The innate immune molecule, NOD1, regulates direct killing of Helicobacter pylori by antimicrobial peptides

Alexandra Grubman, Maria Liaskos, Jerome Viala, Cody Charles Allison, Luminita Badea, Abdulgader Karrar, Ivo G Boneca, Lionel Le Bourhis, Shane Bernadine Reeve, Alexander Ian Smith, Elizabeth Louise Hartland, Dana J Philpott, Richard Louis Ferrero

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72 Citations (Scopus)

Abstract

Summary The cytosolic innate immune molecule, NOD1, recognizes peptidoglycan (PG) delivered to epithelial cells via the Helicobacter pyloricag pathogenicity island (cagPAI), and has been implicated in host defence against cagPAI(+)H. pylori bacteria. To further clarify the role of NOD1 in host defence, we investigated NOD1-dependent regulation of human beta-defensins (DEFBs) in two epithelial cell lines. Our findings identify that NOD1 activation, via either cagPAI(+) bacteria or internalized PG, was required for DEFB4 and DEFB103 expression in HEK293 cells. To investigate cell type-specific induction of DEFB4 and DEFB103, we generated stable NOD1 knockdown (KD) and control AGS cells. Reporter gene assay and RT-PCR analyses revealed that only DEFB4 was induced in a NOD1-/cagPAI-dependent fashion in AGS cells. Moreover, culture supernatants from AGS control, but not AGS NOD1 KD cells, stimulated with cagPAI(+)H. pylori, significantly reduced H. pylori bacterial numbers. siRNA studies confirmed that human beta-defensin 2 (hBD-2), but not hBD-3, contributes to the antimicrobial activity of AGS cell supernatants against H. pylori. This study demonstrates for the first time the involvement of NOD1 and hBD-2 in direct killing of H. pylori bacteria by epithelial cells and confirms the importance of NOD1 in host defence mechanisms against cagPAI(+)H. pylori infection.
Original languageEnglish
Pages (from-to)626-639
Number of pages13
JournalCellular Microbiology
Volume12
Issue number5
DOIs
Publication statusPublished - 2010

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