Left-right determination factor is down-regulated in fibrotic renal tissue of human hydronephrosis.

OBJECTIVE: • To compare the expressions of common fibrosis-relevant genes in hydronephrosis-induced fibrotic renal tissues and normal human renal tissues, thereby providing insights into the cellular and molecular mechanisms of renal fibrosis resulting from hydronephrosis. PATIENTS AND METHODS: • A total of 12 extensively fibrotic renal tissue samples from patients with hydronephrosis (H-group) and six normal renal tissue samples from patients who underwent nephrectomy for renal cell carcinoma (N-group), along with their clinical data, were collected at Renmin Hospital of Wuhan University in China between October 2005 and August 2007. • These tissue samples were compared for their transforming growth factor-ß (TGF-ß)/bone morphogenetic protein (BMP) pathway-related gene profiles using a real-time polymerase chain reaction (PCR) microarray. • Subsequently, reverse transcriptase-PCR assays were used to validate the expression changes of left-right determination factor (LEFTY), a gene of interest, at the mRNA level. • The different expression of LEFTY at the protein level was confirmed by western blotting and immunohistochemistry assays. RESULTS: • The results showed that 49 genes were differently expressed in fibrotic renal tissues relative to normal control tissues. Among these genes, 25 were up-regulated and 24 were down-regulated. • LEFTY-B, one of the most markedly altered genes, was down-regulated 13.55-fold compared with N-group tissues. • RT-PCR showed that the LEFTY-A (6.05-fold down-regulated, P < 0.001) and LEFTY-B (12.5-fold down-regulated, P < 0.001) genes, two members of the LEFTY family in human tissues, were both significantly down-regulated in H-group tissues. • Similarly, down-regulations of LEFTY-A (0.25-fold vs N-group, P < 0.001) and LEFTY-B (0.20-fold vs N-group, P < 0.001) proteins were detected by western blotting (P < 0.001). • Immunohistochemical staining showed different distributions of LEFTY in the two tissue samples, and quantitative image analyses confirmed that LEFTY protein expression was lower in H-group tissues than in N-group tissues (P < 0.001). CONCLUSIONS: • The gene and protein expressions of LEFTY were found to be down-regulated in extensively fibrotic renal tissues induced by hydronephrosis. • LEFTY may represent an ideal candidate for a therapeutic target for renal fibrosis.

Interferon-γ improves renal interstitial fibrosis and decreases intrarenal vascular resistance of hydronephrosis in an animal model.

OBJECTIVES: To investigate the effect of interferon (IFN)-γ administration on renal interstitial fibrosis (RIF) and intrarenal vascular resistance of diseased kidneys in a reversible unilateral ureteral obstruction (RUUO) animal model. METHODS: Thirty-six male Sprague-Dawley rats were randomly divided into three groups: RUUO with intramuscular IFN-γ treatment (400 IU/d; RUUO + IFN), RUUO with vehicle treatment, and sham operation. RUUO was induced by clamping the left ureter using a small polyethylene tube. The obstruction was reversed seven days after the operation by removing the tube. Six animals in each group were killed at days 7 and 14. The intrarenal resistive index (RI) of diseased kidneys was measured by colored Doppler flow imaging. RIF was evaluated using Masson's trichrome staining. RESULTS: The obstruction was successfully reversed in all animals. At day 7, the RIF scores were 32.1 ± 3.1 and 40.3 ± 3.1 in the RUUO + IFN group and the RUUO group, respectively. The RI increased by 87% in the RUUO group and by 64% in the RUUO + IFN group compared with sham. At day 14, the RIF scores decreased to 24.6 ± 3.9 in the RUUO + IFN group, but increased to 50.8 ± 4.4 in the RUUO group. The increase of RI was reduced to 64% in the RUUO group and to 20% in the RUUO + IFN group. Ureteral obstruction induced few lesions in the contralateral kidneys, and IFN-γ administration had no significant effect on them, although it exerted an antifibrotic effect on the obstructed kidneys. CONCLUSIONS: IFN-γ administration restored or preserved renal histology and hemodynamics in an animal model of renal fibrosis after surgical reversal of hydronephrosis.