Emphysema: looking beyond alpha-1 antitrypsin deficiency

ABSTRACT

Introduction: Distinct pathologies can cause chronic obstructive pulmonary disease (COPD). Emphysema is a COPD-phenotype characterized by destruction of lung parenchyma. Alpha-1 antitrypsin deficiency (AATD) is a genetic cause of emphysema, whereas smoking is the most important risk factor of non-AATD emphysema. A general underappreciation of non-AATD emphysema has hampered progress in the field, and clinical guidelines have prohibited the use of emphysema as a diagnosis. Non-AATD emphysema, however, is far from irrelevant as it associates with dyspnea, reduced exercise capacity and relevant outcome measures.

Areas covered: Mechanisms underlying enhanced tissue loss in emphysema are protease/antiprotease imbalance, increased oxidative stress, several fundamental cell biological processes such as programmed cell death and autophagy, and impaired repair mechanisms. Therapeutic options for emphysema vary from smoking cessation to lung volume reduction. Current pharmacological treatments have less favorable effects in emphysematous than in non-emphysematous COPD patients.

Expert opinion: We advocate the acknowledgment of non-AATD emphysema as a clinical diagnosis and propose to end the era of bringing all pathologies that may lead to chronic airflow limitation together under the umbrella-term of COPD. Decelerating proteolysis and restoring damage should be main targets in emphysema. Vitamin A/K, hyaluronan, copper and roflumilast are promising candidates.

KEYWORDS:

• Emphysema
• centrilobular emphysema
• panlobular emphysema
• paraseptal emphysema
• non-alpha1 antitrypsin emphysema
• elastin degradation
• elastin repair
• proteases
• antiproteases
• COPD

Declaration of interest

R Janssen discloses an application for a patent on the repair of elastin fibers in emphysematous lungs and is one of the owners of Desmosine.com. F Franssen discloses speaker and consultancy fees by AstraZeneca, Chiesi, Novartis, GlaxoSmithKline, Boehringer Ingelheim, TEVA and Verona Pharma. The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewers disclosure

Peer reviewers on this manuscript have no relevant financial relationships or otherwise to disclose.

Additional information

Funding

This paper was not funded.