CD4 T cell surface CCR5 density as a host factor in HIV-1 disease progression

OBJECTIVE AND DESIGN: We have recently shown that the number of CCR5 molecules at the surface of peripheral blood CD4 T cells (CCR5 density) correlates with the viral RNA plasma level in HIV-1-infected individuals. As viral load is a strong predictor of outcome in HIV infection, the present study examines the correlation between CCR5 density and HIV-1 disease progression. METHODS: Using a quantitative flow cytometry assay, we measured CCR5 density in HIV-1-infected adults and control healthy volunteers. The CCR5 genotype (presence of a Delta 32 allele) was also determined. RESULTS: CCR5 density was stable over time on non-activated, HLA-DR(-)CD4 T cells of infected individuals. In a study cohort of 25 patients, asymptomatic and non-treated, we observed a correlation between CCR5 density on HLA-DR(-)CD4 T cells and the CD4 T cell slope (P = 0.026), which was independent of the presence or absence of the Delta 32CCR5 deletion. In particular, slow progressors expressed lower CCR5 densities than non-slow progressors (P = 0.004) and non-infected control subjects (P = 0.002). CONCLUSION: These results are compatible with the hypothesis that CCR5 density, which is a key factor of HIV-1 infectability, determines in-vivo HIV production, and thereby the rate of CD4 cell decline. Consequently, CCR5 density quantitation could be a new valuable prognostic tool in HIV-1 infection. Moreover, these data emphasize the therapeutic potential of treatments that reduce functional CCR5 density.     

Dichotomous effects of Plasmodium falciparum antigens on expression of human immunodeficiency virus (HIV) coreceptors and on infectability of CD4 cells by HIV

Many microbial coinfections accelerate the progression of human immunodeficiency virus (HIV) disease. Coinfections of Plasmodium falciparum malaria and HIV-1 are common; however, past studies of the effects of P. falciparum malaria on HIV-1 infection have shown little effect. The present study found that P. falciparum antigens (PF-Ags) variably regulate the expression of HIV-1 coreceptors and modulate the infectability of CD4 cells by HIV-1. Shortly after PF-Ag stimulation, CCR5 expression was down-regulated, but CXCR4 expression was modestly up-regulated. Subsequently, CCR5 expression on CD4 cells was induced. Infectability of PF-Ag-stimulated peripheral blood mononuclear cells (PBMC) by R5 HIV-1 was decreased, regardless of the duration of PF-Ag stimulation or CCR5 expression levels. In contrast, X4 HIV-1 replication was enhanced briefly in PBMC stimulated with PF-Ags but was inhibited with longer stimulation. Decreased HIV-1 infectability resulted, in part, from endogenous production of interferon-gamma. These results may explain why malaria previously did not appear to accelerate HIV-1 disease progression.     

The efficiency of R5 HIV-1 infection is determined by CD4 T-cell surface CCR5 density through G alpha i-protein signalling

OBJECTIVE AND DESIGN: The intensity of replication of CCR5-using HIV-1 strains is highly dependent on the number of CCR5 molecules on the surface of CD4-positive T cells. The molecular mechanisms responsible for this phenomenon remained so far unclear. As CCR5 co-receptors are coupled to G alpha i and G alpha q proteins, we tested the hypothesis that the activation triggered through these proteins secondary to the interaction between the viral envelope and CCR5 could account for the effect of the level of CCR5 expression on HIV-1 production. METHODS: We transduced the wild-type or a G-protein signalling-defective CCR5 gene into CD4/CCR5 HOS cells and peripheral blood mononuclear cells. The effect on cell activation in presence of a CCR5-binding chemokine and on HIV infection was monitored by measuring calcium mobilization and p24 antigen production, respectively. The role of G alpha i protein signalling was tested by adding pertussis toxin to the cell cultures or by transfecting small interfering (si) RNAs into the HOS cells. RESULTS: The over-expression of the wild-type form, but not of a G-protein signalling-defective form of CCR5, on the surface of CCR5 expressing peripheral blood mononuclear cells markedly increased their infectability. In addition, both pertussis toxin and G alpha i 1-specific siRNA drastically inhibited R5 infection. CONCLUSIONS: The signalling through G alpha i-protein induced upon R5 virion binding to CCR5 is responsible for the difference in HIV-1 infectability between CD4-positive T cells expressing low or high levels of cell surface CCR5 density. This observation sheds new light on the physiopathology of HIV infection, and opens new therapeutic opportunities targeting G alpha i signalling.     

New T-lymphocytic cell lines for studying cell infectability by human immunodeficiency virus

We identified five human T-lymphoid cell lines (PB-1, Sez-4, C19PL, HUT 102B and ATL-2) which highly express CD4 in addition to CXCR4 and CCR5. In order to evaluate if these cells are infectabile by human immunodeficiency virus (HIV) and could be employed as a model in HIV research we exposed these cell lines to X4 (T-cell tropic) and R5 (macrophage tropic) and subsequently tried to correlate their infectability with (i) level of chemokine coreceptor (CXCR4 and CCR5) expression, (ii) coreceptor functionality (calcium flux, chemotaxis and phosphorylation of MAPK p42/44 and AKT) and (iii) endogenous expression and secretion of HIV-related chemokines which compete with the virus for binding to CXCR4 (SDF-1/CXCL12) or CCR5 (MIP-1beta/CCL4, MIP-1alpha/CCL3, RANTES/CCL5, MCP-2/CCL8, MCP-3/CCL7 and MCP-4/CCL13). We demonstrated that while PB-1 cells are infectable by both X4 and R5 HIV, Sez-4, C91PL, HUT 102B and ATL-2 cells were infected by X4 HIV only. Moreover, we noticed that the susceptibility of these cells to HIV did not correspond either with the level of surface expression or with the functionality of CXCR4 or CCR5; however, it was modulated to some degree by the endogenously secreted HIV-related chemokines. Thus all five mature T-cell lines described here may provide useful new models for studying various aspects of HIV infection. In addition we demonstrate that the infectability of cells by HIV is modulated by so far unidentified intrinsic factors as well as some already known endogenously secreted chemokines. The identification of these factors may be important for developing new strategies to protect cells from HIV infection.     

Activation of beta-chemokines and CCR5 in persons infected with human immunodeficiency virus type 1 and tuberculosis

Tuberculosis (TB) in human immunodeficiency virus type 1 (HIV-1)-infected persons is associated with progression of HIV-1 disease. The expression of macrophage inflammatory protein (MIP)-1alpha and CCR5 was assessed in HIV-1-infected patients with pulmonary TB (HIV-1/PTB) and without PTB (HIV-1/C), PTB patients not infected with HIV-1 (PTB), and control subjects. Mycobacterium tuberculosis (MTB)-induced MIP-1alpha production was lower in peripheral blood mononuclear cells (PBMC) of HIV-1/PTB patients than in those of PTB patients (P< .05) and was lower in PBMC of HIV-1/C patients than in those of control subjects (P< .005). However, MIP-1alpha production was higher in PBMC of HIV/PTB patients than in those of HIV-1/C patients (P< .01). The pattern of MTB-induced RANTES production was similar to that of MIP-1alpha. However, MTB induced greater expression of mRNA for CCR5 in PBMC of HIV-1/PTB patients than in those of HIV-1/C patients (P< .04). Furthermore, the MTB-induced HIV p24 antigen level in PBMC of HIV-1/PTB patients with a CD4 cell count <500 cells/microL was higher (P< .05) than that in HIV-1/C patients. Thus, perturbations in chemokine pathways in HIV-1/PTB patients may accelerate HIV-1 disease.     

Response to treatment and disease progression linked to CD4+ T cell surface CC chemokine receptor 5 density in human immunodeficiency virus type 1 vertical infection

The factors governing interindividual variability in disease progression among children vertically infected with human immunodeficiency virus type 1 (HIV-1) remain unclear. Because it has recently been shown in infected adults that the density of CC chemokine receptor 5 (CCR5) molecules at the surface of nonactivated (human leukocyte antigen [HLA]-DR(-)) CD4+ T cells correlates with disease progression, the same correlation was sought in children. HLA-DR(-)CD4+ T cell surface CCR5 density was constant over time and correlated with the bioclinical stage and with the CD4 cell slope observed before antiretroviral treatment. In addition, CCR5 density was negatively correlated with the intensity of the decrease in viremia during antiretroviral therapy and was positively correlated with CD4 cell slope since birth. These results are compatible with the hypothesis that CCR5 density is a key factor governing disease progression in pediatric HIV-1 infection and, thereby, an indicator of prognosis. Moreover, they suggest that therapies aimed at reducing CCR5 accessibility should slow down HIV disease evolution in children.     

Polymorphisms in the CCR5 promoter region influence disease progression in perinatally human immunodeficiency virus type 1-infected children

The effect of CC-chemokine receptor 5 (CCR5) promoter polymorphisms on the natural history of human immunodeficiency virus (HIV) disease was studied in 73 HIV-1-infected children. The CCR5(59338-59537) promoter haplotype, CCR5-59029A/G polymorphism, and CCR5Delta32 and CCR2-64I alterations were investigated. After exclusion of carriers of CCR5Delta32 or CCR2-64I, Kaplan-Meier analysis disclosed that children with the P1/P1(59353C,59356C,59402A) genotype progressed faster to disease than did children with other haplotypes (P=.016). When CCR2-64I carriers were included, this effect had borderline significance (P=.065) and was lost when CCR5Delta32 carriers were also considered (P=.387). The P1/P1 effect was strongest early after infection, when progression to disease was mainly associated with CCR5 coreceptor-using viruses. These results indicate that the P1/P1 genotype is predictive of rapid progression in HIV-1-infected children lacking CCR5Delta32 or CCR5-64I alleles. The observation of a linkage disequilibrium between P1 and 59029A might explain the previously reported association between 59029A homozygosity and rapid disease progression.     

Short communication: Influence of active tuberculosis on chemokine and chemokine receptor expression in HIV-infected persons

Tuberculosis (TB) is the major opportunistic infection of HIV-1-infected patients in developing countries. Concurrent infection with TB results in immune cells having enhanced susceptibility to HIV-1 infection, which facilitates entry and replication of the virus. Cumulative data from earlier studies indicate that TB provides a milieu of continuous cellular activation and irregularities in cytokine and chemokine circuits that favor viral replication and disease progression. To better understand the interaction of the host with HIV-1 during active tuberculosis, we investigated in vivo expression of the HIV-1 coreceptors, CCR5 and CXCR4, and circulating levels of the inhibitory beta-chemokines, macrophage inflammatory protein-1-alpha (MIP-1alpha), macrophage inflammatory protein-1-beta (MIP-1beta), and regulated upon activation T cell expressed and secreted (RANTES), in HIV-positive individuals with and without active pulmonary tuberculosis. We found a significant decrease from normal in the fraction of CD4+ T cells expressing CCR5 and CXCR4 in individuals infected with HIV. However, CCR5 and CXCR4 expression did not differ significantly between HIV patients with and without tuberculosis. Higher amounts of MIP-1alpha, MIP-1beta, and RANTES were detected in plasma of HIV-1-positive individuals, particularly those with dual infection, although the increase was not found to be statistically significant.     

Susceptibility of HIV type 2 primary isolates to CCR5 and CXCR4 monoclonal antibodies, ligands, and small molecule inhibitors

Human immunodeficiency virus (HIV) entry into susceptible cells involves the interaction between viral envelope glycoproteins with CD4 and a chemokine receptor (coreceptor), namely CCR5 and CXCR4. This interaction has been studied to enable the discovery of a new class of antiretroviral drugs that targets the envelope glycoprotein-coreceptor interaction. However, very few data exist regarding HIV-2 susceptibility to these coreceptor inhibitors. With this work we aimed to identify this susceptibility in order to assess the potential use of these molecules to treat HIV-2-infected patients and to further understand the molecular basis of HIV-2 envelope glycoprotein interactions with CCR5 and CXCR4. We found that CCR5-using HIV-2 isolates are readily inhibited by maraviroc, TAK-779, and PF-227153, while monoclonal antibody 2D7 shows only residual or no inhibitory effects. The anti-HIV-2 activity of CXCR4-targeted molecules reveals that SDF-1α/CXCL12 inhibited all HIV-2 tested except one, while mAb 12G5 inhibited the replication of only two isolates, showing residual inhibitory effects with all the other CXCR4-using viruses. A major conclusion from our results is that infection by HIV-2 primary isolates is readily blocked in vitro by maraviroc, at concentrations similar to those required for HIV-1. The susceptibility to maraviroc was independent of CD4(+) T cell counts or clinical stage of the patient from which the virus was obtained. These findings indicate that maraviroc could constitute a reliable therapeutic alternative for HIV-2-infected patients, as long as they are infected with CCR5-using variants, and this may have direct implications for the clinical management of HIV-2-infected patients.     

Chemokine receptor polymorphisms and human immunodeficiency virus disease progression.

The role of polymorphisms in genes encoding chemokines and their receptors (CCR2B, SDF-1, and the promoter region of CCR5) in human immunodeficiency virus (HIV) disease progression was studied in 132 white HIV type 1 (HIV-1)-infected participants from a United Kingdom cohort study. Genotyping was done by use of amplification refractory mutation system-polymerase chain reaction with sequence-specific primers, and Cox proportional hazards models were used to examine the impact of polymorphisms on time to a CD4 cell count <200x106/L and to CDC stage IV disease. The results confirm a significant association of the CCR2B-64I mutant genotype with slower progression to a CD4 count <200 (hazards ratio [HR], 0.39; 95% confidence interval [CI], 0.17-0.91) but not with the SDF-1alpha 3' UTR homozygous mutation. The effects of the CCR5 and CCR2 mutations were genetically independent and similar in the magnitude of their protective effect on progression to a CD4 count <200 cells. A novel finding was an association of borderline significance between homozygosity for C at nucleotide position 59353 in the CCR5 promoter region and a slower rate of CD4 cell decline to <200x106/L (HR, 0. 58; 95% CI, 0.34-0.996).     

Human immunodeficiency virus type 1 infection is associated with significant mucosal inflammation characterized by increased expression of CCR5, CXCR4, and beta-chemokines

Mucosal inflammation is characterized by increased expression of proinflammatory cytokines and chemoattractant chemokines, resulting in infiltration of immunocompetent cells. This study compared the degree of mucosal inflammation in human immunodeficiency virus type 1 (HIV-1)-infected gut mucosa with that in tissue samples from subjects with inflammatory bowel disease (IBD) and from healthy seronegative control subjects. Gut mucosal biopsy specimens were immunohistochemically stained and were evaluated by in situ imaging. There was significantly increased expression of HIV-1 coreceptors CCR5 and CXCR4, beta-chemokine RANTES, and macrophage inflammatory protein (MIP)-1alpha and MIP-1beta, as well as increased numbers of T cells in lamina propria of HIV-1-infected patients. The results were similar in patients with IBD and in HIV-1-infected patients, suggesting increased inflammation in the colon of HIV-1-infected patients. To further investigate the effect of inflammation in HIV-1-infected lamina propria, treatments that reduce immune activation in lamina propria must be evaluated.     

Interleukin-2 up-regulates expression of the human immunodeficiency virus fusion coreceptor CCR5 by CD4+ lymphocytes in vivo

Intermittent interleukin-2 (IL-2) therapy can substantially increase CD4+ T cell counts of human immunodeficiency virus (HIV)-infected subjects. Administration of IL-2 led to transient up-regulation of CCR5 on CD4+ T cells; up to 87% of CD4+ cells expressed CCR5 after a 5-day cycle, with return to baseline levels within 2 weeks. Unlike in vitro studies, CCR5 was coexpressed with CD45RA and CXCR4 on CD4+ T cells after IL-2 therapy. The observed increase in coreceptor expression was not associated with detectable increases in viral replication. IL-2 therapy induced CCR5 expression in >90% of circulating memory CD4+ T cells, determined to be a long-term reservoir of HIV, suggesting significant activation of these cells. These studies demonstrate that levels of expression of HIV coreceptors alone do not always correlate with HIV replication in vivo and that IL-2 therapy activates a majority of memory T cells in the circulation and likely throughout the immune system.     

Interclade neutralization and enhancement of human immunodeficiency virus type 1 identified by an assay using HeLa cells expressing both CD4 receptor and CXCR4/CCR5 coreceptors

We report on the development and evaluation of a human immunodeficiency virus (HIV) neutralization assay that uses P4P cells, which are CD4+CXCR4+CCR5+ HeLa cells that carry the lacZ gene under the control of the HIV-1 long terminal repeat. The results of the present study suggest that the P4P assay can be used for the extensive study of both neutralizing and enhancing activity in serum samples from HIV-1-infected patients and from vaccinated individuals.     

Multivalent anti-CCR ribozymes for stem cell-based HIV type 1 gene therapy

HIV-1 infection of susceptible cells is mediated by the specific interaction of viral envelope glycoproteins with the cell surface CD4 receptor and a chemokine coreceptor, CCR5 or CXCR4. Individuals with a CCR5 genetic defect show resistance to HIV-1 infection, indicating that downregulation of CCR5 expression on target cells can prevent viral infection. In previous studies we demonstrated the utility of an anti-CCR5 ribozyme targeted to a single cleavage site in downregulating CCR5 expression and consequently providing resistance to viral infection. To improve on the level of downregulation we designed a construct containing an anti-CCR5 ribozyme heterotrimer (R5RbzTM) targeted to three different cleavage sites in CCR5 mRNA. In vitro tests showed that the anti-CCR5 ribozyme heterotrimer could effectively cleave the CCR5 RNA substrates to yield products of the expected sizes. This construct was introduced into various retroviral vectors for stable gene transduction. HOS.CD4/R5 cells stably transduced with this anti-CCR5 heterotrimer showed a marked reduction in the surface expression of CCR5 and a concomitant 70% reduction in macrophage-tropic viral infection. In addition, a retroviral vector containing the anti-CCR5 ribozyme heterotrimer and an anti-HIV-1 tat-rev ribozyme heterodimer was constructed. This construct also showed a similar inhibition of CCR5 surface expression and reduced infectability by the macrophage-tropic HIV-1 vector in HOS.CD4/R5 cells. The trimeric and multimeric ribozyme constructs were transduced into CD34+ hematopoietic progenitor cells to determine their effects on lineage-specific differentiation. We show that multivalent ribozyme gene-transduced hematopoietic progenitors differentiated normally into mature macrophages that bear CD14 and CD4 surface markers. Macrophages containing the transgenes expressed ribozymes, and showed resistance to M-tropic HIV-1 infection. These results provide strong support for the use of the trimeric anti-CCR5 ribozyme approach in a gene therapy setting for the treatment of HIV infection.     

HIV-1 envelope-dependent restriction of CXCR4-using viruses in child but not adult untransformed CD4+ T-lymphocyte lines

Phytohemagglutin-stimulated child and adult leukocytes equally supported CCR5-dependent (R5) and CXCR4-dependent (X4) HIV-1 replication. In contrast, when phytohemagglutin-stimulated leukocytes from either healthy or congenitally immunodeficient children were cultured on feeder cells, they well supported R5, but not X4 HIV-1 replication, whereas both viruses equally spread in adult cells maintained in similar conditions. Both child and adult cells showed similar levels of proliferation and surface expression of CD4, CCR5, CXCR4, CD25, CD69, and HLA-DR. Lack of X4 HIV-1 replication in child versus adult cells was not caused by a differential expression of several known HIV-1 restriction factors. Similar levels of HIV DNA synthesis occurred in child cells infected with R5 and X4 viruses up to 48 hours after infection when R5 HIV-1 showed a significantly superior capacity to spread in culture than X4 virus. Cultured child cells well supported single round vescicular stomatitis virus-G pseudotyped virus replication, whereas superinfection of R5-infected cells with X4 HIV-1 (or vice versa) rescued the replication of this latter virus. Thus, child cells exposed to feeder cell culture represent a novel model system in which the superior capacity of R5 versus X4 viruses to spread can be investigated in primary, untransformed CD4(+) cells.     

Morphine exacerbates HIV-1 viral protein gp120 induced modulation of chemokine gene expression in U373 astrocytoma cells

HIV-1 affects microglia and astroglia, which subsequently contributes to the neurodegenerative changes. Viral proteins cause neurotoxicity by direct action on the CNS cells or by activating glial cells to cause the release of cytokines, chemokines or neurotoxic substances. Opioid abuse has been postulated as a cofactor in the immunopathogenesis of human immunodeficiency virus (HIV) infection and AIDS. HIV-induced pathogenesis is exacerbated by opiate abuse and that the synergistic neurotoxicity is a direct effect of opiates on the CNS. Chemokines and their receptors have been implicated in the pathogenesis of neuroAIDS. Herein we describe the effects of morphine and/or gp120 on the expression of the genes for the beta-chemokine MIP-1beta and its receptors CCR3 and CCR5 by the U373 cells which are a human brain-derived astrocytoma/glioblastoma cell line. Our results indicate that treatment of U373 cells with morphine significantly downregulated the gene expression of the beta chemokine, MIP-1 beta, while reciprocally upregulating the expression of its specific receptors, CCR3 and CCR5 suggesting that the capacity of mu-opioids to increase HIV-1 co-receptor expression may promote viral binding, trafficking of HIV-1-infected cells, and enhanced disease progression. Additionally, opiates can enhance the cytotoxicity of HIV-1 viral protein gp120 via mechanisms that involve intracellular calcium modulation resulting in direct actions on astroglia, making them an important cellular target for HIV-opiate interactions.     

Morphine promotes simian acquired immunodeficiency syndrome virus replication in monkey peripheral mononuclear cells: induction of CC chemokine receptor 5 expression for virus entry

Rhesus monkeys (Macaca mulatta) chronically administered opioids were more susceptible to simian immunodeficiency virus (SIV) strain mac239 (SIVmac239) infection than those without prior exposure to opioids. Increased plasma viremia in morphine-dependent monkeys allowed SIV to be detected in the animals' peripheral blood mononuclear cells (PBMC) without cocultivation with a tissue culture cell line. In contrast, virus titers from the PBMC of morphine-naive SIVmac239-infected animals were undetectable in the absence of cocultivation. PBMC isolated from noninfected animals and treated with morphine sulfate in vitro produced an increase in the expression of beta-chemokine receptor 5 (CCR5). Because both SIVmac239 and human immunodeficiency virus (HIV) require CCR5 for cell entry, the unique role of morphine in promoting SIV infection may provide a mechanism to account for the high incidence of HIV disease among drug-using populations.     

Natural history of primary Epstein-Barr virus infection in children of mothers infected with human immunodeficiency virus type 1

The natural history of Epstein-Barr virus (EBV) infection in 556 infants born to 517 human immunodeficiency virus (HIV) type 1-infected mothers was studied in a prospective, multicenter, cohort study. HIV-1-infected children had a cumulative EBV infection rate similar to HIV-1-uninfected children at age 3 years (77.8% vs. 84. 9%) but had more frequent oropharyngeal EBV shedding (50.4% vs. 28. 2%; P<.001). The probability of shedding decreased with longer time from EBV seroconversion and was similar to that of HIV-1-uninfected children 3 years after seroconversion. HIV-1-infected children identified as rapid progressors shed EBV more frequently than nonrapid progressors (69.4% vs.41.0%; P=.01). HIV-1-infected children with EBV infection had higher mean CD8 cell counts. EBV infection did not have an independent effect on mean CD4 cell counts, percent CD4, IgG levels, HIV-1 RNA levels, lymphadenopathy, hepatomegaly, or splenomegaly. Early EBV infection is common in children born to HIV-1-infected mothers. Children with rapidly progressive HIV-1 disease have more frequent EBV shedding.