EBV-associated lymphoproliferative disorders: classification and treatment

Systematic analysis of viral and cellular microRNA targets in cells latently infected with human gamma-herpesviruses by RISC immunoprecipitation assay

The mRNA targets of microRNAs (miRNAs) can be identified by immunoprecipitation of Argonaute (Ago) protein-containing RNA-induced silencing complexes (RISCs) followed by microarray analysis (RIP-Chip). Here we used Ago2-based RIP-Chip to identify transcripts targeted by Kaposi's sarcoma-associated herpesvirus (KSHV) miRNAs (n = 114), Epstein-Barr virus (EBV) miRNAs (n = 44), and cellular miRNAs (n = 2337) in six latently infected or stably transduced human B cell lines. Of the six KSHV miRNA targets chosen for validation, four showed regulation via their 3'UTR, while two showed regulation via binding sites within coding sequences. Two genes governing cellular transport processes (TOMM22 and IPO7) were confirmed to be targeted by EBV miRNAs. A significant number of viral miRNA targets were upregulated in infected cells, suggesting that viral miRNAs preferentially target cellular genes induced upon infection. Transcript half-life both of cellular and viral miRNA targets negatively correlated with recruitment to RISC complexes, indicating that RIP-Chip offers a quantitative estimate of miRNA function.

New targets of therapy in T-cell lymphomas

T-cell lymphomas (TCL) are characterized by poor response to chemotherapy and generally poor outcome. While molecular profiling has identified distinct biological subsets and therapeutic targets in B-cell lymphomas, the molecular characterization of TCL has been slower. Surface markers expressed on malignant T-cells, such as CD2, CD3, CD4, CD25, and CD52 were the first TCL-specific therapeutic targets to be discovered. However, the presence of these receptors on normal T-cells means that monoclonal antibody (mAb)- or immunotoxin (IT)-based therapy in TCL inevitably results in variable degrees of immunosuppression. Thus, although some mAbs/IT have significant activity in selected subsets of TCL, more specific agents that target signaling pathways preferentially activated in malignant T-cells are needed. One such novel class of agents is represented by the histone deacetylase (HDAC) inhibitors. These molecules selectively induce apoptosis in a variety of transformed cells, including malignant T-cells, both in vitro and in vivo. Several HDAC inhibitors have been studied in TCL with promising results, and have recently been approved for clinical use. Immunomodulatory drugs, such as interferons and Toll Receptor (TLR) agonists have significant clinical activity in TCL, and are particularly important in the treatment of primary cutaneous subtypes (CTCL). Although most classical cytotoxic drugs have limited efficacy against TCL, agents that inhibit purine and pyrimidine metabolism, known as nucleoside analogues, and novel antifolate drugs, such as pralatrexate, are highly active in TCL. With improved molecular profiling of TCL novel pharmacological agents with activity in TCL are now being discovered at an increasingly rapid pace. Clinical trials are in progress and these agents are being integrated in combination therapies for TCL, both in the relapsed/refractory setting as well as front line.

Characterization of Lymphomas in a high prevalence HIV setting

BACKGROUND

HIV infection has been associated with an increased risk of malignancy, both AIDS defining and non-AIDS defining.

METHODS

This study presents a detailed pathological description of newly diagnosed lymphomas in Johannesburg, South Africa (January 2004 and December 2006). The review coincides with introduction of combination antiretroviral therapy.

RESULTS

One thousand eight hundred and ninety-seven new lymphoproliferative disorders were referred to the Charlotte Maxeke Johannesburg Academic Hospital. B-cell non-Hodgkin lymphoma accounted for 83%, T-cell non-Hodgkin lymphoma 3.5%, and Hodgkin lymphoma 7% of cases. The overall prevalence of HIV infection was 37% (n = 709). Diffuse large B-cell lymphoma (21%; n = 401) was the most common lymphoma. HIV prevalence ranged from an absence in follicular or mantle cell lymphoma to a low prevalence in diseases like small lymphocytic lymphoma/chronic lymphocytic leukemia (4%) and pre-B/common ALL (5%) to a high prevalence in diffuse large B-cell lymphoma (80%), Burkitt lymphoma/leukemia (86%), and primary effusion lymphoma (100%).

CONCLUSIONS

This study provides a baseline for monitoring the impact of HIV and management thereof on lymphoma trends. The high prevalence of HIV in certain lymphoma categories emphasizes the need for capacity to diagnose and manage dual conditions. This study highlights the need for strengthening of cancer registries within South Africa and the region.

Isolated central nervous system involvement by lymphomatoid granulomatosis in an adolescent: a case report and review of literature

Lymphomatoid granulomatosis is an Epstein-Barr virus-associated multisystem disease that combines granulomatous inflammatory process with lymphoproliferative potential. It predominantly affects lungs, skin, and brain and is characterized by multifocal, transmural, angiocentric, and angiodestructive pleomorphic lymphoid infiltrate in a perivascular distribution. Lymphomatoid granulomatosis is generally considered to be a neoplastic B-cell proliferation that has traditionally been associated with poor prognosis, evolving as a progressive multisystem disease transforming into B-cell lymphoma, with a median survival of 14 to 16 months only. Its lymphomatous nature explains prompt response to steroids and systemic chemotherapy, although appropriate optimal management still remains to be defined. The authors report on a young boy who presented with features of raised intracranial tension and sudden onset seizures. Neuroimaging showed 2 space-occupying lesions, larger in the left frontoparietal region with heterogeneous enhancement, moderate perifocal edema, compression, and mass effect. He underwent surgical decompression of the dominant lesion with prompt relief of symptoms. The diagnosis of lymphomatoid granulomatosis was confirmed on light microscopy and immunohistochemistry. An extensive systemic work-up ruled out other site(s) of involvement. He was successfully treated with aggressive systemic chemotherapy and moderate dose of whole-brain radiotherapy. Awareness of disease spectrum in the central nervous system may permit early diagnosis and thus allow institution of timely appropriate therapy.

Imaging findings in immunosuppressed patients with Epstein Barr virus-related B cell malignant lymphoma

OBJECTIVE

The purpose of this study was to describe multimodality imaging findings in immunosuppressed patients with Epstein-Barr virus (EBV)-related malignant lymphoproliferative diseases.

CONCLUSION

EBV-related malignant lymphoproliferative diseases share common features with other aggressive lymphomas, including a high degree of extranodal involvement, tumor vascularization, and tumor necrosis. Cognizance of the particular underlying diseases and conditions associated with the development of EBV-related lymphoproliferative diseases and associated imaging results should provide more accurate diagnosis.

Lymphoproliferative disease of the kidney developing in fibro-inflammatory lesion

An 80-year-old man presented with continuous spike fever and night sweats. Computed tomographic scans revealed a poorly demarcated mass in the upper part of the right kidney, which was resected. At surgery, tumorous lesions were not found in the abdominal cavity. Serum IgG4 level measured after surgery was 40.1mg/dl. Macroscopically, renal parenchyma of the upper part was replaced by an irregularly shaped grayish-white lesion of elastic, firm consistency. Histologically, the lesion consisted mostly of fibrous tissue in which small lymphoid cells, often with formation of aggregates, were evident. IgG4-positive plasma cells were few in number. Careful macroscopic examination revealed several minute nodules, which histologically consisted of large lymphoid cells, small lymphoid cells, and macrophages. These large lymphoid cells were positive for CD20 and contained Epstein-Barr virus (EBV) genome. Taken together, a diagnosis of EBV-positive B-cell lymphoproliferative disease (LPD) developing in inflammatory pseudotumor (IPT) of the kidney was made. This is the first report of B-LPD in IPT of the kidney. In addition, a presence of EBV in renal lymphoma cells has not yet been reported.

Epstein-Barr virus positive diffuse large B-cell lymphoma of the elderly

Epstein-Barr virus positive diffuse large B-cell lymphoma (EBV+ DLBCL) of the elderly is a rare B-cell lymphoproliferative disorder (B-LPD) that occurs in patients > 50 years with no known history of immunodeficiency or lymphoma. Patients present with moderate to severe clinical B-symptoms. These lesions show complete effacement of normal tissue/nodal architecture by large atypical lymphoid cells/immunoblasts and Hodgkin/Reed-Sternberg-like giant cells with variable amounts of inflammatory cells in the background. The ratio of neoplastic to inflammatory cells, degree of mitoses and necrosis can be quite variable; hence EBV+ DLBCL of the elderly was historically divided into low grade polymorphic and high grade monomorphic types. Further studies have shown both types to be different points in the spectrum of disease, and are all high grade lymphomas. The neoplastic large lymphoid cells show expression of CD20/CD79a and PAX-5, with variable expression of CD30, LMP-1 and EBNA-2, but CD15, CD10 and BCL6 are generally negative. Neoplastic cells show EBER positivity and high Ki-67 expression. Differential diagnoses include EBV+ B-LPD, classical Hodgkin lymphoma and EBV-DLBCL. EBV+ DLBCL of the elderly is highly aggressive with a median survival of 2 years. These patients are less responsive to standard chemotherapy compared with other B-LPD.

Nucleofection of DCs to generate Multivirus-specific T cells for prevention or treatment of viral infections in the immunocompromised host

Viral infections cause morbidity and mortality in allogeneic hematopoietic stem cell transplant (HSCT) recipients. To prevent and treat these, we have produced and infused cytotoxic T lymphocytes (CTLs) with specificity for Epstein-Barr virus (EBV), cytomegalovirus (CMV), and adenovirus (Adv), and shown that small numbers of infused cells proliferate in vivo and protect against all three viruses. Despite these encouraging results, broader implementation of this approach is limited by the need for infectious virus material (EBV), expensive production of clinical grade adenoviral vectors, and a prolonged (8-12 weeks) period of manufacture. There is also competition between virus-derived antigens within antigen-presenting cells (APCs), limiting extension to additional agents. We now describe an approach that uses DNA nucleofection of dendritic cells (DCs) with DNA plasmids that encode a range of immunodominant and subdominant viral antigens from CMV, EBV, BK, and Adv. Within 10 days, this methodology provides multivirus-reactive CTLs that lack alloreactivity. We further demonstrate that nucleofected DC stimulation can be combined with interferon-gamma (IFN-gamma) capture technology to produce even more rapid multivirus-CTL products for treatment of acute infection. These CTL generation procedures should increase the feasibility and applicability of T-cell therapy.

Tumour virology--history, status and future challenges

Viruses enter host cells in order to complete their life cycles and have evolved to exploit host cell structures, regulatory factors and mechanisms. The virus and host cell interactions have consequences at multiple levels, spanning from evolution through disease to models and tools for scientific discovery and treatment. Virus-induced human cancers arise after a long duration of time and are monoclonal or oligoclonal in origin. Cancer is therefore a side effect rather than an essential part of viral infections in humans. Still, 15-20% of all human cancers are caused by viruses. A review of tumour virology shows its close integration in cancer research. Viral tools and experimental models have been indispensible for the progress of molecular biology. In particular, retroviruses and DNA tumour viruses have played major roles in our present understanding of the molecular biology of both viruses and the host. Recently, additional complex relationships due to virus and host co-evolution have appeared and may lead to a further understanding of the overall regulation of gene expression programmes in cancer.

Peripheral T-cell lymphoma of Lennert type complicated by monoclonal proliferation of large B-cells

A 69-year-old man presented with lymph node swelling in the right inguinal region. A biopsy was made (LN1) and diagnosed as peripheral T-cell lymphoma. The lesion remitted completely over a period of about 51 months after combination chemotherapy, but erythematous papules, systemic lymphadenopathy, and fever of 38 degrees appeared. Skin (S1) and lymph nodes (LN2) were biopsied. Erythematous papules once disappeared spontaneously, but appeared again and were biopsied (S2). LN1 displayed the typical histologic and immunohistochemical features of Lennert lymphoma, i.e., diffuse proliferation of small to large lymphoid cells of CD3+, CD4+, CD8- immunophenotype accompanied by numerous clusters of epithelioid histiocytes. In LN2, the large cells with CD3+, CD4+, CD8- decreased in number, while numerous CD20+ large cells were discernible. Clonality analysis revealed the persistent presence of an identical T-cell clone in LN1 and LN2. Clonal bands of immunoglobulin heavy (IgH) chain gene were detected in LN2 but not in LN1. S1 and S2 showed diffuse proliferation of small to large lymphoid cells of CD20-, CD3+, CD4+, CD8- in the upper dermis, with obvious epidermotropism. Clonality analysis revealed the presence of a T-cell clone identical to LN1 and LN2 with no B-cell clone, indicating the recurrence of PTCL. In situ hybridization (ISH) for Epstein-Barr virus (EBV) genome revealed that positive signals in the nucleus of large B-lymphoid cells appeared only in LN2. Taken together, EBV-positive large B-cell lymphoma appeared transiently in the course of "Lennert lymphoma".

HIV-associated lymphomas and gamma-herpesviruses

Among the most common HIV-associated lymphomas are Burkitt lymphoma (BL) and diffuse large B-cell lymphoma (DLBCL) with immunoblastic-plasmacytoid differentiation (also involving the central nervous system). Lymphomas occurring specifically in HIV-positive patients include primary effusion lymphoma (PEL) and its solid variants, plasmablastic lymphoma of the oral cavity type and large B-cell lymphoma arising in Kaposi sarcoma herpesvirus (KSHV)-associated multicentric Castleman disease. These lymphomas together with BL and DLBCL with immunoblastic-plasmacytoid differentiation frequently carry EBV infection and display a phenotype related to plasma cells. EBV infection occurs at different rates in different lymphoma types, whereas KSHV is specifically associated with PEL, which usually occurs in the setting of profound immunosuppression. The current knowledge about HIV-associated lymphomas can be summarized in the following key points: (1) lymphomas specifically occurring in patients with HIV infection are closely linked to other viral diseases; (2) AIDS lymphomas fall in a spectrum of B-cell differentiation where those associated with EBV or KSHV commonly exhibit plasmablastic differentiation; and (3) prognosis for patients with lymphomas and concomitant HIV infection could be improved using better combined chemotherapy protocols incorporating anticancer treatments and antiretroviral drugs.

The Germinal centre-derived lymphomas seen through their cellular microenvironment

The human lymph node is a complex tissue resulting from the microenvironmental organisation of different cell populations linked by topographical and/or functional relationships. Germinal centres (GCs) of lymphoid follicles contain a meshwork of follicular dendritic cells in addition to B-cells and some CD4(+) T cells. Moreover, there is a sharp demarcation around the whole follicle centre, which is highlighted by fibroblastic reticulum cells. On the whole, GC exerts a role in B cell physiology and malignancy. In GC-derived lymphomas, gene expression profiling studies have raised the possibility that survival of the affected patients may be associated with signatures preferentially expressed in non-malignant T cells and macrophages and/or dendritic cells. Immunohistological analyses in lymphoma biopsy samples have confirmed that the biological behaviour and tumour progression may be influenced by the tumour microenvironment. This review will examine GC-derived lymphomas, including follicular lymphomas, Hodgkin lymphomas and angioimmunoblastic T-cell lymphoma, through their integrated cellular microenvironment, highlighting those findings which may serve as a useful surrogate marker for tumour diagnosis or tumour progression, together with key molecules involved in tumour development.

MicroRNA expression in non-Hodgkin's lymphomas

MicroRNAs are a class of short, single-stranded, noncoding RNA molecules that negatively regulate the expression target mRNA at posttranslational level. microRNAs as key regulatory molecules play important biological function and might act as tumor suppressor oncogenes in cancer and lymphomas. microRNAs cause the expression of important cancer related genes and might prove useful in the diagnostics, prognosis, and treatment of some lymphomas This review focuses on the role of microRNAs in normal lymphocyte differentiation and in development of non-Hodgkin's lymphomas.