Complement 5b-9 complex-induced alterations in human RPE cell physiology.
BACKGROUND
Recent evidence shows that complements are closely related to the occurrence of choroidal neovascularization (CNV). We studied the effect of complement 5b-9 complex (C5b-9) on membrane permeability and molecular biological behavior in cultured human retinal pigment epithelium (RPE) cells and considered the role of C5b-9 in CNV.


METHODS
Human RPE cells were exposed to different concentrations of C5b-9 for 24 hours, then observed through light and electron microscopy. The dynamics of calcium ion change in cells exposed to sublysis C5b-9 were analyzed by confocal laser scanning microscope, and the amount of VEGF and TGF-beta2 mRNA was determined by reverse transcription polymerase chain reaction (RT-PCR) RESULTS: RPE cells were destroyed when exposed to 80 microg/ml and 40 microg/ml C5b-9. The structure of RPE cells was not obviously changed when exposed to 20 microg/ml or less C5b-9; however, pigment granules are released from the cell membrane when observed using electron microscopy. In most of the cells, calcium fluorescence intensity increased rapidly after the deposition of C5b-9, to a peak at 4 min, lasted for about 6 min, and then began to decrease. The expression of VEGF and TGF- beta2 mRNA in RPE cells with C5b-9 was increased at 4 h and decreased at 24 h, but they were higher than in the control group.


CONCLUSIONS
These observations suggest C5b-9 can induce a change in membrane permeability, an increase in cytoplasmic calcium ion concentration, and significant up-regulation of angiogenic factors in cultured RPE cells, which may be one of many potential mechanisms of CNV formation.
Li
Wenbo
W
TianJin Eye Hospital, Clinical College of Ophthalmology, TianJin Medical University, Tianjin, People's Republic of China.
Chen
Song
S
Ma
Minwang
M
Qian
Jiangyuan
J
Ma
Xiubin
X
D002118:Calcium / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects; D002478:Cells, Cultured; D020256:Choroidal Neovascularization / Q000209:etiology / Q000378:metabolism*; D050776:Complement C5b / Q000633:toxicity*; D003186:Complement C9 / Q000633:toxicity*; D017931:DNA Primers / Q000235:genetics; D006801:Humans; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D046912:Multiprotein Complexes / Q000378:metabolism / Q000633:toxicity*; D055213:Retinal Pigment Epithelium / Q000187:drug effects* / Q000648:ultrastructure; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053781:Transforming Growth Factor beta2 / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
D003186:Complement C9; D017931:DNA Primers; D046912:Multiprotein Complexes; D053781:Transforming Growth Factor beta2; D042461:Vascular Endothelial Growth Factor A; D050776:Complement C5b; D002118:Calcium