P0735ELAVATED INTRACELLULAR COPPER CONTRIBUTES A UNIQUE ROLE TO KIDNEY FIBROSIS BY LYSYL OXIDASE MEDIATED MATRIX CROSSLINGKING

Abstract

Abstract Background and Aims Copper is an essential trace element required for many biological processes. Some studies have demonstrated that copper accumulating was related to liver fibrosis and lung fibrosis, but the underlying mechanism is not very clear. Copper is the essential unit of lysyl oxidase (LOXs), which are the key enzymes of crosslinking of extracellular matrix. Method Sprague-Dawley rats were divided into the sham group, unilateral ureteral obstruction (UUO) operated group and UUO treated with copper chelating agents tetrathiomolybdate (TM). Rat kidney fibroblast cells (NRK-49F) were used in vitro. The concentration of copper, the LOXs activity and the degree of cross-linking of extracellular collagen were detected in vivo and vitro. Results (1) The copper concentration in serum, urine and kidney of rats increased significantly at 7 days after UUO surgery; After treatment of TGF-β1, the intracellular copper concentration was increased significantly in cells; The concentration of copper in patients` serum is on the rise with the progression of chronic kidney disease (CKD). (2) The expression of CTR1 was upregulated in the kidneys of UUO rats; The level of CTR1 was increased significantly by TGF-β1 in vitro; (3) Blockage of Smad2/3 suppresses TGF-β1-induced expression of CTR1; (4) Downregulation of CTR1 significantly inhibited the intracellular copper concentration; (5) The activity of LOXs was increased significantly after TGF-β1 treatment; (6) Downregulation of CTR1 significantly inhibited the activity of LOXs and the cross-linking of extracellular collagen induced by TGF-β1 in vitro; (7) The concentration of copper, the degree of collagen cross-linking and the deposition of collagen were decreased in the kidney tissue of UUO rats after treatment with TM. The concentration of intracellular copper, the activity of LOXs and the degree of collagen cross-linking were attenuated with treatment of TM in vitro. Conclusion We firstly found that the intracellular copper accumulating was closely to renal fibrosis. The underlying mechanism was related with the increasing expression of CTR1 and activity of LOXs. Treatment with TM ameliorated the renal fibrosis. This study presented a novel treatment target for renal fibrosis.