COPD sputum eosinophils; relationship to blood eosinophils and the effect of inhaled PDE4 inhibition.

Patients with chronic obstructive pulmonary disease (COPD) who have higher eosinophil numbers in the airways and peripheral blood demonstrate a greater clinical response to inhaled corticosteroids (ICS) [1–3]. Furthermore, the effect of the oral phosphodiesterase-4 (PDE4) inhibitor roflumilast on exacerbations in severe COPD patients with chronic bronchitis, who are treated with ICS and long acting bronchodilators, also appears to be greater at higher blood eosinophil counts [4]. The mechanisms responsible for these differential drug effects remain to be defined, but may relate to increased type-2 inflammation in and/or decreased presence of colonising airway bacteria in COPD patients with more eosinophils [5, 6], leading to different responses to anti-inflammatory drugs. An association between blood and sputum eosinophils has been observed in some, but not all studies [7–12]. Accurate sputum eosinophil count measurement requires good quality samples to make cytospins where eosinophils can be clearly counted; variable quality of sputum samples, particularly in multicentre studies, will affect the ability to show a relationship with blood eosinophil counts. Footnotes This manuscript has recently been accepted for publication in the European Respiratory Journal . It is published here in its accepted form prior to copyediting and typesetting by our production team. After these production processes are complete and the authors have approved the resulting proofs, the article will move to the latest issue of the ERJ online. Please open or download the PDF to view this article. Conflict of interest: Dr. Singh reports personal fees from AstraZeneca, personal fees from Boehringer Ingelheim, personal fees from Chiesi, personal fees from Cipla, personal fees from Genentech, personal fees from GlaxoSmithKline, personal fees from Glenmark, personal fees from Menarini, personal fees from Mundipharma, personal fees from Novartis, personal fees from Peptinnovate, personal fees from Pfizer, personal fees from Pulmatrix, personal fees from Theravance, personal fees from Verona, outside the submitted work. Conflict of interest: Dr. Watz reports personal fees from Chiesi, during the conduct of the study; personal fees from Bayer, personal fees from GSK, personal fees from Boehringer Ingelheim, personal fees from Novartis, personal fees from AstraZeneca, personal fees from BerlinChemie, personal fees from Roche, outside the submitted work. Conflict of interest: KMB declares that no personal payments were received from any pharmaceutical entity in the past 5 years. KMB is a full time employee of insaf Respiratory Research Institute. The institution has received compensation for services on advisory boards or consulting for Ablynx, Almirall, AstraZeneca, Berlin Chemie, Boehringer, Chiesi, Cytos, Mundipharma, Novartis, Pohl Boskamp, Zentiva. The institution has received compensation for speaker activities in scientific meetings supported by Almirall, AstraZeneca, Berlin Chemie, Boehringer, Cytos, ERT, GSK, Novartis, Pfizer, Pohl Boskamp, Takeda. The institution has further received compensation for design and performance of clinical trials from Almirall, Altana/Nycomed, AstraZeneca, Boehringer, Cytos, GSK, Infinity, Medapharma, MSD, Mundipharma, Novartis, Parexel, Pearl Therapeutics, Pfizer, Revotar, Teva, Sterna, and Zentiva. Conflict of interest: Dr. Kornmann reports other from Chiesi, during the conduct of the study; personal fees from AstraZeneca, personal fees from Boehringer Ingelheim, personal fees from GlaxoSmithKline, personal fees from Sanofi, from Novartis, outside the submitted work. Conflict of interest: Dr. Leaker has nothing to disclose. Conflict of interest: Dr. Colgan has nothing to disclose. Conflict of interest: Dr. Lucci reports and I am an employee of Chiesi, the sponsor of the trial. Conflict of interest: Dr. Emirova reports and I am an employee of Chiesi, the sponsor of the trial. Conflict of interest: Dr. Nandeuil reports and I am an employee of Chiesi, the sponsor of the trial. Conflict of interest: Dr. Santoro reports and I am an employee of Chiesi, the sponsor of the trial. Conflict of interest: Dr. Balzano reports and I am an employee of Chiesi, the sponsor of the trial. Conflict of interest: Dr. Govoni reports and I am an employee of Chiesi, the sponsor of the trial.