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R C Gallo

Publications and source records attributed to R C Gallo.

At least 91 records · Page 5Linked to original sources

Deletion and translocation involving chromosome 3 (p14) in two tumorigenic Kaposi's sarcoma cell lines.

BACKGROUND: Two neoplastic Kaposi's sarcoma (KS) cell lines, KS Y-1 (derived from a patient with KS associated with acquired immunodeficiency syndrome) and KS SLK (derived from an immunosuppressed patient with a renal transplant and KS or iatrogenic KS), have been shown to have abnormal chromosome constitution and to require no exogenous growth factors. They produce malignant tumors in immunodeficient mice. In contrast, all other cell cultures prepared in the past from KS specimens have shown to have normal diploid characteristics are hyperplastic, and depends on cytokines for growth, but they do not produce malignant tumors in immunodeficient mice. PURPOSE: We investigated whether the chromosomal changes that occurred in these KS cell lines were random contribute to the pathogenesis of KS. METHODS: We used the conventional G-banding technique and fluorescence in sti hybridization to identify structural and numerical chromosomal changes in the KS cell lines. RESULTS: We demonstrated that both cell lines are aneuploid and have some additional features in common, i.e., loss of copies of chromosomes 14 and 21 and nonrandom translocations and deletions in the short arm of chromosome 3 at region 3p14. These KS cell lines also exhibits loss of heterozygosity of loci at region 3p14-ter. CONCLUSION: This is the first time nonrandom chromosomal alterations have been described in KS neoplastic cells. On the basis of information available on other available on other cancers, the chromosome 3 alterations observed here can be expected to contribute to the neoplastic process in KS. IMPLICATIONS: Future research should focus on the identification cytogenetic markers, thus facilitating generation of specific molecular probes for detecting neoplastic cells early in the disease process.

Acquired Immunodeficiency Syndrome↗

Interference between human herpesvirus 7 and HIV-1 in mononuclear phagocytes.

Human herpesvirus 7 (HHV-7) uses CD4 as a cellular membrane receptor and thereby interferes with infection of CD4+ T cells by HIV-1. We studied the interactions between HHV-7 and a macrophage-tropic HIV-1 isolate (HIV-1BaL) in terminally differentiated human peripheral blood monocyte-derived macrophages, another critical target for infection by HIV-1 in vivo. Exposure of macrophages to HHV-7 alone yielded no signs of virus replication or cytopathic effects. Nevertheless, when macrophages were pre-exposed to either live or UV-inactivated HHV-7 and subsequently infected with HIV-1BaL, a significant dose-dependent inhibition of HIV-1 replication was documented. At day 7 postinfection, the average level of HIV-1 p24 Ag in cultures from five different donors was reduced by 91.7 +/- 8.3% by pretreatment with live HHV-7 and by 91.8 +/- 8.2% by pretreatment with UV-inactivated HHV-7. Moreover, the synthesis of HIV-1 proviral DNA in macrophages pretreated with HHV-7 was completely inhibited during the early stages after infection, suggesting that HHV-7 blocks HIV-1 at the level of interaction with the CD4 receptor. Consistent with this concept, both macrophage and CD4+ T cell cultures with pre-established HIV-1 infection were not susceptible to inhibitory effects of HHV-7. The proliferative response of PBMC to mitogens was only marginally inhibited by exposure to HHV-7 before mitogen stimulation, indicating that the inhibition of HIV-1 infection was not due to a negative effect on cell proliferation. These data demonstrate that HHV-7 is a powerful inhibitor of HIV-1 infection in cells of the mononuclear phagocytic lineage, despite its inability to replicate actively in such cells.

Adult↗

The V3 domain of the HIV-1 gp120 envelope glycoprotein is critical for chemokine-mediated blockade of infection.

The ability of CD8 T cells derived from human immunodeficiency virus (HIV)-infected patients to produce soluble HIV-suppressive factor(s) (HIV-SF) has been suggested as an important mechanism of control of HIV infection in vivo. The C-C chemokines RANTES, MIP-1 alpha and MIP-1 beta were recently identified as the major components of the HIV-SF produced by both immortalized and primary patient CD8 T cells. Whereas they potently inhibit infection by primary and macrophage-tropic HIV-1 isolates, T-cell line-adapted viral strains tend to be insensitive to their suppressive effects. Consistent with this discrepancy, two distinct chemokine receptors, namely, CXCR4 (ref. 7) and CCR5 (ref. 8), were recently identified as potential co-receptors for T-cell line-adapted and macrophage-tropic HIV-1 isolates, respectively. Here, we demonstrate that the third hypervariable domain of the gp 120 envelope glycoprotein is a critical determinant of the susceptibility of HIV-1 to chemokines. Moreover, we show that RANTES, MIP-1 alpha and MIP-1 beta block the entry of HIV-1 into cells and that their antiviral activity is independent of pertussis toxin-sensitive signal transduction pathways mediated by chemokine receptors. The ability of the chemokines to block the early steps of HIV infection could be exploited to develop novel therapeutic approaches for AIDS.

Amino Acid Sequence↗

New developments: a look to the future.

Inflammatory cytokines plus the human immunodeficiency virus Tat protein apparently trigger the development of early Kaposi's sarcoma. Activated spindle cells provide a self-perpetuating, autocrine-supported mechanism for further development of hyperplastic lesions. In more advanced stages, a true neoplastic process may develop.

Acquired Immunodeficiency Syndrome↗

Human herpesvirus 6 and Epstein-Barr virus in Hodgkin's disease: a controlled study by polymerase chain reaction and in situ hybridization.

Human herpesvirus-6 (HHV-6), a T-lymphotropic double-stranded DNA virus highly endemic in human populations, has been suggested to play a possible role in the development of lymphoid neoplasms, especially Hodgkin's disease. To investigate this point, we evaluated the presence and distribution of HHV-6 DNA by Southern blot, nested polymerase chain reaction, and in situ hybridization in a series of lymphoproliferative disorders including 73 Hodgkin's disease cases, 15 non-Hodgkin lymphomas, and 19 reactive lymph nodes. A high prevalence of HHV-6 infection was observed within the Hodgkin's disease category by polymerase chain reaction (38 of 52, 73%) and in situ hybridization (47 of 57, 82.4%); however, a similar prevalence was found in non-Hodgkin's lymphomas (10 of 15, 66.6%) and reactive lymph nodes (13 of 19, 68.4%). In no case did Southern blot detect viral DNA, suggesting that the neoplastic tissue contained a low number of HHV-6 copies. In situ hybridization showed that the HHV-6 positivity was restricted to lymphocytes, whereas Hodgkin and Reed-Sternberg cells were consistently negative. Immunohistochemical staining with specific monoclonal antibodies against viral structural proteins was also negative, indicating the absence of a productive infection. No relationship was observed between HHV-6 positivity and histological type, clinical parameters, and outcome of the disease. In the same series, a high proportion of cases (39 of 52, 75%) showed the presence of the Epstein-Barr virus (EBV) genome by polymerase chain reaction; In situ hybridization for Epstein-Barr-virus-encoded small RNA and immunohistochemical detection of latent membrane protein-1 gave similar results (73.6% of positive cases with both methods). In 54.9% of the cases, both sequences of HHV-6 and Epstein-Barr virus DNA were found, suggesting that a synergism of the two viruses may occur. However, the lack of detectable HHV-6 DNA in Reed-Sternberg and Hodgkin's cells seems to argue against such an interpretation. Based on these results, HHV-6 does not appear to play a specific role in the pathogenesis of Hodgkin's disease.

Blotting, Southern↗

Identification of RANTES, MIP-1 alpha, and MIP-1 beta as the major HIV-suppressive factors produced by CD8+ T cells.

Evidence suggests that CD8+ T lymphocytes are involved in the control of human immunodeficiency virus (HIV) infection in vivo, either by cytolytic mechanisms or by the release of HIV-suppressive factors (HIV-SF). The chemokines RANTES, MIP-1 alpha, and MIP-1 beta were identified as the major HIV-SF produced by CD8+ T cells. Two active proteins purified from the culture supernatant of an immortalized CD8+ T cell clone revealed sequence identity with human RANTES and MIP-1 alpha. RANTES, MIP-1 alpha, and MIP-1 beta were released by both immortalized and primary CD8+ T cells. HIV-SF activity produced by these cells was completely blocked by a combination of neutralizing antibodies against RANTES, MIP-1 alpha, and MIP-1 beta. Recombinant human RANTES, MIP-1 alpha, and MIP-1 beta induced a dose-dependent inhibition of different strains of HIV-1, HIV-2, and simian immunodeficiency virus (SIV). These data may have relevance for the prevention and therapy of AIDS.

Adult↗

Heterogeneity of spindle cells in Kaposi's sarcoma: comparison of cells in lesions and in culture.

The immunophenotype of spindle cells in epidemic, endemic, and classic (sporadic) Kaposi's sarcoma (KS) lesions was defined by the demonstration of various cell markers and compared with that of KS-derived cell lines. No significant histological or immunophenotypic differences were observed between the three clinical types of KS at comparable stages. The spindle-cell compartment of the different KS types was composed predominantly of a mixture of proliferating CD45+/CD68+ bone-marrow-derived monocytes and TE7+/collagen+ fibroblastic cells with varying expression of EN4/PAL-E/CD31/CD34/CD36 endothelial-associated antigens and/or smooth-muscle-specific alpha-actin (alpha-actin). The latter cells appeared to represent transitional forms of fibroendothelial and fibromyocytic cells. The in vitro cultured KS-derived cell lines (KS-3, KS-6, and KS-8) expressed the fibroblastic antigen TE7 and smooth-muscle-specific alpha-actin but not leukocytic or endothelial-associated antigens consistent with the phenotype of fibromyoid spindle cells of primary lesions. Neither HIV antigen nor provirus DNA was demonstrable in the epidemic KS lesions. The observed heterogeneity of the spindle-cell compartment further substantiates the view that Kaposi's sarcoma, irrespective of clinical setting, expresses salient features more compatible with reactive, tumor-like lesion than clonal sarcoma.

Acquired Immunodeficiency Syndrome↗

Systemic gene therapy: biodistribution and long-term expression of a transgene in mice.

We have investigated the in vivo efficacy of a systemic gene transfer method, which combines a liposomal delivery system (DLS liposomes) with episomally replicative DNA plasmids to effect long-term expression of a transgene in cells. A single i.v. injection of a plasmid DNA vector containing the luciferase gene as a marker was administered with the DLS liposomes in BALB/c mice. The luciferase gene and its product were found in all mouse tissues tested as determined by PCR analysis and immunohistochemistry. Luciferase activity was also detected in all tissues tested and was present in lung, liver, spleen, and heart up to 3 months postinjection. In contrast to the nonepisomal vectors tested (pRSV-luc and pCMVintlux), human papovavirus (BKV)-derived episomal vectors showed long-term transgene expression. We found that these episomal vectors replicated extrachromosomally in lung 2 weeks postinjection. Results indicated that transgene expression in specific tissues depended on the promoter element used, DNA/liposome formulation, dose of DNA per injection, and route of administration.

Animals↗

Angiogenic properties of human immunodeficiency virus type 1 Tat protein.

Extracellular human immunodeficiency virus type 1 (HIV-1) Tat protein promotes growth of spindle cells derived from AIDS-associated Kaposi sarcoma (AIDS-KS), an angioproliferative disease very frequent in HIV-1-infected individuals. Normal vascular cells, progenitors of AIDS-KS cells, proliferate in response to Tat after exposure to inflammatory cytokines, whose levels are augmented in HIV-1-infected individuals and in KS lesions. Here we show that Tat also promotes AIDS-KS and normal vascular cells to migrate and to degrade the basement membrane and stimulates endothelial cell morphogenesis on a matrix substrate. These effects are obtained at picomolar concentrations of exogenous Tat and are promoted by the treatment of the cells with the same inflammatory cytokines stimulating expression of the receptors for Tat, the integrins alpha 5 beta 1 and alpha v beta 3. Thus, under specific circumstances, Tat has angiogenic properties. As Tat and its receptors are present in AIDS-KS lesions, these data may explain some of the mechanisms by which Tat can induce angiogenesis and cooperate in the development of AIDS-KS.

Acquired Immunodeficiency Syndrome↗

Tumorigenesis and metastasis of neoplastic Kaposi's sarcoma cell line in immunodeficient mice blocked by a human pregnancy hormone.

Kaposi's sarcoma (KS) occurs more often in men than in women and HIV-1-associated KS has a high occurrence in homosexual men (over 30%). Most cultures of KS tumours yield cells with properties of hyperplastic (not malignant) endothelial cells under the control of several cytokines. The role of HIV-1 may be in promoting high levels of some cytokines and providing stimulation to angiogenesis by the HIV-1 Tat protein, which synergizes with basic fibroblast growth factor in promoting these effects. Here we describe an immortalized AIDS-KS cell line (KS Y-1) and show that these cells produce malignant metastatic tumours in nude mice and are killed in vitro and in vivo (apparently by apoptosis) by a pregnancy hormone, the beta-chain of human chorionic gonadotropin. Similarly, chorionic gonadotropin kills KS SLK, cells from another neoplastic cell line (established from a non-HIV-associated KS), as well as the hyperplastic KS cells from clinical specimens grown in short-term culture, but does not kill normal endothelial cells. These results provide evidence that KS can evolve into a malignancy and have implications for the hormonal treatment of this tumour.

Acquired Immunodeficiency Syndrome↗

Self-limiting, cell type-dependent replication of an integrase-defective human immunodeficiency virus type 1 in human primary macrophages but not T lymphocytes.

Integration of retroviral DNA into the host cell genome, catalyzed by the integrase (IN) protein, is thought to be required for replication. We show here that one IN-minus defective mutant of human immunodeficiency virus type 1 (HIV-1) is able to replicate in macrophages but not in peripheral blood lymphocytes (PBLs). Replication of the HIV-1 defective mutant, however, was inefficient and self-limiting. The absence of integration in the HIV-1 IN mutant in contrast to the wild-type implies that the replication of the IN mutant depends on the transcription of the extrachromosomal forms of viral DNA. In both PBLs and macrophages circular forms of DNA were detected at significant levels, indicating that the lack of a complete functional IN protein does not preclude nuclear import of HIV-1 DNA. Cell-associated p24 was absent in the IN-defective-infected PBLs, suggesting a transcriptional block of the extrachromosomal forms of HIV-1. These results show the existence of different strategies for HIV-1 replication depending upon the cell type, and indicate the necessity of integration of viral DNA for the self-maintained progression of the infection.

Cells, Cultured↗

Inflammatory cytokines induce AIDS-Kaposi's sarcoma-derived spindle cells to produce and release basic fibroblast growth factor and enhance Kaposi's sarcoma-like lesion formation in nude mice.

Homosexual males often present signs of immune activation and are likely to have increased levels of inflammatory cytokines such as IL-1 beta, TNF-alpha, and IFN-gamma. These individuals develop Kaposi's sarcoma (AIDS-KS) more frequently than other HIV-1-infected groups. Our previous work demonstrated that inflammatory cytokines stimulate the growth of spindle cells derived from AIDS-KS lesions (AIDS-KS cells) and that these cells produce high levels of bFGF that mediate autocrine and paracrine (endothelial) cell growth and angiogenesis. Here we show that AIDS-KS cells constitutively produce and release bioactive bFGF in the absence of cell death, and that extracellular bFGF exist in both a soluble and a bound form; the latter can be released by treatment with trypsin, heparin, or heparinase I. Inflammatory cytokines stimulate both the synthesis and release of biologically active bFGF from KS cells and enhance their ability to induce angiogenic KS-like lesions in nude mice. Because bFGF is highly expressed in primary KS lesions, and is a mediator of KS-like lesion formation, these results suggest that the export of bFGF induced by inflammatory cytokines may play a critical role in the induction and progression of KS in HIV-1-infected homosexual men.

Acquired Immunodeficiency Syndrome↗

Human herpesvirus 6 in AIDS.

Multiple lines of clinical and experimental evidence suggest that human herpesvirus 6 (HHV-6) may act as an accelerating factor in the natural history of human immunodeficiency virus (HIV) infection. Although, in common with HIV, HHV-6 has a primary tropism for CD4+ T cells, its potential effects on the immune system are broader. For instance, HHV-6 can also infect and kill CD8+ T cells, natural killer cells and mononuclear phagocytes. Here, Paolo Lusso and Robert Gallo suggest that understanding the immunopathogenic role of HHV-6 in the course of HIV infection may shed new light on the complex mechanisms of disease progression in AIDS.

Acquired Immunodeficiency Syndrome↗

Human herpesvirus 6.

HHV-6, the first T-lymphotropic human herpesvirus, is an important novel human pathogen. It is the cause of exanthem subitum in infants and may act as an opportunistic agent in immunocompromised patients. Moreover, several lines of clinical and experimental evidence suggest that HHV-6 may accelerate the progression of HIV infection. Progress in the study of HHV-6 has been rapid, in part as a consequence of the strong current interest in human lymphotropic viruses and their relationship with the immune system. Nonetheless, the full spectrum of diseases linked to this agent is still unknown (Table 2) and animal models of infection have not yet been exploited. The next few years will be crucial for a complete understanding of the potential role of HHV-6 in human disease.

Acquired Immunodeficiency Syndrome↗