Summary
Anti‐neurofascin‐155 (NF155) antibodies have been observed in two cases with neuromyelitis optica spectrum disorders (NMOSD). This study investigated the prevalence of anti‐NF155 antibodies in patients with NMOSD and the clinical features of anti‐NF155 antibody‐positive patients. Sera from 129 patients with NMOSD were screened with anti‐NF155 antibodies by cell‐based assay (CBA) and re‐examined using immunostaining of teased mouse sciatic nerve fibres. Fifty‐six patients with multiple sclerosis (MS) and 50 healthy controls (HC) were also enrolled for detecting anti‐NF155 antibodies. A total of 12.40% (16 of 129) of patients with NMOSD were positive for anti‐NF155 antibodies confirmed by both CBA and immunostaining. Immunoglobulin (Ig) G1 was the predominant subclass. However, none of 56 MS patients or 50 HC were positive for anti‐NF155 antibodies. Anti‐NF155 antibody‐positive NMOSD patients had a higher proportion of co‐existing with autoimmune diseases (p < 0.001) and higher positive rates of serum non‐organ‐specific autoantibodies, including anti‐SSA antibodies (p < 0.001), anti‐SSB antibodies (p = 0.008), anti‐Ro‐52 antibodies (p < 0.001) and rheumatoid factor (p < 0.001). Five anti‐NF155 antibody‐positive NMOSD patients who took part in the nerve conduction study showed mildly abnormal results. Differences in some nerve conduction study parameters were observed between anti‐NF155 antibody‐positive and negative patients. Anti‐NF155 antibodies occurred in a small proportion of NMOSD patients. Anti‐NF155 antibody‐positive NMOSD patients tended to co‐exist with autoimmune diseases.
Keywords: anti‐neurofascin‐155 antibodies, neuromyelitis optica spectrum disorders, autoimmune diseases, demyelination
12.40% (16/129) of patients with NMOSD were positive for anti‐NF155 antibodies confirmed by both CBA and immunostaining. Anti‐NF155 antibody‐positive NMOSD patients had a higher proportion of coexisting with autoimmune diseases and higher positive rates of serum non‐organ‐specific autoantibodies. Anti‐NF155 antibody‐positive NMOSD patients tended to coexist with autoimmune diseases.
INTRODUCTION
The neuromyelitis optica spectrum disorders (NMOSD) are autoimmune demyelinating diseases in the central nervous system. The main pathological mechanism of NMOSD is thought to be astrocyte damage and demyelination caused by antibody‐mediated and complement‐dependent cytotoxicity [1]. The aquaporin‐4 immunoglobulin G antibody (AQP4‐IgG) is a specific biomarker for NMOSD and helps to differentiate NMOSD from multiple sclerosis (MS) [2, 3]. However, there are still 10–25% of patients with NMOSD who are seronegative for AQP4‐IgG [4]. Myelin oligodendrocyte glycoprotein immunoglobulin G (MOG‐IgG) is present in approximately 33–42% of AQP4‐IgG seronegative NMOSD patients [5, 6]. Antibodies against aquaporin‐1, N‐methyl‐D‐aspartate‐type glutamate receptor and glycine receptor were also reported in NMOSD, indicating that other non‐AQP4 autoantibodies might be involved in the pathogenesis of NMOSD [7].
Neurofascin‐155 (NF155) is a cell adhesion molecule expressed on the myelin sheath at paranode in both the central nervous system (CNS) and peripheral nervous system (PNS), which plays an essential role in structural and functional integrity of paranode by forming septate‐like junctions with contactin‐1 (CNTN1) and contactin‐associated protein 1 (Caspr1) [8, 9]. These septate‐like junctions work as a barrier that restricts the voltage‐gated Na+ channels in the node and voltage‐gated K+ channels in the juxtaparanodes [8, 9]. Antibodies against NF155, which may cause disruption of Caspr1/CNTN1/NF155 complex at the paranode, have been observed in demyelinating disorders such as chronic inflammatory demyelinating polyneuropathy (CIDP) [10], combined central and peripheral demyelination (CCPD) [11] and MS [12]. Although two cases with NMOSD who tested seropositive for anti‐NF155 antibodies have been described previously [13], the prevalence of anti‐NF155 antibodies in patients with NMOSD remains unclear. The purpose of this study was to evaluate the prevalence of antibodies against NF155 in patients with NMOSD. Clinical features of patients who were seropositive for anti‐NF155 antibodies were investigated.
MATERIALS AND METHODS
Subjects
A total of 129 patients with NMOSD who were hospitalized in the Neurology Department of Tianjin Medical University General Hospital from July 2010 to October 2020 were retrospectively enrolled into this study. There were 118 female and 11 male patients, with a mean age of 47.18 ± 14.31 years in NMOSD patients. Patients with NMOSD were diagnosed according to 2015 international consensus diagnostic criteria by an experienced neurologist [3]. Inclusion criteria were as follows: (1) all the participants were aged over 16 years; (2) cerebral and spinal magnetic resonance imaging (MRI) were performed; and (3) serum AQP4‐IgG was tested in our clinical neuroimmunology laboratory. Demographic and clinical data of patients with NMOSD were collected. Serum samples of all the 129 NMOSD patients during the acute phase before immunosuppressive treatment (104 patients) or in remission phase (25 patients) were collected with informed consent. All the serum samples obtained were immediately stored at −80°C until analysis. The Kurtzke Expanded Disability Status Scale (EDSS) scores were determined by two experienced neurologists. Additionally, 56 patients with MS (37 females and 19 males, mean age = 38.14 ± 13.20 years, 46 in the acute phase and 10 in the remission phase) and 50 healthy controls (HC) (29 females and 21 males, mean age = 56.02 ± 18.82 years) were enrolled and their serum samples were obtained with informed consent for detection of anti‐NF155 antibodies. Diagnosis of MS was based on the 2017 revised McDonald diagnostic criteria [14]. This study was approved by the Medical Research Ethics Committee at Tianjin Medical University General Hospital (Ethical no. IRB2020‐WZ‐200).
Detection of anti‐NF155 antibodies and subclasses by cell‐based assay (CBA)
Serum anti‐NF155 antibodies were detected using CBA, as previously reported [15, 16]. Briefly, a human embryonic kidney (HEK) 293 cell line stably expressing human NF155‐green fluorescent protein (GFP) fusion protein was generated using plasmid containing full‐length cDNA encoding human NF155 (OriGene Technologies, Inc., Rockville, Maryland, USA). The plasmid was transfected using FuGENE6 (Promega Corporation, Madison, Wisconsin, USA), according to the manufacturer’s instructions. Selective medium containing G418 was used for culturing of the transfected cells. After 15–20 days, single colonies had formed with adequate size and were picked up using a sterile cloning cylinder for clonal expansion. The transfected cells were seeded in 24‐well plates with coverslips and allowed to grow overnight. The cells were then fixed with 4% paraformaldehyde for 15 min and blocked with 5% goat serum for 30 min. Serum samples diluted 1:100 with Dulbecco’s modified Eagle’s medium (DMEM) were added as the primary antibody. After incubation at room temperature (RT) for 60 min, the cells were washed with phosphate‐buffered saline (PBS) and incubated with Alexa Fluor 555‐conjugated goat anti‐human IgG (H+L) (Invitrogen, Carlsbad, California, USA) diluted 1:500 with DMEM as secondary antibody at RT for 60 min. The coverslips with cells were washed with PBS and nuclei were counterstained with 4′,6‐diamidino‐2‐phenylindole (DAPI) (Abcam, Cambridge, UK). Cells were examined using a fluorescence microscope (Olympus BX51, Tokyo, Japan) in the darkroom. IgG subclass profiles were detected in anti‐NF155 antibody‐positive NMOSD patients using mouse anti‐human IgG1 Fc (diluted 1:75), mouse anti‐human IgG2 (diluted 1:250), mouse anti‐human IgG3 (heavy chain) (diluted 1:250) and mouse anti‐human IgG4 Fc (diluted 1:75) (Invitrogen) as secondary antibodies and Alexa Fluor 555‐conjugated goat anti‐mouse IgG (Invitrogen) diluted 1:500 for fluorescence detection.
Detection of anti‐NF155 antibodies by immunostaining of teased mouse sciatic nerve fibres
Sera from anti‐NF155 antibodies positive NMOSD patients were further re‐examined using immunostaining of teased mouse sciatic nerve fibres. These methods were conducted essentially as previously reported [15]. The sciatic nerves were dissected from 10‐week‐old female C57BL/6 mice and fixed with 4% paraformaldehyde for 10 min. Fixed nerves were teased gently with two fine forceps and dried on glass slides. Teased nerve fibres were permeabilized and blocked using 0.2% Triton X‐100 and 3% bovine serum albumin (BSA) with PBS for 90 min. The nerve fibres were then incubated with rabbit anti‐Caspr antibody (Abcam) diluted 1:500 and sera from NMOSD patients diluted 1:100 at 4°C. Single‐staining with serum or anti‐Caspr antibody was also performed. After 24 h, the nerve fibres were washed three times with PBS for 10 min each, and incubated with Alexa Fluor 488‐conjugated goat anti‐human IgG and Alexa Fluor 555‐conjugated goat anti‐rabbit IgG (Invitrogen) diluted 1:500 with PBS for 60 min at RT. After washing three times with PBS for 10 min each, the nerve fibers were mounted with DAPI (Abcam) and examined by fluorescence microscope (Olympus BX51) in the darkroom. For confirming the IgG subclass profiles, mouse anti‐human IgG1 Fc, mouse anti‐human IgG2, mouse anti‐human IgG3 (heavy chain) and mouse anti‐human IgG4 Fc (Invitrogen) were incubated as secondary antibodies prior to fluorescent staining with Alexa Fluor 488‐conjugated goat anti‐mouse IgG and Alexa Fluor 555‐conjugated goat anti‐rabbit IgG (Invitrogen). The animal experimental procedures were approved by the Animal Ethics Committee of the Tianjin Medical University. All efforts were made to minimize the number of animals and their suffering.
Preincubation and immunostaining of teased mouse sciatic nerve fibres
Preincubation assays were mainly adapted from the study by Querol et al. [17]. NF155‐transfected HEK 293 cells and non‐transfected HEK 293 cells were seeded in 24‐well‐plates and allowed to grow overnight. After being fixed with 4% paraformaldehyde and blocked with 5% goat serum, cells were incubated with sera of anti‐NF155 antibody‐positive NMOSD patients (diluted 1:100) in 3% BSA in PBS for 1 h. The supernatants from both NF155‐transfected and non‐transfected cell plates were then collected for immunostaining of teased mouse sciatic nerve fibres.
Statistical analysis
All analyses were performed using SPSS version 20 (IBM Corporation, Armonk, New York, USA). The quantitative data were presented as mean ± standard deviation (SD) for normally distributed data or median with interquartile range (IQR) for non‐normally distributed data. For quantitative data analysis between two groups, independent t‐tests or Mann–Whitney U‐tests were used according to whether or not the data were normally distributed. The χ2 test or Fisher’s exact tests were conducted to compare qualitative variables; p < 0.05 was considered statistically significant.
RESULTS
Frequency of anti‐NF155 antibodies in patients with NMOSD, MS and HC
Sera from all the participants were screened for anti‐NF155 antibodies using CBA. Eighteen of 129 NMOSD patients were positive for anti‐NF155 antibodies after testing by CBA (Figure 1a]. In contrast, none of 56 MS patients or 50 HC were positive for anti‐NF155 antibodies. Additionally, after re‐examining using immunostaining of teased mouse sciatic nerve fibres, sera from 16 NMOSD patients were confirmed positive for anti‐NF155 antibodies by co‐localizing with the paranode of Ranvier stained by anti‐Caspr antibody in teased mouse sciatic nerve fibres (Figure 1b]. No cross‐reactions were observed in single‐staining with serum and anti‐Caspr antibody (Figure 1c]. The reaction with paranode was abolished in sera from anti‐NF155 antibody‐positive NMOSD patients after preincubation with NF155‐transfected HEK 293 cells, but remained in sera preincubated with non‐transfected HEK 293 cells (Figure 1d]. In all 16 anti‐NF155 antibody‐positive NMOSD patients, IgG1 was the predominant subclass found in 14 patients and IgG3 in one patient; one patient was both IgG1 and IgG4 positive (Figure 2].
FIGURE 1.
Detection of anti‐NF155 antibodies by cell‐based assay and immunostaining of teased mouse sciatic nerve fibres. (a) Serum from a representative neuromyelitis optica spectrum disorders (NMOSD) patient with anti‐NF155 antibodies showed reaction with cells expressing human NF155‐GFP. Scale bar = 50 μm. (b) Serum from a representative NMOSD patient with anti‐NF155 antibodies showed co‐localizing with anti‐Caspr antibody in teased mouse sciatic nerve fibres. Scale bar = 10 μm. (c) Single‐staining with serum from anti‐NF155 antibody‐positive NMOSD patients and commercial anti‐Caspr antibodies demonstrated no cross‐reactions. Scale bar = 10 μm. (c) The co‐localizing with paranode was abolished in the serum of anti‐NF155 antibody‐positive NMOSD patients after preincubation with NF155‐transfected HEK 293 cells, but remained in the serum preincubated with non‐transfected HEK 293 cells. Scale bar = 10 μm. NF155 = neurofascin‐155; GFP = green fluorescent protein; HEK = human embryonic kidney; Caspr = contactin‐associated protein
FIGURE 2.
Detection of immunoglobulin (Ig) G subclass of anti‐NF155 antibody by cell‐based assay and immunostaining of teased mouse sciatic nerve fibres. (a) A representative IgG1 subclass of anti‐NF155 antibody was detected in a neuromyelitis optica spectrum disorders (NMOSD) patient using a cell‐based assay. Scale bar = 50 μm. (b) A representative IgG1 subclass of anti‐NF155 antibody was confirmed using immunostaining of teased mouse sciatic nerve fibres. Scale bar = 10 μm. NF155 = neurofascin‐155; GFP = green fluorescent protein; Caspr = contactin‐associated protein
Clinical characteristics
The clinical characteristics and radiological and laboratory features of 16 anti‐NF155 antibody‐positive NMOSD patients and 113 anti‐NF155 antibody‐negative NMOSD patients are summarized in Table 1. Anti‐NF155 antibody‐positive NMOSD patients had a higher proportion of co‐existence with autoimmune diseases than anti‐NF155 antibody‐negative patients (56.25% versus 5.31%, p < 0.001). In anti‐NF155 antibody‐positive NMOSD patients, four patients co‐existed with Sjögren’s syndrome (SS), one with immunorelated haemocytopaenia, one with scleroderma, one with rheumatoid arthritis (RA), one with undifferentiated connective tissue diseases (UCTD) and one with myasthenia gravis (MG). In anti‐NF155 antibody‐negative NMOSD patients, four patients co‐existed with SS, one with scleroderma and one with dermatomyositis. Connective tissue diseases (CTD) and MG were diagnosed by rheumatologists and neurologists. Serum AQP4‐IgG was tested by CBA in our clinical neuroimmunology laboratory [18]. Among all the 129 NMOSD patients, 73 patients were AQP4‐IgG‐positive, including 11 patients with both AQP4‐IgG and anti‐NF155 antibody‐positive rates. However, no significant differences were found in AQP4‐IgG‐positive rates between anti‐NF155 antibody‐positive and anti‐NF155 antibody‐negative NMOSD patients. Compared with anti‐NF155 antibody‐negative patients, anti‐NF155 antibody‐positive patients showed higher positive rates of serum non‐organ‐specific autoantibodies, including anti‐SSA antibodies (76.92% versus 18.28%, p < 0.001), anti‐SSB antibodies (30.77% versus 4.30%, p = 0.008), anti‐Ro‐52 antibodies (76.92% versus 19.35%, p < 0.001) and rheumatoid factor (RF) (38.46% versus 3.23%, p < 0.001). However, no other significant differences were found in clinical characteristics, radiological or laboratory features between the two groups of patients. In acute phases, all the NMOSD patients were treated with intravenous corticosteroids with or without intravenous immunoglobulin (IVIG). Long‐term relapse prevention therapy for patients with NMOSD was diverse. In anti‐NF155 antibody‐positive NMOSD patients, four patients used oral low‐dose corticosteroids; 12 patients used immunosuppressive therapies, including four with azathioprine (AZA), two with cyclophosphamide (CTX), three with mycophenolate mofetil (MMF), two with rituximab (RTX) and one with tocilizumab. In anti‐NF155 antibody‐negative NMOSD patients, 62 used oral low‐dose corticosteroids; 51 patients used immunosuppressive therapies including 25 with RTX, 17 with tocilizumab, seven with AZA and two with MMF. Detailed clinical features of 16 anti‐NF155 antibody‐positive NMOSD patients are summarized in Table 2.
TABLE 1.
Demographic and clinical features of NMOSD patients with and without anti‐NF155 antibodies
| Anti‐NF155‐antibody‐positive NMOSD | Anti‐NF155‐antibody‐negative NMOSD | p‐value | |
|---|---|---|---|
| Demographics | n = 16 | n = 113 | |
| Female/male | 16/0 | 102/11 | 0.408 |
| Age at onset (year, mean ± SD) | 41.69 ± 12.69 | 42.26 ± 14.63 | 0.983 |
| Age at sample (year, mean ± SD) | 47.25 ± 13.67 | 47.17 ± 14.46 | 0.883 |
| Follow‐up months, median (IQR) | 83.50 (50.00–102.75) | 49.00 (24.00–112) | 0.280 |
| ARR, median (IQR) | 0.69 (0.46–1.33) | 0.82 (0.50–1.21) | 0.875 |
| Initial presentation, n/N (%) | |||
| ON | 6/16 (37.50) | 50/113 (44.25) | 0.610 |
| AM | 7/16 (43.75) | 51/113 (45.13) | 0.917 |
| APS | 2/16 (12.50) | 10/113 (8.85) | 0.991 |
| Others | 1/16 (6.25) | 2/113 (1.77) | 0.330 |
| Symptoms and signs, n/N (%) | |||
| Visual disturbance | 8/16 (50.00) | 59/113 (52.21) | 0.868 |
| Limb weakness | 12/16 (75.00) | 71/113 (62.83) | 0.342 |
| Abnormal superficial sensation | 14/16 (87.50) | 84/113 (74.33) | 0.400 |
| Abnormal deep sensation | 5/16 (31.25) | 54/113 (47.79) | 0.214 |
| Bowel and bladder disturbance | 6/16 (37.50) | 37/113 (32.74) | 0.706 |
| Tremor | 1/16 (6.25) | 2/113 (1.77) | 0.330 |
| Ataxia | 2/16 (12.5) | 17/113 (15.04) | 1.000 |
| EDSS at nadir, median (IQR) | 3.75 (2.63–6.00) | 4.00 (2.00–6.50) | 0.489 |
| EDSS at last follow‐up, median (IQR) | 3.75 (2.63–4.50) | 4.50 (3.50–6.50) | 0.874 |
| With autoimmune disease, n/N (%) | 9/16 (56.25) | 6/113 (5.31) | <0.001 |
| Blood laboratory tests, n/N (%) | |||
| AQP4‐IgG | 11/16 (68.75) | 62/113 (54.87) | 0.294 |
| ANA (>1:80) | 11/13 (84.62) | 63/93 (67.74) | 0.358 |
| Anti‐SSA | 10/13 (76.92) | 17/93 (18.28) | <0.001 |
| Anti‐SSB | 4/13 (30.77) | 4/93 (4.30) | 0.008 |
| Anti‐Ro‐52 | 10/13 (76.92) | 18/93 (19.35) | <0.001 |
| RF (>20 IU/ml) | 5/13 (38.46) | 3/93 (3.23) | <0.001 |
| CSF laboratory tests | N = 14 | N = 77 | |
| CSF white cell counts (106/l) | 13.64 ± 23.61 | 20.86 ± 67.64 | 0.695 |
| CSF protein (g/l) | 0.53 ± 0.26 | 0.48 ± 0.34 | 0.641 |
| MRI lesions, n/N (%) | N = 16 | N = 113 | |
| Brain | 4/16 (25.00) | 43/113 (38.05) | 0.310 |
| Brain stem and cerebellum | 5/16 (31.25) | 38/113 (33.63) | 0.850 |
| Cervical cord | 9/16 (56.25) | 82/113 (72.57) | 0.295 |
| Thoracic cord | 14/16 (87.50) | 83/113 (73.45) | 0.364 |
| Lumbar cord | 1/16 (6.25) | 4/113 (3.54) | 0.490 |
Abbreviations: AM, acute myelitis; ANA, anti‐nuclear antibodies; APS, area postrema syndrome; AQP4‐IgG, aquaporin‐4 immunoglobulin G antibodies; ARR, annualized relapse rates; CSF, cerebrospinal fluid; EDSS, expanded disability status scale; IQR, interquartile range; MRI, magnetic resonance imaging; n, number of positive patients; N, total number of patients involved; NF155, neurofascin 155; NMOSD, neuromyelitis optica spectrum disorders; ON, optic neuritis; RF, rheumatoid factor; SD, standard deviation.
TABLE 2.
Clinical features of 16 anti‐NF155 antibody‐positive NMOSD patients
| Cases | Gender | Age at onset | Initial presentation | EDSS | Co‐existing autoimmune disease | Non‐organ‐specific autoantibodies | Subclass of anti‐NF155 IgG | AQP4‐IgG | CSF‐pro (g/l) | CSF‐WBC (106/l) | NCS | Long‐term relapse prevention therapy |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Case 1 | Female | 58 | ON | 4.5 | RA | ANA, SSA, Ro‐52 | IgG1 | Negative | 0.35 | 6 | Abnormal | Low‐dose corticosteroids |
| Case 2 | Female | 34 | ON | 2.0 | No | ANA, SSA, Ro‐52 | IgG1 | Positive | 0.44 | 10 | NA | MMF |
| Case 3 | Female | 50 | APS | 2.5 | SS | RF | IgG1 | Positive | 0.47 | 19 | NA | MMF |
| Case 4 | Female | 44 | ON | 8.0 | No | NA | IgG1 | Negative | 0.58 | 4 | NA | Low‐dose corticosteroids |
| Case 5 | Female | 42 | ON | 6.5 | No | ANA, SSA, SSB, Ro‐52 | IgG1 | Positive | 1.38 | 0 | NA | AZA |
| Case 6 | Female | 52 | AM | 3.5 | Immunorelated haemocytopenia | NA | IgG3 | Positive | NA | NA | Abnormal | Tocilizumab |
| Case 7 | Female | 39 | Brain stem | 3.0 | Scleroderma | NA | IgG1 | Positive | 0.57 | 3 | NA | AZA |
| Case 8 | Female | 32 | AM | 1.0 | SS | ANA, SSA, SSB, Ro‐52 | IgG1 | Negative | 0.30 | 0 | NA | CTX |
| Case 9 | Female | 24 | ON | 8.0 | No | Negative | IgG1 | Negative | 0.58 | 1 | NA | RTX |
| Case 10 | Female | 17 | APS | 8.5 | No | ANA, SSA, Ro‐52, RF | IgG1 | Positive | 0.41 | 30 | NA | MMF |
| Case 11 | Female | 40 | AM | 8.0 | No | ANA, SSA, Ro‐52, RF | IgG1 | Negative | 0.36 | 6 | Abnormal | RTX |
| Case 12 | Female | 53 | AM | 3.5 | SS | ANA, SSA, SSB, Ro‐52, RF | IgG1 and IgG4 | Positive | 0.58 | 90 | Abnormal | Low‐dose corticosteroids |
| Case 13 | Female | 58 | AM | 4.0 | MG | ANA | IgG1 | Positive | 0.50 | 0 | NA | Low‐dose corticosteroids |
| Case 14 | Female | 58 | ON | 3.5 | SS | ANA, SSA, SSB, Ro‐52, RF | IgG1 | Positive | 0.51 | 16 | Abnormal | AZA |
| Case 15 | Female | 27 | AM | 4.5 | No | ANA, SSA, Ro‐52 | IgG1 | Positive | NA | NA | NA | AZA |
| Case 16 | Female | 39 | AM | 2.5 | UCTD | ANA, SSA, Ro‐52 | IgG1 | Positive | 0.38 | 6 | NA | CTX |
Abbreviations: AM, acute myelitis; ANA, anti‐nuclear antibodies; APS, area postrema syndrome; AQP4‐IgG, aquaporin‐4 immunoglobulin G antibodies; AZA, azathioprine; CSF‐pro, cerebrospinal fluid protein; CSF‐WBC, cerebrospinal fluid white cells; CTX, cyclophosphamide; EDSS, expanded disability status scale; IgG, immunoglobulin G; MG, myasthenia gravis; MMF, mycophenolate mofetil; NA, not available; NCS, nerve conduction study; NF155 = neurofascin 155; NMOSD = neuromyelitis optica spectrum disorders; ON, optic neuritis; RA, rheumatoid arthritis; RF, rheumatoid factor; RTX, rituximab; SS, Sjögren’s syndrome; UCTD, undifferentiated connective tissue diseases.
Nerve conduction study in NMOSD patients
Five of the 16 anti‐NF155 antibody‐positive NMOSD patients took part in a nerve conduction study. The results of the nerve conduction study were interpreted by two experienced clinical neurophysiologists based on normal values from our laboratory [13]. Abnormal results of the nerve conduction study were observed in these five patients (Table 3]. Case 1 had lower compound motor action potential (CMAP) amplitude and slightly prolonged distal motor latency (DML) in median and ulnar nerves, lower sensory nerve action potential (SNAP) amplitude and prolonged F‐wave latency in median, ulnar and tibial nerves and slower sensory conduction velocity (SCV) in median and peroneal nerves. Case 6 had slightly lower SNAP amplitude in median and slightly prolonged F‐wave latency in tibial nerves. Case 11 had slightly slower SCV and motor conduction velocity (MCV) in tibial and peroneal nerves, lower SNAP amplitude and slower SCV in ulnar nerves and prolonged F‐wave latency in tibial nerves. Case 12 had lower CMAP amplitude and slower MCV in tibial nerves, lower CMAP and SNAP amplitude and slightly slower SCV in peroneal nerves, prolonged DML and F‐wave latency and slower SCV in median nerves. F‐wave was not detectable in right tibial nerves. Case 14 had lower SNAP amplitude and prolonged DML and F‐wave latency in tibial nerves, and slightly slower SCV in peroneal nerves. Notably, all five cases were positive for non‐organ‐specific autoantibodies or co‐existed with other autoimmune disorders (Table 2]. Unfortunately, nerve conduction studies of other anti‐NF155 antibody‐positive NMOSD patients were not available.
TABLE 3.
Nerve conduction study of five anti‐NF155 antibody‐positive NMOSD patients
| Normal values | Case 1 | Case 6 | Case 11 | Case 12 | Case 14 | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| L | R | L | R | L | R | L | R | L | R | |||
| Ulnar | CMAP (mV) | >8 | 3.10 | 2.70 | 4.90 | 6.60 | 9.00 | 8.50 | 5.10 | 6.30 | 9.40 | 7.90 |
| DML (ms) | <4 | 2.79 | 3.00 | 2.98 | 2.54 | 2.85 | 2.92 | 2.35 | 2.58 | 2.50 | 2.79 | |
| MCV (m/s) | >50 | 53.10 | 54.70 | 54.90 | 57.90 | 53.70 | 54.40 | 50.70 | 59.60 | 56.50 | 55.80 | |
| F wave latency (ms) | <28 | 28.40 | 29.10 | 24.30 | 25.00 | 26.50 | 26.00 | 24.90 | 23.70 | 27.30 | 26.70 | |
| SNAP (uV) | >10 | 4.60 | 4.60 | 10.40 | 11.20 | 6.80 | 9.10 | 11.10 | 16.70 | 7.70 | 10.80 | |
| SCV (m/s) | >50 | 50.00 | 50.80 | 56.30 | 54.60 | 48.60 | 46.10 | 53.50 | 52.80 | 54.10 | 54.60 | |
| Median | CMAP (mV) | >8 | 5.70 | 5.40 | 8.10 | 13.50 | 10.80 | 11.20 | 7.80 | 8.70 | 9.80 | 12.00 |
| DML (ms) | <4 | 5.13 | 4.29 | 2.92 | 3.21 | 3.90 | 3.56 | 3.90 | 4.56 | 3.21 | 3.48 | |
| MCV (m/s) | >50 | 50.70 | 52.00 | 59.20 | 58.40 | 55.10 | 58.00 | 55.70 | 55.40 | 60.50 | 58.60 | |
| F wave latency (ms) | <28 | 31.90 | 30.00 | 24.70 | 25.50 | 26.40 | 26.00 | 25.80 | 28.30 | 27.60 | 27.30 | |
| SNAP (uV) | >10 | 4.80 | 4.60 | 11.00 | 5.80 | 12.80 | 15.00 | 10.60 | 10.60 | 11.20 | 9.30 | |
| SCV (m/s) | >50 | 43.20 | 54.40 | 57.30 | 59.80 | 42.90 | 45.60 | 48.80 | 43.80 | 58.30 | 56.00 | |
| Tibial | CMAP (mV) | >5 | 4.50 | 7.50 | 5.90 | 4.80 | 8.30 | 10.30 | 6.00 | 3.90 | 6.20 | 7.00 |
| DML (ms) | <6 | 4.67 | 3.73 | 4.29 | 3.85 | 4.88 | 5.46 | 5.19 | 3.71 | 5.18 | 5.06 | |
| MCV (m/s) | >45 | 45.50 | 48.30 | 46.90 | 45.50 | 41.20 | 42.10 | 46.10 | 43.90 | 44.50 | 44.90 | |
| F wave latency (ms) | <50 | 51.30 | 51.00 | 50.20 | 50.20 | 52.50 | 50.60 | 50.60 | ND | 52.00 | 51.50 | |
| SNAP (uV) | >10 | 5.20 | 5.40 | 10.30 | 11.40 | 12.80 | 15.00 | 10.60 | 11.20 | 4.90 | 4.90 | |
| SCV (m/s) | >50 | 51.40 | 51.70 | 49.50 | 50.00 | 42.90 | 45.60 | 54.10 | 50.90 | 48.70 | 52.80 | |
| Peroneal | CMAP (mV) | >3 | 2.80 | 5.40 | 3.80 | 3.60 | 3.70 | 4.30 | 1.68 | 1.63 | 5.20 | 4.70 |
| DML (ms) | <5 | 3.65 | 3.60 | 3.75 | 3.17 | 5.50 | 4.13 | 3.91 | 3.54 | 3.40 | 3.10 | |
| MCV (m/s) | >45 | 45.20 | 45.40 | 51.10 | 47.00 | 40.90 | 42.50 | 46.50 | 46.10 | 46.40 | 46.50 | |
| SNAP (uV) | >10 | 11.80 | 5.90 | 11.10 | 15.80 | 15.00 | 18.00 | 5.80 | 7.80 | 11.60 | 13.50 | |
| SCV (m/s) | >50 | 48.00 | 47.10 | 50.40 | 49.80 | 41.40 | 46.40 | 45.90 | 42.40 | 45.80 | 47.00 | |
Abbreviations: CMAP, compound motor action potential; DML, distal motor latency; L, left; MCV, motor conduction velocity; ND, not detectable; NF155, neurofascin 155; NMOSD, neuromyelitis optica spectrum disorders; R, right; SCV, sensory conduction velocity; SNAP, sensory nerve action potential.
Twenty‐two anti‐NF155 antibody‐negative NMOSD patients took part in a nerve conduction study. Sixteen patients had abnormal nerve conduction study results. No significant differences in abnormality were found between anti‐NF155 antibody‐positive and ‐negative NMOSD patients (100.00% versus 72.73%, p = 0.555). Comparison of the nerve conduction study results between anti‐NF155 antibody‐positive and ‐negative patients are summarized in Supporting information, Table S1. The value of each nerve was counted individually when bilateral values are available. Anti‐NF155 antibody‐positive NMOSD patients showed longer F‐wave latencies of the ulnar, median and tibial nerves and DML of the ulnar and median nerves than anti‐NF155 antibody‐negative patients. Slower MCV of the ulnar nerve and SCV of the ulnar, median, tibial and peroneal nerves were observed in anti‐NF155 antibody‐positive patients. CMAP amplitude of tibial nerves and SNAP amplitude of peroneal nerves was lower in anti‐NF155 antibody‐positive patients than anti‐NF155 antibody‐negative patients. Nevertheless, the mean values of most nerve conduction study parameters in both anti‐NF155 antibody‐positive and ‐negative patients were within the normal range; the abnormalities of nerve conduction study were mild and approximated to normal values.
DISCUSSION
In the present study, anti‐NF155 antibodies were present in 12.40% (16 of 129) of NMOSD patients and the predominant subclass was IgG1. Anti‐NF155 antibody‐positive NMOSD patients had a higher proportion of co‐existing with autoimmune diseases such as CTD. Compared with anti‐NF155 antibody‐negative patients, anti‐NF155 antibody‐positive patients showed higher positive rates of serum anti‐SSA antibodies, anti‐SSB antibodies, anti‐Ro‐52 antibodies and RF. In addition, five anti‐NF155 antibody‐positive patients who took part in the nerve conduction study showed mildly abnormal results. The longer F‐wave latencies and DML, slower MCV and SCV and lower CMAP and SNAP amplitude were observed in anti‐NF155 antibody‐positive patients when compared with anti‐NF155 antibody‐negative patients, although the abnormalities were close to normal values. These findings extended the preliminary results of two anti‐NF155 antibody‐positive NMOSD cases reported by our group [13].
Previous studies demonstrated that 3.77–18% of CIDP patients were positive for serum anti‐NF155 antibodies [17, 19]. These CIDP patients present younger onset age, higher frequency of drop foot, tremor and poor response to IVIG [19]. The specific human leucocyte antigen (HLA) class II molecules and T helper type 2 (Th2) cell cytokines may be involved in the pathomechanisms of anti‐NF155 antibody‐positive CIDP [20, 21]. Kawamura reported that anti‐NF155 antibodies presented in 86% of patients with CCPD, which may be a potential diagnostic biomarker [11]. Mathey et al. reported that almost one‐third of MS patients (n = 26) had an antibody response to the extracellular domain of NF155 [12]. In a larger MS case (n = 242) study, Stich et al. described that 4.8% of primary progressive MS and 0.6% of relapsing–remitting MS had anti‐NF seroreactivity. However, in the present study, none of 56 MS patients showed positive for anti‐NF155 antibodies, which was consistent with the results in the study by Ogata et al. in 32 MS patients [19]. The different positive rates of anti‐NF155 antibodies in MS may be related to the difference in measurement methods. Similar to Ogata et al. [19], in the present study anti‐NF155 antibodies were screened by CBA and confirmed using immunostaining of teased nerve fibres.
It remains unclear whether or not anti‐NF155 antibodies contributed to the pathogenic mechanism of NMOSD or was simply a consequence of an immune response to inflammatory demyelination. NF155 exists both in the PNS and CNS, which may be the common immunopathogenic mechanism between CNS and PNS in patients with CCPD [11, 22]. In CIDP, the main subclass of anti‐NF155 antibody was IgG4, which may interfere with the interaction between NF155 and CNTN1/Caspr1 complex through the antigen blocking effect [23]. IgG4 antibodies have a weak affinity for the C1q and Fc immunoglobulin domain; thus, these CIDP patients are often refractory to IVIG [24]. The predominant subclass of NMOSD patients in this study was IgG1. IgG1 can efficiently activate complement [25], which may have a different pathophysiology from IgG4 in CIDP. No differences in EDSS and annualized relapse rates (ARR) between NMOSD patients with and without anti‐NF155 antibodies might indicate a unanimous response to treatment. The alteration of NF155 expression and paranodal structures has been observed adjacent to actively demyelinating lesions in patients with MS [26]. In experimental autoimmune encephalomyelitis (EAE), an animal model of MS, passive injection of anti‐NF155 antibodies could aggravate the disease severity [12]. Anti‐neurofascin IgG may be generated by antigenic epitope‐spreading in demyelinating MOG‐induced EAE models [27].
The occurrence of anti‐NF155 antibodies in patients of NMOSD may be associated with loss of self‐tolerance and abnormalities of the immune system. In the present study, anti‐NF155 antibody‐positive NMOSD patients tended to co‐exist with autoimmune diseases. Higher positive rates of serum anti‐SSA antibodies, anti‐SSB antibodies anti‐Ro‐52 antibodies and RF were also observed in anti‐NF155 antibody‐positive patients. It is generally reported that NMOSD often co‐exists with CTD and other autoimmune disorders. Non‐organ‐specific autoantibodies in patients with NMOSD indicate a more severe autoimmune reaction [28, 29]. The damage of blood‐CSF or blood nerve barriers caused by CTD‐related vasculitis may contribute to the breaking of NF155 immune tolerance. The epitope‐spreading refers to the diversification of epitope specificity from the initial focused antigen epitope to subdominant epitope or other antigens [30]. From the viewpoint of epitope‐spreading, anti‐NF155 antibodies may be a non‐specific ‘bystander’ response to inflammatory demyelination, rather than a pathogenic factor in NMOSD [27, 30]. The presence of anti‐NF155 antibodies might indicate that these NMOSD patients were prone to be associated with other autoimmune disorders, such as CTD.
Although some anti‐NF155 antibody‐positive patients exhibited mildly abnormal nerve conduction study results, it was uncertain if the complement‐activating IgG1 subtype of anti‐NF155 antibodies could play a pathogenic role in PNS injury in patients with NMOSD. In this study, 16 of 22 anti‐NF155 antibody‐positive patients also presented with mild abnormalities in the nerve conduction study. Although differences in some nerve conduction study parameters were observed between anti‐NF155 antibody‐positive and ‐negative patients, most values of these parameters were within the normal range. PNS damage has been reported in AQP4‐IgG‐positive NMOSD patients [31]. The expression of AQP4 at the nerve roots level in the junctional zone of CNS–PNS might be associated with PNS damage in NMOSD [31]. Also, systemic vasculitis associated with CTD can lead to peripheral nerve injury [32]. In this study, all five anti‐NF155 antibody‐positive patients who had mildly abnormal nerve conduction study results were positive for non‐organ‐specific autoantibodies or co‐existed with other autoimmune disorders. The pathogenic potential of anti‐NF155 antibody in both CNS and PNS similar to CCPD might be plausible to explain the PNS injury in these patients. However, the nerve conduction study results of NMOSD patients in this study were mildly abnormal and close to normal values. Symptoms caused by CNS lesions may overlap with those of peripheral nerve injury [31]. In the case of mild abnormalities in the nerve conduction study, it may be debatable to attribute sensory or motor disturbances to peripheral nerve abnormalities rather than to the definite lesions in the CNS. The differences in some nerve conduction study parameters between anti‐NF155 antibody‐positive and ‐negative patients may indicate that anti‐NF155 antibodies might affect nerve conduction to some extent, but the pathogenicity of anti‐NF155 antibodies remains questionable. Abnormalities in the nerve conduction study in NMOSD patients may also be associated with the expression of AQP4 at the nerve roots level and the peripheral nerve vasculitis associated with CTD [31, 32]. Nevertheless, considering the high proportion of co‐existence with autoimmune diseases in anti‐NF155 antibody‐positive patients, anti‐NF155 antibodies might be a non‐pathogenic epiphenomenon in patients with NMOSD, which represent an autoimmune predisposition in these patients.
Several limitations to this study need to be acknowledged. First, this study was a clinical observation study with a small sample size of the Chinese population. The prevalence of anti‐NF155 antibodies in other populations requires further studies. Secondly, the anti‐NF155 antibodies were qualitatively tested in the present study; quantitative detection of antibody titres in patients may be helpful for understanding the relationship between antibodies and clinical features. Thirdly, it is not easy to determine the efficacy of the treatments in this retrospective study. Fourthly, only a limited number of patients took part in in the nerve conduction study. Future study that includes more anti‐NF155 antibody‐positive NMOSD patients with a nerve conduction study would provide clues for the potential pathogenic role of anti‐NF155 antibodies in NMOSD.
In conclusion, 12.40% patients of NMOSD were positive for anti‐NF155 antibodies in the present study. These patients showed an autoimmune predisposition, with a higher proportion of co‐existence with autoimmune diseases and non‐organ‐specific autoantibodies. However, there were no other distinct clinical characters in anti‐NF155 antibody‐positive patients. The anti‐NF155 antibody might be a non‐specific ‘bystander’ epiphenomenon in patients with NMOSD. The pathogenic role of anti‐NF155 antibodies in PNS injury of NMOSD needs further investigation.
CONFLICT OF INTERESTS
The authors declare that they have no competing interests.
AUTHOR CONTRIBUTIONS
Sheng‐Hui Chang: experimental design, manuscript writing, experiment implementation and data analysis. Jing Wang and Xu Zhang: experiment implementation and data analysis. Ning Zhao, Kun Jia, Ming Yi, Qiu‐Xia Zhang: data collection and analysis. Hui Zhai and Xiao‐Wen Li: nerve conduction study. Chun‐Sheng Yang: manuscript revision. Li Yang: experimental design, manuscript revision. Lin‐Jie Zhang: experimental design, manuscript revision and data analysis. We would like to thank the study participants and the clinical care staff at the Tianjin Medical University General Hospital in this study.
ETHICS STATEMENT
This study was carried out in accordance with the recommendations of the Medical Research Ethics Committee at Tianjin Medical University General Hospital (Ethical no. IRB2020‐WZ‐200). All subjects provided written informed consent in accordance with the Declaration of Helsinki.
Supporting information
Table S1
ACKNOWLEDGEMENTS
This work was supported by the National Natural Science Foundation of China (81771363), the Natural Science Foundation of Tianjin (18JCQNJC81700).
Chang S‐H, Wang J, Zhang X, Zhao N, Jia K, Yi M, et al. The prevalence of anti‐neurofascin‐155 antibodies in patients with neuromyelitis optica spectrum disorders. Clin Exp Immunol. 2021;206:1–11. 10.1111/cei.13617
DATA AVAILABILITY STATEMENT
Data are available from the corresponding author on reasonable request.
REFERENCES
- 1.Weinshenker BG, Wingerchuk DM. Neuromyelitis spectrum disorders. Mayo Clin Proc. 2017;92:663–79. [DOI] [PubMed] [Google Scholar]
- 2.Lennon VA, Wingerchuk DM, Kryzer TJ, Pittock SJ, Lucchinetti CF, Fujihara K, et al. A serum autoantibody marker of neuromyelitis optica: distinction from multiple sclerosis. Lancet. 2004;364:2106–12. [DOI] [PubMed] [Google Scholar]
- 3.Wingerchuk DM, Banwell B, Bennett JL, Cabre P, Carroll W, Chitnis T, et al. International consensus diagnostic criteria for neuromyelitis optica spectrum disorders. Neurology 2015;85:177–89. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Wingerchuk DM, Lennon VA, Lucchinetti CF, Pittock SJ, Weinshenker BG. The spectrum of neuromyelitis optica. Lancet Neurol. 2007;6:805–15. [DOI] [PubMed] [Google Scholar]
- 5.van Pelt ED, Wong YYM, Ketelslegers IA, Hamann D, Hintzen RQ. Neuromyelitis optica spectrum disorders: comparison of clinical and magnetic resonance imaging characteristics of AQP4‐IgG versus MOG‐IgG seropositive cases in the Netherlands. Eur J Neurol. 2016;23:580–7. [DOI] [PubMed] [Google Scholar]
- 6.Hamid SHM, Whittam D, Mutch K, Linaker S, Solomon T, Das K, et al. What proportion of AQP4‐IgG‐negative NMO spectrum disorder patients are MOG‐IgG positive? A cross sectional study of 132 patients. J Neurol. 2017;264:2088–94. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Jasiak‐Zatonska M, Kalinowska‐Lyszczarz A, Michalak S, Kozubski W. The immunology of neuromyelitis optica – current knowledge, clinical implications, controversies and future perspectives. Int J Mol Sci. 2016;17:273. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Arancibia‐Carcamo IL, Attwell D. The node of Ranvier in CNS pathology. Acta Neuropathol. 2014;128:161–75. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9.Fehmi J, Scherer SS, Willison HJ, Rinaldi S. Nodes, paranodes and neuropathies. J Neurol Neurosurg Psychiatry. 2018;89:61–71. [DOI] [PubMed] [Google Scholar]
- 10.Ng JKM, Malotka J, Kawakami N, Derfuss T, Khademi M, Olsson T, et al. Neurofascin as a target for autoantibodies in peripheral neuropathies. Neurology 2012;79:2241–8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Kawamura N, Yamasaki R, Yonekawa T, Matsushita T, Kusunoki S, Nagayama S, et al. Anti‐neurofascin antibody in patients with combined central and peripheral demyelination. Neurology 2013;81:714–22. [DOI] [PubMed] [Google Scholar]
- 12.Mathey EK, Derfuss T, Storch MK, Williams KR, Hales K, Woolley DR, et al. Neurofascin as a novel target for autoantibody‐mediated axonal injury. J Exp Med. 2007;204:2363–72. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.Jia K, Zhang XU, Zhang L‐J, Li L‐M, Qi Y, Yi M, et al. Anti‐neurofascin‐155 antibody‐positive neuromyelitis optica spectrum disorders. J Neurol Sci. 2019;15:16–8. [DOI] [PubMed] [Google Scholar]
- 14.Thompson AJ, Banwell BL, Barkhof F, Carroll WM, Coetzee T, Comi G, et al. Diagnosis of multiple sclerosis: 2017 revisions of the McDonald criteria. Lancet Neurol. 2018;17:162–73. [DOI] [PubMed] [Google Scholar]
- 15.Hashimoto YU, Ogata H, Yamasaki R, Sasaguri T, Ko S, Yamashita K, et al. Chronic inflammatory demyelinating polyneuropathy with concurrent membranous nephropathy: an anti‐paranode and podocyte protein antibody study and literature survey. Front Neurol. 2018;9:997. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Yang LI, Maxwell S, Leite MI, Waters P, Clover L, Fan X, et al. Non‐radioactive serological diagnosis of myasthenia gravis and clinical features of patients from Tianjin, China. J Neurol Sci. 2011;301:71–6. [DOI] [PubMed] [Google Scholar]
- 17.Querol L, Nogales‐Gadea G, Rojas‐Garcia R, Diaz‐Manera J, Pardo J, Ortega‐Moreno A, et al. Neurofascin IgG4 antibodies in CIDP associate with disabling tremor and poor response to IVIg. Neurology. 2014;82:879–86. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 18.Yang C‐S, Zhang D‐Q, Wang J‐H, Jin W‐N, Li M‐S, Liu J, et al. Clinical features and sera anti‐aquaporin 4 antibody positivity in patients with demyelinating disorders of the central nervous system from Tianjin, China. CNS Neurosci Ther. 2014;20:32–9. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 19.Ogata H, Yamasaki R, Hiwatashi A, Oka N, Kawamura N, Matsuse D, et al. Characterization of IgG4 anti‐neurofascin 155 antibody‐positive polyneuropathy. Ann Clin Transl Neurol. 2015;2:960–71. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.Ogata H, Isobe N, Zhang XU, Yamasaki R, Fujii T, Machida A, et al. Unique HLA haplotype associations in IgG4 anti‐neurofascin 155 antibody‐positive chronic inflammatory demyelinating polyneuropathy. J Neuroimmunol. 2020;15:577139. [DOI] [PubMed] [Google Scholar]
- 21.Ogata H, Zhang XU, Yamasaki R, Fujii T, Machida A, Morimoto N, et al. Intrathecal cytokine profile in neuropathy with anti‐neurofascin 155 antibody. Ann Clin Transl Neurol. 2019;6:2304–16. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 22.Cortese A, Devaux JJ, Zardini E, Manso C, Taieb G, Carra Dallière C, et al. Neurofascin‐155 as a putative antigen in combined central and peripheral demyelination. Neurol Neuroimmunol Neuroinflamm. 2016;3:e238. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 23.Devaux JJ, Miura Y, Fukami Y, Inoue T, Manso C, Belghazi M, et al. Neurofascin‐155 IgG4 in chronic inflammatory demyelinating polyneuropathy. Neurology 2016;86:800–7. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 24.Kira J‐I, Yamasaki R, Ogata H. Anti‐neurofascin autoantibody and demyelination. Neurochem Int. 2019;130:104360. [DOI] [PubMed] [Google Scholar]
- 25.Vidarsson G, Dekkers G, Rispens T. IgG subclasses and allotypes: from structure to effector functions. Front Immunol. 2014;5:520. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 26.Howell OW, Palser A, Polito A, Melrose S, Zonta B, Scheiermann C, et al. Disruption of neurofascin localization reveals early changes preceding demyelination and remyelination in multiple sclerosis. Brain 2006;129:3173–85. [DOI] [PubMed] [Google Scholar]
- 27.Flytzani S, Guerreiro‐Cacais AO, N’diaye M, Lindner M, Linington C, Meinl E, et al. MOG‐induced experimental autoimmune encephalomyelitis in the rat species triggers anti‐neurofascin antibody response that is genetically regulated. J Neuroinflamm. 2015;29:194. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 28.Pittock SJ, Lennon VA, de Seze J, Vermersch P, Homburger HA, Wingerchuk DM, et al. Neuromyelitis optica and non organ‐specific autoimmunity. Arch Neurol. 2008;65:78–83. [DOI] [PubMed] [Google Scholar]
- 29.Yang C‐S, Zhang QX, Chang SH, Zhang LJ, Li LM, Qi Y, et al. Neuromyelitis optica spectrum disorders with and without connective tissue disorders. BMC Neurol. 2018;18:177. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 30.Vanderlugt CL, Miller SD. Epitope spreading in immune‐mediated diseases: implications for immunotherapy. Nat Rev Immunol. 2002;2:85–95. [DOI] [PubMed] [Google Scholar]
- 31.Kim S, Park J, Kwon BS, Park J‐W, Lee HJ, Choi J‐H, et al. Radiculopathy in neuromyelitis optica. How does anti‐AQP4 Ab involve PNS? Mult Scler Relat Disord. 2017;18:77–81. [DOI] [PubMed] [Google Scholar]
- 32.Gwathmey KG, Tracy JA, Dyck PJB. Peripheral nerve vasculitis: classification and disease associations. Neurol Clin. 2019;37:303–33. [DOI] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Table S1
Data Availability Statement
Data are available from the corresponding author on reasonable request.