Eng Eudora, Holgren Cory, Hubchak Susan, Naaz Parveen, Schnaper H William
Division of Nephrology and Hypertension, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA.
Kidney Int. 2005 Aug;68(2):695-703. doi: 10.1111/j.1523-1755.2005.00448.x.
Platelet-derived growth factor (PDGF)-B regulates mesangial cell and vessel development during embryogenesis, and contributes to the pathogenesis of adult renal and vascular diseases. Endothelial cell PDGF-B exerts paracrine effects on mesangial cells, but its regulation is not well defined. We examined the impact of hypoxia on PDGF-B-mediated interactions between glomerular endothelial and mesangial cells, a condition of potential relevance in developing, and diseased adult, kidneys.
Glomerular endothelial or mesangial cells were subjected to hypoxia and responses compared to normoxic cells. Endothelial PDGF-B was studied by Northern and Western analysis. Mesangial proliferative responses to PDGF-B were assessed by (3)H-thymidine incorporation, and migration by a modified Boyden chamber assay. Hypoxia-induced changes in receptor specific binding capacity were studied by saturation binding assays.
Hypoxia stimulated increases in endothelial PDGF-B mRNA and protein. In normoxic mesangial cells, PDGF-B stimulated dose-dependent proliferation, but the proliferative response of hypoxic cells was two to three times greater. Exogenous PDGF-B also caused prompter migration in hypoxic mesangial cells. Mesangial cells were treated with endothelial cell-conditioned medium. More cells migrated when hypoxic cells were stimulated with hypoxic conditioned medium, than when normoxic cells were stimulated with normoxic conditioned medium. Preincubating conditioned medium with PDGF-B neutralizing antibody greatly decreased the chemoattractant activity. Binding studies demonstrated increased specific binding capacity in hypoxic cells.
Hypoxia enhances PDGF-B paracrine interactions between glomerular endothelial and mesangial cells. These hypoxia-regulated interactions may be important during glomerulogenesis in fetal life and during the pathogenesis of adult glomerular disease.
血小板衍生生长因子（PDGF）-B在胚胎发育过程中调节系膜细胞和血管发育，并参与成人肾脏和血管疾病的发病机制。内皮细胞源性PDGF-B对系膜细胞发挥旁分泌作用，但其调节机制尚不清楚。我们研究了缺氧对肾小球内皮细胞和系膜细胞之间由PDGF-B介导的相互作用的影响，这一情况在发育中的肾脏和患病的成人肾脏中可能具有潜在相关性。
将肾小球内皮细胞或系膜细胞置于缺氧环境中，并与常氧细胞比较其反应。通过Northern和Western分析研究内皮细胞源性PDGF-B。通过³H-胸腺嘧啶核苷掺入法评估系膜细胞对PDGF-B的增殖反应，通过改良的Boyden小室试验评估其迁移情况。通过饱和结合试验研究缺氧诱导的受体特异性结合能力变化。
缺氧刺激内皮细胞PDGF-B mRNA和蛋白增加。在常氧系膜细胞中，PDGF-B刺激剂量依赖性增殖，但缺氧细胞的增殖反应大两到三倍。外源性PDGF-B也使缺氧系膜细胞迁移更快。用内皮细胞条件培养基处理系膜细胞。当用缺氧条件培养基刺激缺氧细胞时，比用常氧条件培养基刺激常氧细胞时，有更多细胞迁移。用PDGF-B中和抗体预孵育条件培养基可大大降低趋化活性。结合研究表明缺氧细胞中特异性结合能力增加。
缺氧增强肾小球内皮细胞和系膜细胞之间的PDGF-B旁分泌相互作用。这些受缺氧调节的相互作用在胎儿期肾小球发生过程以及成人肾小球疾病发病机制中可能很重要。
