Quantitative and morphological analysis of the vascular bed in bronchial biopsy specimens from asthmatic and non-asthmatic subjects

Abstract

Background-This study was designed to establish the number and area (as a percentage) of bronchial wall vessels in subjects with and without asthma, to obtain information on the morphology of the vessels, and to see whether changes diVered in patients with mild, moderate, and severe asthma. Methods-Biopsy specimens were taken using a rigid bronchoscope from the carina of the middle lobe bronchus of 20 patients with allergic asthma and 20 non-asthmatic controls. Specimens were sectioned and stained with haematoxylineosin, Masson trichrome, PAS, alcian blue-PAS, and orcein. The vessels were counted and the vascular area was calculated as a percentage in the lamina propria, in blind conditions, on PAS stained sections in 50 microscopic fields (magnification ×1000, 0.02 mm 2 per field). The vascular area was calculated using the points counting procedure (Chalkley point array). The vascular morphology, intravascular cells, and the perivascular area were also studied using a magnification up to ×1200. Results-Patients with asthma had more vessels (mean (SD) 226.70 (74.53) v 172.05 (30.58), p=0.0043) and a larger percentage vascular area (8.61 (2.38)% v 6.81 (2.25)%, p=0.028) than non-asthmatic subjects. Patients with severe asthma had significantly more vessels than those with mild or moderate disease (p=0.0044). Asthmatic capillaries and venules had oedematous walls and thickening of the subendothelial basement membrane, and hypotrophic or atrophic myocytes and fibrosis in the arterioles. Vessels from asthmatic subjects showed eosinophil recruitment, activation, and intravascular lysis. Intense eosinophil recruitment was associated with more marked vascular structural changes. Muscular formations protruded into the lumen in the arterioles of both groups, and in asthmatics these had hypotrophic or atrophic myocytes and fibrosis. Conclusions-Morphometric analysis showed that the bronchial lamina propria of asthmatic subjects had a larger number of vessels, occupying a larger percentage area than in non-asthmatic subjects. The number of vessels was correlated with the severity of the asthma. Marked alterations to the vascular structure appeared to be associated with intense eosinophil recruitment and intravascular activation. This is the first report of asthmatic and non-asthmatic bronchial wall specimens containing intra-arteriolar muscular formations, presumably to regulate blood flow to the capillary network and/or sinusoids. This function might be impaired when these structures are remodelled in asthmatic patients. (Thorax 2001;56:902-906)

The contribution of transforming growth factor-β and epidermal growth factor signalling to airway remodelling in chronic asthma

“…HARMANCI et al [43] demonstrated that bronchial wall thickening was more prominent with increased severity, decreased forced expiratory volume in one second (FEV1) values and the duration of asthma. The submucosa of asthmatic subjects contained more blood vessels; this also correlated with the severity of the disease [44].…”

Aerobic conditioning and allergic pulmonary inflammation in mice. II. Effects on lung vascular and parenchymal inflammation and remodeling

“…The increased deposition of extracellular matrix in pulmonary vessels and parenchyma in asthma presents a significant clinical implication and has an important correlation with asthma severity, including airflow limitation and bronchial hyperresponsiveness (4,16,21,31,48,49,58,59). Although there are differences between human asthma and murine models of asthma, we are aware that animals do not develop asthma and that there are several limitations in animal studies.…”

Pulmonary vascular changes in asthma and COPD

“…The density of vessels in the medium (2-5mm inner diameter) and small (<2mm) airways is significantly elevated in mild and moderate-to-severe asthma compared to healthy controls or subjects with COPD [7] and has been linked to asthma severity [78,82]. Furthermore, the increased density of vessels was reported to be associated with asthmatic subjects with the most hyperresponsive airways [83].…”