Influence of different dosage schedules of inhaled fluticasone propionate on peripheral blood cytokine concentrations in childhood asthma

Background Asthma is characterized by eosinophilic airways inflammation with elevated levels of IL-4, IL-5 and sICAM-1, and reduced levels of IL-10 and IFN-gamma. Inhaled corticosteroids powerfully reduce airways inflammation.

Objective To investigate if eosinophil counts, serum eosinophilic cationic protein (ECP) and sICAM-1 levels, as well as serum and production of cytokines (IL-4, IL-5, IL-10, IFN-gamma) by peripheral blood monocytes (PBMCs) are useful markers to monitor therapy with inhaled fluticasone propionate (FP) in asthmatic children.

Methods In a double-blind, 1-year study, 55 asthmatic children (aged 6-10 years) stopped inhaled corticosteroids for a mean period of 24 days and were randomized to receive either FP 200 mug/day (constant dose group), or a starting dose of FP 1000 mug/day with two monthly reductions to 500, 200 and 100 mug/day (stepdown group). Hyper-responsiveness, symptom scores and blood sampling were performed at 2-month intervals.

Results Symptoms and hyper-responsiveness improved significantly in both treatment groups after reintroduction of FP. Eosinophil counts decreased significantly more during the first 2 months of FP in the stepdown group than in the constant dose group (P = 0.03). We found a trend towards a dose-dependent response in changes of eosinophil counts and serum ECP levels during treatment. Serum IL-4 and IL-5 levels were undetectable in the majority of children. No significant effect of the dose of FP on the release of IL-4, IL-5, IL-10 or IFN-gamma by Con A stimulated PBMCs was found. sICAM-1 levels did not significantly differ at any time point between the two groups.

Conclusion Serum ECP as well as peripheral blood eosinophils, cytokine production by PBMCs and sICAM-1 levels are insensitive markers in titrating and monitoring therapy with inhaled corticosteroids over a wide dose range in childhood asthma.