和厚朴酚抑制线粒体可溶蛋白诱导小胶质细胞活化的体外实验研究

目的:探讨线粒体可溶蛋白诱导小胶质细胞活化作用及和厚朴酚对小胶质细胞活化的影响。方法:培养BV2小胶质细胞,分空白对照组(control)、线粒体可溶蛋白组(MDP)、和厚朴酚干预组(HNK)。ELISA检测不同浓度线粒体可溶蛋白(MSP)刺激不同时间的细胞上清液中IL-6和TNF-α含量;RT-PCR半定量法测定各组转录因子Klf4的表达情况;倒置相差显微镜观察各组细胞形态变化。结果:1.ELISA:MSP(10μg/ml,100μg/ml)处理7h时,IL-6和TNF-α含量与control组比较显著升高(P0.05);100μg/ml MSP处理1、3、5、7h时,IL-6和TNF-α表达与control组比较明显升高(P0.05),且7h时HNK组含量明显低于MDP组(P0.05)。2.RT-PCR结果显示MDP组KLP4的表达显著高于空白对照组和HNK组(P0.05)。3.倒置相差显微镜观察示空白组胶质细胞形态呈静息状态;MDP组小胶质细胞的胞体变圆或者椭圆,突起消失,呈"阿米巴"状;HNK组活化状态的小胶质细胞明显减少。结论:线粒体可溶蛋白可以激活小胶质细胞,促进白细胞介素IL-6和TNF-α的释放,和厚朴酚能够有效地抑制线粒体可溶蛋白诱导的小胶质细胞活化,其机制可能是通过下调Klf4的表达发挥作用。     

黄连素通过SOCS1减轻Aβ淀粉样蛋白诱导的小胶质细胞激活

目的:观察黄连素(Berberine,BBR)对暴露于Aβ淀粉样蛋白(βAmyloid,Aβ)中的小胶质细胞激活的影响,并明确细胞因子沉默蛋白1(Silencing of Cytokine Signaling Factor 1, SOCS1)是否参与了BBR对小胶质细胞激活的影响。方法:将N9小胶质细胞暴露于含5μM Aβ的培养基中模拟阿尔兹海默症(Alzheimer's,AD)中的小胶质细胞激活。随后,将细胞分为5组,分别为Control组、5μM的Aβ损伤组(Aβ)、BBR+Aβ组、SOCS1-siRNA干扰组(SOCS1-siRNA+BBR+Aβ)和乱序si RNA处理组(SC-si RNA+BBR+Aβ),细胞处理24 h后,采用Western blot检测细胞诱导型一氧化氮合酶(Inducible Nitric Oxide Synthase,i NOS)、SOCS1蛋白的表达,酶联免疫吸附法(Enzyme Linked Immunosorbent Assay,ELISA)检测细胞培养基内炎症因子的水平。结果:与正常培养的Control组相比,5μM的Aβ暴露24 h可显著增加细胞i NOS蛋白表达水平和肿瘤坏死因子α(Tumor Necrosis Factorα,TNF-α)、白细胞介素1β(Interleukin 1β,IL-1β)和IL-6的释放(P0.05),但并未对SOCS1蛋白表达产生显著影响(P0.05),5μM的BBR可显著降低i NOS表达和上述3种促炎症因子的释放(P0.05),并上调SOCS1蛋白表达,而SOCS1-siRNA可显著逆转BBR对i NOS和SOCS1蛋白表达及3种炎症因子释放的影响(P0.05)。结论:BBR可能通过SOCS1减轻Aβ淀粉样蛋白对小胶质细胞的激活。     

神经肽CRH对原代大鼠皮层小胶质细胞NO、TNF-α和IL-6释放的影响

目的:探讨神经肽促肾上腺皮质激素释放激素(CRH)参与调节原代大鼠皮层小胶质细胞的激活。方法:取原代大鼠皮层细胞,体外培养10 d,纯化24 h后得小胶质细胞,采用ELISA和NO测试盒检测小胶质细胞激活后促炎症介质一氧化氮(NO)、肿瘤坏死因子α(TNF-α)和白介素6(IL-6)的释放。结果:10-15mol/L CRH明显促进原代大鼠小胶质细胞的促炎症介质NO,TNF-α和IL-6的释放。CRHR1特异性拮抗剂CP154,526可以阻断CRH诱导的小胶质细胞促炎症反应。结论:神经肽CRH通过CRHR1调节原代大鼠小胶质细胞的促炎症反应,CRH联合细菌脂多糖(Lipopolysaccharides,LPS)可以增强LPS诱导的小胶质细胞NO,TNF-α和IL-6的释放。     

α7nAChR调控STAT3磷酸化在星形胶质细胞机械性损伤后炎症反应中的作用

目的:通过建立星形胶质细胞机械性损伤模型,研究烟碱型乙酰胆碱受体α7亚单位(α7nAChR)在创伤性脑损伤后星形胶质细胞炎症反应中的作用及调控机制。方法:建立星形胶质细胞机械性损伤模型,通过ELISA检测炎症因子IL-1β、TNF-α、IL-10和TGF-β的表达;利用α7n ACh R抑制剂α-BGT和激动剂PHA-543613处理星形胶质细胞,检测相关炎症因子表达,并通过Western blot检测信号传导及转录活化因子3(STAT3)和磷酸化STAT3(p-STAT3)的表达;利用α-BGT和STAT3抑制剂Stattic处理星形胶质细胞,检测相关炎症因子表达。结果:①星形胶质细胞机械性损伤后,促炎因子IL-1β、TNF-α表达增加,抗炎因子IL-10、TGF-β表达降低(P0.05)。②利用α-BGT抑制α7nAChR可增加损伤后IL-1β、TNF-α的表达,减少IL-10、TGF-β的表达(P0.05);而利用PHA-543613激活α7nAChR功能,则发挥相反作用(P0.05)。③α-BGT可促进STAT3磷酸化,而PHA-543613抑制STAT3磷酸化(P0.05)。④STAT3抑制剂Stattic可减少IL-1β和TNF-α的表达,增加IL-10和TGF-β的表达,并部分阻断α-BGT对IL-1β、TNF-α、IL-10及TGF-β表达的影响(P0.05)。结论:机械性损伤后,激活α7nAChR可减轻星形胶质细胞炎症反应,而抑制STAT3磷酸化是其重要的下游机制。     

创伤性脑损伤后IL-1?茁在神经胶质细胞中经时定位表达的研究*

目的:探讨创伤性脑损伤(TBI)后白细胞介素-1β(IL-1β)在神经胶质细胞中的经时定位表达情况。方法:选择72只SPF级雄性小鼠分为假手术组(sham组)、TBI 6h组、TBI 12h组、TBI 1d组、TBI 4d组与TBI 7d组,每组12只,分别在脑损伤后6h、12h、1d、4d、7d时获取血清和脑组织并且制作切片。ELISA检测损伤后炎症因子IL-1β、白细胞介素-6 (IL-6)和肿瘤坏死因子-α(TNF-α)的表达。Western blot检测钙离子结合蛋白-1(IBA-1)和胶质纤维酸性蛋白(GFAP)的表达。应用免疫荧光双重染色技术观察炎症因子IL-1β在小胶质细胞和星形胶质细胞中的定位表达情况。结果:TBI后6h-7d时炎症因子IL-1β、IL-6和TNF-α的表达量均高于sham组(P0.05)。Western blot结果显示,IBA-1的表达在损伤后6h-7d时高于sham组,GFAP的表达在损伤后1d-7d时高于sham组(P0.05)。免疫荧光双重染色技术显示,6h、12h时IL-1β主要表达在小胶质细胞中,IL-1β和IBA-1共表达细胞数量多于sham组(P0.05);1d、4d、7d时IL-1β主要表达在星形胶质细胞中,IL-1β和GFAP共表达细胞数量多于sham组(P0.05)。结论:TBI诱导了胶质细胞和炎症因子的表达,其表达随脑损伤的时间而变化,IL-1β早期定位表达于小胶质细胞,后期定位表达于星形胶质细胞中。     

SOCS1在氯胺酮减轻小胶质细胞活化中的机制研究

目的:探讨麻醉药氯胺酮(Ketamine, KET)对暴露于脂多糖(Lipopolysaccharide, LPS)中的小胶质细胞活化水平的影响,并观察细胞因子信号转导抑制因子1(Suppressor of Cytokine Signaling 1, SOCS1)在其中的作用。方法:本研究选用N9小胶质细胞系,将其暴露于浓度为10 ng/mL的LPS中,模拟炎症反应,同时给与浓度为1 m M的KET,采用Western blot、酶联免疫吸附检测(Enzyme-Linked Immunosorbent Assay, ELISA)小RNA干扰和免疫细胞染色等方法,观察KET对暴露于LPS中的小胶质细胞活化水平的影响,及SOCS1分子在其中的作用。结果:将细胞分为3组,分别为正常培养的Control组、LPS组和KET+LPS组,研究发现,将N9小胶质细胞暴露于含10 ng/mL的细胞培养基中24 h后,细胞诱导型一氧化氮合酶(Inducible Nitric Oxide Synthase, i NOS)表达和培养基肿瘤坏死因子α(Tumor Necrosis Factorα, TNF-α)含量显著增加(P0.05),而KET可显著降i NOS蛋白表达和培养基TNF-α含量(P0.05)。随后,将细胞分为5组,分别为Control组、LPS组、KET+LPS组、SOCS1-siRNA+KET+LPS组和乱序siRNA(SC-siRNA)+KET+LPS组,我们发现,LPS可显著增加小胶质细胞TNF-α和白细胞介素1β(Interleukin-1β, IL-1β)的释放、增加SOCS1和核因子κB(Neuclear FactorκB, NF-κB)表达(P0.05),而KET可显著逆转LPS对炎症因子释放和NF-κB表达的影响,并进一步增加SOCS1表达(P0.05),而SOCS1-siRNA显著逆转了KET的上述作用(P0.05),SC-siRNA未对KET产生的上述作用造成显著影响(P0.05)。结论:KET可降低LPS对小胶质细胞的活化作用,上述作用可能通过SOCS1分子介导。     

七氟烷对培养的小鼠小胶质细胞炎症因子表达的影响（英文）

目的:探讨七氟烷对培养的小鼠小胶质细胞中炎症因子表达的影响。方法:取新生(2~3天)C57BL/6小鼠,分离小胶质细胞,将其随机分为4组(n=10):对照组(Control);七氟烷组(Sevoflurane);NF-κB抑制剂组(PDTC);NF-κB抑制剂+七氟烷组(PDTC+Sevoflurane)。用Drager麻醉机向Sevoflurane组PDTC+Sevoflurane组培养的小胶质细胞盒内释放21%O2,5%CO2,4.1%七氟烷的气体,用气体分析仪持续监测各组的浓度。应用Iba-1的免疫荧光染色法对小鼠小胶质细胞进行纯度鉴定。分别在于给七氟烷后2 h、4 h和6 h时采用免疫印迹分析技术检测两组小胶质细胞IL-6和TNF-α的表达水平和NF-κB的活性。PDTC+Sevoflurane组在给七氟烷前一小时给予PDTC,采用ELISA技术和免疫印迹分析技术检测各组小胶质细胞IL-6和TNF-α的浓度和NF-κB的表达。结果:免疫印迹显示七氟烷组细胞中IL-6、TNF-α水平和NF-κB的激活水平升高;PDTC降低了七氟烷作用后核内NF-κB的表达,减弱了IL-6和TNF-α水平的升高作用。结论:七氟烷可通过激活NF-κB信号通路,进一步激活培养的小鼠小胶质细胞中炎症因子的表达。     

高迁移率族蛋白1拮抗剂BoxA对血管性痴呆大鼠急性期海马区域神经炎症的抑制作用

目的:探究高迁移率族蛋白1(HMGB1)拮抗剂BoxA脑室立体定向注射对双侧颈总动脉闭塞(2VO)后大鼠海马区域神经炎症(血脑屏障通透性、小胶质细胞的激活以及炎症因子水平等)的抑制作用。方法:60只雄性Sprague-Dawley(SD)大鼠分为假手术组(即Sham组)、PBS组以及BoxA组(各组n=20),分别在行2VO(n=40,正常手术)或假手术(n=20,仅暴露不结扎)后,立即用BoxA(10μg在10uL PBS溶液中,n=20)或者等体积PBS(n=20)立体定向注射到左侧侧脑室中。造模3 d后,用HMGB1和NeuN免疫荧光双染,western blot观察HMGB1出核现象,伊文思蓝(EB)染色和脑水含量测量评价血脑屏障(BBB)通透性,Iba1免疫荧光染色观察小胶质细胞活化,定量逆转录聚合酶链反应(RT-PCR)检测炎症细胞因子(白介素1β(Interleukin-1β, IL-1β)和白介素6(In-terleukin-6, IL-6)和肿瘤坏死因子α(Tumor necrosis factor-α, TNF-α))的基因表达水平。结果:相比Sham组,PBS组海马CA1亚区HMGB1阳性细胞核(%)以及HMGB1NeuN阳性细胞/HMGB1阳性细胞(%)显著下降(P0.01),而BoxA组以上改变较PBS组部分减少(P0.05)。PBS组EB渗漏、脑含水量均较Sham组显著增加(P0.001),而BoxA组以上指标均较PBS组明显减轻(P0.05)。PBS组Iba1阳性细胞相比Sham组明显增多(P0.01),且炎症因子(IL-1β、IL-6和TNF-α)表达显著增高(P0.05);而相比PBS组,BoxA组Iba1阳性细胞表达减少((P0.05),且炎症因子(IL-1β、IL-6 and TNF-α表达明显减少(P0.05)。结论:HMGB1抑制剂BoxA立体定向注射能够有效缓解急性期血管性痴呆大鼠海马区域的神经炎症反应。     

齐墩果酸抑制肿瘤坏死因子-α诱导的成纤维细胞样滑膜细胞炎症因子表达及其机制研究

探讨齐墩果酸(Oleanolic acid,OA)对肿瘤坏死因子-α(TNF-α)诱导成纤维细胞样滑膜细胞的炎症因子表达的影响及其机制。首先复苏培养人成纤维细胞样滑膜细胞(FLS),通过RT-PCR检测细胞IL-6及IL-1βmRNA表达,采用Western blot方法检测p38MAPK及NF-κB蛋白表达变化,通过ELISA法检测细胞上清液中IL-6及IL-1β浓度。与对照组比较,TNF-α明显诱导FLS细胞IL-6及IL-1βmRNA的表达及上清液中IL-6及IL-1β的分泌(P0.05),同时磷酸化p38蛋白和核NF-κB明显增加(P0.05),且p38MAPK阻断剂SB203580能抑制TNF-α诱导的核NF-κB增加。OA呈浓度依赖性抑制TNF-α诱导的FLS细胞p38蛋白磷酸化和核NF-κB增加(P0.05)。且OA、p38MAPK通路抑制剂SB203580或NF-κB阻断剂BAY 11-7082均能抑制TNF-α诱导的IL-6及IL-1β分泌增加(P0.05)。综上所述,OA能抑制TNF-α诱导的FLS细胞炎症因子IL-6及IL-1β的产生,其机制可能与抑制p38MAPK/NF-κB信号通路有关。     

乙酰胆碱通过作用于α7烟碱型乙酰胆碱受体抑制大鼠小胶质细胞炎性反应

小胶质细胞是中枢神经系统中主要的免疫细胞。本研究旨在探讨乙酰胆碱(acetylcholine,ACh)抑制小胶质细胞炎症反应的具体机制。原代培养Sprague-Dawley(SD)大鼠小胶质细胞,脂多糖(lipopolysaccharide,LPS)诱导建立炎症反应模型,ACh处理24 h后,用Western blot检测多种炎性因子、胰岛素样生长因子1(insulin-like growth factor 1,IGF-1)和α7烟碱型乙酰胆碱受体(α7 nicotinic acetylcholine receptor,α7nAChR)的蛋白表达,用ELISA检测多种炎性因子和IGF-1的释放情况,用慢病毒转染沉默α7nAChR后观察ACh作用的变化。结果显示,LPS可促进小胶质细胞的激活,上调诱生型一氧化氮合酶(inducible nitric oxide synthase,iNOS)蛋白表达,增加白介素1β(interleukin-1β,IL-1β)和肿瘤坏死因子α(tumor necrosis factorα,TNF-α)的表达和释放,减少神经营养因子IGF-1的表达和释放,ACh能逆转LPS的这些作用;LPS可下调小胶质细胞的α7nAChR蛋白表达,ACh逆转该作用;α7n AChR-shRNA慢病毒转染小胶质细胞后,ACh对抗LPS的作用消失。以上结果提示,ACh对抗LPS诱导的小胶质细胞炎症反应的保护作用是通过α7nAChR实现的,这为今后神经炎症疾病的治疗提供了新的治疗靶点。     

EGb761对LPS诱导THP-1细胞释放HMGB1蛋白表达的调节

目的:探讨EGb761对LPS诱导THP-1细胞释放HMGB1蛋白表达的调节,为EGb761的临床运用提供可行的依据。方法:LPS(1μg/m L)诱导不同时间后,western blotting检测THP-1细胞上清液中HMGB1蛋白含量变化及不同浓度EGb761对LPS诱导THP-1细胞释放HMGB1蛋白的表达和NF-κB的活性;酶联免疫吸附法(ELISA)检测细胞中IL-1β、IL-6、TNF-α的含量。共聚焦显微镜观察EGb761对LPS诱导THP-1细胞释放HMGB1蛋白核转位变化。结果:(1)LPS组IL-1β、IL-6、TNF-α的含量在刺激6-12 h后明显高于空白对照组,而EGb761+LPS组IL-1β、IL-6、TNF-α的含量均显著低于LPS组(P0.05)。(2)EGb761处理LPS诱导THP-1细胞6 h后细胞上清液NF-κB活性表达量较空白对照组低,随着处理时间延长至12 h,NF-κB的活性表达量呈明显下降趋势(P0.05)。(3)LPS诱导THP-1细胞18 h后,细胞上清液中HMGB1蛋白含量呈明显升高趋势(P0.05)。(4)不同浓度EGb761对LPS诱导THP-1细胞18 h后,HMGB1蛋白含量较空白对照组有下降趋势,HMGB1蛋白含量随着EGB761浓度增加至100μg/m L呈下降趋势并呈浓度依赖效应(P0.05)。(5)LPS诱导THP-1细胞后,在共聚焦显微镜下可见胞浆中大量HMGB1蛋白标记分布,而EGb761+LPS共同诱导THP-1细胞后胞浆中可见少量HMGB1蛋白分布。结论:LPS可诱导THP-1细胞IL-1β、IL-6、TNF-α表达增多及NF-κB活化,导致HMGB1蛋白表达增多及核转位,而EGB761能抑制THP-1细胞IL-1β、IL-6、TNF-α表达及NF-κB活化,调节HMGB1蛋白的表达及核转位。     

Curcumin protects against acute liver damage in the rat by inhibiting NF-kappaB, proinflammatory cytokines production and oxidative stress

Curcumin, an anti-inflammatory and antioxidant compound, was evaluated for its ability to suppress acute carbon tetrachloride-induced liver damage. Acute hepatotoxicity was induced by oral administration of CCl4 (4 g/kg, p.o.). Curcumin treatment (200 mg/kg, p.o.) was given before and 2 h after CCl4 administration. Indicators of necrosis (alanine aminotransferase) and cholestasis (gamma-glutamyl transpeptidase and bilirubins) resulted in significant increases after CCl4 intoxication, but these effects were prevented by curcumin treatment. As an indicator of oxidative stress, GSH was oxidized and the GSH/GSSG ratio decreased significantly by CCl4, but was preserved within normal values by curcumin. In addition to its antioxidants properties, curcumin is capable of preventing NF-kappaB activation and therefore to prevent the secretion of proinflammatory cytokines. Therefore, in this study we determined the concentrations of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and interleukin-6 (IL-6) mRNA, and NF-kappaB activation. CCl4-administered rats depicted significant increases in TNF-alpha, IL-1beta, and IL-6 production, while curcumin remarkably suppressed these mediators of inflammation in liver damage. These results were confirmed by measuring TNF-alpha, and IL-1beta protein production using Western Blot analysis. Accordingly, these proteins were increased by CCl4 and this effect was abolished by curcumin. Administration of CCl4 induced the translocation of NF-kappaB to the nucleus; CCl4 induced NF-kappaB DNA binding activity was blocked by curcumin treatment. These findings suggest that curcumin prevents acute liver damage by at least two mechanisms: acting as an antioxidant and by inhibiting NF-kappaB activation and thus production of proinflammatory cytokines.     

Modulation of NO and cytokines in microglial cells by Cu/Zn-superoxide dismutase.

The activation of microglial cells in response to neuropathological stimuli is one of the prominent features of human neurodegenerative diseases. Cytokines such as IL-1 beta and TNF-alpha and inflammation-related enzymes such as inducible nitric oxide synthase are usually induced during the activation of microglial cells. We investigated the modulation of the activation of microglial cell by transfecting a Cu/Zn-SOD cDNA into BV-2 cells. Parental and transfected BV-2 cells were then subjected to LPS stimulation. The results showed that in Cu/Zn-SOD-transfected BV-2 cells, the expression and activity of Cu/Zn-SOD increased. On the other hand, upon activation by LPS, these cells produced less NO, IL-1 beta, and TNF-alpha than the parental microglial cells. This finding suggests that superoxide may be an early signal triggering the induction of cytokines and that the transfected Cu/Zn-SOD may provide a neuroprotective function via suppression of microglial activation. In addition, this approach may provide a rationale for the development of treatments for neurodegenerative diseases.     

Differential regulation of cytokine release and leukocyte migration by lipopolysaccharide-stimulated primary human lung alveolar type II epithelial cells and macrophages

Bacterial colonization is a secondary feature of many lung disorders associated with elevated cytokine levels and increased leukocyte recruitment. We hypothesized that, alongside macrophages, the epithelium would be an important source of these mediators. We investigated the effect of LPS (0, 10, 100, and 1000 ng/ml LPS, up to 24 h) on primary human lung macrophages and alveolar type II epithelial cells (ATII; isolated from resected lung tissue). Although macrophages produced higher levels of the cytokines TNF-alpha and IL-1beta (p < 0.0001), ATII cells produced higher levels of chemokines MCP-1, IL-8, and growth-related oncogene alpha (p < 0.001), in a time- and concentration-dependent manner. Macrophage (but not ATII cell) responses to LPS required activation of ERK1/2 and p38 MAPK signaling cascades; phosphorylated ERK1/2 was constitutively up-regulated in ATII cells. Blocking Abs to TNF-alpha and IL-1beta during LPS exposure showed that ATII cell (not macrophage) MCP-1 release depended on the autocrine effects of IL-1beta and TNF-alpha (p < 0.003, 24 h). ATII cell release of IL-6 depended on autocrine effects of TNF-alpha (p < 0.006, 24 h). Macrophage IL-6 release was most effectively inhibited when both TNF-alpha and IL-1beta were blocked (p < 0.03, 24 h). Conditioned media from ATII cells stimulated more leukocyte migration in vitro than conditioned media from macrophages (p < 0.0002). These results show differential activation of cytokine and chemokine release by ATII cells and macrophages following LPS exposure. Activated alveolar epithelium is an important source of chemokines that orchestrate leukocyte migration to the peripheral lung; early release of TNF-alpha and IL-1beta by stimulated macrophages may contribute to alveolar epithelial cell activation and chemokine production.     

Lactate induces tumour necrosis factor-alpha, interleukin-6 and interleukin-1beta release in microglial- and astroglial-enriched primary cultures

Hyperammonaemia has deleterious effects on the CNS in patients with liver dysfunction. Cellular mechanisms underlying the effects of hyperammonaemia are largely unknown, although astrocytes have been the main target of interest. This study investigated how treatment with NH4Cl and lactate, which increase in the brain as a consequence of hyperammonaemia, affects cells in primary rat cultures enriched in either astrocytes or microglia. Morphological changes were studied over time using light microscopy. Release of the proinflammatory cytokines tumour necrosis factor-alpha (TNF-alpha), interleukin (IL)-6 and IL-1beta was measured using ELISA. NH4Cl was found to induce vacuole formation in both culture systems. Lactate treatment altered astrocytic appearance, resulting in increased space between individual cells. Microglia adopted a round morphology with either NH4Cl or lactate treatment. Lactate, but not NH4Cl, induced release of TNF-alpha and IL-6 in both astroglial- and microglial-enriched cultures, while IL-1beta was released only in microglial cultures. Cytokine release was higher in the microglial- than in the astroglial-enriched cultures. Additionally, the astroglial-enriched cultures containing approximately 10% microglial cells released more cytokines than cultures containing about 5% microglial cells. Taken together, our data suggest that most TNF-alpha, IL-6 and IL-1beta release comes from microglia. Thus, microglia could play an important role in the pathological process of hyperammonaemia.     

Neisseria meningitidis can induce pro-inflammatory cytokine production via pathways independent from CD14 and toll-like receptor 4

Fulminant meningococcal sepsis (FMS) is considered the prototypical Gram-negative sepsis. Lipopolysaccharide (LPS) is thought to be the main toxic element that induces pro-inflammatory cytokine production after interaction with CD14 and toll-like receptor 4 (TLR4). However, there is increasing evidence that LPS is not the sole toxic element of meningococci. The aim of the present study was to determine the role of CD14 and TLR4 in pro-inflammatory cytokine induction by meningococci. To this end, cytokine induction by isolated meningoccal LPS, wild-type N. meningitidis H44/76 (LPS+-meningococci) matched for concentrations of LPS and LPS-deficient N. meningitidis H44/76lpxA (LPS - -meningococci) was studied in human PBMCs and murine peritoneal macrophages (PMs). Pre-incubation of PBMCs with WT14, a monoclonal antibody against CD14, abolished TNF-alpha and IL-1beta induction by E. coli LPS, while cytokine induction by meningococcal LPS was only partially inhibited. When LPS+- and LPS - -meningococci at higher concentrations were used as stimuli, anti-CD14 had a minimal effect. In C3H/HeJ murine PMs, devoid of a functional TLR4, minimal IL-1alpha, IL-6 and TNF-alpha production was seen after stimulation with 10 ng/mL E. coli or meningococcal LPS. However, at higher concentrations (1000 ng LPS/mL) the production of TNF-alpha, but not IL-1alpha or IL-6, occurred also independently of TLR4. The expression of a functional TLR4 in murine PMs had no effect on the cytokine induction by LPS+- or LPS - -meningococci. It is concluded that pro-inflammatory cytokine induction by N. meningitidis can occur independently of CD14 and TLR4.     

Cytokine patterns during dengue shock syndrome

OBJECTIVE: To investigate the patterns of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), IL-6, interferon-gamma (IFN-gamma) and interleukin-1 receptor antagonist (IL-1Ra) during the course of dengue shock syndrome. DESIGN: Prospective clinical study. SETTING: Pediatric Intensive Care Unit, Dr. Kariadi Hospital, the university hospital of Diponegoro University, Semarang, Indonesia. PATIENTS: Fifty children with dengue shock syndrome. MEASUREMENTS: The plasma concentration and the ex vivo production, with and without lipopolysaccharide (LPS), of TNF-alpha, IL-1beta and IL-1Ra were measured in duplicate by nonequilibrium radioimmunoassay (RIA); IFN-gamma and IL-6 were measured by ELISA. RESULTS: During the acute phase, the plasma concentrations and the ex vivo production without LPS of IL-1Ra were considerably elevated and returned to normal on recovery. However, the ex vivo LPS-stimulated production of the proinflammatory cytokines TNF-alpha and IL-1beta were considerably depressed. Also, these concentrations returned towards normal on recovery. In non-survivors, the plasma concentrations of IL-6 and IL-1Ra were significantly higher than in survivors (p = 0.00001 and p = 0.0005, respectively). In addition, the ex vivo production of IL-1Ra in non-survivors was significantly higher than in survivors, both without LPS stimulation (p = 0.0008) and with LPS (p < 0.004). IL-1Ra was significantly associated with mortality (p = 0.007). CONCLUSION: Since IL-1Ra was significantly associated with mortality, this measurement may be used as an index of disease severity in dengue shock syndrome.     

Dynamics of cytokine production in human peripheral blood mononuclear cells stimulated by LPS or infected by Borrelia

To specify the role of individual cytokines in the immune response to pyrogens, isolated and cultivated human peripheral blood mononuclear cells (PBMC) were used for the experiments. Different pyrogens (lipopolysaccharide from Escherichia coli - LPS and live Borrelia afzelii) were applied and the time course of changes in concentrations of different cytokines in the medium was followed using the ELISA method. It was found that nonstimulated human PBMC proliferate under in vitro conditions and produce IL-6, TNF-alpha, IL-10 and finally also IL-1beta. Productions of IL-12 and INF-gamma are not changed. Proliferation of PBMC is potentiated after incubation with LPS or live Borrelia. PBMC stimulated by LPS increase the net production (stimulated minus unstimulated) of IL-1beta and TNF-alpha significantly, while production of IL-6 was smaller. A delayed increase in the production of IL-10 was also observed. Productions of IL-12 and INF-gamma were not influenced. In contrast to LPS, stimulation of PBMC with live Borrelia, increases also the production of IL-12 and IFN-gamma, besides IL-1beta, TNF-alpha, IL-6 and IL-10. Productions of IL-1beta, IL-6 and TNFalpha increased immediately after incubation with both LPS and Borrelia, while productions of IL-12 and INF-gamma begin to increase 8 hours and production of IL-10 12 hours after stimulation. Data indicate that stimulation with different pyrogens may activate the cells of the immune cascade in a different way. Stimulation of BPMC by LPS seems to activate the initial steps of the immune response (macrophages and granulocytes) only, while infection with live Borrelia also stimulates the later phase of the immune response, probably due to effect of initially produced cytokines.     

Methylenedioxymethamphetamine (MDMA; Ecstasy) suppresses IL-1beta and TNF-alpha secretion following an in vivo lipopolysaccharide challenge

In this study we examined the effects of methylenedioxymethamphetamine (MDMA) administration on responsiveness to an in vivo immune challenge with lipopolysaccharide (LPS; 100 microg/kg; i.p.). LPS produced an increase in circulating IL-1beta and TNF-alpha in control animals. MDMA (20 mg/kg; i.p.) significantly impaired LPS-induced IL-1beta and TNF-alpha secretion. The suppressive effect of MDMA on IL-1beta secretion was transient and returned to control levels within 3 hours of administration. In contrast, the MDMA-induced suppression of TNF-alpha secretion was evident for up to 12 hours following administration. In a second study we examined the effect of co-administration of MDMA (5, 10 and 20 mg/kg; i.p.) on LPS-induced IL-1beta and TNF-alpha secretion, and demonstrated that all three doses potently suppressed LPS-induced TNF-alpha secretion, but only MDMA 10 and 20 mg/kg suppressed LPS-induced IL-1beta secretion. In addition, serum MDMA concentrations displayed a dose-dependent increase, with the concentrations achieved following administration of 5 and 10 mg/kg being in the range reported in human MDMA abusers. In order to examine the possibility that the suppressive effect of MDMA on IL-1beta and TNF-alpha could be due to a direct effect of the drug on immune cells, the effect of in vitro exposure to MDMA on IL-1beta and TNF-alpha production in LPS-stimulated diluted whole blood was evaluated. However IL-1beta or TNF-alpha production were not altered by in vitro exposure to MDMA. In conclusion, these data demonstrate that acute MDMA administration impairs IL-1beta and TNF-alpha secretion following an in vivo LPS challenge, and that TNF-alpha is more sensitive to the suppressive effects of MDMA than is IL-1beta. However the suppressive effect of MDMA on IL-1beta and TNF-alpha could not be attributed to a direct effect on immune cells. The relevance of these findings to MDMA-induced immunomodulation is discussed.