The team headed by Bruno Pitarddiscovers new concepts for the intracellular delivery of complex drugs including nucleic acids and proteins. the team contributed to more than 80 publications and 16 patents on nucleic acids and protein formulations. The mission of the team is to discover and optimize novel biotherapeutics to treat acquired or inherited diseases using the body capabilities to produce therapeutic proteins or antigens following the intracellular delivery by invented nanocarriers of recombinant and informative macromolecular drugs. To this end the global strategy followed by the team comes from the historical context in which the scientific activity of B. Pitard started in 1992 at the interface between chemistry and biology. The aim was to design and characterize supramolecular self-assembled systems with recombinant informative macromolecules (DNA, RNA, proteins). The original strategy designed by Bruno Pitard relies in the understanding of the relationships between the physicochemical properties of the supramolecular assemblies and their biological function. Usually the strategy which prevaled in this domain was mainly based on empirical approaches of trials and errors. By contrast, the strategy developed by B. Pitard allowed to (1) set up a rational approach to reconstitute membrane proteins into proteoliposomes, (2) identify for the first time the lamellar structure of DNA complexes with polycharged cationic lipids (Pitard et al. PNAS 1997, Pitard et al. PNAS 1999), (3) design novel classes of vectors with natural compounds (Desigaux et al PNAS 2007) and with amphiphilic block copolymers which lead not only to breakthrough supramolecular organizations but also dramatic improvement of nucleic acids delivery in vivo following various routes of administration including intramuscular, intralung and intraheart. Bruno’s team brought a key contribution in the development of this novel class of synthetic poylmer for the in vivo delivery of nucleic acids. In the period 2010-2015, Bruno’s team showed that amphiphilic block copolymers led to a key breakthrough delivery mechanism by the direct delivery of DNA molecules into the cytosol through the plasma membrane and not through the endosomes like observed with cationic lipids. Recently Bruno’s team showed for the first time as far as we know the intracellular delivery by lipoaminoglycosides of antibodies with functional activities in the field of channelopathies. All synthetic delivery systems Bruno developed for more than 20 years today allow overcoming technological barriers of the synthetic in vivo delivery of not only nucleic acids but also proteins including antibodies. One of the nanocarriers he invented is currently under GLP regulatory development for the future use in human to treat hepatocellular carcinoma by a nucleic acids-based vaccination approach. This regulatory development will also pave the path toward the use of this nanocarrier for other vaccine development such as the treatment of allergic asthma by anti-derf vaccination as we showed the proof of principle in a mouse model.
His present research activity is now focused in the understanding of the mechanism by which discovered synthetic nanocarriers improve dramatically the efficiency of nucleic acids based vaccines used for the development of prophylactic and therapeutic vaccines. Some of these nanocarriers present also self-adjuvant properties and we have obtained preliminary data in collaboration with F Altare and J. Lependu showing that artificial synthetic glycolipids constitutive of the carriers stimulate the proliferation and activate human iNKT cells and impact Treg cells in a model of in vitro granuloma. All these molecules could be of great interest and open a new field for the development of novel vaccines against enteric viruses. Therefore, after spending years in synthesizing and discovering novel classes of vectors to deliver DNA, his research activity is now more focused on the delivery of new breakthrough molecules mRNA for immune-prophylaxis and also on the understanding of the consequence of delivery of DNA and mRNA inside cells with respect to their stimulation of the innate immunity.
Vaccination against rotavirus with broad spectrum
Knowing the drawbacks presented above of the two live vaccines presently licensed there is a need to design new approaches to develop vaccines that would not be restricted by HBGA polymorphisms. To this end, we will follow an approach that will NOT use live attenuated vaccines that require the binding of VP8* to carbohydrate to be internalized in cells in order to be active. Instead, we will use synthetic nanocarriers that do not need a specific recognition on cell surface to be internalized. Intracellular internalization is based on different physico-chemical processes depending on the synthetic nanocarriers. Therefore depending on the format of the molecule encoding the antigen of interest either mRNA or DNA, lipids or polymer nanocarriers will be used to stimulate innate immune responses related to RNA molecular sensors (TLR7/8) located in the endosomes or DNA molecular sensors (TBK1 and related) located in the cytosol of cells. In this program we will focus on the development of an mRNA vaccine. At its most basic level, a mRNA vaccine is a simple molecule of linear RNA that contains a gene encoding a viral protein (antigen) of interest, driven by a strong 5’UTR. It is inexpensive, robust, easy to produce and transport, amenable to facile modification and is essentially “off the shelf”. Despite all attempts made in this field to increase the antigen expression, the different improvements of nucleic acids based vaccines could not achieve stellar immunity in human patients. We now understand that crucial to a strong immune response is the “innate” effect of a vaccine. In other words, the vaccine needs to activate sensors in the body that set off an alarm and trigger an immediate “danger response”, much like what happens during the course of a viral infection. The activation of such a “danger response” is an essential step in creating a local environment conducive for proper deployment of immune cells against an invading pathogen. As such, an ideal vaccine formulation should not only deliver the target protein antigen, but also sufficiently activate the danger sensors in the body. One such breakthrough methodology is our nanocarriers + mRNA vaccine combination, developed through many years In preclinical models, one of our formulations has demonstrated a dramatic enhancement of target protein production, and works by an intracellular delivery mechanism that maximizes access of the vaccine to danger sensors in the body (current GLP tox development for future injection in Man). We expect that this part of our project, will pave the way for an effective and economical vaccine against rotavirus.