[Contribution of hypoxia in pulmonary tissue remodeling in asthmatic processes].

Asthma is a chronic airway inflammatory disease that is associated with pulmonary remodelling of respiratory tissue. During asthma, lung structure changes due to persistent inflammation and causes obstruction of the air flow, which leads to a paradoxical hypoxic condition in the affected pulmonary tissue. Angiogenesis, which is one of the main components of the remodelling process, is mainly regulated by the vascular endothelial growth factor (VEGF), although other less influential factors are also involved. It is known that VEGF is up-regulated by hypoxia inducible factor 1 (HIF-1) during hypoxia. The transcription factor HIF-1 is a dimeric protein composed of two subunits: HIF-1alpha (inducible by hypoxia) and HIF-1beta (constitutive). HIF-1 activates the transcription of genes during hypoxia by translocating to the nucleus and binding to hypoxia response elements (HREs) on the promoter regions of target genes. Recently the expression of HIF has been documented during angiogenesis in lung remodelling during asthma, thus suggesting that it may play a role in this process. The objective of this review is to give to the reader an overview of the literature in hypoxia and its role in remodelling and the pathogenesis of asthma.