In green, cells called “lymphoid tissue inducers” which induce a local inflammation ; in red inflamed stromal cells; in blue macrophages. This process recapitulates inflammation after an infection or a wound in the sterile environment of the fetus, and leads to the recruitment of B and T cells, and to the construction of a lymph node.
A developing lymph node in a mouse fetus
Lymphoid cells and the tissue microenvironment interact to define health and immunity of the host.
Microbiota, lymphoid cells and stromal cells develop a crosstalk that allows maintaining homeostasis, organize defense, and resolve inflammation to restore tissue integrity. Deregulation of this crosstalk prolongs inflammation or prevents the healing process, resulting in chronic inflammatory pathologies. Our previous work has led us to define central actors among pro-inflammatory lymphoid and stromal cells (in collaboration with the team of Lucie Peduto, https://research.pasteur.fr/en/team/group-lucie-peduto/), and to identify components of the symbiotic microbiota that efficiently modulate immunity.
Immunity comes into mainly 3 types of effector responses directed against intracellular microbes and tumors, large parasites or extracellular microbes. These responses are orchestrated by dendritic cells (DCs) and regulated by T (helper) Th1, Th2 and Th17 cells. Three types of ILCs have recently been described that mimic the activity of Th cells and that are termed ILC1, ILC2 and ILC3. As ILCs act promptly upon infection and injury, and express large amounts of effector cytokines, it is expected that they play an important role early in the regulation of immune responses. To directly explore this hypothesis, we have generated a panel of transgenic mice that allow for the timed ablation of each individual subset of ILCs, without damage to other immune cells. As ILCs are also involved in inflammatory pathology in response to chronic injury and metabolic stress, we explore how ILCs can be manipulated to restore normal immune functions, and extend our findings to human disease.
The development, homeostasis and pathology of the host are influenced at many levels by the symbiotic microbiota. In particular, we have shown how microbiota regulates the activity of RORgt+ ILCs and T cells, in collaboration with the team of Ivo Boneca, https://research.pasteur.fr/en/team/biology-and-genetics-of-bacterial-cell-wall/). Large projects around the world aim at dissecting the impact of microbiota on human health. We focus on the study of specific bacterial compounds shown to affect the activity of ILCs, such as peptidoglycans recognized by the Nod1 and Nod2 innate receptors, and polysaccharides recognized by TLRs and MHC molecules. We explore the effect of these metabolites on the regulation of immune responses, as well as on the host nervous system that modulates immunity. We also explore the regulation of the microbiota composition and activity by RORgt+ pro-inflammatory cells and the different subsets of ILCs during homeostasis and inflammation. These studies are performed in collaboration with clinical and industrial partners interested in the development of health-efficient probiotics.
The integrative dialogue between the immune system and the nervous systems. The nervous system establishes an extensive network of sensors that not only inform the central nervous sytem of the state of the organism and perturbations to it, but also coordinates the actions of different systems. Both the immune and the nervous sytems integrate information and react to maintain homeostatis of the whole. We develop projects, in collaboration with the team of Pierre-Marie Lledo, https://research.pasteur.fr/en/team/perception-and-memory/), that aim to decipher the regulation of the immune system by the nervous system using cutting-edge neuron manipulation techniques, and in reverse, to measure the activity of the nervous system upon perturbations of the immune system, during the steady state interaction with the symbiotic microbiota, during infection and inflammation.
• 1996 : Ph.D. in Immunology , University of Lausanne, Switzerland, Giampetro Corradin's lab
• 1996-2003 : Postdoctoral fellow, Ludwig Institute for Cancer Research, Switzerland, H. Robson MacDonald's lab followed by Immunology Skirball Institute, New York, USA, Dan Littman's lab
• 2005-2009 : head of the Lymphoid Tissue Development lab, Pasteur Institute, Paris, France
• 2010 : appointed head of the Microenvironment & Immunity Unit, Pasteur Institute, Paris, France
• 2015 : chair of the Department of Immunology, Institut Pasteur, France
• 2016 : appointed Director of INSERM U1224
• Innovator Award (2014) and Breakthrough Award (2015), Kenneth Rainin Foundation
• Elected EMBO member, 2013
• Jacques Oudin Award, French Society of Immunology, 2013
• Pasteur Vallery-Radot Award, from the French National Library, 2012
• Georges Zermati Award, from the Fondation de France, 2011
• Grant from the Simone e Cino del Duca Foundation, Institut de France, 2010
Les super-pouvoirs de l’intestin.
Enquête de santé, France 5.
Nos bactéries et nous : un subtil équilibre.
Pour la science (French edition of Scientific American)
Aug 2015, Science
Oct 2010, Science