Pylori Lipopolysaccharide Research Articles

Antigenic mimicry between Helicobacter pylori and gastric mucosa: failure to implicate heat-shock protein Hsp60 using immunoelectron microscopy.

Helicobacter pylori infection induces autoantibodies that cross-react with human gastric mucosa from infected individuals. Candidates for the antigens responsible for molecular mimicry causing autoreactivity include the heat-shock protein HspB (Hsp60, sometimes called Hsp54) or Lewis x and Lewis y carbohydrate antigens. Our goal was to investigate the involvement of HspB (Hsp60) in autoreactivity between H. pylori and gastric biopsy tissue. Immunoelectron microscopy was used to study cross-reactivity among biopsy tissues from a patient with gastritis, gastric ulcer, and duodenal ulcer and his own serum as well as reactivity with serum raised against HspB from H. pylori and monoclonal antibodies against Lewis antigens. The patient serum reacted with gastric mucosa, and the antibodies involved were predominantly IgG. Antibody raised to H. pylori HspB (Hsp60) reacted only with H. pylori cells but not with gastric mucosal tissue. In contrast, monoclonal antibodies specific for Lewis x and Lewis y antigens reacted with both H. pylori and human gastric epithelial tissue. Hsp60 (Hsp54) is unlikely to be involved in autoreactivity seen in individuals infected with H. pylori. In contrast, we could not rule out the role of Lewis x and Lewis y carbohydrate antigens, expressed as a component of H. pylori lipopolysaccharides, in molecular mimicry and autoantibody production.

The role of Helicobacter pylori LPS in the pathogenesis of H. pylori-related gastropathy

Helicobacter pylori strains and/or their lipopolysaccharides (LPS) represent the trigger of different regional and systemic immune responses in the course of H. pylori-related gastropathy as indicated by the following: (i) in patients with chronic gastritis (CG) or duodenal ulcer (DU), eradication of H. pylori leads to a dramatic decrease of gastric mucosal content of various cytokines such as interleukin-1β and transforming growth factor-β1; (ii) gastric epithelial cells are activated by H. pylori organisms through tyrosine phosphorylation signaling events but H. pylori LPSs do not affect this signal transduction pathway; and (iii) in sera from patients with CG and DU, besides antibodies to S-form LPS, humoral IgG and IgA response against R-form LPS has been also detected. On the other hand, antibodies against synthetic polymeric Lewisx were found in a few patients with CG and in no patients with DU.

Gastric Mucosal Inflammatory Responses to Helicobacter pylori Lipopolysaccharide: Down-regulation of Nitric Oxide Synthase-2 and Caspase-3 by Sulglycotide

We applied the animal model of H. pylori lipopolysaccharide-induced gastritis to assess the effect of antiulcer agent, sulglycotide, on the mucosal inflammatory responses by analyzing the interplay between the activity of a key apoptotic caspase, caspase-3, epithelial cell apoptosis, and the expression of constitutive (cNOS) and inducible (NOS-2) nitric oxide synthase. H. pylori lipopolysaccharide applied intragastrically elicited within 4 days a pattern of mucosal responses resembling that of acute gastritis. This was accompanied by an 11.2-fold increase in epithelial cell apoptosis, a 6.5-fold induction in mucosal expression of NOS-2 and a 2.2-fold decline in cNOS, and a 5.4-fold increase in caspase-3 activity. Treatment with sulglycotide led to a 56.7% reduction in the extent of mucosal inflammatory changes elicited by H. pylori lipopolysaccharide and an 88.3% decrease in the epithelial cells apoptosis. Furthermore, this effect of sulglycotide was associated with a 51% decrease in mucosal expression of caspase-3 activity, a 73.7% decline in NOS-2, and a 64.1% increase in cNOS. The findings suggest that sulglycotide suppresses the H. pylori-induced mucosal inflammatory responses by up-regulating cNOS and interfering with the events propagated by NOS-2 and caspase-3.

Gastric mucosal inflammatory responses toHelicobacter pylori lipopolysaccharide: suppression of caspase-3 and nitric oxide synthase-2 by omeprazole and sucralfate.

Helicobacter pylori lipopolysaccharide is a primary virulence factor responsible for eliciting acute mucosal inflammatory responses associated with H. pylori infection. In this study, we investigated the activity of a key apoptotic protease, caspase-3, and the expression of inducible nitric oxide synthase (NOS-2) during H. pylori lipopolysaccharide-induced acute gastritis, and evaluated the effect of anti-ulcer agents, omeprazole and sucralfate, on this process. Rats, pretreated twice daily with omeprazole at 40 mg/kg, sucralfate at 100 mg/kg, or the vehicle, were subjected to intragastric application of H. pylori lipopolysaccharide at 50 microg/animal, and after 4 additional days on the anti-ulcer drug or vehicle regimen their mucosal tissue was used for histologic assessment, assays of epithelial cells apoptosis, and the measurements of caspase-3 and NOS-2 activities. In the absence of anti-ulcer agents,H. pylori lipopolysaccharide induced acute reaction characterized by the inflammatory infiltration of the lamina propria, hyperemia, and epithelial hemorrhage. This was accompanied by an 11.2-fold increase in epithelial cell apoptosis, a 6.5-fold induction in mucosal expression of NOS-2, and a 5.4-fold increase in caspase-3 activity. Treatment with proton pump inhibitor, omeprazole, produced a 39.6% reduction in the extent of mucosal inflammatory changes elicited by H. pylori lipopolysaccharide and a 75.5% decrease in the epithelial cells apoptosis, while the activity of caspase-3 decreased by 26.8% and that of NOS-2 showed a 46.7% decline. The gastroprotective agent, sucralfate, evoked a 62.3% reduction in the extent of mucosal inflammatory changes caused by the lipopolysaccharide, epithelial cell apoptosis decreased by 85.8%, and NOS-2 showed a 68.2% decline, while the activity of caspase-3 decreased by 39.7%. Our findings implicate caspase-3 involvement in gastric mucosal inflammatory responses toH. pylori lipopolysaccharide, and point towards participation of NOS-2 in the amplification of the cell death-signaling cascade. We also show that anti-ulcer agents, omeprazole and sucralfate, are capable of suppressing the H. pylori-induced mucosal inflammatory responses by interfering with the events propagated by NOS-2 and caspase-3.

Suppression of gastric mucosal inflammatory responses to Helicobacter pylori lipopolysaccharide by sulglycotide

The effect of the antiulcer agent sulglycotide on gastric epithelial cell apoptosis and the expression of tumor necrosis factor-α (TNF-α) and interleukin-4 (IL-4) during Helicobacter pylori lipopolysaccharide-induced acute gastritis was investigated. Rats, pretreated twice daily for 3 consecutive days with sulglycotide at 200 mg/kg or vehicle, were subjected to surface epithelial application of H. pylori lipopolysaccharide (50 μg/animal), and, after 4 additional days on the drug or vehicle regimen, their mucosal tissue was used for histologic assessment, quantitation of TNF-α and IL-4, and the assay of epithelial cell apoptosis. In the absence of sulglycotide, H. pylori lipopolysaccharide caused acute mucosal responses manifested by the inflammatory infiltration of the lamina propria with lymphocytes and plasma cells, edema, hyperemia, and epithelial hemorrhage. These responses were accompanied by an 11-fold increase in epithelial cell apoptosis and a 9-fold enhancement of the mucosal expression of proinflammatory cytokine TNF-α. However, the mucosal expression of regulatory cytokine IL-4 decreased by 15%. Treatment with sulglycotide produced significant (56.6%) reduction in the extent of acute mucosal inflammatory changes caused by H. pylori lipopolysaccharide. Moreover, the effect of sulglycotide was manifested in an 88.3% reduction in the epithelial cell apoptosis and a 69.1% decrease in the mucosal expression of TNF-α, whereas the expression of IL-4 showed only marginal (6%) enhancement. The results suggest that the cytoprotective agent sulglycotide suppresses the inflammatory and apoptotic events elicited in gastric mucosa by H. pylori lipopolysaccharide through stimulation of TNF-α expression.

Helicobacter pylori lipopolysaccharide binds to CD14 and stimulates release of interleukin-8, epithelial neutrophil-activating peptide 78, and monocyte chemotactic protein 1 by human monocytes.

Helicobacter pylori gastritis is characterized by leukocyte infiltration of the gastric mucosa. The aims of this study were to determine whether H. pylori-derived factors stimulate chemokine release from human monocytes and to ascertain whether H. pylori lipopolysaccharide (LPS) may be responsible for this effect. Human peripheral blood monocytes were exposed to an H. pylori water extract (HPE) or to purified H. pylori LPS. Levels of the chemokines interleukin-8 (IL-8), epithelial neutrophil-activating peptide 78 (ENA-78), and monocyte chemotactic protein 1 (MCP-1) were measured by enzyme-linked immunosorbent assay. The contribution of H. pylori LPS to monocyte activation was determined by using the LPS antagonist Rhodobacter sphaeroides lipid A (RSLA) and a blocking monoclonal antibody to CD14 (60bca). HPE increased monocyte secretion of IL-8, ENA-78, and MCP-1. Heat treatment of HPE did not reduce its ability to activate monocytes. Purified H. pylori LPS also stimulated monocyte chemokine production but was 1,000-fold less potent than Salmonella minnesota lipid A. RSLA blocked H. pylori LPS-induced monocyte IL-8 release in a dose-dependent fashion (maximal inhibition 82%, P < 0.001). RSLA also inhibited HPE-induced IL-8 release (by 93%, P < 0.001). The anti-CD14 monoclonal antibody 60bca substantially inhibited IL-8 release from HPE-stimulated monocytes (by 88%, P < 0.01), whereas the nonblocking anti-CD14 monoclonal antibody did not. These experiments with potent and specific LPS inhibitors indicate that the main monocyte-stimulating factor in HPE is LPS. H. pylori LPS, acting through CD14, stimulates human monocytes to release the neutrophil-activating chemokines IL-8 and ENA-78 and the monocyte-activating chemokine MCP-1. Despite its low relative potency, H. pylori LPS may play an important role in the pathogenesis of H. pylori gastritis.

The products of Helicobacter pylori that induce inflammation

Outer membrane of Helicobacter pylori The bacterium H. pylori is known to cause chronic gastric and duodenal infection. As a result of H. pylori colonization, there is an inflammatory response in the gastric mucosa and the host produces a range of immunological mediators in an attempt to eliminate the organism. Despite this, in many cases the bacterium persists, suggesting that the outer membrane of H. pylori may have evolved to minimize the immunological response and ensure survival of the organism in the gastric environment Lipid A component In common with other bacterial species, the lipid A component of H. pylori lipopolysaccharide in the outer membrane endows the molecule with a range of immunological properties, but there are major structural differences between the lipid A of different species. H. pylori lipid A has an unusual phosphorylation and fatty acid substitution pattern which appears to translate into biological differences, since H. pylorilipid A has been shown to have lower immunological activity than that of some other species. H. pylori cell surface proteins, however, are potent inducers of the inflammatory mediators. Balance in host's inflammatory response There appears to be a balance between minimizing the host's inflammatory response to protect the bacterium and stimulating the inflammatory response, which results in chronic infection in the host Neutrophil infiltration, a characteristic of H. pylori infection, and neutrophil migration across the endothelium, is a result of the unique regulation of adhesion molecules on these cells by the bacterium.

Influence of ammonia (NH4OH) and H. Pylori lipopolysaccharide (HP-LPS) on gastric secretion in conscious dogs and rats

Influence of ammonia (NH4OH) and H. Pylori lipopolysaccharide (HP-LPS) on gastric secretion in conscious dogs and rats

Prevention of rat duodenal epithelial cell injury provoked by purified Helicobacter pylori lipopolysaccharide by the highly selective inhibitor of inducible nitric oxide synthase, 1400 W

Prevention of rat duodenal epithelial cell injury provoked by purified Helicobacter pylori lipopolysaccharide by the highly selective inhibitor of inducible nitric oxide synthase, 1400 W

Effect of Sucralfate on Gastric Mucosal Inflammatory Responses Induced by Helicobacter pylori Lipopolysaccharide

Background: Helicobacter pylori

Delayed gastric emptying by Helicobacter pylori lipopolysaccharide in conscious rats.

The present study was carried out to investigate the possibility that lipopolysaccharide deprived from Helicobacter pylori may alter gastric motility. To address the question, we examined the effect of H. pylori lipopolysaccharide on gastric emptying in conscious rats. Gastric emptying was evaluated by the phenol red method. Time-course and dose-related effects of intraperitoneal administration of H. pylori lipopolysaccharide were investigated. Intraperitoneal injection of H. pylori lipopolysaccharide significantly suppressed gastric emptying of a liquid meal in a dose-dependent manner. The inhibitory action of H. pylori lipopolysaccharide was observed 2, 4, 8, or 12 hr after the injection. These results suggest for the first time that H. pylori lipopolysaccharide may suppress gastric emptying in a long-lasting fashion. It is also suggested that H. pylori may influence gastric function through its cell wall structure named lipopolysaccharide.

Serum antibody response against Helicobacter pylori NCTC 11637 smooth- and rough-lipopolysaccharide phenotypes in patients with H. pylori-related gastropathy

The antigenicity of the Helicobacter pylori lipopolysaccharide (LPS) molecule during the course of natural H. pylori infection in humans was investigated. The IgG and IgA responses against smooth (S)- and rough (R)-form LPS were evaluated in H. pylori positive patients with chronic gastritis (CG, n = 30) and duodenal ulcer disease (DU, n = 16), and in 15 H. pylori-negative dyspeptic subjects. The results demonstrated that anti H. pylori LPS IgG and IgA antibody levels were significantly enhanced in both groups of H. pylori-positive patients compared with H. pylori-negative subjects, thus confirming that H. pylori LPS is part of the immunogenic antigen profile of the bacterium. In addition, a marked response against R-LPS, which significantly correlated with that observed against S-LPS, was found for both IgG and IgA, thus indicating that core oligosaccharide plays a powerful immunogenic role. Since the O-side chain of LPS from H. pylori NCTC 11637 contains epitopes which mimic Lewis x (Lex) antigens, the presence of antibodies to monomeric, trimeric, and polymeric Lex was also investigated. Antibodies against polymeric Lex were detected in two patients suffering from chronic atrophic gastritis and active chronic gastritis, respectively.

Helicobacter pylori lipopolysaccharide stimulates histamine release and DNA synthesis in rat enterochromaffin-like cells

BACKGROUND & AIMS: Helicobacter pylori alterations in gastric acid output and mucosal proliferation may involve the enterochromaffin-like (ECL) cell. To test whether H. pylori affects ECL cell histamine secretion and proliferation, the effect of lipopolysaccharide (LPS) on ECL cell function in vitro was investigated.METHODS: Using a rat ECL cell preparation of high purity (+/-95%), basal and stimulated histamine secretion and DNA synthesis were measured by enzyme immunoassay and bromodeoxyuridine (BrdU) uptake, respectively.RESULTS: Escherichia coli LPS (10(-12) to 10(-6) mol/L) had no effect on basal and stimulated histamine secretion at concentrations of > 10(-6) mol/L. H. pylori LPS stimulated basal and gastrin-stimulated histamine secretion. These effects were completely inhibited by somatostatin (10(- 10) mol/L) but not by the gastrin receptor antagonist L365,260 at 10(- 6) mol/L. E. coli LPS had a weak stimulatory effect on ECL cell BrdU uptake at 10(-6) mol/L but had no effect on gastrin-stimulated BrdU uptake. H. pylori LPS did not stimulate basal synthesis but significantly increased (1.5-fold) gastrin-stimulated BrdU uptake.CONCLUSIONS: H. pylori influences both ECL cell proliferation and secretion in vitro. An interaction between H. pylori LPS and ECL cells may contribute to the reported abnormalities in acid secretion and gastric pathobiology noted in H. pylori infections.(Gastroenterology 1997 Oct;113(4):1110-7)

Helicobacter pylori induces proinflammatory cytokines and major histocompatibility complex class II antigen in mouse gastric epithelial cells

Although Helicobacter pylori has been reported to stimulate the release of various cytokines from gastric tissue, it remains unknown whether normal and nontumorous gastric epithelial cells produce these cytokines. Therefore, in this study, we used a normal mouse gastric surface mucous cell line (GSM06) to determine whether gastric epithelial cells produce proinflammatory cytokines in response to H. pylori. The expression of MHC class II antigen was also examined, to investigate whether gastric epithelial cells participate in the immune response to H. pylori. In the study, GSM06 cells were incubated with H. pylori or its lipopolysaccharide (LPS). Proinflammatory cytokines were detected by Northern and Western blot analysis. The expression of MHC class II antigen was examined by fluorescence activated cell sorter (FACS) analysis. Genetic expression of proinflammatory cytokines such as interleukin-1α, tumor necrosis factor-α, and cytokine-induced neutrophil chemoattractant-2β was enhanced by both intact and sonicated H. pylori, but not by H. pylori LPS. The expression of MHC class II antigen was induced by H. pylori more strongly than by interferon-γ. We conclude that H. pylori induces the expression of proinflammatory cytokines and MHC class II antigen in gastric epithelial cells. Gastric epithelial cells may act as antigen-presenting cells and participate in the immune response to H. pylori infection.

Low antigenicity of the polysaccharide region of Helicobacter pylori lipopolysaccharides derived from tumors of patients with gastric cancer

We have examined the antibody response to Helicobacter pylori lipopolysaccharide (LPS) during natural infection in humans. The sera of over 70% of H. pylori-infected individuals were found to contain immunoglobulin G antibodies against the LPS fractions isolated from smooth strains of H. pylori but not against those derived from rough strains, as determined by enzyme-linked immunosorbent assay. These results taken together with the immunoblot data indicated that the polysaccharide region of H. pylori LPS is antigenic in humans. However, the antigenicity of the polysaccharide varied, depending on the strain. We found that smooth H. pylori strains isolated from the tumors of patients with gastric cancer showed significantly lower antigenicity than smooth strains derived from patients with chronic gastritis and gastric and duodenal ulcers. The results suggest that the levels of antigenicity of the polysaccharide region of H. pylori LPS in humans correlate with the nature of the gastroduodenal diseases and that they allow a particular distinction to be made between gastric cancer and other gastroduodenal diseases, especially chronic gastritis.

Reactivities of Lewis antigen monoclonal antibodies with the lipopolysaccharides of Helicobacter pylori strains isolated from patients with gastroduodenal diseases in Japan.

We have examined the reactivity of monoclonal antibodies (MAbs) specific for Lewis antigens (Le(x), Le(y), Le(a), and Le(b)) with Helicobacter pylori lipopolysaccharides (LPS) by immunoblot analysis and enzyme-linked immunosorbent assay (ELISA). Sixty-eight strains of H. pylori were isolated from patients with chronic gastritis, gastric and duodenal ulcers, and gastric cancer in Japan. The cells were treated with proteinase K, and the resulting fractions were used as a source of LPS for the immunoassays. In the immunoblot analysis, 28 isolates (41%) and 29 isolates (42%) reacted with anti-Le(x) and anti-Le(y) MAbs, respectively, while 4 isolates (6%) and 7 isolates (10%) reacted with anti-Le(a) and anti-Le(b) MAbs. On the other hand, in ELISA, the number of isolates that reacted with anti-Le(x) MAbs fell significantly to 21 isolates (30%) but the number of isolates that reacted with the other anti-Lewis antigen MAbs remained relatively unchanged. These data show that the immunoblotting technique is more sensitive than the ELISA technique for the detection of immunocomplexes of anti-Le(x) MAbs and components of H. pylori LPS. Furthermore, human serum was found to react with the synthetic Lewis antigens regardless of the status of the individual's H. pylori infection. This means that humans may naturally possess antibodies against Lewis antigens in the absence of H. pylori infection.

Helicobacter pylori lipopolysaccharide inhibition of gastric somatostatin receptor: effect of sucralfate.

In this study, we investigated the inhibitory effect of Helicobacter pylori lipopolysaccharide on the binding of somatostatin to gastric epithelial cell membrane receptor, and assessed the effect of antiulcer agent, sucralfate, on this process. The assays conducted with the somatostatin receptor, purified from the solubilized epithelial cell membranes by affinity chromatography on Affi-Gel-[D-Tryp8]SRIF-14, revealed a dose-dependent inhibition in receptor-somatostatin binding by the lipopolysaccharide which reached a maximum of 94.1%. This effect of H. pylori lipopolysaccharide was countered by sucralfate that produced a 92.5% restoration in receptor-somatostatin binding at 70 micrograms/ml of the drug. The findings demonstrate that sucralfate is capable of reversing the interference by H. pylori lipopolysaccharide with somatostatin-receptor binding on gastric mucosal G-cells.

Reversal of gastric somatostatin receptor inhibition by Helicobacter pylori lipopolysaccharide with ebrotidine and sulglycotide

1. 1. Among the consequences of H. pylori infection is an increase in gastric acid secretion due to the impairment in feedback inhibition by somatostatin. Here, we show that lipopolysaccharide from H. pylori inhibits the binding of somatostatin to gastric mucosal receptor, and that antiulcer agents, ebrotidine and sulglycotide, are capable of countering this effect. 2. 2. The somatostatin receptor was prepared from the solubilized gastric mucosal epithelial cell membranes by affinity chromatography on Affi-Gel-bound [D-Tryp 8]SRIF-14 and used in the binding assays for 125I-labeled somatostatin in the presence of H. pylori lipopolysaccharide and antiulcer agents. 3. 3. The assays revealed a dose-dependent inhibition in the receptor-somatostatin binding by the lipopolysaccharide which reached a maximum of 94.1%. The effect of H. pylori lipopolysaccharide was countered by ebrotidine and sulglycotide, which at their optimal doses produced 94.9% and 84% restoration in somatostatin-receptor binding, respectively. 4. 4. The results demonstrate that the antiulcer agents, ebrotidine and sulglycotide, possess the ability to counteract the H. pylori interference with somatostatin regulatory effect on gastric acid secretion.

Helicobacter pylori and atrophic gastritis

Infection with Helicobacter pylori plays a crucial role in the etiology of atrophic gastritis and gastric cancer. Studies suggest a nine-fold increased risk for both conditions in the presence of infection. The risk of atrophic gastritis in the presence of infection is dependent upon the severity of the gastritis. Gastritis is increased in subjects infected with a cytotoxic H pylori strain and in those with a decreased acid production. The development of atrophy may be related to the induction of cross-reacting antibodies recognizing Lewis epitopes on H pylori lipopolysaccharide and gastric mucosa. Future studies have to demonstrate whether atrophic gastritis and gastric cancer can be prevented by early H pylori eradication.

Helicobacter pylori lipopolysaccharide can activate 70Z/3 cells via CD14.

Helicobacter pylori persistently colonizes the human gastrointestinal tract and is associated with chronic gastritis and, in some cases, peptic ulcer disease or gastric neoplasms. One factor in the persistence of this organism may be its inability to elicit a strong inflammatory response. Lipopolysaccharide (LPS) is a proinflammatory substance found in the cell walls of all gram-negative bacteria. H. pylori LPS has been found by several different measures to be less active than LPS from Enterobacteriaceae. This study addresses the role of CD14 and LPS-binding protein in the cellular response to H. pylori LPS. We report that H. pylori LPS activates mammalian cells expressing CD14 at much lower LPS concentrations than those for control cells not expressing CD14. The maximal activation of CD14-70Z/3 cells by H. pylori LPS also requires LPS-binding protein. H. pylori LPS at concentrations as high as 30 microg/ml does not elicit an interleukin-8 (IL-8) response from the epithelial cell line SW620 in the presence of CD14; 10 ng of Escherichia coli LPS per ml elicits a maximal IL-8 response. Furthermore, in contrast to some other types of LPS with little activity, H. pylori LPS does not inhibit the CD14-70Z/3 cell response to E. coli LPS. From these studies, we conclude that H. pylori LPS, though much less active than E. coli LPS, stimulates cells via CD14.