Evaluation of soluble junctional adhesion molecule-A as a biomarker of human brain endothelial barrier breakdown.
BACKGROUND
An inducible release of soluble junctional adhesion molecule-A (sJAM-A) under pro-inflammatory conditions was described in cultured non-CNS endothelial cells (EC) and increased sJAM-A serum levels were found to indicate inflammation in non-CNS vascular beds. Here we studied the regulation of JAM-A expression in cultured brain EC and evaluated sJAM-A as a serum biomarker of blood-brain barrier (BBB) function.


RESULTS
As previously reported in non-CNS EC types, pro-inflammatory stimulation of primary or immortalized (hCMEC/D3) human brain microvascular EC (HBMEC) induced a redistribution of cell-bound JAM-A on the cell surface away from tight junctions, along with a dissociation from the cytoskeleton. This was paralleled by reduced immunocytochemical staining of occludin and zonula occludens-1 as well as by increased paracellular permeability for dextran 3000. Both a self-developed ELISA test and Western blot analysis detected a constitutive sJAM-A release by HBMEC into culture supernatants, which importantly was unaffected by pro-inflammatory or hypoxia/reoxygenation challenge. Accordingly, serum levels of sJAM-A were unaltered in 14 patients with clinically active multiple sclerosis compared to 45 stable patients and remained unchanged in 13 patients with acute ischemic non-small vessel stroke over time.


CONCLUSIONS
Soluble JAM-A was not suited as a biomarker of BBB breakdown in our hands. The unexpected non-inducibility of sJAM-A release at the human BBB might contribute to a particular resistance of brain EC to inflammatory stimuli, protecting the CNS compartment.
Department of Neurology, Julius Maximilian University, Würzburg, Germany.
Axel
A
Haarmann
Annika
A
Deiss
Jürgen
J
Prochaska
Christian
C
Foerch
Babette
B
Weksler
Ignacio
I
Romero
Pierre-Olivier
PO
Couraud
Guido
G
Stoll
Peter
P
Rieckmann
Mathias
M
Buttmann
D015415:Biomarkers / Q000378:metabolism*; D001812:Blood-Brain Barrier; D015153:Blotting, Western; D001921:Brain / Q000098:blood supply*; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D002560:Cerebrovascular Circulation; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D006031:Glycosylation; D006801:Humans; D007150:Immunohistochemistry; D062726:Junctional Adhesion Molecules
D015415:Biomarkers; D015815:Cell Adhesion Molecules; D062726:Junctional Adhesion Molecules