<named-content content-type="genus-species">Ehrlichia chaffeensis</named-content> Uses an Invasin To Suppress Reactive Oxygen Species Generation by Macrophages via CD147-Dependent Inhibition of Vav1 To Block Rac1 Activation

ABSTRACT The obligatory intracellular pathogen Ehrlichia chaffeensis lacks most factors that could respond to oxidative stress (a host cell defense mechanism). We previously found that the C terminus of Ehrlichia surface invasin, entry-triggering protein of Ehrlichia (EtpE; EtpE-C) directly binds ma...

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Autores principales:	Omid Teymournejad, Yasuko Rikihisa
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2020
Materias:	CD147 Ehrlichia chaffeensis invasin Rac1 Vav1 macrophages Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/c5a96ac06bf64f6196a20e30f627c342
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spelling	oai:doaj.org-article:c5a96ac06bf64f6196a20e30f627c3422021-11-15T15:57:01Z<named-content content-type="genus-species">Ehrlichia chaffeensis</named-content> Uses an Invasin To Suppress Reactive Oxygen Species Generation by Macrophages via CD147-Dependent Inhibition of Vav1 To Block Rac1 Activation10.1128/mBio.00267-202150-7511https://doaj.org/article/c5a96ac06bf64f6196a20e30f627c3422020-04-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.00267-20https://doaj.org/toc/2150-7511ABSTRACT The obligatory intracellular pathogen Ehrlichia chaffeensis lacks most factors that could respond to oxidative stress (a host cell defense mechanism). We previously found that the C terminus of Ehrlichia surface invasin, entry-triggering protein of Ehrlichia (EtpE; EtpE-C) directly binds mammalian DNase X, a glycosylphosphatidylinositol-anchored cell surface receptor and that binding is required to induce bacterial entry and simultaneously to block the generation of reactive oxygen species (ROS) by host monocytes and macrophages. However, how the EtpE-C−DNase X complex mediates the ROS blockade was unknown. A mammalian transmembrane glycoprotein CD147 (basigin) binds to the EtpE-DNase X complex and is required for Ehrlichia entry and infection of host cells. Here, we found that bone marrow-derived macrophages (BMDM) from myeloid cell lineage-selective CD147-null mice had significantly reduced Ehrlichia-induced or EtpE-C-induced blockade of ROS generation in response to phorbol myristate acetate. In BMDM from CD147-null mice, nucleofection with CD147 partially restored the Ehrlichia-mediated inhibition of ROS generation. Indeed, CD147-null mice as well as their BMDM were resistant to Ehrlichia infection. Moreover, in human monocytes, anti-CD147 partially abrogated EtpE-C-induced blockade of ROS generation. Both Ehrlichia and EtpE-C could block activation of the small GTPase Rac1 (which in turn activates phagocyte NADPH oxidase) and suppress activation of Vav1, a hematopoietic-specific Rho/Rac guanine nucleotide exchange factor by phorbol myristate acetate. Vav1 suppression by Ehrlichia was CD147 dependent. E. chaffeensis is the first example of pathogens that block Rac1 activation to colonize macrophages. Furthermore, Ehrlichia uses EtpE to hijack the unique host DNase X-CD147-Vav1 signaling to block Rac1 activation. IMPORTANCE Ehrlichia chaffeensis is an obligatory intracellular bacterium with the capability of causing an emerging infectious disease called human monocytic ehrlichiosis. E. chaffeensis preferentially infects monocytes and macrophages, professional phagocytes, equipped with an arsenal of antimicrobial mechanisms, including rapid reactive oxygen species (ROS) generation upon encountering bacteria. As Ehrlichia isolated from host cells are readily killed upon exposure to ROS, Ehrlichia must have evolved a unique mechanism to safely enter phagocytes. We discovered that binding of the Ehrlichia surface invasin to the host cell surface receptor not only triggers Ehrlichia entry but also blocks ROS generation by the host cells by mobilizing a novel intracellular signaling pathway. Knowledge of the mechanisms by which ROS production is inhibited may lead to the development of therapeutics for ehrlichiosis as well as other ROS-related pathologies.Omid TeymournejadYasuko RikihisaAmerican Society for MicrobiologyarticleCD147Ehrlichia chaffeensisinvasinRac1Vav1macrophagesMicrobiologyQR1-502ENmBio, Vol 11, Iss 2 (2020)
institution	DOAJ
collection	DOAJ
language	EN
topic	CD147 Ehrlichia chaffeensis invasin Rac1 Vav1 macrophages Microbiology QR1-502
spellingShingle	CD147 Ehrlichia chaffeensis invasin Rac1 Vav1 macrophages Microbiology QR1-502 Omid Teymournejad Yasuko Rikihisa <named-content content-type="genus-species">Ehrlichia chaffeensis</named-content> Uses an Invasin To Suppress Reactive Oxygen Species Generation by Macrophages via CD147-Dependent Inhibition of Vav1 To Block Rac1 Activation
description	ABSTRACT The obligatory intracellular pathogen Ehrlichia chaffeensis lacks most factors that could respond to oxidative stress (a host cell defense mechanism). We previously found that the C terminus of Ehrlichia surface invasin, entry-triggering protein of Ehrlichia (EtpE; EtpE-C) directly binds mammalian DNase X, a glycosylphosphatidylinositol-anchored cell surface receptor and that binding is required to induce bacterial entry and simultaneously to block the generation of reactive oxygen species (ROS) by host monocytes and macrophages. However, how the EtpE-C−DNase X complex mediates the ROS blockade was unknown. A mammalian transmembrane glycoprotein CD147 (basigin) binds to the EtpE-DNase X complex and is required for Ehrlichia entry and infection of host cells. Here, we found that bone marrow-derived macrophages (BMDM) from myeloid cell lineage-selective CD147-null mice had significantly reduced Ehrlichia-induced or EtpE-C-induced blockade of ROS generation in response to phorbol myristate acetate. In BMDM from CD147-null mice, nucleofection with CD147 partially restored the Ehrlichia-mediated inhibition of ROS generation. Indeed, CD147-null mice as well as their BMDM were resistant to Ehrlichia infection. Moreover, in human monocytes, anti-CD147 partially abrogated EtpE-C-induced blockade of ROS generation. Both Ehrlichia and EtpE-C could block activation of the small GTPase Rac1 (which in turn activates phagocyte NADPH oxidase) and suppress activation of Vav1, a hematopoietic-specific Rho/Rac guanine nucleotide exchange factor by phorbol myristate acetate. Vav1 suppression by Ehrlichia was CD147 dependent. E. chaffeensis is the first example of pathogens that block Rac1 activation to colonize macrophages. Furthermore, Ehrlichia uses EtpE to hijack the unique host DNase X-CD147-Vav1 signaling to block Rac1 activation. IMPORTANCE Ehrlichia chaffeensis is an obligatory intracellular bacterium with the capability of causing an emerging infectious disease called human monocytic ehrlichiosis. E. chaffeensis preferentially infects monocytes and macrophages, professional phagocytes, equipped with an arsenal of antimicrobial mechanisms, including rapid reactive oxygen species (ROS) generation upon encountering bacteria. As Ehrlichia isolated from host cells are readily killed upon exposure to ROS, Ehrlichia must have evolved a unique mechanism to safely enter phagocytes. We discovered that binding of the Ehrlichia surface invasin to the host cell surface receptor not only triggers Ehrlichia entry but also blocks ROS generation by the host cells by mobilizing a novel intracellular signaling pathway. Knowledge of the mechanisms by which ROS production is inhibited may lead to the development of therapeutics for ehrlichiosis as well as other ROS-related pathologies.
format	article
author	Omid Teymournejad Yasuko Rikihisa
author_facet	Omid Teymournejad Yasuko Rikihisa
author_sort	Omid Teymournejad
title	<named-content content-type="genus-species">Ehrlichia chaffeensis</named-content> Uses an Invasin To Suppress Reactive Oxygen Species Generation by Macrophages via CD147-Dependent Inhibition of Vav1 To Block Rac1 Activation
title_short	<named-content content-type="genus-species">Ehrlichia chaffeensis</named-content> Uses an Invasin To Suppress Reactive Oxygen Species Generation by Macrophages via CD147-Dependent Inhibition of Vav1 To Block Rac1 Activation
title_full	<named-content content-type="genus-species">Ehrlichia chaffeensis</named-content> Uses an Invasin To Suppress Reactive Oxygen Species Generation by Macrophages via CD147-Dependent Inhibition of Vav1 To Block Rac1 Activation
title_fullStr	<named-content content-type="genus-species">Ehrlichia chaffeensis</named-content> Uses an Invasin To Suppress Reactive Oxygen Species Generation by Macrophages via CD147-Dependent Inhibition of Vav1 To Block Rac1 Activation
title_full_unstemmed	<named-content content-type="genus-species">Ehrlichia chaffeensis</named-content> Uses an Invasin To Suppress Reactive Oxygen Species Generation by Macrophages via CD147-Dependent Inhibition of Vav1 To Block Rac1 Activation
title_sort	<named-content content-type="genus-species">ehrlichia chaffeensis</named-content> uses an invasin to suppress reactive oxygen species generation by macrophages via cd147-dependent inhibition of vav1 to block rac1 activation
publisher	American Society for Microbiology
publishDate	2020
url	https://doaj.org/article/c5a96ac06bf64f6196a20e30f627c342
work_keys_str_mv	AT omidteymournejad namedcontentcontenttypegenusspeciesehrlichiachaffeensisnamedcontentusesaninvasintosuppressreactiveoxygenspeciesgenerationbymacrophagesviacd147dependentinhibitionofvav1toblockrac1activation AT yasukorikihisa namedcontentcontenttypegenusspeciesehrlichiachaffeensisnamedcontentusesaninvasintosuppressreactiveoxygenspeciesgenerationbymacrophagesviacd147dependentinhibitionofvav1toblockrac1activation
_version_	1718427052062801920

<named-content content-type="genus-species">Ehrlichia chaffeensis</named-content> Uses an Invasin To Suppress Reactive Oxygen Species Generation by Macrophages via CD147-Dependent Inhibition of Vav1 To Block Rac1 Activation

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