Evaluation of mediators of fibrosis and angiogenesis in the blood serum of premature infants with bronchopulmonary dysplasia

Abstract

In premature birth and postpartum damage to the developing lung, the processes of the formation of pulmonary vessels and alveoli are disrupted, leading to bronchopulmonary dysplasia (BPD). BPD is a multifactorial disease and the pathogenesis of lung tissue damage is still not fully understood. Studies of angiogenesis biomarkers can be informative for assessing the development of BPD. In this study we examined the blood serum of 65 premature infants aged 6 to 180 days of life; gestational age at birth was 23-33 weeks, body weight 480-1840 g, APGAR score 5-6. All children in the early neonatal period had respiratory distress syndrome, then 46 children formed and 19 did not form bronchopulmonary dysplasia. The concentration of the factors of angiogenesis and fibrosis was determined in blood serum by ELISA. There were no differences in the levels of angiopoietins 1 and 2, vascular endothelial growth factor VEGF-D, transforming growth factor beta TGF-β, thrombospondin-1. We observed a tendency to increasing the level of VEGF-A, which is a key regulator of angiogenesis and lung maturation; we regard this tendency as a favorable sign of lung formation. We found tendencies to increase of the adhesion molecule of endothelial platelet cells PECAM-1, interleukin 8 and connective tissue growth factor CTGF. CTGF expression is enhanced by artificial lung ventilation and exposure to high oxygen concentrations. We consider an increase of CTGF in BPD to be an unfavorable change, since the binding of CTGF to VEGF inhibits VEGF-induced angiogenesis. In children with BPD, we found a decrease in the level of platelet derived growth factor PDGF-BB, the median concentration was 3180 pg/mL in BPD versus 4782 pg/mL without BPD (p = 0.024). PDGF is an important factor in tissue regeneration and plays an important role in the formation of blood vessels. We assume the decreasing of PDGF concentration in BPD can lead to a violation of the alveolarization necessary for the formation of the structure of healthy lungs. Studies of angiogenesis factors will help to better understand the pathogenesis of lung damage in BPD.