巨噬细胞内毒素耐受时TLR4/MD-2的基因表达调节作用

目的　研究脂多糖 (LPS)的跨膜信号传导分子TLR4和MD 2在巨噬细胞内毒素耐受发生中的调节变化和作用。方法　分离小鼠腹腔巨噬细胞 ,活化组直接以 1mg/LLPS刺激一定时间 ,耐受组先用不同剂量LPS预处理 2 0h ,再用 1mg/LLPS刺激。利用逆转录 聚合酶链反应(RT PCR)测定各基因的转录调节变化。结果　在活化组细胞LPS刺激可显著诱导肿瘤坏死因子(TNF) α的基因转录和蛋白分泌 ,但是LPS预处理可使耐受组细胞TNF α的mRNA和蛋白水平均明显低于活化组 (P <0 .0 1) ;耐受组细胞中TLR4的基因表达水平也比活化组明显低 (P <0 .0 1) ,但MD 2的基因表达水平不受LPS刺激的影响。结论　内毒素耐受的巨噬细胞表现为抑制的炎症细胞因子产生 ,TLR4基因的表达下调可能是内毒素耐受发生的机制之一。     

脂多糖受体簇和大电导Ca2+活K+通道在脂多糖信号识别中的作用

背景 细菌脂多糖(lipopolysaccharide,LPS)可激活细胞合成和释放多种细胞因子,导致全身炎症反应.LPS识别及跨膜信号转导是引起细胞效应的关键,成为近年的研究热点.目的 对新近提出的“LPS受体簇”理论和大电导Ca2+激活K+通道(MaxiK)在LPS信号识别中的作用研究进展进行综述.内容 LPS与CD14结合后,不同的信号分子在脂质筏内聚集,LPS被释放到脂质双分子层,并与由多种受体分子组成的受体簇相互作用.根据不同的细胞类型和细菌刺激,形成了不同的LPS受体簇.MaxiK通道在LPS诱导的巨噬细胞信号转导过程的早期即被激活.并且以IκB-α/NF-κB为中心的促炎症反应依赖MaxiK的功能.趋向 需要进一步研究来阐明LPS受体簇在细胞膜特定区域内形成的确切分子机制,以及组成受体簇的几种蛋白分子在刺激识别和信号转导过程中的作用.     

LPS耐受巨噬细胞致炎和抗炎细胞因子表达和分泌的特点

目的：分析巨噬细胞LPS耐受形成过程中致炎和抗炎细胞因子（TNF-α、IL-6和IL-10）释放的特点和规律,探讨其在巨噬细胞建立LPS耐受机制中的作用.方法：培养小鼠腹腔巨噬细胞系RAW264.7 细胞.实验分为两部分：①LPS刺激细胞不同时间（4 h,8 h,20 h）或用PBS培养细胞4 h;②LPS耐受实验（LPS预刺激巨噬细胞20 h后,换液并洗去LPS,再次加入LPS刺激4 h）.ELISA法检测细胞培养上清中TNF-α、IL-6和IL-10的浓度,RT-PCR法相对定量分析巨噬细胞TNF-α和IL-10 mRNA 表达水平.结果：细胞培养上清中TNF-α、IL-6和IL-10的浓度随着LPS刺激时间的延长而增加;LPS刺激20 h后建立耐受的巨噬细胞再次受到LPS打击时,其TNF-α释放量低于非耐受细胞,而IL-6和IL-10释放量则大幅增加,与TNF-α释放减少截然相反.TNF-α和IL-10mRNA 表达水平与其蛋白分泌量呈现相似的变化规律.结论：巨噬细胞对LPS的耐受建立在致炎因子和抗炎因子共同作用的基础上;LPS预刺激细胞再次受到LPS打击时,抑炎因子表达和分泌大幅增加是介导巨噬细胞对LPS耐受的重要机制.     

毒性炎症介质与脓毒症性休克

随着分子生物学的发展及对脓毒症性休克(SS)和多器官功能衰竭(MOF)的深入研究,众多学者认为G~-菌感染所引起的SS及MOF均与毒性炎症介质所致的组织损害有关。迄今为止,已发现的毒性炎症介质不下200种。目前研究较多的有内毒素(ET)、肿瘤坏死因子(TNF)、血小板活化因子(PAF)、白介素(包括IL-1、IL-2及IL-6)、前列腺素E_2(PGE_2)及血栓素A_2(TxA_2)等。兹就参与G-菌所致的SS及MOF的几种常见毒性炎症介质及其拮抗药的研究作一简要介绍。一、内毒素(Endotoxin,ET) 内毒素系脂多糖(LPS)的聚合体。LPS分子的一端为亲水性基团,另一端为疏水性基团。LPS聚合链的长     

白藜芦醇对细菌脂多糖耐受的THP-1细胞TNF-α启动子区的影响

目的:探讨白藜芦醇对细菌脂多糖(LPS)耐受的人原单核细胞THP-1细胞中TNF-α启动子区的影响。方法:首先建立LPS耐受THP-1细胞模型后,然后用LPS分别刺激正常THP-1细胞(对照组)、LPS耐受THP-1细胞(耐受组)、白藜芦醇处理的LPS耐受THP-1细胞(耐受+白藜芦醇组),检测各组细胞TNF-α mRNA的表达及TNF-α启动子区各转录因子的结合情况。结果:LPS刺激后,TNF-α mRNA表达在对照组细胞迅速升高,耐受组缓慢升高,而耐受+白藜芦醇组略微升高,表达量明显低于前两组(均P0.05)。染色体免疫沉淀(ChIP)分析显示,LPS刺激前,耐受组与耐受+白藜芦醇组p65及乙酰化p65(ace-p65)、Rel B、G9a对TNF-p启动子区的结合量均明显高于对照组(均P0.05),而p50的结合量各组细胞间无统计学差异(P0.05);LPS刺激后,p65和ace-p65对TNF-α启动子区的结合量在对照组明显增加,而在耐受+白藜芦醇组明显降低,G9a结合量在对照组量明显降低(均P0.05),其余转录因子较刺激前无明显改变(均P0.05)。结论:白藜芦醇可以抑制LPS耐受的THP-1细胞中TNF-α mRNA的表达,可能部分通过抑制p65/ace-p65对TNF-α启动子区的结合,因此可考虑将白藜芦醇用于治疗脓毒症的辅助治     

甘氨酸抗内毒素性休克和肝损伤的作用及其机制

目的 探讨甘氨酸(Gly)对内毒素(ET)性休克和ET性肝损伤的作用和机制。方法 尾静脉注射脂多糖(LPS)复制小鼠ET休克和肝损伤模型，预防和治疗各组于不同的时间点注射Gly。观察死亡率。另取小鼠分为休克组和Gly治疗组，各组分别于注射LPS后1、2、4、6h观察丙氨酸转氨酶(ALT)、门冬氨酸转氨酶(AST)；肿瘤坏死因子α(TNF-α)和枯否细胞(KC)脂多糖受体(CD14)、清道夫受体(SR)和核转录因子一出(NF一出)的表达。结果 肝损伤指标和NF-kB表达与KC CD14的表达呈正相关和SR表达呈负相关。Gly对ET性休克有很好的防治作用，可降低ALT、AST和肝组织TNF-α含量，可明显下调KC CD14的表达和NFkB的表达，上调KCSR的表达，尤以4、6h为著。结论Gly可有效防治ET性休克和改善ET性肝损害，其机制与Gly阻遏KC CD14表达、增强SR的表达进而抑制KC NF-kB的活化有关。     

正常月经周期中内皮素变化规律的研究

目的 :探讨健康育龄妇女正常月经周期中血浆及子宫内膜内皮素 ( ET)的变化 ,ET和卵巢甾体激素的相关性。方法 :对 3 8名正常月经周期妇女分别于增殖早、中期 ,分泌中、晚期 ,取 4次静脉血 ,应用放射免疫方法测定血浆 ET、雌激素 ( E2 )、孕激素 ( P)含量 ,其中 2 7名妇女选择某一期 ,采血同时取内膜测定子宫内膜 ET含量。结果 :正常月经周期各阶段血浆 ET水平无明显差异。子宫内膜组织 ET,分泌中、晚期 ( 3 .90± 1 .3 0 pg/mg)显著高于增殖早、中期 ( 2 .76± 1 .2 5 pg/mg) ( P<0 .0 5 )。无论是血浆 ET还是子宫内膜组织 ET均与雌、孕激素之间无明显相关性。结论 :子宫内膜中的 ET可能通过自分泌和 (或 )旁分泌机制参与子宫出血的调节 ,并与月经的始动有关。     

内毒素耐受和拟胆碱药物对巨噬细胞分泌肿瘤坏死因子-α的影响

目的:探讨内毒素耐受和拟胆碱药物卡巴胆碱对巨噬细胞肿瘤坏死因子-α(TNF-α)分泌的调节作用.方法:①分离小鼠腹腔巨噬细胞,将其与内毒素(LPS)作用不同时间(0、2、4、8 h);②小鼠腹腔巨噬细胞分为3组:空白对照组(RPMI1640常规培养),LPS耐受组(LPS预刺激20 h,再用LPS刺激4 h)和LPS不...     

脂多糖对小鼠肺成纤维细胞Thy-1 mRNA表达的影响

目的 评价脂多糖(LPS)对小鼠肺成纤维细胞胸腺细胞分化抗原-1(Thy-1)mRNA表达的影响.方法 原代培养小鼠肺成纤维细胞接种于96孔培养板密度(1×104/ml).培养48 h后,将其分为4组(n=3):PBS对照组(C组)、0.01 μg/ml LPS组(LPS0.01组)、0.10 μg/ml LPS组(LPS0.10组)和1.00μg/ml LPS组(LPS1.00组),分别加入PBS或以上终浓度LPS,在加入后即刻、6、24、48和72 h时(T0-4),分别采用CCK-8细胞计数法检测细胞增殖水平,RT-PCR法检测细胞Thy-1 mRNA表达.结果 与C组相比,T3,4时其余组细胞增殖水平升高,Thy-1 mRNA表达下调(P＜0.05)；T3,4时LPS0.01组、LPS0.10组和LPS1.00组细胞增殖水平依次升高,Thy-1 mRNA表达依次下调(P＜0.05).结论 LPS可下调Thy-1 mRNA表达,引起小鼠肺成纤维细胞异常增殖,提示内毒素血症诱发肺纤维化与肺成纤维细胞Thy-1表达下调有关.     

外源性一氧化碳释放分子2对脓毒症时Janus激酶/信号转导和转录激活子通路活化的抑制作用

目的 了解外源性一氧化碳释放分子2(CORM2)对脓毒症时Janus激酶/信号转导和转录激活子(JAK/STAT)信号通路活化的抑制作用.方法 将RAW264.7细胞分为正常对照组、LPS(10 μg/mL LPS,浓度下同)组、LPS+无活性CORM-2组、LPS+小剂量CORM-2(50 μmol/LCORM-2)组、LPS+大剂量CORM-2(100μmol/L CORM-2)组,ELISA法检测细胞上清液中TNF-α的水平及蛋白质印迹法检测JAK1、JAK3分子磷酸化水平.另将35只雄性BALB/c小鼠按随机数字表法分为正常对照组、盲肠结扎和穿孔术(CLP)组、CLP+无活性CORM-2(8.0 mg/Kg)组和CLP+CORM-2(8.0 mg/kg)组.CLP+CORM-2组除伤后使用CORM-2外,其他处理同CLP组.于伤后24 h按上述方法检测小鼠血浆TNF-α、IL-1β的表达水平以及肝组织JAK1、JAK3分子磷酸化水平.对数据行t检验.结果 与正常对照组[(1.9±0.3)pg/mL]比较,LPS组细胞的TNF-α水平明显升高[(8.2±2.7)pg/mL,t=2.844,P<0.01],磷酸化JAK1、JAK3蛋白水平也升高;2种剂量LPS+CORM-2组细胞的TNF-α,水平分别为(5.7±1.4)、(3.2±0.9)pg/mL,较LPS组明显下降(t值分别为2.104、2.363,P值均小于0.05),JAK1、JAK3分子的磷酸化水平呈浓度依赖性下降.与正常对照组比较,CLP组血浆TNF-α、IL-1β水平明显升高(t值分别为2.916、2.796,P值均小于0.01),小鼠肝组织JAK1、JAK3分子的磷酸化水平亦明显升高.CLP+CORM-2组TNF-α、IL-1β血浆水平显著降低(t值分别为2.115、2.398,P值均小于0.05),肝组织JAK1、JAK3蛋白的磷酸化得到有效抑制.结论 CORM-2能明显抑制JAK分子磷酸化,继而抑制JAK/STAT信号通路的活化,减少下游相关细胞因子的表达,有效防止严重感染时炎症反应的级联反应.     

内毒素耐受对人正常前列腺上皮细胞分泌ＩＬ－６和ＩＬ－８的影响

目的 研究发现前列腺组织炎症在前列腺增生的发生与进展中有着重要作用。方法 内毒素耐受（endotoxin tolerance，ET）现象存在于人组织上皮细胞中如肠上皮细胞和人牙龈上皮细胞等，并可能影响组织的炎症和免疫反应。产生内毒素/脂多糖（Lipopolysaccharide，LPS）的G-菌如大肠埃希菌是影响前列腺炎的主要病原体。因此，本研究拟通过分析LPS反复刺激人正常前列腺上皮细胞RWPE-1中细胞炎性因子IL-6和IL-8表达，探讨是否内毒素耐受现象存在于人前列腺上皮细胞中。结果 采用1 μg/mL大肠杆菌（Escherichia coli）LPS刺激人正常前列腺上皮细胞RWPE-1 24 h，洗涤细胞后，给予1 μg/mL 浓度LPS再次刺激24 h，构建内毒素耐受模型。采用液相芯片技术检测细胞培养液中细胞因子IL-6和IL-8分泌水平的变化。结果 LPS刺激后6 h和24 h，IL-6和IL-8分泌水平均呈现上升趋势（P<0.05），较空白对照组有明显增高（P<0.05），LPS反复刺激后，诱导细胞耐受后，IL-6和IL-8分泌水平较第1次刺激后明显降低（P<0.05）。结论 内毒素耐受现象存在于RWPE-1中，能抑制RWPE-1细胞因子IL-6和IL-8的表达，进而可能影响前列腺组织的炎症和免疫反应。     

Interleukin 1 and its relationship to endotoxin tolerance.

Endotoxin (lipopolysaccharide [LPS])-induced cytokine release has been implicated in the pathogenesis of sepsis. Sublethal doses of LPS induce tolerance to a septic insult. This study evaluated pretreatment with interleukin 1 (IL-1) against an LPS challenge and examined its relationship to endotoxin tolerance. C3H/HeN mice (N = 100) were injected intraperitoneally with phosphate-buffered saline (control group), IL-1 (200 micrograms/kg), or LPS (1 mg/kg) for 3 days. On day 5, peritoneal macrophages were harvested and assayed for antimicrobial activity (superoxide anion production and Candida albicans phagocytosis). Serum cytokine levels and survival after an LPS challenge on day 5 were also assessed. Pretreatment with IL-1 or LPS significantly increased superoxide anion production, C albicans phagocytosis, and survival compared with pretreatment with phosphate-buffered solution. Interleukin 6 levels significantly decreased in the IL-1 and LPS groups. Peak levels of tumor necrosis factor significantly decreased only in the LPS group. Thus, pretreatment with IL-1 or low doses of LPS may exert protective effects by decreasing levels of interleukin 6 while increasing antimicrobial activity. Mice pretreated with IL-1 were protected from endotoxin despite elevated peak levels of tumor necrosis factor, suggesting a different mechanism for endotoxin tolerance than for tolerance to tumor necrosis factor.     

内毒素活化和耐受的巨噬细胞差异表达基因分析

目的　分析内毒素活化的和内毒素耐受的巨噬细胞差异表达基因 ,以探讨内毒素耐受的分子机制。方法　分离小鼠腹腔巨噬细胞 ,活化组直接以 1mg/L脂多糖处理 2h ,耐受组先以脂多糖预处理 2 0h ,再以脂多糖处理 2h。利用含 1176个基因的小鼠cDNA表达芯片进行基因表达谱分析。结果　活化组与耐受组间的 3倍差异表达基因为 3 1个 ,其中耐受组有 8个基因的表达水平明显高于活化组 ,包括细胞表面抗原FcgammaRIIb、间隙连接蛋白 43、凋亡相关蛋白NIP3、iN OS、骨髓间充质细胞抗原 (BST) 1以及激活素和卵泡抑素等 ,有 2 3个基因的表达水平明显低于活化组 ,包括转录因子EPAS1、EGR2、IRF1,细胞周期素依赖性蛋白激酶 p2 1和p5 7,骨桥蛋白 ,尿激酶型纤溶酶原激活物及其受体 ,以及多种生长因子受体和细胞因子。结论　这些差异表达基因多数未曾报道与内毒素耐受相关 ,可能在内毒素的发生中具有重要作用 ,并成为内毒素耐受的新的标志分子 ,对其进行干预有可能模拟内毒素耐受的保护效应。     

阿片受体与吗啡镇痛耐受

长期使用阿片类物质如吗啡的主要限制在于生理耐受性的发生.耐受使吗啡的镇痛效果明显减弱.现从阿片受体下调、失敏感、G-蛋白下游信号转导等方面,将阿片受体参与吗啡镇痛耐受机制的研究进展作一综述.     

Lipopolysaccharide suppresses albumin expression by activating NF-kappaB in rat hepatocytes

BACKGROUND: The severity of hypoalbuminemia has been shown to be related to morbidity and mortality in critical illness, illustrating the need for better understanding of the molecular mechanism of hypoalbuminemia. Lipopolysaccharide(LPS) is a key mediator which induces hypoalbuminemia in sepsis and septic shock. The present studies were performed to identify whether the reduction of albumin expression induced by LPS was mediated by activating nuclear factor kappa B(NF-kappaB) in cultured rat hepatocytes. MATERIALS AND METHODS: Primary rat hepatocytes were divided into five groups treated with normal saline or 1 ng/ml, 0.01 microg/ml, 0.1 microg/ml, or 1 microg/ml of LPS for 24 h. The albumin level in the supernatant and NF-kappaB activity in hepatocytes were measured. Hepatocytes were pretreated for 30 min with SN50 (a highly selected inhibitor of NF-kappaB) at different concentrations (10, 30, and 50 microg/ml). After 24 h of treatment with 1 microg/ml of LPS, the culture medium was measured for albumin level. Meanwhile, NF-kappaB activity in hepatocytes was assayed. RESULTS: LPS dramatically decreased albumin expression and enhanced NF-kappaB activity in rat hepatocytes, especially in the 1 microg/ml LPS group. This reduction in albumin expression induced by LPS can be completely inhibited by SN50 in different concentrations, and the maximal increase in albumin was observed at a SN50 dosage of 30 microg/ml. CONCLUSIONS: The results suggest that LPS inhibits albumin expression by activating NF-kappaB signaling. NF-kappaB is a critical signaling pathway in LPS-induced hypoalbuminemia which it is worthwhile to understand in studying the molecular mechanism of hypoalbuminemia in sepsis and septic shock.     

Induction of endotoxin tolerance inhibits alloimmune responses

It was recently reported that the induction of endotoxin tolerance (ET), which is defined as a reduced response to a lipopolysaccharide (LPS) challenge following the first LPS encounter, inhibits major histocompatibility complex (MHC)-restricted antigen presentation. This raises the question whether alloimmune responses can be inhibited by inducing ET in transplant donors. C57BL/6 mice were treated with a low dose of LPS prior to a challenge with a high dose of LPS to induce ET. Hearts from endotoxin-tolerized C57BL/6 mice were transplanted to BALB/c mice. The survival of the endotoxin-tolerized heart allografts was significantly prolonged. By using irradiated splenocytes from C57BL/6 mice and allogeneic splenocytes from BALB/c mice, a mixed lymphocyte reaction (MLR) assay was performed. The MLR assay used CFSE, and revealed that the splenocytes from the endotoxin-tolerized mice failed to induce the proliferation of allogeneic CD4(+) and CD8(+) T cells. Cytokine analyses of the supernatant of the MLR culture using endotoxin-tolerized stimulators revealed a distinct shift in the Th 1/Th 2 balance toward the Th 2-type response. The induction of ET increased the proportion of myeloid-related dendritic cells (DCs) expressing molecules necessary for antigen presentation, which favor the development of a Th 2 response; however, it reduced the proportion of lymphoid-related DCs expressing those molecules, which favor the development of the Th 1 response. Although the relevance of these findings with regard to the prolonged survival of the endotoxin-tolerized heart allografts remains to be elucidated, this is the first study to demonstrate that the induction of ET in donor animals inhibits alloimmune responses.     

Molecular mechanism of morphine tolerance and biological approaches to resolve tolerance

One of the major problems associated with the chronic use of morphine is tolerance. Repeated uses of morphine to relieve pain often cause patients to develop increasing resistance to the effects of the drugs, so that progressively higher doses are required to achieve the same analgesic effects. Acquired tolerance is thought to be different from dependence or addiction, but molecular mechanism underlying the development of tolerance is still unclear. Tolerance has been explained by desensitization of opioid receptor signaling and loss of functional receptors in the cell surface. The classical hypothesis was that phosphorylation and arrestin binding resulted in uncoupling of the receptor from G proteins, and reduced agonist efficacy. The receptor internalization would then result in fewer functional receptors at the cell surface. These events would cause so-called signaling desensitization. However, recent molecular biological studies have led researchers to revise the classical view of tolerance from observations that morphine does not always promote efficient receptor internalization. Among several key processes, the sequestration and subsequent internalization of the opioid receptor may play an important role for morphine tolerance. In fact, recent studies have suggested that receptor internalization can reduce tolerance. In addition, activation of the NMDA subtype of the glutamate receptor has been suggested as an anti-opioid system in the development of morphine tolerance. In this review, we focus on recent research progress on the morphine tolerance, and molecular biological and clinical approaches to resolve morphine tolerance.     

Induction of endotoxin tolerance inhibits alloimmune responses

It was recently reported that the induction of endotoxin tolerance (ET), which is defined as a reduced response to a lipopolysaccharide (LPS) challenge following the first LPS encounter, inhibits major histocompatibility complex (MHC)-restricted antigen presentation. This raises the question whether alloimmune responses can be inhibited by inducing ET in transplant donors. C57BL/6 mice were treated with a low dose of LPS prior to a challenge with a high dose of LPS to induce ET. Hearts from endotoxin-tolerized C57BL/6 mice were transplanted to BALB/c mice. The survival of the endotoxin-tolerized heart allografts was significantly prolonged. By using irradiated splenocytes from C57BL/6 mice and allogeneic splenocytes from BALB/c mice, a mixed lymphocyte reaction (MLR) assay was performed. The MLR assay used CFSE, and revealed that the splenocytes from the endotoxin-tolerized mice failed to induce the proliferation of allogeneic CD4⁺ and CD8⁺ T cells. Cytokine analyses of the supernatant of the MLR culture using endotoxin-tolerized stimulators revealed a distinct shift in the Th 1/Th 2 balance toward the Th 2-type response. The induction of ET increased the proportion of myeloid-related dendritic cells (DCs) expressing molecules necessary for antigen presentation, which favor the development of a Th 2 response; however, it reduced the proportion of lymphoid-related DCs expressing those molecules, which favor the development of the Th 1 response. Although the relevance of these findings with regard to the prolonged survival of the endotoxin-tolerized heart allografts remains to be elucidated, this is the first study to demonstrate that the induction of ET in donor animals inhibits alloimmune responses.     

Surgical stress reduces mortality from endotoxin shock

BACKGROUND AND AIM: Surgical stress has been considered a preliminary to multiple organ failure through what has been termed a "two-hit" mechanism. Recent evidence, however, suggests that such stress has a beneficial influence in reducing endotoxin [lipopolysaccharide (LPS)]-mediated lethality. This study has been an effort to clarify whether and how LPS-mediated septic shock is prevented by a previous insult with mild (laparotomy) or severe (hepatectomy) surgical stress. METHODS: LPS was injected intraperitoneally into mice after two-thirds hepatectomy or laparotomy only. Survival rates, and protein and messenger RNA (mRNA) levels for tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) were measured. RESULTS: Most of the unoperated control mice died within 3 days after the LPS challenge. Mortality following LPS injection was reduced after laparotomy only or hepatectomy (P<0.05). A significant reduction in the mortality was observed from 2 days to 7 days after laparotomy only, and from 2 days to 4 weeks after hepatectomy. Correspondingly, the increase in the serum levels of TNF-alpha and IL-6 induced by the LPS injection was partially impaired by either laparotomy only or hepatectomy at an early (2 days) postoperative stage (P<0.05). At a later (7 days) stage, however, the serum level of IL-6 and its mRNA level in the spleen were elevated after the LPS challenge more quickly in the hepatectomy group than in the unoperated control group ( P<0.05). CONCLUSION: Surgical stress reduces LPS-induced lethality through biphasically regulating the levels of TNF-alpha and IL-6 production.     

Glycogen synthase kinase 3 inhibitor attenuates endotoxin-induced liver injury

Background/Aims

Endotoxin (lipopolysaccharide, LPS)-induced acute liver injury was attenuated by endotoxin tolerance (ET), which is characterized by phosphatidylinositol 3-kinase pathway/Akt signaling. Glycogen synthase kinase 3 (GSK-3) acts downstream of phosphatidylinositol 3-kinase pathway/Akt and GSK-3 inhibitor protects against organic injury. This study evaluates the hypothesis that ET attenuated LPS-induced liver injury through inhibiting GSK-3 functional activity and downstream signaling.

Methods

Sprague-Dawley rats with or without low-dose LPS pretreatment were challenged with or without large dose of LPS and subsequently received studies. Serum tumor necrosis factor-alpha, interleukin-10, alanine aminotransferase, lactate dehydrogenase, and total bilirubin levels were analyzed, morphology of liver tissue was performed, glycogen content, myeloperoxidase content, phagocytosis activity of Kupffer cells, and the expression and inhibitory phosphorylation as well as kinase activity of GSK-3 were examined. Survival after LPS administration was also determined.

Results

LPS induced significant increases of serum TNF-α, alanine aminotransferase, lactate dehydrogenase, and total bilirubin (P < 0.05), which were companied by obvious alterations in liver: the injury of liver tissue, the decrease of glycogen, the infiltration of neutrophils, and the enhancement of phagocytosis of Kupffer cells (P < 0.05). LPS pretreatment significantly attenuated these alterations, promoted the inhibitory phosphorylation of GSK-3 and inhibited its kinase activity, and improved the survival rate (P < 0.05).

Conclusions

ET attenuated LPS-induced acute liver injury through inhibiting GSK-3 functional activity and its downstream signaling.