Proteinuria is a key to suspect autoimmune nodopathies.

BACKGROUND AND PURPOSE: Reports of patients who have autoimmune nodopathies concurrent with nephrotic syndrome are increasing. We investigated whether proteinuria could be a biomarker of autoimmune nodopathies. METHODS: Qualitative urinalysis results were retrospectively obtained from 69 patients who were diagnosed with chronic inflammatory demyelinating polyneuropathy (CIDP) at a hospital in Japan. Proteinuria was graded as mild to severe (i.e., mild, 30-99; moderate, 100-299; severe, 300 mg/dL or more) according to the results of the urine dipstick test. Autoantibodies against the paranodal proteins contactin 1 (CNTN1), neurofascin 155 (NF155), and contactin-associated protein 1 (Caspr1) and the nodal protein neurofascin 186 (NF186) were measured, and the predominant IgG subclass was determined by enzyme-linked immunosorbent assay in sera from the 69 patients. RESULTS: Four patients (6%), five patients (7%), and one (1%) patient were positive for anti-CNTN1, anti-NF155, and anti-Caspr1 IgG4 antibodies, respectively. No patients had IgG4 antibodies against NF186. Proteinuria of mild or greater levels was found in three patients with anti-CNTN1 IgG4 and two patients with anti-NF155 IgG4 antibodies. The autoantibody-positive patients more frequently had proteinuria of mild or greater levels than the seronegative patients (p = 0.01). CONCLUSIONS: Proteinuria is a possible biomarker of autoimmune nodopathies associated with autoantibodies targeting CNTN1 or NF155. Urinalysis results should be carefully checked for quick differentiation of autoimmune nodopathies from CIDP. Patients who present with nephrotic syndrome should be tested for anti-CNTN1 IgG4 antibodies, and patients who exhibit mild proteinuria should be tested for anti-NF155 IgG4 antibodies.

Anti-neurofascin-155 antibody mediated a distinct phenotype of chronic inflammatory demyelinating polyradiculoneuropathy.

BACKGROUND: To investigate Ranvier's autoantibodies prevalence and isotypes in various peripheral neuropathy variants, compare clinical features between seronegative and seropositive patients, and elucidate immune mechanisms underlying antibody generation. METHODS: Antibodies against anti-neurofascin-155 (NF155), NF186, contactin-1 (CNTN1), CNTN2, contactin-associated protein 1 (CASPR1), and CASPR2 were identified through cell-based assays. Plasma cytokines were analyzed in anti-NF155 antibody-positive chronic inflammatory demyelinating polyneuropathy (NF155+ CIDP) and Ranvier's antibodies-negative CIDP (Ab- CIDP) patients using a multiplexed fluorescent immunoassay, validated in vitro in a cell culture model. RESULTS: In 368 plasma samples, 50 Ranvier's autoantibodies were found in 45 individuals, primarily in CIDP cases (25 out of 69 patients) and in 10 out of 122 Guillain-Barré syndrome patients. Anti-NF155 and CNTN1-IgG were exclusive to CIDP. Fourteen samples were NF155-IgG, primarily IgG4 subclass, linked to CIDP features including early onset, tremor, sensory disturbance, elevated CSF protein, prolonged motor latency, conduction block, and poor treatment response. NF155-IgG had low sensitivity (20.28%) but high specificity (100%) for CIDP, rising to 88.88% with tremor and prolonged motor latency. Cytokine profiling in NF155+ CIDP revealed distinct immune responses involving helper T cells, toll-like receptor pathways. Some NF155+ CIDP patients had circulating NF155-specific B cells producing NF155-IgG without antigen presence, suggesting therapeutic potential. CONCLUSION: The study emphasizes the high specificity and sensitivity of NF155-IgG for diagnosing CIDP characterized by distinctive features. Further investigation into circulating NF155-specific B cell phenotypes may pave the way for B cell directed therapy.

Clinical characteristics of patients with autoimmune nodopathy with anti-neurofascin155 antibodies.

Background: According to the latest guidelines on chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), patients with CIDP with anti-neurofascin 155 (NF155) antibodies are referred to as autoimmune nodopathy (AN), an autoimmune disorder distinct from CIDP. We aimed to compare the clinical data of patients with AN with anti-NF155 antibodies with those of anti-NF155 antibodies-negative patients with CIDP, and to summarize the clinical characteristics of patients with AN with anti-NF155 antibodies. Methods: Nine patients with AN with anti-NF155 antibodies and 28 serologically negative patients with CIDP were included in this study. Diagnosis was made according to the diagnostic criteria in the European Academy of Neurology (EAN)/Peripheral Nerve Society (PNS) guidelines on CIDP published in 2021. Demographics, clinical manifestations, electrophysiological examination, cerebrospinal fluid (CSF) tests, and response to treatment were retrospectively analyzed. Results: Compared with serologically negative patients with CIDP, those patients with AN with anti-NF155 antibodies were younger (p=0.007), had a younger onset age (p=0.009), more frequent ataxia (p=0.019), higher CSF protein levels (p=0.001), and more frequent axon damage in electrophysiology (p=0.025). The main characteristics of patients with AN with anti-NF155 antibodies include younger age and onset age, limb weakness, sensory disturbance, ataxia, multiple motor-sensory peripheral neuropathies with demyelination and axonal damage on electrophysiological examination, markedly elevated CSF protein levels, and varying degrees of response to immunotherapy. Conclusions: Patients with AN with anti-NF155 antibodies differed from serologically negative patients with CIDP in terms of clinical characteristics. When AN is suspected, testing for antibodies associated with the nodes of Ranvier is essential for early diagnosis and to guide treatment.

Low-dose rituximab treatment in a patient with anti-neurofascin-155 IgG4 autoimmune nodopathy.

Autoimmune nodopathy is a new entity of immune-mediated neuropathies associated with antibodies against nodal-paranodal epitopes. We present a detailed clinical and serological work-up of a patient with autoimmune nodopathy with anti-neurofascin-155 (anti-NF-155) IgG4 antibodies who was treated with low-dose (500 mg) rituximab, which led to a decrease of anti-NF-155 antibody titer, depletion of B cells, normalization of the levels of neurofilament light chain in serum, and significant clinical improvement. This case suggests that a low-dose rituximab could be as effective as previously reported much higher doses, and presumably with a lower risk of adverse effects and infections.

Anti-pan-neurofascin nodopathy: cause of fulminant neuropathy.

Autoimmune nodopathies are inflammatory diseases of the peripheral nervous system with clinical and neurophysiological peculiar characteristics. In this nosological category, we find patients with autoantibodies against Neurofascin 140/186 and 155, Contactin1, and Caspr1 directed precisely towards nodal and paranodal structures. These antibodies are extremely rare and cause severe clinical symptoms. We describe the clinical case of a patient with autoimmune nodopathy caused by the coexistence of anti-neurofascin (NF) 186/140 and 155, characterized by progressive weakness in all limbs leading to tetraplegia, involving cranial nerves, and respiratory insufficiency. Response to first-line treatments was good followed by rapid dramatic clinical relapse. There are few reported cases of anti-pan NF neuropathy in the literature, and they present a clinical phenotype similar to our patient. In these cases, early recognition of clinical red flags of nodopathies and serial neurophysiological studies can facilitate the diagnosis. However, the severe clinical relapse suggests a possible early use of immunosuppressive therapies for this rare category of patients.

Anti-neurofascin 155 Antibody-positive Neuropathy in a Human Immunodeficiency Virus-infected Patient.

Human immunodeficiency virus (HIV)-associated neuropathy is a common complication of HIV infection and has several clinical subtypes. HIV-associated chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a demyelinating neuropathy whose clinical features are known to differ from those of CIDP in the HIV-uninfected population. We herein report a case of CIDP in an HIV-infected patient who was finally diagnosed with anti-neurofascin 155 (NF155) antibody-positive neuropathy. The clinical features, including clinical findings and therapeutic responses, were typical of paranodal antibody-mediated neuropathy. To our knowledge, this is the first case of anti-NF155 antibody-associated neuropathy in an HIV-infected patient.

Autoimmune paranodopathy / 中华神经科杂志

Autoimmune paranodopathy (APN) has emerged as an independent rare disease,which is medicated by autoimmune antibodies against the essential complex of paranodal region of Ranvier. The antibodies include anti-neurofascin 155 antibody, anti-contactin-1 antibody and anti-contactin-associated protein 1 antibody. Although there are many similarities between APN and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), patients with APN have relatively unique clinical features, pathogenesis, histopathological results and responses to intravenous immune globulin, distinguishing from typical CIDP. The predominant subclass of IgG among pathogenic antibodies is IgG4, meanwhile, other subclasses have been rarely reported. Early detecting the APN related antibodies and their subclasses not only helps to clarify the diagnosis, but also provides valuable clinical information for the selection of precise treatment and prognosis.

Case Report: Telitacicept in treating a patient with NF155+ autoimmune nodopathy: a successful attempt to manage recurrent elevated sero-anti-NF155 antibodies.

This report presents a case of a neurofascin-155 (NF155)+ autoimmune nodopathy (AN) patient who exhibited resistance to conventional treatments but responded positively to telitacicept therapy. Telitacicept, a dual inhibitor of B lymphocyte stimulator (BLyS) and A proliferation-inducing ligand (APRIL), suppressed the development and survival of plasma cells and mature B cells. The patient's unique clinical features were consistent with NF155+ AN, showing limited response to standard treatments like rituximab and a recurrent significant increase in anti-NF155 antibody titers. Administering telitacicept (160mg, ih) led to an improvement in clinical symptoms, inflammatory neuropathy cause and treatment (INCAT) scale and inflammatory Rasch-built overall disability scale (I-RODS), and stabilized anti-NF155 antibody levels without a rebound. This case demonstrates telitacicept as a potential novel therapy for NF155+ AN, particularly when conventional treatments fail. Further investigation into its safety, efficacy, dosage, and treatment cycle in NF155+ AN is warranted.

Anti-rituximab antibodies in patients with refractory autoimmune nodopathy with anti-neurofascin-155 antibody.

Background: Recent studies have reported that similar to other IgG4 autoimmune diseases, such as muscle-specific kinase antibody-associated myasthenia gravis, most anti-neurofascin-155 (anti-NF155) nodopathies respond well to rituximab treatment, regardless of the dosage. However, there are still a few patients for which rituximab is ineffective for unknown reasons. Currently, there are no studies on the mechanism of ineffective treatment with rituximab. Methods: A 33-year-old Chinese man presenting with numbness, tremor, and muscle weakness for 4 years was recruited for this study. Anti-NF155 antibodies were identified by cell-based assay and confirmed by immunofluorescence assay on teased fibers. The anti-NF155 immunoglobulin (IgG) subclasses were also detected by immunofluorescence assay. Anti-rituximab antibodies (ARAs) were quantitatively analyzed using enzyme-linked immunosorbent assay (ELISA), and peripheral B cell counts were determined by flow cytometry. Results: The patient exhibited anti-NF155 IgG4-antibody positivity. After the first round of rituximab infusion, the patient showed stratified outcomes with improvements in numbness, muscle weakness and ambulation. However, after three rounds of rituximab infusion, the patient's symptoms deteriorated, and the numbness, tremor and muscle weakness returned. No obvious improvement was found after plasma exchange and another round of rituximab treatment. 14 days after the last treatment with rituximab, ARAs were detected. And the titers gradually decreased on day 28 and 60 but remained higher than normal. Peripheral CD19+ B cell counts were less than 1% within the 2-month period following the final rituximab administration. Conclusions: In this study, ARAs presented in a patient with anti-NF155 nodopathy undergoing rituximab treatment and showed an unfavorable impact on rituximab efficacy. This is the first case to report the occurrence of ARAs in patients with anti-NF155 antibodies. We suggest that ARAs should be tested early during the initial intervention, especially in patients who respond poorly to rituximab treatment. In addition, we believe it is necessary to investigate the association between ARAs and B cell counts, their effect on clinical efficacy, and their potential adverse reactions in a larger cohort of patients with anti-NF155 nodopathy.

Growing Spectrum of Autoimmune Nodopathies.

PURPOSE OF REVIEW: Recognition of node of Ranvier as the site of injury in inflammatory neuropathies contributed to discovery of antibodies against the nodal/paranodal structures. These antibodies mediate a unique type of inflammatory neuropathies that are different from typical chronic inflammatory demyelinating polyneuropathy. This review discusses the advancements made in the field of autoimmune neuropathies secondary to antibodies to nodal and paranodal proteins. RECENT FINDINGS: Neuropathies caused by antibodies to nodal-paranodal antigens including neurofascin 186, neurofascin 155, contactin1, and contactin-associated protein1 were termed as autoimmune nodopathies (AN) in 2021. Since the initial description almost a decade ago, newer cohorts have expanded the clinical spectrum of AN. In addition to IgG4, other subclasses of IgG such as IgG1/IgG3 have been identified, particularly in relation to acute presentations and anti-pan neurofascin antibody disease. In vitro and in vivo studies have also supported antibody-mediated pathogenicity of many of these biomarkers. Antibodies to nodal-paranodal antigens have emerged as a biomarker for a novel type of immune-mediated neuropathies. These antibodies have distinct pathogenic mechanisms and produce a unique set of clinicopathologic features. Their clinical profile and treatment may also vary depending on the antibody isotype. B cell depleting therapies are effective in managing some of these patients.

Polirradiculoneuropatía desmielinizante inflamatoria crónica con anticuerpos antineurofascina-155: primer reporte de caso en Perú / Chronic inflammatory demyelinating polyradiculoneuropathy with antineurofascin-155 antibodies: A first case report in Peru

La polirradiculoneuropatía desmielinizante inflamatoria crónica, es un grupo de neuro-patías periféricas inmunomediadas clínicamente heterogéneas que comparten manifes-taciones neurofisiológicas de desmielinización y disociación albuminocitológica. Se distinguen una forma típica y variantes atípicas, algunas asociadas a anticuerpos con-tra proteínas del nodo de Ranvier, como la neurofascina- 155. Presentamos el caso de un varón de 38 años, que acudió por cuadro de ocho meses de evolución, caracterizado por parestesias y debilidad progresiva de cuatro extremidades, asociado a diplopía y disfagia. El paciente estaba despierto, con cuadriparesia flácida simétrica de predominio distal, hipotrofia en dorso y palma de ambas manos, arreflexia generalizada, temblor postural de baja frecuencia y alta amplitud en miembros superiores de predominio izquierdo, dismetría apendicular, adiadococinesia, oftalmoparesia a la dextroversión en ojo dere-cho, reflejo nauseoso ausente, marcha atáxica con aumento de base de sustentación y signo de Romberg positivo. El líquido cefalorraquideo mostró disociación albuminocitológica y la electromiografía fue compatible con polineuropatía sensitivo- motora primariamente desmielinizante. Por la sospecha clínica, solicitamos anticuerpos antineurofascina- 155, que resultaron positivos. Recibió tratamiento con metilprednisolona a dosis de un gramo al día durante cinco días, seguido de un miligramo por kilogramo durante tres meses de prednisona, con disminución progresiva con lo que mejoró la diplopía y la disfagia, sin mejoría de la fuerza en extremidades e incluso empeoramiento de la funcionabilidad. Por esta razón se inició tratamiento con rituximab en dosis de dos gramos presentando una notable mejoría en la fuerza muscular distal, el temblor, la estabilidad de la marcha, coordinación y de su funcionabilidad medida con la escala de Rankin modificado.

Chronic inflammatory demyelinating polyradiculoneuropathy is a clinically heterogeneous group of immune- mediated peripheral neuropathies that share neurophysiological manifesta-tions of demyelination and albuminocytologic dissociation. There are typical and atypical variants of this disease, some associated with antibodies against proteins of the node of Ranvier, such as neurofascin- 155. We present the case of a 38- year- old male who presented with an eight- month history of par-esthesia and progressive weakness of four limbs associated with diplopia and dysphagia. The patient was conscious, with symmetric flaccid quadriparesis of distal predominance, hyp-otrophy in the dorsum and palm of both hands, generalized areflexia, postural low frequency, and high amplitude tremor in upper limbs of left predominance, appendicular dysmetria, dys-diadochokinesia, ophthalmoparesis to dextroversion in the right eye, absent gag reflex, ataxic gait with an increased base of support and positive Romberg's sign. Cerebrospinal fluid showed albuminocytologic dissociation, and electromyography was com-patible with primarily demyelinating sensory- motor polyneuropathy. Due to clinical suspicion, we requested anti- neurofascin- 155 antibodies, which tested positive. The patient was treated with methylprednisolone at a dose of one gram per day for five days, followed by one milligram per kilogram for three months of prednisone, with progressive de-crease, which improved diplopia and dysphagia, with no effect on limb strength and even worsening of function. For this reason, treatment with rituximab was started in doses of two grams, presenting a substantial improvement in distal muscle strength, tremor, gait stability, coordination, and functionality measured with the modified Rankin scale.

Chronic inflammatory demyelinating polyradiculoneuropathy with antineurofascin-155 antibodies: A first case report in Peru. / Polirradiculoneuropatía desmielinizante inflamatoria crónica con anticuerpos antineurofascina-155: primer reporte de caso en Perú.

Chronic inflammatory demyelinating polyradiculoneuropathy is a clinically heterogeneous group of immune- mediated peripheral neuropathies that share neurophysiological manifesta-tions of demyelination and albuminocytologic dissociation. There are typical and atypical variants of this disease, some associated with antibodies against proteins of the node of Ranvier, such as neurofascin- 155. We present the case of a 38- year- old male who presented with an eight- month history of par-esthesia and progressive weakness of four limbs associated with diplopia and dysphagia. The patient was conscious, with symmetric flaccid quadriparesis of distal predominance, hyp-otrophy in the dorsum and palm of both hands, generalized areflexia, postural low frequency, and high amplitude tremor in upper limbs of left predominance, appendicular dysmetria, dys-diadochokinesia, ophthalmoparesis to dextroversion in the right eye, absent gag reflex, ataxic gait with an increased base of support and positive Romberg's sign. Cerebrospinal fluid showed albuminocytologic dissociation, and electromyography was com-patible with primarily demyelinating sensory- motor polyneuropathy. Due to clinical suspicion, we requested anti- neurofascin- 155 antibodies, which tested positive. The patient was treated with methylprednisolone at a dose of one gram per day for five days, followed by one milligram per kilogram for three months of prednisone, with progressive de-crease, which improved diplopia and dysphagia, with no effect on limb strength and even worsening of function. For this reason, treatment with rituximab was started in doses of two grams, presenting a substantial improvement in distal muscle strength, tremor, gait stability, coordination, and functionality measured with the modified Rankin scale.

La polirradiculoneuropatía desmielinizante inflamatoria crónica, es un grupo de neuro-patías periféricas inmunomediadas clínicamente heterogéneas que comparten manifes-taciones neurofisiológicas de desmielinización y disociación albuminocitológica. Se distinguen una forma típica y variantes atípicas, algunas asociadas a anticuerpos con-tra proteínas del nodo de Ranvier, como la neurofascina- 155. Presentamos el caso de un varón de 38 años, que acudió por cuadro de ocho meses de evolución, caracterizado por parestesias y debilidad progresiva de cuatro extremidades, asociado a diplopía y disfagia. El paciente estaba despierto, con cuadriparesia flácida simétrica de predominio distal, hipotrofia en dorso y palma de ambas manos, arreflexia generalizada, temblor postural de baja frecuencia y alta amplitud en miembros superiores de predominio izquierdo, dismetría apendicular, adiadococinesia, oftalmoparesia a la dextroversión en ojo dere-cho, reflejo nauseoso ausente, marcha atáxica con aumento de base de sustentación y signo de Romberg positivo. El líquido cefalorraquideo mostró disociación albuminocitológica y la electromiografía fue compatible con polineuropatía sensitivo- motora primariamente desmielinizante. Por la sospecha clínica, solicitamos anticuerpos antineurofascina- 155, que resultaron positivos. Recibió tratamiento con metilprednisolona a dosis de un gramo al día durante cinco días, seguido de un miligramo por kilogramo durante tres meses de prednisona, con disminución progresiva con lo que mejoró la diplopía y la disfagia, sin mejoría de la fuerza en extremidades e incluso empeoramiento de la funcionabilidad. Por esta razón se inició tratamiento con rituximab en dosis de dos gramos presentando una notable mejoría en la fuerza muscular distal, el temblor, la estabilidad de la marcha, coordinación y de su funcionabilidad medida con la escala de Rankin modificado.

Characterization of the patients with antibodies against nodal-paranodal junction proteins in chronic inflammatory demyelinating polyneuropathy.

OBJECTIVE: Antibodies against nodal-paranodal junction proteins have been detected in some patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), which is a crucial step to define the most effective treatment strategies. In this paper, we tested the positive rates of these antibodies in CIDP and characterized the clinical and electrophysiological features of the antibodies-positive patients. METHODS: We prospectively recruited 47 patients with CIDP. We detected IgG antibodies against human neurofascin-155 (NF155), neurofascin-186 (NF186), contactin-1 (CNTN1), contactin-2 (CNTN2) and contactin-associated protein-1 (Caspr1), and identified the IgG isotype with cell-based assay (CBA). We collected the demographic, clinical, laboratory, and electrophysiological information of the patients that were seropositive. RESULTS: Five patients (10.6 %) had IgG against NF155, 3 (6.4 %) against Caspr1, 2 (4.3 %) against NF186 and 1 (2.1 %) against CNTN1. All the 11 antibody-positive patients (8 males and 3 females) presented with typical clinical features. Five of them needed assistance in walking, 5 had cranial nerve impairments and 3 had autonomic disturbances. The age at onset of the patients that were anti-NF155-positive was younger (19.60 ± 9.02 years vs. 55.33 ± 11.93 years, P = 0.003) than those that were anti-Caspr1-positive. No significant difference in the functional status was observed between these two groups. The action potentials of 11/79 (13.9 %) motor nerves and 62/93 (66.7 %) sensory nerves exhibited no response. Moreover, 16/68 (23.5 %) nerves presented conduction block and 13/68 (19.1 %) nerves presented temporal dispersion. Distal motor latency (DML) of ulnar nerve and tibial nerve tended to be longer (p = 0.008 and p = 0.006, respectively) in anti-NF155-positive patients than that in anti-Caspr1-positive patients. Of the 11 patients that were antibody-positive patients, corticosteroids were effective in 3/7 (42.9 %), intravenous immunoglobins (IVIG) were effective in 1/7 (14.3 %), and rituximab was effective in 6/8 (75.0 %). CONCLUSIONS: Our findings validate the previous observation on the clinico-serological correlation between CIDP and antibodies against nodal-paranodal proteins. Of note, the damage on nerves is more severe in anti-NF155-positive patients than that in anti-Caspr1-positive patients during electrophysiological diagnosis.

Anti-NF155/NF186 IgG4 Antibody Positive Autoimmune Nodopathy.

Patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) seropositive for autoantibodies against nodal and paranodal proteins display distinct clinical presentations. In the latest study, CIDP with autoantibodies against paranodal proteins was defined as autoimmune nodopathy (AN). We herein present a case of 39-year-old male with anti- neurofascin (NF) 155 and NF186 IgG4 antibody with gait disturbance and tremor, who was followed up for 4 months and demonstrated clinical improvements after apparently effective rituximab therapy. In addition, a literature review was conducted to investigate the clinical characteristics of anti-NF155/NF186-positive AN.

Case report: Autoimmune nodopathy with concurrent serum and CSF IgG4 anti-neurofascin 155 antibodies.

Objective: To report a case of autoimmune nodopathy (AN) with concurrent serum and CSF immunoglobulin (Ig)G4 anti-neurofascin 155 (NF155) and anti-GD1b antibodies. Methods: A 20-year-old male presented distal weakness of the 4 limbs, hypoesthesia, absent tendon reflexes and sensory ataxia. Nerve conduction studies (NCS), MRI, and autoantibody tests were performed. Results: NCS revealed a diffuse demyelinating neuropathy in the peripheral nerve with motor and sensory involvement. MRI of the cervical and lumbar plexus showed diffuse enlargement. IgG4 anti-NF155 antibodies in both serum and CSF and IgG anti-GD1b antibodies in serum were positive. After treatment with IVIg, rituximab, and plasma exchange, the titer of the patient's anti-NF155 antibodies decreased, but symptoms did not significantly improve. Discussion: This patient presented a typical clinical feature of AN with serum and CSF anti-NF155 antibodies and serum anti-GD1b antibodies coexistent but poor response to IVIg, rituximab and plasma exchange. Early detection of antibodies may be helpful in both diagnosis and therapy of the disease. And prospective studies are necessary to demonstrate the potential role of anti-NF155 antibodies in CSF and help further understand this complex and heterogeneous disease.

Clinical features of Guillain-Barré syndrome with anti-neurofascin 155 antibody.

OBJECTIVE: Anti-neurofascin 155 (NF155) antibody has been discovered in chronic demyelinating conditions. However, the positive rate and clinical description were insufficient in acute demyelinating conditions, such as Guillain-Barré syndrome (GBS). This study aimed to explore the positive rate of anti-NF155 antibody in GBS patients and determine whether there were unique clinical characteristics in these patients. MATERIALS & METHODS: Serum anti-NF155 antibody was detected from 94 GBS patients and 50 sex- and age-matched healthy controls using cell-based assay and tissue-based assay with immunostaining of mouse teased sciatic nerve fibers. Clinical characteristics, laboratory data, and electrophysiology examinations were retrospectively collected. RESULTS: Seven of 94 (7.45%) GBS patients were positive for anti-NF155 antibody, and the main IgG subclass was IgG1. Compared with anti-NF155 antibody-negative GBS patients, anti-NF155 antibody-positive GBS patients had a higher GBS disability score at nadirs (p = .010), higher modified Erasmus GBS outcome score (p = .022), higher rate of abnormal compound motor action potential (CMAP) amplitude (p = .002), higher frequency of prolonged F-wave latency (p < .001), lower frequency of abnormal sensory conduction velocity (p < .001) and sensory nerve action potential amplitude (p < .001), more axonal type (p = .040), and poorer therapeutic effect (p = .017). CONCLUSIONS: Anti-NF155 antibody exists in a small portion of GBS patients. Anti-NF155 antibody-positive GBS patients possibly have a more severe clinical course, less sensory nerves involved, higher proportion of axonal type, poorer therapeutic effect, and worse prognosis, but the pathogenicity of the anti-NF155 antibody in GBS needs further study.

Blood-nerve barrier disruption and coagulation system activation induced by mechanical compression injury participate in the peripheral sensitization of trigeminal neuralgia.

Introduction: The aim of this study was to investigate the effect and possible mechanisms of the blood-nerve barrier (BNB) and the coagulation-anticoagulation system in modulating the mechanical allodynia in a trigeminal neuralgia (TN) rat model induced by chronic compression of the trigeminal root entry zone (TREZ). Methods: Von Frey filaments were applied to determine the orofacial mechanical allodynia threshold. The BNB permeability was evaluated by Evans blue extravasation test. Immunohistochemical staining and laser confocal microscopy were used to measure the length of the depletion zones of the nodes of Ranvier in the TREZ, the diameter of nerve fibers and the length of the nodal gap. The transcriptional levels of prothrombin and endogenous thrombin inhibitor protease nexin-1 (PN-1) in the TREZ of TN rats were assessed by RT-qPCR. A Western blotting assay was performed to detect the expression of paranodal proteins neurofascin-155 (NF155) and neurofascin-125 (NF125) in the TREZ. The spatiotemporal expression pattern of thrombin activated receptor (i.e. protease activated receptor 1, PAR1) in TREZ were defined by immunostaining and immunoblotting assays. PAR1 receptor inhibitors SCH79797 were administrated to TN rats to analyze the effect of thrombin-PAR1 on orofacial hyperalgesia. Results: A compression injury of a rat's TREZ successfully induced TN-like behavior and was accompanied by the destruction of the permeability of the BNB and the promotion of prothrombin and thrombin inhibitor protease nexin-1 (PN-1) expression. The expression of the paranodal proteins neurofascin-155 (NF155) and neurofascin-125 (NF125) was increased, while the nodal gap length of the nodes of Ranvier was widened and the length of node-depleted zones was shortened. Moreover, the expression of PAR1 within the TREZ was upregulated at an early stage of TN, and administration of the PAR1 antagonist SCH79797 effectively ameliorated orofacial mechanical allodynia. Conclusion: A compression injury of the TREZ increased the permeability of the BNB and induced disturbances in the local coagulation-anticoagulation system, concomitant with the structural changes in the nodes of Ranvier, thrombin-PAR1 may play a critical role in modulating orofacial mechanical hyperalgesia in a TN rat model.

Optic Nerve Demyelination in IgG4 Anti-Neurofascin 155 Antibody-Positive Combined Central and Peripheral Demyelination Syndrome.

Optic nerve demyelination is one of the clinical features of combined central and peripheral demyelination (CCPD), an entity with heterogenous immunopathogenesis and clinical characteristics, overlapping between multiple sclerosis (MS) and chronic inflammatory demyelinating polyneuropathy (CIDP). Of interest, earlier studies among patients with CIDP prior to discovery of antibodies against paranodal protein neurofascin 155 (anti-NF 155) also reported optic nerve dysfunction. We aimed to evaluate optic nerve demyelination among anti-NF 155 CIDP patients. We studied 2 patients with anti-NF 155 CIDP using visual-evoked potentials (VEP) and optical coherence tomography (OCT). Both patients had distal acquired demyelinating symmetric (DADS) subtype CIDP. Other common features were prominent sensory ataxia, hand tremors, significantly elevated cerebral spinal fluid protein, high titre anti-NF 155 antibodies and poor response to corticosteroid and intravenous immunoglobulin (IVIg). No central nervous system neuroradiological abnormality detected. Both had normal visual acuity and colour vision, but one had subclinical right relative afferent pupillary defect (RAPD). VEP of both showed bilateral prolonged P100 latencies. OCT for patient with RAPD demonstrated moderate to severe retinal nerve fibre layer (RNFL) thinning. Identification of optic nerve demyelination among subclinical CIDP with anti-NF 155 antibodies expanded the spectrum of demyelination within the subset of CCPD.

Anti-Neurofascin 155 Antibody-Positive Chronic Inflammatory Demyelinating Polyneuropathy/Combined Central and Peripheral Demyelination: Strategies for Diagnosis and Treatment Based on the Disease Mechanism.

Chronic inflammatory demyelinating polyneuropathy (CIDP) is an immune-mediated demyelinating disease of the peripheral nervous system (PNS). A small number of CIDP patients harbors autoantibodies against nodal/paranodal proteins, such as neurofascin 155 (NF155), contactin 1, and contactin-associated protein 1. In most cases, the predominant immunoglobulin (IgG) subclass is IgG4. Node/paranode antibody-positive CIDP demonstrates distinct features compared with antibody-negative CIDP, including a poor response to intravenous immunoglobulin. The neuropathology of biopsied sural nerve shows Schwann cell terminal loop detachment from axons without macrophage infiltration or inflammation. This is partly attributable to IgG4, which blocks protein-protein interactions without inducing inflammation. Anti-NF155 antibody-positive (NF155+) CIDP is unique because of the high frequency of subclinical demyelinating lesions in the central nervous system (CNS). This is probably because NF155 coexists in the PNS and CNS. Such cases showing demyelinating lesions in both the CNS and PNS are now termed combined central and peripheral demyelination (CCPD). NF155+ CIDP/CCPD commonly presents hypertrophy of spinal nerve roots and cranial nerves, such as trigeminal and oculomotor nerves, and extremely high levels of cerebrospinal fluid (CSF) protein, which indicates nerve root inflammation. In the CSF, the CXCL8/IL8, IL13, TNFα, CCL11/eotaxin, CCL2/MCP1, and IFNγ levels are significantly higher and the IL1ß, IL1ra, and GCSF levels are significantly lower in NF155+ CIDP than in non-inflammatory neurological diseases. Even compared with anti-NF155 antibody-negative (NF155-) CIDP, the CXCL8/IL8 and IL13 levels are significantly higher and the IL1ß and IL1ra levels are significantly lower than those in NF155+ CIDP. Canonical discriminant analysis revealed NF155+ and NF155- CIDP to be separable with IL4, IL10, and IL13, the three most significant discriminators, all of which are required for IgG4 class switching. Therefore, upregulation of both Th2 and Th1 cytokines and downregulation of macrophage-related cytokines are characteristic of NF155+ CIDP, which explains spinal root inflammation and the lack of macrophage infiltration in the sural nerves. All Japanese patients with NF155+ CIDP/CCPD have one of two specific human leukocyte antigen (HLA) haplotypes, which results in a significantly higher prevalence of HLA-DRB1 * 15:01-DQB1 * 06:02 compared with healthy Japanese controls. This indicates an involvement of specific HLA class II molecules and relevant T cells in addition to IgG4 anti-NF155 antibodies in the mechanism underlying IgG4 NF155+ CIDP/CCPD.