Mechanisms of Helicobacter pylori Infection: Bacterial Factors

McGee, David J.; Mobley, Harry L. T.

doi:10.1007/978-3-642-60013-5_9

Cited by 94 publications

(96 citation statements)

References 157 publications

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“…Nevertheless, despite the importance of the adhesins in colonization and virulence, they have not been proven to be essential for in vivo survival of H. pylori. 60 H. pylori lipopolysaccharide (LPS) has also been implicated in another aspect of the pathogenesis of H. pylori infection. LPS is a family of toxic phosphorylated glycolipids in the outer membrane of Gram-negative bacteria and is composed of a lipid moiety (termed lipid A), a core oligosaccharide, and a polymeric O-specific polysaccharide chain.…”

Section: Relevance Of Strain Types Of H Pylori In the Outcome Of Infmentioning

confidence: 99%

Helicobacter pylori: recent advances in the study of its pathogenicity and prevention

Aguilar¹,

Ayala²,

Fierros-Zarate³

2001

Salud pública Méx

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Helicobacter pylori has acquired great importance during the last two decades, after being recognized as an important pathogen that infects a great portion of the human population. This microorganism is recognized as the main causal agent of chronic gastritis and duodenal ulcers, and it is associated with the subsequent development of gastric carcinoma. The pathogenic mechanisms of H. pylori and their relation to gastric ailments have not been clearly defined. However, at present it is well established that urease, vacuolating cytotoxin VacA, and the pathogenicity island (cag PAI) gene products, are the main factors of virulence of this organism. Thus, individuals infected with strains that express these virulence factors probably develop a severe local inflammation that may induce the development of peptic ulcer and gastric cancer. The way the infection spreads throughout the world suggests the possibility that there are multiple pathways of transmission. Due to the importance that H. pylori has acquired as a human pathogen, laboratories worldwide are attempting to develop a vaccine that confers long-term immunological protection against infection by this microorganism. Hence, the objective of this review is to present the most relevant findings of the biology of H. Pylori and its interaction with the human host. The full version of this paper is available too at: http:// www.insp.mx/salud/index.html ResumenHelicobacter pylori ha adquirido gran importancia durante las últimas dos décadas, al ser reconocido como un importante patógeno que infecta una gran porción de la población humana. Este microrganismo es reconocido como el principal agente que causa la gastritis crónica y la úlcera duodenal, además de que se ha asociado con el subsecuente desarrollo del carcinoma gástrico. Los mecanismos patogé-nicos de H. pylori y su relación con los padecimientos gás-tricos no se han definido en forma clara. Sin embargo, actualmente está bien establecido que la ureasa, la citotoxina vacuolizante VacA y los productos de los genes de la isla de patogenicidad (cag PAI) son los principales factores de virulencia de este organismo. Así, los individuos infectados con cepas que expresan dichos factores de virulencia, probablemente manifiesten una marcada inflamación local que podría inducir el desarrollo de úlcera péptica y cáncer gástri-co. La manera como la infección se propaga a nivel mundial sugiere la posibilidad de múltiples vías de transmisión. A consecuencia de la importancia que H. pylori ha adquirido como patógeno humano, los laboratorios del mundo se esfuerzan para desarrollar una vacuna que confiera protección inmunológica de larga duración contra la infección por este microorganismo. El objetivo de esta revisión es presentar los hallazgos más relevantes sobre la biología de H. pylori y su interacción con su huésped humano. El texto completo de este artículo también está disponible en:

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Section: Relevance Of Strain Types Of H Pylori In the Outcome Of Infmentioning

confidence: 99%

Helicobacter pylori: recent advances in the study of its pathogenicity and prevention

Aguilar¹,

Ayala²,

Fierros-Zarate³

2001

Salud pública Méx

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“…Urease of H. pylori accounts for about 10% of the total cell protein that is expressed in most of the strains (Suzuki et al, 2007). This enzyme, a nickelrequiring metalloenzyme, consists of two subunits, UreA and UreB (Hu et al, 1992), which hydrolyze urea to ammonia and carbon dioxide within the gastric mucus layer to facilitate its initial interaction in this acidic environment (McGee and Mobley, 1999). There are some other proposed roles for H. pylori urease, including its involvement in colonization of the gastric tissue, chemotactic activity for human monocytes, inhibition of the phagocytosis, intracellular survival of the bacterium, induction of inflammatory cytokines and inducible NO synthase (iNOS) (Shimoyama et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Relationship between ureB Sequence Diversity, Urease Activity and Genotypic Variations of Different Helicobacter pylori Strains in Patients with Gastric Disorders

Ghalehnoei

Ahmadzadeh

Farzi

et al. 2016

Polish Journal of Microbiology

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A b s t r a c tAssociation of the severity of Helicobacter pylori induced diseases with virulence entity of the colonized strains was proven in some studies. Urease has been demonstrated as a potent virulence factor for H. pylori. The main aim of this study was investigation of the relationships of ureB sequence diversity, urease activity and virulence genotypes of different H. pylori strains with histopathological changes of gastric tissue in infected patients suffering from different gastric disorders. Analysis of the virulence genotypes in the isolated strains indicated significant associations between the presence of severe active gastritis and cagA + (P = 0.039) or cagA/iceA1 genotypes (P = 0.026), and intestinal metaplasia and vacA m1 (P = 0.008) or vacA s1/m2 (P = 0.001) genotypes. Our results showed a 2.4-fold increased risk of peptic ulcer (95% CI: 0.483-11.93), compared with gastritis, in the infected patients who had dupA positive strains; however this association was not statistically significant. The results of urease activity showed a significant mean difference between the isolated strains from patients with PUD and NUD (P = 0.034). This activity was relatively higher among patients with intestinal metaplasia. Also a significant association was found between the lack of cagA and increased urease activity among the isolated strains (P = 0.036). While the greatest sequence variation of ureB was detected in a strain from a patient with intestinal metaplasia, the sole determined amino acid change in UreB sequence (Ala201Thr, 30%), showed no influence on urease activity. In conclusion, the supposed role of H. pylori urease to form peptic ulcer and advancing of intestinal metaplasia was postulated in this study. Higher urease activity in the colonizing H. pylori strains that present specific virulence factors was indicated as a risk factor for promotion of histopathological changes of gastric tissue that advance gastric malignancy. K e y w o r d s: Helicobacter pylori, virulence, factor urease activity, histopathological changes

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“…Therefore, the mucosa barrier will be injured by autoimmune reaction (Appelmelk et al, 1996) . Free radical: When H. pylori infects the stomach, it can adhere to gastric epithelium via its surface structure such as N-acetylneuraminic lactose fibril haemogglutinin, extra cellular S adhesin and Lewis B blood-group antigen adhesin, etc (Lundstrom et al, 2001;Domingo et al, 1999;Dundon et al, 2001;McGee et al, 1999) . Neutrophil chemotactic factors such as VacA, CagA and neutrophil activating protein (NAP) are released (Atherton et al, 1997;Naito et al, 2002;Satin et al, 2000;Yoshikawa et al, 2000).…”

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confidence: 99%

Effects of Helicobacter pylori and Non-Steroidal Anti-Inflammatory Drugs on Peptic Ulcer

Wang¹,

Wang²

2011

Peptic Ulcer Disease

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Mechanisms of Helicobacter pylori Infection: Bacterial Factors

Cited by 94 publications

References 157 publications

Helicobacter pylori: recent advances in the study of its pathogenicity and prevention

Helicobacter pylori: recent advances in the study of its pathogenicity and prevention

Relationship between ureB Sequence Diversity, Urease Activity and Genotypic Variations of Different Helicobacter pylori Strains in Patients with Gastric Disorders

Effects of Helicobacter pylori and Non-Steroidal Anti-Inflammatory Drugs on Peptic Ulcer

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