title: Complement mediates nephrin redistribution and actin dissociation in experimental membranous nephropathy.
abstract: BACKGROUND
  The onset of proteinuria in passive Heymann nephritis, (PHN), a rat model of human membranous nephropathy (MN), is complement-dependent and is associated with altered podocyte slit diaphragm integrity and dissociation of nephrin from the actin cytoskeleton. These studies examined if complement is responsible for these podocyte changes.
  
  
  METHODS
  PHN was induced with sheep anti-Fx1A. Controls were injected with normal sheep globulin. A third group was injected with anti-Fx1A and depleted of complement with cobra venom factor. Four days later, proteinuria was measured, slit diaphragm integrity was examined by electron microscopy, nephrin distribution was studied by immunofluorescence, and the glomerular content of nephrin and its association with actin were assessed by sequential extraction of isolated glomeruli and Western blotting.
  
  
  RESULTS
  Four days after immunization, seven out of eight PHN rats were proteinuric, whereas none of the complement depleted group had proteinuria despite similar levels of antibody deposition. Complement depletion preserved slit diaphragm morphology. Immunofluorescence microscopy with an antibody to the extracellular domain of nephrin showed a normal staining pattern in the rats depleted of complement and a shift to a more dispersed and clustered pattern in the PHN group. Western blot analysis of the glomerular extracts showed a significant reduction in the total amount of nephrin and in the fraction of actin-associated nephrin in the PHN group, whereas the amounts in the complement-depleted rats were similar to normal controls.
  
  
  CONCLUSIONS
  The onset of proteinuria in the PHN model of MN is coincident with complement-dependent alterations in the association of nephrin with the actin cytoskeleton and loss of podocyte slit diaphragm integrity.
authors: Renal Section and Department of Medicine, Evans Biomedical Research Center, Boston University Medical Center, Boston, Massachusetts, USA.
authors: Anita M
authors: AM
authors: Saran
authors: Huaping
authors: H
authors: Yuan
authors: Emiko
authors: E
authors: Takeuchi
authors: Margaret
authors: M
authors: McLaughlin
authors: David J
authors: DJ
authors: Salant
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D003165:Complement System Proteins / Q000378:metabolism*; D004195:Disease Models, Animal; D005455:Fluorescent Antibody Technique; D005921:Glomerulonephritis / Q000150:complications / Q000378:metabolism / Q000473:pathology; D015433:Glomerulonephritis, Membranous / Q000378:metabolism*; D007668:Kidney / Q000473:pathology; D008565:Membrane Proteins; D008854:Microscopy, Electron; D011506:Proteins / Q000378:metabolism*; D011507:Proteinuria / Q000209:etiology; D051381:Rats; D014018:Tissue Distribution
chemical_list: D000199:Actins; D008565:Membrane Proteins; D011506:Proteins; C113267:nephrin; D003165:Complement System Proteins