The Effect of Inhaled Ciclesonide Treatment on Systemic Markers of Immune Function in Horses.

ABSTRACT

The use of dexamethasone to control equine asthma is a common and effective treatment. Although short-term systemic dexamethasone treatment has not been shown to induce systemic immunosuppression in the horse, the goal of this study was to determine whether inhaled ciclesonide, an FDA-approved drug for the treatment of equine asthma, exerts any systemic immunosuppressive effects when compared to dexamethasone-treated and untreated horses. Eighteen light, mixed breed horses, ranging in age from 3 to 8 years of age, were used for this study and randomly assigned to one of three treatment groups (1) nontreated controls, (2) ciclesonide treatment, or (3) dexamethasone treatment. Blood was collected daily for steady-state messenger RNA (mRNA) analysis, as well as at Days 0, 5, 10, and 15 of treatment for in vitro stimulation with Concanavalin A (ConA). Messenger RNA relative quantities were determined using RT-qPCR for select genes. Two-way, repeated measures analysis of variance was used to analyze qPCR data and results considered significant at P < .05. There were significant decreases in the steady-state, whole-blood expression of granzyme B and interferon-γ due to dexamethasone treatment, when compared to the nontreated control group. Within ConA-stimulated samples, there remained a suppressive effect of dexamethasone treatment on granzyme B expression compared to nontreated control horses. Similar effects were not noted in the ciclesonide-treated horses. Significant effects of ciclesonide treatment on markers of immune function were not noted in this study, suggesting a low risk for immunosuppression with inhaled ciclesonide treatment.