Imaging the initial cellular events in EAE. (123.26)

Abstract

Abstract Limitations in current techniques to capture rare immune cell events have hindered the characterization of the initiation and progression of experimental autoimmune encephalomyelitis (EAE). With the cranial window and intravital two-photon microscopy techniques, we followed the initial dynamic and sequential cellular processes preceding EAE development. Disease progression was imaged daily in the first 12 days post EAE induction in either CX3CR1-GFP or CD11c-GFP transgenic mice containing adoptively transferred naïve ubiquitin-CFP myelin oligodendrocyte glycoprotein (MOG) specific T cells. Blood-brain barrier (BBB) permeability was assessed by i.v. injection of fluorescent dextran or quantum dots. We hypothesize that lymphocyte accumulation follows an initial transient BBB leak caused by pertussis toxin-initiated inflammation, with subsequent accumulation and activation of microglia and perivascular antigen presenting cells (APCs) facilitating the tissue-specific infiltration of MOG-specific T cells into the brain parenchyma via intra-luminal contact. Indeed, our sequential imaging experiments demonstrated transient leaks in BBB at the pia surface within the first 4 days post EAE induction, local APC accumulation from days 2 to 6, followed by T cell infiltration adjacent to local CNS vessel leak. Future work involves further defining the cellular and molecular regulation of CNS peri-vascular microenvironment responsible for cross-BBB attraction of MOG-specific cells.