UMLS:C0021051 - FACTA Search

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

CC chemokine receptor 5 (CCR5) is a cell entry cofactor for macrophage-tropic isolates of human immunodeficiency virus 1 (HIV-1). An inactive CCR5 allele with a 32-nucleotide deletion (CCR5Delta32) has been described that confers resistance to HIV-1 infection in homozygotes and slows the rate of progression to AIDS in heterozygotes. We found the allele CCR5Delta32 to be not rare in 399 Swiss blood donors with a frequency of 0.080. To assess the influence of defective CCR5 on production of its ligands we determined the capacity to produce the chemokines macrophage inflammatory protein (MIP)-1alpha, MIP-1beta and RANTES in comparison with the production of the CXC chemokine IL-8 which does not bind to CCR5. Production of chemokines was determined during endotoxin stimulation of whole-blood samples ex vivo. Both, basal and LPS-induced chemokine production in 32 blood donors heterozygous for CCR5Delta32 were not significantly different when compared with 55 blood donors who were homozygous for the wild type CCR5 allele.
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PMID:Heterozygous defect in HIV-1 coreceptor CCR5 and chemokine production. 1008 Aug 73

Primary infection of macaques with simian immunodeficiency virus (SIV) as a model of human immunodeficiency virus (HIV) infection represents a unique opportunity to investigate early lentivirus-host interactions. In order to gain insight into immunopathogenic events taking place in the lung during lentiviral infection, we analysed lymphocyte expansion in the lung and chemokine secretion by mononuclear cells obtained by bronchoalveolar lavage (BALMCs) during primary infection by a pathogenic and a non-pathogenic SIV. Two groups of cynomolgus macaques were inoculated intravenously with a fully pathogenic isolate of SIVmac251 or with an attenuated, nef-deleted, molecular clone of SIVmac251. Spontaneous MIP-1alpha, MIP-1beta and RANTES production was assessed by ELISA in supernatants of short-term cultured BALMCs. Kinetics of haematological, virological and immunological parameters were investigated simultaneously. All 11 inoculated animals became infected. Monkeys inoculated with the nef-deleted SIV clone exhibited a significantly reduced plasma virus load and a less pronounced accumulation of lymphocytes in the lung compared to monkeys infected with the pathogenic SIVmac251 isolate. Compared to pre-infection levels, we observed an increase in the levels of RANTES, MIP1-alpha and MIP1-beta production in the two groups of monkeys, by the time of peak viraemia. Strikingly, a greater enhancement of RANTES and MIP-1alpha production was detected in monkeys infected with the attenuated virus. Given the potential influence of beta-chemokines on the immune response and virus replication, such results suggest that RANTES, MIP1-alpha and MIP1-beta could contribute to the singular features of the immune response elicited during infection of macaques with an attenuated SIV.
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PMID:Secretion of beta-chemokines by bronchoalveolar lavage cells during primary infection of macaques inoculated with attenuated nef-deleted or pathogenic simian immunodeficiency virus strain mac251. 1009 18

The chemokine receptor CCR5 is the major coreceptor for R5 human immunodeficiency virus type-1 strains. We mapped the epitope specificities of 18 CCR5 monoclonal antibodies (mAbs) to identify domains of CCR5 required for chemokine binding, gp120 binding, and for inducing conformational changes in Env that lead to membrane fusion. We identified mAbs that bound to N-terminal epitopes, extracellular loop 2 (ECL2) epitopes, and multidomain (MD) epitopes composed of more than one single extracellular domain. N-terminal mAbs recognized specific residues that span the first 13 amino acids of CCR5, while nearly all ECL2 mAbs recognized residues Tyr-184 to Phe-189. In addition, all MD epitopes involved ECL2, including at least residues Lys-171 and Glu-172. We found that ECL2-specific mAbs were more efficient than NH2- or MD-antibodies in blocking RANTES or MIP-1beta binding. By contrast, N-terminal mAbs blocked gp120-CCR5 binding more effectively than ECL2 mAbs. Surprisingly, ECL2 mAbs were more potent inhibitors of viral infection than N-terminal mAbs. Thus, the ability to block virus infection did not correlate with the ability to block gp120 binding. Together, these results imply that chemokines and Env bind to distinct but overlapping sites in CCR5, and suggest that the N-terminal domain of CCR5 is more important for gp120 binding while the extracellular loops are more important for inducing conformational changes in Env that lead to membrane fusion and virus infection. Measurements of individual antibody affinities coupled with kinetic analysis of equilibrium binding states also suggested that there are multiple conformational states of CCR5. A previously described mAb, 2D7, was unique in its ability to effectively block both chemokine and Env binding as well as coreceptor activity. 2D7 bound to a unique antigenic determinant in the first half of ECL2 and recognized a far greater proportion of cell surface CCR5 molecules than the other mAbs examined. Thus, the epitope recognized by 2D7 may represent a particularly attractive target for CCR5 antagonists.
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PMID:Epitope mapping of CCR5 reveals multiple conformational states and distinct but overlapping structures involved in chemokine and coreceptor function. 1009 48

In macaques, the route of immunization has a profound effect on the immune response. Augmenting rectal or vaginal immunization with oral or nasal immunization enhanced the secretory IgA, serum IgG, and T cell responses. However, targeted iliac lymph node (TILN) immunization with recombinant simian immunodeficiency virus (SIV) gp120 and p27 elicited the most consistent mucosal antibody responses in the rectum, vagina, urine, seminal fluid, and blood. Both mucosal and TILN immunization induced specific CD4+ T cell proliferative responses in the iliac lymph nodes, which drain these mucosal surfaces, and in the splenic and circulating T cells. Rectal mucosal challenge with cell-free SIV induced total protection in 4 of 7 macaques that were immunized by the TILN route, and, compared with unimmunized macaques or those immunized by the mucosal route (P<.001), it induced a >90% decrease in virus load in 3 of them. Protection from mucosal rectal infection with SIV was significantly associated with an increase in the CD8 suppressor factor (which was generated by the iliac lymph node), RANTES, and MIP-1beta (P<.01).
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PMID:The effect of route of immunization on mucosal immunity and protection. 1009 26

The natural ligands for the CCR5 chemokine receptor, macrophage inflammatory protein 1alpha (MIP-1alpha), MIP-1beta, and RANTES (regulated on T-cell activation, normal T-cell expressed and secreted), are known to inhibit human immunodeficiency virus (HIV) entry, and N-terminally modified RANTES analogues are more potent than native RANTES in blocking infection. However, potent CCR5 blocking agents may select for HIV-1 variants that use alternative coreceptors at less than fully inhibitory concentrations. In this study, two N-terminal chemical modifications of RANTES produced by total synthesis, aminooxypentane (AOP)-RANTES[2-68] and N-nonanoyl (NNY)-RANTES[2-68], were tested for their ability to prevent HIV-1 infection and to select for coreceptor switch variants in the human peripheral blood lymphocyte-SCID mouse model. Mice were infected with a CCR5-using HIV-1 isolate that requires only one or two amino acid substitutions to use CXCR4 as a coreceptor. Even though it achieved lower circulating concentrations than AOP-RANTES (75 to 96 pM as opposed to 460 pM under our experimental conditions), NNY-RANTES was more effective in preventing HIV-1 infection. However, in a subset of treated mice, these levels of NNY-RANTES rapidly selected viruses with mutations in the V3 loop of envelope that altered coreceptor usage. These results reinforce the case for using agents that block all significant HIV-1 coreceptors for effective therapy.
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PMID:Highly potent RANTES analogues either prevent CCR5-using human immunodeficiency virus type 1 infection in vivo or rapidly select for CXCR4-using variants. 1019 43

The replication of simian immunodeficiency virus (SIV) in acutely infected CD4+ cells can be inhibited in vitro by CD8-suppressor factors (SF) and beta-chemokines induced by immunization of macaques with SIV gp120 and p27 in Alum. A comparison between intradermal, naso-rectal-i.m. and targeted iliac lymph node (TILN) routes showed that immunization by the TILN route elicited the most significant increase in CD8-SF and the beta-chemokines RANTES, MIP-1alpha and MIP-1beta. Increased CD8-SF and beta-chemokines were induced not only in PBMC but also in iliac lymph nodes and spleen of the TILN immunized macaques. Furthermore, CD8-SF and the concentrations of RANTES, MIP-1alpha and MIP-1beta increased with secondary immunizations, suggesting that memory CD8+ cells are involved. Treatment of CD8+ cell culture supernatant with antibodies to RANTES, MIP-1alpha and MIP-1beta neutralized the CD8-SF activity, indicating that blocking the CCR5 by these ligands played an important part in the CD8-SF activity elicited by TILN immunization. Indeed, blocking CCR5 with monoclonal antibodies inhibited SIV replications and MIP-1beta mediated chemotaxis. In contrast, SDF-1 or MAb to CXCR4 failed to suppress SIV replication. However, SDF-1 was able to induce simian PBMC chemotaxis and MAb to CXCR4 inhibited SDF-1 mediated chemotaxis. These results suggest that immunization in macaques induces CD8-SF and beta-chemokines which may prevent SIV infection by blocking the CCR5 coreceptors both in circulating cells and in the rectal and genital draining lymph node cells.
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PMID:The effect of immunization on chemokines and CCR5 and CXCR4 coreceptor functions in SIV binding and chemotaxis. 1021 80

Human CC chemokines macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, and RANTES (regulated on activation normal T cell expressed) self-associate to form high-molecular mass aggregates. To explore the biological significance of chemokine aggregation, nonaggregating variants were sought. The phenotypes of 105 hMIP-1alpha variants generated by systematic mutagenesis and expression in yeast were determined. hMIP-1alpha residues Asp26 and Glu66 were critical to the self-association process. Substitution at either residue resulted in the formation of essentially homogenous tetramers at 0.5 mg/ml. Substitution of identical or analogous residues in homologous positions in both hMIP-1beta and RANTES demonstrated that they were also critical to aggregation. Our analysis suggests that a single charged residue at either position 26 or 66 is insufficient to support extensive aggregation and that two charged residues must be present. Solution of the three-dimensional NMR structure of hMIP-1alpha has enabled comparison of these residues in hMIP-1beta and RANTES. Aggregated and disaggregated forms of hMIP-1alpha, hMIP-1beta, and RANTES generally have equivalent G-protein-coupled receptor-mediated biological potencies. We have therefore generated novel reagents to evaluate the role of hMIP-1alpha, hMIP-1beta, and RANTES aggregation in vitro and in vivo. The disaggregated chemokines retained their human immunodeficiency virus (HIV) inhibitory activities. Surprisingly, high concentrations of RANTES, but not disaggregated RANTES variants, enhanced infection of cells by both M- and T-tropic HIV isolates/strains. This observation has important implications for potential therapeutic uses of chemokines implying that disaggregated forms may be necessary for safe clinical investigation.
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PMID:Identification of amino acid residues critical for aggregation of human CC chemokines macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, and RANTES. Characterization of active disaggregated chemokine variants. 1034 59

Chemokines play diverse roles in inflammatory and non-inflammatory situations via activation of heptahelical G-protein-coupled receptors. Also, many chemokine receptors can act as cofactors for cellular entry of human immunodeficiency virus (HIV) in vitro. CCR5, a receptor for chemokines MIP-1alpha (LD78alpha), MIP-1beta, RANTES, and MCP2, is of particular importance in vivo as polymorphisms in this gene affect HIV infection and rate of progression to AIDS. Moreover, the CCR5 ligands can prevent HIV entry through this receptor and likely contribute to the control of HIV infection. Here we show that a non-allelic isoform of human MIP-1alpha (LD78alpha), termed LD78beta or MIP-1alphaP, has enhanced receptor binding affinities to CCR5 (approximately 6-fold) and the promiscuous beta-chemokine receptor, D6 (approximately 15-20-fold). We demonstrate that a proline residue at position 2 of MIP-1alphaP is responsible for this enhanced activity. Moreover, MIP-1alphaP is by far the most potent natural CCR5 agonist described to date, and importantly, displays markedly higher HIV1 suppressive activity than all other human MIP-1alpha isoforms examined. In addition, while RANTES has been described as the most potent inhibitor of CCR5-mediated HIV entry, MIP-1alphaP was as potent as, if not more potent than, RANTES in HIV-1 suppressive assays. This property suggests that MIP-1alphaP may be of importance in controlling viral spread in HIV-infected individuals.
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PMID:LD78beta, a non-allelic variant of human MIP-1alpha (LD78alpha), has enhanced receptor interactions and potent HIV suppressive activity. 1036 78

Central nervous system (CNS) involvement is a prominent feature of human immunodeficiency virus (HIV-1) infection. Monocytes and CD4+ T cells traverse the blood brain barrier (BBB), and serve as vehicles for the virus and perpetrators for brain pathology by their production of neurotoxins. In the present study cerebrospinal fluid (CSF) samples from HIV-1-infected patients were analyzed for the presence of chemotactic factors. All 36 CSF samples from the patients were positive for the CXC chemokine interferon-gamma inducible protein (IP-10), which was not detected in CSF samples of 14 controls. The IP-10 concentrations were higher in HIV-1-infected patients with HIV-1 associated neurologic disorders than in those without neurological deficits. In contrast to IP-10, other chemotactic factors including the CC chemokines MCP-1, MIP-1alpha, MIP-1beta and RANTES and the cytokines IL-15 and IL-16 were either not detected or increased in only less than 30% of the patients. Unlike the CSF samples of controls, all CSF samples from HIV-1-infected patients induced chemotaxis of T cells activated with IL-2. The significance of IP-10 as a T cell chemotactic cytokine in HIV-1-infected CSF is shown by (1) the correlation of the IP-10 levels with the extent of T cell chemotaxis, (2) the neutralization of T cell chemotaxis by anti-IP-10 antibodies and (3) the correlation of the chemotactic response of CSF samples on activated T cells and the CSF white cell count in the patients. Our data provide evidence that IP-10 contributes to the accumulation of activated T cells in the CSF compartment in HIV-1-infected individuals.
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PMID:Identification of a T cell chemotactic factor in the cerebrospinal fluid of HIV-1-infected individuals as interferon-gamma inducible protein 10. 1037 81

CCR5 is the major coreceptor for macrophage-tropic human immunodeficiency virus type I (HIV-1). For most G-protein-coupled receptors that have been tested so far, the disulfide bonds linking together the extracellular loops (ECL) are required for maintaining the structural integrity necessary for ligand binding and receptor activation. A natural mutation affecting Cys20, which is thought to form a disulfide bond with Cys269, has been described in various human populations, although the consequences of this mutation for CCR5 function are not known. Using site-directed mutagenesis, we mutated the four extracellular cysteines of CCR5 singly or in combination to investigate their role in maintaining the structural conformation of the receptor, its ligand binding and signal transduction properties, and its ability to function as a viral coreceptor. Alanine substitution of any single Cys residue reduced surface expression levels by 40-70%. However, mutation of Cys101 or Cys178, predicted to link ECL1 and ECL2 of the receptor, abolished recognition of CCR5 by a panel of conformation sensitive anti-CCR5 antibodies. The effects of the mutations on receptor expression and conformation were partially temperature-sensitive, with partial restoration of receptor expression and conformation achieved by incubating cells at 32 degrees C. All cysteine mutants were unable to bind detectable levels of MIP-1beta, and did not respond functionally to CCR5 agonists. Surprisingly, all cysteine mutants did support infection by R5 strains of HIV, though at reduced levels. These results indicate that both disulfide bonds of CCR5 are necessary for maintaining the structural integrity of the receptor necessary for ligand binding and signaling. Env binding and the mechanisms of HIV entry appear much less sensitive to alterations of CCR5 conformation.
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PMID:Extracellular cysteines of CCR5 are required for chemokine binding, but dispensable for HIV-1 coreceptor activity. 1038 87

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