The detrimental qualitative and quantitative alterations of circulating endothelial progenitor cells in patients with bronchiectasis

Background: Bronchiectasis is an independent risk factor for cardiovascular disease (CVD) and cardiac dysfunction. Endothelial progenitor cells (EPCs) play a crucial role in maintaining endothelial function, and is inversely correlated with cardiovascular risk factors or cardiac dysfunction. However, the relationship between EPCs and bronchiectasis is unknown. Methods: Twenty-nine patients with stable bronchiectasis and 15 healthy controls were recruited. Fasting venous blood were collected for determining circulating EPC number and activity as well as systemic inflammatory cytokines. Results: The number and migratory or proliferative activity of circulating EPCs in bronchiectasis patients were significantly reduced (p < 0.001). In high E-FACED group, the number of circulating EPCs evaluated by cell culture assay and EPC proliferation were decreased (p < 0.05). Similarly, the number and function of circulating EPCs were both reduced in low forced expiratory volume in 1 s (FEV1) or high mMRC group (p < 0.05). There was a significant correlation between circulating EPCs and bronchiectasis disease severity, according to the EFACED score (p < 0.05), particularly to FEV1 (p < 0.05) and mMRC dyspnea score (p < 0.05). The count and activity of EPCs inversely correlated with hsCRP levels and IL-6 levels (p < 0.01). Conclusions: Deficiencies in the number and function of circulating EPCs are present in patients with bronchiectasis. The changes are related to disease severity and may be partly attributed to systemic inflammation. The current findings may provide novel surrogate evaluation biomarkers and potential therapeutic target for bronchiectasis.