α-促黑素细胞激素抑制RAW264.7细胞产生炎症相关的免疫分子

目的 研究α-促黑素细胞激素（α-MSH）对巨噬细胞产生炎症相关的免疫分子的影响。探讨α-MSH的抗炎作用机制。方法 分别用LPS或α-MSH PLS处理体外培养的小鼠巨噬细胞系RAW264.7细胞,以Griess试剂测定NO,采用DADPH-黄递酶组织化学染色法检测iNOS,采用MTT法检测IL-1和TNF-α,采用ELISA法测定IL-6,细胞膜表面免疫相关分子的表达用FACS进行分析。结果 RAW264.7细胞在LPS刺激下产生NO、IL-1、IL-6和TNF-α显著增多,iNOS活性明显增强,细胞表面MHC Ⅱ、CD14、CD40、CD54、CD80和CD86分子表达水平增高;若在LPS刺激的同时给予α-MSH,能够抑制LPS诱导RAW264.7细胞产生NO,IL-1、IL-6和TNF-α,使iNOS活性及表达MHCⅡ、CD14、CD40、CD54、CD86分子降低,但CD80分子降低不明显。结论 α-MSH抑制巨噬细胞产生NO、iNOS、前炎性细胞因子及表达膜表面免疫相关分子是其抗炎作用的重要机制之一。     

lncRNA MIAT 在巨噬细胞炎症反应中的作用

目的:探索长链非编码RNA心肌梗死转录本(lncRNA MIAT)在巨噬细胞炎症反应中的作用及其可能参与的炎症通路。方法:脂多糖(LPS)刺激小鼠巨噬细胞J774A.1制备炎症反应细胞模型(LPS组),以等体积PBS刺激的J774A.1细胞为PBS对照组(PBS组),实时定量PCR(RT-qPCR)及ELISA法检测两组IL-1β、TNF-α的mRNA及蛋白表达水平,RT-qPCR检测lncRNA MIAT在两组的表达量及亚细胞定位;shRNA敲低lncRNA MIAT,分为shMIAT敲低(KD)组、shNC阴性对照(NC)组,RT-qPCR检测lncRNA MIAT敲低效率及两组IL-1β、TNF-αmRNA相对表达量;Western blot检测KD、NC组的NF-κB、ERK5等多种转录因子磷酸化水平;在LPS刺激J774A.1细胞分别加入ERK5特异性抑制剂(ERK5-IN-2)、ERK5-IN-2溶解液二甲基亚砜(DMSO),分为抑制剂组、DMSO对照组,Western blot检测ERK5磷酸化水平,RT-qPCR检测两组IL-1β、TNF-αmRNA相对表达量。结果:LPS组IL-1β、TNF-αmRNA相对表达水平及蛋白表达水平均高于PBS组(P0.05);lncRNA MIAT在LPS组相对表达量显著高于PBS组,且主要表达于细胞核;lncRNA MIAT在KD组显著低于NC组,其在J774A.1细胞的敲低效率为43%。KD组IL-1β、TNF-αmRNA相对表达量显著高于NC组;KD组ERK5磷酸化程度显著高于NC组,而NF-κB、STAT3、ERK1/2磷酸化水平差异无统计学意义;抑制剂组EKR5磷酸化显著低于DMSO对照组,且抑制剂组的IL-1β、TNF-αmRNA相对表达水平显著低于DMSO对照组。结论:lncRNA MIAT可能通过抑制ERK5磷酸化减少IL-1β、TNF-α合成,从而抑制巨噬细胞炎症反应。     

UⅡ/UT系统在LPS刺激大鼠肝枯否细胞前炎细胞因子TNF-α和IL-1β表达与分泌中的作用研究

目的探讨UⅡ/UT系统在LPS刺激大鼠肝枯否细胞(Kupffer cell,KC)TNF-α和IL-1β表达和分泌中的作用。方法采用胶原酶灌注消化和密度梯度离心分离大鼠KC。细胞分组和处理方法:正常对照组urantide(-)LPS(-)、urantide或UⅡ处理组urantide/UⅡ(+)LPS(-)、LPS刺激组urantide(-)LPS(+)、urantide或UⅡ预处理组urantide/UⅡ(+)LPS(+);细胞内基因表达采用RT-PCR和real-time PCR方法检测,细胞培养上清液中蛋白质分泌水平采用ELISA分析方法检测。结果 LPS刺激后,KC内UⅡ、UT mRNA相对表达水平和细胞培养上清液UⅡ多肽水平显著升高,但urantide预处理组显著低于LPS刺激组(P0.01)。Urantide处理组细胞UⅡ/UT mRNA和上清液UⅡ多肽水平与正常对照组之间无明显统计学差异(P0.05);LPS刺激后(LPS刺激组、UⅡ预处理组和urantide预处理组),TNF-α和IL-1βmRNA表达和蛋白质分泌水平较正常对照组明显升高(P0.01),但urantide预处理组较LPS刺激组和UⅡ预处理组显著降低(P0.01),LPS刺激组与UⅡ预处理组之间无明显统计学差异(P0.05)。UⅡ或urantide处理组KC上述前炎细胞因子的表达和分泌水平与正常对照组之间无明显统计学差异(P0.05)。结论 UⅡ/UT信号系统可能在LPS刺激肝KC前炎细胞因子TNF-α和IL-1β的表达和分泌中起重要作用。     

CD14抑制肽对内毒素诱导U937细胞表达TNF-α的影响

目的 观察CD14抑制肽(CD14 inhibitory peptide,CD14-IP)对内毒素诱导的U937细胞表达TNF-α的影响.方法 U937细胞用佛波脂(PMA)诱导成熟后分5组:正常对照组、LPS组、高剂量抑制肽组、中剂量抑制肽组和低剂量抑制肽组.LPS组给予终浓度为100 ng/mL的LPS和100 ng/mL的LBP,高、中和低剂量抑制肽组除给予LPS和LBP外,分别给予终浓度为10 μg/mL、1.0 μg/mL和0.1 μg/mL的CD14-IP.ELISA测定细胞培养上清NNF-α的浓度.进一步观察不同时间应用CD14-IP(1.0 μg/mL)对LPS诱导U937细胞TNF-α和NTF-α mRNA表达的影响.用RT-PCR测定细胞TNF-α mRNA的表达.结果 LPS组和抑制肽各组TNF-α浓度较正常组明显增高(P<0.05),高、中剂量抑制肽组TNF-α水平比LPS组明显降低(P<0.05),高、中剂量抑制肽组之间TNF-α浓度无明显差别(P>0.05),低剂量抑制肽组TNF-α浓度与LPS组无统计学差异(P>0.05).不同时间应用CD14-IP时,CD14-IP早期应用对TNF-α和TNF-α mRNA的表达抑制作用显著.结论 CD14-IP能显著减少LPS诱导的U937细胞TNF-α和TNF-α mRNA的表达,早期应用效果较好,可能对LPS所致急性肺损伤有保护作用.     

MBL对LPS刺激的不同分化和活化状态THP1/CD14细胞产生TNF-α和IL-12的影响

目的探讨甘露聚糖结合凝集素（MBL）对脂多糖（LPS）刺激的不同分化和活化状态THP1/CD14细胞产生TNF-α和IL-12的影响.方法用PMA和/或IFN-γ诱导不同分化和活化状态的THP1/CD14细胞,以不同浓度人MBL预处理2 h后再用光滑型LPS刺激24h.收集培养上清,以ELISA从蛋白水平分析其TNF-α和IL-12 p40＋p70的产生.收集细胞提取总RNA,以RT-PCR从转录水平评估TNF-α和IL-12的表达.结果ELISA检测发现,LPS可刺激各组细胞分泌TNF-α和IL-12 p40＋p70;IFN-γ活化的THP1/CD14细胞产生IL-12 p40＋p70最高,PMA分化的THP1/CD14细胞最低;PMA分化＋IFN-γ活化的THP1/CD14细胞分泌TNF-α最高,未用PMA或IFN-γ预刺激的THP1/CD14细胞最低.高浓度MBL（50～100 mg/L）可抑制LPS诱导细胞分泌TNF-α和IL-12 p40＋ p70的作用,低浓度MBL（1～10 mg/L）则几无影响.RT-PCR分析亦显示,与相应只用LPS刺激的实验组相比,高浓度MBL（50 mg/L）对不同实验组LPS诱导的TNF-α、IL-12 p35和p40的mRNA表达均有不同程度的抑制作用.结论MBL可抑制LPS诱导的不同分化和活化状态THP1/CD14细胞产生TNF-α和IL-12,THP1/CD14细胞可用做进一步剖析MBL在免疫应答与细胞因子网络调控中的作用及其机理的模型.     

CD14、MD-2 在LPS 致乳腺上皮细胞炎症中的作用

目的:探究LPS致乳腺上皮细胞(MECs)炎症中白细胞分化抗原14(CD14)、髓样分化蛋白2(MD-2)的作用。方法:采用MTT法和流式细胞术检测LPS对小鼠MECs的刺激条件,PCR和流式细胞术检测MECs上CD14、MD-2的表达;siRNA沉默CD14、MD-2基因,通过流式细胞术检测FITC-LPS与细胞的结合率,ELISA法检测LPS介导炎症因子TNF-α、IL-6及IL-1β表达来研究CD14、MD-2在LPS致MECs炎症中的作用。结果:LPS作用于细胞IC_(50)为76.83μg/ml;当5～10μg/ml浓度的LPS刺激细胞6～12 h时,LPS与细胞的结合趋于饱和;基因和蛋白水平都表明MECs上有CD14、MD-2表达,CD14、MD-2基因沉默后,LPS与小鼠MECs结合率被抑制,同LPS组相比分别下降7.88%、3.00%、13.41%(P0.01),同时LPS介导细胞分泌TNF-α、IL-6及IL-1β的量(P0.05、P0.01)也显著或极显著下降。结论:MECs上有CD14、MD-2的存在,它们是乳腺细胞胞外LPS-TLR4炎症信号途径重要基因。     

严重烧伤大鼠在体肺泡巨噬细胞CD14的表达调控对内毒素和细胞因子的影响

目的 探讨严重烧伤和内毒素(LPS)对大鼠肺泡巨噬细胞(AM)CD14膜蛋白(CD14)和mRNA基因表达变化的影响,以及抗CD14抗体拮抗前后AM产生肿瘤坏死因子α(TNF-α)和白细胞介素6(IL-6)的影响及调控作用.方法 (1)体内部分:取成年SD大鼠96只,随机分为烧伤组、烧伤对照组、LPS组和LPS对照组,烧伤组和LPS组各42只,两组各分为1 h、2 h、4 h、6 h、8 h、12 h共7个时相点,每时相点6只大鼠.烧伤对照组和LPS对照组各6只大鼠,只检测一个时相点.烧伤组和LPS组分别在大鼠20%Ⅲ度烧伤和LPS注射后各时相点抽取外周血后立即处死行全肺在体支气管肺泡灌洗(BAL)分离提取相应各组AM.外周血检测外周血LPS浓度,各时相点灌洗提取的AM分别用RT-PCR方法观察相同时相点CD14 mRNA表达、免疫组织化学方法观察蛋白含量变化;(2)体外部分:取成年SD大鼠168只,随机分为烧伤血清组、血清抗体组、LPS组、LPS抗体组,每组42只,每组再分为1 h、2 h、4 h、6 h、8 h、12 h共7个时相点,每时相点6只大鼠.另设烧伤对照组和LPS对照组,各6只成年SD大鼠.各组大鼠行全肺在体支气管肺泡灌洗分离AM,并按时相点分别进行体外培养,前四组分别加入烧伤血清、烧伤血清+抗体、LPS、LPS+抗体,在以上相同时相点终止培养,RT-PCR、免疫组化及ELISA方法分别检测四组肺泡巨噬细胞在各时相点CD14mRNA表达、蛋白表达及分泌TNF-α和IL-6的变化.结果 (1)体内部分:烧伤组及LPS组注射后大鼠各时相点外周血LPS浓度均明显高于相应对照组(P<0.01).在体大鼠AM各时相点CD14 mRNA表达与烧伤对照组比较均明显增高(P<0.01);(2)体外部分:烧伤血清组与烧伤对照组比较,LPS组和LPS对照组比较发现,烧伤血清组、LPS组大鼠AM各时相点CD14 mRNA表达、蛋白表达均明显增高,AM培养上清中TNF-α和IL-6浓度亦相应显著增高(P<0.01).以烧伤血清与AM培养1 h后,烧伤血清组培养上清中TNF-α和IL-6浓度即显著增加.与烧伤血清组比较,血清抗体组肺泡巨噬细胞在各时相点CD14 mRNA表达、蛋白表达显著降低(P<0.01),TNF-α和IL-6浓度亦显著降低(P<0.01).与LPS组比较,LPS抗体组肺泡巨噬细胞在各时相点CD14 mRNA表达、蛋白表达显著降低(P<0.01),TNF-α和IL-6浓度亦显著降低(P<0.01).结论 严重烧伤后外周血LPS浓度增加,在体肺泡巨噬细胞CD14 mRNA表达显著增加,离体肺泡巨噬细胞CD14 mRNA表达和蛋白表达均显著增加,使LPS对免疫系统的激活作用显著增大,AM分泌TNF-α和IL-6明显增加,而抗CD14抗体可以明显拮抗AM合成和分泌炎性介质.提示严重烧伤后通过调节CD14的作用而减少炎性介质的合成和分泌是可行的.     

树突状细胞体外诱导方案的对比

目的探讨并比较不同细胞因子组合、诱导时间对树突状细胞(DC)体外诱导、成熟,分泌细胞因子水平和刺激淋巴细胞增殖能力的影响,为建立DC体外高效、规模化培育体系提供依据。方法分离健康人外周血单个核细胞(PBMC),贴壁法获得DC前体细胞,用白细胞介素4(IL-4)和粒细胞巨噬细胞集落刺激因子(GM-CSF)诱导2 d,将其分为6组。A组加入肿瘤坏死因子α(TNF-α)、IL-1α和前列腺素E2(PGE2);B组加入α干扰素(IFN-α);C组加入脂多糖(LPS);3组细胞继续培育2 d。D~F组细胞先进行1/3体积换液,24 h后,分别再加入上述A~C组的成熟因子,再继续诱导2 d。分别收获各组上清和细胞,进行细胞计数,采用流式细胞术进行表型分析;采用ELISA检测各组DC分泌IL-12p70的水平、采用细胞增殖检测试剂盒刺激淋巴细胞增殖的能力。结果 6组体外诱导体系均能培育出形态学类似DC的细胞,DC数量与纯度(均达到96%以上),各组间无显著性差异。A组与D组比较:CD40、CD80、CD83、CD86共刺激分子表达水平相近,但D组DC分泌IL-12p70水平高于A组;B组与E组比较:E组DC的CD86表达水平显著高于B组,CD80表达量略高于B组,2组DC分泌IL-12p70的水平相近;C组与F组比较:CD40、CD80、CD83、CD86共刺激分子表达水平和分泌IL-12p70的水平均相近。6组DC刺激淋巴细胞增殖水平均相近。三种不同成熟因子(组合)比较:B组DC共刺激分子CD80水平明显低于C组和A组,且IL-12p70分泌水平最低,而C组和A组共刺激分子表达水平与IL-12p70分泌水平相近。结论 TNF-α、IL-1α和PGE-2三种细胞因子联合以及LPS可有效地诱导DC表达高水平免疫共刺激分子、分泌高水平IL-12p70。     

RhoA/ROK信号通路对LPS诱导的人外周血单核细胞分泌细胞因子的调控作用

目的 探讨RhoA／ROK信号通路对人外周血单核细胞分泌TNF-α、IL-1β、IL-6、IL-8等细胞因子的调控作用。方法 用Percoll非连续性密度梯度离心法分离单核细胞，并用LPS诱导人外周血单核细胞活化；Pull down方法检测用RhoA活性，ROK活性用其底物MBS的磷酸化来表示，总RhoA、ROK及磷酸化MBS蛋白表达用免疫印迹法测定，用ELISA法检测细胞因子水平。结果 LPS可诱导单核细胞RhoA快速活化，并呈时间依赖性，Pho特异性抑制剂C3转化酶能显著抑制LPS诱导的人外周血单核细胞分泌TNF-α、IL-1β、IL-6、IL-8等细胞因子；LPS亦可诱导单核细胞ROK活化，ROR特异性抑制剂Y27632可显著降低LPS刺激的人外周血单核细胞分泌TNF-α、IL-1β、IL-6、IL-8等细胞因子。结论 LPS可活化人外周单核细胞RhoA／ROK信号通路，选择性抑制RhoA和ROK活化能抑制单核细胞分泌多种细胞因子，提示RhoA／ROK信号通路可能在调控单核细胞分泌细胞因子中发挥重要作用。     

IL-37抑制脂多糖诱导的小鼠树突状细胞活化

目的探讨白细胞介素37(IL-37)对细菌脂多糖(LPS)诱导的小鼠树突状细胞(DC)活化的调节作用。方法应用GM-CSF和IL-4诱导小鼠骨髓细胞向DC分化,抗CD11c磁珠分选DC。IL-37预处理DC后,进行LPS刺激。流式细胞术检测DC表面共刺激分子(CD80、CD86)表达水平,实时荧光定量PCR检测肿瘤坏死因子α(TNF-α)、IL-6和IL-1αmRNA表达水平,流式细胞微球芯片试剂盒(CBA试剂盒)检测细胞培养上清中IL-1α、IL-6、TNF-α等因子的浓度。结果 DC诱导成功,磁珠分选能够获得高纯度的DC(>90%)。IL-37降低LPS诱导的DC表面共刺激分子CD80、CD86的表达,并抑制DC合成IL-1α、IL-6、TNF-α。结论 IL-37可以通过降低共刺激分子和炎症因子的表达抑制LPS刺激的DC活化。     

Influence of synthetic antiendotoxin peptides on lipopolysaccharide (LPS) recognition and LPS-induced proinflammatory cytokine responses by cells expressing membrane-bound CD14

Lipopolysaccharides (LPS) are proinflammatory bacterial products implicated in the pathogenesis of gram-negative sepsis and septic shock. Polymyxin B (PMB), a cyclic, cationic peptide antibiotic, inhibits biological activities of LPS through high-affinity binding to the lipid A moiety. Small synthetic peptides have been designed to mimic the primary and secondary structures of PMB to determine structural requirements for binding and detoxification of lipid A and to assess possible therapeutic potential. The purpose of this study was to compare and contrast the endotoxin-neutralizing activities of two synthetic antiendotoxin peptides (SAEP-2 and SAEP-4), PMB, and an LPS core-specific monoclonal antibody (MAb), WN1 222-5, based on their abilities to inhibit CD14-mediated target cell uptake of fluorescein isothiocyanate (FITC)-conjugated LPS, detected by flow cytometry and confocal microscopy, and LPS-induced production of the proinflammatory cytokines, interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-alpha), as measured by bioassays. PMB and SAEP-4 produced dose-dependent inhibition of FITC-LPS uptake by CD14-transfected Chinese hamster ovary fibroblasts (CHO-CD14 cells) and by human peripheral blood mononuclear cells. The anti-LPS MAb, WN1 222-5, also blocked LPS uptake by these cells and synergized with PMB and SAEP-4. LPS-induced IL-6 release was inhibited by PMB, SAEP-4, and MAb WN1 222-5, and these inhibitory activities were additive or synergistic. LPS-induced TNF-alpha release by PBMC was also inhibited by PMB and SAEP-4 alone and in combination with anti-LPS MAb. SAEP-2, in contrast, produced comparatively minor decrements in cellular uptake of LPS and LPS-induced cytokine responses, and did so only in the absence of serum, while a nonsense peptide exerted no discernible inhibitory effect on LPS uptake or LPS-induced cytokine expression in the presence or absence of serum. Thus, PMB and SAEP-4, like the LPS-reactive MAb, WN1 222-5, block proinflammatory activities of LPS in part by preventing LPS recognition by membrane-bound CD14-expressing target cells. Differences in peptide structure, however, like those exemplified by SAEP-2 and SAEP-4, may differentially affect the endotoxin-neutralizing potency of these peptides despite similar binding activity against lipid A, reflecting possible differences in peptide solubility or peptide regulation of intracellular signal transduction.     

Lipopolysaccharide complexed with soluble CD14 binds to normal human monocytes

Using flow cytometry we have compared the binding of Neisseria meningitidis lipopolysaccharide labeled with fluorescein isothiocyanate (FITC-LPS) to normal human monocytes in whole blood with the binding to Chinese hamster ovary (CHO) cells transfected with human CD14 gene (hCD14-CHO cells). Binding of FITC-LPS to cells was dose dependent, saturable and enhanced in the presence of increasing concentrations of serum. Blockade of membrane CD14 with saturating concentrations of anti-CD14 monoclonal antibody (mAb) My4 inhibited 50% of the binding of FITC-LPS to monocytes and 100% to hCD14-CHO cells. Similarly, removal of membrane CD14 by phosphatidylinositol phospholipase C (Pl-PLC) treatment of the cells partially decreased the binding of FITC-LPS to monocytes but totally inhibited the binding to hCD14-CHO-transfected cells. These results suggest that binding of FITC-LPS to monocytes is not only mediated by membrane CD14. Using two-color flow cytometry, we observed that FITC-LPS binds to My4-saturated monocytes in association with soluble (s)CD14 present in serum as revealed by staining with rhodaminelabeled My4 mAb. The binding of FITC-LPS/sCD14 complexes to monocytes treated with saturating amounts of unlabeled My4 prior to addition of the complexes was completely inhibited by anti-CD14 mAb 10G33. When cells were first saturated with a mixture of My4 and 10G33 mAb, washed and further incubated with FITC-LPS/sCD14, inhibition of the binding of LPS was similar to that observed with cells saturated with My4 alone, showing that the binding of FITC-LPS is not mediated by the 10G33 epitope present on mCD14. These results suggest that either the 10G33 epitope on sCD14 is involved in the binding of LPS/sCD14 complexes to the cells, or that 10G33 mAb inhibits the binding of FITC-LPS to sCD14. Taken together, these data indicate that sCD14 which is present in normal serum, in addition to membrane CD14, enables LPS to bind monocytes through an as yet unidentified molecule and that sCD14 does not simply serve as a shuttle for transfer of LPS to membrane CD14.     

Saturable CD14-dependent binding of fluorescein-labeled lipopolysaccharide to human monocytes.

We used rough lipopolysaccharide (ReLPS) to construct a fluorescein-labeled LPS (FITC-LPS) with a very high labeling efficiency that bound to isolated human monocytes in a CD14-dependent fashion and that in this respect behaved indistinctively from native LPS. The CD14-dependent binding could be inhibited either by a 1,000-fold excess of unlabeled LPS or by polymyxin B, bactericidal/permeability-increasing protein, cationic protein 18, or soluble CD14. Although this FITC-LPS preparation no longer possessed the ability to prime neutrophils for the production of reactive oxygen species or to stimulate human monocytes to produce tumor necrosis factor, activation of the Limulus amoebocyte lysate cascade was comparable to activation by native LPS. Binding to monocytes was enhanced by human pooled serum (HPS) or LPS-binding protein (LBP) for LPS concentrations up to 100 ng/ml and was completely CD14 dependent. For LPS concentrations exceeding 100 ng/ml, binding was still partially CD14 dependent, but not HPS or LBP dependent. CD14-dependent association of LPS with monocytes was shown to be totally saturable. In conclusion, we found an HPS- or LBP-dependent binding of FITC-LPS to monocytes that was CD14 dependent at up to 100 ng of LPS per ml, and saturation of binding was shown.     

Adherent invasive Escherichia coli strains from patients with Crohn's disease survive and replicate within macrophages without inducing host cell death

Escherichia coli strains recovered from Crohn's disease (CD) lesions are able to adhere to and invade cultured intestinal epithelial cells. We analyzed the behavior within macrophages of adherent invasive E. coli (AIEC) strains isolated from patients with CD. All the 15 AIEC strains tested were able to replicate extensively within J774-A1 cells: the numbers of intracellular bacteria increased 2.2- to 74.2-fold at 48 h over that at 1 h postinfection. By use of murine peritoneal macrophages and human monocyte-derived-macrophages, the reference AIEC strain LF82 was confirmed to be able to survive intracellularly. Transmission electron micrographs of AIEC LF82-infected macrophages showed that at 24 h postinfection, infected cells harbored large vacuoles containing numerous bacteria, as a result of the fusion of several vacuoles occurring after 8 h postinfection. No lactate dehydrogenase (LDH) release, no sign of DNA fragmentation or degradation, and no binding to fluorescein isothlocyanate-labeled annexin V were observed with LF82-infected J774-A1 cells, even after 24 h postinfection. LF82-infected J774-A1 cells secreted 2.7-fold more tumor necrosis factor alpha (TNF-alpha) than cells stimulated with 1 microg of lipopolysaccharide (LPS)/ml. No release of interleukin-1beta was observed with LPS-prestimulated J774-A1 cells infected with AIEC LF82. These findings showed that (i) AIEC strains are able to survive and to replicate within macrophages, (ii) AIEC LF82 replication does not induce any cell death of the infected cells, and (iii) LF82-infected J774-A1 cells release high levels of TNF-alpha. These properties could be related to some features of CD and particularly to granuloma formation, one of the hallmarks of CD lesions.     

大鼠枯否细胞CD14表达的实验研究

目的:探讨大鼠枯否细胞(KC)中CD14表达的变化。方法:应用不同浓度(1μg/L-10mg/L)或同一浓度(10mg/L)的脂多糖(LPS)在不同时间(0.5h-24h)刺激培养大鼠48h的KC并测定其CD14、肿瘤坏死因子α(TNFα)和白介素6(IL-6)表达的变化。结果:LPS能明显上调KC中CD14、TLR4表达,且其表达量与LPS浓度及时间呈正相关,且在3-6h左右达到高峰;同时,KC产生的活性介质亦能明显上调其CD14的表达。结论:LPS及其刺激KC后产生的活性介质能明显上调CD14的表达,且在CD14的表达中存在一个自身调节环。     

Antibacterial activity of a synthetic peptide that mimics the LPS binding domain of Indian mud crab, Scylla serrata anti-lipopolysaccharide factor (SsALF) also involved in the modulation of vaginal immune functions through NF-kB signaling

Recently the cDNA coding for anti-lipopolysaccharide factor (ALF) has been identified from the Indian mud crab, Scylla serrata and has been named S. serrata anti-lipopolysaccharide factor (SsALF). SsALF protein sequence demonstrated the presence of two highly conserved cystine residues between which the putative lipopolysaccharide (LPS) binding domain is known to be located. In this study, we have designed and synthesized a 24 amino acid linear (lSsALF24) and a cyclic (cSsALF24) peptides based on this putative LPS binding domain and demonstrated the ability of these peptides to bind to LPS. The peptides were active against vaginal pathogens demonstrated by MIC, CFU and phagocytosis assays. cSsALF24 did not show toxicity to human vaginal epithelial cells (HeLa-S3), macrophages and rabbit erythrocytes even at high concentration (64.64 μM). Flow cytometry results demonstrated that cSsALF24 peptide suppressed LPS induced phagocytosis of FITC labeled E. coli. HeLa cells were stimulated with LPS (10 μg/ml) alone for 6 h or after two washings with PBS, treated for 1 h with cSsALF24 (64.64 μM). After washing, the cells were cultured for 24 h in fresh media. The spent media as well as cells were collected for the determination of cytokine/chemokine levels such as interleukin-6 (IL-6) interleukin-8 (IL-8), monocyte chemotactic protein-1 (MCP-1) and interleukin-1α (IL-1α) using ELISA and RT-PCR respectively. Similar results were obtained with LPS stimulated cells treated with c/nSsALF24 or unstimulated cells treated with c/nSsALF24. The expression of cytokine/chemokines and mRNA’s coding these proteins were unaffected in c/nSsALF24 treated cells. In contrast, in LPS stimulated cells, the expression levels of these molecules were up-regulated via the induction of nuclear factor kappa-B (NF-kB) levels. However, the expression of these pro-inflammatory markers was decreased in LPS stimulated cells following the treatment with cSsALF24, attributing anti-inflammatory potential of the peptide. Collectively, these findings suggest that cSsALF24 might regulate the vaginal epithelial cell immune responses indirectly through modulation of LPS-TLR4 binding in NF-kB pathway.     

Release from a human monocyte-like cell line of two different soluble forms of the lipopolysaccharide receptor,CD14

Lipopolysaccharide (LPS) stimulates mononuclear phagocytes to synthesize and secrete immunoregulatory and inflammatory molecules such as interleukin-1 (IL-1), IL-6, and tumor necrosis factor-α (TNF-α). LPS forms complexes with either the serum protein termed LPS-binding protein or a serum factor, septin. These complexes are more stimulatory than LPS alone. The myeloid differentiation antigen CD14 is known to be the receptor for such complexes. In the present study, by using a monocytic cell line, we demonstrate the release of two different soluble forms of CD14 (sCD14) which are secreted by different mechanisms. We show that the two sCD14 forms differ in their electrophoretic mobility, two-dimensional gel electrophoretic patterns, sensitivity to endoglycosidases and peptide maps. One of the sCD14 molecules, apparent molecular mass 48 kDa, was found in supernatants of both surface iodinated and [³⁵S] methionine biosynthetically labeled cells. The other sCD14 molecule (56 kDa) was found labeled only in supernatants of [³⁵S] methionine-labeled cells. Furthermore, purified 48 kDa sCD14 enhanced the LPS-induced TNF-a and IL-6 release by the monocytic cells suggesting that a cell-surface signal transducer molecule may be involved in signaling. The data suggest a possible novel role for sCD14 in the monocyte response to LPS.     

CD14 Expression and Binding of Lipopolysaccharide to Alveolar Macrophages and Monocytes

We have studied the expression of the lipopolysaccharide (LPS) receptor CD14 on monocytes (Mo) and alveolar macrophages (AM), including density- and size-defined subpopulations. Bronchoalveolar lavage (BAL) was performed on eleven healthy non-smokers and blood sampled from 5 of them, and the levels of cell CD14 expression was investigated using flow cytometry. The influence of LPS stimulation on the CD14 expression of AM was studied at various intervals during prolonged incubation. Further, the relationship between CD14 expression and LPS binding to Mo and subpopulations of AM was studied by measuring fluorescein isothiocyanate (FITC)-LPS binding (flow cytometry) and binding of radioiodinated LPS (^I25I-LPS). The CD14 expression was 13-fold higher (P < 0.02) on Mo than on unfractionated and high density AM. The CD14 level on the latter was higher than on low density AM, and also higher (P < 0.05) on small AM compared to large (flow cytometrically defined) AM. LPS stimulation had a downregulating effect on AM CD14 level, but after several hours of continuing decreased expression, an increased (P < 0.05) CD14 expression was demonstrated, indicating de novo synthesis. The binding of LPS to subpopulations of AM and isolated Mo was not significantly different, but the binding of FITC-LPS to Mo in whole blood was higher than to AM (P < 0.02). The presented results indicate that AM of different size and maturity have different and variable (activation dependent) CD14 levels. The LPS binding capacity was, however, not proportional to the CD14 expression, indicating that LPS binding mechanisms unrelated to CD14 levels were also operable.     

Porphyromonas gingivalis lipopolysaccharides induce maturation of dendritic cells with CD14+CD16+ phenotype

Primary immune responses are initiated by dendritic cells (DC) that inform naive T helper cells about invading pathogens. DC undergo sequential events leading to irreversible maturation upon bacterial stimulation. To investigate the responses of DC during periodontal infection, we studied the effects of LPS from Porphyromonas gingivalis on DC. DC generated from human peripheral monocytes by culture with IL-4 and GM-CSF were incubated with P. gingivalis LPS (Pg LPS) or Escherichia coli LPS (Ec LPS). Flow cytometry and real-time quantitative RT-PCR analysis revealed that Pg LPS, but not Ec LPS, preferentially up-regulated CD14 and CD16 expression at protein and mRNA levels. Furthermore, Pg LPS preferentially induced the secretion of soluble CD14. CD1a, HLA-DR and CD54 were highly expressed on DC stimulated with both kinds of LPS; however, CD40, CD80, CD83 and CD86 expression on Pg LPS-stimulated DC was lower than on Ec LPS-stimulated DC. With regard to IL-6, IL-8, IL-10, IL-12 and RANTES production from DC and allogeneic T cell proliferation, Pg LPS was a weaker stimulator than Ec LPS. These results suggested that Pg LPS triggers maturation of DC with unique characteristics, which exhibited weak immunostimulatory activity and may contribute to induction of chronic inflammation at the site of periodontal infection.