Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Blood-brain barrier-restricted translocation of Toxoplasma gondii from cortical capillaries
Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.ORCID iD: 0000-0002-0179-4880
Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.ORCID iD: 0000-0001-9959-6470
Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.ORCID iD: 0000-0002-5973-1241
Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.ORCID iD: 0000-0001-7746-9964
Number of Authors: 42021 (English)In: eLIFE, E-ISSN 2050-084X, Vol. 10, article id e69182Article in journal (Refereed) Published
Abstract [en]

The cellular barriers of the central nervous system proficiently protect the brain parenchyma from infectious insults. Yet, the single-celled parasite Toxoplasma gondii commonly causes latent cerebral infection in humans and other vertebrates. Here, we addressed the role of the cerebral vasculature in the passage of T. gondii to the brain parenchyma. Shortly after inoculation in mice, parasites mainly localized to cortical capillaries, in preference over post-capillary venules, cortical arterioles or meningeal and choroidal vessels. Early invasion to the parenchyma (days 1-5) occurred in absence of a measurable increase in blood-brain barrier (BBB) permeability, perivascular leukocyte cuffs or hemorrhage. However, sparse focalized permeability elevations were detected adjacently to replicative parasite foci. Further, T. gondii triggered inflammatory responses in cortical microvessels and endothelium. Pro- and anti-inflammatory treatments of mice with LPS and hydrocortisone, respectively, impacted BBB permeability and parasite loads in the brain parenchyma. Finally, pharmacological inhibition or Cre/loxP conditional knockout of endothelial focal adhesion kinase (FAK), a BBB intercellular junction regulator, facilitated parasite translocation to the brain parenchyma. The data reveal that the initial passage of T. gondii to the central nervous system occurs principally across cortical capillaries. The integrity of the microvascular BBB restricts parasite transit, which conversely is exacerbated by the inflammatory response.

Place, publisher, year, edition, pages
2021. Vol. 10, article id e69182
Keywords [en]
apicomplexa, blood-brain barrier, CNS infection, Toxoplasma gondii, biological barriers, inflammation, Mouse
National Category
Biological Sciences
Identifiers
URN: urn:nbn:se:su:diva-201404DOI: 10.7554/eLife.69182ISI: 000734653800001PubMedID: 34877929OAI: oai:DiVA.org:su-201404DiVA, id: diva2:1635950
Available from: 2022-02-08 Created: 2022-02-08 Last updated: 2023-04-17Bibliographically approved
In thesis
1. Transmigration of Toxoplasma gondii across biological barriers
Open this publication in new window or tab >>Transmigration of Toxoplasma gondii across biological barriers
2022 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Toxoplasma gondii is an obligate intracellular parasite that can likely infect all warm-blooded vertebrates, with estimates of up to 30% of the global human population being infected. Although infection with T. gondii is usually asymptomatic or mild, in immunocompromised individuals infection can lead to lethal toxoplasmic encephalitis. Infection acquired during pregnancy can also lead to serious ocular or neurological damage and even death of the foetus. Following ingestion, the parasite is able to cross the first biological barrier it encounters, the gut epithelium and convert to the rapidly replicating tachyzoite stage. It can then disseminate throughout the body of the host, eventually reaching sites such as the brain, after crossing the blood-brain barrier (BBB). Previous findings have shown that T. gondii can use leukocytes, such as dendritic cells (DCs), for dissemination via a “Trojan horse”-type mechanism, but how T. gondii then crosses restrictive barriers such as the BBB is still not fully understood. The overall objective of this work has been to investigate how T. gondii crosses biological barriers and how infection impacts host cell signalling.

In paper I we demonstrate that T. gondii can cross polarised cell monolayers without significantly perturbing barrier integrity. Reduced phosphorylation of focal adhesion kinase (FAK) was observed in cell monolayers upon T. gondii challenge, and inhibition or gene silencing of FAK (Ptk2) facilitated transmigration of T. gondii across polarised cell monolayers. In paper II we found that upon T. gondii infection of DCs, secreted TIMP-1 induces hypermotility by activating β1 integrin-FAK signalling through interactions with CD63. In paper III we show that T. gondii can cross polarised endothelial cell monolayers inside DCs. We also report that parasitised DCs on endothelium do not display a hypermotile phenotype, switching to integrin-dependent motility. Blockade of β1 and β2 integrins or ICAM-1, and gene silencing of β1 (Itgb1) or talin (Tln1) restored infected-DC motility, and reduced the frequency of transmigration of T. gondii-challenged DCs across endothelium. In paper IV we demonstrate that, shortly after T. gondii inoculation in mice, parasites mainly localised to cortical capillaries of the brain. Early invasion to the brain parenchyma occurred in absence of a significant increase in BBB permeability, perivascular leukocyte cuffs or haemorrhage. Further, pharmacological inhibition or endothelial cell-specific knockout of FAK facilitated parasite transmigration to the brain parenchyma.

In paper V we report that DCs challenged with type II T. gondii transmigrate across polarised endothelial cell monolayers at a higher frequency than type I T. gondii, while type I infected DCs exhibited increased migratory velocities on endothelium. We also show that T. gondii-induced upregulation of ICAM-1 in DCs is genotype-dependent, and requires the T. gondii secreted effector GRA15. Finally, gene silencing of leukocyte ICAM-1 (Icam-1) or deletion of T. gondii GRA15 reduced transmigration across endothelial cell monolayers.

In summary, the work in this thesis provides novel insights into how T. gondii can potentially cross biological barriers on its journey to the brain. We find that T. gondii can cross polarised monolayers both as free parasites and using DCs as a “Trojan horse”, and identify new ways in which T. gondii can alter host cell dynamics to benefit its own dissemination.

Place, publisher, year, edition, pages
Stockholm: Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 2022. p. 27
Keywords
Apicomplexa, blood-brain barrier, leukocyte, immune cell, transendothelial migration, cell adhesion molecule, host-pathogen, FAK, integrin
National Category
Microbiology Cell Biology Immunology
Research subject
Molecular Bioscience
Identifiers
urn:nbn:se:su:diva-204118 (URN)978-91-7911-862-4 (ISBN)978-91-7911-863-1 (ISBN)
Public defence
2022-06-09, Vivi Täckholmsalen (Q-salen) NPQ-huset, Svante Arrhenius väg 20, Stockholm, 09:30 (English)
Opponent
Supervisors
Available from: 2022-05-17 Created: 2022-04-26 Last updated: 2022-05-02Bibliographically approved

Open Access in DiVA

No full text in DiVA

Other links

Publisher's full textPubMed

Authority records

Olivera, Gabriela CarinaRoss, Emily CharlottePeuckert, ChristianeBarragan, Antonio

Search in DiVA

By author/editor
Olivera, Gabriela CarinaRoss, Emily CharlottePeuckert, ChristianeBarragan, Antonio
By organisation
Department of Molecular Biosciences, The Wenner-Gren Institute
In the same journal
eLIFE
Biological Sciences

Search outside of DiVA

GoogleGoogle Scholar

doi
pubmed
urn-nbn

Altmetric score

doi
pubmed
urn-nbn
Total: 42 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf