Bronchial angiogenesis in severe glucocorticoid-dependent asthma

To examine the role of the bronchial microvasculature and adhesion molecule expression in severe asthma, the authors have performed an immunohistochem ical study on bronchial biopsies comparing 15 glucocorticoid-dependent asth matics, 15 mild asthmatics and eight control subjects. Serially cut glycol methacrylate-embedded sections were stained with monocl onal antibodies identifying the vessel marker EN-4, intercellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM)-1. E- and P-selec tin, Sections were also stained for lymphocyte function associated antigen (LFA)-1 and very late antigen (VLA)-4. By comparison with mild asthma and nonasthma, severe asthma was characteriz ed by increased numbers of submucosal vessels (p=0.009) which was associate d with increased numbers of vessels expressing ICAM-1 (p=0.005). A highly s ignificant correlation was found between the total number of EN-4+ vessels and the vessels expressing ICAM-1 (r=0.85, p=0.01), in contrast, E-selectin expression was lower in severe as compared with mild asthma (p=0.01) but n ot different from normal. No differences were found between the three group s in the expression of VCAM-1 and P-selectin nor in numbers of LFA-1+ and V LA-4+ cells. The results of this study support the notion that mucosal neovascularizatio n is an important feature of airways remodelling in severe asthma. This is associated with a relatively higher density of vessels expressing intercell ular adhesion molecule-1, although the expression of this adhesion molecule per vessel was not raised.