Pulmonary remodeling in asthma.

ABSTRACT

For many years it was assumed that all asthmatics had an at least potentially reversible disease. It is now clear both from longitudinal studies of FEV1 and biopsy data that some asthmatics develop permanent obstructive lung disease. Some adults exhibit an accelerated decline in lung function, and some children never reach normal lung volume. The most likely histologic changes accounting for this phenomena are the deposition of collagen and glycoprotein beneath the basement membrane and in the extracellular matrix, and the destruction of elastic tissue. This permanent obstruction does not occur in all asthmatics. Factors that place patients at increased risk appear to be related to the severity and the duration of the disease and the degree of bronchial hyperresponsiveness. It is unclear, based upon present data, as to whether or not inhaled corticosteroids can favorably affect the process of remodeling, but evidence seems to favor this hypothesis. Inhaled corticosteroids, in some studies, have been shown to decrease the thickness of the lamina reticularis and retard the decline in FEV1. In addition, removal of the source of asthma, as demonstrated in occupational asthma due to toluene diisocyanate, can have a beneficial effect in this regard.