Blood eosinophils in COPD: friend or foe?

ABSTRACT

Introduction

The pathogenesis of chronic obstructive pulmonary disease (COPD) is highly complex and the underlying cellular and molecular mechanisms remain poorly understood.

Areas Covered

COPD has been traditionally associated with neutrophilic inflammation of the bronchi, but in the last decade, studies have demonstrated that eosinophils may also migrate into the lower airways of patients with COPD and their increased numbers can be noticed during exacerbations as well as stable disease. In this review, we present clinical characteristics of eosinophilic COPD, as well as the role of eosinophils as a biomarker-guided therapy in COPD. A systematic research using the database of Pubmed up to February 2021 was performed. The terms we searched were eosinophilic inflammation, COPD, COPD phenotypes, COPD exacerbations, corticosteroids in COPD, and monoclonal antibodies in COPD.

Expert Opinion

Blood eosinophil levels show strong potential as a prognostic and theragnostic biomarker in the clinical management of COPD being at the moment the most reliable biomarker. The lack of a certain cutoff value of blood eosinophils as guidance for treatment with ICS and biologic therapies and the uncertainty regarding the stability of eosinophilia and eosinophilic phenotype through the course of COPD remain as unmet dilemmas and problems.

KEYWORDS:

• Eosinophilic inflammation
• COPD
• COPD exacerbations
• corticosteroids
• monoclonal antibodies

Article Highlights

• High blood eosinophils in both stable COPD and during COPD exacerbations predict dreadful events in the disease course including future exacerbation, re-admission to the hospital, or death.

• In stable COPD, blood eosinophils may identify patients who will benefit the most from the addition of ICS in the therapeutic scheme.

• Feature studies should be designed to better evaluate several characteristics of the so-called eosinophilic COPD phenotype including eosinophil cut-off values, as well as novel therapies.

Declaration of Interests

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.

Reviewer disclosures

Peer reviewers of this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was not funded.