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She also had concurrent proteinuria caused by FSGS. using corticosteroids presented a partial or no response. All six patients were treated using intravenous immunoglobulin (IVIg). Among them, five exhibited a partial or poor response and the other exhibited a good response. All three patients treated using rituximab showed a good response. Conclusions The clinical characteristics of the patients were consistent with those in previous studies. Anti-NF155 antibody assay is necessary for diagnosing autoimmune nodopathy and its appropriate treatment, especially in young patients with CIDP who present with sensory ataxia and poor therapeutic responses to corticosteroids and IVIg. Keywords: peripheral neuropathy, autoimmune diseases, autoantibodies, neurofascin, nodes of Ranvier Graphical Abstract INTRODUCTION Autoantibodies against proteins at the nodes and paranodes of Ranvier, such as neurofascin (NF)-155 (NF155), NF186, contactin-1, and contactin-associated protein 1, were recently found in a small proportion of patients who fulfilled the clinical and electrodiagnostic criteria for chronic inflammatory demyelinating polyneuropathy (CIDP).1,2 Patients with these autoantibodies have characteristic clinical features, pathological findings, and poor responses to intravenous immunoglobulin (IVIg) treatment that can distinguish them from patients with CIDP, and autoimmune nodopathy has been proposed as a new category of acquired immune neuropathy associated with autoantibodies against nodal and paranodal proteins.3 Anti-NF155 is the most common autoantibody in autoimmune nodopathy. NF155 is usually a cell adhesion molecule expressed in the myelin loop and involved in the formation of septate-like junctions that anchor the myelin loop to axons at paranodes.4 These junctions play an important role in the compartmentalization of nodal-voltage-gated sodium channels and juxtaparanodal-voltage-gated potassium channels, and in the generation of action potentials.5,6 Previous studies have identified distinct features in patients with anti-NF155 antibody, including predominant distal involvement, sensory ataxia, tremor, highly elevated protein levels in the cerebrospinal fluid (CSF), poor responses to IVIg, good responses to rituximab, and predominance of the immunoglobulin G (IgG)-4 subclass of anti-NF155 antibodies.7,8,9,10 However, autoimmune nodopathy with anti-NF155 antibodies has not yet been observed in South Korea. In this Forskolin study we aimed to identify anti-NF155 antibodies in patients who fulfilled the diagnostic criteria for CIDP using a cell-based assay (CBA) and enzyme-linked immunosorbent assay (ELISA), and to determine the clinical features of South Korean patients with anti-NF155-antibody-positive autoimmune nodopathy. METHODS Patients and samples This study obtained 72 serum samples from 68 patients who fulfilled the 2010 European Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS) diagnostic criteria for CIDP (52 with definite, 11 with probable, and 5 with possible CIDP) from Samsung Medical Center and Severance Hospital in South Korea. Five serum samples were collected from one patient at various points during the disease course. Sera were also collected from 12 healthy individuals, 16 patients with inflammatory CNS diseases (10 with multiple sclerosis, 2 with myelin oligodendrocyte glycoprotein antibody disease, 1 with neuromyelitis optica spectrum disorder, and 3 with unspecified inflammatory Forskolin brain lesions), and 4 patients with other immune-mediated neuropathies (2 with IgM paraproteinemic neuropathy, 1 with multifocal motor neuropathy, and 1 with Miller Fisher syndrome). All serum samples were stored at -70 until they were further analyzed. Cell-based assay Serum Forskolin samples were analyzed to detect autoantibodies against NF155 using a CBA with NF155-transfected human recombinant embryonic kidney 293 (HEK293) cells. HEK293 cells were placed on a coverslip (SPL Life Sciences, Pocheon, South Korea) coated with poly-L-lysine (Sigma Aldrich, St. Rabbit Polyclonal to SLC6A6 Louis, MO, USA) and then placed on 24-well cell culture plates. Cells were produced in Dulbecco Modified Eagle Medium (GE Healthcare, Chicago, IL, USA) that contained 10% Fetal Bovine Serum (GE Healthcare) and 5% penicillin (Invitrogen, Waltham, MA, USA) at 70%C80% confluence. The cells were transfected with a green fluorescent protein (GFP)-tagged RG22907 NF155 plasmid (OriGene, Rockville, MD, USA). Immunofluorescence staining was performed after 48 h of incubation. HEK293 cells that expressed GFP-tagged NF155 were fixed in phosphate-buffered saline using 4% paraformaldehyde and blocked using 5% bovine serum albumin. The cells were incubated for 1 h at room temperature.