[Expression of matrix metalloproteinase-9 in renal tissues of rats with chronic allograft nephropathy at early stage and the role thereof].
OBJECTIVE
To investigate the expression of matrix metalloproteinase-9 (MMP-9) in the renal tissues of rats with chronic allograft nephropathy (CAN) at early stage and its role in CAN.


METHODS
Orthotopic transplantation of left kidney was performed between 10 male LEW rats and 10 male F344 rats with the formers as recipients. Small dose cyclosporin A was used to suppress acute rejection. Ten days after the operation the right kidneys of the recipients were resected. Ten LEW rats and 10 F344 rats with their single kidneys resected were used as controls. Twelve weeks after the operation the rats were harvested to take out the transplanted kidneys to undergo histologic examination. Immunochemistry was used to examine the expression of MMP-9 protein and transforming growth factor (TGF)-beta1 . RT-PCR was used to examine the expression of MMP-mRNA in the kidney tissues. At the same time 24 h urine samples were collected to examine the urinary protein. The relationship between the expression of MMP-9 and TGF-beta1 and the quantity of SMCs and mononuclear cells.


RESULTS
The 24 h urinary protein level of the experimental group was not significantly different from those of the F3244 control group and LEW control group. The serum inosine level of the experimental group was significantly higher than that of the F334 control group and was not significantly different from that of the LEW control group. The degrees of pathologic change degree (Banff score) and fibrosis of kidney interstitium, and the number of inflammatory cells infiltrating into tubulointerstitium, arterial smooth muscle cells (SMCs) in renal cortex, and SMCs in vascular wall of the experimental group were all significantly higher than those of the 2 control groups. The expressions of MMP-9 protein and TGF-beta1 in the kidney interstitium and vascular wall and the expression of MMP-9 mRNA were all significantly higher than those of the 2 control groups. The expression of MMP-9 mRNA in kidney tissues was positively correlated with the degree of infiltration of interstitial mononuclear cells. The MMP-9 mRNA expression level was positively correlated with the number of interstitial mononuclear cells. The MMP-9 protein expression level was positively correlated with the TGF-beta1 expression level in the tubulointerstitium and in the renal arterial wall.


CONCLUSIONS
MMP-9 plays a key role in CAN at early stage. Its expression may be induced by TGF-beta1.
Zou
He-qun
HQ
Department of Nephrology, Fifth Affiliated Hospital of Sun Yat-sen University, Zhuhai 519000, China.
Yao
Juan
J
Wang
Yu-xin
YX
Wang
Jun
J
Li
Duo
D
Wang
Pei
P
D000818:Animals; D016572:Cyclosporine / Q000627:therapeutic use; D006789:Host vs Graft Reaction / Q000276:immunology; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D007668:Kidney / Q000201:enzymology*; D007674:Kidney Diseases / Q000201:enzymology* / Q000473:pathology; D016030:Kidney Transplantation / Q000009:adverse effects*; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000096:biosynthesis* / Q000235:genetics; D051381:Rats; D011916:Rats, Inbred F344; D011917:Rats, Inbred Lew
D007166:Immunosuppressive Agents; D016572:Cyclosporine; D020780:Matrix Metalloproteinase 9