RÉSUMÉ
BACKGROUND:Pulmonary pericytes are located at the concavity where pulmonary vessels are interconnected,which is closely related to the formation and stability of pulmonary vascularization.However,there are few studies on how pulmonary pericytes affect the activity of pulmonary vascular endothelial cells in the pathogenesis of broncho-pulmonary dysplasia. OBJECTIVE:To analyze the relationship between the quantity of subgroups of pulmonary pericytes and endothelial cells in different stages of broncho-pulmonary dysplasia and to explore the effects of PDGFR-β+NG2+α-SMA+ pericytes on the early tube-forming activity of pulmonary vascular endothelial cells. METHODS:(1)Animal experiment:Twelve newborn C57BL/6 mice were randomly divided into normoxia and hyperoxia groups within 24 hours of birth,with six mice in each group.Mice in the hyperoxia group were exposed to an 85%O2 environment to build the mouse models of broncho-pulmonary dysplasia,while those in the normoxia group were fed in the same room air.The lung tissues of the mice in the two groups were taken at 7 and 14 days after birth.The pathological changes of the lung tissues were observed by hematoxylin-eosin staining.Three subgroups of pulmonary pericytes were measured by flow cytometry:PDGFR-β+NG2+α-SMA-,PDGFR-β+NG2+α-SMA+,and PDGFR-β+NG2-α-SMA+ cells.(2)Cellular experiment:Passage 3 PDGFR-β+NG2+α-SMA+ pericytes were co-cultured with mouse pulmonary vascular endothelial cells(experimental group)at a ratio of 1:4.Mouse pulmonary vascular endothelial cells cultured alone were used as controls.The tube-forming difference between two groups was analyzed after 15 hours of co-culture. RESULT AND CONCLUSION:(1)Animal experiment:Hematoxylin-eosin staining revealed that on day 7,the lung tissue of mice in the normoxia group had regular structure,obvious alveolar structure,and uniform size,while the number of alveoli in the lung tissue of mice in the hyperoxia group was less and the morphology of alveoli was irregular.On day 14,the alveoli of mice in the normoxia group gradually developed and matured,the alveolar structure gradually became regular and uniform in size,and the alveolar density gradually increased.The lung tissue structure of mice in the hyperoxia group was relatively disordered and the alveolar formation was delayed with the size gradually increasing and the alveolar structure being simplified.Flow cytometry results indicated that the number of PDGFR-β+NG2-α-SMA+ and PDGFR-β+NG2+α-SMA+ pericytes was increased in the hypoxia group compared with the normoxia group(P＜0.01),while the number of PDGFR-β+NG2+α-SMA-pericytes and pulmonary vascular endothelial cells was decreased(P＜0.01,P＜0.04).(2)Cellular experiment:In the control group,the pulmonary vascular endothelial cells arranged in cords and extended around,and lumen-like structures formed in some areas.In the experimental group,PDGFR-β+NG2+α-SMA+ pericytes and their pseudopodia were not observed,the irregular grid structure of pulmonary vascular endothelial cells was significantly less than that of the control group,and the endothelial cells mainly clustered in clumps.To conclude,α-SMA+ pericyte subgroups are predominant in mice with broncho-pulmonary dysplasia.PDGFR-β+NG2+α-SMA+ pericytes can directly inhibit the tube-forming activity of pulmonary vascular endothelial cells,which may be involved in the process of abnormal vascularization in broncho-pulmonary dysplasia.
RÉSUMÉ
PURPOSE: Inflammation plays a major role in the pathogenesis of RDS and BPD in the immature lung. We investigated the possible role of IL-10 and IL-12 in the cord blood of preterm newborns with RDS or BPD. METHODS: Forty preterm newborns whose mothers received antenatal care at Ewha Womans University Mokdong Hospital between January 2003 to June 2005, and agreed to testing their cord blood samples were enrolled. The gestational ages were below 34 weeks. Cord blood level of IL-10 and IL-12 were determined by ELISA. We separated the patients into 2 groups (RDS group and non- RDS group, BPD group and non-BPD group) and compared the cytokine levels and clinical records of the groups. RESULTS: Cord blood IL-10 level showed a significant inverse correlation with gestational age and birth weight (P=0.001, P=0.005). Preterm infants with RDS showed higher IL-10 level (1.0 vs 0.1 pg/mL; P=0.001) in the cord blood than those without RDS. The differences remained statistically significant after correction for the effect of gestational age between both preterm groups. Despite similar cord blood IL-10 levels, preterm infants with BPD showed no significant difference with those without BPD. CONCLUSION: Cord blood IL-10 levels are increased in preterm infants which may be due to the immuno-suppression occurring during pregnancy and to fetal immaturity because these levels are inversely correlated with the gestational age. So, Cord blood IL-10 level can be used as the predictor of RDS.