Voltage-dependent calcium channel signaling mediates GABAA receptor-induced migratory activation of dendritic cells infected by Toxoplasma gondii

PLoS Pathog. 2017 Dec 7;13(12):e1006739. doi: 10.1371/journal.ppat.1006739. eCollection 2017 Dec.

Abstract

The obligate intracellular parasite Toxoplasma gondii exploits cells of the immune system to disseminate. Upon T. gondii-infection, γ-aminobutyric acid (GABA)/GABAA receptor signaling triggers a hypermigratory phenotype in dendritic cells (DCs) by unknown signal transduction pathways. Here, we demonstrate that calcium (Ca2+) signaling in DCs is indispensable for T. gondii-induced DC hypermotility and transmigration in vitro. We report that activation of GABAA receptors by GABA induces transient Ca2+ entry in DCs. Murine bone marrow-derived DCs preferentially expressed the L-type voltage-dependent Ca2+ channel (VDCC) subtype Cav1.3. Silencing of Cav1.3 by short hairpin RNA or selective pharmacological antagonism of VDCCs abolished the Toxoplasma-induced hypermigratory phenotype. In a mouse model of toxoplasmosis, VDCC inhibition of adoptively transferred Toxoplasma-infected DCs delayed the appearance of cell-associated parasites in the blood circulation and reduced parasite dissemination to target organs. The present data establish that T. gondii-induced hypermigration of DCs requires signaling via VDCCs and that Ca2+ acts as a second messenger to GABAergic signaling via the VDCC Cav1.3. The findings define a novel motility-related signaling axis in DCs and unveil that interneurons and DCs share common GABAergic motogenic pathways. T. gondii employs GABAergic non-canonical pathways to induce host cell migration and facilitate dissemination.

MeSH terms

  • Adoptive Transfer
  • Animals
  • Calcium Channels, L-Type / immunology*
  • Calcium Signaling*
  • Cell Movement
  • Cells, Cultured
  • Dendritic Cells / immunology*
  • Dendritic Cells / parasitology
  • GABA Agents / immunology
  • Mice
  • Mice, Inbred C57BL
  • Receptors, GABA-A / immunology*
  • Toxoplasma / immunology*
  • Toxoplasma / physiology
  • Toxoplasmosis / immunology*
  • Toxoplasmosis / parasitology
  • gamma-Aminobutyric Acid / immunology

Substances

  • Cacna1d protein, mouse
  • Calcium Channels, L-Type
  • GABA Agents
  • Receptors, GABA-A
  • gamma-Aminobutyric Acid

Grants and funding

Funding was received from Vetenskapsrådet/ The Swedish Research Council, grant K2014-56X-15133-11-6 to AB (http://www.vr.se) and from Vetenskapsrådet /EU ERA-net Neuron, grant VR/2014-7533 to AB (http://www.neuron-eranet.eu). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.