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Differential infection of mononuclear phagocytes by Francisella tularensis: role of the macrophage mannose receptor
- J. Leukoc. Biol
, 2006
"... negative bacterium and the causative agent of tu-laremia. It is well established that this organism replicates inside macrophages, but we are only be-ginning to understand this interface at the molecular level. Herein, we compared directly the ability of Ft subspecies holarctica live-vaccine strain ..."
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negative bacterium and the causative agent of tu-laremia. It is well established that this organism replicates inside macrophages, but we are only be-ginning to understand this interface at the molecular level. Herein, we compared directly the ability of Ft subspecies holarctica live-vaccine strain to infect freshly isolated human peripheral blood monocytes, monocyte-derived macrophages (MDM), and cells of the murine macrophage cell line J774A.1 (J774). We now show that unopsonized bacteria infected human MDM fivefold more efficiently than monocytes or J774 cells in standard media. More-over, enhanced infection of MDM was mediated, in part, by the macrophage mannose receptor (MR). Forming Ft phagosomes accumulated MR, and in-fection was inhibited by MR-blocking antibody or soluble mannan but not by the dectin-1 ligand lami-narin. Up-regulation of MR in MDM (by exposure to interleukin-4) increased Ft phagocytosis, as did expression of MR in J774 cells. Conversely, opson-ized Ft were ingested readily by monocytes and MDM. Medium supplementation with 2.5 % fresh autologous serum was sufficient to confer opsonoph-agocytosis and CD11b accumulated in the mem-brane at sites of Ft engulfment. Infection of mono-cytes by opsonized Ft was nearly ablated by com-plement receptor 3 (CR3) blockade. Conversely, MDM used MR and CD11b/CD18 to ingest opson-ized organisms. Altogether, our data demonstrate differential infection of mononuclear phagocytes by Ft and define distinct roles for MR and CR3 in phagocytosis. J. Leukoc. Biol. 80: 563–571; 2006. Key Words: phagocytosis complement live-vaccine strain MDM tularemia lectinophagocytosis
West Nile virus discriminates between DCSIGN and DC-SIGNR for cellular attachment and infection
, 2006
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HIV-1 transmission and cytokine-induced expression of DC-SIGN in human monocyte-derived macrophages
, 2003
"... hesion molecule-3-grabbing nonintegrin (DC-SIGN) has been described as an attachment mole-cule for human immunodeficiency virus type 1 (HIV-1) with the potential to mediate its transmis-sion. We examined DC-SIGN expression in mono-cyte-derived macrophages (MDM) and its role in viral transmission whe ..."
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Cited by 12 (1 self)
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hesion molecule-3-grabbing nonintegrin (DC-SIGN) has been described as an attachment mole-cule for human immunodeficiency virus type 1 (HIV-1) with the potential to mediate its transmis-sion. We examined DC-SIGN expression in mono-cyte-derived macrophages (MDM) and its role in viral transmission when MDM were exposed to in-terleukin (IL)-13, IL-4, or interferon- (IFN-). We show that IL-13 and IL-4 increase transcripts, total protein, and cell-surface expression of DC-SIGN in all MDM tested, IFN- 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. Trans-mission experiments of HIV-1 X4 between cyto-kine-treated MDM to Sup-T1 cells showed no asso-ciation 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 con-trast, IFN- treatment induced a decrease in total transmission by at least two-thirds, despite its in-duction 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 trans-mission. Taken together, results show that DC-SIGN regulation in MDM does not singly predict the transmission potential of this cell type. J. Leu-koc. Biol. 74: 757–763; 2003.
Commentary A Dangerous Liaison between Two Major Killers: Mycobacterium tuberculosis and HIV Target Dendritic Cells through DC-SIGN
"... HIV and Mycobacterium tuberculosis, respectively, again top the infamous WHO list of excess deaths caused by infectious agents (1; Fig. 1). To further worsen the situation, these two pathogens do not operate independently. More than half a million of those who died last year were already coinfected ..."
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HIV and Mycobacterium tuberculosis, respectively, again top the infamous WHO list of excess deaths caused by infectious agents (1; Fig. 1). To further worsen the situation, these two pathogens do not operate independently. More than half a million of those who died last year were already coinfected with both pathogens and more than 50 million individuals coinfected with HIV and M. tuberculosis envisage a similar fate in the upcoming years. One third of the total world population (2 billion people) is infected with M. tuberculosis and coinfection with HIV exacerbates the risk of developing active tuberculosis from 1 in 10 during lifetime to 1 in 10 during the year after HIV infection (2). As long as the immune system remains competent, M. tuberculosis is normally held at bay, though the immune response fails to achieve sterile eradication. Once, however,
Identification and functional characterization of a bovine orthologue to DC-SIGN
- J. Leukoc. Biol
, 2008
"... nonintegrin (DC-SIGN) C-type lectin is almost exclu-sively expressed at the cell surface of DC. In addition to its normal function facilitating contact of DC with T cells, DC-SIGN has been shown to bind a variety of pathogens, including Mycobacterium bovis, and HIV-1 envelope protein gp120. In this ..."
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Cited by 1 (0 self)
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nonintegrin (DC-SIGN) C-type lectin is almost exclu-sively expressed at the cell surface of DC. In addition to its normal function facilitating contact of DC with T cells, DC-SIGN has been shown to bind a variety of pathogens, including Mycobacterium bovis, and HIV-1 envelope protein gp120. In this study, we identified the bovine ortholog of the humanDC-SIGN gene within the bovine genome, which exists as a single copy. PCR amplified a product, showing a 100 % match with the predicted sequences as well as a sequence predicted to be similar to that of SIGNR7. Furthermore, a protein with the same molecular weight as human DC-SIGN was detected by Western blot in cell lysate derived from bovine DC. To char-acterize this molecule functionally, the uptake of FITC-labeled OVA and FITC-labeled gp120 (FITC-gp120) by bovine and humanDCwas assessed. FITC-gp120 was shown to bind to bovine DC in a time- and temperature-dependent manner. Binding was blocked by a polyclonal anti-DC-SIGN antibody but not by a control antibody. Furthermore, blocking of this molecule also reduced the binding of M. bovis bacillus Calmette-Guerin expressing GFP. Confocal microscopy showed that DC-SIGN was expressed on the surface of bovine DC. Subsequent pulse-chase studies revealed that FITC-gp120 was internalized by bovine monocyte-derived DC as early as 10 min. Thus, there is evidence of a DC-SIGN-like molecule expressed specifically by bovine DC. This molecule may play an important role in the infection of bovine
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"... d DC-SIGN+ macrophages inhibit CD8+ T cell proliferation and ..."
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REFERENCES CONTENT ALERTS
, 2001
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REFERENCES CONTENT ALERTS
, 2005
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