Interferon-gamma induces macrophage migration inhibitory factor synthesis and secretion by tubular epithelial cells

SUMMARY:   Macrophage migration inhibitory factor (MIF) promotes macrophage accumulation and leucocyte activation during inflammation. Macrophage migration inhibitory factor is upregulated in intrinsic renal cells in many types of kidney diseases, and has a pathogenic role in rat crescentic nephritis. However, little is known about the factors that regulate the production and secretion of MIF in kidney cells. In this study, we evaluated whether interferon-gamma (IFN-γ), a cytokine implicated in the development of kidney disease and a potent inducer of MIF production in macrophages, could promote MIF synthesis and secretion from renal tubular epithelial cells. Northern blot analysis detected constitutive expression of MIF mRNA in rat tubular epithelial cells (NRK52E), which increased twofold after a 6-h stimulation with IFN-γ. Macrophage migration inhibitory factor protein was found only in the cytoplasm of NRK52E cells. Following IFN-γ stimulation, intracellular MIF in NRK52E cells was rapidly secreted with a maximal reduction of 50% after 20 min, which returned to normal levels after 2–4 h. Rapid secretion of MIF in response to IFN-γ was also seen in rat mesangial cells. These findings indicate that IFN-γ induces rapid secretion of MIF by tubular epithelial cells, and suggest that this may be an important mechanism leading to inflammatory cell accumulation and activation during kidney disease.     

Effects of 1,25-dihydroxyvitamin D3 on macrophage chemo taxis inhibitory factor and nuclear factor-κB/P65 in obstructive nephropathy rats

Objective To investigate the expression of macrophage migration inhibitory factor(MIF) and nuclear factor-κB/P65 (NF-κB/P65) in the kidneys of unilateral ureteral occlusion (UUO) model rats and the effect of 1,25-dihydroxyvitamin D3 on the expression. Method The cell model of obstructive nephropathy was established by renal tubular epithelial cells treated with TGF- beta 1. Thirty healthy adult male SD rats were randomly divided into 3 groups: sham operation group (n=10), UUO group (n=10) and 1,25-dihydroxyvitamin D3 group (n=10, UUO rats treated with 1,25-dihydroxyvitamin D3 by lavage 2 days before operation)．The rats in sham group and UUO group were treated with equal normal saline by lavage. Serum creatinine (Scr) and histopathological changes were tested at week 2. The expressions of collagen Ⅳ (ColⅣ), macrophage marker antigen ED-1, MIF and NF-κB/P65 in renal issue were measured by immunohistochemistry. The MIF mRNA was detected by real-time PCR and the protein expressions of MIF, NF-κB inhibitor α (IKBα) and p-IKBα were measured by Western blotting. In renal tubular epithelial cells (NRK52E) the expressions of MIF and NF-κB were detected by immunocytochemistry, and the the protein expression of MIF and the activation of IKBα were teasted by Western blotting. Results Compared with those in sham group, in model group rats had increaced Scr, tubulointerstitial damage area and expressions of ED-1 and ColⅣ, and up-regulated mRNA and protein expressions of MIF (all P＜0.05). Moreover, the amount of NF-κB/P65 nuclear positive cells and p-IKBα expression were significantly increased while the expression of IKBα decreased in model group (all P＜0.05). NRK52E cells had higher expressions of MIF, NF-κB and p-IKBα, and lower IKBα in model group than those in control group (all P＜0.05). After the application of 1,25-dihydroxyvitamin D3, those above effects were inhibited (all P＜0.05). The results of cell model and animal model were in agreement. Conclusions The expressions of MIF and the activation of NF-κB/P65 in UUO rats increased significantly. 1,25-dihydroxyvitamin D3 may ameliorate the progression of renal tubulointerstitial inflammation and renal fibrosis by intervening the expression of MIF, inducing phosphorylation of IKBα and decreasing the activation of NF-κB/P65.     

Osteopontin expression in progressive renal injury in remnant kidney: role of angiotensin II

BACKGROUND: Osteopontin (OPN) is a macrophage chemotactic and adhesion molecule and has been shown to play a role in glomerular and tubulointerstitial injury in several kidney disease models. METHODS: The present study examined whether OPN expression is involved in the progression of renal disease following subtotal (5/6) nephrectomy (STNx) in rats and whether angiotensin II (Ang II) mediates the up-regulation of renal OPN expression and macrophage accumulation in this model by administering valsartan, an Ang II type I (AT1) receptor antagonist, or ramipril, an angiotensin-converting enzyme (ACE) inhibitor. RESULTS: In normal and sham-operated rat kidneys, OPN was expressed in a few tubules (<5%) and was absent in glomeruli. Following STNx (weeks 2 to 16), there was substantial up-regulation of OPN mRNA and protein expression in glomeruli [2 to 12 cells/glomerular cross section (gcs)] and tubular epithelial cells (20 to 75% OPN+). The up-regulation of OPN expression was associated with macrophage accumulation within the kidney, severe proteinuria, loss of renal function, and severe histologic damage, including tubulitis and tubulointerstitial fibrosis (all P < 0.001). Treatment with either valsartan or ramipril completely abrogated the up-regulation of OPN mRNA and protein expression in glomeruli and tubules. The reduction in OPN expression was associated with a significant inhibition of macrophage accumulation and progressive renal injury (P < 0.001). CONCLUSION: An up-regulation of OPN expression may play a role in progressive renal injury following STNx. Inhibition of OPN expression may be one of the mechanisms by which Ang II blockade attenuated renal injury after renal ablation.     

Increased osteopontin expression following renal ablation is attenuated by angiotensin type 1 receptor antagonism.

Osteopontin is an extracellular matrix protein that is upregulated in renal injury. The aim of this study was to explore the renal expression of osteopontin in a model of progressive renal injury following subtotal nephrectomy (STNx) in rats and the effects of angiotensin type1 (AT1) receptor antagonist irbesartan on osteopontin expression. STNx or a sham operation was performed in 8-week-old Sprague-Dawley rats. STNx rats were given either irbesartan (15 mg/g) or no treatment for 12 weeks. Upregulation of osteopontin mRNA expression was observed in injured renal tubules as assessed by in situ hybridization (42 +/- 8 dpm/mm(2) v.s. control 7.7 +/- 0.6 dpm/mm(2), p < 0.01). Increased osteopontin expression was closely related to infiltration of monocytes/macrophages and increased cellular proliferation. Double immunohistochemical staining demonstrated co-existence of proliferating cell nuclear antigen and osteopontin positive staining in individual cells in kidney sections from STNx rats. The increase in osteopontin expression was inhibited by the AT1 receptor antagonist irbesartan (6.9 +/- 1.2 dpm/mm(2)), associated with attenuation of impaired renal function and pathology as well as decreased monocyte/macrophage infiltration and cellular proliferation. These findings suggest that osteopontin is upregulated in STNx rats and is reduced by AT1 receptor antagonism.     

Mediation of inflammatory activation of renal tubular epithelial cells by high mobility group protein box 1 interacting with Toll-like receptor 4

Objective To observe functional changes of renal tubular epithelial cells stimulated by high mobility group protein box 1 (HMGB1) and associated mechanism. Methods Renal tubular epithelial cells (NRK52E) were divided into control group, HMGB1 group and HMGB1+lipopolysaccharide from Rhodobactersphaeroides (LPS RS) group. Toll-like receptor 4 (TLR4) expression was detected by immunofluorescence and Western blotting. Apoptosis rate and cell cycle arrest were identified with flow cytometry. The activation of MAPK signaling pathway and NF-κB were detected by Western blotting. The IL-1, IL-6 and tissue inhibitor of metalloproteinases 2 (TIMP2) mRNA levels were measured by real-time PCR. The secretion levels of IL-1, IL-6 and TIMP2 were measured by protein chips assay. Results TLR4 was expressed by NRK52E cells. Compared with the control group, there were increased cell cycle G1 arrest, MAPK signaling pathway and NF-κB activation in HMGB1 group. Furthermore, IL-1, IL-6 and TIMP2 mRNA levels were increased and IL-1, IL-6 and TIMP2 were secreted by NRK52E when stimulated with HMGB1 (all P＜0.05). However, effects mediated by HMGB1 stimulation could be inhibited by LPS RS (all P＜0.05). Conclusions Inflammatory activation of NRK52E cells can be mediated by the interaction of HMGB1 and TLR4.     

Proapoptotic Fas ligand is expressed by normal kidney tubular epithelium and injured glomeruli

Fas ligand (FasL) is a cell membrane cytokine that can promote apoptosis through activation of Fas receptors. Fas receptor activation induces glomerular cell apoptosis in vivo and participates in tubular cell death during acute renal failure. However, there is little information on the expression of FasL in the kidney. This study reports that FasL mRNA and protein are present in normal mouse and rat kidney. In situ hybridization and immunohistochemistry showed that proximal tubular epithelium is the main site of FasL expression in the normal kidney. In addition, increased total kidney FasL mRNA and de novo FasL protein expression by glomerular cells were observed in two different models of glomerular injury : rat immune-complex proliferative glumerulonephritis and murine lupus nephritis. Both full-length and soluble FasL were increased in the kidneys of the mice with nephritis. Cultured murine proximal tubular epithelial MCT cells and primary cultures of murine tubular epithelial cells expressed FasL mRNA and protein. Tubular epithelium-derived FasL induced apoptosis in Fassensitive lymphoid cell lines but not in Fas-resistant lymphoid cell lines. By contrast, MCT cells grown in the presence of the survival factors of serum were resistant to FasL, and only became partially sensitive to apoptosis induced by high concentrations (100 ng/ml) of FasL upon serum deprivation. However, MCT cells stimulated with inflammatory mediators (tumor necrosis factor-alpha, interferon-gamma, and lipopolysaccharide) increased cell surface Fas expression and were sensitized to apoptosis induced by FasL (FasL 55 +/- 5% versus control 8.3 +/- 4.1% apoptotic cells at 24 h, P < 0.05). Cytokine-primed primary cultures of tubular epithelial cells also acquired sensitivity to FasL-induced apoptosis. These results suggest that FasL expression by intrinsic renal cells may play a role in cell homeostasis in the normal kidney and during renal injury.     

Role of the renin-angiotensin system on the parathyroid hormone-related protein overexpression induced by nephrotoxic acute renal failure in the rat

Parathyroid hormone-related protein (PTHrP), a mitogenic factor for renal cells, is overexpressed in acute renal failure (ARF). Recent data support an association between PTHrP and the renin-angiotensin system in the damaged kidney. The effects of angiotensin II (Ang II) inhibitors (quinapril, enalapril, and/or losartan) on PTHrP and the PTH1 receptor (PTH1R) expression in rats with either folic acid (FA)- or gentamicin-induced ARF were analyzed. The decreased renal function and the PTHrP upregulation and PTH1R downregulation induced by the nephrotoxins were inhibited by the Ang II blockers. In tubuloepithelial cells NRK-52E, the rapid (10 min) increase in PTHrP mRNA by FA, associated with a perinuclear relocalization of Ang II/AT1 receptor, was inhibited by losartan but not candesartan, which traps Ang II receptors at the cell surface. Maximal PTHrP protein overexpression by FA (at 24 to 72 h)-or by exogenous Ang II-was abolished by both Ang II antagonists. PTHrP upregulation by FA was preceded by increased extracellular signal-regulated kinase (ERK) phosphorylation and inhibited by the ERK inhibitor PD098059. FA also activated cAMP response element-binding (CREB) protein, and this was prevented by losartan in these cells. Moreover, PTHrP mRNA overexpression by either FA or Ang II occurred in NRK 52E that were transfected with a CREB construct but not the dominant-negative CREB133 construct. These findings demonstrate that the decreased renal function and PTHrP overexpression in nephrotoxin-damaged kidney depends on renin-angiotensin system. In this setting, intracellular Ang II/AT1 receptor recycling seems to be related to PTHrP induction through ERK and CREB activation in tubuloepithelial cells.     

Enhanced expression of naofen in kidney of streptozotocin-induced diabetic rats: possible correlation to apoptosis of tubular epithelial cells

Background

Hyperglycemia/high glucose may induce apoptosis in diabetic kidney, but the mechanism is not fully understood. Naofen was found as a Shiga toxin (Stx)-2-related protein. Based on renal dysfunction in infection with Stx-producing Escherichia coli and on participation of naofen in apoptosis of human embryonic kidney cells, the present study was undertaken to investigate the mechanism of renal dysfunction in diabetes mellitus with particular reference to naofen.

Methods

In in vivo studies utilizing streptozotocin (STZ)-induced diabetic rats, and also in in vitro cultured rat kidney epithelial (NRK52E) cells, naofen messenger RNA (mRNA) and protein expressions were analyzed. Naofen mRNA location in diabetic kidney was studied by in situ hybridization. Apoptosis was assessed by caspase-3 activity assay.

Results

Rat diabetic kidney showed significant increases in caspase-3 activities and naofen mRNA. Naofen was mainly observed at both proximal and distal urinary tubules. Incubation of NRK52E cells in high glucose medium resulted in elevated naofen mRNA expression, whereas neither interleukin-1, interleukin-6, nor tumor necrosis factor-α elicited such action. Moreover, treatment of NRK52E cells with naofen small interfering RNA (siRNA) inhibited naofen mRNA expression induced by high glucose and blocked the increase in caspase-3 activity.

Conclusions

These data suggest that naofen expression may be upregulated by hyperglycemia, with possible correlation to apoptosis of tubular epithelial cells and thereby to diabetic nephropathy.     

囊泡型H+-ATP酶B亚基在转化生长因子β1致肾小管上皮细胞转分化中的变化及其意义

目的 探讨在转化生长因子（TGF）β1致大鼠肾小管上皮细胞（NRK52E）发生上皮细胞向间质细胞转分化（EMT）过程中囊泡型H+-ATP酶（V-ATPase）B亚基的变化及其可能意义。 方法 NRK52E细胞无血清培养后予TGF-β1（10 μg/L）刺激不同时间（0、6、12、24、48、72 h）,应用实时定量PCR、Western印迹、免疫荧光技术检测?琢平滑肌肌动蛋白（?琢-SMA）、E钙黏素（E-cadherin）、V-ATPase B亚基（B1、B2）mRNA、蛋白表达及分布的变化。 结果 TGF-β1刺激NRK52E细胞48 h后?琢-SMA mRNA及蛋白表达显著上调,E-cadherin mRNA及蛋白表达显著下调,同时V-ATPase B2亚基mRNA及蛋白表达也显著增加（均P < 0.05）。但是B1亚基在细胞内表达很低,刺激后也未见显著变化。免疫荧光也显示V-ATPase B2亚基在细胞内的分布明显增加并向胞膜聚集。 结论 在NRK52E内主要分布的是V-ATPase B2亚基。TGF-β1刺激NRK52E EMT过程中V-ATPase B2亚基表达显著增加,这提示B2亚基可能参与肾小管EMT过程。     

血管紧张素Ⅱ通过抑制AKT/蛋白激酶B磷酸化诱导肾小管上皮细胞凋亡

目的观察血管紧张素Ⅱ(AngⅡ)在诱导肾小管上皮细胞凋亡的信号传导是否有磷脂酰肌醇3激酶(PI3K)-AKT信号系统的参与,及该系统在诱导细胞凋亡中的作用。方法大鼠肾小管上皮细胞株NRK-52E分别与终浓度为0(对照组)、10-9mol/L、10-8mol/L、10-7mol/L、10-5mol/LAngⅡ共培养24h。用流式细胞仪检测细胞凋亡指数,用免疫组化方法检测增殖细胞核抗原(PCNA)的表达。Western印迹检测PI3K及磷酸化AKT和总AKT蛋白表达,AKT的磷酸化水平用473位丝氨酸磷酸化AKT(AKT-ser473)水平与总AKT水平的比值表示。结果随着AngⅡ浓度的增加,10-6mol/LAngⅡ组与对照组相比,凋亡指数显著增加[(22.7±1.41)%比(3.0±0.75)%,P<0.01]。而10-9mol/LAngⅡ组与对照组相比,PCNA指数显著增强[(47.54±2.6)%比(22.63±2.5)%,P<0.01]。与对照组相比,PI3K-p85蛋白的表达随AngⅡ浓度增加表现为先激活后抑制。AKT的磷酸化具有明显的AngⅡ浓度依赖性,随AngⅡ浓度的增加而逐渐受到抑制,并与细胞凋亡指数呈显著负相关(r=-0.90,P<0.01)。结论AngⅡ可以诱导肾小管上皮细胞凋亡并抑制细胞的增殖,可能部分是通过抑制PI3K-AKT信号传导途径实现的。     

Increased expression of monocyte chemoattractant protein-1 (MCP-1) by renal epithelial cells in culture on exposure to calcium oxalate, phosphate and uric acid crystals.

BACKGROUND: During the development of non-infectious kidney stones, crystals form and deposit in the kidneys and become surrounded by monocytes/macrophages (M/M). We have proposed that in response to crystal exposure renal epithelial cells produce chemokines, which attract the M/M to the sites of crystal deposition. We investigated the expression of monocyte chemoattractant protein-1 (MCP-1) mRNA and protein by NRK52E rat renal tubular epithelial cells exposed to calcium oxalate (CaOx), brushite (Br, a calcium phosphate) and uric acid (UA) crystals. METHODS: Confluent cultures of NRK52E cells were exposed to CaOx, Br or UA at a concentration of 250 micro g/ml (66.7 micro g/cm(2)). They were exposed for 1, 3, 6, 12, 24 and 48 h for isolation of mRNA and 24 h for ELISA to determine the secretion of protein into the culture medium. Since cells are known to produce free radicals on exposure to CaOx crystals we also investigated the effect of free radical scavenger catalase on the crystal induced expression of MCP-1 mRNA and protein. RESULTS: Exposure of NRK52E cells to the crystals resulted in increased expression of MCP-1 mRNA and production of the chemoattractant. CaOx crystals were most provocative while UA the least. Treatment with catalase had a negative effect on the increased expression of both MCP-1 mRNA and protein, which indicates the involvement of free radicals in up-regulation of MCP-1 production. CONCLUSION: Exposure to both CaOx and calcium phosphate crystals stimulates increased production of MCP-1. Free radicals appear to be involved in this up-regulation. Results indicate that MCP-1, which is often associated with localized inflammation, may be one of the chemokine mediators associated with the deposition of various urinary crystals in the kidneys during kidney stone formation. Because of the small number of experiments performed here, results must be confirmed by more extensive studies with larger sample size.     

Par-3蛋白在转化生长因子?茁1介导的大鼠肾小管上皮细胞转分化中的作用

目的 观察转化生长因子（TGF)β1诱导的正常大鼠近端肾小管上皮细胞（NRK52E）转分化（EMT）过程中细胞极性蛋白Par-3的表达及上调Par-3蛋白表达对TGF-β1诱导NRK52E细胞转分化进程的影响。 方法 应用TGF-β1 (10 μg/L)刺激NRK52E细胞，采用RT-PCR、Western印迹和免疫荧光方法分别检测E-钙黏蛋白(E-cadherin)、α-平滑肌肌动蛋白（α-SMA）、Par-3 mRNA和蛋白的表达；应用Lipofectmine 2000将pKH3-HA-Par-3质粒瞬时转染NEK52E细胞，采用Western印迹观察上调表达Par-3对上述指标的影响。 结果 TGF-β1刺激后，NRK52E细胞α-SMA蛋白和mRNA水平上调，E-cadherin蛋白和mRNA的表达下调；Par-3蛋白表达呈时间依赖模式下调，72 h TGF-β1刺激组与对照组比较，差异有统计学意义（P < 0.05）。但Par-3 mRNA水平在各时间点差异均无统计学意义（P > 0.05）。脂质体转染外源性质粒pKH3-HA-Par-3上调表达Par-3可显著抑制TGF-β1诱导NRK52E细胞α-SMA蛋白的上调表达；逆转E-cadherin蛋白的下调表达。 结论 在TGF-β1诱导NRK52E细胞转分化进程中细胞极性Par-3蛋白表达下调，基因转染上调表达Par-3可部分减轻EMT的程度，提示Par-3蛋白在TGF-β1诱导的肾小管上皮细胞转分化和肾脏纤维化中可发挥保护性作用。     

Cdc42相关蛋白4通过极性蛋白6参与肾间质纤维化

目的探讨Cdc42相关蛋白4对闭合素表达的影响及与极性蛋白6之间的相互作用。方法体内实验用单侧输尿管结扎术建立小鼠的。肾脏纤维化模型,根据Masson染色观察肾脏纤维化,用免疫组织化学法观察Cdc42相关蛋白4的表达及分布。体外实验用转化生长因子81诱导大鼠近端肾小管上皮细胞向间质细胞转分化。瞬时转染pcDNA4．0／Cdc42相关蛋白4质粒至NRK52E细胞。Westernblot法检测相关蛋白的表达。免疫沉淀法检测Cdc42相关蛋白4与极性蛋白6的相互作用。结果Cdc42相关蛋白4在纤维化的肾组织中表达上调,主要分布于肾小管上皮细胞。高表达Cdc42相关蛋白4与转化生长因子81刺激后的细胞相关蛋白表达量的改变一致,且均存在Cdc42相关蛋白4与极性蛋白6的相互作用。结论Cdc42相关蛋白4可能通过与极性蛋白6相互作用,调节闭合素的表达,参与肾间质纤维化。     

Protective effects of adipose-derived stem cells with phosphodiesterase 5 inhibition by lentivirus-mediated stable gene silencing on ischemia-reperfusion injury of renal tubular epithelial cells

Objective To explore the protective effects of adipose-derived stem cells (ADSCs) with phosphodiesterase 5 inhibition by lentivirus-mediated stable gene silencing on the proliferation and apoptosis of renal tubular epithelial cells induced by ischemia-reperfusion injury in vitro. Methods To isolate cultivate and indentify ADSCs from rats. Lentiviral expression vector of carrying PDE5 shRNA gene was transfected into ADSCs, and a negative control group was set up．Western blotting was used to detect PDE5 protein expression levels. ADSCs were co-cultured with NRK-52E in a transwell system, and NRK-52E cells were treated with ischemia/reoxygenation protocol. Edu assay was performed to evaluate the proliferation of NRK cells, flow cytometry to detect the apoptosis of NRK cells, and ELISA to quantify the protein expressions of fibroblast growth factor (FGF) and hepatocyte growth factor (HGF). The expression of E-cadherin and cytokeratin 18 (CK18) was quantified by real time PCR and flow cytometry. Results Western blotting for PDE5 protein indicated a significant reduction of PDE5 protein levels in PDE5 shRNA transduced population. After the treatment of ischemia/reoxygenation in vitro, the proliferative viability and apoptosis of NRK-52E cells co-cultured with ADSCs induced by PDE5 gene inhibition were significantly improved, compared to the normal group (all P＜0.05). And the release of HGF, FGF were markedly enhanced (all P＜0.05). Moreover, the NRK-52E cells survival, the expression of E-cadherin and CK18 on PDE5 inhibited ADSCs co-cultured with I/R injured NRK cells was significantly increased compared to that in the negative control group (all P＜0.05). Conclusion ADSCs preconditioned by inhibition of PDE5 can be a powerful novel approach to improve the survival of renal tubular cells following ischemia-reperfusion injury, and have an obvious tendency to transform epithelial cells.     

血管内皮生长因子C对大鼠近端肾小管上皮细胞凋亡的保护作用

目的 探讨肿瘤坏死因子α（TNF-α）对肾小管上皮细胞生成血管内皮生长因子C（ VEGF-C）的影响,及VEGF-C对TNF-α诱导的肾小管上皮细胞凋亡的作用.方法 体外培养大鼠近端肾小管上皮细胞（NRK52E）,加入不同浓度的TNF-α作用不同时间,用实时定量PCR和Western blot方法检测VEGF-C mRNA和蛋白的表达.用不同浓度TNF-α与放线菌素D（ActD）刺激细胞24 h,流式细胞学方法检测细胞凋亡.再加入不同浓度的VEGF-C,观察其对凋亡的抑制情况.结果 TNF-α促进NRK52E细胞VEGF-C的表达,呈剂量和时间依赖性.TNF-α（加入ActD 30ng/ml）促进细胞凋亡,凋亡率随TNF-α浓度增高而增加.VEGF-C能够抑制凋亡,50 ng/ml时对细胞凋亡有抑制作用,100 ng/ml时抑制作用最强.结论 VEGF-C对大鼠近端肾小管上皮细胞的凋亡具有保护作用.     

Urinary excretion of angiotensinogen reflects intrarenal angiotensinogen production

BACKGROUND: In rats maintained on a high salt diet (H/S) to suppress basal renal angiotensinogen levels, angiotensin II (Ang II) infusion for 13 days increased renal angiotensinogen mRNA and protein, thus providing a mechanism for further augmentation of intrarenal Ang II levels. The present study tested the hypothesis that enhanced intrarenal angiotensinogen formation during Ang II infusion is reflected by secretion into the tubular fluid leading to increased urinary excretion of angiotensinogen (UAGT). METHODS: The effects of chronic Ang II infusion were examined on kidney and plasma Ang II levels and UAGT in male Sprague-Dawley rats maintained on an 8% salt diet for three weeks (N=10). Following one week on the H/S diet, Ang II (40 ng/min) was administered for two weeks via an osmotic minipump to one group (H/S + Ang II, N=5), while the remaining rats were sham-operated (H/S + Sham, N=5). Additionally, a control group was prepared with normal salt diet and sham-operation (N/S + Sham, N=5). RESULTS: H/S alone did not alter systolic blood pressure (BP) (103 +/- 2 vs. 104 +/- 2 mm Hg), while Ang II infusion to H/S rats significantly increased systolic BP from 103 +/- 2 to 154 +/- 2 after two weeks. Intrarenal Ang II content in H/S + Ang II was significantly greater than H/S + Sham (435 +/- 153 vs. 65 +/- 14 fmol/g). Ang II infusion significantly increased UAGT (4.0 +/- 0.5 vs. 1.0 +/- 0.2 nmol Ang I/day by radioimmunoassay of generated Ang I; 57 +/- 15 vs. 14 +/- 2 densitometric units by Western blotting analysis) compared to Sham. UAGT by radioimmunoassay was highly correlated with kidney Ang II content (r=0.79); but not with plasma Ang II concentration (r=0.20). CONCLUSIONS: These data demonstrate that chronic Ang II infusion increases urinary excretion rate of angiotensinogen, and suggest that UAGT provides a specific index of intrarenal angiotensinogen production in Ang II-dependent hypertension.     

益肾泄浊方对TGF-β_1诱导大鼠肾小管上皮细胞Ⅰ型胶原及FN表达的影响

目的：探讨益肾泄浊方对TGF-β1诱导大鼠肾小管上皮细胞Ⅰ型胶原及FN表达的影响。方法：采用灌胃法分别给予健康大鼠益肾泻浊方冲剂、缬沙坦以及益肾泻浊方＋缬沙坦联合治疗,取给药后大鼠的血清分组干预经TGF-β1刺激72h后的大鼠肾小管上皮（NRK52E）细胞,用RT-PCR方法检测Ⅰ型胶原、FNmRNA的表达,用ELISA方法检测FN蛋白水平的表达。结果：益肾泻浊方、缬沙坦均能抑制TGF-β1诱导的NRK52EⅠ型胶原、FN的表达,而益肾泻浊方与缬沙坦联用后,对NRK52E细胞FN表达的抑制作用更为显著。结论：益肾泻浊方抑制TGF-β1诱导大鼠肾小管上皮细胞Ⅰ型胶原及FN的表达,可延缓肾脏纤维化的进展。     

黄芪通过c-met调控TGF-β1诱导的肾小管上皮细胞转分化

AB 目的：探讨黄芪对TGF-β1诱导的肾小管上皮细胞转分化及细胞外基质分泌的作用及机制。方法：体外培养正常大鼠肾小管上皮细胞（NRK52E）,应用倒置相差显微镜观察NRK52E细胞形态学变化;免疫组织化学染色法及实时荧光定量PCR法检测α-平滑肌肌动蛋白（α-SMA）,肝细胞生长因子HGF受体（c-met）的表达;ELISA法定量检测细胞上清液中胶原Ⅰ（Col-Ⅰ）,胶原Ⅲ（Col-Ⅲ）和纤维黏连蛋白（FN）的水平。结果：TGF-β1可诱导肾小管上皮细胞肌成纤维细胞转分化（TEMT）,TGF-β1诱导组细胞肥大、拉长,呈长梭形,α-SMA表达明显增强,Col-Ⅰ、Col-Ⅲ和FN分泌增加（P〈0.05）。加入不同浓度黄芪后,细胞形态接近正常肾小管上皮细胞形态,α-SMA表达、Col-Ⅰ、Col-Ⅲ和FN分泌均较TGF-β1诱导组明显抑制（P〈0.05）,c-met表达较TGF-β1诱导组增加（P〈0.05）且呈剂量依赖性。结论：TGF-β1可以诱导肾小管上皮细胞肌成纤维细胞转分化,增加细胞外基质成分Col-Ⅰ、Col-Ⅲ和FN的分泌;黄芪能够抑制TGF-β1诱导的NRK52E细胞转分化以及细胞外基质的分泌;黄芪抑制细胞转分化的机制可能与其增强c-met的表达有关。     

肾小管上皮间充质转化细胞模型中WT1和Pax2重新表达的研究

目的:探讨肾小管上皮间充质转化(EMT)细胞模型中胚胎发育基因WT1和Pax2的重新表达及其规律,并研究上调表达外源性WT1对肾小管上皮细胞株(NRK52E)的影响。方法:采用10 ng/ml IL-1α刺激体外培养的NRK52E细胞,建立EMT细胞模型。采用脂质体转染技术,将pRc/CMV-D-WT1质粒瞬时转染NEK52E细胞。分别提取EMT细胞模型和质粒转染组不同时间点细胞的RNA和蛋白质,采用RT-PCR和Western blot检测NEK52E细胞WT1、Pax2、上皮细胞标志E-cadherin和间充质标志α-SMA的表达,研究基因表达的时效性变化规律,并观察细胞的形态。结果:成功建立EMT细胞模型,该模型中E-cadherin的表达显著减少,α-SMA的表达显著增多,细胞发生明显的成纤维化样改变。在EMT细胞模型中,出生后关闭的WT1和Pax2获得重新表达,且Pax2的表达早于α-SMA和WT1。在NEK52E细胞中上调表达WT1,细胞表达α-SMA,不表达Pax2,同时E-cadherin的表达显著减少,细胞出现成纤维化样改变。结论:Pax2和WT1基因是EMT中的关键基因,在EMT发生时呈序列启动,Pax2在EMT中处于WT1上游。胚胎发育基因WT1和Pax2的重新表达可能是EMT的重要机制。