Complement (C5b-9) induces DNA synthesis in rat mesangial cells in vitro.
BACKGROUND
The membrane attack complex C5b-9 causes injury in many forms of immune-mediated glomerular diseases characterized by mesangial cell (MC) proliferation and inhibiting C5b-9 decreases MC proliferation in vivo. Membrane insertion of sublytic quantities of the membrane attack complex of complement (C5b-9) is a potent stimulus for cell activation and the production of a variety of cytokines, growth factors, oxidants, matrix components, and other nephritogenic molecules. In vivo, a common response of MC to C5b-9--mediated injury is cell proliferation, an event closely linked to matrix expansion and sclerosis. In this study, we tested the hypothesis that C5b-9 might also serve as a mitogenic stimulus for MCs.


METHODS
Rat MCs in vitro were exposed anti-Thy1 antibody and 2% normal PVG serum (a complement source) to induce sublytic C5b-9 attack and DNA synthesis and cell number were measured. Control MCs were exposed to antibody and C6-deficient PVG serum.


RESULTS
Sublytic C5b-9--induced injury to MCs is sufficient to induce DNA synthesis. Furthermore, C5b-9 augmented DNA synthesis induced by platelet-derived growth factor (PDGF) and 5% fetal calf serum. C5b-9--induced DNA synthesis was reduced by inhibiting reactive oxygen species (ROS) with superoxide dismutase and catalase, but not by neutralizing the mitogenic growth factors PDGF and basic fibroblast growth factor (bFGF).


CONCLUSIONS
This study demonstrates that C5b-9 may directly increase DNA synthesis in cultured MCs, which are mediated in part by the release of ROS, and that C5b-9 also augments DNA synthesis induced in MCs by other known mitogens.
Division of Nephrology, Department of Medicine, University of Washington, Seattle, Washington 98195, USA.
W G
WG
Couser
J W
JW
Pippin
S J
SJ
Shankland
D000818:Animals; D002374:Catalase / Q000494:pharmacology; D002452:Cell Count; D002478:Cells, Cultured; D015938:Complement Membrane Attack Complex / Q000494:pharmacology*; D004247:DNA / Q000096:biosynthesis*; D016222:Fibroblast Growth Factor 2 / Q000502:physiology; D005920:Glomerular Mesangium / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D009994:Osmolar Concentration; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology / Q000502:physiology; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000494:pharmacology
D015938:Complement Membrane Attack Complex; D010982:Platelet-Derived Growth Factor; D017382:Reactive Oxygen Species; D016222:Fibroblast Growth Factor 2; D004247:DNA; D002374:Catalase; D013482:Superoxide Dismutase