Inhibition of macrophage inflammatory protein-1 alpha production by Epstein-Barr virus

Distinct Immune Reconstitution Profiles Captured by Immune Functional Assays at 6 Months Post Allogeneic Hematopoietic Stem Cell Transplantation

Immune reconstitution after allogeneic-hematopoietic-stem-cell transplantation (allo-HSCT) is a complex and individual process. In this cross-sectional study, whole-blood (WB) immune functional assay (IFA) was used to characterize immune function by assessing immune-related gene/pathway alterations. The usefulness of this tool in the context of infection, 6 months after transplantation, was evaluated. Sixty allo-HSCT recipients at 6 months after transplantation and 10 healthy volunteers (HV) were included. WB was stimulated in standardized TruCulture tubes using lipopolysaccharides and Staphylococcal enterotoxin B. Gene expression was quantified using a custom 144-gene panel using NanoString nCounter technology and analyzed using Ingenuity Pathway Analysis. The relationships between immune function and clinical characteristics, immune cell counts, and post-transplantation infections were assessed. Allo-HSCT recipients were able to activate similar networks of the innate and adaptive immune response compared to HV, with, nevertheless, a lower intensity. A reduced number and a lower expression of genes associated with immunoregulatory and inflammatory processes were observed in allo-HSCT recipients. The use of immunosuppressive treatments was associated with a protracted immune reconstitution revealed by transcriptomic immunoprofiling. No difference in immune cell counts was observed among patients receiving or not receiving immunosuppressive treatments using a large immunophenotyping panel. Moreover, the expression of a set of genes, including CCL3/CCL4, was significantly lower in patients with Herpesviridae reactivation (32%, 19/60), which once again was not identified using classical immune cell counts. Transcriptional IFA revealed the heterogeneity among allo-HSCT recipients with a reduced immune function, a result that could not be captured by circulating immune cell counts. This highlights the potential added value of this tool for the personalized care of immunocompromised patients.

Pathogen Burden, Blood Biomarkers and Functional Ageing in Community-Dwelling Older Adults

BACKGROUND

Lifelong accumulation of latent or persistent or repeated infections may be a contributing factor to the deterioration of physical and cognitive function associated with functional ageing, but the evidence is limited and the biological underpinnings are unclear.

METHODS

We profiled the seropositivity for common viral, bacterial and plasmodial pathogens of local importance in community-living older adults in two studies involving 745 older adults (mean age 67.0, SD: 7.7 years), and 142 older adults (mean age 72.7, SD: 8.3 years). Pathogen load was related to different sets of age-related physical and cognitive measures of functional ageing and the frailty index, and plasma levels of biomarkers of inflammation, innate and adaptive immunity, and other physiological functions.

RESULTS

High pathogen load was associated with impaired gait speed (GS), (p<0.015), functional mobility (POMA) (p<0.029), cognitive function (MMSE) (p<<0.05), and increased frailty index (FI) (p<<0.05). High pathogen load was significantly associated with C3a complement activity (p<0.001), matrix metalloproteinase-7, macrophage inflammatory protein-1α (p<0.05), and monocyte chemoattractant protein 2 (p=0.028). Blood biomarkers did not fully explain the observed association between pathogen load and functional ageing measures.

CONCLUSIONS

The present study provides novel evidence linking lifelong cumulated numbers of latent, persistent or repeated infection to functional ageing, plausibly via inflammatory and immune and other biological factors.

Overview of Infections in the Immunocompromised Host

Understanding the components of the immune system that contribute to host defense against infection is key to recognizing infections that are more likely to occur in an immunocompromised patient. In this review, we discuss the integrated system of physical barriers and of innate and adaptive immunity that contributes to host defense. Specific defects in the components of this system that predispose to particular infections are presented. This is followed by a review of primary immunodeficiency diseases and secondary immunodeficiencies, the latter of which develop because of a specific illness or condition or are treatment-related. The effects of treatment for neoplasia, autoimmune diseases, solid organ and stem cell transplants on host defenses are reviewed and associated with susceptibility to particular infections. In conclusion, an approach to laboratory screening for a suspected immunodeficiency is presented. Knowledge of which host defects predispose to specific infections allows clinicians to prevent, diagnose, and manage infections in their immunocompromised patients most effectively.

Autocrine CCL3 and CCL4 induced by the oncoprotein LMP1 promote Epstein-Barr virus-triggered B cell proliferation

Epstein-Barr virus (EBV) alters the regulation and expression of a variety of cytokines in its host cells to modulate host immune surveillance and facilitate viral persistence. Using cytokine antibody arrays, we found that, in addition to the cytokines reported previously, two chemotactic cytokines, CCL3 and CCL4, were induced in EBV-infected B cells and were expressed at high levels in all EBV-immortalized lymphoblastoid cell lines (LCLs). Furthermore, EBV latent membrane protein 1 (LMP1)-mediated Jun N-terminal protein kinase activation was responsible for upregulation of CCL3 and CCL4. Inhibition of CCL3 and CCL4 in LCLs using a short hairpin RNA approach or by neutralizing antibodies suppressed cell proliferation and caused apoptosis, indicating that autocrine CCL3 and CCL4 are required for LCL survival and growth. Importantly, significant amounts of CCL3 were detected in EBV-positive plasma from immunocompromised patients, suggesting that EBV modulates this chemokine in vivo. This study reveals the regulatory mechanism and a novel function of CCL3 and CCL4 in EBV-infected B cells. CCL3 might be useful as a therapeutic target in EBV-associated lymphoproliferative diseases and malignancies.

Downregulation of integrin receptor-signaling genes by Epstein-Barr virus EBNA 3C via promoter-proximal and -distal binding elements

Epstein-Barr virus (EBV) establishes a persistent latent infection in B lymphocytes and is associated with the development of numerous human tumors. Epstein-Barr nuclear antigen 3C (EBNA 3C) is essential for B-cell immortalization, has potent cell cycle deregulation capabilities, and functions as a regulator of both viral- and cellular-gene expression. We performed transcription profiling on EBNA 3C-expressing B cells and identified several chemokines and members of integrin receptor-signaling pathways, including CCL3, CCL4, CXCL10, CXCL11, ITGA4, ITGB1, ADAM28, and ADAMDEC1, as cellular target genes that could be repressed by the action of EBNA 3C alone. Chemotaxis assays demonstrated that downregulation of CXCL10 and -11 by EBNA 3C is sufficient to reduce the migration of cells expressing the CXCL10 and -11 receptor CXCR3. Gene repression by EBNA 3C was accompanied by decreased histone H3 lysine 9/14 acetylation and increased histone H3 lysine 27 trimethylation. In an EBV-positive cell line expressing all latent genes, we identified binding sites for EBNA 3C at ITGB1 and ITGA4 and in a distal regulatory region between ADAMDEC1 and ADAM28, providing the first demonstration of EBNA 3C association with cellular-gene control regions. Our data implicate indirect mechanisms in CXCL10 and CXCL11 repression by EBNA 3C. In summary, we have unveiled key cellular pathways repressed by EBNA 3C that are likely to contribute to the ability of EBV-immortalized cells to modulate immune responses, adhesion, and B-lymphocyte migration to facilitate persistence in the host.

Increased incidence of colorectal malignancies in renal transplant recipients: a case control study

This study was to evaluate the frequency of colorectal neoplasia in renal transplant recipients and to investigate the association with Epstein-Barr virus (EBV) and cytomegalovirus (CMV) infection. We compared the frequency of colorectal neoplasia among renal transplant recipients with that of the healthy subjects. Specimens of colorectal neoplasia were examined for EBV and CMV using in situ hybridization and immunohistochemistry, respectively. Of 796 renal transplantation cohorts, 315 were enrolled. The frequency of colorectal neoplasia among the patients was 22.9%. Compared with the healthy subjects, the odds ratio (OR) for advanced adenoma was 3.32 (95% CI, 1.81-6.10). The frequency of cancer among the patients was 1.9% (OR, 12.0; 95% CI, 1.45-99.7). A long interval between transplantation and colonoscopy was a significant factor in the development of advanced colorectal neoplasia. EBV positivity was detected in 30.6% of colorectal neoplasia specimens from renal transplant recipients, which was higher than that for the controls (p = 0.002). CMV was not detected in any lesions of patients or controls. In conclusion, renal transplant recipients have a significantly increased risk of advanced colorectal neoplasia. EBV was more frequently found in specimens of advanced colorectal neoplasm obtained from the renal transplant recipients.

Epstein-Barr virus interferes with the amplification of IFNalpha secretion by activating suppressor of cytokine signaling 3 in primary human monocytes

Background

Epstein-Barr virus is recognized to cause lymphoproliferative disorders and is also associated with cancer. Evidence suggests that monocytes are likely to be involved in EBV pathogenesis, especially due to a number of cellular functions altered in EBV-infected monocytes, a process that may affect efficient host defense. Because type I interferons (IFNs) are crucial mediators of host defense against viruses, we investigated the effect of EBV infection on the IFNα pathway in primary human monocytes.

Methodology/Principal Findings

Infection of monocytes with EBV induced IFNα secretion but inhibited the positive feedback loop for the amplification of IFNα. We showed that EBV infection induced the expression of suppressor of cytokine signaling 3 (SOCS3) and, to a lesser extent, SOCS1, two proteins known to interfere with the amplification of IFNα secretion mediated by the JAK/STAT signal transduction pathway. EBV infection correlated with a blockage in the activation of JAK/STAT pathway members and affected the level of phosphorylated IFN regulatory factor 7 (IRF7). Depletion of SOCS3, but not SOCS1, by small interfering RNA (siRNA) abrogated the inhibitory effect of EBV on JAK/STAT pathway activation and significantly restored IFNα secretion. Finally, transfection of monocytes with the viral protein Zta caused the upregulation of SOCS3, an event that could not be recapitulated with mutated Zta.

Conclusions/Significance

We propose that EBV protein Zta activates SOCS3 protein as an immune escape mechanism that both suppresses optimal IFNα secretion by human monocytes and favors a state of type I IFN irresponsiveness in these cells. This immunomodulatory effect is important to better understand the aspects of the immune response to EBV.

Infiltration of Epstein-Barr virus-harboring lymphocytes occurs in a large subset of bladder cancers

OBJECTIVE

Epstein-Barr virus (EBV) has been implicated in the genesis of a variety of human cancers. We aimed to confirm the presence and define the role of EBV in bladder cancer.

METHODS

A total of 39 bladder cancer specimens were analyzed. Ten urinary bladder tissues obtained at autopsy were used as a normal control. EBV-encoded RNA (EBER) was evaluated by in situ hybridization (ISH). Frozen material available from 18 EBER-positive cases was analyzed by using reverse transcription-polymerase chain reaction for BZLF1, an early lytic gene product. The expression of CD20, CD3, ZEBRA (BZLF1 product) and transforming growth factor beta1 (TGFbeta-1) was assessed using an immunohistochemical technique.

RESULTS

Infiltration of EBER-expressing lymphocytes was detected in 26 of 39 bladder cancer cases (66.7%). A small fraction of the tumor cells as well as the infiltrating lymphocytes were positive in two cases. All normal urinary bladder specimens showed negative results. The incidence of EBV-positive lymphocyte infiltration was significantly higher for advanced stage cancers than those in earlier stages (Ta-152% vs T2-4 93%, P = 0.013). The presence of BZLF1 mRNA was demonstrated in seven out of the 18 EBER-positive cases.

CONCLUSIONS

Infiltration of EBV-harboring lymphocytes occurs in a large subset of bladder cancers cases. It is more frequently associated with advanced stages. EBV infection in tumor cells is very limited. Our findings suggest that EBV-positive lymphocytes might play a role in bladder cancer progression.

Epstein-Barr virus immunossuppression of innate immunity mediated by phagocytes

Epstein-Barr virus (EBV) is an oncogenic human herpesvirus that persistently infects approximately 90% of the world's population. Such a remarkably sustained of viral infectivity relies on EBV's ability to evade the host immune defenses. A crucial part of this anti-EBV response is mediated by cytotoxic CD8+ T lymphocytes, which maintain a life-long control over proliferating latently-infected B cells in order to prevent these from giving rise to lymphomatous diseases. On the other hand, little has been done to assess the role of phagocytes-mediated innate immunity in the pathogenesis of EBV infection. In the course of primary EBV infection, episodes of neutropenia and monocytopenia can be observed during the acute phase of infection. According to the role of those cells in the non specific and specific immunity, such a decrease in circulating phagocytes may then temporarily affect the immune defense and potentially influence the outcome of EBV infection. Recent studies have demonstrated that EBV infects both neutrophils and monocytes and modulates several of their biological functions. This review covers the current state of our knowledge relative to the role of neutrophils and monocytes in EBV pathogenesis and describes the nature of countermeasures deployed by EBV against these cells.

Human gammaherpesvirus cytokines and chemokine receptors

Most herpesviruses of the beta and gamma subfamilies encode homologues of cytokines and chemokine receptor- related G protein-coupled receptors (GPCRs). The roles of these proteins during normal virus replication in the infected host have not been defined in most cases, but the available data and extrapolation from what is known about the properties and functions of their cellular counterparts indicate that they play primary roles in immune evasion or in activating cellular signaling cascades that enhance virus productive replication. Cytokines and chemokine receptors specified by the two human gammaherpesviruses, human herpesvirus 8 (HHV-8) and Epstein-Barr virus (EBV), are the subject of this review. HHV-8 encodes three chemokines, a homologue of interleukin-6, and a CXCR2-related chemokine receptor, while EBV encodes a distinct GPCR and a homologue of interleukin-10. While these viral cytokines and chemokine receptors no doubt contribute to virus biology, their properties indicate that they may also be involved in virus-induced neoplasia. This review discusses the properties, functions, and likely roles of HHV-8 and EBV cytokines and chemokine receptors in relation to both virus biology and virus-associated disease.

Macrophage chemotaxis to apoptotic Burkitt's lymphoma cells in vitro: role of CD14 and CD36

In Burkitt's lymphoma (BL), apoptosis occurs at high frequency alongside uncontrolled proliferation. Macrophages infiltrate these tumours in large numbers and engage in the phagocytic clearance of apoptotic cells in situ. Here we tested the hypothesis that apoptosis of BL cells may provide a mechanism for recruitment of macrophages to these tumours. We show that monocytes and macrophages, but not neutrophils, preferentially migrated to apoptotic BL cells in vitro. Transfection of BL cells with the anti-apoptotic gene bcl-2 both prevented apoptosis and abolished macrophage chemotaxis. Macrophage migration to BL populations correlated well with the number of apoptotic BL cells present (the Pearson correlation r = 0.81, p<0.0001). Chemoattraction of murine macrophages to apoptotic human BL cells demonstrated that the mechanism was conserved across these species. In an attempt to identify the macrophage receptors involved in this process, we investigated whether CD14 and CD36, two receptors important in the phagocytic clearance of apoptotic cells, were also involved in the chemotactic macrophage response. We found that bone marrow-derived macrophages from CD14-/- and CD36-/- mice moved as well as wild-type macrophages in chemotaxis assays towards apoptotic BL cells. Migrating macrophages were found to be up-regulated in their expression of CD14, however, suggesting that, although this receptor does not appear to be required for 'sensing' apoptotic cells, it may be up-regulated on the surface of the migrating macrophage in readiness for apoptotic corpse clearance.