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Couetil L, Cardwell JM, Leguillette R, Mazan M, Richard E, Bienzle D, Bullone M, Gerber V, Ivester K, Lavoie JP, Martin J, Moran G, Niedźwiedź A, Pusterla N, Swiderski C. Equine Asthma: Current Understanding and Future Directions. Front Vet Sci 2020; 7:450. [PMID: 32903600 PMCID: PMC7438831 DOI: 10.3389/fvets.2020.00450] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 06/19/2020] [Indexed: 12/12/2022] Open
Abstract
The 2019 Havemeyer Workshop brought together researchers and clinicians to discuss the latest information on Equine Asthma and provide future research directions. Current clinical and molecular asthma phenotypes and endotypes in humans were discussed and compared to asthma phenotypes in horses. The role of infectious and non-infectious causes of equine asthma, genetic factors and proposed disease pathophysiology were reviewed. Diagnostic limitations were evident by the limited number of tests and biomarkers available to field practitioners. The participants emphasized the need for more accessible, standardized diagnostics that would help identify specific phenotypes and endotypes in order to create more targeted treatments or management strategies. One important outcome of the workshop was the creation of the Equine Asthma Group that will facilitate communication between veterinary practice and research communities through published and easily accessible guidelines and foster research collaboration.
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Affiliation(s)
- Laurent Couetil
- College of Veterinary Medicine, Purdue University, West Lafayette, IN, United States
| | - Jacqueline M Cardwell
- Department of Pathobiology and Population Sciences, Royal Veterinary College, London, United Kingdom
| | - Renaud Leguillette
- College of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - Melissa Mazan
- Cummings School of Veterinary Medicine, Tufts University, Grafton, MA, United States
| | - Eric Richard
- LABÉO (Frank Duncombe), Normandie Université, UniCaen, Caen, France
| | - Dorothee Bienzle
- Department of Pathobiology, University of Guelph, Guelph, ON, Canada
| | - Michela Bullone
- Department of Veterinary Sciences, University of Turin, Grugliasco, Italy
| | - Vinzenz Gerber
- Vetsuisse Faculty, Institut Suisse de Médecine Équine (ISME), University of Bern and Agroscope, Bern, Switzerland
| | - Kathleen Ivester
- College of Veterinary Medicine, Purdue University, West Lafayette, IN, United States
| | - Jean-Pierre Lavoie
- Faculty of Veterinary Medicine, University of Montreal, Montreal, QC, Canada
| | - James Martin
- Meakins Christie Laboratories, McGill University Health Center Research Institute, Montreal, QC, Canada
| | - Gabriel Moran
- Department of Pharmacology, Faculty of Veterinary Sciences, Universidad Austral de Chile, Valdivia, Chile
| | - Artur Niedźwiedź
- Department of Internal Diseases With Clinic for Horses, Dogs and Cats, Wroclaw University of Environmental and Life Sciences, Wrocław, Poland
| | - Nicola Pusterla
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
| | - Cyprianna Swiderski
- College of Veterinary Medicine, Mississippi State University, Starkville, MS, United States
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Chand HS, Harris JF, Tesfaigzi Y. IL-13 in LPS-Induced Inflammation Causes Bcl-2 Expression to Sustain Hyperplastic Mucous cells. Sci Rep 2018; 8:436. [PMID: 29323189 PMCID: PMC5765145 DOI: 10.1038/s41598-017-18884-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 12/19/2017] [Indexed: 12/23/2022] Open
Abstract
Exposure to lipopolysaccharides (LPS) causes extensive neutrophilic inflammation in the airways followed by mucous cell hyperplasia (MCH) that is sustained by the anti-apoptotic protein, Bcl-2. To identify inflammatory factor(s) that are responsible for Bcl-2 expression, we established an organ culture system consisting of airway epithelial tissue from the rat nasal midseptum. The highest Muc5AC and Bcl-2 expression was observed when organ cultures were treated with brochoalveolar lavage (BAL) fluid harvested from rats 10 h post LPS instillation. Further, because BAL harvested from rats depleted of polymorphonuclear cells compared to controls showed increased Bcl-2 expression, analyses of cytokine levels in lavages identified IL-13 as an inducer of Bcl-2 expression. Ectopic IL-13 treatment of differentiated airway epithelial cells increased Bcl-2 and MUC5AC expression in the basal and apical regions of the cells, respectively. When Bcl-2 was blocked using shRNA or a small molecule inhibitor, ABT-263, mucous cell numbers were reduced due to increased apoptosis that disrupted the interaction of Bcl-2 with the pro-apoptotic protein, Bik. Furthermore, intranasal instillation of ABT-263 reduced the LPS-induced MCH in bik +/+ but not bik -/- mice, suggesting that Bik mediated apoptosis in hyperplastic mucous cells. Therefore, blocking Bcl-2 function could be useful in reducing IL-13 induced mucous hypersecretion.
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Affiliation(s)
- Hitendra S Chand
- COPD Program, Lovelace Respiratory Research Institute, Albuquerque, NM, 87108, USA
- Department of Immunology, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, 33199, USA
| | - Jennifer F Harris
- COPD Program, Lovelace Respiratory Research Institute, Albuquerque, NM, 87108, USA
- Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Yohannes Tesfaigzi
- COPD Program, Lovelace Respiratory Research Institute, Albuquerque, NM, 87108, USA.
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Pacholewska A, Kraft MF, Gerber V, Jagannathan V. Differential Expression of Serum MicroRNAs Supports CD4⁺ T Cell Differentiation into Th2/Th17 Cells in Severe Equine Asthma. Genes (Basel) 2017; 8:E383. [PMID: 29231896 PMCID: PMC5748701 DOI: 10.3390/genes8120383] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 11/21/2017] [Accepted: 12/01/2017] [Indexed: 01/06/2023] Open
Abstract
MicroRNAs (miRNAs) regulate post-transcriptional gene expression and may be exported from cells via exosomes or in partnership with RNA-binding proteins. MiRNAs in body fluids can act in a hormone-like manner and play important roles in disease initiation and progression. Hence, miRNAs are promising candidates as biomarkers. To identify serum miRNA biomarkers in the equine model of asthma we investigated small RNA derived from the serum of 34 control and 37 asthmatic horses. These samples were used for next generation sequencing, novel miRNA identification and differential miRNA expression analysis. We identified 11 significantly differentially expressed miRNAs between case and control horses: eca-miR-128, eca-miR-744, eca-miR-197, eca-miR-103, eca-miR-107a, eca-miR-30d, eca-miR-140-3p, eca-miR-7, eca-miR-361-3p, eca-miR-148b-3p and eca-miR-215. Pathway enrichment using experimentally validated target genes of the human homologous miRNAs showed a significant enrichment in the regulation of epithelial-to-mesenchymal transition (key player in airway remodeling in asthma) and the phosphatidylinositol (3,4,5)-triphosphate (PIP3) signaling pathway (modulator of CD4⁺ T cell maturation and function). Downregulated miR-128 and miR-744 supports a Th2/Th17 type immune response in severe equine asthma.
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Affiliation(s)
- Alicja Pacholewska
- Department of Clinical Veterinary Medicine, Swiss Institute of Equine Medicine, Vetsuisse Faculty, University of Bern and Agroscope, Länggassstrasse 124, 3012 Bern, Switzerland.
- Department of Clinical Research and Veterinary Public Health, Institute of Genetics, Vetsuisse Faculty, University of Bern, Bremgartenstrasse 109A, 3012 Bern, Switzerland.
| | - Matthias F Kraft
- Department of Clinical Veterinary Medicine, Swiss Institute of Equine Medicine, Vetsuisse Faculty, University of Bern and Agroscope, Länggassstrasse 124, 3012 Bern, Switzerland.
- Department of Clinical Research and Veterinary Public Health, Institute of Genetics, Vetsuisse Faculty, University of Bern, Bremgartenstrasse 109A, 3012 Bern, Switzerland.
| | - Vincent Gerber
- Department of Clinical Veterinary Medicine, Swiss Institute of Equine Medicine, Vetsuisse Faculty, University of Bern and Agroscope, Länggassstrasse 124, 3012 Bern, Switzerland.
| | - Vidhya Jagannathan
- Department of Clinical Research and Veterinary Public Health, Institute of Genetics, Vetsuisse Faculty, University of Bern, Bremgartenstrasse 109A, 3012 Bern, Switzerland.
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Tessier L, Côté O, Clark ME, Viel L, Diaz-Méndez A, Anders S, Bienzle D. Impaired response of the bronchial epithelium to inflammation characterizes severe equine asthma. BMC Genomics 2017; 18:708. [PMID: 28886691 PMCID: PMC5591550 DOI: 10.1186/s12864-017-4107-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 09/01/2017] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Severe equine asthma is a naturally occurring lung inflammatory disease of mature animals characterized by neutrophilic inflammation, bronchoconstriction, mucus hypersecretion and airway remodeling. Exacerbations are triggered by inhalation of dust and microbial components. Affected animals eventually are unable of aerobic performance. In this study transcriptomic differences between asthmatic and non-asthmatic animals in the response of the bronchial epithelium to an inhaled challenge were determined. RESULTS Paired endobronchial biopsies were obtained pre- and post-challenge from asthmatic and non-asthmatic animals. The transcriptome, determined by RNA-seq and analyzed with edgeR, contained 111 genes differentially expressed (DE) after challenge between horses with and without asthma, and 81 of these were upregulated. Genes involved in neutrophil migration and activation were in central location in interaction networks, and related gene ontology terms were significantly overrepresented. Relative abundance of specific gene products as determined by immunohistochemistry was correlated with differential gene expression. Gene sets involved in neutrophil chemotaxis, immune and inflammatory response, secretion, blood coagulation and apoptosis were overrepresented among up-regulated genes, while the rhythmic process gene set was overrepresented among down-regulated genes. MMP1, IL8, TLR4 and MMP9 appeared to be the most important proteins in connecting the STRING protein network of DE genes. CONCLUSIONS Several differentially expressed genes and networks in horses with asthma also contribute to human asthma, highlighting similarities between severe human adult and equine asthma. Neutrophil activation by the bronchial epithelium is suggested as the trigger of the inflammatory cascade in equine asthma, followed by epithelial injury and impaired repair and differentiation. Circadian rhythm dysregulation and the sonic Hedgehog pathway were identified as potential novel contributory factors in equine asthma.
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Affiliation(s)
- Laurence Tessier
- Department of Pathobiology, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada
| | - Olivier Côté
- Department of Pathobiology, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada.,Present address: BioAssay Works LLC, 10075 Tyler Place, Suite 18, Ijamsville, MD, 21754, USA
| | - Mary Ellen Clark
- Department of Pathobiology, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada
| | - Laurent Viel
- Department of Clinical Studies, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada
| | - Andrés Diaz-Méndez
- Department of Clinical Studies, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada.,Present address: Centre for Equine Infectious Disease, The University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Simon Anders
- Institute for Molecular Medicine, Finland (FIMM), University of Helsinki, Tukholmankatu 8, 00014, Helsinki, Finland
| | - Dorothee Bienzle
- Department of Pathobiology, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada.
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Bullone M, Hélie P, Joubert P, Lavoie JP. Development of a Semiquantitative Histological Score for the Diagnosis of Heaves Using Endobronchial Biopsy Specimens in Horses. J Vet Intern Med 2016; 30:1739-1746. [PMID: 27527123 PMCID: PMC5032871 DOI: 10.1111/jvim.14556] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 06/03/2016] [Accepted: 07/06/2016] [Indexed: 12/11/2022] Open
Abstract
Background Remodeling of the peripheral airways persists during the asymptomatic phase of heaves. Assessing the histology of large bronchi could facilitate the diagnosis of heaves during remission of the disease. Hypothesis Airway inflammation and remodeling in endobronchial biopsy (EBB) specimens differentiate horses with heaves from controls, independently of their clinical status (exacerbation or remission). Animals Fourteen healthy horses and 24 horses with heaves. Methods A 14‐point scoring system assessing central bronchial wall inflammation and remodeling was developed. The score was validated by 2 pathologists using specimens obtained from 18 horses (6 controls, 6 with heaves exacerbation, and 6 with heaves remission) in which lung function had been assessed with impulse oscillometry. Clinical and research application of the score was evaluated using biopsy specimens obtained from 20 additional horses (8 controls, 6 with heaves exacerbation, and 6 with heaves remission). Results The score was repeatable (interclass correlation coefficient = 69%). It differentiated horses with heaves in exacerbation (mean ± SD: 6.2 ± 2.2) from those in remission (4.0 ± 1.0) and controls (3.6 ± 1.7, P < 0.0001). The histological scores of horses with heaves correlated with the ratio of respiratory resistance (R) at 5 and 10 Hz (R5 : R10 ratio, r = 0.65, P = 0.03), a parameter assessing airway obstruction. Conclusions and Clinical Significance The proposed histological scoring system correlates with the degree of airway obstruction measured by impulse oscillometry. However, it does not discriminate horses with heaves in remission from controls. Evaluation of EBB specimens might be considered in future research and clinical studies of respiratory diseases in horses.
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Affiliation(s)
- M Bullone
- Department of Clinical Sciences, Université de Montréal, St-Hyacinthe, QC, Canada
| | - P Hélie
- Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, St-Hyacinthe, QC, Canada
| | - P Joubert
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Quebec, QC, Canada
| | - J-P Lavoie
- Department of Clinical Sciences, Université de Montréal, St-Hyacinthe, QC, Canada.
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Perez B, Henriquez C, Sarmiento J, Morales N, Folch H, Galesio JS, Uberti B, Morán G. Tamoxifen as a new therapeutic tool for neutrophilic lung inflammation. Respirology 2015; 21:112-8. [PMID: 26510482 DOI: 10.1111/resp.12664] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 07/19/2015] [Accepted: 07/29/2015] [Indexed: 12/18/2022]
Abstract
BACKGROUND AND OBJECTIVE Neutrophilic asthma is an important disease subgroup, including patients with severe phenotypes and erratic responses to standard treatments. Tamoxifen (TX), a selective estrogen receptor modulator (SERM) used as treatment of human breast cancer, has been shown to induce early apoptosis of equine blood and bronchoalveolar lavage fluid (BALF) neutrophils in vitro. Equine recurrent airway obstruction (RAO) is a naturally occurring neutrophilic condition, closely related with human asthma. Our purpose was to investigate the therapeutic potential of tamoxifen in horses with neutrophilic lung inflammation. METHODS Twelve horses underwent acute lung inflammation through exposure to allergens known to cause RAO, after which they received treatment with either tamoxifen or dexamethasone. Outcome measures included evaluation of clinical signs, BALF cytology, and early apoptosis of blood and BALF neutrophils. RESULTS Tamoxifen treatment decreased BALF neutrophil counts (65.3 ± 19.38% before treatment; 7.6 ± 4.5% 2 days post-treatment,; and 13.6 ± 9.3% 5 days post-treatment). A similar decrease was observed with dexamethasone treatment (48.6 ± 5.88% before treatment; 11.5 ± 8.1% 2 days post-treatment; 14.6 ± 10.3% 5 days post-treatment). Clinical and endoscopic scores improved in both treatment groups. Tamoxifen treatment significantly increased early apoptosis of peripheral blood neutrophils at 5 days post-treatment (27.04 ± 15.2%), and in BALF neutrophils at 2 and 5 days post-treatment (42.11 ± 11.67% and 48.98 ± 2.6%, respectively). CONCLUSION Tamoxifen treatment in horses with induced acute pulmonary inflammation promoted early apoptosis of blood and BALF neutrophils, reduction in BALF neutrophils and improvement in the animals' clinical status.
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Affiliation(s)
- Barbara Perez
- Department of Pharmacology, Austral University of Chile, Valdivia, Chile.,Graduate School, Austral University of Chile, Valdivia, Chile
| | - Claudio Henriquez
- Department of Pharmacology, Austral University of Chile, Valdivia, Chile
| | - Jose Sarmiento
- Department of Physiology, Austral University of Chile, Valdivia, Chile
| | - Natalia Morales
- Department of Pharmacology, Austral University of Chile, Valdivia, Chile
| | - Hugo Folch
- Department of Immunology, Faculty of Medicine, Austral University of Chile, Valdivia, Chile
| | - Juan S Galesio
- Department of Clinical Science, Faculty of Veterinary Science, Austral University of Chile, Valdivia, Chile
| | - Benjamin Uberti
- Department of Clinical Science, Faculty of Veterinary Science, Austral University of Chile, Valdivia, Chile
| | - Gabriel Morán
- Department of Pharmacology, Austral University of Chile, Valdivia, Chile
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Niedzwiedz A, Jaworski Z, Tykalowski B, Smialek M. Neutrophil and macrophage apoptosis in bronchoalveolar lavage fluid from healthy horses and horses with recurrent airway obstruction (RAO). BMC Vet Res 2014; 10:29. [PMID: 24460911 PMCID: PMC3903020 DOI: 10.1186/1746-6148-10-29] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2013] [Accepted: 01/22/2014] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Dysregulation of apoptosis has been implicated in a range of diseases including tumors, neurodegenerative and autoimmune diseases, as well as allergic asthma and chronic obstructive pulmonary disease (COPD) in humans. Although it has a different pathophysiology, delayed apoptosis of various inflammatory cells may play a pivotal role in the development of recurrent airway obstruction (RAO) in horses. Reduction of inflammatory cell apoptosis or a dysregulation of this process could lead to chronic inflammation and tissue injury. Therefore, the aim of this study was to investigate the rate of apoptosis and necrosis of neutrophils and macrophages in bronchoalveolar lavage fluid obtained from seven horses suffering from RAO (study group) and seven control horses. RESULTS We demonstrated that neutrophil/macrophage apoptosis is altered in RAO-affected horses compared with the control group in the BAL fluid. We found a significant difference between the median percentage of early and late apoptosis of neutrophils between the study and control group of horses. Moreover, we found a positive correlation between the rate of apoptosis and the median percentage of macrophages in RAO-affected horses. CONCLUSION The findings suggest that apoptosis dysregulation may play a significant role in the pathogenesis of RAO. However, further studies are needed to clarify the role of altered apoptosis in the course of equine recurrent airway obstruction.
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Affiliation(s)
- Artur Niedzwiedz
- Department of Internal Diseases with Clinic for Horses, Dogs and Cats, The Faculty of Veterinary Medicine, Wrocław University of Environmental and Life Sciences, Pl, Grunwaldzki 47, Wrocław 50-366, Poland.
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8
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Pirie RS. Recurrent airway obstruction: a review. Equine Vet J 2014; 46:276-88. [PMID: 24164473 DOI: 10.1111/evj.12204] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Accepted: 10/05/2013] [Indexed: 12/01/2022]
Abstract
Recurrent airway obstruction is a widely recognised airway disorder, characterised by hypersensitivity-mediated neutrophilic airway inflammation and lower airway obstruction in a subpopulation of horses when exposed to suboptimal environments high in airborne organic dust. Over the past decade, numerous studies have further advanced our understanding of different aspects of the disease. These include clarification of the important inhaled airborne agents responsible for disease induction, improving our understanding of the underlying genetic basis of disease susceptibility and unveiling the fundamental immunological mechanisms leading to establishment of the classic disease phenotype. This review, as well as giving a clinical overview of recurrent airway obstruction, summarises much of the work in these areas that have culminated in a more thorough understanding of this debilitating disease.
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Affiliation(s)
- R S Pirie
- Royal (Dick) School of Veterinary Studies and Roslin Institute, University of Edinburgh, Roslin, Midlothian, UK
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Abstract
Animal models have been developed to investigate specific components of asthmatic airway inflammation, hyper-responsiveness or remodelling. However, all of these aspects are rarely observed in the same animal. Heaves is a naturally occurring disease of horses that combines these features. It is characterized by stable dust-induced inflammation, bronchospasm and remodelling. The evaluation of horses during well-controlled natural antigen exposure and avoidance in experimental settings allows the study of disease mechanisms in the asymptomatic and symptomatic stages, an approach rarely feasible in humans. Also, the disease can be followed over several years to observe the cumulative effect of repeated episodes of clinical exacerbation or to evaluate long-term treatment, contrasting most murine asthma models. This model has shown complex gene and environment interactions, the involvement of both innate and adaptive responses to inflammation, and the contribution of bronchospasm and tissue remodelling to airway obstruction, all occurring in a natural setting. Similarities with the human asthmatic airways are well described and the model is currently being used to evaluate airway remodelling and its reversibility in ways that are not possible in people for ethical reasons. Tools including antibodies, recombinant proteins or gene arrays, as well as methods for sampling tissues and assessing lung function in the horse are constantly evolving to facilitate the study of this animal model. Research perspectives that can be relevant to asthma include the role of neutrophils in airway inflammation and their response to corticosteroids, systemic response to pulmonary inflammation, and maintaining athletic capacities with early intervention.
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Affiliation(s)
- Mathilde Leclere
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Université de Montréal, St-Hyacinthe, Canada
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10
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Ryhner T, Müller N, Balmer V, Gerber V. Increased mucus accumulation in horses chronically affected with recurrent airway obstruction is not associated with up-regulation of CLCA1, EGFR, MUC5AC, Bcl-2, IL-13 and INF-gamma expression. Vet Immunol Immunopathol 2008; 125:8-17. [PMID: 18597857 DOI: 10.1016/j.vetimm.2008.05.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2007] [Revised: 04/03/2008] [Accepted: 05/19/2008] [Indexed: 11/19/2022]
Abstract
The mechanisms leading to mucus accumulation in equine inflammatory airway disease (IAD) and recurrent airway obstruction (RAO) are unclear. In airways of human patients with asthma and/or chronic obstructive pulmonary disease as well as in animal models of these diseases, associations of mucus hyperproduction with increased calcium-activated chloride channel 1 (CLCA1), epidermal growth factor receptor (EGFR), mucin 5AC (MUC5AC), B-cell lymphoma 2 (Bcl-2), interleukin (IL)-13 and interferon (IFN)-gamma expression have been reported. We hypothesized that increased mucus accumulation in RAO and IAD are associated with alterations in inflammatory cytokine (IL-13 and IFN-gamma) and epithelial gene (CLCA1, EGFR, Bcl-2 and MUC5AC) profiles. Therefore, mRNA expression of these genes in cell pellets extracted from bronchoalveolar lavage fluid (BALF) and bronchial epithelial brushing (BEB) was compared between 11 clinically healthy (Control group), 7 IAD- and 12 RAO-affected horses by reverse transcription polymerase chain reaction. We also performed arterial blood gas analysis, endoscopic scoring of mucus accumulation in the trachea and cytology of tracheo-bronchial secretions (TBS) and of BALF. Tracheal mucus accumulation, along with TBS and BALF neutrophils were significantly increased and arterial pO(2) was decreased in RAO-affected horses compared to the Control group. IL-13 in BALF samples was significantly lower in the RAO group. None of the other genes' relative mRNA levels displayed significant differences between groups. Our findings suggest that mucus production in equine RAO is induced by pathways independent of IL-13, CLCA1, EGFR, MUC5AC and Bcl-2 up-regulation.
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Affiliation(s)
- Thea Ryhner
- Department of Veterinary Clinical Studies, Vetsuisse-Faculty University of Berne, Länggassstrasse 124, CH-3012 Bern, Switzerland.
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11
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Dacre KJ, McGorum BC, Marlin DJ, Bartner LR, Brown JK, Shaw DJ, Robinson NE, Deaton C, Pemberton AD. Organic dust exposure increases mast cell tryptase in bronchoalveolar lavage fluid and airway epithelium of heaves horses. Clin Exp Allergy 2007; 37:1809-18. [PMID: 17956586 DOI: 10.1111/j.1365-2222.2007.02857.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND Mast cell degranulation is believed to act as a key event in initiating and maintaining airway response to allergen challenge in human asthma. It is hypothesized that the mast cell may play a similar role in equine heaves, which shares many similarities with occupational dust-induced asthma. OBJECTIVE The aim of this study was to quantify the mast cell proteinase tryptase in bronchoalveolar lavage fluid (BALF) from control and heaves-susceptible horses and to investigate tryptase mRNA and protein expression in pulmonary mast cells. METHODS Equine BALF tryptase concentrations were determined by ELISA from control and heaves-susceptible horses pre and post 24 h hay/straw challenge (HSC). Tryptase mRNA and protein expression were investigated by quantitative PCR and immunohistochemistry in bronchial and bronchiolar tissue samples of control and heaves-susceptible horses. RESULTS Both control and heaves-susceptible horses had significantly increased BALF tryptase concentrations following HSC (P=0.003 and 0.034, respectively). Increased numbers of tryptase-expressing intra-epithelial mast cells were demonstrated in heaves horses, but not controls, following challenge (P=0.02). Bronchiolar tissue from heaves horses removed from challenge contained significantly lower tryptase transcripts than that from control horses (P=0.02). CONCLUSION Mast cell degranulation and tryptase release into the airways occur following HSC of control and heaves-susceptible horses. The greater number of mast cells available in the bronchiolar epithelium of heaves horses may be clinically significant in the pulmonary inflammatory response of heaves.
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Affiliation(s)
- K J Dacre
- Department of Veterinary Clinical Sciences, Easter Bush Veterinary Centre, Royal (Dick) School of Veterinary Studies, Midlothian, UK.
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12
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Rousseau K, Kirkham S, McKane S, Newton R, Clegg P, Thornton DJ. Muc5b and Muc5ac are the major oligomeric mucins in equine airway mucus. Am J Physiol Lung Cell Mol Physiol 2007; 292:L1396-404. [PMID: 17293373 DOI: 10.1152/ajplung.00444.2006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Horses frequently suffer from respiratory diseases, which, irrespective of etiology, are often associated with airway mucus accumulation. Studies on human airways have shown that the key structural components of the mucus layer are oligomeric mucins, which can undergo changes of expression and properties in disease. However, there is little information on these gel-forming glycoproteins in horse airways mucus. Therefore, the aims of this study were to isolate equine airways oligomeric mucins, characterize their macromolecular properties, and identify their gene products. To this end, pooled tracheal washes, collected from healthy horses and horses suffering from respiratory diseases, were solubilized with 6 M guanidinium chloride (GdmCl). The oligomeric mucins were purified by density gradient centrifugation followed by size exclusion chromatography. Biochemical and biophysical analyses showed the mucins were stiffened random coils in solution that were polydisperse in size (M(r) = 6-20 MDa, average M(r) = 14 MDa) and comprised of disulfide-linked subunits (average M(r) = 7 MDa). Agarose gel electrophoresis showed that the pooled mucus sample contained at least two populations of oligomeric mucins. Electrospray ionization tandem mass spectrometry of tryptic digests of the unfractionated mucin preparation showed that the oligomeric mucins Muc5b and Muc5ac were present. In summary, we have shown that equine airways mucus is a mixture of Muc5b and Muc5ac mucins that have a similar macromolecular organization to their human counterparts. This study will form the basis for future studies to analyze the contribution of these two mucins to equine airways pathology associated with mucus accumulation.
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Affiliation(s)
- Karine Rousseau
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
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