Proteomics represent a powerful tool for the understanding of complex biological mechanisms. Taking advantage of the great improvements in large-scale proteomic analysis of complex samples, we use state-of-the-art mass spectrometry techniques to bring new insights in the molecular mechanisms of the inflammatory and immune responses in specific cellular systems such as endothelial or different types of immune cells.
In collaboration with the team of J-P Girard (Vascular Biology: Endothelial cells, Inflammation and Cancer), we applied proteomic approaches to address several biological questions about endothelial cells (ECs) and inflammatory processes in the endothelium. Our group has been involved in the characterization of new proteins identified in specialized ECs from high endothelial venules (HEVs), which play critical roles in inflammatory diseases and are responsible for lymphocytes recruitment to lymphoid organs and to inflamed tissues. Using strategies based on affinity purification coupled to mass spectrometry (AP-MS), we could identify new specific partners of the THAP-zinc finger family of transcription factors, which plays a key role in endothelial cells proliferation. We also used mass spectrometry to study the functional mechanisms and maturation process of the IL-1-like cytokine IL-33/NF-HEV, and map the cleavage sites that are used by neutrophil proteases to generate “superactive” forms of IL-33. Finally, we are also interested in developing global proteomics strategies associated with label-free quantification to study the pathways and processes activated in ECs under inflammatory conditions. Quantitative proteomic analysis was performed both on the glycoproteome of ECs, through the establishment of a method for cell surface proteome enrichment, or on total ECs lysates, through the implementation of sample pre-fractionation strategies for deep proteome coverage. Using such methods, we could extensively map the ECs proteome, and provided the most complete proteomic characterization to date of the human EC response to several inflammatory cytokines, such as TNFα, IFNg, IL1β, and IL-33.
Another field of our research areas is to decipher, at the cellular and molecular levels, the functional mechanisms of T lymphocytes using proteomic approaches. In collaboration with teams bringing complementary expertise in immunopathology and T cell signaling (A. Saoudi, CPTP, Toulouse; B. Malissen, CIML, Marseille), we are currently involved in the detailed characterization of the T Cell Receptor (TCR) pathway, by analyzing the signalosome of several key components of this complex system using optimized AP-MS strategies. Our studies also aim at providing an in-depth characterization of the molecular events in specific sub-populations of T cells, such as regulatory T cells (Tregs) that play a central role in preventing pathological immune responses including autoimmunity, inflammation and allergy.