Application of genetically engineered tubular epithelial cells in kidney disease.

We constructed an ex vivo gene transfer system to deliver cytokines into the kidney and circulation using genetically modified renal tubular epithelial cells (TEC). TEC were infected with recombinant retroviruses expressing macrophage (Mphi) growth factors using a retroviral Moloney murine leukemia virus-based MFG vector. These infected TEC have the capacity to secrete stable and sustained amounts of cytokines for prolonged periods (>4 months) in vitro and in vivo (>28 days). Implanting genetically modified TEC secreting Mphi growth factors under the kidney capsule initiates severe local renal injury in mice with a deficiency in Fas (Faslpr gene). This system offers a novel and powerful approach to probe for the impact of sustained cytokine expression in the progression of kidney destruction.     

大鼠肾小管上皮细胞的原代培养及传代

建立大鼠肾小管上皮细胞原代培养、传代及鉴定方法。方法采用研磨、消化培养法,并以０．２５％胰蛋白酶（Ａ组）、０．２５％胰蛋白酶－０．０２％ＥＤＴＡ（Ｂ组）分别消化、传代、对比,以免疫细胞化学方法鉴定细胞种类。结果成功培养、传代（１３～１８代）并鉴定（抗Ｃｙｔｏｋｅｒａｔｉｎ１８抗体）了肾小管上皮细胞,发现Ａ组消化传代效果明显优于Ｂ组。结论０．２５％胰蛋白酶消化传代方法是大鼠肾小管上皮细胞原代培养、传代及鉴定的有效手段。     

激活素A在高糖诱导的人肾小管上皮细胞中的表达变化

目的 通过体外高糖刺激的人近端肾小管上皮细胞株(HK-2),探讨激活素A(ACT A)的表达变化及卵泡抑素(FS)的干预作用.方法 HK-2细胞生长于DMEM培养基,待细胞生长至亚融合状态时,更换为无血清DMEM培养基使细胞生长同步化24h,然后将细胞分为以下5组:正常对照组(NG,5.5 mmol/L葡萄糖)、甘露醇对照组(MG,5.5 mmol/L葡萄糖+25 mmol/L甘露醇)、高糖组(HG,25 mmol/L葡萄糖)、HG+FS100组(25 mmol/L葡萄糖+100 μg/L FS)、HG+FS500组(25 mmol/L葡萄糖+500 μg/L FS).12、24、48 h后收集各组细胞及细胞上清液.Western印迹法检测各组细胞ACT A和p-Smad2/3的表达;ELISA检测各组细胞上清液转化生长因子β(TGF-β)和纤连蛋白(FN)的含量.结果 NG组细胞ACT A有微量表达,而HG组表达显著增加(P＜0.05),呈时间依赖性.与HG组相比,FS干预组ACT A表达显著减少(P＜0.05),呈剂量依赖性.与NG组相比,p-Smad2/3在HG组培养24 h后表达显著增加(P＜0.05);FS可抑制p-Smad2/3的高表达(P＜0.05).ELISA检测结果显示,与NG组相比,HG组培养12 h后TGF-β表达即显著增加(P＜0.05),呈时间依赖性,FS干预对高糖诱导的TGF-3高表达没有影响.与NG组相比,HG组培养24h后FN表达显著增高(P＜0.01),FS对此有明显抑制作用,呈剂量依赖性(P＜0.01).结论 高糖能刺激HK-2细胞ACT A表达增加,从而促进肾小管上皮细胞FN的合成;FS可通过阻断ACT A的活化,减轻肾小管上皮细胞FN的合成.     

肾小管上皮细胞与内皮细胞在TiO2纳米管上种植的对比

目的 观察猪肾小管上皮细胞（LLC-PK1）和人脐静脉内皮细胞（ECV304）在TiO2纳米管阵列上的黏附及生长状况,为构建微型化的生物人工肾提供实验依据。 方法 采用阳极氧化法制备4种不同管径的纳米管材料,将每种材料分别经未退火光照、退火未光照及退火光照处理,共计12组,分别将两种细胞种植在12组材料上,利用荧光显微镜观察并比较两种不同细胞在同种材料上的黏附及生长状况。采用MTT检测不同管径上两种细胞的活性及70 nm管径上两种细胞的增殖情况。 结果 两种细胞在TiO2纳米管上的黏附及增殖情况基本一致,综合考虑在管径为70 nm、未光照的锐钛矿型TiO2纳米管上的黏附情况最佳,细胞活性最高。LLC-PK1细胞在该材料上的吸光度值随种植时间的延长越来越大,且任意时间点的吸光度值明显高于纯钛片对照组。ECV304细胞在该材料上的吸光度值随种植时间的延长也越来越大,只是吸光度值较纯钛片对照组低。 结论 单独种植两种细胞时,肾小管上皮细胞在TiO2纳米管上的黏附及增殖活性均很高,而内皮细胞在纳米管上的黏附率较低,且增殖较缓慢,表明TiO2纳米管有利于上皮细胞的生长,而不利于内皮细胞的生长。     

肾小管上皮细胞程序性坏死对慢性肾脏病患者肾损伤的影响

目的:分析不同分期慢性肾脏病（chronic kidney disease,CKD）患者肾组织中发生程序性坏死的肾小管上皮细胞数量及其与临床病理指标的相关性,探讨肾小管上皮细胞程序性坏死在CKD患者肾小管上皮细胞过度死亡、慢性肾损伤进展中的作用。方法:收集2017年6月至2019年6月于海南医学院第一附属医院行肾活检且...     

Characterization of CD44-mediated hyaluronan binding by renal tubular epithelial cells

Background. CD44 is the main receptor for the extracellular polysaccharide hyaluronan (HA). We have recently shown that CD44 is strongly induced on renal tubular epithelial cells (TEC) in autoimmune renal injury and that HA accumulates in the renal interstitium (Kidney Int 1996; 50: 156-163 and Nephrol Dial Transplant 1997; 12: 1344-1353). The functional significance of enhanced tubular CD44 expression and its interaction with HA are not known. The purpose of the present study was to characterize renal tubular CD44 expression and CD44-mediated HA binding in vitro and to investigate the growth modulating effects in response to HA binding by TEC. Methods. RT-PCR analysis, flow cytometry, confocal microscopy and Western blotting were used to examine cell surface and soluble CD44 expression by cultured TEC, using SV40-transformed mouse cortical tubular (MCT) cells. HA binding characteristics were examined by flow cytometry and effects of HA on TEC cell growth by [³H]thymidine incorporation. Results. By RT-PCR analysis MCT cells expressed predominantly the standard form of CD44 mRNA, whereas the expression of variant forms was very weak. Confocal microscopy showed that CD44 was expressed basolaterally and apically on MCT cells with strong staining on microvilli. Shedding of CD44 from MCT cells could be induced with crosslinking of anti-CD44 mAbs or with PMA stimulation. MCT cells constitutively bound HA and this binding could be modulated with anti-CD44 mAbs. Soluble and plate-bound HA markedly inhibited MCT cell growth. Conclusions. CD44 is a regulated HA receptor on MCT cells which can be shed into the cellular environment. Upon binding of HA, CD44 functions as a growth inhibitory cell surface protein in MCT cells. We speculate that the interaction of CD44 with HA may have important regulatory effects on cell proliferation in tubulointerstitial renal diseases.     

Donor-specific lysis of human kidney proximal tubular epithelial cells by renal allograft-infiltrating lymphocytes

In the present study methods are described to obtain both graft infiltrating cells (GIC) of host origin and proximal tubular epithelial cells (PTEC) of donor origin simultaneously from biopsy material of renal allografts undergoing rejection. The identity of PTEC cultures was established using monoclonal antibodies. GIC were shown to exhibit T cell functional activity. These GIC were shown to lyse trypsinized PTEC as well as PTEC monolayers grown from the corresponding biopsy, and not PTEC isolated from biopsies obtained from other patients. Therefore the lytic activity appeared to be donor-specific. Major histocompatibility complex class I antigens were involved since donor PHA-blasts, a target population well known to express class I molecules, were lysed by GIC, and the anti-class I MoAb W6/32 blocked cytolytic activity of GIC against donor PHA-blasts and against donor PTEC. We thus established that donor-specific lysis of a defined population of kidney epithelial cells, namely PTEC, may occur. This model system, in which GIC and PTEC can be propagated from one biopsy specimen may be useful for further study of cell-cell interactions involved in allograft rejection.     

Auto-antibody to kidney tubular cells during retrograde chronic pyelonephritis in rats

Retrograde pyelonephritis was induced in inbred Fischer rat kidneys with Proteus mirabilis (1 X 10(8) organisms/ml). Sera from pyelonephritic animals sacrificed at 4 and 6 weeks contained cytotoxic antibodies to cultured syngeneic 51Cr-labeled kidney tubular cells (p less than 0.02 and p less than 0.05, respectively) which could be absorbed with plasma membranes. Immune sera from 4- and 6-week pyelonephritic animals also displayed a granular fluorescent pattern along the surface of cultured kidney tubular cells. Quick-frozen syngeneic rat kidney sections stained positively with fluorescent antibody on the intraluminal side of kidney tubular cells. The results suggest that during chronic phases of pyelonephritis, auto-antibodies to kidney tubular cells are induced.     

低密度脂蛋白和氧化低密度脂蛋白诱导人肾小管上皮细胞转分化的通路研究

目的探讨低密度脂蛋白（LDL）和氧化（OX）LDL是否可诱导人肾小管上皮细胞转分化及其可能机制。方法体外培养的第2代肾小管上皮细胞随机分为（1）阴性对照组；（2）LDL（50mg／ml）组；（3）oxLDL（50mg／ml）组；（4）LDL（50mg／m1）＋PD98059（5μmol／L）组；（5）oxLDL（50mg／ml）＋PD98059（5μmol／L）组。应用形态学、免疫荧光、Western印迹观察LDL和oxLDL刺激小管细胞角蛋白（cytokerafin）、E-钙粘糖蛋白（cadhefin）、α-SMA和波形蛋白（vimenfin）表达的改变、Ⅰ型胶原产生的改变，及其与ERK1／2MAPK通路活化的关系。结果OXLDL较LDL有更强的致小管上皮细胞转分化的作用，与对照组相比。细胞中上皮细胞标记cytokeratin和E-cadherin表达减少，间充质细胞标记α-SMA和vimentin明显增加，Ⅰ型胶原产生增多（P〈0．05）。LDL和oxLDL刺激组细胞中ERK1／2MAPK和GSK-3β磷酸化活化较对照组明显增强（P〈0．05）；β-catenin发生细胞核内转移。MAPK抑制剂PD98059可抑制GSK-3β的磷酸活化，并几乎完全阻断oxLDL诱导的肾小管上皮细胞转分化，但对LDL诱导的小管上皮细胞转分化只有部分阻断作用。结论本研究首次在体外观察到（1）oxLDL可诱导肾小管细胞上皮细胞转分化和Ⅰ型胶原的产生，作用明显强于LDL；（2）ERK1／2MAPK、GSK-3β和β-catenin组成一条信号通路调节LDL和oxLDL诱导的小管上皮细胞转分化。     

Apoptosis of tubular epithelial cells in donor kidney biopsies predicts early renal allograft function.

Acute renal failure (ARF) is a serious complication in the early postoperative period after kidney transplantation. In an effort to identify subjects at risk, several donor-, recipient-, and procedure-related factors have been studied. Because no morphologic parameter predictive of delayed graft function has been identified to date, this study was conducted to determine whether the number of apoptotic cells in donor biopsies obtained before engraftment is predictive of the development of posttransplant ARF. Donor biopsies of patients with "biopsy-proven" acute tubular damage but no signs of rejection (n = 23) showed significantly higher counts of apoptotic tubular epithelial cells when compared to patients with immediate transplant function (n = 44) or early rejection (n = 22). In all groups, a significantly higher percentage of apoptotic cells was found in the distal compared to the proximal tubule. The expression of bcl-2 and proliferating cell nuclear antigen was not different among the groups. Late allograft function was not affected by early ARF as serum creatinine values were similar in all three groups after 6 mo. These data suggest that the number of apoptotic renal tubular epithelial cells in donor biopsies before engraftment is predictive of the early postoperative course in patients undergoing kidney transplantation.     

Transdifferentiation of distal but not proximal tubular epithelial cells from human kidney in culture.

Human renal proximal and distal (thick ascending limb and early distal convoluted tubule) epithelial cells have been isolated according to their specific antigen expression. The cells were well characterized by flow cytometry, enzyme cytochemistry and electron microscopy and cultured for up to 3 months. Cultured tubular cells coexpressed cytokeratin and vimentin as intermediate filament proteins. While primary isolated cells, proximal as well as distal, revealed the phenotypic characteristics of their nephron origin, cultured distal cells showed the tendency to dedifferentiate/transdifferentiate. Distal cells lost their characteristic expression of Tamm-Horsfall glycoprotein and started de novo expression of the proximal marker proteins aminopeptidase M, gamma-glutamyl transferase and dipeptidyl peptidase IV. The expression of these antigens by distal cells could be shown by flow-cytometric analysis and fluorescence microscopy. Enzyme activity assays revealed the activity of aminopeptidase M, gamma-glutamyl transferase and dipeptidyl peptidase IV, but not of the proximal marker enzyme alkaline phosphatase. This antigenic shift could not be prevented in different culture media, and the original phenotype could not be restored. Cultured cells displayed characteristic hormonal stimulation patterns indicative of their proximal and distal origins, as shown by activation of adenylate cyclase by different peptide hormones. These results indicate that distal tubular cells possibly transdifferentiate to a more proximal phenotype in view of loss of the distal marker enzyme Tamm-Horsfall protein and de novo expression of proximal marker enzymes like dipeptidyl peptidase IV and aminopeptidase M.     

Immunological function of tubular epithelial cells: the functional implications of CD40 expression

Tubulo-interstitial inflammation in the kidney is characterized by the presence of activated T cells. Both by the local production of cytokines, as well as by direct cell-cell interactions, these activated T cells might affect the immune and inflammatory response. Recently it has been demonstrated that these kidney-infiltrating T cells express CD40 ligand and that tubular epithelial cells (TECs) express CD40. In the present review we will discuss the potential implications of CD40-CD40L interactions for the activation of TECs and its immunological function.     

Fluorescent imaging of acute mercuric chloride exposure on cultured human kidney tubular epithelial cells

BACKGROUND: Imaging of intracellular mercuric ion is necessary for mechanism of renal toxicity of exposure to HgCl2. The distribution of Hg2+ inside a living cell, however, is still invisible due to the lack of high selective and sensitive fluorescent molecular probe for Hg2+. METHODS: A new fluorescent probe, EPNP, was applied to the cultured cells of human kidney proximal tubular epithelial cell line (HKC) in the presence of HgCl2 and some other bivalent ions. The relative fluorescence intensity of EPNP was measured and fluorescence images were taken by laser scanning confocal microscope. RESULTS: Results showed it led to an Hg2+ concentration- and time-dependent increase in fluorescence intensity, and responded weakly for some other heavy and transition metal ions. It could be seen during acute exposure on HKC cells, Hg2+ locate perinuclear, and on nuclear membrane, which was beyond what one knew before. CONCLUSION: EPNP is a real-time and on-line probe for imaging Hg2+ in a living cell due to its high selectivity and sensitivity for Hg2+ and slow bleaching/fading. Both the probe and the new results about the distribution of intracellular Hg2+ may be helpful for relevant biologic research.