Cole, G; Coleman, N; Soilleux, E
The process by which hepatitis C virus (HCV) enters cells and the reason for its hepatotropism remain obscure. Recently, the human immunodeficiency virus (HIV) binding lectins, DC-SIGN and DC-SIGNR, were shown to bind HCV. This article reports the expression of DC-SIGN and DC-SIGNR in HCV related liver disease and discusses whether these lectins, in particular DC-SIGNR, are responsible for HCV hepatotropism.
Full Text Available Background. Human dendritic cell-specific intracellular adhesion molecule-3 (ICAM3-grabbing non-integrin (DC-SIGN is a mannose-binding lectin that initiates interaction between dendritic cells and resting T-lymphocytes. DC-SIGN is highly expressed in placental tissue on dendritic cells and Hofbauer cells, and it is suggested that HIV may become adsorbed to DC-SIGN on Hofbauer cells as part of the mechanism of mother-to-child HIV transmission. A possible mechanism of transfer of the virus from the Hofbauer cells to the fetus is the subsequent adsorption to DC-SIGN-related molecules (DC-SIGNRs, present on immediately adjacent capillary vascular endothelium. However, data on DC-SIGN and DC-SIGNR expression in the placenta are few.Methods. Forty term placentas from HIV-positive mothers and 21 term placentas from HIV-negative mothers underwent immunohistochemistry staining for DC-SIGN and DC-SIGNR expression. Five random sets of 10 villi were assessed, and the average number of positive cells were counted in each case. In addition, where possible, maternal and cord blood viral loads and maternal CD4+ counts were performed in the HIV-positive group only.Results. The median maternal CD4+ count was 377 cells/µl and 27% of participants had undetectable viral loads; the median detectable viral load was 3.72 log. Most (97% of the cord bloods tested in infants from HIV-positive mothers had lower than detectable viral loads. HIV-positive cases had significantly greater expression of both DC-SIGNRs (median values in HIV-positive cases, 14.5 positive cells/10 villi (pc/10villi, compared with 11 pc/10villi in HIV-negative cases, p=0.020 and DC-SIGN (median value in HIV-positive cases, 26.5 pc/10villi, compared with 23 pc/10villi in HIV-negative cases, p=0.037. DC-SIGNR expression was also noted in Hofbauer cells and decidual macrophages in addition to endothelium (reported currently. There was no difference in expression of DC-SIGN and DC-SIGNRs in patients
Naderi, Mohammad; Hashemi, Mohammad; Soroush, Navid; Amininia, Shadi; Taheri, Mohsen
There are conflicting results concerning DC-SIGN and DC-SIGNR VNTR polymorphisms. The present study aimed to evaluate the possible association between DC-SIGN as well as DC-SIGNR VNTR polymorphisms and pulmonary tuberculosis (PTB) in a sample of Iranian population. This case-control study was done on 171 PTB and 161 healthy subjects. The variants were detected by polymerase chain reaction (PCR). DC-SIGNR VNTR genotypes in cases were 12.7% for 5/5, 2.4% for 6/5, 32.7% for 7/7, 38.2% for 7/5, 5.5% for 7/6, 1.2% for /5, 0.6% for 9/6, 6.7% for 9/7 in PTB patients and 19.7% for 5/5, 2.0% for 6/5, 31.6% for 7/7, 37.5% for 7/5, 5.7% for 7/6, 0.0% for 9/5, 0.7% for 9/6, 2.6% for 9/7 in controls. The findings showed no significant association between DC-SIGNR VNTR polymorphism and PTB. All subjects in cases and controls were 7/7 genotype regarding DC-SIGN VNTR polymorphism. Our data propose that DC-SIGNR VNTR, as well as DC-SIGN VNTR, were not associated with the risk of PTB in a sample of Iranian population.
许利军; 潘晨; 李勤光
DC-SIGN和DC-SIGNR是两种表达于DC表面的蛋白,被认为是许多病原微生物的黏附受体,参与很多病原微生物的感染.DC-SIGN和DC-SIGNR(DC-SIGN/DC-SIGNR)的多态性或许影响病原微生物的感染过程和结果.此文对DC-SIGN/DC-SIGNR的结构功能以及与HIV、HCV感染、肺结核、登革热的关系进行了综述.%DC-SIGN and DC-SIGNR are two surface proteins on dendritic cells with complex stmction, and are regarded as attachment receptors of many pathogens, DC-SIGN/DC-SIGNR participate in pathogen infection.Polymorphisms of DC-SIGN/DC-SIGNR probably influence the procedure and outcome of pathogen infection. In this article, the structure and function of DC-SIGN/DC-SIGNR are discussed as well as the relation between the DC-SIGN/DC-SIGNR and pathogens such as HIV, HCV infection, pulmonary tuberculosis, dengue fever.
Jun Li; Zhi-Hua Feng; Guang-Yu Li; Dan-Lei Mou; Qing-He Nie
AIM: To generate dendritic cells (DCs) from human peripheral blood and to detect the expression of dendritic cell-specific intercellular adhesion molecule 3 grabbing nonintegrin (DC-SIGN; CD209) for the further study of DC-SIGN in hepatitis C virus (HCV) transmission.METHODS: Peripheral blood monocytes were isolated from blood of healthy individuals by Ficoll-Hypaque sedimentation and cultured in complete medium containing rhGM-CSF and rhIL-4. Cells were cultured for seven days, with cytokine addition every two days to obtain immature DCs. Characteristics of the cultured cells were observed under light and scanning microscope, and the expression of DC-SIGN was detected by immunofluorescence staining.RESULTS: After seven-day culture, a large number of cells with typical characteristics of DCs appeared. Their characteristics were observed under light and scanning electron microscope. These cells had a variety of cell shapes such as those of bipolar elongate cells, elaborate stellate cells and DCs. DC-SIGN was detected by immunofluorescence staining and its expression level on cultivated dendritic cells was high.CONCLUSION: DCs with a high expression of DC-SIGN can be generated from human peripheral blood monocytes in complete medium containing rhGM-CSF and rhIL-4.
Li Ma; Jian Fei; Ying Chen; Bing Zhao; Zhi-Tao Yang; Lu Wang; Hui-Qiu Sheng
Background:The expression of dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin (DC-SIGN) in renal tubular epithelial cells has been thought to be highly correlated with the occurrence of several kidney diseases,but whether it takes place in renal tissues during hemorrhagic shock (HS) is unknown.The present study aimed to investigate this phenomenon and the inhibitory effect of Vitamin C (VitC).Methods:A Sprague-Dawley rat HS model was established in vivo in this study.The expression level and location of DC-SIGN were observed in kidneys.Also,the degree of histological damage,the concentrations of tumor necrosis factor-α and interleukin-6 in the renal tissues,and the serum concentration of blood urea nitrogen and creatinine at different times (2-24 h) after HS (six rats in each group),with or without VitC treatment before resuscitation,were evaluated.Results:HS induced DC-SIGN expression in rat tubular epithelial cells.The proinflammatory cytokine concentration,histological damage scores,and functional injury of kidneys had increased.All these phenomena induced by HS were relieved when the rats were treated with VitC before resuscitation.Conclusions:The results of the present study illustrated that HS could induce tubular epithelial cells expressing DC-SIGN,and the levels of proinflammatory cytokines in the kidney tissues improved correspondingly.The results also indicated that VitC could suppress the DC-SIGN expression in the tubular epithelial cells induced by HS and alleviate the inflammation and functional injury in the kidney.
Bradford, Barry M; Brown, Karen L; Mabbott, Neil A
Prion diseases are infectious neurodegenerative disorders characterised by accumulations of abnormal prion glycoprotein in affected tissues. Following peripheral exposure, many prion strains replicate upon follicular dendritic cells (FDC) in lymphoid tissues before infecting the brain. An intact splenic marginal zone is important for the efficient delivery of prions to FDC. The marginal zone contains a ring of specific intercellular adhesion molecule-3-grabbing non-integrin related 1 (SIGN-R1)-expressing macrophages. This lectin binds dextran and capsular pneumococcal polysaccharides, and also enhances the clearance of apoptotic cells via interactions with complement components. Since prions are acquired as complement-opsonized complexes we determined the role of SIGN-R1 in disease pathogenesis. We show that transient down-regulation of SIGN-R1 prior to intravenous prion exposure had no effect on the early accumulation of prions upon splenic FDC or their subsequent spread to the brain. Thus, SIGN-R1 expression by marginal zone macrophages is not rate-limiting for peripheral prion disease pathogenesis.
Yang Yang, Ali Zohaib, Gong Chen, Jing Ye and Shengbo Cao*
Full Text Available Japanese Encephalitis virus (JEV is a mosquito borne flavivirus that infects macrophages, monocytes and dendritic cells (DCs during in vivo replication. The C-type lectins DC-SIGN and DC-SIGNR have been reported to act as cell attachment factors for diverse array of pathogens. In this study, the effect of these lectins on JEV infection was investigated after the generation of 293T-SIGN (R cell lines expressing DC-SIGN and DC-SIGNR receptors. It was observed that only DC-SIGN but not the DC-SIGNR can act as a viral attachment factor in case of JEV infection. The infection to cells expressing DC-SIGN was efficiently blocked by anti-DC-SIGN and mannan molecules. It was also found that insect derived JEV has higher affinity for DC-SIGN as compare to the mammalian derived JEV. These results initially suggest that DC-SIGN could act as viral attachment receptors (VAR for JEV and enhance JEV infection.
Arrighi, JF; Pion, M; Wiznerowicz, M; Geijtenbeek, T.B.H.; Garcia, E; Abraham, S.; Leuba, F; Dutoit, V; Ducrey-Rundquist, O; Kooijk, van Y.; Trono, D; Piguet, V
In the early events of human immunodeficiency virus type 1 (HIV-1) infection, immature dendritic cells (DCs) expressing the DC-specific intercellular adhesion molecule 3-grabbing nonintegrin (DC-SIGN) receptor capture small amounts of HIV-1 on mucosal surfaces and spread viral infection to CD4(+) T
Ilyas, Rebecca; Wallis, Russell; Soilleux, Elizabeth J; Townsend, Paul; Zehnder, Daniel; Tan, Bee K; Sim, Robert B; Lehnert, Hendrik; Randeva, Harpal S; Mitchell, Daniel A
Diabetic complications include infection and cardiovascular disease. Within the immune system, host-pathogen and regulatory host-host interactions operate through binding of oligosaccharides by C-type lectin. A number of C-type lectins recognise oligosaccharides rich in mannose and fucose - sugars with similar structures to glucose. This raises the possibility that high glucose conditions in diabetes affect protein-oligosaccharide interactions via competitive inhibition. Mannose-binding lectin, soluble DC-SIGN and DC-SIGNR, and surfactant protein D, were tested for carbohydrate binding in the presence of glucose concentrations typical of diabetes, via surface plasmon resonance and affinity chromatography. Complement activation assays were performed in high glucose. DC-SIGN and DC-SIGNR expression in adipose tissues was examined via immunohistochemistry. High glucose inhibited C-type lectin binding to high-mannose glycoprotein and binding of DC-SIGN to fucosylated ligand (blood group B) was abrogated in high glucose. Complement activation via the lectin pathway was inhibited in high glucose and also in high trehalose - a nonreducing sugar with glucoside stereochemistry. DC-SIGN staining was seen on cells with DC morphology within omental and subcutaneous adipose tissues. We conclude that high glucose disrupts C-type lectin function, potentially illuminating new perspectives on susceptibility to infectious and inflammatory disease in diabetes. Mechanisms involve competitive inhibition of carbohydrate binding within sets of defined proteins, in contrast to broadly indiscriminate, irreversible glycation of proteins.
Mayumi, Nobuko; Watanabe, Eri; Norose, Yoshihiko; Watari, Eiji; Kawana, Seiji; Geijtenbeek, Teunis B H; Takahashi, Hidemi
Human skin contains the following two distinct DC subsets: (i) Langerhans cells (LCs), expressing Langerin but not DC-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN), are predominantly localized in the epidermis; and (ii) dermal DCs, expressing DC-SIGN but not Langerin, are observed mainly in the dermis. It is not known whether localization in the epidermis provides cues for LC differentiation. Here, we show that E-cadherin expressed by epidermal keratinocytes (KCs) ...
Lasala, Fátima; Arce, Eva; Otero, Joaquín R.; Rojo, Javier; Delgado, Rafael
We have designed a glycodendritic structure, BH30sucMan, that blocks the interaction between dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin (DC-SIGN) and Ebola virus (EBOV) envelope. BH30sucMan inhibits DC-SIGN-mediated EBOV infection at nanomolar concentrations. BH30sucMan may counteract important steps of the infective process of EBOV and, potentially, of microorganisms shown to exploit DC-SIGN for cell entry and infection. PMID:14638512
Zhi-Hua Feng; Quan-Chu Wang; Qing-He Nie; Zhan-Sheng Jia; Yong-Xin Zhou
DC-SIGN, a dendritic Cell-specific adhesion receptor and a type Ⅱ transmembrane mannose-binding C-type lectin, is very important in the function of DC, both in mediating naive T cell interactions through ICAM-3 and as a rolling receptor that mediates the DC-specific ICAM-2-dependent migration processes. It can be used by viral and bacterial pathogens including Human Immunodeficiency Virus (HIV), HCV, Ebola Virus, CMV and Mycobacterium tuberculosis to facilitate infection. Both DC-SIGN and DC-SIGNR can act either in cis,by concentrating virus on target cells, or in trans, by transmission of bound virus to a target cell expressing appropropriate entry receptors. Recent work showed that DC-SIGN are highaffinity binding receptors for HCV. Besides playing a role in entry into DC, HCV E2 interaction with DC-SIGN might also be detrimental for the interaction of DC with T cells during antigen presentation. The clinical strategies that target DCSIGN may be successful in restricting HCV dissemination and pathogenesis as well as directing the migration of DCs to manipulate appropriate immune responses in autoimmunity and tumorigenic situations.
Zhang, Hongtao; Palma, Angelina S; Zhang, Yibing; Childs, Robert A; Liu, Yan; Mitchell, Daniel A; Guidolin, Leticia S; Weigel, Wilfried; Mulloy, Barbara; Ciocchini, Andrés E; Feizi, Ten; Chai, Wengang
The β1,2-glucans produced by bacteria are important in invasion, survival and immunomodulation in infected hosts be they mammals or plants. However, there has been a lack of information on proteins which recognize these molecules. This is partly due to the extremely limited availability of the sequence-defined oligosaccharides and derived probes for use in the study of their interactions. Here we have used the cyclic β1,2-glucan (CβG) of the bacterial pathogen Brucella abortus, after removal of succinyl side chains, to prepare linearized oligosaccharides which were used to generate microarrays. We describe optimized conditions for partial depolymerization of the cyclic glucan by acid hydrolysis and conversion of the β1,2-gluco-oligosaccharides, with degrees of polymerization 2–13, to neoglycolipids for the purpose of generating microarrays. By microarray analyses, we show that the C-type lectin receptor DC-SIGNR, like the closely related DC-SIGN we investigated earlier, binds to the β1,2-gluco-oligosaccharides, as does the soluble immune effector serum mannose-binding protein. Exploratory studies with DC-SIGN are suggestive of the recognition also of the intact CβG by this receptor. These findings open the way to unravelling mechanisms of immunomodulation mediated by β1,2-glucans in mammalian systems. PMID:27053576
Shimojima, Masayuki; Ströher, Ute; Ebihara, Hideki; Feldmann, Heinz; Kawaoka, Yoshihiro
Although O-mannosylated dystroglycan is a receptor for Lassa virus, a causative agent of Lassa fever, recent findings suggest the existence of an alternative receptor(s). Here we identified four molecules as receptors for Lassa virus: Axl and Tyro3, from the TAM family, and dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin (DC-SIGN) and liver and lymph node sinusoidal endothelial calcium-dependent lectin (LSECtin), from the C-type lectin family. These molecules enhanced the binding of Lassa virus to cells and mediated infection independently of dystroglycan. Axl- or Tyro3-mediated infection required intracellular signaling via the tyrosine kinase activity of Axl or Tyro3, whereas DC-SIGN- or LSECtin-mediated infection and binding were dependent on a specific carbohydrate and on ions. The identification of these four molecules as Lassa virus receptors advances our understanding of Lassa virus cell entry.
Martínez, María Guadalupe; Prado Acosta, Mariano; Candurra, Nélida A; Ruzal, Sandra M
It has been previously described that S-layer binds to the C-type lectin DC-specific ICAM-3-grabbing nonintegrin (DC-SIGN, CD209). It was also shown that DC-SIGN is a cell-surface adhesion factor that enhances viral entry of several virus families. Among those, Junin virus (JUNV) entry is enhanced in cells expressing DC-SIGN and for that reason surface-layer protein (S-layer) of Lactobacillus acidophilus ATCC 4365 was evaluated as a possible JUNV inhibitor. Experiments using 3T3 cells stably expressing DC-SIGN, showed an almost complete inhibition of JUNV infection when they were treated with S-layer in a similar extend as the inhibition shown by mannan. However no inhibition effect was observed in 3T3 wild type cells or in 3T3 cells expressing liver/lymph node-specific ICAM-3 grabbing nonintegrin (L-SIGN or DC-SIGNR or CD209L). Treatments with S-layer during different times in the infection demonstrated that inhibition was only observed when S-layer was presented in early stages of the viral infection. This inhibition does not involve the classic recognition of mannose by this C-type lectin as the S-layer showed no evidence to be glycosylated. In fact, the highly basic nature of the S-layer (pI>9.5) seems to be involved in electrostatic interactions between DC-SIGN and S-layer, since high pH abolished the inhibitory effect on infection cause by the S-layer. In silico analysis predicts a Ca(2+)-dependant carbohydrate recognition domain in the SlpA protein. This novel characteristic of the S-layer, a GRAS status protein, contribute to the pathogen exclusion reported for this probiotic strain and may be applied as an antiviral agent to inhibit several kinds of viruses.
王全楚; 冯志华; 聂青和; 周永兴
Objective To review the recent developments in and research into binding receptors of hepatitis C virus (HCV) and especially the role of dendritic cell-specitic adhesion receptor (DC-SIGN) in HCV.Data sources Both Chinese- and English-languge literature was searched using MEDLINE (2000-2003) and the databank of Chinese-language literature (2000-2003).Study selection Relevant articles on DC-SIGN and HCV binding receptors in recent domestic and foreign literature were selected.Data extraction Data were mainly extracted from 40 articles which are listed in the references section of this review. Results DC-SIGN, a dendritic cell-specific adhesion receptor and a type Ⅱ transmembrane mannose-binding C-type lectin, is very important in the function of dendritic cells (DC), both in mediating na(I)ve T cell interactions through ICAM-3 and as a rolling receptor that mediates the DC-specific ICAM-2-dependent migration processes-It can be used by HCV and other viral and bacterial pathogens including human immunodeficiency virus (HIV), Ebola virus, CMV and Mycobacterium tuberculosis- to facilitate infection. Both DC-SIGN and DC-SIGNR can act either in cis, by concentrating virus on target cells, or in trans, by transmission of bound virus to a target cell expressing appropriate entry receptors. Recent report showed that DC-S IGN not only plays a role in entry into DC, HCV E2 interaction with DC-SIGN might also be detrimental to the interaction of DC with T cells during antigen presentation.Conclusions DC-SIGNs are high-affinity binding receptors for HCV.The clinical strategies that target DC-SIGN may be successful in restricting HCV dissemination and pathogenesis as well as directing the migration of DCs to manipulate appropriate immune responses in autoimmunity and tumorigenic situations.
Full Text Available The zwitterionic capsular polysaccharide A (PSA of Bacteroides fragilis is the first carbohydrate antigen described to be presented in major histocompatibility complex (MHC class II for the induction of CD4+ T cell responses. However, the identity of the receptor mediating binding and internalization of PSA in antigen presenting cells remains elusive. C-type lectins are glycan-binding receptors known for their capacity to target ligands for antigen presentation to T cells. Here, we investigated whether C-type lectins were involved in the internalization of PSA and identified dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN as the main receptor for PSA on human dendritic cells. The induction of PSA-specific T cell proliferation appeared to be completely dependent on DC-SIGN. These data reveal a crucial role for DC-SIGN in the endocytosis and routing of PSA in human dendritic cells for the efficient stimulation of PSA-specific CD4+ T cells.
Full Text Available BACKGROUND: Kawasaki disease (KD is a systemic vasculitis with unknown etiology mainly affecting children in Asian countries. Dendritic cell-specific intercellular adhesion molecule-3 grabbing non-integrin (DC-SIGN, CD209 in humans was showed to trigger an anti-inflammatory cascade and associated with KD susceptibility. This study was conducted to investigate the association between genetic polymorphisms of CD209 and the risk KD. METHODS: A total of 948 subjects (381 KD and 567 controls were recruited. Nine tagging SNPs (rs8112310, rs4804800, rs11465421, rs1544766, rs4804801, rs2287886, rs735239, rs735240, rs4804804 were selected for TaqMan allelic discrimination assay. Clinical phenotypes, coronary artery lesions (CAL and intravenous immunoglobulin (IVIG treatment outcomes were collected for analysis. RESULTS: Significant associations were found between CD209 polymorphisms (rs4804800, rs2287886, rs735240 and the risk of KD. Haplotype analysis for CD209 polymorphisms showed that A/A/G haplotype (P = 0.0002, OR = 1.61 and G/A/G haplotype (P = 0.0365, OR = 1.52 had higher risk of KD as compared with G/G/A haplotype in rs2287886/rs735239/rs735240 pairwise allele analysis. There were no significant association in KD with regards to CAL formation and IVIG treatment responses. CONCLUSION: CD209 polymorphisms were responsible for the susceptibility of KD, but not CAL formation and IVIG treatment responsiveness.
Brzezicka, Katarzyna; Echeverria, Begoña; Serna, Sonia; van Diepen, Angela; Hokke, Cornelis H; Reichardt, Niels-Christian
The synthesis of a collection of 33 xylosylated and core-fucosylated N-glycans found only in nonmammalian organisms such as plants and parasitic helminths has been achieved by employing a highly convergent chemo-enzymatic approach. The influence of these core modifications on the interaction with plant lectins, with the human lectin DC-SIGN (Dendritic Cell-Specific Intercellular adhesion molecule-3-Grabbing Nonintegrin), and with serum antibodies from schistosome-infected individuals was studied. Core xylosylation markedly reduced or completely abolished binding to several mannose-binding plant lectins and to DC-SIGN, a C-type lectin receptor present on antigen presenting cells. Employing the synthetic collection of core-fucosylated and core-xylosylated N-glycans in the context of a larger glycan array including structures lacking these core modifications, we were able to dissect core xylose and core fucose specific antiglycan antibody responses in S. mansoni infection sera, and we observed clear and immunologically relevant differences between children and adult groups infected with this parasite. The work presented here suggests that, quite similar to bisecting N-acetylglucosamine, core xylose distorts the conformation of the unsubstituted glycan, with important implications for the immunogenicity and protein binding properties of complex N-glycans.
Prado Acosta, Mariano; Ruzal, Sandra M; Cordo, Sandra M
Many species of Lactobacillus sp. possess Surface(s) layer proteins in their envelope. Among other important characteristics S-layer from Lactobacillus acidophilus binds to the cellular receptor DC-SIGN (Dendritic Cell-Specific Intercellular adhesion molecule-3-Grabbing Non-integrin; CD209), which is involved in adhesion and infection of several families of bacteria. In this report we investigate the activity of new S-layer proteins from the Lactobacillus family (Lactobacillus acidophilus, Lactobacillus brevis, Lactobacillus helveticus and Lactobacillus kefiri) over the infection of representative microorganisms important to human health. After the treatment of DC-SIGN expressing cells with these proteins, we were able to diminish bacterial infection by up to 79% in both gram negative and mycobacterial models. We discovered that pre-treatment of the bacteria with S-layers from Lactobacillus acidophilus and Lactobacillus brevis reduced bacteria viability but also prevent infection by the pathogenic bacteria. We also proved the importance of the glycosylation of the S-layer from Lactobacillus kefiri in the binding to the receptor and thus inhibition of infection. This novel characteristic of the S-layers proteins may contribute to the already reported pathogen exclusion activity for these Lactobacillus probiotic strains; and might be also considered as a novel enzymatic antimicrobial agents to inhibit bacterial infection and entry to host cells.
Mayumi, Nobuko; Watanabe, Eri; Norose, Yoshihiko; Watari, Eiji; Kawana, Seiji; Geijtenbeek, Teunis B H; Takahashi, Hidemi
Human skin contains the following two distinct DC subsets: (i) Langerhans cells (LCs), expressing Langerin but not DC-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN), are predominantly localized in the epidermis; and (ii) dermal DCs, expressing DC-SIGN but not Langerin, are observed mainly in the dermis. It is not known whether localization in the epidermis provides cues for LC differentiation. Here, we show that E-cadherin expressed by epidermal keratinocytes (KCs) is crucial for differentiation of LCs. Monocytes differentiated into LC-like cells in presence of IL-4, GM-CSF, and TGF-β1. However, these LC-like cells expressed not only Langerin but also DC-SIGN. Notably, co-culturing of these LC-like cells with KCs expressing E-cadherin or recombinant E-cadherin strongly decreased expression of DC-SIGN and further induced a phenotype similar to purified epidermal LCs. Moreover, pretreatment of LC-like cells with anti-E-cadherin-specific antibody completely abolished their Langerin expression, indicating the requirement of E-cadherin–E-cadherin interactions for the differentiation into Langerin+ cells. These findings suggest that E-cadherin expressed by KCs provide environmental cues that induce differentiation of LCs in the epidermis. PMID:23135957
So Young Kim
Full Text Available Flaviviruses are enveloped, positive single stranded ribonucleic acid (RNA viruses with various routes of transmission. While the type and severity of symptoms caused by pathogenic flaviviruses vary from hemorrhagic fever to fetal abnormalities, their general mechanism of host cell entry is similar. All pathogenic flaviviruses, such as dengue virus, yellow fever virus, West Nile virus, Japanese encephalitis virus, and Zika virus, bind to glycosaminglycans (GAGs through the putative GAG binding sites within their envelope proteins to gain access to the surface of host cells. GAGs are long, linear, anionic polysaccharides with a repeating disaccharide unit and are involved in many biological processes, such as cellular signaling, cell adhesion, and pathogenesis. Flavivirus envelope proteins are N-glycosylated surface proteins, which interact with C-type lectins, dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN through their glycans. In this review, we discuss both host and viral surface receptors that have the carbohydrate components, focusing on the surface interactions in the early stage of flavivirus entry. GAG-flavivirus envelope protein interactions as well as interactions between flavivirus envelope proteins and DC-SIGN are discussed in detail. This review also examines natural and synthetic inhibitors of flaviviruses that are carbohydrate-based or carbohydrate-targeting. Both advantages and drawbacks of these inhibitors are explored, as are potential strategies to improve their efficacy to ultimately help eradicate flavivirus infections.
Full Text Available Abstract Dendritic cells (DC are the initiators and modulators of the immune responses. Some species of pathogenic microorganisms have developed immune evasion strategies by controlling antigen presentation function of DC. Simian virus 40 (SV40 is a DNA tumor virus of rhesus monkey origin. It can induce cell transformation and tumorigenesis in many vertebrate species, but often causes no visible effects and persists as a latent infection in rhesus monkeys under natural conditions. To investigate the interaction between SV40 and rhesus monkey DC, rhesus monkey peripheral blood monocyte-derived DC were induced using recombinant human Interleukin-4 (rhIL-4 and infective SV40, the phenotype and function of DC-specific intracellular adhesion molecule-3 grabbing nonintegrin (DC-SIGN+ DC were analyzed by flow cytometry (FCM and mixed lymphocyte reaction (MLR. Results showed that SV40 can down-regulate the expression of CD83 and CD86 on DC and impair DC-induced activation of T cell proliferation. These findings suggest that SV40 might also cause immune suppression by influencing differentiation and maturation of DC.
Batal, Ibrahim; De Serres, Sacha A; Safa, Kassem; Bijol, Vanesa; Ueno, Takuya; Onozato, Maristela L; Iafrate, A John; Herter, Jan M; Lichtman, Andrew H; Mayadas, Tanya N; Guleria, Indira; Rennke, Helmut G; Najafian, Nader; Chandraker, Anil
Progress in long-term renal allograft survival continues to lag behind the progress in short-term transplant outcomes. Dendritic cells are the most efficient antigen-presenting cells, but surprisingly little attention has been paid to their presence in transplanted kidneys. We used dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin as a marker of dendritic cells in 105 allograft biopsy samples from 105 kidney transplant recipients. High dendritic cell density was associated with poor allograft survival independent of clinical variables. Moreover, high dendritic cell density correlated with greater T cell proliferation and poor outcomes in patients with high total inflammation scores, including inflammation in areas of tubular atrophy. We then explored the association between dendritic cells and histologic variables associated with poor prognosis. Multivariate analysis revealed an independent association between the densities of dendritic cells and T cells. In biopsy samples with high dendritic cell density, electron microscopy showed direct physical contact between infiltrating lymphocytes and cells that have the ultrastructural morphologic characteristics of dendritic cells. The origin of graft dendritic cells was sought in nine sex-mismatched recipients using XY fluorescence in situ hybridization. Whereas donor dendritic cells predominated initially, the majority of dendritic cells in late allograft biopsy samples were of recipient origin. Our data highlight the prognostic value of dendritic cell density in allograft biopsy samples, suggest a new role for these cells in shaping graft inflammation, and provide a rationale for targeting dendritic cell recruitment to promote long-term allograft survival.
Daniel C Farley
Full Text Available It is a current regulatory requirement to demonstrate absence of detectable replication-competent lentivirus (RCL in lentiviral vector products prior to use in clinical trials. Immune Design previously described an HIV-1-based integration-deficient lentiviral vector for use in cancer immunotherapy (VP02. VP02 is enveloped with E1001, a modified Sindbis virus glycoprotein which targets dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN expressed on dendritic cells in vivo. Vector enveloped with E1001 does not transduce T-cell lines used in standard HIV-1-based RCL assays, making current RCL testing formats unsuitable for testing VP02. We therefore developed a novel assay to test for RCL in clinical lots of VP02. This assay, which utilizes a murine leukemia positive control virus and a 293F cell line expressing the E1001 receptor DC-SIGN, meets a series of evaluation criteria defined in collaboration with US regulatory authorities and demonstrates the ability of the assay format to amplify and detect a hypothetical RCL derived from VP02 vector components. This assay was qualified and used to test six independent GMP production lots of VP02, in which no RCL was detected. We propose that the evaluation criteria used to rationally design this novel method should be considered when developing an RCL assay for any lentiviral vector.
许利军; 常秀春; 姚航平; 吴南屏
DC-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN) is specific receptor on Dendritic cells, and plays a pivotal role on antigens presentation. Uptodate, the clear regulation mechanisms for DC-SIGN expression are not available.IL-4 is one of the most important cytokines inducing DC-SIGN production, while, NF-κB is an important transcription factor controlling signaling transduction. Both IL-4 and NF-κB are closely related to DC-SIGN regulation. NF-κB and IL-4 actions on DC-SIGN promoter activity, DC-SIGN expression as well as interactions between IL-4 and NF-κB were investigated in THP-1 cell. It was found that the mutation of NF-κB binding site in DC-SIGN promoter results in DC-SIGN promoter activity decrease about 50%.NF-κBp50 stimulates DC-SIGN expression in THP-1 cells. IL-4 upregulates DC-SIGN expression on THP-1 cells as well as NF-κB production. These data reveal that NF-κB is associated with IL-4 induced DC-SIGN expression.%树突状细胞表面特异的胞间黏附分子3捕获非整合素(DC-specific intercellular adhesion molecule-3-grabbing nonintegrin,DC-SIGN)是树突状细胞表面特异的蛋白,在抗原呈递过程中起关键作用.这种特异性的表达和DC-SIGN的调节机制有关.到目前为止,DC-SIGN表达调控的机制还不是很清楚.IL-4是诱导DC-SIGN表达的最重要的细胞因子之一,而NF-κB是调控细胞信号转导的一个重要调控因子,两者都和DC-SIGN的表达调节相关.研究了IL-4和NF-κB对DC-SIGN启动子活性、对DC-SIGN表达的影响以及IL-4和NF-κB之间相互作用的关系.发现:DC-SIGN启动子中NF-κB位点缺失可以使DC-SIGN启动子活性下降大约50%,NF-κBp50可以促进DC-SIGN在THP-1细胞的表达,IL-在THP-1细胞诱导DC-SIGN表达的同时,也促进了NF-κBp50的表达.这些结果显示,在THP-1细胞中NF-κBp50参与IL-4诱导的DC-SIGN表达.
Noll, Alexander J; Yu, Ying; Lasanajak, Yi; Duska-McEwen, Geralyn; Buck, Rachael H; Smith, David F; Cummings, Richard D
Human milk glycans (HMGs) are prebiotics, pathogen receptor decoys and regulators of host physiology and immune responses. Mechanistically, human lectins (glycan-binding proteins, hGBP) expressed by dendritic cells (DCs) are of major interest, as these cells directly contact HMGs. To explore such interactions, we screened many C-type lectins and sialic acid-binding immunoglobulin-like lectins (Siglecs) expressed by DCs for glycan binding on microarrays presenting over 200 HMGs. Unexpectedly, DC-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) showed robust binding to many HMGs, whereas other C-type lectins failed to bind, and Siglec-5 and Siglec-9 showed weak binding to a few glycans. By contrast, most hGBP bound to multiple glycans on other microarrays lacking HMGs. An α-linked fucose residue was characteristic of HMGs bound by DC-SIGN. Binding of DC-SIGN to the simple HMGs 2'-fucosyl-lactose (2'-FL) and 3-fucosyl-lactose (3-FL) was confirmed by flow cytometry to beads conjugated with 2'-FL or 3-FL, as well as the ability of the free glycans to inhibit DC-SIGN binding. 2'-FL had an IC50 of ∼1 mM for DC-SIGN, which is within the physiological concentration of 2'-FL in human milk. These results demonstrate that DC-SIGN among the many hGBP expressed by DCs binds to α-fucosylated HMGs, and suggest that such interactions may be important in influencing immune responses in the developing infant.
Jin, Changzhong; Li, Jie; Cheng, Linfang; Liu, Fumin; Wu, Nanping
The reactivation mechanism of latent human immunodeﬁciency virus type 1 (HIV-1) infection is unclear, especially in dendritic cells (DC). DC-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) binds with HIV-1 and other pathogens to activate the extracellular regulated protein kinase (ERK) and nuclear factor-kappa B (NF-κB) pathways and regulate cytokine expression. We hypothesized that DC-SIGN-induced signaling pathways may activate HIV-1 provirus. To investigate this hypothesis, we generated a model by transfecting 293T cells with a DC-SIGN expression plasmid and an HIV-1 5' long terminal repeat (LTR) reporter plasmid, and then stimulated the 293T cells with HIV-1 gp120 protein, wild-type HIV-1 or VSV-G-pNL4.3 pseudotype virus (without gp120 protein). It was found that the HIV-1 5'LTR was reactivated by HIV-1 gp120 in DC-SIGN-expressing 293T cells. Then the HIV-1 chronically infected CEM-Bru cells were transfected with DC-SIGN expression plasmid and stimulated by HIV-1 gp120 protein. It was found that early and late HIV-1 provirus replication was reactivated by the HIV-1 gp120/DC-SIGN stimulation. We then investigated the involvement of the ERK, p38 mitogen-activated protein kinases and NF-κB signaling pathways in HIV-1 gp120/DC-SIGN-induced activation of HIV-1 provirus by inhibiting the pathways specifically. Our results indicated that HIV-1 gp120/DC-SIGN stimulation reactivates latent HIV-1 provirus via the NF-κB signal pathway.
Cai, Minchao; Zhou, Tong; Wang, Xuan; Shang, Minghua; Zhang, Yueyue; Luo, Maocai; Xu, Chundi; Yuan, Weijie
Podocytes, the main target of immune complex, participate actively in the development of glomerular injury as immune cells. Dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) is an innate immune molecular that has an immune recognition function, and is involved in mediation of cell adhesion and immunoregulation. Here we explored the expression of DC-SIGN on podocytes and its role in immune and inflammatory responses in lupus nephritis (LN). Expression of DC-SIGN and immunoglobulin (Ig)G1 was observed in glomeruli of LN patients. DC-SIGN was co-expressed with nephrin on podocytes. Accompanied by increased proteinuria of LN mice, DC-SIGN and IgG1 expressions were observed in the glomeruli from 20 weeks, and the renal function deteriorated up to 24 weeks. Mice with anti-DC-SIGN antibody showed reduced proteinuria and remission of renal function. After the podocytes were stimulated by serum of LN mice in vitro, the expression of DC-SIGN, major histocompatibility complex (MHC) class II and CD80 was up-regulated, stimulation of T cell proliferation was enhanced and the interferon (IFN)-γ/interleukin (IL)-4 ratio increased. However, anti-DC-SIGN antibody treatment reversed these events. These results suggested that podocytes in LN can exert DC-like function through their expression of DC-SIGN, which may be involved in immune and inflammatory responses of renal tissues. However, blockage of DC-SIGN can inhibit immune functions of podocytes, which may have preventive and therapeutic effects.
谢荣理; 徐海燕; 祁梦之; 毛恩强; 陈尔真; 周同; 聂红; 费健
[Abstrective] Objective To investigate the trans-differentiation of pancreatic acinar cell in acute pancreatitis (AP) by detection of the expression of transmembrane protein that is dendritic cell-specific intercellular adhesion molecule 3-grab-bing non-integrin (DC-SIGN). Methods An in vitro study was conducted using AR42J cell line for establishing the cell model of AP. The expression level of DC-SIGN protein was measured by flow cytometry. The transcription level of DC-SIGN mRNA was detected by RT-PCR. Results DC-SIGN in early phase of AP was characterized by high expression in gene and protein level ( P<0 . 05 ) . Conclusions The high expression of DC-SIGN on pancreatic acinar cells during AP demonstrates the epithelial-dendritic cell trans-differentiation.%目的：检测跨膜蛋白DC-SIGN在急性胰腺炎中的表达，探讨急性胰腺炎胰腺腺泡细胞的转分化现象。方法：采用AR42J细胞株建立急性胰腺炎的体外细胞模型。流式细胞法检测细胞表面DC-SIGN蛋白的表达量，RT-PCR检测DC-SIGN mRNA 转录水平。结果：在蛋白质和基因水平，腺泡细胞 DC-SIGN 在急性胰腺炎早期高表达（P<0.05）。结论：急性胰腺炎胰腺腺泡细胞DC-SIGN高表达，表明存在上皮-树突状细胞转分化现象。
Simon, Ayo Y; Sutherland, Michael R; Pryzdial, Edward L G
Dengue virus (DENV) infection causes ∼200 million cases of severe flulike illness annually, escalating to life-threatening hemorrhagic fever or shock syndrome in ∼500,000. Although thrombocytopenia is typical of both mild and severe diseases, the mechanism triggering platelet reduction is incompletely understood. As a probable initiating event, direct purified DENV-platelet binding was followed in the current study by quantitative reverse transcription-polymerase chain reaction and confirmed antigenically. Approximately 800 viruses specifically bound per platelet at 37°C. Fewer sites were observed at 25°C, the blood bank storage temperature (∼350 sites), or 4°C, known to attenuate virus cell entry (∼200 sites). Dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN) and heparan sulfate proteoglycan were implicated as coreceptors because only the combination of anti-DC-SIGN and low-molecular-weight heparin prevented binding. Interestingly, at 37°C and 25°C, platelets replicated the positive sense single-stranded RNA genome of DENV by up to ∼4-fold over 7 days. Further time course experiments demonstrated production of viral NS1 protein, which is known to be highly antigenic in patient serum. The infectivity of DENV intrinsically decayed in vitro, which was moderated by platelet-mediated generation of viable progeny. This was shown using a transcription inhibitor and confirmed by freeze-denatured platelets being incapable of replicating the DENV genome. For the first time, these data demonstrate that platelets directly bind DENV saturably and produce infectious virus. Thus, expression of antigen encoded by DENV is a novel consideration in the pathogen-induced thrombocytopenia mechanism. These results furthermore draw attention to the possibility that platelets may produce permissive RNA viruses in addition to DENV.
Balboa, Luciana; Romero, María Mercedes; Yokobori, Noemí; Schierloh, Pablo; Geffner, Laura; Basile, Juan I; Musella, Rosa M; Abbate, Eduardo; de la Barrera, Silvia; Sasiain, María C; Alemán, Mercedes
During a chronic infection such as tuberculosis, the pool of tissue dendritic cells (DC) must be renewed by recruitment of both circulating DC progenitors and monocytes (Mo). However, the microenvironment of the inflammatory site affects Mo differentiation. As DC are critical for initiating a Mycobacterium tuberculosis-specific T-cell response, we argue that interference of M. tuberculosis with a correct DC generation would signify a mechanism of immune evasion. In this study, we showed that early interaction of γ-irradiated M. tuberculosis with Mo subverts DC differentiation in vitro. We found that irradiated M. tuberculosis effect involves (1) the loss of a significant fraction of monocyte population and (2) an altered differentiation process of the surviving monocyte subpopulation. Moreover, in the absence of irradiated M. tuberculosis, DC consist in a major DC-specific intercellular adhesion molecule 3-grabbing non-integrin receptor (DC-SIGN(high))/CD86(low) and minor DC-SIGN(low)/CD86(high) subpopulations, whereas in the presence of bacteria, there is an enrichment of DC-SIGN(low)/CD86(high) population. Besides, this population enlarged by irradiated M. tuberculosis, which is characterized by a reduced CD1b expression, correlates with a reduced induction of specific T-lymphocyte proliferation. The loss of CD1molecules partially involves toll-like receptors (TLR-2)/p38 MAPK activation. Finally, several features of Mo, which have been differentiated into DC in the presence of irradiated M. tuberculosis, resemble the features of DC obtained from patients with active tuberculosis. In conclusion, we suggest that M. tuberculosis escapes from acquired immune response in tuberculosis may be caused by an altered differentiation into DC leading to a poor M. tuberculosis-specific T-cell response.
Bene, Krisztián P; Kavanaugh, Devon W; Leclaire, Charlotte; Gunning, Allan P; MacKenzie, Donald A; Wittmann, Alexandra; Young, Ian D; Kawasaki, Norihito; Rajnavolgyi, Eva; Juge, Nathalie
The vertebrate gut symbiont Lactobacillus reuteri exhibits strain-specific adhesion and health-promoting properties. Here, we investigated the role of the mucus adhesins, CmbA and MUB, upon interaction of L. reuteri ATCC PTA 6475 and ATCC 53608 strains with human monocyte-derived dendritic cells (moDCs). We showed that mucus adhesins increased the capacity of L. reuteri strains to interact with moDCs and promoted phagocytosis. Our data also indicated that mucus adhesins mediate anti- and pro-inflammatory effects by the induction of interleukin-10 (IL-10), tumor necrosis factor alpha (TNF-α), IL-1β, IL-6, and IL-12 cytokines. L. reuteri ATCC PTA 6475 and ATCC 53608 were exclusively able to induce moDC-mediated Th1 and Th17 immune responses. We further showed that purified MUB activates moDCs and induces Th1 polarized immune responses associated with increased IFNγ production. MUB appeared to mediate these effects via binding to C-type lectin receptors (CLRs), as shown using cell reporter assays. Blocking moDCs with antibodies against DC-specific intercellular adhesion molecule 3-grabbing non-integrin (DC-SIGN) or Dectin-2 did not affect the uptake of the MUB-expressing strain, but reduced the production of TNF-α and IL-6 by moDCs significantly, in line with the Th1 polarizing capacity of moDCs. The direct interaction between MUB and CLRs was further confirmed by atomic force spectroscopy. Taken together these data suggest that mucus adhesins expressed at the cell surface of L. reuteri strains may exert immunoregulatory effects in the gut through modulating the Th1-promoting capacity of DCs upon interaction with C-type lectins.
Marijke M F Alen
Full Text Available BACKGROUND: Dendritic cells (DC, present in the skin, are the first target cells of dengue virus (DENV. Dendritic cell-specific intercellular adhesion molecule 3-grabbing non-integrin (DC-SIGN is present on DC and recognizes N-glycosylation sites on the E-glycoprotein of DENV. Thus, the DC-SIGN/E-glycoprotein interaction can be considered as an important target for inhibitors of viral replication. We evaluated various carbohydrate-binding agents (CBAs against all four described serotypes of DENV replication in Raji/DC-SIGN(+ cells and in monocyte-derived DC (MDDC. METHODOLOGY/PRINCIPAL FINDINGS: A dose-dependent anti-DENV activity of the CBAs Hippeastrum hybrid (HHA, Galanthus nivalis (GNA and Urtica dioica (UDA, but not actinohivin (AH was observed against all four DENV serotypes as analyzed by flow cytometry making use of anti-DENV antibodies. Remarkably, the potency of the CBAs against DENV in MDDC cultures was significantly higher (up to 100-fold than in Raji/DC-SIGN(+ cells. Pradimicin-S (PRM-S, a small-size non-peptidic CBA, exerted antiviral activity in MDDC but not in Raji/DC-SIGN(+ cells. The CBAs act at an early step of DENV infection as they bind to the viral envelope of DENV and subsequently prevent virus attachment. Only weak antiviral activity of the CBAs was detected when administered after the virus attachment step. The CBAs were also able to completely prevent the cellular activation and differentiation process of MDDC induced upon DENV infection. CONCLUSIONS/SIGNIFICANCE: The CBAs exerted broad spectrum antiviral activity against the four DENV serotypes, laboratory-adapted viruses and low passage clinical isolates, evaluated in Raji/DC-SIGN(+ cells and in primary MDDC.
Arrighi, Jean-François; Pion, Marjorie; Wiznerowicz, Maciej; Geijtenbeek, Teunis B; Garcia, Eduardo; Abraham, Shahnaz; Leuba, Florence; Dutoit, Valérie; Ducrey-Rundquist, Odile; van Kooyk, Yvette; Trono, Didier; Piguet, Vincent
In the early events of human immunodeficiency virus type 1 (HIV-1) infection, immature dendritic cells (DCs) expressing the DC-specific intercellular adhesion molecule 3-grabbing nonintegrin (DC-SIGN) receptor capture small amounts of HIV-1 on mucosal surfaces and spread viral infection to CD4(+) T cells in lymph nodes (22, 34, 45). RNA interference has emerged as a powerful tool to gain insight into gene function. For this purpose, lentiviral vectors that express short hairpin RNA (shRNA) for the delivery of small interfering RNA (siRNA) into mammalian cells represent a powerful tool to achieve stable gene silencing. In order to interfere with DC-SIGN function, we developed shRNA-expressing lentiviral vectors capable of conditionally suppressing DC-SIGN expression. Selectivity of inhibition of human DC-SIGN and L-SIGN and chimpanzee and rhesus macaque DC-SIGN was obtained by using distinct siRNAs. Suppression of DC-SIGN expression inhibited the attachment of the gp120 envelope glycoprotein of HIV-1 to DC-SIGN transfectants, as well as transfer of HIV-1 to target cells in trans. Furthermore, shRNA-expressing lentiviral vectors were capable of efficiently suppressing DC-SIGN expression in primary human DCs. DC-SIGN-negative DCs were unable to enhance transfer of HIV-1 infectivity to T cells in trans, demonstrating an essential role for the DC-SIGN receptor in transferring infectious viral particles from DCs to T cells. The present system should have broad applications for studying the function of DC-SIGN in the pathogenesis of HIV as well as other pathogens also recognized by this receptor.
Full Text Available Objective/Background: Mycobacterium lepraemurium (MLM, the etiologic agent of murine leprosy, is an intracellular parasite of macrophages; the mechanism used by this bacterium to enter macrophages is not known. The fate of the MLM phagosome inside macrophages is also unknown. This study was conducted to investigate how MLM enters macrophages and to define the maturation process of MLM phagosome inside macrophages. Materials and Methods: Peritoneal macrophages were incubated in the presence of mannan–bovine serum albumin (BSA, and antibodies to known macrophage receptors, including, anti-FcγRIII/RII (anti-CD16/32, anti-CD35 (anti-CR1, anti-TLR2, anti-TLR4, anti-TLR6, anti-CD14, and anti-dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN. Then, macrophages were challenged with Iris Fuchsia-stained MLM, at a multiplicity of infection of 50:1. The blocking effect of the antibodies (and mannan–BSA used was analyzed using direct microscopy and flow cytometry. The maturation process of MLM phagosomes was visualized by their interaction with antibodies to Rab5, Rab7, proton ATPase, and cathepsin D, by confocal microscopy. Results: Only mannan–BSA and anti-TLR6 antibody significantly blocked the entry of MLM into macrophages. None of the other antibodies, including that for DC-SIGN, meaningfully inhibited the endocytic process. We also found that MLM is a fusiogenic mycobacterium. This was deduced from the orderly association of MLM phagosomes with Rab5, Rab7, Proton ATPase, and lysosomes (cathepsin D. Conclusion: Fusion of MLM phagosomes with lysosomes seems to be a necessary event for the intracellular multiplication of MLM; similar to Mycobacterium leprae, this microorganism hardly grows on artificial, synthetic, bacteriologic media.
de Geus, Eveline D; Tefsen, Boris; van Haarlem, Daphne A; van Eden, Willem; van Die, Irma; Vervelde, Lonneke
To increase our understanding of the interaction between avian influenza virus and its chicken host, we identified receptors for putative avian influenza virus (AIV) glycan determinants on chicken dendritic cells. Chicken dendritic cells (DCs) were found to recognize glycan determinants containing terminal αGalNAc, Galα1-3Gal, GlcNAcβ1-4GlcNAcβ1-4GlcNAcβ (chitotriose) and Galα1-2Gal. Infection of chicken dendritic cells with either low pathogenic (LP) or highly pathogenic (HP) AIV results in elevated mRNA expression of homologs of the mouse C-type lectins DEC205 and macrophage mannose receptor (MMR), whereas expression levels of the human dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) homolog remained unchanged. Following uptake and subsequent presentation of avian influenza virus by DCs, adaptive immunity, including humoral immune responses are induced. We have investigated the antibody responses against virus glycan epitopes after avian influenza virus infection. Using glycan micro-array analysis we showed that chicken contained antibodies that predominantly recognize terminal Galα1-3Gal-R, chitotriose and Fucα1-2Galβ1-4GlcNAc-R (H-type 2). After influenza-infection, glycan array analysis showed that both levels and repertoire of glycan-recognizing antibodies decreased. However, analysis of the sera by ELISA indicated that the levels of different isotypes of anti-glycan Abs against specific glycan antigens was increased after influenza-infection, suggesting that the presentation of the glycan antigens and iso-type of the Abs are critical parameters to take into account when measuring anti-glycan Abs. This novel approach in avian influenza research may contribute to the development of a broad spectrum vaccine and improves our mechanistic understanding of innate and adaptive responses to glycans.
Full Text Available Surfactant protein D (SP-D is a soluble C-type lectin, belonging to the collectin (collagen-containing calcium-dependent lectin family, which acts as an innate immune pattern recognition molecule in the lungs at other mucosal surfaces. Immune regulation and surfactant homeostasis are salient functions of SP-D. SP-D can bind to a range of viral, bacterial, and fungal pathogens and trigger clearance mechanisms. SP-D binds to gp120, the envelope protein expressed on HIV-1, through its C-type lectin or carbohydrate recognition domain. This is of importance since SP-D is secreted by human mucosal epithelial cells and is present in the female reproductive tract, including vagina. Another C-type lectin, dendritic cell (DC-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN, present on the surface of the DCs, also binds to HIV-1 gp120 and facilitates viral transfer to the lymphoid tissues. DCs are also present at the site of HIV-1 entry, embedded in vaginal or rectal mucosa. In the present study, we report a direct protein–protein interaction between recombinant forms of SP-D (rfhSP-D and DC-SIGN via their C-type lectin domains. Both SP-D and DC-SIGN competed for binding to immobilized HIV-1 gp120. Pre-incubation of human embryonic kidney cells expressing surface DC-SIGN with rfhSP-D significantly inhibited the HIV-1 transfer to activated peripheral blood mononuclear cells. In silico analysis revealed that SP-D and gp120 may occupy same sites on DC-SIGN, which may explain the reduced transfer of HIV-1. In summary, we demonstrate, for the first time, that DC-SIGN is a novel binding partner of SP-D, and this interaction can modulate HIV-1 capture and transfer to CD4+ T cells. In addition, the present study also reveals a novel and distinct mechanism of host defense by SP-D against HIV-1.
Guang-Ying Cui; Hong-Yan Diao
BACKGROUND: Hepatitis B virus (HBV) is a hepatotropic, noncytopathic, DNA virus which can cause acute and chronic infection. Viral persistence is associated with a weak or absent speciifc immune responses to HBV, particularly the cellular immune response. Dendritic cells (DCs) are professional antigen-presenting cells with a unique T cell stimulatory aptitude that play a crucial role in the instruction of adaptive immune responses upon infection. An impaired function of DCs was suggested by recent studies to account for the T and B cell hyporesponsiveness in chronic HBV infection. This review summarizes recent insights into the recognition of HBV antigens by DCs. DATA SOURCES: Studies were identiifed by searching MEDLINE and/or PubMed for articles using the key words"hepatitis B virus (HBV)","dendritic cells","C-type lectins","mannose receptor","toll-like receptor", and "dendritic cell-speciifc intercellular-adhesion-molecule-3 grabbing nonintegrin (DC-SIGN)"up to December 2009. Additional papers were identiifed by a manual search of the references from the key articles. RESULTS:DCs play an important role in the progress of hepatitis B, especially in the recognition of HBV. There are three main ways of recognition of HBV antigens by DCs. First, HBV DNA can be recognized by DCs through toll-like receptor 9 (TLR9) which activates the NF-κB signal pathway and p38 MAPK to up-regulate the expression of interferon (IFN) regulatory factor 7 (IRF-7) in a manner independent of type I IFN signaling, resulting in secretion of type I IFN and inlfammatory cytokines, and induction of DC maturation and the adaptive immune response. Second, HBc/HBeAg cannot be recognized by DCs, but DNA or ssRNA encapsulated within HBcAg can be internalized by DCs through TLRs. Third, HBsAg can be internalized by DCs through the mannose receptor, which lacks the ability to induce DC maturation without the assistance of DC-SIGN. Meanwhile, there is some cross-talk among the three
Emily E I M Mouser
Full Text Available One of the hallmarks of HIV-1 disease is the association of heightened CD4+ T-cell activation with HIV-1 replication. Parasitic helminths including filarial nematodes have evolved numerous and complex mechanisms to skew, dampen and evade human immune responses suggesting that HIV-1 infection may be modulated in co-infected individuals. Here we studied the effects of two filarial nematode products, adult worm antigen from Brugia malayi (BmA and excretory-secretory product 62 (ES-62 from Acanthocheilonema viteae on HIV-1 infection in vitro. Neither BmA nor ES-62 influenced HIV-1 replication in CD4+ enriched T-cells, with either a CCR5- or CXCR4-using virus. BmA, but not ES-62, had the capacity to bind the C-type lectin dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN thereby inhibiting HIV-1 trans-infection of CD4+ enriched T-cells. As for their effect on DCs, neither BmA nor ES-62 could enhance or inhibit DC maturation as determined by CD83, CD86 and HLA-DR expression, or the production of IL-6, IL-10, IL-12 and TNF-α. As expected, due to the unaltered DC phenotype, no differences were found in CD4+ T helper (Th cell phenotypes induced by DCs treated with either BmA or ES-62. Moreover, the HIV-1 susceptibility of the Th-cell populations induced by BmA or ES-62 exposed DCs was unaffected for both CCR5- and CXCR4-using HIV-1 viruses. In conclusion, although BmA has the potential capacity to interfere with HIV-1 transmission or initial viral dissemination through preventing the virus from interacting with DCs, no differences in the Th-cell polarizing capacity of DCs exposed to BmA or ES-62 were observed. Neither antigenic source demonstrated beneficial or detrimental effects on the HIV-1 susceptibility of CD4+ Th-cells induced by exposed DCs.