Cell Biology – Immunology – Pathology
Kidney International (2003) 64, 914–922; doi:10.1046/j.1523-1755.2003.00188.x
Rat glomerular epithelial cells produce and bear factor H on their surface that is up-regulated under complement attack
Guohui Ren, Mona Doshi, Bradley K Hack, Jessy J Alexander and Richard J Quigg
Section of Nephrology, The University of Chicago, Chicago, Illinois
Correspondence: Richard J. Quigg, M.D., Section of Nephrology, The University of Chicago, 5841 S. Maryland Ave., MC5100, Chicago, Illinois 60637. E-mail: rquigg@medicine.bsd.uchicago.edu
Received 9 October 2002; Revised 30 March 2003; Accepted 12 May 2003.
Abstract
Rat glomerular epithelial cells produce and bear factor H on their surface that is up-regulated under complement attack.
Background
Factor H is a potent complement inhibitory molecule that is primarily produced by the liver and appears in plasma as a soluble protein. Yet there is evidence that other cells, including those in the kidney, can produce factor H, and that it can be cell-associated as well as present as a plasma protein. Here we studied factor H in rat glomerular epithelial cells (GEC).
Methods
A polyclonal antibody to factor H was used to identify factor H protein. A polymerase chain reaction (PCR)-based strategy was utilized to clone the full-length cDNA of GEC factor H. The relative quantity of factor H mRNA was measured by quantitative reverse transcription (RT)-PCR in cultured GEC exposed to complement activation and in the passive Heymann nephritis (PHN) model of membranous nephropathy.
Results
By immunofluorescence microscopy, factor H protein was present on the plasma membranes of cultured GEC. Based upon Western blot studies, this appeared to be the full-length 150 kD factor H protein. Factor H cDNA cloned from GEC was identical to the newly deposited sequence for rat liver factor H cDNA. In cultured GEC in which complement was activated, factor H mRNA increased over time. Similarly, in the PHN model in which complement was activated on GEC in vivo, factor H mRNA and protein also increased over time.
Conclusion
Cultured GEC and glomeruli express factor H mRNA and protein. As modeled both in vitro and in vivo in the rat, factor H is up-regulated in membranous nephropathy. This is likely to be a direct response of GEC to complement attack and may represent a protective response of this cell.
Keywords:
factor H, glomerular epithelial cells, complement, rat, Heymann nephritis, rat glomerular epithelial cell factor H
