Interleukin-6 production by endothelial cells after infection with influenza virus and cytomegalovirus

114

Influenza virus, the causative agent of the common flu, is a worldwide health problem with significant economic consequences. Studies of influenza virus biology have revealed elaborate mechanisms by which the virus interacts with its host cell as it inhibits the synthesis of cellular proteins, evades the innate antiviral response, and facilitates production of viral RNAs and proteins. With the advent of DNA array technology it is now possible to obtain a large-scale view of how viruses alter the environment within the host cell. In this study, the cellular response to influenza virus infection was examined by monitoring the steady-state mRNA levels for over 4,600 cellular genes. Infections with active and inactivated influenza viruses identified changes in cellular gene expression that were dependent on or independent of viral replication, respectively. Viral replication resulted in the downregulation of many cellular mRNAs, and the effect was enhanced with time postinfection. Interestingly, several genes involved in protein synthesis, transcriptional regulation, and cytokine signaling were induced by influenza virus replication, suggesting that some may play essential or accessory roles in the viral life cycle or the host cell's stress response. The gene expression pattern induced by inactivated viruses revealed induction of the cellular metallothionein genes that may represent a protective response to virus-induced oxidative stress. Genome-scale analyses of virus infections will help us to understand the complexities of virus-host interactions and may lead to the discovery of novel drug targets or antiviral therapies.Although it has been nearly 7 decades since the isolation of human influenza virus (34), it remains a world health threat with large economic consequences (28, 43, 52). Although vaccine and drug strategies have managed to contain the spread of the disease and the severity of its symptoms, recent outbreaks, such as the one in Hong Kong in 1997, emphasize the need for continued research efforts for influenza prevention. An abundant but often overlooked source of potential antiviral targets are those cellular genes whose expression is most affected by viral infection. With DNA microarray technology it is now possible to measure the mRNA levels of thousands of cellular genes under a variety of experimental conditions. This approach is increasingly being used to monitor cellular gene expression in response to viral infections (5,19,20,25,30,55,59), expression of viral genes (21, 31, 58), or treatment with antiviral compounds such as interferon (12).Influenza virus is a negative-stranded RNA virus that induces a profound inhibitory effect on the synthesis of cellular proteins. Much of this effect occurs at a posttranscriptional level, as viral RNAs are selectively translated while the initiation and elongation of cellular proteins are inhibited (15). On the other hand, viral proteins carry out a variety of functions within the nucleus, such as removing 5Ј methyl caps from host cell mRNAs (50), blocking ...

Section: Vol 75 2001 Microarray Analysis Of Influenza Virus Infectisupporting

confidence: 88%

Global Impact of Influenza Virus on Cellular Pathways Is Mediated by both Replication-Dependent and -Independent Events

Geiss¹,

Bumgarner

et al. 2001

114

“…Confluent primary human lung endothelial monolayers were infected with an H3N2 subtype of influenza A virus (X31) for 24 h; we and others have previously reported that human influenza is capable of infecting and replicating in human endothelial cells both in vitro (13,31,32) and in vivo (7). This was followed by incubation with purified calcein-labeled human platelets.…”

Section: Resultsmentioning

confidence: 99%

Influenza Virus Infection Induces Platelet-Endothelial Adhesion Which Contributes to Lung Injury

Sugiyama

Gamage

Zyla

et al. 2016

Lung injury after influenza infection is characterized by increased permeability of the lung microvasculature, culminating in acute respiratory failure. Platelets interact with activated endothelial cells and have been implicated in the pathogenesis of some forms of acute lung injury. Autopsy studies have revealed pulmonary microthrombi after influenza infection, and epidemiological studies suggest that influenza vaccination is protective against pulmonary thromboembolism; however, the effect of influenza infection on platelet-endothelial interactions is unclear. We demonstrate that endothelial infection with both laboratory and clinical strains of influenza virus increased the adhesion of human platelets to primary human lung microvascular endothelial cells. Platelets adhered to infected cells as well as to neighboring cells, suggesting a paracrine effect. Influenza infection caused the upregulation of von Willebrand factor and ICAM-1, but blocking these receptors did not prevent platelet-endothelial adhesion. Instead, platelet adhesion was inhibited by both RGDS peptide and a blocking antibody to platelet integrin ␣ 5 ␤ 1 , implicating endothelial fibronectin. Concordantly, lung histology from infected mice revealed viral dose-dependent colocalization of viral nucleoprotein and the endothelial marker PECAM-1, while platelet adhesion and fibronectin deposition also were observed in the lungs of influenza-infected mice. Inhibition of platelets using acetylsalicylic acid significantly improved survival, a finding confirmed using a second antiplatelet agent. Thus, influenza infection induces platelet-lung endothelial adhesion via fibronectin, contributing to mortality from acute lung injury. The inhibition of platelets may constitute a practical adjunctive strategy to the treatment of severe infections with influenza. Here, we show that this infection causes platelets to adhere to the lung endothelium. Importantly, blocking platelets using two distinct antiplatelet drugs improved survival in a mouse model of severe influenza infection. Thus, platelet inhibition may constitute a novel therapeutic strategy to improve the host response to severe infections with influenza.

“…hCMV antigens are found in EC in inflammatory pathologies, such as atherosclerosis (2) and inflammatory bowel disease (3), but the role of the virus in their development remains highly controversial. Studies report that hCMV induces production of the EC proinflammatory mediators interleukin 8 (IL-8) (4,5) and IL-6 (6) and expression of the leukocyte adhesion receptor ICAM-1 (7,8). In addition, reports have shown that hCMV-infected EC (hCMV-EC) supported enhanced leukocyte recruitment (5,(9)(10)(11).…”

mentioning

confidence: 99%

Human Cytomegalovirus Induces a Biphasic Inflammatory Response in Primary Endothelial Cells

Jeffery

Söderberg‐Nauclér

Butler

2013

Contradictory studies report either pro-or anti-inflammatory endothelial cell (EC) responses to human cytomegalovirus (hCMV) infection, hindering the validation of a potential link between this virus and associated inflammatory pathologies. Clarifying this issue, we report that hCMV induces a biphasic response. Early after inoculation, hCMV promoted lymphocyte and, to a lesser extent, neutrophil capture under in vivo relevant shear stresses. In contrast, later stages of infection rendered EC refractory to basal, or cytokine-induced, leukocyte recruitment. E ndothelial cells (EC), the master regulators of leukocyte extravasation, are critical sites of human cytomegalovirus (hCMV) infection in vivo (for a review, see reference 1). hCMV antigens are found in EC in inflammatory pathologies, such as atherosclerosis (2) and inflammatory bowel disease (3), but the role of the virus in their development remains highly controversial. Studies report that hCMV induces production of the EC proinflammatory mediators interleukin 8 (IL-8) (4, 5) and IL-6 (6) and expression of the leukocyte adhesion receptor ICAM-1 (7, 8). In addition, reports have shown that hCMV-infected EC (hCMV-EC) supported enhanced leukocyte recruitment (5, 9-11). These heavily cited studies, particularly those demonstrating a role for hCMV-induced IL-8 in neutrophil transmigration (4, 5), support the idea that hCMV contributes to the development or exacerbation of inflammatory pathologies. However, these same studies used static adhesion assays involving prolonged coculture of leukocytes with hCMV-EC or hCMV-EC supernatants before quantification of recruitment. Thus, these systems circumvent components of the leukocyte recruitment paradigm that are critical in vivo, i.e., initial capture from flowing blood and rolling on the EC surface (for a review, see reference 12). Therefore, these results do not determine if hCMV-EC can induce leukocyte recruitment under vascular shear forces. Nevertheless, investigators have shown that hCMV can induce EC VCAM-1 and E-selectin expression, important capture receptors involved in leukocyte tethering from blood flow (11), implying that hCMV-mediated recruitment could occur under shear forces. These results, however, contradict an earlier study that claimed hCMV induces no such increase (8). Furthermore, other data indicate that hCMV renders EC refractory to cytokine-mediated adhesion molecule induction (8) and IL-8 secretion (13), suggesting that hCMV can induce an antiinflammatory phenotype, although there are no reports of the subsequent effects on leukocyte recruitment. Here, we addressed these contradictions in the literature by examining the ability of hCMV to induce a pro-or anti-inflammatory EC phenotype. Importantly, we examined the functional relevance of infection by studying leukocyte recruitment under shear stress in an in vivo relevant flow-based recruitment assay. We found that hCMV induced a biphasic inflammation response, which may explain many of the inconsistencies in the current literature and also h...