Assessment of invasion frequencies of cultured HEp-2 cells by clinical isolates of Helicobacter pylori using an acridine orange assay.

Sg, Wilkinson; Uhl, James R.; Kline, Bruce C.; Cockerill, Franklin R.

doi:10.1136/jcp.51.2.127

Cited by 45 publications

(43 citation statements)

References 21 publications

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“…For a very long time, H. pylori was considered an extracellular pathogen (52,53,56), but an increasing number of re- ports based on biospy examination and in vitro infection experiments have indicated that at least some host-associated H. pylori bacteria are located within host epithelial cells (19,28,31,50,62,64,73,79,85). In the present study, we used AGS cells as an infection model in order to demonstrate that the penetration of gastric epithelial cells is a multifactorial process resulting from an intricate interplay between H. pylori and host cells.…”

Section: Discussionmentioning

confidence: 99%

“…Early reports indicated that H. pylori was not present in the gastric mucosa but was present in the mucus layer overlying the gastric tissue (52,53,56). However, in recent years, a number of biospy studies (28,30,62) and cell culture infection models (19,31,50,64,73,79,85) have provided increasing evidence for the intracellular localization of H. pylori. Clearance of intracellular H. pylori has been demonstrated in vitro by using antibiotics with known intracellular activity (40).…”

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confidence: 99%

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Specific Entry ofHelicobacter pyloriinto Cultured Gastric Epithelial Cells via a Zipper-Like Mechanism

et al. 2002

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Although Helicobacter pylori has generally been considered an extracellular pathogen, a number of in vitro infection experiments and biopsy examinations have shown that it is capable of occasionally entering mammalian host cells. Here, we characterized this entry process by using AGS cells as a host cell model. In gentamicin protection-invasion assays, the number of H. pylori colonies recovered was lower than that for Salmonella enterica serovar Typhimurium X22, Escherichia coli expressing InvA, and Yersinia enterocolitica YO:9 grown at 25°C but higher than that for Neisseria gonorrhoeae VP1 and Y. enterocolitica YO:9 grown at 37°C. At the ultrastructural level, the entry process was observed to occur via a zipper-like mechanism. Internalized H. pylori was bound in tight LAMP-1-containing vacuoles in close association with condensed filamentous actin and tyrosine phosphorylation signals. Wortmannin, a potent inhibitor of phosphatidylinositol 3-kinase, and calphostin C, an inhibitor of protein kinase C, both inhibited the entry of H. pylori in a sensitive and dosedependent manner; however, the level of entry was enhanced by sodium vanadate, an inhibitor of tyrosine phosphatases and ATPases. Furthermore, the cytokine tumor necrosis factor alpha antagonized the entry of H. pylori into AGS cells. Collectively, these results demonstrate that the entry of H. pylori into AGS cells occurs via a zipper-like mechanism which involves various host signal transduction events.

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Section: Discussionmentioning

confidence: 99%

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Specific Entry ofHelicobacter pyloriinto Cultured Gastric Epithelial Cells via a Zipper-Like Mechanism

et al. 2002

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“…Although about 10% of H. pylori can adhere to gastric epithelial cells, organisms are rarely found intracellularly (31)(32)(33). Adherence of H. pylori to the gastric epithelium is a complicated process that involves a number of bacterial cell-surface receptors, including the Lewis B-bind- ing (Le b -binding) adhesin BabA (34), an outer membrane protein encoded by babA2 that binds the histo-blood group antigen Le b on the surface of epithelial cells.…”

Section: Role Of Bacterial Virulence Factors In H Pylori Persistencementioning

confidence: 99%

Inflammation, atrophy, and gastric cancer

Fox

Wang²

2007

J. Clin. Invest.

689

626

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The association between chronic inflammation and cancer is now well established. This association has recently received renewed interest with the recognition that microbial pathogens can be responsible for the chronic inflammation observed in many cancers, particularly those originating in the gastrointestinal system. A prime example is Helicobacter pylori, which infects 50% of the world's population and is now known to be responsible for inducing chronic gastric inflammation that progresses to atrophy, metaplasia, dysplasia, and gastric cancer. This Review provides an overview of recent progress in elucidating the bacterial properties responsible for colonization of the stomach, persistence in the stomach, and triggering of inflammation, as well as the host factors that have a role in determining whether gastritis progresses to gastric cancer. We also discuss how the increased understanding of the relationship between inflammation and gastric cancer still leaves many questions unanswered regarding recommendations for prevention and treatment.

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“…HEp-2 cells from a patent with human larynx carcinoma were obtained from the American Type Culture Collection (ATCC CCL 23) and were grown on tissue culture plasticware in basal Eagle's medium supplemented with Hanks' salts, 50 mM L-glutamine, 0.075% sodium bicarbonate, and 15% fetal bovine serum (FBS; Sigma Chemical Co., S. Louis, Mo.). The cells were incubated at 37°C in 5% CO 2 and with 99% humidity, as described previously (54).…”

Section: Methodsmentioning

confidence: 99%

In Vivo and In Vitro Studies of Cytosolic Phospholipase A₂Expression inHelicobacter pyloriInfection

Nardone¹,

Holicky

Uhl

et al. 2001

Infect Immun

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Modifications of mucosal phospholipids have been detected in samples from patients with Helicobacter pylori-positive gastritis. These alterations appear secondary to increased phospholipase A 2 activity (PLA 2 ). The cytosolic form of this enzyme (cPLA 2 ), normally involved in cellular signaling and growth, has been implicated in cancer pathogenesis. The aim of this study was to investigate cPLA 2 expression and PLA 2 activity in the gastric mucosae of patients with and without H. pylori infection. In gastric biopsies from 10 H. pylori-positive patients, cPLA 2 levels, levels of mRNA as determined by reverse transcriptase PCR, levels of protein as determined by immunohistochemistry, and total PLA 2 activity were higher than in 10 H. pylori-negative gastritis patients. To clarify whether H. pylori had a direct effect on the cellular expression of cPLA 2 , we studied cPLA 2 expression in vitro with different human epithelial cell lines, one from a patient with larynx carcinoma (i.e., HEp-2 cells) and two from patients with gastric adenocarcinoma (i.e., AGS and MKN 28 cells), incubated with different H. pylori strains. The levels of cPLA 2 , mRNA, and protein expression were unchanged in Hep-2 cells independently of cellular adhesion or invasion of the bacteria. Moreover, no change in cPLA 2 protein expression was observed in AGS or MKN 28 cells treated with wild-type H. pylori. In conclusion, our study shows increased cPLA 2 expression and PLA 2 activity in the gastric mucosae of patients with H. pylori infection and no change in epithelial cell lines exposed to H. pylori.Helicobacter pylori infection of the gastric mucosa is present worldwide and may be associated with several pathologic alterations, including gastric cancer (30). The relationship between this organism and the development of gastric cancer has been postulated mainly on the basis of epidemiological investigations and animal models of H. pylori infection (13,15,17,21,39,40,53). This relationship is further supported by the finding that some patients with H. pylori infection show the genetic abnormalities of dysplasia and metaplasia in mucosal areas before the development of carcinoma (35, 50). However, the molecular mechanisms underlying the multistep process of gastric carcinogenesis related to H. pylori infection remain undefined (57). It has been shown that H. pylori damages the gastric barrier function and induces a dramatic change in mucosal phospholipid composition (34). This is likely due to a local increase in phospholipase A 2 (PLA 2 ) activity (4, 27). The cytosolic form (cPLA 2 ), but not the secretory form, of this enzyme is involved in cellular signaling and growth (2,25,26,28,31,38,51) and has recently been implicated in the pathogenesis of malignant transformation (11,22,32,48,49,55,56). Furthermore, many human tumors have been reported to exhibit increased synthesis of prostaglandins, the formation of which is dependent on an increase in cPLA 2 activity (16,18,19,29).In this study, we analyzed cPLA 2 expression in gastric-mucosal b...

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Assessment of invasion frequencies of cultured HEp-2 cells by clinical isolates of Helicobacter pylori using an acridine orange assay.

Cited by 45 publications

References 21 publications

Specific Entry ofHelicobacter pyloriinto Cultured Gastric Epithelial Cells via a Zipper-Like Mechanism

Specific Entry ofHelicobacter pyloriinto Cultured Gastric Epithelial Cells via a Zipper-Like Mechanism

Inflammation, atrophy, and gastric cancer

In Vivo and In Vitro Studies of Cytosolic Phospholipase A₂Expression inHelicobacter pyloriInfection

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Assessment of invasion frequencies of cultured HEp-2 cells by clinical isolates of Helicobacter pylori using an acridine orange assay.

Cited by 45 publications

References 21 publications

Specific Entry ofHelicobacter pyloriinto Cultured Gastric Epithelial Cells via a Zipper-Like Mechanism

Specific Entry ofHelicobacter pyloriinto Cultured Gastric Epithelial Cells via a Zipper-Like Mechanism

Inflammation, atrophy, and gastric cancer

In Vivo and In Vitro Studies of Cytosolic Phospholipase A2Expression inHelicobacter pyloriInfection

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In Vivo and In Vitro Studies of Cytosolic Phospholipase A₂Expression inHelicobacter pyloriInfection