Systematic analysis of glycosphingolipids in the human gastrointestinal tract: enrichment of sulfatides with hydroxylated longer-chain fatty acids in the gastric and duodenal mucosa

Glucosylceramide and galactosylceramide, small glycosphingolipids with significant impact on health and disease

Numerous clinical observations and exploitation of cellular and animal models indicate that glucosylceramide (GlcCer) and galactosylceramide (GalCer) are involved in many physiological and pathological phenomena. In many cases, the biological importance of these monohexosylcermides has been shown indirectly as the result of studies on enzymes involved in their synthesis and degradation. Under physiological conditions, GalCer plays a key role in the maintenance of proper structure and stability of myelin and differentiation of oligodendrocytes. On the other hand, GlcCer is necessary for the proper functions of epidermis. Such an important lysosomal storage disease as Gaucher disease (GD) and a neurodegenerative disorder as Parkinson’s disease are characterized by mutations in the GBA1 gene, decreased activity of lysosomal GBA1 glucosylceramidase and accumulation of GlcCer. In contrast, another lysosomal disease, Krabbe disease, is associated with mutations in the GALC gene, resulting in deficiency or decreased activity of lysosomal galactosylceramidase and accumulation of GalCer and galactosylsphingosine. Little is known about the role of both monohexosylceramides in tumor progression; however, numerous studies indicate that GlcCer and GalCer play important roles in the development of multidrug-resistance by cancer cells. It was shown that GlcCer is able to provoke immune reaction and acts as a self-antigen in GD. On the other hand, GalCer was recognized as an important cellular receptor for HIV-1. Altogether, these two molecules are excellent examples of how slight differences in chemical composition and molecular conformation contribute to profound differences in their physicochemical properties and biological functions.

Carbohydrate-Dependent and Antimicrobial Peptide Defence Mechanisms Against Helicobacter pylori Infections

The human stomach is a harsh and fluctuating environment for bacteria with hazards such as gastric acid and flow through of gastric contents into the intestine. H. pylori gains admission to a stable niche with nutrient access from exudates when attached to the epithelial cells under the mucus layer, whereof adherence to glycolipids and other factors provides stable and intimate attachment. To reach this niche, H. pylori must overcome mucosal defence mechanisms including the continuously secreted mucus layer, which provides several layers of defence: (1) mucins in the mucus layer can bind H. pylori and transport it away from the gastric niche with the gastric emptying, (2) mucins can inhibit H. pylori growth, both via glycans that can have antibiotic like function and via an aggregation-dependent mechanism, (3) antimicrobial peptides (AMPs) have antimicrobial activity and are retained in a strategic position in the mucus layer and (4) underneath the mucus layer, the membrane-bound mucins provide a second barrier, and can function as releasable decoys. Many of these functions are dependent on H. pylori interactions with host glycan structures, and both the host glycosylation and concentration of antimicrobial peptides change with infection and inflammation, making these interactions dynamic. Here, we review our current understanding of mucin glycan and antimicrobial peptide-dependent host defence mechanisms against H. pylori infection.

Helicobacter pylori SabA binding gangliosides of human stomach

Adhesion of Helicobacter pylori to the gastric mucosa is a prerequisite for the pathogenesis of H. pylori related diseases. In this study, we investigated the ganglioside composition of human stomach as the target for attachment mediated by H. pylori SabA (sialic acid binding adhesin). Acid glycosphingolipids were isolated from human stomach and separated into subfractions, which were characterized by mass spectrometry and by binding of antibodies, bacteria, and Solanum tuberosum lectin. H. pylori SabA binding gangliosides were characterized as Neu5Acα3-neolactohexaosylceramide and Neu5Acα3-neolactooctaosylceramide, while the other acid human stomach glycosphingolipids characterized (sulfatide and the gangliosides GM3, GD3, GM1, Neu5Acα3-neolactotetraosylceramide, GD1a and GD1b) were not recognized by the bacteria. Defining H. pylori binding glycosphingolipids of the human gastric mucosa will be useful to specifically target this microbe-host interaction for therapeutic intervention.

A novel function for UDP glycosyltransferase 8: galactosidation of bile acids

The human UDP glycosyltransferase (UGT) superfamily comprises four families of enzymes that catalyze the addition of sugar residues to small lipophilic chemicals. The UGT1 and UGT2 enzymes use UDP-glucuronic acid, and UGT3 enzymes use UDP-N-acetylglucosamine, UDP-glucose, and UDP-xylose to conjugate xenobiotics, including drugs and endobiotics such as metabolic byproducts, hormones, and signaling molecules. This metabolism renders the substrate more polar and more readily excreted from the body and/or functionally inactive. The fourth UGT family, called UGT8, contains only one member that, unlike other UGTs, is considered biosynthetic. UGT8 uses UDP galactose to galactosidate ceramide, a key step in the synthesis of brain sphingolipids. To date other substrates for this UGT have not been identified and there has been no suggestion that UGT8 is involved in metabolism of endo- or xenobiotics. We re-examined the functions of UGT8 and discovered that it efficiently galactosidates bile acids and drug-like bile acid analogs. UGT8 conjugates bile acids ∼60-fold more efficiently than ceramide based on in vitro assays with substrate preference deoxycholic acid > chenodeoxycholic acid > cholic acid > hyodeoxycholic acid > ursodeoxycholic acid. Activities of human and mouse UGT8 are qualitatively similar. UGT8 is expressed at significant levels in kidney and gastrointestinal tract (intestine, colon) where conjugation of bile acids is likely to be metabolically significant. We also investigate the structural determinants of UDP-galactose selectivity. Our novel findings suggest a new role for UGT8 as a modulator of bile acid homeostasis and signaling.

Ceramide galactosyltransferase (UGT8) is a molecular marker of breast cancer malignancy and lung metastases

BACKGROUND

It was shown recently on the level of gene expression that UGT8, coding UDP-galactose:ceramide galactosyltransferase, is one of six genes whose elevated expression correlated with a significantly increased the risk of lung metastases in breast cancer patients. In this study primary tumours and their lung metastases as well as breast cancer cell lines were analysed for UGT8 expression at the protein level.

METHODS

Expression of UGT8 in breast cancer tissue specimens and breast cancer cell lines was analysed using IHC, real-time PCR and Western blotting.

RESULTS

Comparison of the average values of the reaction intensities (IRS scale) showed a significant difference in UGT8 expression between (1) primary and metastatic tumours (Mann-Whitney U, P<0.05), (2) tumours of malignancy grades G3 and G2 (Mann-Whitney U, P<0.01) as well as G3 and G1 (Mann-Whitney U, P<0.001) and (3) node-positive and node-negative tumours (Mann-Whitney U, P<0.001). The predictive ability of increased expression of UGT8 was validated at the mRNA level in three independent cohorts of breast cancer patients (721). Similarly, breast cancer cell lines with the 'luminal epithelial-like' phenotype did not express or weakly expressed UGT8, in contrast to malignant, 'mesenchymal-like,' cells forming metastases in nude mice.

CONCLUSION

Our data suggest that UGT8 is a significant index of tumour aggressiveness and a potential marker for the prognostic evaluation of lung metastases in breast cancer.

Differentiation of glycosphingolipid-derived glycan structural isomers by liquid chromatography/mass spectrometry

Isolation and characterization of glycosphingolipids is of importance in many aspects of glycobiology, but is difficult to achieve due to the high degree of heterogeneity and isomerism present in these compounds. In this study, oligosaccharides obtained from non-acid glycosphingolipids by enzymatic digestion with endoglycoceramidase II of Rhodococcus sp. were analyzed by liquid chromatography/electrospray ionization mass spectrometry using graphitized carbon columns. Resolution of isomeric oligosaccharides was achieved, and the MS(2) analyses gave complete sequence information and allowed differentiation of linkage positions. Diagnostic cross-ring (0,2)A-type fragments have previously been described for GlcNAc substituted on C-4 and for 4-substituted Glc. Diagnostic cross-ring (0,2)A-type fragments were present in the MS(2) spectrum of the H type 2 (Fucalpha2Galbeta4GlcNAcbeta4Galbeta4Glc) pentasaccharide, but not in the MS(2) spectrum of H type 1 pentasaccharide (Fucalpha2Galbeta3GlcNAcbeta4Galbeta4Glc). Cross-ring (0,2)A-type fragments were also obtained from the 4-substituted Glc at the reducing end of the glycosphingolipid-derived oligosaccharides. Oligosaccharides of the globo-series (globotriaose (Galalpha4Galbeta4Glc) and globotetraose (GalNAcbeta3Galalpha4Galbeta4Glc)) and the isoglobo-series (isoglobotriaose (Galalpha3Galbeta4Glc) and isoglobotetraose (GalNAcbeta3Galalpha3Galbeta4Glc)) were also chromatographically resolved on the graphitized carbon column. Furthermore, diagnostic fragment ions from cross-ring (0,2)A-type cleavages were present in the MS(2) spectra of the globo-series oligosaccharides, having a Gal substituted on C-4. The applicability of this method on tissue-derived samples was demonstrated using a non-acid glycosphingolipid fraction from human gastric epithelium and a partially purified non-acid glycosphingolipid fraction from 8 x 10(7) bone marrow-derived mouse dendritic cells. Here, liquid chromatography/mass spectrometry of the oligosaccharides released by endoglycoceramidase allowed tentative identification of a number of glycosphingolipids ranging from tri- to nonaglycosylceramides.

Helicobacter pylori binding to new glycans based on N-acetyllactosamine

Previously we reported binding of Helicobacter pylori to various nonacid and sialylated neolacto carbohydrate structures using a wide range of natural and chemically modified sequences. A novel nonsialylated neolacto-based binding epitope, GlcNAc beta 3Gal beta 4GlcNAc, and analogous structures carrying terminal GalNAc beta 3, GalNAc alpha 3, or Gal alpha 3 showed the binding activity (Miller-Podraza H, Lanne B, Angström J, Teneberg S, Abul-Milh M, Jovall P-A, Karlsson H, Karlsson K-A. 2005. Novel binding epitope for Helicobacter pylori found in neolacto carbohydrate chains. J Biol Chem. 280:19695-19703). The present work reports two other H. pylori-binding nonsialylated neolacto-based structures, GlcA beta 3Gal beta 4GlcNAc beta 3-R and Glc beta 3Gal beta 4GlcNAc beta 3-R, and two amide derivatives (N-methyl and N-ethyl) of GlcA beta 3Gal beta 4GlcNAc beta 3-R which were bound by H. pylori. The latter structures turned out to be more effective as H. pylori binders than the parent saccharide. New reducing-end variants of the neolacto epitope including species containing N-acetyllactosamine linked beta 6 to GlcNAc or Gal with similarity to branched polylactosamines and mucins were prepared and tested. The results extend our previous findings on binding specificities of H. pylori and show that this pathogen is able to interact with an array of N-acetyllactosamine/neolacto structures, which may be of importance for the in vivo interaction of the bacterium with human cells. The information gained in this work may also be of value for rational design of anti-H. pylori drugs.

Reduced expression of sulfatides and galactosylceramide 3'-sulfotransferase in the gastric mucosa of chronic gastritis

BACKGROUND

Sulfatides highly expressed in the normal gastric mucosa play important roles in gastric mucosal protection. However, it is unknown whether the sulfatides expression changes in chronic gastritis.

METHODS

Sulfatides expression levels were examined with immunohistochemical staining in 77 specimens obtained from resected human stomachs, followed by the measurement of optical density of the staining under digital microscopy. For mRNA expression analysis of GalCer (galactosylceramide)-sulfotransferase and arylsulfatase A using a quantitative real time reverse transcription-polymerase chain reaction, 64 biopsy specimens were endoscopically taken from the gastric corpus of out patients. Mucosal changes were scored under microscopic observations according to the updated Sydney System classification.

RESULTS

The sulfatides expression decreased along with the progression of mucosal atrophy and lymphocytes infiltration, and was barely observed in intestinal metaplasia. The mRNA expression of GalCer-sulfotransferase, a biosynthetic enzyme for sulfatides, also decreased along with the progression of mucosal atrophy and lymphocytes infiltration. In contrast, mRNA expression of arylsulfatase A, which degrades sulfatides, was not altered.

CONCLUSIONS

Expression of sulfatides and GalCer-sulfotransferase in the gastric mucosa of chronic gastritis is selectively reduced according to the mucosal atrophy and inflammation. Decreased expression of sulfatides may attribute to the deterioration of mucosal protection in chronic gastritis.

Potential tumor markers for human gastric cancer: an elevation of glycan:sulfotransferases and a concomitant loss of alpha1,2-fucosyltransferase activities

PURPOSE

Several reports indicate a complexity in glycosyltransferase activities which lead to several tumor associated carbohydrate structures in gastric carcinoma. The present study was aimed to identify the carbohydrate associated transferases which exhibit the most marked and consistent change of activity in gastric tumorigenesis.

METHODS

We examined the levels of fucosyl, beta-galactosyl-, beta-N-acetylgalactosaminyl, sialyl- and glycan:sulfotransferase activities, which generate the outer ends of oligosaccharide chains in tumorous and adjacent normal gastric tissues of the same patient in ten gastric carcinoma cases by using well defined specific synthetic acceptors utilized in our several earlier published studies as referenced in the text (e.g. Chandrasekaran et al. in J Biol Chem 279:10032-10041, 2004; Biochemistry 44:15619-15635, 2005; Carbohydr Res 341:983-994, 2006).

RESULTS

Among glycosyltransferases only alpha1,2-fucosyltransferase (FT) was unique in showing a remarkable 40-90% decrease of activity in seven cases. Uniquely several fold elevation of Gal3Sulfo-T(2) (1.9 --> 156.7 fold) and Gal3Sulfo-T(4) (2.4 --> 149.0 fold) activities in all ten cases and moderate elevation of GlcNAc6Sulfo-T (1.3 --> 37.5 fold) activities in nine cases were identified. Poorly differentiated Signet ring cell carcinoma expresses mainly Gal3Sulfo-T(2) activity whereas poorly differentiated adenocarcinoma express predominantly Gal3Sulfo-T(4) activity and also GlcNAc6Sulfo-T activity. But, very low level of these sulfotransferase activities were identified in moderately differentiated gastric carcinomas as well as non-epithelial gastric stromal sarcoma.

CONCLUSION

Up regulation of glycan:sulfotransferase activities and down regulation of alpha1,2-fucosyltransferase activity are apparently associated with human gastric tumorigenesis.

Human gastric glycosphingolipids recognized by Helicobacter pylori vacuolating cytotoxin VacA

Many bacterial toxins utilize cell surface glycoconjugate receptors for attachment to target cells. In the present study the potential carbohydrate binding of Helicobacter pylori vacuolating cytotoxin VacA was investigated by binding to human gastric glycosphingolipids on thin-layer chromatograms. Thereby a distinct binding of the toxin to two compounds in the non-acid glycosphingolipid fraction was detected. The VacA-binding glycosphingolipids were isolated and characterized by mass spectrometry and proton NMR as galactosylceramide (Galbeta1Cer) and galabiosylceramide (Galalpha4Galbeta1Cer). Comparison of the binding preferences of the protein to reference glycosphingolipids from other sources showed an additional recognition of glucosylceramide (Glcbeta1Cer), lactosylceramide (Galbeta4Glcbeta1Cer) and globotriaosylceramide (Galalpha4Galbeta4Glcbeta1Cer). No binding to the glycosphingolipids recognized by the VacA holotoxin was obtained with a mutant toxin with deletion of the 37 kDa fragment of VacA (P58 molecule). Collectively our data show that the VacA cytotoxin is a glycosphingolipid binding protein, where the 37 kDa moiety is required for carbohydrate recognition. The ability to bind to short chain glycosphingolipids will position the toxin close to the cell membrane, which may facilitate toxin internalization.

Uptake of the glycosphingolipid sulfatide in the gastrointestinal tract and pancreas in vivo and in isolated islets of Langerhans

Background

The glycosphingolipid sulfatide has previously been found in several mammalian tissues, but information on the uptake of exogenously administered sulfatide in different organs in vivo is limited. In pancreatic beta cells, sulfatide has been shown to be involved in insulin processing and secretion in vitro. In this study, we examined the uptake of exogenously administered sulfatide and its distribution to the pancreatic beta cells. This might encourage future studies of the function(s) of sulfatide in beta cell physiology in vivo. Radioactive sulfatide was given orally to mice whereafter the uptake of sulfatide in the gastrointestinal tract and subsequent delivery to the pancreas was examined. Sulfatide uptake in pancreas was also studied in vivo by i.p. administration of radioactive sulfatide in mice, and in vitro in isolated rat islets. Isolated tissue/islets were analysed by scintillation counting, autoradiography and thin-layer chromatography-ELISA.

Results

Sulfatide was taken up in the gastrointestinal tract for degradation or further transport to other organs. A selective uptake of short chain and/or hydroxylated sulfatide fatty acid isoforms was observed in the small intestine. Exogenously administered sulfatide was found in pancreas after i.p, but not after oral administration. The in vitro studies in isolated rat islets support that sulfatide, independently of its fatty acid length, is endocytosed and metabolised by pancreatic islets.

Conclusion

Our study supports a selective uptake and/or preservation of sulfatide in the gastrointestinal tract after oral administration and with emphasises on pancreatic sulfatide uptake, i.p. administration results in sulfatide at relevant location.

P-selectin mediates metastatic progression through binding to sulfatides on tumor cells

Hematogenous carcinoma metastasis is associated with tumor cell emboli formation, which is now known to be facilitated by selectins. P-selectin-mediated interactions of platelets with cancer cells are based mostly on mucin- and glycosaminoglycan-type selectin ligands. We previously showed that mouse colon carcinoma cells (MC-38) carry P-selectin ligands of nonmucin origin, which were not identified. Here we show that P-selectin ligands recognized on MC-38 cells are sulfated glycolipids, thereby facilitating experimental metastasis in a syngeneic mouse model. Metabolic inhibition of sulfation by incubation of cells with sodium chlorate almost completely abrogated P-selectin binding. Metabolic labeling of MC-38 cells with (35)S sulfate revealed only a single band as detected by high-performance thin layer chromatography analysis of a total lipid extract. Matrix-assisted laser desorption/ionization tandem time-of-flight/time-of-flight analysis (MALDI-TOF-TOF) analysis of the purified sulfate-containing lipid fraction identified the selectin ligand to be a sulfated galactosylceramide SM4 (HSO(3)-3Galbeta-1Cer). Modulation of glycolipid biosynthesis in MC-38 cells altered P-selectin binding, thereby confirming sulfoglycolipids to be major P-selectin ligands. In addition, P-selectin was also found to recognize lactosylceramide sulfate SM3 (HSO(3)-3Galbeta-4Glcbeta-1Cer) and gangliotriaosylceramide sulfate SM2 [GalNAcbeta-4(HSO(3)-3)Galbeta-4Glcbeta-1Cer] in human hepatoma cells. Finally, the enzymatic removal of sulfation from the cell surface of MC-38 cells resulted in decreased P-selectin binding and led to attenuation of metastasis. Thus, SM4 sulfatide serves as a native ligand for P-selectin contributing to cell-cell interactions and to facilitation of metastasis.

Endogenous immune response to gangliosides in patients with confined prostate cancer

Our study investigated whether endogenous IgM antibodies to gangliosides occur in patients with early stages of prostate cancer (CaP) patients, after defining ganglioside profiles of CaP cell lines. Immune and resorcinol staining detected the presence of gangliosides GM3, GM2, GD3, GD2 and GD1a but not GM1a, GD1b or GT1b in the extracts of normal prostatic epithelial cells (PrEC) and neoplastic androgen-insensitive (PC-3, DU145) and -sensitive (LNCaP-FGC and LNCaP-FGC-10) CaP cells. Using a sensitive ELISA, developed and validated in our laboratory, the titers of IgM against 8 gangliosides from sera of patients with benign prostatic hyperplasia (BPH) (n = 11), organ-confined (T1/T2, n = 36) and unconfined (T3/T4, n = 27) CaP and age-matched healthy men (n = 11) were determined double-blinded. Using ANOVA and Fisher's least significant difference (LSD) methods, the log-titers among different groups were compared. CaP patients differed from healthy and BPH patients in increased titers against GD1a and decreased titers against GD3. Titers of antibodies to other gangliosides exhibited no difference between CaP patients and others. The specific augmentation of anti-GD1a IgM in patients with organ-confined CaP (stage T1/T2) but not in patients with unconfined CaP (stage T3/T4) or BPH or in healthy controls is striking. This finding together with identification of GD1a as a major ganglioside in CaP cell lines and with the accruing studies on the immunosuppressive nature of GD1a indicates that augmentation of anti-GD1a IgM in confined CaP may signify an early endogenous immune response to eliminate a "danger signal" from tumor microenvironment and circulation.

Chemical and enzymatic transacylation of amide-linked FA of buttermilk gangliosides

The goal of this work was to alter the composition of amide-linked FA of bovine buttermilk gangliosides, particularly the disialoganglioside GD3, to adjust lipid sources to special food specifications and pharmacological or cosmetic applications. The chemical transacylation of amide-linked FA of buttermilk gangliosides with free arachidic acid (20:0) by a combination of basic hydrolysis and diethylphosphorylcyanide/triethylamine-catalyzed reacylation was compared to an enzymatic sphingolipid ceramide N-deacylase (EC 3.5.1.23)-catalyzed FA exchange by GC analysis and nano electrospray ionization-MS. The buttermilk predominantly contained the disialoganglioside GD3 and the monosialoganglioside GM3. The heterogeneity of FA that are incorporated into gangliosides, mainly palmitic acid (29.4 wt%), stearic acid (16.9 wt%), oleic acid (17.8 wt%), and myristic acid (8.5 wt%), was effectively altered by both transesterification techniques. Arachidic acid, which was not integrated into the initial buttermilk gangliosides, was transacylated to total gangliosides with 23.2 wt% (GD3, 6.7 wt%) by the chemical process and with 8.7 wt% (GD3, 13.8 wt%) when catalyzed enzymatically. Mainly behenic acid and lignoceric acid of GD3 were exchanged chemically, and stearic acid was exchanged by the enzymatic process. This observation might depend on hydrolytic sensitivities of amide-linked very long chain saturated FA or specific enzyme subtrate affinities, respectively. Results of chemical hydrolysis indicated there was a risk of sialic acid decomposition and unspecific degradations. Regarding specificity and avoidance of critical agents, the enzymatic transesterification is recommended for industrial-scale production of consumer goods.

Interactions between glucosylceramide and galactosylceramide I(3) sulfate and microstructures formed

The monohexoside glycosphingolipids (GSLs), galactosylceramide (GalC), glucosylceramide (GluC), and their sulfated forms are abundant in cell membranes from a number of tissues. Carbohydrate-carbohydrate interactions between the head groups of some GSLs can occur across apposed membranes and may be involved in cell-cell interactions. In the present study, the ability of GluC to participate in trans interactions with galactosylceramide I(3) sulfate (CBS) was investigated by transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy. Gaucher's spleen GluC had polymorphic phase behavior; in its metastable state, it formed large wrinkled vesicles. It transformed to a stable state via an intermediate state in which the surface of the vesicles consisted of narrow ribbons. In the stable state, the narrow ribbons split off from the surface to form membrane fragments and flat and helical ribbons. The strength of the intermolecular hydrogen bonding interactions between the carbonyls increased in the order metastable<intermediate<stable state. Aqueous dispersions of GluC and CBS were combined to allow trans carbohydrate-carbohydrate interaction across apposed bilayers, or the lipids were premixed in a solvent before hydration to allow lateral cis interactions. Premixed dispersions of NFA-GluC and CBS remained in the metastable state even when incubated under stable state conditions. When NFA-GluC dispersions were combined with CBS dispersions, they had a small effect on each other's amide groups in the metastable state. Furthermore, conversion of NFA-GluC to the stable state was inhibited, although it reached the intermediate state, suggesting that some degree of trans interaction between these two lipids occurred.

Lactotetraosylceramide, a novel glycosphingolipid receptor for Helicobacter pylori, present in human gastric epithelium

The binding of Helicobacter pylori to glycosphingolipids was examined by binding of (35)S-labeled bacteria to glycosphingolipids on thin-layer chromatograms. In addition to previously reported binding specificities, a selective binding to a non-acid tetraglycosylceramide of human meconium was found. This H. pylori binding glycosphingolipid was isolated and, on the basis of mass spectrometry, proton NMR spectroscopy, and degradation studies, were identified as Galbeta3GlcNAcbeta3Galbeta4Glcbeta1Cer (lactotetraosylceramide). When using non-acid glycosphingolipid preparations from human gastric epithelial cells, an identical binding of H. pylori to the tetraglycosylceramide interval was obtained in one of seven samples. Evidence for the presence of lactotetraosylceramide in the binding-active interval was obtained by proton NMR spectroscopy of intact glycosphingolipids and by gas chromatography-electron ionization mass spectrometry of permethylated tetrasaccharides obtained by ceramide glycanase hydrolysis. The lactotetraosylceramide binding property was detected in 65 of 74 H. pylori isolates (88%). Binding of H. pylori to lactotetraosylceramide on thin-layer chromatograms was inhibited by preincubation with lactotetraose but not with lactose. Removal of the terminal galactose of lactotetraosylceramide by galactosidase hydrolysis abolished the binding as did hydrazinolysis of the acetamido group of the N-acetylglucosamine. Therefore, Galbeta3GlcNAc is an essential part of the binding epitope.

The aglycone of sulfogalactolipids can alter the sulfate ester substitution position required for hsc70 recognition

3'-Sulfogalactolipids(SGLs), sulfogalactosyl ceramide (SGC), and sulfogalactoglycerolipid (SGG) bind to the N-terminal ATPase-containing domain of members of the heat shock protein 70 family. We have probed this binding specificity using a series of synthetic positional sulfated or phosphorylated glycolipid analogues, containing either a long-chain bisalkyl hydrocarbon-2-(tetradecyl)hexadecane (B30) or C(18) ceramide (SGC(18)) backbone. By TLC overlay and receptor ELISA, recombinant hsc70 bound ceramide-based glycoconjugates having 3'- or 4'-sulfogalactose glycone moieties and the 4'-sulfogalactose positional isomer conjugated to B30. Hsc70 binding was significantly decreased to the 3'-sulfogalactose conjugated to the long-chain branched alkane. 3'-Sulfoglucose conjugated to B30 was not bound, nor were similarly conjugated di-, tri-, and tetra-sulfated or phosphorylated galactolipids. These results highlight the importance of the position, rather than the number of sulfate esters within the galactose ring. This binding selectivity was shared by the sea urchin hsp70-related sperm receptor. A 3'-SGC-based soluble inhibitor, in which the acyl chain was replaced with an adamantyl group, inhibited binding of hsc70 to both 3'- and 4'-SGC species with an IC(50) of 50 and 75 microM, respectively, indicating a shared sulfogalactose binding site. These studies demonstrate the highly specific nature of hsc70/SGL binding and show, for the first time, that the lipid aglycone can alter the substitution position requirement for glycolipid recognition.

Heat-inducible surface stress protein (Hsp70) mediates sulfatide recognition of the respiratory pathogen Haemophilus influenzae

The in vitro glycolipid binding specificity of clinical strains of nontypeable Haemophilus influenzae is altered to include sulfated glycolipids following a brief heat shock. We have constructed, expressed, and purified a recombinant protein of H. influenzae Hsp70, which showed significant specific binding to sulfated galactolipids in vitro. Furthermore, indirect immunofluorescence demonstrates that Hsp70 proteins are surface exposed in H. influenzae only after heat shock and are contained in the outer membrane protein fractions.

Characterization of the human UDP-galactose:ceramide galactosyltransferase gene promoter

UDP-galactose:ceramide galactosyltransferase (CGT, EC 2.4.1.45) is a key enzyme in the biosynthesis of galactocerebroside, the most abundant glycosphingolipid in the myelin sheath. An 8 kb fragment upstream from the transcription initiation site of CGT gene was isolated from a human genomic DNA library. Primer extension analysis revealed a single transcription initiation site 329 bp upstream from the ATG start codon. Neither a consensus TATA nor a CCAAT box was identified in the proximity to the transcription start site; however, this region contains a high GC content and multiple putative regulatory elements. To investigate the transcriptional regulation of CGT, a series of 5' deletion constructs of the 5'-flanking region were generated and cloned upstream from the luciferase reporter gene. By comparing promoter activity in the human oligodendroglioma (HOG) and human neuroblastoma (LAN-5) cell lines, we found that the CGT promoter functions in a cell type-specific manner. Three positive cis-acting regulatory regions were identified, including a proximal region at -292/-256 which contains the potential binding sites for known transcription factors (TFs) such as Ets and SP1 (GC box), a distal region at -747/-688 comprising a number of binding sites such as the ERE half-site, NF1-like, TGGCA-BP, and CRE, and a third positive cis-acting region distally localized at -1325/-1083 consisting of binding sites for TFs such as nitrogen regulatory, TCF-1, TGGCA-BP, NF-IL6, CF1, bHLH, NF1-like, GATA, and gamma-IRE. A negative cis-acting domain localized in a far distal region at -1594/-1326 was also identified. Our results suggest the presence of both positive and negative cis-regulatory regions essential for the cell-specific expression in the TATA-less promoter of the human CGT gene.

The ATPase domain of hsp70 possesses a unique binding specificity for 3'-sulfogalactolipids

The region(s) of hsp70 critical for sulfogalactolipid (SGL) recognition has been defined through deletion analysis and site-directed mutagenesis. Truncated polymerase chain reaction products of hsp70 generated N-terminal fragments of 43, 35, 29, and 22 kDa. The C terminus substrate-binding domain (28 kDa) was also expressed. The N-terminal ATPase domain (rP43) shared the binding specificity of hsp70, because only sulfogalactosyl ceramide and sulfogalactosyl glycerolipid were recognized by both TLC overlay and RELISA. The C-terminal domain showed no binding. SGL binding of rP29 and rP22 was severely reduced. The loss of SGL binding for rP35 by RELISA but not TLC overlay was considered as a function of receptor presentation. The truncation of rP43 to rP35 demonstrates that residues 318-387 (the base of the ATP binding cleft) are critical for high affinity SGL binding. Mutagenesis showed that Arg(342) and Phe(198) are crucial for this process. SGL binding, mediated by these conserved residues within the ATPase domain of hsp70, implies that this binding specificity is evolutionarily conserved.

Midkine binds specifically to sulfatide the role of sulfatide in cell attachment to midkine-coated surfaces

Midkine is a heparin-binding polypeptide which is implicated in the control of development and repair of various tissues. Recognition of sulfate groups in glycosaminoglycans is important for its function. To elucidate further its mechanism of action, the interactions of midkine with sulfated glycolipids were studied. Of various glycolipids and lipids examined, midkine bound strongly to sulfatide and cholesterol-3-sulfate (CHO-3-SO4) in a dose-dependent manner but failed to bind to other standard glycolipids and lipids. The properties of midkine binding to sulfatide and to CHO-3-SO4 differed in their sensitivity to inhibition by anionic polysaccharides, salt concentration and unlabeled midkine. Heparin inhibited midkine binding to sulfatide but weakly inhibited its binding to CHO-3-SO4. Liposomes bearing sulfatide carried out significant interactions with immobilized midkine, whereas those bearing CHO-3-SO4 did not. Incorporation of sulfatide into 32D cells and trypsinized COS cells enhanced 125I-labelled midkine binding, whereas incorporation of ganglioside or galactosylceramide had no effect. Furthermore, sulfatide-incorporated cells enhanced cell attachment to midkine-coated coverslips. These results indicate that midkine binds to sulfatide under physiological conditions and the midkine-sulfatide interaction may be important in controlling cell attachment.

Phosphatidylethanolamine recognition promotes enteropathogenic E. coli and enterohemorrhagic E. coli host cell attachment

Using both solid phase and liposome aggregation assays, we screened a variety of glycolipids and phospholipids and found that EHEC and EPEC bind specifically and in a dose-dependent manner to PE. This binding was consistently observed whether the lipid was immobilized on a thin layer chromatography plate, in a microtitre well or incorporated into a unilamellar vesicle suspended in aqueous solution. There was no evidence of binding to other phospholipids such as phosphatidylcholine (PC) or phosphatidylserine (PS). Bacterial binding to two epithelial cell lines also correlated with the level of outer leaflet PE and was reduced following preincubation with anti-PE. The PE-binding phenotype of EPEC appeared to correlate with the bundle-forming pilus (bfp) genotype of a number of clinical isolates. These results provide evidence of a receptor role for PE in the adhesion of EHEC and EPEC to host cells.

Glycolipid receptors for verotoxin and Helicobacter pylori: role in pathology

Eukaryotic cell surface glycolipids can act as both the primary interface between bacteria and their host and secondly as a targeting mechanism for bacterial virulence factors. The former is characterized by redundancy in adhesin-receptor interactions and the latter by a higher affinity, more restrictive glycolipid binding specificity for targeting. Interactions of verotoxin with its glycolipid receptor globotriaosylceramide and Helicobacter pylori binding to a variety of different glycolipids, which can be environmentally regulated, provide examples of these differing modes of glycolipid receptor function. Verotoxins are involved in endothelial targeting in the microangiopathies of hemorrhagic colitis and hemolytic uremic syndrome (HUS). The highly restricted binding specificity and crystal structure of the verotoxin B subunit have allowed theoretical modeling of the Gb3 binding site of the verotoxin B subunit pentamer which provides an approach to intervention. Studies of the role of glycolipid function in verotoxin-induced disease have concentrated on the distribution of Gb3 and its ability to mediate the internalization of the toxin within the target cell. The distribution of Gb3 within the renal glomerulus plays a central role in defining the age-related etiology of HUS following gastrointestinal infection with VT producing Escherichia coli. H. pylori, on the other hand, instigates a less distinct but more complex disseminated gastric inflammation. Studies on the role of glycolipid receptors in H. pylori infection have been bogged down in establishing the importance of each binding specificity defined. In addition, the physiological condition of the organism within the various binding assays has not been extensively considered, such that spurious non-physiological interactions may have been elucidated. The identification and cloning of a Le(b) binding adhesin and the identification of cell surface hsp70 as a mediator of sulfoglycolipid binding under stress conditions may now allow a more molecular approach to define the role of glycolipid recognition in this infection.

Detection of cerebroside sulfotransferase mRNA in human gastric mucosa and adenocarcinoma

Sulfatide is a major acidic glycolipid in human gastric mucosa, and its sulfation is catalyzed by cerebroside sulfotransferase (CST). To investigate the expression of the CST gene in human gastric cancer, a reverse transcription PCR method was developed with the use of endoscopic bioptic specimens. By this method, we examined the CST mRNA expression in 11 cases of gastric cancer, and in all the cases we detected various levels of the expression both in cancer tissues and in uninvolved adjacent tissues. The present assay method was suggested to be useful in the detection of CST mRNA from a limited amount of bioptic samples.

Sulfatide from the pig jejunum brush border epithelial cell surface is involved in binding of Escherichia coli enterotoxin b

Using a quantitative dot blot overlay assay of polyvinylidene difluoride membranes, we investigated the ability of Escherichia coli heat-stable enterotoxin b (STb) to bind to various glycolipids of defined structure. STb bound strongly to acidic glycosphingolipids, including sulfatide (or 3'-sulfogalactosylceramide) and several gangliosides, but not significantly to their derivatives, galactosylceramide and asialogangliosides, respectively. STb exhibited the highest binding affinity for sulfatide. STb bound to pure sulfatide in a dose-dependent and saturable manner, with a detection level of a few nanograms. The binding was not inhibited by tetramethylurea, which is a strong disrupter of hydrophobic interactions, or by the anionic sulfated polymer of glucose, dextran sulfate, indicating that the binding is not due solely to either hydrophobic or ionic interactions via the sulfate group of the sulfatide. The specificity of the binding was confirmed by the finding that a 500-fold molar excess of sulfatide inhibited STb binding by approximately 45%, whereas no competition was obtained with galactosylceramide under the same conditions. Taken together, our data indicated that a galactose residue linked to a sulfate group is required for the binding specificity of STb. Then, total lipids extracted either from the mucous layer or from the epithelial cells of the pig jejunum brush border, the natural target of STb, were analyzed by thin-layer chromatography (TLC). Both extracts contained a lipidic molecule with a relative mobility on a TLC plate similar to that of the sulfatide standard. The migrated lipid extracted directly from a preparative TLC plate was confirmed to be sulfatide, as it was recognized by laminin, a sulfated glycolipid binding protein, and by a monoclonal antibody directed against sulfatide. In an overlay assay on PVDF membranes, STb bound to the sulfatide prepared from porcine jejunum as well as to the sulfatide standard. Thus, these findings suggest that the terminal oligosaccharide sequence Gal(3SO4)beta1- on sulfatide could mediate binding of STb to its target cells and, in support of a recent report (E. Rousset, J. Harel, and J. D. Dubreuil, Microb. Pathog. 24:277-288, 1998), probably terminal sialic acid residue on another glycosphingolipid. Moreover, pretreatment in the ligated intestinal loop assay with laminin or sulfatase altered the biological activity of STb. In summary, we present data indicating that sulfatide represents a functional receptor for the STb toxin.

Affinity purification of Helicobacter pylori urease. Relevance to gastric mucin adherence by urease protein

A simple, reproducible and high yield method of Helicobacter pylori urease enzyme purification was developed using a heparinoid (Cellufine sulfate) affinity gel. The purification method involved two sequential steps using the same gel that takes advantage of the differential affinity of urease to the heparinoid at two levels of hydrogen ion concentration. SDS-polyacrylamide gel electrophoresis analysis of affinity-purified urease revealed two major protein bands with about 62- and 30-kDa molecular mass. When whole cell lysates of clinical and laboratory strains of H. pylori were probed by Western blot, anti-urease hyperimmune serum produced by affinity-purified urease in rabbit recognized only the two bands corresponding to the urease A and B subunits. To probe the molecular relevance of affinity gel adherence to mucin adherence, the purified urease was derivatized with N-hydroxysuccinimidobiotin and used in adherence assays. Competitive inhibition tests revealed commonality of urease receptors among gastric mucin, heparin, and heparinoid. Composite data on adherence kinetics modulated by pH, salt, incubation time, and concentration of urease or mucin were indicative of conformation-dependent ligand-receptor interaction.

Electrospray ionization tandem mass spectrometric analysis of sulfatide. Determination of fragmentation patterns and characterization of molecular species expressed in brain and in pancreatic islets

The sphingolipid sulfatide is a component of myelin and some non-neuronal cells. Antibodies to sulfatide occur in some patients with autoimmune neuropathies and in patients with insulin-dependent diabetes mellitus (IDDM) caused by immunologic destruction of insulin-secreting pancreatic islet beta-cells. Distinct sulfatide molecular species may differ in immunogenicity, and facile means to identify sulfatide species in islets and other tissues obtainable in only small amounts could be useful. Electrospray ionization mass spectrometry (ESI/MS) permits structural determination of small quantities of phospholipids and is applied here to sulfatide analysis. We find that sulfatide standards are readily analyzed by negative ion ESI/MS, and tandem mass spectra of individual species exhibit some ions common to all species and other ions that reflect distinct fatty acid substituents in different sulfatide molecules. A signature ion cluster resulting from cleavage directed by the alpha-hydroxy group of sulfatide species with a hydroxylated fatty acid substituent identifies such species. Sulfatide profiles in tissue lipid extracts can be obtained by ESI/MS/MS scanning for common sulfatide ions and for ions reflecting fatty acid substituents. Islets are demonstrated to contain sulfatide and to exhibit a profile of species different from that of brain.

Cloning, characterization, and expression of human ceramide galactosyltransferase cDNA

Galactosylceramide (galactocerebroside, GalC) and its sulfated derivative, sulfatide, are major lipid components of the central and peripheral nervous system myelin sheath. The enzyme UDP-galactose:ceramide galactosyltransferase (CGT, EC 2.4.1.45) catalyzes the final step of galactosylceramide synthesis. In this report we describe isolation of the complete copy of human CGT cDNA. Total RNA from N-370 FG cells, a human fetal glioma cell line, was reverse-transcribed and dG-tailed. Degenerate primers synthesized based on rat CGT cDNA sequence were used in 5'- and 3'- rapid amplification of cDNA ends reaction (RACE). The obtained sequence was used to synthesize the primers for the complete coding region to be amplified and cloned into a pCR 3.1 expression vector. Following transfection of the CHOP cells with the resulting vector, the cell homogenate was assayed for the galactosyltransferase activity. Northern blot hybridization was used to determine the length of CGT mRNA and Southern blot hybridization was used to determine the number of homologous genes. Our results indicate that human CGT retains all conservative features of rat and mouse CGT. It is a single copy gene with mRNA transcript of about 4 kb.

Menstrual cycle-associated regulation of anabolic and catabolic enzymes causes luteal phase-characteristic expression of sulfatide in human endometrium

OBJECTIVE

Our purpose was to investigate the metabolic background of the expression of sulfoglycolipids in human endometrium during the luteal phase.

STUDY DESIGN

We investigated the expression of sulfoglycolipids by thin-layer chromatography immunostaining and the activities of galactosylceramide sulfotransferase and arylsulfatase A, which regulate the synthesis and degradation of sulfoglycolipid. In addition, arylsulfatase A messenger ribonucleic acid was studied by reverse transcriptase polymerase chain reaction.

RESULTS

Sulfoglycolipid expression showed a marked increase in the luteal phase but not in the follicular phase, whereas sialoglycolipids remained relatively constant. The increase of sulfoglycolipids was found to be due to 4.5-fold increased activation of sulfotransferase and a concurrent reduction of arylsulfatase A activity in the luteal phase. Arylsulfatase A messenger ribonucleic acid was detected in both phases and showed no significant changes.

CONCLUSIONS

These findings suggest that increased sulfoglycolipid expression in the luteal phase is due to the simultaneous regulation of sulfotransferase and arylsulfatase A, probably by sex steroid hormones.

Adherence to lipids and intestinal mucin by a recently recognized human pathogen, Campylobacter upsaliensis

Campylobacter upsaliensis is a recently recognized human enteric pathogen associated with enteritis, colitis, bacteremia, and sepsis. Very little is known about the mechanisms of pathogenesis of this organism. The goals of this study were to determine whether C. upsaliensis binds to epithelial cells and whether there are specific lipid molecules that might serve as cell membrane receptors. In addition, we also explored C. upsaliensis binding to purified human small-intestinal mucin, since the mucus gel overlying the epithelium provides an initial contact surface for the bacteria and must be penetrated for the organisms to reach their cell receptors. Binding of C. upsaliensis to model epithelial cells was shown by microscopy adhesion assays, and binding to lipids was detected by thin-layer chromatography-overlay assays. Bacteria bound to phosphatidylethanolamine (PE), gangliotetraosylceramide (Gg4), and, more weakly, to phosphatidylserine (PS). There was no binding to ceramide, cholesterol, phosphatidylcholine, and globosides. Using receptor-based microtiter well immunoassays, we observed binding to be equal, specific, and saturable for PE and Gg 4 but low and nonspecific for PS. At least five bacterial surface proteins (50 to 90 kDa) capable of PE binding were identified by a lipid-silica affinity column technique. In slot blot overlay assays, biotin-labeled C. upsaliensis also bound in a concentration-dependent fashion to purified human small-intestinal mucin, implying that these microorganisms also express an adhesin(s) recognizing a specific mucin epitope(s). We speculate that binding to mucins may influence access of the bacteria to cell membrane receptors and thereby influence host resistance to infection.

Synthesis of non-hydroxy-galactosylceramides and galactosyldiglycerides by hydroxy-ceramide galactosyltransferase

Galactosylceramide (GalCer) is the major glycolipid in brain. In order to characterize the activity of brain UDPgalactose: ceramide galactosyltransferase (CGalT), it has been stably expressed in CGalT-negative Chinese hamster ovary (CHO) cells. After fractionation of transfected cells, CHO-CGT, on sucrose gradients, the activity resides at the density of endoplasmic reticulum and not of Golgi. A lipid chromatogram from CHO-CGT cells revealed two new iodine-staining spots identified as GalCer, since they comigrate with GalCer standards, can be metabolically labelled with [3H]galactose, are recognized by anti-GalCer antibodies, and are resistant to alkaline hydrolysis. A third [3H]galactose lipid was identified as galactosyldiglyceride. In the homogenate CGalT displays a 25-fold preference for hydroxy fatty acid-containing ceramides. Remarkably, endogenous GalCer of transfected cells contains exclusively non-hydroxy fatty acids: fast atom bombardment and collision-induced dissociation mass spectrometric analysis revealed mainly C16:0 in the lower GalCer band on TLC and mainly C22:0 and C24:0 in the upper band. Our results suggest that CGalT galactosylates both hydroxy- and non-hydroxy fatty acid-containing ceramides and diglycerides, depending on their local availability. Thus, CGalT alone may be responsible for the synthesis of hydroxy- and non-hydroxy-GalCer, and galactosyldiglyceride in myelin.

Acidic pH changes receptor binding specificity of Helicobacter pylori: a binary adhesion model in which surface heat shock (stress) proteins mediate sulfatide recognition in gastric colonization

The gastric pathogen helicobacter pylori is one of a number of bacteria which bind specifically to gangliotetraosylceramide, gangliotriaosylceramide, and phosphatidylethanolamine in vitro at neutral pH. Since this organism encounters an acid pH during initial infection of the stomach, we have monitored the effect of pH on receptor binding specificity and found induction of specific binding to sulfoglycolipids (sulfatide) following brief treatment at low pH. We have previously shown that heat shock proteins (hsps) bind to sulfatide, and the suspicion that this was a stress-induced response is supported by the fact that a similar change in H. pylori binding specificity was observed if the organisms were briefly exposed to heat shock treatment. Following the stress stimulus, the change in glycolipid binding specificity was prevented by the inclusion of inhibitors of protein synthesis or by incubation with anti-hsp antibodies. Expression of hsps in the surface extract and surface reactivity with anti-hsp antibodies correlated with the change in glycolipid binding specificity. Despite the presence of high levels of H. pylori cell surface urease activity which may neutralize the microenvironmental pH, the acid-induced change in binding specificity was enhanced in the presence of urea. These studies suggest that cell surface hsps mediate sulfatide recognition by this organism under stress conditions. A binary receptor model is proposed for gastric colonization by H. pylori.

Sorting of newly synthesized galactosphingolipids to the two surface domains of epithelial cells

The high concentration of glycosphingolipids on the apical surface of epithelial cells may be generated by selective transport from their site of synthesis to the cell surface. Previously, we showed that canine kidney MDCK and human intestinal Caco-2 cells converted a ceramide carrying the short fluorescent fatty acid C6-NBD to glucosylceramide (GlcCer) and sphingomyelin (SM), and that GlcCer was preferentially transported to the apical surface as compared to SM. Here, we address the point that not all glycosphingolipid classes are apically enriched in epithelia. We show that a ceramide containing the 2-hydroxy fatty acid C6OH was preferentially converted by MDCK and Caco-2 cells to galactosylceramide (GalCer) and its derivatives galabiosylceramide (Ga2Cer) and sulfatide (SGalCer) as compared to SM and GlcCer--all endogenous lipid classes of these cells. Transport to the apical and basolateral cell surface was monitored by a BSA-depletion assay. In MDCK cells, GalCer reached the cell surface with two- to sixfold lower apical/basolateral polarity than GlcCer. Remarkably, in Caco-2 cells GalCer and GlcCer displayed the same apical/basolateral polarity, but it was sixfold lower for lipids with a C6OH chain than for C6-NBD lipids. Therefore, the sorting of a sphingolipid appears to depend on lipid structure and cell type. We propose that the different ratios of gluco- and galactosphingolipid synthesis in the various epithelial tissues govern lipid sorting in the membrane of the trans Golgi network by dictating the composition of the domains from where vesicles bud to the apical and basolateral cell surface.

Biochemical bases in differentiation of a mouse cell line GSM06 to gastric surface cells

A mouse gastric surface cell line GSM06 established from a transgenic mouse harboring temperature-sensitive simian virus 40 large T-antigen gene was subjected to the lipid and glycoprotein analysis. When GSM06 cells were cultured for a long time after formation of a confluent monolayer, they differentiated to resemble foveolar epithelial cells morphologically. Biochemical changes during culture were studied in cells harvested just when a monolayer had formed (day 0), on day 7, and on day 21. Content of total phospholipids, cholesterol, cholesterol sulfate, total sugar and sialic acid increased about 1.5-fold from day 0 to 7 and remained elevated till day 21. The fatty acid composition of phospholipids revealed increased relative levels of oleic acid in phosphatidylcholine and phosphatidylethanolamine, and an increased level of plasmenylethanolamine from day 0 to 7. The level of dolichylphosphate continued to increase in a time-dependent manner. Glycosylation of various proteins, detected with lectins, was enhanced from day 7. In addition, greater resistance to taurodeoxycholate and acetylsalicylic acid was observed on days 7 and 21 than on day 0. Thus, enhanced glycosylation of proteins and an overall increase in the area of cellular membranes were the major changes in GSM06 cells during culture, and they were accompanied by an enhancement of cytoprotective potential.

Role of sulfatides in adhesion of Helicobacter pylori to gastric cancer cells

We have demonstrated that clinical isolates of Helicobacter pylori preferentially bind to sulfatides (I3SO3-GalCer) and GM3 gangliosides (II3NeuAcLacCer), two predominant acidic glycosphingolipids in the human gastric mucosa, on thin-layer chromatography plates. However, it has not yet been clarified that these glycospingolipids truly serve as adhesion receptors for H. pylori in live cells. In this study, we used a gastric cancer cell line, KATO III, as a cellular model of H. pylori adhesion and examined the role of sulfatides in attachment. The adhesion of H. pylori (i.e., a standard strain of H. pylori, NCTC 11637) to KATO III cells and the effects of various substances on this adhesion were monitored and semiquantitated by flow cytometric analysis. Sulfated glycoconjugates, such as heparin and gastric mucin, significantly inhibited H. pylori adhesion to KATO III cells. Membrane preparations from KATO III cells strongly inhibited this adhesion. In the membrane preparations, sulfatides were present as a major acidic glycosphinoglipid. With the exception of sulfatides, no distinct adhesion of H. pylori to glycospingolipids from KATO III cells were observed. Moreover, H. pylori did not bind to any membrane proteins of KATO III cells. Finally, a monoclonal anti-sulfatide antibody markedly reduced H. pylori adhesion to KATO III cells. These results suggest that sulfatides, and possibly related sulfated compounds, serve as a major receptor for cell adhesion by H. pylori.