ABSTRACT
IMPORTANCE: The present study provides a substantial contribution to literature, showing that patients with enterococcal bloodstream infections (BSI) have a lower survival rate than those with Escherichia coli (E. coli) bloodstream infections after adjusting for 17 limiting prognostic factors and excluding patients with a limited life expectancy [metastatic tumor disease, Charlson Comorbidity Index (CCI) (greater than or equal to) 5]. This difference in the 5-year long-term survival was mainly driven by Enterococcus faecium (ECFM) bloodstream infections, with vancomycin resistance not being a significant contributing factor. Our findings imply that E. faecium bloodstream infections seem to be an independent risk factor for poor long-term outcomes. As such, future research should confirm this relationship and prioritize investigating its causality through prospective studies.
Subject(s)
Bacteremia , Escherichia coli Infections , Gram-Positive Bacterial Infections , Sepsis , Humans , Enterococcus , Prospective Studies , Escherichia coli , Bacteremia/epidemiology , Gram-Positive Bacterial Infections/diagnosis , Gram-Positive Bacterial Infections/epidemiology , Risk Factors , Escherichia coli Infections/epidemiology , Patient Acuity , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/therapeutic useABSTRACT
The human tumor viruses Epstein-Barr virus (EBV) and Kaposi sarcoma-associated herpesvirus (KSHV) establish persistent infections in B cells. KSHV is linked to primary effusion lymphoma (PEL), and 90% of PELs also contain EBV. Studies on persistent KSHV infection in vivo and the role of EBV co-infection in PEL development have been hampered by the absence of small animal models. We developed mice reconstituted with human immune system components as a model for KSHV infection and find that EBV/KSHV dual infection enhanced KSHV persistence and tumorigenesis. Dual-infected cells displayed a plasma cell-like gene expression pattern similar to PELs. KSHV persisted in EBV-transformed B cells and was associated with lytic EBV gene expression, resulting in increased tumor formation. Evidence of elevated lytic EBV replication was also found in EBV/KSHV dually infected lymphoproliferative disorders in humans. Our data suggest that KSHV augments EBV-associated tumorigenesis via stimulation of lytic EBV replication.
Subject(s)
Coinfection , Gene Expression Regulation, Viral , Herpesvirus 4, Human/genetics , Herpesvirus 4, Human/pathogenicity , Herpesvirus 8, Human/physiology , Herpesvirus 8, Human/pathogenicity , Neoplasms/virology , Animals , B-Lymphocytes/virology , Cell Line, Tumor , Cytokines/blood , DNA, Viral/analysis , Disease Models, Animal , Epstein-Barr Virus Infections/blood , Epstein-Barr Virus Infections/immunology , Epstein-Barr Virus Infections/virology , Genes, Viral/genetics , Herpesviridae Infections/blood , Herpesviridae Infections/immunology , Herpesviridae Infections/virology , Herpesvirus 8, Human/genetics , High-Throughput Nucleotide Sequencing , Humans , Lymphoma, Primary Effusion/etiology , Lymphoma, Primary Effusion/virology , Mice , Spleen/pathology , Spleen/virology , Survival Rate , Virus ReplicationABSTRACT
Efficient clearance of bacteremia prevents life-threatening disease. Platelet binding to intravascular bacteria, a process involving platelet glycoprotein GPIb and bacterial opsonization with activated complement C3, influences blood clearance and anti-infective immunity. Using intravital microscopy of the bloodstream of mice infected with Listeria monocytogenes, we show that bacterial clearance is not a uniform process but a "dual-track" mechanism consisting of parallel "fast" and "slow" pathways. "Slow clearance" is regulated by time-dependent bacterial opsonization, stochastic platelet binding, and capture of bacteria-platelet-complexes via the complement receptor of the immunoglobulin superfamily, CRIg. The mechanism spares some bacteria from "fast clearance" and rapid destruction in the liver via Kupffer cell scavenger receptors, keeping them available for adaptive immunity induction by splenic CD8α(+) dendritic cells. We consistently find "fast" and "slow" clearance patterns for a broad panel of other Gram+ and Gram- bacteria. Thus, dual-track clearance balances rapid restoration of blood sterility with induction of specific antibacterial immunity.
Subject(s)
Adaptive Immunity , Bacteremia/immunology , Bacterial Adhesion , Blood Platelets/microbiology , Blood/microbiology , Listeria monocytogenes/immunology , Receptors, Complement/metabolism , Animals , Intravital Microscopy , Mice, Inbred C57BL , Mice, Knockout , Time FactorsABSTRACT
Epstein Barr virus (EBV) infection expands CD8+ T cells specific for lytic antigens to high frequencies during symptomatic primary infection, and maintains these at significant numbers during persistence. Despite this, the protective function of these lytic EBV antigen-specific cytotoxic CD8+ T cells remains unclear. Here we demonstrate that lytic EBV replication does not significantly contribute to virus-induced B cell proliferation in vitro and in vivo in a mouse model with reconstituted human immune system components (huNSG mice). However, we report a trend to reduction of EBV-induced lymphoproliferation outside of lymphoid organs upon diminished lytic replication. Moreover, we could demonstrate that CD8+ T cells against the lytic EBV antigen BMLF1 can eliminate lytically replicating EBV-transformed B cells from lymphoblastoid cell lines (LCLs) and in vivo, thereby transiently controlling high viremia after adoptive transfer into EBV infected huNSG mice. These findings suggest a protective function for lytic EBV antigen-specific CD8+ T cells against EBV infection and against virus-associated tumors in extra-lymphoid organs. These specificities should be explored for EBV-specific vaccine development.
Subject(s)
B-Lymphocytes/virology , Cell Transformation, Viral/physiology , Epstein-Barr Virus Infections/immunology , T-Lymphocytes, Cytotoxic/immunology , Adoptive Transfer , Animals , CD8-Positive T-Lymphocytes/immunology , Flow Cytometry , Humans , Immunohistochemistry , Mice , Mice, Transgenic , Real-Time Polymerase Chain ReactionABSTRACT
Functional differences between human dendritic cell (DC) subsets and the potential benefits of targeting them with vaccines remain poorly defined. Here we describe that mice with reconstituted human immune system components (huNSG mice) develop all human conventional and plasmacytoid DC compartments in lymphoid organs. Testing different Toll-like receptor agonists for DC maturation in vivo, we found that IL-12p70 and interferon (IFN)-α production correlated with the maturation of CD141+ (BDCA3+) conventional DCs in huNSG mice. Furthermore, depletion of CD141+ DCs before stimulation significantly reduced IFN-α levels in vivo. This DC subset produced similar total amounts but different subtypes of IFN-α in response to synthetic double-stranded RNA compared with plasmacytoid DCs in response to a single-stranded RNA equivalent. Moreover, synthetic double-stranded RNA as adjuvant and antigen targeting to the endocytic receptor DEC-205, a combination that focuses antigen presentation for T-cell priming on CD141+ DCs, stimulated antigen-specific human CD4+ T-cell responses. Thus, the human CD141+ DC subset is a prominent source of IFN-α and interleukin-12 production and should be further evaluated for vaccine development.
Subject(s)
Antigens, CD/immunology , Dendritic Cells/immunology , Interferon-alpha/biosynthesis , Lectins, C-Type/immunology , Lymphocyte Activation/immunology , RNA, Double-Stranded/immunology , Receptors, Cell Surface/immunology , Animals , Antigen Presentation/immunology , CD8-Positive T-Lymphocytes/immunology , Dendritic Cells/cytology , Enzyme-Linked Immunosorbent Assay , Flow Cytometry , Humans , Interferon-alpha/immunology , Mice , Minor Histocompatibility AntigensABSTRACT
Epstein-Barr virus (EBV) persistently infects more than 90% of the human population and is etiologically linked to several B cell malignancies, including Burkitt lymphoma (BL), Hodgkin lymphoma (HL), and diffuse large B cell lymphoma (DLBCL). Despite its growth transforming properties, most immune-competent individuals control EBV infection throughout their lives. EBV encodes various oncogenes, and of the 6 latency-associated EBV-encoded nuclear antigens, only EBNA3B is completely dispensable for B cell transformation in vitro. Here, we report that infection with EBV lacking EBNA3B leads to aggressive, immune-evading monomorphic DLBCL-like tumors in NOD/SCID/γc-/- mice with reconstituted human immune system components. Infection with EBNA3B-knockout EBV (EBNA3BKO) induced expansion of EBV-specific T cells that failed to infiltrate the tumors. EBNA3BKO-infected B cells expanded more rapidly and secreted less T cell-chemoattractant CXCL10, reducing T cell recruitment in vitro and T cell-mediated killing in vivo. B cell lines from 2 EBV-positive human lymphomas encoding truncated EBNA3B exhibited gene expression profiles and phenotypic characteristics similar to those of tumor-derived lines from the humanized mice, including reduced CXCL10 secretion. Screening EBV-positive DLBCL, HL, and BL human samples identified additional EBNA3B mutations. Thus, EBNA3B is a virus-encoded tumor suppressor whose inactivation promotes immune evasion and virus-driven lymphomagenesis.
Subject(s)
Cell Transformation, Viral/genetics , Epstein-Barr Virus Infections/virology , Epstein-Barr Virus Nuclear Antigens/physiology , Genes, Tumor Suppressor , Genes, Viral , Herpesvirus 4, Human/physiology , Lymphoma, B-Cell/virology , Lymphoproliferative Disorders/virology , Postoperative Complications/virology , Tumor Suppressor Proteins/physiology , Tumor Virus Infections/virology , Animals , Cell Line, Transformed/transplantation , Cell Line, Transformed/virology , Chemokine CXCL10/biosynthesis , Chemokine CXCL10/deficiency , Chemokine CXCL10/genetics , Chimera , DNA Mutational Analysis , Epstein-Barr Virus Infections/genetics , Epstein-Barr Virus Nuclear Antigens/genetics , Gene Deletion , Hematopoietic Stem Cell Transplantation , Herpesvirus 4, Human/genetics , Herpesvirus 4, Human/pathogenicity , Humans , Interferon-gamma/deficiency , Interferon-gamma/genetics , Lymphoma, B-Cell/genetics , Lymphoproliferative Disorders/genetics , Mice , Mice, Inbred NOD , Mice, Knockout , Mice, SCID , Mutation , Postoperative Complications/genetics , Transplantation, Heterologous , Tumor Suppressor Proteins/genetics , Tumor Virus Infections/geneticsABSTRACT
Many pathogens relevant to human disease do not infect other animal species. Therefore, animal models that reconstitute or harbor human tissues are explored as hosts for these. In this review, we will summarize recent advances to utilize mice with human immune system components, reconstituted from hematopoietic progenitor cells in vivo. Such mice can be used to study human pathogens that replicate in leukocytes. In addition to studying the replication of these pathogens, the reconstituted human immune system components can also be analyzed for initiating immune responses and control against these infections. Moreover, these new animal models of human infectious disease should replicate the reactivity of the human immune system to vaccine candidates and, especially, the adjuvants contained in them, more faithfully.
Subject(s)
Immune System/immunology , Adaptive Immunity/immunology , Animals , Humans , Immunity, Innate/immunology , Mice , Models, Animal , VaccinationABSTRACT
To investigate human natural killer (NK)-cell reactivity in vivo we have reconstituted human immune system components by transplantation of human hematopoietic progenitor cells into NOD-scid IL2Rγ(null) mice. We demonstrate here that this model allows the development of all NK-cell subsets that are also found in human adult peripheral and cord blood, including NKp46(+)CD56(-) NK cells. Similar to human cord blood, NK cells from these reconstituted mice require preactivation by interleukin-15 to reach the functional competence of human adult NK cells. Mainly the terminally differentiated CD16(+) NK cells demonstrate lower reactivity without this stimulation. After preactivation, both CD16(+) and CD16(-) NK cells efficiently produce interferon-γ and degranulate in response to stimulation with NK cell-susceptible targets, including K562 erythroleukemia cells. NK-cell lines, established from reconstituted mice, demonstrate cytotoxicity against this tumor cell line. Importantly, preactivation can as well be achieved by bystander cell maturation via poly I:C stimulation in vitro and injection of this maturation stimulus in vivo. Preactivation in vivo enhances killing of human leukocyte antigen class I negative tumor cells after their adoptive transfer. These data suggest that a functional, but resting, NK-cell compartment can be established in immune-compromised mice after human hematopoietic progenitor cell transfer.
Subject(s)
Immune System/immunology , Immunocompetence/immunology , Killer Cells, Natural/immunology , Lymphocyte Activation/immunology , Adult , Animals , Antigens, CD34/metabolism , CD56 Antigen/metabolism , Cell Degranulation/drug effects , Cell Differentiation/drug effects , Cytotoxicity, Immunologic/drug effects , Fetal Blood/cytology , Granzymes/metabolism , Hematopoietic Stem Cells/cytology , Hematopoietic Stem Cells/drug effects , Hematopoietic Stem Cells/immunology , Humans , Immune System/drug effects , Immunocompetence/drug effects , Interferon-gamma/biosynthesis , Interleukin-15/pharmacology , Killer Cells, Natural/cytology , Killer Cells, Natural/drug effects , Killer Cells, Natural/physiology , Lymphocyte Activation/drug effects , Lymphocyte Subsets/cytology , Lymphocyte Subsets/drug effects , Lymphocyte Subsets/immunology , Mice , Mice, Inbred NOD , Mice, SCID , Natural Cytotoxicity Triggering Receptor 1/metabolism , Perforin/metabolism , Poly I-C/administration & dosage , Poly I-C/pharmacology , Receptors, Interleukin-2/metabolismABSTRACT
We have recently characterized that influenza A virus blocks autophagosome degradation via its matrix protein 2. Matrix protein 2 seems to achieve this macroautophagy inhibition not by its well-characterized proton channel function, but possibly due to its binding to Atg6/Beclin 1, thereby enhancing the death of its host cell. Here we discuss several viruses that now have been described to compromise macroautophagy via binding to Atg6/Beclin 1 with different outcomes for their replication, and how interaction with one and the same protein could inhibit autophagosome generation or degradation.
Subject(s)
Apoptosis Regulatory Proteins/genetics , Autophagy/genetics , Gene Targeting , Membrane Proteins/genetics , Virus Diseases/therapy , Viruses/immunology , Animals , Apoptosis Regulatory Proteins/physiology , Autophagy/immunology , Autophagy/physiology , Beclin-1 , Gene Targeting/methods , HIV-1/immunology , HIV-1/physiology , Humans , Immunity, Innate/genetics , Influenza A virus/immunology , Influenza A virus/physiology , Membrane Proteins/physiology , Models, Biological , Virus Diseases/genetics , Virus Diseases/immunologyABSTRACT
Influenza A virus is an important human pathogen causing significant morbidity and mortality every year and threatening the human population with epidemics and pandemics. Therefore, it is important to understand the biology of this virus to develop strategies to control its pathogenicity. Here, we demonstrate that influenza A virus inhibits macroautophagy, a cellular process known to be manipulated by diverse pathogens. Influenza A virus infection causes accumulation of autophagosomes by blocking their fusion with lysosomes, and one viral protein, matrix protein 2, is necessary and sufficient for this inhibition of autophagosome degradation. Macroautophagy inhibition by matrix protein 2 compromises survival of influenza virus-infected cells but does not influence viral replication. We propose that influenza A virus, which also encodes proapoptotic proteins, is able to determine the death of its host cell by inducing apoptosis and also by blocking macroautophagy.