Role of Nuclear Transcription Factor-κB in Endotoxin-induced Shock in Rats

To investigate the role of NF-κB in endotoxic shock in rats. the model of endotoxinshock rats was induced by intravenous infusion of lipopolysaccharidc (LPS). 1 h. 2 h. 4 h and 6 h after LPS injection, the activation of NF-κB in blood mononuclear cells and the content of TNF-α and IL-6 in plasma was detected by enzyme-linked immunoadsordent assay (ELISA). The level of mean arterial pressure (MAP) and the histopathological changes of lung and liver were also observed. The activation of NF-κB in mononuclear cells increased 1 h after LPS injection and reached its peak 2 h after the injection, and its level was higher than that of normal group. The level of TNF-α was increased 1 h after the infusion and peaked 2 h after the injection, and its level was higher than that of normal group after LPS infusion. The content of IL-6 increased gradually with time. the IL-6 level was higher than that of normal group after LPS injection. MAP was decreased gradually with time and its level was lower than that of normal group after LPS injection. Pathological examination showed that endotoxic shock could cause pulmonary alveolar hemorrhage, edema and infiltration of inflammatory cell in lung tissue and congestion, edema, capillary dilation and inflammatory cell infiltration in liver tissue. It is concluded that NF-κB can up-regulate the expression of TNF-α and IL-6 in plasma and play an important role in endotoxin induced shock in rats.     

Protective Effect of Emodin against Lipopolysaccharidesinduced Corneal Injury in Rats

Objective To investigate the effect of emodin on lipopolysaccharides （LPS）-induced corneal injury in rats. Methods Three parallel incisions on the central surface of corneal epithelium were made and LPS was applied on them to induce corneal injury in Wistar rats. All rats were randomly divided into emodin group （n=40） and keratitis group （n=40）. Rats in the emodin group received subconjunctival injection of emodin and rats in the keratitis group received its vehicle 30 minutes before LPS exposure. At different time points-1 3, 6, 12, and 24 hours after LPS exposure, the symptoms of all rats were observed and the severity of their ocular inflammation was examined with a slit lamp microscope, then 8 rats in each group were killed through cervical dislocation and their eyes were enucleated and prepared to observe pathological changes of corneal tissue under a light microscope. The activation of nuclear factor-loB （NF-κB） under different condi- tions was determined by Western blot. Immunocytochemistry staining with an antibody against intercellular adhesion molecule-1 （ICAM-1） was performed to identify positive cells in corneal tissues. Results The model of acute keratitis was successfully established in Wistar rats. LPS could induce a typical corneal inflammatory response, such as hyperemia, corneal edema and opacity, which were observed in model rats. Compared with keratitis group, both ocular behaviors and damages of the corneal structure were improved in emodin group. Furthermore, the activation of NF-κB and the expression of ICAM-1 induced by LPS were markedly inhibited in emodin group. Conclusion Emodin can inhibit the activation of NF-κB and the expression of ICAM-I induced by LPS in corneas, protect against acute corneal injury, and improve symptoms in rats.     

Effect of surfactant protein A on lipopolysaccharide-induced tumor necrosis factor-α expression in human proximal tubular epithelial cells

Background Surfactant protein A （SP-A） contributes to the regulation of sepsis-induced acute lung injury.In a previous study,we demonstrated the expression and localization of SP-A in the kidneys.The present study evaluated the effect of SP-A on lipopolysaccharide （LPS）-induced tumor necrosis factor-α （TNF-α） expression and its underlying mechanisms in the human renal tubular epithelial （HK-2） cells.Methods Indirect immunofiuorescence assay was used to detect SP-A distribution and expression in HK-2 cells.HK-2 cells were treated with various concentrations of LPS （0,0.1,1,2,5,and 10 mg/L） for 8 hours and with 5 mg/L LPS for different times （0,2,4,8,16,and 24 hours） to determine the effects of LPS on SP-A and TNF-α expression.Then,HK-2 cells were transfected with SP-A siRNA to analyze nuclear factor κB （NF-κB） P65 and TNF-α expression of HK-2 cells after LPS-treatment.Results Indirect immunofluorescence assay revealed that SP-A is localized to the membrane and cytoplasm of HK-2 cells.Interestingly,SP-A1/SP-A2 and TNF-α expression were found to be significantly increased in HK-2 cells upon LPS treatment.Transfection of LPS-treated HK-2 cells with SP-A siRNA resulted in significant increases in the levels of NF-κB P65 protein and TNF-α mRNA and protein compared to those in non-transfected LPS-treated HK-2 cells.Conclusion SP-A plays an important role in protecting cells against sepsis-induced acute kidney injury by inhibiting NF-κB activity to modulate LPS-induced increase in TNF-α expression.     

Inhibition of NF-κB by mutant IκBα enhances TNF-α-induced apoptosis in HL-60 cells by controlling bcl-xL expression

Backgound The aim of this study was to explore whether the inhibition of nuclear factor-κB (NF-κB)activation by mutant IκBα (S32,36→A) can enhance TNF-α-induced apoptosis of leukemia cells and to investigate the possible mechanism. Methods The mutant IκBα gene was transfected into HL-60 cells by liposome-mediated techniques. G418 resistant clones stably expressing mutant IκBα were obtained by the limiting dilution method. TNF-α-induced NF-κB activation was measured by electrophoretic mobility shift assay (EMSA). The expression of bcl-xL was detected by RT-PCR and Western blot after 4 hours exposure of parental HL-60 and transfected HL-60 cells to a variety of concentrations of TNF-α. The percentage of apoptotic leukemia cells was evaluated by flow cytometry (FCM). Results Mutant IκBα protein was confirmed to exist by Western blot. The results of EMSA showed that NF-κB activation by TNF-α in HL-60 cells was induced in a dose-dependent manner, but was almost completely inhibited by mutant IκBα repressor in transfected cells. The levels of bcl-xL mRNA and protein in HL-60 cells increased after exposure to TNF-α, but changed very little in transfected HL-60 cells. The inhibition of NF-κB activation by mutant IκBα enhanced TNF-α-induced apoptosis. Thecytotoxic effects of TNF-α were amplified in a time- and dose-dependent manner. Conclusions NF-κB activation plays an important role in the resistance to TNF-α-induced apoptosis. The inhibition of NF-κB by mutant IκBα could provide a new approach that may enhance the antileukemia effects of TNF-α or even of other cytotoxic agents.     

LPS-induced NF-κB activation requires Ca2+ as a mediator in isolated pancreatic acinar cells of rat

Objective To investigate the effect of Ca2+ on lipopolysaccharide (LPS)-induced NF-κB activation in pancreatic acinar cells and the role of NF-κB in LPS-induced acinar cell injury. Methods Male rat pancreatic acinar cells were isolated by collagenase digestion, then exposed to varying concentrations of LPS (from 1 to 20 mg/L) in the presence or absence of EGTA. At various time points (30 minutes, 1 hour, 2 hours, 4 hours and 10 hours) after treatment with the agents, cell viability was determined by MTT. Nuclear translocation of NF-κB’s subunit p65 was visualized by immunofluorescence staining and nuclei protein was extracted to perform EMSA which was used to assay the activity of NF-κB binding to the DNA sequence containing the recognition site of NF-κB. Results LPS induced cell damage in a time- and concentration-dependent manner while EGTA attenuated LPS-induced cell damage (P<0.05). NF-κB p65 immunofluorescence staining had increased intensity in the cytoplasm and indicated that nuclear translocation occurred within 30 minutes and its zenith was reached at 1 hour after LPS (10 mg/L) treatment. Testing of NF-κB DNA binding activity showed the same alteration phase as p65 immunofluorescence staining. NF-κB activation preceded the pathological alteration of pancreatic acinar cells. The Ca2+ chelator EGTA inhibited LPS-induced NF-κB activation. Conclusions NF-κB activation is an important early event in LPS-induced injury to pancreatic acinar cells. Ca2+ is an important mediator in the process of LPS-induced NF-κB activation.     

Perfluorocarbon attenuates lipopolysaccharide-mediated inflammatory responses of alveolar epithelial cells in vitro

Background  Toll-like receptor-4 (TLR-4) is integrally involved in lipopolysaccharide (LPS) signaling and has a requisite role in the activation of nuclear factor-κB (NF-κB). The exact mechanisms that lend perfluorocarbon (PFC) liquids a cytoprotective effect have yet to be elucidated. Therefore we examined in an in vitro model the cytoprotective effect of PFC on LPS-stimulated alveolar epithelial cellls (AECs). 

Methods  AECs (A549 cells, human lung adenocarcinoma cell line) were divided into four groups: control, PFC, LPS and LPS + PFC (coculture group) groups. Intercellular adhesion molecule-1 (ICAM-1) was detected by ELISA, tumor necrosis factor-α (TNF-α) and interleukin-8 (IL-8) were detected by radioimmunological methods. The expression of TLR-4 mRNA and protein was detected by real time PCR and Western blotting, respectively. The activation of NF-κB was detected by Western blotting (proteins of I-κBα and NF-κB p65). 

Results  ICAM-1, TNF-α and IL-8 were significantly increased in LPS-stimulated AECs groups. The expression of TLR-4 mRNA and protein in LPS-stimulated groups was markedly increased. Meanwhile, NF-κB was activated as indicated by the significant degradation of IκB-α and the significant release of NF-κB P65 and its subsequent translocation into the nucleus. There were no significant effects of PFC alone on any of the factors studied while the coculture group showed significant downregulation of the secretion of ICAM-1, TNF-α and IL-8, the expression of TLR-4 mRNA and the activity of NF-κB. 

Conclusions  Taken together, our results demonstrate that LPS can induce AEC-related inflammatory injury via the activation of TLR-4 and subsequent activation of NF-κB. PFC is able to protect AECs from LPS-induced inflammatory injury by blocking the initiation of the LPS signaling pathway, which is indicated by the significant decrease of TLR-4 expression and NF-κB activation.

     

The Role of IκBα in TNF-α-induced Apoptosis in Hepatic Stellate Cell Line HSC-T6

To investigate the role of NF-κB in TNF-α induced apoptosis in HSC-T6, a mutant IκBα was transfected into HSC-T6 cells by lipofectin transfection technique and its transient effect was examined 48 h after the transfection. The activation of NF-κB was detected by immune fluorescence cytochemistry and Western blotting with anti-p65 antibody. The apoptosis and the rate of inhibition by TNF-α in both transfected and untransfected HSC-T6 cells were measured respectively by FAC-Scan side scatter analysis and MTF methods. Our results showed that TNF-α could activate NF-κB in untransfected cells but not in transfected HSC-T6 cells. The percentage of apoptosis in transfected cells were significantly higher than that in the untransfected ones （P〈0.01） and it was also true of the inhibition rate （P〈0.01）. It is concluded that the resistance of HSC-T6 towards apoptosis induced by TNF-α can be mediated by NF-κB activation. The inhibition of NF-κB activation by mutant IκBα can attenuate the resistance of HSC-T6 cells and increase its sensitivity to TNF-α.     

EFFECT OF PEROXISOME PROLIFERATOR-ACTIVATED RECEPTOR ACTIVATORS ON TUMOR NECROSIS FACTOR-α EXPRESSION IN NEONATAL RAT CARDIAC MYOCYTES

Objective To investigate the effect ofperoxisome proliferator-activated receptor-α (PPARα) and PPARγ activators on tumor necrosis factor-α (TNFα) expression in neonatal rat cardiac myocytes.Methods Primary cultures of cardiac myocytes from 1- to 3-day-old Wistar rats were prepared, and myocytes were exposed to lipopolysaccharide (LPS) and varying concentrations of PPARα or PPARγ activator (fenofibrate or pioglitazone).RT-PCR and ELISA were used to measure TNFα, PPARα, and PPARγexpression in cultured cardiac myocytes. Transient transfection of TNFα promoter with or without nuclear factor-kappaB (NF-κB) binding site to cardiac myocytes was performed.Results Pretreatment of cardiac myocytes with fenofibrate or pioglitazone inhibited LPS-induced TNFα mRNA and protein expression in a dose-dependent manner. However, no significant changes were observed on PPARα or PPARγ mRNA expression when cardiac myocytes were pretreated with fenofibrate or pioglitazone. Proportional suppression of TNFαpromoter activity was observed when myocytes was transiently transfected with whole length of TNFα promoter (-721/ 17) after being stimulated with LPS and fenofibrate or pioglitazone, whereas no change of promoter activity was observed with transfection of TNFα reporter construct in deletion of NF-κB binding site (-182/ 17).Conclusions PPARα and PPARγ activators may inhibit cardiac TNFα expression but not accompanied by change of PPARα or PPARγmRNA expression. Therefore PPARα and PPARγ activators appear to play a role in anti-inflammation.The mechanism may partly be involved in suppression of the NF-κB pathway.     

Effect of N-tosyl-L-phenylalanylchloromethyl Ketone on Tumor Necrosis Factor-alpha -induced NF-κB Activation and Apoptosis in U937 Cell Line

Summary: To investigate the effect of N-tosyl-L-phenylalanylchloromethyl ketone (TPCK) on tumor necrosis factor-alpha-induced NF-κB activation and apoptosis in U937 cell line, changes and subcellular localization of NF-κB/p65 and IκB-α were observed by fluorescencemicroscopy and expression and degradation of IκB-α by flow cytometry. The apoptosis of U937 cells was measured by flow cytometry and electrophoresis of DNA. Immunolfluorescence assay showed that NF-κB/p65,IκB-α only localized in cytoplasm. After TNF-α stimulation, p65 was localized only in nuclei, and IκB-α was only localized in cytoplasm and decreased. The changes of TNF-α stimulation were specifically inhibited by TPCK. Flow cytometry also revealed the downregulation of IκB-α protein during TNF-α-induced apoptosis and the down-regulation was specifically inhibited by TPCK. Flow cytometry also showed the apoptosis of U937 cells after TNF-α induction. DNA ladder can be detected in cells treated by TNF-α. It is concluded that degradation of IκB-α protein and NF-κB/p65 translocation occur during TNF-α-induced apoptosis of U937 cells, suggesting the activation of NF-κB.TPCK-sensitive protease plays an important role in the degradation of IκB-α protein induced by TNF-α in U937 cells. TPCK sensitive protease also plays an important role in the apoptosis of U937 cells induced by TNF-α.     

Toll-like receptor 4/nuclear factor-kappa B signaling detected in brain after early subarachnoid hemorrhage

Background Inflammation and immunity play a vital role in the pathogenesis of early brain injury after subarachnoid hemorrhage （SAH）. Nuclear factor-kappa B （NF-κB） regulates many genes essential for inflammation and immunity and is activated by toll-like receptor （TLR）. This study aimed to detect the expression of the toll-like receptor 4/nuclear factor-kappa B （TLR4/NF-κB） signaling in the rat brain after early SAH. Methods The rats were decapitated and their brains were removed at 0, 2, 4, 6, 12, 24 and 48 hours after a single injection of blood into the prechiasmatic cistern, mRNA expression of TLR4 was measured by Taqman real-time RT-PCR, and protein expression by immunohistochemistry and Western blotting. NF-κB activity and concentrations of tumor necrosis factor-alpha （TNF-α）, interleukin-lbeta （IL-1β） and interleukin-6 （IL-6） were measured by enzyme-linked immunosorbent assay （ELISA）. Results TaqMan real-time RT-PCR and Western blotting identified a biphasic change in TLR4 expression in both mRNA and protein： an initial peak （2-6 hours） and a sustained elevation （12-48 hours）. Immunohistochemical staining showed the inducible expression of TLR4-like immunoreactions predominantly in glial cells and vascular endothelium. A similar biphasic change in the activation of NF-κB subunit p65 as well as the production of NF-κB-regulated proinflammatory cytokines （TNF-α, IL-1β and IL-6） were detected by ELISA. Conclusions These data suggest that experimental SAH induces significant up-regulation of TLR4 expression and the NF-κB signaling in early brain injury. Activation of the TLR4/NF-κB signaling may regulate the inflammatory responses after SAH.     

氯胺酮对内毒素诱导大鼠急性肺损伤的影响及其机制

目的探讨不同剂量氯胺酮对内毒素（LPS）诱导大鼠肺损伤的影响和作用机理。方法48只雄性Wistar大鼠随机分为4组：对照组,LPS组（5mg／kg）,低剂量氯胺酮治疗组（5mg／kg）,高剂量氯胺酮治疗组（10mg／kg）,每组12只。建立内毒素诱导的大鼠急性肺损伤模型,于注射LPS后4h处死大鼠,测肺湿／干重比,观察支气管肺泡灌洗液（BALF）中性粒细胞计数比、蛋白浓度,测肺组织中肿瘤坏死因子α（TNF-α）、白细胞介素-8（IL-8）、NO水平。RT．PCR测肺组织中．NOSmRNA表达,Western-blot测肺组织中NF-κB蛋白表达。结果LPS组大鼠肺湿／干重比、BALF中性粒细胞计数比、蛋白浓度均明显增加（P〈0．01）,肺组织中TNF-α、IL-8、NO水平显著性升高（P〈0.01）,同时肺组织中iNOSmRNA和核因子-κB（NF-κB）蛋白表达均增加。而氯胺酮治疗组的各项指标均较LPS组减轻,大剂量组作用更明显。结论氯胺酮通过抑制NF-κB表达,减少炎症性细胞因子的产生,从而对内毒素（LPS）诱导的大鼠肺损伤有一定保护作用。     

大黄素对急性角膜炎症反应中ICAM-1表达的影响及意义

 目的 观察大黄素对急性角膜炎大鼠角膜组织中细胞间粘附分子-1（ICAM-1）表达的影响及意义。方法 建立角膜炎大鼠模型,模型制备前30 min,大鼠结膜下分别注射大黄素（治疗组）及等容二甲基亚砜（炎症组）。按脂多糖(LPS)刺激后不同时点,各组又分为1、3、6、12、24?h组,每亚组8只鼠。于各时点观察大鼠的全身情况,裂隙灯显微镜观察大鼠结膜、角膜及房水等眼部表现;抽取大鼠房水涂片,HE染色观察房水细胞的变化;角膜组织切片,HE染色观察各组大鼠角膜的组织形态学改变;逆转录 聚合酶链反应（RT-PCR）检测大鼠角膜组织中ICAM-1 mRNA的表达。 结果 球结膜下预防性注射大黄素,可明显改善角膜炎大鼠畏光、流泪等眼部表现,减轻角膜混浊、组织水肿等炎症反应。大黄素预处理可明显减轻大鼠角组织及房水中炎症细胞浸润的程度,改善角膜组织水肿及角膜基质层胶原纤维排列的紊乱程度。LPS刺激可引起炎症组大鼠角膜组织中ICAM-1mRNA表达增加,该作用可被大黄素部分抑制,治疗组各时点ICAM-1 mRNA的表达较炎症组均明显降低（P均＜0.01）。  结论 大黄素可减少急性角膜炎症反应中ICAM-1 mRNA的表达,对急性角膜炎大鼠角膜损伤起保护作用。     

Triggering of toll-like receptors 2 and 4 by Aspergillus fumigatus conidia in immortalized human corneal epithelial cells to induce inflammatory cytokines

Background Cornea epithelial cells play eady and crucial roles in the initiation of ocular surface responses to pathogens. Participation of toll-like receptor （TLR） 2 and TLR4, which are major forms of fungi receptors, may be involved in Aspergillus fumigatus induced immune responses. The objective of the present study was to examine whether inactive Aspergillus fumigatus conidia induce NF-KB activation and production of proinflammaory cytokines, and whether the expression of TLR2 and TLR4 were amplified by conidia in cultured immortalized human corneal epithelial cells （THCEs）. This may contribute to our knowledge of the mechanism by which the host cornea can successfully defend against invasive fungi. Methods Aspergillus fumigatus conidia were used to challenge THCE cells. THCE cells were harvested after 0.5, 1, 2 or 4 hours incubation. Real-time quantitative PCR was performed to determine the expression of TLR2, TLR4, TNF-a and IL-8. Western blotting was performed to determine the expression of NF-KB. Enzyme-linked immunosorbent assay （ELISA） was performed to determine the expression of TNF-a and IL-8. And the release of TNF-a and IL-8 in the cell supematant were also assessed by ELISA with or without pretreatment with TLR2 and TLR4 neutralizing antibodies. Results Aspergillus fumigatus conidia elicited the expression of TLR2, TLR4, TNF-a and IL-8 mRNA in THCEs. Exposure of THCE cells to Aspergillus fumigatus conidia resulted in NF-KB activation, which increased at 30 minutes （increased from 11.35±2.74 in the controls to 19.12±3.48, p〈0.05） and thereafter increased steadily up to 4 hours after challenge （P 〈0.01）. Concomitant with NF-KB activation, secretion of TNF-α and IL-8 in conidia-challenged cells was increased in a time-dependent manner. Incubation of THCE cells with TLR2 antibody or TLR4 antibody before conidia challenge resulted in inhibition of conidia-induced TNF-α and IL-8 secretion （P 〈0.05）, TLR2 antibody and TLR4 antibody together significantly increased inhibit     

小鼠巨噬细胞α-肿瘤坏死因子基因表达的调节

The expression of tumor necrosis factor-alpha (TNF-alpha) mRNA in murine inflammatory peritoneal macrophages (M phi) was studied with a sensitive liquid hybridization method. Upon exposure to 10-1000 ng/ml of lipopolysaccharide (LPS), M phi were induced to express TNF-alpha mRNA in a dose-dependent manner. mRNA was detectable within 1 h after stimulation, peaked at about 2 h and then gradually declined. A 10 min treatment with LPS was enough to stimulate the maximal level of TNF-alpha mRNA, as determined in a 2 h period. Although calcium ionophore A23187 and macrophage activating factor (MAF) (both can activate M phi to mediate tumoricidal activity) did not induce TNF-alpha mRNA expression by themselves, they did act synergistically with LPS. Treatment of M phi with retinoic acid strongly inhibited LPS-induced TNF-alpha mRNA expression, whereas trifluoperazine had an opposite effect. Cycloheximide not only synergized with LPS but also induced TNF-alpha mRNA expression by itself. In contrast, actinomycin D completely blocked LPS-induced TNF-alpha gene activation. These findings indicate that LPS-induced TNF-alpha mRNA expression is not solely due to an increase in intracellular free calcium ion and is independent of the protein kinase C pathway of signal transduction. In addition, TNF gene activity may be regulated by short-lived protein repressor(s).     

白黎芦醇对脂多糖诱导大鼠腹腔巨噬细胞活化的抑制作用

目的探讨脂多糖（LPS）诱导的大鼠腹腔巨噬细胞（PMA）活性变化及白黎芦醇（RESV）对它的抑制作用。方法分离大鼠PMA，随机分为对照组、LPS组和RESVI-V组。培养24h后，分别用免疫组化方法检测核网子-kB（NF-kB）活性，酶联免疫吸附法和硝酸还原法检测细胞上清液中肿瘤坏死因子-α（TNF-α）、白细胞介素-1（IL-1）和一氧化氮（NO）水平。结果对照组仅有少量NF-kB的活化。LPS诱导后，PMA出现大量NF-kB的活化，继而细胞上清液中TNF-α、IL-1和NO的水平显著升高。RESV治疗后NF-kB的活性较PMA组逐渐降低，具有剂量依赖性，并且相应的细胞上清液中TNF-α、IL-1和NO水平明显降低。结论RESV可以抑制PMA中NF-kB的活化，从而减少TNF-α、IL-1和NO的过度分泌。     

RNA干扰对活化的小鼠巨噬细胞肿瘤坏死因子α表达的影响

目的：观察靶向小鼠肿瘤坏死因子α（TNF-α）基因的小干扰RNA（siRNA）在体外对小鼠巨噬细胞系RAW264．7表达TNF-α的抑制作用。方法：采用化学法合成针对TNF-α mRNA不同位点设计的3条siRNA序列（siRNA1～3）和1条带有荧光标记的BLOCK—IT^TM荧光Oligo（修饰的荧光标记的dsRNA,siRNA4）通过脂质体包裹后将其分别转染至小鼠巨噬细胞系RAW264．7,同时设立1个无任何靶基因的siRNA作为阴性对照（siRNA4）。荧光显微镜下观察siRNA的转染效率;用实时荧光定量PCR和酶联免疫吸附实验（ELISA）法分别检测siRNA对TNF-α的mRNA和蛋白表达的抑制作用。结果：内毒素刺激后6h,巨噬细胞表达TNF-α mRNA和合成分泌的TNF-α量均增加,于9～12h达高峰。利用荧光标记的Oligo观察到siRNA转染效率达72％～80％。siRNA1～4转染巨噬细胞后,siRNA2、3可见内毒素刺激的TNF-α mRNA（0．158±0．030、0．114±0．028）和TNF-α蛋白表达[（1355±348）pg／ml、（817±138）pg／m1]均明显少于未转染组[TNF-α mRNA0．294±0．147,蛋白（2104±32）pg／ml,均P〈0．05],其中siRNA3的抑制率非常显著,达61．2％（P〈0．01）。阴性对照siRNA4对细胞基因及蛋白表达无影响。结论：内毒素可刺激小鼠巨噬细胞TNF-α的合成。化学合成siRNA转染小鼠巨噬细胞能有效抑制TNF-α mRNA及蛋白的表达。     

TREM-1在细菌性化脓性角膜炎中的作用及其分子机制

【目的】 探讨髓样细胞诱发受体1(TREM-1)在铜绿假单胞菌(PA)感染角膜炎中的作用及其分子机制。【方法】为了揭示TREM-1在细菌性角膜炎中的作用,我们建立了PA角膜炎小鼠模型和PA感染的腹腔巨噬细胞模型,real-time PCR和免疫荧光法检测感染前后TREM-1的表达水平;用丝裂原活化蛋白激酶(MAPKs)的抑制剂或磷脂酰肌醇3-激酶(PI3K)抑制剂预处理巨噬细胞,再用脂多糖(LPS)和TREM-1活化抗体刺激,real-time PCR检测IL-1β、MIP-2、TNF-α和IL-6等促炎因子的表达水平,进一步探讨TREM-1调控PA角膜炎的分子机制;用Th1细胞因子IFN-γ或者Th2细胞因子IL-4?IL-10刺激巨噬细胞,real-time PCR检测Th1/Th2细胞因子对TREM-1表达的调控。【结果】 PA感染的C57BL/6小鼠角膜中TREM-1表达高于BALB/c小鼠;体外研究显示PA感染和LPS刺激均诱导TREM-1高表达;TREM-1通过MAPK和PI3K-Akt通路调节促炎因子生成;Th1细胞因子促进TREM-1表达,而Th2细胞因子不影响TREM-1的表达。【结论】 PA 感染上调TREM-1的表达,TREM-1通过调控Th1/Th2细胞因子的表达进一步放大炎症,导致角膜溃疡穿孔,这一发现可能为化脓性角膜炎的防治提供了新的理论依据。     

糖皮质激素对内毒素致急性肺损伤大鼠肺组织Fractalkine表达的影响

目的动态观察内毒素（LPS）所致急性肺损伤（acute lung injury,ALI）大鼠肺组织内趋化因子Fractalkine（FKN）的表达变化,及糖皮质激素对其的影响。方法将42只大鼠随机分为空白对照组、模型组（LPS）及地塞米松干预组（DEX）,其中LPS组和DEX组再分为1h、2h、4h3个时相组,每组6只,LPS组和DEX组大鼠经尾静脉注射LPS（4mg／kg）建立ALI大鼠模型。采用ELISA、RT—PCR等方法,观察ALI大鼠模型肺组织病理学改变、肺湿干重比值（W／D）及血清TNF-a变化,并检测肺组织FKNmRNA的表达,同时观察地塞米松对上述指标的影响．结果模型组1h、2h与4h3个时相组肺损伤病理改变、肺W／D、血浆TNF—α均明显增高,地塞米松能减轻ALl大鼠肺组织炎症反应、肺W／D值及血清TNF—α水平（P均〈0．05）。正常大鼠肺组织FKNmRNA有表达,模型组3个时相亚组肺组织FKNmRNA表达较正常组明显增加（P〈0．05）,在2h时点达峰值,地塞米松能下调ALI大鼠肺组织FKNmRNA表达（P〈0．05）。FKNmRNA的表达量与血清TNF—α水平呈正相关（r=0．674,P〈0．05）．结论早期应用地塞米松可降低TNF-α水平,下调肺组织FKN mRNA的表达,这可能是糖皮质激素对内毒素致急性肺损伤实验大鼠保护作用机制之一。