Background The characteristic structure of motor neurons (MNs), particularly of the long axons, becomes damaged in the early stages of amyotrophic lateral sclerosis (ALS). However, the molecular pathophysiology of axonal degeneration remains to be fully elucidated. Method Two sets of isogenic human-induced pluripotent stem cell (hiPSCs)-derived MNs possessing the single amino acid difference (p.H517D) in the fused in sarcoma ( FUS ) were constructed. By combining MN reporter lentivirus, MN specific phenotype was analyzed. Moreover, RNA profiling of isolated axons were conducted by applying the microfluidic devices that enable axon bundles to be produced for omics analysis. The relationship between the target gene, which was identified as a pathological candidate in ALS with RNA-sequencing, and the MN phenotype was confirmed by intervention with si-RNA or overexpression to hiPSCs-derived MNs and even in vivo . The commonality was further confirmed with other ALS-causative mutant hiPSCs-derived MNs and human pathology. Findings We identified aberrant increasing of axon branchings in FUS -mutant hiPSCs-derived MN axons compared with isogenic controls as a novel phenotype. We identified increased level of Fos-B mRNA, the binding target of FUS, in FUS -mutant MNs. While Fos-B reduction using si-RNA or an inhibitor ameliorated the observed aberrant axon branching, Fos-B overexpression resulted in aberrant axon branching even in vivo . The commonality of those phenotypes was further confirmed with other ALS causative mutation than FUS . Interpretation Analyzing the axonal fraction of hiPSC-derived MNs using microfluidic devices revealed that Fos-B is a key regulator of FUS -mutant axon branching. Fund Japan Agency for Medical Research and development; Japanese Ministry of Education, Culture, Sports, Science and Technology Clinical Research, Innovation and Education Center, Tohoku University Hospital; Japan Intractable Diseases (Nanbyo) Research Foundation; the Kanae Foundation for the Promotion of Medical Science; and “Inochi-no-Iro” ALS research grant.

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Background: There are still insufficient quantitative comparisons of phase-dependent blood-brain barrier permeability among inflammatory central nervous system disorders. Aim: By using the Reibergram (2-D diagram of the quotient of albumin and quotient of immunoglobulin G), we visually compared the extent of blood-brain barrier permeability among inflammatory central nervous system disorders. Methods: Both the quotient of albumin and that of immunoglobulin G in the acute and chronic phase were calculated in non-herpetic meningitis, septic meningitis, multiple sclerosis and neuromyelitis optica, and were plotted on the Reibergram. As controls, samples from non-inflammatory patients without pleocytosis were collected. The correlation coefficient between each cerebrospinal fluid biomarker and disease severity index in each disorder was also studied. Results: In the controls, the distribution differed between males and females, suggesting a sex-dependent difference in blood-brain barrier-function, in addition to the age-related compromise. A compromised blood-brain barrier was confirmed in the acute phase of meningitis and neuromyelitis optica, but not in the acute phase of multiple sclerosis. However, blood-brain barrier permeability significantly correlated with the severity and disability in multiple sclerosis. In meningitis, a compromised blood-brain barrier correlated well with the length of hospitalization rather than cerebrospinal fluid cell count. Conclusion: Visualization of the blood-brain barrier permeability with a Reibergram indicated distinct pathophysiology in each disorder. The quotient of albumin and quotient of immunoglobulin G would be useful for estimating the pathophysiology in each disorder, and the severity of ongoing inflammation or damage in the central nervous system.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease. Progressive and systemic loss of motor neurons with gliosis in the central nervous system (CNS) is a neuropathological hallmark of ALS. Chondroitin sulfate proteoglycans (CSPGs) are the major components of the extracellular matrix of the mammalian CNS, and they inhibit axonal regeneration physically by participating to form the glial scar. Recently, protein tyrosine phosphatase sigma (PTPσ) and leukocyte common antigen-related protein were discovered as CSPG receptors that play roles in inhibiting regeneration. Here we examined the expression of CSPG receptors in transgenic female rats overexpressing an ALS-linked mutant cytosolic Cu/Zn superoxide dismutase gene (SOD1). In contrast to controls, multiple immunofluorescence analyses revealed aberrant expression of CSPG receptors dominantly in reactive astrocytes, while PTPσ expression in neurons decreased in the spinal ventral horns of ALS transgenic rats. The aberrant and progressive astrocytic expression of CSPG receptors and reactive astrocytes themselves may be therapeutic targets for reconstructing a regeneration-supportive microenvironment under neurodegenerative conditions such as ALS.