On the functional consequences of bronchial basement membrane thickening

Abstract

Reticular basement membrane (RBM) thickness and airway responses to inhaled methacholine (MCh) were studied in perennial allergic asthma (n = 11), perennial allergic rhinitis (n = 8), seasonal allergic rhinitis (n = 5), and chronic obstructive pulmonary disease (COPD, n = 9). RBM was significantly thicker in asthma (10.1 +/- 3.7 microm) and perennial rhinitis (11.2 +/- 4.2 microm) than in seasonal rhinitis (4.7 +/- 0.7 microm) and COPD (5.2 +/- 0.7 microm). The dose (geometric mean) of MCh causing a 20% decrease of 1-s forced expiratory volume (FEV(1)) was significantly higher in perennial rhinitis (1,073 microg) than in asthma (106 microg). In COPD, the slope of the linear regression of all values of forced vital capacity plotted against FEV(1) during the challenge was higher, and the intercept less, than in other groups, suggesting enhanced airway closure. In asthma, RBM thickness was positively correlated (r = 0.77) with the dose (geometric mean) of MCh causing a 20% decrease of FEV(1) and negatively correlated (r = -0.73) with the forced vital capacity vs. FEV(1) slope. We conclude that 1) RBM thickening is not unique to bronchial asthma, and 2) when present, it may protect against airway narrowing and air trapping. These findings support the opinion that RBM thickening represents an additional load on airway smooth muscle.

Relationship between past airway pathology and current lung function in preschool wheezers

“…Indeed, it has been proposed that RBM thickening may be protective rather than deleterious [5,6]. Although our failure to show a relationship between RBM thickness and impaired lung function may be a power issue, it is also compatible with the view that increased RBM thickness does not have adverse physiological effects [6].…”

“…However, the physiological consequences of pathological changes in the asthmatic airways are poorly understood. While some adult studies show that increased reticular basement membrane (RBM) thickness is associated with airway obstruction [4], others show that RBM thickening is protective against bronchoconstriction [5,6]. Contemporaneous studies of pathology and function in preschool children with recurrent wheeze are lacking, due to ethical concerns over performing endobronchial biopsies and preschool lung function testing being limited to specialist centres.…”

Airway Remodeling in Asthma and its Influence on Clinical Pathophysiology

“…They revealed that the thickness of basement membrane in the patients with mild perennial asthma and perennial allergic rhinitis was significantly higher than in the patients with seasonal rhinitis and COPD. In addition, thickness of basement membrane in the patients with asthma showed a positive relationship with provocative dose of methacholine in airway hyperresponsiveness (Milanese et al 2001). These results suggest that reduction of elasticity in airway is associated with progress of thickness of basement membrane.…”

“…Ward et al (2001) showed a negative relationship between the distensibility of airway and thickness of basement membrane. Furthermore, Milanese et al (2001) measured thickness of epithelial basement membrane of bronchial tissues obtained by transbronchial biopsy from patients with mild perennial asthma, perennial allergic rhinitis, seasonal rhinitis and chronic obstructive pulmonary disease (COPD). They revealed that the thickness of basement membrane in the patients with mild perennial asthma and perennial allergic rhinitis was significantly higher than in the patients with seasonal rhinitis and COPD.…”

Airway smooth muscle dynamics: a common pathway of airway obstruction in asthma

“…Airway remodelling is a well-documented phenomenon associated with asthma development. Thickening of some airway wall components seen in asthmatic airways may contribute to excessive airway narrowing [146]; thickening of other components may have a protective effect against excessive narrowing [147][148][149][150][151]. Many of these predictions were based on computer simulations of geometrical changes in airway components and, therefore, were limited by the assumptions associated with the simulation.…”