Levels of soluble vascular endothelial growth factor receptor 1 are elevated in the exudative pleural effusions

Purpose : Vascular endothelial growth factor (VEGF) plays a critical role in the production of malignant pleural effusions. In the present study, we examined the levels of soluble VEGF receptor-1 (sVEGFR-1) and angiopoietin-2 (Ang-2), as possible regulators of VEGF activity, in transudative and exudative pleural effusions.
Methods : Forty-two patients were included in this study : 4 with transudative pleural effusions due to heart failure (HF), 38 with exudative pleural effusions (lung cancer [LC], 22 ; other malignant diseases [MD], 10 ; tuberculosis [TB], 6) . The levels of VEGF, Ang-2, and sVEGFR-1 in the pleural effusions were measured by an enzyme-linked immunosorbent assay.
Results : The levels of VEGF, Ang-2, and sVEGFR-1 in exudative effusions were higher than those in transudative effusions. Interestingly, the levels of VEGF and Ang-2 in bloody effusions were significantly higher than those in non-bloody effusions (p < 0.05), but the level of sVEGFR-1 in bloody effusions was lower than that in non-bloody effusions. The levels of VEGF and Ang-2 were significantly higher in the malignant effusions, compared with effusion from HF and TB (p < 0.05). In addition, sVEGFR-1 was significantly higher in the effusion from LC, MD, and TB compared with effusion from HF (p < 0.05). In the malignant effusions, direct correlations were observed among VEGF, sVEGFR-1, and Ang-2.
Conclusions : The sVEGFR-1 levels were elevated in exudative pleural effusions, and were lower in bloody effusions than in non-bloody effusions, thus suggesting the regulatory role of sVEGFR-1 in the exudative pleural effusions.