LPS致敏巨噬细胞产生及其信号机制

目的探讨LPS诱导的巨噬细胞(Mφ)致敏及其信号机制.方法巨噬细胞样细胞株RAW 264.7以10μg/L LPS预处理1 h后洗去,再以1 mg/LPMA、1μmmol/LfMLP、100μg/L LPS、1 g/LZyms和15mg/L MDP攻击1h,检测上清中超氧阴离子(O-2)的产生,并用荧光显微成像系统检测细胞内游离钙离子浓度([Ca2+]i),探讨[Ca2+]i与LPS致敏Mφ产生O-2的关系.结果LPS预处理后以上述刺激剂攻击1 h均能不同程度致敏O-2的产生,且致敏程度在一定范围内与LPS剂量和作用时间相关;细胞内静息态[Ca2+]i也呈LPS剂量和时间依赖性升高,均显著相关.且LPS预处理后用PMA攻击,细胞内瞬时[Ca2+]i升高幅度明显高于LPS未处理组.用A23187使细胞内[Ca2+]i升高可代替LPS致敏O-2的产生,而预先用BAPTA和EGTA降低细胞内[Ca2+]i则可阻断LPS致敏O-2的作用.结论LPS可致敏Mφ产生O-2;LPS预处理后细胞内静态[Ca2+]i的升高是LPS诱导O-2致敏的重要原因.     

LPS致敏巨噬细胞产生O_2~及其信号机制

目的 :探讨LPS诱导的巨噬细胞 (MΦ)致敏及其信号机制。方法 :巨噬细胞样细胞株RAW 2 6 4 .7以10 μg/LLPS预处理 1h后洗去 ,再以 1mg/LPMA、1μmmol/LfMLP、10 0 μg/LLPS、1g/LZyms和 15mg/LMDP攻击 1h ,检测上清中超氧阴离子 (O 2 )的产生 ,并用荧光显微成像系统检测细胞内游离钙离子浓度 ( [Ca2 +]i) ,探讨 [Ca2 +]i与LPS致敏MΦ产生O 2 的关系。结果 :LPS预处理后以上述刺激剂攻击 1h均能不同程度致敏O 2 的产生 ,且致敏程度在一定范围内与LPS剂量和作用时间相关 ;细胞内静息态 [Ca2 +]i也呈LPS剂量和时间依赖性升高 ,均显著相关。且LPS预处理后用PMA攻击 ,细胞内瞬时 [Ca2 +]i升高幅度明显高于LPS未处理组。用A2 3187使细胞内 [Ca2 +]i升高可代替LPS致敏O 2 的产生 ,而预先用BAPTA和EGTA降低细胞内 [Ca2 +]i则可阻断LPS致敏O 2 的作用。结论 :LPS可致敏MΦ产生O 2 ;LPS预处理后细胞内静态 [Ca2 +]i的升高是LPS诱导O 2 致敏的重要原因。     

α-MSH对脂多糖诱导小鼠腹腔巨噬细胞CD14和TLR4 mRNA 表达的影响

目的：观察α-黑色素细胞刺激素(α-MSH)对脂多糖（LPS）诱导小鼠腹腔巨噬细胞CD14和TLR4 mRNA表达的影响，探讨α-MSH拮抗LPS的作用机制。方法：用半定量逆转录多聚酶链反应（RT-PCR）的方法检测LPS诱导体外培养的小鼠腹腔巨噬细胞CD14和TLR4 mRNA表达水平和给予α-MSH后对CD14和TLR4 mRNA表达的影响。结果：正常静息小鼠腹腔巨噬细胞只表达少量的CD14和TLR4 mRNA,给予LPS刺激后6 h，两者表达明显强于正常对照（P<0.01），并且其表达量随着LPS刺激时间的增加维持在高水平，24 h达到峰值，在48 h CD14 mRNA的表达降到正常水平，而TLR4 mRNA的表达仍然维持在高水平。在LPS刺激的同时给予α-MSH，CD14和TLR4 mRNA的表达则明显低于LPS组（P<0.05），而且α-MSH这种效应与其使用浓度有关，0.1 nmol/L α-MSH不影响LPS诱导的CD14和TLR4 mRNA的表达，而当α-MSH的浓度达到1、10、100 nmol/L则能显著影响CD14和TLR4 mRNA的表达（P<0.05），但各个浓度组之间的作用没有明显差别（P>0.05）。结论：α-MSH抗LPS的效应可能与其下调LPS信号转导通路关键受体CD14和TLR4 mRNA的表达有关，从而干扰LPS跨膜信号转导，阻碍巨噬细胞活化。     

LPS致敏巨噬细胞产生O-2及其信号机制

目的：探讨LPS诱导的巨噬细胞(MΦ)致敏及其信号机制。方法：巨噬细胞样细胞株RAW264．7以10μg/L LPS预处理1h后洗去，再以1mg／L PMA、1μmmol／L fMLP、100μg／L LPS、1g／L Zyms和15mg／L MDP攻击1h，检测上清中超氧阴离子(O2^-)的产生，并用荧光显微成像系统检测细胞内游离钙离子浓度([Ca^2 ]i)，探讨[Ca^2 ]i与LPS致敏MΦ产生O2^-的关系。结果：LPS预处理后以上述刺激剂攻击1h均能不同程度致敏O2^-的产生，且致敏程度在一定范围内与LPS剂量和作用时间相关；细胞内静息态[Ca^2 ]i也呈LPS剂量和时间依赖性升高，均显著相关。且LPS预处理后用PMA攻击，细胞内瞬时[Ca^2 ]i升高幅度明显高于LPS未处理组。用A23187使细胞内[Ca^2 ]i升高可代替LPS致敏O2^-的产生，而预先用BAPTA和EGTA降低细胞内[Ca^2 ]i则可阻断LPS致敏O2^-的作用。结论：LPS可致敏MΦ产生O2^-；LPS预处理后细胞内静态[Ca^2 ]i的升高是LPS诱导O2^-致敏的重要原因。     

脂多糖诱导小鼠肺损伤模型巨噬细胞活化及共刺激分子CD40上调研究

目的观察肺泡巨噬细胞（AM）活化过程和共刺激分子CD40表达变化，探讨其在脂多糖（LPS）诱导的小鼠急性肺损伤（ALI）模型中所发挥的作用。方法BALB／c小鼠分为正常对照组和LPS处理组。光镜观察24、48h肺组织病理变化；RT-PCR测定活化巨噬细胞（activated macrophage，AMφ）中TLR4表达；电泳迁移率变动分析（EMSA）检测AMφ核提取物中NF-κB的活性；Northern blot检测CD40 mRNA表达，流式细胞术检测CD40蛋白表达；ELISA测定肺泡灌洗液（BALF）中TNF-α、MIP-2及IL-1β的含量。结果小鼠吸入LPS后，肺泡隔断裂、肺间质充血及肺泡腔中性粒细胞浸润，并检测到AMφ表面TLR4的表达、核转录因子NF-κB活性增强、共刺激分子CD40mRNA和蛋白显著表达，并随着时间延长出现增加趋势，BALF中炎症因子释放增加，正常对照组无明显变化（P〈0．05）。结论LPS诱导的ALI中，AM活化和共刺激分子CD40上调，导致瀑链式炎症反应，造成肺急性炎症损伤。     

人参二醇组皂苷对内毒素休克大鼠脑皮质TLR4 mRNA表达的影响

目的：通过观察内毒素休克大鼠脑皮质中NOS活性、NO含量和TLR4 mRNA的表达及人参二醇组皂苷（PDS）对其的影响，探讨内毒素引起脑组织损伤的分子机制。 方法： 大鼠随机分为实验对照（control）组、内毒素休克（LPS）组、地塞米松（LPS+Dex）组和人参二醇组皂苷（LPS+PDS）组。大鼠静脉注射内毒素（4 mg/kg）4 h后测定脑组织中NOS活性、NO含量及TLR4 mRNA的表达。 结果： LPS+Dex组和LPS+PDS组NOS活性、NO2-/NO3-含量显著低于LPS组（P＜0.05），TLR4 mRNA表达亦明显低于LPS组。 结论： PDS能够下调脑组织中TLR4 mRNA的表达，降低NOS活性、NO含量，对中枢神经系统具有保护作用。     

α-MSH对脂多糖诱导小鼠腹腔巨噬细胞SOCS-3mRNA表达的影响

目的:观察α-黑色素细胞刺激素(α-MSH)对脂多糖(LPS)诱导小鼠腹腔巨噬细胞SOCS-3mRNA表达及NO释放的影响,以探讨α-MSH拮抗LPS的作用机制。方法:用半定量逆转录多聚酶链反应(RT-PCR)的方法检测LPS诱导体外培养的小鼠腹腔巨噬细胞SOCS-3mRNA表达水平和给予α-MSH后对SOCS-3mRNA表达的影响;用Griess试剂检测单独给予LPS与同时给予α-MSH和LPS作用巨噬细胞后对NO生成量的影响。结果:未受LPS刺激的小鼠腹腔巨噬细胞表达低水平的SOCS-3。LPS组SOCS-3的表达和NO的生成显著高于对照组,而同时给予α-MSH和LPS培养,巨噬细胞的SOCS-3的表达明显低于LPS组,NO的生成则几乎完全阻断。结论:LPS在启动炎症的过程中可能也激活了SOCS介导的负调节机制;但SOCS可能不参与α-MSH的抗LPS作用。     

UⅡ／UT系统对LPS刺激枯否细胞固有免疫炎症信号通路TLR4-IRF3的影响

目的：探讨Urotensin Ⅱ（ UⅡ）/UT系统对脂多糖（ Lipopolysaccharide ,LPS）刺激枯否细胞（ Kupffer cell ,KC）固有免疫炎症信号通路Toll样受体4（Toll-like receptor 4,TLR4）-干扰素调节因子3（Interferon regulatory factor 3,IRF3）的影响。方法：体外分离培养大鼠肝KCs,KCs培养上清液促炎性细胞因子IL-6、IFN-β和IFN-γ分泌水平采用ELISA分析检测,细胞表面TLR4的表达采用流式细胞技术分析,IRF3基因和蛋白表达情况分别采用real-time PCR和Western blot 分析方法检测。结果：LPS刺激后,KCs培养上清液IL-6、IFN-β和IFN-γ分泌水平、细胞表面TLR4表达阳性细胞率及细胞内IRF3 mRNA表达水平均显著升高,UT拮抗剂urantide预处理抑制了LPS刺激诱导KCs对上述分子的上调表达;LPS的应用也造成了KCs胞核内IRF3蛋白表达水平升高,而使胞浆内IRF3蛋白表达水平降低,urantide预处理后,抑制了LPS诱导KCs核内IRF3蛋白上调和胞浆水平下调。结论：UⅡ/UT系统通过对TLR4-IRF3通路的正性调控作用,介导了或至少部分介导了LPS刺激KCs的免疫性炎症分泌效应。     

抑制内质网钙离子释放在诱导巨噬细胞自噬及逆转LPS耐受中的作用

目的观察LPS耐受巨噬细胞自噬水平以及抑制内质网Ca2+释放是否具有上调自噬水平和逆转LPS耐受的作用。方法分离Balb/c小鼠腹腔巨噬细胞,LPS 5 ng/ml诱导耐受4 h,随后给予LPS 100 ng/ml刺激,ELISA检测TNF-α和IL-6水平,Western blot和免疫荧光检测自噬蛋白(Beclin-1和LC3-Ⅱ/Ⅰ)表达水平,Fluo-4 AM探针检测胞内Ca~(2+)浓度;在LPS刺激的同时给予胞内Ca~(2+)螯合剂(BAPTA)或内质网IP3通道阻断剂(2-APB)或CaMKⅡ抑制剂(KN-93),检测对自噬蛋白LC3-Ⅱ/Ⅰ表达以及TNF-α释放的影响。结果 LPS耐受细胞经LPS再次刺激后,TNF-α、IL-6释放明显减少,自噬水平也显著下降,同时胞内Ca2+水平异常增高;给予BAPTA或2-APB或KN-93能够降低胞内Ca~(2+)水平,上调LC3-Ⅱ/Ⅰ表达,增加TNF-α释放。结论 LPS耐受的巨噬细胞自噬水平显著降低,抑制内质网Ca2+通路是上调自噬水平并逆转LPS耐受的有效途径。     

地塞米松对小鼠脾脏巨噬细胞内TLR4和TLR2表达的影响

为观察小鼠脾巨噬细胞内的TLR4和TLR2在脂多糖 (LPS )刺激后 ,地塞米松 (Dx )对其表达量的影响 ,在向BALB/c小鼠腹腔内注射LPS和Dx后采用贴壁法分离小鼠脾巨噬细胞 ,通过半定量RT PCR方法测定了TLR4和TLR2mRNA的表达量。结果显示 :①LPS刺激后 ,小鼠脾巨噬细胞内TLR4mRNA显著上调 (吸光度比为 0 11) ,TLR2上调不明显 (吸光度比为0 0 0 8) ;②预先注射不同剂量Dx ,分别为 0 1mg/kg、 1mg/kg、 10mg/kg ,再用LPS刺激小鼠。注射了Dx后巨噬细胞TLR4mRNA表达量较单纯注射LPS的小鼠显著降低 (吸光度比分别为 0 0 93、 0 0 5 0和 0 0 14 ) ;但TLR2mRNA表达量随着Dx使用剂量增加而增加 (吸光度比分别为 0 0 5 4、 0 0 80和 0 16 1)。该项研究表明TLR4是参与LPS引起炎症反应的主要Toll样受体 ,而TLR2不起主要作用 ;Dx对LPS刺激后TLR 4mRNA的表达有抑制作用 ,而对TLR2mRNA的表达有增强作用 ;Dx抑制LPS引起的炎症反应可能与抑制TLR4的表达有关     

Lipopolysaccharide primes macrophages to increase nitric oxide production in response to Staphylococcus aureus

Sepsis, the leading cause of death in intensive care units, is associated with overproduction of nitric oxide (NO). The mechanism concerning the NO production in the sepsis caused by both Gram-negative and Gram-positive bacteria is largely unknown. The present study examines the effect of lipopolysaccharide (LPS) on Staphylococcus aureus-induced NO production in macrophages. In the na?ve murine macrophage cell line RAW264.7, heat-killed Staphylococcus aureus (HKSa) induced a significant NO production at a high concentration (100 microg/ml). However, pretreatment of the cells with increasing concentration of LPS (10-50 ng/ml) resulted in induction of NO production by HKSa even at the doses of 1 and 10 microg/ml. The expression of inducible NO synthase (iNOS) in response to HKSa was also enhanced by LPS pretreatment, suggesting that LPS priming NO production is due to the enhancement of iNOS expression. We examined whether protein kinase C (PKC), mitogen-activated protein kinases (MAPKs) and calcineurin signaling pathways are involved in the priming effects of LPS. It was found that the PKC inhibitor G?6976, the p38 inhibitor SB203580 and the calcineurin inhibitor cyclosporine A significantly reversed the priming effects of LPS on HKSa-induced NO production and iNOS expression. In contrast, the ERK1/2 inhibitor PD98059 did not block the induction of priming by LPS. These data support the hypothesis that LPS primes macrophages for enhancement of HKSa-induced NO production, and indicate that PKC, p38 and calcineurin might be involved in the LPS-induced priming.     

Bacterial Cell Wall Constituents Induce Hepcidin Expression in Macrophages Through MyD88 Signaling

Hepcidin is a key regulator of iron recycling by macrophages that is synthesized mainly by hepatocytes but also by macrophages. However, very little is known about the molecular regulation of hepcidin in macrophages. In the present study, we investigated hepcidin regulation in the RAW264.7 macrophage cell line and in murine peritoneal macrophages stimulated with different Toll-like receptor (TLR) ligands. We found that TLR-2 and TLR-4 ligands activated hepcidin expression in RAW264.7 cells and in wild-type murine peritoneal macrophages, but not in murine peritoneal macrophages isolated from TLR2(-/-), TLR-4-deficient or MyD88(-/-) mice. IL-6 production by RAW264.7 cells stimulated with lipopolysaccharide (LPS, TLR4 ligand) was enhanced by high amounts of iron present in the culture medium. We conclude that hepcidin expression in macrophages is regulated mainly through TLR2 and TLR4 receptors via the MyD88-dependent signaling pathway and that autocrine regulation of iron accumulation in macrophages by hepcidin may affect the levels of proinflammatory cytokine production.     

肾上腺素对小鼠巨噬细胞中促炎／抗炎介质比值的影响

目的：研究肾上腺素对脂多糖（LPS）诱导的小鼠单核巨噬细胞株RAW264.7中促炎介质［肿瘤坏死因子（TNF-α）、一氧化氮（NO）、环加氧酶-2（COX-2）］和抗炎介质［血红素氧化酶-1（HO-1）、白介素10（IL-10）］表达及NF-κB活化的影响。 方法： 以10 μg/L的LPS刺激体外培养的RAW264.7细胞作为炎症模型，加入不同浓度的肾上腺素（1、5、10、50 μmol/L）孵育24 h后，收集培养上清并提取细胞总蛋白，酶联免疫法测定上清中TNF-α、IL-10浓度，Griess法检测上清NO含量(以NO2-/NO3-表示)，免疫印迹法检测细胞总蛋白中COX-2、HO-1、IκB-α的含量。 结果： 10 μg/L的LPS明显诱导TNF-α、NO(NO2-/NO3-)、COX-2、IL-10及HO-1的产生；LPS+肾上腺素组与LPS单独作用组相比促炎介质TNF-α、NO(NO2-/NO3-)、COX-2的表达量显著下降，而抗炎介质IL-10、HO-1的表达却明显增强；肾上腺素与LPS共同作用组中IκB-α的含量与单独LPS作用组相比无明显差异。 结论： 肾上腺素下调LPS诱导的巨噬细胞中促炎介质的表达同时促进抗炎介质的表达，这种效应并不通过影响NF-κB的活化来实现。     

NOD8对LPS诱导巨噬细胞释放NO、TNF-α和IL-1β的影响

 目的： 探讨NOD8对脂多糖（LPS）诱导巨噬细胞释放一氧化氮（NO）、肿瘤坏死因子α（TNF-α）和白细胞介素1β（IL-1β）的影响。方法： pEGFP-C2及pEGFP-NOD8重组质粒分别转染小鼠巨噬细胞RAW264.7,以LPS刺激RAW264.7细胞0、6、12、24 h后,采用Griess reagent法测定观察细胞分泌的NO水平;ELISA法检测IL-1β 和 TNF-α 的含量;荧光法测定活化的caspase-1水平; Western blotting检测NOD8蛋白表达及NF-κB  p65亚基的核转位情况。结果： (1)与转染pEGFP-C2空质粒组比较,转染pEGFP-NOD8质粒组NOD8蛋白表达明显增加。(2) LPS刺激6、12、24 h后,RAW264.7细胞释放NO、IL-1β及TNF-α均明显增加;而在pEGFP-NOD8+LPS组RAW264.7细胞, NO于12、24 h 的释放显著降低,IL-1β于6、12、24 h的释放也明显降低,TNF-α的释放则无明显变化。（3）在LPS刺激6、12、24 h后, RAW264.7细胞caspase-1活化水平均明显升高,胞浆NF-κB p65亚基表达明显减少,表明p65核转位增加;而pEGFP-NOD8+LPS组可显著抑制caspase-1的活化以及NF-κB p65亚基的核转位,差异有统计学意义。结论： NOD8可抑制LPS诱导的巨噬细胞NO与IL-1β释放,其作用机制可能与NOD8抑制caspase-1及NF-κB 的活化有关。     

Spironolactone inhibits production of proinflammatory mediators in response to lipopolysaccharide via inactivation of nuclear factor-κB

The effect of spironolactone (SPIR) on lipopolysaccharide (LPS)-induced production of proinflammatory mediators was examined using RAW 264.7 macrophage-like cells and mouse peritoneal macrophages. SPIR significantly inhibited LPS-induced production of nitric oxide (NO), tumor necrosis factor-α and prostaglandin E2. The inhibition was not mediated by cell death. SPIR reduced the expression of an inducible NO synthase mRNA in response to LPS. SPIR significantly inhibited phosphorylation of p65 nuclear factor (NF)-κB in response to LPS. Furthermore, SPIR inhibited phosphorylation of IκB kinase (IKK) as an upstream molecule of NF-κB in response to LPS. LPS did not induce the production of aldosterone in RAW 264.7 cells. Taken together, SPIR is suggested to inhibit LPS-induced proinflammatory mediators via inactivation of IKK/NF-κB in LPS signaling.     

Effects of Lycium barbarum polysaccharides with different molecular weights on function of RAW264.7 macrophages

The present study was aimed at investigating the effects of four LBP fractions with different molecular weights (MWs), designated LBP2, LBP3, LBP4 and LBP5, on RAW264.7 macrophages function. Results showed that LBP fractions could significantly enhance the expression of CD86 and MHC-II molecules on RAW264.7 macrophages. LBP3, LBP4 and LBP5 could enhance the production of ROS, NO, TNF-α and IL-6, and the phagocytosis of RAW264.7 macrophages. LBP2 with an MW of larger than 350?kDa could only enhance the secretion of TNF-α. LBP3 enhanced the RAW264.7 macrophages function in a dose-dependent manner and also enhanced the iNOS mRNA expression in the cells. These results demonstrated that the immunomodulatory activity of LBP on RAW264.7 macrophages was closely related to its MW. It indicated that fractions with an MW smaller than 350?kDa were the main active fractions of LBP in enhancing macrophages function.     

Induction of inducible nitric oxide synthase (iNOS) in <Emphasis Type="Italic">Porphyromonas gingivalis</Emphasis> LPS-treated mouse macrophage cell line (RAW264.7) requires Toll-like receptor 9

Objective

The aim of this study is to investigate the involvement of TLR9 in the regulation of iNOS expression and nitric oxide (NO) production in Porphyromonas gingivalis LPS-treated mouse macrophages.

Methods

Mouse macrophage cell line (RAW264.7) was transfected with siRNAs against TLR9 and then stimulated with P. gingivalis LPS. At indicated time points, the activated cells were lysed. Gene and protein expression of iNOS were determined by RT-PCR and immunoblotting, respectively. The level of nitric oxide (NO) production in the supernatant of the activated cells was determined by Griess reaction assay.

Results and conclusion

Depletion of TLR9 in mouse macrophages demonstrated the markedly decreased iNOS gene and protein expression by P. gingivalis LPS compared to those of the wild-type or control siRNA transfected cells. In consistent with these results, the level of NO secretion was also significantly diminished in TLR9-depleted cells after challenged with P. gingivalis LPS. These results indicate that TLR9 involves in the regulation of the iNOS expression and the NO secretion in P. gingivalis LPS-treated macrophages.

     

黄连乙醇提取物与盐酸小檗碱体外抗炎对比研究

目的:比较黄连乙醇提取物与盐酸小檗碱体外抗炎活性,探索体外抗炎机制。方法:通过脂多糖体外刺激小鼠单核巨噬细胞建立细胞炎症模型,给药干预后,LPS 长时间刺激RAW264.7 细胞,MTT 比色法分析黄连乙醇提取物及盐酸小檗碱对RAW264.7 细胞生长活性的影响。酶联免疫吸附法检测细胞上清液中IL-β、IL-6、TNF-α、NO、前列腺素E2 (PGE2)含量。实时荧光定量RT-PCR 法检测iNos、HO-1、TNF-αmRNA 表达。结果:在5 ~80 mg/ L 范围内,黄连乙醇提取物及盐酸小檗碱对RAW264.7 细胞无抑制作用;各浓度给药组IL-6、IL-1β、TNF-α、NO、前列腺素E2 (PGE2 )含量与LPS 刺激模型组比较均有显著性(P<0.01),且浓度与剂量无效应相关。实时荧光定量RT-PCR 结果显示,各浓度给药组均明显降低iNos、HO-1、TNF-αmRNA 表达(P<0.05,P<0.05,P<0.01),且与浓度不呈效应关系。结论:黄连乙醇提取物具有体外抗炎作用,抗炎活性优于盐酸小檗碱,其作用机制可能与抑制TNF-α、NO 等炎症因子的活化,进而影响花生四烯酸(AA)代谢有关。