Attenuation of the allergen-induced late asthmatic reaction by cyclosporin A is associated with inhibition of bronchial eosinophils, interleukin-5, granulocyte macrophage colony-stimulating factor, and eotaxin

Interleukin-5: a novel target for asthma therapy

Eosinophilic airway inflammation is the main histologic correlate of airway hyper-responsiveness (AHR) and tissue injury in the pathogenesis of bronchial asthma. There is strong evidence for a central role of CD4+ T-cells secreting pro-allergic Th2-cytokines, such as IL-4 and IL-5, in the induction of airway eosinophilia and AHR. IL-5 appears to be one of the main pro-inflammatory mediators among a growing number of cytokines and chemokines that induce, regulate and sustain eosinophilic airway inflammation. Animal studies provide confirmatory evidence for the important role of IL-5 in the induction and maintenance of eosinophilic airway infiltration leading to altered airway function. Interfering with the action of IL-5 represents one of the new immunomodulatory therapeutic strategies in the treatment of bronchial asthma. Compared to established immunosuppressive agents like steroids, a major advantage of this strategy is the specificity of reducing eosinophilic inflammation, thus possibly acting nearly without side effects. There are several possible ways to inhibit the effects of IL-5 including alteration of the signalling pathway in the IL-5 producing cell by inhibition or modification of transcription factors or the use of antisense oligonucleotides and blocking of the IL-5 protein itself by monoclonal antibodies, soluble IL-5 receptor or antagonists of the IL-5 receptor expressed on the surface of eosinophils. Although preliminary data from the first clinical trials gave rise to skepticism about the efficacy of anti-IL-5 treatment regarding the improvement of lung function of asthmatic patients, further studies with a better defined profile of the target population may provide encouraging results, allowing the introduction of this truly new therapeutic concept.

Cyclosporin as an oral corticosteroid sparing agent in stable asthma

BACKGROUND

Patients with chronic severe asthma are often dependent on the long term prescription of oral corticosteroids. The use of steroids is associated with serious side effects. Physicians treating such patients continue to search for alternative therapies that reduce the need for chronic dosing with oral steroids. Cyclosporin is an immunosuppressive agent and has benefits in the treatment of a number of inflammatory disorders. It has therefore been identified as an potentially useful agent in the treatment of chronic severe asthma both in terms of possible efficacy and as a steroid sparing agent.

OBJECTIVES

The objective of this review was to assess the effects of adding cyclosporin to oral steroids in the treatment of chronic steroid dependent asthmatics.

SEARCH STRATEGY

The Cochrane Airways Group trials register and reference lists of identified articles were searched.

SELECTION CRITERIA

Randomised trials looking at the addition of cyclosporin compared to placebo in adult steroid dependent asthmatics.

DATA COLLECTION AND ANALYSIS

Trial quality was assessed and data extraction was carried out by two reviewers independently. Study authors were contacted for missing information.

MAIN RESULTS

Three trials fulfilled the criteria for inclusion in the review and a total of 106 patients were recruited into these studies. Data from 98 patients could be analysed. There was a small but significant treatment effect for cyclosporin in terms of steroid dose reduction (SMD -0.5, 95% CI -1.0, -0.04). No meta-analyses could be performed for measures of lung function although one study showed small, but significant improvements in lung spirometry.

REVIEWER'S CONCLUSIONS

The changes with cyclosporin are small and of questionable clinical significance. Given the side effects of cyclosporin, the evidence available does not recommend routine use of this drug in the treatment of oral corticosteroid dependent asthma.