Effects of mixed polyphenol supplementation on lower airway inflammation in horses with Equine Asthma Syndrome.

Overview

• This study investigated whether giving horses with Equine Asthma Syndrome (EAS) a mixed polyphenol dietary supplement could reduce lung inflammation and improve respiratory symptoms.
• Researchers found that polyphenol supplementation reduced specific inflammatory markers in the lungs and improved clinical signs in mildly asthmatic horses.

Background and Objective

• Equine Asthma Syndrome (EAS): A chronic inflammatory disease affecting the lower airways of adult horses, causing respiratory symptoms and lung inflammation.
• Polyphenols: Natural compounds found in plants known to have anti-inflammatory properties in humans, especially in asthma; however, their effects had not been studied in horses with asthma.
• Study Objective: To evaluate how a mixed polyphenol supplement affects systemic (whole body) and pulmonary (lung) inflammation, lung cell populations, and clinical respiratory signs in both healthy and asthmatic horses.
• Hypothesis: Polyphenol supplementation would reduce inflammation in both healthy and asthmatic horses and improve lung cell profiles and clinical respiratory symptoms in asthmatic horses.

Study Design and Methods

• The study was conducted in two parts involving a total of 28 adult horses (healthy and asthmatic).
• Part One:
  • Participants: 18 horses (8 healthy, 10 asthmatic).
  • Intervention: All received a daily mixed polyphenol supplement for 6 to 8 weeks.
  • Measurements: Physical exams, bronchoalveolar lavage (BAL) cytology (to analyze lung immune cells), and cytokine levels in blood serum and BAL fluid were taken before and after supplementation.
• Part Two:
  • Participants: 10 asthmatic horses divided randomly into two groups (5 supplemented, 5 control).
  • Protocol: All horses fed a low-dust diet for 4 weeks, with or without polyphenol supplementation depending on group.
  • Then, they were exposed to dusty hay for 4 weeks to exacerbate airway inflammation.
  • Assessments: Clinical respiratory signs, rebreathing exam results (to evaluate lung function), and pulmonary inflammation were measured.

Key Findings

• Part One Findings:
  • In asthmatic horses, the percentage of neutrophils (immune cells linked to inflammation) in the BAL fluid significantly decreased after supplementation, indicating reduced lung inflammation.
  • Levels of interleukin-6 (IL-6), a pro-inflammatory cytokine in BAL fluid, also significantly decreased in asthmatic horses.
  • There was a notable decrease in interleukin-10 (IL-10), which often has anti-inflammatory roles, particularly in asthmatic horses compared to healthy ones, suggesting a complex immune modulation.
• Part Two Findings:
  • Fewer supplemented horses showed abnormal lung function on rebreathing exams after being exposed to dusty hay compared to controls, suggesting protective effects of polyphenols.
  • Supplemented horses had significantly lower respiratory rates, indicating less respiratory distress during inflammation exacerbation.

Conclusions and Implications

• Polyphenol supplementation appears to modify lung inflammation markers in horses with mild Equine Asthma Syndrome.
• The supplementation combined with environmental management (low-dust diet) improved clinical respiratory signs and lung function during airway inflammation exacerbation.
• These results suggest that dietary polyphenols could be a useful adjunct therapy for managing Equine Asthma Syndrome by reducing airway inflammation and improving symptoms.
• Further studies with larger groups and longer duration may help confirm these benefits and optimize dosages.