Molecular Mechanisms Involved in lymphocyte Recruitment in Inflamed Brain Microvessels: Critical Roles for P-Selectin Glycoprotein Ligand-1 and Hterotrimeric G_i-Linked Receptors~1

摘要

Lymphocyte recruitment into the brain is a critical event int eh pathogenesis of multiple sclerosis and experimental autoimmune encephalomyelitis. We developed a novel intravital microscopy model to directly analyze through the skull the interactions between lymphocytes and the endothelium in cerebral venules of mice. No adhesive interactions were observed between lymphocytes and the nonactivated endothelium in the cerebral microcirculation. When brain venules were activated by pretreating mice with TNF-#alpha# or LPS, proteolipid protein 139-151 autoreactive T lymphocytes rolled and arrested; notably, only a few peripheral lymph mode cells rolled tand firmly adhered. Abs anti-P-selectin glycoprotein ligand-1 and anti-E- and P-selectin blocked tethering and rolling of autoreactive lymphocytes, suggesting that P-selection glycoprotein ligand-1/endothelial selectins are critical in the recruitment of lymphocytes in inflamed brain venules. E-and P-selectin were expressed on cerebral vessels upon in vivo activation and had a patchy distribution during the preclinical phase of active and passive experimental autoimmune encephalomyelitis. LFA-1/ICAM-1 and #alpha#_4 integrins/VCAM-1 supported rolling, but were not relevant to rolling velocity. Firm arrest was mainly mediated by LFA-1 and ICAM-1. Pretreatment of autoreactive lymphocytes with pertussis toxin blocked integrin-dependent arrest, implicating a requirement for G_I protein-dependent signaling in vessels from nonlymphoid districts. In conclusion, our data unveils the molecular mechanisms controlling the recruitment of autoreactive lymphocytes in inflamed cerebral vessels and suggest new insights into the pathogenesis of autoimmune inflamatory diseases of the CNS.