This special issue focuses on the interplay between airway microbiota and immunological processes in chronic respiratory diseases. Traditionally, microbiome research has largely centered on the gut, while the respiratory microbiome remained underexplored. However, advances in bronchoscopy over the past decade have made it safer and more feasible to collect bronchoalveolar lavage fluid and airway biopsy specimens, leading to a growing interest in the respiratory microbiome.

Bronchoscopy is now widely utilized for both diagnostic and therapeutic purposes in chronic respiratory diseases such as chronic obstructive pulmonary disease (COPD), asthma, interstitial lung disease (ILD), bronchiectasis, and certain types of lung cancer. Although various immunological mechanisms underlying these diseases have been described, significant gaps remain in our understanding of how respiratory microbes influence immune responses and disease progression.

This special issue aims to highlight recent advances in respiratory immunity and microbiomics, particularly in the context of chronic airway diseases. We welcome original research, reviews, and clinical studies, especially from respiratory endoscopists, that explore the immunological roles of airway microbiota and their diagnostic or therapeutic implications.