BACKGROUND AND OBJECTIVES: Breakdown of the blood-nerve barrier (BNB) is observed in patients with Guillain-Barré syndrome (GBS)
however, the molecular mechanism underlying this phenomenon remains unclear.The aim of this study was to identify antibodies against the BNB-endothelial cells that initiate BNB breakdown in patients with GBS. METHODS: We purified IgGs from the serum samples of patients with GBS (n = 77) during the acute phase, disease controls ([DCs], n = 51), and healthy controls ([HCs], n = 24). Human peripheral nerve microvascular endothelial cells (PnMECs) were incubated with IgG. Molecular changes in PnMECs after GBS-IgG exposure were evaluated using RNA-seq and a high-content imaging system. U1-small nuclear ribonucleoprotein (U1-snRNP) autoantibodies were detected using an ELISA. The clinical information of U1-snRNP antibody-positive GBS patients was verified. RESULTS: GBS-IgGs significantly increased NF-κB nuclear translocation and permeability of the 10-kDa dextran in PnMECs compared with DC-IgGs or HC-IgGs. RNA-seq analyses of PnMECs demonstrated that NF-κB p65 in the center of the network analysis, snRNPs as upstream genes of NF-κB p65, and CXCR5 as downstream genes of NF-κB p65 were important molecules after GBS-IgG exposure. The protein level of claudin-5 and U1-snRNP was significantly reduced while that of CXCR5 was significantly increased after incubation with IgG from patients with GBS, compared with that from HCs. The rate of U1-snRNP antibody positivity was 36% (28 of 77) in patients with GBS, 7% (2 of 28) in DCs, and 0% (0 of 16) in HCs. The serum titer of snRNP antibody decreased after treatment. Both cerebral spinal fluid protein and albumin quotient (QALB)/QALBLIM were higher in snRNP antibody-positive GBS patients than in snRNP antibody-negative GBS patients. IgG from U1-snRNP antibody-positive GBS patients decreased the barrier function and claudin-5 expression more than that from HCs in an in vitro BNB coculture model. The reduction in U1-snRNP antibody decreased the biological effect of IgG from GBS patients with U1-snRNP antibody on the increased permeability of PnMECs. DISCUSSION: U1-snRNP autoantibodies are associated with the breakdown of BNB in GBS, through the reduction of U1-snRNP and claudin-5 and the induction of NF-κB activation in BNB-endothelial cells. A temporary autoantibody response against snRNP may be boosted by the periodic response to infection in GBS.