Optic, trigeminal, and facial neuropathy related to anti-neurofascin 155 antibody

Antibody-Mediated Nodo- and Paranodopathies

The recent discovery of pathogenic antibodies targeting cell adhesion molecules of the node of Ranvier has prompted efforts to develop a new classification for a subset of antibody-mediated peripheral neuropathies. These autoimmune nodo- and paranodopathies encompass epitopes such as neurofascin 155, neurofascin 186, contactin-1, and contactin-associated protein 1, with a high likelihood of involving additional yet unidentified proteins. So far, the investigation of this subset of patients was primarily focused on adults, with only rare reports of pediatric cases. Low awareness among pediatricians and insufficient availability of appropriate diagnostic methods in many laboratories may mask a higher pediatric incidence than currently observed. Diagnosis is made by transfected cell-based assays and ELISA to characterize the specific target antigen and antibody subclass that provides insight into the pathophysiology. Clinical features often resemble those of CIDP or GBS in adults, whilst in pediatric patients, although rare, an atypical CIDP phenotype has predominantly been reported. Yet, in contrast to classical immune-mediated neuropathies, the clinical course is usually rapidly progressive, and response to classical first-line therapy often poor. Although electrophysiological signs of demyelination are observed, segmental demyelination and inflammation are not present on pathological examination. Rather, few neuropathological reports demonstrate features of axonal neuropathy without signs of true de- or remyelination. This review aims to summarize recent findings on such nodo- and paranodoneuropathies, shining light on features of these disorders in pediatric patients, a still little-explored field with only a few reports currently present.

A nationwide survey of facial onset sensory and motor neuronopathy in Japan

The epidemiology and etiology of facial onset sensory and motor neuronopathy (FOSMN), a rare syndrome that initiates with facial sensory disturbances followed by bulbar symptoms, remain unknown. To estimate the prevalence of FOSMN in Japan and establish the characteristics of this disease, we conducted a nationwide epidemiological survey. In the primary survey, we received answers from 604 facilities (49.8%), leading to an estimated number of 35.8 (95% confidential interval: 21.5-50.2) FOSMN cases in Japan. The secondary survey collected detailed clinical and laboratory data from 21 cases. Decreased or absent corneal and pharyngeal reflexes were present in over 85% of the cases. Electrophysiological analyses detected blink reflex test abnormalities in 94.1% of the examined cases. Immunotherapy was administered in 81% of cases and all patients received intravenous immunoglobulin. Among them, 35.3% were judged to have temporary beneficial effects evaluated by the physicians in charge. Immunotherapy tended to be effective in the early stage of disease. The spreading pattern of motor and sensory symptoms differed between cases and the characteristics of the motor-dominant and sensory-dominant cases were distinct. Cases with motor-dominant progression appeared to mimic amyotrophic lateral sclerosis. This is the first nationwide epidemiological survey of FOSMN in Japan. The clinical course of FOSMN is highly variable and motor-dominant cases developed a more severe condition than other types of cases. Because clinical interventions tend to be effective in the early phase of the disease, an early diagnosis is desirable.

Aggressive Acquired Demyelinating Neuropathy Caused by NF-155: Initially Treatment-Resistant

OBJECTIVES

Anti-neurofascin-155 IgG4 (NF-155) antibody disease has previously been associated with a subset of patients with chronic inflammatory demyelinating polyradiculoneuropathy. We report a case of NF-155 positive polyneuropathy that initially presented as an acute inflammatory demyelinating polyradiculoneuropathy. The patient responded appropriately to treatment but subsequently progressed over a 3-month period, resulting in quadriplegia, areflexia, and oculobulbar paralysis.

METHODS

Case report and literature review.

RESULTS

A 40-year-old male presented with acute bilateral arm and thigh weakness, areflexia, and distal sensory loss. Treatment with intravenous immunoglobulin (IVIg) for acute acquired demyelinating neuropathy resulted in initial improvement but subsequent decline. Lack of response to additional IVIg and plasmapheresis (PLEX) prompted testing for NF-155. Treatment with rituximab and steroids resulted in virtually complete recovery.

CONCLUSIONS

Early testing for nodal and paranodal proteins is indicated in patients who present with acute acquired demyelinating neuropathy but fail to respond to conventional treatments, such as IVIg or PLEX. Identification of nodal and paranodal antibodies should prompt treatment with rituximab and steroids to increase likelihood of recovery.

[The significance of autoantibodies against nodal and paranodal proteins in autoimmune nodopathies]

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is recognized as a syndrome caused by multiple pathologies. Since the 2010s, it has been clarified that autoantibodies against membranous proteins localized in the nodes of Ranvier and paranodes are positive in subsets of CIDP patients, leading to proposing a new disease concept called autoimmune nodopathies, which is independent of CIDP, in the revised international CIDP guidelines. This article reviews the significance of these autoantibodies, especially anti-neurofascin 155 and anti-contactin 1 antibodies, which have been the most prevalent and achieved a higher degree of consensus.

Anti-LGI4 Antibody Is a Novel Juxtaparanodal Autoantibody for Chronic Inflammatory Demyelinating Polyneuropathy

BACKGROUND AND OBJECTIVES

The objective of this study was to discover novel nodal autoantibodies in chronic inflammatory demyelinating polyneuropathy (CIDP).

METHODS

We screened for autoantibodies that bind to mouse sciatic nerves and dorsal root ganglia (DRG) using indirect immunofluorescence (IFA) assays with sera from 113 patients with CIDP seronegative for anti-neurofascin 155 and anticontactin-1 antibodies and 127 controls. Western blotting, IFA assays using HEK293T cells transfected with relevant antigen expression plasmids, and cell-based RNA interference assays were used to identify target antigens. Krox20 and Periaxin expression, both of which independently control peripheral nerve myelination, was assessed by quantitative real-time PCR after application of patient and control sera to Schwann cells.

RESULTS

Sera from 4 patients with CIDP, but not control sera, selectively bound to the nodal regions of sciatic nerves and DRG satellite glia (p = 0.048). The main immunoglobulin G (IgG) subtype was IgG4. IgG from these 4 patients stained a 60-kDa band on Western blots of mouse DRG and sciatic nerve lysates. These features indicated leucine-rich repeat LGI family member 4 (LGI4) as a candidate antigen. A commercial anti-LGI4 antibody and IgG from all 4 seropositive patients with CIDP showed the same immunostaining patterns of DRG and cultured rat Schwann cells and bound to the 60-kDa protein in Western blots of LGI4 overexpression lysates. IgG from 3 seropositive patients, but none from controls, bound to cells cotransfected with plasmids containing LGI4 and a disintegrin and metalloprotease domain-containing protein 22 (ADAM22), an LGI4 receptor. In cultured rat Schwann and human melanoma cells constitutively expressing LGI4, LGI4 siRNA effectively downregulated LGI4 and reduced patients' IgG binding compared with scrambled siRNA. Application of serum from a positive patient to Schwann cells expressing ADAM22 significantly reduced the expression of Krox20, but not Periaxin. Anti-LGI4 antibody-positive patients had a relatively old age at onset (mean age 58 years), motor weakness, deep and superficial sensory impairment with Romberg sign, and extremely high levels of CSF protein. Three patients showed subacute CIDP onset resembling Guillain-Barré syndrome.

DISCUSSION

IgG4 anti-LGI4 antibodies are found in some elderly patients with CIDP who present subacute sensory impairment and motor weakness and are worth measuring, particularly in patients with symptoms resembling Guillain-Barré syndrome.

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.

Neurofascin-155 Immunoglobulin Subtypes: Clinicopathologic Associations and Neurologic Outcomes

BACKGROUND AND OBJECTIVE

Multiple studies highlighting diagnostic utility of neurofascin 155 (NF155)-IgG4 in chronic demyelinating inflammatory polyradiculoneuropathy (CIDP) have been published. However, few studies comprehensively address the long-term outcomes, or clinical utility of NF155-IgM or NF155-IgG, in the absence of NF155-IgG4. In this study we evaluate phenotypic and histopathological specificity, and differences in outcomes between these NF155 antibody isotypes or IgG subclasses. We also compare NF155-IgG4 seropositive cases to other seropositive demyelinating neuropathies.

METHODS

In this study, neuropathy patient sera seen at Mayo Clinic were tested for NF155-IgG4, NF155-IgG and NF155-IgM autoantibodies. Demographic and clinical data of all seropositive cases were reviewed.

RESULTS

We identified 32 NF155 patients (25 NF155-IgG positive [20 NF155-IgG4 positive], 7 NF155-IgM seropositive). NF155-IgG4 seropositive patients clinically presented with distal more than proximal muscle weakness, positive sensory symptoms (prickling, asymmetric paresthesia, neuropathic pain) and gait ataxia. Cranial nerve involvement (11/20, 55%) and papilledema (4/12, 33%) occurred in many. Electrodiagnostic testing (EDX) demonstrated demyelinating polyradiculoneuropathy (19/20, 95%). Autonomic involvement occurred in 45% (n=9, median CASS score 3.5, range 1-7). Nerve biopsies from the NF155-IgG4 patients (n=11) demonstrated grouped segmental demyelination (50%), myelin reduplication (45%) and paranodal swellings (50%). Most patients needed 2^nd and 3^rd line immunosuppression but had favorable long-term outcomes (n=18). Among 14 patients with serial EDX over 2 years, all except one demonstrated improvement after treatment. NF155-IgG positive NF155-IgG4 negative (NF155-IgG positive) and NF155-IgM positive patients were phenotypically different from NF155-IgG4 seropositive patients. Sensory ataxia, neuropathic pain, cerebellar dysfunction and root/plexus MRI abnormalities were significantly more common in NF155-IgG4 positive compared to MAG-IgM neuropathy. Chronic immune sensory polyradiculopathy (CISP)/CISP-plus phenotype was more common among Contactin-1 neuropathies compared to NF155-IgG4 positive cases. NF155-IgG4 positive cases responded favorably to immunotherapy compared to MAG-IgM seropositive cases with distal acquired demyelinating symmetric neuropathy (p<0.001) and had better long-term clinical outcomes compared to contactin-1 IgG (p=0.04).

DISCUSSION

We report long-term follow-up and clinical outcome of NF155-IgG4 patients. NF155-IgG4 but not IgM or IgG patients have unique clinical-electrodiagnostic signature. We demonstrate NF155-IgG4 positive patients, unlike classical CIDP with neuropathic pain and dysautonomia common at presentation. Long-term outcomes were favorable.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that NF155-IgG4 seropositive patients, compared to typical CIDP patients, present with distal more than proximal muscle weakness, positive sensory symptoms, and gait ataxia.

An Epitope Platform for Safe and Effective HTLV-1-Immunization: Potential Applications for mRNA and Peptide-Based Vaccines

Human T-cell lymphotropic virus type 1 (HTLV-1) infection affects millions of individuals worldwide and can lead to severe leukemia, myelopathy/tropical spastic paraparesis, and numerous other disorders. Pursuing a safe and effective immunotherapeutic approach, we compared the viral polyprotein and the human proteome with a sliding window approach in order to identify oligopeptide sequences unique to the virus. The immunological relevance of the viral unique oligopeptides was assessed by searching them in the immune epitope database (IEDB). We found that HTLV-1 has 15 peptide stretches each consisting of uniquely viral non-human pentapeptides which are ideal candidate for a safe and effective anti-HTLV-1 vaccine. Indeed, experimentally validated HTLV-1 epitopes, as retrieved from the IEDB, contain peptide sequences also present in a vast number of human proteins, thus potentially instituting the basis for cross-reactions. We found a potential for cross-reactivity between the virus and the human proteome and described an epitope platform to be used in order to avoid it, thus obtaining effective, specific, and safe immunization. Potential advantages for mRNA and peptide-based vaccine formulations are discussed.

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 IL1β, 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 IL1β 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.

Neurofascin antibodies in chronic inflammatory demyelinating polyradiculoneuropathy: from intrinsic genetic background to clinical manifestations

There are bunch of autoantibodies, particularly autoantibodies against proteins located at the node of Ranvier, have been discovered and transformed the clinical management of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Neurofascin (NF) plays an important role in both the nodal and paranodal regions of the node of Ranvier. In this review, we focus on the two characteristic forms of neurofascin: NF186 and NF155, comparing the similarities and differences between them, reviewing the current knowledge on genetic backgrounds, pathogenesis, clinical manifestations, and management of patients with anti-neurofascin positive CIDP. Autoantibodies against neurofascin were mainly IgG4 isotype. Mutation of NFASC gene in human causes severe neurodevelopment disorders, and HLA DRB1*15 may be a strong risk factor for the development of anti-NF155 antibodies. Motor impairment, sensory ataxia, and tremor were the typical presentations of patients with anti-NF155+ CIDP, while tetraplegia and cranial nerve involvement were more common in patients with anti-NF186+ CIDP. Recent studies have depicted a relatively clear picture of anti-NF155+ CIDP, and the strong clinical correlation of NF186 with CIDP remains unclear. The genetic background of neurofascin will assist in future explorations.

From PNS to CNS: characteristics of anti-neurofascin 186 neuropathy in 16 cases

INTRODUCTION

Neurofascin (NF) is critical for the formation and maintenance of Ranvier nodes. NF186, the neuronal form of NF, localizes in the initial segment of axon and Ranvier node. NF186 antibody has been detected in demyelinating diseases of both central nervous system (CNS) and peripheral nervous system (PNS).

AIMS

To evaluate the clinical features of patients with anti-NF186 IgG neuropathy.

METHODS

Sixteen patients (16/138) with serum-positive anti-NF186 IgG were included and divided into groups of either CNS or PNS-involved according to their clinical manifestations. Anti-NF186 IgG was detected by cell-based assays.

RESULTS

In 7 patients who were confirmed to have CNS involvement, the most frequent symptoms were dizziness (57%) and vision impairment (43%); lesions in centrum semiovale, cerebellum, and meninges were shown by magnetic resonance imaging (MRI). In comparison, limb weakness (78%) and numbness (78%) were the most common symptoms in PNS-involved patients; axonal loss and demyelination were confirmed by nerve conduction examinations. Elevated level of cerebrospinal fluid (CSF) protein was found in 12 cases without statistically significant difference between the CNS and PNS groups. Meanwhile, CSF white blood cell counts were found significantly elevated in CNS-involved patients compared with patients of PNS group. Thirteen patients received immunomodulating treatments, and patients with chronic onset and progressive course showed poor response to the therapies.

CONCLUSIONS

Patients with anti-NF186 IgG neuropathy showed no specific symptoms or signs. It is worth noting that quite a few patients show CNS-impaired signs only, and cranial MRI is essential for the screening of CNS involvement.