Shao-Bin Duan

NEPHROTOXICITY OF HIGH- AND LOW-OSMOLAR CONTRAST MEDIA: The protective role of amlodipine in a rat model

Purpose: To evaluate the nephrotoxicity of high- and low-osmolar contrast media (HOCM, LOCM) on kidneys in Sprague-Dawley rats. The protective role of amlodipine was studied. Material and Methods: Forty rats of both sexes were randomly divided into 5 groups (n = 8/group) and glycerine for inducing renal failure was given to all rats except controls. Results: In diatrizoate-injected rats, blood urea nitrogen (BUN) and serum creatinine (SCr) were increased; levels of phospholipase A2 (PLA2), lipid peroxide (LPO) and calcium were also increased in renal tissues. There was no significant difference between LOCM (iohexol) animals and glycerol controls either in the renal levels of PLA2, LPO and calcium or in the levels of BUN and SCr. The histologic changes were milder in the LOCM animals than in the HOCM animals. In the group pretreated with amlodipine, no increase in the levels of BUN or SCr was discovered and the renal content of PLA2, LPO and calcium were significantly lower than in the HOCM group; the renal injuries induced by diatrizoate were alleviated. Conclusion: The HOCM, diatrizoate, was more toxic to rat kidneys than the LOCM iohexol; PLA2, LPO and calcium load played a role in producing renal function impairment induced by diatrizoate meglumine; amlodipine protected the renal tissue from nephrotoxicity induced by diatrizoate.

The Protective Role of Telmisartan Against Nephrotoxicity Induced by X-ray Contrast Media in Rat Model

Background: Contrast-induced nephropathy is a serious complication of diagnostic and interventional procedures. Purpose: To evaluate the nephrotoxicity of high- and low-osmolar contrast media (HOCM, LOCM) on kidneys in Sprague-Dawley rats. Telmisartan was administered to confirm its protective role against nephrotoxicity induced by contrast media. Material and Methods: Sixty male rats were randomly divided into six groups (n=10/group). Glycerin was given to all rats except controls to induce renal injury. HOCM (diatrizoate) or LOCM (iohexol) (10 ml/kg b.w., 300 mg I/ml) was given through a caudal vein. Serum creatinine level was measured by an automatical biochemical analyzer. Caspase-3 activity and Angiotensin II (Ang II) level of renal tissue were detected by fluorometric method and radioimmunoassay, respectively. The renal injury was also assessed by hematoxylin and eosin and TdT-mediated deoxyuridine nick end-labeling staining. Results: In diatrizoate-injected rats, serum creatinine level was increased (P<0.001). There was no significant difference between iohexol animals and glycerol controls in the level of serum creatinine. The renal caspase-3 activity and Ang II levels in HOCM and LOCM groups were higher than those in glycerol control group (P<0.001). The percentage of apoptotic tubular cells and pathological scores were lower in the iohexol animals than that in the diatrizoate animals (P<0.001). In the groups pretreated with telmisartan, no increase in the levels of serum creatinine, renal Ang II, and caspase-3 activity was observed (P>0.05). The renal injuries induced by contrast media were alleviated. Conclusion: Both HOCM (diatrizoate) and LOCM (iohexol) could cause renal tubular cell apoptosis in the kidneys damaged by glycerin. LOCM was less toxic to rat kidneys than HOCM. Caspase-3 and Ang II might play a role in renal tubular cell apoptosis induced by contrast media. Telmisartan protected the renal tissue from nephrotoxicity induced by contrast media.

Norcantharidin Inhibits Renal Interstitial Fibrosis by Blocking the Tubular Epithelial-Mesenchymal Transition

Epithelial–mesenchymal transition (EMT) is thought to contribute to the progression of renal tubulointerstitial fibrosis. Norcantharidin (NCTD) is a promising agent for inhibiting renal interstitial fibrosis. However, the molecular mechanisms of NCTD are unclear. In this study, a unilateral ureteral obstruction (UUO) rat model was established and treated with intraperitoneal NCTD (0.1 mg/kg/day). The UUO rats treated with NCTD showed a reduction in obstruction-induced upregulation of α-SMA and downregulation of E-cadherin in the rat kidney (P<0.05). Human renal proximal tubule cell lines (HK-2) stimulated with TGF-β1 were treated with different concentrations of NCTD. HK-2 cells stimulated by TGF-β1 in vitro led to downregulation of E-cadherin and increased de novo expression of α-SMA; co-treatment with NCTD attenuated all of these changes (P<0.05). NCTD reduced TGF-β1-induced expression and phosphorylation of Smad2/3 and downregulated the expression of Snail1 (P<0.05). These results suggest that NCTD antagonizes tubular EMT by inhibiting the Smad pathway. NCTD may play a critical role in preserving the normal epithelial phenotype and modulating tubular EMT.

Norcantharidin Ameliorates Proteinuria, Associated Tubulointerstitial Inflammation and Fibrosis in Protein Overload Nephropathy

Norcantharidin (NCTD), the demethylated analog of cantharidin isolated from Mylabris, is an anticancer drug routinely used against various human cancers in China. The aims of this study are to learn if NCTD has a protective action against severe proteinuria and consequent interstitial inflammation and fibrosis, and if the inhibition of nuclear factor-ĸB (NF-ĸB) and connective tissue growth factor (CTGF) by NCTD might be involved. Male Sprague-Dawley rats with protein overload nephropathy induced by intraperitoneally injected bovine serum albumin were used as a model. The histopathological examination of kidney tissue in the 9th week by light microscopy and scanning electron microscopy revealed that inflammatory cells had extensively infiltrated into the tubulointerstitial areas with interstitial fibrosis. The administration of NCTD at 0.1 mg/kg/day to the bovine-serum-albumin-injected animal models effectively reduced the proteinuria, and prevented the proteinuria-induced interstitial inflammation and fibrosis. Expressions of the NF-ĸB p65 subunit and CTGF, detected by immunohistochemistry, Western blotting and reverse-transcription polymerase chain reaction, were upregulated in protein overload nephropathy and were attenuated by NCTD. Inhibition of the expressions of the NF-ĸB p65 subunit and CTGF was one beneficial effect of NCTD. These results suggest that in addition to the antiproteinuric action of NCTD, due to its anti-inflammatory and antifibrotic effects as shown in the present study, it may become a therapeutic agent for proteinuria and its associated chronic inflammatory and fibrotic nephropathy.

Cordycepin inhibits albumin-induced epithelial-mesenchymal transition of renal tubular epithelial cells by reducing reactive oxygen species production

Albumin induced epithelial-mesenchymal transition (EMT) of renal tubular cells through reactive oxygen species (ROS) pathway plays an important role in tubulointerstitial fibrosis. Cordycepin (3 -deoxyadenosine), a potential antioxidant, was demonstrated to have various pharmacological effects and could inhibit EMT of some cells. However, the role of cordycepin on albumin-induced EMT in renal tubular cells (HK2) is unclear. In this study, we investigated the effect of cordycepin on albumin-induced EMT of HK2 cells and its mechanisms. HK-2 cells were exposed to bovine serum albumin with or without pretreatment with cordycepin. Results showed that albumin significantly induced EMT formation of HK-2 which associated with NADPH oxidase activation and intracellular ROS overproduction through increased Rac1 activity and expression of NOX4, p22phox and p47phox, while these effects were abolished in that pretreated with cordycepin. In conclusion, cordycepin could ameliorate albumin-induced EMT of HK2 cells by decreasing NADPH oxidase activity and inhibiting ROS production.

Urinary KIM-1, IL-18 and Cys-c as early predictive biomarkers in gadolinium-based contrast-induced nephropathy in the elderly patients.

BACKGROUND/AIMS This study was designed to investigate whether urinary kidney injury molecule-1 (KIM-1), interleukin-18 (IL-18) and cystatin C (Cys-C) are early predictive biomarkers for gadolinium-based contrast-induced nephropathy (Gd-CIN) in the elderly patients undergoing gadolinium-enhanced magnetic resonance imaging (MRI). METHODS 60 elderly patients undergoing enhanced MRI using gadolinium-based contrast media were enrolled. Urine samples were collected before and 24 hours and 48 hours after the procedure, and KIM-1, IL-18 and Cys-C levels were measured by using an ELLSA kit respectively. Serum samples before and 24 hours and 48 hours after the procedure were also collected, and creatinine was measured by automatic biochemical analyzer. RESULTS Gd-CIN was diagnosed in 8 of 60 (13.3%) patients. At 24 hours after MRI with gadolinium administration in the Gd-CIN group, the urinary KIM-1, IL-18 and Cys-C were significantly increased. Logistic regression analysis showed that urinary KIM-1 and IL-18 at 24 hours after gadolinium injection were independent predictive markers of Gd-CIN. The predictable time of acute kidney injury (AKI) onset determined by urinary KIM-1, IL-18 and Cys-C was 24 hours earlier than by serum creatinine. CONCLUSIONS Urinary KIM-1, IL-18 and Cys-C could be early predictive biomarkers of Gd-CIN in the elderly patients, which showed a good performance in early diagnosis of Gd-CIN as compared with serum creatinine.

Connective Tissue Growth Factor Knockdown Attenuated Matrix Protein Production and Vascular Endothelial Growth Factor Expression Induced by Transforming Growth Factor‐β1 in Cultured Human Peritoneal Mesothelial Cells

Connective tissue growth factor (CTGF), a downstream mediator of transforming growth factor‐β1 (TGF‐β1) inducing fibrosis, has recently been implicated in peritoneal fibrosis. Extracellular matrix (ECM) accumulation and angiogenesis are characteristic changes in peritoneal fibrosis. In this study we investigated the effect of CTGF knockdown via interference RNA (RNAi) on ECM production and vascular endothelial growth factor (VEGF) expression induced by TGF‐β1 in human peritoneal mesothelial cells (HPMCs). Four CTGF short hairpin RNA (shRNA) expression constructs were generated using the pRetroSuper vector, and infectious retroviral particles were prepared to infect HPMCs. Expression levels of CTGF, fibronectin(FN), collagen 1 (col 1), laminin, and VEGF mRNA and protein were measured by semi‐quantitative reverse transcription polymerase chain reaction and western blot assay. CTGF expression was increased after stimulation with TGF‐β1, but inhibited using each of the four independent CTGF shRNA constructs (P < 0.01). Moreover, expression of ECM proteins (FN, col 1, and laminin) and VEGF were upregulated after incubation with TGF‐β1, but elevated levels of ECM and VEGF induced by TGF‐β1 were significantly inhibited by RNAi (P < 0.01), but not by the empty retroviral vector (P > 0.05). From these results, we concluded that retrovirus‐mediated CTGF shRNA can effectively inhibit ECM production and VEGF expression induced by TGF‐β1 in HPMCs. This study suggests that downregulation of CTGF may represent a potential therapeutic approach for peritoneal fibrosis through decreasing ECM accumulation and angiogenesis.

Mast cell infiltration is involved in renal interstitial fibrosis in a rat model of protein-overload nephropathy.

Aims: The present study investigated the relationship between mast cells (MCs) and the protein expression of stem cell factor (SCF) and transforming growth factor-β1 (TGF-β1) in the regions of renal interstitial fibrosis with protein-overload nephropathy, in order to provide a good animal model to study the mechanism of renal fibrosis induced by proteinuria. Methods: 60 male Sprague-Dawley rats were divided into a bovine serum albumin (BSA) group and a control group. The intensity of MCs infiltration was examined by toluidine blue and chymase and tryptase staining. The protein expression of SCF and TGF-β1 was respectively examined by immunohistochemical and immunofluorescence staining. Results: Severe proteinuria was induced in rats of the BSA group. Expression of SCF and TGF-β1 was detected in the tubular and the interstitial cells. The number of MCs positively correlated with the severity of interstitial lesions and the expression of SCF and TGF-β1. Conclusion: Our results demonstrated that in protein-overload nephropathy, MCs infiltrated into the kidney, and the expression of SCF and TGF-β1 gradually increased. They might play important roles in the development of renal interstitial fibrosis, but the underlying mechanism needs to be further studied.

Mitochondria-targeted peptides prevent on contrast-induced acute kidney injury in the rats with hypercholesterolemia.

Abstract Objective: The objective of this study is to evaluate the effect and mechanism of mitochondria-targeted peptides (MTP131 and SPI20) on contrast-induced acute kidney injury (CI-AKI) in rats with hypercholesterolemia. Method: Forty SD rats were randomly divided into normal diet group (NN, n = 8) and high cholesterol supplemented dietary group (HN, n = 32). At the end of 8 weeks, the group HN was divided into four subgroups. All Rats were given injection of either diatrizoate (10 mL/kg) or equal volume of normal saline, the rats pretreated with MTP131 or SPI20 were given injection with MTP131 or SPI 20 (3 mg/kg) by peritoneal cavity for 3 times. Blood, urine and renal tissue samples were prepared to determine biochemical parameters. The renal pathological changes were evaluated by hematoxylin and eosin staining and scored semiquantitatively, The protein expression of renal NOX4 was also measured by Western blotting. Results: In diatrizoate-injected rats, Serum creatinine (Scr), fractional excretion of sodium (FeNa%), fractional excretion of potassium (FeK%), pathological scores, renal malondialdehyde (MDA) content, the NADPH oxidase activity and the expression of NOX4 in kidney tissue were significantly increased (p < 0.01). In the groups pretreated with MTP131 or SPI20, the levels of Scr, FeNa%, FeK%, MDA content and NADPH oxidase activity in renal tissue decreased (p < 0.01), the levels of renal super oxygen dehydrogenises and ATPase activity increased (p < 0.01). The renal injuries induced by contrast media (CM) were alleviated. Conclusion: MTP131 and SPI20 might protect acute kidney injury induced by CM in rats with hypercholesterolemia.

Epithelial-to-Mesenchymal Transdifferentiation of Renal Tubular Epithelial Cell Mediated by Oxidative Stress and Intervention Effect of Probucol in Diabetic Nephropathy Rats

Objective: To elucidate the relationship of oxidative stress and specificity protein 1 (Sp1) in the process of epithelial-to-mesenchymal transdifferentiation (EMT) and also to investigate the molecular mechanism of protective effect of probucol on the pathogenesis of diabetic kidney disease (DKD). Methods: Thirty male Sprague–Dawley (SD) rats were randomly divided into control group, diabetic group, and diabetic group under probucol therapy (n = 10 per group). The biochemical indicators including 24-h urinary total protein (24-h UTP) excretion, blood glucose (BG), lipids [triglycerides (TGs), total cholesterol (TC)], serum creatinine (Scr), creatinine clearance rate (Ccr), kidney tissue malondialdehyde (MDA) level, and glutathione peroxidase (GSH-Px) activity were assessed in all groups. The renal pathological changes were evaluated by hematoxylin and eosin (HE) and Masson staining. The protein expression of Sp1, α-smooth muscle actin (α-SMA), and E-cadherin was also measured and analyzed by immunohistochemistry and Western blotting. Results: Compared with the control group, the BG, TC, Scr, 24-h UTP, and MDA level of renal tissue increased significantly and the Ccr reduced in the rats of diabetic group (all p < 0.01). The pathological scores and the expression of Sp1 and α-SMA in renal tissue were up-regulated (p < 0.01) and the expression of E-cadherin was down-regulated significantly in the diabetic animals (p < 0.01). In the diabetic animals treated with probucol, the renal injuries were alleviated (p < 0.01). Conclusions: Oxidative stress may play an important role in the EMT process of tubular epithelial cells. Probucol could ameliorate renal disease progression in this model of diabetic nephropathy, which might be due to an antioxidant action, down-regulation of Sp1 protein expression, and inhibition of renal tubular EMT.