Visualizing context-dependent calcium signaling in encephalitogenic T cells in vivo by two-photon microscopy

Nikolaos I. Kyratsous, Isabel J. Bauer, Guokun Zhang, Marija Pesic, Ingo Bartholomäus, Marsilius Mues, Ping Fang, Miriam Wörner, Stephanie Everts, Joachim W. Ellwart, Joanna M. Watt, Barry V.L. Potter, Reinhard Hohlfeld, Hartmut Wekerle, Naoto Kawakami

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

In experimental autoimmune encephalitis (EAE), autoimmune T cells are activated in the periphery before they home to the CNS. On their way, the T cells pass through a series of different cellular milieus where they receive signals that instruct them to invade their target tissues. These signals involve interaction with the surrounding stroma cells, in the presence or absence of autoantigens. To portray the serial signaling events, we studied a T-cell–mediated model of EAE combining in vivo two-photon microscopy with two different activation reporters, the FRET-based calcium biosensor Twitch1 and fluorescent NFAT. In vitro activated T cells first settle in secondary (2°) lymphatic tissues (e.g., the spleen) where, in the absence of autoantigen, they establish transient contacts with stroma cells as indicated by sporadic short-lived calcium spikes. The T cells then exit the spleen for the CNS where they first roll and crawl along the luminal surface of leptomeningeal vessels without showing calcium activity. Having crossed the blood–brain barrier, the T cells scan the leptomeningeal space for autoantigen-presenting cells (APCs). Sustained contacts result in long-lasting calcium activity and NFAT translocation, a measure of full T-cell activation. This process is sensitive to anti-MHC class II antibodies. Importantly, the capacity to activate T cells is not a general property of all leptomeningeal phagocytes, but varies between individual APCs. Our results identify distinct checkpoints of T-cell activation, controlling the capacity of myelin-specific T cells to invade and attack the CNS. These processes may be valuable therapeutic targets.

Original languageEnglish
Pages (from-to)E6381-E6389
JournalProceedings of the National Academy of Sciences of the United States of America
Volume114
Issue number31
Early online date17 Jul 2017
DOIs
Publication statusPublished - 1 Aug 2017

Keywords

  • Autoimmunity
  • Central nervous system
  • Intracellular calcium
  • T-cell activation
  • two-photon imaging

ASJC Scopus subject areas

  • General

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    Kyratsous, N. I., Bauer, I. J., Zhang, G., Pesic, M., Bartholomäus, I., Mues, M., Fang, P., Wörner, M., Everts, S., Ellwart, J. W., Watt, J. M., Potter, B. V. L., Hohlfeld, R., Wekerle, H., & Kawakami, N. (2017). Visualizing context-dependent calcium signaling in encephalitogenic T cells in vivo by two-photon microscopy. Proceedings of the National Academy of Sciences of the United States of America, 114(31), E6381-E6389. https://doi.org/10.1073/pnas.1701806114