[Urine protein from patients with lupus nephritis stimulates transdifferentiation and high expression of collagen in renal tubular cells].
OBJECTIVE
To investigate the effects of urine protein on the renal tubular-interstitial fibrosis in the patients with lupus nephritis (LN).


METHODS
Protein was isolated and purified from the urine of six patients with primary LN, 1 male and 5 females, aged 27.4, and incubated with renal tubular cells of the line HK-2 for 0, 1, 2, 12, 24, or 48 h respectively. The mRNA expressions of transforming growth factor beta1(TGF-beta1), collagen I (COL I), and alpha-smooth muscle actin (alpha-SMA) in the HK-2 cells were detected by RT-PCR, and the. protein expressions of TGF-beta1, COL I, and alpha-SMA were detected with Western blotting and indirect immunofluorescence.


RESULTS
The urine protein from the LN patients dose-and time-dependently increased the mRNA and protein expressions of TGF-beta1, COL I, and alpha-SMA in the HK-2 cells. The TGF-beta1 mRNA level 48 h after incubation was 0.39 +/- 0.03, significantly higher than that at the beginning of incubation (0.27 +/- 0.02, P < 0.01), and the TGF-beta1 protein level 48 h after incubation was 0.37 +/- 0.03, 1.7 times that at the beginning of incubation (0.27 +/- 0.04, P < 0.01). The COL I mRNA level 48 h after incubation was 0.38 +/- 0.02, significantly higher than the baseline level (0.22 +/- 0.03, P < 0.01); and the COL I protein level 48 h after incubation was 0.44 +/- 0.03, significantly higher than the baseline level (0.19 +/- 0.02, P < 0.01). The alpha-SMA mRNA level 48 h after incubation was 0.66 +/- 0.04, significantly higher than the baseline level (0.44 +/- 0.03, P < 0.01), and the alpha-SMA protein level 48 h after incubation was 0.43 +/- 0.02, significantly higher than the baseline level (0.24 +/- 0.03, P < 0.01).


CONCLUSIONS
Urine protein may play an important role in the renal tubular-interstitial fibrosis by inducing the production of extracellular matrix and phenotype change in HK-2 cells.
Liu
Guan-xian
GX
Department of Nephrology, Huizhou Municipal Central Hospital, China, Huizhou 516001, China.
Deng
An-guo
AG
Yu
Xue-qing
XQ
Duan
Wen-juan
WJ
Wen
Qiong
Q
Luo
Ning
N
Li
Xiao-yan
XY
D000199:Actins / Q000235:genetics / Q000378:metabolism; D000328:Adult; D015153:Blotting, Western; D002460:Cell Line; D054338:Cell Transdifferentiation / Q000187:drug effects*; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D007684:Kidney Tubules / Q000166:cytology; D008181:Lupus Nephritis / Q000378:metabolism / Q000652:urine*; D008297:Male; D011506:Proteins / Q000302:isolation & purification / Q000494:pharmacology*; D011507:Proteinuria / Q000378:metabolism / Q000652:urine; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D053773:Transforming Growth Factor beta1 / Q000235:genetics / Q000378:metabolism
D000199:Actins; D024042:Collagen Type I; D011506:Proteins; D012333:RNA, Messenger; D053773:Transforming Growth Factor beta1