EBV counteracts IL-21-induced apoptosis in an EBV-positive diffuse large B-cell lymphoma cell line

Epstein‒Barr virus-associated cellular immunotherapy

Epstein‒Barr virus (EBV) is a human herpes virus that is saliva-transmissible and universally asymptomatic. It has been confirmed that more than 90% of the population is latently infected with EBV for life. EBV can cause a variety of related cancers, such as nasopharyngeal carcinoma, diffuse large B-cell lymphoma, and Burkitt lymphoma. Currently, many clinical studies have demonstrated that EBV-specific cytotoxic T lymphocytes and other cell therapies can be safely and effectively transfused to prevent and treat some diseases caused by EBV. This review will mainly focus on discussing EBV-specific cytotoxic T lymphocytes and will touch on therapeutic EBV vaccines and chimeric antigen receptor T-cell therapy briefly.

EBV dUTPase: A Novel Modulator of Inflammation and the Tumor Microenvironment in EBV-Associated Malignancies

There is increasing evidence that put into question the classical dogma that the Epstein-Barr virus (EBV) exists in cells as either a lytic virus in which new progeny is produced or in a latent state in which no progeny is produced. Notably, a third state has now been described, known as the abortive-lytic phase, which is characterized by the expression of some immediate early (IE) and early (E) genes, but no new virus progeny is produced. While the function of these IE and E gene products is not well understood, several recent studies support the concept they may contribute to tumor promotion by altering the tumor microenvironment (TME). The mechanisms by which these viral gene products may contribute to tumorigenesis remain unclear; however, it has been proposed that some of them promote cellular growth, immune evasion, and/or inhibit apoptosis. One of these EBV early gene products is the deoxyuridine triphosphate nucleotidohydrolase (dUTPase) encoded by BLLF3, which not only contributes to the establishment of latency through the production of activin A and IL-21, but it may also alter the TME, thus promoting oncogenesis.

Cytokine Based Immunotherapy for Cancer and Lymphoma: Biology, Challenges and Future Perspectives

Cytokines regulate both the innate and adaptive immune responses to cancer. Although antitumor activity has been seen for several cytokines in preclinical models, they have had limited success as single therapeutic agents in clinical trials of cancer immunotherapy. However, the possible combinations of cytokines with other immune therapeutics and the advancement in genetic engineering, synthetic biology and cellular and immune therapy has led to the revival of interest in cytokines as anticancer agents. This article will review several immunostimulatory cytokines with anticancer activity, focusing on the those that have been studied in treatment of lymphoma and highlighting recent advances of potential clinical relevance.

IL-21 Stimulates the expression and activation of cell cycle regulators and promotes cell proliferation in EBV-positive diffuse large B cell lymphoma

The clinical features of EBV-positive diffuse large B cell lymphoma (DLBCL) indicate a poorer prognosis than EBV-negative DLBCL. Currently, there is no efficacious drug for EBV-positive DLBCL. The cytokine interleukin-21 (IL-21) has been reported to be pro-apoptotic in DLBCL cell lines and is being explored as a new therapeutic strategy for this type of lymphomas. However, our previous studies showed that IL-21 stimulation of EBV-positive DLBCL cell lines leads to increased proliferation. Here, analysis of a rare clinical sample of EBV-positive DLBCL, in combination with a NOD/SCID mouse xenograft model, confirmed the effect of IL-21 on the proliferation of EBV-positive DLBCL cells. Using RNA-sequencing, we identified the pattern of differentially-expressed genes following IL-21 treatment and verified the expression of key genes at the protein level using western blotting. We found that IL-21 upregulates expression of the host MYC and AP-1 (composed of related Jun and Fos family proteins) and STAT3 phosphorylation, as well as expression of the viral LMP-1 protein. These proteins are known to promote the G1/S phase transition to accelerate cell cycle progression. Furthermore, in NOD/SCID mouse xenograft model experiments, we found that IL-21 treatment increases glucose uptake and angiogenesis in EBV-positive DLBCL tumours. Although more samples are needed to validate these observations, our study reconfirms the adverse effects of IL-21 on EBV-positive DLBCL, which has implications for the drug development of DLBCL.

Epstein-Barr virus (EBV) provides survival factors to EBV+ diffuse large B-cell lymphoma (DLBCL) lines and modulates cytokine induced specific chemotaxis in EBV+ DLBCL

Diffuse large B-cell lymphoma (DLBCL), the most common type of malignant lymphoma, accounts for 30% of adult non-Hodgkin lymphomas. Epstein-Barr virus (EBV) -positive DLBCL of the elderly is a newly recognized subtype that accounts for 8-10% of DLBCLs in Asian countries, but is less common in Western populations. Five DLBCL-derived cell lines were employed to characterize patterns of EBV latent gene expression, as well as response to cytokines and chemotaxis. Interleukin-4 and interleukin-21 modified LMP1, EBNA1 and EBNA2 expression depending on cell phenotype and type of EBV latent programme (type I, II or III). These cytokines also affected CXCR4- or CCR7-mediated chemotaxis in two of the cell lines, Farage (type III) and Val (type II). Further, we investigated the effect of EBV by using dominant-negative EBV nuclear antigen 1(dnEBNA1) to eliminate EBV genomes. This resulted in decreased chemotaxis. By employing an alternative way to eliminate EBV genomes, Roscovitine, we show an increase of apoptosis in the EBV-positive lines. These results show that EBV plays an important role in EBV-positive DLBCL lines with regard to survival and chemotactic response. Our findings provide evidence for the impact of microenvironment on EBV-carrying DLBCL cells and might have therapeutic implications.

Cytotoxic Epstein-Barr virus-positive large B cell lymphoma: a regulatory B cell-derived neoplasia?

AIMS

A new subtype of granzyme B (GrB)-producing regulatory B cells (B_regs ) has been described recently; these peculiar cytotoxic B cells are increased significantly in interleukin (IL)-21-rich settings, and in particular during HIV and Epstein-Barr virus (EBV) infection. Our aim is to report a unique case of an EBV-positive diffuse large B cell lymphoma (DLBCL) with cytotoxic features arisen in an HIV⁺ patient, and to understand if this lesion may represent a proliferation of neoplastic cytotoxic B_regs .

METHODS AND RESULTS

We describe a 66-year-old male patient who presented with cervical lymph node enlargement and B symptoms; subsequently, HIV infection was diagnosed. Histopathological, immunohistochemical and molecular studies were performed, and revealed an EBV-positive DLBCL with cytotoxic features. Considering the immunological setting and unconventional phenotype observed, we tried to evaluate further the expression of GrB and IL-21 in another 150 aggressive B cell lymphomas (17 of 150 EBV⁺ , two of 150 EBV⁺ /HIV⁺ ). Minimal dot-like expression of GrB was found in seven lymphomas (in fewer than 1% of tumour cells), three of which were EBV-positive.

CONCLUSIONS

B_reg origin has never been reported in B cell lymphomas. We describe an exceptional case of EBV-positive DLBCL with aberrant expression of cytotoxic markers in a patient with a previously unknown HIV infection. We propose cytotoxic B_regs as a possible normal counterpart for this unusual tumour.

Does persistent HIV replication explain continued lymphoma incidence in the era of effective antiretroviral therapy?

Non-Hodgkin lymphomas are highly increased in incidence in individuals infected with HIV, and this continues to be the case in spite of highly effective combined antiretroviral therapy (cART). New evidence has demonstrated that while successful virtual recovery of CD4 counts and elimination of HIV from peripheral blood can be achieved with cART, viral replication can still occur in lymphoid tissues. In addition, recent studies have suggested that adipose tissue provides an additional reservoir for HIV-infected macrophages and T lymphocytes even in the context of successful cART therapy. In this review article, we discuss possible mechanisms leading to the development of lymphoma in the cART era.

Interleukin 21 - its potential role in the therapy of B-cell lymphomas

Interleukin-21 (IL-21), a member of IL-2 cytokine family, has pleotropic biological effects on lymphoid and myeloid cells. During the past 15 years, since the discovery of IL-21, great advances have been made regarding its biological activity and the mechanisms controlling IL-21-mediated cellular responses, especially in hematological malignancies. Preclinical studies have shown that IL-21R is expressed on healthy and neoplastic B-cells and exogenous IL-21 can induce direct apoptosis of IL-21R expressing B-cell non-Hodgkin lymphomas (NHL), making it a potentially attractive anti-lymphoma therapy. However, in some hematological malignancies such as multiple myeloma, Hodgkin lymphoma and Burkitt lymphoma, IL-21 can induce proliferation of neoplastic B-cells. In NHL, the underlying mechanism of cell death was found to be different between the various subtypes, including activation of different JAK/STAT signal transduction pathways or other factors. Immunomodulatory effects of IL-21 have also been reported to contribute to its anti-tumor effects as described by earlier studies in solid tumors and B-cell associated malignancies. These effects are predominantly mediated by IL-21's ability to activate cytolytic activities by NK-cells and CD4⁺/CD8⁺ T-cells. In this review, we provide an overview of IL-21's effects in NHL, results from clinical trials utilizing IL-21, and propose how IL-21 can be therapeutically exploited for treating these lymphomas.

Effect of Interleukins on Antibody Production by Epstein-Barr Virus Transformed B Cells

During the past few decades, monoclonal antibodies (MAbs) have become an increasingly used tool in diagnostics, therapeutics, and biomedical research. Several methods have been employed to produce MAbs, one of which is the immortalization of B cells by Epstein-Barr virus (EBV). Despite its simplicity, this procedure was never routinely adopted due to its poor efficiency and short-lived antibody (Ab) production. Various adjustments to the basic procedure were introduced, including the addition of certain cytokines and CpG oligodeoxynucleotides, which were shown to improve EBV infectivity and cloning efficiency. The objective of this study was to manipulate culture conditions of the EBV-transformed human lymphocytes, lymphoblastoid cell lines (LCLs), by the timely addition of stimuli including CpG and various interleukins. Such manipulations are aimed at improving LCL proliferative activity and enhancing the cell lines' immortalization potential as well as their Ab production. To accomplish this, IgG(+) B cells were isolated from peripheral blood of a hepatitis B vaccinated, anti-HB Ab-positive volunteer. These cells were infected with EBV and incubated in the presence of CpG DNA 2006 motifs, recombinant human interleukin-2 (rhIL-2), rhIL-4, rhIL-6, and rhIL-21, individually and in combinations. Cells were then restimulated for 2 weeks with the same ILs. The effect of these ILs on anti-HB Ab production and the proliferation of the EBV-transformed lymphocytes were investigated. The current study demonstrates that treatment of LCL cultures with rhIL-2, rh-IL4, rhIL-6, and rhIL-21, individually and in combination, increased to varying degrees the proliferative activity and Ab production of these cells. The addition of IL-4 alone was able to sustain increase in anti-HB Ab despite IL-4 withdrawal. This study suggests that with further optimization ILs can have an enhancing effect on LCL immortalization potential and Ab production capacity.