Observation of extracellular matrix damage in the kidney of rats with multiple organ dysfunction syndrome

Abstract

Objective To determine the levels of type Ⅳ collagen and matrix metalloproteinase-9 ( MMP-9 ) in the serum and kidney of rats with the multiple organ dysfunction syndrome ( MODS ) and investigate the mechanism of extracellular matrix damage in renal failure of MODS.Methods Forty adult male Sprague- Dawley (SD) rats were randomly (ramdom number) divided into two groups,namely the normal control group ( n =8 ) and the MODS model group ( n =32 ).The rats of model group were further divided into four sub-groups as per different intervals,6 h,12 h,24 h and 48 h,after modeling (n =8 in each).The animal models of MODS were established by two hits,the left eyeball of each model rat was removed to bleed to 2 ml bloocd/100 g body weight and lipopolysaccharide ( LPS,5 mg/kg) was injected into intraperitoneal cavity of model rats four hours later. The same volume of saline instead was injected intraperitoneally into rats of control group.All rats were sacrificed at different intervals.Creatinine (Cr)and blood urea nitrogen (BUN) were determined by using a Hitachi Automatic Biochemical Analyzer.The histological changes in renal tissue were observed under light microscope and transmission electronic microscope.The levels of serum type Ⅳ collagen and MMP - 9 protein were measured by using enzyme linked immunosorbent assay (ELISA).Type Ⅳ collagen and MMP- 9 protein levels in renal tissue were detected by western blot.One - way ANOVA was used for comparison among multiple groups.Results Compared with the control group,Cr and BUN were significantly higher in MODS group ( P ＜0.05 ).There were no histopathological changes in kidney of rats in control group,and the renal injury was serious in rats with MODS.The remarkable edema of basement membrane and defect of collagen fibers in renal tissue were observed in MODS group.Compared with the control group,the levels of MMP-9 in serum increased 6-48 hours after modeling and peaking at interval of 12 hours after modeling ( P ＜ 0.05 ).The protein levels of type Ⅳ collagen increased not significantly in 6 h group and 12 h group in comparison with control group (P ＞ 0.05 ),while those in 24 h group and 48 h group significantly increased ( P ＜ 0.01 ).The levels of MMP -9 in renal tissue of rats with MODS increased in 6 h group and 12 h group (P＜0.05),peaked in 24 h group ( P ＜ 0.05 ),and decreased in 48 hours.However,the level of Ⅳ collagen in serum of rats with MODS decreased significantly 6-48 hours after modeling (P ＜ 0.05 ) Conclusions The injury of extracellular matrix is an important factor to the kidney damage in MODS and it may he used for early diagnose and as a treatment target for kidney injury in MODS. Key words: Multiple organ dysfunction syndrome; Matrixmetalloproteinase-9; Endothelial cell; Extracellular matrix; Collagen Ⅳ; Lipopolysaccharide; Systemic inflammatory response syndrome; Two hits; Rat