Lex Antigen Research Articles

Lewis x-carrying O-glycans are candidate modulators for conceptus attachment in pigs†.

Successful attachment of conceptus to the uterine luminal epithelium (LE) is crucial for establishing a functional placenta in pigs. However, the underlying mechanisms are yet to be elucidated. The uterine LE-conceptus interface is enriched in various glycoconjugates essential to implantation. Using MALDI-MS profiling, we identified for the first time the O-glycan repertoire of pig endometrium during the conceptus attachment stage. The expression pattern of blood group A, O(H), Lewis x, y, a, b (Lex, Ley, Lea, and Leb), the sialylated and sulfated Lex antigens in the uterine LE-conceptus interface was assessed using immunofluorescence assays. Notably, the Lex-carrying O-glycans exhibited a temporal-spatial expression pattern. They were absent in the endometrium on estrous cycle days but strongly and spatially presented in the conceptus and uterine LE to which the conceptus apposes during the early conceptus attachment stage. In addition, Lex-carrying O-glycans were co-localized with secreted phosphoprotein 1 (SPP1), a well-characterized factor that plays a role in promoting conceptus attachment through interacting with integrin αVβ3 and integrin αVβ6. Meanwhile, the immunoprecipitation assays revealed an interaction between the Lex-carrying O-glycans and SPP1, integrin αV, and integrin β6. Furthermore, we provided evidence that the β1,4-galactosyltransferase 1 (B4GALT1) gene is a potential regulator for Lex antigen expression in the uterine LE-conceptus interface during the early conceptus attachment stage. In conclusion, our findings show that Lex-carrying O-glycans, presumably dependent on B4GALT1 gene expression, might modulate conceptus attachment by interacting with the SPP1-integrin receptor complex in pigs.

Antagonistic Activities of Lactobacillus rhamnosus JB3 Against Helicobacter pylori Infection Through Lipid Raft Formation.

Helicobacter pylori is a Gram-negative pathogen that can increase the risk of stomach cancer in infected patients. H. pylori exploits lipid rafts to infect host cells. Infection triggers clustering of Lewis x antigen (Lex) and integrins in lipid rafts to facilitate H. pylori adherence to the gastric epithelium. H. pylori infection can be treated with probiotics containing lactic acid bacteria that offer numerous benefits to the host while lacking the side effects associated with antibiotic therapy. Previously, we showed that the cell-free supernatant (CFS) derived from Lactobacillus rhamnosus JB3 (LR-JB3) at a multiplicity of infection (MOI) of 25 attenuated the pathogenicity of H. pylori. In this study, we established a mucin model to simulate the gastric environment and to further understand the influence of mucin on the pathogenesis of H. pylori. Porcine stomach mucin dramatically upregulated H. pylori virulence gene expression, including that of babA, sabA, fucT, vacA, hp0499, cagA, and cagL, as well as the adhesion and invasion ability of H. pylori and induced increased levels of IL-8 in infected-AGS cells. The CFS derived from LR-JB3 at a MOI of 25 reduced the expression of H. pylori sabA, fucT, and hp0499 in mucin, as well as that of the Lex antigen and the α5β1 integrin in AGS cells during co-cultivation. These inhibitory effects of LR-JB3 also suppressed lipid raft clustering and attenuated Lewis antigen-dependent adherence, type IV secretion system-mediated cell contact, and lipid raft-mediated entry of VacA to host cells. In conclusion, LR-JB3 could affect H. pylori infection through mediating lipid raft formation of the host cells. The currently unknown cues secreted from LR-JB3 are valuable not only for treating H. pylori infection, but also for treating diseases that are also mediated by lipid raft signaling, such as cancer and aging-associated and neurodegenerative conditions.

Lactobacillus rhamnosus JB3 inhibits Helicobacter pylori infection through multiple molecular actions.

Eradication of Helicobacter pylori infection is the most direct and effective way for preventing gastric cancer. Lactic acid bacteria are considered as alternative therapeutic agents against H.pylori infection. Effects of Lactobacillus rhamnosus JB3 (LR-JB3) on the virulence gene expression of H.pylori and infection-induced cellular responses of AGS cells were investigated by co-cultivating infected AGS cells with different multiplicity of infections (MOIs) of LR-JB3. LR-JB3, specifically at a MOI of 25, suppressed the association ability of H.pylori and its induced IL-8 levels, as well as the mRNA levels of vacA, sabA, and fucT of H.pylori, infection-induced Lewis (Le)x antigen and Toll-like receptor 4 (TLR4) expressions in AGS cells. However, the apoptosis mediated by infection was inhibited by LR-JB3 in a dose-dependent manner. In addition, autoinducer (AI)-2 was observed to have increased the association ability and fucT expression of H.pylori, and Lex antigen and TLR4 expression of AGS cells. Interestingly, an unknown bioactive cue was hypothesized to have been secreted from LR-JB3 at a MOI of 25 to act as an antagonist of AI-2. LR-JB3 possesses various means to interfere with H.pylori pathogenesis and infection-induced cellular responses of AGS cells to fight against infection.

Recognition of Dimeric Lewis X by Anti-Dimeric Lex Antibody SH2.

The carbohydrate antigen dimeric Lewis X (DimLex), which accumulates in colonic and liver adenocarcinomas, is a valuable target to develop anti-cancer therapeutics. Using the native DimLex antigen as a vaccine would elicit an autoimmune response against the Lex antigen found on normal, healthy cells. Thus, we aim to study the immunogenic potential of DimLex and search internal epitopes displayed by DimLex that remain to be recognized by anti-DimLex monoclonal antibodies (mAbs) but no longer possess epitopes recognized by anti-Lex mAbs. In this context, we attempted to map the epitope recognized by anti-DimLex mAb SH2 by titrations and competitive inhibition experiments using oligosaccharide fragments of DimLex as well as Lex analogues. We compare our results with that reported for anti-Lex mAb SH1 and anti-polymeric Lex mAbs 1G5F6 and 291-2G3-A. While SH1 recognizes an epitope localized to the non-reducing end Lex trisaccharide, SH2, 1G5F6, and 291-2G3-A have greater affinity for DimLex conjugates than for Lex conjugates. We show, however, that the Lex trisaccharide is still an important recognition element for SH2, which (like 1G5F6 and 291-2G3-A) makes contacts with all three sugar units of Lex. In contrast to mAb SH1, anti-polymeric Lex mAbs make contact with the GlcNAc acetamido group, suggesting that epitopes extend further from the non-reducing end Lex. Results with SH2 show that this epitope is only recognized when DimLex is presented by glycoconjugates. We have reported that DimLex adopts two conformations around the β-d-GlcNAc-(1→3)-d-Gal bond connecting the Lex trisaccharides. We propose that only one of these conformations is recognized by SH2 and that this conformation is favored when the hexasaccharide is presented as part of a glycoconjugate such as DimLex-bovine serum albumin (DimLex-BSA). Proper presentation of the oligosaccharide candidate via conjugation to a protein or lipid is essential for the design of an anti-cancer vaccine or immunotherapeutic based on DimLex.

Comparative immunological studies of tumor-associated Lewis X, Lewis Y, and KH-1 antigens

Tumor-associated carbohydrate antigens Lewis X (Lex), Lewis Y (Ley), and KH-1 are useful targets for cancer immunotherapy. In this regard, an insight into the structure-immunogenicity relationships of these antigens is important but this has not been systematically investigated yet. In the current study, Lex, Ley, and KH-1 antigens with a lactose unit at the reducing end as a spacer were synthesized and coupled with keyhole limpet hemocyanin (KLH) protein. Immunological evaluations of the resultant conjugates revealed that they all could elicit robust immune responses whilst the Ley conjugate could provoke the highest titers of total and IgG antibodies. The binding assays of their antisera to each antigen and to cancer cells showed that each antiserum had extensive cross-reaction with all three antigens as protein conjugates and strong but somewhat antigen-selective binding towards MCF-7 cancer cell. Moreover, none of these antisera had obvious binding to SKMEL-28 cancer cell that does not express Lex, Ley and KH-1. The results of assays of these antisera to mediate complement-dependent cytotoxicity (CDC) to MCF-7 and SKMEL-28 cancer cells were very similar to the results of binding assays. Thus, it was concluded that all three antigens could form effective conjugate vaccines whereas the Ley conjugate induced the most robust immune responses and the antiserum of Lex had the highest binding and cytotoxicity to target cancer cells. In addition, as the antibodies induced by each antigen had extensive cross-reaction with other two antigens, either Lex or Ley or the two combined can be utilized to formulate effective conjugate vaccines for cancer immunotherapy. Another paradigm-shifting discovery of this study is that the presentation of Lex, Ley, and KH-1 antigens on cancer cell can be different from that in synthetic conjugates, which should be taken into consideration during the design and optimization of related cancer vaccines or immunotherapies.

Synthesis of daunorubicin conjugates with fragments of H type 5, Lea, Lex antigens and N-fucoglycan

Daunorubicin was conjugated with spacered N-glycosides of di- and trisaccharides containing terminal α-l-fucopyranose residues. The synthesis was carried out by N-monoalkylation of daunorubicin hydrochloride (1) in aqueous DMF in the presence of NaHCO3 using N-β-glycoside N-bromoacetylglycyl derivatives, namely, α-l-Fucp-(1→2)-β-d-Galp-(1→4)-β-d-Glcp-NHCOCH2NHCOCH2Br (2a), α-l-Fucp-(1→4)-[β-d-Galp-(1→3)]-β-d-GlcpNAc-NHCOCH2NHCOCH2Br (3a), α-l-Fucp-(1→3)-β-d-GlcpNAc-NHCOCH2NHCOCH2Br (4a), and α-l-Fucp-(1→6)-β-d-GlcpNAc-NHCOCH2NHCOCH2Br (5a). The conjugates of daunorubicin were obtained as hydrochlorides (2b-5b) in 40% yield. Their oligosaccharide components are fragments of H type 5, Lea, Lex antigens and N-fucolglycan, respectively. 0(I) Erythrocytes hemagglutination inhibition assay was performed with conjugates 2b–5b and Ulex europaeus (UEA 1), Lotus tetragonolobus (LTA), and Laburnum anagyroides (LAA) plant fucolectins.

Synthesis of LacNAcLex‐ and DimLex‐BSA Conjugates and Binding to Anti‐Polymeric Lex mAbs

The chemical synthesis of tetra‐ and pentasaccharide fragments of the tumor‐associated carbohydrate antigen dimeric Lewis X (dimLex) lacking either both or only the non‐reducing end fucosyl residues is described following a 1 + 1 + 1 synthetic strategy. Use of a 6‐chlorohexyl aglycon gave access to hexyl glycoside soluble inhibitors as well as the 6‐aminohexyl glycoside pentasaccharide. The 6‐aminohexyl glycoside pentasaccharide and a dimLex analogue were conjugated to BSA via a squarate linker and the glycoconjugates were shown by MALDI MS to both display an average of 16 oligosaccharides per BSA molecule. These glycoconjugates were used in the attempt to identify the smallest dimLex fragment required to maintain binding to mAbs SH2 and IG5F6, which are known to bind polymeric Lex structures preferentially over the monomeric Lex antigen. Titration studies showed that the non‐reducing end fucosyl residue in dimLex is involved in the recognition of the antigen by both mAbs SH2 and IG5F6.

Saliva as a source of reagent to study human susceptibility to avian influenza H7N9 virus infection

Avian influenza H7N9 viruses are an important public health concern due to their high mortality rate and potentials for future pandemics. We investigated human susceptibility to H7N9 viruses using recombinant H7N9 hemagglutinin (HA) proteins as a probe and found a strong association between H7N9 infections and HA binding among saliva samples from 32 patients and 60 uninfected controls in Jiangsu province, China, during the 2016 epidemic season. We also found that sialyl Lex (SLex) antigen that was recognized by H7N9 HA was associated with H7N9 virus infection. Further analysis suggested that additional saccharide residues adjacent to the SLex moiety may affect the H7N9-binding specificity. Our data suggested that saliva may be a useful reagent to study human susceptibility to avian influenza H7N9 virus, which may impact the disease control and prevention of avian influenza viruses as important human pathogens.

Synthesis of N-glycyl-β-glycopyranosyl amines, derivatives of natural oligosaccharides — glucose analogs of Lex antigen

Treatment of the natural tri-, tetra-, and pentasaccharides, β-d-Galp-(1→4)-[α-l-Fucp-(1→3)]-d-Glcp, α-l-Fucp-(1→2)-β-d-Galp-(1→4)-[α-l-Fucp-(1→3)]-d-Glcp, and α-l-Fucp-(1→2)-[α-d-GalNAcp-(1→3)]-β-d-Galp-(1→4)-[α-l-Fucp-(1→3)]-d-Glcp, which are glucose analogs of Lex, with ammonium carbamate in aqueous methanol gave the corresponding β-glycopyranosyl amines. After their N-acylation with N-Z-glycine N-hydroxysuccinimidyl ester (Z is benzyloxycarbonyl) with subsequent hydrogenolytic removal of Z-group, corresponding N-glycyl-β-glycopyranosyl amines were obtained in yields up to 70%.

Synthesis of benzaldehyde-functionalized LewisX trisaccharide analogs for glyco-SAM formation

LewisX (Lex) antigen based carbohydrate–carbohydrate interactions are mediated by complexation of metal ions. Although theoretical studies about the influence of participating hydroxyl groups in the Lex trisaccharide head group (Galβ(1-4)[Fucα(1-3)]GlcNAc) could gave same rudimental information about the basic mechanism behind this interaction, a little is known about orientation and configuration of the hydroxyl groups required for the specific interaction mediated by Ca2+ complexation. Therefore, there is a need of non-natural derivatives to provide detailed information about the requirements for hydroxyl group arrangement in Lex head group surface plasmon resonance and gold nanoparticle techniques have shown to be powerful tools to investigate carbohydrate–carbohydrate interactions. Benzaldehyde-functionalized glycans can be used for attachment to both gold nanoparticles and surface plasmon resonance sensor surfaces. Therefore, seven benzaldehyde equipped Lex analogs including the natural trisaccharide were synthesized utilizing convergent approach. The derivatives were applied in ongoing carbohydrate–carbohydrate interaction studies by surface plasmon resonance experiments to prove theoretical postulate about the structural requirements of hydroxyl group arrangements in Lex trisaccharides.

Understanding the Recognition of Lewis X by Anti-Lex Monoclonal Antibodies

The recognition of the Le(x) antigen by the anti-Le(x) monoclonal antibody (mAb) SH1 was studied by ELISA using a panel of 4″-modified Le(x) analogues. We confirmed that these analogues maintained the stacked conformation adopted by natural Le(x) antigen using 1D ROESY experiments and measuring intramolecular distances. Our binding studies show that the 4-OH″ of galactose behaves as an H-bond donor to an electronegative amino acid side chain in the SH1 binding site. While removal of this H-bond leads to reduced inhibition, disturbing the hydrophobic α face of the β-galactosyl residue leads to complete loss of binding to SH1. We compared our results to the crystal structure of the Fab fragment of anti-Le(x) mAb 291-2G3-A complexed with Le(x) (PDB entry 1UZ8 ). While no H-bond involving the 4-OH″ was described, hydrophobic interactions between a tryptophan residue and the β-galactoside α face are observed. We conclude that the hydrophobic α face that is uniquely displayed by β-galactosyl residues is essential to the recognition of the Le(x) antigen by anti-Le(x) antibodies.

Real-Time Label Free Analysis of Native Bacterial Cells Binding to Carbohydrate Microarray

We present a novel experimental system based on glycoconjugates microarray and oblique-incidence reflectivity difference (OI-RD) microscopy to analyze binding of the onco-pathogen Helicobacter pylori to surface immobilized carbohydrates. The results confirm the recognized high-affinity binding of H. pylori BabA to the fucosylated Leb antigen, and suggest the presence of additional Leb binding adhesins not previously detected. OI-RD microscopy is a recently developed method for analyses of label-free biomolecules binding to immobilized targets by measuring small changes in phase and amplitude of a reflected optical wave from a solid surface due to the reaction of a solution-phase probe with the target. Besides applications of OI-RD in DNA hybridization, antigen-antibody interactions and small molecule libraries screening, we apply OI-RD microscopy to the binding analyses of whole bacterial cells to their host receptors presented on surfaces. Glycoconjugates microarrays consisting of Lea-HSA, Leb-HSA, Lex-HSA, and Ley-HSA were probed with H. pylori, H. pylori BabA deletion mutant and recombinant BabA protein. H. pylori demonstrated specific binding to Leb antigen, but did not bind to the closely related Lea, Lex or Ley antigens. The specificity in binding to the Leb antigen and not to Lea, Lex or Ley antigens was faithfully reproduced by recombinant BabA protein. Besides, H. pylori BabA deletion mutant does not express BabA and does not bind to Leb-HSA in solution, also demonstrated specific albeit reduced binding to Leb antigen. These results suggest that some H. pylori strains exhibit a complementary Leb-binding activity (independent of BabA) that has not been previously detected. The OI-RD technology with real-time analyses of whole cell bacterial binding to multivalently presented receptors in solid phase combined with magnified sensitivity for weaker adherence properties, offers new possibilities for identification of discrete attachment mechanisms essential for the infectious.

Activity, Splice Variants, Conserved Peptide Motifs, and Phylogeny of Two New α1,3-Fucosyltransferase Families (FUT10 and FUT11)

We report the cloning of three splice variants of the FUT10 gene, encoding for active alpha-l-fucosyltransferase-isoforms of 391, 419, and 479 amino acids, and two splice variants of the FUT11 gene, encoding for two related alpha-l-fucosyltransferases of 476 and 492 amino acids. The FUT10 and FUT11 appeared 830 million years ago, whereas the other alpha1,3-fucosyltransferases emerged 450 million years ago. FUT10-391 and FUT10-419 were expressed in human embryos, whereas FUT10-479 was cloned from adult brain and was not found in embryos. Recombinant FUT10-419 and FUT10-479 have a type II trans-membrane topology and are retained in the endoplasmic reticulum (ER) by a membrane retention signal at their NH(2) termini. The FUT10-479 has, in addition, a COOH-ER membrane retention signal. The FUT10-391 is a soluble protein without a trans-membrane domain or ER retention signal that transiently localizes to the Golgi and then is routed to the lysosome. After transfection in COS7 cells, the three FUT10s and at least one FUT11, link alpha-l-fucose onto conalbumin glycopeptides and biantennary N-glycan acceptors but not onto short lactosaminyl acceptor substrates as do classical monoexonic alpha1,3-fucosyltransferases. Modifications of the innermost core GlcNAc of the N-glycan, by substitution with ManNAc or with an opened GlcNAc ring or by the addition of an alpha1,6-fucose, suggest that the FUT10 transfer is performed on the innermost GlcNAc of the core chitobiose. We can exclude alpha1,3-fucosylation of the two peripheral GlcNAcs linked to the trimannosyl core of the acceptor, because the FUT10 fucosylated biantennary N-glycan product loses both terminal GlcNAc residues after digestion with human placenta alpha-N-acetylglucosaminidase.

Losses of expression of the antigens A, Lea and Lex and over-expression of Ley in carcinomas and HG-SIL of the uterine cervix.

BackgroundThe glycosylation of a great number of molecules, glyco-protein or glycolipids, has been of interest for decades.ObjectiveTo compare the expressive patterns of the isoantigenic determinants of histo-blood groups ABH and Lewis in squamous and simple epithelium and in precursors and cancers of the cervix.MethodsA total of 36 lesions and neoplasms (10 LG-SIL, 16 HG-SIL and 10 invasive carcinomas) have been studied with immunohistochemical techniques, using monoclonal antibodies (MoAb BG1 to BG8) for precursor chains, blood-group ABH and Lewis group Lea, Leb, Lex, and Ley, and four types of lectins. In addition, we have studied the expression of p53 protein and PCNA, establishing the rate of proliferation of each lesion. Using PCR techniques, we have also detected part of the intron of the E6 gene of HPV-16.ResultsIn the invasive cervical carcinomas, we observed a loss of expression of the Lex antigen (p < 0.01). With regard to the progression of the different lesions studied, we found alterations in the patterns of expression of the antigens of the ABH and Lewis blood groups. There was a tendency towards a loss of expression and heterogeneous patterns in the more advanced lesions, as well as over-expression of the Ley antigens. With PCNA, we established a proliferative rate which tended to be greater in relation to the progression of the cervix neoplasms.ConclusionThese results indicate that there is a relation between the losses of histo-blood groups and the progression of the squamous intraepithelial lesions.

Anti-Lewis X Antibody PromotesHelicobacter pyloriAdhesion to Gastric Epithelial Cells

Lewis X (Le(x)) antigen is expressed on the human gastric mucosa and the O-specific chain of lipopolysaccharides of Helicobacter pylori. This antigen can induce autoantibodies, which may be involved in bacterial colonization and thus deserve further investigation. Flow cytometry was used to examine the effects of anti-Le monoclonal antibodies (MAbs) on H. pylori adhesion. A babA2 mutant was also constructed to evaluate the effect of an anti-Le(x) MAb on adhesion. The bacterial agglutination and in situ adhesion assays were used to confirm the anti-Le(x) MAb effect on H. pylori adhesion. This study revealed that an anti-Le(x) MAb, but not an anti-Le(b) MAb or an anti-Le(y) MAb, could enhance the adhesion of H. pylori strains that expressed high levels of Le(x) antigen to AGS cells. The enhancement was not found on an H. pylori strain with a low level of Le(x) antigen. Anti-Le(x) MAb could increase the adhesion of both the wild-type strain and its isogenic babA2 mutant to AGS cells. When AGS cells were pretreated with anti-Le(x) MAb, the adhesion of the babA2 mutant also increased. Only anti-Le(x) MAb could promote bacterial agglutination, and the in situ adhesion assay further confirmed that adding anti-Le(x) MAb resulted in denser bacterial adhesion on the gastric epithelia collected from clinical patients. These results suggest anti-Le(x) MAb could specifically enhance the adhesion abilities of H. pylori strains through a mechanism by which anti-Le(x) MAb promotes bacterial aggregation and mediates bivalent interaction (antigen-antibody-antigen) between bacteria and host cells.

Ultrastructural localization of glycodelin oligosaccharides Le‐x and Le‐y in human seminal vesicles by immunogold staining

Histo-blood group antigens Le-x and Le-y are oligosaccharidic terminals that characterize many glycoproteins in the human tissues. In seminal plasma, they are expressed as part of the so-called glycodelin S, which is suggested to regulate sperm capacitation/decapacitation. It has recently been demonstrated that the core protein of glycodelin S is secreted by seminal vesicles. Here we show that epithelial cells of human seminal vesicles also release the Le-x and Le-y antigens. The presence of these substances in secretory material was revealed by means of an immunogold staining method in normal surgical samples. The results suggest that glycodelin S is secreted by seminal vesicles in its finished glycosylated form. Moreover, antigen reactivity was also revealed associated with plasma membranes.

Three‐dimensional structures of carbohydrate determinants of Lewis system antigens: Implications for effective antibody targeting of cancer

Lewis system carbohydrate antigens have been shown to be expressed at high levels in many cancers of epithelial cell origin, including those of colon, breast, lung, prostate and ovary. The type 1 (Le(a) and Le(b)) antigens are important histo-blood groups, while type 2 (Le(x) and Le(y)) antigens in healthy individuals are only expressed, at relatively low levels, by a few tissues, including some epithelial cells. Thus, the type 2 antigens are considered to be tumour-associated antigens and are promising targets for cancer treatment, including antibody-based immunotherapy. In this review, we discuss the conformational characteristics of the free and bound forms of Lewis oligosaccharides and the 3D structures of antibodies in complex with Le(y) and Le(x) antigens. Collectively, the structural studies have demonstrated that the Lewis determinants are rigid structures, which generally maintain the same conformation in the free and bound states. The rigid nature and similarities in shape of type 1 and 2 Lewis oligosaccharides appear to make them perfectly suited to driving a structurally convergent immune response (at least in the case of Le(y) specific antibodies) toward a highly specific recognition of individual carbohydrate determinants, which is a goal in the development of effective antibody-based cancer treatments.

Multipotentiality, homing properties, and pyramidal neurogenesis of CNS‐derived LeX(ssea‐1) + /CXCR4 + stem cells

Achieving efficient distribution of neural stem cells throughout the central nervous system (CNS) and robust generation of specific neurons is a major challenge for the development of cell-mediated therapy for neurodegenerative diseases. We isolated a primitive neural stem cell subset, double positive for LeX(Le) and CXCR4(CX) antigens that possesses CNS homing potential and extensive neuronal repopulating capacity. Le+CX+ cells are multipotential and can generate neurons as well as myogenic and endothelial cells. In vivo Le+CX+ cells displayed widespread incorporation and differentiated into cortical and hippocampal pyramidal neurons. Since intravenous delivery could be a less invasive route of transplantation, we investigated whether Le+CX+ cells could migrate across endothelial monolayers. Intracerebral coadministration of SDF enabled migration of intravenously injected Le+CX+ cells into the CNS and a small, yet significant, number of donor cells differentiated into neurons. The isolation of a specific neural stem cell population could offer major advantages to neuronal replacement strategies.

Molecular Basis of the Differences in Binding Properties of the Highly Related C-type Lectins DC-SIGN and L-SIGN to Lewis X Trisaccharide and Schistosoma mansoni Egg Antigens

The dendritic cell-specific C-type lectin DC-SIGN functions as a pathogen receptor that recognizes Schistosoma mansoni egg antigens through its major glycan epitope Galbeta1,4(Fucalpha1,3)GlcNAc (Lex). Here we report that L-SIGN, a highly related homologue of DC-SIGN found on liver sinusoidal endothelial cells, binds to S. mansoni egg antigens but not to the Lex epitope. L-SIGN does bind the Lewis antigens Lea, Leb, and Ley, similar as DC-SIGN. A specific mutation in the carbohydrate recognition domain of DC-SIGN (V351G) abrogates binding to all Lewis antigens. In L-SIGN Ser363 is present at the corresponding position of Val351 in DC-SIGN. Replacement of this Ser into Val resulted in a "gain of function" L-SIGN mutant that binds to Lex, and shows increased binding to the other Lewis antigens. These data indicate that Val351 is important for the fucose specificity of DC-SIGN. Molecular modeling and docking of the different Lewis antigens in the carbohydrate recognition domains of L-SIGN, DC-SIGN, and their mutant forms, demonstrate that Val351 in DC-SIGN creates a hydrophobic pocket that strongly interacts with the Fucalpha1,3/4-GlcNAc moiety of the Lewis antigens. The equivalent amino acid residue Ser363 in L-SIGN creates a hydrophilic pocket that prevents interaction with Fucalpha1,3-GlcNAc in Lex but supports interactions with the Fucalpha1,4-GlcNAc moiety in Lea and Leb antigens. These data demonstrate for the first time that DC-SIGN and L-SIGN differ in their carbohydrate binding profiles and will contribute to our understanding of the functional roles of these C-type lectin receptors, both in recognition of pathogen and self-glycan antigens.

Clinicopathological significance of sialyl Lex expression in human gallbladder carcinoma

Sialyl Lex antigen, a member of a family of high molecular weight glycoproteins, is a ligand for E-selectin and may play an important role in tumor metastasis. However, expression patterns of sialyl Lex have not yet been established in human gallbladder carcinomas. In this study, we analyzed the clinicopathological significance of sialyl Lex expression and patients' prognosis in cases of human gallbladder adenocarcinoma. Sialyl Lex immunoreactivity was detected not only in cancer cells (cytoplasmic type; 51.9%, 28/54) but also in cancer stroma (stromal type; 38.9%, 21/54). Stromal sialyl Lex expression was detected in 50.0% (20/40) and 7.1% (1/14) of T2-4 and T1 cancers, respectively (p<0.05). Stromal sialyl Lex-positive gallbladder cancers frequently showed lymphatic invasion, venous invasion and lymph node metastasis (54.3, 50.0 and 60.0%, respectively) (p<0.05), and the expression was associated with a poor outcome. Sialyl Lex expression plays important roles in the vascular invasion and metastasis of human gallbladder adenocarcinoma.