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SELECTED ARTICLES FROM THE RECENT LITERATURE 2006
12/4/06
Effects of inhaled ciclesonide on T lymphocyte sub-populations
Summary
Background - The mechanisms underlying the inhibition by inhaled corticosteroid (ICS) drug treatment of the late phase asthmatic response (LPR) to inhaled allergens are still not well defined. Previous studies have shown that this LPR to inhaled allergen is accompanied by decreased levels of interferon-gamma (IFN-g) positive lymphocytes (Th1 marker) in the blood and sputum.
Findings - Kawayama et al of the Mc Master Univ in Hamilton, ON, Canada assessed the effects of prior inhalation of ciclesonide (Cic), an ICS pro-drug, 40 and 80 mcg vs placebo on the inflammatory responses to inhaled aeroallergens in allergen-sensitive subjects. They found that prior inhalation of Cic, but not inhalation of placebo, inhibited the LPR and associated eosinophil accumulation response to allergen inhalation. There was also inhibition of the decrease in blood levels of IFN-g positive T cells. But, of note, neither the allergen inhalation nor the Cic pre-treatment affected the levels of IL-4 -positive T cells.
Reference
Clin Exp Allergy 2006;36:14417-24
Editor's Comments
These findings are of interest on several accounts. Cic is actually a pro-drug, being converted enzymatically in the lower airways into a metabolite with potent ICS activity. This metabolite is likely responsible for the T cell changes found in this study, likely after systemic absorption of the metabolite. It is also of note that allergen inhalation challenge did not result in an increase in a Th2 marker (IL4 -positive T cells) in the blood. Cic pre-treatment did not affect the frequency of IL-4 positive T cells either.
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