Helicobacter pylori is the major causative agent of chronic antral gastritis and is thought to be involved in the pathogenesis of mucosa-associated lymphoid tissue lymphoma (MALToma) developing in the human stomach. The aim of this study was to clarify whether corporal autoimmune gastritis (AIG), which is known to decrease acidity due to destruction of parietal cells, predisposes mice to H. pylori infection, thereby leading to MALToma-like pathology. BALB/c mice in which AIG had been induced by thymectomy 3 days after birth (AIG mice) were used. The AIG mice were orally administered mouse-adapted H. pylori at the age of 6 weeks and were examined histologically and serologically after 2 to 12 months. The results were compared with those obtained from uninfected AIG mice and infected normal mice. Germinal centers were induced in the corpus in 57% of the H. pylori-infected AIG mice, which elicited anti-H. pylori antibody responses in association with upregulation of interleukin-4 (IL-4) mRNA. In these mice, parietal cells remained in the corpus mucosa. These findings were in contrast to those with the uninfected AIG mice: fundic gland atrophy due to disappearance of parietal cells associated with upregulation of gamma interferon, but not IL-4, mRNA and no germinal center formation in the corpus. These observations suggest that AIG alters the infectivity of H. pylori, leading to MALToma-like follicular gastritis, at an early stage after H. pylori infection.

The aim of the present study was to comparatively evaluate DNA damage and cellular death in cells exposed to various commercially available mouthrinses: Listerine Cepacol, Plax alcohol free, Periogard, and Plax Whitening. A total of 75 volunteers were included in the search distributed into five groups containing 15 people each for in vivo study. Exfoliated buccal mucosa cells were collected immediately before mouthrinse exposure and after 2 weeks. Furthermore, blood samples were obtained from three healthy donors for in vitro study. The micronucleus test was used to evaluate mutagenicity and cytotoxicity in vivo. The single-cell gel (comet) assay was used to determine DNA damage in vitro. After 2 weeks exposure, Periogard showed 1.8% of micronucleated cells with significant statistical differences (p < 0.05) compared to before exposure (0.27%). Plax Whitening presented high tail moment value (4.5) when compared to negative control (0.6). The addition of all mouthrinses to cells incubated with methyl methanesulfonate did not alter the number of strand breaks in the genetic material. Listerine was able to reduce genetic damage induced by hydrogen peroxide because a decrease of tail moment was noticed. The results of the present study suggest that Periogard and Plax Whitening can induce genetic damage, whereas Listerine is an antioxidant agent. Since DNA damage is considered to be prime mechanism during chemical carcinogenesis, these data may be relevant in risk assessment for protecting human health and preventing carcinogenesis.

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Immunological interaction between the host and Helicobacter pylori seems to play a critical role in follicular formation in gastric mucosa. We reported H. pylori-induced follicular gastritis model using neonatally thymectomized mice. In this study, we investigated the involvement of various cytokines in this model. BALB/c mice were thymectomized on the third day after birth (nTx). At 6 weeks old, these mice were orally infected with H. pylori. Histological studies showed that follicular formation occurred from 8 weeks after the infection and that most of the infiltrating lymphocytes were CD4؉ and B cells. Neutrophils increased transiently at 1 week after the infection. Gamma interferon, interleukin-7 (IL-7), and IL-7 receptor were expressed in the stomach of the nTx mice irrespective of the infection. In contrast, expressions of the tumor necrosis factor alpha, IL-4 and lymphotoxin-␣ genes were remarkably upregulated by the infection. Our findings suggest that follicular formation may require cooperative involvement of a Th2-type immune response, tumor necrosis factor alpha and lymphotoxin-␣ in addition to the Th1-type immune response in H. pylori-induced gastritis in nTx mice.

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