Shigeru Kamiya

Prevention of Helicobacter pylori infection by lactobacilli in a gnotobiotic murine model.

BACKGROUND: Helicobacter pylori is a bacterium which causes gastric inflammatory diseases. Oral inoculation of H pylori usually results in only a temporary colonisation without a successful infection in the stomach of conventional mice in which lactobacilli are the predominant indigenous bacteria. AIM: To determine whether lactobacilli exert an inhibitory effect on colonisation by H pylori in the stomach. METHODS: The effects of H pylori on attachment to murine and human gastric epithelial cells and the H pylori mediated release of interleukin-8 (IL-8) by these cells were examined in vitro. Lactobacillus salivarius infected gnotobiotic BALB/c mice and control germ free mice were inoculated orally with H pylori to examine whether L salivarius can inhibit colonisation by H pylori. RESULTS: L salivarius inhibited both the attachment and IL-8 release in vitro. H pylori could not colonise the stomach of L salivarius infected gnotobiotic BALB/c mice, but colonised in large numbers and subsequently caused active gastritis in germ free mice. In addition, L salivarius given after H pylori implantation could eliminate colonisation by H pylori. CONCLUSION: These findings suggest the possibility of lactobacilli being used as probiotic agents against H pylori.

Heat-shock protein 60 homologue of Helicobacter pylori is associated with adhesion of H. pylori to human gastric epithelial cells.

A previous study reported a relationship between the expression of heat-shock protein 60 (HSP60) by Helicobacter pylori and its adhesion to human gastric carcinoma (MKN45) cells. To examine whether the HSP60 homologue of H. pylori is associated with the adhesion of H. pylori to human gastric epithelial cells, an inhibition assay of adhesion of H. pylori to MKN45 cells was performed by flow cytometric analysis with monoclonal antibody (MAb) designated as H20 recognising HSP60 of H. pylori. The rate of adhesion of H. pylori pretreated with MAbH20 to MKN45 cells was lower than that of untreated H. pylori. Primary human gastric epithelial cells from a patient with gastric cancer were also prepared for comparison in the inhibition assay with MAbH20. H. pylori adhered to the primary human gastric epithelial cells, and this adhesion was significantly inhibited by MAbH20. These results suggest that the H. pylori HSP60 homologue recognised by MAbH20 might be associated with the adhesion of H. pylori to primary human gastric epithelial cells as well as to cultured gastric cancer cells.

Establishment and characterisation of a monoclonal antibody to inhibit adhesion of Helicobacter pylori to gastric epithelial cells

Monoclonal antibodies (MAbs) that inhibit adhesion of Helicobacter pylori to human gastric cancer (MKN45) cells were established to clarify the mechanism of adhesion of H. pylori. Of 53 hybridoma clones screened by the primary inhibition assay for adhesion, MAb A20 of IgM class was selected on the basis of both its reactivity to whole cells of H. pylori by ELISA and its inhibitory effect on adhesion of H. pylori. The adhesion of H. pylori strain TK1029 to MKN45 cells was inhibited by MAb A20, depending on the concentration of the MAb. The MAb recognised the surface antigen, lipopolysaccharide (LPS) of H. pylori, suggesting that LPS is associated with adhesion of H. pylori to human gastric epithelial cells.

A virulence factor of Helicobacter pylori : Role of heat shock protein in mucosal inflammation after H. pylori infection

Among the various virulence factors of Helicobacter pylori the role of its heat shock protein 60 (HSP60, HspB) in mucosal inflammation after H. pylori infection was examined. In flow cytometric analysis, the expression of HSP60 on the cell surface was different, depending on the H. pylori strain used. The HSP60 epitope was also detected on the surface of both human gastric cancer cells (MKN45, KATOIII, and MKN28) and human gastric biopsy specimens. The intensity of the expression of HSP60 on the cell surface correlated significantly with the adhesion of H. pylori to MKN45 cells, but not with urease activity and production of vacuolating cytotoxin. A monoclonal antibody to H. pylori HSP60 inhibited the adhesion of H. pylori to MKN45 cells. These results suggest that HSP60 of H. pylori might act as an important virulence factor after H. pylori infection.

Flagellin Gene Diversity among Helicobacter pylori Strains and IL-8 Secretion from Gastric Epithelial Cells

BACKGROUND To clarify the pathological functions of the virulence factors of Helicobacter pylori, a comparative analysis was carried out on the relationship between motility, flagellar gene polymorphism, vacuolating cytotoxin (VT) production and interleukin-8 (IL-8) induction. METHODS Twenty-five strains were examined for restriction fragment length polymorphism (RFLP) of the flagellin gene. Motility was measured using semisolid agar plates. Cytotoxicity was assayed using RK-13 cells. IL-8 secretion was assessed by the enzyme-linked immunosorbent assay (ELISA) methods. RESULTS H. pylori was classified into four groups according to their flagellar RFLP. No differences were noted in motility or VT production among the four groups, but a significant difference was noted in IL-8 induction. In addition, highly motile strains produced more IL-8. CONCLUSION This flagellar genetic polymorphism may be associated with IL-8 induction.

Growth Inhibition of Helicobacter pylori by Monoclonal Antibody to Heat-Shock Protein 60

The H20mAb recognizing the 60‐kilodalton protein, which existed in the outer membrane and was induced by heat shock at 42 C, was established. The molecule recognized with the mAb was a heat‐shock protein 60 (HSP60) of Helicobacter pylori. To understand the role of HSP60 on the cell surface of H. pylori, whether or not H20mAb affects the growth of H. pylori was investigated. When bacteria were cultured with H20mAb, growth was markedly inhibited after 24 hr, although an initial 5 hr‐incubation with the mAb induced no significant inhibition of H. pylori growth. The 24‐ and 48 hr growth of the bacteria after washing to remove the mAb at 5 hr was also inhibited though the inhibitory effect was not strong. In electron microscopical analysis, the spots with high electron density in the cytoplasm of the bacteria treated with H20mAb were increased, depending on the length of incubation time from 5 to 24 hr. After 24 hr treatment with H20mAb, bacterial destruction was also observed, indicating bactericidal activity by H20mAb. These results suggest that the HSP60 on the cell surface of H. pylori might have an essential role in the growth of the bacteria.

Cytotoxicity and motility of Helicobacter pylori

To clarify the relationship between interleukin-8 (IL-8) production and virulent factors, we examined the motility and cytotoxicity of H. pylori, suggested to be a major cause of chronic gastritis and peptic ulcers. Our results demonstrated that among cytotoxic strains of H. pylori, high-motility strains induced more IL-8 than low-motility strains. There was no correlation between cytotoxicity and motility of H. pylori. Four restriction fragment length polymorphism (RFLP) patterns were observed in the flaA PCR products. There was no correlation between flaA RFLP and motility. In conclusion, our findings suggest that both cytotoxicity and motility are virulent factors in the pathogenesis of gastric mucosal injury.

Effect of sofalcone on adherence, production of vacuolating toxin, and induction of interleukin-8 secretion by Helicobacter pylori.

We examined the effect of sofalcone, a mucosal protective agent that has been reported to inhibit growth of Helicobacter pylori, on adherence, production of vacuolating toxin (VT), and induction of interleukin-8 (IL-8) secretion by H. pylori. Mixing VT with various concentrations (1.5-100 micrograms/ml) of sofalcone resulted in a 50% decrease in the VT titer. When toxigenic H. pylori strains were incubated in the presence of sofalcone (20 and 40 micrograms/ml), although bacterial growth was not inhibited significantly there was significant inhibition of VT production. Notable inhibition of IL-8 secretion by human gastric cancer cells (MKN 45) was detected in the presence of sofalcone (20-100 micrograms/ml) after co-incubation with H. pylori strains. In flow cytometric analysis, adherence of H. pylori strains to MKN 45 cells was significantly inhibited by treatment with sofalcone (20-60 micrograms/ml), indicating at least one reason for the inhibition of IL-8 secretion. These results show that sofalcone is an effective mucosal protective agent that inhibits both production of VT and induction of IL-8 secretion.

Heat shock protein 60 (HSP60) immunoreactivity in gastric epithelium associated with Helicobacter pylori infection: a pitfall in immunohistochemically interpreting HSP60-mediated autoimmune responses.

Previous studies have suggested that heat shock proteins (HSP) of Helicobacter pylori (H. pylori) are involved in the induction of autoimmunity mediated gastritis. In the present report, the cross‐reactivity between H. pylori‐related HSP60 and gastric epithelial cells was investigated by the indirect immunoperoxidase method using two monoclonal antibodies (mAb) against H. pylori‐derived HSP60, H9 and H20. H9 is reactive with an epitope common to bacterial HSP60, while H20 is specific to H. pylori HSP60. A total of 70 paraffin‐embedded gastric biopsy specimens were analyzed after heat‐induced epitope retrieval. Both mAb were cross‐reactive with the gastric epithelial cells, with a higher frequency seen for the H9‐reactive epitope. The frequency of positive epithelial decoration was not significantly different between H. pylori‐positive and H. pylori‐negative gastric mucosae. A variety of epithelial and non‐epithelial cells were immunostained with mAb H9, while mAb H20 was cross‐reactive only with small intestinal epithelia. Reactivity was mainly located in the Golgi area and rarely in the cytoplasm. These results suggest a noteworthy pitfall in immunohistochemical interpretations of HSP60‐associated autoimmune reactions in the gastric mucosa.