A low molecular weight factor is a significant mediator of non-opsonic neutrophil activation by Helicobacter pylori

Leakey, Alison; Hirst, Robert G.; Brooy, Justin La

doi:10.1099/0022-1317-50-9-787

Cited by 4 publications

(1 citation statement)

References 18 publications

(49 reference statements)

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“…For gonococci proteins belonging to a family of heatmodifiable outer membrane proteins termed opacity-associated proteins are responsible for the activation (34). For H. pylori several soluble factors involved in the nonopsonic neutrophil activation have been described, including HP-NAP (7), the urease (35), a low molecular weight factor in water extracts from the bacteria (36), and the cecropin-like bactericidal peptide Hp (2-20) (37).…”

Section: Discussionmentioning

confidence: 99%

The Sialic Acid Binding SabA Adhesin of Helicobacter pylori Is Essential for Nonopsonic Activation of Human Neutrophils

Unemo

Aspholm-Hurtig

Ilver

et al. 2005

Journal of Biological Chemistry

105

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Infiltration of neutrophils and monocytes into the gastric mucosa is a hallmark of chronic gastritis caused by Helicobacter pylori. Certain H. pylori strains nonopsonized stimulate neutrophils to production of reactive oxygen species causing oxidative damage of the gastric epithelium. Here, the contribution of some H. pylori virulence factors, the blood group antigen-binding adhesin BabA, the sialic acid-binding adhesin SabA, the neutrophil-activating protein HP-NAP, and the vacuolating cytotoxin VacA, to the activation of human neutrophils in terms of adherence, phagocytosis, and oxidative burst was investigated. Neutrophils were challenged with wild type bacteria and isogenic mutants lacking BabA, SabA, HP-NAP, or VacA. Mutant and wild type strains lacking SabA had no neutrophil-activating capacity, demonstrating that binding of H. pylori to sialylated neutrophil receptors plays a pivotal initial role in the adherence and phagocytosis of the bacteria and the induction of the oxidative burst. The link between receptor binding and oxidative burst involves a G-proteinlinked signaling pathway and downstream activation of phosphatidylinositol 3-kinase as shown by experiments using signal transduction inhibitors. Collectively our data suggest that the sialic acid-binding SabA adhesin is a prerequisite for the nonopsonic activation of human neutrophils and, thus, is a virulence factor important for the pathogenesis of H. pylori infection.

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Section: Discussionmentioning

confidence: 99%

The Sialic Acid Binding SabA Adhesin of Helicobacter pylori Is Essential for Nonopsonic Activation of Human Neutrophils

Unemo

Aspholm-Hurtig

Ilver

et al. 2005

Journal of Biological Chemistry

105

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Problems in assaying neutrophil activators

Leakey

Hirst

2001

Trends in Microbiology

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The Physiological Role of Ferritin-Like Compounds in Bacteria

Smith

2004

Critical Reviews in Microbiology

130

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Iron, as the ferrous or ferric ion, is essential for the life processes of all eukaryotes and most prokaryotes; however, the element is toxic when in excess of that needed for cellular homeostasis. Ferrous ions can react with metabolically generated hydrogen peroxide to yield toxic hydroxyl radicals that in turn degrade lipids, DNA, and other cellular biomolecules. Mechanisms have evolved in living systems for iron detoxification and for the removal of excess ferrous ions from the cytosol. These detoxification mechanisms involve the oxidation of excess ferrous ions to the ferric state and storage of the ferric ions in ferritin-like proteins. There are at least three types of ferritin-like proteins in bacteria: bacterial ferritin, bacterioferritin, and dodecameric ferritin. These bacterial proteins are related to the ferritins found in eukaryotes. The structure and physical characteristics of the ferritin-like compounds have been elucidated in several bacteria. Unfortunately, the physiological roles of the bacterial ferritin-like compounds have been less thoroughly studied. A few studies conducted with mutants indicated that ferritin-like compounds can protect bacterial cells from iron overload, serve as an iron source when iron is limited, protect the bacterial cells against oxidative stress and/or protect DNA against enzymatic or oxidative attack. There is very little information available concerning the roles that ferritin-like compounds might play in the survival of bacteria in food, water, soil, or eukaryotic host environments.

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A low molecular weight factor is a significant mediator of non-opsonic neutrophil activation by Helicobacter pylori

Cited by 4 publications

References 18 publications

The Sialic Acid Binding SabA Adhesin of Helicobacter pylori Is Essential for Nonopsonic Activation of Human Neutrophils

The Sialic Acid Binding SabA Adhesin of Helicobacter pylori Is Essential for Nonopsonic Activation of Human Neutrophils

Problems in assaying neutrophil activators

The Physiological Role of Ferritin-Like Compounds in Bacteria

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