Differences in plasma and sputum biomarkers between COPD and COPD–asthma overlap

Abstract

The pathophysiological features of chronic obstructive pulmonary disease (COPD)-asthma overlap are poorly understood and there has been no study of plasma or sputum biomarkers in overlap patients. In order to clarify the similarity and differences between overlap and COPD or asthma, we have investigated four potential biomarkers of COPD: surfactant protein A (SP-A), soluble receptor for advanced glycation end-products (sRAGE), myeloperoxidase (MPO) and neutrophil gelatinase-associated lipocalin (NGAL). SP-A and sRAGE are pneumocyte-derived markers. MPO and NGAL are neutrophil-derived molecules, but NGAL can also be expressed by respiratory epithelial cells.Plasma levels of SP-A and sRAGE and induced sputum levels of MPO and NGAL were measured by enzyme immunoassay/ELISA in 134 subjects: nonsmokers (n526), smokers (n523), asthma (n532), COPD (n539) and COPD-asthma overlap patients (n514).In patients with COPD-asthma overlap, sputum MPO and plasma SP-A were significantly elevated whereas plasma sRAGE levels were reduced compared with asthma patients. Only sputum NGAL was significantly elevated in COPD-asthma overlap compared with COPD (p50.00016) and could be used to differentiate patients with overlap from those with COPD.Increased induced sputum levels of NGAL might be a characteristic feature of overlap, suggesting enhanced neutrophilic airway inflammation and/or airway epithelial injury in COPD-asthma overlap. @ERSpublications Increased sputum levels of neutrophil gelatinase-associated lipocalin in COPD-asthma overlap versus COPD/asthma patients

Asthma and chronic obstructive pulmonary disease overlap: asthmatic chronic obstructive pulmonary disease or chronic obstructive asthma?

“…Iwamoto showed increased sputum eosinophilia in patients with asthma and ACOS compared with healthy smokers and those with COPD [Iwamoto et al 2014]. However, patients with overlap syndrome and COPD had more sputum neutrophilia compared with those with asthma and healthy controls.…”

“…Lower NOx might indicate a decrease in oxidant activity compared with COPD alone. Iwamoto and colleagues investigated four potential biomarkers in COPD, asthma and ACOS [Iwamoto et al 2014]. Compared with asthma, sputum myeloperoxidases and plasma surfactant protein A were significantly elevated in ACOS and COPD and soluble receptor for advanced glycation end products was decreased in ACOS and COPD.…”

Asthmatics with high levels of serum surfactant protein D have more severe disease

“…The involvement of pulmonary surfactant in the pathophysiology of asthma has been suggested [1][2][3][4]. An interesting working hypothesis is that the surface tension of the peripheral airways is altered in asthma, because the inflammatory process affects the structure and function of surfactant, leading to excessive airway narrowing and features of air trapping.…”

Why is COPD phenotyping like sorting diamonds?

“…IWAMOTO et al [18] reported elevated sputum lipocalin, a neutrophil marker, as differentiating COPD and ACOS. In contrast, BAFADHEL et al [19] found that the mediator profile reflected the pattern of granulocytic inflammation, which is not specific for a diagnosis of asthma or COPD.…”