Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UMLS:C0021051 (immunodeficiency)
71,517 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

CCR5 is a functional receptor for MIP-1alpha, MIP-1beta, RANTES (regulated on activation normal T cell expressed), MCP-2, and MCP-4 and constitutes the main coreceptor for macrophage tropic human and simian immunodeficiency viruses. By using CCR5-CCR2b chimeras, we have shown previously that the second extracellular loop of CCR5 is the major determinant for chemokine binding specificity, whereas the amino-terminal domain plays a major role for human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus coreceptor function. In the present work, by using a panel of truncation and alanine-scanning mutants, we investigated the role of specific residues in the CCR5 amino-terminal domain for chemokine binding, functional response to chemokines, HIV-1 gp120 binding, and coreceptor function. Truncation of the amino-terminal domain resulted in a progressive decrease of the binding affinity for chemokines, which correlated with a similar drop in functional responsiveness. Mutants lacking residues 2-13 exhibited fairly weak responses to high concentrations (500 nM) of RANTES or MIP-1beta. Truncated mutants also exhibited a reduction in the binding affinity for R5 Env proteins and coreceptor activity. Deletion of 4 or 12 residues resulted in a 50 or 80% decrease in coreceptor function, respectively. Alanine-scanning mutagenesis identified several charged and aromatic residues (Asp-2, Tyr-3, Tyr-10, Asp-11, and Glu-18) that played an important role in both chemokine and Env high affinity binding. The overlapping binding site of chemokines and gp120 on the CCR5 amino terminus, as well as the involvement of these residues in the epitopes of monoclonal antibodies, suggests that these regions are particularly exposed at the receptor surface.
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PMID:Multiple charged and aromatic residues in CCR5 amino-terminal domain are involved in high affinity binding of both chemokines and HIV-1 Env protein. 1057 39

Chemokine receptors serve as portals of entry for certain intracellular pathogens, most notably human immunodeficiency virus (HIV). Myxoma virus is a member of the poxvirus family that induces a lethal systemic disease in rabbits, but no poxvirus receptor has ever been defined. Rodent fibroblasts (3T3) that cannot be infected with myxoma virus could be made fully permissive for myxoma virus infection by expression of any one of several human chemokine receptors, including CCR1, CCR5, and CXCR4. Conversely, infection of 3T3-CCR5 cells can be inhibited by RANTES, anti-CCR5 polyclonal antibody, or herbimycin A but not by monoclonal antibodies that block HIV-1 infection or by pertussis toxin. These findings suggest that poxviruses, like HIV, are able to use chemokine receptors to infect specific cell subtypes, notably migratory leukocytes, but that their mechanisms of receptor interactions are distinct.
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PMID:Use of chemokine receptors by poxviruses. 1058 63

Analysis of immune responses generated by live-attenuated simian immunodeficiency virus (SIV) strains may provide clues to the mechanisms of protective immunity induced by this approach. We examined SIV-specific T-helper responses in macaques immunized with the live-attenuated SIV strains SIVmac239deltanef and SIVmac239delta3. Optimization of the concentration and duration of antigenic stimulation resulted in the detection of relatively strong SIV-specific proliferative responses, with peak stimulation indices of up to 84. SIV-specific proliferative responses were mediated by CD4+ T cells and were major histocompatibility (MHC) class II restricted. Limiting dilution analysis revealed SIV-specific T-helper precursor frequencies of up to 96 per 10(6) peripheral blood mononuclear cells (PBMC). Intracellular flow-cytometric analysis demonstrated the production of interleukin (IL)-2, interferon (IFN)-gamma, RANTES and macrophage inhibitory protein-1alpha (MIP-1alpha) by T lymphocytes from SIVmac239deltanef-vaccinated animals following SIV p55 stimulation. Induction of strong SIV-specific T-helper responses by live-attenuated SIV vaccines may play a role in their ability to induce protective immunity.
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PMID:Characterization of SIV-specific CD4+ T-helper proliferative responses in macaques immunized with live-attenuated SIV. 1059 90

Earlier studies have supported a significant role for cocaine in the susceptibility to and the progression of human immunodeficiency virus type 1 (HIV-1) infection. Recently, several unique HIV-1 entry coreceptors (e.g., CCR5 and CCR3) and a trio of HIV-1-specific suppressor chemokines, namely, RANTES (regulated-upon-activation T expressed and secreted), macrophage inflammatory protein 1alpha (MIP-1alpha) and MIP-1beta, were identified. Although cocaine has been linked to the immunopathogenesis of HIV-1 infection, the corresponding cellular and molecular mechanism(s) have not been well defined. We hypothesize that cocaine mediates these pathologic effects through the downregulation of HIV-1-suppressing chemokines and/or upregulating HIV-1 entry coreceptors in HIV-1-infected subjects, resulting in disease progression to AIDS. Our results show that cocaine selectively downregulates endogenous MIP-1beta secretion by normal peripheral blood mononuclear cells (PBMC), while cocaine did not affect the MIP-1beta production by PBMC from AIDS patients. Cocaine also selectively suppresses lipopolysaccharide-induced MIP-1beta production by PBMC from HIV-infected patients. Further, cocaine significantly downregulates endogenous MIP-1beta gene expression, while it upregulates HIV-1 entry coreceptor CCR5 by normal PBMC. These studies suggests a role for cocaine as a cofactor in the pathogenesis of HIV infection and support the premise that cocaine increases susceptibility to and progression of HIV-1 infection by inhibiting the synthesis of HIV-1 protective chemokines and/or upregulating the HIV-1 entry coreceptor, CCR5.
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PMID:Cocaine differentially modulates chemokine production by mononuclear cells from normal donors and human immunodeficiency virus type 1-infected patients. 1061 85

Chemokines are secreted proteins that function as chemoattractants, mediating the recruitment of specific subsets of leukocytes to sites of tissue damage and immunological reactions. Chemokines may also function as antiviral agents, since viruses such as human immunodeficiency virus type 1 (HIV-1) use chemokine receptors as co-receptors for viral entry. This study examines whether virus-induced interferon, IFNbeta, or immune-related interferon, IFNgamma, affects the production of beta-chemokines by CNS microglia and peripheral monocytes. When IFNbeta was used as the stimulus, induction of MIP-1alpha, MIP-1beta, MCP-1, and RANTES mRNA and protein was observed within 12 h of stimulation in microglia. By contrast, when IFNgamma was used as the stimulus, only MCP-1 was induced. IFNbeta stimulation of blood monocytes resulted in upregulation of MIP-1alpha, MIP-1beta, and MCP-1. Thus, type I and II interferons differentially regulate beta-chemokines in human fetal microglia and peripheral blood monocytes. These observations may have relevance for the therapeutic activity of IFNbeta in multiple sclerosis and for the antiviral effects of IFNbeta for HIV-1 infection of monocytes and microglia.
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PMID:Differential induction of chemokines in human microglia by type I and II interferons. 1064 53

To determine whether C-C chemokines play an important role in the phenotype switch of human immunodeficiency virus (HIV) from CCR5 to CXCR4 usage during the course of an infection in vivo, macrophage inflammatory protein (MIP)-1alpha-resistant variants were isolated from CCR5-tropic (R5) HIV-1 in vitro. The selected variants displayed reduced sensitivities to MIP-1alpha (fourfold) through CCR5-expressing CD4-HeLa/long terminal repeat-beta-galactosidase (MAGI/CCR5) cells. The variants were also resistant to other natural ligands for CCR5, namely, MIP-1beta (>4-fold) and RANTES (regulated upon activation, normal T-cell expressed and secreted) (6-fold). The env sequence analyses revealed that the variants had amino acid substitutions in V2 (valine 166 to methionine) and V3 (serine 303 to glycine), although the same V3 substitution appeared in virus passaged without MIP-1alpha. A single-round replication assay using a luciferase reporter HIV-1 strain pseudotyped with mutant envelopes confirmed that mutations in both V2 and V3 were necessary to confer the reduced sensitivity to MIP-1alpha, MIP-1beta, and RANTES. However, the double mutant did not switch its chemokine receptor usage from CCR5 to CXCR4, indicating the altered recognition of CCR5 by this mutant. These results indicated that V2 combined with the V3 region of the CCR5-tropic HIV-1 envelope modulates the sensitivity of HIV-1 to C-C chemokines without altering the ability to use chemokine receptors.
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PMID:Involvement of both the V2 and V3 regions of the CCR5-tropic human immunodeficiency virus type 1 envelope in reduced sensitivity to macrophage inflammatory protein 1alpha. 1064 51

Novel secreted and/or type I transmembrane proteins containing N-terminal signal sequences have been successfully cloned using the signal sequence trapping (SST) method. Often this involves random cloning of short 5' cDNA terminal ends into an epitope-tagged expression vector and the detection of expressed recombinant proteins on the cell surfaces of transfected cells with an antibody to the tagged epitope. Here, we report a novel cloning system for the detection of secreted proteins also using SST. In this method, we used the human immunodeficiency virus (HIV-1) p24 as the epitope for tagging. To test the system, two constructs were created. The 5' terminal end of a human beta-chemokine (which was regulated upon activation, expressed by normal T cells and presumably secreted [RANTES]) and the 5' end of a human CD4 receptor were cloned upstream of and in-frame with the p24 cDNA. Secreted p24 was detectable in the culture media two days after transfection of either DNA construct into the human cell lines, HeLa and 293T. When the chimeric p24 expression constructs were transfected at a ratio of 1:100 to the vector pcDNA3.1(+), p24 could still be detected in cell supernatants. The use of a secreted viral antigen like HIV-1 p24 (or of any noncellular protein) as a marker in SST cloning approaches is likely to be advantageous because it reduces the background noise in detection and also renders this system suitable for high-throughput screening.
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PMID:Cloning trap for signal peptide sequences. 1064 82

A prospective blinded study was conducted to determine whether immunological differences exist between patients receiving potent antiretroviral therapy who are able to achieve and maintain an undetectable virus load (<50 copies/mL) and those who are not. Eleven patients receiving protease inhibitor-containing antiretroviral therapy were studied for 1 year. After analysis of all baseline samples, patient virus load was disclosed, and patients were classified as suppressors (those who maintained undetectable virus load for 1 year) and nonsuppressors. Baseline virus load and CD4+ T cell count did not differ significantly between the 2 groups. Levels of RANTES production by CD4+ and CD8+ T cells and CD8-mediated inhibition of human immunodeficiency virus type 1 gene expression before initiation of antiretroviral therapy were significantly associated with an undetectable virus load maintained for 1 year (P<.05). Thus, a functionally intact T cell-mediated immune system at the time of initiation of potent antiretroviral therapy may predict long-term virus suppression.
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PMID:RANTES production by T cells and CD8-mediated inhibition of human immunodeficiency virus gene expression before initiation of potent antiretroviral therapy predict sustained suppression of viral replication. 1066 33

The beta-chemokine macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, and RANTES are critical for recruitment of inflammatory cells into infected tissue. Moreover, by binding to the human immunodeficiency virus (HIV) coreceptor CCR5, release of these chemokines could influence the course of HIV infection. beta-chemokine gene expression and release was determined by ELISA and RNase protection assay, respectively, in peripheral blood mononuclear cells (PBMC) from HIV-negative and -positive persons stimulated with Candida albicans and Cryptococcus neoformans, 2 fungi common in HIV-infected persons. Gene expression and/or release of all 3 chemokines was seen in response to both fungi although C. albicans was more potent than C. neoformans. Fungal stimulated chemokine production by HIV-positive PBMC was similar to that in HIV-negative PBMC, suggesting that the scant inflammatory response often seen in AIDS patients with cryptococcosis and candidiasis is not secondary to suboptimal beta-chemokine release.
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PMID:Stimulation of macrophage inflammatory protein-1alpha, macrophage inflammatory protein-1beta, and RANTES by Candida albicans and Cryptococcus neoformans in peripheral blood mononuclear cells from persons with and without human immunodeficiency virus infection. 1066 79

Numerous cytokines and chemokines are involved in inflammatory and immune response. Whereas some of them inhibit virus replication in vitro directly or increase the patients' T4-lymphocyte level, others effects are not so clear. Using human immunodeficiency virus (HIV) and cell cultures we have studied the antiviral effect of complexes of salmon DNA with metals and of a new factor(s) (antiviral factor, AVF) induced in cells by the complexes. The Fe3+/DNA complex possessed the highest antiviral activity. It was found that MT-2, MT-4, CEM and Jurkat cells treated with the complexes secreted AVF which inhibited the replication of nine HIV-1 isolates, was noncytotoxic and stimulated cell proliferation. AVF did not inactivate HIV. The molecular mass analysis of AVF showed that its antiviral activity is associated with its fraction of M(r) of 3 K. Reverse transcription-polymerase chain reaction (RT-PCR) analysis of mRNA from MT-4 cells treated with the complexes showed an increase in the the expression of genes for interleukin-1 alpha (IL-1 alpha), tumour necrosis factor alpha (TNF-alpha) and TNF-beta while expression of genes for IL-1-beta, IL-2, IL-4, IL-6, IL-8. IL-10, IL-12; 35p, 40p, IL-13, GMCSF, GSF and RANTES was not detected at all. However, the anti-HIV activity of the cell culture supernatant in vitro cannot be explained by mere presence of the inflammatory substances mentioned above, because they do not possess such activity and their M(r) is higher than that of AVF. Our findings raise the possibility that AVF(s) may be involved in the mechanism of cell resistance against HIV.
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PMID:A Fe(3+)/DNA complex induces an anti-human immunodeficiency virus factor(s) in CD4+ lymphocyte cell lines. 1067 40


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