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MyD88-dependent inflammasome activation and autophagy inhibition contributes to Ehrlichia-induced liver injury and toxic shock
Severe hepatic inflammation is a common cause of acute liver injury following systemic infection with Ehrlichia, obligate Gram-negative intracellular bacteria that lack lipopolysaccharide (LPS). We have previously shown that type I IFN (IFN-I) and inflammasome activation are key host-pathogenic medi...
Autores principales: | , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Public Library of Science
2017
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5663626/ https://www.ncbi.nlm.nih.gov/pubmed/29049365 http://dx.doi.org/10.1371/journal.ppat.1006644 |
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author | Kader, Muhamuda Alaoui-EL-Azher, Mounia Vorhauer, Jennie Kode, Bhushan B Wells, Jakob Z. Stolz, Donna Michalopoulos, George Wells, Alan Scott, Melanie Ismail, Nahed |
author_facet | Kader, Muhamuda Alaoui-EL-Azher, Mounia Vorhauer, Jennie Kode, Bhushan B Wells, Jakob Z. Stolz, Donna Michalopoulos, George Wells, Alan Scott, Melanie Ismail, Nahed |
author_sort | Kader, Muhamuda |
collection | PubMed |
description | Severe hepatic inflammation is a common cause of acute liver injury following systemic infection with Ehrlichia, obligate Gram-negative intracellular bacteria that lack lipopolysaccharide (LPS). We have previously shown that type I IFN (IFN-I) and inflammasome activation are key host-pathogenic mediators that promote excessive inflammation and liver damage following fatal Ehrlichia infection. However, the underlying signals and mechanisms that regulate protective immunity and immunopathology during Ehrlichia infection are not well understood. To address this issue, we compared susceptibility to lethal Ixodes ovatus Ehrlichia (IOE) infection between wild type (WT) and MyD88-deficient (MyD88(-/-)) mice. We show here that MyD88(-/-) mice exhibited decreased inflammasome activation, attenuated liver injury, and were more resistant to lethal infection than WT mice, despite suppressed protective immunity and increased bacterial burden in the liver. MyD88-dependent inflammasome activation was also dependent on activation of the metabolic checkpoint kinase mammalian target of rapamycin complex 1 (mTORC1), inhibition of autophagic flux, and defective mitophagy in macrophages. Blocking mTORC1 signaling in infected WT mice and primary macrophages enhanced bacterial replication and attenuated inflammasome activation, suggesting autophagy promotes bacterial replication while inhibiting inflammasome activation. Finally, our data suggest TLR9 and IFN-I are upstream signaling mechanisms triggering MyD88-mediated mTORC1 and inflammasome activation in macrophages following Ehrlichia infection. This study reveals that Ehrlichia-induced liver injury and toxic shock are mediated by MyD88-dependent inflammasome activation and autophagy inhibition. |
format | Online Article Text |
id | pubmed-5663626 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2017 |
publisher | Public Library of Science |
record_format | MEDLINE/PubMed |
spelling | pubmed-56636262017-11-08 MyD88-dependent inflammasome activation and autophagy inhibition contributes to Ehrlichia-induced liver injury and toxic shock Kader, Muhamuda Alaoui-EL-Azher, Mounia Vorhauer, Jennie Kode, Bhushan B Wells, Jakob Z. Stolz, Donna Michalopoulos, George Wells, Alan Scott, Melanie Ismail, Nahed PLoS Pathog Research Article Severe hepatic inflammation is a common cause of acute liver injury following systemic infection with Ehrlichia, obligate Gram-negative intracellular bacteria that lack lipopolysaccharide (LPS). We have previously shown that type I IFN (IFN-I) and inflammasome activation are key host-pathogenic mediators that promote excessive inflammation and liver damage following fatal Ehrlichia infection. However, the underlying signals and mechanisms that regulate protective immunity and immunopathology during Ehrlichia infection are not well understood. To address this issue, we compared susceptibility to lethal Ixodes ovatus Ehrlichia (IOE) infection between wild type (WT) and MyD88-deficient (MyD88(-/-)) mice. We show here that MyD88(-/-) mice exhibited decreased inflammasome activation, attenuated liver injury, and were more resistant to lethal infection than WT mice, despite suppressed protective immunity and increased bacterial burden in the liver. MyD88-dependent inflammasome activation was also dependent on activation of the metabolic checkpoint kinase mammalian target of rapamycin complex 1 (mTORC1), inhibition of autophagic flux, and defective mitophagy in macrophages. Blocking mTORC1 signaling in infected WT mice and primary macrophages enhanced bacterial replication and attenuated inflammasome activation, suggesting autophagy promotes bacterial replication while inhibiting inflammasome activation. Finally, our data suggest TLR9 and IFN-I are upstream signaling mechanisms triggering MyD88-mediated mTORC1 and inflammasome activation in macrophages following Ehrlichia infection. This study reveals that Ehrlichia-induced liver injury and toxic shock are mediated by MyD88-dependent inflammasome activation and autophagy inhibition. Public Library of Science 2017-10-19 /pmc/articles/PMC5663626/ /pubmed/29049365 http://dx.doi.org/10.1371/journal.ppat.1006644 Text en © 2017 Kader et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. |
spellingShingle | Research Article Kader, Muhamuda Alaoui-EL-Azher, Mounia Vorhauer, Jennie Kode, Bhushan B Wells, Jakob Z. Stolz, Donna Michalopoulos, George Wells, Alan Scott, Melanie Ismail, Nahed MyD88-dependent inflammasome activation and autophagy inhibition contributes to Ehrlichia-induced liver injury and toxic shock |
title | MyD88-dependent inflammasome activation and autophagy inhibition contributes to Ehrlichia-induced liver injury and toxic shock |
title_full | MyD88-dependent inflammasome activation and autophagy inhibition contributes to Ehrlichia-induced liver injury and toxic shock |
title_fullStr | MyD88-dependent inflammasome activation and autophagy inhibition contributes to Ehrlichia-induced liver injury and toxic shock |
title_full_unstemmed | MyD88-dependent inflammasome activation and autophagy inhibition contributes to Ehrlichia-induced liver injury and toxic shock |
title_short | MyD88-dependent inflammasome activation and autophagy inhibition contributes to Ehrlichia-induced liver injury and toxic shock |
title_sort | myd88-dependent inflammasome activation and autophagy inhibition contributes to ehrlichia-induced liver injury and toxic shock |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5663626/ https://www.ncbi.nlm.nih.gov/pubmed/29049365 http://dx.doi.org/10.1371/journal.ppat.1006644 |
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