Tissue inhibitor of metalloproteinase-1 exacerbated renal interstitial fibrosis through enhancing inflammation.
BACKGROUND
Tissue inhibitor of metalloproteinase-1 (TIMP-1) is associated with renal fibrosis. Furthermore, it is a multi-functional protein, and whether it has other roles in renal fibrosis is unknown. As several inflammatory mediators are substrates of matrix metalloproteinases (MMPs), TIMP-1 might affect renal fibrosis via inflamatory pathways.


METHODS
Plasmids containing the sense and antisense human TIMP-1 sequence were stably transfected into the human kidney proximal tubular epithelial cell line (HKC), MMP-2 and MMP-9 siRNA were transiently transfected into HKC and the transfected cells were stimulated with phorbol 12-myristate 13-acetate (PMA). In vivo, we established unilateral ureteral obstruction (UUO) models by using homozygote human TIMP-1 transgenic mice. The expression of intercellular adhesion molecule-1 (ICAM-1) in transfected cells and F4/80-positive cells in the renal interstitium were examined by indirect immunofluorescence. Protein levels in the cells and UUO models were examined by western blot, and the activities of the gelatinases and TIMP-1 were examined by gelatin zymography and reverse zymography, respectively.


RESULTS
After stimulation with PMA, the activities of the gelatinases were decreased, ICAM-1 was upregulated, and soluble ICAM-1 in the supernatant was decreased, in HKC transfected with sense TIMP-1, and ICAM-1 was increased in HKC transfected with MMP-9 siRNA. At 14 days after UUO, it was found that compared with wild-type mice, in transgenic mice, with upregulation of TIMP-1, activities of gelatinases were downregulated, ICAM-1, transforming growth factor-beta1 (TGF-beta1), collagens I and III were upregulated, and the extent of renal fibrosis and infiltration of macrophages was more severe.


CONCLUSIONS
Overexpression of TIMP-1 could promote renal interstitial fibrosis through the inflammatory pathway, which might be partly induced by upregulating ICAM-1.
Cai
Guangyan
G
Department of Nephrology, Institute of Nephrology and Key Lab of PLA, Chinese General Hospital of PLA, Fuxing Road 28, Beijing 100853, PR China.
Zhang
Xueguang
X
Hong
Quan
Q
Shao
Fengmin
F
Shang
Xiyao
X
Fu
Bo
B
Feng
Zhe
Z
Lin
Hongli
H
Wang
Jianzhong
J
Shi
Suozhu
S
Yin
Zhong
Z
Chen
Xiangmei
X
D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D004195:Disease Models, Animal; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D018836:Inflammation Mediators / Q000032:analysis*; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism*; D007687:Kidney Tubules, Proximal / Q000166:cytology; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D018613:Microscopy, Confocal; D009395:Nephritis, Interstitial / Q000503:physiopathology*; D011336:Probability; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000378:metabolism*; D014162:Transfection; D015854:Up-Regulation
D018836:Inflammation Mediators; D018799:Intercellular Adhesion Molecule-1; D019716:Tissue Inhibitor of Metalloproteinase-2; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9