title: Excretion of complement proteins and its activation marker C5b-9 in IgA nephropathy in relation to renal function.
abstract: BACKGROUND
  Glomerular damage in IgA nephropathy (IgAN) is mediated by complement activation via the alternative and lectin pathways. Therefore, we focused on molecules stabilizing and regulating the alternative pathway C3 convertase in urine which might be associated with IgAN pathogenesis.
  
  
  METHODS
  Membrane attack complex (MAC), properdin (P), factor H (fH) and Complement receptor type 1 (CR1) were quantified in urine samples from 71 patients with IgAN and 72 healthy controls. Glomerular deposition of C5, fH and P was assessed using an immunofluorescence technique and correlated with histological severity of IgAN and clinical parameters. Fibrotic changes and glomerular sclerosis were evaluated in renal biopsy specimens.
  
  
  RESULTS
  Immunofluorescence studies revealed glomerular depositions of C5, fH and P in patients with IgAN. Urinary MAC, fH and P levels in IgAN patients were significantly higher than those in healthy controls (p < 0.001), but CR1 was significantly lower than that in healthy controls (p < 0.001). Urinary MAC and fH levels were positively correlated with serum creatinine (sCr), urinary N-acetyl-β-D-glucosaminidase (u-NAG), urinary β2 microglobulin (u-Bm), urinary protein (p < 0.001), interstitial fibrosis (MAC: p < 0.01, fH: p < 0.05) and the percentage of global glomerular sclerosis (p < 0.01). Urinary P was positively correlated with u-NAG, u-Bm, and urinary protein (p < 0.01).
  
  
  CONCLUSIONS
  Complement activation occurs in the urinary space in IgAN and the measurement of levels of MAC and fH in the urine could be a useful indicator of renal injury in patients with IgAN.
authors: Division of Nephrology, Department of Internal Medicine, Juntendo University Faculty of Medicine, Tokyo, Japan.
authors: Kisara
authors: K
authors: Onda
authors: Isao
authors: I
authors: Ohsawa
authors: Hiroyuki
authors: H
authors: Ohi
authors: Mariko
authors: M
authors: Tamano
authors: Satoshi
authors: S
authors: Mano
authors: Michiro
authors: M
authors: Wakabayashi
authors: Akie
authors: A
authors: Toki
authors: Satoshi
authors: S
authors: Horikoshi
authors: Teizo
authors: T
authors: Fujita
authors: Yasuhiko
authors: Y
authors: Tomino
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015415:Biomarkers; D003167:Complement Activation; D017242:Complement Factor H / Q000652:urine; D015938:Complement Membrane Attack Complex / Q000652:urine*; D003170:Complement Pathway, Alternative; D003165:Complement System Proteins / Q000032:analysis; D005260:Female; D005355:Fibrosis; D005922:Glomerulonephritis, IGA / Q000276:immunology* / Q000503:physiopathology / Q000652:urine; D006801:Humans; D007668:Kidney / Q000503:physiopathology*; D007678:Kidney Glomerulus / Q000737:chemistry / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011414:Properdin / Q000652:urine; D011951:Receptors, Complement / Q000032:analysis; D055815:Young Adult
chemical_list: D015415:Biomarkers; D015938:Complement Membrane Attack Complex; D011951:Receptors, Complement; D011414:Properdin; D017242:Complement Factor H; D003165:Complement System Proteins