Effects of nebulized alpha-2 macroglobulin in horses with lower airway inflammation

Equine asthma is a chronic inflammatory airway disease with limited safe long-term treatments. Alpha-2-macroglobulin (A2M), a natural anti-inflammatory protease inhibitor, may provide a novel non-steroidal therapeutic option for horses with lower respiratory tract inflammation.

To characterize the impact of nebulization with alpha-2-macroglobulin (A2M) on clinical signs, bronchoalveolar lavage cytology, and local and systemic cytokine response in horses with lower respiratory tract inflammation.

Thirteen university-owned horses with lower airway inflammation were randomized into two groups. The A2M group received alpha-2-macroglobulin suspension via nebulization every 48 hours for 6 doses. The SALINE group received saline via nebulization at the same timepoints. Vital parameters and clinical respiratory score were obtained prior to each treatment and 24 hours following the sixth treatment. At these time points, a rebreathing examination was performed, bronchoalveolar lavage fluid (BALF) was analyzed for cytologic evidence of inflammation, and both BALF and plasma were tested for inflammatory cytokine concentrations using validated ELISA assays. Data were analyzed using descriptive and inferential statistics.

There were no significant changes in clinical respiratory scores in the A2M group over the treatment period. The SALINE group showed an increase in scores on days 2, 6, and 8. BALF cytology did not differ significantly between treatment groups at any time point (p > 0.05). TNF-α and IL-6 in both BALF and serum showed no significant differences between the A2M and SALINE groups throughout the study (p > 0.05).

Nebulization with A2M did not significantly alter clinical respiratory scores, airway inflammation, or inflammatory cytokines.