Differential cytokine expression in EBV positive peripheral T cell lymphomas

Amphiregulin in infectious diseases: Role, mechanism, and potential therapeutic targets

Amphiregulin (AREG) serves as a ligand for the epidermal growth factor receptor (EGFR) and is involved in vital biological functions, including inflammatory responses, tissue regeneration, and immune system function. Upon interaction with the EGFR, AREG initiates a series of signaling cascades necessary for several physiological activities, such as metabolism, cell cycle regulation, and cellular proliferation. Recent findings have provided evidence for the substantial role of AREG in maintaining the equilibrium of homeostasis in damaged tissues and preserving epithelial cell structure in the context of viral infections affecting the lungs. The development of resistance to influenza virus infection depends on the presence of type 1 cytokine responses. Following the eradication of the pathogen, the lungs are subsequently colonized by several cell types that are linked with type 2 immune responses. These cells contribute to the process of repairing and resolving the tissue injury and inflammation caused by infections. Following influenza infection, the activation of AREG promotes the regeneration of bronchial epithelial cells, enhancing the tissue's structural integrity and increasing the survival rate of infected mice. In the same manner, mice afflicted with influenza experience rapid mortality due to a subsequent bacterial infection in the pulmonary region when both bacterial and viral infections manifest concurrently inside the same host. The involvement of AREG in bacterial infections has been demonstrated. The gene AREG experiences increased transcriptional activity inside host cells in response to bacterial infections caused by pathogens such as Escherichia coli and Neisseria gonorrhea. In addition, AREG has been extensively studied as a mitogenic stimulus in epithelial cell layers. Consequently, it is regarded as a prospective contender that might potentially contribute to the observed epithelial cell reactions in helminth infection. Consistent with this finding, mice that lack the AREG gene exhibit a delay in the eradication of the intestinal parasite Trichuris muris. The observed delay is associated with a reduction in the proliferation rate of colonic epithelial cells compared to the infected animals in the control group. The aforementioned findings indicate that AREG plays a pivotal role in facilitating the activation of defensive mechanisms inside the epithelial cells of the intestinal tissue. The precise cellular sources of AREG in this specific context have not yet been determined. However, it is evident that the increased proliferation of the epithelial cell layer in infected mice is reliant on CD4+ T cells. The significance of this finding lies in its demonstration of the crucial role played by the interaction between immunological and epithelial cells in regulating the AREG-EGFR pathway. Additional research is necessary to delve into the cellular origins and signaling mechanisms that govern the synthesis of AREG and its tissue-protective properties, independent of infection.

Comprehensive Profiling of EBV Gene Expression and Promoter Methylation Reveals Latency II Viral Infection and Sporadic Abortive Lytic Activation in Peripheral T-Cell Lymphomas

Epstein-Barr virus (EBV) latency patterns are well defined in EBV-associated epithelial, NK/T-cell, and B-cell malignancies, with links between latency stage and tumorigenesis deciphered in various studies. In vitro studies suggest that the oncogenic activity of EBV in T-cells might be somewhat different from that in EBV-tropic B lymphoid cells, prompting us to study this much less investigated viral gene expression pattern and its regulation in nine EBV+ peripheral T-cell lymphoma (PTCL) biopsies. Using frozen specimens, RT-PCR showed 6/7 cases with a latency II pattern of EBV gene expression. Analyses of EBNA1 promoter usage and CpG methylation status in these six cases showed that only Qp was used, while Cp, Wp, and Fp were all silent. However, the remaining case showed an exceptionally unique latency III type with lytic activation, as evidenced by EBV lytic clonality and confirmed by the full usage of Cp and Qp as well as weakly lytic Fp and Wp, fully unmethylated Cp and marginally unmethylated Wp. Further immunostaining of the eight cases revealed a few focally clustered LMP1+ cells in 7/8 cases, with rare isolated LMP1+ cells detected in another case. Double immunostaining confirmed that the LMP1+ cells were of the T-cell phenotype (CD3+). In 6/8 cases, sporadically scattered Zta+ cells were detected. Double staining of EBER-ISH with T-cell (CD45RO/UCHL1) or B-cell (CD20) markers confirmed that the vast majority of EBER+ cells were of the T-cell phenotype. Predominant type-A EBV variant and LMP1 30-bp deletion variant were present, with both F and f variants detected. In summary, the EBV gene expression pattern in PTCL was found to be mainly of latency II (BART+EBNA1(Qp)+LMP1+LMP2A+BZLF1+), similar to that previously reported in EBV-infected nasopharyngeal epithelial, NK/T-cell, and Hodgkin malignancies; however, fully lytic infection could also be detected in occasional cases. Rare cells with sporadic immediate-early gene expression were commonly detected in PTCL. These findings have implications for the future development of EBV-targeting therapeutics for this cancer.

Amphiregulin/epidermal growth factor receptor/hypoxia-inducible factor-1α pathway regulates T helper 9 and T cytotoxic 9 cell response in adult patients with infectious mononucleosis

Amphiregulin (AREG)/epidermal growth factor receptor (EGFR) signaling induces hypoxia-inducible factor-1α (HIF-1α), leading to promotion of T helper 9 (Th9) differentiation and anti-tumor functions. However, the role of the AREG/EGFR/HIF-1α pathway in regulating interleukin-9 (IL-9) production by T cells in adult patients with infectious mononucleosis (IM) has not been fully elucidated. Fifty IM patients and 20 controls were enrolled. The percentages of Th9 and T cytotoxic 9 (Tc9) cells, the mRNA relative expressions of the transcription factors of IL-9-secreting T cells, purine-rich nucleic acid binding protein 1 (PU.1) and forkhead box protein O1 (FOXO1), and the levels of IL-9, AREG, EGFR, and HIF-1α were measured. Peripheral blood mononuclear cells from IM patients were stimulated with EGFR inhibitor or exogenous AREG in the presence or absence of anti-HIF-1α. Regulation of the AREG/EGFR/HIF-1α pathway to IL-9 production by T cells was assessed. The percentages of Th9 and Tc9 cells, plasma IL-9 levels, and PU.1 and FOXO1 mRNA expressions were elevated in IM patients. Plasma levels of AREG and HIF-1α were also increased in IM patients. AREG levels correlated positively with the percentages of Th9 and Tc9 cells in IM patients. Inhibition of EGFR suppressed IL-9-producing T cell differentiation and HIF-1α production. Exogenous AREG stimulation not only induced EGFR and HIF-1α expression but also promoted IL-9-secreting T cell differentiation. Neutralization of HIF-1α abrogated AREG/EGFR-induced Th9 and Tc9 differentiation in IM patients. The current data suggested that the AREG/EGFR/HIF-1α pathway contributed to the elevation of Th9 and Tc9 differentiation in IM patients.

Epstein-Barr Virus-Induced Metabolic Rearrangements in Human B-Cell Lymphomas

Tumor metabolism has been the object of several studies in the past, leading to the pivotal observation of a consistent shift toward aerobic glycolysis (so-called Warburg effect). More recently, several additional investigations proved that tumor metabolism is profoundly affected during tumorigenesis, including glucose, lipid and amino-acid metabolism. It is noticeable that metabolic reprogramming can represent a suitable therapeutic target in many cancer types. Epstein–Barr virus (EBV) was the first virus linked with cancer in humans when Burkitt lymphoma (BL) was described. Besides other well-known effects, it was recently demonstrated that EBV can induce significant modification in cell metabolism, which may lead or contribute to neoplastic transformation of human cells. Similarly, virus-induced tumorigenesis is characterized by relevant metabolic abnormalities directly induced by the oncoviruses. In this article, the authors critically review the most recent literature concerning EBV-induced metabolism alterations in lymphomas.

Programmed death-ligand 1 and its soluble form are highly expressed in nasal natural killer/T-cell lymphoma: a potential rationale for immunotherapy

Nasal natural killer/T-cell lymphoma (NNKTL) is an aggressive neoplasm with poor therapeutic responses and prognosis. The programmed death-1/programmed death-ligand 1 (PD-1/PD-L1) pathway plays an important role in immune evasion of tumor cells through T-cell exhaustion. The aim of the present study was to examine the expression of PD-L1 and PD-1 molecules in NNKTL. We detected the expression of PD-L1 in biopsy samples from all of the NNKTL patients studied. PD-L1 was found on both malignant cells and tumor-infiltrating macrophages, while PD-1-positive mononuclear cells infiltrated the tumor tissues in 36% of patients. Most significantly, soluble PD-L1 (sPD-L1) was present in sera of NNKTL patients at higher levels as compared to healthy individuals and the levels of serum sPD-L1 in patients positively correlated with the expression of PD-L1 in lymphoma cells of tumor tissues. In addition, the high-sPD-L1 group of patients showed significantly worse prognosis than the low-sPD-L1 group. Furthermore, we confirmed that membrane and soluble PD-L1 was expressed on the surface and in the culture supernatant, respectively, of NNKTL cell lines. The expression of PD-L1 was observed in tumor tissues and sera from a murine xenograft model inoculated with an NNKTL cell line. Our results suggest that sPD-L1 could be a prognostic predictor for NNKTL and open up the possibility of immunotherapy of this lymphoma using PD-1/PD-L1 axis inhibitors.

BZLF1 Attenuates Transmission of Inflammatory Paracrine Senescence in Epstein-Barr Virus-Infected Cells by Downregulating Tumor Necrosis Factor Alpha

Recent studies have shown that inflammatory responses trigger and transmit senescence to neighboring cells and activate the senescence-associated secretory phenotype (SASP). Latent Epstein-Barr virus (EBV) infection induces increased secretion of several inflammatory factors, whereas lytic infections evade the antiviral inflammatory response. However, the changes in and roles of the inflammatory microenvironment during the switch between EBV life cycles remain unknown. In the present study, we demonstrate that latent EBV infection in EBV-positive cells triggers the SASP in neighboring epithelial cells. In contrast, lytic EBV infection abolishes this phenotype. BZLF1 attenuates the transmission of paracrine senescence during lytic EBV infection by downregulating tumor necrosis factor alpha (TNF-α) secretion. A mutant BZLF1 protein, BZLF1Δ207-210, that cannot inhibit TNF-α secretion while maintaining viral transcription, fails to block paracrine senescence, whereas a neutralizing antibody against TNF-α is sufficient to restore its inhibition. Furthermore, latent EBV infection induces oxidative stress in neighboring cells, while BZLF1-mediated downregulation of TNF-α reduces reactive oxygen species (ROS) levels in neighboring cells, and ROS scavengers alleviate paracrine senescence. These results suggest that lytic EBV infection attenuates the transmission of inflammatory paracrine senescence through BZLF1 downregulation of TNF-α secretion and alters the inflammatory microenvironment to allow virus propagation and persistence.

IMPORTANCE

The senescence-associated secretory phenotype (SASP), an important tumorigenic process, is triggered and transmitted by inflammatory factors. The different life cycles of Epstein-Barr virus (EBV) infection in EBV-positive cells employ distinct strategies to modulate the inflammatory response and senescence. The elevation of inflammatory factors during latent EBV infection promotes the SASP in uninfected cells. In contrast, during the viral lytic cycle, BZLF1 suppresses the production of TNF-α, resulting in the attenuation of paracrine inflammatory senescence. This finding indicates that EBV evades inflammatory senescence during lytic infection and switches from facilitating tumor-promoting SASP to generating a virus-propagating microenvironment, thereby facilitating viral spread in EBV-associated diseases.

Epstein-Barr Virus BZLF1-Mediated Downregulation of Proinflammatory Factors Is Essential for Optimal Lytic Viral Replication

Elevated secretion of inflammatory factors is associated with latent Epstein-Barr virus (EBV) infection and the pathology of EBV-associated diseases; however, knowledge of the inflammatory response and its biological significance during the lytic EBV cycle remains elusive. Here, we demonstrate that the immediate early transcriptional activator BZLF1 suppresses the proinflammatory factor tumor necrosis factor alpha (TNF-α) by binding to the promoter of TNF-α and preventing NF-κB activation. A BZLF1Δ207-210 mutant with a deletion of 4 amino acids (aa) in the protein-protein binding domain was not able to inhibit the proinflammatory factors TNF-α and gamma interferon (IFN-γ) and reduced viral DNA replication with complete transcriptional activity during EBV lytic gene expression. TNF-α depletion restored the viral replication mediated by BZLF1Δ207-210. Furthermore, a combination of TNF-α- and IFN-γ-neutralizing antibodies recovered BZLF1Δ207-210-mediated viral replication, indicating that BZLF1 attenuates the antiviral response to aid optimal lytic replication primarily through the inhibition of TNF-α and IFN-γ secretion during the lytic cycle. These results suggest that EBV BZLF1 attenuates the proinflammatory responses to facilitate viral replication.

IMPORTANCE

The proinflammatory response is an antiviral and anticancer strategy following the complex inflammatory phenotype. Latent Epstein-Barr virus (EBV) infection strongly correlates with an elevated secretion of inflammatory factors in a variety of severe diseases, while the inflammatory responses during the lytic EBV cycle have not been established. Here, we demonstrate that BZLF1 acts as a transcriptional suppressor of the inflammatory factors TNF-α and IFN-γ and confirm that BZLF1-facilitated escape from the TNF-α and IFN-γ response during the EBV lytic life cycle is required for optimal viral replication. This finding implies that the EBV lytic cycle employs a distinct strategy to evade the antiviral inflammatory response.

Epstein-Barr Virus-associated lymphoproliferative disorders: experimental and clinical developments

Epstein-Barr Virus (EBV), the first human virus related to oncogenesis, was initially identified in a Burkitt lymphoma cell line in 1964. EBV infects over 90% of the world's population. Most infected people maintain an asymptomatic but persistent EBV infection lifelong. However, in some individuals, EBV infection has been involved in the development of cancer and autoimmune disease. Nowadays, oncogenic potential of EBV has been intensively studied in a wide range of human neoplasms, including Hodgkin's lymphoma (HL), non-Hodgkin's lymphoma (NHL), nasopharyngeal carcinoma (NPC), gastric carcinoma (GC), etc. EBV encodes a series of viral protein and miRNAs, promoting its persistent infection and the transformation of EBV-infected cells. Although the exact role of EBV in the oncogenesis remains to be clarified, novel diagnostic and targeted therapeutic approaches are encouraging for the management of EBV-related malignancies. This review mainly focuses on the experimental and clinical advances of EBV-associated lymphoproliferative disorders.

Transcriptome analysis of porcine thymus following porcine cytomegalovirus infection

Porcine cytomegalovirus (PCMV) is a major immunosuppressive virus that mainly affects the immune function of T lymphocytes and macrophages. Despite being widely distributed around the world, no significantly different PCMV serotypes have been found. Moreover, the molecular immunosuppressive mechanisms of PCMV, along with the host antiviral mechanisms, are still not well characterized. To understand the potential impact of PCMV on the function of immune organs, we examined the transcriptome of PCMV-infected thymuses by microarray analysis. We identified 5,582 genes that were differentially expressed as a result of PCMV infection. Of these, 2,161 were upregulated and 3,421 were downregulated compared with the uninfected group. We confirmed the expression of 13 differentially expressed immune-related genes using quantitative real-time RT-PCR, and further confirmed the expression of six of those cytokines by western blot. Gene ontology, gene interaction networks, and KEGG pathway analysis of our results indicated that PCMV regulates multiple functional pathways, including the immune system, cellular and metabolic processes, networks of cytokine-cytokine receptor interactions, the TGF-β signaling pathway, the lymphocyte receptor signaling pathway, and the TNF-α signaling pathway. Our study is the first comprehensive attempt to explore the host transcriptional response to PCMV infection in the porcine immune system. It provides new insights into the immunosuppressive molecular mechanisms and pathogenesis of PCMV. This previously unrecognized endogenous antiviral mechanism has implications for the development of host-directed strategies for the prevention and treatment of immunosuppressive viral diseases.

Monocytes enhance cell proliferation and LMP1 expression of nasal natural killer/T-cell lymphoma cells by cell contact-dependent interaction through membrane-bound IL-15

Nasal natural killer (NK)/T-cell lymphoma (NNKTL) is an Epstein-Barr virus (EBV)-related malignancy with poor prognosis and has distinct histological features characterized by angiocentric and polymorphous lymphoreticular infiltrates including inflammatory cells such as granulocytes, monocytes, macrophages and lymphocytes. Here, we show that the monocytes enhance proliferation as well as LMP1 expression of NNKTL cells by cell contact-dependent interaction through membrane-bound interleukin (IL)-15. We used two EBV-positive NK-cell lines, SNK6 and KAI3, which originated from two patients-SNK6 from a patient with NNKTL and KAI3 from a patient with a severe mosquito allergy. We cocultured the cell lines with granulocytes or monocytes and examined whether proliferation, survival and LMP1 expression of the cells changed. Although cocultured granulocytes did not affect proliferation, survival or LMP1 expression of the cells, cocultured monocytes enhanced both proliferation and LMP1 expression in a dose-dependent manner. These phenomena were not seen when monocytes were placed in a separate chamber. Moreover, the monocyte-inducible proliferation and LMP1 expression were inhibited by treatment with an antibody against IL-15. Furthermore, production of interferon-gamma-inducible protein (IP)-10 were enhanced by coculture with monocytes and were inhibited by the antibody. Immunohistological studies confirmed that a number of infiltrating CD14-positive monocytes contacted CD56-positive lymphoma cells in all of 20 NNKTL tissues tested. These results suggest that monocytes enhance cell growth as well as LMP1 expression of NNKTL cells by cell contact-dependent interaction through membrane-bound IL-15. In the microenvironment of NNKTL tissue, a positive feedback loop of interaction between lymphoma cells and monocytes may be present and contribute to lymphoma progression.

Interleukin-2 induces NF-kappaB activation through BCL10 and affects its subcellular localization in natural killer lymphoma cells

Deregulation of nuclear factor (NF)-kappaB signalling is common in cancers and is essential for tumourigenesis. Constitutive NF-kappaB activation in extranodal natural killer (NK)-cell lymphoma, nasal type (ENKL) is known to be associated with aberrant nuclear translocation of BCL10. Here we investigated the mechanisms leading to NF-kappaB activation and BCL10 nuclear localization in ENKLs. Given that ENKLs are dependent on T-cell-derived interleukin-2 (IL2) for cytotoxicity and proliferation, we investigated whether IL2 modulates NF-kappaB activation and BCL10 subcellular localization in ENKLs. In the present study, IL2-activated NK lymphoma cells were found to induce NF-kappaB activation via the PI3K/Akt pathway, leading to an increase in the entry of G(2)/M phase and concomitant transcription of NF-kappaB-responsive genes. We also found that BCL10, a key mediator of NF-kappaB signalling, participates in the cytokine receptor-induced activation of NF-kappaB. Knockdown of BCL10 expression resulted in deficient NF-kappaB signalling, whereas Akt activation was unaffected. Our results suggest that BCL10 plays a role downstream of Akt in the IL2-triggered NF-kappaB signalling pathway. Moreover, the addition of IL2 to NK cells led to aberrant nuclear translocation of BCL10, which is a pathological feature of ENKLs. We further show that BCL10 can bind to BCL3, a transcriptional co-activator and nuclear protein. Up-regulation of BCL3 expression was observed in response to IL2. Similar to BCL10, the expression and nuclear translocation of BCL3 were induced by IL2 in an Akt-dependent manner. The nuclear translocation of BCL10 was also dependent on BCL3 because silencing BCL3 by RNA interference abrogated this translocation. We identified a critical role for BCL10 in the cytokine receptor-induced NF-kappaB signalling pathway, which is essential for NK cell activation. We also revealed the underlying mechanism that controls BCL10 nuclear translocation in NK cells. Our findings provide insight into a molecular network within the NF-kappaB signalling pathway that promotes the pathogenesis of NK cell lymphomas.

Cytokine levels in patients with Epstein-Barr virus associated laryngeal carcinoma

OBJECTIVE

Some researchers have suggested that Epstein-Barr virus may play a role in the pathogenesis of laryngeal malignancies. In order to clarify the role of cytokines in this disease context, the current study aimed to determine the serum levels of cytokines in Epstein-Barr virus DNA positive patients with laryngeal carcinoma.

SUBJECTS

The study included 10 patients with diagnosed laryngeal carcinoma and Epstein-Barr virus DNA positive tumour tissue samples. The control group comprised 10 Epstein-Barr virus DNA negative patients diagnosed with laryngeal carcinoma, 10 patients with acute Epstein-Barr virus infection and 10 healthy individuals.

METHOD

Serum cytokine levels were determined by enzyme-linked immunosorbent assay.

RESULTS

The Epstein-Barr virus DNA positive and negative laryngeal carcinoma patients showed no differences regarding serum levels of the following cytokines: interleukins 1beta, 2, 6 and 12, tumour necrosis factor alpha, and interferon gamma. However, serum levels of interleukin 10 and transforming growth factor beta1 were significantly higher in Epstein-Barr virus DNA positive laryngeal carcinoma patients compared with Epstein-Barr virus DNA negative laryngeal carcinoma patients (p < 0.05).

CONCLUSION

Our results suggest that the cytokines interleukin 10 and transforming growth factor beta1 may act as growth factors in Epstein-Barr virus related laryngeal carcinoma. These cytokines may thus represent potential targets for molecular therapeutic treatment for laryngeal carcinoma; they may also be useful as indicators of disease prognosis.

Serum adiponectin as a predictor of childhood non-Hodgkin's lymphoma: a nationwide case-control study

PURPOSE

To our knowledge, this is the first study exploring the association of childhood non-Hodgkin's lymphoma (NHL) with serum adiponectin and leptin levels in a nationwide case-control series. In addition, expression of adiponectin receptors in NHL specimens was assessed, and the association between adipokines and childhood NHL survival and prognosis was examined.

PATIENTS AND METHODS

We studied 121 incident childhood (0 to 14 years) NHL cases registered in the Nationwide Registry for Childhood Hematological Malignancies (1996 to 2006) and an equal number of matched controls, for whom sociodemographic, lifestyle, prenatal characteristics, and fasting blood serums were collected. Serum adiponectin and leptin levels were determined. Immunohistochemisty for adiponectin receptors expression was performed on commercially available adult NHL specimens (n = 30) and in a subset of childhood NHL cases (n = 6) that were available. Summary statistics, multiple conditional logistic regression analyses, and survival analysis were performed.

RESULTS

Higher serum adiponectin, but not leptin, levels were independently associated with childhood NHL (odds ratio, 1.82; 95% CI, 1.30 to 2.56), after adjusting for obesity and established risk factors. Higher adiponectin levels at diagnosis were positively associated with relapse and poor survival, but hormone levels did not differ among NHL subtypes. Adiponectin receptors 1 and 2 were present in 90% and 57% of adult samples and in 83% and 100% of childhood NHL samples, respectively.

CONCLUSION

Elevated serum adiponectin, but not leptin, levels are independently associated with childhood NHL and poor prognosis. Adiponectin receptors are expressed in NHL, suggesting that adiponectin may represent not only a potential clinically significant diagnostic and prognostic marker but also a molecule that may be implicated in NHL pathogenesis.

Epstein-Barr Virus Negative Clonal Plasma Cell Proliferations and Lymphomas in Peripheral T-cell Lymphomas

Clonal B-cell populations have been described in peripheral T-cell lymphomas (PTCL) as secondary Epstein-Barr virus (EBV) driven B-cell expansions that may evolve to an overt B-cell lymphoma. EBV-negative B-cell proliferations associated with T-cell lymphomas are uncommon and not well characterized. We studied 15 patients who developed an EBV-negative B-cell proliferation or malignant lymphoma associated with PTCL. The T-cell tumors were 8 PTCL, not otherwise specified, 4 angioimmunoblastic T-cell lymphomas, and 3 cutaneous PTCL. The B-cell component was intermingled with the PTCL in all patients and it was classified as clonal/monotypic plasma cell proliferation in 8 lesions, clonal/monotypic large B-cell proliferation in 4 patients, and B-cell lymphoma with plasmacytic/plasmablastic differentiation in 3 patients. Two patients had 2 clonally unrelated plasma cell proliferations associated with the same PTCL. All cases showed cytoplasmic Ig light chain restriction. Clonal IgH and T-cell receptor rearrangements were detected in 11/12 and 11/13 cases examined, respectively. EBV, cytomegalovirus, and HHV-8 were not observed in any of the examined cases. Sequential samples in 7 patients showed persistence of the PTCL and the B-cell component in 4, the PTCL without the B-cell lymphoma in 2, and progression of the B-cell neoplasm in 1. Patients followed an aggressive clinical course similar to conventional PTCL. In conclusion, EBV-negative clonal or mononotypic B-cell proliferations in patients with PTCL present with a spectrum of lesions ranging from plasma cell proliferations to overt lymphomas with plasmacytic/plasmablastic features. The distinctive features of these patients suggest that these lesions represent a specific phenomenon in PTCL.

NK-cell lymphomas and leukemias: a spectrum of tumors with variable manifestations and immunophenotype

Natural killer (NK) cells are lymphocytes that have some phenotypic and functional similarities to cytotoxic T cells but do not express the T-cell receptor complex. NK-cell malignancies may be localized or disseminated at initial examination, and most behave aggressively. The variable presentation of NK-cell lymphomas and leukemias suggests that they represent a spectrum of disease, with Epstein-Barr virus (EBV) implicated in the pathogenesis of most cases. Using cases presented in Session 10 of the 2005 Society for Hematopathology/European Association for Haematopathology Workshop on T-cell and NK-cell malignancies, we discuss outstanding issues in the classification and diagnosis of NK-cell malignancies. These difficulties are related to unusual sites of manifestation, atypical immunophenotypic features, and EBV+ T-cell tumors that resemble classical extranodal NK/T-cell lymphoma, nasal-type (EN-NK/T-NT). Although some of these cases can be grouped into ENNK/T-NT, classification of tumors that have atypical or discordant features will remain controversial, particularly when EBV is absent.

Interleukin-10 gene polymorphism influences the prognosis of T-cell non-Hodgkin lymphomas

Interleukin-10 (IL-10) is one of the cytokines implicated in the pathogenesis of diffuse large B-cell lymphoma (DLBCL) in which it acts as auto/paracrine growth factor for lymphoma growth. T-cell non-Hodgkin lymphoma (NHL) is a heterogeneous disease, the biological basis of which is not fully understood. Some evidence suggests that IL-10 might be associated with the progression of T-cell NHLs and that IL-10 may be involved in a rescue effect, protecting T cells from apoptotic cell death associated with upregulated bcl-2 expression. The current study evaluated the impact of IL-10 gene (IL10) polymorphism on the response to chemotherapy and survival in T-cell NHL. IL10 polymorphisms were determined in 108 patients with T-cell NHL. The response to chemotherapy was not dependent on IL10 polymorphism, while survival differed significantly according to IL10 polymorphism. The group with ATA haplotype showed superior overall survival (61.2 +/- 5.9% vs. 21.2 +/- 11.7%, P = 0.001) and failure-free survival (35.0 +/- 5.7% vs. 13.2 +/- 8.7%, P = 0.001) compared to those without ATA haplotype. The ATA haplotype was identified as a favourable prognostic factor compared to non-ATA haplotype (P = 0.037, hazard ratio 2.1), together with international prognostic index (IPI) in a multivariate model for overall survival. In conclusion, IL10 polymorphism may affect the survival of T-cell NHL patients.

Concomitant increase of LMP1 and CD25 (IL-2-receptor alpha) expression induced by IL-10 in the EBV-positive NK lines SNK6 and KAI3

Extranodal, nasal NK/T-cell lymphomas are regularly Epstein-Barr virus (EBV)-positive, with a type II latency pattern, expressing thus EBNA-1 and LMP1. The contribution of EBV to the tumor development is not known. Similarly to normal natural killer (NK) cells, cell lines derived from malignancies with a NK phenotype require IL-2 for in vitro proliferation. In our effort to explore the contribution of EBV, particularly the role of the LMP1 protein, to the pathogenesis of the NK lymphoma we found that its expression, studied in the NK-lines SNK6 and KAI3, depended on the supply of IL-2 or other cytokines. In the absence of IL-2 other cytokines, such as IL-10 and IFN-gamma, could maintain LMP1, but the cells did not proliferate. When grown in IL-2, the SNK6 cells produced IL-10 and IFN-gamma, and these cytokines mediated the expression of LMP1. IL-10 treatment enhanced, while IFN-gamma receptor blocking antibody reduced, the expression of CD25 and CD54 in the EBV-positive, but not in the EBV-negative lines. IL-10 treated cells required lower amount of IL-2 for proliferation compared to the untreated cells. This effect was seen only with the EBV-positive NK lines in which LMP1 and CD25 were concomitantly upregulated. By this mechanism EBV could have an important role in the development of NK lymphoma since the inflammatory component in the tumor tissue can provide these cytokines.

Epstein-Barr virus and cancer

EBV was the first human virus to be directly implicated in carcinogenesis. It infects >90% of the world's population. Although most humans coexist with the virus without serious sequelae, a small proportion will develop tumors. Normal host populations can have vastly different susceptibility to EBV-related tumors as demonstrated by geographical and immunological variations in the prevalence of these cancers. EBV has been implicated in the pathogenesis of Burkitt's lymphoma, Hodgkin's disease, non-Hodgkin's lymphoma, nasopharyngeal carcinoma, and lymphomas, as well as leiomyosarcomas arising in immunocompromised individuals. The presence of this virus has also been associated with epithelial malignancies arising in the gastric region and the breast, although some of this work remains in dispute. EBV uses its viral proteins, the actions of which mimic several growth factors, transcription factors, and antiapoptotic factors, to usurp control of the cellular pathways that regulate diverse homeostatic cellular functions. Recent advances in antiviral therapeutics, application of monoclonal antibodies, and generation of EBV-specific CTLs are beginning to show promise in the treatment of EBV-related disorders.

Differential chemokine, chemokine receptor and cytokine expression in Epstein-Barr virus-associated lymphoproliferative diseases

T cell immunity plays an important role in the clinicopathology of Epstein-Barr virus (EBV)-associated diseases. Acute EBV-induced infectious mononucleosis (IM) is a common self-limiting disease, however, other EBV-associated diseases, including chronic active EBV infection (CAEBV), NK cell lymphoma (NKL), and Hodgkin's lymphoma (HL), exhibit distinct clinical features. Chemokines are members of a family of small-secreted proteins. The relationships between chemokines and the chemokine receptor (R) are thought to be important for selectivity of local immunity. Some chemokines, chemokine R and cytokines closely associate with the T cell subtypes, Th1 and Th2 T cells and cytotoxic cells. To clarify the role of T cell immunity in EBV-associated diseases, we conducted gene expression profiling, using chemokine, chemokine R and cytokine DNA chips. Compared to EBV negative non-specific lymphadenitis, CAEBV and NKL exhibited diffuse down- and up-regulation, respectively, of these gene profiles. IM had a predominantly Th1-type profile, whereas HL had a mixed Th1/Th2-type profile. Reduction of the Th1-type cytokine interferon gamma (IFN-gamma) in CAEBV was confirmed by Reverse transcriptase-polymerase chain reaction, whereas IFN-gamma expression was markedly enhanced in NKL, and moderately enhanced in IM. Compared to IM, CAEBV showed slight elevation of "regulated upon activation, normal T expressed and secreted" (RANTES), but almost all other genes assayed were down-regulated. NKL exhibited elevated expression of numerous genes, particularly IFN-gamma-inducible-10 (IP-10) and monokine induced by IFN-gamma (MIG). HL showed variable elevated and reduced expression of various genes, with increased expression of IL-13 receptor and MIG. Our study demonstrated the enormous potential of gene expression profiling for clarifying the pathogenesis of EBV-associated diseases.

The role of Epstein-Barr virus and elevated levels of tumor necrosis factor in determining prognosis in Asian peripheral T-cell lymphomas

Evidence of Epstein-Barr virus (EBV) infection in patients continues to be associated with the development of various lymphomas, and EBV genomic regions are detected in some lymphoma cells. Its role in causality and progression of disease versus the role of a passenger continues to be debated. Several reports of Asian T-cell lymphomas have also associated these diseases with evidence of EBV infections. Asian T-cell lymphomas are clinically distinct from Western T-cell lymphoma, and are also associated with increased levels of cytokine production, including tumor necrosis factor (TNF). The current study reports correlations of EBV + T-cell lymphoma with higher levels of TNF, and suggests some prognostic correlations.

Epstein-barr virus latent membrane protein-1 mediates upregulation of tumor necrosis factor-alpha in EBV-infected T cells: implications for the pathogenesis of hemophagocytic syndrome

The infection of human T cells by Epstein-Barr virus (EBV) may result in a fatal hemophagocytic syndrome (HS). We have previously shown that EBV can selectively upregulate the tumor necrosis factor-alpha (TNFalpha) gene and lead to activation of macrophages in a manner similar to the pathobiology of HS in EBV-infected T lymphoproliferative disorders (LPDs). This study was designed to further clarify the specific EBV gene product(s) responsible for TNFalpha upregulation. RT-PCR analysis of EBV gene expression was performed on 2 CR2-transfected EBV-infected T lymphoma lines and 2 EBV-infected B cell lines. To identify the EBV gene responsible for upregulation of TNFalpha, 2 reporter recombinant plasmids, pTNF-CAT and pTNFalpha-Luc, were then constructed and cotransfected with the expression plasmids of the EBV latent and lytic genes (EBNA-1, EBNA-2, LMP-1, LMP-2A, and BZLF-1) in both T and B cell lines. Analyses using ELISA and Western blotting were further performed to detect the secreted TNFalpha. The results revealed that EBNA-1 and LMP-1 were consistently expressed in EBV-infected T cell lines (type II latency), while a type III latency with expression of EBNA-1, EBNA-2, LMP-1, and lytic BZLF transcripts was detected in EBV-infected B cell lines. LMP-1 was demonstrated to be the only EBV gene product to transactivate the TNFalpha gene, and this phenomenon was observed only in T, not in B, cells. Enhanced secretion of TNF-alpha protein was also detected in LMP1-transfected T cell lines. We concluded that LMP1 is the candidate protein in the upregulation of the TNFalpha gene in T cells and is probably responsible for the pathogenesis of HS in EBV-infected T lymphoproliferative disorders.

Quantitative analysis of cell-free Epstein-Barr virus genome copy number in patients with EBV-associated hemophagocytic lymphohistiocytosis

To determine whether the EBV genome content in serum or plasma reflects clinical features and outcome in EBV-associated hemophagocytic lymphohistiocytosis (EBV-HLH), we quantified the cell-free EBV genome copy number by real-time PCR in 38 patients with EBV-HLH, and compared this to the values from 15 patients with infectious mononucleosis (IM). The median (range) cell-free EBV genome copy number at diagnosis was 3.0 x 10(3) (undetectable -5.5 x 10(7)) copies/ml in EBV-HLH, which was significantly higher than the 6.6 x 10(1) (undetectable -1.0 x 10(3)) copies/ml in IM (P = 0.0008). We serially analyzed cell-free EBV genome copy number in 10 cases of EBV-HLH up to 4 months from diagnosis. In four patients who achieved remission, the EBV genome became undetectable soon after starting therapy. In the remaining six patients who responded poorly to therapy, the EBV genome copy number in the serum or plasma remained at high levels except for one case. In addition, we confirmed that the EBV genome became undetectable after hematopoietic stem cell transplantation in 4 EBV-HLH cases. These results suggest that the quantitative analysis of cell-free EBV genome copy number is useful for evaluating disease activity and for predicting the response to therapy in EBV-HLH.

Expression of HLA class I, beta(2)-microglobulin, TAP1 and IL-10 in Epstein-Barr virus-associated nasal NK/T-cell lymphoma: Implications for tumor immune escape mechanism

Several mechanisms of immune escape might be in operation in Epstein-Barr virus (EBV)-associated nasal NK/T-cell lymphoma. We have previously shown the downregulation of the immunogenic EBV nuclear antigens by alternative promoter usage and the preferential selection of the deletion genotype of latent membrane protein 1 in nasal lymphoma. To understand further the strategies used for immune escape by this tumor, we examined by immunohistochemistry HLA class I expression in 15 cases using frozen sections, along with beta(2)-microglobulin and transporter associated with antigen processing 1 (TAP1) expression in 39 cases using paraffin sections. All nasal NK/T-cell lymphomas showed positive staining for HLA class I, beta(2)-microglobulin and TAP1 on most tumor cells, except for two cases (5%) in which most of the tumor cells lacked beta(2)-microglobulin staining. We next immunostained for interleukin-10 on frozen sections in 13 cases, all of which showed strong expression by most tumor cells. Transcription of human interleukin-10 but not EBV BCRF1 (viral interleukin-10) was identified by reverse transcriptase-polymerase chain reaction in these nasal NK/T-cell lymphomas. Overall, our data suggest that global downregulation of HLA class I or TAP1 rarely accounts for the ability of nasal NK/T-cell lymphoma to evade immunosurveillance and that other immune escape mechanisms may be operating in nasal NK/T-cell lymphoma, such as production of interleukin-10 to suppress the local immune response.