Biomedical subjects

Robert W Finberg

Publications and source records attributed to Robert W Finberg.

At least 19 recordsLinked to original sources

PubMed2006

Flavivirus activation of plasmacytoid dendritic cells delineates key elements of TLR7 signaling beyond endosomal recognition.

TLR7 senses RNA in endosomal compartments. TLR7 expression and signaling have been demonstrated in plasmacytoid and myeloid dendritic cells, B cells, and T cells. The regulation of TLR7 signaling can play a crucial role in shaping the immune response to RNA viruses with different cellular tropisms, and in developing adjuvants capable of promoting balanced humoral and cell-mediated immunity. We used unique characteristics of two ssRNA viruses, dengue virus and influenza virus, to delineate factors that regulate viral RNA-human TLR7 signaling beyond recognition in endosomal compartments. Our data show that TLR7 recognition of enveloped RNA virus genomes is linked to virus fusion or uncoating from the endosome. The signaling threshold required to activate TLR7-type I IFN production is greater than that required to activate TLR7-NF-kappaB-IL-8 production. The higher order structure of viral RNA appears to be an important determinant of TLR7-signaling potency. A greater understanding of viral RNA-TLR7 activity relationships will promote rational approaches to interventional and vaccine strategies for important human viral pathogens.

Adult↗

PubMed2006

CD14: chaperone or matchmaker?

In this issue of Immunity, describe a physical and functional relationship between Toll-like receptor 3 (TLR3) and the pattern recognition protein CD14. In the presence of CD14, TLR3-mediated signal transduction events are amplified.

Adaptor Proteins, Signal Transducing↗

PubMed2006

Role for TLR2 in NK cell-mediated control of murine cytomegalovirus in vivo.

Natural killer (NK) cells are essential for the early control of murine cytomegalovirus (MCMV) infection. Here, we demonstrate that toll-like receptor 2 (TLR2) plays a role in the NK cell-mediated control of MCMV. TLR2 knockout (KO) mice had elevated levels of MCMV in the spleen and liver on day 4 postinfection compared to C57BL/6 mice. In vivo depletion of NK cells with anti-NK1.1 antibodies, however, eliminated the differences in viral titers between the two groups, suggesting that the effect of TLR2 on MCMV clearance on day 4 was NK cell mediated. The defect in early antiviral control was associated with a decreased NK cell population in the spleen and liver and reduced amounts of interleukin-18 and alpha/beta interferon secreted in the TLR2 KO mice. Our studies suggest that in addition to the reported involvement of TLR9 and TLR3, TLR2 is also involved in innate immune responses to MCMV infection.

Animals↗

PubMed2005

The erythrocyte viral trap: transgenic expression of viral receptor on erythrocytes attenuates coxsackievirus B infection.

Viruses rely on attachment to specific cell surface receptors to infect host cells. Selective expression of viral receptors has the potential to attenuate infection of susceptible tissues by redirecting virus to cells that cannot support viral replication. We propose that erythrocytes are an ideal instrument for this strategy, because they are present in vast numbers, permeate every organ, and cannot serve as hosts for viral propagation. To test this hypothesis, we generated a transgenic mouse, termed globin transcription factor 1 (GATA1)-coxsackie and adenovirus receptor (CAR), that expressed the CAR on erythrocytes. Coxsackievirus group B (CVB) adhered to the surface of CAR-expressing erythrocytes and was rendered noninfectious. Upon infection with CVB, GATA1-CAR mice had diminished viremia and reduced viral replication in heart, brain, and liver. Furthermore, when faced with a CVB challenge that was lethal to WT littermates, the survival of GATA1-CAR mice was prolonged, and their ultimate mortality was reduced. The GATA1-CAR mouse model presented here demonstrates that erythrocyte expression of CAR limits CVB pathogenesis. Erythrocytes also may be coated with a variety of receptors by nontransgenic methods, making this a very flexible model for the treatment of infectious diseases in humans.

Animals↗

PubMed2005

Negative regulation of Toll-like receptor 4 signaling by the Toll-like receptor homolog RP105.

Activation of Toll-like receptor (TLR) signaling by microbial signatures is critical to the induction of immune responses. Such responses demand tight regulation. RP105 is a TLR homolog thought to be mostly B cell specific, lacking a signaling domain. We report here that RP105 expression was wide, directly mirroring that of TLR4 on antigen-presenting cells. Moreover, RP105 was a specific inhibitor of TLR4 signaling in HEK 293 cells, a function conferred by its extracellular domain. Notably, RP105 and its helper molecule, MD-1, interacted directly with the TLR4 signaling complex, inhibiting its ability to bind microbial ligand. Finally, RP105 regulated TLR4 signaling in dendritic cells as well as endotoxin responses in vivo. Thus, our results identify RP105 as a physiological negative regulator of TLR4 responses.

Animals↗

PubMed2005

The role of toll-like receptors in herpes simplex infection in neonates.

Toll-like receptors (TLRs)--and their associated signal-transducing proteins--on the surface of cells have been demonstrated to account for most, if not all, of the events associated with bacterial sepsis. Using human cells expressing different TLRs, we demonstrated that the interaction between TLR2 and herpes simplex virus (HSV)-1-2 leads to the production of cytokines. Using peripheral-blood mononuclear cells, we tested the ability of cells from people of different age groups to make cytokines in response to HSV. An examination of the host responses of neonates to HSV indicates that, rather than producing less interleukin-6 and interleukin-8 in response to HSV than adults do, neonates produce more of these cytokines than adults do. This may explain the sepsis syndrome that is seen with HSV (and other virus infections) in neonates.

Adult↗

PubMed2005

Development and characterization of a severe acute respiratory syndrome-associated coronavirus-neutralizing human monoclonal antibody that provides effective immunoprophylaxis in mice.

BACKGROUND: Severe acute respiratory syndrome (SARS) remains a significant public health concern after the epidemic in 2003. Human monoclonal antibodies (MAbs) that neutralize SARS-associated coronavirus (SARS-CoV) could provide protection for exposed individuals. METHODS: Transgenic mice with human immunoglobulin genes were immunized with the recombinant major surface (S) glycoprotein ectodomain of SARS-CoV. Epitopes of 2 neutralizing MAbs derived from these mice were mapped and evaluated in a murine model of SARS-CoV infection. RESULTS: Both MAbs bound to S glycoprotein expressed on transfected cells but differed in their ability to block binding of S glycoprotein to Vero E6 cells. Immunoprecipitation analysis revealed 2 antibody-binding epitopes: one MAb (201) bound within the receptor-binding domain at aa 490-510, and the other MAb (68) bound externally to the domain at aa 130-150. Mice that received 40 mg/kg of either MAb prior to challenge with SARS-CoV were completely protected from virus replication in the lungs, and doses as low as 1.6 mg/kg offered significant protection. CONCLUSIONS: Two neutralizing epitopes were defined for MAbs to SARS-CoV S glycoprotein. Antibodies to both epitopes protected mice against SARS-CoV challenge. Clinical trials are planned to test MAb 201, a fully human MAb specific for the epitope within the receptor-binding region.

Animals↗

PubMed2005

MyD88 is critical for the development of innate and adaptive immunity during acute lymphocytic choriomeningitis virus infection.

We investigated the roles of Toll-like receptor 2 (TLR2) and myeloid differentiation factor 88 (MyD88) in the course of a lymphocytic choriomeningitis virus (LCMV) infection and revealed the following: (i) studies of transfected cells and murine peritoneal macrophages demonstrated that TLR2 and MyD88 are essential for the initial pro-inflammatory cytokine response (human IL-8, mouse IL-6) to LCMV; (ii) TLR2 knockout (KO) mice and MyD88 KO mice challenged with LCMV produced less IL-6 and monocyte chemotactic protein-1 in the serum than wild-type mice; (iii) in contrast to inflammatory cytokines, the production of type 1 IFN (IFN-alpha) in response to LCMV was MyD88 independent; (iv) MyD88 plays an essential role in antiviral CD8(+) T cell responses, CD8(+) T cells in MyD88 KO mice were defective in their expression of intracellular antiviral cytokines; and (v) the failure of MyD88 KO mice to activate CD8(+) T cells was accompanied by persistent viral infection in MyD88 KO mice. We demonstrate that TLR-mediated responses are important in the innate immune response to LCMV and that MyD88 is essential for the control of the LCMV infection and the maturation/activation of virus-specific CD8(+) T cells.

Adaptor Proteins, Signal Transducing↗

PubMed2005

Coxsackievirus and adenovirus receptor is essential for cardiomyocyte development.

The coxsackievirus and adenovirus receptor (CAR) is a transmembrane protein that is known to be a site of viral attachment and entry, but its physiologic functions are undefined. CAR expression is maximal in neonates and wanes rapidly after birth in organs such as heart, muscle, and brain, suggesting that CAR plays a role in the development of these tissues. Here, we show that CAR deficiency resulted in an embryonic lethal condition associated with cardiac defects. Specifically, commencing approximately 10.5 days postconception (dpc), CAR-/- cardiomyocytes exhibited regional apoptosis evidenced by both histopathologic features of cell death and positive staining for the apoptotic marker cleaved caspase 3. CAR-/- fetuses invariably suffered from degeneration of the myocardial wall and thoracic hemorrhaging, leading to death by 11.5 dpc. These findings are consistent with the view that CAR provides positive survival signals to cardiomyocytes that are essential for normal heart development.

Animals↗

PubMed2005

Herpes simplex virus and toll-like receptors.

The earliest interactions between viruses and host cells are critical to determining the outcome of infections. The interactions between a virus and its host cells that lead to the production of inflammatory cytokines are essential to the development of T cells and antibodies that provide long-term defense against the invaders. At the same time, however, these same cytokines (or sometimes other mediators or chemokines) stimulate inflammation, which may lead to localized tissue damage and/or systemic circulatory collapse and death. This review focuses on the interaction between Toll-like receptors, a critical component of the innate immune system of mammals, and their role in herpes simplex pathogenesis and immunity.

Animals↗

PubMed2005

Varicella-zoster virus activates inflammatory cytokines in human monocytes and macrophages via Toll-like receptor 2.

The pattern recognition receptor Toll-like receptor 2 (TLR2) has been implicated in the response to several human viruses, including herpes simplex viruses (types 1 and 2) and cytomegalovirus. We demonstrated that varicella-zoster virus (VZV) activates inflammatory cytokine responses via TLR2. VZV specifically induced interleukin-6 (IL-6) in human monocytes via TLR2-dependent activation of NF-kappaB, and small interfering RNA designed to suppress TLR2 mRNA reduced the IL-6 response to VZV in human monocyte-derived macrophages. Unlike other herpesviruses, the cytokine response to VZV was species specific. VZV did not induce cytokines in murine embryonic fibroblasts or in a mouse cell line, although VZV did activate NF-kappaB in a human cell line expressing a murine TLR2 construct. Together, these results suggest that TLR2 may play a role in the inflammatory response to VZV infection.

Animals↗

PubMed2005

Inhibition of TLR-4/MD-2 signaling by RP105/MD-1.

Activation of Toll-like receptor (TLR) signaling by microbial and host molecular signatures is critical to the induction of immune responses. Such signaling is, perforce, kept under tight control. We recently discovered a novel endogenous inhibitor of TLR-4 - RP105. Initially identified as a B-cell-specific molecule with a role in B-cell proliferation in response to RP105 mAb and LPS, RP105 is a TLR-4 homologue. Further, like TLR-4 whose surface expression and signaling depends upon co-expression of the secreted protein MD-2, surface expression of RP105 is dependent upon co-expression of the MD2 homologue, MD-1. Unlike the TLRs, however, RP105 lacks a signaling domain, having the apparent structure of a TLR inhibitor. Further, RP105 is not B-cell-specific; its expression directly mirrors that of TLR-4 on dendritic cells and macrophages. These considerations suggested a role for RP105 as a physiological inhibitor of TLR-4 signaling. Indeed, we have recently found that: (i) RP105 is a specific inhibitor of TLR-4 signaling in HEK293 cells; (ii) RP105/MD-1 interacts directly with TLR-4/MD-2, inhibiting the ability of this signaling complex to bind LPS; (iii) RP105 regulates TLR-4 signaling in dendritic cells and macrophages; and (iv) RP105 regulates in vivo responses to LPS.

Animals↗

PubMed2004

The importance of bactericidal drugs: future directions in infectious disease.

BACKGROUND: Although a considerable amount of research has gone into the study of the role of bactericidal versus bacteriostatic antimicrobial agents in the treatment of different infectious diseases, there is no accepted standard of practice. METHODS: A panel of infectious diseases specialists reviewed the available literature to try to define specific recommendations for clinical practice. RESULTS: In infections of the central nervous system, the rapidity with which the organism is killed may be an important determinant, because of the serious damage that may occur during these clinical situations. The failure of bacteriostatic antibiotics to adequately treat endocarditis is well documented, both in human studies and in animal models. CONCLUSION: The bulk of the evidence supports the concept that, in treating endocarditis and meningitis, it is important to use antibacterial agents with in vitro bactericidal activity. This conclusion is based on both human and animal data. The data to support bactericidal drugs' superiority to bacteriostatic drugs do not exist for most other clinical situations, and animal models do not support this concept in some situations. Clinicians should be aware that drugs that are bacteriostatic for one organism may in fact be bactericidal for another organism or another strain of the same organism.

Animals↗

PubMed2004

CD109 represents a novel branch of the alpha2-macroglobulin/complement gene family.

We report here the genomic organization and phylogenic relationships of CD109, a member of the the alpha2-macroglobulin/complement (AMCOM) gene family. CD109 is a GPI-linked glycoprotein expressed on endothelial cells, platelets, activated T-cells, and a wide variety of tumors. We cloned full-length CD109 cDNA from the mammalian U373 cell line by RT-PCR and performed analysis of its corresponding genomic sequence. The CD109 cDNA spans 128 kb of chromosome 6q with its 33 exons constituting approximately 3.3% of the total CD109 genomic sequence. Sequence analysis revealed that CD109 contains specific motifs in its N-terminus, that are highly conserved in all AMCOM members. CD109 also shares motifs with certain other AMCOM members including: (1) a thioester 'GCGEQ" motif, (2) a furin site of four positively charged amino acids, and (3) a double tyrosine near the C-terminus. Based on a phylogenic analysis of human CD109 with other human homologs as well as orthologs from other mammalian species, C. elegans (ZK337.1) and E. coli homologs, we propose CD109 represents a novel and independent branch of the alpha2-macroglobulin/complement gene family (AMCOM) and may be its oldest member.

Amino Acid Sequence↗

PubMed2004

Herpes simplex virus 1 interaction with Toll-like receptor 2 contributes to lethal encephalitis.

Human neonates infected with herpes simplex virus 1 (HSV-1) develop one of three distinct patterns of infection: (i) infection limited to the skin, eye or mouth; (ii) infection of the CNS; or (iii) disseminated infection. The disseminated form usually involves the liver, adrenal gland, and lung, and resembles the clinical picture of bacterial sepsis. This spectrum of symptoms in HSV-1-infected neonates suggests that inflammatory cytokines play a significant role in the pathogenesis of the disease. Recent studies suggest that the Toll-like receptors (TLRs) may play an important role in the induction of inflammatory cytokines in response to viruses. TLRs are mammalian homologues of Toll, a Drosophila protein that is essential for host defense against infection. Engagement of TLRs by bacterial, viral, or fungal components leads to the production and release of cytokines and other antimicrobial products. Here, we demonstrate that TLR2 mediates the inflammatory cytokine response to HSV-1 by using both transfected cell lines and knockout mice. Studies of infected mice revealed that HSV-1 induced a blunted cytokine response in TLR2(-/-) mice. Brain levels of monocyte chemoattractant protein 1 chemokine were significantly lower in TLR2(-/-) mice than in either wild-type or TLR4(-/-) mice. TLR2(-/-) mice had reduced mortality compared with wild-type mice. The differences between TLR2(-/-) mice and both wild-type and TLR4(-/-) mice in the induction of monocyte chemoattractant protein 1, brain inflammation, or mortality could not be accounted for on the basis of virus levels. Thus, these studies suggest the TLR2-mediated cytokine response to HSV-1 is detrimental to the host.

Animals↗

PubMed2004

Viruses and Toll-like receptors.

Production of inflammatory cytokines and type I interferons by mammalian cells is mediated through virus-specific activation of Toll-like receptors (TLRs). Known roles for different TLRs and speculation as to their roles in viral pathogenesis and immunity are discussed in this review.

Animals↗

PubMed2004

Hepatitis C core and nonstructural 3 proteins trigger toll-like receptor 2-mediated pathways and inflammatory activation.

BACKGROUND AND AIMS: Recent evidence suggests that toll-like receptors (TLRs) recognize certain viruses. We reported that hepatitis C virus (HCV) core and nonstructural 3 (NS3) proteins activate inflammatory pathways in monocytes. The aim of this study was to investigate the role of TLRs in innate immune cell activation by core and NS3 proteins. METHODS: Human monocytes, human embryonic kidney cells transfected with TLR2, and peritoneal macrophages from TLR2, MyD88 knockout, and wild-type mice were studied to determine intracellular signaling and proinflammatory cytokine induction by HCV proteins. RESULTS: HCV core and NS3 proteins triggered inflammatory cell activation via the pattern recognition receptor TLR2 and failed to activate macrophages from TLR2 or MyD88-deficient mice. HCV core and NS3 induced interleukin (IL)-1 receptor-associated kinase (IRAK) activity, phosphorylation of p38, extracellular regulated (ERK), and c-jun N-terminal (JNK) kinases and induced AP-1 activation. Activation of nuclear factor-kappaB by core and NS3 was associated with increased IkappaBalpha phosphorylation. TLR2-mediated cell activation was dependent on the conformation of core and NS3 proteins and required sequences in the regions of aa 2-122 in core and aa 1450-1643 in NS3. Although cellular uptake of core and NS3 proteins was independent of TLR2 expression, cell activation required TLR2. HCV core protein and TLR2 showed intracellular colocalization. The hyper-elevated TNF-alpha induction by TLR2 ligands in monocytes of HCV-infected patients was not due to increased TLR2 expression. CONCLUSIONS: HCV core and NS3 proteins trigger inflammatory pathways via TLR2 that may affect viral recognition and contribute to activation of the innate immune system.

Animals↗

PubMed2004

Cell activation by Toll-like receptors: role of LBP and CD14.

Members of the Toll-like receptor (TLR) family have been shown to be important in the activation of cells by a variety of microbial ligands. TLRs are thought to mediate the 'recognition event' that follows an encounter between a mammalian cell and a microbial agent. In the case of the response to bacterial lipopolysaccharide (LPS), it is clear that the ability of these cell surface proteins to initiate the events necessary for activation of cells to produce cytokines is dependent upon 'accessory proteins' such as the pattern recognition protein CD14 and the lipopolysaccharide binding protein (LBP). While the role of these proteins in the LPS-specific response is defined, their role in other TLR responses has not been defined, but it is important in understanding these events and, potentially, in designing new therapeutic strategies. Here we report on the role of these proteins in the response to yeast zymosan. The requirements for this response (which unlike the response to LPS is a response to a particulate antigen) and the role of other serum proteins are defined.

Acute-Phase Proteins↗