Interactions between Helicobacter pylori and the local mucosal immune system

Effect of moxibustion pretreatment on serum levels of Helicobacter pylori IgG and eHSP72 in rats with Helicobacter pylori-induced gastritis

AIM: To investigate the effect of moxibustion pretreatment on serum levels of Helicobacter pylori (H. pylori) IgG and extracellular heat shock protein 72 (eHSP72) in rats with H. pylori-induced gastritis.

METHODS: Fifty healthy rats were randomly divided into five groups: A (normal controls), B (infected with H. pylori), C (moxibustion at acupoints), D (moxibustion at non-acupoints), and E (electroacupuncture at acupoints). Gastritis was induced in rats by oral gavage with H. pylori. The levels of serum H. pylori IgG and eHSP72 were measured by enzyme-linked immunosorbent assay.

RESULTS: Compared to group A, the ulcer index and serum levels of H. pylori IgG and eHSP72 significantly increased in group B (0.50 ± 1.00 vs 6.50 ± 4.75, 76.72 μg/L ± 11.02 μg/L vs 131.91 μg/L ± 30.04 μg/L, 152.2 ng/L ± 22.72 ng/L vs

222.59 ng/L ± 56.69 ng/L, all P < 0.01). Compared to group B, the UI and serum levels of H. pylori IgG significantly decreased (6.50 ± 4.75 vs 1.00 ± 2.00, 131.91 μg/L ± 30.04 μg/L vs 86.25 μg/L ± 18.63 μg/L, both P < 0.01) and serum levels of eHSP72 significantly increased in group C (222.59 ng/L ± 56.69 ng/L vs 285.54 ng/L ± 68.23 ng/L, P < 0.05). Compared to group D, the UI and serum levels of H. pylori IgG significantly decreased (3.00 ± 5.00 vs 1.00 ± 2.00, 116.19 μg/L ± 31.25 μg/L vs 86.25 μg/L ± 18.63 μg/L, both P < 0.01) and serum levels of eHSP72 significantly increased in group C (185.97 ng/L ± 77.62 ng/L vs 285.54 ng/L ± 68.23 ng/L, P < 0.01). Compared to group E, serum levels of H. pylori IgG significantly decreased in group C (120.25 μg/L ± 25.40 μg/L vs 86.25 μg/L ± 18.63 μg/L, P < 0.01).

CONCLUSION: Moxibustion at acupoints reduces H. pylori-induced gastric mucosal injury possibly via mechanisms associated with increasing serum levels of eHSP72.

Helicobacter pylori infection of human gastric epithelial cells induces IL-8 and TNFalpha, but not TGFbeta1 mRNA

Helicobacter pylori (Hp) infection causes gastric ulcers and gastric carcinomas. The mechanisms of these diseases are not known but Hp induction of cytokines is believed to be involved. However, the profile as well as the involvement of cytokines induced by Hp infection is less clear. In the present study, steady state levels of interleukin-8 (IL-8), tumor necrosis factor-alpha (TNFalpha) and TGFbeta1 mRNA of human gastric epithelial cell lines Kato III, AGS and NCI-87N in response to Hp infection were investigated. The cell cultures were infected with Hp for up to 18 h. Total RNA was extracted and analyzed by reverse transcription-PCR. The three cell lines tested expressed low constitutive levels of mRNA for IL-8 and TNFalpha. The mRNA levels of IL-8 quickly increased within 2 h in all three cells tested and reached a peak at 4 h following infection with Hp. In contrast, the levels of TNFalpha after Hp infection increased in only Kato III cells. The other cells, AGS and NCI-87N, responded with minimum increases after Hp infection. The TGFbeta1 mRNA was constitutively expressed in both AGS and NCI-87N cells, but Kato III cells expressed only low levels prior to infection. The Hp infection did not increase the levels of TGFbeta1 mRNA as well as TGFbeta1 secretion in all cells tested. These results indicate that the cytokine response to Hp infection differs according to the cells studied and the response may be linked somewhat to TGF levels of gastric cells.

An epizootic of lymphoplasmacytic gastritis attributed to Helicobacter pylori infection in cynomolgus monkeys (Macaca fascicularis)

An epizootic of subclinical lymphoplasmacytic gastritis occurred in cynomolgus monkeys maintained at our research facility. Gastric pathology data and histologic sections of 63 adolescent monkeys (2.5-3.5 years old) sacrificed during the epizootic were reviewed. Localized to multifocal reddening of the gastric mucosa was noted grossly in 7 of 44 (16%) monkeys harboring Helicobacter pylori, but not in any of 19 monkeys in which these bacteria were not seen. Gastritis, characterized by accentuation of lymphoplasmacytic infiltrates in antral and to a lesser degree cardiac mucosa, occurred in 42 of 63 (67%) monkeys evaluated and in 42 of 44 (93%) monkeys in which H. pylori was observed microscopically. Two monkeys with H. pylori infection had infiltrate scores that overlapped with the upper limit of scores of H. pylori-negative animals. Coincident with accentuated infiltrates were gastric gland epithelial hyperplasia, reduction in mucin content of surface and gland epithelia, and comparatively minor infiltrates of neutrophils in superficial lamina propria and gastric glands. Antral mucosa thickness often exceeded 1.5 to 2 times normal. Antral mucosal erosions occurred in 7 of 44 (16%) monkeys with H. pylori. Argyrophilic bacteria morphologically consistent with H. pylori were present in antral and less commonly cardiac mucosal glands. Intensity of bacterial colonization correlated with lymphoplasmacytic infiltrates (r = 0.754) and hyperplasia (r = 0.700), although responses were quite variable. These bacteria were not detected in fundic mucosa except in instances where parietal cells were substantially depleted in glands coincident with localized increases in lamina propria inflammatory cell infiltrates. Helicobacter heilmannii-like organisms (HHLOs) were present in fundic glands of all 63 monkeys; colonization was often pronounced. Scores for fundic mucosal inflammation did not correlate with presence or intensity of colonization with HHLOs (r = 0.005). Rather, fundic inflammation scores positively correlated with the antral inflammation scores (r = 0.548). Bacteria morphologically, biochemically, and genetically consistent with H. pylori were cultured from gastric mucosal specimens confirming bacterial identification. These findings demonstrate that adolescent cynomolgus monkeys are susceptible to natural infection with H. pylori and develop many morphologic hallmarks of H. pylori-related gastritis in humans.

Helicobacter pylori disrupts epithelial barrier function in a process inhibited by protein kinase C activators

Helicobacter pylori colonizes the gastric mucosa, and the infection is related to the development of diverse gastric pathologies, possibly by directly or indirectly affecting epithelial-cell function. We analyzed the influence of the bacteria on transepithelial electrical resistance (TER) on a model tight epithelium, T84, grown to confluence in permeable filters. H. pylori sonicates produced a dramatic decrease in TER after 1 to 2 h of exposure, while sonicates from other bacteria did not induce a significant reduction of TER. The effect induced by sonicates was mimicked by a water-soluble fraction from the bacterial surface, was not reproducible with isolated lipopolysaccharide, and was concomitant with a significant increase in the paracellular permeability of the marker molecule [14C]mannitol. Furthermore, H. pylori sonicates also provoked a significant increase in permeability to [14C]mannitol across rat gastric mucosa in vitro. The sonicate-induced decrease in TER in T84 monolayers was inhibited by the protein kinase C (PKC) activator phorbol myristate acetate. As PKC is directly involved in tight junction regulation, we suggest that H. pylori may induce intracellular signalling events counteracting PKC effects. Following long-term H. pylori stimulation, epithelial monolayers regained baseline resistance values slowly after 24 h. The resistance recovery process was inhibited by cycloheximide, indicating its dependency upon protein synthesis. No association between resistance variation and E-cadherin protein levels was observed. These results indicate that H. pylori alters in vitro the barrier properties of the epithelium, probably by generating cell signalling events counteracting the normal function of PKC. This increased permeability may provide a potential mechanism by which H. pylori antigens can reach the gastric lamina propria, thereby activating the mucosal immune system.

Helicobacter pylori induces an array of pro-inflammatory cytokines in human gastric epithelial cells: quantification of mRNA for interleukin-8, -1 alpha/beta, granulocyte-macrophage colony-stimulating factor, monocyte chemoattractant protein-1 and tumour necrosis factor-alpha

Despite the fact that Helicobacter pylori is known to be non-invasive, mucosal infiltration of inflammatory cells have been observed in the gastric mucosa. The exact pathogenesis of such an inflammatory reaction has not been well defined. We explored the repertoire of cytokine genes expressed in human gastric epithelial cells in response to coculture with H. pylori. After gastric epithelial cells, SNU-5 and KATO III, were infected with H. pylori, expression of several cytokine genes was assessed using quantitative reverse transcription polymerase chain reaction. Interleukin (IL)-8, -1 alpha and -1 beta mRNA were expressed in both gastric epithelial cells throughout the entire infection period. In SNU-5, IL-1 alpha and IL-8 mRNA were expressed at 1 h, reached a peak level at 4 h and then decreased. Interleukin-1 beta mRNA was expressed less frequently than IL-1 alpha, or IL-8 mRNA. In SNU-5 cells, granulocyte-macrophage colony-stimulating factor (GM-CSF), monocyte chemoattractant protein-1 (MCP-1), and tumour necrosis factor-alpha (TNF-alpha) mRNA were expressed at 9 h, but was not expressed in KATO III. Gene expression paralleled the amount of IL-8 protein measured by enzyme-linked immunoabsorbent assay (ELISA). Interleukin-8 mRNA expression was not observed in KATO III cells infected with Campylobacter fetus ssp. fetus, Campylobacter jejuni or Escherichia coli. IL-8 mRNA expression was increased not only in gastric epithelial cells but also in non-gastric cells infected with H. pylori. These results suggest that an inflammatory reaction induced by H. pylori may be initially triggered by an array of pro-inflammatory cytokines expressed by infected gastric epithelial cells.

Increased motility of Helicobacter pylori by methylcellulose could upregulate the expression of proinflammatory cytokines in human gastric epithelial cells

The inflammatory reaction in the human gastric mucosa to Helicobacter pylori could be initially triggered by an array of cytokines expressed in infected gastric epithelial cells. The spiral morphology and flagella of these organisms could increase their velocity in a viscous environment such as methylcellulose solution. The goal of this study was to determine whether modification of H. pylori motility could influence the expression of cytokine genes from gastric epithelial cells infected with H. pylori. Adherent human gastric epithelial cells were cultured and overlaid with methylcellulose solutions of varying viscosity. These epithelial cell layers covered with methylcellulose solution were inoculated with H. pylori. RNAs were then extracted from the gastric epithelial cells. Various cytokine gene expressions were assessed and quantified by reverse transcription-polymerase chain reaction (RT-PCR) and standard synthetic RNA. Cytokine proteins were also measured by enzyme-linked immunosorbent assay (ELISA). Expression of mRNA for interleukin(IL)-8 was upregulated in H. pylori-infected gastric epithelial cells overlaid with methylcellulose of 15 centipoise (cp) viscosity. The expression of mRNA for IL-1 alpha, IL-8, monocyte chemotactic protein (MCP)-1 and granulocyte macrophage colony-stimulating factor (GM-CSF) was also upregulated in H. pylori-infected gastric epithelial cells overlaid with methylcellulose solution of the same viscosity. The number of molecules of the expressed cytokine transcripts also paralleled the amounts of protein secreted from gastric epithelial cells infected with H. pylori. These results suggest that methylcellulose solution (simulating the mucus layer in vivo) could increase contact of H. pylori with gastric epithelial cells by increasing its motility. This could result in the upregulation of mRNA for proinflammatory cytokines in gastric epithelial cells, therefore enhancing inflammatory reaction at H. pylori-infected sites.

Expression of interleukin 8 and CD54 by human gastric epithelium after Helicobacter pylori infection in vitro

BACKGROUND/AIMS

Helicobacter pylori is associated with neutrophil infiltrates, although the mechanism of their recruitment is only partially defined. The aim of the study was to determine if Kato III, a human gastric epithelial cell line, expressed cytokines and the intercellular adhesion molecule 1 (ICAM-1), which could contribute to the initiation of inflammation during infection with H. pylori.

METHODS

Kato III cells were stimulated with H. pylori and were examined for evidence of infection, cytokine production, and the expression of ICAM-1.

RESULTS

The expression of interleukin 8 messenger RNA and immunoreactive protein by Kato III cells was significantly increased over constitutive levels within 3 hours of infection with H. pylori. Infected Kato III supernatants activated neutrophils as evidenced by increased CD11b/CD18 and decreased L-selectin that could be blocked by anti-interleukin 8. In contrast, Campylobacter jejuni, lipopolysaccharide, killed H. pylori, and supernatants from cultures of H. pylori did not increase interleukin 8. Interleukins 2 and 6; interferons alfa, beta, and gamma; and tumor necrosis factor were not produced by resting or H. pylori-stimulated Kato III cells. In addition to producing interleukin 8, Kato III constitutively expressed surface ICAM-1, which acts as an intercellular adhesion molecule for neutrophils.

CONCLUSIONS

Our results indicate that H. pylori stimulates the gastric epithelium to initiate inflammation and neutrophil recruitment and activation.

Natural gastric infection with Helicobacter pylori in monkeys: a model for spiral bacteria infection in humans

BACKGROUND/AIMS

There is no generally accepted model for Helicobacter pylori infection in humans. The aim of this study was to examine the natural history and effect of treatment in rhesus monkeys and sequentially define the immune response to H. pylori in relation to treatment.

METHODS

Infection and gastritis were graded blindly by histological analysis and culture of biopsy specimens harvested during gastroduodenoscopies in 26 anesthetized colony-bred monkeys. Plasma H. pylori-specific immunoglobulin (Ig) G levels were determined by enzyme-linked immunosorbent assay.

RESULTS

H. pylori and Gastrospirilum hominis-like organisms were present in 13 and 9 monkeys, respectively; 3 animals harbored both organisms, whereas 4 monkeys were not infected. Gastritis score was < or = 1.5 in animals uninfected or infected only with G. hominis-like organisms and > or = 2.0 in all H. pylori-infected animals. IgG ratios were > or = 0.5 in 12 of 13 H. pylori-infected animals and in 2 of 13 H. pylori-negative animals (P < 0.001). One monkey became infected with H. pylori during the observation period, with concurrent increase of gastritis and plasma IgG levels. In untreated animals, infection, gastritis, and plasma IgG levels remained unchanged over 7-15 months. Triple therapy eradicated H. pylori at 6 months in 4 of 6 animals while suppressing gastritis and plasma IgG levels.

CONCLUSIONS

Rhesus monkeys harboring H. pylori are persistently infected and have gastritis and elevated specific IgG levels, all of which may respond to appropriate therapy, whereas G. hominis infection is associated with little inflammation.