In situ hybridization analysis of cytomegalovirus lytic infection in Kaposi's sarcoma associated with AIDS. A study of 14 autopsy cases

Kaposi's Sarcoma: A Clinico-Pathologic Overview

A careful overview of the classical appearances of Kaposi's sarcoma (KS) as well as of its variants were reviewed from the clinical and pathological point of view. The growth phases (stages) and the cellular patterns were histopathologically compared with emphasis on the developmental progression of disease as well as mitotic activity. Other morphological aspects were also assessed such as the features of the early phases and the incidence of hyaline bodies. One hundred and forty-three lesions from 96 patients mostly of the Italian sporadic type were investigated. A complete list of those entities which should be considered in differential diagnosis is shown and the dilemma of whether KS is a neoplasia or a hyperplasia is discussed.

Cutaneous vascular proliferations. Part III. Malignant neoplasms, other cutaneous neoplasms with significant vascular component, and disorders erroneously considered as vascular neoplasms

In this third and last part of our review of cutaneous vascular proliferations we include malignant vascular neoplasms and a group of heterogeneous cutaneous neoplasms characterized by a significant vascular component. We also review some disorders that, in our opinion, have been erroneously considered as vascular neoplasms. We review the epidemiologic, histogenetic, clinical, and histopathologic aspects of Kaposi's sarcoma in its four distinctive variants (classic, African-endemic, immunosuppressive drug-associated, and AIDS-associated Kaposi's sarcoma). There is still controversy about whether Kaposi's sarcoma represents a reactive vascular proliferation or a true neoplastic proliferation. In any event, most authors believe that Kaposi's sarcoma does not produce metastatic disease, but rather develops in multifocal fashion. However, Kaposi's sarcoma may cause death, especially in immunosuppressed patients. Epithelioid hemangioendothelioma, Dabska's tumor, and retiform hemangioendothelioma are examples of low-grade angiosarcoma. In contrast, cutaneous angiosarcomas, including the clinical variants of angiosarcoma of face and scalp in elderly patients, angiosarcoma associated with lymphedema, and radiation-induced angiosarcoma are highly aggressive neoplasms with poor prognosis and most patients die within a short period after presentation. A group of benign and relatively frequent cutaneous neoplasms, including multinucleate cell angiohistiocytoma, angiofibroma, angioleiomyoma, angiolipoma, cutaneous angiolipoleiomyoma, and cutaneous angiomyxoma are here covered because of their significant vascular component. Finally, we review briefly a series of cutaneous disorders that have been erroneously considered as vascular neoplasms. Kimura's disease is an inflammatory reactive condition of unknown origin, "benign" angioendotheliomatosis is a reactive intravascular proliferation of endothelial cells that occurs in the skin as a response to a variety of stimuli, "malignant" angioendotheliomatosis is an intravascular lymphoma, and acral pseudolymphomatous angiokeratoma of children (APACHE) is better interpreted as a pseudolymphoma.

Pathogenesis of AIDS--related Kaposi's sarcoma. Evidence of a viral etiology

Kaposi's sarcoma is the most common malignancy in patients with HIV infection. New studies point to the involvement of a new human Kaposi's sarcoma herpes virus (KSHV) as a transforming agent. After transformation, cytokine perturbations facilitate growth and in some cases clonal growth occurs. This results in a malignancy with devastating clinical consequences. A clear understanding of the mechanism of transformation by KSHV will lead to better therapies.

Kaposi's sarcoma of internal organs. A multiparameter study of 86 cases

BACKGROUND

During the past decade, Kaposi's sarcoma (KS), one of the most common acquired immune deficiency syndrome-defining diseases, has been the subject of sustained research. However, basic questions about its etiology, histogenesis, growth, and dissemination remain unanswered. Even its nature, whether hyperplasia or neoplasia, is still controversial. Most studies and concepts to date have been based on dermatologic KS. The present study, in contrast, examines by various parameters a series of patients with KS of internal organs.

MATERIALS AND METHODS

The series includes 86 cases (39 surgical specimens and 47 autopsies) of visceral and disseminated KS. The study is focused on the gross distribution of lesions, the mode of dissemination, the histologic patterns, and the cellular immunophenotypes, which are investigated with the use of 18 monoclonal antibodies.

RESULTS

The involvement of various organs, multiplicity of lesions, and progression of tumors were recorded. Seven histologic patterns forming a spectrum of cellular differentiation were distinguished. Immunophenotypes characteristic for different histologic patterns were recognized. Although some cell markers such as those recognized by antibodies against Factor VIII R-Ag, Actin, and Ulex europaeus were restricted to the well differentiated KS cells, others including CD34 and CD31 demonstrated a strong affinity for the entire spectrum of KS cell differentiation.

CONCLUSION

The present study of KS of internal organs revealed that poor grades of histologic and immunophenotypic differentiation correlated with invasion and dissemination, which are fundamental characteristics of malignant tumors.

Circulating endothelial giant cells permissive for human cytomegalovirus (HCMV) are detected in disseminated HCMV infections with organ involvement

Giant cells fully permissive for human cytomegalovirus (HCMV) were found to circulate, at a variable proportion, in peripheral blood of 21 out of 25 immunocompromised patients with disseminated HCMV infection. Circulating endothelial giant cells (EGC) were identified by a specific monoclonal antibody of endothelial origin and shown to express immediate-early, early, and late viral proteins. Immunostaining patterns of different viral proteins were comparable to those detected in vitro in cultured human umbilical vein endothelial cells. EGC counts > 10 were associated with high levels (> 100) of HCMV viremia and antigenemia, as well as with an overt clinical syndrome in transplanted patients, and to an untreated long lasting organ localization in AIDS patients. On the other hand, EGC counts were < 10 during disseminated HCMV infections of both transplant recipients with no apparent organ syndrome and AIDS patients with recent organ involvement. In tissue sections from AIDS patients, infected endothelial cells were found to progressively enlarge till detaching from the small vessel wall and entering blood stream. HCMV-infected EGC represent a new systemic parameter suitable for the diagnosis of HCMV organ involvement and for the study of the pathogenesis of disseminated infections.

Kaposi's sarcoma. Epidemiology, pathogenesis, histology, clinical spectrum, staging criteria and therapy

The acquired immunodeficiency syndrome (AIDS) epidemic has had a profound impact on our understanding of Kaposi's sarcoma (KS). Epidemiologic features suggest a sexually transmitted cofactor in the pathogenesis of AIDS-associated KS (AIDS-KS), and several putative agents have received intense scrutiny. Cell culture studies suggest that the angiogenesis of AIDS-KS is stimulated by both human immunodeficiency virus proteins and growth factors that may be involved in the development and progression of AIDS-KS, thereby providing a rationale for new therapeutic interventions. The dermatologist is uniquely qualified to provide care for the majority of patients with KS, as many patients have cutaneous lesions amendable to local therapy (cryotherapy, intralesional therapy, simple excision). Patients requiring more aggressive local therapy (radiation therapy) or systemic therapies (interferon, chemotherapy) can be easily recognized. Standardized staging criteria provide assistance for determining appropriate local or systemic therapy and for evaluating and comparing responses to new therapies. This article reviews the epidemiology, pathogenesis, histologic features, clinical spectrum, staging criteria, and treatment of KS.

Kaposi's sarcoma: a review of gene expression and ultrastructure of KS spindle cells in vivo

The ultrastructural features and the gene expression pattern of Kaposi's sarcoma (KS) spindle cells in vivo suggest that KS is a tumor of the mixed cell type. The expression pattern of cytokines and cytokine receptors in the tumor lesion, together with the results obtained from in vitro characterization of KS-derived cells, provide evidence that paracrine mechanisms of growth factor action are important for the maintenance of KS. The reports on virus infection of KS cells suggest an indirect role of virus infection in the induction of KS, most likely mediated by immunostimulation and subsequent production of cytokines.

Preservation of natural endothelial cytopathogenicity of cytomegalovirus by propagation in endothelial cells

Cytomegalovirus (CMV) is a source of major complications in immunosuppressed individuals, and endothelial involvement in CMV infection is well documented. Traditionally the virus has been propagated in fibroblasts, however this process may alter CMV's characteristics, thereby limiting the fibroblast model's utility as a research tool. In our efforts to develop a more accurate in vitro model of CMV/endothelial cell interaction, we have propagated a recent isolate (CMV VHL) through multiple passages in human umbilical vein endothelial cells (HUVE) and, collaterally in neonatal human dermal fibroblasts (NHDF). Infection of HUVE inoculated with either sub-strain of the virus was confirmed by CMV-specific in situ hybridization and by immunocytochemical staining for CMV antigens. Whereas infection of HUVE by substrain VHL/E (endothelial-raised) was accompanied by dramatic cytopathology resembling that observed clinically, the endothelial cytopathic potential of VHL/F (fibroblast-raised) was lost by its 20th passage in NHDF. Similarly, the ability of VHL/F to initiate sustained productive infection in HUVE was severely attenuated; plaque assay of culture supernatants and infected cell fractions, as well as virus-specific DNA polymerase assay of cell lysates, demonstrated progressive viral reproductive activity in VHL/E-inoculated HUVE, whereas VHL/F reproduction was barely detectable. Since properties of VHL/F bear strong resemblance to those of the fibroblast-raised AD169, these studies suggest that while the fibroblast adaptation process commonly employed in the propagation of CMV restricts the host range of the virus and attenuates its spectrum of cytopathic potential, endothelial-based propagation preserves the natural endothelial cytopathogenicity of the original isolate.

Comparison of in situ hybridization and immunohistochemistry for detection of cytomegalovirus and herpes simplex virus

In situ hybridization (ISH) and immunohistochemistry (IHC) were compared for detection of cytomegalovirus (CMV) and herpes simplex virus (HSV) in routinely processed tissue. Fifty-four formalin-fixed paraffin-embedded tissue samples infected with CMV (36 tissues) or HSV (18 tissues) from 30 autopsies were studied. All tissues had either positive viral cultures (38 of 54) or characteristic viral inclusions on hematoxylin and eosin examination (39 of 54). The tissues examined included lung (28), liver (nine), kidney (five), heart (three), adrenal (two), spleen (two), and thymus, pancreas, appendix, esophagus, and duodenum (one each). Studies by ISH were performed with two detection systems, using biotinylated probes to CMV and HSV (Enzo Biochem, New York, NY). Using ISH with an alkaline phosphatase detection system, infected cells were detected in 33 of 54 tissues (CMV: 23 of 36, HSV: 10 of 18). Using ISH with a peroxidase detection system, infected cells were identified in 30 of 54 tissues (CMV: 22 of 36, HSV: eight of 18). With IHC, antibodies to CMV and HSV stained the infected cells in 34 of 54 tissues (CMV: 24 of 36, HSV: 10 of 18). All infections detected with ISH were also detected with IHC. We conclude that these techniques for ISH and IHC are equally effective for detecting CMV and HSV in paraffin sections. The results of both techniques correlate better with viral inclusions than with culture results. The ISH stains are more difficult to prepare and in some cases are more difficult to interpret. Therefore, IHC may be preferable to ISH for detecting CMV and HSV in routine diagnostic work.

In situ nucleic acid hybridization

Nucleic acid hybridization is a recently developed laboratory technique that allows identification of the genetic material in tissue specimens. The role of the nucleic acids DNA and RNA in cellular function and disease is reviewed, followed by discussion of nucleic acid detection techniques. Earlier methods used to detect nucleic acids were slow and time-consuming. Current in situ detection techniques allow rapid characterization of pathogenic organisms in tissue sections and localization of the pathologic genetic material to specific cellular regions. This technology has been useful in the understanding of viral ocular diseases including herpes keratitis and cytomegalovirus retinitis and also has great potential in the understanding of the pathogenesis of human cancers, genetic disorders and endocrine and immunologic diseases.

Enhanced endothelial cytopathogenicity induced by a cytomegalovirus strain propagated in endothelial cells

Endothelial involvement has been implicated in cytomegalovirus (CMV) infection, a source of major complications in immunosuppressed individuals (e.g., those with acquired immune deficiency syndrome [AIDS] and organ transplants). Traditionally, CMV has been grown in fibroblasts; however, propagation in these cells may alter characteristics of the virus. In developing an in vitro model system of CMV/endothelial cell interaction, we have addressed this issue by propagating a clinical isolate, CMV VHL 1, in human umbilical vein endothelial (HUVE) cells by serial cocultivation of heavily infected cultures with fresh HUVE monolayers and have compared its infectious properties with those of the fibroblast-raised strain, CMV AD169. In situ hybridization using a biotinylated DNA probe, as well as immunofluorescent staining for CMV-specific antigen, has confirmed infection of HUVE cells inoculated with either strain of the virus. Infection of HUVE by VHL was accompanied by dramatic cytopathology not observed in AD169-infected cells. Plaque assay of culture supernatants revealed greater virus production in VHL-infected HUVE as compared with equivalently inoculated fibroblasts. In contrast, AD169 production in inoculated fibroblasts exceeded that in HUVE. These studies demonstrate the suitability of cultured endothelial cells as a substrate for CMV propagation and suggest that a strain of virus thus propagated may offer an accurate model of CMV/endothelial cell interaction in human disease.