Effects of inflammatory cytokines on the permeability of human lung microvascular endothelial cell monolayers and differential eosinophil transmigration

BACKGROUND: Rhinovirus (RV) infections can result in asthma exacerbations in both adults and children. Respiratory epithelium, the primary site of RV replication, responds to the viral infection by generating a variety of cytokines and chemokines capable of promoting airway inflammation and hence might increase asthma severity. Some of these mediators might also affect the permeability of underlying vascular endothelium. OBJECTIVE: We hypothesized that RV infections can promote airway inflammation and thus asthma by enhancing local vascular permeability. METHODS: Confluent human lung microvascular endothelial cell (HMVEC-L) monolayers were used as an in vitro model of vascular endothelium to determine whether cytokines associated with RV-induced infections are capable of modulating endothelial cell permeability as measured by means of transendothelial electrical resistance. Recombinant cytokines and chemokines were added to confluent HMVEC-L monolayers cultured on Transwell filters, and permeability was measured as decreased electrical resistance over time. Eosinophil transendothelial migration was assessed under the same experimental conditions. RESULTS: TNF- alpha, IL-1 beta, and IFN- gamma significantly increased HMVEC-L permeability. In contrast, GM-CSF, G-CSF, IL-8, IL-6, and RANTES had no effect. Although incubation of HMVEC-L monolayers with either TNF-alpha or IL-1beta promoted eosinophil migration, IFN-gamma had no effect, indicating that enhanced permeability alone was not sufficient for eosinophil infiltration. CONCLUSION: Select cytokines, generated in response to RV infection, can increase vascular permeability and might provide a mechanism by which RV infection can lead to edema, cellular infiltration, and inflammation and thus compromised airflow.     

几种细胞因子对登革病毒感染U937细胞的影响研究

本文作者研究了几种细胞因子（ｒＩＬ－１，ｒＩＬ－２，ｒＩＬ－６，ｒＴＮＦ－α，ｎＩＦＮ－α和ｎＩＦＮ－γ）对Ｄ２Ｖ感染Ｕ９３７细胞的影响，结果显示：除ｎＩＦＮ－γ对ＤＶ感染Ｕ９３７细胞的感染无影响外，其余几种细胞因子都可使Ｄ２Ｖ感染Ｕ９３７细胞的感染率明显降低，为研究细胞因子在ＤＶ感染中的作用作了初步探索。     

Tissue plasminogen activator induced by dengue virus infection of human endothelial cells

Dengue hemorrhagic fever and dengue shock syndrome (DHF/DSS) are severe complications of dengue virus (DV) infection. However, the pathogenesis of hemorrhage induced by dengue virus infection is poorly understood. Since endothelial cells play a pivotal role in the regulation of hemostasis, we studied the effect of DV infection on the production of tissue plasminogen activator (tPA) and plasminogen activator inhibitor 1 (PAI-1) in vitro using both primary isolated endothelial cells, human umbilical cord veins cells, and a human microvascular endothelial cell line. DV infection significantly induced the secretion of tPA but not PAI-1 of human endothelial cells. In addition, tPA mRNA of endothelial cells was induced by DV as demonstrated by RT-PCR. Antibody against IL-6 but not control antibody inhibited DV-induced tPA production of endothelial cells. Furthermore, a good correlation between sera levels of IL-6 and tPA was found in DHF but not DF patients. These results suggest that IL-6 can regulate DV-induced tPA production of endothelial cells, which may play important roles in the pathogenic development of DHF/DSS.     

Supernatants from dengue virus type-2 infected macrophages induce permeability changes in endothelial cell monolayers

The ability of dengue virus-infected human monocyte-derived macrophages to induce permeability changes in primary human umbilical vein endothelial cells was investigated. Supernatants from dengue virus type 2-infected monocyte-derived macrophages increased permeability in human umbilical vein endothelial cell monolayers without inducing endothelial cell infection. Production of permeabilising activity from monocyte-derived macrophages occurred after the peak of progeny virus release. TNF-alpha, a known inducer of endothelial cell permeability, was released from dengue virus infected monocyte-derived macrophages but its release did not coincide with release of endothelial cell permeabilising activity. Permeability induction was enhanced by pre-incubation with supernatants from infected monocyte-derived macrophages harvested at the time of peak release of TNF-alpha and infectious virus. Thus, supernatants from dengue virus-infected monocyte-derived macrophages contain factors that increase human umbilical vein endothelial cell permeability, but this is not accompanied by endothelial cell infection or directly correlated with release of dengue virus or TNF-alpha from monocyte-derived macrophages. This model system can be used for further in vitro analysis of mechanisms that may relate to capillary leakage and the development of dengue haemorrhagic fever/dengue shock syndrome.     

Dengue hemorrhagic fever-associated immunomediators induced via maturation of dengue virus nonstructural 4B protein in monocytes modulate endothelial cell adhesion molecules and human microvascular endothelial cells permeability

We previously demonstrated that dengue virus (DENV) nonstructural 4B protein (NS4B) induced dengue hemorrhagic fever (DHF)-associated immunomediators in THP-1 monocytes. Moreover, cleavage of NS4AB polyprotein by the NS2B3 protease, significantly increased immunomediator production to levels found after DENV infection. In this report using primary human microvascular endothelial cells (HMVEC) transwell permeability model and HMVEC monolayer, we demonstrate that the immunomediators secreted in the supernatants of DENV-infected monocytes increase HMVEC permeability and expression of ICAM-1, VCAM-1 and E-selectin. Moreover, maturation of NS4B via cleavage of 2KNS4B is sufficient to induce immunomediators that cause HMVEC phenotypic changes, which appear to be synergistically induced by TNFα and IL-8. These data suggest that therapies targeting the maturation steps of NS4B, particularly 2KNS4B processing, may reduce overall DHF-associated immunomediator levels, thereby reducing DHF-associated morbidity and mortality. Alternatively, TNFα inhibitors may be a valid intervention strategy during the later stages of infection to prevent DHF progression.     

In vitro effects of PAF on venous endothelial cell actin disposition

Venous endothelial cells have been stainedin vitro for the contractile protein actin, using an immunofluorescence technique. Semi-automated image analysis showed that treatment with platelet-activating factor (PAF 5×10^–7 M) caused elongation of endothelial cells and alteration in their actin-staining characteristics. These changes are prevented by the PAF antagonist BN52021 (1×10^–5 M and 1×10^–6 M) and the absence of extracellular Ca⁺⁺. It is suggested that it is the resultant decrease in intracellular Ca⁺⁺ levels which is responsible for preventing the effects of PAF.     

Differential regulation of angiopoietin 1 and angiopoietin 2 during dengue virus infection of human umbilical vein endothelial cells: implications for endothelial hyperpermeability

Infection with dengue virus (DV) can result in dengue hemorrhagic fever and dengue shock syndrome, where patients suffer from bleeding and plasma leakage involving endothelial cells. Angiopoietins (Ang) 1 and 2 are important angiogenic factors that affect endothelial barrier integrity. In this study, DV was observed to induce endothelial leakage at multiplicity of infection of 10 in primary human umbilical vein endothelial cells (HUVEC) with interendothelial gap formation. Immunostaining of vascular endothelial cadherin (VE-cadherin) and zona occludin 1 (ZO-1) showed the absence of these endothelial junctional proteins at the cell–cell contact zones between adjacent cells. In addition, Ang1 that is required for protecting against endothelial hyperpermeability was found to be down-regulated during DV infection. Treatment with increasing concentrations of recombinant Ang1 was shown to prevent DV-induced endothelial hyperpermeability in a dose-dependent manner by preventing the down-regulation of VE-cadherin and ZO-1 at cell membrane. In contrast, the expression of Ang2, the natural antagonist of Ang1, was observed to be up-regulated during DV infection. Recombinant Ang2 added to HUVEC at non-toxic concentrations showed decreased in transendothelial electrical resistance reading and the down-regulation of VE-cadherin and ZO-1. These findings suggest that DV reduces the expression of Ang1 and enhances the expression of Ang2 in endothelial cells and that this imbalance of Ang 1 and Ang 2 may play a contributing role to the increased permeability of human primary endothelial cells during DV infection.     

高浓度尿素诱导人脑微血管内皮细胞系产生炎性因子

目的研究高浓度尿素诱导人脑微血管内皮细胞系(HBMECs)产生炎性因子及其机制。方法以相同渗透压的甘露醇为对照,高浓度尿素(25 mmol/L)干预HBMECs 3、6、12和24 h后,免疫荧光法观察细胞内肿瘤坏死因子α(TNF-α)和诱导型一氧化氮合酶(i NOS)的表达。蛋白免疫印迹法(Western blot)检测TNF-α、i NOS、环氧合酶-2(cycloxygenase-2,COX-2)、核因子κB(NF-κB)/P65和p-P65的表达水平。一氧化氮(NO)试剂盒检测细胞NO含量。结果高浓度尿素增强细胞内TNF-α和i NOS表达。细胞TNF-α、COX-2和p-P65蛋白水平在3和6 h明显高于对照组(P0.01);i NOS蛋白水平持续增高(P0.01)。NO含量在3 h明显增多(P0.05)。结论高浓度尿素诱导人脑微血管内皮细胞产生炎性因子。     

Ultrastructural studies on dengue virus infection of human lymphoblasts

Ultrastructural studies of dengue-2 virus-infected lymphoblastoid Raji cells showed that the virus induced an increase in the size of the rough endoplasmic reticula (RER) and that the replication of the virus was confined to the cisternae of these RER. The proliferating RER formed cytoplasmic inclusions that could be seen by light microscopy. This observation could be used as evidence of a cytopathogenic effect of dengue virus on infected Rajii cells in routine cultures. Accumulation of virions in the infected cells was minimal in comparison with other cell systems, however. Sporadic clusters of mature virions were often seen on the plasma membrane. These extracellular virions were distributed adjacent to the virus-bearing RER and were presumably released virions. Vertical transmission of the virus was evident in mitotic lymphoblasts. The replication pattern of dengue virus in lymphoblastoid cells suggests that efforts should be made to determine whether blast-transformed lymphocytes, numerous in secondary dengue infections, support dengue virus replication in vivo.     

Association of influenza virus infection and inflammatory cytokines with acute myocardial infarction

Objective  

To explore the potential relationship between previous influenza virus (IV) infection and acute myocardial infarction (AMI), and the mechanism of atherosclerosis, we conducted a case–control study and examined inflammatory cytokines to assess the association of previous IV infection and AMI.     

Centrifugal enhancement of Kaposi's sarcoma-associated virus infection of human endothelial cells in vitro

In order to improve the efficiency of infection of primary human endothelial cells in vitro of Kaposi's sarcoma-associated herpesvirus (KSHV), the effect of low speed centrifugation was investigated. The recombinant KSHV, BAC36, was used to examine the centrifugal enhancement of KSHV. Infectivity was estimated by green fluorescent protein (GFP) expression and real-time RT-PCR. The enhancement of infectivity was dependent upon the time and force of centrifugation in human umbilical vein endothelial cells (HUVECs). Centrifugation enhanced the infectivity of KSHV by up to 70 fold compared to non-centrifugal control infection for the same period of time; viral mRNA expression was also enhanced by centrifugation. HUVECs that were centrifuged before infection with KSHV displayed no enhancement in infectivity; therefore, enhancement is believed to occur during centrifugation. In addition, the mechanisms of infection including the initial viral attachment to cells, lipid rafts, and clathrin-mediated and caveolae endocytosis appear to be similar in KSHV infection with and without centrifugal enhancement. These results show that low speed centrifugation could be a useful tool for improving the efficiency of KSHV infection in vitro.     

Antibody-dependent enhancement of dengue virus infection in vitro by undiluted sera from monkeys infected with heterotypic dengue virus

Two monkeys (Macaca fascicularis) each were infected with dengue virus type 1 (DENV-1) and type 2 (DENV-2). High levels of neutralizing antibody to homotypic serotype were detected from day 10 to week 58 after infection. Levels of cross-reactive neutralizing antibody to other serotypes were at lower levels or undetectable. Serum samples collected from day 10 to week 58 enhanced infection by homotypic and heterotypic serotypes of DENV when diluted, demonstrating antibody-dependent enhancement (ADE). The ADE activities to heterotypic and homotypic dengue virus infections peaked at dilutions of 1:10–1:100 and 1:100–1:1,000, respectively. Serum samples collected enhanced heterotypic dengue virus infection without any dilution. The results indicate that sera from infected monkeys have an ability to enhance heterotypic dengue virus infection in vitro without dilution, although some of these sera also possess neutralizing activity.     

抗DEN-2基因核酶的克隆及其体外切割活性的研究

目的：探讨核酶抗登革病毒活性。方法：根据DEN－2基因结构的特点，按照锤头状核酶的结构模型和作用模式，设计，合成针对172－174GUC位点的核酶基因；定向插入质粒pGEM-3Zf( )的Sac I和Sal I位点之间；核酶基因克隆和DEN－2靶基因克隆分别进行体外转录，生成核酶的靶RNA，体外进行切割反应。结果：核酶与登革病毒靶序列体外产物电泳 见预期切割条带。结论：该核酶具有切割相应靶RNA的活性，可进一步用于细胞内核酶抗登革病毒的研究。     

登革病毒对人血管内皮细胞分泌ET-1及PGI2的影响

目的　研究登革病毒感染对人血管内皮细胞分泌重要的血管活性物质ＥＴ１ 及ＰＧＩ２ 的影响,以了解登革出血热及登革休克综合征（ＤＨＦＤＳＳ）的发病机制。方法　用登革病毒Ⅱ型,感染人脐静脉内皮细胞（ＨＵＶＥＣ） ,于感染后４ 、２４ 、４８ 、７２ 及９６ 小时,分别收集病毒感染上清液,用放射免疫检测法测定ＥＴ１ 及ＰＧＩ２ 的含量。结果　登革病毒感染可使ＨＵＶＥＣ分泌ＥＴ１ 及ＰＧＩ２ 的能力受到明显抑制。在病毒感染早期（４ 小时）,ＨＵＶＥＣ分泌ＥＴ１ 及ＰＧＩ２ 的能力即受到明显抑制。登革病毒对ＨＵＶＥＣ分泌ＥＴ１ 抑制作用强烈而持久,至感染后９６ 小时,ＨＵＶＥＣ分泌ＥＴ１ 的能力与未受感染的阴性对照组比较,差异仍有显著性。然而,登革病毒对ＨＵＶＥＣ 分泌ＰＧＩ２ 的抑制作用,可随时间的推移而减弱,至感染后９６ 小时,ＨＵＶＥＣ分泌ＰＧＩ２ 的能力已达正常水平。结论　登革病毒感染可影响血管内皮细胞分泌血管活性物质ＥＴ１ 及ＰＧＩ２ 的功能,导致血管通透性增加和凝血、止血功能障碍。因此,登革病毒所致的血管内皮细胞功能障碍,可能是ＤＨＦＤＳＳ重要的发病机制     

GM—CSF在登革病毒感染人单核细胞中的作用

以正常人外周血和脐带血单核细胞作为登革Ⅱ型病毒（Ｄ２Ｖ）感染的靶细胞，研究了粒细胞巨噬细胞集落刺激因子（ＧＭ－ＣＳＦ）对Ｄ２Ｖ复制的影响以及单核细胞感染Ｄ２Ｖ后ＧＭ－ＣＳＦ产生能力的变化。结果表明，ＧＭ－ＣＳＦ能增加Ｄ２Ｖ的复制，Ｄ２Ｖ感染能引起人单核细胞产生ＧＭ－ＣＳＦ，它们的量与Ｄ２Ｖ感染量呈正相关。结果提示，ＧＭ－ＣＳＦ在病毒感染过程中起重要作用。     

Dengue virus infection: predictors for severe dengue

Dengue virus (DENV) infection is a mosquito born disease that is endemic in all WHO regions, except European region, and may present a broad range of severity. It may appear as an asymptomatic condition, dengue fever (DF), or life threatening forms, such as dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS), or the currently defined severe dengue. Currently there are means to diagnose DENV infection, but there is no accurate means to early predict the progress into severe manifestations. Therefore, this article addresses the factors that might be used to predict the progress into severe dengue. Predictors for severe dengue are the previously established warning signs, and coexisting conditions, as is recommended by the WHO, in addition to Caucasian race, and people with AB blood group. In the future, viral load assessment, viral serotype testing, NS1, cytokine, elastase, hyaluronan, soluble thrombomodulin, and NO level, and circulating endothelial cell detection test are promising to be studied and developed as early predictors of severe dengue.     

Antigenic cell associated dengue 2 virus proteins detected in vitro using dengue fever patients sera

At least three major antigenic dengue 2 virus proteins were recognized by pooled dengue fever patients' sera in infected Aedes albopictus (C6/36) mosquito cells. Dengue virus envelope (E), premembrane (PrM) and non-structural protein 1 (NS 1) dimer were detected beginning on day 3 postinfection in both the cell membrane and cytosolic fractions. Using the patients' sera, the presence of antigenic intermediate core protein (C)-PrM and NS1-non-structural protein 2a (NS2a) in the cytoplasmic fraction of dengue 2 virus infected cells was revealed. The presence of a approximately 92 and approximately 84 kDa NS 1 dimer in the membrane (NS 1m) and cytosolic (NS 1c) fractions of C6/36 cells, respectively, was also recognized. Using individual patient's serum, it was further confirmed that all patients' sera contained antibodies that specifically recognized E, NS 1 and PrM present in the dengue 2 virus-infected cell membrane fractions, suggesting that these glycosylated virus proteins were the main antigenic proteins recognized in vivo. Detection of dengue 2 virus C antibody in some patients further suggested that C could be antigenic if presented in vivo.     

Natural killer cell infection and inactivation in vitro by the human immunodeficiency virus

Cytolytic activity of human mononuclear peripheral blood leukocytes from healthy donors, cultured in interleukin-2 conditioned medium, was abrogated by in vitro infection with the lymphadenopathy associated virus (LAV) isolate of the human immunodeficiency virus (HIV). Although viral antigens are not expressed in cultured cells until 14 days postinfection, cytolytic activity was lost as early as 3 days after infection. Loss of cytolytic function was not a result of the release of suppressive factors from either infected cells or uninfected CEM cells since supernatants from neither infected cultures nor CEM cell cultures had any inhibitory effects on the function of uninfected cells. Cultured lymphocytes expressing Leu 11b were also shown to express HIV antigens via immunofluorescence after 14 days in culture. These results suggest that natural killer (NK) cells, as defined by expression of Leu 11b, were infected by HIV in vitro and the loss of lytic function was likely a direct consequence of that infection.