Sublytic complement injury does not activate NF-kappa B, or induce mitogenesis in rat mesangial cells.
Sublytic complement injury to glomerular mesangial cells, mediated by the terminal membrane attack complex of complement (C5b-9), is a potential initiating mechanism in IgA nephropathy. Sublytic complement injury has been reported to result in the production of a variety of pro-inflammatory molecules and growth factors, including many regulated by the transcription factor NF-kappa B. To determine the importance of complement injury in the pro-inflammatory signalling which occurs in IgA nephropathy, we investigated NF-kappa B activation following sublytic complement injury to cultured rat glomerular mesangial cells (RMCs). A sublytic dose of rabbit anti-Thy 1.1 (THY) serum and normal human serum was selected based upon flow cytometry, chromium-release assay, and induction of superoxide production. No significant C5b-9-induced NF-kappa B activation was detected by electrophoretic mobility shift assays, luciferase activity of RMCs transfected with a NF-kappa B-driven luciferase reporter construct, nor by Northern blots for the NF-kappa B-responsive mRNA species monocyte chemoattractant protein-1 or I kappa B alpha. Furthermore, measurements of (3)H incorporation following sublytic complement injury showed inhibition of mesangial cell mitogenesis in comparison to the heat-inactivated serum treatment and to THY alone. The results of this study suggest that sublytic complement injury to RMC does not directly activate NF-kappa B nor induce mesangial cell proliferation in mesangial cells. Other mechanisms such as IgA immune complex formation must be required to produce these events in IgA nephropathy.
Mudge
S J
SJ
Immunology Research Centre, St. Vincent's Hospital, Melbourne, Australia. mudges@svhm.org.au
McRae
J L
JL
Auwardt
R B
RB
Murphy
B F
BF
Chen
C G
CG
Power
D A
DA
D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D002857:Chromium / Q000378:metabolism; D003186:Complement C9 / Q000276:immunology; D015938:Complement Membrane Attack Complex / Q000276:immunology*; D004586:Electrophoresis; D005434:Flow Cytometry; D005920:Glomerular Mesangium / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D005922:Glomerulonephritis, IGA / Q000276:immunology; D008938:Mitosis; D016328:NF-kappa B / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013481:Superoxides / Q000378:metabolism; D018800:Thy-1 Antigens / Q000276:immunology
D000906:Antibodies; D003186:Complement C9; D015938:Complement Membrane Attack Complex; D016328:NF-kappa B; D018800:Thy-1 Antigens; D002857:Chromium; D013481:Superoxides