Effect of angiotensin-(1-7) on angiotensin II-induced rat renal interstitial fibroblast activation

AIM: To explore the influence of angiotensin-(1-7) on angiotension II (Ang II)-induced activation and extracellular matrix secretion in rat renal interstitial fibroblasts (NRK-49F cells). METHODS: The NRK-49F cells were maintained and sub-cultured, then the cells were divided into control group, Ang II group, Ang-(1-7) group and Ang II+Ang-(1-7) group. The expression of α-smooth muscle actin(α-SMA),transforming growth factor β₁ (TGF-β₁) and insulin-like growth factor I(IGF-I) was detected by the method of immunocytochemistry when the cells were cultured for 72 h. The content of TGF-β₁, IGF-I and collagen type I(Col I) in the cultured supernatants were measured by ELISA. RESULTS: In control group and Ang-(1-7) group, only basic expression of α-SMA and almost no expression of TGF-β₁, IGF-I and Col I were observed. Compared with control group, the expression of α-SMA, TGF-β₁, IGF-I and Col I was increased in Ang II group. Compared with Ang II group, the expression of α-SMA, TGF-β₁, IGF-I and Col I was significantly decreased in Ang II+Ang-(1-7) group.CONCLUSION: Ang-(1-7) inhibits the activation of renal interstitial fibroblasts and decreases the Ang II induced secretion of Col I by suppressing TGF-β₁ and IGF-I expression.     

Effect of all-trans-retinoic acid on the proliferation and expression of α-SMA in human embryonic lung fibroblasts

AIM: To investigate the effects of all-trans-retinoic acid (ATRA) on the proliferation and differentiation of transforming growth factor β₁(TGF-β₁)-stimulated human embryonic lung fibroblasts (HFL-I).METHODS: The HFL-I cells were cultured in vitro and were pretreated with ATRA for 3 days at the concentrations of 0.1 μmol/L, 1 μmol/L and 10 μmol/L. The proliferation of HFL-1 cells was detected by MTT method. The mRNA expression of α-smooth muscle actin(α-SMA) in HFL-I cells stimulated with TGF-β₁ for 0 h, 6 h, 12 h, 24 h, 48 h and 72 h was detected by RT-PCR and the protein expression of α-SMA at the time points of 1,3 and 5 days was detected by Western blotting. The mRNA expression of α-SMA in HFL-I cells pretreated with different concentrations of ATRA for 24 h was detected the by RT-PCR and the protein expression at time point of 3rd day was detected by Western blotting. RESULTS: Different concentration of ATRA inhibited the proliferation of HFL-I in a dose-dependent manner (P<0.05). Both mRNA and protein expression of α-SMA in HFL-I cells pretreated with TGF-β₁ was up-regulated (P<0.05). ATRA down-regulated the mRNA and protein expression of α-SMA induced by TGF-β₁ in a dose-dependent manner (P<0.05). CONCLUSION: ATRA inhibits the proliferation and TGF-β₁-stimulated differentiation in HFL-I cells by down-regulating the mRNA and protein expression of α-SMA.     

Effect of salvianolic acid B on high glucose-induced phenotypic transition and extracellular matrix secretion in human glomerular mesangial cells

AIM:To investigate the effect of salvianolic acid B (Sal B) on high glucose-induced phenotypic transition and extracellular matrix (ECM) secretion in human glomerular mesangial cells (HGMCs) and the underlying mechanisms. METHODS:HGMCs were randomly divided into control group, high glucose group and high glucose plus high dose, medium dose and low dose of Sal B groups. The HGMCs except those in control group were exposed to high glucose (33.3 mmol/L) for 72 h, while those in Sal B groups were co-incubated with indicated concentrations of Sal B. The protein levels of α-smooth muscle actin (α-SMA), transforming growth factor-β₁ (TGF-β₁) and phosphorylated Smad2 and p38 mitogen-activated protein kinase (MAPK) were determined by Western blot. The secretion levels of collagen type I (Col I), collagen type Ⅲ (Col Ⅲ), fibronectin (FN) and laminin (LN) were measured by ELISA. RESULTS:Exposure to high glucose markedly increased the protein expression of α-SMA, TGF-β₁, Col I, Col Ⅲ, FN and LN in the HGMCs (P<0.01). The phosphorylation levels of Smad2 and p38 MAPK were also significantly increased (P<0.01). Co-incubation with Sal B evidently decreased the protein expression of α-SMA, TGF-β₁, Col I, Col Ⅲ, FN and LN in the HGMCs induced by high glucose (P<0.05 or P<0.01). The phosphorylated levels of Smad2 and p38 MAPK were also reduced noticeably (P<0.05 or P<0.01). CONCLUSION:Sal B significantly suppresses high glucose-induced phenotypic transition and ECM secretion in the HGMCs, which might be attributed, at least partly, to inhibition of TGF-β₁/Smad signaling pathway and p38 MAPK activation.     

Dynamical observation of the expression of TGF-β1 and MAPK1/3 in the renal tubules of rats with diabetes

AIM: To observe the expression of transforming growth factor β₁ (TGF-β₁), MAPK_1/3 and fibronectin (FN) in the development of renal tubulointerstitial disease. METHODS: Wistar male rats were randomly divided into normal control group, diabetic group of 1week, 2 weeks, 4 weeks and 8 weeks. Diabetic model was induced by peritoneal injection of streptozotocin. Immunohistochemistry was employed to detect the expression of TGF-β₁, MAPK_1/3 and FN in the kidney. TGF-β₁ protein in the renal cortex was checked by Western blot. BG, Scr and UP were analysed by biochemical methods, and the morphological changes in renal tubulointerstitium were also examined under microscopy on sections stained with HE and PAS. RESULTS: The expression of MAPK_1/3 and FN was observed, but not the expression of TGF-β₁ in normal renal tissue. Positive staining of TGF-β₁ was observed in the renal tubulo-interstitium in 1-week diabetic group and thereafter it increased in the course of diabetes. A continuous increase in the expression of MAPK_1/3 and FN was also observed in two - week diabetic rats. Chronologically the expression of TGF-β₁,MAPK_1/3 and FN and the ratio of KW/BW were positively correlative with each other in diabetic animals except one -week diabetic rats. There was also a positive correlation between MAPK_1/3 and FN in l -week diabetic rats. CONCLUSION: Our data suggest that TGF-β₁ appears in the renal tubulointerstitium in early period of diabetes and then its signal is mediated by MAPK_1/3 cascades to accelerate production of FN ,and in turn leads to renal hypertrophy and tubulointerstitial fibrosis.     

Roles of gap junction in TGF-β1-induced proliferation of vascular smooth muscle cells from spontaneous hypertensive rats

AIM: To investigate whether gap junction participates in transforming growth factor β₁(TGF-β₁)-induced proliferation of spontaneous hypertensive rat (SHR) vascular smooth muscle cells (VSMCs). METHODS: The thoracic aorta of the rats were sampled. The primary SHR VSMCs were isolated and cultured in vitro. The cells were divided into 4 groups: control group, TGF-β₁ group,18α-glycyrrhetinic acid(18α-GA) group and TGF-β₁+18α-GA group. The proliferation of SHR VSMCs was observed by the methods of MTT and flow cytometry. The protein expression and co-localization of connexin(Cx)43 and Cx40 in SHR VSMCs were detected by immunofluorescence staining. The protein levels of Cx43 and Cx40 in the cells were also measured by Western blotting. The method of molecular dye transfer (scrape dye transfer method) was applied to detect the function of gap junction in SHR VSMCs. RESULTS: The protein expression of Cx43 and Cx40 in SHR VSMCs was positive and co-localized in the cytoplasm. Compared with control group, the percentage of S-phase detected by cell cycle and A value detected by MTT in TGF-β₁ group were obviously increased (P<0.05), indicating that the proliferation of the cells was enhanced. However, the proliferation of the cells decreased in 18α-GA group (P<0.05). Compared with TGF-β₁ group, the percentage of S-phase and A value in TGF-β₁+18α-GA group were both significantly decreased (P<0.05), indicating that the proliferation of the cells decreased. Compared with control group, the protein expression of Cx43 in TGF-β₁ group was increased (P<0.05), whereas the protein expression of Cx40 was not changed (P>0.05), and the protein expression of Cx43 and Cx40 in 18α-GA group were decreased (P<0.05). Compared with TGF-β₁ group, the expression of Cx43 in TGF-β₁+18α-GA group was significantly decreased (P<0.05),but no difference of the Cx40 protein levels between the two groups was observed. Compared with control group, the function of gap junction detected by scrape dye transfer method in TGF-β₁ group was enhanced (P<0.05), and weakened in 18α-GA group (P<0.05). Compared with the TGF-β₁ group, the function of gap junction in TGF-β₁+18α-GA group was significantly attenuated (P<0.05). CONCLUSION: TGF-β₁ enhances the function of gap junction to stimulate the proliferation of SHR VSMCs through the expression of Cx43 protein. The expression of Cx40 protein may not play a major role in this process.     

Blockage of core fucosylation contributes to inhibition of epithelial mesenchymal transition of renal tubular epithelial cells

AIM: To investigate the role of inhibiting core fucosylation in the process of epithelial mesenchymal transition (EMT) in HK-2 cells.METHODS: An EMT cell model with transforming growth factor-β₁(TGF-β₁) was established and RNAi technique was used to silence the expression of α-1,6-fucosyltransferase ( FUT8) gene which is responsible to catalysation of core fucose. The morphological changes of HK-2 cells were observed under light microscope. The epithelial cell marker E-cadherin and fibrotic cell markers N-cadherin, fibroblast-specific protein-1(FSP-1) and α-smooth muscle actin(α-SMA) were detected by Western blotting and immunocytochemistry. The apoptosis induced by TGF-β₁ was determined by flow cytometry. RESULTS: After incubated with TGF-β₁ at the concentration of 5 μg/L for 48 h, HK-2 cells lost epithelial morphology and showed fibrotic morphology. The expression of α-SMA, FSP-1 and N-cadherin was markedly increased, while E-cadherin was decreased. Meanwhile, the expression of FUT8 was up-regulated, and the apoptosis of the cells increased. However, pre-incubation of the cells with FUT8 siRNA inhibited these changes above.CONCLUSION: The core fucosylation involves in the process of EMT in HK-2 cells. Blockage of core fucosylation results in the inhibition of EMT in HK-2 cells.     

Ginsenoside Rh1 attenuates unilateral ureteral obstruction-induced renal interstitial fibrosis in rats

AIM:To observe the effects of ginsenoside Rh1 (G-Rh1) on unilateral ureteral obstruction (UUO)-induced renal interstitial fibrosis and to investigate the underlying mechanisms. METHODS:Male Sprague-Dawley (SD) rats (n=40) were divided into the following 4 groups:UUO-operated group (UUO group), sham-operated group (sham group), UUO-operated plus a low dose (50 mg·kg^-1·d^-1) of G-Rh1 treatment (low G-Rh1 group) and UUO-operated plus a high dose (100 mg·kg^-1·d^-1) of G-Rh1 treatment group (high G-Rh1 group). The G-Rh1 treatment was carried out by gastric gavage from the next day after the UUO operation once a day for 2 weeks (14 d). Immediately after the final dose of G-Rh1, 24 h urine was collected for the urine protein test, and then the rats were euthanized. The blood was collected for the blood urea nitrogen (BUN) and serum creatinine (SCr) assays, and the kidney was removed for pathological and biochemical evaluations. RESULTS:The levels of 24 h urine protein did not show any significant diffe-rence among the groups, while significantly increased levels of BUN and SCr in UUO group were observed (P<0.05), which was prevented by the treatment with G-Rh1 at both doses in a dose-dependent manner. Pathological evaluation showed the renal tissue damage was obvious in UUO group, which was improved by the treatment with G-Rh1 at both doses. Immunohistochemcial analysis exhibited that UUO increased renal interstitial transforming growth factor-β₁ (TGF-β₁) expression, which was also inhibited by the treatment with G-Rh1 at both doses(P<0.05). Significantly increased protein expression of renal interstitial collagen type I, α-smooth muscle actin (α-SMA) and connective tissue growth factor (CTGF) in UUO group was detected, which was suppressed by the treatment with G-Rh1 at both doses. CONCLUSION:G-Rh1 improves UUO-induced renal dysfunction and attenuates interstitial fibrosis, which is mediated via modulation of TGF-β₁-related pro-fibrogenic signaling pathway.     

Protective effects of luteolin on STZ-induced diabetic kidneys

AIM: To explore the protective effects of luteolin on the diabetic kidneys. METHODS: Male Sprague-Dawley rats were randomly divided into 5 groups: normal control group, diabetic model group and the groups of diabetic rats treated with luteolin at a low dose, a middle dose and a high dose. The diabetic model was induced by a single intraperitoneal injection of streptozotocin (STZ,65 mg/kg). Blood glucose, urine protein, the activity of superoxide dismutase and catalase in serum and kidney, and the content of malonaldehyde(MDA) in kidney were analyzed by biochemical methods. Western blotting was used to detect the protein expression of transforming growth factor-β₁(TGF-β₁) and plasminogen activator inhibitor-1(PAI-1) in the renal cortex. The morphological changes of the renal tissues were observed under microscope. RESULTS: Compared with diabetic model group, luteolin significantly reduced the level of blood glucose (P<0.01), the content of urine protein (P<0.01) and MDA (P<0.01) in the kidneys, and increased the activity of superoxide dismutase and catalase (P<0.01) in serum and kidneys in the diabetic rats. The protein levels of TGF-β₁ and PAI-1 in the renal cortex were dramatically decreased as the rats were treated with luteolin. CONCLUSION: Luteolin may exert an important protective effect on diabetic kidneys by relieving oxidative stress and inhibiting the protein expression of TGF-β₁ and PAI-1 in the renal tissues of STZ-induced diabetic rats.     

Inhibitory effect of metformin on alveolar epithelial-mesenchymal transition in lung tissue of rats with pulmonary fibrosis

AIM: To study the inhibitory effect of metformin on alveolar epithelial-mesenchymal transition (EMT) in rats with pulmonary fibrosis and the possible mechanism. METHODS: SD rats (n=48) were used, 12 of which were set up as normal control group, and 36 of which were induced by bleomycin (5 mg/kg) by tracheal instillation to establish pulmonary fibrosis. The pulmonary fibrosis rats were randomly divided into bleomycin group, low dose (100 mg/kg) of metformin group, and high dose (300 mg/kg) of metformin group. The rats in metformin groups were given the corresponding dose of metformin daily for 4 weeks. HE staining and Masson staining were used to observe the changes of lung histopathology and collagen deposition. Real-time PCR, Western blot and innunohistochemical staining were used to detect the mRNA and protein expression of α-smooth muscle actin (α-SMA), E-cadherin, vimentin, zonula occludens-1 (ZO-1), collagen I, collagen III and transforming growth factor-β₁ (TGF-β₁), and the protein phosphorylation levels of Smad2/3 and extracellular signal-regulated kinase 1/2 (ERK1/2) were also determined. RESULTS: Metformin up-regulated the expression of E-cadherin and ZO-1, down-regulated the expression of α-SMA, vimentin, collagen I and collagen III, and the protein phosphorylation levels of Smad2/3 and ERK1/2 were also decreased (P<0.05). CONCLUSION: Metformin inhibits alveolar EMT in the rats with pulmonary fibrosis, and its mechanism may be related to the inhibition of TGF-β₁ signal transduction pathway.     

Role of EndoMT in HHPH based on TGF-β/Smads signaling pathway and regulated by Yiqi-Wenyang-Huoxue-Huatan formula

AIM: To investigate the relationship between transforming growth factor-β (TGF-β)/Smads signaling pathway and pulmonary arterial endothelial-mesenchymal transition (EndoMT) in hypoxia-hypercapnia pulmonary hypertension (HHPH) process and the regulatory effect of Yiqi-Wenyang-Huoxue-Huatan formula (YWHHF). METHODS: Healthy male SD rats were randomly divided into 5 groups:normal control (N) group, hypoxia-hypercapnia (HH) group, high-dose YWHHF (YH) group, middle-dose YWHHF (YM) group and low-dose YWHHF (YL) group. The rats in N group was housed in normoxic environment, and the rats in the other 4 groups were housed in hypoxia-hypercapnia environment (9%~11% O₂ and 5%~6% CO₂) for 4 weeks, 8 h/d, 6 d/week. The excess water vapor was absorbed by anhydrous CaCl₂, and CO₂ was absorbed by sodium hydroxide. The rats in YWHHF groups were put into the oxygen chamber before the same volume of YWHHF at different concentrations were given (200 g/L for YH group, 100 g/L for YM group and 50 g/L for YL group). The average pulmonary artery pressure and the average carotid artery pressure were measured during the operation. After operation, the right ventricular free wall and left ventricle plus interventricular septum were collected for determining the right ventricular hypertrophy index. Moreover, the morphological changes of the lung tissues were observed under light microscope. The mRNA and protein levels of α-smooth muscle actin (α-SMA), CD31, TGF-β1 and Smad2/3, and the protein level of p-Smad2/3 were detected by RT-PCR and Western blot. RESULTS: Compared with N group, the pulmonary artery mean pressure, the mRNA and protein expression of α-SMA, TGF-β1 and Smad2/3, and the protein level of p-Smad2/3 were increased, the levels of CD31 were decreased (P<0.05), and the lung tissue damage was observed in the other 4 groups. Compared with HH group, the pulmonary artery mean pressure, the mRNA and protein expression of α-SMA, TGF-β1 and Smad2/3, and the protein level of p-Smad2/3 were decreased, while the mRNA and protein levels of CD31 were increased. Moreover, the lung tissue damage was reduced in YH, YM and YL groups. CONCLUSION: TGF-β/Smads pathway may be involved in the process of EndoMT under hypoxia and hypercapnia condition, and YWHHF may reduce EndoMT by inhibiting the expression of TGF-β/Smads pathway-related molecules.     

Protectin D1 inhibits renal fibrosis in early-stage diabetic nephropathy mice by inhibiting renal inflammation and podocyte epithelial-mesenchymal transition

AIM:To study the effect of protectin D1 (PD1) as a potent anti-inflammatory lipid mediator on diabetic nephropathy (DN). METHODS:PD1 (0.08 mg·kg-1·d-1) was intraperitoneally injected into the mice for 8 weeks after diabetes was induced by injection of streptozotocin. The 24-h urinary protein and albumin levels, body weight, renal weight, kidney-to-body weight ratio, creatinine clearance, glomerular mesangial matrix accumulation, renal cortical macrophage accumulation, and glomerular expression of fibronectin (FN), α-smooth muscle actin (α-SMA), zonula occludens-1 (ZO-1) and P-cadherin were detected. Thfe effect of PD1 on inhibiting epithelial-mesenchymal transition (EMT) in the podocytes induced by transforming growth factor β1 (TGF-β1), and the effect of PD1 on inhibiting the inflammatory effect of macrophages induced by high glucose were determined. RESULTS:PD1 markedly suppressed diabetes-induced elevation of 24-h urinary protein and albumin levels, body weight, renal weight, kidney-to-body weight ratio, creatinine clearance, glomerular mesangial matrix accumulation, and glomerular expression of FN and α-SMA. PD1 also suppressed diabetes-induced increase in the number of renal cortical macrophages in the mice with DN. Analysis by Western blotting and immunohistochemistry revealed that PD1 suppressed diabetes-induced elevation of mesenchymal/fibrotic markers FN and α-SMA, and increased podocyte-related epithelial markers ZO-1 and P-cadherin in the glomeruli of the mice with DN. PD1 repressed high glucose-induced generation of tumor necrosis factor α and interleukin 1β by macrophages, and inhibited TGF-β1-induced increases in fibroblast-specific protein 1 and α-SMA, and inhibited TGF-β1-induced decreases in epithelial markers P-cadherin and ZO-1 in podocytes in vitro. CONCLUSION: PD1 inhibits renal fibrosis in the early stage of DN, and its mechanisms may be related to its anti-inflammatory and anti-EMT effects on podocytes.     

Effect of blood glucose control on expression of Smad7 and renal fibrosis in diabetic rats

AIM： To verify the hypothesis that treatment with insulin to control the blood glucose (BG) may relieve or slow down the development of diabetic nephropathy (DN) in diabetic rats by increasing the expression of Smad7. METHODS：The diabetic rat model was established by tail-vein injection of streptozotocin. Sixteen rats were divided into 2 groups. Eight of these animals in diabetes mellitus (DM) group had no treatment. The remaining eight of them in insulin treatment (INS) group were injected with insulin. After 13 weeks, the rats in INS group were given individual treatment with insulin to let the blood glucose level keep within 4 to 7 mmol/L. Meanwhile, 8 rats were used for normal control (NC group). After 16 weeks, the rats were sacrificed to detect the relevant biochemical parameters, and to observe the histophathological changes of the kidney and pancreas. In addition, immunohistochemical staining and Western blotting were employed to detect the protein expression of transforming growth factor β1 (TGF-β1), Smad ubiquitin regulatory factor 2 (Smurf2), Smad7, E-cadherin, α-sooth muscle actin (α-SMA), fibronectin (FN) and collagen I. RESULTS：Compared with NC group, the body weight was significantly reduced in DM group, whereas the body weight in INS group increased gradually. Compared with NC group, the levels of 24 h urine protein (24 h UP), BG and triglyceride (TG) were remarkably increased in DM group. Pathological detection on pancreas indicated that the islet was destroyed. The levels of TGF-β1, Smurf2, α-SMA, FN and collagenⅠ in the kidneys were increased in DM group, and the expression of Smad7 and E-cadherin, which were mainly located in renal tubular epithelial cells, was significantly reduced. Compared with DM group, the levels of 24 h UP and BG were significantly reduced in INS group, and the alleviated renal fibrosis was observed under light microscope. In addition, the protein levels of TGF-β1, Smurf2, α-SMA, FN and collagenⅠ in INS group were decreased compared with DM group, and the expression of Smad7 and E-cadherin was increased significantly. CONCLUSION：Target glucose control with insulin treatment restores the protein expression of Smad7 in the kidney of diabetic rats, reduces the accumulation of extracellular matrix and slows down DN progress. The decrease in TGF-β1 and Smurf2 expression, and the attenuation of Smad7 ubiquitination in renal tissues are the crucial parts in this process.     

Localization and expression of TGF-β1,2 in fetal and adult skins

AIM:To explore the localization and expression of transforming growth factor-β_1,2 (TGF-β_1,2) and alpha-smooth muscle actin (α-ASMA) in fetal and adult skins. METHODS:Skins of 15 cases of fetuses with different gestational ages and 5 cases of adults were taken, embedded with paraffin wax, and sectioned. Immunohistochemistry method and pathological method were used to detect the expression intensity and distribution of TGF-β_1,2 and α-ASMA. RESULTS: Positive immunohistochemical signals of TGF-β_{1, 2} and α-ASMA were found in fetal and adult skins. In skins derived from young fetus, the positive signals of these three proteins were very weak. Along with the increment in gestational age, the positive cellular rates of TGF-β_1,2M and α-ASMA were elevated progressively. In elder fetal and adult skins, TGF-β_1,2 were mostly distributed in epidermal cells, endothelial cells and some fibroblasts, while α-ASMA was mainly located in myofibroblasts and sweat gland epithelial cells. CONCLUSION:The endogenous TGF-β_1,2might be involved in the cutaneous development at embryonic stage, in the cutaneous structure maintenance at adult stage, and in the wound healing after injury.     

Brain damage of cerebral ischemia/reperfusion and expression of TGF-β1 mRNA in diabetic rats

AIM:To observe the difference of cerebral inj ury following ischemia/reperfusion and mR-NA expression of TGF-β₁ between diabetic and non-diabetic rats.METHODS:At first,Wistar rats weredivided i nto two groups,non-diabetes and diabetes,and then two groups followed by sham,middle cerebralartery occlusion(MCAO) 2h and reperfusion 24 h after MCAO 2 h respectively.TGF-β₁ mRNA expressionwas measured by semi-quantitative reverse transcri ption polymerase chain reaction(RT-PCR);Cerebraldamage was eval uated by histopathology.RESULTS:In the same condition of ischemia or ischemia/reperfu-sion,inj uried area enlarged in DMgroups;The expressionlevel of TGF-β₁ mRNA increased at the ti me of 2h after MCAOi n non-diabetic group and diabetic group,especialy significantly in non-diabetic group withMCAO 2 h,and decreased at the time of reperfusion 24 h after MCAO 2 h,but still higher than that in theshamgroup.CONCLUSION:Diabetes mellitus exacerbated brain lesion following ischemia/repefusion,in-creased TGF-β₁ mRNA expresion after MCAO may be an anti-injury reaction,and anti-injury abilityis de-creased under diabetic condition.     

TAK1 regulates fibrosis of renal tubular epithelial cells by regulating p38 MAPK signaling pathway

AIM:To investigate the effect of transforming growth factor-β (TGF-β) activated kinase 1(TAK1) on renal tubular epithelial fibrosis. METHODS:The renal tubular epithelial cell line HK-2 was used as the research object. After induced by TGF-β1, real-time PCR and Western blot were used to detect the expression of TAK1 in the HK-2 cells. TAK1 shRNA lentivirus was used to infect HK-2 cells, real-time PCR and Western blot were used to determine the interference effect on TAK1 expression in the HK-2 cells with TGF-β1 stimulation. Under the condition of treating with p38 MAPK activator anisomycin, the levels of type I collagen and type Ⅲ collagen in the supernatant, and the protein levels of α-smooth muscle actin (α-SMA), connective tissue growth factor (CTGF) and p-p38MAPK^{Thr 180/Tyr 182} in the HK-2 cells with TAK1 knock-down were determined by ELISA and Western blot, respectively. RESULTS:TGF-β1 significantly increased the expression of TAK1 in the HK-2 cells(P<0.05). TAK1 shRNA significantly decreased the expression of TAK1 in the HK-2 cells with TGF-β1 stimulation. Type I collagen and type Ⅲ collagen secreted by the HK-2 cells after treatment with TGF-β1 were increased, the protein levels of α-SMA, CTGF and p-p38MAPK^{Thr 180/Tyr 182} were also increased(P<0.05). Knock-down of TAK1 expression significantly inhibited the secretion of type I and type Ⅲ collagen, reduced the protein levels of α-SMA, CTGF and p-p38MAPK^{Thr 180/Tyr 182} in the TGF-β1-induced HK-2 cells(P<0.05). Treatment with p38 MAPK activator reversed the inhibitory effect of TAK1 knock-down on the secretion of type I and type Ⅲ collagens, and the protein levels of α-SMA, CTGF and p-p38 MAPK^{Thr 180/Tyr 182} in the HK-2 cells(P<0.05). CONCLUSION:Knock-down of TAK1 expression attenuates the TGF-β1 induced fibrosis of renal tubular epithelial cells by inhibiting p38 MAPK signaling pathway.     

Therapeutic effects of losartan and astragalus membranaceus on diabetic nephropathy

AIM: To observe the protective effects of losartan and astragalus membranace on the kidney of diabetic rats, and to study their possible mechanisms. METHODS: The diabetic rats were induced by a single intraperitoneal injection of streptozotocin. At the end of 12th week,changes in urinary albumin excretion, urinary β₂-MG excretion, Ccr,NO,ET-1 levels in blood, urinary and renal tissue were observed. Serum and urinary TGF-β₁ concentration,average volume of glomeruler,average thickness of glomerular basement membrane were also measured. RESULTS: In the treated diabetic rats, urinary albumin excretion, urinary β₂-MG excretion, Ccr, urinary and renal tissue NO, urinary TGF-β₁, average volume of glomeruler, average thickness of glomerular basement membrane decreased obviously as compared with diabetic untreated rats. These effects were enhanced when losartan was combined with astragalus membranace. CONCLUSION: Losartan or astragalus membranace reversed the injury of renal structure and function in STZ-induced diabetic rats. The protective effects were enhanced when losartan was combined with astragalus membranace. The decrease in NO,ET,TGF-β₁ concentration in renal tissue may be one of mechanisms for this action.     

Activation of renal tubular epithelial cells by monocytes/macrophages and the relative mechanisms

AIM: To observe the direct effects of peripheral blood monocytes/macrophages (MO/MAC) on renal tubular epithelial cells (RTEC),and further probe into the possible mechanisms. METHODS: Conditioned medium(M-CM) of human peripheral blood MO/MAC was collected and added to HK-2,a human renal proximal tubular cell line.After incubation with M-CM for 24 hours,HK-2 cells were detected for DNA synthesis by [³H]-TdR incorporation,osteopontin (OPN) and α-smooth muscle actin (α-SMA) expression by Western blot,and fibronectin(FN) secretion by ELISA.Furthermore,anti-TGFβ₁ neutralizing antibody and interlukin-10(IL-10) were used separately to antagonize the effects of M-CM on HK-2 cells. RESULTS: ①DNA synthesis,α-SMA expression and FN secretion were all increased in HK-2 cells when incubated with M-CM.②When adding with anti-TGFβ₁ neutralizing antibody (5 mg/L) in the M-CM,the degree of upregulation of α-SMA and FN in HK-2 cells was much lower than that stimulated by M-CM alone.③M-CM added with IL-10 (20 μg/L) had a weaker ability to induce the increasing in α-SMA expression and FN excretion in HK-2 cells, compared with M-CM itself alone.M-CM from MO/MAC preincubated with IL-10 caused a lower upregulation of α-SMA expression in HK-2 cells than M-CM from non-preincubated MO/MAC. CONCLUSION: MO/MAC can directly induce proliferation,transdifferentiation and extracellular matrix secretion in RTEC.TGFβ₁ and proinflammatory cytokines secreted by MO/MAC might be involved in the aboveeffects.     

Effect of puerarin injection on epithelial-mesenchymal transition in renal tubular epithelial cells of diabetic KKAy mice

AIM:To observe the effect of puerarin injection on the expression of epithelial-mesenchymal transition-related proteins in KKAy mice with renal interstitial fibrosis (RIF). METHODS:Sixteen KKAy mice were randomly divided into model group (n=8) and puerarin injection treatment group (n=8), and 8 C57BL/6J mice were used as normal controls. The mice in treatment group were intraperitoneally given puerarin injection from the 14th week. The blood glucose levels were observed on a daily basis. The mice were sacrificed at the 24th week.The renal pathological changes were observed under light microscope. The expression of α-smooth muscle actin (α-SMA), transforming growth factor β1 (TGF-β1) and transforming growth factor β type I receptor (TGF-β-RI) in the renal tissues were examined by immunohistochemical staining. RESULTS:Fibrosis was found in the KKAy mice of model group, while the mice in treatment group showed a slight increase in renal interstitium. Treatment with puerarin injection decreased the protein expression levels of α-SMA, TGF-β1 and TGF-β-RI in the kidney tissues as compared with those in model group. CONCLUSION: Puerarin injection reduces the expression of α-SMA, and restrains the protein expression of TGF-β1 and TGF-β-RI in the kidney tissue of KKAy mice. These changes may inhibit and reverse the process of epithelial-mesenchymal transition, thus delaying the occurrence and development of RIF.     

Inhibitory effect of oxymatrine on high glucose-induced rat renal tubular epithelial-mesenchymal transition

AIM:To investigate the inhibitory effect of oxymatrine (OM) on high glucose-induced rat renal tubular epithelial-mesenchymal transition (EMT). METHODS:The rat renal tubular epithelial NRK52E cells were cultured in vitro. The cells were divided into control group, high glucose group, high glucose+different concentrations of OM groups and high glucose+0.50 g/L OM dynamic observation group. The expression of TGF-β1, Smad7, α-SMA and E-cadherin at mRNA and protein levels was detected by real-time PCR and Western blotting. The viability of NRK52E cells was determined by MTT assay. RESULTS:(1) Compared with control group, the expression of TGF-β1 and α-SMA at mRNA and protein levels in high glucose group gradually increased, and Smad7 protein and E-cadherin mRNA and protein gradually reduced, but the mRNA expression of Smad7 gradually increased. (2) Compared with high glucose group, as increases in OM doses, the expression of TGF-β1 and α-SMA at mRNA and protein levels in high glucose+different concentrations of OM groups gradually reduced, and Smad7 protein and E-cadherin mRNA and protein gradually increased, but the mRNA expression of Smad7 had no significant change. (3) Compared with high glucose group, the expression of TGF-β1 and α-SMA at mRNA and protein levels was significantly reduced, the expression of E-cadherin at mRNA and protein levels significantly increased, and the protein expression of Smad7 significantly increased, but the mRNA expression of Smad7 had no significant change in high glucose+0.50 g/L OM dynamic observation group. CONCLUSION: In NRK52E cells, oxymatrine inhibits high glucose induced EMT by down-regulating TGF-β1 and up-regulating Smad7, thus preventing the fibrosis effect of TGF-β1/Smads signaling.