Modern views on pathogenesis of bronchial hyperresponsiveness in childhood asthma

Asthma is a chronic lung disorder with the cardinal features of reversible airway obstruction, airway inflammation, and hyperresponsiveness. The last one, defines as an exaggerated bronchoconstrictor response to a nonspecific irritants, is most characteristic of asthma and is seen in all active children and most of those with no current symptoms but past diagnosis of asthma. The actual mechanism of bronchial hyperresponsiveness (BHR) in asthma remains still poorly understood, in childhood asthma also. It is widely believed that BHR is a consequence of chronic bronchial inflammation. This is supported by the observations that BHR increases with allergens exposure and is reduced by anti-inflammatory treatment. However, lack of correlation between BHR and inflammatory markers of asthma suggests the participation of other noninflammatory pathogenetic mechanisms of BHR. Both family and twin studies in asthma point to a strong genetic component of BHR. More than one genomic regions linked to asthma and associated phenotypes that include BHR had been identified in human and mouse studies. Structural remodeling of bronchial wall associated with inflammation plays an important role also. This paper reviews potential mechanisms cause of BHR which have been reported in the medical literature. It was shown that nonspecific BHR is multifactorial phenomenon with complex and still poorly known pathogenesis.