Endothelial progenitor cells increased during COPD exacerbations
MedWire News: Levels of endothelial progenitor cells (EPCs) are increased in patients who are experiencing an exacerbation of chronic obstructive pulmonary disease (COPD), researchers have found.
“Cardiovascular (CV) morbidity and mortality is increased in patients with COPD, particularly during exacerbations of the disease,” write Ernest Sala (Hospital Universitari Son Dureta, Palma de Mallorca, Spain) and team in the journal Lung.
They explain: “Reduced levels of circulating EPCs are associated with increased risk of death in patients with stable coronary artery disease (CAD). Likewise, during acute events of CAD, the number of circulating EPCs increases under the influence of vascular endothelial growth factor (VEGF) and systemic inflammation.”
However, they add that, although previous studies have identified a decrease in circulating EPCs in patients with stable COPD compared with healthy controls, “the response of EPCs to exacerbations of COPD has not been studied.”
To address this, the researchers studied levels of circulating EPCs – calculated as the percentage of CD34+KDR+ cells determined by flow cytometry – in 35 patients hospitalized with an exacerbation of COPD who were aged an average of 65 years and had a mean FEV1 of 46% of predicted.
These were compared with EPC levels in 44 patients with stable COPD, aged an average of 68 years with a mean FEV1 of 49% of predicted, 10 smokers aged an average of 60 years with normal lung function, and 10 healthy individuals aged an average of 62 years who had never smoked.
Serum levels of VEGF were also measured to investigate potential mechanisms of EPC regulation.
Analysis revealed that EPC levels were higher in patients with a COPD exacerbation (1.46%) than in those with stable disease (0.68%), smokers with normal lung function (0.65%), and healthy participants who had never smoked (1.05%).
Furthermore, the percentage of circulating EPCs was positively related to VEGF levels during COPD exacerbations.
The researchers also note that, in a subset of 12 COPD patients who were assessed when stable and during an exacerbation, EPC levels increased during the exacerbation.
“Our results show that the level of EPCs increases in most patients with an exacerbation of COPD, likely in relation to VEGF upregulation,” Sala and team conclude.
They add: “The prognostic value of circulating EPCs in COPD has not been assessed yet [but] we propose here that those unable to raise the concentration of EPCs during exacerbations of COPD (nonresponders) may have a poor prognosis. This is a testable hypothesis in future longitudinal studies.”
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By Mark Cowen