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Biomedical subjects

Zvi Bentwich

Publications and source records attributed to Zvi Bentwich.

26 records · Page 2Linked to original sources
PubMed2003

Blocking of cell-free and cell-associated HIV-1 transmission through human cervix organ culture with UC781.

OBJECTIVE: To determine the efficacy of UC781 in preventing HIV-1 transmission through cervical tissue. DESIGN: Use of human cervical tissue organ culture, in which the cervix is in the upper chamber of a transwell and transmission of infective virus is quantified in the lower chamber. METHODS: Five-millimeter pieces of cervical tissues are exposed to UC781. After thorough removal of the drug, the tissues are exposed to high doses of cell-free or cell-associated HIV-1. Transmission of HIV-1 through the cervix is measured by determining infection of target cells in the lower chamber. RESULTS: Exposure of cervix to 0.5 microM UC781 for 30 min, followed by extensive washing away of the residual drug, resulted in 95% reduction of subsequent viral transmission. Exposure of the cervix to 1 microM UC781 for 20 min, or 10 microM UC781 for 2 min, resulted in neutralization of T- and M-tropic HIV-1 isolates of various clades, and prevention of cell-associated HIV-1 transmission. Moreover, a 20 min incubation with 10 microM UC781 abolished HIV-1 transmission through the cervix for 48 h after drug pretreatment. Importantly, UC781 was not toxic, even when the cervical tissues were exposed to 20 microM UC781 for 24 h. UC781 was effective against transmission of both cell-free and cell-associated HIV-1 also when formulated into a non-spermicidal (Replen) or spermicidal (BufferGel) gel. CONCLUSIONS: Exposure of the cervix to UC781 results in blocking of subsequent HIV-1 transmission with no toxicity. Therefore, UC781 is an excellent candidate microbiocide.

Anilides↗
PubMed2003

Concurrent infections that rise the HIV viral load.

A common denominator of all the major infections found concurrently with HIV is immune activation. Though the type and characteristics of this activation differ among the various infections, the result is invariably increased HIV infection and replication. Furthermore, the immune activation may affect other concurrent infections such as tuberculosis. Therefore, eradication or suppression of concurrent infections in HIV-infected people may have a major impact on the spread and progression of HIV infection and AIDS, and also on protective HIV vaccines. This applies particularly to developing countries, where these infections are common and no antiretroviral therapy is available. Further studies are urgently needed to clarify and further characterise the long-term effects of concurrent infections on the spread and progression of HIV/AIDS, and particularly on the immune response of the infected host.

Animals↗
PubMed2002

Attenuated signaling associated with immune activation in HIV-1-infected individuals.

Chronic immune activation is associated with impaired signal transduction. Since such activation is commonly found during HIV-1 infection, we studied cellular responses to non-specific T-cell receptor stimulation of PBMC obtained from 20 HIV-1 non-infected individuals and 23 highly or partially immune activated HIV-1 infected individuals. PBMC proliferation and ERK-1/2 phosphorylation following anti-CD3 stimulation, and constitutive levels of Cbl-b, were determined. Increased levels of Cbl-b, decreased proliferation, and lower ERK-1/2 phosphorylation were found in PBMC of highly immune activated HIV-1 infected individuals. The elevated expression of Cbl-b and impaired phosphorylation of ERK-1/2 associated with immune activation probably contribute to the attenuated proliferative and cellular responses characteristic of HIV-1 infection. Therefore, targeting immune negative modulators, such as Cbl-b, may serve as a novel approach for controlling HIV-1 disease progression.

Antigens, CD↗
PubMed2002

Treatment of intestinal worms is associated with decreased HIV plasma viral load.

BACKGROUND: We have previously suggested that helminthic infections make the host more susceptible to HIV infection and enhance its progression due to the chronic immune activation they cause. OBJECTIVE: To study the effect of antihelminthic treatment on HIV plasma viral load (VL) in HIV- and helminth-infected individuals living in Ethiopia. METHODS: Fifty-six clinically asymptomatic HIV-1-infected individuals, 31 (55%) of whom were also infected with helminths, were studied. All participants received antihelminthic treatment at baseline and at 3 and 6 months. Worm egg excretion, HIV plasma VL, and T-cell subsets were determined at baseline and 6 months after treatment. RESULTS: The mean age, number of CD4 T cells, and gender distribution were similar in the helminth-infected and -noninfected groups. At baseline, HIV plasma VL was strongly correlated to the number of eggs excreted (p <.001) and was higher in individuals infected with more than one helminth (5.28 +/- 0.35 versus 4.30 +/- 1.13 log RNA copies/mL, respectively; p =.16). After treatment of helminths, the 6-month change in HIV plasma VL was significantly different between the successfully treated group and the persistently helminth-positive group (p =.04) CONCLUSIONS: Helminth "load" is correlated to HIV plasma VL, and successful deworming is associated with a significant decrease in HIV plasma VL. The results of the current study, if confirmed in a larger study, may have important implications for slowing disease progression and reducing risks of transmission.

Acquired Immunodeficiency Syndrome↗
PubMed2002

Generation of Th1 immune responses to inactivated, gp120-depleted HIV-1 in mice with a dominant Th2 biased immune profile via immunostimulatory [correction of imunostimulatory] oligonucleotides--relevance to AIDS vaccines in developing countries.

Vaccination against HIV-1 of hosts with a dominant Th2 immune profile may fail to induce essential protective Th1 immune responses. By using Schistosoma-infected mice, with a pre-existent Th2 immune background, we demonstrate that oligodeoxynucleotides (ODN) containing unmethylated cytosine-phosphate-guanosine (CpG) immunostimulatory sequences co-administered with inactivated, gp120-depleted HIV-1 viral particles (HIV-1 immunogen) lead to potent Th1 anti-HIV-1 immune responses overcoming the Th2 bias. In contrast, Schistosoma-infected mice immunized with HIV-1 immunogen in incomplete Freund's adjuvant only, induced Th2 anti-HIV-1 immune responses. These findings strongly support the advisability of using CpG ODN as a Th1 inducing adjuvant when immunizing human populations with a strong pre-existent Th2 immune profile.

AIDS Vaccines↗
PubMed2002

CTLA-4 upregulation during HIV infection: association with anergy and possible target for therapeutic intervention.

OBJECTIVE: To study the role of cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) during HIV infection. METHODS: Intracellular CTLA-4 expression, determined by flow-cytometry, and proliferative responses to HIV antigens, were studied in peripheral blood mononuclear cells (PBMC) from 93 HIV-1-infected [HIV(+)] patients and 40 HIV-1 seronegative controls. RESULTS: The proportions of CTLA-4 expressing CD4+ T cells were: (1) significantly higher in HIV(+) patients, 10.95 +/- 0.66%, than in controls, 6 +/- 0.45% (P < 0.0001); (2) inversely correlated to CD4+ counts (r = -0.67, P < 0.005, n = 16, drug-naive patients; r = -0.57, P < 0.0001, n = 77, HAART-treated patients); and (3) positively correlated to proportion of activated (HLA-DR+CD3+) (r = 0.53, P < 0.0001) and memory (CD45RO+CD4+) T cells (r = 0.46, P < 0.001). CD28 median fluorescence intensity in CTLA-4- cells was twice that in CTLA-4+ cells (140 +/- 5.3 versus 70 +/- 2.28, P < 0.00001), whereas cells low in CD28 and CD4, expressed more CTLA-4 (P < 0.0001). Higher proportion of CTLA-4+CD4+ cells expressed CCR5 and Ki-67, in comparison with CTLA-4-CD4+ cells, (65 +/- 11.9 and 25 +/- 7.5% versus 27 +/- 8.9 and 3.7 +/- 2%, P < 0.0001 and P < 0.01, respectively). Among HAART-treated patients, with viral load below detectable levels, CD4+ cells increase was inversely correlated to %CTLA-4+CD4+ cells (r = -0.5, P = 0.003, n = 39). Proliferation of PBMC to anti-CD3, gp-120 depleted HIV-1 antigen or HIV-1 p24 stimulation was inversely correlated with CTLA-4 levels (r = -0.68, P = 0.0035; r = -0.38,P = 0.04; and r = -0.43, P = 0.028, respectively). CONCLUSIONS: (1) CTLA-4 is upregulated during HIV infection and may therefore account for CD4 T-cell decline and anergy in HIV-1 infection. (2) Increased levels of CTLA-4 may undermine immune responses and in the HAART-treated patient-immune reconstitution. (3) Blocking of CTLA-4 may offer a novel approach for immune-based therapy in HIV infection.

Abatacept↗
PubMed2002

CTLA-4 upregulation during aging.

The immune system gradually becomes anergic with age. Here, we measured intracellular levels of cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), a negative regulator of T-cells, in 53 healthy individuals aged 18-94. We found a highly significant correlation between age and percent of CTLA-4+CD4+ cells (r=0.6, P<0.001) and between age and mean fluorescence intensities of CTLA-4 (i.e. number of molecules, r=0.61, P<0.001). CTLA-4 levels were also correlated with immune activation, determined by levels of HLA-DR+CD3+ cells (r=0.55, P<0.001). We postulate that immune senescence associated with age is caused in part by chronic immune activation with related decrease in CD28 costimulatory molecules and increase in inhibitory CTLA-4 molecules.

Abatacept↗