Angiogenic molecule Tie-2 and VEGF in the pathogenesis of pleural effusions.

Background: The role of angiogenesis in the pathogenesis of pleural effusion (PE) has not been determined. The expression of angiogenic factors may represent useful markers for the diagnosis and prediction of disease outcome. To measure the pleural fluid (PF) and serum levels of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and Tie receptor tyrosine kinase (Tie-2) in order to investigate their role in the pathogenesis of PEs.
Methods: Sixty-seven, 17 with transudative PEs due to heart failure and 50 with exudative PEs (malignant, 22; inflammatory, 15; undiagnosed, 13) were included in the study. PF and serum levels of the growth factors (VEGF, bFGF and Tie-2) were measured using enzyme-linked immunosorbent assays.
Results: PF and serum VEGF levels but not bFGF and Tie-2 levels were higher (p<0.005) in exudates than in transudates. PF VEGF levels were significantly higher in malignant than inflammatory and undiagnosed PEs (p=0.03). In addition, PF Tie-2 levels were not found different in malignant or in parapneumonic PEs.
Conclusion: Our results showed that VEGF is one of the main mediators in exudative PEs, but this effect is not mediated through the angiogenetic pathway Ang-1/Tie-2. However, the role of angiogenesis and its pathways in the pathogenesis of exudative PEs needs further exploration.