Mucus plugs-associated gene expression identifies pathophysiology shared with chronic bronchitis.

Area of Science:

• Pulmonary Medicine
• Molecular Biology
• Genomics

Background:

• Mucus plug formation and chronic bronchitis are key features of mucus pathology in chronic obstructive pulmonary disease (COPD).
• Understanding the genetic underpinnings of mucus pathology is crucial for elucidating its pathogenesis.

Purpose of the Study:

• Investigate gene expression alterations in individuals with mucus plugs.
• Identify associated biological pathways.
• Correlate mucus plug-related gene expression with clinical features of other mucus pathologies.

Main Methods:

• Utilized bulk RNA-sequencing on bronchial brush samples from 290 participants (204 discovery, 86 validation) in the "Detection of Early Lung Cancer Among Military Personnel 2" study.
• Quantified mucus plugging via chest CT scans and performed correlative analyses to identify differentially expressed genes.
• Examined associations between gene expression and chronic bronchitis symptoms.

Main Results:

• Mucus plugs were present in 37% of the discovery set.
• Differentially expressed genes were predominantly epithelial (e.g., decreased cilia maintenance, increased epithelial protection) and immune-related.
• Epithelial gene expression patterns correlated with chronic bronchitis symptoms.
• Immune gene expression varied with lung function and showed weaker association with mucus plugs compared to epithelial genes.
• Key findings were validated in an independent cohort.

Conclusions:

• Distinct gene expression patterns are associated with mucus plug presence, revealing critical biological pathways in mucus pathophysiology.
• Variability in gene expression suggests a spectrum of mucus pathophysiology underlies mucus plugs and chronic bronchitis.
• These findings provide a molecular basis for understanding mucus-related disorders in COPD.