Study: Nanoparticles to Deliver Therapy for Heaves in Horses

Scientists at Ludwig Maximilians University’s Department of Veterinary Medicine in Munich, Germany, are applying nanoscale molecule research in human allergy suppression to horses. In a recent study the team designed and administered a nanoparticleto deliver CpG-ODN (an immunostimulating DNA that has been shown to suppress allergies in humans) to horses with recurrent airway obstruction (RAO, or heaves); the study yielded promising results.

"CpG-ODN works by producing an anti-allergic and anti-inflammatory cytokine (IL 10) that modulates the immune system to 'switch away' from the allergy and inflammatory reaction," said researcher Heidrun Gehlen, PhD, DrMedVet, Dipl. ECEIM.

Immunotherapy is the treatment of disease by modulating the immune response. Its goal is to target the allergic response directly to suppress hyperallergic reactions involved in airway inflammation. Nanoparticles are man-made devices that can deliver immunotherapy directly to cells, targeting the specific molecular mechanisms of inflammation.

To test the nanoparticle's ability to deliver the drug, the researchers measured the cytokine levels in washes from two groups of horses' respiratory systems. A group of healthy horses and a group of RAO-affected horses inhaled an aerosol formulation of the nontoxic nanoparticle/drug combination, and the researchers examined them for clinical signs of recurrent airway obstruction.

In both groups, the nanoparticle-bound drug triggered anti-inflammatory/anti-allergic cytokines after only five consecutive inhalations, showing rapid delivery of the drug. The percentage of neutrophils (white blood cells) in the lungs decreased about 40%. Arterial oxygen pressure in blood gas increased into the normal range (indicating improved lung function), and there was less mucus accumulation in the airways.

The horses with allergies showed a partial remission of allergy signs, indicating that nanoparticle-mediated drug delivery might be an effective way to treat allergies in horses, according to the authors.

Heaves is a chronic problem in horses similar to asthma in humans. Small particles pass through the upper respiratory tract to the lower respiratory tract and cause inflammation, mucus accumulation, and constriction of the horse's airways, primarily the bronchioles, which are tiny airways of the lungs. Over time, after recurrent bouts of inflammation, permanent changes occur and the airway walls become irreversibly thickened. As a result, it is more difficult for the air to flow to and from the lungs, which is why this condition is referred to as an obstructive disease.

The study, "A Nebulized Gelatin Nanoparticle-Based CpG Formulation is Effective in Immunotherapy of Allergic Horses," will be included in an upcoming issue of Pharmaceutical Research. The abstract is available online.

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.

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