081-8
Source: PubMed


Equine recurrent airway obstruction (RAO; a term combining both chronic obstructive pulmonary disease (COPD) and summer pasture associated obstructive pulmonary disease (SPAOPD)) is one of the most common equine respiratory diseases with up to 50% of horses affected worldwide. The etiopathogenesis of RAO is unknown although pulmonary hypersensitivity to inhaled mold antigens may be involved. Recent work in our laboratory demonstrating elevated levels of IL-4 and IL-13 mRNA in the airways and peripheral blood of horses with RAO is consistent with an atopic component to RAO. Little is known regarding the earliest phases of RAO in horses. Here we describe the development of a novel airway model for equine RAO that utilizes ovalbumin-coated polystyrene beads for airway sensitization and challenge. Aerosol challenge of sensitized ponies with OVA-coated microbeads resulted in decreased airway compliance, increased percentage of lymphocytes and neutrophils in the bronchoalveolar lavage fluid, and evidence of a Th2 cytokine response in the bronchoalveolar cells. These results suggest that this approach may be useful in describing the initial stages of RAO development in the horse.

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Available from: Ralph E Beadle, Sep 21, 2014
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    • "However , contradictory results were found trying to identify the major immunological mechanisms underlying both human and equine respiratory obstructive diseases. Some authors gathered evidence in support of a Th2-mediated response, primarily associated with a possible role of the allergic response in the development of the RAO disease (Bowles et al., 2002; Cordeau et al., 2004) while other studies found an increased expression of Th1-specific transcripts or a mixed Th1/Th2 response (Giguère et al., 2002; Horohov et al., 2005). "
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    ABSTRACT: The goal of the present study was to investigate mRNA expression levels of several cytokines and inflammatory mediators in broncho-alveolar lavage (BAL) fluid and respiratory epithelium in recurrent airway obstruction (RAO)-affected horses. RAO, also called heaves, is a common, performance-limiting, equine respiratory disease with clinical signs and pathophysiological similarities to human asthma, and characterized by bronchospasm, neutrophilic infiltration and increased mucus in the airways. Six RAO-affected horses were examined twice within 15 days and seven clinically healthy horses were examined for comparison. Quantitative real-time RT-PCR was used to assess mRNA expression of the inflammatory mediators IL-1β, IL-6, IL-8, IL-13, IL-17, TNFα, INFγ, TGFβ1, NFκ-β and TRL4 in bronchial biopsies and in BAL fluid. Gene expression levels were then compared with clinical signs, endoscopic examination, complete blood cell count, cytology of BAL fluid, histological examination of bronchial tissue and bacteriological and mycological examinations. Expression of IL1β, IL8, TLR4, TNFα, TGFβ1 and NFkβ transcripts was significantly up-regulated in RAO-affected compared to healthy horses. A similar trend, albeit not significant, was showed for IL17 and INFγ. A highly significant correlation was observed among IL-1β, IL8, TGFβ1, NFkβ, TRL4, and INFγ expression patterns as well as between expression levels of these genes and clinical parameters. In the present study, the comparison between clinically healthy and RAO-affected horses gave new insights on the cytokine expression in equine health and disease status. The identification of cytokines implicated in the pathogenesis of RAO may contribute to the diagnosis and treatment of this disease.
    Full-text · Article · Oct 2013 · Veterinary Immunology and Immunopathology
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    • "In addition, its incidence also appears to be related to the type of horse housing environment where exposure to high dust density may be related to hay storage and the use of straw bedding. Bowles et al. (2002), indicate that Agriculture, Ecosystems and Environment 135 (2010) 206–215 A R T I C L E I N F O "
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    ABSTRACT: It is now widely recognized that an environmental approach to the prevention of equine Recurrent Airway Obstruction (RAO), resulting from recurrent exposure to dust and aeroallergens, requires closer consideration. The aims of this study were to quantify the dust and aeroallergens in hays in order to characterize the health quality of hay, to identify the most variable parameters and determine which climatic factors and agricultural practices improve the health quality of hay.Hays were experimentally produced from a homogeneous grassland by applying different agricultural practices and rainfall amounts. Treatment effects were evaluated by dust and aeroallergen quantifications and identifications.The highest fungal contamination in airborne particles and dust contamination during late harvest, occurred when hay moisture remained high during (rainfall after cut) or after the making process (baled at 75% DM). Eurotium amstelodami and Eurotium repens were mainly found in all hays, while Aspergillus fumigatus was mostly found in hays showing the highest colony forming units (CFUs). Barn drying increased dust content and haylages produced the lowest level of airborne particles. The highest levels of endotoxins were found in the hay harvested at 75% of dry matter and the hay exposed to a rainfall after cut. The presence of zearalenone was only detected in these two low quality hays.Overall results suggest that better agricultural practices for hay making can be adopted and may be used in combination to significantly improve the health quality of hay, leading to a lower long-term exposure of horses.
    Full-text · Article · Jan 2010 · Agriculture Ecosystems & Environment
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    • "Subsequent studies have shown that mucosal spirals, eosinophils, and crystals are not characteristic of asthma only, but may be seen also in other pathological conditions, including the sputa of smokers, former smokers, and persons exposed to noxious inhalants (Djuricic and Plamenac, 1998; Djuricic et al., 2001; Plamenac et al., 1972a,b, 1974, 1979b, 1981, 1985; Walker and Fullmer, 1970). Studies of numerous authors (Beadle et al., 2002; Bowels et al., 2002; Geisel and Sandersleben, 1987; Giguere et al., 2002; Halliwell et al., 1993; Lavoie et al., 2001; Mair et al., 1988; Schmallenbach et al., 1998; Zinkl, 2002) have shown the predominant cellular population in the lumen of airways in horses is represented by neutrophilic granulocytes and desquamated epithelial cells, macrophages, and eosinophilic granulocytes may be seen. However, in the studied material of our research, desquamated epithelial cells and eosinophilic granulocytes with a large number of neutrophilic granulocytes were the predominant cellular population in the lumens of bronchi and bronchioli. "
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    ABSTRACT: Chronic obstructive pulmonary disease (COPD) is an inflammatory obstructive disease of the airways characterized with hypersensitivity of the airway tissues to various allergens, most commonly the fungi contained in the poor-quality hay and straw bedding-Saccharopolyspora rectivirgula, Aspergillus fumigatus, and Thermoactinomyces vulgaris. It is manifested clinically in middle-aged horses with recurrent episodes of dyspnea, chronic cough, and their reduced athletic and working capacity. Pulmonary emphysema and lack of pulmonary collapse are the most common gross lesion. Pathohistological findings in horses with COPD are chronic bronchitis/bronchiolitis, with characteristic changes in lumen, mucosa, submucosa, and smooth muscle layer and alveolar emphysema, both distensive and destructive form. Increased immunoreactivity in lungs and tracheobronchial lymph nodes is also noted. Most common lesions seen on cytology imprint smears from tracheal bifurcation is thick, viscous, PAS-positive mucus that forms Curschmann's spirals. Dominant cell population consists of desquamated airway epithelial cells, as well as eosinophils, neutrophils, mast cells, erythrocytes, and alveolar macrophages. Primary pulmonary pathogens as well as potential contaminants and secondary infection agents were isolated bacteriologically from lung samples. All of the aforementioned findings correlate pointing to the fact that chronic bronchitis/bronchiolitis represents a basic substrate of COPD, which have combined inflammatory and immunological etiology, and emphysema is secondary to airway obstruction.
    Preview · Article · Feb 2007 · International Review of Cytology
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