Report on the 2nd scientific meeting of the "Verein zur Förderung des Wissenschaftlichen Nachwuchses in der Neurologie" (NEUROWIND e.V.) held in Motzen, Germany, Oct. 29'th - Oct. 31'st, 2010

Excerpt

T cell driven autoimmune inflammation in the CNS has widely been investigated in the model of experimental autoimmune encephalomyelitis (EAE) [1]. During decades of EAE research, it has been established that autoreactive T cells are activated in the peripheral immune tissue, then enter the CNS compartment and - upon local re-activation - acquire the ability to invade the CNS parenchyma and exert effector functions. Only with the advent of modern imaging techniques has it become possible to actually visualize the individual steps of T cell activation in the lymph nodes, of crossing the blood brain barrier, and of interaction between autoreactive T cells and their molecular targets within the CNS. Alexander Flügel has adapted the model of adoptive transfer EAE for imaging purposes making inflammatory processes accessible to two-photon-microscopy in situ. By retroviral expression of fluorescent proteins in encephalitogenic T cells, these T cells were visualized in vivo by two photon microscopy [2]. Christian Schläger from Alexander Flügel's group showed two-photon scanning data providing evidence that in the CNS vasculature encephalitogenic T cells tended to crawl against the blood stream before they left the vessel lumen in order to enter the perivascular space. Here, the cells appeared to be scanning their environment and only upon productive contact with antigen presenting cells that presented the appropriate antigen, T cells were instructed to infiltrate into the CNS parenchyma. It is becoming increasingly clear that many features of leukocyte extravasation in the CNS vasculature are unique and distinct from leukocyte extravasation in other vascular territories [3]. The advanced imaging tools that are now available hold promise to address current questions of T lymphocyte biology at the blood brain barrier: Why do lymphocytes move against the blood stream in the CNS microvasculature? Do lymphocytes trespass the endothelial barrier in a paracellular or transcellular way? How and to what extent do T cells become activated in the perivascular space? …