Tracheobronchial mucus viscoelasticity during environmental challenge in horses with recurrent airway obstruction.
Abstract: The goal of this study was to compare the rheological properties of mucus from horses with recurrent airway obstruction (RAO) to that from healthy controls during environmental challenge by stabling in stalls with straw as bedding and hay as feed. We determined viscoelasticity (log G* dyn/cm2, at 10 radian/s) and calculated mucociliary clearability index (MCI) and cough clearability index (CCI), which are derivative parameters of G* and the ratio of viscosity and elasticity measured at 1 and 100 radian/s, respectively. We also investigated the solids content of mucus, and cytology of bronchoalveolar lavage fluid (BALF). Samples were obtained before (0 h) and 6, 24 and 48 h after environmental challenge. The central findings were rheological changes in airway mucus, which occurred over time in RAO-affected animals, but not in controls. Mucus rheology was similar in both groups at 0 and 6 h. In RAO-affected horses, mucus viscoelasticity, as measured by log G*, increased from 2.49 +/- 0.18 dyn/cm2 (mean +/- s.e.) at 0 h to 3.05 +/- 0.13 dyn/cm2 at 24 h after environmental challenge, and was accompanied by significant decreases in MCI and CCI. Percent solids of mucus did not differ significantly between the 2 groups, nor over time. Rheological values did not correlate with BALF cytology. We conclude that viscoelastic properties of tracheal mucus samples from RAO horses in remission do not differ from those of normal horses. However, environmental challenge causes clinical signs of small airway disease and a concurrent increase in mucus viscoelasticity only in RAO horses. Therefore, we infer that unfavourable changes in mucus rheology may contribute to stasis and accumulation of mucus in RAO horses in exacerbation, but not in clinical remission.
Publication Date: 2000-10-19 PubMed ID: 11037263DOI: 10.2746/042516400777591183Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
- Research Support
- U.S. Gov't
- Non-P.H.S.
Summary
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This research sought to investigate and compare the properties of mucus in horses affected by recurrent airway obstruction (RAO) and healthy ones when exposed to an environmental challenge. Key findings revealed that changes in mucus properties occurred over time in RAO-affected horses but not in healthy ones, suggesting that unfavorable modifications in mucus rheology might be linked to mucus accumulation in RAO horses.
Objectives and Methodology
- The study aimed to compare the rheological (flow and deformation) properties of mucus from RAO-affected horses and healthy ones during an environmental challenge.
- This was achieved by stabling these horses in stalls that used straw for bedding and hay for feeding.
- Several parameters were assessed including: mucus viscoelasticity (a measure of the viscosity and elasticity of the mucus), mucociliary clearability index (MCI), cough clearability index (CCI) and the solids content of the mucus.
- The cytology (cellular study) of bronchoalveolar lavage fluid (BALF) – a tool in diagnosing lung diseases – was investigated too.
- Mucus samples were collected before and 6, 24, and 48 hours after the environmental challenge.
Key Findings
- The central discovery of the study was that changes in mucus properties were seen over time in RAO-affected horses but not in the control group, suggesting a response to the environmental challenge in the former group.
- The properties of the mucus in both groups were similar before and after the first 6 hours of the environmental challenge.
- However, in RAO-affected horses, there was a significant increase in mucus viscoelasticity and a reduction in MCI and CCI 24 hours after the challenge.
- The composition of the mucus in terms of solids content did not differ significantly between the two groups or over time.
- The study also found no correlation between the rheological values (properties) and BALF cytology.
Implications and Conclusion
- The results indicate that the viscoelastic properties of tracheal mucus samples from RAO horses in remission do not differ from those of normal horses under normal conditions.
- However, the introduction of an environmental challenge triggers clinical signs of small airway disease and an associated increase in mucus viscoelasticity in RAO-affected horses.
- These findings suggest that unfavorable changes in mucus rheology may be underlying the stasis and accumulation of mucus observed in RAO horses during exacerbations.
- However, these changes are not present when the animals are in clinical remission, highlighting the need for more targeted environmental management for RAO-affected horses.
Cite This Article
APA
Gerber V, King M, Schneider DA, Robinson NE.
(2000).
Tracheobronchial mucus viscoelasticity during environmental challenge in horses with recurrent airway obstruction.
Equine Vet J, 32(5), 411-417.
https://doi.org/10.2746/042516400777591183 Publication
Researcher Affiliations
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing 48824, USA.
MeSH Terms
- Airway Obstruction / physiopathology
- Airway Obstruction / veterinary
- Animals
- Bronchi / metabolism
- Bronchoalveolar Lavage Fluid / chemistry
- Chronic Disease
- Horse Diseases / physiopathology
- Horses
- Housing, Animal
- Mucus
- Respiratory Hypersensitivity / physiopathology
- Respiratory Hypersensitivity / veterinary
- Rheology
- Trachea / metabolism
- Viscosity
Citations
This article has been cited 7 times.- Luettich K, Sharma M, Yepiskoposyan H, Breheny D, Lowe FJ. An Adverse Outcome Pathway for Decreased Lung Function Focusing on Mechanisms of Impaired Mucociliary Clearance Following Inhalation Exposure.. Front Toxicol 2021;3:750254.
- Klier J, Bartl C, Geuder S, Geh KJ, Reese S, Goehring LS, Winter G, Gehlen H. Immunomodulatory asthma therapy in the equine animal model: A dose-response study and evaluation of a long-term effect.. Immun Inflamm Dis 2019 Sep;7(3):130-149.
- Klier J, Geis S, Steuer J, Geh K, Reese S, Fuchs S, Mueller RS, Winter G, Gehlen H. A comparison of nanoparticullate CpG immunotherapy with and without allergens in spontaneously equine asthma-affected horses, an animal model.. Immun Inflamm Dis 2018 Mar;6(1):81-96.
- Weigand WJ, Messmore A, Tu J, Morales-Sanz A, Blair DL, Deheyn DD, Urbach JS, Robertson-Anderson RM. Active microrheology determines scale-dependent material properties of Chaetopterus mucus.. PLoS One 2017;12(5):e0176732.
- Duncan GA, Jung J, Hanes J, Suk JS. The Mucus Barrier to Inhaled Gene Therapy.. Mol Ther 2016 Dec;24(12):2043-2053.
- Klier J, Lehmann B, Fuchs S, Reese S, Hirschmann A, Coester C, Winter G, Gehlen H. Nanoparticulate CpG immunotherapy in RAO-affected horses: phase I and IIa study.. J Vet Intern Med 2015 Jan;29(1):286-93.
- Lai SK, Wang YY, Wirtz D, Hanes J. Micro- and macrorheology of mucus.. Adv Drug Deliv Rev 2009 Feb 27;61(2):86-100.
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