STEROID-THERAPY AND BRONCHIAL INFLAMMATIO N IN THE ASTHMATIC

The development of fibreoptic bronchoscopy has enabled significant pro gress in the understanding of the pathogenesis of asthma. It has broug ht to the Sore rite importance of bronchial inflammation even in asymp tomatic patients and/or in patients who have only mild disease. The pr actice of bronchial biopsy in vivo is an excellent method of studying bronchial inflammation. The purpose of this general review is to recal l the value of bronchial biopsies in the understanding of rite effects of steroids on asthma: effects on the epithelium, the basement membra ne and the blood vessels. Their cellular contents consist equally of c ytokines, enzymes and adhesion molecules. At the level of the bronchia l epithelium steroid therapy engenders a diminution in eosinophils, ma st cells and lymphocytes. it restores the ratio of ciliated to other c ells back to normal and increases the number of nerve synapses. Regard ing the interstitium the corticoids diminish rite number of eosinophil s, mast cells and T lymphocytes. The effect oil different lymphocyte s ubtypes is controversial, as is the effect of the basal membrane. Ster oid therapy diminishes the proteins GM-CSF.RANTES and IL-8 as well as the messengers IL-4, IL-13 and IL-5. It seems to increase the messenge r for IFN-gamma and IL-12 and favourable: modulates the vascular compo sition to inflammation in asthma. Nevertheless it is to be regretted t hat too Sew studies have looked at the correlations between histologic al changes and clinical and respiratory function improvement engendred by steroid therapy.