KSHV-associated multicentric Castleman disease: A tangle of different entities requiring multitarget treatment strategies

Castleman Disease: A Rare Lymphoproliferative Disorder With Diverse Clinical Presentation, Diagnosis, and Treatment Approach

Castleman disease (CD) includes rare and intricate lymphoproliferative disorders characterized by the abnormal growth of lymph nodes and immune system disturbances. It primarily presents in two forms: unicentric Castleman disease (UCD), which affects a single lymph node area, and multicentric Castleman disease (MCD), which involves multiple lymph nodes and systemic manifestations. The disease's underlying mechanisms are often linked to immune system irregularities, especially involving interleukin-6 (IL-6). The condition was first documented by Dr. Benjamin Castleman in 1954, laying the groundwork for understanding this complex disorder. MCD can be further divided into idiopathic MCD (iMCD), which includes thrombocytopenia, ascites, fibrosis, renal impairment, and organ enlargement (TAFRO) syndrome, and human herpesvirus-8 (HHV-8)-associated MCD, which can occur in individuals with or without HIV. The prevalence of CD shows a higher occurrence of UCD, with the disease typically presenting in individuals in their fifth to seventh decades of life and being more common in areas with high HIV prevalence. The clinical presentation of CD can include symptoms such as swollen lymph nodes, fever, anemia, and systemic inflammation. Diagnostic challenges arise due to the disease's rarity, and its symptoms overlap with other conditions. Treatment approaches differ based on the subtype. UCD generally responds favorably to the surgical removal of the affected lymph nodes, while MCD often requires antiviral treatments, interleukin-6 (IL-6) inhibitors, and new biologic therapies. Recent advances in treatment, including innovative biologic agents and combination therapies, offer promising prospects for improving patient outcomes. Accurate diagnosis and customized treatment strategies are essential for the effective management of this complex disease.

Renal Neoplasms with Concurrent Castleman-Like Regional Lymphadenopathy

INTRODUCTION

Renal cell neoplasms are known to be associated with paraneoplastic syndromes, and the association with Castleman-like regional lymphadenopathy has been rarely reported. We aim to characterize the association between renal neoplasms and Castleman-like lymphadenopathy.

METHODS

A search for renal neoplasms with concurrent Castleman-like lymphadenopathy in one single medical institution from 2000 to 2023 resulted in 4 specimens. A literature search for "Castleman" and "renal neoplasm" resulted in 8 reports. Patients' demographics, clinical presentation, gross and histologic features, results of ancillary studies, treatment, and follow-up were evaluated.

RESULTS

Our patients included 3 men and 1 woman, with a mean age of 60 years. Four different subtypes of renal neoplasms were diagnosed, including clear cell renal cell carcinoma (RCC), papillary RCC, chromophobe RCC, and mucinous cystadenoma of the renal pelvis. For Castleman-like regional lymphadenopathy, 2 were plasma-cell predominant, and 2 were hyaline-vascular. After a median follow-up of 84 months, all patients were alive with no recurrence or progression of Castleman-like features following nephrectomies.

CONCLUSION

Castleman-like regional lymphadenopathy should be considered in patients with renal tumors and lymphadenopathy. Although more prevalent in clear cell RCC, it can be also associated with other renal neoplasms. The concurrent lymphadenopathy was remitted following the renal tumor resections.

Evidence for Multiple Subpopulations of Herpesvirus-Latently Infected Cells

Kaposi's sarcoma-associated herpesvirus (KSHV)-associated primary effusion lymphomas (PEL) are traditionally viewed as homogenous regarding viral transcription and lineage of origin, but so far this contention has not been explored at the single-cell level. Single-cell RNA sequencing of latently infected PEL supports the existence of multiple subpopulations even within a single cell line. At most 1% of the cells showed evidence of near-complete lytic transcription. The majority of cells only expressed the canonical viral latent transcripts: those originating from the latency locus, the viral interferon regulatory factor locus, and the viral lncRNA nut-1/Pan/T1.1; however, a significant fraction of cells showed various degrees of more permissive transcription, and some showed no evidence of KSHV transcripts whatsoever. Levels of viral interleukin-6 (IL-6)/K2 mRNA emerged as the most distinguishing feature to subset KSHV-infected PEL. One newly uncovered phenotype is the existence of BCBL-1 cells that readily adhered to fibronectin and that displayed mesenchymal lineage-like characteristics. IMPORTANCE Latency is the defining characteristic of the Herpesviridae and central to the tumorigenesis phenotype of Kaposi's sarcoma-associated herpesvirus (KSHV). KSHV-driven primary effusion lymphomas (PEL) rapidly develop resistance to therapy, suggesting tumor instability and plasticity. At any given time, a fraction of PEL cells spontaneously reactivate KSHV, suggesting transcriptional heterogeneity even within a clonal cell line under optimal growth conditions. This study employed single-cell mRNA sequencing to explore the within-population variability of KSHV transcription and how it relates to host cell transcription. Individual clonal PEL cells exhibited differing patterns of viral transcription. Most cells showed the canonical pattern of KSHV latency (LANA, vCyc, vFLIP, Kaposin, and vIRFs), but a significant fraction evidenced extended viral gene transcription, including of the viral IL-6 homolog, open reading frame K2. This study suggests new targets of intervention for PEL. It establishes a conceptual framework to design KSHV cure studies analogous to those for HIV.

Castleman disease

Castleman disease (CD), a heterogeneous group of disorders that share morphological features, is divided into unicentric CD and multicentric CD (MCD) according to the clinical presentation and disease course. Unicentric CD involves a solitary enlarged lymph node and mild symptoms and excision surgery is often curative. MCD includes a form associated with Kaposi sarcoma herpesvirus (KSHV) (also known as human herpesvirus 8) and a KSHV-negative idiopathic form (iMCD). iMCD can present in association with severe syndromes such as TAFRO (thrombocytopenia, ascites, fever, reticulin fibrosis and organomegaly) or POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder and skin changes). KSHV-MCD often occurs in the setting of HIV infection or another cause of immune deficiency. The interplay between KSHV and HIV elevates the risk for the development of KSHV-induced disorders, including KSHV-MCD, KSHV-lymphoproliferation, KSHV inflammatory cytokine syndrome, primary effusion lymphoma and Kaposi sarcoma. A CD diagnosis requires a multidimensional approach, including clinical presentation and imaging, pathological features, and molecular virology. B cell-directed monoclonal antibody therapy is the standard of care in KSHV-MCD, and anti-IL-6 therapy is the recommended first-line therapy and only treatment of iMCD approved by the US FDA and EMA.

The m6A landscape of polyadenylated nuclear (PAN) RNA and its related methylome in the context of KSHV replication

Polyadenylated nuclear (PAN) RNA is a long noncoding transcript involved in Kaposi's sarcoma-associated herpesvirus (KSHV) lytic reactivation and regulation of cellular and viral gene expression. We have previously shown that PAN RNA has dynamic secondary structure and protein binding profiles that can be influenced by epitranscriptomic modifications. N6-methyladenosine (m6A) is one of the most abundant chemical signatures found in viral RNA genomes and virus-encoded RNAs. Here, we combined antibody-independent next-generation mapping with direct RNA sequencing to address the epitranscriptomic status of PAN RNA in KSHV infected cells. We showed that PAN m6A status is dynamic, reaching the highest number of modifications at the late lytic stages of KSHV infection. Using a newly developed method, termed selenium-modified deoxythymidine triphosphate (SedTTP)-reverse transcription (RT) and ligation assisted PCR analysis of m6A (SLAP), we gained insight into the fraction of modification at identified sites. By applying comprehensive proteomic approaches, we identified writers and erasers that regulate the m6A status of PAN, and readers that can convey PAN m6A phenotypic effects. We verified the temporal and spatial subcellular availability of the methylome components for PAN modification by performing confocal microscopy analysis. Additionally, the RNA biochemical probing (SHAPE-MaP) outlined local and global structural alterations invoked by m6A in the context of full-length PAN RNA. This work represents the first comprehensive overview of the dynamic interplay that takes place between the cellular epitranscriptomic machinery and a specific viral RNA in the context of KSHV infected cells.

Hematological cancers in individuals infected by HIV

HIV infection increases cancer risk and is linked to cancers associated to infectious agents classified as carcinogenic to humans by the International Agency for Research on Cancer. Lymphomas represent one of the most frequent malignancies among individuals infected by HIV. Diffuse large B-cell lymphoma remains a leading cancer after the introduction of combined antiretroviral therapy (cART). The incidence of other lymphomas including Burkitt lymphoma, primary effusion lymphomas, and plasmablastic lymphoma of the oral cavity remain stable, while the incidence of Hodgkin lymphoma and Kaposi sarcoma-associated herpesvirus (KSHV)-associated Multicentric Castleman Disease has increased. The heterogeneity of lymphomas in individuals infected by HIV likely depends on the complexity of involved pathogenetic mechanisms, i.e. HIV-induced immunosuppression, genetic abnormalities, cytokine dysregulation, co-infection with the gamma-herpesviruses, Epstein Barr virus and KSHV, and the dysregulation of the immune responses controlling these viruses. In the modern cART era, standard treatments for HIV-associated lymphoma including stem cell transplantation in relapsed/refractory disease, mirrors that of the general population. The combination of cART and anti neoplastic treatments has resulted in remarkable prolongation of long-term survival. However, oncolytic and immunotherapic strategies, and therapies targeting specific viral oncogenes will need to be developed primarily.

Multicentric Castleman's disease in HIV patients: a single-center cohort diagnosed from 2008 to 2018

Purpose

Castleman’s disease (CD) is a well-established entity but there is a lack of available data regarding the management and therapy of HIV- and HHV-8-positive multicentric CD (MCD). We provide our own single-center experience with HIV-associated MCD.

Methods

We performed a retrospective, descriptive study on a cohort of patients with MCD, diagnosed and admitted to the infectious diseases or intensive care unit in the University Hospital Düsseldorf between 2008 and 2018. Included patients had a previous or new HIV diagnosis and clinical signs resembling MCD with evidence of HHV-8 replication or histological diagnosis for MCD.

Results

Nine male patients were included in the study. All patients were treated with Rituximab after diagnosis of MCD, with six of them acquiring resolution of symptoms. Three patients received tocilizumab additionally. Other treatment options included: splenectomy (2/9), valganciclovir (2/9), vincristine and siltuximab (1/9), ruxolitinib and Cytosorb^® (2/9). The relapse rate was 44% (4/9) and the survival rate 87.5% after 1 year (8/9) and 71.4% after 3 years (5/7).

Conclusion

The most effective first-line therapy and retreatment option remains rituximab. The effectiveness of other treatment options like splenectomy or different immunotherapeutic approaches requires confirmation in larger-scale studies.

Proteomic approaches to investigate gammaherpesvirus biology and associated tumorigenesis

The DNA viruses, Kaposi's sarcoma-associated herpesvirus (KSHV) and Epstein-Barr virus (EBV), are members of the gammaherpesvirus subfamily, a group of viruses whose infection is associated with multiple malignancies, including cancer. The primary host for these viruses is humans and, like all herpesviruses, infection with these pathogens is lifelong. Due to the persistence of gammaherpesvirus infection and the potential for cancer formation in infected individuals, there is a driving need to understand not only the biology of these viruses and how they remain undetected in host cells but also the mechanism(s) by which tumorigenesis occurs. One of the methods that has provided much insight into these processes is proteomics. Proteomics is the study of all the proteins that are encoded by a genome and allows for (i) identification of existing and novel proteins derived from a given genome, (ii) interrogation of protein-protein interactions within a system, and (iii) discovery of druggable targets for the treatment of malignancies. In this chapter, we explore how proteomics has contributed to our current understanding of gammaherpesvirus biology and their oncogenic processes, as well as the clinical applications of proteomics for the detection and treatment of gammaherpesvirus-associated cancers.

HIV-associated multicentric Castleman disease: a report of 19 cases at an oncology institution

The aim of this study is to describe the clinical characteristics and outcome of multicentric Castleman disease (MCD) in HIV-infected patients at an oncological referral center in Mexico. Clinical records at the HIV-AIDS clinic of all patients diagnosed with MCD from 1994 to 2018 were reviewed. There were 19 patients, mean age was 31.3 ± 8.4 years, and 17 (89.5%) were males. Fifteen patients (79%) had also Kaposi sarcoma (KS). Main clinical characteristics were multiple lymphadenopathy (95%), systemic symptoms (63%), and hepatosplenomegaly (50%). Computed tomography scan and 2-[18F]-fluoro-2-deoxy-d-glucose positron emission tomography showed multiple lymphadenopathy, inversion of the liver:spleen uptake ratio, with an increase in SUVmax (5.7). The histopathology report described plasma cells in 58%, mixed type in 26%, and hyaline vascular in 16%. Eleven patients (57.9%) received different chemotherapy regimens. Seven patients died (36.8%): four related to MCD progression or chemotherapy complications, median survival was eight months. For those patients who survived, median, follow-up was 28 months (p < 0.001). The incidence of MCD in people living with HIV is probably underestimated. In patients with lymphadenopathy, B symptoms, deranged inflammatory markers, and/or disseminated KS, a biopsy of an enlarged lymph node is warranted, and the histology should be reviewed by an experienced pathologist.

USP7-Dependent Regulation of TRAF Activation and Signaling by a Viral Interferon Regulatory Factor Homologue

Human herpesvirus 8 (HHV-8) encodes four viral interferon regulatory factors (vIRFs 1 to 4), all of which are expressed during lytic replication and inhibit a variety of antiviral signaling pathways. Viral IRFs 1, 2, and 3 are also expressed during latency in primary effusion lymphoma (PEL) cells, and vIRF-1 and vIRF-3 have been reported to promote PEL cell viability. Viral IRFs 1, 3, and 4 are known to interact with ubiquitin-specific protease 7 (USP7); interactions of vIRF-1 and vIRF-3 with USP7 promote PEL cell viability and regulate productive replication. Here, we report that vIRF-2 also targets USP7, utilizing a PSTS motif matching the USP7 N-terminal domain-binding A/PxxS consensus, but uniquely requires catalytic domain residues for intracellular interaction. In functional and mechanistic analyses, tumor necrosis factor receptor-associated factor (TRAF)-mediated signaling and associated polyubiquitination of TRAFs 3 and 6, specifically, were regulated negatively by USP7 and positively by vIRF-2-USP7 interaction, the latter competing for USP7-TRAF association. Using depletion, depletion-complementation, and targeted mutagenesis approaches, vIRF-2 was determined to promote latent PEL cell viability, likely independently of USP7 interaction, while lytic replication was inhibited by vIRF-2, in part or in whole via USP7 interaction. Together, our data identify a new molecular determinant of USP7 recognition, TRAF3/6-specific targeting by the deubiquitinase, associated activation of these TRAFs by vIRF-2, and activities of vIRF-2 and vIRF-2-USP7 interaction in HHV-8 latent and lytic biology.IMPORTANCE Human herpesvirus 8-encoded IRF homologues were the first to be identified in a virus. Through inhibitory interactions with cellular IRFs and other mediators of antiviral signaling, the vIRFs are believed to be essential for productive replication and also for latency in particular cell types. The deubiquitinase USP7 is a regulator of key cellular pathways, modulates HHV-8 latent and lytic infection, and is targeted by vIRFs 1, 3, and 4. Here, we report that vIRF-2 also interacts with USP7, via a means distinguishable from USP7 interactions with other vIRFs and other proteins, that this interaction modulates antiviral signaling via disruption of USP7 interactions with innate immune signaling proteins TRAF3 and TRAF6, and that vIRF-2 targeting of USP7 regulates HHV-8 productive replication. The presented data are the first to identify vIRF-2 targeting of USP7 and its role in HHV-8 biology, expanding our understanding of the repertoire and importance of virus-host interactions.

Association of NFκB and related-cytokines with the viral load and development of antibodies against HHV-8 in people living with HIV/AIDS

Human gammaherpesvirus 8 (HHV-8) replication is influenced by a complex interaction between viral and host elements. Here, we evaluated the expression of NFκB and TNF-α in B (CD19 +) and T (CD3 +) lymphocytes, and the serum concentration of IL-1β and IL-12 cytokines in people living with HIV/AIDS (PLHA), negative for HHV-8-related diseases, and who presented antibodies to latent or lytic antigens from HHV-8. In addition, we also evaluated the correlation of HHV-8 viral load with NFκB, TNF-α, IL-1β and IL-12 levels. The expression of NFκB (p < 0.0001) or TNF-α (p < 0.0001) in B lymphocytes (CD19 +) and the IL-1β (p < 0.0266) and IL-12 (p < 0.0001) concentrations were associated with the presence of antibodies to HHV-8 lytic antigens. The CD19 + NFκB + TNF-α + and CD3 + NFκB + TNF-α + cells were also associated with the presence of antibodies to lytic infection (p < 0.0001). Among all PLHA evaluated, only individuals with the highest titers of lytic antibodies, i.e., 1:320, had detectable HHV-8 viral load. In these, HHV-8 viral load was correlated to NFκB (r = 0.6, p = 0.003) and TNF-α (r = 0.5, p = 0.01) (both in CD19 + lymphocytes) and with IL-1β (r = 0.5, p = 0.01) and IL-12 (r = 0.6, p = 0.006) levels. We believe that viral replication and/or reactivation, in addition to being associated with the development of lytic antibodies against HHV-8, may be associated with inflammatory response via NFκB. Finally, although immune response imbalance has been previously related to HHV-8-associated diseases, our results indicate that important changes in immunity, mainly in the inflammatory response, may be clearly observed in individuals with HHV-8, but who have not yet presented clinical manifestations.

Molecular Biology of KSHV in Relation to HIV/AIDS-Associated Oncogenesis

Discovered in 1994, Kaposi's sarcoma-associated herpesvirus (KSHV) has been associated with four human malignancies including Kaposi's sarcoma, primary effusion lymphoma, a subset of multicentric Castleman's disease, and KSHV inflammatory cytokine syndrome. These malignancies mostly occur in immunocompromised patients including patients with acquired immunodeficiency syndrome and often cause significant mortality because of the lack of effective therapies. Significant progresses have been made to understand the molecular basis of KSHV infection and KSHV-induced oncogenesis in the last two decades. This chapter provides an update on the recent advancements focusing on the molecular events of KSHV primary infection, the mechanisms regulating KSHV life cycle, innate and adaptive immunity, mechanism of KSHV-induced tumorigenesis and inflammation, and metabolic reprogramming in KSHV infection and KSHV-transformed cells.

Herpesvirus acts with the cytoskeleton and promotes cancer progression

The cytoskeleton is a complex fibrous reticular structure composed of microfilaments, microtubules and intermediate filaments. These components coordinate morphology support and intracellular transport that is involved in a variety of cell activities, such as cell proliferation, migration and differentiation. In addition, the cytoskeleton also plays an important role in viral infection. During an infection by a Herpesvirus, the virus utilizes microfilaments to enter cells and travel to the nucleus by microtubules; the viral DNA replicates with the help of host microfilaments; and the virus particles start assembling with a capsid in the cytoplasm before egress. The cytoskeleton changes in cells infected with Herpesvirus are made to either counteract or obey the virus, thereby promote cell transforming into cancerous ones. This article aims to clarify the interaction between the virus and cytoskeleton components in the process of Herpesvirus infection and the molecular motor, cytoskeleton-associated proteins and drugs that play an important role in the process of a Herpesvirus infection and carcinogenesis process.

Kaposi's Sarcoma-Associated Herpesvirus Latency Locus Renders B Cells Hyperresponsive to Secondary Infections

Kaposi's sarcoma-associated herpesvirus (KSHV) induces B cell hyperplasia and neoplasia, such as multicentric Castleman's disease (MCD) and primary effusion lymphoma (PEL). To explore KSHV-induced B cell reprogramming in vivo, we expressed the KSHV latency locus, inclusive of all viral microRNAs (miRNAs), in B cells of transgenic mice in the absence of the inhibitory FcγRIIB receptor. The BALB/c strain was chosen as this is the preferred model to study B cell differentiation. The mice developed hyperglobulinemia, plasmacytosis, and B lymphoid hyperplasia. This phenotype was ameliorated by everolimus, which is a rapamycin derivative used for the treatment of mantle cell lymphoma. KSHV latency mice exhibited hyperresponsiveness to the T-dependent (TD) antigen mimic anti-CD40 and increased incidence of pristane-induced inflammation. Lastly, the adaptive immunity against a secondary infection with Zika virus (ZIKV) was markedly enhanced. These phenotypes are consistent with KSHV lowering the activation threshold of latently infected B cells, which may be beneficial in areas of endemicity, where KSHV is acquired in childhood and infections are common.IMPORTANCE Kaposi's sarcoma-associated herpesvirus (KSHV) establishes latency in B cells and is stringently linked to primary effusion lymphoma (PEL) and the premalignant B cell hyperplasia multicentric Castleman's disease (MCD). To investigate potential genetic background effects, we expressed the KSHV miRNAs in BALB/c transgenic mice. BALB/c mice are the preferred strain for B cell hybridoma development because of their propensity to develop predictable B cell responses to antigen. The BALB/c latency mice exhibited a higher incidence of B cell hyperplasia as well as sustained hyperglobulinemia. The development of neutralizing antibodies against ZIKV was augmented in BALB/c latency mice. Hyperglobulinemia was dampened by everolimus, a derivative of rapamycin, suggesting a role for mTOR inhibitors in managing immune activation, which is hallmark of KSHV infection as well as HIV infection.

Activation and counteraction of antiviral innate immunity by KSHV: an Update

The innate immune responses triggering production of type I interferons and inflammatory cytokines constitute a nonspecific innate resistance that eliminates invading pathogens including viruses. The activation of innate immune signaling through pattern recognition receptors (PRRs) is by sensing pathogen-associated molecular patterns derived from viruses. According to their distribution within cells, PRRs are classified into three types of receptors: membrane, cytoplasmic, and nuclear. Kaposi's sarcoma-associated herpesvirus (KSHV), a large DNA virus, replicates in the nucleus. Its genome is protected by capsid proteins during transport in the cytosol. Multiple PRRs are involved in KSHV recognition. To successfully establish latent infection, KSHV has evolved to manipulate different aspects of the host antiviral innate immune responses. This review presents recent advances in our understanding about the activation of the innate immune signaling in response to infection of KSHV. It also reviews the evasion strategies used by KSHV to subvert host innate immune detection for establishing a persistent infection.

Epstein-Barr virus associated lymphomas in people with HIV

PURPOSE OF REVIEW

The present review summarizes the association of the different histotypes of Epstein-Barr virus (EBV)-associated lymphomas with known genetic lesions and/or oncogenic viruses. A more comprehensive understanding of the complex interplay existing between genetic abnormalities of tumor cells and the viral contribution to the development of EBV-associated lymphomas is pivotal for the development of more effective treatments.

RECENT FINDINGS

Recent evidence indicates that HIV may contribute to lymphomagenesis by acting directly on B lymphocytes as a critical microenvironmental factor. The pathogenesis of EBV-associated lymphomas in patients with HIV infection is considered the result of the concerted action of different factors, mainly including impaired immune surveillance, genetic alterations, and concomitant viral infection (EBV and HIV).

SUMMARY

Immunodeficiency states usually increase susceptibility to cancer as a result of reduced immune surveillance and enhanced chances for virus-driven oncogenesis. Lymphoma remains the most frequent neoplastic cause of death among patients infected with HIV. Several of the HIV-associated lymphomas are related to EBV infection. EBV-associated lymphomas in patients infected with HIV are heterogeneous, not only pathologically but also in terms of pathogenetic pathways and cellular derivation.

Multiple viral infections in primary effusion lymphoma: a model of viral cooperation in lymphomagenesis

INTRODUCTION

Primary effusion lymphoma (PEL) is a rare B-cell lymphoid neoplasm mainly associated with HIV infection, presenting as pleural, peritoneal, and pericardial effusions. A defining property of PEL is its consistent association with Kaposi sarcoma associated herpesvirus (KSHV) infection, and, in most cases, Epstein Barr virus (EBV) co-infection. On these grounds, a review of the literature related to viral cooperation and lymphomagenesis can help to understand the complex interplay between KSHV and EBV in PEL pathogenesis. Areas covered: In this review, the authors highlight clinical, pathologic, genetic and proteomic features of PEL, in the context of viral cooperation in PEL lymphomagenesis. Expert commentary: Tumour cells are characterized by the overexpression of genes that are involved in inflammation and invasion. Coherently, PEL secretomes are enriched in proteins probably responsible for the particular tropism (cell adhesion and migration) of PEL cells. The development of PEL in HIV+ patients is multifactorial and involves a complex interplay among co-infection with oncogenic viruses (EBV and KSHV), inflammatory factors, and environmental conditions.

KSHV-Mediated Angiogenesis in Tumor Progression

Human herpesvirus 8 (HHV-8), also known as Kaposi's sarcoma-associated herpesvirus (KSHV), is a malignant human oncovirus belonging to the gamma herpesvirus family. HHV-8 is closely linked to the pathogenesis of Kaposi's sarcoma (KS) and two other B-cell lymphoproliferative diseases: primary effusion lymphoma (PEL) and a plasmablastic variant of multicentric Castleman's disease (MCD). KS is an invasive tumor of endothelial cells most commonly found in untreated HIV-AIDS or immuno-compromised individuals. KS tumors are highly vascularized and have abnormal, excessive neo-angiogenesis, inflammation, and proliferation of infected endothelial cells. KSHV directly induces angiogenesis in an autocrine and paracrine fashion through a complex interplay of various viral and cellular pro-angiogenic and inflammatory factors. KS is believed to originate due to a combination of KSHV's efficient strategies for evading host immune systems and several pro-angiogenic and pro-inflammatory stimuli. In addition, KSHV infection of endothelial cells produces a wide array of viral oncoproteins with transforming capabilities that regulate multiple host-signaling pathways involved in the activation of angiogenesis. It is likely that the cellular-signaling pathways of angiogenesis and lymph-angiogenesis modulate the rate of tumorigenesis induction by KSHV. This review summarizes the current knowledge on regulating KSHV-mediated angiogenesis by integrating the findings reported thus far on the roles of host and viral genes in oncogenesis, recent developments in cell-culture/animal-model systems, and various anti-angiogenic therapies for treating KSHV-related lymphoproliferative disorders.

Molecular Epidemiology of Kaposi's Sarcoma-Associated Herpes Virus, and Risk Factors in HIV-infected Patients in Tehran, 2014

Background

Kaposi’s sarcoma (KS) remains the most common malignancy among HIV-infected patients. Human herpesvirus type-8 (HHV-8) is regarded as the infectious etiological agent of Kaposi’s sarcoma (KSHV). Diagnostic procedures associated with KSHV are not routinely performed in HIV-infected subjects.

Objectives

The main objective of this study is to obtain information on KSHV epidemiology in Iranian HIV-infected individuals.

Patients and Methods

In the present cross-sectional study, 109 patients with established HIV infection, who visited a governmental and referral center for HIV screening in Tehran (Tehran west health center (TWHC)) between May 2014 and July 2015 were enrolled according to the convenience sample strategy. After peripheral blood collection, isolation of plasma and peripheral blood mononuclear cell (PBMC) compartments, DNA extraction was performed. KSHV DNA was analyzed by nested polymerase chain reaction (nested PCR) using primers from ORF-26 (virus minor capsid).

Results

Among all 109 HIV-infected patients, 67 (61.5%) were male, with an age range of 2 - 64 years (mean ± standard deviation 35.8 ± 13.3). KSHV DNA was found in PBMC and plasma samples of six (5.5%) and four (3.6%) patients, respectively.

Conclusions

This study revealed a considerable prevalence of KSHV DNA, during latent and lytic phases, among HIV-infected patients. Risk factors for KSHV infection acquisition and concurrent. 0+infection with HIV were also evaluated. Diagnosis of KSHV in the group could be helpful for prognosis of Kaposi’s sarcoma and clinical management.

Clinical management of HIV-associated hematologic malignancies

HIV is associated with an excess risk for lymphoid malignancies. Although the risk of lymphoma has decreased in HIV-infected individuals in the era of effective combination antiretroviral therapy, it remains high. Treatment outcomes have improved due to improvements in HIV and cancer therapeutics for the common HIV-associated lymphomas. R-CHOP/R-EPOCH are the standard of care for HIV-associated diffuse large B-cell lymphoma. HIV-infected patients with Burkitt lymphoma and good performance status should receive dose-intensive regimens. HIV-infected patients with primary central nervous system lymphoma can respond favorably to high-dose methotrexate-based therapy. In many cases, treatment and expected outcomes for HIV-infected patients with either Hodgkin or non-Hodgkin's lymphomas are very similar to HIV-negative patients. There is currently no standard treatment for HIV-associated multicentric Castleman disease or primary effusion lymphoma. For those hematologic cancers in which transplantation is part of standard care, this modality should be considered an option in those with well-controlled HIV infection.

A lymphomagenic role for HIV beyond immune suppression?

Despite the immune reconstitution promoted by combined antiretroviral therapy (cART), lymphomas still represent the most common type of cancer in HIV-infected individuals. Cofactors related to immunodeficiency such as oncogenic viruses, chronic antigenic stimulation, and cytokine overproduction are thought to be the main drivers of HIV lymphomagenesis, although the current scenario does not convincingly explain the still-high incidence of lymphomas and the occurrence of peculiar lymphoma histotypes in HIV-infected patients under cART. Recent findings are challenging the current view of a mainly indirect role of HIV in lymphoma development and support the possibility that HIV may directly contribute to lymphomagenesis. In fact, mechanisms other than immune suppression involve biologic effects mediated by HIV products that are secreted and accumulate in lymphoid tissues, mainly within lymph node germinal centers. Notably, HIV-infected patients with lymphomas, but not those not affected by these tumors, were recently shown to carry HIV p17 protein variants with enhanced B-cell clonogenic activity. HIV p17 protein variants were characterized by the presence of distinct insertions at the C-terminal region of the protein responsible for a structural destabilization and the acquisition of novel biologic properties. These data are changing the current paradigm assuming that HIV is only indirectly related to lymphomagenesis. Furthermore, these recent findings are consistent with a role of HIV as a critical microenvironmental factor promoting lymphoma development and pave the way for further studies that may lead to the design of more effective strategies for an early identification and improved control of lymphomas in the HIV setting.

Practical Applications in Immunohistochemistry: Evaluation of Diffuse Large B-Cell Lymphoma and Related Large B-Cell Lymphomas

Context

Diffuse large B-cell lymphoma is the most commonly diagnosed subtype of lymphoma worldwide. The current World Health Organization (WHO) classification includes several subtypes, based on a combination of clinical, immunohistochemical, and genetic differences. Immunohistochemical staining is essential in evaluating diffuse large B-cell lymphoma and many related large B-cell lymphomas and aggressive B-cell lymphomas.

Objective

To address different immunohistochemical features used for identification, subclassification, prognosis and in some cases, therapy, of diffuse large B-cell lymphoma and related lymphomas.

Data Sources

The information outlined in this review article is based on our experiences with routine cases, on the current WHO classification of hematopoietic and lymphoid tumors, and on a review of English-language articles published throughout 2014.

Conclusions

Features and diagnostic criteria of diffuse large B-cell lymphoma, aggressive variants of B-cell lymphomas, including Burkitt lymphoma and “double-hit” lymphomas, are discussed. Identification of cell of origin (germinal center type versus activated B-cell type) is discussed at length. Finally, practical approaches for diagnosis are discussed.