Receptor-mediated transcytosis is one of the major routes for drug delivery of large molecules into the brain. The aim of this study was to develop a novel model of the human blood–brain barrier (BBB) in a high-throughput microfluidic device. This model can be used to assess passage of large biopharmaceuticals, such as therapeutic antibodies, across the BBB. The model comprises human cell lines of brain endothelial cells, astrocytes, and pericytes in a two-lane or three-lane microfluidic platform that harbors 96 or 40 chips, respectively, in a 384-well plate format. In each chip, a perfused vessel of brain endothelial cells was grown against an extracellular matrix gel, which was patterned by means of surface tension techniques. Astrocytes and pericytes were added on the other side of the gel to complete the BBB on-a-chip model. Barrier function of the model was studied using fluorescent barrier integrity assays. To test antibody transcytosis, the lumen of the model’s endothelial vessel was perfused with an anti-transferrin receptor antibody or with a control antibody. The levels of antibody that penetrated to the basal compartment were quantified using a mesoscale discovery assay. The perfused BBB on-a-chip model shows presence of adherens and tight junctions and severely limits the passage of a 20 kDa FITC-dextran dye. Penetration of the antibody targeting the human transferrin receptor (MEM-189) was markedly higher than penetration of the control antibody (apparent permeability of 2.9 × 10−5 versus 1.6 × 10−5 cm/min, respectively). We demonstrate successful integration of a human BBB microfluidic model in a high-throughput plate-based format that can be used for drug screening purposes. This in vitro model shows sufficient barrier function to study the passage of large molecules and is sensitive to differences in antibody penetration, which could support discovery and engineering of BBB-shuttle technologies.

An autoantibody target on brain microvascular endothelial cells in patients with neuromyelitis optica may be exploited to manipulate blood-brain barrier permeability.

Background and Objectives To evaluate the pathophysiology of neuromyelitis optica spectrum disorder (NMOSD) and the therapeutic mechanism and levels of interleukin-6 (IL-6) blockade (satralizumab), especially with respect to blood-brain barrier (BBB) disruption with the new in vitro and ex vivo human BBB models and in vivo model. Methods We constructed new static in vitro and flow-based ex vivo models for evaluating continued barrier function, leukocyte transmigration, and intracerebral transferability of neuromyelitis optica-immunoglobulin G (NMO-IgG) and satralizumab across the BBB using the newly established triple coculture system that are specialized to closely mimic endothelial cell contact of pericytes and endfeet of astrocytes. In the in vivo study, we assessed the effects of an anti–IL-6 receptor antibody for mice (MR16-1) on in vivo BBB disruption in mice with experimental autoimmune encephalomyelitis in which IL-6 concentration in the spinal cord dramatically increases. Results In vitro and ex vivo experiments demonstrated that NMO-IgG increased intracerebral transferability of satralizumab and NMO-IgG and that satralizumab suppressed the NMO-IgG–induced transmigration of T cells and barrier dysfunction. In the in vivo study, the blockade of IL-6 signaling suppressed the migration of T cells into the spinal cord and prevented the increased BBB permeability. Discussion These results suggest that (1) our triple-cultured in vitro and in ex vivo BBB models are ideal for evaluating barrier function, leukocyte transmigration, and intracerebral transferability; (2) NMO-IgG increased the intracerebral transferability of NMO-IgG via decreasing barrier function and induced secretion of IL-6 from astrocytes causing more dysfunction of the barrier and disrupting controlled cellular infiltration; and (3) satralizumab, which can pass through the BBB in the presence of NMO-IgG, suppresses the BBB dysfunction and the infiltration of inflammatory cells, leading to prevention of onset of NMOSD.

The blood–brain barrier (BBB) acts as a structural and functional barrier for brain homeostasis. This review highlights the pathological contribution of BBB dysfunction to neuroimmunological diseases, including multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD), myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), autoimmune encephalitis (AE), and paraneoplastic neurological syndrome (PNS). The transmigration of massive lymphocytes across the BBB caused by the activation of cell adhesion molecules is involved in the early phase of MS, and dysfunction of the cortical BBB is associated with the atrophy of gray matter in the late phase of MS. At the onset of NMOSD, increased permeability of the BBB causes the entry of circulating AQP4 autoantibodies into the central nervous system (CNS). Recent reports have shown the importance of glucose-regulated protein (GRP) autoantibodies as BBB-reactive autoantibodies in NMOSD, which induce antibody-mediated BBB dysfunction. BBB breakdown has also been observed in MOGAD, NPSLE, and AE with anti-NMDAR antibodies. Our recent report demonstrated the presence of GRP78 autoantibodies in patients with MOGAD and the molecular mechanism responsible for GRP78 autoantibody-mediated BBB impairment. Disruption of the BBB may explain the symptoms in the brain and cerebellum in the development of PNS, as it induces the entry of pathogenic autoantibodies or lymphocytes into the CNS through autoimmunity against tumors in the periphery. GRP78 autoantibodies were detected in paraneoplastic cerebellar degeneration and Lambert–Eaton myasthenic syndrome, and they were associated with cerebellar ataxia with anti-P/Q type voltage-gated calcium channel antibodies. This review reports that therapies affecting the BBB that are currently available for disease-modifying therapies for neuroimmunological diseases have the potential to prevent BBB damage.

Blood–brain barrier (BBB) dysfunction is a key feature in neuroimmunological and neurodegenerative diseases. In this study, we developed a microfluidic human BBB-on-a-chip to model barrier dysfunction and immune cell migration using immortalized TY10 brain endothelial cells, pericytes, and astrocytes. It was found that immortalized TY10 brain endothelial cells developed a microvascular structure under flow. Pericytes were localized on the basal side surrounding the TY10 microvascular structure, showing an in vivo-like structure. Barrier integrity increased under co-culture with pericytes. In addition, both ethylenediaminetetraacetic acid (EDTA) and anti-Claudin-5 (CLDN5) neutralizing antibody caused a decrease in the transendothelial electrical resistance (TEER). EDTA caused the leakage of 20 kDa dextran, suggesting different effects on the BBB based on the mechanism of action, whereas anti-CLDN5 antibody did not cause leakage. In the tri-culture model, human T cells migrated through endothelial vessels towards basal C-X-C motif chemokine ligand 12 (CXCL12). The live-imaging analysis confirmed the extravasation of fluorescence-labelled T cells in a CXCL12-concentration- and time-dependent manner. Our BBB model had an in vivo-like structure and successfully represented barrier dysfunction and transendothelial T cell migration. In addition, our study suggests that the inhibition of CLDN5 attenuates the BBB in humans. This platform has various potential uses in relation to the BBB in both drug discovery research and in elucidating the mechanisms of central nervous system diseases.

Background and Objectives To analyze (1) the effect of immunoglobulin G (IgG) from patients with anti–myelin oligodendrocyte glycoprotein antibody (MOG-Ab)–associated disorder on the blood-brain barrier (BBB) endothelial cells and (2) the positivity of glucose-regulated protein 78 (GRP78) antibodies in MOG-Ab–associated disorders. Methods IgG was purified from sera with patients with MOG-Ab–associated disorder in the acute phase (acute MOG, n = 15), in the stable stage (stable MOG, n = 14), healthy controls (HCs, n = 9), and disease controls (DCs, n = 27). Human brain microvascular endothelial cells (BMECs) were incubated with IgG, and the number of nuclear NF-κB p65-positive cells in BMECs using high-content imaging system and the quantitative messenger RNA change in gene expression over the whole transcriptome using RNA-seq were analyzed. GRP78 antibodies from patient IgGs were detected by Western blotting. Results IgG in the acute MOG group significantly induced the nuclear translocation of NF-κB and increased the vascular cell adhesion molecule 1/intercellular adhesion molecule 1 expression/permeability of 10-kDa dextran compared with that from the stable MOG and HC/DC groups. RNA-seq and pathway analysis revealed that NF-κB signaling and oxidative stress (NQO1) play key roles. The NQO1 and Nrf2 protein amounts were significantly decreased after exposure to IgG in the acute MOG group. The rate of GRP78 antibody positivity in the acute MOG group (10/15, 67% [95% confidence interval, 38%–88%]) was significantly higher than that in the stable MOG group (5/14, 36% [13%–65%]), multiple sclerosis group (4/29, 14% [4%–32%]), the DCs (3/27, 11% [2%–29%]), or HCs (0/9, 0%). Removal of GRP78 antibodies from MOG-IgG reduced the effect on NF-κB nuclear translocation and increased permeability. Discussion GRP78 antibodies may be associated with BBB dysfunction in MOG-Ab–associated disorder.