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Biomedical subjects

F Dianzani

Publications and source records attributed to F Dianzani.

At least 55 records · Page 3Linked to original sources
PubMed1996

Antibodies to interferon (IFN) in hepatitis C patients relapsing while continuing recombinant IFN-alpha2 therapy.

A number of trials have demonstrated that IFN-alpha is effective in chronic hepatitis C virus infection. It is known, however, that a number of chronic hepatitis C patients experience, after an initial response to IFN, disease reactivation or relapse (also called 'breakthrough') while IFN therapy is still ongoing. Since in a number of clinical conditions a significant correlation between development of antibodies to IFN and failure of therapy has been established, we addressed the possibility that the development of antibodies to IFN may take part in the relapse occurring in hepatitis C patients during recombinant IFN-alpha (rIFN-alpha) therapy. The prevalence of neutralizing (NA) and binding antibodies (BA) to rIFN-alpha2 has been evaluated in 45 patients with chronic hepatitis C treated with rIFN-alpha2a who first normalized aminotransferase (ALT) levels, and subsequently showed disease reactivation while on treatment. The presence of NA and BA was tested before therapy, during the response to IFN treatment, and at the time when ALT started to rise again to abnormal levels. The results showed that no patients had detectable antibodies to IFN before therapy and during the period of response to the therapy, while most of them (88.9%) developed NA and/or BA to IFN-alpha2 concomitantly with disease reactivation. In particular, in 29 of the 45 patients (64.4%) ALT normalized on treatment and rose to abnormal levels when NA appeared in their serum, while in 11 of the 16 (68.8%) remaining patients the relapse was associated with BA development. The frequency of seroconversion in these patients is significantly higher than that observed in the control group. These data indicate that antibodies to IFN may be responsible for breakthrough in the majority of patients showing disease reactivation while rIFN-alpha therapy is still ongoing.

Adolescent↗
PubMed1995

Antibody to ICAM-1 mediates enhancement of HIV-1 infection of human endothelial cells.

Human umbilical vein endothelial cells (HUVEC) can be abortively infected with HIV-1, but virus production is rescued by the addition of T cells. Monoclonal antibody (Mab) to ICAM-1, but not its Fab' fragment or MAbs to LFA-1 and PECAM-1, increases HIV-1 infection of HUVEC by enhancing HIV-1 absorption. Enhancement by anti ICAM-1 is probably due to a bridging effect different from the ADE mediated by anti-gp120 that involves FcR or CR-mediated capture of the virus-antibody complex. Since antibodies to cell membrane molecules are present in HIV-1 infected patients, the ADE mediated by such a mechanism can be important in AIDS pathogenesis.

Antibodies, Monoclonal↗
PubMed1995

Host cell antigenic profile acquired by HIV-1 is a marker of its cellular origin.

HIV-1 acquires cell membrane proteins during budding. The cell membrane proteins (CMP) profile of laboratory HIV-1 strains grown in different host cells was established, by using an immobilized antibody capture (IAC), to verify whether CMPs present on HIV-1 correlate with its host cell origin. HIV-1 grown in different cell lines incorporates cell markers such as CD3, CD19, CD14, CD31 and IL 2-R, according to the distinctive expression of these antigens on the host cells. Furthermore, also T-tropic and monocytotropic HIV-1 strains display host cell specific markers, supporting the hypothesis that virus associated CMPs are a marker of host cell origin.

Antigens, CD↗
PubMed1995

HIV type 1 grown on interferon gamma-treated U937 cells shows selective increase in virion-associated intercellular adhesion molecule 1 and HLA-DR and enhanced infectivity for CD4-negative cells.

Cellular adhesion molecules, such as ICAM-1, -2, and -3; LFA-1; and HLA class I and II are incorporated into HIV-1 virions during budding from infected cells. These virion-associated molecules can be involved in the adsorption to susceptible cells displaying the corresponding counterligands. A number of cytokines have been shown to upregulate the cellular expression of adhesion molecules, such as ICAM-1 and HLA-DR. In this study we investigated the effects of IFN-gamma on the incorporation of ICAM-1, LFA-1, and HLA-DR into mature HIV-1 progeny from chronically infected cells. The ability of such virus progeny to infect either CD4-positive or -negative cells was also investigated. The results indicate that IFN-gamma stimulates the expression of ICAM-1 and of HLA-DR on HIV-1-infected cells, whereas LFA-1 expression is unaffected. The same modifications were also observed on virus progeny, because specific MAbs to ICAM-1 and HLA-DR captured infectious HIV-1 from IFN-treated cells with higher efficiency as compared to virus from control cells, whereas virus binding to anti LFA-1 MAb was unchanged. Moreover, the HIV-1 progeny released from IFN-treated cells showed an increased ability to bind to and to infect CD4-negative cells, whereas the infectivity was basically unchanged for CD4-positive cells. Our results suggest that cytokines, as well as other soluble factors, may expand the host cell range of HIV-1, possibly through modifications of the cell-derived surface molecules on the virions.(ABSTRACT TRUNCATED AT 250 WORDS)

CD4 Antigens↗
PubMed1995

Tyrosine phosphorylation pathway is involved in interferon-gamma (IFN-gamma) production; effect of sodium ortho vanadate.

The molecular mechanisms regulating IFN-gamma production have yet to be well characterized. We describe here how treatment of activated cultures of peripheral blood mononuclear cells (PBMC) with the phosphotyrosine phosphatases (PTP) inhibitor sodium ortho vanadate results in greatly enhanced IFN-gamma production. Conversely, cellular proliferation of the same cultures is profoundly inhibited by treatment with vanadate, while the expression of IL-2R and DR molecules on activated lymphocytes remains substantially unmodified. Increased IFN-gamma production, but not inhibition of cellular proliferation, was also observed in mitogen-activated vanadate-treated Jurkat cells. On the other hand, IFN-gamma production induced in cultures of PBMC treated or not with vanadate, was strongly inhibited by incubation with the protein tyrosine kinase (PTK) inhibitor herbimycin A. As a result of the inhibited phosphatase activity, substrates for PTK become hyperphosphorylated on tyrosine residues, as shown by Western blot analysis of cell lysates from cultures of PBMC treated with vanadate. We suggest that the tyrosine phosphorylation pathway plays a role in regulating IFN-gamma production.

Cell Division↗
PubMed1995

Treatment with natural IFN of hepatitis C patients with or without antibodies to recombinant IFN.

The purpose of this study was to evaluate if a retreatment with natural human interferon alpha could lead to a recovery of the therapeutic responsiveness in non-responder patients with chronic hepatitis C who did (9 cases) or did not (14 cases) develop anti-interferon neutralizing antibodies while on treatment with recombinant interferon alpha2a. During retreatment, no patient developed detectable levels of neutralizing antibodies to natural interferon. At the end of retreatment, 6/9 positive patients showed a complete response to natural interferon therapy, while only 1/14 negative patients had a partial response. These data suggest that a second course of treatment with the natural preparation may be useful in patients who failed to respond to an earlier course of recombinant interferon, particularly the anti-interferon positive patients who showed hepatitis reactivation after an initial response concomitantly with antibody appearance. Conversely, a second course of natural interferon therapy might be useless in cases in which the lack of response is not associated to antibody development.

Antibodies↗
PubMed1995

Unidirectional budding of HIV-1 at the site of cell-to-cell contact is associated with co-polarization of intercellular adhesion molecules and HIV-1 viral matrix protein.

OBJECTIVES: To explore the possibility that HIV-1 budding and cellular adhesion molecules co-polarize at cell-to-cell contact sites. To investigate the incorporation of host-cell-derived adhesion molecules into HIV-1. METHODS: The cellular sites involved in HIV-1 budding were examined by transmission electron microscopy. Single and double immunocytochemistry staining was used to evaluate the cellular distribution of the viral matrix protein and adhesion molecules. Quantitative flow cytometry was used to measure the cellular expression of adhesion molecules. An immunocapture technique was used to measure the presence of cell-derived proteins on HIV-1. The captured virus was measured by a p24 antigen assay. The infectivity of virus captured by monoclonal antibodies was tested by measuring the virus antigen yield in supernatants after the addition of sensitive cells. RESULTS: Released and budding HIV-1 was mainly localized at the cell-to-cell contact regions. This feature was consistent with a polarized staining for the virus matrix protein p18 at cell-to-cell contact regions. Intercellular adhesion molecules (ICAM)-1 in HIV-1-infected cells were polarized on both isolated cells and syncytia, co-localizing with HIV-1 matrix protein. HIV-1 incorporated all the adhesion molecules expressed by the host cells, although without quantitative correlation with their cellular expression. CONCLUSIONS: HIV-1 is released at cell-to-cell membrane contact sites. Both ICAM-1 and virus matrix protein co-polarized on isolated cells and syncytia at the sites involved in the recruitment of uninfected cells. The impressive concentration of ICAM at cell sites where most virions are released may account for the acquisition of these membrane proteins by the HIV-1 progeny, and may be important for the cell-mediated spread.

Antigens, CD↗
PubMed1995

Breakthrough during recombinant interferon alfa therapy in patients with chronic hepatitis C virus infection: prevalence, etiology, and management.

Recombinant interferon alfa (r-IFN alpha 2) has been shown to normalize the aminotransferase levels in approximately 50% of patients with chronic hepatitis C virus (HCV). Few patients experience a relapse during the treatment, in spite of a complete initial response (breakthrough). We studied 191 HCV Ab-positive patients with histologically proven chronic hepatitis. All of them were treated with r-IFN alpha 2 (3 MU three times a week). A complete response was seen in 54.4%. However, 12 of 104 responders experienced a breakthrough. At the time of breakthrough, neutralizing IFN antibodies were positive in 6 of 12 patients. Binding IFN antibodies were positive in all of these 12 patients. Continued treatment with r-IFN alpha 2, even at higher doses, did not restore the previous response in any patient. All of them were then switched to natural lymphoblastoid IFN, and this rapidly restored a complete response in all of the patients.

Adolescent↗
PubMed1994

Interferon induction by HIV glycoprotein 120: role of the V3 loop.

We have studied the mechanism of IFN induction by HIV-1 in peripheral blood mononuclear cells (PBMC), using recombinant viral membrane glycoproteins as potential inducers. Whereas 8 nM HIVIIIB-derived gp120 resulted in IFN levels between 80 and 2000 IU/ml with PBMC from different donors, gp120 from the MN strain was not an inducer. Preincubation of HIVIIIB-gp120 with a monoclonal antibody (mAB) to its CD4 binding domain or of PBMC with a mAB to the gp120 binding domain of CD4 abolished IFN induction. Antibodies against the third extracellular domain of CD4 which did not block binding of gp120, however, were also inhibitory. Furthermore, several mABs to the third variable loop (V3) of HIVIIIB-gp120 also blocked IFN induction, suggesting an important role of V3 in this process. This was further supported by the inhibitory action of peptides homologous to complete or partial sequences of V3. We conclude that after binding of gp120 to its CD4 receptor the V3 loop can be positioned close to the membrane of the responder cells by bending of gp120-occupied CD4 at its hinge region between extracellular domains 2 and 3. As a result V3 is able to interact with a V3-specific "secondary receptor" on the membranes of these cells. We suggest that it is the latter interaction which triggers IFN induction.

Amino Acid Sequence↗
PubMed1994

Determination of the size of HIV using adenovirus type 2 as an internal length marker.

The size of a virion is a key criterion to its proper classification and may have implications in many practical aspects. Size determinations by thin section electron microscopy often result in length aberrations of more than 10% because of a number of preparative and instrumental inaccuracies, e.g. specimen shrinkage or swelling and unreliable calibration. Using adenovirus type 2 as an isometric size marker for internal calibration, we have determined the diameters of mature and immature HIV-1 to be 110 to 128 and 132 to 146 nm, respectively. The marker had been used either as a purified particle suspension added to the HIV producing culture, or adenovirus had been propagated together with HIV by infecting HIV producing cells. Using well characterized isometric markers, e.g. an icosahedral virus, in thin section electron microscopy appears to be a suitable technique for viral size determinations.

Adenoviruses, Human↗
PubMed1994

The interferons: a biological system with therapeutic potential in viral infections.

Successful medical use of interferon for chronic viral infections is increasingly dependent on understanding the biologic and molecular mechanisms of the interferon system. Interferon (IFN) is one of the body's natural defenses. Production of IFN is a defensive response to foreign components of microbes, tumors and antigens. This IFN response begins with the production of the IFN proteins (alpha, beta and gamma) which then induce antiviral, antimicrobial, antitumor, and immunomodulatory actions. Thus, the initial production or administration of IFN(s) does not protect directly but instead reacts with specific receptors on cell surfaces to activate cytoplasmic transduction signals that then enter the nucleus to stimulate cellular genes encoding a number of effector proteins which lead to the defensive actions. The known molecular, humoral and cellular mechanisms by which these effector proteins exert their antiviral activities are presented. In addition, the pathogenesis of chronic infections is overviewed in the context of the interferon defenses.

Acute Disease↗
PubMed1994

Infectious virus with reduced cytopathogenicity resulting from persistent infection of normal lung fibroblasts by HIV type 1 strains.

We asked whether HIV-1 had the capacity to establish a persistent infection of cultured human diploid fibroblasts. Human strains of normal diploid embryo lung fibroblasts were infected with HIV-1 of the HTLV-IIIB and HIV-1P1 strains. Infection was followed over time, to analyze HIV expression. Virus production (intra- and extracellular virus) was evaluated as follows: ability to form syncytia in the C8166 T cell line, production of p24 and other viral antigens (ELISA and indirect immunofluorescence), search for a gag sequence in cell DNA by the polymerase chain reaction followed by hybridization to an HIV-1-specific probe (SK19). Cell-free culture supernatant was used as a virus source to infect de novo fibroblasts and C8166 T cells. Infection of cultured fibroblasts with either the HTLV-IIIB or HIV-1P1 strain led regularly to the establishment of persistently infected cultures. Fibroblast cells were capable of continuous virus production for at least 10 months. The released virus was capable of reinfecting cultured fibroblasts and of producing cytopathic effects in the C8166 T cell line. However, when compared to wild-type strains, the infectious virus derived from fibroblasts showed a prolonged replication cycle and a decreased ability to form syncytia in the T cell line. Therefore, HIV-1 can establish a persistent and productive infection in normal lung fibroblasts. The data are consistent with the hypothesis that in vivo, at least in the lung, fibroblasts may represent a virus reservoir and that infection of these cells may lead to the production of attenuated variants of HIV.

Cell Line↗
PubMed1994

Zidovudine induces the expression of cellular resistance affecting its antiviral activity.

We have previously shown that multidrug-resistant cells expressing the multidrug transporter P-glycoprotein are less sensitive to the antiviral activity of AZT. Subsequently, we addressed the question whether AZT itself is able to induce cellular resistance to the drug. Indeed, CEM cells propagated in the presence of increasing concentrations of AZT become resistant to the antigrowth and antiviral activity of AZT but do not express detectable level of P-glycoprotein. Sensitivity of these cells to other compounds, such as vinblastine, vincristine, ddI, and ddC remained unchanged, indicating that, in contrast to P-glycoprotein-positive cells, AZT-induced resistance is specific for AZT. Interestingly, in AZT-induced resistant cells the intracellular accumulation of AZT and exogenous deoxythymidine, as well as thymidine kinase activity, are significantly reduced when compared with the parental cell line. Our findings show that AZT itself may directly induce the expression of cellular mechanisms leading to the acquisition of specific cellular resistance that can affect its antiviral activity.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

Interferon expression in Crohn's disease patients: increased interferon-gamma and -alpha mRNA in the intestinal lamina propria mononuclear cells.

The in vivo interferon (IFN) activation in Crohn's disease was evaluated by measuring the relative amounts of IFN-alpha and -gamma mRNA in freshly isolated human lamina propria mononuclear cells (LPMC) from patients with Crohn's disease and controls. Both IFN-gamma and IFN-alpha mRNA, as estimated by dot blot analysis, were increased in Crohn's disease (LPMC), although the relative amounts of IFN mRNA appeared to differ among patients. Appreciable amounts of IFN-gamma mRNA were found in Crohn's disease peripheral blood mononuclear cells (PBMC) extracts, whereas the same cells were negative for IFN-alpha mRNA. Only minute amounts of IFN-gamma RNA were found sporadically in control LPMC while no IFN-alpha was detected. Control PBMC were shown to be virtually negative for both IFN-alpha and IFN-gamma mRNA. These data suggest that IFN induction in the normal human gut is a well-controlled function and that in Crohn's disease tissues, both IFN-gamma and IFN-alpha production are dysregulated. The increased IFN activity may represent a major feature in the induction and perpetuation of the chronic inflammatory process in Crohn's disease.

Crohn Disease↗
PubMed1994

A simple and reliable method to detect cell membrane proteins on infectious human immunodeficiency virus type 1 particles.

Identification of cell-derived molecules on infectious human immunodeficiency virus type 1 (HIV-1) particles may be helpful in investigating mechanisms of HIV infection and in vaccine studies. Some of these molecules were detected on HIV-1 virions in previous studies, but rather elaborate methods were used. The method presented here allows an extensive characterization of the cell surface molecules associated with HIV-1 by capturing virus particles on monoclonal antibodies to cell membrane antigens bound to plastic wells. Binding of infectious virus was assessed by adding permissive target cells (C8166) and determining viral replication. With this procedure, beta 2-microglobulin, HLA-DR, intercellular adhesion molecule-1, and leukocyte function antigen-1 were found on HIV-1 particles from laboratory strains and primary clinical isolates. In contrast, CD19, CD4, and CD8 molecules were not detected.

Antigens, Surface↗