阳离子多肽MP-1拮抗内毒素/脂多糖活性的实验研究

目的　探讨阳离子多肽MP -1对内毒素/脂多糖(LPS)攻击小鼠的作用及机制。方法将30只昆明小鼠随机分为MP- 1组(尾静脉注射3mg/kgMP- 1)、致伤组(尾静脉注射20mg/kgLPS)、保护组(先注射20mg/kgLPS, 20s内再注射3mg/kgMP- 1),每组10只。观察3组小鼠注射后3d内的存活情况。应用生物传感器及FASTfit作图,比较MP- 1、多黏菌素(PMB)与LPS的亲和力,以Kd值表示。通过动态比浊法和鲎试验定量,比较5、10、20、40μmol/LMP -1、PMB对2μg/LLPS的中和作用,以LPS中和0μmol/LMP -1、PMB为对照。采用逆转录聚合酶链反应法,观察MP- 1对LPS刺激的10只昆明小鼠腹腔巨噬细胞(PM)Toll样受体4(TLR4)mRNA、肿瘤坏死因子(TNF)αmRNA、白细胞介素(IL)6mRNA表达的影响。　结果　致伤组小鼠注射LPS后48h全部死亡。保护组小鼠精神状态一度萎靡但恢复较快,食欲、活动度在短时间内改善,存活率为90%。MP- 1组小鼠存活率为100%。MP -1对LPS具有高亲和力(Kd值为484. 0nmol/L)但弱于对LPS有极高亲和力的PMB(Kd值为18.9nmol/L). MP- 1具有中和LPS的能力但弱于PMB; 20、40μmol/LMP -1中和LPS的能力明显高于0μmol/LMP- 1(P<0. 01).MP- 1对LPS刺激的小鼠PM-TLR4mRNA、TNF- αmRNA和IL -6mRNA的表达均有显著的抑制作用。　结论　MP -1对L     

右美托咪啶对脂多糖诱导大鼠外周血单核细胞Toll样受体4mRNA表达的影响

目的 探讨右美托咪啶对脂多糖(LPS)诱导大鼠外周血单核细胞Toll样受体4(TLR4)mRNA表达的影响.方法 健康雄性Wistar大鼠40只,取外周血分离培养单核细胞,采用随机数字表法,将其随机分为5组(n=8),A组:阴性对照;B组:单核细胞中加入LPS(终浓度为1μg/ml);C组:单核细胞中加入LPS(终浓度为1μg/ml)+右美托咪啶(终浓度为0.5 ng/ml);D组:单核细胞中加入LPS(终浓度为1μg/ml)+右美托咪啶(终浓度为5.0 ng/ml);E组:单核细胞中加入LPS(终浓度为1μg/ml)+右美托咪啶(终浓度为50.0 ng/ml).孵育24 h后,收集上清液,采用ELISA法测定TNF-α、IL-1β和IL-6的浓度,采用RT-PCR法测定TLR4 mRNA的表达.结果 与A组比较,B组TNF-α、IL-1p、IL-6的浓度升高,TLR4 mRNA表达上调(P＜0.01);与B组比较,C组、D组和E组TNF-α、IL-1β、IL-6的浓度降低,TLR4 mRNA表达下调(P＜0.05或0.01);与C组比较,D组和E组TNF-α、IL-1β、IL-6的浓度降低(P＜0.01),TLR4 mRNA表达差异无统计学意义(P＞0.05);D组和E组各指标比较差异无统计学意义(P＞0.05).结论 右美托咪啶可通过下调TLR4 mRNA表达,抑制TLR4的合成,从而抑制LPS诱导大鼠外周血单核细胞TNF-α、IL-1β和IL-6的生成与释放.

Abstract：

Objective To investigate the effects of different concentrations of dexmedetomidine on the expression of Toll-like receptor 4 (TLR4) mRNA in rat peripheral blood monocytes exposed to lipopolysaccharide ( LPS ). Methods Peripheral blood monocytes isolated from male Wistar rats were seeded in 24-well plate in RPMI 1640 liquid culture medium in CO2 incubator at 37 ℃ and 5% CO2 for 2 h, and were randomly divided into 5 groups ( n = 8 each): group A negative control; group B was exposed to LPS 1 μg/ml and C, D and E groups were exposed to LPS 1 μg/ml + dexmetomidine 0.5, 5.0 and 50.0 ng/ml respectively. The monocytes were then incubated for 24 h. The concentrations of TNF-α, IL-1β and IL-6 in the supernatant of the cultured monocytes were detected by ELISA. The expression of TLR4 mRNA in the monocytes was detected by RT-PCR.Results Exposure to LPS significantly increased the expression of TLR4 mRNA and the concentrations of TNF-α, IL-1β and IL -6 in group B as compared with group A ( P ＜ 0.01 ). Dexmedetomidine attenuated the LPS-induced increase in the expression of TLR 4 mRNA and the concentrations of TNF-α, IL-1β and IL-6 in a dose-dependent manner ( P ＜0.05or 0.01 ). Conclusion Dexmedetomidine can inhibit the synthesis of TLR4 and inhibit the secretion and dilivery of TNF-α, IL-1β and IL-6 by down-regulating the gene expression of TLR4 in rat peripheral blood monocytes exposed to LPS.     

信号转导及转录激活子1和3抑制剂对高迁移率族蛋白B1诱导鼠巨噬细胞合成肿瘤坏死因子α的影响

目的探讨信号转导及转录激活子1(STAT1)和3抑制剂对高迁移率族蛋白B1(HMGB1)诱导巨噬细胞合成肿瘤坏死因子α(TNFα)的影响。方法取正常Wistar大鼠腹腔巨噬细胞置24孔培养板中(1×106细胞/孔),培养3d后以HMGB1刺激,采用氟达拉滨(Fludarabine,STAT1特异性抑制剂)及雷帕霉素(Rapamycin,STAT3特异性抑制剂)进行干预。观察HMGB1刺激与肿瘤坏死因子αmRNA表达和蛋白释放的时效、量效关系,Fludarabine和Rapamycin处理对TNFαmRNA表达和蛋白释放的影响。结果(1)HMGB1可导致大鼠腹腔巨噬细胞TNFα基因表达明显升高,于攻击后24h达峰值,至36h减弱。HMGB1的用量为10μg/ml时,TNFα基因表达明显增强;(2)HMGB1可诱导大鼠腹腔巨噬细胞TNFα蛋白早期释放,4h即可达到高峰,8h后减弱。随着HMGB1刺激剂量从5μg/ml增大到25μg/ml,TNFα蛋白释放持续增强;(3)Fludarabine和Rapamycin可抑制大鼠腹腔巨噬细胞TNFα基因表达,但不能影响TNFα蛋白的释放。结论STAT1和STAT3抑制剂可显著下调巨噬细胞由HMGB1诱导的TNFα基因表达,但不能影响其早期(<24h)蛋白释放。     

内毒素结合肽及其突变体的表达纯化和抗内毒素/脂多糖活性研究

目的使内毒素结合肽（EBP）及其突变体mEBP在E．coli DH5α中表达，纯化后鉴定其抗内毒素／脂多糖（LPS）活性。方法（1）将含Pinpoint Xa3-EBP及其突变体Pinpoint Xa3-mEBP的工程菌DHSα活化，加入异丙硫半乳糖苷（IPTG）诱导其表达生物素融合蛋白。分离纯化表达产物，因子Xa酶切融合蛋白分离目的肽EBP和mEBP。采用亲和层析及反相高效液相色谱法纯化目的肽，用氨基末端10个氨基酸残基序列分析法鉴定突变体mEBP。（2）分离正常人外周血单核细胞（PBMC），用5mg／L异硫氰酸荧光素（FITC）-LPS＋不同浓度EBP或mEBP（均为2．0、5．0、12、5mg／L）刺激PBMC，检测其平均荧光强度。用1mg／L LPS＋3种浓度（同前）EBP或mEBP刺激PBMC，5h后取上清液，检测肿瘤坏死因子（TNF）α和白细胞介素（IL）6浓度。（3）将25只昆明小鼠分为正常对照组（5只）：腹腔注射等渗盐水0.2ml；模型组（5只）：小鼠造成20％TBSAHI度烧伤，伤后腹腔注射LPS（1mg／kg）；治疗组（15只）：小鼠同前致伤后，腹腔注射多黏菌素B（PMB，5mg／kg）或EBP或mEBP（后两者均为10mg／kg）。6h后检测各组小鼠血清TNF—α、IL-6浓度及肝组织中TNF—α mRNA的表达水平。结果（1）纯化后的目的肽EBP、mEBP纯度均达98％以上，mEBP氨基末端10个氨基酸残基序列分析符合预期结果。（2）随着mEBP或EBP浓度的增加，PBMC表面的平均荧光强度逐渐减弱；且在同一浓度下，加入mEBP后平均荧光强度的减弱程度较加入EBP明显。与用1mg／LLPS刺激PBMC比较，加入1mg／L LPS＋12．5mg／LEBP以及1mg／LLPS＋3种浓度mEBP刺激后，PBMC培养上清液中IL-6及TNF—α的水平均明显降低（P〈0．01）。（3）与模型组比较，治疗组小鼠血清IL-6、TNF-α水平均明显降低（P〈0．01），其中10mg／kg mEBP治疗组两指标低于等浓度EBP治疗组（P〈0．05）。（4）小鼠肝组织TNF—α mRNA表达水平：正常对照组相对灰度值为0．25，模型组为0．93，10mg／kg mEBP治疗组为0．51，10mg／kg EBP治疗组为0．77，5mg／kg PMB治疗组为0．43。结论具有抗LPS活性的小分子肽可通过原核表达获得：EBP及mEBP均具有抗LPS活性，其中mEBP拮抗作用更强。     

In vitro effect of danazol on the cytokine production of peritoneal macrophages in patients with endometriosis

Recent evidence suggested that immunologic mechanisms might play a role in thepathogenesis of endo..t.io.is[1]. Women withendometriosis have an increased number andactivity of macrophages in peritoneal fluid(PF) and secretion of cytokines such as tumornecrosis factor (TNF ) and interleukin 6 (IL--6)by these cells.. In addition, autoantibodiessuch as antiendometrial antibody are often detected in peripherial blood samples obtainedfrom patients with endometriosis. Danazol, adrug commonly used…     

Ghrelin down-regulates proinflammatory cytokines in sepsis through activation of the vagus nerve

OBJECTIVE: To test the hypothesis that administration of ghrelin attenuates inflammatory responses in sepsis through vagal nerve stimulation. SUMMARY BACKGROUND DATA: Ghrelin has been demonstrated to possess multiple functions, including stimulation of the vagus nerve. Our recent study has shown that plasma levels of ghrelin were significantly reduced in sepsis; and ghrelin administration improved organ perfusion and function. However, it remained unknown whether ghrelin also decreases proinflammatory cytokines in sepsis and, if so, whether the down-regulatory effect of ghrelin is mediated by activation of the vagus nerve. METHODS: Male rats were subjected to sepsis by cecal ligation and puncture (CLP). At 5 hours after CLP, a bolus intravenous injection of 2 nmol ghrelin was followed by a continuous infusion of 12 nmol ghrelin via a primed 200-microL Alzet mini-pump for 15 hours. At 20 hours after CLP, plasma and peritoneal fluid levels of TNF-alpha and IL-6 were determined. The direct effect of ghrelin on cytokine production was studied using cultured normal rat Kupffer cells or peritoneal macrophages stimulated by lipopolysaccharide (LPS). In additional animals, vagotomy or sham vagotomy was performed in sham and septic animals immediately prior to ghrelin administration and cytokine levels were then measured. RESULTS: Ghrelin significantly reduced TNF-alpha and IL-6 levels in sepsis. In contrast, ghrelin did not inhibit TNF-alpha and IL-6 release from LPS-stimulated Kupffer cells or peritoneal macrophages. However, vagotomy, but not sham vagotomy, prevented ghrelin's down-regulatory effect on TNF-alpha and IL-6 production. CONCLUSIONS: Ghrelin down-regulates proinflammatory cytokines in sepsis through activation of the vagus nerve. Pharmacologic stimulation of the vagus nerve may offer a novel approach of anti-sepsis therapy.     

PPARγ激动剂对腹膜透析相关性急性腹膜炎大鼠PPARγ、Toll样受体4表达及STAT1信号活化的影响

目的 观察过氧化物酶体增殖物活化受体γ(PPARγ)激动剂罗格列酮和15脱氧前列腺素J2（15d-PGJ2）对脂多糖（LPS）诱导大鼠腹膜透析相关性急性腹膜炎模型腹膜组织PPARγ、Toll样受体4（TLR4）表达、STAT1活化及腹腔局部炎性反应的影响。 方法 24只雄性SD大鼠随机分成4组，每组6只。对照组：腹腔注入4.25%葡萄糖乳酸盐腹膜透析液（简称腹透液，90 ml/kg）；LPS组：LPS 1 mg/kg腹腔注入4 h后，再注入腹透液；罗格列酮+ LPS组（罗格列酮组）：罗格列酮20 mg&#8226;kg-1&#8226;d-1灌胃预处理3 d，注入LPS及腹透液；15d-PGJ2 + LPS组（15d-PGJ2组）：15d-PGJ2 0.3 mg&#8226;kg-1&#8226;d-1腹腔注入预处理3 d，注入LPS及腹透液。注入腹透液4 h后处死大鼠，留取腹水、壁层及脏层腹膜组织。ELISA法检测腹水中IL-6浓度。常规行腹膜组织Masson染色和腹水白细胞计数。RT-PCR检测腹膜组织PPARγ、TLR4 mRNA的表达；Western印迹法检测腹膜组织PPARγ、TLR4、磷酸化（p）-STAT1、STAT1蛋白的表达。 结果 LPS组大鼠腹水IL-6浓度[268.53（201.87～335.19） ng/L]高于对照组[147.62（130.60～164.64） ng/L）]（P < 0.01）；罗格列酮组大鼠腹水IL-6浓度[110.20（77.60～142.80） ng/L]低于LPS组（P < 0.05）。与对照组比较，LPS组大鼠腹膜组织明显水肿，腹膜组织PPARγ、TLR4 mRNA及蛋白表达均显著增强（P < 0.05）。与LPS组相比，罗格列酮组大鼠腹膜组织水肿明显减轻，PPARγ、TLR4 mRNA表达显著增高（P < 0.05），但其蛋白表达显著减弱（P < 0.05）。15d-PGJ2组大鼠腹膜组织水肿明显减轻，PPARγ mRNA及其蛋白表达均显著减弱（均P < 0.05），TLR4 mRNA表达显著增强（P < 0.01），但其蛋白表达减弱（P < 0.05）。各组间腹水白细胞计数差异无统计学意义。罗格列酮、15d-PGJ2均明显上调LPS诱导的p-STAT1表达（P < 0.01）。 结论 罗格列酮和15d-PGJ2可负性调节LPS诱导的大鼠急性腹膜炎性反应，并对LPS信号通路中相关功能蛋白起一定的调控作用。     

鲎抗内毒素因子模拟肽REMP2体外中和内毒素及抗菌活性的研究

目的 了解鲎抗内毒素因子模拟肽REMP2体外中和内毒素及抗菌活性的作用. 方法以多黏菌素B(PMB)为阳性对照,将REMP2、PMB与内毒素/脂多糖(LPS)溶液混合,使REMP2、PMB反应终浓度分别为100.00、10.00、1.00、0.10、0.01μmol/L,LPS为1 EU/mL.测定各溶液中LPS浓度,计算其中和率;以等渗盐水(NS)作为对照,分别将REMP2及PMB配制成10、20、40、80 μmol/L溶液,LPS配制成100μg/L,分别作用于LPS刺激的小鼠单核巨噬细胞,采用酶联免疫吸附测定法检测其肿瘤坏死因子α(TNF-α)含量;将REMP2加入大肠杆菌标准菌株菌液中,终浓度为40μmol/L,于加入后10、20、40 min在透射电镜下观察大肠杆菌的形态学变化. 结果浓度为0.10、10.00、100.00μmol/L的REMP2对LPS的中和率与阳性对照的PMB值相近(P>0.05);浓度为10、20、40、80μmol/L的REMP2作用于细胞后,其TNF-α含量[(1175-4-162)、(859-4-122)、(645±142)、(489±102)ng/L]均低于对照组[(3463±218)ng/L,P<0.01].REMP2作用后透射电镜下大肠杆菌内外膜变模糊、毛糙,菌体肿胀,胞质空泡变性. 结论 REMP2具有良好的中和LPs活性及杀菌作用.     

白鲜皮提取物拮抗内毒素/脂多糖的实验观察

目的 了解白鲜皮提取物2（DPR-2）对内毒素／脂多糖（LPS）的体外拮抗活性。方法 采用动态比浊法鲎试验定量检测DPR-2对LPS（0．1μg／L）的中和作用，激光共聚焦扫描显微镜观察不同浓度DPR-2（0、8、0、16．0、32．0、64．0mg／L）对异硫氰酸荧光素-LPS（FITC-LPS，100．0μg／L）与小鼠单核细胞株RAW264、7结合力的影响，用荧光定量反转录．聚合酶链反应（RT-PCR）法检测以上浓度DPR-2对LPS（100．0μg／L）刺激的RAW264．7细胞肿瘤坏死因子α（TNF-α）和白细胞介素6（IL-6）mRNA表达的影响。结果 DPR-2对LPS具有一定的中和作用（P〈0．05或P〈0．01）；浓度为32．0、64．0mg／L时可显著抑制FITC-LPS与RAW264．7细胞结合（P〈0.01）；对LPS刺激的小鼠RAW264．7细胞TNF-α和IL-6mRNA的表达有抑制作用，该作用具有一定的剂量-效应关系。结论 DPR-2可通过中和LPS的作用阻断与RAW264．7细胞膜受体结合，从而抑制LPS介导的细胞活化。     

Glycine attenuates endotoxin-induced liver injury by downregulating TLR4 signaling in Kupffer cells

BACKGROUND: Several experimental studies have observed better outcomes after glycine treatment in patients with endotoxin-induced liver injuries, but its molecular mechanism is not yet fully understood. The purpose of this study was to evaluate the hypothesis that glycine attenuates endotoxin-induced liver injury by affecting endotoxin signal transduction in liver macrophages. METHODS: An animal model of endotoxin-induced liver injury was established by intraperitoneally injecting mice with 10 mg/kg body weight endotoxin fed a pretreatment diet with or without 5% (w/w) glycine. Blood and liver samples were obtained for analysis of liver morphology and to determine concentrations of alanine aminotransferase, endotoxin receptor Toll-like receptor 4 (TLR4), tumor necrosis factor-alpha (TNF-alpha), and interleukin (IL)-10 at various time points after injection. To investigate the effect of glycine on liver macrophages, Kupffer cells (KCs) were isolated and challenged by LPS (100 ng/mL), with or without glycine (4 mmol/l) pretreatment, and the expressions of TLR4, IL-10, and TNF-alpha were assayed at mRNA and protein levels. DNA-binding activity of nuclear factor-kappa B (NF-kappaB) was also analyzed using enzyme-linked immunosorbent assay. RESULTS: Dietary glycine significantly improved the survival rate of endotoxemic mice (P < .05), whereas serum alanine aminotransferase and TNF-alpha levels were significantly decreased at different time points (P < .05); IL-10 levels were increased (P < .05). Concurrently, LPS-induced hepatic tissue injury was attenuated as indicated by morphologic analysis; secretion of IL-10 in liver tissue (P < .05) was enhanced; and expression of TLR4 and TNF-alpha in liver tissue was downregulated (P < .05). Consistent with these in vivo experiments, enhanced secretion of IL-10 and inhibited expression of TLR4 and TNF-alpha caused by glycine pretreatment were also observed in LPS-stimulated KCs. NF-kappaB DNA-binding activity was also significantly inhibited by glycine (P < .05, respectively). CONCLUSIONS: Dietary glycine improved survival rates and liver function in endotoxemic mice by regulating the production of proinflammatory or anti-inflammatory cytokines in liver. It attenuated liver injury by deactivating KCs through inhibiting TNF-alpha secretion and increasing IL-10 production. The downregulative effect of glycine on the endotoxin signaling pathway and TLR4/NF-kappaB/TNF-alpha may be a novel potential mechanism by which glycine inhibits KC activity.     

Inhibition of cyclic-3',5'-nucleotide phosphodiesterase abrogates the synergism of hypoxia with lipopolysaccharide in the induction of macrophage TNF-alpha production.

BACKGROUND: Local tumor necrosis factor (TNF)-alpha production by resident macrophages (M phi) contributes to posttraumatic tissue injury. Hypoxia decreases cellular cyclic adenosine monophosphate (cAMP) levels and enhances M phi secretion of TNF-alpha following lipopolysaccharide (LPS) stimulation. Thus, tissue hypoxia associated with trauma likely synergizes with proinflammatory mediators in the induction of M phi TNF-alpha production through an influence on cAMP generation or degradation. It is unclear whether elevation of cellular cAMP inhibits LPS-stimulated TNF-alpha production by hypoxic M phi. Moreover, it is unknown whether the synergism of hypoxia with LPS can be abrogated by promotion of cAMP generation or inhibition of cAMP degradation. METHODS: Rat peritoneal M phi were stimulated with Escherichia coli LPS (20 ng/ml) in a normoxic (room air with 5% CO(2)) or hypoxic (95% N(2) with 5% CO(2)) condition. TNF-alpha levels in cell-free supernatants were measured by enzyme-linked immunoassay. The beta-adrenoceptor agonist isoproterenol (ISP; 5.0 microM) and the adenylate cyclase activator forskolin (FSK; 50 microM) were applied to promote cAMP generation. The nonselective cyclic-3',5'-nucleotide phosphodiesterase (PDE) inhibitor 3-isobutyl-1-methylxanthine (IBMX; 1.0 mM) and the PDE III-specific inhibitor milrinone (200 microM) were used to inhibit cAMP degradation. The nondegradable cAMP analogue dibutyryl cAMP (dbcAMP; 100 microM) was applied to further determine the role of PDE. RESULTS. Although hypoxia alone had a minimal effect on TNF-alpha production, it dramatically enhanced LPS-stimulated TNF-alpha production (4.08 +/- 0.28 ng/10(6) cells in hypoxia plus LPS vs 1.63 +/- 0.26 ng/10(6) cells in LPS, 2.5-fold, P < 0.01). Promotion of cAMP generation by either ISP or FSK reduced TNF-alpha production by hypoxic cells. However, neither of these two agents abolished the synergism of hypoxia with LPS (1.68 +/- 0.13 ng/10(6) cells in ISP plus hypoxia plus LPS vs 0.55 +/- 0.04 ng/10(6) cells in ISP plus LPS, threefold; 1.17 +/- 0.03 ng/10(6) cells in FSK plus hypoxia plus LPS vs 0.33 +/- 0.02 ng/10(6) cells in FSK plus LPS, 3.5-fold; both P < 0.01). Inhibition of cAMP degradation with IBMX reduced TNF-alpha production in hypoxic cells and abrogated the synergism (0.31 +/- 0.11 ng/10(6) cells in IBMX plus hypoxia plus LPS vs 0.27 +/- 0.04 ng/10(6) cells in IBMX plus LPS, P > 0.05), and the PDE III inhibitor milrinone had a comparable effect. Moreover, dbcAMP also attenuated TNF-alpha production with abrogation of the synergistic effect of hypoxia (0.56 +/- 0.08 ng/10(6) cells in dbcAMP plus hypoxia plus LPS vs 0.46 +/- 0.04 ng/10(6) cells in dbcAMP plus LPS, P > 0.05). CONCLUSIONS: The results show that elevation of cellular cAMP, either by promotion of generation or by inhibition of degradation, suppresses LPS-stimulated TNF-alpha production in hypoxic M phi. It appears that hypoxia synergizes with LPS in the induction of M phi TNF-alpha production through PDE-mediated cAMP degradation. Inhibition of PDE may be a therapeutic approach for suppression of synergistic induction of M phi TNF-alpha production by hypoxia and LPS in posttraumatic tissue.     

Interleukin 1-alpha and tumor necrosis factor-alpha induce oxygen radical production in mesangial cells

Adherent human mesangial cells (HMC) were unable to phagocytose serum-treated zymosan (STZ), nevertheless this stimulus (1 mg/ml) induced a marked immediate increase of H2O2 and O2- release at a rate of 3.15 +/- 0.35 and 3.40 +/- 0.12 nmol/10(6) HMC/hr, respectively. Zymosan alone resulted in no release of either H2O2 or O2-. Phorbol myristate acetate (PMA, 2 X 10(-6) M) had only marginal effects on HMC leading to the generation of 0.273 +/- 0.014 nmol O2-/10(6) HMC/hr. After a lag period, human recombinant tumor necrosis factor-alpha (TNF-alpha) and human recombinant interleukin 1-alpha IL-1 alpha) both induced significant O2- production measured as SOD inhibitable reduction of cytochrome c, 5 X 10(-5) M, by adherent HMC for up to five hours, the maximum rates being 3.04 +/- 0.08 and 3.2 +/- 0.08 nmol/10(6) HMC/hr for IL-1 alpha and TNF-alpha, respectively. Significant O2- release was detectable at 0.625 ng/ml (37 pM) IL-1 alpha or 1 ng/ml (59 pM) TNF-alpha (P less than 0.05). Catalase inhibitable H2O2 production was also induced by IL-1 alpha and TNF-alpha in a dose dependent manner. Using scopoletin (40 nM) and 1 microM peroxidase we fluorimetrically measured 1.73 +/- 0.14 and 1.49 +/- 0.19 nmol H2O2/10(6) HMC/hr induced by IL-1 alpha (25 ng/ml) and TNF-alpha (20 ng/ml). Finally, we ascertained the type of radical species produced by HMC stimulated by cytokines employing ESR-spin-trapping with DMPO.2+ These results demonstrated that O2- was the primary radical species formed.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cytokine modulation in experimental endotoxemia: characterization of an ex vivo whole blood model

A new model was developed to study cytokine regulation and modulation in whole blood ex vivo. The model is characterized by stable leukocyte counts and high leukocyte viability throughout the experimental period. Oxygen consumption per time decreased slowly, whereas carbon dioxide partial pressure increased accordingly throughout the experiment. In this model, the anti-inflammatory effects of recombinant human (rh) interleukin (IL)-4, rhIL-10 and rhIL-13 on lipopolysaccharide (LPS) stimulated (10 ng/ml) leukocytes were examined and compared by measuring their ability to inhibit the release and mRNA levels of tumor necrosis factor (TNF)alpha, IL-6 and IL-1beta. rhIL-10 potently inhibited the release of TNF-alpha, IL-6 and IL-1beta in a potent and dose-dependent manner, but did not influence the mRNA levels of these cytokines in CD14-positive cells. Also, rhIL-4 and rhIL-13 inhibited the release of IL-6 and IL-1beta in a potent and dose-dependent manner, however, stronger maximal inhibition of IL-1beta (85%) than of IL-6 (60%) was obtained. In contrast, rhIL-4 and rhIL-13 seemed to have both stimulatory and inhibitory effects on plasma values of TNF-alpha. The effects of 10 ng/ml LPS showed to be signalling through the CD14 receptor, since blood treated with a monoclonal anti-CD14 antibody did not produce any TNF-alpha. The whole blood model described in this study is in our opinion a useful tool for investigating immunomodulating effects on a mixed white blood cell population.     

'Endotoxin tolerance': TNF-alpha hyper-reactivity and tubular cytoresistance in a renal cholesterol loading state

The term 'endotoxin tolerance' defines a state in which prior endotoxin (lipopolysaccharide (LPS)) exposure induces resistance to subsequent LPS attack. However, its characteristics within kidney have not been well defined. Hence, this study tested the impact of LPS 'preconditioning' (LPS-PC; 18 or 72 h earlier) on: (i) selected renal inflammatory mediators (tumor necrosis factor (TNF)-alpha, interleukin-10 (IL-10), monocyte chemotactic protein-1 (MCP-1), inducible nitric oxide synthase (iNOS), Toll-like receptor 4 (TLR4); protein or mRNA); (ii) cholesterol homeostasis (a stress reactant); and (iii) isolated proximal tubule (PT) vulnerability to hypoxia or membrane cholesterol (cholesterol oxidase/esterase) attack. Two hours post LPS injection, LPS-PC mice manifested reduced plasma TNF-alpha levels, consistent with systemic LPS tolerance. However, in kidney, paradoxical TNF-alpha hyper-reactivity (protein/mRNA) to LPS existed, despite normal TLR4 protein levels. PT TNF-alpha levels paralleled renal cortical results, implying that PTs were involved. LPS-PC also induced: (i) renal cortical iNOS, IL-10 (but not MCP-1) mRNA hyper-reactivity; (ii), PT cholesterol loading, and (iii) cytoresistance to hypoxia and plasma membrane cholesterol attack. A link between cholesterol homeostasis and cell LPS responsiveness was suggested by observations that cholesterol reductions in HK-2 cells (methylcyclodextrin), or reductions in HK-2 membrane fluidity (A2C), blunted LPS-mediated TNF-alpha/MCP-1 mRNA increases. In sum: (i) systemic LPS tolerance can be associated with renal hyper-responsiveness of selected components within the LPS signaling cascade (e.g., TNF-alpha, iNOS, IL-10); (ii) PT cytoresistance against hypoxic/membrane injury coexists; and (iii) LPS-induced renal/PT cholesterol accumulation may mechanistically contribute to each of these results.     

Endotoxin-induced chemokine expression in murine peritoneal mesothelial cells: the role of toll-like receptor 4

Acute peritonitis, in which peritoneal mesothelial cells are directly exposed to bacterial components, is a major cause of peritoneal dysfunction in continuous ambulatory peritoneal dialysis patients. We have previously shown that Toll-like receptors (TLR) are expressed in kidney cells, and LPS induces TLR4-dependent chemokine production in tubular epithelial cells. The present work was designed to investigate the involvement of TLR, especially TLR4, in the lipid A-mediated chemokine production by murine peritoneal mesothelial cells (MPMC). A primary cell culture of MPMC from C3H/HeN mice (wild-type mice; LPS sensitive) and from C3H/HeJ mice (containing a point mutation of TLR4; LPS hyposensitive) was established. The expression profile of the TLR family and their accessory molecules, CD14 and MD-2, which are requisite for the LPS signaling pathway, was examined by RT-PCR, Northern blot test, and immunohistochemical staining. Synthetic lipid A-mediated chemokine production by MPMC was studied. The involvement of MAP kinase family (ERK, JNK, and p38 mitogen-activated protein kinase) and nuclear factor (NF)-kappaB in these processes was also studied. MPMC constitutively express TLR4, CD14, and MD-2. A prominent induction of monocyte chemotactic protein-1 (MCP-1) and macrophage inflammatory protein (MIP)-2 by MPMC was detected after lipid A stimulation and was strictly dependent on TLR4. Furthermore, TLR4-dependent chemokine production followed by leukocyte influx into the peritoneal cavity was also confirmed in vivo after stimulation with LPS. mRNA expression of MCP-1 was abolished by NF-kappaB inhibition, but were not affected by the inhibition of ERK, JNK, or p38. As compared with MCP-1, MIP-2 mRNA expression was inhibited by a high dose of curcumin but not by NF-kappaB decoy oligodeoxynucleotide and individual inhibitions of MAP kinase, suggesting that the additional signaling pathway with NF-kappaB might be involved in mRNA expression of MIP-2. These show that TLR4 is directly involved in the production of MCP-1 and MIP-2 by MPMC in a NF-kappaB-dependent manner, but the process does not require any MAP kinase activation. The results provide a candidate molecular target in prevention of it.     

Expression and regulation of Toll-like receptors in lupus-like immune complex glomerulonephritis of MRL-Fas(lpr) mice.

BACKGROUND: How microbial infections exacerbate immune complex glomerulonephritis remains speculative. Toll-like receptors (TLRs) may be involved in this phenomenon, because TLRs have potent immunostimulatory functions when exposed to selected pathogen-associated molecules. METHODS: We addressed this issue by characterizing the expression of TLR1-9 in MRLlpr/lpr mice that spontaneously develop immune complex glomerulonephritis as part of a systemic lupus-like autoimmune syndrome. RESULTS: Five-week-old healthy MRLlpr/lpr mice expressed TLR3 mRNA in kidneys at comparable levels as in the spleen, while all other TLRs were expressed at low levels in the kidney. In 20-week-old nephritic MRLlpr/lpr mice, renal mRNA levels had increased for TLR1-9. Renal TLR mRNA originated at least in part from glomeruli as evidenced by real-time RT-PCR from laser capture microdissected glomeruli. Immunostaining for TLR3, TLR7 and TLR9 revealed their expression by F4/80-positive infiltrating macrophages in 20-week-old nephritic MRLlpr/lpr mice. In addition, TLR3 localized to glomerular mesangial cells. Cultured mesangial cells expressed TLR1-4 and TLR6, while murine macrophages expressed TLR1-9. TNF-alpha and IFN-gamma induced TLR2, TLR3 and TLR6 mRNA in mesangial cells, while they down-regulated TLR1-9 mRNA in macrophages. Stimulation of both cell types with ligands for TLR1-4, TLR5, TLR7 and TLR9 induced IL-6 production consistent with their respective TLR expression patterns. TNF-alpha and IFN-gamma enhanced ligand-induced IL-6 production in both cell types irrespective of their modulatory effect on respective TLR mRNA levels. CONCLUSION: Thus, cell-type-specific expression and regulation of TLRs may be involved in infection-associated exacerbation of immune complex glomerulonephritis of MRLlpr/lpr mice.