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Accumulation of virulence-associated proteins in Campylobacter jejuni Outer Membrane Vesicles at human body temperature
Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
2019 (English)In: Journal of Proteomics, ISSN 1874-3919, E-ISSN 1876-7737, Vol. 195, p. 33-40Article in journal (Refereed) Published
Abstract [en]

Campylobacter jejuni is the major cause of bacterial gastroenteritis in humans. In contrast, colonization in avian hosts is asymptomatic. Body temperature differs between human (37 °C) and avian (42 °C) hosts, and bacterial growth in 37 °C is therefore a potential cue for higher virulence properties during human infection. The proteome of the bacteria was previously shown to be altered by temperature. Here we investigated whether temperature has an effect on the C. jejuni outer membrane vesicle (OMV) proteome, as OMVs are considered to be bacterial vehicles for protein delivery and might play a role during infection. OMVs isolated from C. jejuni strain 81-176 grown at 37 °C and 42 °C were analyzed by LC-ESI-MS/MS. 181 proteins were detected in both sample groups, one protein was exclusively present, and three were absent in OMVs from 37 °C. Of the 181 proteins, 59 were differentially expressed; 30 proteins were detected with higher abundance, and 29 proteins with lower abundance at 37 °C. Among the more highly abundant proteins, significantly more proteins were predicted to be associated with virulence. These data show that temperature has an impact on the property of the OMVs, and this might affect the outcome of colonization/infection by C. jejuni in different hosts.

Place, publisher, year, edition, pages
2019. Vol. 195, p. 33-40
Keywords [en]
Campylobacter jejuni, OMVs, Proteomics, Temperature
National Category
Microbiology
Research subject
Microbiology
Identifiers
URN: urn:nbn:se:umu:diva-155499DOI: 10.1016/j.jprot.2019.01.005ISI: 000459366000004PubMedID: 30641234OAI: oai:DiVA.org:umu-155499DiVA, id: diva2:1280435
Available from: 2019-01-18 Created: 2019-01-18 Last updated: 2019-04-16Bibliographically approved
In thesis
1. Host-pathogen interactions during Campylobacter and Yersinia infections
Open this publication in new window or tab >>Host-pathogen interactions during Campylobacter and Yersinia infections
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The innate immune system is known for protecting the host against invading pathogens, for instance enteropathogens infecting the gastrointestinal tract. The production of e.g. antimicrobial peptides, cytokines, and chemokines by innate immune cells and intestinal epithelial cells contribute to bacterial clearance. Given the significance of this system in overall defense, pathogens affect and/or manipulate immune cells and responses in favor of their own survival. This thesis focuses on how the Gram-negative enteropathogenic bacteria Yersinia pseudotuberculosis and Campylobacter jejuni affect the host, either directly via type 3 secretion system (T3SS) effector proteins or via outer membrane vesicles (OMVs), and how host factors potentially affect their virulence.

Yersinia pseudotuberculosis uses its T3SS to translocate virulence factors that disable various immune responses and subvert phagocytosis. Neutrophils are main target cells during Yersinia infection. They release granules that contain proteins with antimicrobial properties to the cell's exterior upon activation through a process called degranulation. We found that extracellular Y. pseudotuberculosis could prevent neutrophil degranulation upon cell contact. Prevention of degranulation was shown to be mediated via co-operative actions of the two anti-phagocytic Yersinia outer proteins YopH and YopE. Bacterial contact with neutrophils resulted in a transient inhibition of degranulation and further prevented degranulation upon subsequent contact with avirulent Y. pseudotuberculosis (lacking YopE and YopH) as well as Escherichia coli. Thus, Y. pseudotuberculosis impairs several neutrophil defense mechanisms to remain in the extracellular environment and to increase its survival during infection.

Campylobacter jejuni lacks a T3SS and appears to use OMVs and flagella as its main secretion apparatus. During passage through the intestine C. jejuni is exposed to bile, an important physiological component and part of the natural barrier of the intestine, and ability to resist bile is advantageous for C. jejuni survival. We investigated how C. jejuni OMV production and protein content is affected by bile. The main invasion and colonization of C. jejuni occurs in the lower part of the intestine where the concentration of bile is low compared with the proximal intestine. The OMV proteomic profiles were radically altered when bacteria were grown in low concentration of bile corresponding to cecal concentrations. Twenty-five present of the detected proteins of OMVs showed an altered abundance in the presence of low concentration of bile. In contrast, the overall proteome of the bacteria was unaffected. Moreover, OMVs frombile-exposed bacteria could enhance adhesion as well as invasion of bacteria into intestinal epithelial cells, suggesting a role of OMVs to the virulence of C. jejuni in the gut. The body temperature differs between the asymptomatic avian carriers of C. jejuni and humans, which develop symptomatic disease. We investigated whether the bacterial growth temperature affects the OMV proteome and found that 59 proteins were differentially expressed at 37°C. Among the higher abundant proteins, significantly more proteins were predicted to be related to virulence. Thus, temperature has an impact on the property of the OMVs, and this might affect the outcome of infection by C. jejuni in different hosts.

C. jejuni OMV interactions with innate immune cells were studied by analyses of OMV-mediated inflammasome activation. OMVs were found to induce ASC- and caspase-1-dependent inflammasome activation in murine and human macrophages and dendritic cells as well as in human neutrophils. While C. jejuni infection induced a low level of inflammasome-dependent cell death, OMV-induced inflammasome activation did not result in cell death. Thus, OMVs disseminate into tissue without bacteria can be a vehicle for virulence factors without inducing inflammatory cell death.

Place, publisher, year, edition, pages
Umeå: Umeå University, 2019. p. 79
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 2005
Keywords
Campylobacter jejuni, Yersinia pseudotuberculosis, OMV, bile, temperature, proteomic
National Category
Biochemistry and Molecular Biology Microbiology Immunology
Identifiers
urn:nbn:se:umu:diva-155504 (URN)978-91-7855-003-6 (ISBN)
Public defence
2019-02-15, Hörsal D Unod T9, NUS, Umeå, 09:00 (English)
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Supervisors
Available from: 2019-01-25 Created: 2019-01-18 Last updated: 2019-01-29Bibliographically approved

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Taheri, NayyerFällman, MariaWai, Sun NyuntFahlgren, Anna

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