Helicobacter pylori-secreted factors inhibit dendritic cell IL-12 secretion: a mechanism of ineffective host defense

Helicobacter pylori evades host immune defenses and causes chronic gastritis. Immunity against intestinal pathogens is largely mediated by dendritic cells, yet the role of dendritic cells in acute H. pylori infection is largely unknown. We observed the recruitment of dendritic cells to the gastric m...

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Bibliographic Details
Published in:American journal of physiology: Gastrointestinal and liver physiology 2006-07, Vol.291 (1), p.G73-G81
Main Authors: Kao, John Y, Rathinavelu, Sivaprakash, Eaton, Kathryn A, Bai, Longchuan, Zavros, Yana, Takami, Mimi, Pierzchala, Anna, Merchant, Juanita L
Format: Article
Language:English
Subjects:
Acinetobacter - immunology
Animals
Bacterial Proteins - immunology
Cells, Cultured
Cytokines - immunology
Dendritic Cells - immunology
Dendritic Cells - microbiology
Gastric Mucosa - immunology
Gastric Mucosa - microbiology
Helicobacter pylori - immunology
Immunity, Innate - immunology
Immunity, Mucosal - immunology
Interleukin-12 - immunology
Mice
Mice, Inbred C57BL
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Summary:Helicobacter pylori evades host immune defenses and causes chronic gastritis. Immunity against intestinal pathogens is largely mediated by dendritic cells, yet the role of dendritic cells in acute H. pylori infection is largely unknown. We observed the recruitment of dendritic cells to the gastric mucosa of H. pylori-infected mice. Bone marrow-derived dendritic cells from mice responded to live H. pylori by upregulating the expression of proinflammatory cytokine mRNA (i.e., IL-1alpha, IL-1beta, and IL-6). The supernatant from dendritic cells stimulated with H. pylori for 18 h contained twofold higher levels of IL-12p70 than IL-10 and induced the proliferation of syngeneic splenocytes and type 1 T helper cell cytokine release (IFN-gamma and TNF-alpha). These responses were significantly lower compared with those induced by Acinetobacter lwoffi, another gastritis-causing pathogen more susceptible to host defenses. Analysis of whole H. pylori sonicate revealed the presence of a heat-stable factor secreted from H. pylori that specifically inhibited IL-12 but not IL-10 release from dendritic cells activated by A. lwoffi. Our findings suggest that dendritic cells participate in the host immune response against H. pylori and that their suppression by H. pylori may explain why infected hosts fail to prevent bacterial colonization.
ISSN:0193-1857
1522-1547
DOI:10.1152/ajpgi.00139.2005