大肠杆菌脂多糖和氢化考的松诱导胸腺细胞凋亡的实验研究

用琼脂糖凝胶电泳、电镜等方法研究大肠杆菌脂多糖（ＬＰＳ）和氢化考的松所致的小鼠胸腺细胞凋亡，以建立适于实验的细胞凋亡模型，并确定了凋亡模型的最佳用药剂量和时相。实验结果表明，ＬＰＳ和氢化考的松均可诱导小鼠胸腺细胞发生凋亡，ＬＰＳ腹腔注射量为２５μｇ／只时造模较为适宜，造模最佳时相为腹腔注射１８ｈ，氢化考的松模型经测定其最佳时相为肌肉注射２４ｈ。两种凋亡模型比较，ＬＰＳ模型造模时间短（仅需１８ｈ），     

双歧杆菌表面分子对LPS在小鼠体内调节胸腺细胞凋亡？…

目的 研究双歧杆菌表面分子细胞壁肽聚糖（ＷＰＧ）、脂磷壁酸（ＬＴＡ）对ＬＰＳ体内诱导小鼠胸腺细胞凋亡的调节。方法 用ＤＮＡ凝胶电泳、ＴＵＮＥＬ法检测ＷＰＧ、ＬＴＡ对ＬＰＳ体内诱导小鼠胸腺细胞凋亡的影响,并分别用生物活性和Ｇｒｉｅｓｓ反应测定ＷＰＧ、ＬＴＡ、ＬＰＳ体外诱生ＴＮＦ－α、ＮＯ２的含量。结果 ＷＰＧ,ＬＴＡ可显著抑制ＬＰＳ体内诱导的小鼠胸腺细胞的凋亡。ＷＰＧ、ＬＴＡ单独刺激巨噬细胞时所诱生     

双歧杆菌表面分子对LPS在小鼠体内调节胸腺细胞凋亡的观察

目的研究双歧杆菌表面分子细胞壁肽聚糖（ＷＰＧ）、脂磷壁酸（ＬＴＡ）对ＬＰＳ体内诱导小鼠胸腺细胞凋亡的调节。方法用ＤＮＡ凝胶电泳、ＴＵＮＥＬ法检测ＷＰＧ、ＬＴＡ对ＬＰＳ体内诱导小鼠胸腺细胞凋亡的影响,并分别用生物活性法和Ｇｒｉｅｓｓ反应测定ＷＰＧ、ＬＴＡ、ＬＰＳ体外诱生ＴＮＦ－α、ＮＯ２－的含量。结果ＷＰＧ、ＬＴＡ可显著抑制ＬＰＳ体内诱导的小鼠胸腺细胞的凋亡。ＷＰＧ、ＬＴＡ单独刺激巨噬细胞时所诱生的ＴＮＦ－α、ＮＯ的量显著低于ＬＰＳ刺激时所产生的这两种活性介质的量,而ＷＰＧ、ＬＴＡ与ＬＰＳ共同应用时可显著降低ＬＰＳ诱导巨噬细胞产生的ＴＮＦ－α、ＮＯ的量;诱生型一氧化氮合成酶抑制剂Ｓ－甲基异硫脲硫酸盐体外可抑制巨噬细胞产生的ＮＯ的量,在体内可部分抑制ＬＰＳ诱导的小鼠胸腺细胞的凋亡。结论ＷＰＧ、ＬＴＡ与ＬＰＳ共同应用时,可抑制ＬＰＳ诱导的巨噬细胞产生的ＴＮＦ－α、ＮＯ的量,从而下调ＬＰＳ体内诱导小鼠胸腺细胞的凋亡     

Protection of growth hormone on apoptosis of murine thymocytes induced by dexamethasone

目的:研究生长激素(GH)对地塞米松(Dex)诱导小鼠胸腺细胞凋亡的作用及机制.方法:建立地塞米松诱导小鼠胸腺细胞凋亡模型,通过观察小鼠胸腺指数的变化、形态学改变,TdT缺口末端标记(TUNEL)及流式细胞仪检测,研究生长激素影响胸腺细胞凋亡情况,并运用免疫组织化学观察生长激素对小鼠胸腺凋亡蛋白Bax和Bcl-2表达的调节.结果:经生长激素处理后,电镜下观察小鼠胸腺细胞凋亡现象明显改善;TUNEL检测和流式细胞仪检测结果显示,胸腺细胞凋亡数量减少;图像分析系统测定光密度值显示,生长激素处理组小鼠胸腺细胞中Bax表达较模型组降低,Bcl-2表达增加.结论:生长激素对地塞米松诱导的小鼠胸腺细胞凋亡具有一定的抑制作用,这种作用可以通过调节凋亡蛋白Bax、Bcl-2的表达等途径实现.     

BAD和Bcl-X/L基因在小鼠胸腺细胞凋亡时的表达及其意义

目的检测BAD和Bcl-X/L基因在小鼠胸腺细胞凋亡的表达,探讨细胞凋亡调控基因在小鼠胸腺细胞凋亡时的作用。方法应用免疫组织化学染色法,观察不同剂量糖皮质激素诱导的小鼠胸腺细胞凋亡时BAD和Bcl-X/L基因的表达。结果免疫组织化学结果表明,正常对照组胸腺内BAD呈低表达,地塞米松组随剂量的增加BAD的表达成递增趋势,地塞米松各组与对照组比较差异有有统计学意义(P<0.05);正常对照组胸腺内Bcl-X/L呈高表达,地塞米松组随剂量的增加Bcl-X/L的表达成递减趋势,地塞米松各组与对照组比较差异有统计学意义(P<0.05)。结论促凋亡蛋白BAD和抗凋亡蛋白Bcl-X/L在糖皮质激素诱导引起的胸腺细胞凋亡调控中起重要作用。     

人参提取物对内毒素所致小鼠脾细胞损伤的保护作用

目的 观察人参提取物在内毒素脂多糖(LPS)所致的SIRS／MODS中对脾细胞的作用。方法 通过HE、TUNEL染色和透射电镜比较注射人参提取物(GS)后再注射LPS时的脾脏形态学及凋亡情况，并用免疫组织化学的方法检测Bcl-2，Fas，FasL的表达。结果 随LPS作用时间的延长，脾损伤逐渐加重。动脉周围淋巴鞘细胞碎片及TUNEL阳性细胞增多，电镜观察可见到凋亡的淋巴细胞。而人参组细胞损伤明显减轻。Bcl-2的表达随着LPS作用时间的延长而减少，Fas，FasL则增强。人参提取物主要阻止Bcl-2表达减少。结论 人参提取物对LPS脾细胞损伤有保护作用，其作用机制与增强Bcl-2表达有关。     

人参皂甙Rg1对帕金森病小鼠黑质JNK细胞凋亡通路的影响

目的 探讨人参皂甙Rg1(ginsenoside Rg1)抗帕金森病(PD)小鼠黑质神经元凋亡的可能机制。方法 采用MPTP制备帕金森病(PD)小鼠模型，经人参皂甙Rgl预处理后，用尼氏染色、TH和活化型caspase-3组织化学染色及TUNEL染色法观察黑质神经元的损害情况，并计算神经元的凋亡率，同时应用蛋白免疫印迹法检测黑质神经元磷酸化．JNK(c—Jun氨基末端激酶)及磷酸化c—Jun蛋白表达水平。结果 人参皂甙Rg1预处理可减轻PD小鼠黑质致密带Niss1阳性神经元和TH阳性神经元的丢失现象，同时减少磷酸化．INK及磷酸化C-Jun蛋白表达水平，活化型caspase-3表达减少，降低黑质神经元的凋亡率。结论人参皂甙Rg1能减少MPTP诱导的小鼠黑质神经元凋亡，其机制与阻断．JNK细胞凋亡通路激活有关。     

地塞米松诱导小鼠胸腺凋亡的形态学及组织化学研究

地塞米松诱导小鼠胸腺凋亡的形态学及组织化学研究陈英杰孙品伟朱小辉（北京医科大学组织学与胚胎学系）采用半薄切片技术研究小鼠胸腺内细胞凋亡。对ＢＡＬＢ／ｃ小鼠腹腔内注射地塞米松诱发胸腺细胞凋亡，制成凋亡模型。于注射后１、７、１５、１９、３０ｈ取材，常规电...     

枸杞多糖对小鼠胸腺细胞程序化死亡的影响

采用电镜、ＤＮＡ琼脂糖电泳和ＦＡＣＳ分析的方法，对枸杞多糖（ＬＢＰ）对小鼠胸腺细胞凋亡的效应进行了研究。结果发现１００μｇ／ｍｌ和４００μｇ／ｍｌＬＢＰ可明显抑制小鼠胸腺细胞培养７小时和２４小时自发出现的细胞凋亡（ａｐｏｐｔｏｓｉｓ），而对１０－７ｍｏｌ／Ｌ地塞米松诱导的细胞凋亡则没有影响。说明ＬＢＰ具有抑制小鼠胸腺细胞自发凋亡的作用，显示出枸杞多糖的一种新的免疫调节效应。     

白色念珠菌诱导小鼠胸腺细胞凋亡

目的　研究白色念珠菌（ 白念菌） 在体内对小鼠胸腺细胞凋亡的诱导作用。方法　小鼠经尾静脉注射白念菌后,以流式细胞仪（ＦＣＭ） 分析、ＤＮＡ 琼脂糖凝胶电泳分析及细胞形态学改变为指标检测细胞凋亡。静脉注射ＮＯＳ 抑制剂观察对白念菌诱导胸腺细胞凋亡的影响。结果　白念菌能诱导小鼠胸腺细胞产生特征性的细胞凋亡形态学改变;流式细胞仪分析显示特征性的凋亡峰;琼脂糖凝胶电泳显示胸腺细胞出现典型的ＤＮＡ“梯状带”;用荧光染色（ＡＯ＋ ＥＢ） 以及ＦＣＭ 检测凋亡细胞百分率,发现白念菌注射后２４ 小时,胸腺细胞凋亡百分率随白念菌剂量增加而增高;用４ ×１０６ 白念菌经尾静脉注射后,胸腺细胞凋亡百分率于６ 小时开始增高,２４ 小时达高峰,以后迅速降低;小鼠胸腺萎缩,胸腺重量于１２ 小时明显降低,且于７２ 小时达到最低水平;ＮＯＳ 抑制剂氨基胍仅能部分抑制白念菌诱导的小鼠胸腺细胞凋亡;热灭活的白念菌不能诱导胸腺细胞凋亡。结论　白念菌菌血症能诱导小鼠胸腺细胞凋亡,而且呈时间和剂量依赖性;白念菌诱导小鼠胸腺细胞凋亡有赖于真菌的代谢;白念菌诱导小鼠胸腺细胞凋亡的过程可能与ＮＯ 部分相关。     

重症肌无力患者胸腺细胞凋亡障碍与Fas表达异常的关系

目的 :探讨重症肌无力 (MG)胸腺细胞凋亡异常、Fas表达异常在自身免疫应答形成中的作用。方法 :用手术切除的MG患者的胸腺 ,制备胸腺提取液和胸腺细胞悬液 ,用MTT比色法测定胸腺细胞的增殖 ;用DNA电泳及细胞形态学观察细胞凋亡 ;用流式细胞仪检测细胞表面Fas的表达 ,用RT PCR结合单链多态构象性分析 (SSCP) ,探讨Fas基因的转录及可能存在的Fas基因突变。结果 :MG患者的胸腺提取液 ,能抑制正常胸腺细胞增殖 ,但不能抑制MG患者胸腺细胞增殖。在地塞米松作用下 ,正常人及患者胸腺细胞的增殖均可被抑制 ,细胞增殖抑制率分别为 5 8.33%和 5 4 .2 6 %。MG患者胸腺细胞的DNA电泳可见梯状条带 ,并且胸腺细胞上Fas的表达百分率增加 [(2 0 .38± 6 .0 7) % ],与空白对照组 [(12 .4 3±4 .32 ) % ]相比较P <0 .0 5。对MG患者胸腺细胞FasmRNA进行RT PCR SSCP分析 ,部分MG患者出现异常电泳条带。结论 :MG患者胸腺细胞的凋亡及Fas分子表达均异常 ,而且存在Fas基因突变 ,提示与本病的发生发展有关。     

In vivo induction of apoptosis (programmed cell death) in mouse thymus by administration of lipopolysaccharide.

In vivo administration of bacterial lipopolysaccharide to mice induced DNA fragmentation in the thymus. Fragmented DNA was confirmed by agarose gel electrophoresis and laser flow cytometry. DNA fragmentation was predominantly detected in the thymus of young mice, while it was undetectable in the spleen, bone marrow, and lymph nodes. DNA fragmentation in the thymus was roughly dependent on the dose of lipopolysaccharide injected and reached the peak about 18 h after the injection. The addition of lipopolysaccharide to in vitro cultures of thymocytes did not cause DNA fragmentation, suggesting that lipopolysaccharide was unable to induce apoptosis of thymocytes directly. The injection of lipopolysaccharide induced no significant DNA fragmentation in adrenalectomized mice. The injection of anti-tumor necrosis factor alpha antibody together with lipopolysaccharide partially inhibited the appearance of DNA fragmentation in the thymus. On the basis of the fact that DNA fragmentation is one of the characteristics typical in apoptotic cell death, it was suggested that lipopolysaccharide could induce apoptosis in the mouse thymus in vivo. This apoptosis in the thymus might be mediated mainly by the adrenal hormones, but it is likely that tumor necrosis factor alpha might also participate in it.     

CD4单克隆抗体在体内诱导小鼠胸腺细胞凋亡

为研究抗ＣＤ４ ＭｃＡｂ引起胸腺细胞减少的机理，本课题探讨了ＣＤ４ ＭｃＡｂ诱导胸腺细胞发生凋亡的可能性。小鼠注射抗ＣＤ４ ＭｃＡｂ后，皮质胸腺细胞体积缩小，染色质凝聚；ＰＩ染色后经流式细胞计测定，显示大量的亚二倍体细胞（凋亡细胞，Ａｐｏｐｔｏｔｉｃ ｃｅｌｌｓ），与正常小鼠相比Ｐ〈０．００１；片断化ＤＮＡ的百分比也明显高于正常小鼠，Ｐ〈０．０１。片断化ＤＮＡ在凝胶电泳上呈现典型的阶梯现象。细胞内     

鲑鱼鱼白DNA对老龄小鼠胸腺淋巴细胞构成的影响

目的：探讨外源性核酸对自然衰老小鼠CD3^ 、CD3^ CD4^ 和CD3^ CD8^ 胸腺淋巴细胞构成的影响。方法：10月龄雌性Balb/c小鼠按体质量随机分为高剂量组、低剂量组和对照组。5周后，测定胸腺脏器指数；胸腺组织切片后以Image-pro Plus专业图像分析系统（4.0版）计数胸腺细胞；采用直接免疫荧光流式细胞术检测老龄小鼠胸腺细胞CD3^ 、CD3^ CD4^ 和CD3^ CD8^ 的表达情况。结果：鲑鱼鱼白DNA提取物对小鼠的体质量、胸腺质量和胸腺指数均没有影响，但可增加小鼠的胸腺皮质和髓质细胞数量，并提高CD3^ 、CD3^ CD4^ 和CD3^ CD8^ 淋巴细胞的比例，而对CD3^ CD4^ 和CD3^ CD8^ 淋巴细胞的比值没有影响。结论：补充鲑鱼鱼白DNA可能改变自然衰老Balb/c小鼠胸腺细胞的构成，使胸腺有效细胞数量增加，从而可能延缓胸腺的退化萎缩。     

IL—2,IL—6对地塞米松诱导小鼠胸腺细胞凋亡的调节作用

目的：以Ｄｅｘ诱导小鼠胸腺细胞凋亡为模型,研究细胞因子（ＩＬ－２、ＩＬ－６）对小鼠胸腺细胞凋亡的调节作用。方法：应用ＰＩ法检测亚二倍体细胞,二苯胺法测定胸腺细胞片段化ＤＮＡ含量（％）,ＤＮＡ凝胶电泳,流式细胞计分析胸腺细胞表型、测定高钙细胞百分比。结果：发现地塞米松（Ｄｅｘ）与小鼠胸腺细胞共同培养引起细胞凋亡,胸腺细胞减少以ＣＤ４^ ＣＤ８^ 细胞最明显。细胞凋亡具有时间效应并与Ｄｅｘ浓度有关。３～４     

Effect of intrauterine exposure of murine fetus to cyclophosphamide on development of thymus

The objective of this study was to demonstrate thymic alterations produced by cyclophosphamide intervention during intrauterine life of murine fetus. Cyclophosphamide (CP) was administered to pregnant mice on day 11 of gestation in a single dose of 10 mg/kg body weight. Fetuses were dissected out on day 19 and studied for various effects on thymus. Thymus of fetuses exposed to cyclophosphamide showed thymic atrophy with retardation of thymic size and a remarkable shrinkage in lobular morphology. Histological studies showed a massive depletion of thymic cortex. Study of thymocytes revealed an increase in apoptotic cell count and percent DNA fragmentation along with a decrease in proliferation. Thymocytes obtained from fetuses of CP-treated mice showed a higher expression of caspase-activated DNase (CAD) indicating that the CP-dependent induction of apoptosis in thymocytes involved caspase pathway. The results of the present study may help in understanding the mechanism of the teratogenic effect of cyclophosphamide on thymus.     

Effect of Intrauterine Exposure of Murine Fetus to Cyclophosphamide on Development of Thymus

The objective of this study was to demonstrate thymic alterations produced by cyclophosphamide intervention during intrauterine life of murine fetus. Cyclophosphamide (CP) was administered to pregnant mice on day 11 of gestation in a single dose of 10 mg/kg body weight. Fetuses were dissected out on day 19 and studied for various effects on thymus. Thymus of fetuses exposed to cyclophosphamide showed thymic atrophy with retardation of thymic size and a remarkable shrinkage in lobular morphology. Histological studies showed a massive depletion of thymic cortex. Study of thymocytes revealed an increase in apoptotic cell count and percent DNA fragmentation along with a decrease in proliferation. Thymocytes obtained from fetuses of CP-treated mice showed a higher expression of caspase-activated DNase (CAD) indicating that the CP-dependent induction of apoptosis in thymocytes involved caspase pathway. The results of the present study may help in understanding the mechanism of the teratogenic effect of cyclophosphamide on thymus.     

Apoptosis of murine thymocytes induced by extracellular ATP is dose- and cytosolic pH-dependent

Thymocytes from young Balb/C mice responded to low extracellular ATP (ATPec) doses (< or = 0.3 mM) with a rapid intracellular acidification (mean pH: ca. 0.3 pH unit) that was inhibited by the Ca2+ channel blocker verapamil, or by suramin (50 microM) and TNP-ATP (40 microM), potent P2x (and P2y) purinoreceptor antagonists. ATPec also triggered a remarkable DNA fragmentation and cell shrinkage detectable only at these low doses. DNA fragmentation gradually disappears with increasing [ATPec] above 0.5 mM, with a concomitant dominance of cytosolic alkalinization of the cells. Suramin and TNP-ATP also blocked the ATPec-triggered DNA fragmentation efficiently. oATP, inhibitor of P2z nonspecific ATP-gated membrane pores, and 2 mM extracellular Mg2+ did not influence either the cytosolic acidification or the DNA fragmentation, but almost completely abolished the intracellular alkalinization characteristic of P2z receptor activation at high ATPec doses. Antagonist-sensitivity of the ATPec-induced membrane potential responses indicates that hyperpolarization is associated with intracellular acidification, while rapid depolarization is linked to alkalinization. These data together indicate that the Ca2+-dependent hyperpolarization and cytosolic acidification triggered by low ATPec doses are essential early signals in apoptosis of murine thymocytes and are likely mediated by P2x1 type ATP-gated ion channels. Subset specificity of the early purinergic signals suggests that the double positive thymocytes are most sensitive to ATPec showing both P2z and P2x receptor activation characteristics, the double negative thymocytes preferentially show P2z-type, while single positive (CD4- CD8+ or CD4+ CD8-) thymocytes respond mostly by weaker P2x-type changes, indicating that ATPec, similarly to adenosine may serve as a potential regulator of cell death and differentiation in the thymus.     

Massive telomere loss and telomerase RNA expression in dexamethasone-induced apoptosis in mouse thymocytes

Apoptosis is a well-recognized process of cell death occurring under several physiological and pathological conditions and represents the principal mechanism involved in cell selection in the thymus. Glucocorticoids are well known to stimulate apoptosis in rat thymocytes. However, it is unclear whether the same changes occur after in vivo glucocorticoid treatment in mice. Chromosomal stability and cell viability require a proficient telomeric end-capping function. Cells with critical telomere shortening and telomerase dysfunction undergo increased apoptosis. In turn, the change in telomere function in cells undergoing apoptosis is not fully characterized. In order to investigate this, we studied the changes in thymocytes after dexamethasone administration in BALB/c mice. The loss of normal thymocytes coincided with the appearance of small dense cells with characteristic features of apoptosis including condensed chromatin, internucleosomal DNA cleavage, and a "hypodiploid" peak on flow cytometry, which suggested that dexamethasone-induced thymocyte apoptosis in BALB/c mice could be considered a well-defined experimental model for studying apoptotic processes. Dexamethasone-treated thymocytes exhibited rapid and dynamic loss of telomeric sequences and up-regulation of telomerase RNA as an early event in the apoptotic process. Telomerase activity was unchanged in this event. Thereafter, telomere gain associated with an increase in telomerase activity occurred in the regenerative process of the thymus. These results suggest a role of telomere loss and up-regulation of telomerase RNA as key apoptosis sensors.     

Induction of Apoptosis in Mouse Thymocytes by Cyclosporin A: An In Vitro Study

The effect of cyclosporin A (CsA) on mouse thymocytes was investigated in vitro. Ultrastructural examination and DNA electrophoresis of 24hr-CsA-treated thymocytes showed chromatin condensation, cellular shrinkage and nuclear fragmentation in oligonucleosomal fragments. DNA labeling of CsA-treated-thymocytes with propidium iodide (PI) showed an increase in the number of apoptotic nuclei compared to untreated thymocytes. Furthermore, flow cytometric analysis using monoclonal antibodies (mAbs) specific to particular thymocyte subsets showed that CsA induces a decrease in the relative number of immature double positive (DP) CD4+CD8+ thymocytes in direct proportion to the concentration of CsA. No significant changes were observed in mature single positive (SP) CD4+CD8-and CD8+CD4-cells. Moreover, the cell viability of CsA-treated thymocytes was decreased. These results suggest that CsA induces the programmed cell death of thymocytes in vitro. Taken together with our previous study on the in vivo effect of CsA on mouse thymus and thymocytes, the present study confirms that, in addition to its effect on the thymic epithelium, CsA acts directly on thymocytes by inducing their programmed cell death. We postulate that immature DP thymocytes are the most likely targets of CsA.