CHEST Guidelines-Unraveling-the-Pathophysiology-of-the-Asthma-COPD-

Unraveling-the-Pathophysiology-of-the-Asthma-COPD-

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The article from CHEST delves into the complex interplay between asthma and COPD in patients, discussing a subset where the two overlap, known as the asthma-COPD overlap syndrome (ACOS). Despite treatment, some asthmatics—particularly never smokers—with chronic asthma experience persistent expiratory airflow limitations. This phenomenon has been traditionally attributed to airway remodeling, but the study highlights a recently uncovered factor: unsuspected, mild centrilobular emphysema.<br /><br />This study involved ten asthmatics who had never smoked and who, despite treatment, exhibited expiratory airflow obstruction. Significant findings from this study included a notable decrease in lung elastic recoil and the presence of mild centrilobular emphysema discovered upon autopsy, which was not easily detectable through common diagnostic methods like lung CT scans. The authors suggest that the emphysema and airflow issues in these patients might be related to a subtle lung tissue breakdown, linked to pro-inflammatory and proteolytic pathways within the lungs.<br /><br />Investigations point to the possibility that recurring asthma attacks may induce inflammation in terminal bronchioles, triggering pathways that lead to tissue breakdown similarly seen in smokers. Besides, the lung tissue of never-smoking individuals with chronic asthma showed typical asthmatic remodeling but also exhibited mild emphysema, a finding requiring further confirmation and understanding of the mechanisms involved.<br /><br />The study underscores the need for in-depth structure-function studies, including advanced imaging and physiological measurements, to better understand ACOS and its pathophysiological underpinnings. These findings suggest a need for a potential reevaluation of asthma treatment in a subset of patients presenting with ACOS and warrant further research into identifying specific trigger mechanisms and therapeutic options to mitigate this overlap syndrome's effects.

Keywords

asthma-COPD overlap syndrome

ACOS

expiratory airflow limitation

centrilobular emphysema

airway remodeling

lung elastic recoil

pro-inflammatory pathways

proteolytic pathways

asthma treatment

lung tissue breakdown