RT Journal Article SR Electronic T1 Sera from patients with multifocal motor neuropathy disrupt the blood-nerve barrier JF Journal of Neurology, Neurosurgery & Psychiatry JO J Neurol Neurosurg Psychiatry FD BMJ Publishing Group Ltd SP 526 OP 537 DO 10.1136/jnnp-2013-305405 VO 85 IS 5 A1 Shimizu, Fumitaka A1 Omoto, Masatoshi A1 Sano, Yasuteru A1 Mastui, Naoko A1 Miyashiro, Ai A1 Tasaki, Ayako A1 Maeda, Toshihiko A1 Koga, Michiaki A1 Kaji, Ryuji A1 Kanda, Takashi YR 2014 UL http://jnnp.bmj.com/content/85/5/526.abstract AB Objective In multifocal motor neuropathy (MMN), the destruction of the blood-nerve barrier (BNB) has been considered to be the key step in the disease process. The purpose of the present study was to ascertain whether sera from patients with MMN can open the BNB, and which component of patient sera is the most important for this disruption. Methods We evaluated the effects of sera from patients with MMN, patients with amyotrophic lateral sclerosis, and control subjects on the expression of tight junction proteins and vascular cell adhesion molecule-1 (VCAM-1), and on the transendothelial electrical resistance (TEER) in human peripheral nerve microvascular endothelial cells (PnMECs). Results The sera from patients with MMN decreased the claudin-5 protein expression and the TEER in PnMECs. However, this effect was reversed after application of an anti-vascular endothelial growth factor (anti-VEGF) neutralising antibody. The VEGF secreted by PnMECs was significantly increased after exposure to the sera from patients with MMN. The sera from patients with MMN also increased the VCAM-1 protein expression by upregulating the nuclear factor kappa-B (NF-κB) signalling. The immunoglobulin G purified from MMN sera decreased the expression of claudin-5 and increased the VCAM-1 expression in PnMECs. Conclusions The sera from MMN patients may disrupt the BNB function via the autocrine secretion of VEGF in PnMECs, or the exposure to autoantibodies against PnMECs that are contained in the MMN sera. Autoantibodies against PnMECs in MMN sera may activate the BNB by upregulating the VCAM-1 expression, thereby allowing for the entry of a large number of circulating inflammatory cells into the peripheral nervous system.