Infection by Toxoplasma gondii Induces Amoeboid-Like Migration of Dendritic Cells in a Three-Dimensional Collagen Matrix

PLoS One. 2015 Sep 25;10(9):e0139104. doi: 10.1371/journal.pone.0139104. eCollection 2015.

Abstract

Toxoplasma gondii, an obligate intracellular parasite of humans and other warm-blooded vertebrates, invades a variety of cell types in the organism, including immune cells. Notably, dendritic cells (DCs) infected by T. gondii acquire a hypermigratory phenotype that potentiates parasite dissemination by a 'Trojan horse' type of mechanism in mice. Previous studies have demonstrated that, shortly after parasite invasion, infected DCs exhibit hypermotility in 2-dimensional confinements in vitro and enhanced transmigration in transwell systems. However, interstitial migration in vivo involves interactions with the extracellular matrix in a 3-dimensional (3D) space. We have developed a collagen matrix-based assay in a 96-well plate format that allows quantitative locomotion analyses of infected DCs in a 3D confinement over time. We report that active invasion of DCs by T. gondii tachyzoites induces enhanced migration of infected DCs in the collagen matrix. Parasites of genotype II induced superior DC migratory distances than type I parasites. Moreover, Toxoplasma-induced hypermigration of DCs was further potentiated in the presence of the CCR7 chemotactic cue CCL19. Blocking antibodies to integrins (CD11a, CD11b, CD18, CD29, CD49b) insignificantly affected migration of infected DCs in the 3D matrix, contrasting with their inhibitory effects on adhesion in 2D assays. Morphological analyses of infected DCs in the matrix were consistent with the acquisition of an amoeboid-like migratory phenotype. Altogether, the present data show that the Toxoplasma-induced hypermigratory phenotype in a 3D matrix is consistent with integrin-independent amoeboid DC migration with maintained responsiveness to chemotactic and chemokinetic cues. The data support the hypothesis that induction of amoeboid hypermigration and chemotaxis/chemokinesis in infected DCs potentiates the dissemination of T. gondii.

MeSH terms

  • Animals
  • Antibodies, Blocking / pharmacology
  • Bystander Effect / drug effects
  • Cattle
  • Cell Adhesion / drug effects
  • Cell Movement / drug effects*
  • Cell Shape / drug effects
  • Chemokine CCL19 / pharmacology
  • Collagen / pharmacology*
  • Dendritic Cells / cytology
  • Dendritic Cells / drug effects
  • Dendritic Cells / parasitology*
  • Humans
  • Integrins / metabolism
  • Mice
  • Phenotype
  • Toxoplasma / physiology*
  • Toxoplasmosis / pathology*

Substances

  • Antibodies, Blocking
  • Chemokine CCL19
  • Integrins
  • Collagen

Grant support

Funding was provided by Vetenskapsrådet (Swedish Research Council), http://www.vr.se/inenglish.4.12fff4451215cbd83e4800015152.html.