Biomedical subjects

N Oyaizu

Publications and source records attributed to N Oyaizu.

At least 37 records · Page 2Linked to original sources

PubMed1997

Cytokine pattern in relation to disease progression in human immunodeficiency virus-infected children.

Cytokine mRNA expression and stimulus-induced cytokines were examined in peripheral blood mononuclear cells in 62 human immunodeficiency virus (HIV)-infected children and uninfected controls. Compared with that in controls, constitutive mRNA expression in patients was increased for tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, and interleukin (IL)-10 and decreased for IL-12; it was undetectable for IL-2 and IL-4 in both patients and controls. Stimulus-induced secretion of TNF-alpha, IFN-gamma, IL-12, and IL-4 was less than that in controls; IL-10 secretion was similar. There was no increase in stimulus-induced or constitutive IL-4 or IL-10 in children with severe immunologic deficit compared with controls. A higher stimulus-induced IL-10 secretion and a lower constitutive TNF-alpha mRNA were associated with a slower rate of disease progression, and TNF-alpha mRNA expression correlated with lower plasma HIV RNA. Thus, constitutive cytokine mRNA expression differs from stimulus-induced cytokine responses. The dominant defect in HIV-infected children appears to be one of reduced type 1 cytokines, predominantly IL-2.

Acquired Immunodeficiency Syndrome↗

PubMed1997

Upregulation of human immunodeficiency virus (HIV) replication by CD4 cross-linking in peripheral blood mononuclear cells of HIV-infected adults.

This study was conducted with peripheral blood mononuclear cells from 67 human immunodeficiency virus (HIV)-infected adults. It supports the hypothesis that cross-linking of CD4 molecules by HIV gp120 can result in HIV upregulation and spread of infection. Underlying mechanisms include activation of latent infection by factors in addition to, or other than, tumor necrosis factor alpha.

Adult↗

PubMed1996

IL-2 rescues in vitro lymphocyte apoptosis in patients with HIV infection: correlation with its ability to block culture-induced down-modulation of Bcl-2.

IL-2 administration in vivo has been shown to increase CD4+ T cell counts in HIV+ patients. We have previously reported that PBMC from HIV-infected patients undergo marked spontaneous apoptosis in vitro. In this study, we examined the effect of IL-2 added in vitro upon culture-induced apoptosis in PBMC from 80 HIV-infected patients by flow cytometry. IL-2 at concentrations of > or = 10 U/ml significantly reduced spontaneous apoptosis in CD3+ T lymphocytes in patients but not in healthy volunteers. Interestingly, we observed that Bcl-2 expression in patient lymphocytes decreased rapidly upon in vitro culture while that in cells of healthy volunteers was relatively unaffected. The most significant decrease in Bcl-2 expression was noted in the apoptotic cell population. The IL-2-mediated reduction in lymphocyte apoptosis was found to be associated with the blocking of this culture-induced down-modulation of Bcl-2 expression. IL-2 did not induce significant expansion of lymphocytes during the culture period nor did it affect Fas Ag expression in patient cells, which were already expressing Fas maximally. These findings strongly suggest that IL-2 mediates its apoptosis-blocking effects via suppressing down-modulation of Bcl-2. Our findings also provide an experimental basis for the ongoing therapies utilizing this cytokine for slowing HIV disease progression.

Adult↗

PubMed1996

Virus load as a marker of disease progression in HIV-infected children.

The relationship of virus load to clinical disease progression in HIV-infected children remains to be elucidated. In this study, HIV-1 proviral DNA load was determined in peripheral blood mononuclear cells (PBMCs) by the quantitative competitive DNA polymerase chain reaction assay (QC-PCR) in 47 HIV-infected children subdivided by age (group I, < or = 2 years; group II, > or = 5 years), who were further categorized to include 12 rapid progressors (RP, age < or = 2 years, Centers for Disease Control [CDC] defined clinical category C and/or immune category 3, or death before age 2 years) and slow progressors (SP, age > or = 5 years, excluding CDC categories C and/or immune category 3). Significantly higher mean proviral copies/10(3) PBMCs were detected in group I versus group II (75.4 +/- 104.3 and 13.0 +/- 17.8 respectively, p < 0.0001) and in RP (158.0 +/- 118.2) as compared to either SP (11.8 +/- 18.8, p < 0.0001) or other age-matched infected children (20.3 +/- 38.8, p < 0.0001). Thus HIV-infected children appear to have a higher cell-associated virus load early in life, especially in association with rapid disease progression.

Adolescent↗

PubMed1996

Inhibition of CD4 cross-linking-induced lymphocytes apoptosis by vesnarinone as a novel immunomodulating agent: vesnarinone inhibits Fas expression and apoptosis by blocking cytokine secretion.

Evidence is accumulating that T cells from human immunodeficiency virus type 1 (HIV-1)-infected individuals show accelerated cell death through apoptosis. We have recently demonstrated that the cross-linking of CD4 molecules (CD4XL) results in death of normal peripheral T cells through apoptosis and imbalanced cytokine secretion (ie, induction of tumor necrosis factor-alpha [TNF-alpha] and interferon-gamma [IFN-gamma] in the absence of interleukin-2 [IL-2] or IL-4 secretion). These upregulated cytokines (TNF-alpha/IFN-gamma) largely contributed to upregulation of the apoptosis-inducing cell surface molecule, Fas (APO-1/CD95) and apoptosis induction. The present study investigated the effect of vesnarinone as a novel immunomodulating agent on CD4XL-induced T-cell apoptosis. The addition of vesnarinone to peripheral blood mononuclear cells (PBMC) significantly inhibited CD4XL-induced lymphocyte apoptosis. This apoptosis-inhibitory effect of vesnarinone was associated with the blocking of CD4XL-induced TNF-alpha IFN-gamma secretion and of Fas antigen upregulation. However, vesnarinone did not block effects of exogenously supplemented TNF-alpha/IFN-gamma on Fas induction. These data suggest that vesnarinone inhibits CD4XL-induced TNF-alpha/IFN-gamma secretion, thereby blocking subsequent Fas upregulation and apoptosis induction. Given the potent pathogenic role of imbalanced cytokine secretion observed in HIV-infection, an agent such as vesnarinone may be of therapeutic value in slowing disease progression.

Adjuvants, Immunologic↗

PubMed1996

HIV-1 gp160 induces transforming growth factor-beta production in human PBMC.

Transforming growth factor-beta (TGF-beta) is a multifunctional cytokine secreted by many mononuclear cells in peripheral blood (PBMC) and has diverse effects on cellular and humoral immunity. Increased TGF-beta mRNA expression has been reported in PBMC of HIV-infected patients, but the mechanism by which HIV induces TGF-beta secretion is unknown. In this study, we observed that HIV gp160 could induce significant TGF-beta secretion and TGF-beta mRNA expression in PBMC from HIV-seronegative healthy donors. The cellular source of TGF-beta was attributed to non-T cells, presumably monocytes. Specificity of secreted TGF-beta was confirmed by the addition of anti-TGF-beta mAb which abrogated the proliferative response of CCL-64 cells by gp160-treated culture supernatants. Soluble CD4 blocked the gp160-induced TGF-beta production, suggesting that CD4-gp160 interaction is required to induce TGF-beta production. Our results suggest that HIV-1 gp160 may contribute to the immune defects in HIV infection by inducing TGF-beta secretion.

Antibodies↗

PubMed1996

HIV-1 gp 120 blocks jacalin-induced proliferative response in CD4+ T cells: jacalin as a useful surrogate marker for qualitative and quantitative deficiency of CD4+ T cells in HIV-1 infection.

Jacalin is a plant lectin that induces mitogenic responses selectively in CD4+ T lymphocytes and has been shown to block infection by the human immunodeficiency virus type 1 (HIV-1) in a T lymphoid cell line, but the relationship of jacalin to the HIV envelope glycoprotein gp 120 in its interaction with the CD4 molecule is unclear. Here we demonstrate that pretreatment of normal T cells with native HIV-1 gp 120 impairs their ability to proliferate and secrete IL-2 in response to jacalin. This effect was not observed with deglycosylated gp 120, which fails to bind to CD4 molecule, or with gp 120 that has been premixed with soluble CD4. Flow cytometric studies and Western blotting analysis indicated that gp 120 and jacalin compete with each other in binding to CD4 molecules. In HIV-infected patients, proliferative responses of PBMC in response to jacalin were found to correlate quantitatively with percentages of CD4+ T cells but also showed a qualitative defect in comparison to healthy volunteers based on responses that were correlated for CD4+ T cell numbers. These findings suggest that (i) gp 120 and jacalin compete with each other for CD4 binding and (ii) jacalin might be a useful surrogate marker for quantitative as well as qualitative deficiency of CD4+ T cells in HIV-1 infection.

Antiviral Agents↗

PubMed1995

Requirement of p56lck in T-cell receptor/CD3-mediated apoptosis and Fas-ligand induction in Jurkat cells.

Interactions of Fas (CD95) and its ligand (Fas-L) has been shown to play a pivotal role in T cells receptor (TCR)/CD3 activation-induced cell death via apoptosis. Although several lines of evidence suggest involvement of protein tyrosine kinase (PTK) activity in this process, the role of src family PTK p561ck (lck) is not known. We report here that, contrary to wild type Jurkat, the lck-deficient mutant JCaM is resistant to anti-CD3-induced apoptosis and fails to express Fas-L mRNA upon anti-CD3 treatment. However, both Jurkat and JCaM were found to constitutively express Fas and were equally sensitive to anti-Fas-mediated apoptosis. If stimulated with PMA plus ionomycin, JCaM expressed Fas-L mRNA and underwent apoptosis. These findings indicate that p56lck is required for TCR/CD3-mediated Fas-L induction but not for the transduction of Fas receptor-mediated death signal.

Antigens, Surface↗

PubMed1995

Expression of the Fas antigen in patients infected with human immunodeficiency virus.

Lymphocytes from patients with HIV infection have been shown to undergo accelerated apoptosis. Fas antigen is a cell surface protein known to initiate an apoptotic signal. Therefore, we undertook a study to examine the expression of the Fas antigen during HIV infection. Using three color flow cytometry, expression of the Fas antigen on lymphocytes of 23 HIV infected individuals (CDC category 2, CD4 200-499 cells/microL, n = 10; CDC category 3, CD4 < 200 cells/microL, n = 13) and 10 healthy controls was examined. Both CD3+CD4+ and CD3+CD8+ subsets were examined for their expression of this marker. In lymphocytes of healthy controls, 47% of the CD3+CD4+ and 45% of the CD3+CD8+ cells were Fas antigen positive. This percentage was significantly increased in CD4 cells from HIV infected patients belonging to CDC category 3, but was unchanged from normal values in CDC category 2 subjects. The increase in the percentage of CD4+ T cells expressing Fas antigen in patients correlated significantly with the decrease in circulating CD4 T cell count (P < 0.009). In addition, by examining mean fluorescence intensity, we found that the amount of Fas expression per cell was increased threefold in CD3+CD4+ cells and increased twofold in CD3+CD8+ cells in category 3 patients. These results demonstrate that an increase in Fas antigen expression occurs during HIV infection.

Adult↗

PubMed1995

Mechanism of apoptosis in peripheral blood mononuclear cells of HIV-infected patients.

Lymphocytes from patients with HIV-infection have been shown to undergo accelerated spontaneous apoptosis. Binding of CD4 molecules by HIV envelope protein gp120 and anti-gp120 antibodies can lead to crosslinking of CD4 molecules (CD4XL) in vitro and conceivably in vivo. We have recently shown that CD4XL in vitro, when performed in unfractioned peripheral blood mononuclear cells (PBMC) on normal HIV seronegative donors, is by itself sufficient to induce T cell apoptosis (Blood 82:3392, 1993). To further examine the mechanisms involved in apoptosis, we have examined the expression of Fas antigen (Fas) using 3 color flow cytometry. Fas is a cell surface molecule known to mediate apoptosis-triggering signals. We induced CD4XL in PBMC obtained from normal donors, either by anti-CD4 mAb Leu3a or by HIV-1 envelope protein gp160. PBMC subpopulations were examined for Fas Ag expression and for apoptosis induction by flow cytometry. CD4XL was found to result in increased Fas expression as well as Fas mRNA in lymphocytes and the up-regulated Fas Ag was closely correlated with apoptotic cell death. CD4XL in PBMC also resulted in induction of the cytokines INF-tau and TNF-alpha in the absence of IL-2 and IL-4 secretion. Both these cytokins contributed to Fas Ag up-regulation and antibodies to TNF-alpha and INF-tau abrogated CD4XL-induced Fas up-regulation and T-cell apoptosis. These findings suggest that CD4XL occurring in vivo might play an important role in inducing an abberant cytokine profile (which has been observed in HIV infected individuals) and also in triggering of T-cell apoptosis.

Apoptosis↗

PubMed1995

Role of apoptosis in HIV disease pathogenesis.

After approximately one and a half decades of intensive studies, the exact mechanisms to explain HIV-mediated cytopathicity are still enigmatic and need closer scrutiny. There has been a dichotomy between virological and immunological viewpoints in understanding HIV-mediated cytopathicity, the former emphasizing a killing of infected cells by HIV-1 and the latter emphasizing indirect mechanisms wherein HIV or its soluble component(s) alter CD4 T-cell function and induce susceptibility to apoptosis. Accumulating evidence points to the notion that apoptosis might be a major contributor to the depletion of CD4 T-cells in HIV infection. This review summarizes current information about the regulatory mechanisms of T-cell apoptosis and the role of apoptosis in HIV pathogenesis with the goal of providing an integrated view of HIV cytopathicity.

Animals↗

PubMed1995

Correlation of maternal cytophilic human immunodeficiency virus (HIV)-1 V3 loop peptide-specific antibodies in infants with vertical HIV transmission.

Approximately 70% of human immunodeficiency virus (HIV)-1-infected pregnant women do not transmit HIV to their offsprings. The identification of factors involved in maternal-child transmission of HIV is important for the design and implementation of therapeutic and prevention strategies. Recently we have developed a modified peripheral mononuclear cell (PBMC) culture system for in vitro antibody production (IVAP) by which we can distinguish serum-derived cytophilic anti-HIV-1 antibody from de novo synthesized antibody. In this study, we analyzed the presence of antibodies directed to HIV-1 gp160, gp120, gp41, and V3 loop synthetic peptides (C51, C53, and C57 from MN and IIIB strains) utilizing the grid-blot method in PBMC cultures of 52 mother-child pairs. Among the mothers (39 nontransmitters and 13 transmitters), presence of serum-derived cytophilic antibodies or de novo synthesized HIV V3 loop peptide-specific antibodies did not correlate with vertical transmission. However, PBMC-associated, cytophilic antibodies of maternal origin reactive with C51, C53, and C57 from MN and IIIB strains were identified in cultures of uninfected infants, but not in infected infants. These observations suggest that cytophilic antibodies of maternal origin directed to HIV-1 V3 loop peptides which are bound to infant cells might play a role in preventing vertical transmission.

Amino Acid Sequence↗

PubMed1994

Cross-linking of CD4 molecules upregulates Fas antigen expression in lymphocytes by inducing interferon-gamma and tumor necrosis factor-alpha secretion.

We have recently shown that, in unfractioned peripheral blood mononuclear cells (PBMCs), the cross-linking of CD4 molecules (CD4XL) is sufficient to induce T-cell apoptosis. However, the underlying mechanism for the CD4XL-mediated T-cell apoptosis is largely unknown. Several recent studies have shown that Fas antigen (Ag), a cell-surface molecule, mediates apoptosis-triggering signals. We show here that cross-linking of CD4 molecules, induced either by anti-CD4 monoclonal antibody (MoAb) Leu3a or by human immunodeficiency virus-1 (HIV-1) envelope protein gp160, upregulates Fas Ag expression as well as Fas mRNA in normal lymphocytes. Addition of the tyrosine protein kinase inhibitor genistein or of the immunosuppressive agent cyclosporin A abrogated these effects. The upregulation of Fas Ag closely correlated with apoptotic cell death, as determined by flow cytometry. In addition, CD4XL resulted in the induction of interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) in the absence of interleukin-2 (IL-2) and IL-4 secretion in PBMCs. Both INF-gamma and TNF-alpha were found to contribute to Fas Ag upregulation and both anti-IFN-gamma and anti-TNF-alpha antibodies blocked CD4XL-induced Fas Ag upregulation and lymphocyte apoptosis. These findings strongly suggest that aberrant cytokine secretion induced by CD4XL and consequent upregulation of Fas Ag expression might play a critical role in triggering peripheral T-cell apoptosis and thereby contribute to HIV disease pathogenesis.

Antibodies↗

PubMed1994

Effect of human immunodeficiency virus type-1 envelope glycoprotein gp160 on cytokine production from cord-blood T cells.

We have recently demonstrated that the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein gp160 enhances the in vitro differentiation of hematopoietic myeloid progenitor cells derived from cord blood by inducing secretion of colony-stimulating factor(s) (CSF) in T cells, presumably through the interaction of gp160 with CD4 molecules. In this study, we investigated the gp 160-induced humoral CSFs in cord blood by enzyme-linked immunosorbent assay (ELISA) and by polymerase chain reaction on reverse-transcribed mRNA (RT-PCR). We demonstrate that gp160 can induce interleukin (IL)-3, IL-6, and granulocyte-macrophage CSF (GM-CSF) protein secretion only in purified cord-blood T cells (CB-T) and not in detectable amounts in whole cord blood cells (WCB); cytokine mRNA induction occurred in purified CB-T and WCB, but was significantly greater in the former. Treatment of gp160 with soluble CD4 (sCD4) abolished the secretion of all three cytokines in CB-T cells, which suggests that interaction of gp160 with CD4 molecules is required for the secretion of these cytokines from CB-T cells. However, in WCB cells, sCD4 treatment of gp160 resulted in inhibition of only IL-3 and GM-CSF mRNA, whereas IL-6 secretion was enhanced. Purified cord-blood monocytes secreted only IL-6 in response to gp160, and the gp160-induced IL-6 secretion by monocytes was also further increased by gp160 + sCD4 complex. Furthermore, monocyte culture supernatants suppressed gp160-induced IL-3 secretion from CB-T cells. These findings indicate that (1) CB-T cells are a potent source of gp160-induced hematopoietic cytokines, and (2) that different mechanisms are involved in the induction of IL-6 by gp160 in the T- and non-T-cell fractions of cord blood. The ability of HIV gp160 to induce hematopoietic CSFs in cord blood may be important in HIV pathogenesis.

Base Sequence↗

PubMed1994

Envelope glycoproteins of HIV-1 interfere with T-cell-dependent B cell differentiation: role of CD4-MHC class II interaction in the effector phase of T cell help.

T-cell-dependent B cell differentiation involves two phases: an inductive phase of T cell activation followed by an effector phase, which involves stimulation of B cells by activated T cells. We have previously demonstrated that anti-CD3 mAb and antigen-induced T-cell-dependent B cell functions are inhibited by HIV-1 envelope glycoprotein, gp120, at the inductive phase of T-cell-dependent B cell response. In this study we have investigated whether gp120 also inhibits the effector phase of interactions involved in T-cell-dependent-B cell differentiation response. For these studies, CD4+ T cells were first activated with antigen or pokeweed mitogen, cultured with soluble HIV-gp120 or medium for 2 hr, and washed. Coculture of gp120-treated preactivated T cells with autologous B cells resulted in impairment of IgG secretion, but did not affect IgM secretion significantly. The IgG secretion was restored by the addition of PMA (activator of protein kinase C) or forskolin (activator of adenylate cyclase), but not by the addition of ionomycin (inducer of intracellular calcium) to the T plus B cell cultures. A similar pattern of Ig secretion (IgM, no IgG) was observed with B cells of a patient with bare lymphocyte syndrome, indicating a requirement for MHC class II molecule interaction with T cells. These studies suggest that the effector phase of T-B cell interactions are impaired by gp120, and that the mechanism involves a signal transducing event(s), which is dependent upon cyclic AMP and/or protein kinase C. Furthermore, these latter reactions occur subsequent to T-B cell contact-dependent interactions at the effector phase, which involve MHC class II molecules on B cells and CD4 molecules on T cells.

Antigen Presentation↗

PubMed1994

Use of a flow cytometric assay to quantitate apoptosis in human lymphocytes.

Apoptosis is an active process of cellular self-destruction which plays an important physiologic role in the maintenance of homeostasis. This form of cell death has classically been assessed by the appearance of a "ladder-like" banding pattern upon gel electrophoresis of disrupted cells. The electrophoretic method is qualitative but offers no means of quantitation. We have optimized a flow cytometric method which allows quantitation of the apoptotic subset of cells. This assay uses propidium iodide and therefore can be performed on any flow cytometer with a blue-green excitation line. We initially verified the results of this method by using human thymocytes treated with dexamethasone, a known inducer of apoptosis. Gels were run simultaneously with flow cytometric analysis and assessed for the presence or the absence of apoptotic cells. Results obtained with gel electrophoresis correlated well with the flow cytometric method. In further studies, we applied this assay to human PBMC and obtained similar results. In conclusion, this assay is a significant improvement over currently available methodology for the determination of apoptosis. We have found it to be quantitative, reproducible, and applicable to different human cell types. The role of apoptosis in human disease remains to be elucidated and this method offers a convenient means to study this process.

Adult↗

PubMed1994

HIV-1 gp160 as a modifier of Th1 and Th2 cytokine response: gp160 suppresses interferon-gamma and interleukin-2 production concomitantly with enhanced interleukin-4 production in vitro.

Disease progression in HIV-1 infection is reported to be associated with a gradual shift in CD4+ T cell function from a Th type 1 to a Th type 2 of response, but the underlying mechanism remains unclear. In this study, the effect of HIV-1 envelope glycoprotein gp160 on secretion of cytokines IFN-gamma/IL-2 (Th1 type) and IL-4 (Th2 type) was analyzed using freshly isolated unfractioned peripheral blood mononuclear cells (PBMC), CD4+ T cell lines, and PBMC depleted of CD8+ cells (CD8- PBMC) as target cells. Pretreatment of these cells with HIV gp160 significantly reduced PHA-induced secretion of IFN-gamma and IL-2 but augmented IL-4 production. This effect of gp160 was not observed when the target cells consisted of PBMC depleted of either CD4+ cells (CD4- PBMC) or of CD2+ cells (CD2- PBMC). Pretreatment of gp160 with soluble CD4-immunoglobulin chimeric molecules abrogated the observed effects of gp160, suggesting that CD4-gp120 interaction is required for modification of the cytokine secretion profile. Our results suggest that exposure of CD4+ T cells to HIV-1 envelope proteins may modify the responses evoked by additional stimuli in favor of a Th2-type dominant response.

CD4-Positive T-Lymphocytes↗

PubMed1994

Improved specificity of in vitro anti-HIV antibody production: implications for diagnosis and timing of transmission in infants born to HIV-seropositive mothers.

In vitro anti-HIV antibody production (IVAP), initially introduced as a method for diagnosis of human immunodeficiency virus type 1 (HIV-1) infection in infants, has been limited in its application because of poor specificity and sensitivity early in life. The aims of this study were to improve the specificity of the IVAP assay and to evaluate its sensitivity in conjunction with assays of HIV culture, polymerase chain reaction (PCR), and p24 antigen. To prevent false-positive reactions resulting from maternal serum-derived cytophilic anti-HIV IgG, additional preculture and washing steps for peripheral blood mononuclear cells (PBMCs) were introduced that resulted in dramatic improvement in specificity of IVAP. The sensitivity of the revised IVAP at age < 3 months in 20 infected infants was, however, only 25%; of 15 infected infants initially negative in IVAP, 13 became positive at a mean estimated age of 4.4 +/- 1.8 months. When correlated with virological assays, a failure to respond in IVAP at age < 1 month was often associated with negative virological identification, whereas a positive IVAP response at age < 3 months was always associated with positive results in all virological assays. Moreover, conversion from negative IVAP to positive responses occurred subsequent to, and not concurrently with, a positive virological identification of infected infants. The revised IVAP methodology renders this assay potentially useful as an additional tool not only for the diagnosis of HIV infection, but for estimating timing of maternal-infant HIV transmission as well.

Antibody Specificity↗