Rapid communication Effect of inhaled glucocorticoids on IL-1b and IL-1 receptor antagonist (IL-1ra) expression in asthmatic bronchial epithelium

IL-1b is produced by many different cell types such as monocytes, tissue macrophages, Background – Accumulating evidence suggests that the cytokine network is central to alveolar macrophages, lymphocytes, mast cells or basophilic cell lines, smooth muscle and the immunopathology of bronchial asthma and the existence of naturally occurring endothelium. It has a wide spectrum of activities but, of particular importance in asthma, cytokineantagonists hasaddedto thiscomplexity. Upregulation of both interleukin 1b is its ability to stimulate granulocytes, B and T lymphocytes, endothelium, epithelium, and (IL-1b)anditsnaturallyoccurringreceptor antagonist, interleukin 1 receptor antaghaemopoietic cells. Evidence that IL-1b contributes directly to onist (IL-1ra), has previously been observed on asthmatic bronchial epithelium the pathology of asthma comes from studies of the intratracheal administration of IL-1b in compared with normal airways. Methods – The effect of inhaled becloBrown Norway rats which resulted in inmethasone dipropionate (BDP) on asthflammatory changes, including an increased matic bronchial epithelial expression of neutrophil count in bronchoalveolar lavage IL-1b and IL-1ra was studied. Frozen (BAL) fluid and increased airway responbronchial biopsy specimens from nine siveness to bradykinin. Work on alveolar asthmatic subjects receiving 1000 lg BDP macrophages of asthmatic subjects has shown daily for eight weeks and from six asththat IL-1b expression is upregulated and that matic subjects receiving matching placebo the level of IL-1b in the BAL fluid of subjects were stained with anti-IL-1b and anti-ILwith symptomatic asthma is higher than that of 1ra antibodies. Hue-saturation-intensity normal subjects or subjects with asymptomatic (HSI) colour image analysis was used to asthma. In addition, BAL fluid from sympquantify the brown immunoperoxidase retomatic, non-allergic asthmatic subjects has inaction colour present on the bronchial epicreased levels of IL-1, as well as tumour thelium. necrosis factor (TNF) and IL-6. Results – There was a significant twofold IL-1ra is produced by a similar range of cell decrease in the epithelial expression of ILtypes to IL-1b – mainly monocytes, macro1b after treatment with BDP but no sigphages, neutrophils, fibroblasts, and kernificant change was seen in IL-1ra (p= atinocytes. It may protect against bronchial Department of Allergy and Respiratory 0.175). asthma as exposure of ovalbumin sensitised Medicine Conclusion – The selective inhibition of guinea pigs to an aerosol of IL-1ra immediately A R Sousa IL-1b, without effect on IL-1ra, provides a before antigen challenge results in a marked C J Trigg S J Lane novel mechanism for the anti-inflamprotection against bronchial hyperreactivity R Hawksworth matory action of glucocorticosteroids. and accumulation of pulmonary eosinophils. T H Lee (Thorax 1997;52:407–410) TNF bioreactivity in the BAL fluid of antigen Department of challenged animals was also significantly re