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Biomedical subjects

B Bizzini

Publications and source records attributed to B Bizzini.

At least 19 recordsLinked to original sources
PubMed1999

Active anti-interferon-alpha immunization: a European-Israeli, randomized, double-blind, placebo-controlled clinical trial in 242 HIV-1--infected patients (the EURIS study).

This randomized, double-blind, placebo-controlled, phase II/III study was designed to evaluate safety, immunogenicity, and efficacy of an active anti-interferon-alpha (anti-IFN-alpha) vaccine in asymptomatic HIV-1-infected patients. The active immunization was aimed at inducing anti-IFN-alpha antibodies to counteract IFN-alpha overproduction. In all, 242 patients, recruited between December 1995 and July 1996 in eight centers in Europe and Israel, with CD4+ counts from 100 to 634 cells/mm3 who were receiving or not receiving antiretroviral therapy (including protease inhibitors) were randomized to receive either anti-IFN-alpha vaccine or placebo. The anti-IFN-alpha immunization regimen consisted of three priming injections delivered intramuscularly at 1-month intervals in a water-in-oil emulsion of inactivated recombinant IFN-alpha-2b (i-IFN-alpha) followed by intramuscular booster injections of i-IFN-alpha adsorbed onto calcium phosphate every 3 months. Immunogenicity to vaccine was defined as an increase of anti-IFN-alpha antibody level of more than twofold the preimmunization value. Clinical progression, changes in antiretroviral treatment, and decrease of CD4+ counts to <200 cells/mm3 were considered endpoints for efficacy evaluation. Contrary to our previous experience, in which six to seven oil priming injections induced a >90% response rate, the three oil-adjuvanted injections in this trial were suboptimal because only 40 of 122 vaccinees (33%) had raised anti-IFN-alpha antibody following immunization. In vaccinees, both antibody responders (AbRV) and nonresponders (AbNRV), the tolerance to the vaccine was good and was without evidence of significant safety concerns. During the course of the trial, 62% of vaccine responders, 64% of nonresponders, and 63% of placebo patients elected to add protease inhibitor-containing regimens as new treatment guidelines were established, resulting in a marked decrease in clinical and laboratory progression such that the expected endpoints of the study could not be achieved and further follow-up was halted. Despite the unexpectedly low immunogenicity and fewer than expected endpoints, anti-IFN-alpha vaccine recipients, in comparison with placebo recipients, showed a lower rate of disease progression, nonelective treatment changes, and/or CD4+ count decrease to <200 cells/mm3, but the difference was not statistically significant. Nevertheless, the subgroup of patients immunized to IFN-alpha who experienced a rise in anti-IFN-alpha antibodies had a significantly lower rate of occurrence of HIV-1-related events and of any combination of the endpoints compared with those of either placebo patients or vaccinees who failed to develop anti-IFN-alpha antibodies, the latter two groups behaving similarly. Further studies of this approach are warranted because these data suggest a beneficial effect of this adjuvant approach.

AIDS Vaccines↗
PubMed1999

Tat toxoid as a component of a preventive vaccine in seronegative subjects.

Because administration of Tat protein, the HIV-1 toxin that induces immunosuppression and apoptosis, may be deleterious to the host immune system, a chemically inactivated but nonetheless immunogenic Tat preparation, Tat toxoid, was used to immunize seronegative individuals against Tat. In an open, controlled, phase I clinical trial, Tat toxoid turned out to be safe, well tolerated, and able to trigger a specific immune reaction. In particular, a threefold to more than 10-fold increase of circulating antibodies directed against the native Tat was observed after immunization in all of 5 immunized study subjects, together with a positive reaction to delayed-type hypersensitivity (DTH) skin test with Tat toxoid in vivo and increased lymphoproliferative response to native Tat in vitro. Persistent (> or =1 year) high levels of circulating anti-Tat antibodies could prevent the Tat-induced immune suppression and, following HIV-1 exposure, allow the anti-HIV-1 cellular immune response, with its early release of protective beta-chemokines, to occur leading to an increase of host resistance, that is, protection.

AIDS Vaccines↗
PubMed1999

Amplification of the inflammatory cellular redox state by human immunodeficiency virus type 1-immunosuppressive tat and gp160 proteins.

In the course of our studies on oxidative stress as a component of pathological processes in humans, we showed that microintrusion into cells with microcapillary and ultramicroelectrochemical detection could mimic many types of mechanical intrusion leading to an instant (0.1 s) and high (some femtomoles) burst release of H2O2. Specific inhibitors of NADPH enzymes seem to support the assumption that this enzyme is one of the main targets of our experiments. Also, human immunodeficiency virus type 1 (HIV-1) gp160 inhibits the cooperative response of uninfected T cells as well as Tat protein release by infected cells does. In this study, we analyzed in real time, lymphocyte per lymphocyte, the T-cell response following activation in relation to the redox state. We showed that the immunosuppressive effects of HIV-1 Tat and gp160 proteins and oxidative stress are correlated, since the native but not the inactivated Tat and gp160 proteins inhibit the cellular immune response and enhance oxidative stress. These results are consistent with a role of the membrane NADPH oxidase in the cellular response to immune activation.

Arsenicals↗
PubMed1998

Interferon alpha and Tat involvement in the immunosuppression of uninfected T cells and C-C chemokine decline in AIDS.

HIV type 1 (HIV-1) not only directly kills infected CD4(+) T cells but also induces immunosuppression of uninfected T cells. Two immunosuppressive proteins, interferon alpha (IFNalpha) and extracellular Tat, mediate this process because specific antibodies against these proteins prevent generation of suppressor cells in HIV-1-infected peripheral blood mononuclear cell cultures. Furthermore, the production of C-C chemokines in response to immune cell activation, initially enhanced by IFNalpha and Tat, ultimately is inhibited by these proteins in parallel with their induction of immunosuppression. The clinical corollary is the immunosuppression of uninfected T cells and the decline in C-C chemokine release found at advanced stages of HIV-1 infection paralleling rising levels of IFNalpha and extracellular Tat. We, therefore, suggest that IFNalpha and Tat may be critical targets for anti-AIDS strategies.

Acquired Immunodeficiency Syndrome↗
PubMed1998

C-C chemokines, pivotal in protection against HIV type 1 infection.

Exposure to HIV type 1 (HIV-1) does not usually lead to infection. Although this could be because of insufficient virus titer, there is now abundant evidence that some individuals resist infection even when directly exposed to a high titer of HIV. This protection recently has been correlated with homozygous mutations of an HIV-1 coreceptor, namely CCR5, the receptor for the beta-chemokines. Moreover, earlier results already had shown that the same chemokines markedly suppress the nonsyncitial inducing variants of HIV-1, the chief virus type transmitted from person to person. CCR5 mutation, as a unique mechanism of protection, is, however, suspect because HIV-1 variants can use other chemokine receptors as their coreceptor. Moreover, recent results have established that infection can indeed sometimes occur with such mutations. Here, we report on transient natural resistance over time of most of 128 hemophiliacs who were inoculated repeatedly with HIV-1-contaminated Factor VIII concentrate from plasma during 1980-1985 before the development of the HIV blood test. Furthermore, and remarkably, 14 subjects remain uninfected to this date, and in these subjects we found homozygous CCR5 mutations in none but in most of them overproduction of beta chemokines. In vitro experiments confirmed the potent anti-HIV suppressive effect of these chemokines.

Cells, Cultured↗
PubMed1998

A prophylactic and therapeutic AIDS vaccine containing as a component the innocuous Tat toxoid.

Extracellular Tat can act as a viral toxin on uninfected cells of different tissues, including the CNS and the immune system, thus in order to immunize humans against Tat we have prepared a biologically inactivated but immunogenic Tat (Tat Toxoid). Tat Toxoid is not toxic in mice even at high doses. It triggers high levels of specific Tat Abs in the mouse and rabbit. Furthermore, in humans Tat Toxoid immunization was safe and induced in seronegatives persistent high levels of Tat Abs and in immunodeficient patients a significant rise of these specific Abs. Facing acute HIV-1 infection, the presence of high level of circulating Tat Abs promoted by Tat Toxoid vaccine should prevent Tat-induced immunosuppression and allow anti-HIV-1 cellular response to develop. As a consequence, early release of beta-chemokines could enhance host resistance towards HIV-1, and, in infected people, inhibit viral replication and evolution towards AIDS.

AIDS Vaccines↗
PubMed1998

Binding of HIV-1 to RBCs involves the Duffy antigen receptors for chemokines (DARC).

The Duffy Antigen Receptor for Chemokines (DARC) belongs to a family of erythrocyte chemokine receptors that bind C-X-C and C-C chemokines such as interleukin 8 (IL-8), monocyte chemoattractant protein 1 (MCP-1) and regulated-on-activation, normal T cell-expressed and -secreted (RANTES), but not macrophage inflammatory protein 1 alpha (MIP-1 alpha) or MIP-1 beta. DARC has also been identified to a receptor for malaria parasites Plasmodium vivax and Plasmodium knowlesi. In the present study, we show that HIV-1 binds to RBCs from Caucasian individuals via DARC making RBCs able to transmit HIV to peripheral blood mononuclear cells (PBMCs). Furthermore, binding of HIV-1 particles to RBCs is inhibited by treating these cells with recombinant RANTES, but not with recombinant MIP-1 alpha prior to their incubation with HIV-1. This finding suggests that RBCs may function as a reservoir for HIV-1 or as a receptor for the entry of HIV-1 into CD4-cell subsets as well as neurons or endothelial cells.

Antigens, Protozoan↗
PubMed1997

Potentialization of IL-2 effects on immune cells by oyster extract (JCOE) in normal and HIV-infected individuals.

Peripheral blood mononuclear cells (PBMCs) are physiologically activated by interleukin (IL)-2. We found that oyster extract (JCOE) currently used as a functional nutrient enhanced in vitro the IL-2 dependent activation as measured by cell count. 3H-thymidine uptake and up-regulation of a IL-2 receptor. In human immunodeficiency virus (HIV) seropositive individuals, this oyster extract-induced effect was marked in asymptomatic individuals with quasi-normal CD4 cell counts, but was weakly reflected in acquired immunodeficiency syndrome (AIDS) patients.

Animals↗
PubMed1996

Repair of the in vitro HIV-1-induced immunosuppression and blockade of the generation of functional suppressive CD8 cells by anti-alpha interferon and anti-Tat antibodies.

The acute human immunodeficiency virus type 1 (HIV-1) infection of activated peripheral blood mononuclear cells (PBMCs) from normal donors results in inhibition of cell proliferation and generation of functional suppressive T cells. Cultured HIV-1 infected PBMCs but not uninfected PBMCs, following irradiation, can inhibit the proliferation of antigen-activated autologous T cells in a dose-dependent way. CD8+ cell subpopulation is responsible for this inhibition. The presence of anti-alpha interferon (IFN alpha) and anti-Tat antibodies in the culture medium counteracts the HIV-1-induced immunosuppression and prevents the generation of suppressive T cells by these PBMCs. The reported data should have major implications for strategies of AIDS treatment which, in association with antiviral drugs, aim at targetting immune disorders.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Absence of clinical, virological, and immunological signs of progression in HIV-1-infected patients receiving active anti-interferon-alpha immunization: a 30-month follow-up report.

Twenty-seven HIV-1-infected patients, 16 at early stage of disease and without concomitant antiretroviral therapy and 11 at more advanced stage of disease receiving antiretroviral therapy, have been followed since their enrollment, November 1992 and July 1993, respectively, in phase I/II studies to evaluate safety and immunogenicity of an anti-interferon-alpha (IFN-alpha) vaccine, aimed at modulating the impaired cytokine network in AIDS patients by counteracting IFN-alpha overproduction. We compared clinical, virological, and immunological markers of disease progression, including circulating IFN-alpha levels in a 24- to 30-month follow-up period with those of 62 patients fulfilling the same enrollment criteria and comparable for sex, risk factor, and age, regularly followed at our center. Anti-IFN-alpha immunization consisted of four-six intramuscular injections 1 month apart of a water-in-oil emulsion of 500 micrograms formalin-inactivated recombinant IFN-alpha-2b (iIFN-alpha) followed by intramuscular injections of 250 micrograms iIFN-alpha adsorbed onto calcium phosphate every 3 months. Neither clinical deterioration nor a CD4+ cell count decrease from pretreatment values was observed in IFN-alpha-immunized patients in the follow-up period, whereas clinical and immunological disease progressions were observed among open-comparison patients. Furthermore, statistical analysis showed a strong association between occurrence of clinical manifestations and high circulating IFN-alpha titers, while nonprogression of IFN-alpha-immunized patients was associated with decreased levels of circulating IFN-alpha.

Adolescent↗
PubMed1995

Tetanus toxin inhibits spontaneous quantal release and cleaves VAMP/synaptobrevin.

Tetanus toxin decreased the frequency of spontaneous events at the electric organ of Torpedo marmorata. This reduction was up to 70% in poisoned electric organ. According to distribution analysis of miniature end plate currents, only a subpopulation of events which have small amplitudes were recorded after poisoning. Furthermore, isolated cholinergic nerve terminals showed a decrease in VAMP/synaptobrevin when poisoned with tetanus toxin under similar conditions. The relationship between the two effects of the toxin, i.e. inhibition of vesicle exocytosis and peptidase activity on synaptobrevin, is discussed.

Acetylcholine↗
PubMed1995

Biological effect of active anti-IFN alpha immunization in HIV-infected patients.

Circulating interferon (IFN) was investigated in HIV-1 seropositive patients by measuring the IFN alpha antiviral effect in the serum. While serum of healthy seronegative individuals exhibits an antiviral effect, not due to IFNs, considered as background, serum of seropositive patients showed an additional antiviral effect due to the abnormal presence of IFN alpha. Increased titers of IFN alpha were found in the course of the HIV infection and seemed to correlate with the evolution of AIDS disease. Furthermore, patients immunized against IFN alpha had both stabilized CD4 cell count and decreased IFN alpha in their serum. HIV-1-infected patients also exhibited higher titers of natural anti-IFN antibodies than seronegative controls and the level of specific antibodies (Abs) markedly increased in immunized patients. Finally, serum from immunized patients, when compared to seronegative controls, exhibits an interferon neutralizing capacity.

Acquired Immunodeficiency Syndrome↗
PubMed1995

"Kinoids": the basis for anticytokine immunization and their use in HIV infection.

HIV infection is characterized, at least in part, by the dysregulation of the cytokine network. Both IFN gamma and IFN alpha are occasionally overproduced. These cytokines could participate in the HIV-induced immunosuppression. To enable a HIV-infected organism to promote an immune reaction against the virus, the immune competence should tentatively be restored by counteracting the overproduction of IFN alpha because of its well known antiproliferative properties. For this purpose, IFN alpha was chemically converted into a biologically inactive, but still immunogenic product, which we termed "kinoid", reminiscent of that of bacterial toxins which have been transformed into toxoids for vaccination. The "kinoid" derived from IFN alpha showed to be well tolerated and immunogenic, since its administration to experimental animals and humans should result in no untoward reactions, while eliciting the production of anti-IFN alpha antibodies. Active "kinoid" immunization should permit to counteract the overproduction of the corresponding cytokine when involved in pathogenesis. Another alternative, although less attractive than active anti-kinoid vaccination, is passive immunization by administering anti-kinoid antibodies. Biological antagonists of cytokine, as well as gene therapy should also be taken into consideration.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Anti-alpha interferon immunization: safety and immunogenicity in asymptomatic HIV positive patients at high risk of disease progression.

A randomized, placebo-controlled trial was designed to evaluate safety and immunogenicity of an anti-cytokine vaccine in high risk HIV-positive patients. This strategy was aimed to modulate the impaired cytokine regulation in AIDS. Twelve asymptomatic patients on antiretroviral therapy for at least 1 year and with CD4 cell counts between 100-300/mm3 were randomized to receive adjuvanted formol-inactivated interferon alpha-2a (IFN alpha) and continue the current antiretroviral treatment, whatever it was, or to receive the adjuvant alone and the current antiretroviral treatment. All patients received 4 i.m. injections monthly, followed by booster injections every 3 months. Clinical status, immunology and virology were monitored. Immune response to vaccination was evaluated in term of antibody detection (ELISA) and serum anti-IFN alpha neutralizing capacity. Only local discomfort and transient fever were reported. All vaccines except one showed increased levels of anti-IFN alpha Abs and developed serum IFN alpha neutralizing capacity. Viral load did not increase in vaccinees while it remained unchanged or even increased in placebo-treated patients. None of them showed HIV-related symptoms and all had their CD4 cell counts stabilized over 18 months, whereas 2 placebo-treated patients developed full-blow AIDS. In conclusion, anti-IFN alpha vaccine was safe and immunogenic. Stable clinical and immunological status over 18 months was observed in vaccinees coupled to increased serum IFN alpha neutralizing capacity.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Production in rabbits of high levels of anti-HIV-1 gp160 antibodies.

The production of anti-HIV-1 gp160 antibodies was obtained in rabbits given gp160 either in saline or adsorbed onto calcium phosphate. Immunization with gp160 in saline induced the formation of antibodies directed to the p18 protein, whereas the gp160 adsorbed onto calcium phosphate elicited antibodies recognizing the gp160, p55, p25 and p18 proteins. Calcium phosphate was found to be a powerful adjuvant and it should be used for potentiating candidate anti-HIV vaccines.

Adjuvants, Immunologic↗
PubMed1995

HIV-1 soluble antigens induced CD8+ cytotoxic T-cell responses in an immunized individual.

In an attempt to determine whether immunization of healthy HIV-1 seronegative individuals with a soluble gp160 candidate vaccine could induce an anti-HIV specific immune response, volunteers were immunized by two injections of a water-in-oil emulsion containing a mixture of gp160 antigen together with selected peptides. Following immunization, lymphocytes were collected and stimulated in vitro with autologous HIV-1-infected cells. The results showed that immunization with soluble HIV-1 envelope was able to generate CD3+ CD8+ CTLs directed to gp160 antigen. The CTL response was restricted to class I molecule HLA-A2. The CTL response was comparable to that elicited by immunization with HIV-1-envelope recombinant vaccinia virus.

AIDS Vaccines↗