The anti-inflammatory effects of IV administered clenbuterol in horses with recurrent airway obstruction.

This research delves into the use of clenbuterol (CB), a cyclic AMP elevating agent, in treating recurrent airway obstruction (RAO) in horses, focusing on its anti-inflammatory properties alongside its established bronchodilation effects. The study indicates that CB boosts lung function and moderates inflammation in horses exposed to different inhalation challenges.

Objective of the Study

• The aim of this research was to explore the dual action of clenbuterol, a drug typically used for bronchodilation, on horses affected by recurrent airway obstruction. In addition to its effect on dilating bronchi, clenbuterol was hypothesized to have anti-inflammatory properties, which could potentially provide additional benefits in treating RAO.

Methodology

• Seven horses vulnerable to RAO were selected for the study. To simulate the real-world triggers, these horses were exposed to aerosolised lipopolysaccharide (LPS), hay dust suspension (HDS), and Aspergillus fumigatus antigen (AF) both with and without prior treatment with intravenous clenbuterol.

Effects of Clenbuterol

• The study data revealed that clenbuterol had a significant positive effect on the lung function of the horses, reducing the total cell count and the influx of bronchoalveolar lavage neutrophils, both indicative of diminished inflammation in the lungs.
• Additionally, the drug was shown to substantially decrease the expression of several pro-inflammatory cytokines (signaling molecules used in cell communication) and chemokines in the alveolar (related to the air sacs in the lungs) macrophages of the horses after they were exposed to LPS and HDS.
• Clenbuterol also increased the expression of interleukin-6, a cytokine known to act as both a pro-inflammatory and anti-inflammatory agent, after different challenges.

Conclusions of the Study

• The research concluded that the anti-inflammatory activity of clenbuterol is a worthwhile additional benefit to its recognized use in treating equine RAO. By reducing the expression of certain pro-inflammatory elements and increasing cytokines like interleukin-6, it not only improves lung function but also seems to mitigate the inflammatory response associated with RAO.