Toshiko Kumagai

Acquisition versus Loss of Helicobacter pylori Infection in Japan: Results from an 8-Year Birth Cohort Study

Studies of the pattern of change in the epidemiology of Helicobacter pylori infection are scarce. A longitudinal cohort study consisted of 644 children and adults, and two independent cross-sectional surveys were conducted in rural Japan between 1986 and 1994. The anti-H. pylori IgG seroconversion rates were 1.1% and 1% per year for children and adults, respectively. The seroreversion rate per year was 1.8% for children and 1.5% for adults. The cohort study was confirmed by the two cross-sectional studies. H. pylori prevalence fell in all age groups in both children (odds ratio [OR] = 0.5, 95% confidence interval [CI] = 0.2-1.0, P = .05) and adults (OR = 0.4, 95% CI = 0.3-0.6, P = .001). The rate of loss of H. pylori infection was greater than the acquisition. Data regarding acquisition and loss of H. pylori infection are critical to understanding the epidemiology of the infection and to developing treatment and vaccination strategies.

Changes in seroepidemiological pattern of Helicobacter pylori and hepatitis A virus over the last 20 years in Japan

OBJECTIVE:The age groups most susceptible to infection and the mode of transmission of Helicobacter pylori (H. pylori) are not yet clear. To contribute to a better understanding of this disease, this study was undertaken to evaluate changes in the seroepidemiological pattern of H. pylori in a group of Japanese people over the last 20 yr sampled in 1974, 1984, and 1994 in comparison with that of the hepatitis A virus (HAV), which was used as a marker of the fecal-oral route of transmission.METHODS:A total of 1015 serum samples were obtained from the National Institute of Infectious Diseases in Tokyo. All of these samples were from healthy persons aged 0–89 yr (442 male and 573 female; median age 35.6 yr), living in seven prefectures in the central part of Japan in 1974, 1984, and 1994. All serum samples were assayed for H. pylori IgG by means of enzyme-linked immunosorbent assay (ELISA). Further, anti-HAV antibodies were assayed by blocking ELISA in the same samples. We investigated the prevalence of H. pylori and HAV for all ages, and the positive rate of H. pylori for infants and children separately.RESULTS:The overall prevalence of H. pylori antibodies was 72.7% (CI 95%, 68.0–77.3) in 1974, 54.6% (CI 95%, 49.1–60.0) in 1984 and 39.3% (CI 95%, 34.1–44.4) in 1994. That of HAV was 57.7% (CI 95%, 52.5–62.8) in 1974, 41.7% (CI 95%, 36.3–47.0) in 1984, and 23.4% (CI 95%, 18.9–27.8) in 1994. The prevalence of both H. pylori and HAV was found to increase with age, whereas there have been clear cohort shifts in the seroepidemiological patterns of both infections over the last 20 yr in Japan. This study shows that there is a slight similarity in the concordance of positive and negative populations between H. pylori and HAV. However, it was very difficult to determine the concordance between H. pylori and HAV infection in this study.CONCLUSIONS:Our data strongly suggest that the highest infection rates for both H. pylori and HAV occur among infants and children in Japan. This study provides evidence that H. pylori and HAV may share a common mode of transmission but that changes in environmental conditions make this very difficult if not impossible to prove with seroepidemiological data.

Effect of early eradication on Helicobacter pylori-related gastric carcinogenesis in Mongolian gerbils

Helicobacter pylori (Hp) infection and gastric carcinogenesis are known to have a close relationship, but the effect of eradication of Hp on Hp‐related gastric carcinogenesis has not been fully studied experimentally. To evaluate the effect of eradication in gastric carcinogenesis, an experimental model with eradication in the early, middle or late period was studied using Hp‐infected and N‐methyl‐N‐nitrosourea (MNU)‐treated Mongolian gerbils. The animals were divided into seven groups: group A (MNU+Hp+ eradication at 15 w), group B (MNU+Hp+eradication at 35 w), group C (MNU+Hp+eradication at 55 w), group D (MNU+Hp), group E (MNU), group F (Hp) and group G (control). The tumor incidences at week 75 in the early (group A), middle (group B) and late (group C) eradicated groups were 6.7%, 27.3% and 38.2%, respectively. The incidence of 56.3% in the non‐eradicated group was the highest (group D). Incidences in group E, group F and group G were 6.3%, 0.0% and 0.0%, respectively. The tumor incidences were related to the period of inflammatory status induced by Hp infection. Hp infection strongly enhanced gastric carcinogenesis initiated with a chemical carcinogen, and following eradication at an early period this enhancing effect was effectively reduced. Eradication at an early stage of inflammation might be effective in preventing Hp‐related gastric carcinogenesis. (Cancer Sci 2003; 94: 235–239)

High salt diets dose-dependently promote gastric chemical carcinogenesis in Helicobacter pylori-infected Mongolian gerbils associated with a shift in mucin production from glandular to surface mucous cells.

Intake of salt and salty food is known as a risk factor for gastric carcinogenesis. To examine the dose‐dependence and the mechanisms underlying enhancing effects, Mongolian gerbils were treated with N‐methyl‐N‐nitrosourea (MNU), Helicobacter pylori and food containing various concentrations of salt, and were sacrificed after 50 weeks. Among gerbils treated with MNU and H. pylori, the incidences of glandular stomach cancers were 15% in the normal diet group and 33%, 36% and 63% in the 2.5%, 5% and 10% NaCl diet groups, showing dose‐dependent increase (p < 0.01). Intermittent intragastric injection of saturated NaCl solution, in contrast, did not promote gastric carcinogenesis. In gerbils infected with H. pylori, a high salt diet was associated with elevation of anti‐H. pylori antibody titers, serum gastrin levels and inflammatory cell infiltration in a dose‐dependent fashion. Ten percent NaCl diet upregulated the amount of surface mucous cell mucin (p < 0.05), suitable for H. pylori colonization, despite no increment of MUC5AC mRNA, while H. pylori infection itself had an opposing effect, stimulating transcription of MUC6 and increasing the amount of gland mucous cell mucin (GMCM). High salt diet, in turn, decreased the amount of GMCM, which acts against H. pylori infection. In conclusion, the present study demonstrated dose‐dependent enhancing effects of salt in gastric chemical carcinogenesis in H. pylori‐infected Mongolian gerbils associated with alteration of the mucous microenvironment. Reduction of salt intake could thus be one of the most important chemopreventive methods for human gastric carcinogenesis.

Anti‐inflammatory effects of caffeic acid phenethyl ester (CAPE), a nuclear factor‐κB inhibitor, on Helicobacter pylori‐induced gastritis in Mongolian gerbils

Nuclear factor‐κB (NF‐κB) plays a major role in host inflammatory responses and carcinogenesis and as such is an important drug target for adjuvant therapy. In this study, we examined the effect of caffeic acid phenethyl ester (CAPE), an NF‐κB inhibitor, on Helicobacter pylori (H. pylori)‐induced NF‐κB activation in cell culture and chronic gastritis in Mongolian gerbils. In AGS gastric cancer cells, CAPE significantly inhibited H. pylori‐stimulated NF‐κB activation and mRNA expression of several inflammatory factors in a dose‐dependent manner, and prevented degradation of IκB‐α and phosphorylation of p65 subunit. To evaluate the effects of CAPE on H. pylori‐induced gastritis, specific pathogen‐free male, 6‐week‐old Mongolian gerbils were intragastrically inoculated with H. pylori, fed diets containing CAPE (0–0.1%) and sacrificed after 12 weeks. Infiltration of neutrophils and mononuclear cells and expression of NF‐κB p50 subunit and phospho‐IκB‐α were significantly suppressed by 0.1% CAPE treatment in the antrum of H. pylori‐infected gerbils. Labeling indices for 5′‐bromo‐2′‐deoxyuridine both in the antrum and corpus and lengths of isolated pyloric glands were also markedly reduced at the highest dose, suggesting a preventive effect of CAPE on epithelial proliferation. Furthermore, in the pyloric mucosa, mRNA expression of inflammatory mediators including tumor necrosis factor‐α, interferon‐γ, interleukin (IL)‐2, IL‐6, KC (IL‐8 homologue), and inducible nitric oxide synthase was significantly reduced. These results suggest that CAPE has inhibitory effects on H. pylori‐induced gastritis in Mongolian gerbils through the suppression of NF‐κB activation, and may thus have potential for prevention and therapy of H. pylori‐associated gastric disorders.

Clinical Usefulness of Urine‐based Enzyme‐linked Immunosorbent Assay for Detection of Antibody to Helicobacter pylori: A Collaborative Study in Nine Medical Institutions in Japan

Background. A urine‐based enzyme‐linked immunosorbent assay (ELISA) kit for detection of antibody to Helicobacter pylori has been developed in Japan. Urine samples can be obtained noninvasively and are easier and safer to handle than are serum samples. The aim of this study was to examine the clinical usefulness of this urine‐based ELISA kit.

Earlier Helicobacter pylori infection increases the risk for the N-methyl-N-nitrosourea-induced stomach carcinogenesis in Mongolian gerbils

Helicobacter pylori (H. pylori) is now well known to be associated with stomach cancer, with infection during childhood rather than as an adult considered to be more important for carcinogenesis. To evaluate the difference in susceptibility to stomach carcinogenesis in relation to age of acquisition of H. pylori infection, we designed an experiment involving inoculation of H. pylori ATCC43504 followed by N‐methyl‐N‐nitrosourea (MNU) treatment at different ages. Four‐week‐ old male Mongolian gerbils (MGs) were divided into twelve groups. H. pylori was inoculated at 4, 18 and 32 weeks of age, as representatives of early, middle and late infection, respectively. Two weeks later, the animals were treated with MNU. Groups without H. pylori and/or MNU were included as controls. The incidences of adenocarcinomas at 52 weeks after the inoculation in the early (H. pylori+MNU), middle (H. pylori+MNU), and late (H. pylori+MNU) group were 60% (12/ 20), 18.4% (2/11), and 10% (2/20), respectively. The corresponding figures were 14.8% (4/27), 0% (0/11), and 0% (0/21) in the MNU‐alone groups. A higher titer of serum IgG for H. pylori and higher gastrin level were seen in the early‐infected compared to the middle and the late groups (P<0.01). The results clearly demonstrated that early acquisition of H. pylori significantly increases gastric chemical carcinogenesis with MNU, as compared to the case with later infection, possibly because of differences in host gastric mucosal factors and immunologic responses.

Eradication of Helicobacter pylori induces apoptosis and inhibits proliferation of heterotopic proliferative glands in infected Mongolian gerbils

Mongolian gerbils infected with Helicobacter pylori (H. pylori) develop heterotopic proliferative glands (HPGs) in the glandular stomach submucosa. To investigate the effects of H. pylori eradication on cell turnover in HPGs, three antibiotics, lansoprazole, amoxicillin and clarithromycin, were administered at 50 or 75 weeks after inoculation of H. pylori, and the stomachs were excised for histological examination at 1, 2, 4, 8 or 25 weeks thereafter. The HPGs were classified into gastric type (G‐type) and others (Gl+I‐type), which included both pure intestinal (I‐type) and gastric‐and‐intestinal mixed type (Gl‐type). Apoptosis and cell proliferation were evaluated by means of TUNEL assay and BrdU labeling, respectively. At 8 weeks post‐eradication, apoptotic indices were significantly increased in the eradication group (G‐type: 2.5%; Gl+I‐type: 7.2%) compared to the non‐eradication group (G‐type: 0.6%; Gl+I‐type: 2.1%: P<0.01), while BrdU labeling indices were significantly decreased (G‐type: 1.9%; Gl+I‐type: 6.8% as compared with 4.3% and 13.2%, respectively, P<0.01 for both). At 25 weeks, the apoptotic indices were similarly higher [G‐type: 0.4 (eradication group) vs. 0.2% (non‐eradication group); Gl+I‐type: 5.8 vs. 1.1%, both P<0.01], and the BrdU labeling indices (G‐type: 0.8 vs. 2.2%, P<0.01; Gl+I‐type: 5.1 vs. 11%, P<0.05) continued to be lower in HPGs. Furthermore, there were highly significant reductions in the areas of HPGs at 8 and 25 weeks post‐eradication. These findings demonstrated that eradication results in apoptosis and reduction of proliferation of HPGs in H. pylori‐infected gerbils, these lesions thus being apparently reversible through regulation of cell kinetics.

Serum immunoglobulin G immune response to Helicobacter pylori antigens in Mongolian gerbils.

ABSTRACT The Mongolian gerbil model for Helicobacter pyloriinfection is an animal model that mimics human disease. We examined the serum immune response to H. pylori infection in gerbils by enzyme-linked immunosorbent assay (ELISA) and Western blotting, both with whole-cell (H. pylori) extracts. A total of 66 7-week-old specific-pathogen-free male gerbils were inoculated orogastrically with H. pylori strain ATCC 43504. Sera were collected 1, 2, 4, 8, 12, 26, 38, and 52 weeks after H. pylori inoculation. Sixty-nine noninfected gerbils and their sera were used as controls. The specificity of the ELISA was 95.7%. The frequency of seropositivity increased over time: 2 of 10 (20%), 7 of 10 (70%), and 7 of 7 (100%) samples of sera from inoculated gerbils were positive for H. pylori at 2, 4, and 8 weeks postinoculation, respectively. Western blot assays showed that the primary immunoglobulin G (IgG) response against low-molecular-mass (25-, 30-, and 20-kDa) proteins appeared after a lag period of 2 to 8 weeks after inoculation. Antibodies against 160-, 150-, 110-, 120-, 80-, 66-, and 63-kDa proteins were observed 12 weeks after inoculation. The early reactive 30-kDa protein was identified as a urease α subunit by N-terminal amino acid sequencing. After 26 weeks, two groups of animals could be distinguished: one group developed ulcers (n = 5), and the other developed hyperplastic polyps without ulcers (n = 19). Gerbils in the gastric ulcer group showed significantly higher serum anti-H. pylori IgG levels than did gerbils in the hyperplastic group (P = 0.001) as measured by ELISA. Furthermore, a higher proportion of animals developed antibodies to H. pylori proteins of 26, 25, and 20 kDa in the ulcer group than those animals with hyperplastic polyps (75 to 100% versus 17 to 50%) in Western blot assays. These results highlight the importance of the immune response of the host in the development of H. pylori-related gastric lesions.

Inhibitory effect of nordihydroguaiaretic acid, a plant lignan, on Helicobacter pylori‐associated gastric carcinogenesis in Mongolian gerbils

Recent epidemiological studies have demonstrated that consumption of certain natural products can lower cancer risk in humans. For example, plant‐derived lignans have been shown to exert chemopreventive effects against cancer in vitro and in vivo. In the present study, the effects of three such lignans, termed arctiin, arctigenin, and nordihydroguaiaretic acid (NDGA), on the proliferation of Helicobacter pylori and the prevention of H. pylori‐associated gastric cancer were investigated in Mongolian gerbils. To examine the effects of arctigenin and NDGA on stomach carcinogenesis, specific pathogen‐free male, 5‐week‐old gerbils were infected with H. pylori, administered 10 p.p.m. N‐methyl‐N‐nitrosourea in their drinking water and fed diets containing various concentrations of lignans until they were killed after 52 weeks. At a dietary level of 0.25%, NDGA significantly decreased the incidence of gastric adenocarcinomas. Arctigenin, in contrast, failed to attenuate neoplasia at a level of 0.1%. Both NDGA and arctigenin significantly reduced serum 8‐hydroxy‐2′‐deoxyguanosine levels at doses of 0.25 and 0.05% (NDGA), and 0.1% (arctigenin). Administration of 0.25% NDGA significantly suppressed the formation of intestinal metaplasia both in the antrum and the corpus. Although all three lignans dose‐dependently inhibited the in vitro proliferation of H. pylori, there were no differences in the titers of anti‐H. pylori antibodies or the amount of the H. pylori‐specific urease A gene among all H. pylori‐infected groups. These results suggest that NDGA might be effective for prevention of gastric carcinogenesis. The possible mechanisms appear to be related to inhibitory effects on progression of gastritis and antioxidative activity rather than direct antimicrobial influence. (Cancer Sci 2007; 98: 1689–1695)