ABSTRACT
Objective To explore the influence of albumin-activated renal tubular epithelial cells (RTECs)on peritubular capillaries in co-culture system and its potential mechanism. Methods Endocytosis of TRITC labeled bovine scrum albumin (TRITC-BSA) by HKC was detected by laser scanning confocal fluorescence microscope. HKC or HKC transfected with cubilin (endocytic receptor of albumin) siRNA or pre-treated with rotenone was incubated with albumin(20 g/L) for 24 h respectively. Fluorescence probe technique and spectrometry were applied for determination of intracellular superoxide anion O2-and H2O2 in supematant. Then, the albumin-aetivated-HKC, pretreated-HKC with cubilin siRNA or rotenone, was cultured with HUVEC for 24 h in co-culture system respectively. HUVEC proliferation was determined by MTT and cellular apoptosis was analyzed by flow cytometry. Tabular morphogenesis of endothelial cells was examinedby microscopy. Results TRITC-BSA uptake was obviously lower in HKC transfected with cubilin siRNA. Intracellular generation of O2-and H2O2 in culture supernatant was increased in dose-and time-dependent manner after stimulating with albumin. The levels of O2-and H2O2 were suppressed by cubilin siRNA and rotenone. In co-culture system, albumin-activated-HKC induced endothelial cells apoptosis and inhibited their capillary tubular morphogenesis. Pretreatment of HKC with cubilin siRNA or rotenone could suppress endothelial cells apoptosis and promote capillary tubular morphogenesis. Conclusions There may be a crosstalk between RTECs and peritubular microvascular endothelial cells in renal proteinurie diseases. The generation of ROS by albumin-activated RTECs may play an important role in this process.