Circulating fibrocytes are an indicator of severity and exacerbation in chronic obstructive pulmonary disease

RationaleChronic obstructive pulmonary disease (COPD) is characterized by progressive airflow limitation that is associated with an enhanced inflammatory response in the airways and the lung. The remodeling process in COPD is greatly under the influence of growth factors. Lung fibroblasts in COPD demonstrated alterations in its functional capacity that is mediated by TGF-β1, therefore, could play a role in the pathogenesis of COPD. Fibrocytes are bone marrow derived cells that migrate to the injured sites and differentiate into fibroblast-like cells.ObjectivesTo test the hypothesis that assay of circulating fibrocytes may provide a biomarker for exacerbation and severity of COPD.MethodsFibrocytes were defined by flow cytometry and quantified in fifty male patients with stable COPD and during exacerbation. We investigated the clinical and prognostic value of fibrocytes by comparison with standard clinical parameters. Thirteen healthy subjects were selected as control.ResultsFibrocytes were significantly elevated in stable COPD patients (n=25), with a further increase during exacerbation (n=25; P<0.001 vs. control subjects n=13). Correlation analysis between fibrocyte counts and mMRC score, 6-MWT, BODE index, arterial oxygen saturation, pre- and post-bronchodilator FEV1/FVC, FEV1, FVC and FEF25–75 showed a direct relationship in COPD patients. There was a direct correlation between fibrocytes with the mMRC score and the serum levels of TGF-β1 only in COPD patients in exacerbations (n=25).ConclusionsFibrocytes are an indicator of COPD exacerbation and might be useful as a clinical (bio) marker for disease progression