title: Urinary miR-21, miR-29, and miR-93: novel biomarkers of fibrosis.
abstract: BACKGROUND
  MicroRNAs (miRNAs) play important roles in the progression of renal fibrosis. We studied the urinary levels of miR-21, miR-29 family and miR-93, which are downstream mediators of the transforming growth factor-β(1) (TGF-β(1)), in patients with immunoglobulin A (IgA) nephropathy.
  
  
  METHODS
  We studied the urinary miRNA levels of 43 IgA nephropathy patients and 13 healthy controls.
  
  
  RESULTS
  The IgA nephropathy group had significantly lower urinary miR-29b and miR-29c, but higher miR-93 levels than controls. Proteinuria significantly correlated with urinary levels of miR-29b (r = -0.388, p = 0.003) and miR-29c (r = -0.409, p = 0.002). Glomerular filtration rate significantly correlated with urinary levels of miR-21 (r = 0.338, p = 0.028), miR-29b (r = 0.333, p = 0.031) and miR-29c (r = 0.304, p = 0.050). Urinary miR-93 level significantly correlated with glomerular scarring (r = -0.392, p = 0.010). Urinary miRNA level of SMAD3, but not TGF-β(1), correlated with urinary miR-21 (r = 0.624, p < 0.001), miR-29b (r = 0.566, p < 0.001), miR-29c (r = 0.619, p < 0.001) and miR-93 (r = 0.332, p = 0.032).
  
  
  CONCLUSIONS
  Urinary miR-29b and miR-29c levels correlated with proteinuria and renal function, while urinary miR-93 level correlated with glomerular scarring. More importantly, urinary levels of these miRNA targets significantly correlated with urinary SMAD3 level. Our results suggest that these miRNA targets are regulated by the TGF-β(1)/SMAD3 pathway and they may play important roles in the development of progressive renal fibrosis in IgA nephropathy.
authors.affiliation: Department of Medicine and Therapeutics, Prince of Wales Hospital, The Chinese University of Hong Kong, SAR, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Wang
authors.forename: Bonnie Ching-Ha
authors.initials: BC
authors.lastname: Kwan
authors.forename: Fernand Mac-Moune
authors.initials: FM
authors.lastname: Lai
authors.forename: Kai-Ming
authors.initials: KM
authors.lastname: Chow
authors.forename: Philip Kam-Tao
authors.initials: PK
authors.lastname: Li
authors.forename: Cheuk-Chun
authors.initials: CC
authors.lastname: Szeto
mesh_terms: D015415:Biomarkers / Q000652:urine; D005260:Female; D005355:Fibrosis / Q000652:urine; D006801:Humans; D007668:Kidney / Q000473:pathology*; D007674:Kidney Diseases / Q000652:urine*; D008297:Male; D035683:MicroRNAs / Q000652:urine*; D008875:Middle Aged
chemical_list: D015415:Biomarkers; C524940:MIRN21 microRNA, human; C532045:MIRN29a microRNA, human; C543350:MIRN93 microRNA, human; D035683:MicroRNAs