Intravital imaging of blood vessels and immune cells in inflammation, infection and cancer
Our team has a unique expertise in the intravital imaging of blood vessels and immune cells in inflammation, infection and cancer. This unique expertise in intravital and multiphoton microscopy allows us to monitor in vivo and in real time the location, dynamics and interactions of key cells activated or recruited in tissues (lymph nodes, tumors and lungs) in physiological or pathological conditions (cancer, infection, inflammation) or during therapeutic treatments.
For instance, we used intravital microscopy to characterize the interactions of lymphocytes with High Endothelial Venules (HEVs) in lymph nodes during physiological homing (Moussion and Girard, Nature 2011). In another study, we were able to visualize the trafficking of leukemic cells from chronic lymphocytic leukemia patients inside HEV blood vessels from mouse lymph nodes (Lafouresse et al, Blood 2015)
Chronic Lymphocytic Leukemia (CLL) cells bind to HEVs in vivo via a multistep adhesion cascade, which involves rolling, sticking and crawling of the leukemic cells on the endothelium. Intravital microscopy visualization of human CLL cells behavior in lymph node microcirculation of mice. CLL cells from patients interact (roll and stick) on HEVs endothelium in vivo. © E. Bellard and F. Lafouresse
Tumor-associated HEVs (TA-HEVs) function as portals of entry for lymphocytes into tumors during cancer immunotherapy. Multiphoton imaging of lymphocytes (in green) migrating through TA-HEVs (in red) during combination anti-PD-1 plus anti-CTLA-4 immunotherapy. © E. Bellard and J.-P. Girard.
Intravital and multiphoton microscopy were also key for the study of the molecular and cellular mechanisms mediating lymphocyte entry into tumors. For the first time, we were able to film the lymphocytes entering tumors through tumor-associated HEVs (TA-HEVs). We showed that these specialized tumor blood vessels (< 10 % of total tumor blood vessels) are the main sites of lymphocyte extravasation into tumors during cancer immunotherapy with anti-CTLA-4 and anti-PD-1 antibodies (Asrir et al, Cancer Cell 2022, movie 2).
Our team also masters the intravital imaging method applied to the lung (Lefrancais et al Nature 2017; Lefrancais et al JCI Insight 2018).
By setting it up in a level 3 biosafety laboratory (Barlerin Scientific Reports 2017), we can follow cellular dynamics in infected lungs.
This allows us to conduct projects aimed at understanding the behavior and dynamics of innate lymphoid cells, lymphocytes, macrophages, neutrophils or platelets within the inflamed or infected lung (Allergic inflammation, Pseudomonas Aeruginosa, Mycobacterium Tuberculosis, SARS-Cov2,…) (Santoni et al, Plos Pathogens 2022).
Neutrophil Extracellular Traps (NETs) serve as an emergency first-line defense mechanism to trap and kill extracellular bacteria and other pathogens during serious infections; however, NETs are increasingly implicated in a variety of noninfectious diseases associated with inflammation and tissue injury. Intravital microscopy visualization of granulocyte death and NETs in mice infected with Pseudomonas Aeruginosa. Pseudo colors represent vessels (gray, mTomato); Granulocytes (Green, MRP8-mGFP+); Dead cells (Purple, SYTOX blue) © Emma Lefrançais and E. Meunier
We work with dedicated microscopes of the IPBS-TRI imaging platform that offer complementary approaches (lien vers TRI-IPBS microscopie https://www.ipbs.fr/fr/tri-microscopie/):
• DM6FS provides video frame rate tracking of fast events occurring within the bloodstream in wide field, monochrome or two colours.
• The 7MP makes it possible to follow, in greater depth and in 3 dimensions, the slower rolling and transmigration events in the tissues under standard conditions.
• Trimscope offers the same approach as 7MP but under infectious conditions in a BSL3 environment.
The use of the machines is done according to the conditions of access and opening of the platform