Cellular localisation of HHV-8 in Castleman's disease: is there a link with lymph node vascularity?

The Peripheral Neuropathies of POEMS Syndrome and Castleman Disease

Polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder, skin changes (POEMS) syndrome is a rare paraneoplastic disorder. The polyneuropathy can be the presenting symptom and is typically a painful, motor-predominant polyradiculoneuropathy often mimicking chronic inflammatory demyelinating polyradiculoneuropathy. The presence of a lambda monoclonal protein, elevated vascular endothelial growth factor, systemic features, and treatment resistance are clues to the diagnosis. Castleman disease (CD) is seen in a subset of these patients, and when present the neuropathy is similar but less severe. In contrast, in those patients with purely CD, the neuropathy is often a mild, painless distal sensory neuropathy.

The clinical spectrum of Castleman's disease

Castleman's disease (CD) is a rare, poorly understood lymphoproliferative disease. The spectrum of symptoms and course of disease are broad, but there is no large study describing the natural history of this disease. Basic clinic and laboratory data from the records of 113 patients with CD evaluated at the Mayo Clinic and University of Nebraska were abstracted. The impact of these variables on overall survival (OS) from time of diagnosis was evaluated. Sixty patients had multicentric disease. Of the patients with multicentric CD, 32% had criteria sufficient for a diagnosis of POEMS syndrome. For all patients, 2, 5, and 10-year OS was 92%, 76%, 59%, respectively. Most of the factors identified as risk factors for death on univariate analysis cosegregated with diagnostic criteria for POEMS syndrome, which supported the concept of four categories of CD, which are (along with their 5-year OS): (1) unicentric CD (91%); (2) multicentric CD associated with the osteosclerotic variant of POEMS syndrome (90%); (3); multicentric CD without POEMS syndrome (65%); and (4) multicentric CD with POEMS syndrome without osteosclerotic lesions (27%). We have demonstrated that CD represents a spectrum of disease that can be differentiated by simple prognostic factors that provide a framework for further study.

HIV-associated multicentric Castleman's disease

Multicentric Castleman's disease (MCD), a relatively rare lymphoproliferative disorder that presents with heterogenous symptoms including fevers, anemia, and multifocal lymphadenopathy, is today most commonly observed in individuals infected with human immunodeficiency virus type-1 (HIV). In such individuals, a lymph node biopsy typically identifies cells that stain for Kaposi's sarcoma-associated herpesvirus proteins, and most HIV-associated MCD features can be attributed to the presence of this gamma-herpesvirus. Surgery and antiviral therapies including highly active antiretroviral therapy, interferon-alpha, foscarnet, ganciclovir, and antibodies to interleukin-6 have proved largely ineffective, and chemotherapy in HIV positive individuals is complicated by limited efficacy and pronounced toxicity. While no randomized trials have been performed, more recently the use of the anti-CD20 monoclonal antibody rituximab in large single center cohorts has been associated with prolonged remissions, radiologic responses, as well as hematologic and serum chemistry normalization of the inflammatory picture observed, at the expense of B cell depletion and flare of Kaposi's sarcoma. MCD represents a model of disease at the interplay between tumor biology, infection, and immunology.

Abrogation of viral interleukin-6 (vIL-6)-induced signaling by intracellular retention and neutralization of vIL-6 with an anti-vIL-6 single-chain antibody selected by phage display

Human herpesvirus 8 (HHV-8) encodes several putative oncogenes, which are homologues to cellular host genes known to function in cell cycle regulation, control of apoptosis, and cytokine signaling. Viral interleukin (vIL-6) is believed to play an important role in the pathogenesis of Kaposi's sarcoma as well as primary effusion lymphoma and multicentric Castleman's disease. Therefore, vIL-6 is a promising target for novel therapies directed against HHV-8-associated diseases. By phage display screening of human synthetic antibody libraries, we have selected a specific recombinant antibody, called monoclonal anti-vIL-6 (MAV), binding to vIL-6. The epitope recognized by MAV was localized on the top of the D helix of the vIL-6 protein, which is a part of receptor binding site III. Consequently, MAV specifically inhibits vIL-6-mediated growth of the primary effusion lymphoma-derived cell line BCBL-1 and blocks STAT3 phosphorylation in the human hepatoma cell line HepG2. Since it was previously found that vIL-6 can also induce signals from within the cell, presumably within the endoplasmic reticulum, we fused the recombinant antibody MAV with the endoplasmic retention sequence KDEL (MAV-KDEL). As a result, COS-7 cells expressing MAV-KDEL and synthesizing vIL-6 ceased to secrete the cytokine. Moreover, we observed that vIL-6 that was bound to MAV-KDEL and retained in the endoplasmic reticulum did not induce STAT3 phosphorylation in HepG2 cells. We conclude that the activity of the intracellularly retained vIL-6 protein is neutralized by MAV-KDEL. Our results might represent a novel therapeutic strategy to neutralize virally encoded growth factors or oncogenes.

Immunoglobulin and T-cell receptor gene rearrangement in Castleman's disease: molecular genetic analysis

AIMS

Castleman's disease (CD) is a rare heterogeneous disorder that is associated with an increased risk of developing lymphoma. Whether CD is primarily hyperplastic or neoplastic in origin is not yet clear. The aim of this study was to investigate CD further by determining the clonality status of its lymphocyte populations.

METHODS AND RESULTS

We reviewed 20 patients with CD, 15 with the hyaline-vascular type and five with the plasma cell type. Immunoglobulin (JH) and T-cell receptor (TCR) gene rearrangements were examined using polymerase chain reaction and Southern blotting techniques. B-lymphocyte clonality was also assessed by flow cytometry (FC) and by immunohistochemistry (IHC). The age range of the patients was 15-66 years: nine female and 11 male. Monoclonal rearrangement of the immunoglobulin (JH) gene was detected in only one case. No cases were positive for monoclonal rearrangement of the TCR gene. All of the cases except one were negative for immunoglobulin light chain restriction by both FC and IHC.

CONCLUSIONS

The lymphoid cells in CD are most commonly polyclonal in origin, which supports a non-neoplastic origin. However, rare cases may show lymphocyte monoclonality, which could represent the development of a neoplastic population. The latter cases should be followed closely.

Immunohistochemical and molecular assessment of human herpesvirus type 8 in gastrointestinal tumours

BACKGROUND

Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal tumours of the gastrointestinal tract, histologically identified as highly cellular spindle or epithelioid cell tumours, and often positive for CD34 (60-70%). Kaposi's sarcomas (KSs) are similar to GISTs: they are most often found in the gastrointestinal tract (although cutaneous lesions do occur), they are also composed of spindle or epithelioid cells (although erythrocytes are also seen), and the tumour cells are nearly all positive for CD34. Human herpesvirus type 8 (HHV-8) DNA has been found consistently in all types of KS, in particular in CD34 positive KS tumour cells. However, the association between HHV-8 and GIST has not been investigated.

AIMS

To assess the presence of HHV-8 in GISTs.

METHODS

Paraffin wax embedded tissues of 86 primary GISTs and their recurrent or metastatic tumours were analysed immunohistochemically for the CD34 antigen and HHV-8 latent nuclear antigen 1 (LNA-1) and by means of the nested polymerase chain reaction (PCR) and real time PCR for HHV-8 DNA.

RESULTS

None of the 86 GISTs contained HHV-8 DNA sequences or LNA-1 positive cells.

CONCLUSIONS

These results demonstrate the lack of HHV-8 infection in GIST tumour cells. HHV-8 does not appear to play a role in the pathogenesis of GIST, irrespective of the status of the tumour.

Real-time Fluorescent PCR Techniques to Study Microbial-Host Interactions

This chapter describes how real-time polymerase chain reaction (PCR) performs and how it may be used to detect microbial pathogens and the relationship they form with their host. Research and diagnostic microbiology laboratories contain a mix of traditional and leading-edge, in-house and commercial assays for the detection of microbes and the effects they impart upon target tissues, organs, and systems. The PCR has undergone significant change over the last decade, to the extent that only a small proportion of scientists have been able or willing to keep abreast of the latest offerings. The chapter reviews these changes. It discusses the second-generation of PCR technology-kinetic or real-time PCR, a tool gaining widespread acceptance in many scientific disciplines but especially in the microbiology laboratory.

[Transitional type of Castleman's disease manifested as the POEMS syndrome]

BACKGROUND

Castleman's disease is an atypical lymphoproliferative disorder characterized by angiofollicular hyperplasia of lymph nodes. Histologically, it can be classified into a hyaline-vascular type, plasma-cell type, and transitional (mixed-cell) type, while clinically localized type has been classified as unicentric, or generalized (multicentric) form of the disease.

CASE REPORT

This paper presents a 21 year old male patient with multicentric Castleman's disease, a transitional (mixed-cell) type. The disease was manifested by fever, generalized enlargement of peripheral lymph nodes, breast glands enlargement, hyperemia of the face, and weakness of the lower extremities. We found mediastinal lymphadenopathy, pleural and pericardial effusions, sensorimotor peripheral neuropathy and polyclonal hypergammaglobulinemia. The simultaneous presence of these manifestations of the disease (sensomotor peripheral neuropathy, lymphadenopathy, effusions, endocrinopathy, polyclonal gammaglobulinemia and skin changes) is indentified as POEMS syndrome. The diagnosis of Castleman's disease was based on the results of histopathologic analysis of mediastinal lymph node biopsies after thoracotomy. The patient was treated with corticosteroids (prednisone 80 mg daily for 2 weeks followed by 60 mg daily). A partial response was achieved after 4 months of treatment.

CONCLUSION

A transitional type of multicentric Castleman's disease may be present itself as POEMS syndrome. The effect of corticosteroid therapy in this form of the disease is unpredictable.

Characterization of entry mechanisms of human herpesvirus 8 by using an Rta-dependent reporter cell line

To analyze the mechanisms of entry of human herpesvirus 8 (HHV-8), we established a reporter cell line T1H6 that contains the lacZ gene under the control of the polyadenylated nuclear RNA promoter, known to be strongly activated by a viral transactivator, Rta. We found that infection with cell-free virus, as well as cocultivation with HHV-8-positive primary effusion lymphoma cell lines, activated the lacZ gene of T1H6 in a sensitive and dose-dependent manner. Addition of Polybrene and centrifugation enhanced, but polysulfonate compounds inhibited, the HHV-8 infectivity. RGD-motif-containing polypeptides and integrins did not decrease the infectivity, suggesting the presence of an additional cellular receptor other than the reported one. The entry was dependent on pH acidification but not on the clathrin pathway. Although conditioned media obtained from human immunodeficiency virus (HIV)-infected cells did not have any effect on the early steps of HHV-8 infection, intracellular expression of a proviral HIV type 1, but not of Tat alone, increased the HHV-8-dependent reporter activation slightly, suggesting a potential of HIV-mediated enhancement of an early step of HHV-8 infection.

Castleman's disease in a child presenting with a partly mineralized solitary meningeal mass

We report a case of solitary intracranial childhood Castleman's disease (CD) presenting with a sudden onset of partial seizures due to a meningeal and cortical mass lesion. The patient was a previously healthy 8-year-old girl who developed a new onset of simple partial seizures with motor signs. On physical examination, she was neurologically intact. Other findings included low-grade fever, mild microcytic anemia and lymphopenia. Magnetic resonance imaging (MRI) of the brain revealed a left posterior parietal, partly mineralized, contrast-enhancing meningeal mass with cortical invasion and adjacent white matter edema. A complete surgical resection of the dural-based component and a subtotal resection of the adherent, invasive cortical lesion were performed. Pathohistology and flow cytometry of the dural-based lesion disclosed a hyaline-vascular type of CD with striking proliferation of polyclonal B lymphocytes, scattered plasma cells and extensive multifocal cortical mineralization. At the 6-month follow-up, the patient was seizure free on antiepileptics and had returned to normal daily activities. MRI showed no residual lesion, and a workup for systemic disease was negative.

Charting latency transcripts in Kaposi's sarcoma-associated herpesvirus by whole-genome real-time quantitative PCR

The division into a latent or lytic life cycle is fundamental to all herpesviridae. In the case of Kaposi's sarcoma-associated herpesvirus (KSHV) (human herpesvirus 8), latent genes have been implicated in cell autonomous transformation, while certain lytic genes procure a tumor friendly milieu through paracrine mechanism. To query KSHV transcription, we devised and validated a high-throughput, high-specificity, high-sensitivity, real-time quantitative reverse transcription-PCR array. This novel methodology is applicable to many human pathogens. Its first use demonstrated that the mRNA levels for KSHV LANA, v-cyclin, and v-FLIP do not increase at any time after viral reactivation. The mRNA for LANA-2/vIRF-3 is similarly resistant to viral reactivation. In contrast, every other latent or lytic message was induced. Hence, LANA, v-FLIP, v-cyclin, and LANA-2 constitute a group of uniquely regulated transcripts in the KSHV genome.

Real-time PCR in virology

The use of the polymerase chain reaction (PCR) in molecular diagnostics has increased to the point where it is now accepted as the gold standard for detecting nucleic acids from a number of origins and it has become an essential tool in the research laboratory. Real-time PCR has engendered wider acceptance of the PCR due to its improved rapidity, sensitivity, reproducibility and the reduced risk of carry-over contamination. There are currently five main chemistries used for the detection of PCR product during real-time PCR. These are the DNA binding fluorophores, the 5' endonuclease, adjacent linear and hairpin oligoprobes and the self-fluorescing amplicons, which are described in detail. We also discuss factors that have restricted the development of multiplex real-time PCR as well as the role of real-time PCR in quantitating nucleic acids. Both amplification hardware and the fluorogenic detection chemistries have evolved rapidly as the understanding of real-time PCR has developed and this review aims to update the scientist on the current state of the art. We describe the background, advantages and limitations of real-time PCR and we review the literature as it applies to virus detection in the routine and research laboratory in order to focus on one of the many areas in which the application of real-time PCR has provided significant methodological benefits and improved patient outcomes. However, the technology discussed has been applied to other areas of microbiology as well as studies of gene expression and genetic disease.

Analysis of the human herpesvirus 8 (HHV-8) genome and HHV-8 vIL-6 expression in archival cases of castleman disease at low risk for HIV infection

Lymph nodes from 44 patients with Castleman disease (CD) without risk factors for HIV infection were analyzed with polymerase chain reaction (PCR), in situ hybridization (ISH), and immunohistochemical analysis for human herpesvirus 8 (HHV-8) and viral interleukin-6 (vIL-6). PCR detected HHV-8 genome in 2 of 4 cases; ISH detected it in 9 of 16 cases. HHV-8 vIL-6 peptides were detected in 2 of 44 cases. vIL-6- and ISH-positive cells were found in large transformed and small lymphocytes of the follicular mantle, respectively. Of 9 cases of plasma cell (PC) CD that demonstrated HHV-8 genome by PCR or ISH, 1 expressed vIL-6. Clonal populations of PCs in CD by immunohistochemical analysis or immunoelectrophoresis of serum and urine were associated with neuropathy. HHV-8 vIL-6 detection was associated with poor survival and lack of HHV-8 IL-6, with low risk for subsequent lymphoma. Although HHV-8 genome was detected in a considerable number of patients with PC CD, vIL-6 expression was infrequent. Expression of HHV-8 vIL-6 in CD may indicate poor prognosis in patients at risk for lymphoma who may prospectively require more aggressive treatment. The lack of vIL-6 expression in CD with HHV-8 genome suggests that human IL-6 rather than vIL-6 may be the principal pathogenic cytokine.

Quantitative, fluorogenic probe PCR assay for detection of human herpesvirus 8 DNA in clinical specimens

A quantitative, fluorescence-based PCR assay (TaqMan-based system) was developed for detection of human herpesvirus 8 (HHV-8) DNA in clinical specimens. Primers and probes chosen from each of five 10-kb segments from the unique region of the HHV-8 genome were evaluated for sensitivity with dilution series of DNA extracted from a cell line (BCBL-1) that harbors HHV-8 DNA. Although several of the primer-probe sets performed similarly with BCBL-1 DNA that had been diluted in water, their performance differed when target DNA was diluted in a constant background of uninfected cell DNA, an environment more relevant to their intended use. The two best primer-probe combinations were specific for HHV-8 relative to the other known human herpesviruses and herpesvirus saimiri, a closely related gammaherpesvirus of nonhuman primates. PCRs included an enzymatic digestion step to eliminate PCR carryover and an exogenous internal positive control that enabled discrimination of false-negative from true-negative reactions. The new assays were compared to conventional PCR assays for clinical specimens (saliva, rectal brushings, rectal swab specimens, peripheral blood lymphocytes, semen, and urine) from human immunodeficiency virus-positive patients with or without Kaposi's sarcoma. In all instances, the new assays agreed with each other and with the conventional PCR system. In addition, the quantitative results obtained with the new assays were in good agreement both for duplicate reactions in the same assay and between assays.