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J Menezes

Publications and source records attributed to J Menezes.

At least 37 records · Page 2Linked to original sources
PubMed1999

[Serologic study of human herpesviruses 6 and 7 in lymphoma patients].

DNA sequences, antigens and elevated antibodies to HHV-6, and DNA sequences of HHV-7 in patients with Hodgkin's disease and non-Hodgkin's lymphoma have been detected. It is not known whether HHV-6 variants A and B, and HHV-7 contribute to the malignization by different ways, there is any interaction between these viruses, and their primary or recurrent infections occur during the disease progression. Total and high avidity IgG, IgM to HHV-6A, HHV-6B and HHV-7 were quantitated simultaneously in the sera of 12 patients with lymphomas and 12 control persons by indirect immunofluorescent assay and ELISA. It was established that, primary infection by HHV-6B in Hodgkin's disease, its primary or recurrent infections in non-Hodgkin's lymphoma; primary or recurrent infection by HHV-6A in Hodgkin's disease, its recurrent infection in non-Hodgkin's lymphoma; recurrent infection by HHV-7 in Hodgkin's disease may contribute to the deterioration of clinical conditions. Probably, HHV-7 exerts its effects through activating HHV-6B. The simultaneous effects of HHV-7 and HHV-6A, and that of HHV-6B and HHV-6A seem to be independent. Our results supports the recent opinion that, the effect of these herpesviruses on the tumorous cells is exerted indirectly by altered mediators of the immune system.

Female↗
PubMed1999

[Presence of antibodies to human herpesvirus type 6 and 7 in Hungarian children].

Prevalence of antibodies to variants HHV-6A and B as well as HHV-7, the time of primary infections are not know in Hungarian children. Therefore, antibodies to these viruses were studied in 21 healthy children aged between 6 and 18 months. Lymphoid cultures were infected with standard virus strains for indirect immunofluorescence. IgM, IgG and high avidity IgG after 8M urea treatment were quantified in serial dilutions of sera. It was established that, three of 13 boys had low level (1:20) IgG or IgM antibodies to HHV-6A, but all girls were negative. With exception of one girl and one boy, all had antibodies to HHV-6B in different titres (1:20 to 1:640 by immunofluorescence), in 9 cases only IgM, in further 4 cases only low avidity IgG were detected. Children studied gradually acquired symptom-free HHV-6B infection between age of 8 and 18 months. Antibodies to HHV-7 were found in 3 boys and one girl before their age of 12 months, but the majority were infected after that age. Approximately three quarters of children acquired either HHV-6B or HHV-7 before age of 18 months. More than half of the children were infected with HHV-6B prior to HHV-7. Antibody level to HHV-6B was slightly higher in boys, while that to HHV-7 was higher in girls. In Hungary, childhood infection with HHV-6A seems to be a very rare event. Epidemiology of HHV-6B primary infection is similar to that of industrial countries, while that of HHV-7 resembles data of developing world: onset of antibodies occurs 1 or 2 years earlier than in the industrial nations.

Antibodies, Viral↗
PubMed1999

Modulatory effects of human herpes virus-7 on cytokine synthesis and cell proliferation in human peripheral blood mononuclear cell cultures.

Human herpes virus-7 (HHV-7) infects cells of the immune system and thus may modulate their function. To investigate the potential immunomodulatory effects of this virus, we performed an in vitro study in which we investigated effects of HHV-7 on the synthesis of several key immunomodulatory cytokines, i.e. tumor necrosis factor alpha (TNF-alpha), interleukin-2 (IL-2), interferon-gamma (IFN-gamma), IL-4, IL-6, and transforming growth factor beta (TGF-beta). This was examined after in vitro infection of human peripheral blood mononuclear cells (PBMC) with HHV-7. We found elevated levels of TNF-alpha, TGF-beta, and IFN-gamma in the supernatants of HHV-7-infected cells. By reverse transcriptase-polymerase chain reaction (RT-PCR) analysis, using cytokine-specific primers, we found that levels of TNF-alpha, TGF-beta, and IFN-gamma mRNA were increased in the infected cells. The HHV-7 infection also significantly (P < 0.05) decreased the production of IL-2 from activated, IL-2-producing PBMC. Furthermore, mitogen- and cytokine-induced cellular proliferative responses of human PBMC were found to be significantly (P < 0.05) down-regulated by this virus. On the other hand, HHV-7 did not affect IL-4 and IL-6 synthesis. Overall, our results indicate that HHV-7 infection causes significant immunomodulatory effects with regard to cytokine synthesis in these cells as well as inhibiting lymphocyte proliferation by various stimuli.

Cell Division↗
PubMed1999

Epstein-Barr virus envelope glycoprotein gp350 induces NF-kappaB activation and IL-1beta synthesis in human monocytes-macrophages involving PKC and PI3-K.

Epstein-Barr virus (EBV) is a highly immunotropic human herpesvirus with oncogenic potential and is involved in numerous pathologies. EBV utilizes its major envelope glycoprotein gp350 to bind to its receptor CR2/CD21 on target cells for initiating the infection. We have previously shown that EBV is able to modulate transcription and translation of a number of cytokine genes via its gp350-mediated binding to this receptor. However, the effects of the binding of purified gp350 to CR2/CD21 on plastic-adherent monocyte-macrophages (AMM) have not been investigated. These cells are a rich source of potent proinflammatory and immune-modulating cytokines, and express low levels of CR2/CD21. We show here for the first time that recombinant gp350 (rgp350) causes production of the potent proinflammatory cytokine IL-1beta in human AMM. Surprisingly, rgp350 is comparable in this capacity to the phorbol ester 12-0-tetradecanoylphorbol 13-acetate. This induction of IL-1beta production was accompanied by increased steady-state levels of its mRNA in gp350-treated AMM, and was dependent on the specific binding of rgp350 to the EBV receptor CR2/CD21. We also show that the signaling pathways resulting in the induction of IL-1beta synthesis by rgp350 required protein kinase C and phosphatidylinositol 3,4,5 triphosphate kinase activities and occurred via activation of the NF-kappaB family of transcription factors.-D'Addario, M., Ahmad, A., Xu, J. W., Menezes, J. Epstein-Barr virus envelope glycoprotein gp350 induces NF-kappaB activation and IL-1beta synthesis in human monocytes-macrophages involving PKC and PI3-K.

Antibodies, Monoclonal↗
PubMed1999

Neutrophil accumulation and damage to the gastric mucosa in resuscitated hemorrhagic shock is independent of inducible nitric oxide synthase.

Polymorphonuclear leukocytes (PMN) and inducible nitric oxide synthase (iNOS) appear to play important roles in the liver and in lung injury induced by hemorrhagic shock. Their precise roles in hemorrhagic shock-induced acute gastric mucosal lesions (AGML), however, are still poorly understood. In this study, we investigated the effect of neutropenia on hemorrhagic shock-induced AGML. We also examined the roles of iNOS in PMN infiltration into the mucosa and AGML during hemorrhagic shock by using L-N6-(1-iminoethyl)-lysine, a potent inhibitor of iNOS, and by reverse transcriptase polymerase chain reaction. Remarkable gastric mucosal damage occurs after hemorrhagic shock. PMN depletion caused by Vinblastine pretreatment significantly attenuates this AGML. Although low-dose L-N6-(1-iminoethyl)-lysine (50 microg/kg, iNOS inhibition) has no effect on AGML, high-dose L-N6-(1-iminoethyl)-lysine (250 microg/kg, iNOS + endothelial NOS inhibition) significantly exacerbates AGML without increasing PMN infiltration into the mucosa. The mRNA expression of iNOS in the stomach during hemorrhagic shock cannot be detected by reverse transcriptase polymerase chain reaction. We conclude that PMN play a pivotal role in hemorrhagic shock-induced AGML, iNOS does not regulate PMN infiltration into the mucosa, and endothelial NOS provides important protection against AGML during hemorrhagic shock.

Animals↗
PubMed1999

A novel nitric oxide scavenger decreases liver injury and improves survival after hemorrhagic shock.

We tested the ability of a nitric oxide (NO) scavenger to reduce tissue injury in a rodent model of hemorrhagic shock. Rats were hemorrhaged to a mean arterial blood pressure (MAP) of 40 mmHg and then resuscitated when either 30% of their shed blood had been returned (group 1) or after 100 min of continuous shock (group 2). Selected animals were treated with the NO scavenger NOX (30 mg. kg(-1). h(-1)) infused over 4 h. Hemorrhaged rats had a lower MAP after resuscitation compared with sham-shock control rats. NOX treatment significantly increased MAP after resuscitation from hemorrhage. Hemorrhagic shock also increased liver injury as reflected by elevated ornithine carbamoyltransferase (OCT) plasma levels, and NOX treatment significantly reduced OCT release. In addition, NOX was associated with significantly decreased hepatic neutrophil infiltration and improved 24-h survival (n = 8 of 9) compared with saline-treated shock animals (n = 3 of 9). These data suggest that excess NO mediates shock-induced tissue injury and that suppression of NO availability with NO scavengers may reduce the pathophysiological sequelae of severe hemorrhage.

Animals↗
PubMed1998

The Epstein-Barr virus (EBV) major envelope glycoprotein gp350/220-specific antibody reactivities in the sera of patients with different EBV-associated diseases.

gp350 of Epstein-Barr virus (EBV) induces a strong immune response in EBV-infected individuals, but relatively little is known about the clinical relevance of this response in patients with different EBV-associated malignancies and other diseases. Using our gp350-expressing cell clones, we studied gp350-specific humoral immune responses in the sera of individuals with nasopharyngeal carcinoma (NPC), chronic symptomatic EBV infection (CEI), Hodgkin's disease (HD), acute infectious mononucleosis (IM) and healthy EBV-seropositive individuals (HI). The titres of antibody-dependent cellular cytotoxicity (ADCC) antibodies were highest in HI followed by CEI, HD and NPC. EBV-neutralizing (NA) and gp350-specific IgG antibody profiles in these conditions were: CEI > HI > NPC > HD, whereas IgA titres were the highest in NPC sera followed by CEI and HD. The sera from IM patients were found to be negative for gp350-specific ADCC and IgA activities. Sera from HI were also negative for gp350-specific IgA. A significant positive correlation was found between serum gp350 IgA and viral capsid antigen IgA and a significant negative one between IgM and ADCC titres. High IgA titres were also found in CEI and EBV-genome positive HD in addition to NPC. Importantly, gp350-specific IgA titres were of prognostic value in NPC patients. Our data provide new insights about the clinical relevance of gp350-specific immune responses in these diseases.

Antibodies, Viral↗
PubMed1998

Binding of the endogenously expressed Epstein-Barr virus (EBV) envelope glycoprotein gp350 with the viral receptor masks the major EBV-neutralizing epitope and affects gp350-specific ADCC.

The major neutralizing epitope (MNE) for the Epstein-Barr virus (EBV) is present on its envelope glycoprotein gp350/220 (hereafter referred to as gp350) in close proximity to the virus-receptor (CR2) binding site and is recognized by the neutralizing murine monoclonal antibody (mAb) 72A1. We studied the reactivities of 72A1 and another anti-gp350 mAb 2L10 (which does not neutralize EBV) with gp350 expressed on three different lymphoid cell lines (Raji, CEM.NKr and BJA-B). Our results indicate that gp350 expressed on the surface of CR2-positive cells interacts with the viral receptor and that this interaction masks the major EBV-neutralizing epitope. The interaction was reversible and the masked epitope was revealed on incubation with an excess of anti-CR2 mAb OKB7. Gp350-expressing CEM-NKr cells with intact MNE exhibited significantly higher (P < or = 0.05) lysis in gp350-specific antibody-dependent cellular cytotoxic assays compared with its Raji counterpart. The present results may have important implications for the use of soluble viral receptors as therapeutic agents in acute and chronic EBV and other viral infections (e.g., HIV-1).

Antibodies, Blocking↗
PubMed1997

Enhancement of natural killer cell cytotoxicity by the human herpesvirus-7 via IL-15 induction.

NK cells, a key component of the innate immune system, are known to play an important role against viral infections. Previously, we reported that the human herpesvirus-6 (HHV-6) induces IL-15 in human PBMC and increases their NK activity. We describe in this work that another human herpesvirus, HHV-7, which shares genomic homology with HHV-6, also causes up-regulation of NK cell cytotoxicity via IL-15 induction. The NK cell activity of the PBMC from different donors displayed a variable range of enhancement after treatment with HHV-7. This enhancement occurred within a few hours of exposure to the virus and was blocked by Abs to IL-15, but not to other cytotoxicity-enhancing cytokines (i.e., to IFN-gamma, IL-2, TNF-alpha, or IL-12). Our results also show that this HHV-7-induced IL-15-mediated activation of NK cells occurs via IL-2R, since HHV-7-enhanced NK cytotoxic activity could be blocked completely by anti-IL-2R beta-chain mAb (anti-CD122). The up-regulation of NK cell cytotoxicity did not require infectious virus, as the use of UV-irradiated HHV-7 produced similar results. This effect was virus specific because it was abrogated by neutralizing the virus with human sera containing Abs to HHV-7. We also found increased amount of IL-15 transcripts in HHV-7-treated PBMC as compared with the untreated PBMC. Taken together, these results would suggest that host responds to HHV-7 infection by up-regulating IL-15 production, which then results in an enhancement of NK cell activity; this, in turn, may play a major role in the control of the viral infection.

Adjuvants, Immunologic↗
PubMed1997

Enhancement of natural killer and antibody-dependent cytolytic activities of the peripheral blood mononuclear cells of HIV-infected patients by recombinant IL-15.

Natural killer (NK) cells are an important subset of lymphocytes capable of killing virus-infected target cells without prior sensitization. HIV-infected individuals show impairment of their NK cell activity. Although the mechanism responsible for this defect remains unclear, NK cytotoxicity of lymphocytes from these individuals can be partially restored by interleukin (IL)-2. IL-15 is a recently discovered cytokine that shares many biologic activities with IL-2--for example, enhancement of NK activity. In this study, we investigated the effect of recombinant IL-15 (rIL-15) on the NK and antibody-dependent cellular cytotoxicity (ADCC) effector activities of peripheral blood mononuclear cells (PBMCs) from HIV-infected individuals using K562 cell line and HIV gp120-expressing cells. The effect of anti-IL-15 antibodies on NK activity was also examined using PBMCs of HIV-seronegative individuals. Our results show that NK and ADCC activities of PBMCs in HIV-seropositive patients were significantly lower than those of seronegative donors (p < or = 0.05). However, these two activities were significantly enhanced when rIL-15 was added to the assay wells (p < or = 0.05). Moreover, addition of saturating concentrations of neutralizing monoclonal antibodies (mAb) specific for IL-2, IL-12, or interferon (IFN)-gamma in the assays failed to inhibit IL-15-mediated enhancement of NK cell functions. Only the antibody against IL-15 abrogated the upregulation of NK and ADCC activities mediated by IL-15, suggesting that this cytokine enhances NK cell functions through a mechanism that is independent of the induction of other cytokines. IL-15 did not exert any modulatory effect on the expression of CD16 or CD56 molecules. Our results show that IL-15 can increase the NK and ADCC activities of the PBMCs of HIV-infected individuals in vitro. In view of its higher therapeutic index as determined using murine models, IL-15 may represent a better immunotherapeutic agent than IL-2 to restore these functions in HIV-seropositive patients.

Antibodies, Monoclonal↗
PubMed1997

Binding of the Epstein-Barr virus to human platelets causes the release of transforming growth factor-beta.

Human platelets bear on their surface complement receptor type II (CR2), which is also the receptor for the EBV. Although the cross-linking of these receptors causes activation and aggregation of platelets, no immunologic consequence of the potential binding of EBV to these receptors on human platelets has ever been described. We report here that binding of EBV to human platelets causes the release of TGF-beta from the latter. Both infectious and UV-inactivated noninfectious viral particles can mediate this release. Anti-CR2 mAb OKB7, which blocks the binding of EBV to CR2, also blocks the EBV-mediated release of TGF-beta. Furthermore, platelets recovered from the initial incubation no longer release TGF-beta upon subsequent incubation with EBV. Since TGF-beta is a potent immunosuppressive agent, its release from platelets upon binding of EBV may play a role in the pathogenesis of EBV-associated diseases.

Antibodies, Monoclonal↗
PubMed1997

Antibody and antibody-dependent cellular cytotoxicity responses against the BamHI A rightward open-reading frame-1 protein of Epstein-Barr virus (EBV) in EBV-associated disorders.

Antibody-dependent cellular cytotoxicity (ADCC) is an important antiviral effector mechanism. ADCC to the protein encoded by the Epstein-Barr virus (EBV) BamHI A rightward open-reading frame-1 (BARF1) was studied by transducing Raji-tk- cells with the BARF1 gene using a retroviral expression vector. The transduced Raji cells expressed BARF1 on the cell surface, as determined by flow cytometry. Sera from chronic and acute infectious mononucleosis and nasopharyngeal carcinoma patients were found to contain antibodies that react with the BARF1 protein. When BARF1-expressing Raji cells were used as targets for ADCC, sera from several nasopharyngeal carcinoma patients demonstrated significant ADCC reactivity, whereas sera from healthy EBV-seronegative and -seropositive persons lacked such reactivity. BARF1-specific ADCC activity could be competitively inhibited with recombinant BARF1 protein. The level of anti-BARF1 antibody activity in sera of patients with EBV-associated diseases suggests that the BARF1 protein may serve as a target on EBV-infected cells for ADCC.

Acute Disease↗
PubMed1996

Human herpesvirus-6 enhances natural killer cell cytotoxicity via IL-15.

The marked tropism of human herpesvirus-6 (HHV-6) for natural killer (NK) cells and T lymphocytes has led us to investigate the effect of HHV-6 on cellular cytotoxicity. We describe here how HHV-6 infection of peripheral blood mononuclear cells (PBMC) leads to upregulation of their NK cell cytotoxicity. The induction of NK cell activity by HHV-6 was abrogated by monoclonal antibodies (mAbs) to IL-15 but not by mAbs to other cytokines (IFN-alpha, IFN-gamma, TNF-alpha, TNF-beta, IL-2, IL-12) suggesting that IL-15 secreted in response to viral infection was responsible for the observed effect. Furthermore, NK activation by HHV-6 was blocked with mAb to CD122, as well as by human anti-HHV-6 neutralizing antibodies. Using RT-PCR, we were able to detect IL-15 mRNA upregulation in purified monocyte and NK cell preparations. IL-15 protein synthesis was increased in response to HHV-6. Finally, addition of IL-15 to PBMC cultures was found to severely curtail HHV-6 expression. Taken together, our data suggest that enhanced NK activity in response to viral infection represent a natural anti-viral defense mechanism aimed at rapidly eliminating virus-infected cells.

Base Sequence↗
PubMed1996

Antibody-dependent cellular cytotoxicity in HIV infections.

ADCC is an important immune effector mechanism against tumor and virus-infected cells that can be destroyed by the combined action of specific antibodies of IgG isotype against cell surface-associated antigens and effector cells, predominantly of the NK phenotype. ADCC has been shown to function in vivo in several systems. With regard to HIV, it can be readily demonstrated in vitro against the viral envelope proteins with serum and/or effector cells obtained from HIV-infected subjects. Several studies have demonstrated that the titers of the envy-specific ADCC-mediating antibodies decrease in the sera of HIV-infected individuals as the infection progresses toward AIDS. The cells that mediate ADCC also become functionally compromised in these individuals in early stages of the infection, thus depriving the host of the potential benefits of this process. Restoration of this process in the infected individuals by the administration of functionally competent effector cells (in vitro expanded and lymphokine-activated killer cells) and ADCC-mediating antibodies (hyperimmune serum or appropriate monoclonal antibodies), alone or in combination, may help slow the disease progress. Because of the multicomponent nature of the process, ADCC-mediating antibodies may prove a better correlate of protection and prognosis than the virus-specific neutralizing antibodies and cytotoxic T cells in assessing anti-HIV immunization and immunotherapy.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1996

Defective killing activity against gp120/41-expressing human erythroleukaemic K562 cell line by monocytes and natural killer cells from HIV-infected individuals.

OBJECTIVE: To determine the role of natural cellular cytotoxicity of peripheral blood mononuclear cells (PBMC) in killing of HIV-1 envelope protein-expressing, natural killer (NK)-sensitive human target cells, and to investigate this effector function in HIV-infected individuals. DESIGN AND METHODS: An HIV-1 env gene-containing expression vector was transfected into NK-sensitive K562 cells, and cell clones expressing gp120/41 were selected and used as targets in natural cytotoxicity assays using PBMC from both HIV-seropositive and seronegative individuals. A 16h 51Cr-release assay was used to determine the susceptibility of the gp120/41-expressing K562 as well as control vector-transfected cells. To identify the cell types involved in the killing of the transfected cells, PBMC depleted for a specific cell type as well as enriched or purified cell types were used as effector cells. RESULTS: Endogenous expression of gp120/41 by target cells increased their susceptibility to lysis by PBMC of HIV-seronegative individuals. The two cell types responsible for this enhanced killing, NK cells and monocytes, were found severely compromised in HIV-seropositive individuals in their ability to kill both env gene-transfected and control cells; killing by monocytes occurred via CD4. CONCLUSIONS: The present results illustrate for the first time that the transfected gp120/41 serves as target for both NK and monocyte-mediated killing and that cytocidal activity of these two effector cell types is defective in HIV-infected subjects. Strengthening this innate cytotoxic activity in these individuals may represent a valuable approach in controlling HIV infection.

CD4 Antigens↗
PubMed1996

Effect of adoptive transfer of CD4, CD8 and B cells on recovery from MHV3-induced immunodeficiencies.

A chronic viral infection can occur when the host fails to mount an effective immune response to clear the virus. Mouse hepatitis virus type 3 (MHV3) appears to be an excellent model for the study of the relationship between viral-induced immunodeficiency and chronic disease development. (C57BL/6 x A/J)F1 mice surviving acute hepatitis develop a chronic disease characterized by T- and B-cell immunodeficiencies, viral persistence in various organs including the brain, spleen and thymus, and death within 3 months postinfection (p.i.). We have reported that T- or B-cell deficiencies, observed in MHV3 chronically infected (C57BL/6 x A/J)F1 mice, can be partially or totally thwarted by adoptive transfer of CD4+, CD8+ and/or B cells, at 15 days p.i. in mice surviving the acute phase of the disease. Adoptive transfer of syngeneic CD4+ and/or CD8+ allowed a partial restoration of the T-cell deficiencies, as characterized by thymic atrophy, decrease in splenic T cells, and in all thymocyte subpopulations. B-cell immunodeficiency, as defined by a decrease in splenic B cells, as well as in the bone marrow pre-B- and B-cell compartments, and the occurrence of abnormally larger forms of bone marrow pre-B and B cells, were partially thwarted by B-cell treatment only. Splenic B cells and the bone marrow B-cell compartment, respectively, returned partially or totally to normal values, whereas the pre-B-cell compartment remained depleted in infected mice treated with B cells. Levels of all immunoglobulin classes returned to normal values in MHV3 chronically infected mice when treated with CD4+ in combination with CD8+ cells. All T- and/or B-cell treatments, however, were sufficient to thwart the process of the chronic disease, and favoured the survival of mice for up to 6 months p.i.

Animals↗
PubMed1996

Cyclic AMP-responsive element-dependent activation of Epstein-Barr virus zebra promoter by human herpesvirus 6.

We have recently shown that infection of Epstein-Barr virus (EBV) genome-positive B cells by human herpesvirus 6 (HHV-6) results in the expression of the immediate-early EBV Zebra gene, followed by virus replication (L. Flamand, I. Stefanescu, D. V. Ablashi, and J. Menezes, J. Virol. 67:6768-6777, 1993). Here we show that HHV-6 upregulates Zebra gene transcription through a cyclic AMP-responsive element (CRE) located within the Zebra promoter (Zp). Using human B- or T-cell lines transfected with ZpCat reporter gene constructs, we demonstrate that a region designated the ZII domain of Zp is the target of HHV-6 transactivation. Mutation of the consensus AP-1/CRE site within ZII abolished the inducibility of Zp by HHV-6, whereas positioning of the ZII domain upstream of the beta-globin minimal promoter conferred responsiveness following HHV-6 infection. Binding of these factors to ZII was prevented by oligonucleotides containing CRE but not by AP-1 consensus sequences. Antibodies against CRE-binding (CREB) protein but not against c-Fos or c-Jun were able to supershift the DNA-protein complex, identifying the nature of the transcription factor which binds to ZII as a member of the CREB family of proteins. Finally, transfection of CREB protein and protein kinase A expression vectors were found to activate Zp in Jurkat cells, suggesting that phosphorylated form of CREB protein can play a determining role in the EBV reactivation process.

B-Lymphocytes↗