scholarly journals Ebola Virus Glycoprotein Toxicity Is Mediated by a Dynamin-Dependent Protein-Trafficking Pathway

2005 ◽  
Vol 79 (1) ◽  
pp. 547-553 ◽  
Author(s):  
Nancy J. Sullivan ◽  
Mary Peterson ◽  
Zhi-yong Yang ◽  
Wing-pui Kong ◽  
Heinricus Duckers ◽  
...  

ABSTRACT Ebola virus infection causes a highly lethal hemorrhagic fever syndrome associated with profound immunosuppression through its ability to induce widespread inflammation and cellular damage. Though GP, the viral envelope glycoprotein, mediates many of these effects, the molecular events that underlie Ebola virus cytopathicity are poorly understood. Here, we define a cellular mechanism responsible for Ebola virus GP cytotoxicity. GP selectively decreased the expression of cell surface molecules that are essential for cell adhesion and immune function. GP dramatically reduced levels of αVβ3 without affecting the levels of α2β1 or cadherin, leading to cell detachment and death. This effect was inhibited in vitro and in vivo by brefeldin A and was dependent on dynamin, the GTPase. GP also decreased cell surface expression of major histocompatibility complex class I molecules, which alters recognition by immune cells, and this effect was also dependent on the mucin domain previously implicated in GP cytotoxicity. By altering the trafficking of select cellular proteins, Ebola virus GP inflicts cell damage and may facilitate immune escape by the virus.

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
María Martínez-Esparza ◽  
Antonio José Ruiz-Alcaraz ◽  
Violeta Carmona-Martínez ◽  
María Dolores Fernández-Fernández ◽  
Gonzalo Antón ◽  
...  

Background and Aim. The presumed role of the inhibitory receptor LAIR-1 (CD305) in the inflammatory response suggests that it might contribute to the pathophysiology of chronic inflammatory diseases such as liver cirrhosis. We studied the LAIR-1 expression on liver macrophages and blood monocytes related to the progression of liver cirrhosis. Methods. The expression of LAIR-1 was analyzed by immunohistochemistry, flow cytometry, and Western blot. Results. We found a decreased number of macrophages expressing LAIR-1 in cirrhotic liver that could be due to a high presence of collagen, ligand of LAIR-1, in the fibrotic tissue which could downregulate its expression or interfere with the immunostaining. The expression of LAIR-1 decreased after cell differentiation, and the total content, but not the cell surface expression, increased after activation in the HL-60 human macrophage in vitro model. Blood monocytes exhibited higher LAIR-1 expression levels in cirrhotic patients, which were evident even in early clinical stages in all monocyte subsets, and greater in the “intermediate” inflammatory monocyte subpopulation. The in vitro activation of human blood monocytes did not increase its expression on the cell surface suggesting that the in vivo increase of LAIR-1 must be the result of a specific combination of stimuli present in cirrhotic patients. This represents an exclusive feature of liver cirrhosis, since blood monocytes from other chronic inflammatory pathologies showed similar or lower LAIR-1 levels compared with those of healthy controls. Conclusions. These results may indicate that monocyte LAIR-1 expression is a new biomarker to early detect liver damage caused by chronic inflammation in liver cirrhosis.


2008 ◽  
Vol 295 (1) ◽  
pp. G16-G26 ◽  
Author(s):  
Mubeen Jafri ◽  
Bryan Donnelly ◽  
Steven Allen ◽  
Alex Bondoc ◽  
Monica McNeal ◽  
...  

Inoculation of BALB/c mice with rhesus rotavirus (RRV) in the newborn period results in biliary epithelial cell (cholangiocyte) infection and the murine model of biliary atresia. Rotavirus infection of a cell requires attachment, which is governed in part by cell-surface expression of integrins such as α2β1. We hypothesized that cholangiocytes were susceptible to RRV infection because they express α2β1. RRV attachment and replication was measured in cell lines derived from cholangiocytes and hepatocytes. Flow cytometry was performed on these cell lines to determine whether α2β1 was present. Cholangiocytes were blocked with natural ligands, a monoclonal antibody, or small interfering RNA against the α2-subunit and were infected with RRV. The extrahepatic biliary tract of newborn mice was screened for the expression of the α2β1-integrin. Newborn mice were pretreated with a monoclonal antibody against the α2-subunit and were inoculated with RRV. RRV attached and replicated significantly better in cholangiocytes than in hepatocytes. Cholangiocytes, but not hepatocytes, expressed α2β1 in vitro and in vivo. Blocking assays led to a significant reduction in attachment and yield of virus in RRV-infected cholangiocytes. Pretreatment of newborn pups with an anti-α2 monoclonal antibody reduced the ability of RRV to cause biliary atresia in mice. Cell-surface expression of the α2β1-integrin plays a role in the mechanism that confers cholangiocyte susceptibility to RRV infection.


1996 ◽  
Vol 133 (1) ◽  
pp. 159-167 ◽  
Author(s):  
A Saada ◽  
F Reichert ◽  
S Rotshenker

Peripheral nerve injury is followed by Wallerian degeneration which is characterized by cellular and molecular events that turn the degenerating nerve into a tissue that supports nerve regeneration. One of these is the removal, by phagocytosis, of myelin that contains molecules which inhibit regeneration. We have recently documented that the scavenger macrophage and Schwann cells express the galactose-specific lectin MAC-2 which is significant to myelin phagocytosis. In the present study we provide evidence for a mechanism leading to the augmented expression of cell surface MAC-2. Nerve lesion causes noneuronal cells, primarily fibroblasts, to produce the cytokine granulocyte macrophage-colony stimulating factor (GM-CSF). In turn, GM-CSF induces Schwann cells and macrophages to up-regulate surface expression of MAC-2. The proposed mechanism is based on the following novel observations. GM-CSF mRNA was detected by PCR in in vitro and in vivo degenerating nerves, but not in intact nerves. The GM-CSF molecule was detected by ELISA in medium conditioned by in vitro and in vivo degenerating peripheral nerves as of the 4th h after injury. GM-CSF activity was demonstrated by two independent bioassays, and repressed by activity blocking antibodies. Significant levels of GM-CSF were produced by nerve derived fibroblasts, but neither by Schwann cells nor by nerve derived macrophages. Mouse rGM-CSF enhanced MAC-2 production in nerve explants, and up-regulated cell surface expression of MAC-2 by Schwann cells and macrophages. Interleukin-1 beta up-regulated GM-CSF production thus suggesting that injury induced GM-CSF production may be mediated by interleukin-1 beta. Our findings highlight the fact that fibroblasts, by producing GM-CSF and thereby affecting macrophage and Schwann function, play a significant role in the cascade of molecular events and cellular interactions of Wallerian degeneration.


Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 2789-2789
Author(s):  
Lindsey F Call ◽  
Sommer Castro ◽  
Thao T. Tang ◽  
Cynthia Nourigat-Mckay ◽  
LaKeisha Perkins ◽  
...  

Abstract Adoptive transfer of T cells engineered to express chimeric antigen receptors (CARs) has achieved impressive outcomes in the treatment of refractory/relapsed B-ALL, providing potentially curative treatment options for these patients. The use of CAR T in AML, however, is still in its infancy with limitations due to the innate heterogeneity associated with AML and the lack of AML-specific targets for therapeutic development. The CRLF2 gene encodes for thymic stromal lymphopoietin receptor (TSLPR) and has previously been shown to be highly upregulated in a subset of children and adults with B-ALL. Targeting TSLPR with CAR T cells demonstrates potent anti-leukemia activity against TSLPR-positive B-ALL (PMID 26041741). Through Target Pediatric AML (TpAML), we profiled the transcriptome of nearly 3000 children and young adults with AML and identified CRLF2 (TSLPR) to be highly expressed in a subset of AML, including the majority of AML harboring KM2TA (aka MLL) fusions. TSLPR cell surface expression was validated in primary patient samples using flow cytometry, which showed uniform expression of TSLPR on AML blasts. Given that TSLPR is expressed in AML with confirmed cell surface expression, we developed TSLPR-directed CAR T for preclinical evaluation in AML. We generated a TSLPR-directed CAR using the single-chain variable fragment (scFv) derived from an anti-TSLPR binder (clone 3G1, MD Anderson), IgG4 spacer and 41-BB/CD3zeta signaling domains. The in vitro cytotoxicity of TSLPR CAR T cells was evaluated against the REH-1 cell line and primary AML specimens. TSLPR CAR T cells demonstrated anti-leukemia activity against REH-1 as well as against primary AML specimens. To evaluate the in vivo efficacy of TSLPR CAR T cells, we developed a patient-derived xenograft (PDX) model using bone marrow cells from a TSLPR-positive patient. These cells provided a robust model system to evaluate the in vivo activity of TSLPR CAR T cells, as they produced an aggressive leukemia in humanized NSG-SGM3 mice. The PDX generated from these cells died within 2 months of transplant with significant leukemia infiltration into the bone marrow, liver, and spleen. In the in vivo study, the leukemia burden was assessed by flow cytometric analysis of AML cells in the peripheral blood and bone marrow aspirates following treatment with unmodified control or TSLPR CAR T cells given at 10x10 6 T cells per mouse. After CAR T treatment, we detected a significant decrease in leukemia infiltration into the peripheral blood and bone marrow in the CAR T-treated mice compared to mice that received unmodified T cells. In this study, we report that similar to B-ALL, CRLF2 (TSLPR) is overexpressed in a subset of AML, providing a strategy to eliminate AML cells with CAR T cell therapy. We validated the cell surface expression of TSLPR and showed that the expression is uniform across AML specimens. We further demonstrate that CAR T cells targeting TSLPR were effective in eliminating AML cells in vitro and in vivo. Given that TSLPR is highly expressed in the KMT2A-rearranged AML, a subtype that is associated with poor outcomes, TSLPR-directed CAR T cells represent a promising immunotherapy for this high-risk AML subset. Disclosures Pardo: Hematologics, Inc.: Current Employment.


Blood ◽  
2003 ◽  
Vol 102 (6) ◽  
pp. 2173-2179 ◽  
Author(s):  
Martha J. James ◽  
Lavina Belaramani ◽  
Kanella Prodromidou ◽  
Arpita Datta ◽  
Sussan Nourshargh ◽  
...  

Abstract Due to their ability to inhibit antigen-induced T-cell activation in vitro and in vivo, anergic T cells can be considered part of the spectrum of immunoregulatory T lymphocytes. Here we report that both murine and human anergic T cells can impair the ability of parenchymal cells (including endothelial and epithelial cells) to establish cell-cell interactions necessary to sustain leukocyte migration in vitro and tissue infiltration in vivo. The inhibition is reversible and cell-contact dependent but does not require cognate recognition of the parenchymal cells to occur. Instrumental to this effect is the increased cell surface expression and enzymatic activity of molecules such as CD26 (dipeptidyl-peptidase IV), which may act by metabolizing chemoattractants bound to the endothelial/epithelial cell surface. These results describe a previously unknown antigen-independent anti-inflammatory activity by locally generated anergic T cells and define a novel mechanism for the long-known immunoregulatory properties of these cells.


2021 ◽  
Author(s):  
Rebecca I. Johnson ◽  
Beata Boczkowska ◽  
Kendra Alfson ◽  
Taylor Weary ◽  
Heather Menzie ◽  
...  

Ebola virus (EBOV), of the family Filoviridae, is an RNA virus that can cause hemorrhagic fever with a high mortality rate. Defective viral genomes (DVGs) are truncated genomes that have been observed during multiple RNA virus infections, including  in vitro EBOV infection, and have previously been associated with viral persistence and immunostimulatory activity. As DVGs have been detected in cells persistently infected with EBOV, we hypothesized that DVGs may also accumulate during viral replication in filovirus-infected hosts. Therefore, we interrogated sequence data from serum and tissues using a bioinformatics tool in order to identify the presence of DVGs in nonhuman primates (NHPs) infected with EBOV, Sudan virus (SUDV) or Marburg virus (MARV). Multiple 5’ copy-back DVGs (cbDVGs) were detected in NHP serum during the acute phase of filovirus infection. While the relative abundance of total DVGs in most animals was low, serum collected during acute EBOV and SUDV infections, but not MARV infection, contained a higher proportion of short trailer sequence cbDVGs than the challenge stock. This indicated an accumulation of these DVGs throughout infection, potentially due to the preferential replication of short DVGs over the longer viral genome. Using RT-PCR and deep sequencing, we also confirmed the presence of 5’ cbDVGs in EBOV-infected NHP testes, which is of interest due to EBOV persistence in semen of male survivors of infection. This work suggests that DVGs play a role in EBOV infection in vivo and further study will lead to a better understanding of EBOV pathogenesis. Importance The study of filovirus pathogenesis is critical for understanding the consequences of infection and the development of strategies to ameliorate future outbreaks. Defective viral genomes (DVGs) have been detected during EBOV infections in vitro , however their presence in in vivo infections remains unknown. In this study, DVGs were detected in samples collected from EBOV- and SUDV-infected nonhuman primates (NHPs). The accumulation of these DVGs in the trailer region of the genome during infection indicates a potential role in EBOV and SUDV pathogenesis. In particular, the presence of DVGs in the testes of infected NHPs requires further investigation as it may be linked to the establishment of persistence.


2005 ◽  
Vol 15 (1) ◽  
pp. 1-12 ◽  
Author(s):  
V. Apaire-Marchais ◽  
J. Cottin ◽  
A. Marot-Leblond ◽  
C. Lefrançois ◽  
G. Tronchin ◽  
...  

2014 ◽  
Vol 89 (5) ◽  
pp. 2530-2542 ◽  
Author(s):  
Harry H. Matundan ◽  
Kevin R. Mott ◽  
Aslam Abbasi Akhtar ◽  
Joshua J. Breunig ◽  
Homayon Ghiasi

ABSTRACTTo investigate the role of the signal sequences of herpes simplex virus 1 (HSV-1) gK on virus replication and viral pathogenesis, we constructed recombinant viruses with or without mutations within the signal sequences of gK. These recombinant viruses expressed two additional copies of the mutated (MgK) or native (NgK) form of the gK gene in place of the latency-associated transcript with a myc epitope tag to facilitate detection at their 3′ ends. The replication of MgK virus was similar to that of NgK bothin vitroandin vivo, as well as in the trigeminal ganglia (TG) of latently infected mice. The levels of gB and gK transcripts in the corneas, TG, and brains of infected mice on days 3 and 5 postinfection were markedly virus and time dependent, as well as tissue specific. Mutation in the signal sequence of gK in MgK virus blocked cell surface expression of gK-myc in rabbit skin cells, increased 50% lethal dose, and decreased corneal scarring in ocularly infected mice compared to the NgK or revertant (RgK) virus. MgK and NgK viruses, and not the RgK virus, showed a reduced extent of explant reactivation at the lower dose of ocular infection but not at the higher dose. However, the time of reactivation was not affected by overexpression of the different forms of gK. Taken together, these results strongly suggest that the 8mer peptide (ITAYGLVL) within the signal sequence of gK promotes cell surface expression of gK in infected cells and ocular pathogenesis in infected mice.IMPORTANCEIn this study, we show for the first time that mutations within the signal sequence of gK blocked cell surface expression of inserted recombinant gKin vitro. Furthermore, this blockage in cell surface expression was correlated with higher 50% lethal dose and less corneal scarringin vivo. Thus, these studies point to a key role for the 8mer within the signal sequence of gK in HSV-1-induced pathogenicity.


2015 ◽  
Vol 89 (17) ◽  
pp. 8945-8956 ◽  
Author(s):  
Alix de Brogniez ◽  
Amel Baya Bouzar ◽  
Jean-Rock Jacques ◽  
Jean-Philippe Cosse ◽  
Nicolas Gillet ◽  
...  

ABSTRACTViruses have coevolved with their host to ensure efficient replication and transmission without inducing excessive pathogenicity that would indirectly impair their persistence. This is exemplified by the bovine leukemia virus (BLV) system in which lymphoproliferative disorders develop in ruminants after latency periods of several years. In principle, the equilibrium reached between the virus and its host could be disrupted by emergence of more pathogenic strains. Intriguingly but fortunately, such a hyperpathogenic BLV strain was never observed in the field or designedin vitro. In this study, we sought to understand the role of envelope N-linked glycosylation with the hypothesis that this posttranslational modification could either favor BLV infection by allowing viral entry or allow immune escape by using glycans as a shield. Using reverse genetics of an infectious molecular provirus, we identified a N-linked envelope glycosylation site (N230) that limits viral replication and pathogenicity. Indeed, mutation N230E unexpectedly leads to enhanced fusogenicity and protein stability.IMPORTANCEInfection by retroviruses requires the interaction of the viral envelope protein (SU) with a membrane-associated receptor allowing fusion and release of the viral genomic RNA into the cell. We show that N-linked glycosylation of the bovine leukemia virus (BLV) SU protein is, as expected, essential for cell infectionin vitro. Consistently, mutation of all glycosylation sites of a BLV provirus destroys infectivityin vivo. However, single mutations do not significantly modify replicationin vivo. Instead, a particular mutation at SU codon 230 increases replication and accelerates pathogenesis. This unexpected observation has important consequences in terms of disease control and managing.


Blood ◽  
2013 ◽  
Vol 122 (3) ◽  
pp. 394-404 ◽  
Author(s):  
Jessica Matta ◽  
Myriam Baratin ◽  
Laurent Chiche ◽  
Jean-Marie Forel ◽  
Céline Cognet ◽  
...  

Key Points B7-H6 transcripts, B7-H6 cell-surface expression, and sB7-H6 can be induced in inflammatory conditions in vitro and in vivo. B7-H6 is expressed on proinflammatory CD14+CD16+ monocytes in sepsis conditions and is linked to an increased mortality.


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