PDP2019-04

Deciphering chemical signals guiding T cells towards and in lymph node

Abstract

Lymphocytes CD8+ and CD4+ T cells have a crucial role in resistance to pathogens and can kill malignant cells. Activation of these lymphocyte subsets involves recognition of antigens presented by dendritic cells (DCs), but the frequencies of such antigen-bearing cells early in an infection and of the relevant naive T cells are both low. This suggests that an active mechanism facilitates the necessary cell–cell associations. Within lymphoid organs, chemokines are believed to diffuse locally before being captured on extracellular matrix components present on the surface of architectural stromal cells. As lymphocytes crawl on the same stromal cells, this physical gradient of chemokines is thought to control their migration and direction in vivo by haptotaxis. We propose here to combine in vivo imaging and quantitative in vitro approaches to decipher chemical signals guiding T cells towards and in lymph node.

Keywords

Chemotaxis, lymph node traffic, microenvironnement, quantitative reductionist approaches, microfluidics, protein printing.

Objectives

-Develop innovative microfabricated tools to control chemical gradients (microfluidics and protein printing)

-Prepare and isolate sub-sets of DC and T cell in mice to characterize their interplay migration in vitro

-Identify and decipher biochemical signals guiding cells in lymph node

-Track and model the chemotactic phenotypes in a multicellular population of immune cells

Proposed approach

The multicellular systems of interest imply different sub-sets of dendritic cells, T cells and stromal cells that will be prepared at CIML on mice models. The isolated cells will then be exposed to controlled in vitro microenvironments prepared by a combination of microfluidics and protein printing. Analysis of multicellular phenotypes in 2D and 3D versus the spatiotemporal stimuli of biochemical signals emitted by companion cells and/or a diffused by a controlled source will require advanced image analysis routines. An important modeling effort will then be instrumental to interpret the intercellular behavior as well as the intracellular signaling machinery accessible by use of biosensor.

 

Interdisciplinarity

This project combines the expertise in immunology of Marc Bajenoff, which studies lymph node trafficking by in vivo imaging, the expertise in biophysics of Olivier Theodoly, which develops quantitative in vitro approaches to decipher biological mechanisms, and the expertise of Paul Villoutreix in image data analysis. The project implies pure immunology concerning the step of cell preparation/isolation for in vitro assays and the step of in vivo imaging to validate in vitro quantitative results in animal model. The project also implies a strong aspect of biotechnological and biophysical developments to design and perform in vitro assays. Computing expertise will then be essential to track and analyze 3D migratory characteristics of multicellular system. Finally modeling will be important to interpret multicellular interactions and phenotypes.

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