Our team has a long-standing interest in vascular cell biology in the context of infection, inflammation or cancer. A wide range of pathogens directly targets peripheral and brain endothelial cells. Among those, Neisseria meningitidis (meningococcus) is still a leading cause of two rare but devastating invasive diseases, meningitis and severe form of sepsis (purpura fulminans). We have developed interdisciplinary approaches to elucidate the intricate network of interactions and molecular strategies selected by this bacterial pathogen to colonize human peripheral and brain vasculatures to get access to the brain. We are deciphering the molecular and cellular events leading to vascular dysfunction, thrombosis, organ failure and immune escape by this pathogen. Our original findings led to the discovery of innovative therapeutic compounds against meningococcal diseases. We also uncovered an original allosteric mechanism controlling the activity of tyrosine kinase receptor ErbB2/HER2 involved in 25-30% of all breast cancer and identified new HER2 inhibitors. We are now defining new diagnostic and prognostic biomarkers for HER2-positive breast cancers, and we develop innovative therapeutic approaches to fight against resistance mechanisms to current therapies.