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PubMed2003

Sialic acids linked to glycoconjugates of Fas regulate the caspase-9-dependent and mitochondria-mediated pathway of Fas-induced apoptosis in Jurkat T cell lymphoma.

To clarify the functions of sialic acids linked to glycoconjugates of Fas in Fas-induced apoptosis, Jurkat T cells, untreated and treated with neuraminidase, were incubated with anti-Fas monoclonal antibody, CH11. Apoptosis of Jurkat T cells induced by incubation with CH11 was enhanced by the pre-treatment with neuraminidase. By flow cytometry sialylated glycoconjugates were detected on the cell surface of Jurkat T cells using LFA lectin, which specifically reacts with sialic acid, and pre-treatment with Vibrio Cholerae neuraminidase resulted in desialylation of Jurkat cell surface glycoconjugates. The enhancement of Fas-induced apoptosis by pre-treatment with neuraminidase was inhibited by z-VAD-fmk, a broad caspase inhibitor, and Ac-LEHD-CHO, an inhibitor of caspase-9, but not by Ac-IETD-CHO an inhibitor of caspase-8 or 6, imipramine, an inhibitor of acidic sphingomyelinase, glutathione, an inhibitor of neutral sphingomyelinase and Fumonisin B1, an inhibitor of ceramide synthase. Mitochondrial membrane potentials (Deltapsim) measured with a Mitocapture assay kit demonstrated that the loss of Deltapsim involved in Fas-induced apoptosis was enhanced by pre-treatment with neuraminidase. Furthermore, Western blot analysis using polyclonal antibody (C-20) against Fas detected Fas at about 45 kDa, and pre-treatment with neuraminidase resulted in a reduction of the molecular weight of Fas of about 8 kDa. These data suggest that the enhancement of Fas-induced apoptosis by pre-treatment with neuraminidase was mediated by a caspase-9 dependent pathway closely associated with the loss of Deltapsim, not by activation of caspase-8, -6 or acidic and neutral sphingomyelinases, and that sialic acid linked to glycoconjugates of Fas may regulate Fas-induced apoptosis in human T cell lymphoma.

Apoptosis↗

PubMed1991

Distribution of glycoconjugates in the human retinal internal limiting membrane.

The internal limiting membrane (ILM), or basal lamina, of the neural retina is located between the end feet of retinal Müller cells and the vitreous cortex. Recent studies of ILM substructure and histochemistry suggest that the ILM lamina rara externa, a region of the ILM likely to mediate vitreoretinal adhesion, is rich in noncollagen glycoconjugates. To characterize the spatial distribution and temporal expression of ILM glycoconjugates further, fetal and adult human retinas were examined using lectin histochemistry. Eyes from early fetal (13-15 weeks of gestation), midfetal (17-20 weeks of gestation), late fetal (23-26 weeks of gestation), full-term (38-41 weeks of gestation), early adult (17-20 yr of age), and late adult (57-84 yr of age) stages were examined. Although a number of significant observations pertaining to the distribution and temporal expression of ILM-associated glycoconjugates are described, two may have a significant relationship to vitreoretinal adhesion. In contrast to laminin and fibronectin, which are detectable throughout the retinal ILM at both young and older adulthood, erythrina cristagalii (ECA), a lectin with high binding affinity for galactose beta (1,3) N-acetyl-glucosamine, binds strongly to the ILM of young eyes but does not bind to the ILM of eyes from older donors. In addition, dolichos bifloris (DBA), a lectin with high binding affinity for N-acetylgalactosamine, does not bind to the ILM at early fetal stages, but binds at the midfetal stage, a time which corresponds with the onset of tertiary vitreous elaboration. More significantly, the DBA-binding glycoconjugate is neural retina ILM specific; it is not present in the basal lamina of the ciliary epithelium. Based on the known oligosaccharide composition of nonocular forms of human laminin, fibronectin, and collagen type I, and on the distribution of these molecules in the basal laminas of both the retina and ciliary epithelium, the authors conclude that the molecule bound by DBA has not been identified previously as a component of the ILM. Further characterization of ILM-associated molecules will be important to understand vitreoretinal adhesion and clinical disorders where adhesion is anomalous.

Adolescent↗

PubMed1990

Properdin binds to sulfatide [Gal(3-SO4)beta 1-1 Cer] and has a sequence homology with other proteins that bind sulfated glycoconjugates.

Properdin, which stabilizes the C3 convertase during the activation of the alternate complement pathway, contains amino acid sequence homologies with several proteins that bind sulfated glycoconjugates, including the adhesive protein thrombospondin and the leech salivary protein antistasin. This homology is based around the sequence Cys-Ser-Val-Thr-Cys-Gly-X-Gly-X-X-X-Arg-X-Arg. To determine if these homologous amino acid sequences are sulfated glycoconjugate-binding domains, purified native properdin, as well as activated properdin (a high molecular weight form of properdin), were examined for binding to various lipids in solid phase radioimmunoassays. Of the lipids tested, both native and activated properdin bind with high affinity only to sulfatide [Gal(3-SO4)beta 1-1 Cer], but not to comparable levels of cholesterol-3-SO4, or several neutral glycolipids, gangliosides, and phospholipids. Sulfatide binding by both forms of properdin is inhibited by dextran sulfate (Mr = 500,000) or fucoidan, whereas only the activated form is inhibited by dextran sulfate (Mr = 5,000) or heparin. Comparable levels of chondroitin sulfates A, B, and C, keratan sulfate, dextran (Mr = 90,000), or hyaluronic acid do not inhibit binding. Taken together, these data suggest that properdin, like antistasin and thrombospondin, binds sulfated glycoconjugates and supports the conclusion that the homologous sequences are sulfated glycoconjugate-binding domains.

Amino Acid Sequence↗

PubMed1985

Histochemical examination of glycoconjugates of epithelial cells in the human fallopian tube.

In human fallopian tubes, secretory cells made up about 70% and ciliated cells most of the remainder of the epithelium. At the light microscopic level, lectin-peroxidase conjugates and other methods demonstrated on secretory cells a surface glycocalyx containing glycoconjugates with fucose residues, terminal sialic acid-beta-galactose disaccharides, and sulfate esters. Secretory cells also expressed ABO blood group antigens, on their surface, staining for terminal alpha-N-acetylgalactosamine and alpha-galactose in blood group A and B subjects, respectively. The glycocalyx coating the cilia of all ciliated cells contained an acidic glycoconjugate with terminal sialic acid-beta-galactose disaccharides. Ciliated cells ranged from strongly positive to negative in staining for blood group ABO antigens, fucose, and terminal beta-galactose. The glycocalyx on the surface of cilia differed from that on the secretory cell surface in lacking sulfate esters and possessing terminal sialic acid-beta-galactose disaccharides cytochemically unlike those on secretory cells. Cytoplasmic granules, presumably secretory in nature, stained for blood group antigen in secretory cells of some specimens. Two lectin conjugates with affinity for the core region of N-glycosidically linked oligosaccharides revealed bodies interpreted as lysosomes in ciliated and secretory cells of most specimens. The latter lectins also stained mast cells intensely, presumably because of affinity for N-acetylglucosamine. The luminal surface of endothelial cells stained heavily for fucose and for a terminal sialic acid-beta-galactose disaccharide like that on the surface of cilia. The staining for carbohydrate did not vary qualitatively, and the ratio of secretory to ciliated cells did not differ with the phase of the menstrual cycle. The salpingeal epithelium in two patients with inactive endometrium did not differ from the others. The epithelium in a specimen from a patient with uterine fibroids showed foci of mucous metaplasia, containing a nonsulfated sialylated glycoconjugate. At the electron microscopic level, fucosylated glycoconjugate was visualized with a specific lectin conjugate on the surface of the secretory cells but not on the surface of ciliated and endothelial cells. Infrequent cytoplasmic granules containing mucosubstance apparently provided the cell mechanism in secretory cells for collecting and transporting material from biosynthetic sites to the glycocalyx.(ABSTRACT TRUNCATED AT 400 WORDS)

ABO Blood-Group System↗

PubMed1987

Fluorescence-labeled lectins, glycoconjugates, and the development of the mouse AOP.

The development of the aqueous outflow pathway (AOP) in early postnatal mouse eyes was examined for the presence of a variety of lectin receptors using fluorescein isothiocyanate (FITC) conjugated lectins, 1 micron araldite plastic sections, and computer-aided fluorescence photography. The trabecular meshwork anlage (days 1-4) was characterized by the presence of loosely arranged cells and an extracellular matrix that exhibited intense areas of Con A- and RCA-lectin staining, and absence of WGA- and LPA-lectin staining. By day 6, trabecular meshwork LPA- and WGA-positive materials were observed as focal areas of staining. By day 10, LPA- and WGA-positive materials were present as diffuse areas of staining, as the AOP differentiated into an organized and functional biological filter. The age-dependent pattern of LPA- and WGA-positive materials indicated that there were time-dependent points in the synthesis of glycoconjugates in the developing AOP. The results suggest: The composition and/or conformation of the glycoconjugates on cells and extracellular matrix changed as the AOP differentiated into a functional tissue. The use of FITC lectins as biological markers for studies of the AOP provided information on the potential role of glycoconjugates in the development of the normal AOP. Modification in the type, amount, and distribution of glycoconjugates may provide a basis for understanding the cellular mechanisms of abnormal development of the AOP, eg, congenital glaucoma.

Animals↗

PubMed1983

[Cytidine monophosphatase (CMPase), a transport hydrolase of membrane-bound glycoconjugates].

Membrane bound glycoconjugates (glycoproteins, -lipids and proteoglycans) of the plasmalemmaa and of the cytoplasmic membrane tube system are responsible for essential cell function. Accordingly it is necessary to keep them in a proper functional state. Our results indicate a possible involvement of cytidine monophosphatase (CMPase) in these events. Study is published by Novikoff (1967) and Clermont et al. (1981) the CMPase being a hydrolase which participates to a major part in the sequestration process and vesicular packaging from the GERL system. The enzyme is carried on towards the cell surface bound to the membrane of transport vesicles. Our observations suggest a possible incorporation of glycoconjugates in the plasmalemm by involvement of CMPase. In addition, the enzyme takes part in the endocytotic reuptake of glycoconjugates having lost their complete function with recycling and rebuilding in the GERL and Golgi apparatus. By using antigen provoked mononuclear and neutrophilic leucocytes the membrane bound response of CMPase is seen to be very distinct. The same is true for enterocytes exposed for a short-time ischemia. A strictly localized appearance of the CMPase in close vicinity to the couplings of short-time ischaemic muscle fibres in apparently of relevancy fr restructuring and availability of membrane bound glycoconjugates. This suggest a direct influence on the mechanism of excitation-contraction couplings of skeletal muscle fibres.

Animals↗

PubMed1982

Evidence that galactosyltransferase is a surface receptor for poly(N)-acetyllactosamine glycoconjugates on embryonal carcinoma cells.

Cell surface glycosyltransferases are thought to participate in a variety of cellular interactions, but their specific glycoside acceptors have received little attention. In this paper, poly(N)-acetyllactosamine glycoconjugates are shown to be the endogenous substrates for embryonal carcinoma (EC) cell surface galactosyltransferases. All controls have been performed to ensure a surface localization for the galactosyltransferase activity. The galactosylated product(s) is relatively insoluble in organic solvents, is larger than conventional glycopeptides following pronase digestion, and is highly sensitive to endo-beta-galactosidase degradation. Solubilized polylactosaminyl glycoconjugates serve as competitive exogenous acceptors for the surface galactosyltransferase. In addition, the endogenous galactosyl acceptor(s) reacts with antiserum directed against EC cell poly(N)-acetyllactosamines. Anti-EC antiserum inhibits galactosylation of endogenous acceptors, simultaneously stimulates galactosylation of an exogenous acceptor, and immunoprecipitates 74% of the reaction product. Differentiated EC cells no longer react with anti-EC antiserum and no longer show anti-EC antiserum effects on surface galactosyltransferase activity. Interestingly, forced galactosylation with UDPGal releases polylactosaminyl substrates from the cell surface. In the absence of UDPGal, glycoconjugate release is dramatically reduced. GDPMan cannot substitute for UDPGal, and a galactosyltransferase inhibitor prevents glycoside release from the cell surface. Thus, surface galactosyltransferase preferentially binds poly(N)-acetyllactosamine glycoconjugates and serves as at least one of their surface receptors on EC cells.

Animals↗

PubMed1981

Urinary glycoconjugates in schizophrenic patients.

The level of glycoconjugates excreted in the urine of five schizophrenic patients was compared to that excreted by six controls. Urinary samples were fractionated by means of gel filtration and anion exchange chromatography to yield (i) fraction I consisting of basic, neutral, or slightly acidic glycopeptides and/or oligosaccharides, (ii) fraction II consisting of acidic glycopeptides and/or oligosaccharides, and (iii) fraction III consisting of glycosaminoglycans (acidic mucopolysaccharides). The hexose levels of fraction II (p less than 0.05) and uronate levels of fraction III (p less than 0.025) were significantly reduced in schizophrenic patients. The ratio of galactose/mannose in the glycoconjugates of fraction II was lower than normal in the urine from schizophrenic patients. Significantly (p less than 0.05) lower levels of rhamnose and higher levels of fucose were found in the glycoconjugates of fraction I from schizophrenic patients. Contrary to a previous report, we found no evidence for the presence of an abnormally elevated rhamnose-containing glycoprotein or glycoconjugate in fraction II. I appears that the pattern of metabolism of glycoproteins and glycosaminoglycans in schizophrenic patients deviates from the normal.

Adult↗

PubMed1988

Glycoconjugate abnormalities in cultured keratoconus stromal cells.

We examined the plasma membrane glycoconjugates of cultured corneal stromal cells derived from patients with keratoconus and healthy subjects. Using radiolabeled lectins as probes, we found that a majority of our keratoconus strains contained more binding sites for concanavalin A, Ricinus communis agglutinin I, and soybean agglutinin than did the controls. The number of binding sites in cultured keratoconus cells for radioactive peanut agglutinin, wheat germ agglutinin, and Griffonia simplicifolia agglutinin I, however, was similar to that found in normal controls. Using a second method with biotin-labeled lectins as probes, we confirmed that increased amounts of glycoconjugates would bind to concanavalin A and R communis agglutinin I in stromal cells of patients with keratoconus compared with those of the control subjects. This study suggests that plasma membranes of cells derived from some patients with keratoconus may contain elevated amounts of glycoconjugates with glucose and/or mannose, terminal galactose, and N-acetylgalactosamine residues.

Adolescent↗

PubMed1996

Differentiation of glycoconjugates localized to sensory terminals and selected sites in brain.

Distribution of complex carbohydrates in the peripheral and central nervous systems was investigated cytochemically with a lectin that binds specifically to terminal alpha GalNAc and with monoclonal antibodies against carbohydrate epitopes, including glucuronic acid 3-SO4 and chondroitins 6-SO4 and 4-SO4. Comparative staining with these methods differentiated and partially characterized several glycoconjugates in various sites and allowed a comparison of chemical heterogeneity to neural specialization. Distal terminals of sensory neurons concerned with hearing, balance, taste, touch, and sight expressed glucuronyl 3-SO4, which apparently was present in an undefined glycoprotein. Some neurons in sensory nuclei of the brainstem exhibited a similar constituent on their surfaces. Retinal rod outer segments and the cerebellar granular layer possessed masked glucuronyl 3-SO4 that became immunopositive after digestion with chondroitinase ABC and that occurred in chondroitin 6-SO4 and chondroitin 4-SO4, respectively. The surface of neurons in the eighth nerve root and in neighboring nodes of Ranvier stained for unmasked glucuronic acid 3-SO4 and chondroitin 6-SO4. Some neurons of the cerebral cortex expressed unmasked glucuronyl 3-SO4, chondroitin 6-SO4, and terminal alpha GalNAc on their surfaces. Certain cortical neurons and nerve tracts with chondroitin 6-SO4 and terminal alpha GalNAc lacked glucuronyl 3-SO4, and other neurons possessing chondroitin 6-SO4 failed to express either glucuronyl 3-SO4 or terminal alpha GalNAc. Lability of lectin affinity to hyaluronidase suggested the presence of terminal alpha GalNAc in the chondroitin 6-SO4 on cortical neurons. The findings document further the heterogeneity of neural glycoconjugates, expand knowledge about the diversity of neurons with respect to their content of partially characterized glycoconjugates, and link glucuronyl 3-SO4 with or without chondroitin 6-SO4 spatially to sites of active Na+ transport in sensory nerves.

Animals↗

PubMed1999

State-of-the-art of capillary electrophoresis with application to the area of glycoconjugates.

Glycoconjugates constitute a major group of biomolecules, which participate in several biological functions and processes. Their carbohydrate components play key roles in determining the properties of glycoconjugates and, therefore, analysis and structural characterization of carbohydrates are essential. Capillary electrophoresis, due to its high resolving power and sensitivity, has been successfully used for the analysis of carbohydrates. In this review the principles of high-performance capillary electrophoresis; mechanisms employed for glycoconjugate analysis as well as the various detection techniques used are summarized.

Animals↗

PubMed1989

Effect of selected denervations on glycoconjugate composition and tissue morphology during the initiation phase of limb regeneration in adult Ambystoma.

This study was undertaken to assess the effects of various quantities of neural tissue on the temporal relationship of matrix glycoconjugates to the regeneration morphology. 1) Denervation before amputation revealed that a threshold level of nervous tissue was necessary to activate a regeneration response from the tissue, i.e., appearance of regeneration-specific morphologies and glycoconjugates. 2) Denervation after amputation demonstrated that the level of neural tissue necessary to maintain these responses was below the level necessary to activate the regeneration response. If neural tissue was completely removed there was a concomitant loss of regenerate morphologies and glycoconjugates. 3) Bilateral amputation of a neurogenically intact limb and its completely denervated contralateral limb revealed that the regeneration response was a localized phenomenon during the first 30 days after amputation. After 30 days the regeneration response appeared within the previously degenerated denervating limb. The results suggest that the factors controlling the regenerative response in adult Ambystoma are large diffusible substances that can be transported by the circulation and can affect the regenerative response in remote, previously activated, tissues.

Ambystoma↗

PubMed1990

Demonstration by lectin-gold cytochemistry of transfer of glycoconjugates of oviductal origin to the zona pellucida of oocytes after ovulation in hamsters.

We have previously localized an antigen of oviductal origin to the zona pellucida of superovulated hamster oocytes (Kan et al.: Journal of Histochemistry and Cytochemistry 36:1441-1447, 1988) and described the intracellular distribution of this antigen in the oviductal epithelium (Kan et al.: Biology of Reproduction 40:585-598, 1989). These results led to our hypothesis that the oviduct is a bona fide site of origin of certain components of the zona pellucida. In this report, using the high resolution lectin-gold approach with Helix pomatia lectin (HPL)-colloidal gold complex, we present cytochemical evidence to show that glycoconjugates containing terminal N-acetyl-D-galactosamine residues are absent from the zona pellucida of ovarian oocytes but are synthesized and secreted by the nonciliated secretory cells of the oviduct and later become associated with well-defined structural elements of the zona matrix of oocytes during passage through the oviduct. The nature of the HPL-binding glycoconjugates was determined by biochemical analyses. Electrophoretic and immunological experiments demonstrated that the glycoconjugates correspond to the high molecular weight polydispersed glycoprotein that we have previously described. We have designated this glycoprotein "hamster oviductin 1" (Hm OV-1). Our results further substantiate the belief that the oviduct is a source of origin of zona pellucida constituents.

Animals↗

PubMed1990

Distribution of cell surface glycoconjugates during secondary neurulation in the chick embryo.

Lectin histochemistry was used to examine the expression of cell surface glycoconjugates during secondary neurulation in chick embryos. Fourteen lectins were applied to serial sections of the caudal region of embryos at the various stages of tail bud development. The lectins Bandeiraea simplicifolia, Dolichos biflorus agglutinin, Phaseolus vulgaris leukoagglutinin, soybean agglutinin, Sophora japonica agglutinin, Ulex europaeus agglutinin and succinylated wheat germ agglutinin (sWGA) showed very light or no binding to the developing medullary cord of the tail bud. With the other lectins, staining occurred throughout the early tail bud and solid medullary cord. During cavitation, however, differential expression of cell surface glycoconjugates by different cell populations was observed. The lectins concanavalin A, Lens culinaris agglutinin, Pisum sativum agglutinin, Phaseolus vulgaris erythroagglutinin, Ricinus communis agglutinin and WGA showed basic similarities in the distribution of lectin binding. Of these, the binding pattern of WGA was the most striking. As the medullary cord cells were separating into central mesenchymal and peripheral epithelial populations, WGA bound preferentially to the epithelial cells and the notochord. The lectin PNA, however, became preferentially bound to the mesenchymal cells. Heavy staining by WGA (specific for N-acetylglucosamine and sialic acid) where sWGA staining (specific for N-acetylglucosamine only) was faint suggested that WGA binding was due to the presence of sialic acid containing glycoconjugates.

Animals↗

PubMed2003

PNA-positive glycoconjugates are negatively correlated with the access of neural crest cells to the gut in chicken embryos.

Neural crest cells give rise to many derivatives, including the neurons and glia of the peripheral nervous system, adrenomedulary cells, and melanocytes, and migrate through precise pathways that differ according to their axial level and/or state of specification. The migratory routes taken by neural crest cells are reported to be regulated by extracellular matrix molecules. We examined the possible influence of glycoconjugates on the establishment of barriers to neural crest access to ventral regions leading to the gut, by labeling stage-16-28 white Leghorn (WL) and Silky (SK) embryos with peanut agglutinin (PNA) at vagal, thoracic, and sacral levels. We observed a transitory expression of glycoconjugates that correlate with a barrier to the entrance of neural crest cells into the gut at the thoracic level, which is not present at vagal and sacral levels. In later stages, neural crest cells of melanocytic lineage were observed entering the gut in embryos of the SK chicken, a mutant with an altered pattern of pigmentation. The ventral regions occupied by melanoblasts in SK embryos were free of PNA labeling, while in WL embryos, in which PNA-positive molecules are strongly expressed, melanoblasts were restricted to peripheral regions. We suggest that PNA-binding glycoconjugates are good molecular marker for barriers that control the access of neural crest cells to the gut.

Animals↗

PubMed2003

Distribution of glycoconjugates during cochlea development in mice: light microscopic lectin study.

During development, different epithelial cells in the mouse cochlea express different cell surface glycoconjugates, which may reflect membrane specialization. Some of the lectins tested in this study (SBA, succ-WGA, and PSA) labeled the sensory cells of the cochlea around birth. Other lectins (WGA, Con A, RCA-II, and PHA-E) labeled surfaces of the sensory cells, particularly the stereocilia, from early stages of development (gestation day (GD) 16) through 21 days after birth. These may be adhesion molecules needed to attach the newly forming tectorial membrane (TM) to the stereocilia. Lectin staining of the developing TM revealed that the substructures of the TM are biochemically distinct. Lectin staining also showed the temporal sequence of the expression of cytoplasmic glycoconjugates of the cochlear epithelium during development. Biochemical changes during development are probably the result of different cells being involved in the production of glycoconjugates, and may have functional significance, specifically with regard to the expression of adhesion and/or signaling molecules.

Animals↗

PubMedDate not supplied

Targeting of lanthanide(III) chelates of DOTA-type glycoconjugates to the hepatic asyaloglycoprotein receptor: cell internalization and animal imaging studies.

The characterization of a new class of hydrophilic liver-targeted agents for gamma-scintigraphy and MRI, consisting, respectively, of [(153)Sm](3+) or Gd(3+) complexes of DOTA monoamide or bisamide linked glycoconjugates (DOTA = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid), is reported. In vitro studies show high uptake of radiolabeled [(153)Sm]-DOTAGal(2) by the human hepatocyte carcinoma cell line Hep G2 containing the asialoglycoprotein receptor (ASGP-R), which is decreased to less than 50% by the presence of its high-affinity ligand asialofetuin (ASF). In vivo biodistribution, gamma-imaging and pharmacokinetic studies on Wistar rats using the [(153)Sm](3+)-labeled glycoconjugates show a high uptake in the receptor-rich organ liver of the radiolabeled compounds containing terminal galactosyl groups, but very little uptake for those compounds with terminal glycosyl groups. Blocking the receptor in vivo reduced liver uptake by 90%, strongly suggesting that the liver uptake of these compounds is mediated by their binding to the asyaloglycoprotein receptor (ASGP-R). This study also demonstrated that the valency increase improves the targeting capability of the glycoconjugates, which is also affected by their topology. However despite the specific liver uptake of the radiolabeled galactose-bearing multivalent compounds, the animal MRI assessment of the corresponding Gd(3+) chelates shows liver-to-kidney contrast effects which are not significantly better than those shown by GdDTPA. This probably results from the quick wash-out from the liver of these highly hydrophilic complexes, before they can be sufficiently concentrated within the hepatocytes via receptor-mediated endocytosis.

Animals↗

PubMed2003

Treponemal glycoconjugate inhibits Toll-like receptor ligand-induced cell activation by blocking LPS-binding protein and CD14 functions.

Spirochetes are well-known as causative agents of various chronic infectious diseases. Glycolipids of small-sized Treponema spirochetes have been shown to exhibit immunostimulating activities. In this study, we found that a glycoconjugate preparation obtained from Treponema medium (Tm-Gp), an intermediate-sized oral Treponema seen in subgingival plaque from patients with chronic periodontal diseases, diminished the LPS-induced activation of a human monocytic cell line, while TNF-alpha-induced activation was unaffected. NF-kappaB activation in Ba/F3 cells expressing murine Toll-like receptor (TLR) 4 and MD-2 was inhibited by Tm-Gp in a CD14/LPS-binding protein (LBP)-dependent manner when stimulated with LPS or its active center lipid A but not when stimulated with Taxol. Tm-Gp blocked the binding of LPS to immobilized CD14 and LBP and inhibited nitric oxide (NO) production by a murine Mphi cell line following stimulation with peptidoglycan and LPS in the presence of FBS, while NO production in response poly (I:C) RNA or CpG DNA remained unaffected. The inhibitory effects of Tm-Gp seem to be attributable to the lipophilic portion of the glycoconjugate. These results indicate that T. medium contains a glycoconjugate possessing an inhibitory effect on TLR-mediated cell activation through interaction with LBP and CD14.

Acute-Phase Proteins↗