TGF-beta 1/Smads signaling stimulates renal interstitial fibrosis in experimental AAN.
Aristolochic acid nephropathy (AAN) is regarded as a kind of rapidly progressive renal fibrosis caused by the ingestion of herbal remedies containing aristolochic acids (AA). A mouse model of AAN was used to assess the patterns of renal injury and TGF-beta1/Smads signaling pathway during the evolution of tubulointerstitial damage and to relate them to the development of fibrosis. A total of 28 mice were randomly assigned to four groups. Three groups were given aristolochic acid I (AAI) at different doses consecutively by gavage for 30 days, while the control group received only phosphate-buffered saline (PBS). Immunohistochemistry and semi-quantitative reverse transcriptase (RT-PCR) detection of the increased expression of fibroblast marker vimentin and de novo expression of alpha-smooth muscle actin (alpha-SMA) with the loss of epithelial maker cytokeratin 18 (CK18) can be utilized to assess AAI-induced tubular necrosis and extensive cortical interstitial fibrosis in a dose-dependent manner. Transforming growth factor-beta1 (TGF-beta1) has been widely recognized as a key fibrogenic cytokine. In our study, TGF-beta1 in the group at dose of 12 mg/kg/ day AAI increased 109.9% compared to control. Smad2 mRNA level in the group at dose of 4.2 mg/kg/day AAI increased 106.4%, and declined 12% in the group at dose of 12 mg/kg/day AAI; Smad4 expression was down-regulated in experimental groups, which declined 13% in the group at dose of 4.2 mg/kg/day AAI. Smad7 mRNA level was down-regulated by AAI in dose-dependence. Collectively, the involvement in interstitial fibrosis progression of active TGF-beta is highly suggested, via the Smads intracellular signaling pathway. These results may be attributed to the dosage of drug and the treatment of renal interstitial fibrosis.
Li
Jing
J
Laboratory of Pharmacology of the Chinese Veterinary Medicine, Department of Animal Science and Technology, Beijing University of Agriculture, Beijing 102206, PR China.
Zhang
Zhongwen
Z
Wang
Dianren
D
Wang
Yanying
Y
Li
Ying
Y
Wu
Guojuan
G
D000199:Actins; D000818:Animals; D034341:Aristolochic Acids / Q000633:toxicity*; D015153:Blotting, Western; D002478:Cells, Cultured; D005355:Fibrosis / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology*; D007124:Immunoenzyme Techniques; D053538:Keratin-18 / Q000235:genetics / Q000378:metabolism; D007684:Kidney Tubules / Q000378:metabolism / Q000473:pathology; D051379:Mice; D009130:Muscle, Smooth / Q000737:chemistry; D009395:Nephritis, Interstitial / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D051785:Smad Proteins / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D053773:Transforming Growth Factor beta1 / Q000235:genetics / Q000378:metabolism*; D014746:Vimentin / Q000235:genetics / Q000378:metabolism
D000199:Actins; D034341:Aristolochic Acids; D053538:Keratin-18; D012333:RNA, Messenger; D051785:Smad Proteins; D053773:Transforming Growth Factor beta1; D014746:Vimentin