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.
Immunology Research Centre, St. Vincent's Hospital, Melbourne, Australia. mudges@svhm.org.au
S J
SJ
Mudge
J L
JL
McRae
R B
RB
Auwardt
B F
BF
Murphy
C G
CG
Chen
D A
DA
Power
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