AIM: To investigate the effect of L-arginine(L-arg) on the production of collagens of human mesangial cells. METHODS: Radioimmunoassay, hydroxyproline colorimetric assay and reverse transcription polymerase chain reaction (RT-PCR) were used to determine procollagen Ⅲ, total collagen level in the supernatant and expression of collagen Ⅳ mRNA in human mesangial cells. RESULTS: L-arg significantly inhibited the production of procollagenⅢ, total collagen in the supernatants ( P

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Objective To investigate whether low density lipoprotein receptor (LDLr) pathway involves in the progression of vascular calcification (VC) in hemodialysis patients under microinflammation.Methods Twenty-eight hemodialysis patients were divided into control and inflammation group according to plasma C-reactive protein level.Surgically removed tissues from radial artery of patients receiving arteriovenostomy were used in experiments.Foam cell formation and calcification deposition were observed by hematoxylin-eosin (HE) and alizarin red S staining respectively.VC-related protein expression,such as bone morphogenetic proteins-2 (BMP-2),collagen Ⅰ,alkaline phosphatase (ALP),and LDLr and its related nuclear factor of transcriptional regulation,such as sterol regulatory element binding protein-2 (SREBP-2) and SREBP cleavage-activating protein (SCAP),were detected by immunohistochemistry and immunofluorescence staining.Results HE and alizarin red S staining showed that there were parallel increased foam cell formation and calcium deposit in continuous cross-sections of radial arteries in inflammation group compared to control group,which were closely correlated with increased protein expressions of LDLr,SREBP-2,BMP-2,and collagen Ⅰ as shown by immunohistochemical and immunofluorescent staining.Confocal microscopy confirmed that inflammation enhanced the translocation of SCAP/SREBP-2 complex from endoplasmic reticulum to Golgi,thereby activating LDLr gene transcription.Inflammation increased protein expression of ALP and reduced protein expression of alpha-smooth muscle actin,contributing to the phenotype conversion of vascular smooth muscle cells in calcified vessels from the fibroblastic to the osteogenic,which were the main cell components in VC.Further analysis showed that the disruption of LDLr pathway induced by inflammation was positively correlated with the enhanced expression of BMP-2 and collagen Ⅰ (r=0.782,P＜0.01; r=0.644,P＜0.05).Conclusion Inflammation accelerates the progression of VC in hemodialysis patients through the disruption of LDLr feedback regulation.

Objective To investigate the effects of angiotensin Ⅱ (Ang Ⅱ) stimulating on cholesterol influx in human renal proximal tubular epithelial cells (HK-2) and the relation to low-density lipoprotein receptor (LDLr) pathway.Methods HK-2 cells were cultured and divided into the control group (incubated with serum-free medium) and Ang Ⅱ group (treated by 10-7 mol/L of Ang Ⅱ for 24 hours).The effects of Ang Ⅱ on lipid accumulation were examined by Oil red O staining and a quantitative assay of intracellular cholesterol.The expression of LDLr,sterol regulatory elementbinding protein (SREBP) cleavage activating protein (SCAP) and SREBP-2 mRNA and protein were examined by real-time PCR and Western blotting.The cotranslocation of SCAP-SREBP-2 from endoplasmic retieulum to Golgi in HK-2 cells was examined by immunofluorescent staining under confocal microscopy.Results Ang Ⅱ treatment increased intracellular lipid accumulation in HK-2 cells,which was associated with increased mRNA and protein expression of LDLr,SCAP,and SREBP-2 in HK-2 cells induced by Ang Ⅱ.Furthermore,results from confocal microscopy observation demonstrated that Ang Ⅱ increased the translocation of SCAP/SREBP-2 complex from endoplasmic reticulum to Golgi,thereby up-regulating LDLr gene transcription.Conclusion Ang Ⅱ disrupts LDLr feed-back regulation to increase cholesterol uptake and induce intracellular lipid accumulation.

Objective To investigate the effects of monocytes on phenotypic changes of human proximal tubular HK-2 cells and the mechanism.Methods Monocytes were co-cultured with HK-2 cells.Morphological changes of HK-2 cells were detected by inverted phase contrast microscope.Expressions of E-cadherin,α-SMA and fibronectin were assessed by RT-PCR,Western blotting and immunocytochemical staining.Flow cytometry techniques was applied to evaluate intercellular cell adhesion molecule-1 (ICAM-1) expression on HK-2 cells.The intracellular signal was investigated by gene microarr ay.Results The typical epithelial cell morphology of HK-2 cells disappeared after co-culture with monocytes,accompanied by decreased E-cadherin expression and increased α-SMA and fibronectin expression (all P＜0.05).The expression of ICAM-1 on HK-2 cells was increased by monocytes stimulation.Interestingly,administration of CD18 antibody directly inhibited the phenotypic change of HK-2 cells.Furthermore,NF-κB signaling might be critical in mediating this process,and blockade of this signaling pathway could inhibit 1CAM-1 expression and epithelial mesenchymal transition (EMT) formation.Conclusion Monocytes can directly induce EMT of HK-2 cells via up-regulating ICAM-1 through NF-κB signaling pathway.

Objective To develop a model of type 2 diabetes with early renal injury on spontaneously hypertensive rats (SHR). Methods The 6-week old SHR were fed with the diets enriched with sucrose (20%, W/W), lard (10%, W/W), cholesterol (2.5%, W/W) and chleolate (1%, W/W) to induce insulin resistance. Hyperglycemia was developed by intraperitoneal injection of streptozotocin (STZ, 35 mg/kg). Wistar-Kyoto rats (WKY) were used as normal controls. Rats with plasma glucose (PGL) ≥ 16.7 mmol/L were diagnosed as diabetes. Eight weeks after the induction of diabetes, plasma triglyceride (TG), cholesterol (CHO), glucose, systolic pressure(SP), 24-h urine protein excretion (Upro) were examined in all the rats, and the homeostasis model assessment of insulin resistance (HOMA-IR) was analyzed. Renal pathological changes were studied by immunohistochemical staining and electron microscope. Results After 2 weeks on the high sucrose and fat diets, the model rats exhibited significant increase in basal PGL, TG and CHO levels as compared to control rats (P<0.05, respectively). The insulin resistance was developed in model rats demonstrated by the higher HOMA-IR (5.03±0.38 vs 2.61±0.34, P<0.05). At the end of the experiment, model rats were associated with hypertension. Upro level was significantly increased in model rats compared with that in controls [(57.58±16.54) mg/24 h vs (5.35±1.90) mg/24 h, P<0.01]. The kidney hypertrophy index (KWI) was significantly increased in the model rats compared to controls (P <0.05). Moreover, the diabetic model rats showed glomerular hypertrophy, foot process effacement, micro villous transformation, glomerular basement membrane (GBM) thickening. Conclusion A rat model is successfully established, which presents typical features of human type 2 diabetes and can be served as an ideal model to study the diabetic nephropathy.

AIM: To investigate the change of connective tissue growth factor(CTGF) expression and its role in streptozotocin-induced diabetic rat kidney. METHODS: Male SD rats were randomly divided into two groups: control(sham operated rats, group C,n=32) and diabetic rats (group DN,n=35). Rats in each group were sacrificed at 1, 2, 4, and 8 weeks respectively after induction of diabetes. Body weight(BW), blood glucose(BG), 24-hour urine volumn(UV), kidney weight, KW/BW,24-hour urinary albumin excretion (24Ualb), creatinine clearance (Ccr), kidney weight (KW), KW/BW, glomerular area (AG), proximal tubular area (AT) and the width of GBM、TBM at each time point were measured. Expression of CTGF and ?-SMA were detected by immunostaining. RESULTS: There was a significant increase of 24 h Ualb, Ccr, KW/BW, AG, VG and the expression of CTGF in glomeruli and tubuli from week 1 onward in diabetic rats compared with those in group C (P

AIM: To investigate the influence of irbesartan (Irb), a new angiotensin II receptor 1 antagonist, on renal hypertrophy in streptozotocin (STZ)-induced diabetic rats. METHODS: Sprague-Dawley (SD) rats were randomly divided into three groups: normal group (Group N, n=7), diabetic group (Group DN, n=6) and irbesartan treated group (Group DNI, n=7). In the experimental group, after the rats subjected to uninephrectomy, STZ was given by peritoneally injection at bolus dose of 50 mg/kg to induce diabetes. Blood glucose (BG), body weight (BW), urinary albumin excretion (Ualb), 24 hour proteinuria (24 h Upro) were measured at week 4, 8, 12, respectively. By the end of experiment at week 12, creatinine clearance (Ccr), kidney weight (KW), indicator of renal hypertrophy (KW/BW), renal total protein content (RTP), glomerular area (AG) and glomerular volume (VG) as well as glomerular basement membrane (GBM) were determined by semi-quantitative pathology technique. RESULTS: It was showed that there was no significant difference in BG between group DN and DNI, while Irb significantly reduced the increasing of Ualb, 24 h Upro in diabetic rats compared to control group (P

Objective To explore the effect of irbesartan on cardiac endothelial-mesenchymal transition (EndMT) in diabetic rats.Methods The model of diabetic rat was induced by intraperitoneal injection with streptozotocin (STZ,35 mg/kg) in spontaneous hypertensive rats (SHR).Diabetic rats were divided into diabetic group and the Irbesartan treated group.The pathological changes were investigated by fluorescence microscope and electron microscope.The EndMT was studied in human aortic endothelial cells (HAEC) exposure to high glucose.The concentration of angiotensin Ⅱ in the supernatant was detected by radioimmunoassay.Immunofluorescence staining was performed to detect the co-localization of CD31 and FSP1.Results The significant myocardial fibrosis was presented in the diabetic group.Endothelial protrusions were prominent feature in myocardial microvascular of diabetic rat compared with the control group rats.Double staining of HAEC showed co-localization of CD31 and FSP1,which was decreased by the treatment of Irbesartan (P ＜ 0.05).When HAEC was exposed to high glucose,it showed some cells acquired spindle-shaped morphology and lost CD31 staining,and FSP1 and α-SMA protein expression levels were markedly upregulated,which attenuated by the treatment of Irbesartan.Conclusion Irbesartan might prevent diabetes from myocardial fibrosis via inhibition of EndMT in diabetic rats.

Objective To investigate the effects of low density lipoprotein receptor (LDLr) pathway on podocyte injury in diabetic nephropathy (DN) under inflammatory stress.Methods Male db/db mice and db/m mice were randomly divided into four groups (8 mice in each group):db/m group (control),casein injected db/m group (db/m + casein),db/db group (db/db),and casein injected db/db group (db/db + casein).An inflamed model of DN was established according to our previous study.24-hour urinary protein was measured every week.The plasma lipid profile was detected by clinical biochemistry assay.Podocyte changes were evaluated by electron microscope and immunofluorescent staining.Lipid accumulation in the kidney was evaluated by oil red O staining and intracellular cholesterol quantitative assay.The protein expression of Wilm's tumor-1 (WT-1),nephrin,α-smooth muscle actin (t-SMA),and molecules correlated with LDLr pathway were examined by immunohistochemical staining or Western blotting.The colocalized protein expression of LDLr with WT-1 was examined by immunofluorescent staining and laser confocal microscopy.Results There were no differences in plasma levels of LDL and HDL among four groups.Compared with db/db group,the db/db+ casein group showed markedly increased 24-hour urinary protein,more significant podocyte foot process effacement and podocyte damage,increased lipid droplet accumulation in kidneys,increased protein expressions of LDLr,SCAP and SREBP-2 in kidneys (all P ＜ 0.05).Interestingly,increased LDLr protein expression in kidneys of db/db mice was negatively correlated with decreased nephrin protein expression (r =-0.855,P ＜ 0.01) and positively correlated with increased α-SMA protein expression (r=0.768,P ＜ 0.01).Conclusions The disruption of LDLr pathway induced by inflammation contributes to podocyte injuries in diabetic nephropathy.