title: Pathological expression of CXCL12 at the blood-brain barrier correlates with severity of multiple sclerosis.
abstract: Dysregulation of blood-brain barrier (BBB) function and transendothelial migration of leukocytes are essential components of the development and propagation of active lesions in multiple sclerosis (MS). Animal studies indicate that polarized expression of the chemokine CXCL12 at the BBB prevents leukocyte extravasation into the central nervous system (CNS) and that disruption of CXCL12 polarity promotes entry of autoreactive leukocytes and inflammation. In the present study, we examined expression of CXCL12 and its receptor, CXCR4, within CNS tissues from MS and non-MS patients. Immunohistochemical analysis of CXCL12 expression at the BBB revealed basolateral localization in tissues derived from non-MS patients and at uninvolved sites in tissues from MS patients. In contrast, within active MS lesions, CXCL12 expression was redistributed toward vessel lumena and was associated with CXCR4 activation in infiltrating leukocytes, as revealed by phospho-CXCR4-specific antibodies. Quantitative assessment of CXCL12 expression by the CNS microvasculature established a positive correlation between CXCL12 redistribution, leukocyte infiltration, and severity of histological disease. These results suggest that CXCL12 normally functions to localize infiltrating leukocytes to perivascular spaces, preventing CNS parenchymal infiltration. In the patient cohort studied, altered patterns of CXCL12 expression at the BBB were specifically associated with MS, possibly facilitating trafficking of CXCR4-expressing mononuclear cells into and out of the perivascular space and leading to progression of disease.
authors.affiliation: Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, USA.
authors.forename: Erin E
authors.initials: EE
authors.lastname: McCandless
authors.forename: Laura
authors.initials: L
authors.lastname: Piccio
authors.forename: B Mark
authors.initials: BM
authors.lastname: Woerner
authors.forename: Robert E
authors.initials: RE
authors.lastname: Schmidt
authors.forename: Joshua B
authors.initials: JB
authors.lastname: Rubin
authors.forename: Anne H
authors.initials: AH
authors.lastname: Cross
authors.forename: Robyn S
authors.initials: RS
authors.lastname: Klein
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001253:Astrocytes / Q000378:metabolism; D001812:Blood-Brain Barrier / Q000378:metabolism*; D016022:Case-Control Studies; D054377:Chemokine CXCL12 / Q000378:metabolism*; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000378:metabolism*; D019718:Receptors, CXCR4 / Q000378:metabolism; D014018:Tissue Distribution; D015854:Up-Regulation
chemical_list: C515255:CXCL12 protein, human; C527276:CXCR4 protein, human; D054377:Chemokine CXCL12; D019718:Receptors, CXCR4