Serum concentration of surfactant protein D in horses with lower airway inflammation.
Authors: Richard E A, Pitel P-H, Christmann U, Lekeux P, Fortier G, Pronost S
Journal: Equine veterinary journal
Summary
# Editorial Summary: Serum Surfactant Protein D as a Biomarker for Equine Lower Airway Inflammation Surfactant protein D (SP-D), produced by alveolar type II cells and bronchiolar epithelium, functions as a critical component of innate lung immunity and has established clinical utility as a pulmonary injury biomarker in human medicine. This 2012 investigation extended previous work beyond experimental bacterial infection models to characterise serum SP-D concentrations in horses presenting with naturally occurring lower airway inflammation, potentially offering equine practitioners a non-invasive biomarker for respiratory tract pathology. The researchers measured circulating SP-D levels across horses with varying degrees of lower airway disease and correlated findings with inflammatory markers and clinical status. Elevated serum SP-D concentrations distinguished horses with lower airway inflammation from healthy controls, suggesting that systemic SP-D measurement could complement existing diagnostic approaches such as tracheal aspiration and bronchoalveolar lavage. For clinical practitioners, the ability to assess pulmonary inflammation through serum sampling—rather than invasive airway sampling alone—could streamline diagnosis of equine recurrent airway obstruction, inflammatory airway disease, and other lower respiratory conditions, whilst reducing stress on compromised horses during initial assessment.
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Practical Takeaways
- •Serum SP-D measurement may offer a non-invasive biomarker for detecting and monitoring lower airway inflammation in clinical practice
- •SP-D could help differentiate pulmonary injury severity and guide treatment decisions for horses with respiratory disease
- •Further research is needed to establish reference ranges and clinical thresholds for SP-D in horses with naturally occurring airway disease
Key Findings
- •Surfactant protein D (SP-D) is synthesized by alveolar type II cells and nonciliated bronchiolar cells as a component of innate pulmonary immunity
- •Serum SP-D concentrations can serve as biomarkers for pulmonary injury in horses, paralleling established clinical use in human medicine
- •This study extends previous experimental bacterial infection models to investigate SP-D levels in natural cases of lower airway inflammation