Basic and clinical immunology
Synergistic effects of fluticasone propionate and salmeterol on in vitro T-cell activation and apoptosis in asthma

https://doi.org/10.1016/j.jaci.2004.07.052Get rights and content

Background

In asthma T cells are characterized by an increased activation state and by reduced apoptosis.

Objective

Because the clinical efficacy of inhaled corticosteroids combined with long-acting β2-agonists has been widely demonstrated in asthma, we studied, in vitro, the effect of fluticasone propionate (FP) and salmeterol alone and in combination on the activation and apoptosis of peripheral blood T cells (PBTs), on the expression of phosphorylated nuclear factor κB inhibitor (IκBα), and on the nuclear translocation of glucocorticoid receptor (GR) in PBTs from asthmatic subjects.

Methods

Apoptosis was evaluated on the basis of annexin V binding, whereas the expression of caspases 8 and 3 and phosphorylated IκBα, as well as the nuclear translocation of the GR, were evaluated by means of Western blot analysis.

Results

FP alone increases and salmeterol alone does not affect T-cell apoptosis. The combination of FP and salmeterol significantly increases PBT apoptosis in comparison with FP alone. FP at the lower concentration, when combined with salmeterol, is equivalent to FP at the higher concentration in inducing PBT apoptosis. The synergy in the induction of cell apoptosis is associated with more efficient activation of caspases 8 and 3. FP plus salmeterol is also able to synergistically reduce the expression of phosphorylated IκBα, thus limiting nuclear factor κB activation. The synergy was related to an increased nuclear translocation of the GR.

Conclusion

This study shows that the combination of FP and salmeterol is able to control PBT activation in asthmatic patients more efficiently than FP alone and with a lower concentration of steroids.

Section snippets

Subjects

We selected 15 patients with mild intermittent asthma (age, 9-13 years), according to the criteria of the American Thoracic Society. The diagnosis of asthma and the assessment of its severity were performed at study entry according to Global Initiative for Asthma guidelines.13 None of the patients received any corticosteroid treatment during the previous 2 weeks.

The study fulfilled the criteria of the ethics committee of our hospital, and all subjects, parents, or both provided informed consent.

FP and salmeterol in combination increase apoptosis in resting PBTs

FP significantly increased PBT apoptosis in a dose-dependent manner when compared with baseline values, whereas salmeterol alone did not affect spontaneous PBT apoptosis at either tested time point. Interestingly, the combined presence of FP at all the tested concentrations and salmeterol was able to significantly increase PBT apoptosis at both time points. Moreover, FP at the concentration of 10−9 M when combined with salmeterol was not statistically different from FP at the concentration of 10

Discussion

A main goal of asthma therapy is to achieve optimal control of airway inflammation. ICSs are the mainstay of asthma management and are extremely effective inhibitors of T-cell activation7 and TH2 cytokine production.21

Previous reports demonstrated the clinical utility of combined use of glucocorticoids and LABAs in the improvement of patient symptoms and airflow limitation.10 This study shows, for the first time, a synergistic proapoptotic effect of FP and salmeterol on resting and activated T

References (30)

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Supported by the Italian National Research Council and by GlaxoSmithKline.

Potential conflict of interest: E. Pace has received research support from GlaxoSmithKline. No other conflicts of interest are declared.

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