纤维连接蛋白对支气管上皮细胞抗氧化损伤保护作用的研究

目的和方法：为验证整合素分子激活对支气管上皮细胞（BEC）的抗氧化性保护作用,本实验用臭氧（O3）攻击培养的兔BEC,测定细胞的^3H释放率、乳酸脱氢酶（LDH）释放活性及脂质过氧化产物丙二醛（MDA）含量,反映细胞损伤程度;观察纤维连接蛋白（Fn）及人工合成的精－甘－天冬氨酸片段（RGD肽）的保护效应。结果：①臭氧攻击使BEC的^3H释放率增高,Fn处理可减少臭氧所致的^3H释放,钙调素抑制剂W7能抑制Fn的这一作用,RGD可减轻臭氧所致的^3H释放;②臭氧攻击后细胞上清液中LDH释放增多,Fn或RGD处理均能降低LDH释放,W7阻断Fn的这一效奕;③臭氧作用后明显提高细胞内MDA含量,Fn或RGD可降低MDA含量;④臭氧攻击使细胞内GSH含量下降,Fn或RGD可增加BEC内GSH的含量;⑤Fn可增强BEC内过氧化氢酶（CAT）活性,但可被W7阻断,RGD则显示有剂量依赖性促进作用。结论：Fn及其特异识别片段与BEC的整合素分子结合后,可减轻臭氧对BEC细胞的损伤,其机理与经钙调素途径上调BEC抗氧化能力有关。     

表皮生长因子对培养的气道上皮细胞抗臭氧损伤的保护作用

本研究观察到臭氧（Ｏ３）对体外培养经３Ｈ－ＵｄＲ标记的免气道上皮细胞有明显细胞毒性作用,且损伤程度与Ｏ３作用时间呈正相关。Ｏ３暴露组细胞内丙二醛（ＭＤＡ）产生增多（Ｐ＜０．０１）,提示Ｏ３损伤细胞的机制与胞膜脂质过氧化有关。表皮生长因子（ＥＧＦ）可明显降低Ｏ３所致的３Ｈ释放率（Ｐ＜０．０１）、降低Ｏ３的细胞毒指数及细胞内ＭＤＡ含量（Ｐ＜０．０１）,证明ＥＧＦ对气道上皮细胞有保护作用。进一步还观察到浓度为５ｎｇ／ｍｌ的ＥＯＦ可以取消Ｏ３所引起的细胞内还原型谷胱甘肽（ＧＳＨ）含量降低（Ｐ＜０．０１）,并增加细胞内谷胱甘肽总含量（Ｐ＜０．０５）,但不能改变Ｏ３所致的氧化型谷胱甘肽（ＧＳＳＧ）含量的增加（Ｐ＞０．０５）,对ＧＳＨ／ＧＳＳＧ比值也无明显提高,这些都提示ＥＧＦ的细胞保护机理可能与其促进细胞内谷胱甘肽合成有关,而对ＧＳＳＧ转化为ＧＳＨ的还原过程影响不明显。     

哮喘气道重塑大鼠气道上皮细胞及线粒体超微结构变化

目的探讨哮喘气道重塑大鼠气道上皮细线粒体超微结构变化,为哮喘的治疗寻求新的理论基础。方法雌性Wistar大鼠6只、随机分为2组,采用卵蛋白吸人法制作哮喘气道重塑大鼠模型;取两组大鼠气管制作电镜切片,观察两组大鼠气道纤毛上皮,气道上皮细胞问胶原沉积及细胞内线粒体超微结构改变。结果哮喘组大鼠气道多层纤毛上皮层,纤毛脱落,杯状细胞增多,排列不整齐,上皮细胞中线粒体基膜密度下降,线粒体峡减少,上皮细胞细胞核多切迹,形状不规则;气道上皮细胞间胶原沉积;板层小体和线粒体空泡化。结论哮喘大鼠气道上皮细胞出现早期凋亡改变,线粒体失去正常形态。     

支气管上皮细胞在气道高反应中的作用

气道高反应的发病机制目前仍然不清楚,但人多数人认同是气道的一种慢性炎症。近十年来,上皮缺陷学说逐渐成为解释气道高反应机制的主流观点。气道上皮不再被仅仅看作为单纯的机械屏障,而是机体内环境与外部环境相互作用的界面。气道上皮具有广泛的生理作用,包括抗氧化、内分泌和外分泌、黏液运输、生物代谢、结构性黏附、损伤修复、应激或炎症信号传递、抗原递呈作用等。借助这些生理作用,支气管上皮细胞在气道局部微环境稳态维持中发挥重要作用。有理由相信,气道上皮的结构完整性缺陷或功能紊乱是哮喘和慢性阻塞性肺疾病等气道高反应性疾病的启动环节。     

谷氨酰胺对体外培养人小肠上皮细胞缺氧复氧损伤的保护作用

应用原代培养人胎小肠上皮细胞（ＩＥＣ）,观察了谷氨酰胺（ＧＬＮ）对缺氧复氧（Ａ／Ｒ）损伤人ＩＥＣ的影响。结果：缺氧６０ｍｉｎ复氧３０ｍｉｎ后,细胞内乳酸脱氢酶（ＬＤＨ）漏出量显著上升,细胞存活率显著下降。预先应用１～５ｍｍｏｌ／ＬＧＬＮ可使Ａ／Ｒ损伤ＩＥＣ细胞存活率升高和细胞内ＬＤＨ漏出量减少,ＧＬＮ作用的最佳剂量为２ｍｍｏｌ／Ｌ。提示ＧＬＮ对人ＩＥＣ具有直接的保护作用,这可能是其整体保护作用机制之一。     

血管活性肠肽对兔支气管上皮细胞抗臭氧损伤的保护作用

用支气管刷洗法收集新西兰兔支气管上皮细胞（ＢＥＣ）,以臭氧（Ｏ３）攻击培养的ＢＥＣ,建立细胞损伤模型。测定ＢＥＣ的３Ｈ释放率计算Ｏ３的细胞毒指数（ＣＩ）、测定细胞内丙二醛（ＭＤＡ）的含量反映细胞氧化性损伤的程度,测定细胞内过氧化氢酶（ＣＡＴ）活性及还原型和氧化型谷胱甘肽（ＧＳＨ和ＧＳＳＧ）的含量反映细胞抗氧化能力。观察血管活性肠肽（ＶＩＰ）预处理对ＢＥＣ的细胞保护作用并初步探讨其保护机制。观察到：ＢＥＣ的３Ｈ释放率与Ｏ３暴露时间成正比;Ｏ３暴露２ｈ使ＭＤＡ含量和ＧＳＳＧ含量明显增加,ＧＳＨ减少;ＶＩＰ预处理呈剂量依赖性降低Ｏ３暴露的ＣＩ值、降低ＭＤＡ和ＧＳＳＧ含量、增加ＧＳＨ及ＧＳＨ／ＧＳＳＧ比值、增加ＣＡＴ活性,显示出细胞保护效应;ＶＩＰ的保护效应可被放线菌素Ｄ（Ａ－Ｄ）或蛋白激酶Ｃ阻断剂Ｈ７部分取消。结果表明：Ｏ３暴露会导致ＢＥＣ损伤,ＶＩＰ可通过增强ＢＥＣ的抗氧化能力而保护ＢＥＣ,ＶＩＰ的信号在细胞内的转导途径与基因转录及依赖ＰＫＣ的酶蛋白磷酸化有关。     

支架蛋白IQGAP1参与气道上皮细胞损伤修复过程

气道上皮损伤修复过程包括细胞延伸、迁移和增殖.IQGAP1 (IQ domain GTPase-activating protein 1)是一个在许多细胞生命活动中非常有意义的蛋白,但其在肺上皮细胞中的作用尚未阐述清楚.本文采用目前广泛应用的刮伤气道上皮细胞的体外模型来研究IQGAP1的功能.结果显示,IQGAP1在小鼠、大鼠、猪和人气道上皮细胞中有丰富表达.它与微管骨架共定位,可被微管解聚剂nocodazole破坏.刮伤6～9h后,IQGAP1 mRNA及蛋白表达上调.过表达外源性IQGAP1导致β-catenin核转位,从而活化Tcf/Lef信号.此外,刮伤还影响IQGAP1与β-catenin、结肠腺瘤病(adenomatous polyposis coli, APC)蛋白及细胞质连接蛋白-170 (cytoplasmic linker protein-170, CLIP-170)之间的相互作用.通过小干扰RNA (small interference RNA, siRNA)沉默IQGAP1表达则明显延迟损伤愈合.结果提示,IQGAP1信号参与气道上皮细胞损伤修复过程.     

糖原合酶激酶3β和腺瘤性结肠息肉病蛋白在气道上皮细胞机械损伤修复过程的时空分布

为了探讨糖原合酶激酶3β（glycogen synthase kinase 3β,GSK3β）和腺瘤性结肠息肉病（adenomatous polyposis coli, APC）蛋白在气道上皮细胞（airway epithelial cells,AECs）损伤和修复中的作用,我们采用机械划线损伤的方法建立体外气道上皮损伤修复模型,采用Western blot、免疫荧光双标共聚焦成像和免疫沉淀的方法观察损伤修复过程中APC蛋白和GSK3β在AECs中表达及分布的动态变化。结果显示：（1）用Western blot方法观察到划线损伤0．5 h后即有GSK3β磷酸化增强（P〈 0．05）,6 h达到高峰（P〈0．05）,持续到12 h（P〈0．05）,24 h开始下降,而GSK3β总量大致保持一致。（2）在免疫荧光双标共聚焦成像实验中,划线损伤0 h组APC蛋白主要表达于胞浆,而划线损伤6 h后APC蛋白主要聚集于损伤前沿区的迁移活跃细胞。（3）免疫共沉淀的实验结果显示,划线损伤0 h时GSK3B和APC蛋白能共同沉淀,但在划线损伤6 h之后,两者发生了分离。以上结果表明：划线损伤后AECs立即启动修复过程,此时GSK3B的活性被抑制,促使APC蛋白游离出来;游离出来的APC蛋白则与微管正极结合,增加了微管的稳定性,从而调节细胞骨架运动,促进气道上皮的损伤修复。     

茶多糖的抗氧化活性及对细胞氧化损伤的保护机制

茶多糖是一种从茶叶中提取的酸性糖蛋白,具有良好的抗氧化活性。以自由基清除率为指标,分析皖西南地区夏秋茶多糖的抗氧化活性,基于H₂O₂和EDTA-Fe²⁺建立的外源性羟基自由基(·OH)损伤细胞模型和PMA诱导内源性羟基自由基损伤模型,进一步探讨茶多糖对自由基损伤的修复作用机制。结果表明,茶多糖具有良好的体外抗氧化活性,对DPPH·和·OH均具有较强的清除效果,EC₅₀值分别为209.5和535.2μg·mL^–1,最大清除效率与Vc相当。细胞增殖实验表明,外源性和内源性自由基氧化损伤模型中细胞存活率均随着茶多糖浓度的增加而升高,在茶多糖浓度为800μg·mL^–1时细胞存活率分别高达87.41%和85.84%,且显著高于模型组(47.67%和48.03%)。在修复机制上,利用激光共聚焦显微镜显影细胞内活性氧(ROS)分布以及荧光强度,分析结果显示,与模型组相比,茶多糖对于细胞模型中外源和内源性ROS均具有明显的清除效果,与体外抗氧化实验结果一致。茶多糖在体外表...     

亚硒酸钠诱发的晶状体上皮细胞DNA损伤及修复

观察了亚硒酸钠（Ｎａ２ＳｅＯ３）在体外作用于大鼠晶状体上皮细胞（ＲＬＥ ｃｅｌｌｓ）而造成的ＤＮＡ单链断裂（ＳＳＢ）,并对其ＤＮＡ损伤、修复动力学做了初步研究。发现ＳＳＢ严重程度与亚硒酸钠的浓度呈线性相关,其ＳＳＢ重接修复约在３０￣６０ｍｉｎ内完成,还作了有关非程序ＤＮＡ合居（ＵＤＳ）的检测,发现与ＳＳＢ相比,ＵＤＳ发生迟且持续时间更长,提示Ｎａ２ＳｅＯ３可能在体外对大鼠晶状体上皮细胞除造成ＳＳＢ     

BIM deficiency differentially impacts the function of kidney endothelial and epithelial cells through modulation of their local microenvironment

The extracellular matrix (ECM) acts as a scaffold for kidney cellular organization. Local secretion of the ECM allows kidney cells to readily adapt to changes occurring within the kidney. In addition to providing structural support for cells, the ECM also modulates cell survival, migration, proliferation, and differentiation. Although aberrant regulation of ECM proteins can play a causative role in many diseases, it is not known whether ECM production, cell adhesion, and migration are regulated in a similar manner in kidney epithelial and endothelial cells. Here, we demonstrate that lack of BIM expression differentially impacts kidney endothelial and epithelial cell ECM production, migration, and adhesion, further emphasizing the specialized role of these cell types in kidney function. Bim -/- kidney epithelial cells demonstrated decreased migration, increased adhesion, and sustained expression of osteopontin and thrombospondin-1 (TSP1). In contrast, bim -/- kidney endothelial cells demonstrated increased cell migration, and decreased expression of osteopontin and TSP1. We also observed a fivefold increase in VEGF expression in bim -/- kidney endothelial cells consistent with their increased migration and capillary morphogenesis. These cells also had decreased endothelial nitric oxide synthase activity and nitric oxide bioavailability. Thus kidney endothelial and epithelial cells make unique contributions to the regulation of their ECM composition, with specific impact on adhesive and migratory properties that are essential for their proper function.     

免疫系统区室化与上皮细胞局部微环境中的免疫调节作用

近年来,免疫系统区室化（compartmentalization of immune system）的概念逐渐引起了人们的重视。对各类免疫及非免疫器官中的免疫区室化现象进行深入研究,有助于进一步了解机体免疫系统、免疫应答以及免疫相关疾病的发病机制,并可提供新的应对策略。上皮细胞体内广泛分布,承载机体多种重要生理功能。它作为免疫防御首道防线参与免疫系统区室化形成,并在免疫反应局部微环境中,既可与免疫细胞相互作用发挥固有免疫调节作用,亦可通过自身转分化调节后续适应性免疫应答,在抵御及清除病原体入侵、调控局部炎症免疫反应以及促进组织损伤修复中,发挥了不可或缺的重要作用。病理状态下,上皮细胞又可能是免疫稳态失衡甚或肿瘤发生发展的关键因素。结合免疫系统区室化,对上皮细胞在局部微环境中的免疫调节作用作一综述,为免疫相关疾病的研究以及临床诊疗提供新的思路和策略。     

Protection of human endothelial cells from oxidant injury by adenovirus-mediated transfer of the human catalase cDNA.

In a variety of disorders, endothelial cells are exposed to high levels of oxidants, generated within the cells and/or consequent to local inflammation. In the context of the sensitivity of endothelial cells to oxidant stress, particularly related to H2O2, we have designed a replication deficient recombinant adenovirus containing the human catalase cDNA (AdCL) to transfer the catalase cDNA to the endothelial cells, in order to augment intracellular anti-H2O2 protection. Human umbilical vein endothelial cells that were not infected or infected with control adenovirus maintained low levels of catalase mRNA. Endothelial cells infected with AdCL expressed AdCL-driven exogenous catalase mRNA, as early as 24 hr and at least for 7 days. Catalase protein levels were increased significantly over controls in cells infected with AdCL, as were catalase activity levels, with catalase activity correlated closely with levels of catalase protein. Importantly, when the endothelial cells were exposed to 500 microM H2O2, all the AdCL infected endothelial cells survived, compared to only 37% of the control cells. Thus, a recombinant adenovirus containing the human catalase cDNA is able to infect human endothelial cells in vitro and express high levels of functional intracellular catalase, protecting the cells against H2O2-mediated oxidant stress. These observations support the feasibility of the transfer of catalase cDNA to human endothelium to protect against oxidant injury.     

beta-Adrenergic agonist modulation of monocyte adhesion to airway epithelial cells in vitro

beta-Adrenergic agonists are commonly used in the treatment of obstructive airway diseases and are known to modulate cAMP-dependent processes of airway epithelial cells. However, little is known regarding the ability of cAMP-dependent mechanisms to influence cell-cell interactions within the airway. Thus we investigated the role of the beta-adrenergic agonist isoproterenol in modulating the ability of human bronchial epithelial cells to support the adhesion of THP-1 cells, a monocyte/macrophage cell line, in vitro. We demonstrated that pretreatment of human bronchial epithelial cells (HBECs) with 10 microM isoproterenol or 100 microM salbutamol augments the adhesion of fluorescently labeled THP-1 cells to HBEC monolayers by approximately 40-60%. The increase in THP-1 cell adhesion occurred with 10 min of isoproterenol pretreatment of HBECs and gradually declined but persisted with up to 24 h of isoproterenol exposure. Exposure of THP-1 cells to isoproterenol or salbutamol before the adhesion assays did not result in an increase in adhesion to HBECs, suggesting that the isoproterenol modulation was primarily via changes in epithelial cells. A specific protein kinase A inhibitor, KT-5720, inhibited subsequent isoproterenol augmentation of THP-1 cell adhesion, further supporting the role of cAMP-dependent mechanisms in modulating THP-1 cell adhesion to HBECs.     

Basal chloride currents in murine airway epithelial cells: modulation by CFTR

We have isolatedciliated respiratory cells from the nasal epithelium of wild-type andcystic fibrosis (CF) null mice and used the patch-clamp technique toinvestigate their basal conductances. Current-clamp experiments onunstimulated cells indicated the presence ofK⁺ andCl conductances and, undercertain conditions, a small Na⁺conductance. Voltage-clamp experiments revealed three distinct Cl conductances.I_tv-indep wastime and voltage independent with a linear current-voltage(I-V)plot; I_v-actexhibited activation at potentials greater than ±50 mV, giving anS-shapedI-Vplot; andI_hyp-act wasactivated by hyperpolarizing potentials and had an inwardly rectifiedI-Vplot. The current density sequence was I_hyp-act = I_v-act  I_tv-indep. Theseconductances hadCl-to-N-methyl-D-glucaminecation permeability ratios of between 2.8 and 10.3 and were unaffectedby tamoxifen, flufenamate, glibenclamide, DIDS, and5-nitro-2-(3-phenylpropylamino) benzoic acid but were inhibited byZn²⁺ andGd³⁺.I_tv-indep andI_v-act werepresent in wild-type and CF cells at equal density and frequency.However, I_hyp-actwas detected in only 3% of CF cells compared with 26% of wild-typecells, suggesting that this conductance may be modulated by cysticfibrosis transmembrane conductance regulator (CFTR).

     

骨髓间充质干细胞在组织损伤局部微环境中的调节作用

骨髓间充质干细胞(mesenchymal stem cells,MSCs)是一种具有自我增殖和多向分化潜能的细胞,植入体内后对损伤组织具有一定的修复作用,研究发现MSCs在体内的分化效率极低(不足10%),故仅用其分化能力不能完全解释它良好的修复效能。新近研究表明,MSCs可通过旁分泌途径调节损伤局部的微环境,从而促进受损组织的修复,提示这种微环境的调节较其自身分化更具有临床意义。该文对MSCs在组织损伤局部微环境中的调节作用做一简要概述,为MSCs更广阔地应用于医学领域提供理论基础。