Functional inactivation of EBV-specific T-lymphocytes in nasopharyngeal carcinoma: implications for tumor immunotherapy

Differential analysis of histopathological and genetic markers of cancer aggressiveness, and survival difference in EBV-positive and EBV-negative prostate carcinoma

Several studies have shown an association between prostate carcinoma (PCa) and Epstein-Barr virus (EBV); however, none of the studies so far have identified the histopathological and genetic markers of cancer aggressiveness associated with EBV in PCa tissues. In this study, we used previously characterized EBV-PCR-positive (n = 39) and EBV-negative (n = 60) PCa tissues to perform an IHC-based assessment of key histopathological and molecular markers of PCa aggressiveness (EMT markers, AR expression, perineural invasion, and lymphocytic infiltration characterization). Additionally, we investigated the differential expression of key oncogenes, EMT-associated genes, and PCa-specific oncomiRs, in EBV-positive and -negative tissues, using the qPCR array. Finally, survival benefit analysis was also performed in EBV-positive and EBV-negative PCa patients. The EBV-positive PCa exhibited a higher percentage (80%) of perineural invasion (PNI) compared to EBV-negative PCa (67.3%) samples. Similarly, a higher lymphocytic infiltration was observed in EBV-LMP1-positive PCa samples. The subset characterization of T and B cell lymphocytic infiltration showed a trend of higher intratumoral and tumor stromal lymphocytic infiltration in EBV-negative tissues compared with EBV-positive tissues. The logistic regression analysis showed that EBV-positive status was associated with decreased odds (OR = 0.07; p-value < 0.019) of CD3 intratumoral lymphocytic infiltration in PCa tissues. The analysis of IHC-based expression patterns of EMT markers showed comparable expression of all EMT markers, except vimentin, which showed higher expression in EBV-positive PCa tissues compared to EBV-negative PCa tissues. Furthermore, gene expression analysis showed a statistically significant difference (p < 0.05) in the expression of CDH1, AR, CHEK-2, CDKN-1B, and CDC-20 and oncomiRs miR-126, miR-152-3p, miR-452, miR-145-3p, miR-196a, miR-183-3p, and miR-146b in EBV-positive PCa tissues compared to EBV-negative PCa tissues. Overall, the survival proportion was comparable in both groups. The presence of EBV in the PCa tissues results in an increased expression of certain oncogenes, oncomiRs, and EMT marker (vimentin) and a decrease in CD3 ITL, which may be associated with the aggressive forms of PCa.

The impact of HLA polymorphism on herpesvirus infection and disease

Human Leukocyte Antigens (HLA) are cell surface molecules, central in coordinating innate and adaptive immune responses, that are targets of strong diversifying natural selection by pathogens. Of these pathogens, human herpesviruses have a uniquely ancient relationship with our species, where coevolution likely has reciprocating impact on HLA and viral genomic diversity. Consistent with this notion, genetic variation at multiple HLA loci is strongly associated with modulating immunity to herpesvirus infection. Here, we synthesize published genetic associations of HLA with herpesvirus infection and disease, both from case/control and genome-wide association studies. We analyze genetic associations across the eight human herpesviruses and identify HLA alleles that are associated with diverse herpesvirus-related phenotypes. We find that whereas most HLA genetic associations are virus- or disease-specific, HLA-A*01 and HLA-A*02 allotypes may be more generally associated with immune susceptibility and control, respectively, across multiple herpesviruses. Connecting genetic association data with functional corroboration, we discuss mechanisms by which diverse HLA and cognate receptor allotypes direct variable immune responses during herpesvirus infection and pathogenesis. Together, this review examines the complexity of HLA-herpesvirus interactions driven by differential T cell and Natural Killer cell immune responses.

T-cell dysfunction in natural killer/T-cell lymphoma

Natural killer/T-cell lymphoma (NKTCL) is an incurable aggressive T-cell lymphoma closely correlated with Epstein‒Barr virus (EBV) infection. Chronic and consistent viral infection induces T-cell exhaustion. Herein, we describe T-cell dysfunction in NKTCL patients for the first time. Peripheral blood mononuclear cells (PBMCs) from age-matched healthy donors (HDs) and NKTCL patients were collected, and lymphocyte distributions, multiple surface inhibitory receptors (IRs), effector cytokine production and cell proliferation were determined by flow cytometry. PBMCs from HDs were cocultured with NKTCL cell lines to verify the clinical findings. IR expression was further assessed in NKTCL tumor biopsies using multiplex immunohistochemistry (mIHC). NKTCL patients have higher frequencies than HDs of inhibitory T regulatory cells (Tregs) and myeloid-derived suppressor cells (MDSCs). T-cell distribution also varies between NKTCL patients and HDs. T cells from NKTCL patients demonstrated higher expression levels of multiple IRs than HDs. Meanwhile, T-cell proliferation and interferon-γ production was significantly reduced in NKTCL patients. More importantly, the number of EBV-specific cytotoxic cells was lower in NTKCL patients, and these cells demonstrated upregulation of multiple IRs and secreted fewer effector cytokines. Interestingly, NKTCL cells caused normal PBMCs to acquire T-cell exhaustion phenotypes and induced generation of Tregs and MDSCs. In line with ex vivo finding, mIHC results showed that CD8+ T cells from NKTCL tumor biopsies expressed much higher level of IRs compared with reactive lymphoid hyperplasia individuals. The immune microenvironment of NKTCL patients exhibited T-cell dysfunction and accumulation of inhibitory cell components, which may contribute to impaired antitumor immunity.

Clinical efficacy and biomarker analysis of dual PD-1/CTLA-4 blockade in recurrent/metastatic EBV-associated nasopharyngeal carcinoma

Single-agent checkpoint inhibitor (CPI) activity in Epstein-Barr Virus (EBV) related nasopharyngeal carcinoma (NPC) is limited. Dual CPI shows increased activity in solid cancers. In this single-arm phase II trial (NCT03097939), 40 patients with recurrent/metastatic EBV-positive NPC who failed prior chemotherapy receive nivolumab 3 mg/kg every 2 weeks and ipilimumab 1 mg/kg every 6 weeks. Primary outcome of best overall response rate (BOR) and secondary outcomes (progression-free survival [PFS], clinical benefit rate, adverse events, duration of response, time to progression, overall survival [OS]) are reported. The BOR is 38% with median PFS and OS of 5.3 and 19.5 months, respectively. This regimen is well-tolerated and treatment-related adverse events requiring discontinuation are low. Biomarker analysis shows no correlation of outcomes to PD-L1 expression or tumor mutation burden. While the BOR does not meet pre-planned estimates, patients with low plasma EBV-DNA titre (<7800 IU/ml) trend to better response and PFS. Deep immunophenotyping of pre- and on-treatment tumor biopsies demonstrate early activation of the adaptive immune response, with T-cell cytotoxicity seen in responders prior to any clinically evident response. Immune-subpopulation profiling also identifies specific PD-1 and CTLA-4 expressing CD8 subpopulations that predict for response to combined immune checkpoint blockade in NPC.

Nasopharyngeal carcinoma cells promote regulatory T cell development and suppressive activity via CD70-CD27 interaction

Despite the intense CD8+ T-cell infiltration in the tumor microenvironment of nasopharyngeal carcinoma, anti-PD-1 immunotherapy shows an unsatisfactory response rate in clinical trials, hindered by immunosuppressive signals. To understand how microenvironmental characteristics alter immune homeostasis and limit immunotherapy efficacy in nasopharyngeal carcinoma, here we establish a multi-center single-cell cohort based on public data, containing 357,206 cells from 50 patient samples. We reveal that nasopharyngeal carcinoma cells enhance development and suppressive activity of regulatory T cells via CD70-CD27 interaction. CD70 blocking reverts Treg-mediated suppression and thus reinvigorate CD8+ T-cell immunity. Anti-CD70+ anti-PD-1 therapy is evaluated in xenograft-derived organoids and humanized mice, exhibiting an improved tumor-killing efficacy. Mechanistically, CD70 knockout inhibits a collective lipid signaling network in CD4+ naïve and regulatory T cells involving mitochondrial integrity, cholesterol homeostasis, and fatty acid metabolism. Furthermore, ATAC-Seq delineates that CD70 is transcriptionally upregulated by NFKB2 via an Epstein-Barr virus-dependent epigenetic modification. Our findings identify CD70+ nasopharyngeal carcinoma cells as a metabolic switch that enforces the lipid-driven development, functional specialization and homeostasis of Tregs, leading to immune evasion. This study also demonstrates that CD70 blockade can act synergistically with anti-PD-1 treatment to reinvigorate T-cell immunity against nasopharyngeal carcinoma.

Epstein–Barr Virus Epithelial Cancers—A Comprehensive Understanding to Drive Novel Therapies

Epstein–Barr virus (EBV) is a ubiquitous oncovirus associated with specific epithelial and lymphoid cancers. Among the epithelial cancers, nasopharyngeal carcinoma (NPC), lymphoepithelioma-like carcinoma (LELC), and EBV-associated gastric cancers (EBVaGC) are the most common. The role of EBV in the pathogenesis of NPC and in the modulation of its tumour immune microenvironment (TIME) has been increasingly well described. Much less is known about the pathogenesis and tumour–microenvironment interactions in other EBV-associated epithelial cancers. Despite the expression of EBV-related viral oncoproteins and a generally immune-inflamed cancer subtype, EBV-associated epithelial cancers have limited systemic therapeutic options beyond conventional chemotherapy. Immune checkpoint inhibitors are effective only in a minority of these patients and even less efficacious with molecular targeting drugs. Here, we examine the key similarities and differences of NPC, LELC, and EBVaGC and comprehensively describe the clinical, pathological, and molecular characteristics of these cancers. A deeper comparative understanding of these EBV-driven cancers can potentially uncover targets in the tumour, TIME, and stroma, which may guide future drug development and cast light on resistance to immunotherapy.

The Stromal and Immune Landscape of Nasopharyngeal Carcinoma and Its Implications for Precision Medicine Targeting the Tumor Microenvironment

The evolution of the tumor microenvironment (TME) is a cancer-dependent and dynamic process. The TME is often a complex ecosystem with immunosuppressive and tumor-promoting functions. Conventional chemotherapy and radiotherapy, primarily focus on inducing tumor apoptosis and hijacking tumor growth, whereas the tumor-protective microenvironment cannot be altered or destructed. Thus, tumor cells can quickly escape from extraneous attack and develop therapeutic resistance, eventually leading to treatment failure. As an Epstein Barr virus (EBV)-associated malignancy, nasopharyngeal carcinoma (NPC) is frequently infiltrated with varied stromal cells, making its microenvironment a highly heterogeneous and suppressive harbor protecting tumor cells from drug penetration, immune attack, and facilitating tumor development. In the last decade, targeted therapy and immunotherapy have emerged as promising options to treat advanced, metastatic, recurrent, and resistant NPC, but lack of understanding of the TME had hindered the therapeutic development and optimization. Single-cell sequencing of NPC-infiltrating cells has recently deciphered stromal composition and functional dynamics in the TME and non-malignant counterpart. In this review, we aim to depict the stromal landscape of NPC in detail based on recent advances, and propose various microenvironment-based approaches for precision therapy.

Radiotherapy Combined with PD-1 Inhibition Increases NK Cell Cytotoxicity towards Nasopharyngeal Carcinoma Cells

BACKGROUND

Nasopharyngeal carcinoma (NPC) in endemic regions and younger patients is characterized by a prominent lymphomononuclear infiltration. Radiation is the principal therapeutic modality for patients with NPC. Recent data suggest that the efficacy of radiotherapy in various cancers can be augmented when combined with immune checkpoint blockade. Here, we investigate the effect of radiotherapy on the killing of NPC cells by Natural Killer (NK) cells.

METHODS

NPC cell lines and a patient-derived xenograft were exposed to NK cells in the context of radiotherapy. Cytotoxicity was measured using the calcein-release assay. The contribution of the PD-L1/PD-1 checkpoint and signaling pathways to killing were analyzed using specific inhibitors.

RESULTS

Radiotherapy sensitized NPC cells to NK cell killing and upregulated expression of PD-1 ligand (PD-L1) in NPC cells and PD-1 receptor (PD-1) in NK cells. Blocking of the PD-L1/PD-1 checkpoint further increased the killing of NPC cells by NK cells in the context of radiotherapy.

CONCLUSION

Radiation boosts the killing of NPC cells by NK cells. Killing can be further augmented by blockade of the PD-L1/PD-1 checkpoint. The combination of radiotherapy with PD-L1/PD-1 checkpoint blockade could therefore increase the efficacy of radiotherapy in NPC tumors.

The molecular march of primary and recurrent nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) results from the aberrant and uncontrolled growth of the nasopharyngeal epithelium. It is highly associated with the Epstein-Barr virus, especially in regions where it is endemic. In the last decade, significant advances in genetic sequencing techniques have allowed the discovery of many new abnormal molecular processes that undoubtedly contribute to the establishment, growth and spread of this deadly disease. In this review, we consider NPC as EBV induced. We summarise the recent discoveries and how they add to our understanding of the pathophysiology of NPC in the context of genomics first in primary and then in recurrent disease. Overall, we find key early events lead to p16 inactivation and cyclin D1 expression, allowing latent viral infection. Host and viral factors work together to affect a variety of molecular pathways, the most fundamental being activation of NF-κB. Nonetheless, much still yearns to be discovered, especially in recurrent NPC.

The Role of EBV-Encoded LMP1 in the NPC Tumor Microenvironment: From Function to Therapy

Nasopharyngeal carcinoma (NPC) is closely associated with Epstein-Barr virus (EBV) infection. It is also characterized by heavy infiltration with non-malignant leucocytes. The EBV-encoded latent membrane protein 1 (LMP1) is believed to play an important role in NPC pathogenesis by virtue of its ability to activate multiple cell signaling pathways which collectively promote cell proliferation and survival, angiogenesis, invasiveness, and aerobic glycolysis. LMP1 also affects cell-cell interactions, antigen presentation, and cytokine and chemokine production. Here, we discuss how LMP1 modulates local immune responses that contribute to the establishment of the NPC tumor microenvironment. We also discuss strategies for targeting the LMP1 protein as a novel therapy for EBV-driven malignancies.

Extracellular Vesicles in Viral Pathogenesis: A Case of Dr. Jekyll and Mr. Hyde

Secretion of extracellular vesicles (EVs) is a fundamental property of living cells. EVs are known to transfer biological signals between cells and thus regulate the functional state of recipient cells. Such vesicles mediate the intercellular transport of many biologically active molecules (proteins, nucleic acids, specific lipids) and participate in regulation of key physiological processes. In addition, EVs are involved in the pathogenesis of multiple diseases: infectious, neurodegenerative, and oncological. The current EV classification into microvesicles, apoptotic bodies, and exosomes is based on their size, pathways of cellular biogenesis, and molecular composition. This review is focused on analysis of the role of EVs (mainly exosomes) in the pathogenesis of viral infection. We briefly characterize the biogenesis and molecular composition of various EV types. Then, we consider EV-mediated pro- and anti-viral mechanisms. EV secretion by infected cells can be an important factor of virus spread in target cell populations, or a protective factor limiting viral invasion. The data discussed in this review, on the effect of EV secretion by infected cells on processes in neighboring cells and on immune cells, are of high significance in the search for new therapeutic approaches and for design of new generations of vaccines.

Targeting the signaling in Epstein-Barr virus-associated diseases: mechanism, regulation, and clinical study

Epstein–Barr virus-associated diseases are important global health concerns. As a group I carcinogen, EBV accounts for 1.5% of human malignances, including both epithelial- and lymphatic-originated tumors. Moreover, EBV plays an etiological and pathogenic role in a number of non-neoplastic diseases, and is even involved in multiple autoimmune diseases (SADs). In this review, we summarize and discuss some recent exciting discoveries in EBV research area, which including DNA methylation alterations, metabolic reprogramming, the changes of mitochondria and ubiquitin-proteasome system (UPS), oxidative stress and EBV lytic reactivation, variations in non-coding RNA (ncRNA), radiochemotherapy and immunotherapy. Understanding and learning from this advancement will further confirm the far-reaching and future value of therapeutic strategies in EBV-associated diseases.

The Therapeutic Potential of Targeting BARF1 in EBV-Associated Malignancies

Epstein-Barr virus (EBV) is closely linked to the development of a number of human cancers. EBV-associated malignancies are characterized by a restricted pattern of viral latent protein expression which is sufficient for the virus to both initiate and sustain cell growth and to protect virus-infected cells from immune attack. Expression of these EBV proteins in malignant cells provides an attractive target for therapeutic intervention. Among the viral proteins expressed in the EBV-associated epithelial malignancies, the protein encoded by the BamHI-A rightward frame 1 (BARF1) is of particular interest. BARF1 is a viral oncoprotein selectively expressed in latently infected epithelial cancers, nasopharyngeal carcinoma (NPC) and EBV-positive gastric cancer (EBV-GC). Here, we review the roles of BARF1 in oncogenesis and immunomodulation. We also discuss potential strategies for targeting the BARF1 protein as a novel therapy for EBV-driven epithelial cancers.

Emerging therapeutic targets for nasopharyngeal carcinoma: opportunities and challenges

Introduction: Nasopharyngeal carcinoma (NPC) is a major public health problem in several countries, especially those in Southeast Asia and North Africa. In its typical poorly differentiated form, the Epstein-Barr virus (EBV) genome is present in the nuclei of all malignant cells with restricted expression of a few viral genes. The malignant phenotype of NPC cells results from the influence of these viral products in combination with cellular genetic, epigenetic and functional alterations. With regard to host/tumor interactions, NPC is a remarkable example of immune escape in the context of a hot tumor.Areas covered: This article has an emphasis on emerging therapeutic targets that are considered upstream or at an early stage of clinical application. It examines targets related to cellular oncogenic alterations, latent EBV infection and tumor interactions with the immune system.Expert opinion: There is a remarkable emergence of new agents that target EBV products. The clinical application of these agents would benefit from a systematic and comprehensive molecular classification of NPCs and from easy access to pre-clinical models in public repositories. There is a strong rationale for more investigations on the potential of immune modulators, especially those related to NK cells.

Low PD-L1 Expression Strongly Correlates with Local Recurrence in Epstein-Barr Virus-Positive Nasopharyngeal Carcinoma after Radiation-Based Therapy

The prognostic value of programmed death-ligand 1 (PD-L1) expression in nasopharyngeal carcinoma (NPC) is controversial, with previous studies showing conflicting results. Most NPCs in endemic areas are Epstein-Barr virus (EBV)-positive. Our aim was to evaluate the clinical significance of PD-L1 expression in EBV-positive NPC. We retrospectively analyzed PD-L1 expression on tumor cells (TCs) and immune cells (ICs) by immunohistochemistry in 208 EBV-positive NPC patients who underwent radiotherapy (203 with concurrent chemotherapy). The percentages of TCs and ICs expressing PD-L1 were evaluated respectively. There was a strong correlation between local recurrence and low PD-L1 expression on ICs (p = 0.0012), TCs (p = 0.013) or both (p = 0.000044), whereas all clinical parameters had no influence on local recurrence. Using multivariate analysis, low PD-L1 expression on ICs was an independent adverse prognostic factor (p = 0.0080; HR = 1.88; 95% CI = 1.18⁻3.00) for disease-free survival. High PD-L1 expression on both ICs and TCs was an independent favorable prognostic factor (p = 0.022; HR = 0.46; 95% CI = 0.24⁻0.89) for overall survival. We show for the first time that low PD-L1 expression on ICs and TCs strongly correlates with local recurrence in EBV-positive NPC patients after radiation-based therapy. A simple immunohistochemical study for PD-L1 can identify patients prone to local recurrence, and such patients might benefit from more aggressive treatment in future clinical trials.

The emerging role of Epstein-Barr virus encoded microRNAs in nasopharyngeal carcinoma

Epstein-Barr virus (EBV) is an oncogenic herpes virus that is closely associated with the initiation and development of nasopharyngeal carcinoma (NPC), lymphoma and other malignant tumors. EBV encodes 44 mature miRNAs that regulate viral and host cell gene expression and plays a variety of roles in biological functions and the development of cancer. In this review, we summarized the biological functions and molecular mechanisms of Epstein-Barr virus-encoded microRNAs (EBV miRNAs) in tumor immune evasion, proliferation, anti-apoptosis, invasion, metastasis and as a potential biomarker for NPC diagnosis and prognosis. The knowledge generated by EBV miRNAs can be used for EBV miRNA-based precision cancer treatments in the near future.

Role of Epstein-Barr Virus in the Pathogenesis of Head and Neck Cancers and Its Potential as an Immunotherapeutic Target

The role of Epstein-Barr virus (EBV) infection in the development and progression of tumor cells has been described in various cancers. Etiologically, EBV is a causative agent in certain variants of head and neck cancers such as nasopharyngeal cancer. Proteins expressed by the EVB genome are involved in invoking and perpetuating the oncogenic properties of the virus. However, these protein products were also identified as important targets for therapeutic research in the past decades, particularly within the context of immunotherapy. The adoptive transfer of EBV-targeted T-cells as well as the development of EBV vaccines has opened newer lines of research to conceptualize novel therapeutic approaches toward the disease. This review addresses the most important aspects of the association of EBV with head and neck cancers from an immunological perspective. It also aims to highlight the current and future prospects of enhanced EBV-targeted immunotherapies.

Interplay of Viral Infection, Host Cell Factors and Tumor Microenvironment in the Pathogenesis of Nasopharyngeal Carcinoma

Undifferentiated nasopharyngeal carcinoma (NPC) is strongly associated with Epstein-Barr virus (EBV) infection. In addition, heavy infiltration of leukocytes is a common characteristic of EBV-associated NPC. It has long been suggested that substantial and interactive impacts between cancer and stromal cells create a tumor microenvironment (TME) to promote tumorigenesis. The coexistence of tumor-infiltrating lymphocytes with EBV-infected NPC cells represents a distinct TME which supports immune evasion and cancer development from the early phase of EBV infection. Intracellularly, EBV-encoded viral products alter host cell signaling to facilitate tumor development and progression. Intercellularly, EBV-infected cancer cells communicate with stromal cells through secretion of cytokines and chemokines, or via release of tumor exosomes, to repress immune surveillance and enhance metastasis. Although high expression of miR-BARTs has been detected in NPC patients, contributions of these more recently discovered viral products to the establishment of TME are still vaguely defined. Further investigations are needed to delineate the mechanistic linkage of the interplay between viral and host factors, especially in relation to TME, which can be harnessed in future therapeutic strategies.

Analysis of the Expression of Surface Receptors on NK Cells and NKG2D on Immunocytes in Peripheral Blood of Patients with Nasopharyngeal Carcinoma

Background:

The aberrant expression of surface receptors on immunocytes may represent potential markers of tumor escape for nasopharyngeal carcinoma (NPC). The aim of this study was to investigate the expression of representative receptors on natural killer (NK) cells and NK group 2, member D (NKG2D) on immunocytes in the peripheral blood of patients with NPC.

Methods:

Patients (n = 64) with NPC prior to initiation of treatment were defined as the study group. Healthy volunteers (n = 31) served as the control group. The expression of NK cells and NKT cells; the triggering receptors NKp30, NKp44, and NKp46 on NK cells; the activating receptor NKG2D on NK cells, CD4+ T cells, and CD8+ T cells; and the inhibitory receptors CD158b and CD159a on NK cells were analyzed by flow cytometry in the two groups.

Results:

Here, our study showed that no differences were observed in terms of the numbers of NK cells or NKT cells, or the expression of CD158b and CD159a on the surface of NK cells between the two groups. Nevertheless, the expression levels of NKp30 and NKp46 on NK cells in the NPC patients were significantly lower than in the healthy individuals (P < 0.05). No differences existed in the expression of NKG2D on NK cells, but NKG2D on CD8+ T cells showed a markedly lower expression in the study group (P < 0.001).

Conclusions:

Our findings may reflect a possible mechanism of immune evasion for NPC. The enhancement of immunotherapy concerning NKp30, NKp46, and NKG2D may be an innovative treatment strategy for patients with NPC.

Monocyte-derived factors including PLA2G7 induced by macrophage-nasopharyngeal carcinoma cell interaction promote tumor cell invasiveness

The non-keratinizing undifferentiated subtype of nasopharyngeal carcinoma (NPC) is a malignancy characterized by an intimate relationship between neoplastic cells and a non-neoplastic lymphoid component. Tumor-associated macrophages (TAMs) foster tumor progression through production of soluble mediators that support proliferation, angiogenesis, survival and invasion of malignant cells. However, the role of macrophages in the progression of NPC remains poorly understood. This study aims to investigate the functional and phenotypic changes that occur to macrophages in macrophage-NPC cell co-culture systems, and how these changes influence tumor cells. We found that monocytes, including THP-1 cells and primary human monocytes, co-cultured with C666-1 NPC cells upregulate expression of pro-inflammatory cytokines at the early stages, followed by the induction of metastasis-related genes and interferon-stimulated genes at the later stage of coculture, indicating that TAMs are “educated” by NPC cells for cancer progression. Importantly, the induction of these factors from the TAMs was also found to enhance the migratory capabilities of the NPC cells. We have also identified one of these macrophage-derived factor, phospholipase A2 Group 7 (PLA2G7), to be important in regulating tumor cell migration and a novel tumor-promoting factor in NPC. Further studies to characterize the role of PLA2G7 in tumor metastasis may help determine its potential as a therapeutic target in NPC.

A novel Epstein-Barr virus-latent membrane protein-1-specific T-cell receptor for TCR gene therapy

BACKGROUND

Adoptive transfer of genetically engineered T-cells to express antigen-specific T-cell receptor (TCR) is a feasible and effective therapeutic approach for numerous types of cancers, including Epstein-Barr virus (EBV)-associated malignancies. Here, we describe a TCR gene transfer regimen to rapidly and reliably generate T-cells specific to EBV-encoded latent membrane protein-1 (LMP1), which is a potential target for T-cell-based immunotherapy.

METHODS

A novel TCR specific to LMP1 (LMP1-TCR) was isolated from HLA-A*0201 transgenic mice that were immunised with the minimal epitope LMP1₁₆₆ (TLLVDLLWL), and LMP1-TCR-transduced peripheral blood lymphocytes were evaluated for functional specificities.

RESULTS

Both human CD8 and CD4 T-cells expressing the LMP1-TCR provoked high levels of cytokine secretion and cytolytic activity towards peptide-pulsed and LMP1-expressing tumour cells. Notably, recognition of these T-cells to peptide-pulsed cells was maintained at low concentration of peptide, implying that the LMP1-TCR has high avidity. Infusion of these engineered T-cells revealed remarkable therapeutic effects and inhibition of tumour growth in a preclinical xenogeneic model. We observed explosive ex vivo proliferation of functional TCR-transduced T-cells with artificial antigen-presenting cells that express co-stimulatory molecules CD80 and 4-1BBL.

CONCLUSIONS

These data suggest that the novel TCR-targeting LMP1 might allow the potential design of T-cell-based immunotherapeutic strategies against EBV-positive malignancies.

Cytolytic virus activation therapy and treatment monitoring for Epstein-Barr virus associated nasopharyngeal carcinoma in a mouse tumor model

Undifferentiated nasopharyngeal carcinoma (NPC) is 100% associated with Epstein‐Barr virus (EBV). Expression of viral proteins in the tumor cells is highly restricted. EBV reactivation by CytoLytic Virus Activation (CLVA) therapy triggers de novo expression of early viral kinases (PK and TK) and uses antiviral treatment to kill activated cells. The mechanism of tumor elimination by CLVA was analyzed in NPC mouse model using C666.1 cells. Valproic acid (VPA) was combined with gemcitabine (GCb) to stimulate EBV reactivation, followed by antiviral treatment with ganciclovir (GCV). A single cycle of CLVA treatment resulted in specific tumor cell killing as indicated by reduced tumor volume, loss of EBV‐positive cells in situ, and paralleled by decreased EBV DNA levels in circulation, which was more pronounced than treatment with GCb alone. In vivo reactivation was confirmed by presence of lytic gene transcripts and proteins in tumors 6 days after GCb/VPA treatment. Virus reactivation was visualized by [¹²⁴I]‐FIAU accumulation in tumors using PET‐scan. This studied showed that CLVA therapy is a potent EBV‐specific targeting approach for killing tumor cells. The [¹²⁴I]‐FIAU appears valuable as PET tracer for studies on CLVA drug dosage and kinetics in vivo, and may find clinical application in treatment monitoring.

Regulatory T Cell Effect on CD8+ T Cell Responses to Human Herpesvirus 8 Infection and Development of Kaposi's Sarcoma

We assessed CD8⁺ T cell reactivity to human herpesvirus 8 (HHV-8; Kaposi's sarcoma [KS]-associated herpesvirus) and the role of CD4⁺CD25^hiFoxP3⁺ regulatory T cells (Treg) in HHV-8- and HIV-coinfected participants of the Multicenter AIDS Cohort Study who did or did not develop KS. There were similarly low CD8⁺ T cell interferon-γ responses to MHC class I-restricted epitopes of HHV-8 lytic and latent proteins over 5.7 years before KS in participants who developed KS compared to those who did not. T cell reactivity to HHV-8 antigens was low relative to responses to a combination of cytomegalovirus, Epstein-Barr virus and influenza A virus (CEF) peptide epitopes, and dominant HIV peptide epitopes. There was no change in %Treg in the HHV-8- and HIV-coinfected participants who did not develop KS, whereas there was a significant increase in %Treg in HHV-8- and HIV-coinfected participants who developed KS beginning 1.8 years before development of KS. Removal of Treg enhanced HHV-8-specific T cell responses in HHV-8- and HIV-coinfected participants who did or did not develop KS, with a similar pattern observed in response to CEF and HIV peptides. Thus, long-term, low levels of anti-HHV-8 CD8⁺ T cell reactivity were present in both HHV-8- and HIV-coinfected men who did and did not develop KS. This was related to moderately enhanced Treg function.

The Safety and Immunological Effects of rAd5-EBV-LMP2 Vaccine in Nasopharyngeal Carcinoma Patients: A Phase I Clinical Trial and Two-Year Follow-Up

Epstein-Barr virus (EBV)-encoded latent membrane protein 2 (LMP2) promotes nasopharyngeal carcinoma (NPC) progression. Previously, we reported that the dendritic cells (DCs) transfected with EBV-LMP2 recombinant serotype 5 adenoviruses (rAd5) induced anti-tumor effect by eliciting cytotoxic T lymphocytes (CTLs)-mediated immune response in vitro and the adenoviral vaccine of EBV-LMP2 (rAd5-EBV-LMP2) stimulated antigen-specific cellular immunity in mice. However, the safety and immunological effect of rAd5-EBV-LMP2 vaccine in human still remained unknown. Here we conducted a single-center, non-randomized, open-label, single-arm phase I clinical trial to clarify this unsolved issue. A total of 24 patients with regional advanced NPC were sequentially enrolled into three dose level groups (2×10(9), 2×10(10), 2×10(11) vp). The rAd5-EBV-LMP2 vaccines were intramuscularly injected for four times within 28 d (D0, D7, D14, D28). Blood samples were harvested immediately before every vaccination, one week and one month after the last vaccination (D0, D7, D14, D28, D35, D58). All the vaccine inoculation-related toxicities presented as grade I/II adverse events. The most frequent systemic adverse reactions were fatigue (33.0%, 8/24), myalgia (29.2%, 7/24) and cough (29.2%, 7/24), while the most common regional adverse reaction was tenderness in the inoculation site (54.2%, 13/24). In addition, proportion of CD(3+)CD(4+) cells in peripheral blood was significantly increased in the high dose group (2×10(11) vp). The rAd5-EBV-LMP2 vaccine was generally well-tolerated and the high dose (2×10(11) vp) is recommended to be adopted in phase II studies. The long-term outcome of rAd5-EBV-LMP2 vaccine inoculation is required to be determined in following placebo-controlled trials.

Prognostic value of indoleamine 2,3-dioxygenase activity and expression in nasopharyngeal carcinoma

Indoleamine 2,3-dioxygenase (IDO) is an enzyme with an immunosuppressive effect whose function is diverted by tumor cells to counteract immune cell functions, inducing immune escape of tumor cells. The aim of this study was to investigate the clinical significance of IDO in nasopharyngeal carcinoma (NPC). Compared to controls, NPC patients' plasma IDO activity was significantly higher, especially among patients with metastatic cancer (p=0.005). The immunohistochemical analysis revealed that high IDO expression was observed in 74% of NPC tissues and the epithelial IDO expression was inversely correlated to T-cell infiltration. Kaplan-Meier survival analysis showed that whatever the localization, intratumoral or stromal, patients with a high IDO expression and low T-cell infiltration have significantly lower survival rates. Moreover, in multivariate analysis, intratumoral and stromal IDO expression were found to be independent prognostic factors for disease-free survival (p=0.016; HR: 3.52) and overall survival (p=0.015; HR: 4.76) respectively. Our findings provide evidence that IDO is involved in tumor immune evasion of NPC, suggesting that it could be a relevant therapeutic target for NPC.

Extracellular vesicles from infected cells: potential for direct pathogenesis

Infections that result in natural or manmade spread of lethal biological agents are a concern and require national and focused preparedness. In this manuscript, as part of an early diagnostics and pathogen treatment strategy, we have focused on extracellular vesicles (EVs) that arise following infections. Although the field of biodefense does not currently have a rich resource in EVs literature, none the less, similar pathogens belonging to the more classical emerging and non-emerging diseases have been studied in their EV/exosomal contents and function. These exosomes are formed in late endosomes and released from the cell membrane in almost every cell type in vivo. These vesicles contain proteins, RNA, and lipids from the cells they originate from and function in development, signal transduction, cell survival, and transfer of infectious material. The current review focuses on how different forms of infection exploit the exosomal pathway and how exosomes can be exploited artificially to treat infection and disease and potentially also be used as a source of vaccine. Virally-infected cells can secrete viral as well as cellular proteins and RNA in exosomes, allowing viruses to cause latent infection and spread of miRNA to nearby cells prior to a subsequent infection. In addition to virally-infected host cells, bacteria, protozoa, and fungi can all release small vesicles that contain pathogen-associated molecular patterns, regulating the neighboring uninfected cells. Examples of exosomes from both virally and bacterially infected cells point toward a re-programming network of pathways in the recipient cells. Finally, many of these exosomes contain cytokines and miRNAs that in turn can effect gene expression in the recipient cells through the classical toll-like receptor and NFκB pathway. Therefore, although exosomes do not replicate as an independent entity, they however facilitate movement of infectious material through tissues and may be the cause of many pathologies seen in infected hosts.

Nasopharyngeal Cancer: Molecular Landscape

Nasopharyngeal carcinoma (NPC) is a unique epithelial malignancy arising from the superior aspect of the pharyngeal mucosal space, associated with latent Epstein-Barr virus infection in most cases. The capacity to characterize cancer genomes in unprecedented detail is now providing insights into the genesis and molecular underpinnings of this disease. Herein, we provide an overview of the molecular aberrations that likely drive nasopharyngeal tumor development and progression. The contributions of major Epstein-Barr virus–encoded factors, including proteins, small RNAs, and microRNAs, along with their interactions with pathways regulating cell proliferation and survival are highlighted. We review recent analyses that clearly define the role of genetic and epigenetic variations affecting the human genome in NPC. These findings point to the impact of DNA methylation and histone modifications on gene expression programs that promote this malignancy. The molecular interactions that allow NPC cells to evade immune recognition and elimination, which is crucial for the survival of cells expressing potentially immunogenic viral proteins, are also described. Finally, the potential utility of detecting host and viral factors for the diagnosis and prognosis of NPC is discussed. Altogether, the studies summarized herein have greatly expanded our knowledge of the molecular biology of NPC, yet much remains to be uncovered. Emerging techniques for using and analyzing well-annotated biospecimens from patients with NPC will ultimately lead to a greater level of understanding, and enable improvements in precision therapies and clinical outcomes.

Management of Nasopharyngeal Carcinoma: Current Practice and Future Perspective

Nasopharyngeal carcinoma of the undifferentiated subtype is endemic to southern China, and patient prognosis has improved significantly over the past three decades because of advances in disease management, diagnostic imaging, radiotherapy technology, and broader application of systemic therapy. Despite the excellent local control with modern radiotherapy, distant failure remains a key challenge. Advances in molecular technology have helped to decipher the molecular pathogenesis of nasopharyngeal carcinoma as well as its etiologic association with the Epstein-Barr virus. This in turn has led to the discovery of novel biomarkers and drug targets, rendering this cancer site a current focus for new drug development. This article reviews and appraises the key literature on the current management of nasopharyngeal carcinoma and future directions in clinical research.

EBV-driven LMP1 and IFN-γ up-regulate PD-L1 in nasopharyngeal carcinoma: Implications for oncotargeted therapy

PD-L1 expression is a feature of Epstein-Barr virus (EBV) associated malignancies such as nasopharyngeal carcinoma (NPC). Here, we found that EBV-induced latent membrane protein 1 (LMP1) and IFN-γ pathways cooperate to regulate programmed cell death protein 1 ligand (PD-L1). Expression of PD-L1 was higher in EBV positive NPC cell lines compared with EBV negative cell lines. PD-L1 expression could be increased by exogenous and endogenous induction of LMP1 induced PD-L1. In agreement, expression of PD-L1 was suppressed by knocking down LMP1 in EBV positive cell lines. We further demonstrated that LMP1 up-regulated PD-L1 through STAT3, AP-1, and NF-κB pathways. Besides, IFN-γ was independent of but synergetic with LMP1 in up-regulating PD-L1 in NPC. Furthermore, we showed that PD-L1 was associated with worse disease-free survival in NPC patients. These results imply that blocking both the LMP1 oncogenic pathway and PD-1/PD-L1 checkpoints may be a promising therapeutic approach for EBV positive NPC patients.

Novel roles and therapeutic targets of Epstein-Barr virus-encoded latent membrane protein 1-induced oncogenesis in nasopharyngeal carcinoma

Epstein-Barr virus (EBV) was first discovered 50 years ago as an oncogenic gamma-1 herpesvirus and infects more than 90% of the worldwide adult population. Nasopharyngeal carcinoma (NPC) poses a serious health problem in southern China and is one of the most common cancers among the Chinese. There is now strong evidence supporting a role for EBV in the pathogenesis of NPC. Latent membrane protein 1 (LMP1), a primary oncoprotein encoded by EBV, alters several functional and oncogenic properties, including transformation, cell death and survival in epithelial cells in NPC. LMP1 may increase protein modification, such as phosphorylation, and initiate aberrant signalling via derailed activation of host adaptor molecules and transcription factors. Here, we summarise the novel features of different domains of LMP1 and several new LMP1-mediated signalling pathways in NPC. When then focus on the potential roles of LMP1 in cancer stem cells, metabolism reprogramming, epigenetic modifications and therapy strategies in NPC.

Impaired T-Cell Function in B-Cell Lymphoma: A Direct Consequence of Events at the Immunological Synapse?

Tumors can escape immune destruction through the development of antigen loss variants and loss of antigen processing/presentation pathways, thereby rendering them invisible to T cells. Alternatively, mechanisms of peripheral T-cell tolerance that would normally be important for protection from the development of autoimmunity may also be co-opted to (i) generate an immuno-inhibitory tumor environment, (ii) promote development of regulatory cell populations, or (iii) cell-intrinsically inactivate tumor-specific T cells. Emerging evidence suggests that T-cell function is impaired in hematological malignancies, which may manifest from cognate interactions between T cells and the tumor. The immunological synapse forms the cognate T-cell and antigen-presenting cell interaction and is the site where key signalling events, including those delivered by co-inhibitory receptors, that determine the fate of T cells occur. Here, we review evidence that events at the immune synapse between T cells and malignant B cells and alterations in immune synapse function may contribute to loss of T-cell function in B-cell malignancies.

Phase I trial of adoptively transferred tumor-infiltrating lymphocyte immunotherapy following concurrent chemoradiotherapy in patients with locoregionally advanced nasopharyngeal carcinoma

Adoptive cell therapy (ACT) for cancers using autologous tumor-infiltrating lymphocytes (TILs) can induce immune responses and antitumor activity in metastatic melanoma patients. Here, we aimed to assess the safety and antitumor activity of ACT using expanded TILs following concurrent chemoradiotherapy (CCRT) in patients with locoregionally advanced nasopharyngeal carcinoma (NPC). Twenty-three newly diagnosed, locoregionally advanced NPC patients were enrolled, of whom 20 received a single-dose of TIL infusion following CCRT. All treated patients were assessed for toxicity, survival and clinical and immunologic responses. Correlations between immunological responses and treatment effectiveness were further studied. Only mild adverse events (AEs), including Grade 3 neutropenia (1/23, 5%) consistent with immune-related causes, were observed. Nineteen of 20 patients exhibited an objective antitumor response, and 18 patients displayed disease-free survival longer than 12 mo after ACT. A measurable plasma Epstein-Barr virus (EBV) load was detected in 14 patients at diagnosis, but a measurable EBV load was not found in patients after one week of ACT, and the plasma EBV load remained undetectable in 17 patients at 6 mo after ACT. Expansion and persistence of T cells specific for EBV antigens in peripheral blood following TIL therapy were observed in 13 patients. The apparent positive correlation between tumor regression and the expansion of T cells specific for EBV was further investigated in four patients. This study shows that NPC patients can tolerate ACT with TILs following CCRT and that this treatment results in sustained antitumor activity and anti-EBV immune responses. A larger phase II trial is in progress.

Understanding the interplay between host immunity and Epstein-Barr virus in NPC patients

Epstein-Barr virus (EBV) has been used as a paradigm for studying host-virus interactions, not only because of its importance as a human oncogenic virus associated with several malignancies including nasopharyngeal carcinoma (NPC) but also owing to its sophisticated strategies to subvert the host antiviral responses. An understanding of the interplay between EBV and NPC is critical for the development of EBV-targeted immunotherapy. Here, we summarize the current knowledge regarding the host immune responses and EBV immune evasion mechanisms in the context of NPC.

Co-expression of PD-1 and PD-L1 predicts poor outcome in nasopharyngeal carcinoma

Tumor immune evasion is a hallmark of cancer. The programmed death-1/programmed death-ligand 1 (PD-1/PD-L1) pathway has been suggested to play an important role in T cell tolerance and tumor immune escape. In this study, we aimed to evaluate the correlation between the expression of PD-1/PD-L1 and the post-treatment outcome in patients with nasopharyngeal carcinoma (NPC). Formalin-fixed, paraffin-embedded tissue biopsies from 139 patients with histological diagnosis of NPC treated with conventional chemoradiotherapy were studied. By using immunohistochemistry staining, expressions of PD-1 on tumor-infiltrating lymphocyte and PD-L1 on tumor tissue were detected. The staining results were evaluated with H-score. The correlation between PD-1/PD-L1 expression and clinical characteristics and post-treatment outcome were analyzed. PD-1(+) immune cell were present in 52 of these 139 tumors (37.4%). PD-L1 expression was detected in 132 patients (95.0%), which located on tumor tissue. High expression of PD-L1 (median H-score >35) in tumor tissue significantly correlated with a poor prognosis of disease-free survival (P = 0.009). Co-expression of PD-1 and PD-L1 in NPC at diagnosis correlated with the poorest prognosis of disease-free survival (P = 0.038). PD-1/PD-L1 co-expression reflected the selective suppression of cytotoxic lymphocytes in the tumor microenvironment and predicted recurrence and metastasis of NPC after conventional therapies. Blocking this pathway in patients with co-expression of PD-1/PD-L1 provides a potential therapy target for NPC.

Complement receptor 1 expression in peripheral blood mononuclear cells and the association with clinicopathological features and prognosis of nasopharyngeal carcinoma

PURPOSE

Complement receptor 1 (CR1) is induced by Epstein-Barr virus (EBV) and may be a potential biomarker of nasopharyngeal carcinoma (NPC). We conducted the present study to evaluate the association of CR1 expression with clinicopathological features and prognosis of NPC.

METHODS

We enrolled 145 NPC patients and 110 controls. Expression levels of CR1 in peripheral blood mononuclear cells (PBMCs) were detected using quantitative real-time PCR and associations with clinicopathological features and prognosis were examined.

RESULTS

CR1 levels in the NPC group [3.54 (3.34, 3.79)] were slightly higher than those in the controls [3.33 (3.20, 3.47)] (P<0.001). Increased CR1 expression was associated with histology classification (type III vs. type II, P=0.002), advanced clinical stage (P=0.003), high T stage (P=0.017), and poor overall survival (HR, 4.89; 95% CI, 1.23-19.42; P=0.024). However, there were no statistically significant differences in CR1 expression among N or M stages.

CONCLUSION

These findings indicate that CR1 expression in PBMCs may be a new biomarker for prognosis of NPC and a potential therapeutic target.

Therapeutic implications of Epstein-Barr virus infection for the treatment of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is highly endemic in certain regions including the People’s Republic of China and Southeast Asia. Its etiology is unique and multifactorial, involving genetic background, epigenetic, and environment factors, including Epstein–Barr virus (EBV) infection. The presence of EBV in all tumor cells, aberrant pattern of antibodies against EBV antigens in patient sera, and elevated viral DNA in patient circulation as well as nasopharyngeal site underline the role of EBV during NPC development. In NPC tumors, EBV expresses latency type II, where three EBV-encoded proteins, Epstein–Barr nuclear antigen 1, latent membrane protein 1 and 2 (LMP1, 2), are expressed along with BamH1-A rightward reading frame 1, Epstein–Barr virus-encoded small nuclear RNAs, and BamH1-A rightward transcripts. Among all encoded proteins, LMP1 plays a central role in the propagation of NPC. Standard treatment of NPC consists of radiotherapy with or without chemotherapy for early stage, concurrent chemoradiotherapy in locally advanced tumors, and palliative systemic chemotherapy in metastatic disease. However, this standard care has limitations, allowing recurrences and disease progression in a certain proportion of cases. Although the pathophysiological link and molecular process of EBV-induced oncogenesis are not fully understood, therapeutic approaches targeting the virus may increase the cure rate and add clinical benefit. The promising results of early phase clinical trials on EBV-specific immunotherapy, epigenetic therapy, and treatment with viral lytic induction offer new options for treating NPC.

Methods and matrices: approaches to identifying miRNAs for nasopharyngeal carcinoma

Background

Nasopharyngeal carcinoma (NPC) is a solid tumor of the head and neck. Multimodal therapy is highly effective when NPC is detected early. However, due to the location of the tumor and the absence of clinical signs, early detection is difficult, making a biomarker for the early detection of NPC a priority. The dysregulation of small non-coding RNAs (miRNAs) during carcinogenesis is the focus of much current biomarker research. Herein, we examine several miRNA discovery methods using two sample matrices to identify circulating miRNAs (c-miRNAs) associated with NPC.

Methods

We tested two miRNA discovery workflows on two sample sources for miRNAs associated with NPC. In the first workflow, we assumed that NPC tumor tissue would be enriched for miRNAs, so we compared miRNA expression in FFPE from NPC cases and controls using microarray and RNA-Seq technologies. Candidate miRNAs from both technologies were verified by qPCR in FFPE and sera from an independent NPC sample set. In a second workflow, we directly interrogated NPC case and control sera by RNA-Seq for c-miRNAs associated with NPC, with candidate c-miRNAs verified by qPCR in the sera from the same independent NPC sample set.

Results

Both microarray and RNA-Seq narrowed the miRNA signature to 1-5% of the known mature human miRNAs. Moreover, these two methods produced similar results when applied to the same sample type (FFPE), with RNA-Seq additionally indicating “unknown” miRNAs associated with NPC. However, we found different miRNA profiles in NPC sera compared to FFPE using RNA-Seq, with the few overlapping miRNAs found to be significantly up-regulated in FFPE significantly down-regulated in sera (and vice versa). Despite the different miRNA profiles found in FFPE and sera, both profiles strongly associated with NPC, providing two potential sources for biomarker signatures for NPC.

Conclusions

We determined that the direct interrogation of sera by RNA-Seq was the most informative method for identifying a c-miRNA signature associated with NPC. We also showed that there are different miRNA expression profiles associated with NPC for tumor tissue and sera. These results reflect on the methods and meaning of miRNA biomarkers for NPC in tissue and peripheral blood.

Epstein-Barr virus as a paradigm in nasopharyngeal cancer: from lab to clinic

Nasopharyngeal carcinoma (NPC) of the undifferentiated subtype remains endemic in southern China, with a peak incidence in this region approaching 30 cases per 100,000 population per year. Despite advances in chemotherapy and radiation delivery techniques in localized disease, distant metastasis is still common and NPC remains the seventh leading cause of cancer death in the region. There is great need for early diagnosis, developing novel therapies, and identifying patients with localized disease at higher risk of future recurrence or metastasis to appropriately tailor their treatment and improve outcomes. Knowledge of the integral involvement of Epstein-Barr virus (EBV) in the pathogenesis of undifferentiated NPC has been of seminal importance in developing strategies to optimize disease management. The close association with EBV is being evaluated in multiple settings including screening of at-risk populations, disease prognostication, development of targeted therapies, optimizing adjuvant treatment, and early recurrence detection. These translational studies are likely to have an enormous effect on management of undifferentiated NPC and significantly improve the landscape of the disease in years to come.

BamHI-A rightward frame 1, an Epstein-Barr virus-encoded oncogene and immune modulator

Epstein–Barr virus (EBV) causes several benign and malignant disorders of lymphoid and epithelial origin. EBV-related tumors display distinct patterns of viral latent gene expression, of which the BamHI-A rightward frame 1 (BARF1) is selectively expressed in carcinomas, regulated by cellular differentiation factors including ΔNp63α. BARF1 functions as a viral oncogene, immortalizing and transforming epithelial cells of different origin by acting as a mitogenic growth factor, inducing cyclin-D expression, and up-regulating antiapoptotic Bcl-2, stimulating host cell growth and survival. In addition, secreted hexameric BARF1 has immune evasive properties, functionally corrupting macrophage colony stimulating factor, as supported by recent functional and structural data. Therefore, BARF1, an intracellular and secreted protein, not only has multiple pathogenic functions but also can function as a target for immune responses. Deciphering the role of BARF1 in EBV biology will contribute to novel diagnostic and treatment options for EBV-driven carcinomas. Herein, we discuss recent insights on the regulation of BARF1 expression and aspects of structure-function relating to its oncogenic and immune suppressive properties. © 2013 The Authors. Reviews in Medical Virology published by John Wiley & Sons, Ltd.

Phase I trial of recombinant modified vaccinia ankara encoding Epstein-Barr viral tumor antigens in nasopharyngeal carcinoma patients

Epstein-Barr virus (EBV) is associated with several malignancies including nasopharyngeal carcinoma, a high incidence tumor in Chinese populations, in which tumor cells express the two EBV antigens EB nuclear antigen 1 (EBNA1) and latent membrane protein 2 (LMP2). Here, we report the phase I trial of a recombinant vaccinia virus, MVA-EL, which encodes an EBNA1/LMP2 fusion protein designed to boost T-cell immunity to these antigens. The vaccine was delivered to Hong Kong patients with nasopharyngeal carcinoma to determine a safe and immunogenic dose. The patients, all in remission more than 12 weeks after primary therapy, received three intradermal MVA-EL vaccinations at three weekly intervals, using five escalating dose levels between 5 × 10(7) and 5 × 10(8) plaque-forming unit (pfu). Blood samples were taken during prescreening, immediately before vaccination, one week afterward and at intervals up to one year later. Immunogenicity was tested by IFN-γ ELIspot assays using complete EBNA1 and LMP2 15-mer peptide mixes and known epitope peptides relevant to patient MHC type. Eighteen patients were treated, three per dose level one to four and six at the highest dose, without dose-limiting toxicity. T-cell responses to one or both vaccine antigens were increased in 15 of 18 patients and, in many cases, were mapped to known CD4 and CD8 epitopes in EBNA1 and/or LMP2. The range of these responses suggested a direct relationship with vaccine dose, with all six patients at the highest dose level giving strong EBNA1/LMP2 responses. We concluded that MVA-EL is both safe and immunogenic, allowing the highest dose to be forwarded to phase II studies examining clinical benefit.

Professional antigen presenting cells in human herpesvirus 8 infection

Professional antigen presenting cells (APC), i.e., dendritic cells (DC), monocytes/macrophages, and B lymphocytes, are critically important in the recognition of an invading pathogen and presentation of antigens to the T cell-mediated arm of immunity. Human herpesvirus 8 (HHV-8) is one of the few human viruses that primarily targets these APC for infection, altering their cytokine profiles, manipulating their surface expression of MHC molecules, and altering their ability to activate HHV-8-specific T cells. This could be why T cell responses to HHV-8 antigens are not very robust. Of these APC, only B cells support complete, lytic HHV-8 infection. However, both complete and abortive virus replication cycles in APC could directly affect viral pathogenesis and progression to Kaposi's sarcoma (KS) and HHV-8-associated B cell cancers. In this review, we discuss the effects of HHV-8 infection on professional APC and their relationship to the development of KS and B cell lymphomas.

Epstein-Barr virus-encoded BARF1 protein is a decoy receptor for macrophage colony stimulating factor and interferes with macrophage differentiation and activation

Epstein-Barr virus (EBV), like many other persistent herpes viruses, has acquired numerous mechanisms for subverting or evading immune surveillance. This study investigates the role of secreted EBV-encoded BARF1 protein (sBARF1) in creating an immune evasive microenvironment. Wild-type consensus BARF1 was expressed in the human 293 cell line and purified. This native hexameric sBARF1 had inhibitory capacity on macrophage colony stimulating factor (M-CSF)-stimulated, and not on granulocyte macrophage-colony stimulating factor (GM-CSF)-stimulated growth and differentiation of myeloid cells. Antibodies specific to hexameric sBARF1 were able to block this effect. M-CSF was shown to interact with sBARF1 via the protruding N-terminal loops involving Val38 and Ala84. Each BARF1 hexamer was capable of binding three M-CSF dimers. Mutations in the BARF1 loops greatly affected M-CSF interaction, and showed loss of growth inhibition. Analysis of the activation state of the M-CSF receptor c-fms and its downstream kinase pathways showed that sBARF1 prevented M-CSF-induced downstream phosphorylation. Since M-CSF is an important factor in macrophage differentiation, the effect of sBARF1 on the function of monocyte-derived macrophages was evaluated. sBARF1 affected overall survival and morphology and significantly reduced expression of macrophage differentiation surface markers such as CD14, CD11b, CD16, and CD169. Macrophages differentiating in the presence of sBARF1 showed impaired responses to lipopolysaccharide and decreased oxygen radical formation as well as reduced phagocytosis of apoptotic cells. In conclusion, EBV sBARF1 protein is a potent decoy receptor for M-CSF, hampering the function and differentiation of macrophages. These results suggest that sBARF1 contributes to the modulation of immune responses in the microenvironment of EBV-positive carcinomas.

Extracellular vesicles and their convergence with viral pathways

Extracellular vesicles (microvesicles), such as exosomes and shed microvesicles, contain a variety of molecules including proteins, lipids, and nucleic acids. Microvesicles appear mostly to originate from multivesicular bodies or to bud from the plasma membrane. Here, we review the convergence of microvesicle biogenesis and aspects of viral assembly and release pathways. Herpesviruses and retroviruses, amongst others, recruit several elements from the microvesicle biogenesis pathways for functional virus release. In addition, noninfectious pleiotropic virus-like vesicles can be released, containing viral and cellular components. We highlight the heterogeneity of microvesicle function during viral infection, addressing microvesicles that can either block or enhance infection, or cause immune dysregulation through bystander action in the immune system. Finally, endogenous retrovirus and retrotransposon elements deposited in our genomes millions of years ago can be released from cells within microvesicles, suggestive of a viral origin of the microvesicle system or perhaps of an evolutionary conserved system of virus-vesicle codependence. More research is needed to further elucidate the complex function of the various microvesicles produced during viral infection, possibly revealing new therapeutic intervention strategies.

Increased production of nitric oxide correlates with tumor growth in Algerian patients with nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is thought to arise because of chronic inflammation. The correlation between nitric oxide (NO) production, a biomarker of inflammation and NPC development remains unexplored. To investigate this question, we performed a profile analysis on plasma collected from untreated, treated, remissive, cured and relapsing patients. Nitrites were measured to assess NO activity. We observed that increased nitrites concentrations in untreated and relapsing patients associated with tumor development. Moreover, nitrites levels were similar in remissive, cured and healthy individuals. Altogether, our results suggest that NO might be an interesting blood biomarker to monitor tumor growth in NPC patients.

The pathological roles of BART miRNAs in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a distinct type of head and neck cancer prevalent in south-east Asia and southern China, where it constitutes a significant health burden. Although the close association of NPC with Epstein-Barr virus (EBV) infection has been known for more than four decades, the exact role that EBV plays in the pathogenesis of this malignancy is still unclear. While NPC tumours are known to express a number of EBV-encoded proteins, they also express a large number of virus-encoded microRNAs (miRNAs), the most abundant of which are those encoded from the BamHI-A region of the viral genome: the so-called BART miRNAs. miRNAs are small non-coding mRNAs that negatively regulate the expression of various genes at the post-transcriptional level. Accumulating evidence suggests that miRNAs play important roles in tumourigenesis. Here, we review the role of EBV-encoded BART miRNAs in modulating apoptosis and host innate defence mechanisms and their contribution to NPC pathogenesis. The rationale and strategies for therapeutic targeting of BART miRNAs in EBV-infected NPC are also discussed.