Differential expression of chemokine receptors in B cell malignancies

Chemokines are a family of 8-10 kDa proteins with a wide range of biological activities including the regulation of leukocyte trafficking, modulation of haemopoietic cell proliferation and adhesion to extracellular matrix molecules. Using a panel of chemokine receptor-specific monoclonal antibodies (MoAb) in a multicolour flow cytometry approach we analysed the expression of the lymphocyte-associated chemokine receptors CXCR4, CXCR5, CCR5 and CCR6 in B cell acute lymphoblastic leukaemia (precursor B-ALL; six cases), B cell chronic lymphocytic leukaemia (B-CLL; 31 cases), multiple myeloma (10 cases), mantle cell lymphoma (MCL, four cases), follicular lymphoma (FL, three cases) and hairy cell leukaemia (HCL, five cases). We demonstrate that CXCR4, CXCR5 and CCR6 are differentially expressed in these B lymphoproliferative disorders depending on the maturational stage of the malignant B cell population investigated. In particular, we found that CXCR4 is strongly expressed on immature ALL blasts whereas no surface immunoreactivity for CXCR5, CCR5 and CCR6 was observed. By contrast, non-Hodgkin's lymphomas (NHLs) corresponding to more mature peripheral B cell subsets (ie B-CLL and MCL) exhibited high expression levels of CXCR4 and CXCR5. Analysis of terminally differentiated myeloma cells revealed a down-regulation of CXCR4, CXCR5 and CCR6. CCR5, which is not expressed in normal B cells, was also absent from the majority of NHLs. However, CCR5 staining was seen in three of five cases of HCL, representing the first example of cross-lineage aberrant chemokine receptor expression in malignant haemopoietic cells.

Cervical and prostate primary epithelial cells are not productively infected but sequester human immunodeficiency virus type 1

Primary prostate and cervical epithelial cells and epithelial cell lines were examined for human immunodeficiency virus type 1 (HIV-1) infection or transmission to peripheral blood mononuclear cells (PBMC). Neither cell-free nor cell-associated HIV-1 infected primary epithelial cells or cell lines. Pretreatment of HIV-1 to enhance CD4-independent entry did not augment infection. Cell surface expression was detected for galactosyl ceramide but not for CC-chemokine receptor 5, CXC-chemokine receptor 4, or CD4. The ability to transfer HIV-1 to resting or activated PBMC was tested by culturing with rinsed or trypsinized and replated HIV-1-exposed epithelial cells. Virus was not recovered from the rinsed or replated cocultures with resting PBMC; however, activated PBMC recovered HIV-1 from rinsed epithelial cells and rarely from replated epithelial cells. Although urogenital epithelial cells are not infected, these data suggest that they can transfer virus to activated immune cells and have implications for sexual transmission of HIV-1.

Duration of sample storage dramatically alters expression of the human immunodeficiency virus coreceptors CXCR4 and CCR5

Expression of the chemokine receptors CXCR4 and CCR5 was monitored using EDTA-anticoagulated whole blood held for different time periods prior to fluorescent-antibody staining. When left overnight CXCR4 expression on leukocytes was substantially increased, whereas CCR5 expression was reduced. The results were similar when heparin and acid-citrate-dextrose were used as anticoagulants.

Determination of coreceptor usage of human immunodeficiency virus type 1 from patient plasma samples by using a recombinant phenotypic assay

We developed a recombinant virus technique to determine the coreceptor usage of human immunodeficiency virus type 1 (HIV-1) from plasma samples, the source expected to represent the most actively replicating virus population in infected subjects. This method is not subject to selective bias associated with virus isolation in culture, a step required for conventional tropism determination procedures. The addition of a simple subcloning step allowed semiquantitative evaluation of virus populations with a different coreceptor (CCR5 or CXCR4) usage specificity present in each plasma sample. This procedure detected mixtures of CCR5- and CXCR4-exclusive virus populations as well as dualtropic viral variants, in variable proportions. Sequence analysis of dualtropic clones indicated that changes in the V3 loop are necessary for the use of CXCR4 as a coreceptor, but the overall context of the V1-V3 region is important to preserve the capacity to use CCR5. This convenient technique can greatly assist the study of virus evolution and compartmentalization in infected individuals.

CXCR3 and CCR5 ligands in rheumatoid arthritis synovium

The pathogenesis of rheumatoid arthritis (RA) may be mediated by Th1-type T cells. Since chemokine receptors CXCR3 and CCR5 are preferentially expressed on Th1 cells, we tested the expression and regulation of several chemokines, including those that signal through CXCR3 (interferon-gamma-inducible protein of 10 kDa, IP-10, CXCL10; and monokine induced by interferon-gamma, Mig, CXCL9) and CCR5 (macrophage inflammatory protein (Mip)-1 alpha, CCL3; and Mip-1 beta, CCL4) in RA synovial fluids, synovial tissues, and blood. Synovial fluid (SF) protein levels of IP-10 (32.1 +/- 10.5 ng/ml), Mig (15.0 +/- 6.4 ng/ml), Mip-1 beta (0.7 +/- 0.3 ng/ml), and Mip-1 alpha (0.8 +/- 0.1 ng/ml) were 100-, 50-, 25-, and 2-fold elevated in RASF compared to control SF (P < 0.001, P < 0.001, P < 0. 001, and P < 0.02, respectively). Tissue levels of IP-10, Mig, and Mip-1 beta were significantly higher in RA than in OA (P < 0.01). Serum levels of IP-10 (3.1 +/- 1.2 ng/ml) were higher in patients with seropositive RA compared to controls (1.2 +/- 0.2 ng/ml) (P < 0.02). There was a gradient of IP-10, Mig, Mip-1 alpha, and Mip-1 beta from the blood into the synovial fluid in RA. Infiltrating T cells around high endothelial venules in RA synovium and 90 +/- 3% of SF CD3(+)CD4(+) T cells expressed CXCR3, and 85 +/- 2% of SF CD3(+)CD4(+) T cells expressed CCR5. Chemokines, including IP-10, Mig, Mip-1 alpha, and Mip-1 beta, may participate in the selective recruitment of CCR5(+)CXCR3(+) T cells to the inflamed synovium.

Differential susceptibility of resting CD4(+) T lymphocytes to a T-tropic and a macrophage (M)-tropic human immunodeficiency virus type 1 is associated with their surface expression of CD38 molecules

Recent evidence has accumulated which definitively shows that chemokine receptors CCR5 and CXCR4 play an essential role as coreceptors for human immunodeficiency virus type 1 (HIV-1) infection. Flow cytometric analysis permitted us to detect CD38, a surface marker of early differentiation, as well as activation of T cells, on about half of healthy donor-derived CD4(+) T cells. In this study, we focused on the susceptibility of CD38(+) and CD38(-) subsets of CD4(+) T cells to HIV-1 infection with different coreceptor tropisms. About 20% of peripheral blood mononuclear cell-derived resting CD4(+) T cells were recovered into the CD38(+) subset fraction by panning with a monoclonal antibody to CD38. Most of the cells in this CD38(high) fraction also expressed CD45RA and CD62L at higher intensities compared with those of CD38(low) fraction. CCR5(+) T cells predominated in the CD38(-) subset, although cell surface expression of CD4 and CXCR4 was almost similar between both subsets. This difference was consistent with a significantly higher susceptibility of the CD38(-) subset to a macrophage (M)-tropic HIV-1 strain. In contrast, it was shown that a T-tropic strain of HIV-1 could replicate more efficiently in the CD38(+) subset, although viral adsorption rates were similar between both subsets. Thus, the differential susceptibility of CD4(+) T cells to M(-) and T-tropic HIV-1 was associated with their surface expression of CD38.

Ultrasensitive magnetic biosensor for homogeneous immunoassay

A technique is described for specific, sensitive, quantitative, and rapid detection of biological targets by using superparamagnetic nanoparticles and a "microscope" based on a high-transition temperature dc superconducting quantum interference device (SQUID). In this technique, a mylar film to which the targets have been bound is placed on the microscope. The film, at room temperature and atmospheric pressure, is typically 40 micrometer from the SQUID, which is at 77 K in a vacuum. A suspension of magnetic nanoparticles carrying antibodies directed against the target is added to the mixture in the well, and 1-s pulses of magnetic field are applied parallel to the SQUID. In the presence of this aligning field the nanoparticles develop a net magnetization, which relaxes when the field is turned off. Unbound nanoparticles relax rapidly by Brownian rotation and contribute no measurable signal. Nanoparticles that are bound to the target on the film are immobilized and undergo Néel relaxation, producing a slowly decaying magnetic flux, which is detected by the SQUID. The ability to distinguish between bound and unbound labels allows one to run homogeneous assays, which do not require separation and removal of unbound magnetic particles. The technique has been demonstrated with a model system of liposomes carrying the FLAG epitope. The SQUID microscope requires no more than (5 +/- 2) x 10(4) magnetic nanoparticles to register a reproducible signal.

The level of CD4 expression limits infection of primary rhesus monkey macrophages by a T-tropic simian immunodeficiency virus and macrophagetropic human immunodeficiency viruses

The entry of primate immunodeficiency viruses into cells is dependent on the interaction of the viral envelope glycoproteins with receptors, CD4, and specific members of the chemokine receptor family. Although in many cases the tropism of these viruses is explained by the qualitative pattern of coreceptor expression, several instances have been observed where the expression of a coreceptor on the cell surface is not sufficient to allow infection by a virus that successfully utilizes the coreceptor in a different context. For example, both the T-tropic simian immunodeficiency virus (SIV) SIVmac239 and the macrophagetropic (M-tropic) SIVmac316 can utilize CD4 and CCR5 as coreceptors, and both viruses can infect primary T lymphocytes, yet only SIVmac316 can efficiently infect CCR5-expressing primary macrophages from rhesus monkeys. Likewise, M-tropic strains of human immunodeficiency virus type 1 (HIV-1) do not infect primary rhesus monkey macrophages efficiently. Here we show that the basis of this restriction is the low level of CD4 on the surface of these cells. Overexpression of human or rhesus monkey CD4 in primary rhesus monkey macrophages allowed infection by both T-tropic and M-tropic SIV and by primary M-tropic HIV-1. By contrast, CCR5 overexpression did not specifically compensate for the inefficient infection of primary monkey macrophages by T-tropic SIV or M-tropic HIV-1. Apparently, the limited ability of these viruses to utilize a low density of CD4 for target cell entry accounts for the restriction of these viruses in primary rhesus monkey macrophages.

Immunohistochemical analysis of CCR2, CCR3, CCR5, and CXCR4 in the human brain: potential mechanisms for HIV dementia

The CXC chemokine receptor CXCR4 was the first molecule identified as a coreceptor working in conjunction with CD4 to mediate cellular entry for the human immunodeficiency virus (HIV-1). Since that original discovery, 11 other seven-mtransmembrane domain molecules, many of which are chemokine receptors, have been shown to facilitate HIV entry into cells. These include CCR5, CCR3, CCR2, CCR1, CCR8, CX3CR1, STRL33 (BONZO), GPR15 (BOB), GPR1, US28, and APJ. In studies done by this and other labs, CCR3, CCR5, and CXCR4 have been identified in CNS microglia and several laboratories, including ours, have shown that CXCR4 is expressed in neurons. Neuronal expression of CCR2, CCR3, and CCR5 has been less consistent. We performed a semiquantitative immunohistochemical analysis of the expression of CCR2, CCR3, CCR5, and CXCR4 in 23 regions of the brain and in two sections of the spinal cord. Hippocampal neurons were positive for CCR2, CCR3, and CXCR4, but not for CCR5. In other regions of the brain, neurons, and glial cells reacted with anti-CCR2, anti-CCR3, and anti-CXCR4 antibodies, whereas only glial cells (primarily microglia) were positive for CCR5. The areas of highest expression, however, seem to be subcortical regions and the limbic system. The limbic system plays a key role in memory, and the presence of CXCR4-which can bind the viral envelope protein gp120-min a subset of neurons from this system may play a role in the development of HIV-related dementia.

Dynamics of CCR5 expression by CD4(+) T cells in lymphoid tissues during simian immunodeficiency virus infection

Early viral replication and profound CD4(+) T-cell depletion occur preferentially in intestinal tissues of macaques infected with simian immunodeficiency virus (SIV). Here we show that a much higher percentage of CD4(+) T cells in the intestine express CCR5 compared with those found in the peripheral blood, spleen, or lymph nodes. In addition, the selectivity and extent of the CD4(+) T-cell loss in SIV infection may depend upon these cells coexpressing CCR5 and having a "memory" phenotype (CD45RA(-)). Following intravenous infection with SIVmac251, memory CD4(+) CCR5(+) T cells were selectively eliminated within 14 days in all major lymphoid tissues (intestine, spleen, and lymph nodes). However, the effect on CD4(+) T-cell numbers was most profound in the intestine, where cells of this phenotype predominate. The CD4(+) T cells that remain after 14 days of infection lacked CCR5 and/or were naive (CD45RA(+)). Furthermore, when animals in the terminal stages of SIV infection (with AIDS) were examined, virtually no CCR5-expressing CD4(+) T cells were found in lymphoid tissues, and all of the remaining CD4(+) T cells were naive and coexpressed CXCR4. These findings suggest that chemokine receptor usage determines which cells are targeted for SIV infection and elimination in vivo.

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.

CCR5 and beta-chemokines in HIV-1 infected children

The duration from initial infection with HIV-1 to CD4 lymphocyte depletion and progression to AIDS varies among infected individuals. Despite treatment with highly active antiretroviral therapy (HAART), patients still show different stages of disease progression. We examined the role of beta-chemokines and its receptor, CCR5 in HIV-1 infected children in order to define determinants of HIV progression among treated individuals. Population was divided in two groups: Group 1--Long Term Non Progressors (LTNP) includes 10 patients with B1-B2 CDC disease classification and with a less aggressive therapy (only 2 in HAART); Group 2--Rapid Progressors (RP) includes 9 patients with C3 disease classification. All the patients had a CCR5 wild type (wt) genotype indicating that they do not have the 32 base-pair deletion associated with slower progression. There was an increased production of MIP 1-beta in 8/10 LTNP but only in 4/9 Progressors (Paired t-test/Wilcoxon Sign test, p-value < 0.05). The change in the levels of MIP-1 beta after PHA stimulation was statistically significant in both groups. The levels of RANTES increased in LTNP and RP and the change of the levels after mitogen stimulation was statistically significant for both groups included. The production of RANTES and MIP-1 beta in response to stimulation between both groups was not statistically significant. The production of MIP-1 alpha was variable in both groups and the difference in the levels after mitogen stimulation between the groups was not statistically significant. These results suggest that beta-chemokines do not play an important role in HIV-1 progression in children undergoing HAART.

Mono Mac 1: a new in vitro model system to study HIV-1 infection in human cells of the mononuclear phagocyte series

Throughout the years, most researchers have used continuous cell lines as in vitro models to evaluate the immunopathogenesis of human immunodeficiency virus type-1 (HIV-1) infection. Unfortunately, the most commonly used monocytoid malignant cells have not been shown to adequately mimic primary human monocyte-derived macrophages, at least with respect to HIV-1 infection. The Mono Mac 1 cell line has been defined as a model system for studying biochemical, immunological, and genetic functions of human cells of the monocyte/macrophage lineage. In this study, we have investigated whether Mono Mac 1 represents an in vitro culture system for HIV-1 infection. Flow cytometric analyses revealed that Mono Mac 1 are positive for the HIV-1 primary receptor (CD4), as well as for the coreceptors (CXCR4, CCR5, and CCR3). Infectivity experiments conducted with recombinant luciferase-encoding and fully infectious viruses demonstrated that Mono Mac 1 can support a highly productive infection with both macrophage- and dual-tropic isolates of HIV-1. Furthermore, differentiation of such cells led to a marked increase in virus production. Data from semiquantitative polymerase chain reaction analysis and mobility shift assays indicated that enhanced virus production in differentiated Mono Mac 1 cells was most likely related to an increase in nuclear translocation of NF-kappaB. Mono Mac 1 can thus be considered as a human monocytoid cell line representing a proper in vitro system for studying the complex interactions between HIV-1 and cells of the monocyte/macrophage lineage.

Intrinsic susceptibility of rhesus macaque peripheral CD4(+) T cells to simian immunodeficiency virus in vitro is predictive of in vivo viral replication

Previous studies with simian immunodeficiency virus (SIV) infection of rhesus macaques suggested that the intrinsic susceptibility of peripheral blood mononuclear cells (PBMC) to infection with SIV in vitro was predictive of relative viremia after SIV challenge. The present study was conducted to evaluate this parameter in a well-characterized cohort of six rhesus macaques selected for marked differences in susceptibility to SIV infection in vitro. Rank order relative susceptibility of PBMC to SIVsmE543-3-infection in vitro was maintained over a 1-year period of evaluation. Differential susceptibility of different donors was maintained in CD8(+) T-cell-depleted PBMC, macrophages, and CD4(+) T-cell lines derived by transformation of PBMC with herpesvirus saimiri, suggesting that this phenomenon is an intrinsic property of CD4(+) target cells. Following intravenous infection of these macaques with SIVsmE543-3, we observed a wide range in plasma viremia which followed the same rank order as the relative susceptibility established by in vitro studies. A significant correlation was observed between plasma viremia at 2 and 8 weeks postinoculation and in vitro susceptibility (P < 0.05). The observation that the two most susceptible macaques were seropositive for simian T-lymphotropic virus type 1 may suggests a role for this viral infection in enhancing susceptibility to SIV infection in vitro and in vivo. In summary, intrinsic susceptibility of CD4(+) target cells appears to be an important factor influencing early virus replication patterns in vivo that should be considered in the design and interpretation of vaccine studies using the SIV/macaque model.

Identification of gp120 regions targeted by a highly potent neutralizing antiserum elicited in a chimpanzee inoculated with a primary human immunodeficiency virus type 1 isolate

We have previously reported that a chimpanzee infected with a primary human immunodeficiency virus type 1 (HIV-1) isolate (HIV-1(DH12)) developed an extremely potent virus-neutralizing antibody. Immunoglobulin G purified from this animal conferred sterilizing immunity following passive transfer to macaques which were subsequently challenged with simian immunodeficiency virus/HIV-1 chimeric virus strain DH12. In addition to being highly strain specific, the chimpanzee antiserum did not bind to the V3 loop peptide of HIV-1(DH12), nor did it block the interaction of gp120 with the CD4 receptor. When neutralization was examined in the context of virus particles carrying chimeric envelope glycoproteins, the presence of all five hypervariable regions (V1 to V5) was required for optimal neutralization. Virions bearing chimeric gp120 containing the V1-V2 and V4 regions of HIV-1(DH12) could also be neutralized, but larger quantities of the chimpanzee antiserum were needed to block infection. These results indicate that the HIV-1 gp120 epitope(s) targeted by the chimpanzee antiserum is highly conformational, involving surface elements contributed by all of the hypervariable domains of the envelope glycoprotein.

Immune activation in africa is environmentally-driven and is associated with upregulation of CCR5. Italian-Ugandan AIDS Project

BACKGROUND

HIV infection in Africa is associated with immune activation and a cytokine profile that stimulates CCR5 expression. We investigated whether this immune activation is environmentally driven; if a dominant expression of CCR5 could indeed be detected in African individuals; and if R5 HIV strains would be prevalent in this population.

METHODS

Freshly drawn peripheral blood mononuclear cells from HIV-uninfected African and Italian individuals living in rural Africa, from HIV-uninfected Africans and Italians living in Italy, and from HIV-infected African and Italian patients were analysed. Determinations of HIV coreceptor-specific mRNAs and immunophenotype analyses were performed in all samples. Virological analyses included virus isolation and characterization of plasma neutralizing activity.

FINDINGS

Results showed that: immune activation is detected both in Italian and African HIV-uninfected individuals living in Africa but not in African subjects living in Italy; CCR5-specific mRNA is augmented and the surface expression of CCR5 is increased in African compared with Italian residents (CXCR4-specific mRNA is comparable); R5-HIV strains are isolated prevalently from lymphocytes of African HIV-infected patients; and plasma neutralizing activity in HIV-infected African patients is mostly specific for R5 strains.

CONCLUSIONS

Immune activation in African residents is environmentally driven and not genetically predetermined. This immune activation results in a skewing of the CCR5 : CXCR4 ratio which is associated with a prevalent isolation of R5 viruses. These data suggest that the selection of the predominant virus strain within the population could be influenced by an immunologically driven pattern of HIV co receptor expression.

Adenoids provide a microenvironment for the generation of CD4(+), CD45RO(+), L-selectin(-), CXCR4(+), CCR5(+) T lymphocytes, a lymphocyte phenotype found in the middle ear effusion

Adenoidectomy in children with otitis media with effusion reduces inflammation in the middle ear by an unknown mechanism. Potentially, the adenoids of these children may serve as a site for the differentiation of lymphocytes, which after entering blood circulation eventually extravasate in the middle ear mucosa and thereby contribute to excessive inflammation. During lymphocyte extravasation various adhesion molecules and chemokines play a crucial role. To evaluate possible connections between the adenoids and middle ear inflammation, the expression of the chemokine receptors CXCR4 and CCR5 and the lymphocyte homing receptor L-selectin were analyzed in adenoidal and middle ear lymphocytes. It was found that most CD4(+) T lymphocytes in the middle ear effusion express the memory phenotype marker CD45RO and the chemokine receptors CXCR4 and CCR5, but are negative for the lymphocyte homing receptor L-selectin. This cell phenotype was rare in peripheral blood but was found much more frequently in the adenoids. The results suggest that the adenoids provide a microenvironment for the generation for CD4(+), CD45RO(+), L-selectin(-), CXCR4(+) and CCR5(+) T lymphocytes. Further, these cells may include cells that have the capacity to home to the middle ear mucosa. As the adenoidal CD4(+) memory phenotype CD45RO(+) T cells expressed the activation antigen CD69 and included cells expressing the HIV co-receptors CXCR4 and CCR5 at a high level, they may be permissive for HIV infection.

Influence of nucleotide polymorphisms in the CCR2 gene and the CCR5 promoter on the expression of cell surface CCR5 and CXCR4

Polymorphisms in the CCR2 gene (CCR2-64I) and the CCR5 promoter (pCCR5-59029G) have been correlated with slower HIV-1 disease progression. How these polymorphisms influence the rate of AIDS progression has remained unclear. We have therefore investigated whether these nucleotide polymorphisms will reduce the expression levels of surface CCR5 and CXCR4, and thus lead to slower AIDS progression. For this, a cohort of Chinese volunteers in Taiwan was subjected to the determination of CCR2 and pCCR5 genotypes followed by analysis of the surface CCR5 and CXCR4 expression on five cell types derived from peripheral blood mononuclear cells by flow cytometry. Several significant associations were detected between genotypes and expression levels of the proteins. The most important finding was that an increased number of CD4(+) cells expressing CCR5 correlated with pCCR5-59029A homozygosity without the interference of both the CCR2-64 and the CCR5 delta 32 (deleted 32 bp) mutations (P: = 0.0453), which is consistent with the previous data on the association of the genotype to AIDS progression. Since different genetic polymorphisms co-exist in human beings, the rate of AIDS progression as well as the risk of rheumatoid arthritis may be governed by the interplay of the array of nucleotide changes and their affected proteins.

High levels of IL-10 and determination of other cytokines and chemokines in HIV-associated haemophagocytic syndrome

Haemophagocytic syndrome (HPS) and HIV infection are both associated with cytokine network dysregulation. We therefore analysed plasma levels and mRNA synthesis in peripheral blood mononuclear cells (PBMC) of cytokines, chemokines and chemokine receptors in one HIV-infected patient with HPS. We compared the results with those for eight HIV-infected patients with similar CD4+ T cell counts (207/mm3 versus controls: median 214/mm3) and plasma virus load (4.1 log copies/ml, versus controls: median 4.2 log copies/ml). The HPS patient had a lower viral DNA load in PBMC and higher plasma levels of interferon-gamma, IL-10, and macrophage inflammatory protein (MIP)-1beta. No difference in plasma tumour necrosis factor-alpha (TNF-alpha), IL-6 and MIP-1alpha concentration was observed between the HPS patient and control patients. No difference was observed in TNF-alpha, IL-1beta, IL-10, IL-4, MIP-1alpha, MIP-1beta, RANTES, CXCR-4, and CCR-5 mRNA levels in PBMC, but IL-6 levels were higher in the HPS patient. Our results emphasize the role of IL-10 in the control of immune hyperactivation that is observed in HPS.

Expression of the beta-chemokine receptors CCR2, CCR3 and CCR5 in multiple sclerosis central nervous system tissue

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS) characterised by perivascular inflammatory cell infiltrates and plaques of demyelination. Chemokines have been shown to play an important role in the activation and directional migration of cells to sites of CNS inflammation. The action of chemokines requires the expression of their complementary chemokine receptors by their target cells. We have examined the expression of the beta-chemokine receptors CCR2, CCR3 and CCR5 in post-mortem MS CNS tissue using single- and double-labelling immunocytochemistry techniques. Low levels of CCR2, CCR3 and CCR5 were expressed by microglial cells throughout control CNS tissue. In chronic active MS lesions CCR2, CCR3 and CCR5 were associated with foamy macrophages and activated microglia. CCR2 and CCR5 were also present on large numbers of infiltrating lymphocytes. A smaller number of CCR3-positive lymphocytes were present, but we also noted CCR3 and CCR5 on astrocytes in five of the 14 cases of MS investigated, particularly associated with processes around vessels and at the glia limitans. Ligands for CCR2 and CCR3 include MCP-1 and MCP-3 which were co-localised around vessels with the infiltrating leukocytes, but were also present in unaffected areas of cortex. The elevated expression of CCR2, CCR3 and CCR5 in the CNS in MS suggests these beta-chemokine receptors and their ligands play a role in the pathogenesis of MS.

Expression pattern of T-cell-associated chemokine receptors and their chemokines correlates with specific subtypes of T-cell non-Hodgkin lymphoma

Chemokine receptors mediate the migration of lymphocytes through the binding of soluble ligands, and their expression is differentially regulated in lymphocyte subsets. The pattern of chemokine receptor expression in T-cell non-Hodgkin lymphoma has not been previously studied. Using a panel of mouse monoclonal antibodies, we studied the immunohistochemical expression of the Th1-associated chemokine receptor CXCR3 in 141 patients with T-cell lymphoma, and we studied the receptors CCR4 and CCR5 and some of their ligands in a subset of these tumors. Expression of CXCR3 was typical of the smaller T cells in angioimmunoblastic lymphoma (15 of 18 patients), angiocentric lymphoma (3 of 3 patients), histiocyte-rich tumors (4 of 5 patients), and unspecified T-cell lymphomas (17 of 39 patients). CXCR3 expression was seen in only 1 of 15 patients with anaplastic lymphoma kinase (ALK)-positive anaplastic large-cell lymphoma. In contrast, all ALK-positive tumors showed diffuse reactivity for the Th2-associated receptor CCR4 (5 of 5 patients). CCR4 expression was also a consistent feature of the large-cell transformation of mycosis fungoides. CCR5 expression showed no consistent association with any T-cell tumor type. The chemokines Mig (CXCR3 ligand), TARC (CCR4 ligand), and MCP-2 (CCR5 ligand) were detected in intratumoral blood vessels and histiocytes. Mig was also coexpressed by a subset of CXCR3-positive tumor cells in 6 of 20 lymphomas. MCP-2 was highly expressed in stromal cells in 3 patients with nodal involvement by cutaneous T-cell lymphoma. As with normal T-cell subsets, we demonstrated that there is frequent differential expression of chemokine receptors in T-cell tumors, which may explain, in part, the distinctive patterns of spread in different tumor subtypes. (Blood. 2000;96:685-690)

Thalidomide suppresses Up-regulation of human immunodeficiency virus coreceptors CXCR4 and CCR5 on CD4+ T cells in humans

Concurrent infection in patients with human immunodeficiency virus (HIV) infection increases the expression of HIV coreceptors CXCR4 and CCR5. Thalidomide has beneficial effects in a number of HIV-associated diseases. The effect of thalidomide on CXCR4 and CCR5 expression on CD4+ T cells was determined. Thalidomide produced a dose-dependent inhibition of lipopolysaccharide (LPS)-induced up-regulation of CXCR4 and CCR5 in vitro. Antibody to tumor necrosis factor-alpha (TNF-alpha) also attenuated the LPS-induced HIV coreceptor up-regulation, which was not further reduced by thalidomide. Thalidomide (400 mg) was orally administered to 6 men, and their blood was stimulated ex vivo with LPS, staphylococcal or mycobacterial antigens, or antibody to CD3 or CD28 cells. All stimuli induced up-regulation of HIV coreceptors, which was reduced after ingestion of thalidomide. Thalidomide may be beneficial in the treatment of intercurrent infections during HIV infection by reducing the up-regulation of CXCR4 and CCR5 expression on CD4+ T cells induced by bacterial and mycobacterial antigens, by a mechanism that involves inhibition of TNF-alpha.

Productive human immunodeficiency virus-1 infection of epithelial cell lines of salivary gland origin

To ascertain whether epithelial cells of oral cavity origin may be infected with human immunodeficiency virus (HIV-1), a study to determine susceptibility to infection of salivary gland epithelial cell lines (HSY and HSG) was undertaken. Because of the potential for oral-genital transmission, an endometrial cell line, HEC-1, was also studied. Epithelial cell monolayers were infected with cell-free HTLVIIIB or a primary HIV-1 isolate. Several lines of evidence indicated that inoculation of these cell lines with HIV-1 led to productive infection: 1) p24 antigen was present in supernatants, with levels peaking on days 3-4; 2) provirus was found in cells by polymerase chain reaction; 3) virions present in supernatants were infectious as confirmed by coculture with the T-lymphoblastoid line CEM-NKr. Following a period of virus production, HIV-1 entered a latency phase over 10 weeks. All epithelial cell lines were positive for galactosylceramide (GalC) and CXCR4. HSY was weakly positive for surface CD4, and also expressed mRNA for CD4 and CCR5, as did HEC-1. Blocking studies indicated that anti-GalC, but not anti-CD4, significantly reduced productive infection, and that regulated on activation normal T cell expressed and secreted (RANTES) but not stromal cell-derived factor (SDF-1) could partially block infection of the M-tropic primary isolate. These results suggest that epithelial cells in the oral cavity and the genital tract might be targets of HIV-1 and potentially serve as a mediator of systemic infection.

Wavelet change-point prediction of transmembrane proteins

MOTIVATION

A non-parametric method, based on a wavelet data-dependent threshold technique for change-point analysis, is applied to predict location and topology of helices in transmembrane proteins. A new propensity scale generated from a transmembrane helix database is proposed.

RESULTS

We show that wavelet change-point performs well for smoothing hydropathy and transmembrane profiles generated using different scales. We investigate which wavelet bases and threshold functions are overall most appropriate to detect transmembrane segments. Prediction accuracy is based on the analysis of two data sets used as standard benchmarks for transmembrane prediction algorithms. The analysis of a test set of 83 proteins results in accuracy per segment equal to 98.2%; the analysis of a 48 proteins blind-test set, i.e. containing proteins not used to generate the propensity scales, results in accuracy per segment equal to 97.4%. We believe that this method can also be applied to the detection of boundaries of other patterns such as G + Cisochores and dot-plots.

AVAILABILITY

The transmembrane database, TMALN and source code are available upon request from the authors.

Global distribution of the CCR2-64I/CCR5-59653T HIV-1 disease-protective haplotype

OBJECTIVES

Several natural polymorphisms in the genes for the human CC-chemokine receptors CCR5 and CCR2 are associated with HIV-1 disease. The CCR2-64I genetic variant [a G to A substitution resulting in a valine (V) to isoleucine (I) change at position 64] is in strong linkage disequilibrium with a mutation within the CCR5 regulatory region (CCR5-59653T). Individuals with two CCR2-64I alleles are not resistant to sexual transmission of HIV-1, but progress significantly more slowly to HIV-1 disease. It is therefore important to determine the global distributions of CCR2-64I and CCR5-59653T genetic variants and define the degree of linkage between them.

DESIGN AND METHODS

We have developed molecular beacon-based, real-time PCR allele discrimination assays for all three chemokine receptor mutations, and used these spectral genotyping assays to genotype 3923 individuals from a globally distributed set of 53 populations.

RESULTS

CCR2-64I and CCR5-59653T genetic variants are found in almost all populations studied: their allele frequencies are greatest (approximately 35%) in Africa and Asia but decrease in Northern Europe. We confirm that CCR2-64I is in strong linkage disequilibrium with CCR5-59653T (96.92% of individuals had the same genotype for both CCR2-64I and CCR5-59653T polymorphisms).

CONCLUSIONS

The greater geographical distribution of the CCR2-64I/CCR5-59653T haplotype compared with that of CCR5-delta32 suggests that it is a much older mutation whose origin predates the dispersal of modern humans.

Productive infection of CD34+-cell-derived megakaryocytes by X4 and R5 HIV-1 isolates

The human immunodeficiency virus (HIV-1) causes various hematopoietic abnormalities, with thrombocytopenia (TP) occurring in 30% of infected individuals. In the present study, we aimed to determine whether HIV-1 in the bone marrow of TP patients can infect primary megakaryocytes in vitro, which may contribute to the development of thrombocytopenia. We amplified the V3 loop of HIV-1 envelope from the bone marrow of TP and non-TP patients and constructed recombinant viruses. We demonstrate that the bone marrow of TP and non-TP patients contained R5 strains, whereas X4 strains were present only in the bone marrow of TP patients. Furthermore, HIV-1 from the bone marrow of TP and non-TP patients infected megakaryocytes to similar levels, suggesting that the V3 loop of HIV-1 may not contain the viral determinants of HIV-associated TP. Chemokine receptor analysis determined that CD34+-cell-derived megakaryocytes express CD4, CXCR4, and CCR5 and are productively infected by both X4 and R5 HIV-1 isolates. Finally, we showed that CD34+-cell-derived megakaryocytes express the chemokine receptor CCR3.

CD4+ T cell surface CCR5 density as a determining factor of virus load in persons infected with human immunodeficiency virus type 1

The intensity of expression of the chemokine receptor CCR5 is involved in in vitro cell infectability by human immunodeficiency virus (HIV)-1 R5 isolates. Because CCR5 expression varies among individuals, the hypothesis that this expression could determine virus load in HIV-1-infected persons was tested. The mean number of CCR5 molecules per cell was measured on peripheral blood CD4+ T lymphocytes (CCR5 density) from HIV-1-infected, asymptomatic, nontreated adults. There was a strong correlation between HIV RNA plasma level and CCR5 density (P=.009) that was independent of cell activation and was not due to an HIV-induced CCR5 up-regulation. These data are compatible with the hypothesis that CCR5 density is a key factor governing cell infectability and in vivo virus production and explain the protective effect of the Delta32CCR5 deletion, which results in low CCR5 expression. CCR5 density might be of critical predictive value in HIV infection.

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.

In vivo HIV-1 infection of CD45RA(+)CD4(+) T cells is established primarily by syncytium-inducing variants and correlates with the rate of CD4(+) T cell decline

Switch from non-syncytium-inducing (NSI) to syncytium-inducing (SI) HIV type 1 (HIV-1) is associated with accelerated CD4(+) T cell depletion, which might partially be explained by higher virulence of SI variants compared with NSI variants. Because NSI and SI variants use different coreceptors for entry of target cells, altered tropism might offer an explanation for increased pathogenesis associated with SI HIV-1 infection. To investigate whether SI and NSI HIV-1 variants infect different CD4(+) T cell subsets in vivo, the distribution of SI and NSI variants over CD4(+) memory (CD45RA(-)RO(+)) and naive (CD45RA(+)RO(-)) cells was studied by using limiting dilution cultures. In contrast to NSI variants that were mainly present in CD45RO(+) cells, SI variants were equally distributed over CD45RO(+) and CD45RA(+) cells. Infection of memory cells by both NSI and SI HIV-1 and infection of naive cells primarily by SI HIV-1 corresponded closely with the differential cell surface expression of CXCR4 and CCR5. The frequency of SI-infected CD45RA(+) CD4(+) T cells, but not the frequency of NSI- or SI-infected CD45RO(+) CD4(+) T cells, correlated with the rate of CD4(+) T cell depletion. Infection of naive cells by SI HIV-1 may interfere with CD4(+) T cell production and thus account for rapid CD4(+) T cell depletion.

Bone marrow CD34(+) cells and megakaryoblasts secrete beta-chemokines that block infection of hematopoietic cells by M-tropic R5 HIV

CD34(+) cells are nonpermissive to infection by HIV strains X4 and R5, despite the fact that many CD34(+) cells express high levels of the viral receptor protein CD4 and the coreceptor CXCR4 on their surface. In these cells, the co-receptor CCR5 protein, which, like CXCR4, is a chemokine receptor, is detected mainly intracellularly. We hypothesized that CD34(+) cells secrete CCR5-binding chemokines and that these factors interfere with HIV R5 interactions with these cells, possibly by binding CCR5 or by inducing its internalization. We found that human CD34(+) cells and CD34(+)KIT(+) cells, which are enriched in myeloid progenitor cells, expressed and secreted the CCR5 ligands RANTES, MIP-1alpha, and MIP-1beta and that IFN-gamma stimulated expression of these chemokines. In contrast, SDF-1, a CXCR4 ligand, was not detectable in the CD34(+)KIT(+) cells, even by RT-PCR. Conditioned media from CD34(+) cell culture significantly protected the T lymphocyte cell line PB-1 from infection by R5 but not X4 strains of HIV. Interestingly, the secretion of endogenous chemokines decreased with the maturation of CD34(+) cells, although ex vivo, expanded megakaryoblasts still secreted a significant amount of RANTES. Synthesis of CCR5-binding chemokines by human CD34(+) cells and megakaryoblasts therefore largely determines the susceptibility of these cells to infection by R5 HIV strains. We postulate that therapeutic agents that induce the endogenous synthesis of chemokines in human hematopoietic cells may protect these cells from HIV infection.

Characterisation of the differential response of normal and CML haemopoietic progenitor cells to macrophage inflammatory protein-1alpha

The clonogenic cells of chronic myeloid leukaemia (CML), unlike normal haemopoietic colony forming cells (CFC), are resistant to the growth inhibitory effects of the chemokine, macrophage inflammatory protein-1alpha (MIP-1alpha). Here, we tested the hypothesis that MIP-1alpha protects normal, but not CML, CFC from the cytotoxic effects of the cell-cycle active drug cytosine arabinoside (Ara-C). Using a 24-h Ara-C protection assay we showed that MIP-1alpha confers protection to normal CFC but also sensitizes CML CFC to Ara-C. The differential MIP-1alpha responsiveness was not due to a down-regulation of MIP-1alpha receptors on CML CD34+ cells as flow cytometric analysis showed similar binding of a biotinylated MIP-1alpha molecule to normal and CML CD34+ cells. Flow cytometric analysis of the MIP-1alpha receptor subtype CCR-5 revealed comparable CCR-5 expression levels on normal and CML CD34+ cells. Furthermore, culture of CD34+ cells for 10 h in the presence of TNF-alpha resulted in an increased MIP-1alpha receptor expression on both normal and CML CD34+ cells. Our data suggest that the unresponsiveness of CML CFC to the growth inhibitory effect of MIP-1alpha is not caused by a lack of MIP-1alpha receptor or total uncoupling of the MIP-1alpha responsiveness but may be due to an intracellular signalling defect downstream of the receptors.

Failure of HIV-1 to infect human oocytes directly

In this study, the susceptibility of mature human oocytes to HIV-1 infection has been investigated. We exposed in vitro human oocytes of healthy women using inocula of cell-free HIV-1. We also tested for the presence of HIV-1-specific receptor molecules on the surface of these cells. By applying polymerase chain reaction (PCR) analysis, transmission electron microscopy (TEM), and immunocytochemistry at both light and electron microscopic levels, we did not obtain evidence for HIV DNA production nor for oocyte-associated HIV particles. Experiments of immunostaining for CD4, CCR5, and GalAAG (putative receptor for HIV in sperm), as well as reverse transcriptase (RT)-PCR for CD4, CCR5, and CXCR4, which all suggested the absence of the mentioned receptors in mature oocytes and in follicular cells. This study fills an important gap concerning the information available on the direct HIV infection of human gametes, adds to our basic understanding of HIV infection in human oocytes, provides different results from those obtained with human spermatozoa using comparable methods, and provides a basic contribution to the investigation on HIV infection in human oocytes.

Chemokine receptor expression by human intestinal epithelial cells

BACKGROUND & AIMS

Intestinal epithelial cells produce an array of proinflammatory chemokines that can provide signals to mucosal immune and inflammatory cells. To determine if chemokines can also signal epithelial cells, we characterized the expression of chemokine receptors on human colon epithelial cells in vitro and in vivo.

METHODS

Expression of chemokine receptor messenger RNAs (mRNAs) by the human colon epithelial cell lines HT-29, HT-29.18.C1, Caco-2, T84, HCA-7, and LS174T was assessed by reverse-transcription polymerase chain reaction. Chemokine receptors on intestinal epithelial cells in vitro were determined by flow cytometry, and expression in vivo was determined by immunostaining of human colon. Interleukin (IL)-8 and growth-related (GRO) alpha secretion were assayed by enzyme-linked immunosorbent assay.

RESULTS

Human colon epithelial cells constitutively expressed mRNAs for an array of CC and CXC chemokine receptors, including CCR1-8 and CXCR4, but little if any CXCR1 or CXCR2. Further studies focused on CXCR4 and CCR5 because mRNA for those chemokine receptors was abundantly expressed by each of the colon epithelial cell lines, and these receptors were present on the cell surface. Analogous to their localization on polarized cell lines, CXCR4 and CCR5 had a predominant apical and, to a lesser extent, basolateral distribution on human enterocytes, as demonstrated by immunostaining of human colon. Human colon epithelial cells stimulated with stromal cell-derived factor 1alpha and macrophage inflammatory protein (MIP)- 1alpha or MIP-1beta, which are the chemokine ligands for CXCR4 or CCR5, up-regulated production of the CXC chemokines IL-8 and GROalpha.

CONCLUSIONS

Human colon epithelial cells express chemokine receptors. Human colonocytes have the potential to serve as targets for chemokine signaling.

Active participation of CCR5(+)CD8(+) T lymphocytes in the pathogenesis of liver injury in graft-versus-host disease

We examined the molecular pathogenesis of graft-versus-host disease-associated (GVHD-associated) liver injury in mice, focusing on the role of chemokines. At the second week after cell transfer in the parent-into-F1 model of GVHD, CD8(+) T cells -- especially donor-derived CD8(+) T cells -- infiltrated the liver, causing both portal hepatitis and nonsuppurative destructive cholangitis (NSDC). These migrating cells expressed CCR5. Moreover, macrophage inflammatory protein-1alpha (MIP-1alpha), one of the ligands for CCR5, was selectively expressed on intralobular bile duct epithelial cells, endothelial cells, and infiltrating macrophages and lymphocytes. Administration of anti-CCR5 antibody dramatically reduced the infiltration of CCR5(+)CD8(+) T lymphocytes into the liver, and consequently protected against liver damage in GVHD. The levels of Fas ligand (FasL) mRNA expression in the liver were also decreased by anti-CCR5 antibody treatment. Anti-MIP-1alpha antibody treatment also reduced liver injury. These results suggest that MIP-1alpha-induced migration of CCR5-expressing CD8(+) T cells into the portal areas of the liver plays a significant role in causing liver injury in GVHD; thus, CCR5 and its ligand may be the novel target molecules of therapeutic intervention of hepatic GVHD.

Microglial activation varies in different models of Creutzfeldt-Jakob disease

Progressive changes in host mRNA expression can illuminate crucial pathogenetic pathways in infectious disease. We examined general and specific approaches to mRNA expression in three rodent models of Creutzfeldt-Jakob disease (CJD). Each of these models displays distinctive neuropathology. Although mRNAs for the chemokine receptor CCR5, the lysosomal protease cathepsin S, and the pleiotropic cytokine transforming growth factor beta1 (TGF-beta1) were progressively upregulated in rodent CJD, the temporal patterns and peak magnitudes of each of these transcripts varied substantially among models. Cathepsin S and TGF-beta1 were elevated more than 15-fold in mice and rats infected with two different CJD strains, but not in CJD-infected hamsters. In rats, an early activation of microglial transcripts preceded obvious deposits of prion protein (PrP) amyloid. However, in each of the three CJD models, the upregulation of CCR5, cathepsin S, and TGF-beta1 was variable with respect to the onset of PrP pathology. These results show glial cell involvement varies as a consequence of the agent strain and species infected. Although neurons are generally assumed to be the primary sites for agent replication and abnormal PrP formation, microglia may be targeted by some agent strains. In such instances, microglia can both process PrP to become amyloid and can enhance neuronal destruction. Because microglia can participate in agent clearance, they may also act as chronic reservoirs of infectivity. Finally, the results here strongly suggest that TGF-beta1 can be an essential signal for amyloid deposition.

Definition of the stage of host cell genetic restriction of replication of human immunodeficiency virus type 1 in monocytes and monocyte-derived macrophages by using twins

Using identical (ID) twins, we have previously demonstrated that host cell genes exert a significant impact on productive human immunodeficiency virus (HIV) infection of monocytes and macrophages (J. Chang et al., J. Virol. 70:7792-7803, 1996). Therefore, the stage in the replication cycle at which these host genetic influences act was investigated in a study using 8 pairs of ID twins and 10 pairs of sex- and age-matched unrelated donors (URDs). In the first phase of the study, blood monocytes and monocyte-derived macrophages (MDM) of ID twins and URDs were infected with 15 HIV type 1 strains. Four well-characterized primary isolates and HIV-BaL were then examined in more detail. The host cell genetic effect in MDM was exerted predominantly prior to complete reverse transcription, as the HIV DNA level and p24 antigen levels were concordant (r = 0.91, P = 0.0001) and similar between the pairs of ID twin pairs (r = 0.96, P = 0.0001) but discordant between URD pairs (r = 0.11, P = 0.3) in both phases of the study. To further examine genetic influence on viral entry, we examined the proportion of CCR5 membrane expression on MDM. As expected, there was wide variability in proportion of MDM expressing CCR5 among URDs (r = 0. 58, P = 0.2); however, this variability was significantly reduced between ID twin pairs (r = 0.81, P = 0.01). Differences in viral entry did not necessarily correlate with CCR5 expression, and only very low levels of CCR5 expression restricted HIV entry and production. In summary, the host cell genetic effect on HIV replication in macrophages appears to be exerted predominantly pre-reverse transcription. Although CCR5 was necessary for infection, other unidentified host genes are likely to limit productive infection.

Quantification of CD4, CCR5, and CXCR4 levels on lymphocyte subsets, dendritic cells, and differentially conditioned monocyte-derived macrophages

CCR5 and CXCR4 are the major HIV-1 coreceptors for R5 and X4 HIV-1 strains, respectively, and a threshold number of CD4 and chemokine receptor molecules is required to support virus infection. Therefore, we used a quantitative fluorescence-activated cell sorting assay to determine the number of CD4, CCR5, and CXCR4 antibody-binding sites (ABS) on various T cell lines, T cell subsets, peripheral blood dendritic cells (PBDC), and monocyte-derived macrophages by using four-color fluorescence-activated cell sorting analysis on fresh whole blood. Receptor levels varied dramatically among the various subsets examined and typically varied from 2- to 5-fold between individuals. CCR5 was expressed at much higher levels in CD4+/CD45RO+/CD62L-true memory cells compared with CD4+/CD45RO+/CD62L+ cells. Fresh PBDC had the highest number of CCR5 ABS among the leukocyte subsets examined but had few CXCR4 ABS, affording a strategy for sort-purifying PBDC. In vitro maturation of PBDC resulted in median 3- and 41-fold increases in CCR5 and CXCR4 ABS, respectively. We found that macrophage colony-stimulating factor caused the greatest up-regulation of both CCR5 and CXCR4 on macrophage maturation (from approximately 5,000 to approximately 50, 000 ABS) whereas granulocyte-macrophage colony-stimulating factor caused a marked decrease of CXCR4 (from approximately 5,000 ABS to <500) while up-regulating CCR5 expression (from approximately 5,000 to approximately 20,000 ABS). Absolute ABS for CD4 and the major HIV-1 coreceptors serve as a more quantitative measure of cell surface expression, and we propose that this be used for future studies looking at the modulation of CD4 or chemokine receptor expression by cytokines, HIV-1 infection, or receptor polymorphisms.

Human intestinal lamina propria lymphocytes are naturally permissive to HIV-1 infection

The presence of HIV-1 in the intestinal mucosa of AIDS patients has been reported and human intestinal lamina propria lymphocytes (LPL) have been proposed as important targets for HIV-1 infection. However, little information is available concerning the permissiveness of human intestinal CD4+ T lymphocytes to HIV-1 infection. Here, we show that human LPL, in contrast to autologous peripheral blood lymphocytes (PBL), are permissive to both X4 T-tropic and R5 M-tropic strains of HIV-1, as well as to clinical isolates, in the absence of exogenous stimuli. Flow cytometry showed that the vast majority of T LPL were CD45RO+ and CD69+, and that CD4+ T LPL highly expressed CC chemokine receptor 5 (CCR5) as compared to PBL, while CX chemokine receptor 4 was equally expressed on LPL and PBL. Exogenous RANTES and macrophage inflammatory protein-1alpha (natural CCR5 ligands) virtually abolished the entry of the R5 M-tropic strain HIV-1 into human LPL. Thus, we infer that human intestinal CD4+ T lymphocytes are naturally susceptible to HIV-1 infection, due to their physiological state of activation and to marked expression of HIV-1 coreceptors, independently of the route of primary (either mucosal or parental) infection and the shifts of the virus phenotype occurring during the course of AIDS.

CCR2-64I polymorphism is not associated with altered CCR5 expression or coreceptor function

A polymorphism in the gene encoding CCR2 is associated with a delay in progression to AIDS in human immunodeficiency virus (HIV)-infected individuals. The polymorphism, CCR2-64I, changes valine 64 of CCR2 to isoleucine. However, it is not clear whether the effect on AIDS progression results from the amino acid change or whether the polymorphism marks a genetically linked, yet unidentified mutation that mediates the effect. Because the gene encoding CCR5, the major coreceptor for HIV type 1 primary isolates, lies 15 kb 3' to CCR2, linked mutations in the CCR5 promoter or other regulatory sequences could explain the association of CCR2-64I with slowed AIDS pathogenesis. Here, we show that CCR2-64I is efficiently expressed on the cell surface but does not have dominant negative activity on CCR5 coreceptor function. A panel of peripheral blood mononuclear cells (PBMC) from uninfected donors representing the various CCR5/CCR2 genotypes was assembled. Activated primary CD4(+) T cells of CCR2 64I/64I donors expressed cell surface CCR5 at levels comparable to those of CCR2 +/+ donors. A slight reduction in CCR5 expression was noted, although this was not statistically significant. CCR5 and CCR2 mRNA levels were nearly identical for each of the donor PBMC, regardless of genotype. Cell surface CCR5 and CCR2 levels were more variable than mRNA transcript levels, suggesting that an alternative mechanism may influence CCR5 cell surface levels. CCR2-64I is linked to the CCR5 promoter polymorphisms 208G, 303A, 627C, and 676A; however, in transfected promoter reporter constructs, these did not affect transcriptional activity. Taken together, these findings suggest that CCR2-64I does not act by influencing CCR5 transcription or mRNA levels.

Intrinsic human immunodeficiency virus type 1 resistance of hematopoietic stem cells despite coreceptor expression

Interactions of human immunodeficiency virus type 1 (HIV-1) with hematopoietic stem cells may define restrictions on immune reconstitution following effective antiretroviral therapy and affect stem cell gene therapy strategies for AIDS. In the present study, we demonstrated mRNA and cell surface expression of HIV-1 receptors CD4 and the chemokine receptors CCR-5 and CXCR-4 in fractionated cells representing multiple stages of hematopoietic development. Chemokine receptor function was documented in subsets of cells by calcium flux in response to a cognate ligand. Productive infection by HIV-1 via these receptors was observed with the notable exception of stem cells, in which case the presence of CD4, CXCR-4, and CCR-5, as documented by single-cell analysis for expression and function, was insufficient for infection. Neither productive infection, transgene expression, nor virus entry was detectable following exposure of stem cells to either wild-type HIV-1 or lentivirus constructs pseudotyped in HIV-1 envelopes of macrophage-tropic, T-cell-tropic, or dualtropic specificity. Successful entry into stem cells of a vesicular stomatitis virus G protein-pseudotyped HIV-1 construct demonstrated that the resistance to HIV-1 was mediated at the level of virus-cell membrane fusion and entry. These data define the hematopoietic stem cell as a sanctuary cell which is resistant to HIV-1 infection by a mechanism independent of receptor and coreceptor expression that suggests a novel means of cellular protection from HIV-1.

Determinant in human immunodeficiency virus type 1 for efficient replication under cytokine-induced CD4(+) T-helper 1 (Th1)- and Th2-type conditions

Cytokines are potent stimuli for CD4(+)-T-cell differentiation. Among them, interleukin-12 (IL-12) and IL-4 induce naive CD4(+) T cells to become T-helper 1 (Th1) or Th2 cells, respectively. In this study we found that macrophage-tropic human immunodeficiency virus type 1 (HIV-1) strains replicated more efficiently in IL-12-induced Th1-type cultures derived from normal CD4(+) T cells than did T-cell-line-tropic (T-tropic) strains. In contrast, T-tropic strains preferentially infected IL-4-induced Th2-type cultures derived from the same donor CD4(+) T cells. Additional studies using chimeric viruses demonstrated that the V3 region of HIV-1 gp120 was the principal determinant for efficiency of replication. Cell fusion analysis showed that cells expressing envelope protein from a T-tropic strain effectively fused with IL-4-induced Th2-type culture cells. Flow cytometric analysis showed that the level of CCR5 expression was higher on IL-12-induced Th1-type culture cells, whereas CXCR4 was highly expressed on IL-4-induced Th2-type culture cells, although a low level of CXCR4 expression was observed on IL-12-induced Th1-type culture cells. These results indicate that HIV-1 isolates exhibit differences in the ability to infect CD4(+)-T-cell subsets such as Th1 or Th2 cells and that this difference may partly correlate with the expression of particular chemokine receptors on these cells. The findings suggest that immunological conditions are one of the factors responsible for inducing selection of HIV-1 strains.

Correlation between humoral responses to human immunodeficiency virus type 1 envelope and disease progression in early-stage infection

Human immunodeficiency virus (HIV)-1-infected rapid and slow progressors showed differential humoral responses against HIV envelope peptides and proteins early in infection. Sera from slow progressors reacted more strongly with short envelope peptides modeling gp160NL4-3, predominantly in gp41. Reactivity to six peptides (in constant regions C3, C4, and C5 of gp120 and in gp41) correlated with slower progression. In a novel association, reactivity to three peptides (in constant regions C1 and C3 and variable region V3 of gp120) correlated with faster progression. Envelope peptide reactivity correlated with subsequent course of disease progression as strongly as did reactivity to gag p24. Patients heterozygous for 32-bp deletions in the CCR5 coreceptor reacted more frequently to an epitope in gp41. Rapid progressors had greater gp120 native-to-denatured binding ratios than did slow progressors. While antibody-dependent cellular cytotoxicity against gp120 did not strongly differentiate the groups, slow progressors showed a broader neutralization pattern against 5 primary virus isolates.

Lymphocyte-specific chemokine receptor CXCR3: regulation, chemokine binding and gene localization

Expression of CXCR3, the receptor for the CXC chemokines IFN-gamma-inducible 10-kDa protein (IP10) and monokine induced by IFN-gamma (Mig), in human T lymphocytes and their responses to IP10 and Mig were analyzed. About 40 % of resting T lymphocytes (and low numbers of B cells and natural killer cells) stained positive for CXCR3 but these cells did not express CXCR3 transcripts and did not respond to these chemokines. However, treatment with IL-2 with or without addition of phytohemagglutinin for 10 or more days resulted in cultures of fully responsive, CXCR3-positive T lymphocytes. Treatment with anti-CD3 antibodies in the presence or absence of soluble anti-CD28 antibodies was inhibitory. Addition of chondroitin sulfate C to CXCR3-expressing murine pre-B cells allowed the determination of high-affinity binding for Mig and IP10 with Kd of 0.9-1.2 nM and 0.2-0.3 nM, respectively, and 1.3 x 10(4) binding sites per cell. The gene for CXCR3 was localized on human chromosome Xq13 which is in clear contrast to all other chemokine receptor genes, suggesting unique function(s) for this receptor and its ligands that may lie beyond their established role in T cell-dependent immunity.

Characterization of the cutaneous exanthem in macaques infected with a Nef gene variant of SIVmac239

The molecularly cloned viruses known as SIVmac239/R17Y and SIVmac239/YEnef cause extensive lymphocyte activation and induce an acute disease syndrome in macaque monkeys. One manifestation of this syndrome is a severe diffuse cutaneous maculopapular exanthem that is similar to the exanthem associated with HIV-1 infection. To examine the pathogenesis of this exanthem, biopsies obtained throughout the course of clinically evident rash were examined for the presence of virus by in situ hybridization and immunohistochemistry, and the cellular infiltrate was characterized with respect to cellular immunophenotype and chemokine receptor expression. The onset of rash was associated with abundant simian immunodeficiency virus nucleic acid and protein within perivascular dermal infiltrates and occasionally within intraepithelial cells. Analysis of cellular infiltrates showed that biopsies, obtained on the day of rash onset, were composed of equal numbers of CD4+ and CD8+ lymphocytes and abundant alphaEbeta7 positive cells surrounding vessels with upregulated endothelial E-selectin. Moreover, by examining virus expression in sequential skin biopsies from the same animal, the clearance of virus and the resolution of rash were associated with an increase in the percentage of cells expressing CD8, the chemokine receptor CXCR3, and GMP-17, a marker of cytotoxic granules. These results suggest that activated cytotoxic T cells are trafficking to sites of inflammation in the skin and directly or indirectly affect levels of viral replication at these sites.

In vivo distribution of the human immunodeficiency virus/simian immunodeficiency virus coreceptors: CXCR4, CCR3, and CCR5

We have evaluated the in vivo distribution of the major human immunodeficiency virus/simian immunodeficiency virus (HIV/SIV) coreceptors, CXCR4, CCR3, and CCR5, in both rhesus macaques and humans. T lymphocytes and macrophages in both lymphoid and nonlymphoid tissues are the major cell populations expressing HIV/SIV coreceptors, reaffirming that these cells are the major targets of HIV/SIV infection in vivo. In lymphoid tissues such as the lymph node and the thymus, approximately 1 to 10% of the T lymphocytes and macrophages are coreceptor positive. However, coreceptor expression was not detected on follicular dendritic cells (FDC) in lymph nodes, suggesting that the ability of FDC to trap extracellular virions is unlikely to be mediated by a coreceptor-specific mechanism. In the thymus, a large number of immature and mature T lymphocytes express CXCR4, which may render these cells susceptible to infection by syncytium-inducing viral variants that use this coreceptor for entry. In addition, various degrees of coreceptor expression are found among different tissues and also among different cells within the same tissues. Coreceptor-positive cells are more frequently identified in the colon than in the rectum and more frequently identified in the cervix than in the vagina, suggesting that the expression levels of coreceptors are differentially regulated at different anatomic sites. Furthermore, extremely high levels of CXCR4 and CCR3 expression are found on the neurons from both the central and peripheral nervous systems. These findings may be helpful in understanding certain aspects of HIV and SIV pathogenesis and transmission.

Flexible programs of chemokine receptor expression on human polarized T helper 1 and 2 lymphocytes

Chemokines and their receptors are important elements for the selective attraction of various subsets of leukocytes. To better understand the selective migration of functional subsets of T cells, chemokine receptor expression was analyzed using monoclonal antibodies, RNase protection assays, and the response to distinct chemokines. Naive T cells expressed only CXC chemokine receptor (CXCR)4, whereas the majority of memory/activated T cells expressed CXCR3, and a small proportion expressed CC chemokine receptor (CCR)3 and CCR5. When polarized T cell lines were analyzed, CXCR3 was found to be expressed at high levels on T helper cell (Th)0s and Th1s and at low levels on Th2s. In contrast, CCR3 and CCR4 were found on Th2s. This was confirmed by functional responses: only Th2s responded with an increase in [Ca2+]i to the CCR3 and CCR4 agonists eotaxin and thymus and activation regulated chemokine (TARC), whereas only Th0s and Th1s responded to low concentrations of the CXCR3 agonists IFN-gamma-inducible protein 10 (IP-10) and monokine induced by IFN-gamma (Mig). Although CCR5 was expressed on both Th1 and Th2 lines, it was absent in several Th2 clones and its expression was markedly influenced by interleukin 2. Chemokine receptor expression and association with Th1 and Th2 phenotypes was affected by other cytokines present during polarization. Transforming growth factor beta inhibited CCR3, but enhanced CCR4 and CCR7 expression, whereas interferon alpha inhibited CCR3 but upregulated CXCR3 and CCR1. These results demonstrate that chemokine receptors are markers of naive and polarized T cell subsets and suggest that flexible programs of chemokine receptor gene expression may control tissue-specific migration of effector T cells.