Research Article: Effect of bronchial thermoplasty on airway inflammatory and profibrotic gene expression after one?year follow?up in severe asthma
Abstract:
Bronchial thermoplasty (BT) reduces symptoms in severe asthma, but its mechanisms remain poorly understood. This preliminary study aimed to investigate the effect of BT on bronchial gene expression and its associations with airway structural changes.
Bronchoscopy with endobronchial ultrasound (EBUS), bronchoalveolar lavage (BAL), and endobronchial biopsies was performed in 10 patients with severe asthma before and 12 months after BT. We assessed BAL cytology, biopsy histomorphometry, and mRNA expression of genes related to immune (e.g., innate or type-2 related) and profibrotic responses.
BT resulted in significant improvement in asthma control (ACT score increased from median 14 to 18, p = 0.0078) and a reduction in exacerbation rate (from 5 to 1, p = 0.0020). Spirometric measures of airflow obstruction did not improve, but air trapping decreased (RV/TLC from 0.47 to 0.39, p = 0.0078) after BT. An increase in BAL eosinophils was observed (from 0.3% to 3.7%, p = 0.0020), predominantly in patients with greater reductions in systemic corticosteroids. Histological analysis showed a significant reduction in the airway smooth muscle (ASM) mass, while gene-expression data demonstrated only moderate upregulation of remodeling-related transcripts (e.g., COL3A1 , GDNF ). These molecular changes were not associated with bronchial structural or spirometric parameters and likely reflect shifts in local inflammatory patterns.
BT does not appear to fundamentally alter the immunological profile in the treated airways but is associated with a decrease in ASM thickness along with features of fibrosis. This was associated with increased BALF eosinophilia, suggesting heterogeneous effect of BT across airway compartments, further modified by corticosteroid reduction accompanying clinical improvement.
Introduction:
Bronchial thermoplasty (BT) reduces symptoms in severe asthma, but its mechanisms remain poorly understood. This preliminary study aimed to investigate the effect of BT on bronchial gene expression and its associations with airway structural changes.
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