Vascular endothelial growth factor production and regulation in human peritoneal mesothelial cells.
BACKGROUND
Vascular endothelial growth factor (VEGF) was recently found in peritoneal effluents of peritoneal dialysis (PD) patients. It was suggested that human peritoneal mesothelial cells (HMC) contribute to the intraperitoneal production of VEGF, which may augment vascular permeability, vasodilation and neoangiogenesis in the peritoneal membrane. The present study was designed to assess the influence of proinflammatory cytokines, thrombin, d-glucose and glycated albumin in the regulation of VEGF synthesis in primary HMC cultures.


METHODS
VEGF antigen concentrations were measured in the cell supernatant by ELISA and VEGF mRNA expression was evaluated by real time RT-PCR.


RESULTS
Incubation of HMC with interleukin-1alpha (IL-1alpha; 10 to 100 U/mL), tumor necrosis factor-alpha (TNF-alpha; 500 to 1000 U/mL) or thrombin (1 to 10 U/mL) resulted in a time (24 to 72 hours) and concentration dependent increase in VEGF synthesis. In contrast, d-glucose (30 to 90 mmol/L), which is commonly used as an osmotic agent in peritoneal dialysis, was not able to up-regulate VEGF expression. High glucose levels even decreased VEGF production. However, exposure of HMC to Amadori-modified glycated albumin, which is generated in the peritoneal cavity in the presence of glucose-based dialysis solutions, resulted in a dose and time dependent increase in VEGF mRNA expression and antigen secretion.


CONCLUSIONS
These results demonstrate, to our knowledge for the first time, that glycated serum albumin, not glucose, increases VEGF production in HMC. HMC play an important role as a source of intraperitoneal VEGF synthesis, and VEGF expression also is up-regulated in the presence of proinflammatory cytokines and thrombin. Additionally, these results confirm clinical data that the continuous exposure of the peritoneal membrane to glucose-based dialysis solutions is an important stimulus for VEGF expression. However, it is not glucose per se, but nonenzymatic glycation products like glycated albumin that up-regulate VEGF expression.
Mandl-Weber
Sonja
S
Nephrologisches Zentrum, Medizinische Klinik und Poliklinik-Innenstadt, Klinikum der Universität München,Munich, Germany.
Cohen
Clemens D
CD
Haslinger
Bettina
B
Kretzler
Matthias
M
Sitter
Thomas
T
D000970:Antineoplastic Agents / Q000494:pharmacology; D002478:Cells, Cultured; D016228:Endothelial Growth Factors / Q000235:genetics* / Q000378:metabolism; D004848:Epithelium / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology; D005947:Glucose / Q000378:metabolism; D017127:Glycation End Products, Advanced / Q000378:metabolism; D006490:Hemostatics / Q000494:pharmacology; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology; D007676:Kidney Failure, Chronic / Q000378:metabolism / Q000628:therapy; D008222:Lymphokines / Q000235:genetics* / Q000378:metabolism; D010530:Peritoneal Dialysis; D010537:Peritoneum / Q000166:cytology* / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D012709:Serum Albumin / Q000494:pharmacology; D013917:Thrombin / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D000093423:Glycated Serum Albumin
D000970:Antineoplastic Agents; D016228:Endothelial Growth Factors; D017127:Glycation End Products, Advanced; D006490:Hemostatics; D007375:Interleukin-1; D008222:Lymphokines; D012333:RNA, Messenger; D012709:Serum Albumin; D014409:Tumor Necrosis Factor-alpha; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D013917:Thrombin; D005947:Glucose; D000093423:Glycated Serum Albumin