Bruno Lemaître’s pioneering work on the innate immune system of Drosophila has paved the way to a better understanding of evolutionarily conserved defence mechanisms that are similar in both insects and mammals, such as humans.

Innate immunity versus adaptive immunity

Through evolution, animals and plants have inherited an innate, ancestral immune system that can recognise the major families of pathogens. It is our first line of defence. This rapid response can eliminate intruders and trigger an inflammatory response.

In vertebrates, when pathogens cross this first barrier, the adaptive immune system is activated. Its strength lies in its ability to adapt to the rapid evolution of different microbes by mobilising specific antibodies and memorise the various aspects of this immune response so that it can react more rapidly in the event of future encounters with the same intruder.

How does our immune system distinguish between infectious agents and harmless intruders? Since the adaptive system is not able to make this distinction, this mission must fall to the innate system.

Toll-like receptors and the elucidation of innate immunity mechanisms

In 1996, Bruno Lemaître and Jules Hoffmann discovered that, in Drosophila, the innate system uses Toll-like receptors to respond to fungal infections. These receptors help to identify the aggressor and trigger an appropriate antimicrobial response. The first human Toll-like receptor was discovered in 1997. Bruno Lemaître was also involved in the identification of a second innate immune pathway in Drosophila, the IMD (immune deficiency) pathway, which responds more specifically to infections caused by Gram-negative bacteria.

Contrary to popular belief, Bruno Lemaître demonstrated that the innate immune system’s response is not aspecific, but rather adapts to the pathogens encountered.

These findings have not only provided an understanding of the mechanisms of resistance or susceptibility to infection, but have also opened a wide range of therapeutic possibilities: vaccines, immunotherapy for cancer, treatment of autoimmune diseases, etc.

Symbiosis between the intestinal microbiota and the immune system

Another element of our immune barrier, found inside the body, are the vast number of bacteria that make up our microbiota. It plays a major role in the maturation of our immune system, which, for its part, influences the microbiota’s bacterial composition.

Bruno Lemaître and his team were awarded the Liliane Bettencourt Prize for Life Sciences so that they could examine the defence mechanisms of the intestinal epithelium and, more broadly, the homeostasis of the digestive tract.

Using Drosophila as a model, the researchers were able to demonstrate the role played by intestinal stem cells in repairing the digestive tract in the event of bacterial infection.

It is essential for our health that the immune system and the microbiota interact harmoniously, as any imbalance can cause disease, such as diabetes, cancer and cardiovascular disease.

Bruno Lemaître in a few words

Holder of a PhD in Genetics, Bruno Lemaitre joined Jules Hoffmann’s laboratory at the Institute of Genetics and Molecular and Cellular Biology in Strasbourg. In 1996, he made his mark in immunological history when he discovered that Toll-like receptors play an essential role in the innate immune response in Drosophila. As a result of this seminal work, Toll-like receptors were identified as mediators of innate immunity in humans.

He subsequently debunked the scientific dogma that innate immunity is aspecific, by demonstrating that in Drosophila, this system activates a distinct response according to the pathogen encountered.

Supported by the Fondation Bettencourt Schueller after receiving the Bettencourt Prize Coups d'élan pour la recherche française in 2003, and the Liliane Bettencourt Prize for Life Sciences in 2010, Bruno Lemaître has continued to conduct research on Drosophila at the Institute of Infectiology of the École Polytechnique Fédérale de Lausanne, and started work on exploring the symbiotic relationship between the intestinal microbiota and the immune system.

  • 1992 PhD in Genetics, Pierre et Marie Curie University, Paris

  • 1992 CNRS Researcher, Institute of Genetics and Molecular and Cellular Biology, Strasbourg

  • 1998 Director of the Host-Pathogen Interactions and Innate immunity in Drosophila Research Team, Center for Molecular Genetics, Gif-sur-Yvette

  • 2003 William B. Coley Award for Fundamental Research in Immunology, American Cancer Research Institute

  • 2003 Bettencourt Prize Coups d'élan pour la recherche française

  • 2007 Full Professor, Laboratory Director, Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (Switzerland)

  • 2010 Liliane Bettencourt Prize for Life Sciences

Bettencourt Prize Coups d'Élan pour la recherche française

The Bettencourt Prize Coups d'Élan pour la recherche française was created by the Foundation in 2000. It has rewarded 78 French laboratories and more than 900 researchers have benefited from this prize. Until 2021, this prize was awarded each year to four research teams, from Inserm and the CNRS Institute of Biological Sciences. The amount of the prize endowment was 250,000 euros per laboratory.

All the award-winners

Liliane Bettencourt Prize for Life Sciences

The Liliane Bettencourt Prize for Life Sciences rewards each year a researcher under the age of 45 for the excellence of their work and their remarkable contribution to their field of scientific research. This prize is awarded, depending on the year, to a researcher based in France or working in another European country. Thirty winners have been awarded since 1997. From 2023, prize rewards the laureate up to 100,000 euros.

All the award-winners