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Query: UMLS:C0019693 (HIV)
 170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The human immunodeficiency virus type 1 (HIV-1) requires the presence of specific chemokine receptors in addition to CD4 to enter its target cell. The chemokine receptor CCR5 is used by macrophage-tropic strains of HIV-1, which predominate during the asymptomatic stages of infection. Here we investigate whether the ability of CCR5 to signal in response to its beta-chemokine ligands is necessary or sufficient for viral entry. Three CCR5 mutants with little or no ability to mobilize calcium in response to macrophage inflammatory protein-1beta could nonetheless support HIV-1 entry and the early steps in the virus life cycle with efficiencies comparable with those of wild-type CCR5. Conversely, a chimeric receptor with the N terminus of CCR2 replacing that of CCR5 responded to macrophage inflammatory protein-1beta and MCP-1 but did not efficiently support viral entry. These results demonstrate that chemokine signaling and HIV-1 entry are separable functions of CCR5 and that only viral entry requires the N-terminal domain of CCR5.
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PMID:HIV-1 entry and macrophage inflammatory protein-1beta-mediated signaling are independent functions of the chemokine receptor CCR5. 905 70

Monocyte chemotactic protein-1 (MCP-1) interacts with the chemokine receptor CCR2. Two CCR2 cDNAs have been described. Sequence analysis as well as Northern blotting and RNase protection with different probes revealed that the CCR2 gene is expressed in activated natural killer (NK) cells and mononuclear phagocytes as a predominant long transcript (3.4 kb) consisting of CCR2B followed by a novel sequence (X), corresponding to an intron in the genome, and by a CCR2A specific portion. The predominant long transcript is polyadenylated and present in the cytoplasm. We found that bacterial products and cytokines affect CCR2 expression. Interleukin-2 (IL-2) augmented CCR2 mRNA in monocytes and NK cells. The augmented migratory capacity of IL-2-activated versus resting NK cells was associated with increased CCR2 transcript levels. Lipopolysaccharide (LPS) and other microbial agents caused a rapid and drastic reduction of CCR2 mRNA levels. The rate of nuclear transcription of CCR2 was not affected by LPS, whereas the mRNA half life was reduced. These results suggest that regulation of receptor expression, in addition to agonist production, is probably a crucial point in the regulation of the chemokine system. Down-regulation of chemokine receptor expression may play a role in the modulation of HIV infection in macrophages by LPS. Levels of MCP-1 were markedly elevated in the cerebrospinal fluid (CSF) but not in blood of HIV-infected patients with cytomegalovirus (CMV) encephalitis. The CSF levels of MCP-1 in CMV encephalitis were markedly higher than those found in the CSF of HIV-infected patients with or without unrelated neurological diseases. IL-8, the prototype of C-X-C chemokines and RANTES and macrophage inflammatory protein-1 alpha (C-C chemokines) were not substantially increased in the liquor of CMV encephalitis patients. High levels of MCP-1 may underlie monocyte recruitment and tissue damage in CMV encephalitis and may represent a rapid and useful tool in the diagnostic armamentarium for neurological disorders associated with HIV.
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PMID:MCP-1 and CCR2 in HIV infection: regulation of agonist and receptor expression. 922 89

The chemokines are a homologous serum protein family characterized by their ability to induce activation of integrin adhesion molecules and leukocyte migration. Chemokines interact with their receptors, which are composed of a single-chain, seven-helix, membrane-spanning protein coupled to G proteins. Two CC chemokine receptors, CCR3 and CCR5, as well as the CXCR4 chemokine receptor, have been shown necessary for infection by several HIV-1 virus isolates. We studied the effect of the chemokine monocyte chemoattractant protein 1 (MCP-1) and of a panel of MCP-1 receptor (CCR2)-specific monoclonal antibodies (mAb) on the suppression of HIV-1 replication in peripheral blood mononuclear cells. We have compelling evidence that MCP-1 has potent HIV-1 suppressive activity when HIV-1-infected peripheral blood lymphocytes are used as target cells. Furthermore, mAb specific for the MCP-1R CCR2 which recognize the third extracellular CCR2 domain inhibit all MCP-1 activity and also block MCP-1 suppressive activity. Finally, a set of mAb specific for the CCR2 amino-terminal domain, one of which mimics MCP-1 activity, has a potent suppressive effect on HIV-1 replication in M- and T-tropic HIV-1 viral isolates. We conjecture a role for CCR2 as a coreceptor for HIV-1 infection and map the HIV-1 binding site to the amino-terminal part of this receptor. This concurs with results showing that the CCR5 amino terminus is relevant in HIV-1 infection, although chimeric fusion of various extracellular domains shows that other domains are also implicated. We discuss the importance of CCR2 structure relative to its coreceptor role and the role of anti-CCR2 receptor antibodies in the prevention of HIV-1 infection.
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PMID:The amino-terminal domain of the CCR2 chemokine receptor acts as coreceptor for HIV-1 infection. 923 95

The critical role of chemokine receptors (CCR5 and CXCR4) in human immunodeficiency virus-type 1 (HIV-1) infection and pathogenesis prompted a search for polymorphisms in other chemokine receptor genes that mediate HIV-1 disease progression. A mutation (CCR2-64I) within the first transmembrane region of the CCR2 chemokine and HIV-1 receptor gene is described that occurred at an allele frequency of 10 to 15 percent among Caucasians and African Americans. Genetic association analysis of five acquired immunodeficiency syndrome (AIDS) cohorts (3003 patients) revealed that although CCR2-64I exerts no influence on the incidence of HIV-1 infection, HIV-1-infected individuals carrying the CCR2-64I allele progressed to AIDS 2 to 4 years later than individuals homozygous for the common allele. Because CCR2-64I occurs invariably on a CCR5-+-bearing chromosomal haplotype, the independent effects of CCR5-Delta32 (which also delays AIDS onset) and CCR2-64I were determined. An estimated 38 to 45 percent of AIDS patients whose disease progresses rapidly (less than 3 years until onset of AIDS symptoms after HIV-1 exposure) can be attributed to their CCR2-+/+ or CCR5-+/+ genotype, whereas the survival of 28 to 29 percent of long-term survivors, who avoid AIDS for 16 years or more, can be explained by a mutant genotype for CCR2 or CCR5.
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PMID:Contrasting genetic influence of CCR2 and CCR5 variants on HIV-1 infection and disease progression. Hemophilia Growth and Development Study (HGDS), Multicenter AIDS Cohort Study (MACS), Multicenter Hemophilia Cohort Study (MHCS), San Francisco City Cohort (SFCC), ALIVE Study. 925 28

Dendritic cells (DC) are migratory cells that exhibit complex trafficking properties in vivo. The present study was designed to characterize receptor expression and responsiveness to chemoattractants of human DC obtained from PBMC by culture with granulocyte/macrophage-CSF and IL-13. DC expressed appreciable levels of the CCR1, CCR2, and CCR5 receptors for the CC chemokines and the chemokine receptors CXCR1, CXCR2, and CXCR4. DC increased intracellular free calcium and migrated in response to the CC chemokines MCP-3, MCP-4, RANTES, MIP-1alpha, MIP-1beta, and MIP-5/HCC2 and the CXC chemokine SDF-1. In contrast, the CC chemokines MCP-1 and eotaxin had little or no activity in the concentration range tested (up to 1 microg/ml). IL-8 and Gro-beta (CXC) and lymphotactin (C chemokines) were also inactive. DC did not respond to 5-HETE, whereas platelet-activating factor was an active agonist. Selected chemokines active on DC in terms of migration and calcium fluxes were examined for their capacity to modulate endocytosis and Ag presentation. Under conditions in which TNF-alpha was active, MCP-1, MCP-3, MIP-1alpha, and RANTES did not affect these two responses. Thus, among hemopoietic elements, DC respond to a unique set of CC and CXC chemokines, and their responsiveness is restricted to migration with no effect on Ag capture and presentation. Chemokines may play a role in the trafficking of DC under resting or stimulated conditions. Chemokine receptors expressed in DC are likely to underlie HIV infection of this cell type.
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PMID:Receptor expression and responsiveness of human dendritic cells to a defined set of CC and CXC chemokines. 925 66

The CC chemokine receptors CCR5, CCR2, and CCR3 and the CXC chemokine receptor CXCR4 have been implicated as CD4-associated cofactors in the entry of primary and cell line-adapted human immunodeficiency virus type 1 (HIV-1) strains. CXCR4 is also a receptor for T-cell-line-adapted, CD4-independent strains of HIV-2. With the exception of this latter example, little has been reported on the entry cofactors used by HIV-2 strains. Here we show that a CD4-dependent, T-cell-line-adapted HIV-2 strain uses CXCR4 and, to a lesser extent, CCR3 for fusion with and infectious entry into cells. In a cell-to-cell fusion assay, the envelope protein of this virus can utilize a wider repertoire of chemokine receptors to induce fusion. These include CCR1, CCR2, CCR3, CCR4, CCR5, CXCR2, and CXCR4. Kinetic analysis indicated that cell lines expressing the receptors that support infection, CXCR4 and CCR3, form syncytia more rapidly than do cell lines expressing the other receptors. Nevertheless, although less efficient, fusion with CXCR2 expressing cells was specific, since it was inhibited by antibodies against CXCR2. The extensive use of chemokine receptors in cell-to-cell fusion has implications for understanding the molecular basis of CD4-chemokine receptor-induced lentivirus fusion and may have relevance for syncytium formation and the direct cell-to-cell transfer of virus in vivo.
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PMID:Promiscuous use of CC and CXC chemokine receptors in cell-to-cell fusion mediated by a human immunodeficiency virus type 2 envelope protein. 934 97

Chemokines are a structurally related family of cytokines that are important for leukocyte trafficking. The C-C chemokine monocyte chemoattractant protein-1 (MCP-1) is a potent monocyte activator in vitro and has been associated with monocytic infiltration in several inflammatory diseases. One C-C chemokine receptor, CCR2, has been identified that mediates in vitro responses to MCP-1 and its close structural homologues. CCR2 has also recently been demonstrated to be a fusion cofactor for several HIV isolates. To investigate the normal physiological function of CCR2, we generated mice with a targeted disruption of the ccr2 gene. Mice deficient for CCR2 developed normally and had no hematopoietic abnormalities. However, ccr2(-/-) mice failed to recruit macrophages in an experimental peritoneal inflammation model. In addition, these mice were unable to clear infection by the intracellular bacteria, Listeria monocytogenes. These results suggest that CCR2 has a nonredundant role as a major mediator of macrophage recruitment and host defense against bacterial pathogens and that MCP-1 and other CCR2 ligands are effectors of those functions.
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PMID:Defects in macrophage recruitment and host defense in mice lacking the CCR2 chemokine receptor. 936 35

Stromal-derived factor (SDF-1) is the principal ligand for CXCR4, a coreceptor with CD4 for T lymphocyte cell line-tropic human immunodeficiency virus-type 1 (HIV-1). A common polymorphism, SDF1-3'A, was identified in an evolutionarily conserved segment of the 3' untranslated region of the SDF-1 structural gene transcript. In the homozygous state, SDF1-3'A/3'A delays the onset of acquired immunodeficiency syndrome (AIDS), according to a genetic association analysis of 2857 patients enrolled in five AIDS cohort studies. The recessive protective effect of SDF1-3'A was increasingly pronounced in individuals infected with HIV-1 for longer periods, was twice as strong as the dominant genetic restriction of AIDS conferred by CCR5 and CCR2 chemokine receptor variants in these populations, and was complementary with these mutations in delaying the onset of AIDS.
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PMID:Genetic restriction of AIDS pathogenesis by an SDF-1 chemokine gene variant. ALIVE Study, Hemophilia Growth and Development Study (HGDS), Multicenter AIDS Cohort Study (MACS), Multicenter Hemophilia Cohort Study (MHCS), San Francisco City Cohort (SFCC) 945 27

Viral and host factors influence the rate of HIV-1 disease progression. For HIV-1 to fuse, a CD4+ cell must express a co-receptor that the virus can use. The chemokine receptors CCR5 and CXCR4 are used by R5 and X4 viruses, respectively. Most new infections involve transmission of R5 viruses, but variants can arise later that also use CXCR4 (R5-X4 or X4 viruses). This is associated with an increased rate of CD4+ T-cell loss and poor prognosis. The ability of host cells to support HIV-1 entry also influences progression. The absence of CCR5 in approximately 1% of the Caucasian population, due to homozygosity for a 32-nucleotide deletion in the coding region (delta32-CCR5 allele), very strongly protects against HIV-1 transmission. Heterozygosity for the delta32-CCR5 allele delays progression typically by 2 years. A recent study showed that a conservative substitution (V64I) in the coding region of CCR2 also has a significant impact on disease progression, but not on HIV-1 transmission. This was unexpected, since CCR2 is rarely used as a co-receptor in vitro and the V64I change is in a transmembrane region. Because a subsequent study did not confirm this effect on progression to disease, we analyzed CCR2-V64I using subjects in the Chicago MACS. We show that CCR2-V64I is indeed protective against disease progression and go on to show that the CCR2-V64I allele is in complete linkage disequilibrium with a point mutation in the CCR5 regulatory region.
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PMID:A chemokine receptor CCR2 allele delays HIV-1 disease progression and is associated with a CCR5 promoter mutation. 958 7

beta-chemokines play an important role in the development of immunologic reactions. Macrophages are major beta-chemokine-producing cells during T-cell directed, delayed-type hypersensitivity reactions in tissues, and have been reported to be important producers of beta-chemokines in the lymph nodes of HIV-1-infected individuals. However, the physiological signals responsible for inducing macrophages to produce beta-chemokines have not been established. Two soluble T cell products, interferon-gamma and granulocyte-macrophage colony stimulating factor, were added to cultured macrophages, but failed to stimulate the production of macrophage inflammatory protein-1alpha and -1beta; regulated upon activation, normal T cell expressed and secreted (RANTES); or monocyte chemoattractant protein-1. Instead, direct cell-cell contact between macrophages and cells engineered to express CD40L (also known as CD154) resulted in the production of large amounts of macrophage inflammatory protein-1alpha and -1beta, and RANTES (all ligands for CCR5), and monocyte chemoattractant protein-1 (a ligand for CCR2). Supernatants from CD40L-stimulated macrophages protected CD4(+) T cells from infection by a nonsyncytium-inducing strain of HIV-1 (which uses CCR5 as a coreceptor). These results have implications for granulomatous diseases, and conditions such as atherosclerosis and multiple sclerosis, where CD40L-bearing cells have been found in the macrophage-rich lesions where beta-chemokines are being produced. Overall, these findings define a pathway linking the specific recognition of antigen by T cells to the production of beta-chemokines by macrophages. This pathway may play a role in anti-HIV-1 immunity and the development of immunologic reactions or lesions.
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PMID:CD40 ligand (CD154) stimulation of macrophages to produce HIV-1-suppressive beta-chemokines. 956 Feb 54


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