title: Transforming growth factor-β1 short hairpin RNA inhibits renal allograft fibrosis.
abstract: BACKGROUND
  Transforming growth factor-β1 (TGF-β1) is known to be a key fibrogenic cytokine in a number of chronic fibrotic diseases, including chronic allograft nephropathy. We examined the effects of inhibition of TGF-β1 expression by RNA interference on renal allograft fibrosis, and explored the mechanisms responsible for these effects.
  
  
  METHODS
  A Sprague-Dawley-to-Wistar rat model of accelerated kidney transplant fibrosis was used. Sixty recipient adult Wistar rats were randomly divided into four groups: group J (sham-operated group), group T (plasmid-transfected group), group H (control plasmid group), and group Y (transplant only group). Rats in group T were transfected with 200 µg of TGF-β1 short hairpin RNA (shRNA). Reverse transcription-polymerase chain reaction and Western blotting were used to examine the expression of TGF-β1, Smad3/7, E-cadherin, and type I collagen. The distribution of type I collagen was measured by immunohistochemistry. The pathologic changes and extent of fibrosis were assessed by hematoxylin and eosin and Masson staining. E-cadherin and α-smooth muscle actin immunohistochemical staining were used to label tubular epithelial cells and fibroblasts, respectively.
  
  
  RESULTS
  Plasmid transfection significantly inhibited the expression of TGF-β1, as well as that of its target gene, type I collagen (P < 0.05 and P < 0.01, respectively). In addition, the degree of fibrosis was mild, and its development was delayed in plasmid-transfected rats. In contrast, TGF-β1-shRNA transfection maintained the expression of E-cadherin in tubular epithelial cells while it inhibited the transformation from epithelial cells to fibroblasts. Blood urea nitrogen and serum creatinine were lower in the plasmid group than in the control groups (P < 0.05 and P < 0.01, respectively).
  
  
  CONCLUSIONS
  This study suggests that transfection of a TGF-β1-shRNA plasmid could inhibit the fibrosis of renal allografts. The mechanism may be associated with the downregulation of Smad3 and upregulation of Smad7, resulting in suppressed epithelial-myofibroblast transdifferentiation and extracellular matrix synthesis.
authors.affiliation: Department of Urology, First Affiliated Hospital, Chongqing Medical University, Chongqing 400016, China.
authors.forename: Zhi-Kang
authors.initials: ZK
authors.lastname: Yin
authors.forename: Xiao-Hou
authors.initials: XH
authors.lastname: Wu
authors.forename: Yu-Guo
authors.initials: YG
authors.lastname: Xia
authors.forename: Chun-Li
authors.initials: CL
authors.lastname: Luo
mesh_terms: D000818:Animals; D015153:Blotting, Western; D054338:Cell Transdifferentiation / Q000235:genetics / Q000502:physiology; D004847:Epithelial Cells / Q000166:cytology; D005355:Fibrosis / Q000517:prevention & control*; D007668:Kidney / Q000378:metabolism / Q000473:pathology*; D016030:Kidney Transplantation / Q000379:methods*; D058628:Myofibroblasts / Q000166:cytology; D034741:RNA, Small Interfering / Q000235:genetics / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053773:Transforming Growth Factor beta1 / Q000235:genetics / Q000378:metabolism*; D014184:Transplantation, Homologous
chemical_list: D034741:RNA, Small Interfering; D053773:Transforming Growth Factor beta1