Biomedical subjects

Gadi Borkow

Publications and source records attributed to Gadi Borkow.

At least 19 recordsLinked to original sources

PubMed2006

Increased TGF-beta, Cbl-b and CTLA-4 levels and immunosuppression in association with chronic immune activation.

In this study we investigated the mechanisms mediating T-cell hyporesponsiveness in chronically immune-activated individuals. We analyzed in healthy and persistently helminth-infected individuals the relationship between immune activation and general T-cell hyporesponsiveness, Th3/regulatory T-cell expression, transforming growth factor-beta (TGF-beta) secretion, CTL-associated antigen 4 (CTLA-4) levels, Casitas B-cell lymphoma-b (Cbl-b) (a negative regulator of T-cell activation) levels and phosphorylation of mitogen-activated protein kinases/extracellular signal-regulated kinase (ERK)-1 and -2. We found a very significant increase in plasma levels of TGF-beta and intracellular pools of CTLA-4 and Cbl-b in association with immune activation, which correlates with decreased T-cell responses to anti-CD3 stimulation. We demonstrate that the impaired activity of ERK of peripheral T cells in highly immune-activated individuals is associated with increased levels of CTLA-4 and Cbl-b. Interestingly, in some, but not in all, of these immune-activated individuals, induction of Cbl-b intracellular pools occurs by TGF-beta or CTLA-4 stimulation. We suggest that the higher levels of CTLA-4 and TGF-beta, both involved in the induction of Cbl-b, point at potential mechanisms underlying general and antigen-specific immune hyporesponsiveness in chronically infected individuals.

Adolescent↗

PubMed2005

A novel small animal model for HIV-1 infection.

Lethally irradiated normal BALB/c mice, reconstituted with murine SCID bone marrow and engrafted with human PBMC (Trimera mice), were used to establish a novel murine model for HIV-1 infection. The Trimera mice were successfully infected with different clades and primary isolates of T- and M-tropic HIV-1, with the infection persisting in the animals for 4-6 wk. Rapid loss of the human CD4+ T cells, decrease in CD4/CD8 ratio, and increased T cell activation accompanied the viral infection. All HIV-1 infected animals were able to generate both primary and secondary immune responses, including HIV specific human humoral and cellular responses. In addition to testing the efficacy of new antiviral compounds, this new murine HIV-1 model may be used for studying host-virus interactions and, most importantly, for screening and developing potential HIV-1 protective vaccines and adjuvants (Ayash-Rashkovsky et al., http://www.fasebj.org/cgi/doi/10.1096/fj.04-3185fje; doi:10.1096/fj.04-3185fje.).

Acquired Immunodeficiency Syndrome↗

PubMed2005

Enhanced HIV-1 specific immune response by CpG ODN and HIV-1 immunogen-pulsed dendritic cells confers protection in the Trimera murine model of HIV-1 infection.

We have recently developed a novel small animal model for HIV-1 infection (Ayash-Rashkovsky et al., http://www.fasebj.org/cgi/doi/10.1096/fj.04-3184fje; doi:10.1096/fj.04-3184fje). The mice were successfully infected with HIV-1 for 4-6 wk with different clades of either T- or M-tropic isolates. HIV-1 infection was accompanied by rapid loss of human CD4+ T cells, decrease in CD4/CD8 ratio, and increased T cell activation. HIV specific human humoral and cellular immune responses were observed in all HIV-1 infected animals. In the present study, HIV specific human immune responses, both humoral and cellular, were generated in noninfected Trimera mice, after their immunization with gp120-depleted HIV-1 antigen, presented by autologous human dendritic cells. Addition of CpG ODN to the antigen-pulsed DCs significantly enhanced (by 2- to 30-fold) the humoral and cellular HIV-1 specific immune responses. Only mice immunized with the HIV-1 immunogen and CpG were completely protected from infection with HIV-1 after challenge with high infection titers of the virus. This novel small animal model for HIV-1 infection may thus serve as an attractive platform for rapid testing of candidate HIV-1 vaccines and of adjuvants and may shorten the time needed for the development and final assessment of protective HIV-1 vaccines in human trials.

AIDS Vaccines↗

PubMed2005

TLR9 expression is related to immune activation but is impaired in individuals with chronic immune activation.

Millions of individuals in developing countries are infected with helminths and other chronic infectious diseases, such as HIV-1, which lead to persistent immune activation and unbalanced immune state. We have suggested that the capacity of chronically immune activated individuals to protect themselves, cope with infections, and mount protective immunity following vaccination, is highly impaired. Here we examined the expression of toll-like receptor 9 (TLR9), as an essential component in the recognition of immunostimulating bacterial CpG-DNA motifs, in different subsets of human peripheral blood mononuclear cells (PBMC) obtained from chronically immune activated and non-activated individuals. TLR9 expression was correlated to immune cell activation and was upregulated following phytohemagglutinin or anti-CD3 activation. PBMC obtained from chronically immune activated individuals had a different overall pattern of TLR9 expression, including reduced upregulation of this receptor following additional immune activation, and diminished responsiveness to CpG-DNA stimulation, in comparison to non-activated individuals. These differences may partly account for the reduced capacity of chronically immune activated individuals to mount effective immune responses and strengthen the notion that the host immune background should be considered in the design and trial of potential adjuvants and vaccines.

Adolescent↗

PubMed2005

Can worms defend our hearts? Chronic helminthic infections may attenuate the development of cardiovascular diseases.

The established risk factors for atherosclerosis fail to fully explain the extent and severity of coronary artery diseases in 50% of the patients. Thus, the causative agents and processes, which may be involved in the pathogenesis of atherosclerosis, are being sought. Notoriously, atherosclerosis and cardiovascular event rates are much lower in developing countries. Clinically, severe infections by intracellular pathogens are widespread mostly in developing countries with poor sanitation, nutrition and massive worm infections. A link between atherosclerosis and helminth infections has never been examined. Based on the present knowledge of immune and infectious mechanisms related to atherosclerosis, it is proposed that chronic helminthic infections can have a significant bearing on the epidemiology of cardiovascular diseases. How can helminthic infections affect the cardiovascular risk? (1) Helminths evade or suppress host immune responses, by producing anti-inflammatory and other immunomodulatory molecules. (2) Helminths induce chronic Th2 activation, which can modify cytokine profiles and immunological responses to heat shock proteins, Chlamydia pneumoniae and cytomegalovirus. (3) The chronic Th2 profile may modulate monocyte activation and chemotaxis to inflammatory sites (atherosclerotic plaques). (4) Chronic Th2 activation may lead to a cytokine profile that could be beneficial for attenuation of atherosclerosis development (upregulation of IL-4, IL-10 and IL-13 and downregulation of proinflammatory cytokines). (5) Helminthic infections may reduce plasma LDL level not only by affecting the host nutrition, but also via modulation of naturally occurring antibodies to cholesterol. Studies are needed to clarify these suggestions. If the hypothesis that helminthic infections impact atherosclerosis is correct, it should be taken into consideration in atherosclerosis immunomodulation therapy and especially in the design of vaccines and vaccine trials.

Animals↗

PubMed2005

Mouse models for HIV-1 infection.

The generation of small animal models, which preserve the ability for the generation of primary and memory immune responses of the engrafted human immune cells and in which a robust HIV-1 infection may occur, may enable the rapid screening, development and evaluation of HIV-1 protective vaccines and adjuvants. This manuscript reviews the existing mouse HIV-1 models used to study virologic, immunologic and pathogenic aspects of HIV-1 infection and disease and discusses their limitations and advantages, especially in the context of vaccine development, with special focus on the recently developed Trimera-HIV-1 animal model.

AIDS Vaccines↗

PubMed2005

Copper as a biocidal tool.

Copper ions, either alone or in copper complexes, have been used to disinfect liquids, solids and human tissue for centuries. Today copper is used as a water purifier, algaecide, fungicide, nematocide, molluscicide as well as an anti-bacterial and anti-fouling agent. Copper also displays potent anti-viral activity. This article reviews (i) the biocidal properties of copper; (ii) the possible mechanisms by which copper is toxic to microorganisms; and (iii) the systems by which many microorganisms resist high concentrations of heavy metals, with an emphasis on copper.

Anti-Infective Agents↗

PubMed2004

Putting copper into action: copper-impregnated products with potent biocidal activities.

Copper ions, either alone or in copper complexes, have been used for centuries to disinfect liquids, solids, and human tissue. Today copper is used as a water purifier, algaecide, fungicide, nematocide, molluscicide, and antibacterial and antifouling agent. Copper also displays potent antiviral activity. We hypothesized that introducing copper into clothing, bedding, and other articles would provide them with biocidal properties. A durable platform technology has been developed that introduces copper into cotton fibers, latex, and other polymeric materials. This study demonstrates the broad-spectrum antimicrobial (antibacterial, antiviral, antifungal) and antimite activities of copper-impregnated fibers and polyester products. This technology enabled the production of antiviral gloves and filters (which deactivate HIV-1 and other viruses), antibacterial self-sterilizing fabrics (which kill antibiotic-resistant bacteria, including methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococci), antifungal socks (which alleviate symptoms of athlete's foot), and anti-dust mite mattress covers (which reduce mite-related allergies). These products did not have skin-sensitizing properties, as determined by guine pig maximization and rabbit skin irritation tests. Our study demonstrates the potential use of copper in new applications. These applications address medical issues of the greatest importance, such as viral transmissions; nosocomial, or healthcare-associated, infections; and the spread of antibiotic-resistant bacteria.

Acaridae↗

PubMed2004

Adenovirus expressing a bioluminescence reporter gene and cMAGI cell assay for the detection of HIV-1.

We report a fast, highly sensitive method for detecting and testing drug resistance of M-tropic and T-tropic laboratory and primary HIV-1 isolates. cMAGI cells are infected with an adenovirus vector harboring the luciferase reporter gene controlled by HIV-1 Tat-responsive element, TAR. HIV-1 Tat production by HIV-1 chronically infected cells, or by cMAGI cells as early as two days after being acutely infected with HIV-1, is readily monitored in the presence or absence of antiviral drugs. This method is more sensitive than HIV-1 Tat dependant production of beta-galactosidase in the cMAGI cells. The fast answer, ease and sensitivity as well as the possibility of using this method in high throughput screening, makes it an very attractive tool for phenotypic detection of HIV-1 in clinical samples as well as a sensitive assay for monitoring drug resistant HIV-1 variants. This method can also be used for discovery of novel anti HIV-1 drugs.

Adenoviridae↗

PubMed2004

Chronic immune activation associated with chronic helminthic and human immunodeficiency virus infections: role of hyporesponsiveness and anergy.

Chronic immune activation is one of the hallmarks of human immunodeficiency virus (HIV) infection. It is present also, with very similar characteristics, in very large human populations infested with helminthic infections. We have tried to review the studies addressing the changes in the immune profiles and responses of hosts infected with either one of these two chronic infections. Not surprisingly, several of the immune derangements and impairments seen in HIV infection, and considered by many to be the "specific" effects of HIV, can be found in helminth-infected but HIV-noninfected individuals and can thus be accounted for by the chronic immune activation itself. A less appreciated element in chronic immune activation is the immune suppression and anergy which it may generate. Both HIV and helminth infections represent this aspect in a very wide and illustrative way. Different degrees of anergy and immune hyporesponsiveness are present in these infections and probably have far-reaching effects on the ability of the host to cope with these and other infections. Furthermore, they may have important practical implications, especially with regard to protective vaccinations against AIDS, for populations chronically infected with helminths and therefore widely anergic. The current knowledge of the mechanisms responsible for the generation of anergy by chronic immune activation is thoroughly reviewed.

AIDS-Related Opportunistic Infections↗

PubMed2003

Mutations in gp41 and gp120 of HIV-1 isolates resistant to hexa-arginine neomycin B conjugate.

Aminoglycoside-arginine conjugates (AACs) inhibit HIV-1 replication and act as Tat antagonists. AACs compete with monoclonal antibody binding to CXCR4, compete with SDF-1alpha and HIV-1 gp120 cellular uptake, indicating that they interfere with initial steps of HIV-1 infection. We here present the selection of HIV-1 isolates resistant to hexa-arginine neomycin B conjugate (NeoR6), the most potent anti-HIV-1 AAC. We found in the NeoR6-resistant isolates the following mutations in gp120: I339T in the C3 region, S372L in the V4 region, and Q395K in the C4 region; and in gp41: S668R and F672Y in the 'heptad repeat' 2 (HR2) region. These findings strongly suggest that NeoR6 obstructs HIV-1 replication by interfering with the fusion step, dependent on both conformational changes in gp120 following CD4 and CXCR4 interaction, as well as by conformational changes in gp41 induced by HR1 and HR2 interaction. The AACs may thus represent a novel family of fusion inhibitors.

Drug Resistance↗

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

Structure-activity relationship of neomycin, paromomycin, and neamine-arginine conjugates, targeting HIV-1 gp120-CXCR4 binding step.

We have recently designed and synthesized aminoglycoside-arginine conjugates (AACs) as potential anti-HIV-1 agents. AACs exert a number of activities related to Tat antagonism. We here present a new set of AACs, conjugates of neomycin B, paromomycin, and neamine with different number of arginines (1-6), their (a) uptake by human T-cell lines, (b) antiviral activities, (c) competition with monoclonal antibody (mAb) 12G5 binding to CXCR4, (d) competition with stromal cell-derived factor-1 (SDF-1alpha) binding to CXCR4, and (e) competition with HIV-1 coat protein gp120 cell penetration. The appearance of mutations in HIV-1 gp120 gene in AACs resistant HIV-1 isolates, supports that AACs inhibit HIV-1 infectivity via interference of gp120-CXCR4 interaction. Our results point that the most potent AACs is the hexa-arginine-neomycin conjugate, the other multi-arginine-aminoglycoside conjugates are less active, and the mono-arginine conjugates display the lowest activity. Our studies demonstrate that, in addition to the core, the number of arginines attached to a specific aminoglycoside, are also important in the design of potent anti-HIV agents. The AACs play an important role, not only as HIV-1 RNA binders but also as inhibitors of viral entry into human cells.

Anti-HIV Agents↗

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

Attenuated infectivity of HIV type 1 from epithelial cells pretreated with a tight-binding nonnucleoside reverse transcriptase inhibitor.

Short exposure of uninfected lymphocytes to UC781, a tight-binding nonnucleoside reverse transcriptase inhibitor (NNRTI), renders these cells refractory to subsequent HIV infection in the absence of exogenous drug (Borkow et al: J Virol 1997;71:3023-3030). Since epithelial cells may play a role in the sexual transmission of HIV-1, we examined the ability of NNRTI pretreatment to protect ME180 cervical epithelial cells and I407 intestinal epithelial cells from subsequent HIV-1 infection. Epithelial cells were pretreated with NNRTI, then exposed to HIV-1 chronically infected H9(+) cells for a short time following removal of the exogenous drug. The epithelial cells were productively infected by HIV-1, as shown by the presence of integrated HIV-1 proviral DNA, the presence of intracellular p24 antigen, and the production of nascent HIV-1 virions (cell-free p24) at various times postinfection. UC781 pretreatment of the epithelial cells did not prevent HIV-1 infection, since the cells had integrated proviral DNA, but the infectivity of virus subsequently produced from the UC781-treated cells was attenuated in a dose-dependent manner and virtually abolished at UC781 concentrations readily attainable in vivo. In contrast, nevirapine was ineffective in this respect, suggesting that not all NNRTI have microbicidal potential. The abrogation of infectivity of virus produced from UC781-pretreated epithelial cells suggests that this NNRTI may be useful in vaginal microbicide formulations targeted to inhibit HIV-1 in the vaginal/cervical or rectal milieus of a newly exposed individual.

Anilides↗

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↗