bluuebunny/crossref_metadata_2025_split huggingface dataset:
Macrophages and lymphocytes differentially modulate the ability of RANTES to inhibit HIV-1 infection
Authors: Gross Eleanore , Amella Carol A , Pompucci Lorena , Franchin Giovanni , Sherry Barbara , Schmidtmayerova Helena 
Published: September 2003

AbstractThe β-chemokines MIP-1α, MIP-1β, and RANTES inhibit HIV-1 infection of CD4+ T cells by inhibiting interactions between the virus and CCR5 receptors. However, while β-chemokine-mediated inhibition of HIV-1 infection of primary lymphocytes is well documented, conflicting results have been obtained using primary macrophages as the virus target. Here, we show that the β-chemokine RANTES inhibits virus entry into both cellular targets of the virus, lymphocytes and macrophages. However, while virus entry is inhibited at the moment of infection in both cell types, the amount of virus progeny is lowered only in lymphocytes. In macrophages, early-entry restriction is lost during long-term cultivation, and the amount of virus produced by RANTES-treated macrophages is similar to the untreated cultures, suggesting an enhanced virus replication. We further show that at least two distinct cellular responses to RANTES treatment in primary lymphocytes and macrophages contribute to this phenomenon. In lymphocytes, exposure to RANTES significantly increases the pool of inhibitory β-chemokines through intracellular signals that result in increased production of MIP-1α and MIP-1β, thereby amplifying the antiviral effects of RANTES. In macrophages this amplification step does not occur. In fact, RANTES added to the macrophages is efficiently cleared from the culture, without inducing synthesis of β-chemokines. Our results demonstrate dichotomous effects of RANTES on HIV-1 entry at the moment of infection, and on production and spread of virus progeny in primary macrophages. Since macrophages serve as a reservoir of HIV-1, this may contribute to the failure of endogenous chemokines to successfully eradicate the virus.
The contribution of monocyte infection and trafficking to viral persistence, and maintenance of the viral reservoir in HIV infection
Authors: Crowe Suzanne , Zhu Tuofu , Muller William A 
Published: September 2003

AbstractCellular viral reservoirs and anatomic sanctuary sites allow continuing HIV-1 replication in patients with suppressed plasma viremia who are receiving highly active antiretroviral therapy and prevent eradication of HIV-1 by these regimens. Cells of macrophage lineage, including monocytes subsets within the blood, play a role in HIV-1 persistence. Evidence of sequence evolution in blood monocytes, in comparison to resting CD4+ T cells, demonstrates their distinct contribution to plasma viremia. There is evidence to suggest that a specific monocyte subset, of CD14loCD16hi phenotype, is more susceptible to HIV-1 infection than the majority of blood monocytes. Trafficking of monocytes through various tissues following their emigration from the bloodstream allows these cells to differentiate into tissue macrophages, or potentially to egress from the tissues as migratory dendritic cells. This review provides an evaluation of the contribution of monocytes to HIV-1 persistence and the HIV-1 reservoir, essential for the effective design of therapeutic eradication strategies.
Macrophage activation through CCR5- and CXCR4-mediated gp120-elicited signaling pathways
Authors: Lee ChuHee , Liu Qing-Hua , Tomkowicz Brian , Yi Yanjie , Freedman Bruce D , Collman Ronald G 
Published: September 2003

AbstractMacrophages are major targets for infection by human immunodeficiency virus type 1 (HIV-1). In addition to their role as productive viral reservoirs, inappropriate activation of infected and uninfected macrophages appears to contribute to pathogenesis. HIV-1 infection requires initial interactions between the viral envelope surface glycoprotein gp120, the cell-surface protein CD4, and a chemokine receptor CCR5 or CXCR4. Besides their role in HIV-1 entry, CCR5 and CXCR4 are G protein-coupled receptors that can activate multiple intracellular signaling pathways. HIV-1 gp120 has been shown to activate signaling pathways through the chemokine receptors in several cell types including lymphocytes, neurons, and astrocytes. In some cell types, these consequences may cause cellular injury. In this review, we highlight our data demonstrating diverse signaling events that occur in primary human macrophages in response to gp120/chemokine receptor interactions. These responses include K+, Cl–, and nonselective cation currents, intracellular Ca2+ increases, and activation of several kinases including the focal adhesion-related tyrosine kinase Pyk2, mitogen-activated protein kinases (MAPK), and phosphoinositol-3 kinase. Activation of the MAPK leads to gp120-induced expression of chemokines such as monocyte chemoattractant protein-1 and macrophage-inflammatory protein-1β and the proinflammatory cytokine tumor necrosis factor α. These responses establish a complex cytokine network, which may enhance or suppress HIV-1 replication. In addition, dysregulation of macrophage function by gp120/chemokine receptor signaling may contribute to local inflammation and injury and further recruit additional inflammatory and/or target cells. Targeting these cellular signaling pathways may have benefit in controlling inflammatory sequelae of HIV infection such as in neurological disease.
Monocyte/macrophage traffic in HIV and SIV encephalitis
Authors: Kim Woong-Ki , Corey Sarah , Alvarez Xavier , Williams Kenneth 
Published: September 2003

AbstractThis short review focuses on the role of central nervous system (CNS) perivascular macrophages as targets of productive infection of the CNS. Data discussed include the importance of these cells as early targets of infection and their productive infection with AIDS. Many of the immune molecules on perivascular macrophages are also found on subsets of blood monocyte/macrophages, some of which are expanded during human immunodeficiency virus (HIV) infection. These observations paired with the known bone marrow (BM) origin of perivascular macrophages and the BM as a site of HIV infection underscore the importance of the study of monocyte populations in the BM and blood, which are activated and infected as a source of virus that enters the CNS. Data presented and discussed herein suggest a role of HIV-infected BM-derived monocytes as “Trojan horse” cells that traffic to the CNS to become perivascular macrophages. The study of such cells including their timing of infection, activation, and traffic and the role of HIV-specific immune responses controlling their accumulation in the CNS warrant study with regard to CNS neuropathogenesis.
The role of dendritic cell C-type lectin receptors in HIV pathogenesis
Authors: Turville Stuart , Wilkinson John , Cameron Paul , Dable Joanne , Cunningham Anthony L 
Published: September 2003

AbstractDendritic cells play a major role in HIV pathogenesis. Epithelial dendritic cells appear to be one of the first cells infected after sexual transmission and transfer of the virus to CD4 lymphocytes, simultaneously activating these cells to produce high levels of HIV replication. Such transfer may occur locally in inflamed mucosa or after dendritic cells have matured and migrated to local lymph nodes. Therefore, the mechanism of binding, internalization, infection and transfer of HIV to CD4 lymphocytes is of great interest. Recently, the role of the C-type lectin DC-SIGN as a dendritic cell receptor for HIV has been intensively studied with in vitro monocyte-derived dendritic cells. However, it is clear that other C-type lectin receptors such as Langerin on Langerhan cells and mannose receptor on dermal dendritic cells are at least equally important for gp120 binding on epithelial dendritic cells. C-type lectin receptors play a role in virus transfer to T cells, either via de novo infection (“cis transfer”) or without infection (“in trans” or transinfection). Both these processes are important in vitro, and both may have a role in vivo, although the low-level infection of immature dendritic cells may be more important as it leads to R5 HIV strain selection and persistence of virus within dendritic cells for at least 24 h, sufficient for these cells to transit to lymph nodes. The exact details of these processes are currently the subject of intense study.
Insulin-dependent signaling regulates azurophil granule-selective macroautophagy in human myeloblastic cells
Authors: Saeki Kumiko , Hong Zhang , Nakatsu Masami , Yoshimori Tamotsu , Kabeya Yukiko , Yamamoto Akitsugu , Kaburagi Yasushi , Yuo Akira 
Published: September 2003

AbstractWe show that insulin-dependent signals regulate azurophil granule-selective macroautophagy in human myeloid cells. Depletion of insulin from an insulin-transferrin-supplemented serum-free medium caused growth retardation of myeloblastic HL-60 cells, in which sequestration of electronic-dense cytoplasmic materials by autophagosomes was observed. Positive immunoreactivity with anti-CD68, anti-cathepsin D, and anti-myeloperoxidase antibodies indicated that the sequestrated materials were azurophil granules, the granulocyte/macrophage lineage-specific lysosome-like particles. By contrast, other organelles, including the mitochondria, endoplasmic reticulum, and Golgi apparatus remained intact, indicating that the macroautophagy selectively targeted azurophil granules. The addition of insulin induced rapid activations of p70S6K and Akt, and the cells were rescued from macroautophagy. Rapamycin, an inhibitor of mammalian target of rapamycin, did not block the insulin-mediated rescue from macroautophagy, although it nullified the activation of p70S6K and cell growth. Low doses of LY294002, a phosphatidyl-inositol-3-kinase inhibitor, which abolished cell growth and p70S6K activity but did not influence Akt activity, did not block the insulin-mediated rescue either. By contrast, low doses of Akt-specific inhibitors, which inhibited neither cell growth nor p70S6K activity, completely blocked the insulin-mediated rescue from macroautophagy. Thus, insulin-dependent signals are responsible for the control of azurophil granule-selective macroautophagy via Akt-dependent pathways, while p70S6K-dependent pathways promote cell growth.
Macrophage HIV-1 infection and the gastrointestinal tract reservoir
Authors: Smith Phillip D , Meng Gang , Salazar-Gonzalez Jesus F , Shaw George M 
Published: September 2003

AbstractExcluding parenteral transmissions, virtually all vertical and homosexual transmission of human immunodeficiency virus type 1 (HIV-1) occurs via the gastrointestinal tract. Cellular routes implicated in the translocation of virus across the epithelium include M cells, dendritic cells, and epithelial cells. Intestinal epithelial cells express CCR5 and can selectively transfer CCR5-tropic HIV-1, the phenotype of the majority of transmitted viruses. In the lamina propria, virus encounters the largest reservoir of mononuclear cells in the body. Surprisingly, lamina propria lymphocytes, not macrophages, express CCR5 and CXCR4 and support HIV-1 replication, implicating intestinal lymphocytes as the initial target cell in the intestinal mucosa. From the mucosa, virus is disseminated to systemic sites, followed by profound depletion of CD4+ T cells, first in the intestinal lamina propria and subsequently in the blood. As mucosal and circulating CD4+ T cells are depleted, monocytes and macrophages assume an increasingly important role as target and reservoir cells for HIV-1. Blood monocytes, including HIV-1-infected cells, are recruited to the mucosa, where they differentiate into lamina propria macrophages in the presence of stroma-derived factors. Although the prevalence of HIV-1-infected macrophages in the mucosa is low (0.06% of lamina propria mononuclear cells), the extraordinary size of the gastrointestinal mucosa imparts to intestinal macrophages a prominent role as a HIV-1 reservoir. Elucidating the immunobiology of mucosal HIV-1 infection is critical for understanding disease pathogenesis and ultimately for devising an effective mucosal HIV-1 vaccine.
Viral and host cofactors facilitate HIV-1 replication in macrophages
Authors: Wahl Sharon M , Greenwell-Wild Teresa , Peng Gang , Ma Ge , Orenstein Jan M , Vázquez Nancy 
Published: September 2003

AbstractHuman immunodeficiency virus type 1 (HIV-1) infection of CD4+ T lymphocytes leads to their progressive loss, whereas HIV-1-infected macrophages appear to resist HIV-1-mediated apoptotic death. The differential response of these two host-cell populations may be critical in the development of immunodeficiency and long-term persistence of the virus. Multiple contributing factors may favor the macrophage as a resilient host, not only supporting infection by HIV-1 but also promoting replication and persistence of this member of the lentivirus subfamily of primate retroviruses. An encounter between macrophages and R5 virus engages a signal cascade eventuating in transcriptional regulation of multiple genes including those associated with host defense, cell cycle, nuclear factor-κB regulation, and apoptosis. It is important that enhanced gene expression is transient, declining to near control levels, and during this quiescent state, the virus continues its life cycle unimpeded. However, when viral replication becomes prominent, an increase in host genes again occurs under the orchestration of viral gene products. This biphasic host response must fulfill the needs of the parasitic virus as viral replication activity occurs and leads to intracellular and cell surface-associated viral budding. Inroads into understanding how HIV-1 co-opts host factors to generate a permissive environment for viral replication and transmission to new viral hosts may provide opportunities for targeted interruption of this lethal process.
Generation and characterization of mice transgenic for human IL-18-binding protein isoforma
Authors: Fantuzzi Giamila , Banda Nirmal K , Guthridge Carla , Vondracek Andrea , Kim Soo-Hyun , Siegmund Britta , Azam Tania , Sennello Joseph A , Dinarello Charles A , Arend William P 
Published: September 2003

AbstractInterleukin (IL)-18 binding protein (IL-18BP) is a natural inhibitor of the pleiotropic cytokine IL-18. To study the role of IL-18BP in modulating inflammatory responses in vivo, mice transgenic for human IL-18BP isoform a (IL-18BP-Tg) were generated. The transgene was expressed at high levels in each organ examined. High levels of bioactive human IL-18BPa were detectable in the circulation of IL-18BP-Tg mice, which were viable, fertile, and had no tissue or organ abnormality. The high levels of IL-18BP in the transgenic mice were able to completely neutralize the interferon-γ (IFN-γ)-inducing activity of exogenously administered IL-18. Following administration of endotoxin, with or without prior sensitization with heat-inactivated Propionibacterium acnes, IL-18BP-Tg mice produced significantly lower serum levels of IFN-γ and macrophage-inflammatory protein-2 compared with nontransgenic littermates. Significantly reduced production of IFN-γ in response to endotoxin was also observed in cultures of IL-18BP-Tg splenocytes. Finally, IL-18BP-Tg mice were completely protected in a model of hepatotoxicity induced by administration of concanavalin A. These results indicate that high endogenous levels of IL-18BP in trangenic mice effectively neutralize IL-18 and are protective in response to different inflammatory stimuli.
HIV-1 transmission and cytokine-induced expression of DC-SIGN in human monocyte-derived macrophages
Authors: Chehimi Jihed , Luo Qi , Azzoni Livio , Shawver Linda , Ngoubilly Noel , June Ray , Jerandi Ghassen , Farabaugh Matthew , Montaner Luis J 
Published: September 2003

AbstractDendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN) has been described as an attachment molecule for human immunodeficiency virus type 1 (HIV-1) with the potential to mediate its transmission. We examined DC-SIGN expression in monocyte-derived macrophages (MDM) and its role in viral transmission when MDM were exposed to interleukin (IL)-13, IL-4, or interferon-γ (IFN-γ). We show that IL-13 and IL-4 increase transcripts, total protein, and cell-surface expression of DC-SIGN in all MDM tested, IFN-γ results ranged from no change to up-regulation of surface expression, and message and total protein were, respectively, induced in all and 86% of donors tested. Transmission experiments of HIV-1 X4 between cytokine-treated MDM to Sup-T1 cells showed no association between total transmission and DC-SIGN up-regulation. IL-4 but not IL-13 resulted in a less than twofold increase in MDM viral transmission to CD4+ T cells in spite of a fourfold up-regulation in DC-SIGN expression by either cytokine. In contrast, IFN-γ treatment induced a decrease in total transmission by at least two-thirds, despite its induction of DC-SIGN. Soluble mannan resulted in a greater inhibition of viral transmission to CD4+ T cells than neutralizing anti-DC-SIGN monoclonal antibody (67–75% vs. 39–48%), supporting the role of mannose-binding receptors in viral transmission. Taken together, results show that DC-SIGN regulation in MDM does not singly predict the transmission potential of this cell type.
STI571 inhibits growth and adhesion of human mast cells in culture
Authors: Takeuchi Kouichi , Koike Kenichi , Kamijo Takehiko , Ishida Shuichi , Nakazawa Yozo , Kurokawa Yumi , Sakashita Kazuo , Kinoshita Tatsuya , Matsuzawa Shigeyuki , Shiohara Masaaki , Yamashita Tetsuji , Nakajima Motowo , Komiyama Atsushi 
Published: September 2003

AbstractStem cell factor (SCF)/c-kit system is critical for human mast cell development. We thus examined the effects of STI571, an inhibitor of the c-kit tyrosine kinase receptor, on the proliferation and function of human mast cells. STI571 at concentrations of 10−6 M or higher almost completely abolished the SCF-dependent progeny generation from cord blood-derived cultured mast cells through an inhibition of the tyrosine phosphorylation of c-kit. The compound also suppressed the early phase of mast cell development. The extinction of mast cell growth induced by STI571 may be due largely to apoptosis according to the flow cytometric analysis and gel electrophoresis. Two-hour exposure to STI571 that failed to influence the total viable cell number suppressed adhesion of the cells to fibronectin in the presence of SCF without altering the expressions of integrin molecules. Our results may provide a fundamental insight for the clinical application of STI571 in allergic disorders.
ANP inhibits TNF-α-induced endothelial MCP-1 expression—involvement of p38 MAPK and MKP-1
Authors: Weber Nina C , Blumenthal Signe B , Hartung Thomas , Vollmar Angelika M , Kiemer Alexandra K 
Published: September 2003

AbstractAtrial natriuretic peptide (ANP) has been shown to reduce tumor necrosis factor-α (TNF-α)-induced activation of endothelial cells via inhibition of p38 mitogen-activated protein kinase (MAPK) and nuclear factor (NF)-κB pathways. The aim of this study was to determine whether ANP is able to inhibit TNF-α-induced expression of monocyte chemoattractant protein-1 (MCP-1) in endothelial cells and to elucidate the mechanisms involved. Pretreatment of human umbilical vein endothelial cells (HUVEC) with ANP significantly reduced TNF-α-induced expression of MCP-1 protein and mRNA. The effects of ANP were shown to be mediated via the guanylyl-cyclase (GC)-coupled A receptor. Activation of the other GC-coupled receptor (natriuretic peptide receptor-B) by the C-type natriuretic peptide as well as activation of soluble GC with S-nitroso-L-glutathione (GSNO) exerted similar effects as ANP, supporting a role for cyclic guanosine monophosphate (cGMP) in the signal transduction. Antisense experiments showed a requirement of MAPK phosphatase-1 (MKP-1) induction and therefore, inhibition of p38 MAPK in the ANP-mediated inhibition of TNF-α-induced expression of MCP-1. To investigate a potential interplay between TNF-α-induced activation of p38 MAPK and NF-κB, the p38 MAPK inhibitor SB203580 and a dominant-negative p38 MAPK mutant were used. The results indicated that the blockade of p38 MAPK activity leads to an increased activation of NF-κB and therefore, suggest a counter-regulatory action of p38 MAPK and NF-κB. As antisense experiments revealed a pivotal role for MKP-1 induction and therefore, p38 MAPK inhibition in ANP-mediated attenuation of MCP-1 expression, this action seems to be rather independent of NF-κB inhibition.
Comparative analysis of IRF and IFN-alpha expression in human plasmacytoid and monocyte-derived dendritic cells
Authors: Izaguirre Alexander , Barnes Betsy J , Amrute Sheela , Yeow Wen-Shuz , Megjugorac Nicholas , Dai Jihong , Feng Di , Chung Eugene , Pitha Paula M , Fitzgerald-Bocarsly Patricia 
Published: September 2003

AbstractPlasmacytoid dendritic cells (PDC) produce high levels of type I IFN upon stimulation with viruses, while monocytes and monocyte-derived dendritic cells (MDDC) produce significantly lower levels. To find what determines the high production of type I IFN in PDC, we examined the relative levels of IRF transcription factors, some of which play critical roles in the induction of IFN. Furthermore, to determine whether the differences could result from expression of distinct IFNA subtypes, the profile of IFNA genes expressed was examined. PDC responded equally well to stimulation with HSV-1 and Sendai virus (SV) by producing high levels of type I IFN, whereas the MDDC and monocyte response to SV were lower, and neither responded well to HSV-1. All three populations constitutively expressed most of the IRF genes. However, real-time RT-PCR demonstrated increased levels of IRF-7 transcripts in PDC compared with monocytes. As determined by intracellular flow cytometry, the PDC constitutively expressed significantly higher levels of IRF-7 protein than the other populations while IRF-3 levels were similar among populations. Analysis of the profile of IFNA genes expressed in virus-stimulated PDC, monocytes and MDDC demonstrated that each population expressed IFNA1 as the major subtype but that the range of the subtypes expressed in PDC was broader, with some donor and stimulus-dependent variability. We conclude that PDC but not MDDC are uniquely preprogrammed to respond rapidly and effectively to a range of viral pathogens with high levels of IFN-α production due to the high levels of constitutively expressed IRF-7.
The main function of IL-2 is to promote the development of T regulatory cells
Authors: Malek Thomas R 
Published: September 2003

AbstractBased primarily on vitro studies, interleukin (IL)-2 has been considered a key growth and death factor for antigen-activated T lymphocytes. IL-2 is also essential to maintain self-tolerance, as IL-2- and IL-2 receptor-deficient mice exhibit lethal autoimmunity. The intrinsic death-sensitizing activity of IL-2 was thought to be a key mediator for apoptosis of peripheral autoreactive T cells. However, recent in vivo studies strongly favor a model whereby IL-2 controls autoimmunity through the production of CD4+CD25+ T regulatory (Treg) cells. In this setting, IL-2 is essential for expansion of Treg cells within the thymus and in peripheral neonatal-immune tissue. Thus, from being considered the primary growth factor for antigen-activated T lymphocytes, these new findings redefine the pivotal role for IL-2 as the major inducer for the developmental production of suppressive Treg cells.