recrute

Our defence against pathogens relies on the complex and sophisticated orchestration of immune cells recruitment by external cues. However, although the capacity of cells to orient versus chemical gradients (chemotaxis) has long been identified, existing information on actual chemokines distribution in vivo is still very sparse. Moreover, mechanical cues as efficient players in immune cell orientation (mechanotaxis) have only recently been acknowledged, and their function and mechanisms remain largely unexplained. In this context, we propose here to investigate quantitatively the guidance mechanisms of immune cells by both mechanical and chemical cues. The first aim of the project will consist in developing novel in vitro assays to study the main T cell recruitments events at the single cell level. A second aim will consist in using the novel assays of guided cell migration to study immune response failures during an infection in vivo and to explore potential prospects for medical diagnostic. In the first part of the project, we will develop quantitative in vitro tools to study the main events of leukocytes recruitment from the blood system (arrest and migration on the vessel walls, and transmigration through the endothelial layer). Mechanical guiding by hydrodynamic stress and space confinement will be studied in customized microfluidic chambers. Flow chambers with flow of changing direction coupled with magnetic/optical tweezers will allow investigation of guided migration versus an external force, whereas microfluidic chambers with porous walls mimicking extra-cellular matrix environment will enable the precise observation of the transmigration process. An important and original asset of this project relies on the novel opportunities offered by our collaboration with the company ALVEOLE in terms of surface treatment. ALVEOLE has developed a novel “protein printing” method that allows functional surface patterning with unprecedented spatial resolution and quantitative control. The protein printing methods will be adapted in this project to prepare substrates for immune cells migration, both on two- and three-dimensional micro-environments. Chemical guiding on flat surfaces (mimicking vessel walls) and confined environments (mimicking tissues) will be studied on surfaces or gels coated with patterns of adhesion proteins (e.g. ICAM, VCAM, E-selectins) and chemokines (e.g. CCL3-4-5, CXCL8-9-10). In the second part of the project, our novel quantitative assays will be used to tackle important bio-medical issues. We will attempt to decipher the chemokine cross-talk between dendritic cells and T cells at work in lymph node trafficking with Dr. M Bajenoff (CIML). We will also examine mechanisms of Bordatella pertussis infection, the causative agent of whooping cough, in collaboration with Pr. JP Gorvel (CIML). Our novel assays will be used to provide a more in-depth functional characterization of the immune response and will be used to assess the development of lasting immunological memory, and to predict effective protection against B. pertussis. This approach, once validated, may strengthen the range of technologies available for testing vaccine formulations in different animal and human models of disease. Finally, in collaboration with MDr. Phillipe Robert, we will explore the potential of our novel assays in the diagnosis and personalized treatment of inflammatory diseases. This exploratory project will be greatly facilitated by the LAI’s affiliation with the “Hopitâl de la Conception” in Marseille, which provides access to a vast library of clinical samples. Targeted pathologies will include leukocyte adhesion deficiency, multiple sclerosis (notably assessing anti-integrin therapies), atherosclerosis, and common variable immunodeficiency. This exploratory activity is critical for our industrial partner, ALVEOLE, who is actively looking for applications for their technologies in medicine and in particular, immunology.