Mechanisms of T cell migration and interactions in the tumor microenvironment

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Summary

The project will use intravital two-photon microscopy to determine the molecules involved in interstitial T cell migration and the molecular mechanisms of T cell interactions with tumour cells.

Supervisor(s)

Professor Wolfgang Weninger

Research Location

Camperdown - Centenary Institute

Program Type

Masters/PHD

Synopsis

Tumour cell-host cell interactions are critical determinants for the progression of neoplasms. Of particular importance are cytotoxic T cells, as they may recognise and destroy tumour cells. How T cells navigate within the tumour microenvironment, how they interact with neoplastic cells, as well as their overall contribution to the tumour micromilieu is not well understood. The project’s long-term goal is to define the cellular and molecular cues responsible for the guidance of tumour infiltrating T cells (TIL) through the tumour stroma, and mediation of their communication with neoplastic cells. We hypothesise that the quality of TIL migration and interactions with target cells determines whether a tumour is destroyed or grows unimpeded. To test our hypothesis, we will employ a newly-developed two-photon microscopy model that facilitates visualisation of the behaviour of single cells in real-time within the intricate three-dimensional context of intact tumours. Based on our discovery that migrating TIL are polarised and interact with extracellular matrix (ECM) fibres, we will explore the role of CD44, a receptor for ECM molecules, in TIL migration within the tumour stroma (Subaim 1a). In Subaim 1b, we will determine how Scribble, a master regulator of T cell polarisation, regulates TIL locomotion and anti-tumour immune responses. We have further observed that TIL undergo long-lasting, physical interactions with tumour cells. In Aim 2 we will determine the molecular composition of the T cell-tumour cell interface. Subaim 2a will decipher whether immunologic synapses form during TIL-tumour cell interactions, and what molecules are involved in this process. Subaim 2b will ask whether cytotoxic granules are released during TIL-tumour cell interactions, and will elucidate the dynamics of this process. Our experiments will provide mechanistic insights into the events leading to tumour cell destruction or tumour immune evasion. Therefore, these studies have important implications for the optimisation of immuno-therapeutic strategies that aim to target cancer.

Additional Information

Techniques: The project will employ intravital two-photon microcopy. This emerging imaging technology facilitates visualisation of fluorescently-tagged cells and molecules deep within intact tissues. In addition, it allows us to visualize extracellular matrix fibres using an optical phenomenon called second harmonic generation. This is extremely helpful to track migrating cells in the extracellular space. For the purpose of our studies, we will tag certain molecules, such as adhesion receptors with fluorescent markers, such as GFP, and then transduce effector T cells with retroviral constructs. This enables imaging of such molecules at subcellular resolution in vivo. Thus we can study, for example, how lytic synapses between TIL and tumour cells form in vivo. We are currently setting up a cutting-edge two-photon microscope at the Centenary Institute. We are implementing some novel features, such as high wave-lengths imaging options that not only allow for even higher tissue penetration, but also will also help to highlight ECM fibres at a resolution that has not been reached before. In addition, we will also have a high speed imaging option that allows for video frame rate acquisition of images. Thus, we can visualise fast moving objects, for example, cells in the blood stream. Together, this will be Australia’s first two-photon imaging facility dedicated to study immune cells behaviour in vivo. Funding: Our laboratory is currently funded by grants from the National Institutes of Health (NIH, USA) and a Life Science Research Award from NSW. At the moment, we also have 3 NHRMC grants pending. Potential PhD projects:

  1. Related to this project: Define interactions between TIL and tumour cells at the molecular level in vivo. This includes
    • the kinetics of formation and the molecular composition of the lytic synapse, and
    • the kinetics and geometry of lytic granule release from TIL.
  2. Other projects in the lab:
    • Characterise the behaviour of innate immune cells in the skin in response to infectious agents (H. simplex, L. major) and UV irradiation using 2-photon microscopy
    • Study the role of T cell receptor affinity on T cell activation during influenza virus infection. This study combined 2-photon microscopy and standard immunological techniques with a pair of transgenic mice whose TCRs are specific for influenza hemagglutinin

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Keywords

tumours, tumour immunity, adoptive transfer, immunotherapy, T cells, migration, two-photon microscopy, extracellular matrix, immunologic (lytic) synapse, lytic granules, Cancer & leukaemia, Cell biology, Infection & immunity

Opportunity ID

The opportunity ID for this research opportunity is: 209

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