Ganoderma extract prevents albumin-induced oxidative damage and chemokines synthesis in cultured human proximal tubular epithelial cells.

BACKGROUND: Ganoderma lucidum (Ganoderma or lingzhi) is widely used as an alternative medicine remedy to promote health and longevity. Recent studies have indicated that components extracted from Ganoderma have a wide range of pharmacological actions including suppressing inflammation and scavenging free radicals. We recently reported that tubular secretion of interleukin-8 (IL-8) induced by albumin is important in the pathogenesis of tubulointerstitial injury in the proteinuric state. In this study, we explored the protective effect of Ganoderma extract (LZ) on albumin-induced kidney epithelial injury. METHODS: Growth arrested human proximal tubular epithelial cells (PTECs) were incubated with 0.625 to 10 mg/ml human serum albumin (HSA) for up to 72 h. HSA induced DNA damage and apoptosis in PTEC in a dose- and time-dependent manner. Co-incubation of PTEC with 4-64 microg/ml LZ significantly reduced the oxidative damage and cytotoxic effect of HSA in a dose-dependent manner (P<0.001). Increased release of IL-8 and soluble intercellular adhesion molecules-1 (sICAM-1) in PTEC induced by HSA was ameliorated by co-incubation with Ganoderma (16 microg/ml). To explore the components of LZ that exhibited most protective effect in HSA-induced PTEC damages, LZ was further separated into two sub-fractions, LZF1 (MW <30 kDa) and LZF2 (MW <3 kDa), by molecular sieving using millipore membrane. PTEC were incubated with 5 mg/ml HSA in the presence of different doses of LZF1, LZF2 or unfractionated LZ. RESULTS: There was no difference in the degree of protection from HSA-induced cytotoxicity or oxidative DNA damage between different fractions of LZ. However, low molecular weight LZ (<3 kDa) was most effective in reducing sICAM-1 released from HSA-activated PTEC whereas the high molecular weight LZ (unfractionated LZ) was more effective in diminishing IL-8 production. CONCLUSIONS: Our results suggest that Ganoderma significantly reduces oxidative damages and apoptosis in PTEC induced by HSA. The differential reduction of IL-8 or sICAM-1 released from HSA-activated PTEC by different components of the LZ implicates that components of Ganoderma with different molecular weights could play different roles and operate different mechanisms in preventing HSA-induced PTEC damage.     

Role of serotonin in the regulation of renal proximal tubular epithelial cells

In various renal injuries, tissue damage occurs and platelet activation is observed. Recent studies suggest that some factors, such as serotonin, are released into microenvironment upon platelet activation following renal injury. In the present study, we aimed to investigate whether platelets and platelet-released serotonin are involved in the functional regulation of renal proximal tubular epithelial cells (PTECs). PTECs were obtained by primary cell culture and treated with platelet lysate (PL) (2?×?10⁶/mL, 4?×?10⁶/mL, 8?×?10⁶/mL) or serotonin (1?μM or 5?μM) for 12 or 24?h. Phenotypic transdifferentiation of epithelial cells into myofibroblasts were demonstrated under light microscope and confirmed by the determination of α-smooth muscle actin gene expression. Serotonin and PL were shown to induce epithelial–mesenchymal transdifferentiation of PTECs. After stimulation of PTECs with serotonin or PL, matrix metalloproteinase-2, tissue inhibitor of metalloproteinase-1, and collagen-α1 gene expressions, which were reported to be elevated in renal injury, were determined by real-time PCR and found to be upregulated. Expressions of some inflammatory cytokines such as tumor necrosis factor-α, interleukin-6, and transforming growth factor-β1 were found to be increased in both protein and gene levels. Recently there is no published report on the effect of serotonin on renal PTECs. Results obtained in this study have lightened the role of serotonin and platelet-mediated effects of serotonin on fibrotic and inflammatory processes in PTECs.     

High molecular weight plasma proteins induce apoptosis and Fas/FasL expression in human proximal tubular cells.

BACKGROUND: In proteinuria, proximal tubular epithelial cells (PTECs) are exposed to abnormally high protein concentrations, eventually leading to tubular atrophy and end-stage renal disease. The mode of cell death leading to tubular atrophy in proteinuria has not been fully established. This study examines the role of protein overload on apoptosis, necrosis and cell proliferation in primary cultures of human PTECs using plasma protein fractions representative of selective and non-selective proteinuria. The involvement of the Fas/Fas ligand (FasL) system was also investigated. METHODS: Plasma was collected from healthy volunteers and fractionated into albumin-rich (30-100 kDa), high molecular weight (100-440 kDa) and combined (30-440 kDa) fractions. PTECs were exposed to 10 mg/ml of the protein fractions for 24, 48 and 72 h. Apoptosis was measured using fluorescein isothiocyanate (FITC)-annexinV and TUNEL. Necrosis was measured using propidium iodide, metabolic activity by MTT and cell proliferation by bromodeoxyuridine incorporation. Fas and FasL expression was analysed by western blotting. RESULTS: Exposure to the 100-440 and 30-440 kDa fractions produced significant increases in apoptosis at all time points, whereas PTECs exposed to the 30-100 kDa fraction were not significantly different from control cells. There were no changes in the rates of necrosis as a result of protein loading. A significant reduction in metabolic activity was observed in PTECs exposed to the 100-440 and 30-440 kDa fractions, but not to the 30-100 kDa fraction. Cell proliferation was significantly reduced by 24 h in cells exposed to the 100-440 and 30-440 kDa fractions. By 48 and 72 h, all the three fractions had inhibited cell proliferation. PTECs exposed to the 100-440 and the 30-440 kDa fractions showed a significant upregulation in the expression of Fas and FasL. Overall, the high molecular weight fraction was more 'toxic' than the albumin-rich or combined fraction. CONCLUSION: Increased apoptosis and decreased cell proliferation are the major mechanisms of cell death in human PTECs in response to protein overload. These effects may be mediated at least in part by overexpression of the Fas/FasL system. The severity of such changes is largely determined by the high molecular weight fraction (100-440 kDa) rather than the albumin-rich fraction.     

虫草菌液拮抗马兜铃酸对人近端肾小管上皮细胞的作用

目的 探讨虫草菌液能否拮抗马兜铃酸诱发的人近端肾小管上皮细胞系(HKC)的促纤维化效应。 方法 马兜铃酸钠盐(AA-Na，40 mg/L)加或不加虫草菌液(10 mg/L)与HKC孵育(孵育12 h检测mRNA表达，孵育36 h检测蛋白质表达)，然后检测HKC中转化生长因子-β1(TGF-β1)、结缔组织生长因子(CTGF)、金属蛋白酶1组织抑制物(TIMP-1)以及纤溶酶原激活物抑制物1(PAI-1)的mRNA(RT-PCR法)和相应蛋白质(CTGF表达采用免疫印迹法，其余采用ELISA方法)表达。结果 AA-Na能显著上调HKC对TGF-β1、CTGF、TIMP-1、PAI-1的表达，与对照组比较，mRNA表达分别上调1.24、1.31、1.27及1.36倍，蛋白质表达分别上调2.50、1.75、2.13及1.46倍，P均<0.05。加虫草菌液后，上述TGF-β1、CTGF及TIMP-1的高表达被显著抑制，与AA-Na组比较，mRNA表达的抑制率分别为12%、20%及17%；蛋白质表达的抑制率分别为25%、20%及37%，P均<0.05，但未能抑制PAI-1的高表达(P > 0.05)。结论 虫草菌液可下调AA-Na刺激的HKC促细胞外基质(ECM)合成因子(TGF-β1、CTGF)及抗ECM降解因子(TIMP-1)的表达。     

乙型肝炎病毒X基因对肾小管上皮细胞间质转分化的影响

目的 探讨乙型肝炎病毒(HBV)X基因表达蛋白HBX对体外培养的人近端肾小管上皮细胞株(HK-2)细胞形态及转分化的影响.方法 用分子克隆的方法构建pcDNA3.1-myc-HBX质粒,采用脂质体转染法瞬时转染HK-2细胞,Q-PCR及Western印迹法验证HBX在HK-2细胞中的表达.以未转染质粒和转染空载质粒pcDNA3.1-myc作为对照.用显微镜观察转染pcDNA3.1-myc-HBX质粒后HK-2细胞形态,用Western印迹及Q-PCR法检测细胞转分化标志蛋白α平滑肌肌动蛋白(α-SMA)、E钙黏蛋白(E-cadherin)的表达;ELISA检测细胞上清液中白细胞介素(IL)-1、IL-6和肿瘤坏死因子α(TNF-α)的表达.结果 转染HBX后的HK-2细胞中存在HBX的高表达,证实转染成功.转染pcDNA3.1-myc-HBX质粒的HK-2细胞数量明显下降,细胞形态不规则,细胞状态受损;转染pcDNA3.1-myc-HBX质粒的HK-2细胞可上调E-cadherin及α-SMA表达;细胞上清液中高表达IL-1、IL-6和TNF-α(P＜ 0.01).结论 HBX质粒转染HK-2细胞后可引起细胞数目和形态的变化,并促进肾小管上皮细胞发生上皮间质转分化,肾小管上皮细胞周围炎性微环境的改变可能是其发生上皮间质转分化的原因之一.     

缬沙坦抑制人类肾小管上皮细胞转分化的初步研究

目的：探讨血管紧张素ⅡⅠ型受体拮抗剂缬沙坦（ｖａｌｓａｒｔａｎ,Ｖａｌ）在人类肾小管上皮细胞系（ＨＫＣ）转分化中的作用。方法将培养的ＨＫＣ细胞分为（１）无血清培养培养对照组;（２）阳性对照组（ＭＣＰ－１＋ＡＡＩ组）：培养液中加入马兜铃酸－Ｉ（ＡＡＩ）和单核细胞趋化蛋白－１）ＭＣＰ－１）：（３）Ｖａｌ组：培养液中加入Ｖａｌ;（４）ＭＣＰ－１＋ＡＡＩ＋Ｖａｌ组。应用间接酶标免疫组织化学方法（ＩＥＩ）检     

重组人骨桥蛋白刺激人近端肾小管上皮细胞向间质细胞转化的研究

目的 观察骨桥蛋白(OPN)对人近端肾小管上皮细胞(HK-2)向间质细胞转化(EMT)的影响.方法 依据加入的重组人骨桥蛋白(rhOPN)的浓度,将HK-2细胞分成6组,rhOPN的浓度依次为:0.00、0.04、0.08、0.12、0.16、0.20 mg/L,刺激时间为48h.采用共聚焦显微镜观察细胞形态学变化;实时定量聚合酶链反应(PCR)、Western blot检测E-钙黏素(E-cad)、α-平滑肌肌动蛋白(α-SMA)、纤连蛋白(FN)的表达;应用流式细胞仪检测各组细胞的凋亡.结果 在形态学上,rhOPN能够刺激HK-2细胞向间质细胞转变,通过实时定量PCR、Western blot分析发现上皮细胞的表面标记E-cad随着刺激浓度的增加而逐渐降低,间质细胞的标记物α-SMA、FN的表达逐渐升高,实时定量PCR检测E-cad依次为:1947.0±301.0、1114.0±187.4、668.7±180.4、436.7±121.8、242.7±105.2、223.5±73.4; α-SMA依次为:0.01465±0.003 38、0.034 28±0.01200、0.06034±0.005 65、0.09205±0.010 68、0.11360±0.018 92、0.186 30±0.021 75;FN依次为:0.000 818±0.000103、0.001 341±0.000203、0.001 708±0.000128、0.002 170±0.000161、0.003 369±0.000314、0.004961±0.000364.Western blot检测E-cad依次为:1.719±0.159、1.370±0.016、1.238±0.031、0.916±0.056、0.520±0.065、0.456±0.073;α-SMA依次为:0.623±0.127、0.640±0.031、0.865±0.045、1.015±0.107、1.290±0.103、1.381±0.040; FN依次为:0.475±0.044、0.499±0.062、0.904±0.066、0.981 ±0.052、1.272±0.093、1.614±0.056,各组之间差异有统计学意义(均P＜0.05),且随着OPN刺激浓度的增加,细胞的抗凋亡能力也逐渐增强.结论 OPN能够刺激HK-2细胞向间质细胞转化,且呈现出明显的剂量依赖性.     

Chemoattraction of T cells expressing CCR5, CXCR3 and CX3CR1 by proximal tubular epithelial cell chemokines.

BACKGROUND: Chemokines produced by resident renal cells promote the infiltration of leukocyte subsets. We have analysed the chemotactic responses of CD3+ peripheral blood lymphocytes (PBLs) to factors secreted by proximal tubular epithelial cells (PTEC), assessing the role of chemokines and chemokine receptors in this process. METHODS: By FACS we analysed expression of the chemokine receptors CCR5, CXCR3, CX3CR1, CCR2, CXCR1 and CXCR2 on both freshly isolated and activated PBLs. Using Boyden chambers we studied the chemotactic activity of supernatant from resting and cytokine-stimulated (TNF-alpha and IFN-gamma) PTEC towards PBLs. Soluble recombinant chemokines and blocking antibodies were used to study the role of individual chemokine receptors. Chemokine secretion by PTEC was analysed by ELISA. RESULTS: Only a small proportion of freshly isolated cells expressed the chemokine receptors and there was low grade chemotaxis of these cells towards cytokine-stimulated PTEC supernatant compared with unstimulated PTEC supernatant. After activation, 84% of PBLs expressed CCR5, 90% expressed CXCR3 and 19% expressed CX3CR1. There remained low expression levels of CXCR1, CXCR2 and CCR2. Activated PBLs showed strong chemotactic responses to supernatant from cytokine-stimulated PTEC compared with unstimulated PTEC (P<0.001). Chemotaxis of these cells was inhibited by blocking CCR5, CXCR3 and CX3CR1 by 69%, 71% and 29% respectively, with complete inhibition following combined blockade. ELISA showed high levels of the chemokine RANTES/CCL5 (for CCR5) and IP-10/CXCL10 (for CXCR3) in cytokine-stimulated PTEC supernatant. CONCLUSIONS: Chemokines produced by cytokine activated PTEC promote the selective recruitment of activated T cells via the receptors, CCR5, CXCR3 and CX3CR1. These receptors may be amenable to therapeutic manipulation in renal inflammation.     

钙化纳米微粒诱导人肾小管上皮细胞自噬的研究

目的 观察不同浓度钙化纳米微粒( calcifying naniparticles,CNP)对人肾小管上皮细胞HK-2生长的影响,探讨CNP是否可以诱发体外培养HK-2细胞的自噬作用. 方法 将0.0125、0.025、0.05、0.1 mg/ml等4种浓度CNP加入对数生长期的HK-2细胞,培养12、24、48、72 h后,MTT法检测HK-2细胞生长、增殖情况.EGFP-LC3表达质粒转染体外培养HK-2细胞,培养24 h后,加入CNP共同孵育,作用3、6、24、48 h后收集细胞,透射电镜下检测CNP作用后HK-2细胞自噬体的形成,荧光显微镜检测CNP作用前后HK-2细胞LC-3斑点的形成情况. 结果 CNP对HK-2细胞的生长抑制作用随着CNP浓度的升高和作用时间的延长而增强,0.05 mg/ml CNP作用48 h后HK-2细胞增殖抑制率为14.5％,0.1 mg/ml CNP作用72h后抑制率达21.5％.加入CNP 6 h后透射电镜下可见CNP聚集形成结晶样物并黏附于HK-2细胞表面,HK-2细胞质内见散在的自噬体形成.荧光显微镜下可见转染EGFP-LC3的HK-2细胞质内散在分布的LC-3荧光斑点. 结论 CNP可以诱发HK-2细胞的自噬作用,可能在肾结石等生物矿化相关疾病发生中起重要的作用.     

肾康注射液对肾小管上皮细胞LLC-PK1分泌层粘连蛋白的影响

目的：探讨肾康注射液对肾小管上皮细胞LLC－PK1分泌层粘连蛋白（LN）的影响。方法：用细胞酶联免疫吸附（ELISA）方法,以单味大黄注射液为实验对照组,检测肾康注射液对肾小管上皮细胞LLC－PK1分泌LN含量的影响。结果：肾康注射液可以显抑制肾小管上皮细胞LLC－PK1分泌LN的含量,并呈剂量依赖关系;肾康注射液作用明显优于同等含量的单味大黄注射液。结论：肾康注射液抑制肾小管上皮细胞LLC－PK1分泌LN含量,是该方延缓慢性肾衰竭进展的机理之一。     

脯氨酸羟化酶2 siRNA对抗霉素诱导肾小管上皮细胞凋亡的影响

目的 探讨是否脯氨酸羟化酶2 (PHD2) siRNA 通过减少缺氧诱导因子(HIF)1的降解而减轻缺氧引起的肾小管上皮细胞凋亡。方法 构建针对人PHD2的表达质粒,将其转染到培养的人肾小管上皮细胞系(HKC)中。用RT-PCR方法观察其对PHD2表达的抑制作用。Western印迹观察HIF-1α的表达。培养的HKC细胞分为对照组、模型组和siRNA组、siRNA组经PHD2 siRNA转染后与模型组同时用抗霉素诱导,用Western印迹方法观察3组细胞HIF-1α的表达,用流式细胞仪观察3组细胞的凋亡情况。 结果 经PHD2 siRNA转染的HKC细胞PHD2 mRNA表达明显下调(P < 0.01),HIF-1α蛋白表达明显上调(P < 0.05)。经抗霉素处理后,模型组和siRNA组HIF-1α蛋白表达均明显高于对照组(P < 0.01),但siRNA组HIF-1α蛋白表达高于模型组(P < 0.05。与模型组相比,siRNA组细胞凋亡明显减轻(P < 0.05)。 结论 通过RNA干扰技术抑制PHD2的表达可以增强HKC细胞HIF-1的蛋白表达,从而增强其在缺氧条件下的抗凋亡能力。     

Renal tubular epithelial cell death and cyclosporin A.

BACKGROUND: The pathogenesis of chronic cyclosporin A (CsA) nephrotoxicity is largely unknown. In this study we examined whether CsA produces cell death through necrosis or apoptosis of either cultured human proximal tubular epithelial cells (PTEC) or the porcine tubular cell line LLC-PK(1). METHODS: Primary isolates of human PTEC and LLC-PK(1) cells were treated for various time periods with CsA at concentrations of 0.01-100 microg/ml. Apoptosis was studied by the assessment of annexin binding and propidium iodide uptake, the measurement of cellular DNA content and cell cycle analysis, and by the evaluation of nuclear morphology. Cell death was studied by the trypan blue exclusion method. Hypoxic conditions were simulated through chemical ATP depletion. RESULTS: In human PTEC, cell death was observed at CsA concentrations higher than 10 microg/ml; at these concentrations PTEC died as a result of necrosis and the toxicity of its vehicle Cremophore EL, and not as a result of CsA inducing apoptosis. The addition of cycloheximide to relieve a possible block in the apoptotic process had no effect on human PTEC, but did result in apoptosis of LLC-PK(1). In human PTEC, CsA did not augment cell death induced by chemical ATP depletion. CONCLUSIONS: The results of this in vitro study do not support the hypothesis that CsA directly induces cell death of proximal tubular epithelial cells.     

Angiotensin II receptor blocker inhibits tumour necrosis factor-alpha-induced cell damage in human renal proximal tubular epithelial cells

Aim: We investigated the effect of angiotensin II (AII) type 1 (AT1) and angiotensin II type 2 (AT2) receptor blockers on tumour necrosis factor alpha (TNF‐α)‐induced cell damage in human renal proximal tubular epithelial cells (RPTEC). Methods: The lactate dehydrogenase (LDH) and N‐acetyl‐beta‐glucosaminidase (NAG) release into the medium after TNF‐α treatment in RPTEC were determined using modified commercial procedures. In addition, the levels of caspase 3/7 activity in RPTEC were measured after TNF‐α treatment with ΑΤ1 or AT2 receptor blockers. Finally we investigated the change of p22phox protein levels after TNF‐α with ΑΤ1 or AT2 receptor blockers in RPTEC. Results: Tumour necrosis factor alpha (10^?8 mol/L) significantly increased LDH and NAG release into the medium from RPTEC. ΑΤ1 receptor blockers, olmesartan and valsartan (10^?9?10^?6 mol/L) showed a significant reduction on TNF‐α‐induced LDH and NAG release in RPTEC. AT2 receptor blocker, PD123319 (10^?7?10^?5 mol/L) also decreased TNF‐α‐induced LDH and NAG release in RPTEC. Blockade of both ΑΤ1 and AT2 receptor indicated additional reduction on TNF‐α‐induced LDH and NAG release. TNF‐α (10^?8 mol/L) treatment showed small but significant increases of caspase 3/7 activity in RPTEC, and AT1 and AT2 receptor blockers (10^?8 mol/L) comparably decreased TNF‐α‐induced caspase 3/7 activity. Significant increases of p22phox protein levels were observed in TNF‐α‐treated group in RPTEC. However, only ΑΤ1 (10^?8 mol/L) but not AT2 (10^?5 mol/L) receptor blocker significantly decreased TNF‐α‐induced p22phox protein levels. Conclusion: The present study demonstrates that TNF‐α induces renal tubular cell damage in RPTEC and AT1/AT2 receptor blockers showed cytoprotective effects probably via at least partly different mechanism.     

Astragalosides IV inhibits high glucose-induced cell apoptosis through HGF activation in cultured human tubular epithelial cells

Astragaloside IV (ASI) in Radix Astragali is believed to be the active component. The study aims to investigate whether ASI inhibits tubular epithelial cells apoptosis induced by high glucose and its mechanisms. Tubular epithelial cells in this paper were isolated from human kidney. The cells apoptosis was detected by TUNEL and caspase 3 assay. The protein levels of HGF and TGF-β1 were measured by ELISA. The phospho-p38 production, ERK and JNK were determined by Western blot. ASI could inhibit cells apoptosis induced by high glucose (25?mmol/L) in dose-dependent and time-dependent manners. ASI also inhibited high glucose-induced expression of TGF-β1 and activation of p38 MAPK pathway at the protein level. Furthermore, ASI increased HGF production in human tubular epithelial cells. The ASI inhibition of tubular epithelial cells apoptosis and reduction of TGF-β1 expression induced by high glucose may represent a new treatment for diabetic kidney injury. The mechanism underlying this inhibitory effect may be related to the inhibition of p38 MAPK signaling pathway activation and HGF overproduction.     

Effects of mycophenolic acid on human renal proximal and distal tubular cells in vitro.

BACKGROUND:Mycophenolic acid has been shown to be effective for the prevention and treatment of renal allograft rejection. Rejection episodes were found to be associated with an infiltration of lymphocytes and macrophages/monocytes into the diseased kidney. Expression of RANTES, HLA-DR and ICAM-1 may be important for the pathogenesis of this leukocyte infiltration. Therefore the aim of this study was to evaluate the effect of the antiproliferative and immunosuppressive agent mycophenolic acid (MPA) on cell growth and cytokine-induced expression of RANTES, HLA-DR and ICAM-1 of highly purified proximal (PTC) and distal tubular cells (DTC) from human kidney. METHODS:Human PTC and DTC were cultured in the presence of different concentrations of MPA (0.25-50 microM) or MPA plus guanosine (100 microM). Total cell number (DNA content) was determined after 4 days of cell culture by a non-radioactive fluorescence assay. Cells were stimulated by a combination of cytokines (IL1beta+gammaIFN+TNFalpha=cytomix) or cytomix plus MPA. Secretion of RANTES protein was evaluated with an enzyme-linked-immunosorbent assay. Cell surface expression of HLA-DR and ICAM-1 was assessed by flow cytometric analysis. RESULTS:MPA inhibited cell growth of PTC and DTC in a dose-dependent manner. This effect was totally abolished by the addition of guanosine. Cytokine-induced RANTES expression was synergistically increased in the presence of MPA, an effect that was partially prevented by the addition of guanosine. Cytokine stimulation resulted in de novo expression of HLA-DR and a marked increase of ICAM-1 expression, which was partially inhibited by dexamethasone. Addition of MPA did not influence this stimulated expression. CONCLUSIONS:We demonstrate that MPA has an effect on cell growth and chemokine release of tubular epithelial cells, and that these effects are dependent on the inhibition of cellular guanosine production. The clinical consequences of this possible pro-inflammatory effect of MPA on RANTES release may be abolished by a concomitant treatment with steroids.