The following is a summary of “Airway wall extracellular matrix changes induced by bronchial thermoplasty in severe asthma,” published in the February 2024 issue of Allergy & Immunology by Wijsman, et al.

A prominent feature of asthma is airway remodeling, characterized by increased airway smooth muscle mass and altered extracellular matrix composition. Bronchial thermoplasty (BT), a bronchoscopic treatment for severe asthma, targets airway remodeling to improve clinical outcomes. For a study, researchers sought to investigate the effect of BT on extracellular matrix composition and its association with clinical outcomes.

The substudy was part of the TASMA trial and included thirty patients with severe asthma who underwent BT treatment. Thirteen patients received standard therapy for six months before BT (control group). Demographic and clinical data, including pulmonary function, were collected, along with bronchial biopsies. Histological and immunohistochemical staining was performed on biopsies from BT-treated and nontreated locations, and associations between histology and clinical outcomes were explored.

After six months of treatment, reticular basement membrane thickness decreased from 7.28 μm to 5.74 μm (21% relative reduction), while the percentage area of tissue positive for collagen increased from 26.3% to 29.8% (13% relative increase). Collagen structure analysis revealed a reduction in fiber curvature frequency. The percentage area positive for fibulin-1 and fibronectin increased by 2.5% and 5.9%, respectively (relative increases of 124% and 15%). No changes were observed for elastin. Changes in collagen and fibulin-1 were negatively associated with changes in FEV1 reversibility.

In addition to reducing airway smooth muscle mass, BT influenced reticular basement membrane thickness and extracellular matrix arrangement, characterized by increased collagen area with less dense fiber organization. Both collagen and fibulin-1 were negatively associated with changes in FEV1 reversibility, suggesting their potential role in clinical outcomes following BT treatment for severe asthma.

Reference: jacionline.org/article/S0091-6749(23)01247-2/fulltext