Analysis of the relative contribution of phagocytosis, LC3-associated phagocytosis, and canonical autophagy during helicobacter pyloriiInfection of macrophages

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Abstract

BACKGROUND: Previous findings have suggested that Helicobacter pylori induces autophagic processes and subsequently takes refuge in autophagosomes, thereby contributing to persistent infection. Recently, a noncanonical form of autophagy, LC3 (microtubule-associated protein 1 light chain 3)-associated phagocytosis (LAP), has been shown to be required for efficient clearance of some intracellular bacteria. Whether H. pylori infection induces LAP had not been examined previously. In this study, we determined the extent to which H. pylori infection induces canonical autophagy or LAP in macrophages, and the involvement of the H. pylori cag pathogenicity island (cagPAI) with these processes. METHODS: Immunofluorescence confocal microscopy was used to analyze the formation of GFP-LC3 puncta and their colocalization with H. pylori. Transmission electron microscopy was used to detect the ultrastructure of H. pylori-containing compartments. RESULTS: The majority of intracellular bacteria (85-95 ) were found in phagosomes that were LC3-negative, with a small proportion (4-14 ) appearing free in the cytosol. Only a very small percentage (0.5-6 ) of intracellular H. pylori was sequestered in autophagosomes. Furthermore, no statistically significant difference in the relative distribution of H. pylori in the various compartments was observed between wild-type and cagPAI-mutant bacteria. CONCLUSIONS: In macrophages, H. pylori infection does not induce LAP, but can induce canonical autophagy, which entraps a very small fraction of intracellular bacteria. We propose that this subpopulation of intracellular H. pylori might have escaped from phagosomes into the cytosol before being sequestered by autophagosomes. The cagPAI of H. pylori has only minor influence, if any, on the extent of these processes.
Original languageEnglish
Pages (from-to)449 - 459
Number of pages11
JournalHelicobacter
Volume20
Issue number6
DOIs
Publication statusPublished - 2015

Cite this

@article{235618841639495a94ab0a9003ecae49,
title = "Analysis of the relative contribution of phagocytosis, LC3-associated phagocytosis, and canonical autophagy during helicobacter pyloriiInfection of macrophages",
abstract = "BACKGROUND: Previous findings have suggested that Helicobacter pylori induces autophagic processes and subsequently takes refuge in autophagosomes, thereby contributing to persistent infection. Recently, a noncanonical form of autophagy, LC3 (microtubule-associated protein 1 light chain 3)-associated phagocytosis (LAP), has been shown to be required for efficient clearance of some intracellular bacteria. Whether H. pylori infection induces LAP had not been examined previously. In this study, we determined the extent to which H. pylori infection induces canonical autophagy or LAP in macrophages, and the involvement of the H. pylori cag pathogenicity island (cagPAI) with these processes. METHODS: Immunofluorescence confocal microscopy was used to analyze the formation of GFP-LC3 puncta and their colocalization with H. pylori. Transmission electron microscopy was used to detect the ultrastructure of H. pylori-containing compartments. RESULTS: The majority of intracellular bacteria (85-95 ) were found in phagosomes that were LC3-negative, with a small proportion (4-14 ) appearing free in the cytosol. Only a very small percentage (0.5-6 ) of intracellular H. pylori was sequestered in autophagosomes. Furthermore, no statistically significant difference in the relative distribution of H. pylori in the various compartments was observed between wild-type and cagPAI-mutant bacteria. CONCLUSIONS: In macrophages, H. pylori infection does not induce LAP, but can induce canonical autophagy, which entraps a very small fraction of intracellular bacteria. We propose that this subpopulation of intracellular H. pylori might have escaped from phagosomes into the cytosol before being sequestered by autophagosomes. The cagPAI of H. pylori has only minor influence, if any, on the extent of these processes.",
author = "Deen, {Nadia S} and Lan Gong and Thomas Naderer and Devenish, {Rodney J} and Terry Kwok",
year = "2015",
doi = "10.1111/hel.12223",
language = "English",
volume = "20",
pages = "449 -- 459",
journal = "Helicobacter",
issn = "1083-4389",
publisher = "Wiley-Blackwell",
number = "6",

}

TY - JOUR

T1 - Analysis of the relative contribution of phagocytosis, LC3-associated phagocytosis, and canonical autophagy during helicobacter pyloriiInfection of macrophages

AU - Deen, Nadia S

AU - Gong, Lan

AU - Naderer, Thomas

AU - Devenish, Rodney J

AU - Kwok, Terry

PY - 2015

Y1 - 2015

N2 - BACKGROUND: Previous findings have suggested that Helicobacter pylori induces autophagic processes and subsequently takes refuge in autophagosomes, thereby contributing to persistent infection. Recently, a noncanonical form of autophagy, LC3 (microtubule-associated protein 1 light chain 3)-associated phagocytosis (LAP), has been shown to be required for efficient clearance of some intracellular bacteria. Whether H. pylori infection induces LAP had not been examined previously. In this study, we determined the extent to which H. pylori infection induces canonical autophagy or LAP in macrophages, and the involvement of the H. pylori cag pathogenicity island (cagPAI) with these processes. METHODS: Immunofluorescence confocal microscopy was used to analyze the formation of GFP-LC3 puncta and their colocalization with H. pylori. Transmission electron microscopy was used to detect the ultrastructure of H. pylori-containing compartments. RESULTS: The majority of intracellular bacteria (85-95 ) were found in phagosomes that were LC3-negative, with a small proportion (4-14 ) appearing free in the cytosol. Only a very small percentage (0.5-6 ) of intracellular H. pylori was sequestered in autophagosomes. Furthermore, no statistically significant difference in the relative distribution of H. pylori in the various compartments was observed between wild-type and cagPAI-mutant bacteria. CONCLUSIONS: In macrophages, H. pylori infection does not induce LAP, but can induce canonical autophagy, which entraps a very small fraction of intracellular bacteria. We propose that this subpopulation of intracellular H. pylori might have escaped from phagosomes into the cytosol before being sequestered by autophagosomes. The cagPAI of H. pylori has only minor influence, if any, on the extent of these processes.

AB - BACKGROUND: Previous findings have suggested that Helicobacter pylori induces autophagic processes and subsequently takes refuge in autophagosomes, thereby contributing to persistent infection. Recently, a noncanonical form of autophagy, LC3 (microtubule-associated protein 1 light chain 3)-associated phagocytosis (LAP), has been shown to be required for efficient clearance of some intracellular bacteria. Whether H. pylori infection induces LAP had not been examined previously. In this study, we determined the extent to which H. pylori infection induces canonical autophagy or LAP in macrophages, and the involvement of the H. pylori cag pathogenicity island (cagPAI) with these processes. METHODS: Immunofluorescence confocal microscopy was used to analyze the formation of GFP-LC3 puncta and their colocalization with H. pylori. Transmission electron microscopy was used to detect the ultrastructure of H. pylori-containing compartments. RESULTS: The majority of intracellular bacteria (85-95 ) were found in phagosomes that were LC3-negative, with a small proportion (4-14 ) appearing free in the cytosol. Only a very small percentage (0.5-6 ) of intracellular H. pylori was sequestered in autophagosomes. Furthermore, no statistically significant difference in the relative distribution of H. pylori in the various compartments was observed between wild-type and cagPAI-mutant bacteria. CONCLUSIONS: In macrophages, H. pylori infection does not induce LAP, but can induce canonical autophagy, which entraps a very small fraction of intracellular bacteria. We propose that this subpopulation of intracellular H. pylori might have escaped from phagosomes into the cytosol before being sequestered by autophagosomes. The cagPAI of H. pylori has only minor influence, if any, on the extent of these processes.

UR - http://onlinelibrary.wiley.com/doi/10.1111/hel.12223/epdf

U2 - 10.1111/hel.12223

DO - 10.1111/hel.12223

M3 - Article

VL - 20

SP - 449

EP - 459

JO - Helicobacter

JF - Helicobacter

SN - 1083-4389

IS - 6

ER -