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Woodrow JS, Hines M, Sommardahl C, Flatland B, Lo Y, Wang Z, Sheats MK, Lennon EM. Initial investigation of molecular phenotypes of airway mast cells and cytokine profiles in equine asthma. Front Vet Sci 2023; 9:997139. [PMID: 36713876 PMCID: PMC9875299 DOI: 10.3389/fvets.2022.997139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 12/23/2022] [Indexed: 01/13/2023] Open
Abstract
Equine asthma is a naturally occurring lung disease characterized by chronic, partially reversible airway obstruction, pulmonary remodeling, and lower airway inflammation. Asthma is currently divided into two major groups, mild to moderate asthma (mEA) and severe asthma (sEA), but further subtyping by phenotype (i.e., clinical presentation) and/or endotype (i.e., cellular mechanisms) may be warranted. For this study, we were interested in further investigation of cellular and inflammatory characteristics of EA, including airway mast cells. The purpose of this study was to: (1) compare mast cell protease mRNA expression between healthy and asthmatic horses, (2) analyze the cytokine profile present in BALF of currently defined equine asthma groups, and (3) use these data to evaluate potential biomarkers of defined asthma groups. We hypothesized that there would be significant differences in the cellular mast cell phenotypes (i.e., mucosal vs. connective tissue) and cytokine profiles in the BALF of asthmatic vs. healthy horses and across asthma groups. We assert these characteristics may inform additional subtypes of equine asthma. Adult horses were recruited from the institution's teaching herd and clinical caseload. Mast cell protease gene expression of the BALF cellular component and multiplex bead immunoassay for cytokine concentrations in the BALF supernatant were investigated. Airway mast cells primarily expressed tryptase, with low levels of chymase. No significant changes in protease expression were detected across groups. Horses with severe asthma had increased TNF-α, CXCL-8, and IFN-γ concentrations in BALF supernatant. Multidimensional analysis demonstrated healthy and mEA horses have overlapping characteristics, with sEA separating from the other groups. This difference was primarily due to BALF neutrophil and lymphocyte concentrations. These study results further inform understanding of EA immunopathology, and future studies designed to investigate asthma phenotypes and endotypes. Ultimately, a better understanding of these groups could help identify novel therapeutic strategies.
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Affiliation(s)
- Jane S. Woodrow
- Department of Comparative and Experimental Medicine, College of Veterinary Medicine, University of Tennessee, Knoxville, Knoxville, TN, United States,Department of Clinical Sciences and Advanced Medicine, College of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Melissa Hines
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Carla Sommardahl
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Bente Flatland
- Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Yancy Lo
- Bioinformatics Core, Institute for Biomedical Informatics, University of Pennsylvania, Philadelphia, PA, United States
| | - Zhiping Wang
- Bioinformatics Core, Institute for Biomedical Informatics, University of Pennsylvania, Philadelphia, PA, United States
| | - Mary Katie Sheats
- Department of Clinical Sciences, Comparative Medicine Institute, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, United States
| | - Elizabeth M. Lennon
- Department of Clinical Sciences and Advanced Medicine, College of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, United States,*Correspondence: Elizabeth M. Lennon ✉
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The Immune Mechanisms of Severe Equine Asthma-Current Understanding and What Is Missing. Animals (Basel) 2022; 12:ani12060744. [PMID: 35327141 PMCID: PMC8944511 DOI: 10.3390/ani12060744] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 03/11/2022] [Accepted: 03/14/2022] [Indexed: 01/27/2023] Open
Abstract
Severe equine asthma is a chronic respiratory disease of adult horses, occurring when genetically susceptible individuals are exposed to environmental aeroallergens. This results in airway inflammation, mucus accumulation and bronchial constriction. Although several studies aimed at evaluating the genetic and immune pathways associated with the disease, the results reported are inconsistent. Furthermore, the complexity and heterogeneity of this disease bears great similarity to what is described for human asthma. Currently available studies identified two chromosome regions (ECA13 and ECA15) and several genes associated with the disease. The inflammatory response appears to be mediated by T helper cells (Th1, Th2, Th17) and neutrophilic inflammation significantly contributes to the persistence of airway inflammatory status. This review evaluates the reported findings pertaining to the genetical and immunological background of severe equine asthma and reflects on their implications in the pathophysiology of the disease whilst discussing further areas of research interest aiming at advancing treatment and prognosis of affected individuals.
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Bullone M, Lavoie JP. The equine asthma model of airway remodeling: from a veterinary to a human perspective. Cell Tissue Res 2019; 380:223-236. [PMID: 31713728 DOI: 10.1007/s00441-019-03117-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 09/22/2019] [Indexed: 02/06/2023]
Abstract
Human asthma is a complex and heterogeneous disorder characterized by chronic inflammation, bronchospasm and airway remodeling. The latter is a major determinant of the structure-function relationship of the respiratory system and likely contributes to the progressive and accelerated decline in lung function observed in patients over time. Corticosteroids are the cornerstone of asthma treatment. While their action on inflammation and lung function is well characterized, their effect on remodeling remains largely unknown. An important hindrance to the study of airway remodeling as a major focus in asthma research is the lack of reliable non-invasive biomarkers. In consequence, the physiologic and clinical consequences of airway wall thickening and altered composition are not well understood. In this perspective, equine asthma provides a unique and ethical (non-terminal) preclinical model for hypothesis testing and generation. Severe equine asthma is a spontaneous disease affecting adult horses characterized by recurrent and reversible episodes of disease exacerbations. It is associated with bronchoalveolar neutrophilic inflammation, bronchospasm, and excessive mucus secretion. Severe equine asthma is also characterized by bronchial remodeling, which is only partially improved by prolonged period of disease remission induced by therapy or antigen avoidance strategies. This review will focus on the similarities and differences of airway remodeling in equine and human asthma, on the strengths and limitations of the equine model, and on the challenges the model has to face to keep up with human asthma research.
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Affiliation(s)
- Michela Bullone
- Department of Veterinary Sciences, Università degli Studi di Torino, Grugliasco, Italy
| | - Jean-Pierre Lavoie
- Faculty of Veterinary Sciences, University of Montreal, 3200 rue Sicotte, St-Hyacinthe, Quebec, Canada.
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Secombe CJ, van Eps AW, Bruce M, Lester GD. The relationship between bronchoalveolar lavage fluid cytology and airway hyper-reactivity in a population of Australian horses presented for poor performance. Aust Vet J 2019; 97:343-350. [PMID: 31286483 DOI: 10.1111/avj.12861] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 06/09/2019] [Accepted: 06/17/2019] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To investigate the relationship between bronchoalveolar lavage fluid cytology, particularly mast cells, and airway hyper-reactivity in athletic horses presented for poor performance that included a respiratory tract evaluation in two disparate locations in Australia. DESIGN Multi-centre, retrospective and prospective cross-sectional study METHODS: Eighty four adult horses underwent both pulmonary function testing and histamine bronchoprovocation with a commercial flowmetric plethysmography system. A bronchoalveolar lavage was performed four to twelve hours later. Bronchoalveolar lavage fluid cytology was categorised using two differing classification systems to define mild equine asthma. Statistical analysis was used to assess associations between bronchoalveolar lavage fluid relative inflammatory cell percentages, and airway hyper-reactivity and their associated categorisations. RESULTS Sixty four percent (54/84) of horses displayed airway hyper-reactivity, as defined by PC35 < 6 mg/ml of histamine. A relative mastocytosis was the most common bronchoalveolar lavage fluid cytological abnormality. Horses with a sole mast cell response of ≥ 5% within their bronchoalveolar lavage fluid displayed airway hyper-reactivity at a lower dose of nebulized histamine than horses with normal bronchoalveolar lavage fluid cytology. Horses with mixed cell responses (relative mast cell percentage > 2% and/or relative neutrophil percentage > 5% and/or eosinophil relative cell percentage ≥ 1%) displayed airway hyper-reactivity at a lower dose of nebulized histamine than horses with normal bronchoalveolar lavage fluid cytology. CONCLUSION In the Australian context, recently revised increased bronchoalveolar lavage fluid cytology relative cell percentage cut offs appear appropriate for sole mast cell responses. The historical lower cut offs appear to be appropriate for mixed inflammatory cell responses.
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Affiliation(s)
- C J Secombe
- School of Veterinary Medicine, College of Science, Health, Engineering and Education, Murdoch University, 90 South Street, Murdoch, Western Australia, Australia
| | - A W van Eps
- Equine Specialist Hospital, School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
| | - M Bruce
- School of Veterinary Medicine, College of Science, Health, Engineering and Education, Murdoch University, 90 South Street, Murdoch, Western Australia, Australia
| | - G D Lester
- School of Veterinary Medicine, College of Science, Health, Engineering and Education, Murdoch University, 90 South Street, Murdoch, Western Australia, Australia
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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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Mazan MR. Update on noninfectious inflammatory diseases of the lower airway. Vet Clin North Am Equine Pract 2015; 31:159-85. [PMID: 25770068 DOI: 10.1016/j.cveq.2014.11.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Inflammatory airway disease and recurrent airway obstruction are 2 nonseptic diseases of the equine respiratory system with a shared cause of exposure to particulate matter. They appear to occupy 2 ends of a spectrum of disease, but are differentiated by history, clinical signs, and response to treatment. Diagnosis can be made by sampling of respiratory fluids and lung function testing. Treatment consists of environmental modification and pharmacologic treatment with systemic or inhaled corticosteroids and bronchodilators.
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Affiliation(s)
- Melissa R Mazan
- Large Animal Department of Clinical Sciences, Cummings School of Veterinary Medicine at Tufts University, 200 Westborough Road, North Grafton, MA 01536, USA.
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Secombe CJ, Lester GD, Robertson ID, Cullimore AM. Retrospective survey of bronchoalveolar lavage fluid cytology in Western Australian horses presented for evaluation of the respiratory tract: effect of season on relative cell percentages. Aust Vet J 2015; 93:152-6. [DOI: 10.1111/avj.12315] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 07/02/2014] [Accepted: 07/11/2014] [Indexed: 10/23/2022]
Affiliation(s)
- CJ Secombe
- College of Veterinary Medicine; Murdoch University; South Street Murdoch Western Australia, WA 6150 Australia
| | - GD Lester
- College of Veterinary Medicine; Murdoch University; South Street Murdoch Western Australia, WA 6150 Australia
| | - ID Robertson
- College of Veterinary Medicine; Murdoch University; South Street Murdoch Western Australia, WA 6150 Australia
| | - AM Cullimore
- College of Veterinary Medicine; Murdoch University; South Street Murdoch Western Australia, WA 6150 Australia
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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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Hamza E, Gerber V, Steinbach F, Marti E. Equine CD4(+) CD25(high) T cells exhibit regulatory activity by close contact and cytokine-dependent mechanisms in vitro. Immunology 2011; 134:292-304. [PMID: 21977999 DOI: 10.1111/j.1365-2567.2011.03489.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Horses are particularly prone to allergic and autoimmune diseases, but little information about equine regulatory T cells (Treg) is currently available. The aim of this study therefore was to investigate the existence of CD4(+) Treg cells in horses, determine their suppressive function as well as their mechanism of action. Freshly isolated peripheral blood mononuclear cells (PBMC) from healthy horses were examined for CD4, CD25 and forkhead box P3 (FoxP3) expression. We show that equine FoxP3 is expressed constitutively by a population of CD4(+) CD25(+) T cells, mainly in the CD4(+) CD25(high) subpopulation. Proliferation of CD4(+) CD25(-) sorted cells stimulated with irradiated allogenic PBMC was significantly suppressed in co-culture with CD4(+) CD25(high) sorted cells in a dose-dependent manner. The mechanism of suppression by the CD4(+) CD25(high) cell population is mediated by close contact as well as interleukin (IL)-10 and transforming growth factor-β1 (TGF-β1) and probably other factors. In addition, we studied the in vitro induction of CD4(+) Treg and their characteristics compared to those of freshly isolated CD4(+) Treg cells. Upon stimulation with a combination of concanavalin A, TGF-β1 and IL-2, CD4(+) CD25(+) T cells which express FoxP3 and have suppressive capability were induced from CD4(+) CD25(-) cells. The induced CD4(+) CD25(high) express higher levels of IL-10 and TGF-β1 mRNA compared to the freshly isolated ones. Thus, in horses as in man, the circulating CD4(+) CD25(high) subpopulation contains natural Treg cells and functional Treg can be induced in vitro upon appropriate stimulation. Our study provides the first evidence of the regulatory function of CD4(+) CD25(+) cells in horses and offers insights into ex vivo manipulation of Treg cells.
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Affiliation(s)
- Eman Hamza
- Department of Clinical Research and Veterinary Public Health, University of Bern, Bern, Switzerland.
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Current World Literature. Curr Opin Allergy Clin Immunol 2009; 9:177-84. [DOI: 10.1097/aci.0b013e328329f9ca] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Art T, Bureau F, Robinson NE. Hunting for a key to the enigma of heaves in the black box of the white cells. Vet J 2008; 177:307-8. [PMID: 18294884 DOI: 10.1016/j.tvjl.2007.12.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2007] [Revised: 11/26/2007] [Accepted: 12/02/2007] [Indexed: 11/30/2022]
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