RESUMEN
Glycosylation is a key modification of proteins and lipids and is involved in most intermolecular and intercellular interactions. The gastrointestinal mucus gel is continuous and can be divided into two layers: a secreted loosely associated layer and a layer firmly attached to the mucosa. In addition, the membrane-bound glycosylated proteins and lipids create a glycocalyx, which remains adherent on each cell and is dynamic and responsive to the physiological state and environment of the cell. The secreted glycans form a mucus gel layer that serves as a physicochemical sensor and barrier network and is primarily composed of mucins and associated peptides. These glycans protect gut epithelial cells from chemical, biological and physical insults and are continuously renewed. Pathogens colonise and invade the host epithelial cells using protein-protein and glycan-lectin interactions. During the process of colonisation and infection, the glycosylation state of both host and pathogen change in response to the presence of the other. This complex modulation of glycan expression critically determines pathogenesis and the host response in terms of structural changes and immune response. In addition, by influencing host immunity and gut glycosylation, the microbiota can further effect protection against pathogens. In this review, the roles of host glycosylation in interactions with two prevalent bacterial pathogens, Campylobater jejuni and Helicobacter pylori, are discussed to illustrate important concepts in pathogenesis.
Asunto(s)
Bacterias/genética , Tracto Gastrointestinal/metabolismo , Metagenoma , Animales , Tracto Gastrointestinal/microbiología , Glicosilación , Humanos , Mucosa Intestinal/metabolismo , Mucosa Intestinal/microbiologíaRESUMEN
Helicobacter pylori (H. pylori) have been recognized as a major cause of chronic gastritis, gastric and duodenal ulcers and gastric cancer. Macrophages are the targets of lipopolysaccharide (LPS), which is a constituent of the outer membrane of Gram-negative rods. In this study we focused on a potential role of macrophages in the proliferation of human peripheral blood mononuclear leukocytes (PBML) in the milieu of H. pylori LPS and standard E. coli LPS. First, we found that H. pylori and E. coli LPS induced proliferation of total PBML (tPBML) from 5 out 21 healthy blood donors (LPS responders). In the LPS milieu, tPBML from the majority of volunteers (LPS non-responders) showed a significant decrease in the [(3)H]-thymidine incorporation as compared to tPBML in medium alone. The decreased cell proliferation was associated with a diminished metabolic activity of non-adherent lymphocytes. Then, non-adherent lymphocytes were stimulated with autologous macrophages pulsed with bacterial LPS. Still, the lymphocytes from the non-responders did not proliferate in the cultures with LPS exposed macrophages. In the group of LPS responders, the macrophages pulsed with H. pylori LPS significantly reduced the proliferation of non-adherent lymphocytes. The possible mechanism regulating the responses of PBML to bacterial LPS with an implication for the outcome of H. pylori infections is discussed.
Asunto(s)
Leucocitos Mononucleares/efectos de los fármacos , Leucocitos Mononucleares/metabolismo , Lipopolisacáridos/metabolismo , Lipopolisacáridos/toxicidad , Adulto , Apoptosis/efectos de los fármacos , Apoptosis/fisiología , Proliferación Celular/efectos de los fármacos , Células Cultivadas , Femenino , Humanos , Persona de Mediana EdadRESUMEN
In Helicobacter pylori gastritis gastric epithelium plays a central role in the innate immunity to H. pylori. However, epithelial receptors interacting with H. pylori have been poorly characterized so far. Recently a new triggering receptor expressed on myeloid cells-1 (TREM-1) has been identified on human neutrophils and monocytes. On these cells TREM-1 triggers innate immunity by stimulating the secretion of interleukin (IL)-8 and tumour necrosis factor (TNF)-alpha and thus amplifies bacterial-induced inflammation. In this study expression and function of TREM-1 in gastric epithelium exposed to H. pylori has been investigated. TREM-1 mRNA and protein were expressed on gastric epithelial cell lines as demonstrated by reverse transcription-polymerase chain reaction (RT-PCR) and fluorescence activated cell sorter analysis. Gastric epithelial TREM-1 expression was up-regulated directly by H. pylori and was independent of epithelial IL-8 induced by H. pylori. Immunohistochemistry and tissue RT-PCR demonstrated significantly stronger TREM-1 expression in H. pylori gastritis compared with the non-inflamed gastric mucosa supporting in vivo that epithelial TREM-1 is up-regulated during H. pylori infection. Stimulation of gastric epithelial TREM-1 receptor resulted in IL-8 up-regulation on mRNA and protein level, as shown by real-time PCR and immunoassay. This is the first study localizing TREM-1 on gastric epithelium. Functional data suggest that TREM-1 expressed on gastric epithelium amplifies inflammation of the underlying gastric mucosa by up-regulation of IL-8.
Asunto(s)
Mucosa Gástrica/inmunología , Infecciones por Helicobacter/inmunología , Helicobacter pylori , Glicoproteínas de Membrana/metabolismo , Receptores Inmunológicos/metabolismo , Línea Celular , Células Epiteliales/inmunología , Gastritis/inmunología , Gastritis/microbiología , Expresión Génica/inmunología , Humanos , Inmunidad Innata , Interleucina-8/inmunología , Lipopolisacáridos/inmunología , Glicoproteínas de Membrana/genética , ARN Mensajero/genética , Receptores Inmunológicos/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa/métodos , Receptor Activador Expresado en Células Mieloides 1 , Regulación hacia Arriba/inmunologíaRESUMEN
BACKGROUND: The induction of general anaesthesia is associated with the greatest cardiovascular changes in elderly patients. Induction can be performed either intravenously or with gaseous induction. Sevoflurane has advantages over propofol for induction of anaesthesia in the elderly, since the lower reduction in mean arterial pressure with sevoflurane is both statistically and clinically significant. This prospective randomized controlled trial investigated the cardiovascular benefits of co-induction of anaesthesia with 0.75 mg kg(-1) propofol and 8% sevoflurane, when compared with 8% sevoflurane alone in patients requiring surgery for fractured neck of femur. METHOD: In total, 38 patients aged 75 or over were allocated into the two groups, receiving either 0.75 mg kg(-1) of propofol followed by 8% sevoflurane or 8% sevoflurane alone. Vital signs were recorded until successful insertion of a laryngeal mask. Induction times, induction events and patient satisfaction scores were also recorded. RESULTS: Results showed that there were no differences in the cardiovascular parameters between the two groups. Induction times were faster in the propofol and sevoflurane group (62 vs. 81 s; P = 0.028). The postoperative questionnaire showed that the majority of patients in both groups were satisfied with the induction process. CONCLUSIONS: We concluded that 0.75 mg kg(-1) of propofol followed by sevoflurane induction is an acceptable alternative to sevoflurane induction. It is associated with similar haemodynamic variables, faster induction times and is very well tolerated.
Asunto(s)
Anestesia General/efectos adversos , Anestésicos Combinados/efectos adversos , Presión Sanguínea/efectos de los fármacos , Frecuencia Cardíaca/efectos de los fármacos , Éteres Metílicos/efectos adversos , Propofol/efectos adversos , Anciano , Anciano de 80 o más Años , Anestesia General/métodos , Anestésicos Combinados/uso terapéutico , Anestésicos por Inhalación/efectos adversos , Anestésicos por Inhalación/uso terapéutico , Anestésicos Intravenosos/efectos adversos , Anestésicos Intravenosos/uso terapéutico , Quimioterapia Combinada , Femenino , Fracturas del Cuello Femoral/cirugía , Humanos , Masculino , Éteres Metílicos/uso terapéutico , Oximetría , Satisfacción del Paciente , Propofol/uso terapéutico , Estudios Prospectivos , Factores de Riesgo , Sevoflurano , Factores de TiempoRESUMEN
We have examined the effects of intravenous administration of a purified lipopolysaccharide (LPS) from Helicobacter pylori (3 mg kg(-1), i.v.) on rat vascular permeability, assessed by the radiolabelled human serum albumin leakage technique in the heart, kidney, liver and lung 4 h after challenge. An increased vascular permeability in cardiac, renal, hepatic and pulmonary tissues after challenge was determined. The albumin leakage observed in all these organs could be prevented by the selective inducible nitric oxide synthase inhibitor, N-(8-(aminomethyl)benzyl)-acetamidine (1400W; 0.2-1 mg kg(-1), s.c.) administered concurrently with LPS. Thus, H. pylori LPS can provoke a microvascular inflammatory response in the rat cardiac, renal, hepatic and pulmonary tissues, actions mediated through the activation of the inducible nitric oxide synthase isoenzyme.
Asunto(s)
Helicobacter pylori , Lipopolisacáridos , Óxido Nítrico Sintasa/fisiología , Vasculitis/inducido químicamente , Enfermedad Aguda , Amidinas/farmacología , Animales , Bencilaminas/farmacología , Permeabilidad Capilar/efectos de los fármacos , Circulación Coronaria/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , Lipopolisacáridos/farmacología , Circulación Hepática/efectos de los fármacos , Masculino , Microcirculación/efectos de los fármacos , Óxido Nítrico Sintasa/antagonistas & inhibidores , Óxido Nítrico Sintasa de Tipo II , Circulación Pulmonar/efectos de los fármacos , Ratas , Ratas Wistar , Circulación Renal/efectos de los fármacosRESUMEN
We studied the actions of purified Helicobacter pylori endotoxin (3 mg kg(-1), i.v.) on rat intestinal vascular permeability (assessed by the radiolabelled human serum albumin leakage technique) and on nitric oxide synthase induction (assessed by the citrulline assay) 4 h later. We found increased albumin leakage and expression of the inducible nitric oxide synthase in jejunum and colon, effects reversed by a selective inducible nitric oxide synthase inhibitor N-(8-(aminomethyl)benzyl)-acetamidine (1400W; 0.2-1 mg kg(-1), s.c., concurrently with endotoxin). Thus, H. pylori endotoxin seems to be capable of provoking an inflammatory response in the rat intestinal tissue. Systemic liberation of H. pylori endotoxin might possibly attenuate jejunal and colonic mucosal barrier function, a process mediated by the expression of the inducible nitric oxide synthase.
Asunto(s)
Endotoxinas , Enteritis/inducido químicamente , Helicobacter pylori , Óxido Nítrico Sintasa/antagonistas & inhibidores , Amidinas/farmacología , Animales , Bencilaminas/farmacología , Permeabilidad Capilar/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Endotoxinas/farmacología , Inhibidores Enzimáticos/farmacología , Humanos , Intestinos/irrigación sanguínea , Intestinos/enzimología , Masculino , Óxido Nítrico Sintasa/metabolismo , Óxido Nítrico Sintasa de Tipo II , Ratas , Ratas Wistar , Albúmina Sérica/farmacocinéticaRESUMEN
Lewis (Le) antigens have been implicated in the pathogenesis of atrophic gastritis and gastric cancer in the setting of Helicobacter pylori infection, and H. pylori-induced anti-Le antibodies have been described that cross-react with the gastric mucosa of both mice and humans. The aim of this study was to examine the presence of anti-Le antibodies in patients with H. pylori infection and gastric cancer and to examine the relationships between anti-Le antibody production, bacterial Le expression, gastric histopathology, and host Le erythrocyte phenotype. Anti-Le antibody production and H. pylori Le expression were determined by enzyme-linked immunosorbent assay, erythrocyte Le phenotype was examined by agglutination assays, and histology was scored blindly. Significant levels of anti-Le(x) antibody (P < 0.0001, T = 76.4, DF = 5) and anti-Le(y) antibody (P < 0.0001, T = 73.05, DF = 5) were found in the sera of patients with gastric cancer and other H. pylori-associated pathology compared with H. pylori-negative controls. Following incubation of patient sera with synthetic Le glycoconjugates, anti-Le(x) and -Le(y) autoantibody binding was abolished. The degree of the anti-Le(x) and -Le(y) antibody response was unrelated to the host Le phenotype but was significantly associated with the bacterial expression of Le(x) (r = 0.863, r(2) = 0.745, P < 0.0001) and Le(y) (r = 0.796, r(2) = 0.634, P < 0.0001), respectively. Collectively, these data suggest that anti-Le antibodies are present in most patients with H. pylori infection, including those with gastric cancer, that variability exists in the strength of the anti-Le response, and that this response is independent of the host Le phenotype but related to the bacterial Le phenotype.
Asunto(s)
Autoanticuerpos/inmunología , Autoantígenos/inmunología , Gastritis Atrófica/inmunología , Infecciones por Helicobacter/inmunología , Helicobacter pylori/inmunología , Antígenos del Grupo Sanguíneo de Lewis/inmunología , Antígeno Lewis X/inmunología , Neoplasias Gástricas/inmunología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Autoanticuerpos/sangre , Autoinmunidad/inmunología , Enfermedad Crónica , Femenino , Gastritis Atrófica/sangre , Gastritis Atrófica/patología , Infecciones por Helicobacter/sangre , Infecciones por Helicobacter/patología , Humanos , Inmunofenotipificación , Masculino , Persona de Mediana Edad , Neoplasias Gástricas/sangre , Neoplasias Gástricas/patologíaRESUMEN
The actions of a purified Helicobacter pylori lipopolysaccharide (3 mg x kg(-1), i.v.) on rat gastric antral and duodenal microvascular integrity (determined as radiolabelled albumin leakage) and the expression of the inducible nitric oxide (NO) synthase (iNOS; assessed by the citrulline assay) were investigated 4 h after challenge. Significant increases of albumin leakage and expression of iNOS in both antral and duodenal tissues were observed following challenge. Concurrent administration of the selective iNOS inhibitor, 1400W (N-(8-(aminomethyl)benzyl)-acetamidine; 0.2-1 mg x kg(-1), s.c.), with lipopolysaccharide, caused a dose-dependent attenuation of the gastric and duodenal albumin leakage. Thus, H. pylori lipopolysaccharide can initiate the expression of iNOS in the stomach and duodenum following systemic challenge, which can provoke gastroduodenal microvascular dysfunction.
Asunto(s)
Permeabilidad Capilar/efectos de los fármacos , Sistema Digestivo/efectos de los fármacos , Lipopolisacáridos/toxicidad , Óxido Nítrico Sintasa/metabolismo , Amidinas/farmacología , Animales , Bencilaminas/farmacología , Sistema Digestivo/irrigación sanguínea , Sistema Digestivo/patología , Relación Dosis-Respuesta a Droga , Duodeno/efectos de los fármacos , Duodeno/enzimología , Duodeno/patología , Inhibidores Enzimáticos/farmacología , Helicobacter pylori/química , Humanos , Masculino , Óxido Nítrico Sintasa/antagonistas & inhibidores , Óxido Nítrico Sintasa de Tipo II , Antro Pilórico/efectos de los fármacos , Antro Pilórico/enzimología , Antro Pilórico/patología , Ratas , Ratas Wistar , Albúmina Sérica/metabolismoRESUMEN
As a bacterial product, Helicobacter pylori lipopolysaccharide (LPS) can originate in close proximity to parietal cells, but the role of this uniquely structured endotoxin on acid secretion has not been fully investigated and remains unclear. The purpose of this study was to test the direct effect of purified LPS (tested range, 0.1 to 100 microg/ml) from various strains of H. pylori and from one Helicobacter felis strain on histamine- and carbachol-stimulated acid secretion in vitro using mouse gastric glands and the accumulation of [(14)C]aminopyrine. In addition, we investigated whether H. pylori LPS can interfere with two native antisecretory substances, prostaglandin E(2) (PGE(2)) and somatostatin, which may contribute to bacterial pathogenicity. Except for the LPS from H. pylori SS1 (Sydney strain), which gave a statistically significant increase in both histamine- and carbachol-stimulated acid output (38 and 24%, respectively; P < 0.05), no effect of the tested LPS was observed on acid secretion. H. pylori LPS purified from a patient isolate did not affect the potency or the efficacy of the inhibitory dose response curve to PGE(2) or somatostatin. Bacterial interstrain variation in the direct stimulatory effect of Helicobacter-derived LPS on acid secretion was observed, which probably reflects the molecular structure of LPS and the potential to contribute to virulence. Importantly, the data showed that H. pylori LPS did not have any direct antisecretory properties. It can be speculated that the acid stimulatory properties of LPS from H. pylori SS1 may contribute to the gastric damage observed in the mouse model of H. pylori infection.
Asunto(s)
Ácido Gástrico/metabolismo , Mucosa Gástrica/efectos de los fármacos , Helicobacter pylori/metabolismo , Helicobacter/metabolismo , Lipopolisacáridos/farmacología , Animales , Carbacol/farmacología , Dinoprostona/farmacología , Modelos Animales de Enfermedad , Úlcera Duodenal/microbiología , Femenino , Mucosa Gástrica/metabolismo , Infecciones por Helicobacter/microbiología , Histamina/farmacología , Humanos , Ratones , Ratones Endogámicos BALB C , Somatostatina/farmacologíaRESUMEN
Molecular mimicry of host structures by the saccharide portion of lipopolysaccharides (LPS) of the gastrointestinal pathogens Campylobacter jejuni and Helicobacter pylori is thought to be associated with the development of autoimmune sequelae. C. jejuni, a leading cause of gastroenteritis, is the most common antecedent infection in Guillain-Barré syndrome (GBS), an inflammatory neuropathy. Chemical analyses of the core oligosaccharides of neuropathy-associated C. jejuni strains have revealed structural homology with human gangliosides. Serum antibodies against gangliosides are found in one third of GBS patients but are generally absent in enteritis cases. Collective data suggest that the antibodies are induced by antecedent infection with C. jejuni, and subsequently react with nerve tissue causing damage. The O-chains of most H. pylori strains express Lewis blood group antigens which are thought to have a role in camouflage of the bacterium as these antigens are also present on human gastric epithelial cells. In chronic H. pylori infections, bacterial expression of Lewis antigens is suggested to be involved in the induction of autoantibodies against the Lewis antigen-expressing gastric proton pump. Many aspects of the autoimmune mechanisms in C. jejuni -associated GBS and H. pylori -induced atrophic gastritis remain unclear, such as the involvement of T cells and the role of host factors.
Asunto(s)
Autoinmunidad/inmunología , Campylobacter jejuni/inmunología , Helicobacter pylori/inmunología , Lipopolisacáridos/inmunología , Imitación Molecular/inmunología , Animales , Enfermedades Gastrointestinales/inmunología , Síndrome de Guillain-Barré/inmunología , Humanos , Antígenos del Grupo Sanguíneo de Lewis/inmunología , Lipopolisacáridos/químicaRESUMEN
Mimicry of peripheral nerve gangliosides by Campylobacter jejuni lipopolysaccharides (LPSs) has been proposed to induce cross-reacting antiganglioside antibodies in Guillain-Barré syndrome (GBS). Because current methods for LPS characterization are labor-intensive and inhibit the screening of large numbers of strains, a rapid GM(1) epitope screening assay was developed. Biomass from two agar plates of confluent growth yielded sufficient LPS using a novel phenol-water and ether extraction procedure. Extracts of LPS were reacted with cholera toxin (GM(1) ligand), peanut agglutinin (Gal beta1-->3GalNAc ligand), and anti-GM(1) antibodies. After the assay was validated, 12 of 59 (20%) C. jejuni serostrains, including four serotypes that have not previously been associated with GBS, reacted with two or more anti-GM(1) ganglioside reagents. Subsequently, LPS extracts from 5 of 7 (71%) C. jejuni isolates and 2 of 3 (67%) C. jejuni culture collection strains bore GM(1) structures. Overall, the assay system was reliable, efficient, and reproducible and may be adapted for large-scale epidemiological studies.
Asunto(s)
Campylobacter jejuni/inmunología , Epítopos/inmunología , Gangliósido G(M1)/inmunología , Lipopolisacáridos/inmunología , Imitación Molecular , Campylobacter jejuni/clasificación , Campylobacter jejuni/crecimiento & desarrollo , Cromatografía en Capa Delgada , Gangliósido G(M1)/química , Humanos , Inmunoensayo/métodos , Lipopolisacáridos/químicaRESUMEN
A lipopolysaccharide (LPS) was isolated by hot phenol-water extraction from Helicobacter pylori strain D4 and found to contain no fucosylated poly-N-acetyllactosamine chain typical of most H. pylori strains studied but a homopolymer of D-glycero-D-manno-heptose (DD-Hep). The heptan attached to a core oligosaccharide was released by mild acid degradation of the LPS, and the following structure of the trisaccharide-repeating unit was established by chemical methods and 1H and 13C NMR spectroscopy: --> 2)-D-alpha-D-Hepp-(1 --> 3)-D-alpha-D-Hepp-(1 --> 3)-D-alpha-D-Hepp-(1 -->. 1H NMR spectroscopy performed on small amounts of the intact LPS revealed the presence of the same polysaccharide in LPS of H. pylori strains D2 and D5, but not strain D10.
Asunto(s)
Helicobacter pylori/química , Heptosas/química , Lipopolisacáridos/química , Espectroscopía de Resonancia MagnéticaRESUMEN
Lipopolysaccharides (LPS) are major antigenic components of the outer membrane of Gram-negative bacteria and can stimulate activation of the complement system. Such activation leads to formation of the complement membrane attack complex (MAC) on the cell walls, LPS release and, in serum-sensitive strains, to cell death. In this study, Escherichia coli J5 strains, which incorporate exogenous galactose exclusively into LPS, were used to generate target strains with different LPS chemotypes, and the LPS of the strains was labelled with tritium (3H-LPS). The ability of normal human serum (NHS) and human complement-deficient sera to release LPS was subsequently monitored. NHS-induced release of 64-95.7% of 3H-LPS within 30 min; overall, no significant difference was observed between release of LPS from E. coli J5 strains with different LPS chemotypes. In functional assays, maximum LPS release had occurred by 30 min and before maximum bacterial killing. Electron microscopy revealed NHS-induced outer-membrane disruption in the form of blebs at 15 min; at this time-point the inner membrane remained intact. Background LPS release and no bactericidal activity were detected in heat-inactivated serum or human sera deficient in C6, C7 or C8. The C9-deficient (C9D) serum had low bactericidal activity and failed to induce LPS release; however, addition of purified human C9 reconstituted its ability to release LPS. This study demonstrated the need for functional C9 molecules for LPS-releasing activities in serum-sensitive E. coli J5 strains.
Asunto(s)
Complemento C9/inmunología , Escherichia coli/inmunología , Lipopolisacáridos/metabolismo , Actividad Bactericida de la Sangre/inmunología , Membrana Celular/ultraestructura , Escherichia coli/metabolismo , Escherichia coli/ultraestructura , Galactosa/metabolismo , Humanos , Microscopía ElectrónicaRESUMEN
The prevalence of clarithromycin resistance-associated mutations, the cytotoxin-associated gene (cagA), and the various vacuolating cytotoxin (vacA) genotypes was determined in 50 gastric biopsy specimens from Helicobacter pylori-infected patients, using line probe assays. The clarithromycin resistance-associated mutation A2143G was detected in H. pylori strains from 26% of the specimens, which suggested that the high rate of H. pylori treatment failure in Ireland may be partly attributable to the presence of these mutations. All strains examined carried the vacA s1 genotype, and 76% were cagA positive. Of these 50 specimens, 13 (26%) carried H. pylori strains with vacA midregion genotype m1, 29 (58%) carried strains that were m2, 1 (2%) was infected by a strain that was positive for both m1 and m2, and 7 (14%) carried strains that could not be typed.
Asunto(s)
Antibacterianos/farmacología , Antígenos Bacterianos , Proteínas Bacterianas/genética , Claritromicina/farmacología , Infecciones por Helicobacter/epidemiología , Helicobacter pylori/efectos de los fármacos , Biopsia , Sondas de ADN , ADN Bacteriano/análisis , Digoxigenina/metabolismo , Farmacorresistencia Microbiana/genética , Genes de ARNr , Genotipo , Infecciones por Helicobacter/microbiología , Helicobacter pylori/clasificación , Helicobacter pylori/genética , Humanos , Irlanda , ARN Ribosómico 23S/genética , Estómago/microbiologíaRESUMEN
BACKGROUND AND AIMS: Helicobacter pylori is a frequent gram-negative colonizer of the human stomach. Its interaction with complement may be involved in the pathogenesis of chronic gastritis, and was mechanistically studied in vitro. METHODS: Four H. pylori strains, 2 cytotoxin-associated genes (cag)A+ and 2 cagA-, were isolated from infected patients. Bacteria or purified H. pylori lipopolysaccharides (LPSs) were incubated with nonimmune serum at 37 degrees C; the activation products C3b/iC3b/C3c (C3bc) and terminal complement complex (TCC) were then quantified by immunoassays. The serum sensitivity of 1 strain (L01, cagA+) was tested by counting the numbers of colony-forming units. RESULTS: All strains and LPSs generated large amounts of C3bc and TCC. Blocking of the classic complement pathway by the calcium chelator ethylene glycol tetraacetic acid (EGTA) markedly reduced the complement products, suggesting that H. pylori and its LPSs directly engage the classic activation pathway. H. pylori was shown to be serum sensitive, but 30% or more nonimmune serum was necessary to induce marked killing. After 5 minutes, swelled bacteria coated with C3bc and TCC were shown. CONCLUSIONS: H. pylori is complement sensitive and activates the classic pathway even in the absence of specific antibodies. Released cell wall constituents such as LPSs can activate complement and may explain why this bacterium induces gastric pathology without invading the mucosa.
Asunto(s)
Antígenos Bacterianos , Activación de Complemento/inmunología , Infecciones por Helicobacter/inmunología , Helicobacter pylori/inmunología , Anticuerpos Antibacterianos/inmunología , Proteínas Bacterianas/genética , Proteínas Sanguíneas/farmacología , Activación de Complemento/efectos de los fármacos , Complemento C3b/inmunología , Complemento C3c/inmunología , ADN Bacteriano/análisis , Técnica del Anticuerpo Fluorescente , Helicobacter pylori/genética , Humanos , Técnicas In Vitro , Lipopolisacáridos/farmacologíaRESUMEN
The structure of the core oligosaccharide of aerotolerant Campylobacter jejuni 0:2 lipopolysaccharide was determined and found to contain 3-deoxy-D-manno-octulosonic acid (Kdo), L-glycero-D-manno-heptose (LD-Hep), D-galactose, D-glucose, and phosphorylethanolamine (PEtn). Based on 1H, 13C and 31P NMR spectroscopic studies including 2D COSY, TOCSY, ROESY and heteronuclear 1H-31P and HMQC experiments it was established that the oligosaccharide has the following structure: [structure: see text].
Asunto(s)
Campylobacter jejuni/química , Lipopolisacáridos/química , Oligosacáridos/química , Conformación de Carbohidratos , Secuencia de Carbohidratos , Lipopolisacáridos/inmunología , Lipopolisacáridos/aislamiento & purificación , Datos de Secuencia Molecular , Resonancia Magnética Nuclear Biomolecular , Antígenos O/química , Antígenos O/aislamiento & purificación , Oligosacáridos/inmunología , Isótopos de FósforoRESUMEN
In mimicry with human gastric epithelial cells, the lipopolysaccharide of Helicobacter pylori expresses Lewis blood group antigens. Recent data suggest that molecular mimicry does not promote immune evasion, nor does it lead to induction of autoantibodies, but that H. pylori Lewis X mediates adhesion to gastric epithelial cells and is essential for colonization.