The Effect Of TIMP-1 Overexpression On Inflammatory Reaction Induced By Ischemical Reperfusion Injury Of The Kidney And Its Mechanism

Background and objectiveAcute renal failure (ARF) is common in clinics, which has a high mortality. It is well established that ischemical reperfusion (I/R) injury plays a important role in the pathophysiological mechanism by which ARF develops. Apoptosis of parenchymal cells and tissue inflammation in target organs are two fundamental pathological events in I/R injury. The latter event is considered as critical for production and development of I/R injury and also is involved in the whole process of injury of target organs. The Molecular mechanism for association between ischemia-induced inflammation and injure of organs is obscure. Our previous work has revealed the inhibitory effects of overexpression of tissue inhibitors of metalloproteinases-1 (TIMP-1) on apoptosis of renal tubular epithelial cells during the renal I/R injure and, as such, function of renal tubules is protected and injure degree is decreased. A number of evidences indicate the crucial role of matrix metalloproteinases (MMPs) in the invasion and metastasis of cancer as well as inflammatory reaction, which can be inhibited by TIMP-1. However, the relation of TIMP-1 and other relevant inflammatory molecules is not well known. Thus, the exploration of molecular mechanism by which inflammatory reaction is produced in renal I/R injure will provide a possibility of discovering new candidate molecules involved in ischemia-induced inflammation and developing targeted drugs for prophylaxis and treatment of ARF with a substantial theoretical significance and applicable value. To investigate the effect of TIMP-1 overexpression on the inflammatory reaction induced by I/R and related molecular mechanism.MethodsIn the present study, three types of male mice were used, i.e. human TIMP-1 (hTIMP-1) transgenic mice, wild-type mice, and minocycline (an inhibitor of MMPs) -treated mice. The procedure of minocycline treatment was i.p. injection of minocycline with a dose of 45mg/kg 12h before preparation of a model of renal I/R injure. (1) The preparation of an model of renal VR injure: The method of surgery mediated occlusion of bilateral kidney pedicle was used. Intraoperatively, occlusion of bilateral kidney pedicle was carried out for 30min, and subsequently reperfusion was performed with selective five time points of 1h, 4h, 24h, 48h, and 72h. The above three types of mice were all randomly divided into six groups, including negative control group (only to open abdomen and find kidney pedicle), reperfusion lh group, 4h group, 24h group, 48h group, and 72h group, respectively. Every group had 5 mice with total 18 groups. (2) Determination of inflammatory reaction induced by I/R: mice were sacrificed, and specimens of blood and kidney were collected for further evaluations of related items. Observation items were as followed:â‘ renal function: serum creatinine (Scr) and blood urea nitrogen (BUN);â‘¡active inflammation-related materials in kidney: myeloperoxidase (MPO);â‘¢renal histopathology;â‘£expressions of TIMP-1 and vascular cell adhesion molecule-1 (VCAM-1): reverse-transcriptase polymerase chain reaction (RT-PCR) and Western blot used.Results(1) Compared with wild-type group, after renal I/R injure hTIMP-1 transgenic group showed following changes:â‘ decreased level or activity of Scr, BUN, and MPO with the two former having significant difference (P<0.01) and no difference in the latter;â‘¡significantly decreased score of renal tubule (P<0.01);â‘¢remarkably increased expression of TIMP-1 mRNA (P<0.01) and obviously decreased expression of VCAM-1 mRNA and protein (P<0.05).(2) Compared with wild-type group, after renal I/R injure minocycline-treated group showed following changes:â‘ significantly decreased level or activity of Scr, BUN, and MPO (P<0.01);â‘¡evidently decreased score of renal tubule (P<0.01);â‘¢no difference in expression of TIMP-1 mRNA and VCAM-1 mRNA and protein (P>0.05).ConclusionsThe present study shows that TIMP-1 overexpression can inhibit inflammatory reaction induced by renal I/R injure, and the inhibitory effect is probably related with downregulation of VCAM-1 expression.