DR. Bruno Lemaitre
Brief Biography: I obtained my PhD in 1992 with Dario Coen at the University Pierre and
Marie Curie (Paris) while studying mechanisms of P element transposition in Drosophila.
Next, I joined the laboratory of Jules Hoffmann (CNRS, Strasbourg, France) as a research
associate where I analysed the role of the Toll and Imd genes in the Drosophila immune
response. In 1998, I started my own lab at the Centre Génétique Moléculaire (Gif-surYvette, France).
Awards 1998 : ATIPE CNRS 2000 : Young Investigator Program (EMBO) 2001 : Prize Noury,
Thorlet, Lazare from the French Academy of Sciences (personal prize) 2002 : First Prize of
the Schlumberger Foundation 2003: William B. Coley Award for distinguished research in
basic and tumor immunology (American Cancer Research Institute) (personal prize) 2004:
Award from the Bettencourt-Schueller Foundation
Major discoveries
In 1993, I joined Jules Hoffmann’s group at the University of Strasbourg. His laboratory
was working on insect immune responses using molecular and biochemical approaches. I
initiated the first genetic studies of insect immunity in order to elucidate the mechanisms
that regulate antimicrobial peptide gene expression.
- immune deficiency and the antibacterial response pathway (Lemaitre et al. 1995, Proc.
Natl. Acad. Sci. USA 92:9465-9469) I identified the first Drosophila mutation, immune
deficiency (imd), that blocks both the expression of the genes that encode antibacterial
peptides and confers high susceptibility to bacterial infection. This mutation defines a
novel signaling pathway regulating Drosophila antibacterial responses.
Toll and the antifungal response pathway (Lemaitre et al., 1996, Cell 86:973-983) I
demonstrated that the Toll signaling cascade that was known to regulate the NF-kB factor,
Dorsal, during embryonic development, also regulates Drosophila antimicrobial responses.
Our demonstration of Toll function in the antifungal immune response provided the first
evidence that Toll receptors play an important role in animal host defence.
-Specificity of Drosophila immune responses (Lemaitre et al., 1997 Proc. Natl. Acad. Sci.
USA 94: 14614-619) By using different bacteria and fungi, I revealed Drosophila’s ability
to differentiate between pathogens and mount specific immune responses through the
selective activation of either the Imd or Toll pathways. This work demonstrated that
pathogen recognition leads to specific innate immune responses when Pattern recognition
receptors are coupled to distinct signaling cascades.
These three studies sets the basis of the Toll and Imd model which still exerts a strong
influence on the innate immunity field. A Perspective “The road to Toll” describing these
studies will appear in July 2004 in Nature Review Immunology.
Since 1998, my team has continued these studies by the isolation of new components of
the Imd and Toll pathways; by the characterization of the bacterial determinants that
trigger the Toll and Imd pathways; by the identification of the first bacterial species that
infects Drosophila via natural routes; and by extensive genomic analysis of Drosophila
immune responses.
Impact of these studies My demonstration that Toll regulated Drosophila immune
responses through a conserved signaling cascade inspired a search for mammalian Toll
like proteins that also mediate host defense reactions. Medzhitov and Janeway, who were
linked to the Hoffmann lab through a Human Frontiers Grant, were the first, in 1997, to
implicate a Toll-related protein (TLR) in the activation of mammalian immune response
(Nature 388:394-397). Subsequently, a series of remarkable studies demonstrated the
crucial role of mammalian TLRs in the regulation of NF-_B, a central mediator of the
mammalian innate immunity, in response to several microbial elicitors. For example, mice
deficient for TLR4, TLR2 or TLR9 do not respond to Lipopolysaccharides, Peptidoglycans
and bacterial DNA respectively. TLRs are now the focus of intense research. Therefore,
our study has strongly stimulated the field of innate immunity and demonstrated the power
of Drosophila as a model for dissecting these processes