2015•Chin J Kidney Dis Invest(Electronic Edition)Requires access
Up-regulation of intermedin inhibited renal interstitial fibrosis in the kidney of rats with unilateral ureteral obstruction
Xi Qiao, N. Zhao, Lihua Wang, Ruijing Zhang
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Abstract
Objective
To investigate the effects of intermedin (IMD) overexpression on renal interstitial fibrosis in the obstructed kidney of rats with unilateral ureteral obstruction (UUO).
Methods
Male Wistar rats were randomly divided into sham-operated group, UUO group, IMD+ UUO group, and empty plasmid+ UUO group. For IMD+ UUO group or empty plasmid+ UUO group, pcDNA3.1-IMD plasmid or control empty vector was transfected into the left kidney via the renal artery by an ultrasound-microbubble-mediated system before the ureter was obstructed. The transfection rate was detected by real-time RT-PCR and immunohistochemistry. Groups of six animals were killed at 7 d and 14 d after operation. Kidneys were harvested for further analysis. Paraffin-embedded transverse kidney slices were stained with hematoxylin and eosin. For analyzing the degree of tubulointerstitial collagen deposition, sections were stained with Masson trichrome. mRNA expression levels of TGF-β1 and fibronectin (Fn1) were detected by real-time RT-PCR. Protein expression of TGF-β1 was detected by immunohistochemical staining. Protein expression of Fn1 was examined by Western blot analysis.
Results
The ultrasound-microbubble-mediated delivery system yielded high expression of IMD in kidney cells. IMD overexpression remarkably attenuated UUO-induced tubular injury, and blunted fibrotic response as shown by decreased interstitial collagen deposition (7 d, t=3.892, P=0.018 vs UUO group; 14 d, t=4.047, P=0.016 vs UUO group) and downregulation of fibronectin (mRNA 7 d, t=3.103, P=0.036 vs UUO group; 14 d, t=2.913, P=0.044 vs UUO group; Protein 7 d, t=2.955, P=0.042 vs UUO group; 14 d, t=2.991, P=0.040 vs UUO group), whereas TGF-β1 upregulation was not affected (mRNA 7 d, t=0.176, P=0.869 vs UUO group; 14 d, t=0.126, P=0.906 vs UUO; Protein 7 d, t=0.198, P=0.853 vs UUO; 14 d, t=0.196, P=0.854 vs UUO group).
Conclusion
Our results indicated that kidney-specific IMD gene delivery inhibited renal fibrosis induced by UUO. The inhibitory effect of IMD on renal fibrosis was not achieved by directly inhibiting TGF-β1 expression.
Key words:
Kidney; Interstitial fibrosis; Intermedin; Transforming growth factor-beta 1; Fibronectin