<italic toggle="yes">Salmonella</italic> Suppresses the TRIF-Dependent Type I Interferon Response in Macrophages

ABSTRACT Salmonella enterica is an intracellular pathogen that causes diseases ranging from gastroenteritis to typhoid fever. Salmonella bacteria trigger an autophagic response in host cells upon infection but have evolved mechanisms for suppressing this response, thereby enhancing intracellular sur...

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Autores principales:	Katherine A. Owen, C. J. Anderson, James E. Casanova
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2016
Materias:	Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/f6a38c9960ce4835b5fd5756c48294e0
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spelling	oai:doaj.org-article:f6a38c9960ce4835b5fd5756c48294e02021-11-15T15:49:39Z<italic toggle="yes">Salmonella</italic> Suppresses the TRIF-Dependent Type I Interferon Response in Macrophages10.1128/mBio.02051-152150-7511https://doaj.org/article/f6a38c9960ce4835b5fd5756c48294e02016-03-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.02051-15https://doaj.org/toc/2150-7511ABSTRACT Salmonella enterica is an intracellular pathogen that causes diseases ranging from gastroenteritis to typhoid fever. Salmonella bacteria trigger an autophagic response in host cells upon infection but have evolved mechanisms for suppressing this response, thereby enhancing intracellular survival. We recently reported that S. enterica serovar Typhimurium actively recruits the host tyrosine kinase focal adhesion kinase (FAK) to the surface of the Salmonella-containing vacuole (SCV) (K. A. Owen et al., PLoS Pathog 10:e1004159, 2014). FAK then suppresses autophagy through activation of the Akt/mTORC1 signaling pathway. In FAK−/− macrophages, bacteria are captured in autophagosomes and intracellular survival is attenuated. Here we show that the cell-autonomous bacterial suppression of autophagy also suppresses the broader innate immune response by inhibiting production of beta interferon (IFN-β). Induction of bacterial autophagy (xenophagy), but not autophagy alone, triggers IFN-β production through a pathway involving the adapter TRIF and endosomal Toll-like receptor 3 (TLR3) and TLR4. Selective FAK knockout in macrophages resulted in rapid bacterial clearance from mucosal tissues after oral infection. Clearance correlated with increased IFN-β production by intestinal macrophages and with IFN-β-dependent induction of IFN-γ by intestinal NK cells. Blockade of either IFN-β or IFN-γ increased host susceptibility to infection, whereas experimental induction of IFN-β was protective. Thus, bacterial suppression of autophagy not only enhances cell-autonomous survival but also suppresses more-systemic innate immune responses by limiting type I and type II interferons. IMPORTANCE Salmonella enterica serovar Typhimurium represents one of the most commonly identified bacterial causes of foodborne illness worldwide. S. Typhimurium has developed numerous strategies to evade detection by the host immune system. Autophagy is a cellular process that involves the recognition and degradation of defective proteins and organelles. More recently, autophagy has been described as an important means by which host cells recognize and eliminate invading intracellular pathogens and plays a key role in the production of cytokines. Previously, we determined that Salmonella bacteria are able to suppress their own autophagic capture and elimination by macrophages. Building on that study, we show here that the inhibition of autophagy by Salmonella also prevents the induction of a protective cytokine response mediated by beta interferon (IFN-β) and IFN-γ. Together, these findings identify a novel virulence strategy whereby Salmonella bacteria prevent cell autonomous elimination via autophagy and suppress the activation of innate immune responses.Katherine A. OwenC. J. AndersonJames E. CasanovaAmerican Society for MicrobiologyarticleMicrobiologyQR1-502ENmBio, Vol 7, Iss 1 (2016)
institution	DOAJ
collection	DOAJ
language	EN
topic	Microbiology QR1-502
spellingShingle	Microbiology QR1-502 Katherine A. Owen C. J. Anderson James E. Casanova <italic toggle="yes">Salmonella</italic> Suppresses the TRIF-Dependent Type I Interferon Response in Macrophages
description	ABSTRACT Salmonella enterica is an intracellular pathogen that causes diseases ranging from gastroenteritis to typhoid fever. Salmonella bacteria trigger an autophagic response in host cells upon infection but have evolved mechanisms for suppressing this response, thereby enhancing intracellular survival. We recently reported that S. enterica serovar Typhimurium actively recruits the host tyrosine kinase focal adhesion kinase (FAK) to the surface of the Salmonella-containing vacuole (SCV) (K. A. Owen et al., PLoS Pathog 10:e1004159, 2014). FAK then suppresses autophagy through activation of the Akt/mTORC1 signaling pathway. In FAK−/− macrophages, bacteria are captured in autophagosomes and intracellular survival is attenuated. Here we show that the cell-autonomous bacterial suppression of autophagy also suppresses the broader innate immune response by inhibiting production of beta interferon (IFN-β). Induction of bacterial autophagy (xenophagy), but not autophagy alone, triggers IFN-β production through a pathway involving the adapter TRIF and endosomal Toll-like receptor 3 (TLR3) and TLR4. Selective FAK knockout in macrophages resulted in rapid bacterial clearance from mucosal tissues after oral infection. Clearance correlated with increased IFN-β production by intestinal macrophages and with IFN-β-dependent induction of IFN-γ by intestinal NK cells. Blockade of either IFN-β or IFN-γ increased host susceptibility to infection, whereas experimental induction of IFN-β was protective. Thus, bacterial suppression of autophagy not only enhances cell-autonomous survival but also suppresses more-systemic innate immune responses by limiting type I and type II interferons. IMPORTANCE Salmonella enterica serovar Typhimurium represents one of the most commonly identified bacterial causes of foodborne illness worldwide. S. Typhimurium has developed numerous strategies to evade detection by the host immune system. Autophagy is a cellular process that involves the recognition and degradation of defective proteins and organelles. More recently, autophagy has been described as an important means by which host cells recognize and eliminate invading intracellular pathogens and plays a key role in the production of cytokines. Previously, we determined that Salmonella bacteria are able to suppress their own autophagic capture and elimination by macrophages. Building on that study, we show here that the inhibition of autophagy by Salmonella also prevents the induction of a protective cytokine response mediated by beta interferon (IFN-β) and IFN-γ. Together, these findings identify a novel virulence strategy whereby Salmonella bacteria prevent cell autonomous elimination via autophagy and suppress the activation of innate immune responses.
format	article
author	Katherine A. Owen C. J. Anderson James E. Casanova
author_facet	Katherine A. Owen C. J. Anderson James E. Casanova
author_sort	Katherine A. Owen
title	<italic toggle="yes">Salmonella</italic> Suppresses the TRIF-Dependent Type I Interferon Response in Macrophages
title_short	<italic toggle="yes">Salmonella</italic> Suppresses the TRIF-Dependent Type I Interferon Response in Macrophages
title_full	<italic toggle="yes">Salmonella</italic> Suppresses the TRIF-Dependent Type I Interferon Response in Macrophages
title_fullStr	<italic toggle="yes">Salmonella</italic> Suppresses the TRIF-Dependent Type I Interferon Response in Macrophages
title_full_unstemmed	<italic toggle="yes">Salmonella</italic> Suppresses the TRIF-Dependent Type I Interferon Response in Macrophages
title_sort	<italic toggle="yes">salmonella</italic> suppresses the trif-dependent type i interferon response in macrophages
publisher	American Society for Microbiology
publishDate	2016
url	https://doaj.org/article/f6a38c9960ce4835b5fd5756c48294e0
work_keys_str_mv	AT katherineaowen italictoggleyessalmonellaitalicsuppressesthetrifdependenttypeiinterferonresponseinmacrophages AT cjanderson italictoggleyessalmonellaitalicsuppressesthetrifdependenttypeiinterferonresponseinmacrophages AT jamesecasanova italictoggleyessalmonellaitalicsuppressesthetrifdependenttypeiinterferonresponseinmacrophages
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<italic toggle="yes">Salmonella</italic> Suppresses the TRIF-Dependent Type I Interferon Response in Macrophages

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