Ductal carcinoma in situ (DCIS) is the preinvasive form of breast cancer (BC). It is disputed whether all cases of DCIS require extensive treatment as the overall risk of progression to BC is ...estimated at 40%. Therefore, the crucial objective for researchers is to identify DCIS with significant risk of transformation into BC. Dendritic cells (DC) are professional antigen presenting cells and as such play a pivotal role in the formation of immune cells that infiltrate in breast tumors. The aim of this study was to investigate the relationship between the density of DCs with different superficial antigens (CD1a, CD123, DC-LAMP, DC-SIGN) and various histopathological characteristics of DCIS. Our evaluation indicated that CD123
and DC-LAMP
cells were strongly associated with maximal tumor size, grading and neoductgenesis. Together with CD1a
cells, they were negatively correlated with hormonal receptors expression. Furthermore, the number of DC-LAMP
cells was higher in DCIS with comedo necrosis, ductal spread, lobular cancerization as well as comedo-type tumors, while CD1a
cells were abundant in cases with Paget disease. We concluded that different subpopulations of DCs relate to various characteristics of DCIS. Of the superficial DCs markers, DC-LAMP seems particularly promising as a target for further research in this area.
A fluorine nuclear magnetic resonance (
F-NMR)-based method is employed to assess the binding preferences and interaction details of a library of synthetic fluorinated monosaccharides towards ...dendritic cell-specific intercellular adhesion molecule 3-grabbing non-integrin (DC-SIGN), a lectin of biomedical interest, which is involved in different viral infections, including HIV and Ebola, and is able to recognize a variety of self- and non-self-glycans. The strategy employed allows not only screening of a mixture of compounds, but also obtaining valuable information on the specific sugar-protein interactions. The analysis of the data demonstrates that monosaccharides Fuc, Man, Glc, and Gal are able to bind DC-SIGN, although with decreasing affinity. Moreover, a new binding mode between Man moieties and DC-SIGN, which might have biological implications, is also detected for the first time. The combination of the
F with standard proton saturation transfer difference (
H-STD-NMR) data, assisted by molecular dynamics (MD) simulations, permits us to successfully define this new binding epitope, where Man coordinates a Ca
ion of the lectin carbohydrate recognition domain (CRD) through the axial OH-2 and equatorial OH-3 groups, thus mimicking the Fuc/DC-SIGN binding architecture.
C-Type Lectin Receptors (CTLR) are involved in the activation of innate and adaptative immune responses. Among these receptors, the Dendritic Cell-Specific ICAM-3-Grabbing nonintegrin (DC-SIGN/CD209) ...has become a hot topic due to its ability to bind and facilitate the infections processes of several pathogens. Although well characterized in mammals, little documentation exists about the receptor in salmonid fishes. Here, we report the sequence and expression analysis of eight DC-SIGN-like genes in Salmo salar. Each receptor displays structural similarities to DC-SIGN molecules described in mammals, including internalization motifs, a neck region with heptad repeats, and a Ca+2-dependent carbohydrate recognition domain. The receptors are expressed in multiple tissues of fish, and fish cell lines, with differential expression upon infection with viral and bacterial pathogens. The identification of DC-SIGN-like receptors in Salmo salar provides new information regarding the structure of the immune system of salmon, potential markers for cell subsets, as well as insights into DC-SIGN conservation across species.
•DC-SIGN receptors are involved in the activation of innate and adaptative immune responses in mammals.•We describe eight genes in Salmo salar coding for DC-SIGN-like receptors.•SsSIGNs are expressed in multiple fish tissues, and gene expression is differentially regulated upon infection.
Human milk oligosaccharides (HMOs) and their most abundant component, 2'-Fucosyllactose (2'-FL), are known to be immunomodulatory. Previously, it was shown that HMOs and 2'-FL bind to the C-type ...lectin receptor DC-SIGN. Here we show, using a ligand-receptor competition assay, that a whole mixture of HMOs from pooled human milk (HMOS) and 2'-FL inhibit the binding of the carbohydrate-binding receptor DC-SIGN to its prototypical ligands, fucose and the oligosaccharide Lewis-B, (Le
) in a dose-dependent way. Interestingly, such inhibition by HMOS and 2'-FL was not detected for another C-type lectin, langerin, which is evolutionarily similar to DC-SIGN. The cell-ligand competition assay using DC-SIGN expressing cells confirmed that 2'-FL inhibits the binding of DC-SIGN to Le
. Molecular dynamic (MD) simulations show that 2'-FL exists in a preorganized bioactive conformation before binding to DC-SIGN and this conformation is retained after binding to DC-SIGN. Le
has more flexible conformations and utilizes two binding modes, which operate one at a time via its two fucoses to bind to DC-SIGN. Our hypothesis is that 2'-FL may have a reduced entropic penalty due to its preorganized state, compared to Le
, and it has a lower binding enthalpy, suggesting a better binding to DC-SIGN. Thus, due to the better binding to DC-SIGN, 2'-FL may replace Le
from its binding pocket in DC-SIGN. The MD simulations also showed that 2'-FL does not bind to langerin. Our studies confirm 2'-FL as a specific ligand for DC-SIGN and suggest that 2'-FL can replace other DC-SIGN ligands from its binding pocket during the ligand-receptor interactions in possible immunomodulatory processes.
Many viruses exploit the human C‐type lectin receptor dendritic cell‐specific ICAM‐3 grabbing nonintegrin (DC‐SIGN) for cell entry and virus dissemination. An inhibition of DC‐SIGN‐mediated virus ...attachment by glycan‐derived ligands has, thus, emerged as a promising strategy toward broad‐spectrum antiviral therapeutics. In this contribution, several cognate fragments of oligomannose‐ and complex‐type glycans grafted onto a poly‐l‐lysine scaffold are evaluated as polyvalent DC‐SIGN ligands. The range of selected carbohydrate epitopes encompasses linear (α‐
d‐Man‐(1→2)‐α‐
d‐Man, α‐
d‐Man‐(1→2)‐α‐
d‐Man‐(1→2)‐α‐
d‐Man‐(1→3)‐α‐
d‐Man) and branched (α‐
d‐Man‐(1→6)‐α‐
d‐Man‐(1→3)‐α‐
d‐Man) oligomannosides, as well as α‐
l‐Fuc. The thermodynamics of binding are investigated on a mono‐ and multivalent level to shed light on the molecular details of the interactions with the tetravalent receptor. Cellular models of virus attachment and DC‐SIGN‐mediated virus dissemination reveal a high potency of the presented glycopolymers in the low pico‐ and nanomolar ranges, respectively. The high activity of oligomannose epitopes in combination with the biocompatible properties of the poly‐
l‐lysine scaffold highlights the potential for further preclinical development of polyvalent DC‐SIGN ligands.
Viruses can exploit the host receptor dendritic cell‐specific ICAM‐3 grabbing nonintegrin (DC‐SIGN) to promote host infection and virus dissemination. Using SARS‐CoV‐2 as a model, it is demonstrated that synthetic glycan fragments presented on a multivalent poly‐l‐lysine scaffold are potent mimetics of viral envelope glycoproteins and can efficiently abrogate virus attachment and DC‐SIGN‐mediated trans‐infection in pico‐ to nanomolar concentrations.
Alphaviruses and flaviviruses are important human pathogens that include Chikungunya virus (CHIKV), Dengue virus (DENV), and Zika virus (ZIKV), which can cause diseases in humans ranging from ...arthralgia to hemorrhagic fevers and microcephaly. It was previously shown that treatment with surface layer (S-layer) protein, present on the bacterial cell-envelope of
, is able to inhibit viral and bacterial infections by blocking the pathogen's interaction with DC-specific intercellular adhesion molecule 3-grabbing non-integrin (DC-SIGN), a trans-membrane protein that is a C-type calcium-dependent lectin. DC-SIGN is known to act as an attachment factor for several viruses including alphaviruses and flaviviruses. In the present study, we used alphaviruses as a model system to dissect the mechanism of S-layer inhibition. We first evaluated the protective effect of S-layer using 3T3 cells, either wild type or stably expressing DC-SIGN, and infecting with the alphaviruses Semliki Forest virus (SFV) and CHIKV and the flaviviruses ZIKV and DENV. DC-SIGN expression significantly enhanced infection by all four viruses. Treatment of the cells with S-layer prior to infection decreased infectivity of all viruses only in cells expressing DC-SIGN.
ELISA experiments showed a direct interaction between S-layer and DC-SIGN; however, confocal microscopy and flow cytometry demonstrated that S-layer binding to the cells was independent of DC-SIGN expression. S-layer protein prevented SFV binding and internalization in DC-SIGN-expressing cells but had no effect on virus binding to DC-SIGN-negative cells. Inhibition of virus binding occurred in a time-dependent manner, with a significant reduction of infection requiring at least a 30-min pre-incubation of S-layer with DC-SIGN-expressing cells. These results suggest that S-layer has a different mechanism of action compared to mannan, a common DC-SIGN-binding compound that has an immediate effect in blocking viral infection. This difference could reflect slower kinetics of S-layer binding to the DC-SIGN present at the plasma membrane (PM). Alternatively, the S-layer/DC-SIGN interaction may trigger the activation of signaling pathways that are required for the inhibition of viral infection. Together our results add important information relevant to the potential use of
S-layer protein as an antiviral therapy.
Macrophage polarization and HIV-1 infection Cassol, Edana; Cassetta, Luca; Alfano, Massimo ...
Journal of leukocyte biology,
April 2010, Letnik:
87, Številka:
4
Journal Article
Recenzirano
Polarization of MP into classically activated (M1) and alternatively activated (M2a, M2b, and M2c) macrophages is critical in mediating an effective immune response against invading pathogens. ...However, several pathogens use these activation pathways to facilitate dissemination and pathogenesis. Viruses generally induce an M1-like phenotype during the acute phase of infection. In addition to promoting the development of Th1 responses and IFN production, M1 macrophages often produce cytokines that drive viral replication and tissue damage. As shown for HIV-1, polarization can also alter macrophage susceptibility to infection. In vitro polarization into M1 cells prevents HIV-1 infection, and M2a polarization inhibits viral replication at a post-integration level. M2a cells also express high levels of C-type lectins that can facilitate macrophage-mediated transmission of HIV-1 to CD4(+) T cells. Macrophages are particularly abundant in mucosal membranes and unlike DCs, do not usually migrate to distal tissues. As a result, macrophages are likely to contribute to HIV-1 pathogenesis in mucosal rather than lymphatic tissues. In vivo polarization of MP is likely to span a spectrum of activation phenotypes that may change the permissivity to and alter the outcome of HIV-1 and other viral infections.
Allergen-specific immunotherapy (AIT) is the only curative treatment for allergic diseases. However, the long desensitization phase and potentially dangerous allergic side effects limit its broad ...application. Therefore, safer and more effective vaccines are required. Targeting dendritic cells (DCs) with novel allergen conjugates is a promising strategy for AIT. In this study, a novel vaccine with a DC-targeting effect for AIT was constructed. Liposomes were used as vehicles, and a targeted nanovaccine (Lex-lip-Der f 2) was constructed by loading the recombinant group 2 allergen of Dermatophagoides farinae (Der f 2) and conjugating with the DC-SIGN ligand Lewis X. The effect of the vaccine on DCs and T cell responses and the safety of the vaccine were investigated in vitro. The results showed that the Lex-lip-Der f 2 vaccine was spherical, with size of approximately 128 nm. The protein-loading capacity of the vaccine was 0.106 ± 0.001 mg per mg liposome and protein was gradually released from the liposomes during the first 12 h. Lex-lip-Der f 2 was taken up more efficiently by DCs than non-targeted liposomes or free Der f 2. Besides, Lex-lip-Der f 2 significantly inhibited the release of IL-4, IL-6, and TNF-a from DCs. Accordingly, Der f 2-lip loaded DCs significantly decreased IL-4 levels in autologous naïve CD4+T cells. Moreover, Lex-lip-Der f 2-treated basophils showed lower activation levels. These results suggest that DC-SIGN targeting mediated by Lewis X could inhibit the Th2 cell response and improve vaccine safety, and may be a novel vaccination strategy.
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Background. Chikungunya infections range from subclinical infection to debilitating arthralgia and to chronic inflammatory rheumatism. Tumor necrosis factor (TNF) alpha, DC-SIGN (dendritic ...cell-specific intercellular adhesion molecule 3-grabbing nonintegrin), Toll-like receptor (TLR) 3, and blood groups have been directly or indirectly implicated in the susceptibility and pathogenesis of chikungunya. Methods. To test the hypothesis that polymorphisms in genes coding for these molecules determine clinical outcomes of chikungunya infection, a retrospective case-control study was performed in Leon, Nicaragua. The study included 132 case patients and 132 controls, matched for age, sex and neighborhood. Case patients had clinical symptoms of chikungunya, which was diagnosed by means of polymerase chain reaction. Controls were individuals not reporting abrupt presentation of clinical chikungunya-like symptoms. Polymorphisms were identified by TaqMan single-nucleotide polymorphism genotyping assays. Results. After adjustment for sociodemographic risk factors, chikungunya disease was associated with polymorphism in DC-SIGN and TLR3 genes (odds ratios, 5.2 and 3.3, respectively), and TNF-alpha with reduced persistent joint pain (0.24). Persistent joint pain was also associated with age, female sex and other comorbid conditions. Most interestingly, the Lewis-negative phenotype was strongly associated with both symptomatic chikungunya and immunoglobulin G seropositivity (odds ratios, 2.7, and 3.3, respectively). Conclusion. This study identified polymorphisms in DC-SIGN, TLR3, and TNF-alpha genes as well as Lewis-negative phenotype as risk factors for chikungunya infection and disease progression.
Multivalency plays a major role in biological processes and particularly in the relationship between pathogenic microorganisms and their host that involves protein-glycan recognition. These ...interactions occur during the first steps of infection, for specific recognition between host and bacteria, but also at different stages of the immune response. The search for high-affinity ligands for studying such interactions involves the combination of carbohydrate head groups with different scaffolds and linkers generating multivalent glycocompounds with controlled spatial and topology parameters. By interfering with pathogen adhesion, such glycocompounds including glycopolymers, glycoclusters, glycodendrimers and glyconanoparticles have the potential to improve or replace antibiotic treatments that are now subverted by resistance. Multivalent glycoconjugates have also been used for stimulating the innate and adaptive immune systems, for example with carbohydrate-based vaccines. Bacteria present on their surfaces natural multivalent glycoconjugates such as lipopolysaccharides and S-layers that can also be exploited or targeted in anti-infectious strategies.
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