突变MyD88重组质粒的构建及其抑制绿脓杆菌诱导的A549细胞IL-8表达

构建突变MyD88真核表达质粒(MyD88 DN),转染人呼吸道上皮细胞株A549,探讨其对绿脓杆菌及其分泌产物刺激IL-8表达的影响.结果显示突变MyD88成功构建入pcDNA3.1/zeo真核表达质粒,转染A549细胞后,可降低绿脓杆菌培养上清或活菌刺激诱导的IL-8分泌.提示突变MyD88可阻断绿脓杆菌感染引起的呼吸道上皮细胞IL-8释放,为呼吸道炎症的基因治疗提供了新的靶基因.     

结核分支杆菌培养上清诱导呼吸道上皮细胞IL-8表达

目的：观察呼吸道上皮细胞对结核杆菌产物产生的炎症反应，探讨炎症反应信号传递的机制。方法：制备结核分枝杆菌强毒力H37RV株培养上清，用培养上清刺激肺上皮细胞株SPC-A-1和A549，酶联免疫吸附实验检测细胞IL-8表达量。用突变MyD88表达重组质粒转染SPC-A-1细胞，观察MyD88与结核杆菌培养上清诱导上皮细胞炎症反应信号传递的关系。结果：结核分枝杆菌强毒力H37RV株培养上清明显增加SPC-A-1和A549细胞IL-8的表达。用突变MyD88表达重组质粒pcDNA3．1-MyD88转染SPC-A-1。结果显著抑制了结核杆菌培养上清对SPC-A-l细胞的炎症刺激作用。结论：结核杆菌培养上清能够诱导呼吸道上皮细胞IL-8表达，，Toll／IL-1受体信号通路及MyD88分子与细胞炎症反应的信号传递相关，提示在肺结核病发病过程中。结核杆菌的代谢产物可能刺激肺上皮细胞产生炎症细胞因子，参与肺结核炎症病变的形成。     

铜绿假单胞菌活菌对呼吸道上皮细胞表达IL-8的影响

目的:探讨铜绿假单胞菌活菌与人呼吸道上皮细胞的相互关系,细菌对呼吸道上皮炎症反应的影响。方法:采用PAO1及ATCC 27853两株铜绿假单胞菌,在体外与培养的呼吸道上皮细胞株A549及无血清培养的人支气管上皮原代细胞相互作用,收集细胞培养上清,ELISA检测上清IL-8浓度。结果:两株绿脓杆菌均能诱导呼吸道上皮细胞IL-8分泌增加,在细菌刺激下,A549细胞IL-8分泌比对照高出5倍(P<0.05),原代上皮细胞IL-8分泌比对照高出8倍(P<0.05)。结论:铜绿假单胞菌呼吸道感染的过程中,细菌与上皮细胞的直接作用可能是呼吸道炎症反应的重要原因。铜绿假单胞菌刺激上皮细胞炎症的分子机制和信号传导值得进一步探讨。     

LOC152742通过TLR4信号通路和炎症反应调控结核分枝杆菌对Ⅱ型肺泡上皮细胞的感染

目的 探讨长链非编码RNA(lncRNA)LOC152742对结核分枝杆菌感染的人Ⅱ型肺泡上皮细胞炎症反应和Toll样受体4(TLR4)信号通路的影响。方法 在A549细胞中转染LOC152742 siRNA，实验分为对照（Con）组、感染（H37Rv）组、转染对照（H37Rv+si-NC）组和转染（H37Rv+si-LOC152742）组。RT-PCR分析LOC152742表达水平变化，MTT法分析A549细胞增殖率，流式细胞术检测细胞凋亡情况，蛋白免疫印迹（Western blot）法检测活化的半胱氨酸天冬氨酸蛋白酶-3(cleaved caspase-3)、活化的半胱氨酸天冬氨酸蛋白酶-9(cleaved caspase-9)、TLR4、髓样分化因子（MyD88）蛋白表达，ELISA分析细胞上清中白细胞介素-6(IL-6)、白细胞介素-1β(IL-1β)和肿瘤坏死因子-α(TNF-α)的含量。在H37Rv+si-LOC152742组A549细胞中添加TLR4特异性抑制剂TAK242，检测TAK242对炎症反应的影响。结果 与Con组相比，H37Rv组A549细胞凋亡率、LOC15...     

MyD88/PI3-K/NF-κB途径介导脂氧素A4拮抗LPS诱导大鼠内皮细胞的白细胞介素合成

目的研究脂氧素A4（LXA4）对脂多糖（LPS）诱导血管内皮细胞合成白细胞介素（IL）-1β、IL-6、IL-8的影响，并探讨其机制。方法对体外培养大鼠肺微血管内皮细胞（PMVEC），用LXA4孵育，再加入LPS；或单用LPS刺激PMVEC。在孵育后用酶联免疫吸附法（ELISA）检测培养上清中的IL-1β、IL-6、IL-8蛋白表达；用RT-PCR法检测IL-1β、IL-6、IL-8的mRNA表达。应用Western blot法检测磷酸化的磷脂酰肌醇-3-激酶（PI3-K）、髓细胞分化因子88（MyD88）的表达。应用凝胶电泳迁移率试验（EMSA）测定核因子-κB（NF-κB）和活化蛋白-1（AP-1）的DNA结合活性。结果LXA4呈剂量依赖性地抑制LPS诱导的PMVEC的IL-1β、IL-6、IL-8的蛋白合成与mRNA表达，抑制PI-3K的表达，抑制NF-κB和AP-1的DNA结合活性，但不影响LPS诱导的MyD88表达。结论LXA4通过下调PI3-K的表达和NF-κB、AP-1的DNA结合活性，拮抗LPS对PMVEC的IL-1β、IL-6、IL-8合成的诱导作用。     

人参皂苷Rg1通过TLR4/MyD88/NF-κB p65通路调控小鼠急性肾损伤诱导的急性肝损伤的机制研究

目的：探讨人参皂苷Rg1(GRg1)对小鼠急性肾损伤所诱导的急性肝损伤的保护作用及其调控机制。方法：昆明小鼠随机分为假手术（sham）组、模型（model）组、GRg1组和necrostatin-1 (Nec-1)组，每组10只。制备急性肾损伤模型，24 h后收集血液。采用生化试剂盒检测小鼠血清肌酐（SCr）、血尿素氮（BUN）、天冬氨酸转氨酶（AST）、谷氨酸转氨酶（ALT）、丙二醛（MDA）和超氧化物歧化酶（SOD）水平。采用ELISA法检测炎症因子白细胞介素1β(IL-1β)、IL-6、IL-8和肿瘤坏死因子α(TNF-α)的表达。HE染色观察组织病理学改变，采用免疫组织化学和Western blot法检测TLR4、MyD88和NF-κB p65蛋白的表达水平。结果：与假手术组比较，model组小鼠出现明显的肝细胞坏死、肝肾功能减退，血清中SCr、BUN、AST和ALT均显著升高（P<0.01）,MDA含量显著上升，SOD活性显著降低（P<0.01），且血清中炎症因子IL-1β、IL-6、IL-8和TNF-α含量显著升高（P<0.01）,TLR4、MyD88和N...     

SIGIRR对H292细胞Toll样受体4、5、9致炎作用的影响及机制研究

目的 观察SIGIRR(sigh Ig IL-IR-related molecule)对人气道上皮细胞株H292中Toll样受体(TLR)4、5、9致炎作用的影响,并初步了解其作用机制.方法 运用脂质体转染的方法,将SIGIRR-EGFP融和蛋白真核表达载体稳定转染H292细胞,通过免疫细胞化学技术观察H292细胞中SIGIRR的过表达情况;经LPS、Flagellin、CpG DNA 2006处理后,ELISA检测重组质粒(SIGIRR-EGFP)、空质粒(pEGFP-N1)转染以及未转染的H292细胞分泌致炎因子TNF-a和IL-6水平;通过免疫共沉淀的方法了解SIGIRR与MyD88之间的关系.结果 激光共聚焦显微镜显示重组融合蛋白SIGIRR-EGFP与H292内源SIGIRR共定位于细胞膜上;经LPS、Flagellin、CpG DNA 2006刺激后,重组质粒转染的H292细胞分泌的IL-6和TNF-a水平显著低于空质粒转染和未转染的H292细胞(P＜0.01);免疫共沉淀提示H292细胞受到刺激后,SIGIRR与MyD88有较强相互作用,可与TLR4、5、9竞争结合MyD88分子.结论 SIGIRR对H292细胞TLR4、5、9致炎通路的负性调节作用,可能是通过减少MyD88分子与TLR4、5、9的结合,从而削弱了炎症信号的细胞内转导.     

纳米载体组氨酸接枝聚介导的 shRNA 对大鼠肝脏 MyD88基因表达的干扰作用

目的：研究应用纳米载体组氨酸接枝聚（β-氨基酯）（HGPAEs）介导的RNA干扰技术对大鼠肝脏髓样分化因子88（myeloid differentiation factor 88,MyD88）基因表达的抑制作用。方法构建HGPAEs及针对大鼠MyD88基因的shRNA（ small hairpin RNA）质粒,并将二者耦合成pMyD88-HGPAEs载体,分别设置生理盐水组、HGPAEs 组、pHK-HGPAEs 阴性对照组、shRNA 组和pMyD88-HGPAEs干预组,通过门静脉注射方法体内转染大鼠肝脏,分别采用荧光定量PCR技术和蛋白印迹法（ Western blot ）检测转染后的MyD88转录水平及蛋白表达水平。结果成功构建载shRNA质粒的HGPAEs载体,体内转染大鼠肝脏后,shRNA组及pMyD88-HGPAEs干预组MyD88基因表达水平差异具有统计学意义（P＜0．05）。与其他4组相比,pMyD88-HGPAEs干预组MyD88基因的mRNA转录水平及蛋白表达水平显著下降（ P＜0．01）,而生理盐水组、单纯HGPAEs组、pHK-HGPAEs阴性对照组转染后MyD88基因mRNA转录水平及蛋白表达水平差异无统计学意义（ P＞0．05）。结论 HGPAEs是一种较为理想的基因转运载体,应用针对大鼠MyD88基因的载shRNA质粒的HGPAEs载体,经门静脉注射方法转染大鼠肝脏可显著性抑制MyD88基因表达,本实验成果的取得为下一步动物实验提供一定的资料。     

Menin 对 MyD88表达调控的初步研究

目的：探讨 menin 蛋白对髓样分化因子88(myeloid differentiation factor 88, MyD88)基因表达的调控作用。方法在 Men1基因敲除的小鼠 mef (Men1-/- mef)细胞中,转染可以过表达 menin 蛋白的 me-nin-PCI-NEO 质粒,运用 Western 印迹技术检测 menin 对 MyD88蛋白表达的影响。构建包含 MyD88启动子的报告基因质粒,在 Men1-/- mef 细胞中,将 MyD88启动子质粒和 menin-PCI-NEO 质粒或其阴性对照 PCI-NEO 共转染,利用荧光报告基因系统分析 menin 对 MyD88基因启动子活性的影响。结果转染 menin-PCI-NEO 质粒后, menin 蛋白表达升高的同时, MyD88蛋白的表达减少。在荧光报告基因系统中,转染 menin-PCI-NEO 质粒后 MyD88基因启动子活性被抑制。结论 menin 蛋白可以下调 MyD88蛋白的表达,这种作用可能通过抑制 MyD88基因的转录而实现。     

呼吸道上皮细胞与致病菌相互作用--上皮细胞内吞细菌实验研究

目的：呼吸道上皮细胞在防御这类机会致病菌感染时发挥了重要的作用。本研究旨在探讨上皮细胞能否清除胞内的绿脓杆菌，胞内模式识别受体Nods蛋白家族是否参与胞内杀菌，防御素是否能通过促经克雷伯杆菌粘附到上皮细胞而被上皮细胞内在化而清除。方法：首先用绿脓杆菌活菌刺激支气管原代上皮细胞及A549细胞，活菌细胞共孵育两小时后庆大霉素杀死未进入胞内的细菌，继续孵育4小时，24小时后，用TritonX-100溶解细胞，采用平板菌落计数法计数胞内活菌数。绿脓杆菌与细胞按不同比例共孵育两小时后庆大霉素杀死未进入胞内的细菌，继续培养24小时后收集细胞培养上清，酶联免疫吸附法（ELISA）检测IL-8的表达量。为进一步研究Nods蛋白是否在胞内杀菌及活菌在胞内引起IL-8分泌中发挥作用，我们用超声处理的绿脓杆菌菌体成分刺激使细胞膜通透性增加的温和去污剂digitonin处理和未使用digitonin处理A549细胞，ELISA检测细胞IL-8表达水平。胞内模式识别受体Nod1，Nod2可以识别菌体成分，用RT-PCR检测肺上皮细胞Nodl，Nod2的表达。其次，     

Fluticasone and budesonide inhibit cytokine release in human lung epithelial cells and alveolar macrophages

Glucocorticoids are potent anti-inflammatory agents capable of influencing cytokine release in a number of cell types. The aim of the present study was to investigate whether glucocorticoids, frequently used in the treatment of asthma, interfere with cytokine secretion by lung epithelial cells and alveolar macrophages in vitro. Inhalation of swine dust induces airway inflammation with influx of inflammatory cells and release of proinflammatory cytokines in the lungs. Therefore, human lung epithelial cells (A549) and human alveolar macrophages were stimulated with swine dust or lipopolysaccharide (LPS), and the inhibitory effect of budesonide and fluticasone propionate on cytokine release was studied in a dose-response (10(-13)-10(-8) M) manner. The time course for the steroid effect was also investigated. Both steroids caused a dose-dependent, almost total, inhibition of swine dust-induced IL-6 and IL-8 release from epithelial cells and LPS-induced IL-6 and TNF-alpha from alveolar macrophages. The steroids only partially inhibited IL-8 release from alveolar macrophages. Budesonide was approximately 10 times less potent than fluticasone propionate. Preincubation with the steroids did not inhibit cytokine release more than simultaneous incubation with stimulus and steroid. In conclusion, budesonide and fluticasone propionate, in concentrations that probably occur in the airway lining fluid during inhalational therapy, inhibited cytokine release from human lung epithelial cells (IL-6, IL-8) and alveolar macrophages (TNF-alpha, IL-6, IL-8). In vitro, the onset of this effect was rapid.     

The myeloid differentiation factor 88 is dispensable for the development of a delayed host response to Pseudomonas aeruginosa lung infection in mice

Because MyD88 transduces a core set of Toll-like receptor (TLR)-induced signals, microbial-induced host responses can be divided broadly into the MyD88-dependent and MyD88-independent pathways. A specific pathogen induces a distinct pattern of host response dependent upon the signalling pathways employed. Recently, we demonstrated that a MyD88-dependent pathway is essential for the development of early (4-8 h) host response to Pseudomonas aeruginosa lung infection. Here, we show that the development of a delayed (24-48 h) host response to P. aeruginosa is independent of MyD88. Using MyD88-deficient mice, the production of macrophage inflammatory protein 2, tumour necrosis factor and interleukin 1alpha in the airway was observed following P. aeruginosa lung infection for 24 or 48 h. Moreover, the MyD88-deficient mice recruited sufficient neutrophils in the lung and cleared the bacteria efficiently from the lung after 48 h. Thus, the full development of host responses to P. aeruginosa lung infection involves, in a sequential, stepwise fashion, a MyD88-dependent early response and a MyD88-independent delayed mechanism.     

Endotoxin potency in the A549 lung epithelial cell bioassay and the limulus amebocyte lysate assay.

The purpose of this study was to elucidate to what extent the potency of endotoxins measured by the limulus amebocyte lysate (LAL) assay is reflected in the potency in an in vitro assay based on release of interleukin-8 (IL-8) from a lung epithelial cell line, A549. Lipopolysaccharides (LPS) from Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella enteritidis and detoxified LPS from E. coli were applied in serial dilutions in the LAL assay and in the A549 bioassay. Also 19 organic dust samples from waste recycling plants were tested. The A549 cells were incubated for 24 h with LPS or dust, and the IL-8 secretion was determined by ELISA. The method for evaluation of the LAL assay showed linearity for the four endotoxins. Using the slope as a measure of the potency factor (PF), LPS from E. coli and S. enteritidis was about four times more potent than that for LPS from K. pneumoniae and P. aeruginosa. In the A549 bioassay each of the different types of endotoxin had characteristic and very different dose-response curves. The potency of the LPS, in the A549 bioassay, ranked as follows K. pneumoniae > P. aeruginosa > E. coli > or = S. enteritidis. The content of endotoxin in the dust samples did not correlate with their potency in the A549 bioassay. The present study indicates a poor correlation between the potency of endotoxin in the LAL assay compared with the A549 bioassay. The lack of correlation when organic dust samples are tested may reflect the fact that these samples contain biological active compounds, which are non-reactive in the LAL-assay but stimulate IL-8 secretion from epithelial cells.     

MyD88-dependent dendritic and epithelial cell crosstalk orchestrates immune responses to allergens

Sensitization to inhaled allergens is dependent on activation of conventional dendritic cells (cDCs) and on the adaptor molecule, MyD88. However, many cell types in the lung express Myd88, and it is unclear how signaling in these different cell types reprograms cDCs and leads to allergic inflammation of the airway. By combining ATAC-seq with RNA profiling, we found that MyD88 signaling in cDCs maintained open chromatin at select loci even at steady state, allowing genes to be rapidly induced during allergic sensitization. A distinct set of genes related to metabolism was indirectly controlled in cDCs through MyD88 signaling in airway epithelial cells (ECs). In mouse models of asthma, Myd88 expression in ECs was critical for eosinophilic inflammation, whereas Myd88 expression in cDCs was required for Th17 cell differentiation and consequent airway neutrophilia. Thus, both cell-intrinsic and cell-extrinsic MyD88 signaling controls gene expression in cDCs and orchestrates immune responses to inhaled allergens.     

Essential role of transcription factor nuclear factor-kappaB in regulation of interleukin-8 gene expression by nitrite reductase from Pseudomonas aeruginosa in respiratory epithelial cells.

Persistent infection with Pseudomonas aeruginosa increases interleukin-8 (IL-8) levels and causes dense neutrophil infiltrations in the airways of patients with chronic airway diseases. Recently, we have reported that nitrite reductase from P. aeruginosa induces the production of IL-8 in respiratory cells, including bronchial epithelial cells. To determine the molecular mechanism(s) of nitrite reductase-induced IL-8 expression in respiratory cells, A549 epithelial cells were transfected with plasmids containing serial deletions of the 5'-flanking region of the IL-8 gene and then exposed to nitrite reductase. Nitrite reductase significantly enhanced IL-8 gene promoter-driven reporter activity. This increased IL-8 gene expression was inhibited by mutating the nuclear factor-kappaB (NF-kappaB) binding element. Nitrite reductase enhanced nuclear localization of the NF-kappaB binding complex. Furthermore, nitrite reductase induced the degradation of IkappaBalpha, the major cytoplasmic inhibitor of NF-kappaB, and the expression of IkappaBalpha mRNA. These data support the critical role of the activation of NF-kappaB in nitrite reductase-induced IL-8 gene expression in airway epithelium.     

克雷伯杆菌分泌因子及菌体成分在细胞内、外刺激肺上皮细胞分泌IL-8的研究

目的:通过比较肺炎克雷伯杆菌(Klebsiellapneumoniae,Kp)分泌因子及菌体成分对经过digitonin处理和未处理的肺上皮细胞株IL8分泌的影响,进一步了解克雷伯杆菌诱导肺上皮细胞炎症反应的信号转导机制。方法:实验分为两组,一组使用能使细胞膜通透性增加的温和去污剂digitonin处理,而另一组不处理。分别用Kp03183的细菌培养上清和超声处理的菌体成分刺激肺上皮细胞株A549,酶联免疫吸附实验(ELISA)检测细胞IL8表达水平。并用RT-PCR的方法检测肺上皮细胞胞内模式识别受体NOD1的表达。结果:Kp培养上清对未经digitonin处理的细胞IL8分泌无明显增强作用,与对照相比差异无显著意义(p>0.05),菌体成分能刺激IL8分泌增加(P<0.01),但增高不超过一倍。经digitonin处理使细胞膜通透性增加后,Kp培养上清及菌体成分刺激细胞IL8的作用都增强,菌体成分刺激IL8效果更为显著,为对照的3倍,而培养上清作用相对较弱。RT-PCR检测结果表明,肺上皮细胞表达胞内模式识别受体NOD1。结论:菌体成分是诱导炎症反应更有效的刺激物,肺炎克雷柏杆菌侵入肺上皮细胞可能是引发细胞炎症反应的始动环节。肺上皮细胞表达胞内模式识别受体NOD1,它是否参与肺上皮细胞识别肺炎克雷伯杆菌菌体成分,值得进一步的研究。     

Epithelial-specific blockade of MyD88-dependent pathway causes spontaneous small intestinal inflammation

Accumulating evidence suggests a role for Toll-like receptor (TLR) signaling at the intestinal epithelial cells (IECs) level for intestinal protection against exogenous injury or pathogenic infection. We hypothesized that MyD88 dependent TLR signaling at intestinal epithelium is critical for mucosal immune homeostasis. In the current study, a transgenic mouse model was generated in which a dominant-negative mutant of MyD88 (dnMyD88) was driven by an intestinal epithelial-specific murine villin promoter. Aged transgenic mice spontaneously developed chronic small intestinal inflammation, as revealed by increased CD4+ and CD8+ lymphocytes, neutrophil and macrophage infiltration, increased production of cytokines as TNF-α, IFN-γ, IL-1β, and IL-17, crypt abscesses, lymphedema, and Goblet cell depletion. The chronic inflammation was not due to increased epithelial apoptosis or permeability, but to a decreased Paneth cell-derived α-defensins (cryptdins) and RegIII-γ and increased commensal bacteria translocation. Thus, epithelial MyD88-dependent pathway plays an essential role in limiting mucosal microflora penetration and preventing mucosal immunoregulation disturbance in vivo.