Advances in the diagnosis, pathogenesis and treatment of CIDP

Animal models of immune-mediated demyelinating polyneuropathies

Immune-mediated demyelinating polyneuropathies (IMDPs) are rare disorders in which dysregulated adaptive immune responses cause peripheral nerve demyelinating inflammation and axonal injury in susceptible individuals. Despite significant advances in understanding IMDP pathogenesis guided by patient data and representative mammalian models, specific therapies are lacking. Significant knowledge gaps in IMDP pathogenesis still exist, e.g. precise antigen(s) and mechanisms that initially trigger immune system activation and identification of large population disease susceptibility factors. The initial directional cues for antigen-specific effector or autoreactive leukocyte trafficking into peripheral nerves are also unknown. An overview of current animal models, with emphasis on the experimental autoimmune neuritis and spontaneous autoimmune peripheral polyneuropathy models, is provided. Insights on the initial directional cues for peripheral nerve tissue specific autoimmunity using a novel Major Histocompatibility Complex class II conditional knockout mouse strain are also discussed, suggesting an essential research tool to study cell- and time-dependent adaptive immunity in autoimmune diseases.

Antibodies in Autoimmune Neuropathies: What to Test, How to Test, Why to Test

Autoimmune neuropathies are a heterogeneous group of immune-mediated disorders of the peripheral nerves. Guillain-Barré syndrome (GBS) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) are the archetypal acute and chronic forms. Over the past few decades, pathogenic antibodies targeting antigens of the peripheral nervous system and driving peripheral nerve damage in selected patients have been described. Moreover, the detection of these antibodies has diagnostic and therapeutic implications that have prompted a modification of the GBS and CIDP diagnostic algorithms. GBS diagnosis is based in clinical criteria, and systematic testing of anti-ganglioside antibodies is not required. Nonetheless, a positive anti-ganglioside antibody test may support the clinical suspicion when diagnosis of GBS (GM1 IgG), Miller Fisher (GQ1b IgG), or acute sensory-ataxic (GD1b IgG) syndromes is uncertain. Anti-myelin-associated glycoprotein (MAG) IgM and anti-disialosyl IgM antibodies are key in the diagnosis of anti-MAG neuropathy and chronic ataxic neuropathy, ophthalmoplegia, M-protein, cold agglutinins, and disialosyl antibodies spectrum neuropathies, respectively, and help differentiating these conditions from CIDP. Recently, the field has been boosted by the discovery of pathogenic antibodies targeting proteins of the node of Ranvier contactin-1, contactin-associated protein 1, and nodal and paranodal isoforms of neurofascin (NF140, NF186, or NF155). These antibodies define subgroups of patients with specific clinical (most importantly poor or partial response to conventional therapies and excellent response to anti-CD20 therapy) and pathologic (node of Ranvier disruption in the absence of inflammation) features that led to the definition of the "autoimmune nodopathy" diagnostic category and to the incorporation of nodal/paranodal antibodies to clinical routine testing. The purpose of this review was to provide a practical vision for the general neurologist of the use of antibodies in the clinical assessment of autoimmune neuropathies.

Efficacy, safety and tolerability of rozanolixizumab in patients with chronic inflammatory demyelinating polyradiculoneuropathy: a randomised, subject-blind, investigator-blind, placebo-controlled, phase 2a trial and open-label extension study

BACKGROUND

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a peripheral nerve disorder characterised by weakness and sensory loss. We assessed the neonatal Fc receptor inhibitor rozanolixizumab for CIDP management.

METHODS

CIDP01 (NCT03861481) was a randomised, subject-blind, investigator-blind, placebo-controlled, phase 2a study. Adults with definite or probable CIDP receiving subcutaneous or intravenous immunoglobulin maintenance therapy were randomised 1:1 to 12 once-weekly subcutaneous infusions of rozanolixizumab 10 mg/kg or placebo, stratified according to previous immunoglobulin administration route. Investigators administering treatment and assessing efficacy, and patients, were blinded. The primary outcome was a change from baseline (CFB) to day 85 in inflammatory Rasch-built Overall Disability Scale (iRODS) score. Eligible patients who completed CIDP01 entered the open-label extension CIDP04 (NCT04051944).

RESULTS

In CIDP01, between 26 March 2019 and 31 March 2021, 34 patients were randomised to rozanolixizumab or placebo (17 (50%) each). No significant difference in CFB to day 85 in iRODS centile score was observed between rozanolixizumab (least squares mean 2.0 (SE 3.2)) and placebo (3.4 (2.6); difference -1.5 (90% CI -7.5 to 4.5)). Overall, 14 (82%) patients receiving rozanolixizumab and 13 (76%) receiving placebo experienced a treatment-emergent adverse event during the treatment period. Across CIDP01 and CIDP04, rozanolixizumab was well tolerated over up to 614 days; no clinically meaningful efficacy results were seen. No deaths occurred.

CONCLUSIONS

Rozanolixizumab did not show efficacy in patients with CIDP in this study, although this could be due to a relatively high placebo stability rate. Rozanolixizumab was well tolerated over medium-to-long-term weekly use, with an acceptable safety profile.

Genetic analyses of inflammatory polyneuropathy and chronic inflammatory demyelinating polyradiculoneuropathy identified candidate genes

Chronic inflammatory demyelinating polyneuropathy (CIDP) is a rare, immune-mediated disorder in which an aberrant immune response causes demyelination and axonal damage of the peripheral nerves. Genetic contribution to CIDP is unclear and no genome-wide association study (GWAS) has been reported so far. In this study, we aimed to identify CIDP-related risk loci, genes, and pathways. We first focused on CIDP, and 516 CIDP cases and 403,545 controls were included in the GWAS analysis. We also investigated genetic risk for inflammatory polyneuropathy (IP), in which we performed a GWAS study using FinnGen data and combined the results with GWAS from the UK Biobank using a fixed-effect meta-analysis. A total of 1,261 IP cases and 823,730 controls were included in the analysis. Stratified analyses by gender were performed. Mendelian randomization (MR), colocalization, and transcriptome-wide association study (TWAS) analyses were performed to identify associated genes. Gene-set analyses were conducted to identify associated pathways. We identified one genome-wide significant locus at 20q13.33 for CIDP risk among women, the top variant located at the intron region of gene CDH4. Sex-combined MR, colocalization, and TWAS analyses identified three candidate pathogenic genes for CIDP and five genes for IP. MAGMA gene-set analyses identified a total of 18 pathways related to IP or CIDP. Sex-stratified analyses identified three genes for IP among males and two genes for IP among females. Our study identified suggestive risk genes and pathways for CIDP and IP. Functional analyses should be conducted to further confirm these associations.

Hypoglossal nerve involvement and sternocleidomastoid muscle atrophy in chronic inflammatory demyelinating polyneuropathy with Hashimoto's thyroiditis: A case report and literature review

Chronic inflammatory demyelinating polyneuropathy (CIDP) is an immune-mediated neuropathy. While CIDP typically affects the peripheral nerves in the limbs, involvement of cranial nerves is atypical, and cases of muscle atrophy secondary to cranial nerve involvement are exceptionally rare. A 30-year-old female patient, who complained of numbness and weakness in her limbs, was diagnosed with CIDP after experiencing atrophy of the tongue and sternocleidomastoid muscles, along with tongue muscle fibrillation during a neurological examination. Additionally, the patient had hypothyroidism caused by Hashimoto's thyroiditis. Cerebrospinal fluid tests indicated albumincytological dissociation. Electrophysiological examination results confirmed the diagnosis of typical CIDP. Glucocorticoid treatment, a standard therapy for CIDP, led to a significant improvement in the patient's symptoms, including the regeneration of her tongue muscles. A literature review revealed only eight cases of CIDP with hypoglossal nerve involvement, and this case represents the first documentation of concurrent sternocleidomastoid muscle atrophy. Although muscle atrophy from cranial nerve involvement is infrequent in CIDP, the positive response to treatment is encouraging.

Therapy-resistant autoimmune nodopathy with anti-neurofascin 155 antibodies: a case report

This study reports the case of a previously healthy man in his late 20s who began experiencing symptoms 3 months before admission to our hospital, including arm and leg weakness and distal hypesthesia. Initially, the patient responded to corticosteroid therapy. However, as his symptoms progressed, he underwent plasmapheresis and received intravenous immunoglobulin therapy, neither of which led to any discernible improvement. With rapid symptom progression during subsequent hospital visits, further investigation led to the detection of neurofascin 155 antibodies. Based on existing evidence of its efficacy, rituximab treatment was initiated. To date, the patient has received three doses of rituximab, which has been partially ineffective. Thus, treatment is ongoing and includes a combination of rituximab and subcutaneous immunoglobulin.

A pathologically expanded, clonal lineage of IL-21-producing CD4+ T cells drives inflammatory neuropathy

Inflammatory neuropathies, which include chronic inflammatory demyelinating polyneuropathy (CIDP) and Guillain Barré syndrome (GBS), result from autoimmune destruction of the PNS and are characterized by progressive weakness and sensory loss. CD4+ T cells play a key role in the autoimmune destruction of the PNS. Yet, key properties of pathogenic CD4+ T cells remain incompletely understood. Here, we used paired single-cell RNA-Seq (scRNA-Seq) and single-cell T cell receptor-sequencing (scTCR-Seq) of peripheral nerves from an inflammatory neuropathy mouse model to identify IL-21-expressing CD4+ T cells that were clonally expanded and multifunctional. These IL-21-expressing CD4+ T cells consisted of 2 transcriptionally distinct expanded cell populations, which expressed genes associated with T follicular helper (Tfh) and T peripheral helper (Tph) cell subsets. Remarkably, TCR clonotypes were shared between these 2 IL-21-expressing cell populations, suggesting a common lineage differentiation pathway. Finally, we demonstrated that IL-21 receptor-KO (IL-21R-KO) mice were protected from neuropathy development and had decreased immune infiltration into peripheral nerves. IL-21 signaling upregulated CXCR6, a chemokine receptor that promotes CD4+ T cell localization in peripheral nerves. Together, these findings point to IL-21 signaling, Tfh/Tph differentiation, and CXCR6-mediated cellular localization as potential therapeutic targets in inflammatory neuropathies.

Membrane Proteome-Wide Screening of Autoantibodies in CIDP Using Human Cell Microarray Technology

BACKGROUND AND OBJECTIVES

Autoantibody discovery in complex autoimmune diseases is challenging. Diverse successful antigen identification strategies are available, but, so far, have often been unsuccessful, especially in the discovery of protein antigens in which conformational and post-translational modification are critical. Our study assesses the utility of a human membrane and secreted protein microarray technology to detect autoantibodies in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP).

METHODS

A cell microarray consisting of human embryonic kidney-293 cells expressing >5,000 human proteins was used. First, a validation step was performed with 4 serum samples from patients with autoimmune nodopathy (AN) to assess the ability of this technology to detect circulating known autoantibodies. The ability of the cell microarray technology to discover novel IgG autoantibodies was assessed incubating the array with 8 CIDP serum samples. Identified autoantibodies were subsequently validated using cell-based assays (CBAs), ELISA, and/or tissue immunohistochemistry and analyzed in a cohort of CIDP and AN (n = 96) and control (n = 100) samples.

RESULTS

Serum anti-contactin-1 and anti-neurofascin-155 were detected by the human cell microarray technology. Nine potentially relevant antigens were found in patients with CIDP without other detectable antibodies; confirmation was possible in six of them: ephrin type-A receptor 7 (EPHA7); potassium-transporting ATPase alpha chain 1 and subunit beta (ATP4A/4B); leukemia-inhibitory factor (LIF); and interferon lambda 1, 2, and 3 (IFNL1, IFNL2, IFNL3). Anti-ATP4A/4B and anti-EPHA7 antibodies were detected in patients and controls and considered unrelated to CIDP. Both anti-LIF and anti-IFNL antibodies were found in the same 2 patients and were not detected in any control. Both patients showed the same staining pattern against myelinating fibers of peripheral nerve tissue and of myelinating neuron-Schwann cell cocultures. Clinically relevant correlations could not be established for anti-LIF and anti-IFNL3 antibodies.

DISCUSSION

Our work demonstrates the utility of human cell microarray technology to detect known and discover unknown autoantibodies in human serum samples. Despite potential CIDP-associated autoantibodies (anti-LIF and anti-IFNL3) being identified, their clinical and pathogenic relevance needs to be elucidated in bigger cohorts.

A pathologically expanded, clonal lineage of IL-21 producing CD4+ T cells drives Inflammatory neuropathy

Inflammatory neuropathies, which include CIDP (chronic inflammatory demyelinating polyneuropathy) and GBS (Guillain Barre Syndrome), result from autoimmune destruction of the peripheral nervous system (PNS) and are characterized by progressive weakness and sensory loss. CD4+ T cells play a key role in the autoimmune destruction of the PNS. Yet, key properties of pathogenic CD4+ T cells remain incompletely understood. Here, we use paired scRNAseq and scTCRseq of peripheral nerves from an inflammatory neuropathy mouse model to identify IL-21 expressing CD4+ T cells that are clonally expanded and multifunctional. These IL-21-expressing CD4+ T cells are comprised of two transcriptionally distinct expanded populations, which express genes associated with Tfh and Tph subsets. Remarkably, TCR clonotypes are shared between these two IL-21-expressing populations, suggesting a common lineage differentiation pathway. Finally, we demonstrate that IL-21 signaling is required for neuropathy development and pathogenic T cell infiltration into peripheral nerves. IL-21 signaling upregulates CXCR6, a chemokine receptor that promotes CD4+ T cell localization in peripheral nerves. Together, these findings point to IL-21 signaling, Tfh/Tph differentiation, and CXCR6-mediated cellular localization as potential therapeutic targets in inflammatory neuropathies.

How I Treat Chronic Inflammatory Demyelinating Polyneuropathy Podcast

Chronic inflammatory demyelinating polyneuropathy (CIDP) is an acquired immune-mediated neuropathy that typically presents with progressive or relapsing, symmetric, proximal, and distal weakness of upper and lower limbs, sensory involvement of at least two limbs, and decreased or absent deep tendon reflexes. The symptoms of CIDP can be similar to those of other neuropathies, making diagnosis difficult, which can often lead to delays in correct diagnosis and treatment. The updated European Academy of Neurology/Peripheral Nerve Society (EAN/PNS) 2021 guideline outlines a set of diagnostic criteria that help to identify CIDP with high accuracy and provides recommendations for the treatment of CIDP. The aim of this podcast, featuring Dr. Urvi Desai (Professor of Neurology, Wake Forest School of Medicine and Atrium Health Neurosciences Institute Wake Forest Baptist, Charlotte), is to discuss how the new guideline impacts diagnosis and treatment decisions in her everyday clinical practice. Using a patient case study example, the updated guideline recommends assessing a patient for clinical, electrophysiological, and supportive criteria for CIDP, enabling a more straightforward diagnosis of either typical CIDP, a CIDP variant, or an autoimmune nodopathy. A second patient case study highlights how the new guideline no longer considers autoimmune nodopathies as CIDP, as patients with these disorders do not meet hallmark CIDP criteria. This leaves an unmet need in terms of guidance on how to treat this subset of patients. Although the new guideline has not necessarily changed treatment preference in clinical practice, the addition of subcutaneous immunoglobulin (SCIG) into the guideline now better reflects clinical practice. The guideline helps to define and categorize CIDP more simply and consistently, allowing quicker and more accurate diagnosis, leading to a positive impact on treatment response and prognosis. These real-world insights into the diagnosis and management of patients with CIDP could help guide best clinical practice and help facilitate optimization of patient outcomes.

Distal Chronic Inflammatory Demyelinating Polyneuropathy Following COVID-19 Vaccination in a Patient with Solitary Plasmacytoma: A Case Report and Literature Review

We herein report a rare case of distal chronic inflammatory demyelinating polyneuropathy (CIDP) following coronavirus disease 2019 (COVID-19) vaccination. A 39-year-old woman with a solitary plasmacytoma developed general weakness 7 days after receiving the second dose of the Pfizer-BioNTech COVID-19 vaccine, which had progressed for 3 months. A neurological examination revealed limb weakness with areflexia. Serological tests identified the presence of IgG antibodies against anti-GM1 and anti-GM2 gangliosides. Comprehensive evaluations met the criteria of distal CIDP. Intravenous immunoglobulin, intravenous methylprednisolone, oral prednisolone, and plasma exchange were administered, and she gradually improved. Physicians should be aware of CIDP as a rare complication of COVID-19 vaccination.

Repurposing MS immunotherapies for CIDP and other autoimmune neuropathies: unfulfilled promise or efficient strategy?

Despite advances in the treatment of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and other common autoimmune neuropathies (AN), still-many patients with these diseases do not respond satisfactorily to the available treatments. Repurposing of disease-modifying therapies (DMTs) from other autoimmune conditions, particularly multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD), is a promising strategy that may accelerate the establishment of novel treatment choices for AN. This approach appears attractive due to homologies in the pathogenesis of these diseases and the extensive post-marketing experience that has been gathered from treating MS and NMOSD patients. The idea is also strengthened by a number of studies that explored the efficacy of DMTs in animal models of AN but also in some CIDP patients. We here review the available preclinical and clinical data of approved MS therapeutics in terms of their applicability to AN, especially CIDP. Promising therapeutic approaches appear to be B cell-directed and complement-targeting strategies, such as anti-CD20/anti-CD19 agents, Bruton's tyrosine kinase inhibitors and anti-C5 agents, as they exert their effects in the periphery. This is a major advantage because, in contrast to MS, their action in the periphery is sufficient to exert significant immunomodulation.

Sex differences in Guillain Barré syndrome, chronic inflammatory demyelinating polyradiculoneuropathy and experimental autoimmune neuritis

Guillain Barré syndrome (GBS) and its variants, and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP and its variants, are regarded as immune mediated neuropathies. Unlike in many autoimmune disorders, GBS and CIDP are more common in males than females. Sex is not a clear predictor of outcome. Experimental autoimmune neuritis (EAN) is an animal model of these diseases, but there are no studies of the effects of sex in EAN. The pathogenesis of GBS and CIDP involves immune response to non-protein antigens, antigen presentation through non-conventional T cells and, in CIDP with nodopathy, IgG4 antibody responses to antigens. There are some reported sex differences in some of these elements of the immune system and we speculate that these sex differences could contribute to the male predominance of these diseases, and suggest that sex differences in peripheral nerves is a topic worthy of further study.

A first case of childhood chronic inflammatory demyelinating polyneuropathy associated with alopecia universalis

Chronic inflammatory demyelinating polyneuropathy (CIDP) is an acquired demyelinating disease of the peripheral nervous system with unknown etiology. Alopecia universalis, an advanced form of alopecia areata (AA), is a condition characterized by complete hair loss. Here we report the first case of childhood CIDP associated with AA who was successfully treated with a combination of intravenous immunoglobulin (IVIg) and corticosteroids. CASE REPORT: This case describes a nine-year-old Japanese girl who developed alopecia, progressive muscle weakness, and eventually loss of walking ability (at ages 2, 4, and 7, respectively). She was treated with IVIg and prednisolone combination therapy, which improved muscle weakness and alopecia. She was positive for serum IgG-GM2 type anti-glycolipid antibodies, which may be associated with this rare combination of diseases.

Electrophysiological and functional signs of Guillain-Barré syndrome predicted by a multiscale neuromuscular computational model

Objective. The diagnosis of nerve disorders in humans has relied heavily on the measurement of electrical signals from nerves or muscles in response to electrical stimuli applied at appropriate locations on the body surface. The present study investigated the demyelinating subtype of Guillain-Barré syndrome using multiscale computational model simulations to verify how demyelination of peripheral axons may affect plantar flexion torque as well as the ongoing electromyogram (EMG) during voluntary isometric or isotonic contractions. Approach. Changes in axonal conduction velocities, mimicking those found in patients with the disease at different stages, were imposed on a multiscale computational neuromusculoskeletal model to simulate subjects performing unipodal plantar flexion force and position tasks. Main results. The simulated results indicated changes in the torque signal during the early phase of the disease while performing isotonic tasks, as well as in torque variability after partial conduction block while performing both isometric and isotonic tasks. Our results also indicated changes in the root mean square values and in the power spectrum of the soleus EMG signal as well as changes in the synchronisation index computed from the firing times of the active motor units. All these quantitative changes in functional indicators suggest that the adoption of such additional measurements, such as torques and ongoing EMG, could be used with advantage in the diagnosis and be relevant in providing extra information for the neurologist about the level of the disease. Significance. Our findings enrich the knowledge of the possible ways demyelination affects force generation and position control during plantarflexion. Moreover, this work extends computational neuroscience to computational neurology and shows the potential of biologically compatible neuromuscular computational models in providing relevant quantitative signs that may be useful for diagnosis in the clinic, complementing the tools traditionally used in neurological electrodiagnosis.

Protocol of comparison of the effects of single plasma exchange and double filtration plasmapheresis on peripheral lymphocyte phenotypes in patients with Chronic Inflammatory Demyelinating Polyradiculoneuropathy: a monocentric prospective study with single-case experimental design

BACKGROUND

Chronic Inflammatory Demyelinating Polyradiculoneuropathy (CIDP), a rare disorder affecting young adults, causes gradual weakness of the limbs, areflexia and impaired sensory function. New CIDP phenotypes without pathogenic antibodies but with modified cell profiles have been described. Treatments include corticotherapy, intravenous immunoglobulins, and plasmapheresis but the latter's action mechanisms remain unclear. Plasmapheresis supposedly removes toxic agents like antibodies from plasma but it is uncertain whether it has an immune-modulating effect. Also, the refining mechanisms of the two main plasmapheresis techniques-single plasma exchange and double filtration plasmapheresis (DFPP) - are different and unclear. This study aims to compare the evolution of peripheral lymphocyte profiles in patients with CIDP according to their treatment (single centrifugation plasmapheresis or DFPP) to better grasp the action mechanisms of both techniques.

METHOD

In this proof-of-concept, monocentric, prospective, Single-Case Experimental Design study, 5 patients are evaluated by alternating their treatment type (single plasma exchange or DFPP) for 6 courses of treatment after randomization to their first treatment type. Each course of treatment lasts 2-4 weeks. For single plasma exchange, 60 ml/kg plasma will be removed from the patient and replaced with albumin solutes, with a centrifugation method to avoid the immunological reaction caused by the membrane used with the filtration method. For DFPP, 60 ml/kg plasma will be removed from the patient with a plasma separator membrane, then processed via a fractionator membrane to remove molecules of a greater size than albumin before returning it to the patient. This technique requires no substitution solutes, only 20 g of albumin to replace what would normally be lost during a session. The primary outcome is the difference between the two plasmapheresis techniques in the variation of the TH1/TH17 ratio over the period D0H0-D0H3 and D0H0-D7. Secondary outcomes include the variation in lymphocyte subpopulations at each session and between therapeutic plasmapheresis techniques, the clinical evolution, tolerance and cost of treatments.

DISCUSSION

Understanding the action mechanisms of single plasma exchange and DFPP will help us to offer the right treatment to each patient with CIPD according to efficacy, tolerance and cost.

TRIAL REGISTRATION

ClinicalTrials.gov under the no. NCT04742374 and date of registration 10 December 2020.

Autoantibodies in central nervous system and neuromuscular autoimmune disorders: A narrative review

The discovery of novel autoantibodies in neurological disorders contributes to a better understanding of its pathogenesis, improves the accuracy of diagnosis, and leads to new treatment strategies. Advances in techniques for the screening and detection of autoantibodies have enabled the discovery of new antibodies in the central nervous system (CNS) and neuromuscular diseases. Cell-based assays using live or fixed cells overexpressing target antigens are widely used for autoantibody-based diagnosis in clinical practice. Common pathogenic autoantibodies are unknown in most patients with multiple sclerosis (MS) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Novel pathogenic autoantibodies to aquaporin-4 and myelin oligodendrocyte glycoprotein (MOG) have been identified in neuromyelitis optica spectrum disorder and MOG antibody-associated disease, respectively. These diseases have clinical similarities to MS, but with the discovery of pathogenic autoantibodies, they are now recognized as distinct disease entities. Antibodies to paranodal membrane proteins such as neurofascin-155, contactin‑1, contactin‑associated protein‑1 in CIDP and muscle-specific kinase and low-density lipoprotein receptor–related protein 4 in myasthenia gravis were added to the profiles of autoantibodies in neurological disorders. Despite the relatively low frequency of seropositivity, autoantibody detection is currently essential for the clinical diagnosis of CNS and neuromuscular autoimmune disorders, and differential approaches to seropositive patients will contribute to more personalized medicine. We reviewed recent discoveries of autoantibodies and their clinical implications in CNS and neuromuscular disorders.

Evolution of Anti-B Cell Therapeutics in Autoimmune Neurological Diseases

B cells have an ever-increasing role in the etiopathology of a number of autoimmune neurological disorders, acting as antigen-presenting cells facilitating antibody production but also as sensors, coordinators, and regulators of the immune response. In particular, B cells can regulate the T cell activation process through their participation in antigen presentation, production of proinflammatory cytokines (bystander activation or suppression), and contribution to ectopic lymphoid aggregates. Such an important interplay between B and T cells makes therapeutic depletion of B cells an attractive treatment strategy. The last decade, anti-B cell therapies using monoclonal antibodies against B cell surface molecules have evolved into a rational approach for successfully treating autoimmune neurological disorders, even when T cells seem to be the main effector cells. The paper summarizes basic aspects of B cell biology, discusses the roles of B cells in neurological autoimmunities, and highlights how the currently available or under development anti-B cell therapeutics exert their action in the wide spectrum and immunologically diverse neurological disorders. The efficacy of the various anti-B cell therapies and practical issues on induction and maintenance therapy is specifically detailed for the treatment of patients with multiple sclerosis, neuromyelitis-spectrum disorders, autoimmune encephalitis and hyperexcitability CNS disorders, autoimmune neuropathies, myasthenia gravis, and inflammatory myopathies. The success of anti-B cell therapies in inducing long-term remission in IgG4 neuroautoimmunities is also highlighted pointing out potential biomarkers for follow-up infusions.

The Role of the Complement System in Chronic Inflammatory Demyelinating Polyneuropathy: Implications for Complement-Targeted Therapies

Chronic inflammatory demyelinating polyneuropathy (CIDP) is the most common, heterogeneous, immune-mediated neuropathy, characterized by predominant demyelination of motor and sensory nerves. CIDP follows a relapsing-remitting or a progressive course and causes substantial disability. The pathogenesis of CIDP involves a complex interplay of multiple aberrant immune responses, creating a pro-inflammatory environment, subsequently inflicting damage on the myelin sheath. Though the exact triggers are unclear, diverse immune mechanisms encompassing cellular and humoral pathways are implicated. The complement system appears to play a role in promoting macrophage-mediated demyelination. Complement deposition in sural nerve biopsies, as well as signs of increased complement activation in serum and CSF of patients with CIDP, suggest complement involvement in CIDP pathogenesis. Here, we present a comprehensive overview of the preclinical and clinical evidence supporting the potential role of the complement system in CIDP. This understanding furnishes a strong rationale for targeting the complement system to develop new therapies that could serve the unmet needs of patients affected by CIDP, particularly in those refractory to standard therapies.

Pathogenic TNF-α drives peripheral nerve inflammation in an Aire-deficient model of autoimmunity

Immune cells infiltrate the peripheral nervous system (PNS) after injury and with autoimmunity, but their net effect is divergent. After injury, immune cells are reparative, while in inflammatory neuropathies (e.g., Guillain Barré Syndrome and chronic inflammatory demyelinating polyneuropathy), immune cells are proinflammatory and promote autoimmune demyelination. An understanding of immune cell phenotypes that distinguish these conditions may, therefore, reveal new therapeutic targets for switching immune cells from an inflammatory role to a reparative state. In an autoimmune regulator (Aire)-deficient mouse model of inflammatory neuropathy, we used single-cell RNA sequencing of sciatic nerves to discover a transcriptionally heterogeneous cellular landscape, including multiple myeloid, innate lymphoid, and lymphoid cell types. Analysis of cell-cell ligand-receptor interactions uncovered a macrophage-mediated tumor necrosis factor-α (TNF-α) signaling axis that is induced by interferon-γ and required for initiation of autoimmune demyelination. Developmental trajectory visualization suggested that TNF-α signaling is associated with metabolic reprogramming of macrophages and polarization of macrophages from a reparative state in injury to a pathogenic, inflammatory state in autoimmunity. Autocrine TNF-α signaling induced macrophage expression of multiple genes (Clec4e, Marcksl1, Cxcl1, and Cxcl10) important in immune cell activation and recruitment. Genetic and antibody-based blockade of TNF-α/TNF-α signaling ameliorated clinical neuropathy, peripheral nerve infiltration, and demyelination, which provides preclinical evidence that the TNF-α axis may be effectively targeted to resolve inflammatory neuropathies.

Pathophysiology of the Different Clinical Phenotypes of Chronic Inflammatory Demyelinating Polyradiculoneuropathy (CIDP)

Chronic inflammatory demyelinating polyneuropathy (CIDP) is the most common form of autoimmune polyneuropathy. It is a chronic disease and may be monophasic, progressive or recurrent with exacerbations and incomplete remissions, causing accumulating disability. In recent years, there has been rapid progress in understanding the background of CIDP, which allowed us to distinguish specific phenotypes of this disease. This in turn allowed us to better understand the mechanism of response or non-response to various forms of therapy. On the basis of a review of the relevant literature, the authors present the current state of knowledge concerning the pathophysiology of the different clinical phenotypes of CIDP as well as ongoing research in this field, with reference to key points of immune-mediated processes involved in the background of CIDP.

AstraZeneca COVID-19 vaccine and Guillain- Barré Syndrome in Tasmania: A causal link?

The emergence of the coronavirus 2019 (COVID-19) pandemic has presented an unprecedented global challenge. Vaccines against COVID have been developed to date. Covid-19 has been linked with the development of Guillain-Barre Syndrome (GBS), a rare immune-mediated demyelinating neuropathy. We report three cases of Guillain-Barre Syndrome and one case of Chronic Inflammatory Demyelinating Polyneuropathy (CIDP), presenting to a Tasmanian hospital, and review 15 other reported cases and discuss likely immunopathology. Nearly all reported cases of post-COVID-19 vacciation inflammatory demyelinating polyneuropathy are linked to AstraZeneca vaccination and a variant with bifacial weakness is the most reported form of GBS globally.

Update on Intravenous Immunoglobulin in Neurology: Modulating Neuro-autoimmunity, Evolving Factors on Efficacy and Dosing and Challenges on Stopping Chronic IVIg Therapy

In the last 25 years, intravenous immunoglobulin (IVIg) has had a major impact in the successful treatment of previously untreatable or poorly controlled autoimmune neurological disorders. Derived from thousands of healthy donors, IVIg contains IgG1 isotypes of idiotypic antibodies that have the potential to bind pathogenic autoantibodies or cross-react with various antigenic peptides, including proteins conserved among the "common cold"-pre-pandemic coronaviruses; as a result, after IVIg infusions, some of the patients' sera may transiently become positive for various neuronal antibodies, even for anti-SARS-CoV-2, necessitating caution in separating antibodies derived from the infused IVIg or acquired humoral immunity. IVIg exerts multiple effects on the immunoregulatory network by variably affecting autoantibodies, complement activation, FcRn saturation, FcγRIIb receptors, cytokines, and inflammatory mediators. Based on randomized controlled trials, IVIg is approved for the treatment of GBS, CIDP, MMN and dermatomyositis; has been effective in, myasthenia gravis exacerbations, and stiff-person syndrome; and exhibits convincing efficacy in autoimmune epilepsy, neuromyelitis, and autoimmune encephalitis. Recent evidence suggests that polymorphisms in the genes encoding FcRn and FcγRIIB may influence the catabolism of infused IgG or its anti-inflammatory effects, impacting on individualized dosing or efficacy. For chronic maintenance therapy, IVIg and subcutaneous IgG are effective in controlled studies only in CIDP and MMN preventing relapses and axonal loss up to 48 weeks; in practice, however, IVIg is continuously used for years in all the aforementioned neurological conditions, like is a "forever necessary therapy" for maintaining stability, generating challenges on when and how to stop it. Because about 35-40% of patients on chronic therapy do not exhibit objective neurological signs of worsening after stopping IVIg but express subjective symptoms of fatigue, pains, spasms, or a feeling of generalized weakness, a conditioning effect combined with fear that discontinuing chronic therapy may destabilize a multi-year stability status is likely. The dilemmas of continuing chronic therapy, the importance of adjusting dosing and scheduling or periodically stopping IVIg to objectively assess necessity, and concerns in accurately interpreting IVIg-dependency are discussed. Finally, the merit of subcutaneous IgG, the ineffectiveness of IVIg in IgG4-neurological autoimmunities, and genetic factors affecting IVIg dosing and efficacy are addressed.

Retrospective analysis of response to rituximab in chronic inflammatory demyelinating polyneuropathy refractory to first-line therapy

Few case reports/series describe the efficacy of rituximab in refractory chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), which is preferred in the presence of anti-nodal/paranodal antibodies. We aimed at evaluating the clinical response to rituximab in a subset of patients with refractory CIDP for whom the anti-nodal/paranodal antibodies status was unknown, as not available in Iran. We retrospectively analyzed the response to rituximab in 14 Iranian patients with refractory CIDP (3 children, 11 adults), in whom the anti-nodal/paranodal antibodies status was unknown. The subjects were evaluated with the Medical Research Council (MRC) sum score (MRCSS), Inflammatory Neuropathy Cause and Treatment (INCAT) disability scores, and electrophysiology, before and after treatment. Mean age was 34.4 ± 20.7 years, disease duration pre-rituximab treatment was 27.8 ± 18.8 (range: 6-60) months, and mean follow-up duration was 18.5 ± 11.0 (range: 4-36) months. Considering the INCAT sum score, one worsened during post-rituximab treatment, and three patients did not change. Considering MRCSS, notably, four patients achieved normalization of their MRCSS. Regarding the corticosteroid dose, two patients could discontinue prednisolone. As rated by a pre-defined scoring system, nerve conduction parameters improved significantly post-rituximab in the treated cohort (P = .006). All patients tolerated rituximab infusions without adverse effects. Rituximab may be effective in refractory CIDP, even though worsening may occur in some patients. Anti-nodal/paranodal antibodies assay, when available, and other criteria may help drive therapeutic decision-making on rituximab as second-line treatment.

Neuropathies périphériques associées aux syndromes lymphoprolifératifs : spectre clinique et démarche diagnostique

Lymphoproliferative syndromes (multiple myeloma, Waldenström's disease, chronic lymphocytic leukemia, lymphomas) may be associated with peripheral neuropathies. The mechanism can be dysimmune, associated or not with monoclonal gammopathies; paraneoplastic; infiltrative; or more commonly, iatrogenic or due to vitamin deficiency. The diagnosis can be complex, especially when the neuropathy is the presenting manifestation, requiring a close cooperation between internists and neurologists. The positive diagnosis of the neuropathy is based on a systematic electro-clinical investigation, which specifies the topography and the mechanism of the nerve damage, sometimes reinforced by imaging examinations, in particular, nerve and/or plexus MRI. The imputability of the neuropathy to a lymphoproliferative syndrome is based on a set of arguments including the clinical context (B signs, tumour syndrome), first-line laboratory tests (hemogram, protein electrophoresis, viral serologies, complement), auto-antibodies discussed according to the neuropathy (anti-MAG, anti-gangliosides) and sometimes more invasive examinations (bone marrow or neuro-muscular biopsies).

Corneal inflammatory cell infiltration predicts disease activity in chronic inflammatory demyelinating polyneuropathy

The assessment of disease activity is fundamental in the management of chronic inflammatory demyelinating polyneuropathy (CIDP). Previous studies with small patient numbers found an increase of corneal immune cell infiltrates as a potential marker of inflammation in patients with CIDP. However, its clinical relevance remained unclear. The present study aimed to determine whether the amount of corneal inflammatory cells (CIC) measured by corneal confocal microscopy (CCM) detects disease activity in CIDP. CIC were measured in 142 CCM-investigations of 97 CIDP-patients. Data on clinical disease activity, disability (INCAT-ODSS) and need for therapy escalation at the timepoint of CCM, 3 and 6 months later were analyzed depending CIC-count. Pathological spontaneous activity during electromyography was examined as another possible biomarker for disease activity in comparison to CIC-count. An increased CIC-count at baseline was found in patients with clinical disease activity and disability progression in the following 3-6 months. An increase to more than 25 CIC/mm² had a sensitivity of 0.73 and a specificity of 0.71 to detect clinical disease activity and a sensitivity of 0.77 and a specificity of 0.64 to detect disability progression (increasing INCAT-ODSS) in the following 6 months. An increase to more than 50 CIC/mm² had a sensitivity of about 0.51 and a specificity of 0.91 to detect clinical disease activity and a sensitivity of 0.53 and a specificity of 0.80 to detect disability progression. CIC count is a non-invasive biomarker for the detection of disease activity in the following 6 months in CIDP.

Interleukin 8, a Biomarker to Differentiate Guillain-Barré Syndrome From CIDP

Objective

To determine whether CSF interleukin 8 (IL-8) concentration can help to distinguish Guillain-Barré syndrome (GBS) from chronic inflammatory demyelinating polyneuropathy (CIDP) at the initial stage of the disease.

Methods

We performed retrospective immunoassay of IL-8 in CSF, collected at the University Hospitals of Geneva between 2010 and 2018, from patients diagnosed with GBS (n = 45) and with CIDP (n = 30) according to the Brighton and European Federation of Neurological Societies/Peripheral Nerve Society criteria by a physician blinded to biological results.

Results

CSF IL-8 was higher in GBS (median: 83.9 pg/mL) than in CIDP (41.0 pg/mL) (p < 0.001). Receiver operating characteristic analyses indicated that the optimal IL-8 cutoff was 70 pg/mL. Above this value, patients were more likely to present GBS than CIDP (specificity 96.7%, sensitivity 64.4%, positive predictive value [PPV] 96.7%, and negative predictive value [NPV] 64.4%). Among GBS subcategories, IL-8 was higher in acute inflammatory demyelinating polyneuropathy (AIDP, median: 101.8 pg/mL) than in other GBS variants (median: 53.7 pg/mL). In addition, with CSF IL-8 above 70 pg/mL, patients were more likely to present AIDP than acute-onset CIDP (p < 0.001; specificity 100%, sensitivity 78.8%, PPV 100%, and NPV 46.2%) or other CIDP with nonacute presentation (p < 0.0001; specificity 95.8%, sensitivity 78.8%, PPV 96.3%, and NPV 76.7%).

Conclusion

CSF IL-8 levels can help to differentiate AIDP variant of GBS from CIDP, including acute-onset CIDP, with high specificity and PPV. This may improve early and appropriate treatment.

Classification of Evidence

This study provides Class II evidence that CSF IL-8 levels accurately distinguish patients with GBS from those with CIDP.

Serum neurofilament light chain in chronic inflammatory demyelinating polyneuropathy

OBJECTIVES

Neurofilament light chain (NfL) levels have been suggested as reflecting axonal damage in various inflammatory and neurodegenerative disorders, including acquired peripheral neuropathies. We aimed to investigate if serum NfL (sNfL) levels can be a biomarker of disease activity and treatment response in patients with chronic inflammatory demyelinating polyneuropathy (CIDP).

MATERIALS AND METHODS

The sNfL levels of eleven newly diagnosed patients with CIDP were retrospectively assayed and compared with seven healthy volunteers. The levels were assayed before and after intravenous immunoglobulin treatment in patients with CIDP and were also assayed in the remission period.

RESULTS

Baseline sNfL levels in patients with CIDP before treatment were significantly higher than those in healthy controls. The levels significantly decreased overtime after one month of treatment and in remission period. There were significant negative correlations between the sNfL levels and the disease duration (the interval between the onset of the disease and the time of sampling), and weak correlations between the sNfL levels and overall neuropathy limitations scale.

CONCLUSIONS

sNfL may be a potential biomarker reflecting the disease activity in patients with CIDP.

Antibodies to the Caspr1/contactin-1 complex in chronic inflammatory demyelinating polyradiculoneuropathy

Previous studies have described the clinical, serological and pathological features of patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and antibodies directed against the paranodal proteins neurofascin-155, contactin-1 (CNTN1), contactin-associated protein-1 (Caspr1), or nodal forms of neurofascin. Such antibodies are useful for diagnosis and potentially treatment selection. However, antibodies targeting Caspr1 only or the Caspr1/CNTN1 complex have been reported in few patients with CIDP. Moreover, it is unclear if these patients belong to the same pathophysiological subgroup. Using cell-based assays in routine clinical testing, we identified sera from patients with CIDP showing strong membrane reactivity when both CNTN1 and Caspr1 were co-transfected (but not when CNTN1 was transfected alone). Fifteen patients (10 male; aged between 40 and 75) with antibodies targeting Caspr1/CNTN1 co-transfected cells were enrolled for characterization. The prevalence of anti-Caspr1/CNTN1 antibodies was 1.9% (1/52) in the Sant Pau CIDP cohort, and 4.3% (1/23) in a German cohort of acute-onset CIDP. All patients fulfilled European Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS) definite diagnostic criteria for CIDP. Seven (47%) were initially diagnosed with Guillain-Barré syndrome due to an acute-subacute onset. Six (40%) patients had cranial nerve involvement, eight (53%) reported neuropathic pain and 12 (80%) ataxia. Axonal involvement and acute denervation were frequent in electrophysiological studies. Complete response to intravenous immunoglobulin was not observed, while most (90%) responded well to rituximab. Enzyme-linked immunosorbent assay (ELISA) and teased nerve fibre immunohistochemistry confirmed reactivity against the paranodal Caspr1/CNTN1 complex. Weaker reactivity against Caspr1 transfected alone was also detected in 10/15 (67%). Sera from 13 of these patients were available for testing by ELISA. All 13 samples reacted against Caspr1 by ELISA and this reactivity was enhanced when CNTN1 was added to the Caspr1 ELISA. IgG subclasses were also investigated by ELISA. IgG4 was the predominant subclass in 10 patients, while IgG3 was predominant in other three patients. In conclusion, patients with antibodies to the Caspr1/CNTN1 complex display similar serological and clinical features and constitute a single subgroup within the CIDP syndrome. These antibodies likely target Caspr1 primarily and are detected with Caspr1-only ELISA, but reactivity is optimal when CNTN1 is added to Caspr1 in cell-based assays and ELISA.

Emerging Role of C5 Complement Pathway in Peripheral Neuropathies: Current Treatments and Future Perspectives

The complement system is a key component of innate immunity since it plays a critical role in inflammation and defense against common pathogens. However, an inappropriate activation of the complement system is involved in numerous disorders, including peripheral neuropathies. Current strategies for neuropathy-related pain fail to achieve adequate pain relief, and although several therapies are used to alleviate symptoms, approved disease-modifying treatments are unavailable. This urgent medical need is driving the development of therapeutic agents for this condition, and special emphasis is given to complement-targeting approaches. Recent evidence has underscored the importance of complement component C5a and its receptor C5aR1 in inflammatory and neuropathic pain, indicating that C5a/C5aR1 axis activation triggers a cascade of events involved in pathophysiology of peripheral neuropathy and painful neuro-inflammatory states. However, the underlying pathophysiological mechanisms of this signaling in peripheral neuropathy are not fully known. Here, we provide an overview of complement pathways and major components associated with dysregulated complement activation in peripheral neuropathy, and of drugs under development targeting the C5 system. C5/C5aR1 axis modulators could represent a new strategy to treat complement-related peripheral neuropathies. Specifically, we describe novel C5aR allosteric modulators, which may potentially become new tools in the therapeutic armory against neuropathic pain.

Association of serum neurofilament light chain levels with clinicopathology of chronic inflammatory demyelinating polyneuropathy, including NF155 reactive patients

OBJECTIVES

To clarify whether serum neurofilament light chains (NfLs) serve as a biomarker of axonal damage in patients with chronic inflammatory demyelinating polyneuropathy (CIDP), especially in patients with anti-neurofascin 155 (NF155) antibodies.

METHODS

The Simoa system was used to examine serum NfL levels from 58 patients with CIDP, including 13 anti-NF155 antibody-positive patients, and from 14 age- and sex-matched healthy individuals. Serum NfL levels were evaluated before and after treatment in eight patients with anti-NF155 antibodies. Clinical features, electrophysiological findings, and cerebrospinal fluid (CSF) protein levels, were evaluated. The pathological features of sural nerves from 40 patients were also examined.

RESULTS

Serum NfL levels were significantly higher in patients with CIDP than in healthy individuals (median 29.63 vs. 7.71 pg/mL, p < 0.001) and were correlated with both modified Rankin Scale scores (r = 0.584, p < 0.001) and CSF protein levels (r = 0.432, p = 0.001). The NfL levels of anti-NF155 antibody-positive patients were higher than those of antibody-negative patients (p = 0.005). Serum NfL levels were negatively correlated with compound muscle action potential amplitudes of the tibial nerves (r =  - 0.404, p = 0.004) and positively correlated with the degree of active axonal degeneration in the pathological findings (r = 0.485, p = 0.001). In the antibody-positive group, NfL levels and antibody titers decreased after treatment in all examined patients.

CONCLUSION

Serum NfL correlated with pathological indices of axonal degeneration, and may serve as a biomarker that reflects active axonal damage of CIDP.

A Global Survey of Disease Burden in Patients Who Carry a Diagnosis of Chronic Inflammatory Demyelinating Polyneuropathy

Introduction

The extent to which work productivity, emotional well-being, social interactions, and family life are impacted in patients who self-identify as having chronic inflammatory demyelinating polyneuropathy (CIDP) is not well characterized.

Methods

Data from an online survey of 595 individuals with self-reported CIDP, recruited by the Guillain–Barré syndrome (GBS)/CIDP Foundation, were used to assess disease and treatment burden. A total of 37% of patients were classified as “likely”, 34% as “somewhat likely”, and 28% as “unlikely” CIDP.

Results

Of ten symptoms that patients with CIDP may experience, each symptom was experienced by 77–94% of “likely”, 79–96% of “somewhat likely”, and 66–91% of “unlikely” patients. In “likely” CIDP patients 44% stopped working because of their symptoms and 24% moved to a new home. The most common treatments were intravenous immunoglobulin (IVIg) infusion and corticosteroids. IVIg was associated with venous access issues and work/school absenteeism.

Conclusions

CIDP diagnostic confirmation was not performed in any of the survey respondents. Our results do not add any knowledge on the diagnosis or treatment of CIDP. Our findings do provide insight into the symptoms that patients that think they have CIDP or have been told they have CIDP experience, explores how patients that are labeled as having CIDP view treatment expectations, and highlights how these symptoms affect home and work life. We hope that the findings are constructively used to get patients the services they need to improve quality of life, maintain employment, and ensure a safe home environment regardless of diagnostic accuracy.

Pathophysiology of Chronic Inflammatory Demyelinating Polyneuropathy: Insights into Classification and Therapeutic Strategy

Chronic inflammatory demyelinating polyneuropathy (CIDP) is classically defined as polyneuropathy with symmetric involvement of the proximal and distal portions of the limbs. In addition to this "typical CIDP", the currently prevailing diagnostic criteria proposed by the European Federation of Neurological Societies and Peripheral Nerve Society (EFNS/PNS) define "atypical CIDP" as encompassing the multifocal acquired demyelinating sensory and motor (MADSAM), distal acquired demyelinating symmetric (DADS), pure sensory, pure motor, and focal subtypes. Although macrophage-induced demyelination is considered pivotal to the pathogenesis of CIDP, recent studies have indicated the presence of distinctive mechanisms initiated by autoantibodies against paranodal junction proteins, such as neurofascin 155 and contactin 1. These findings led to the emergence of the concept of nodopathy or paranodopathy. Patients with these antibodies tend to show clinical features compatible with typical CIDP or DADS, particularly the latter. In contrast, classical macrophage-induced demyelination is commonly found in some patients in each major subtype, including the typical CIDP, DADS, MADSAM, and pure sensory subtypes. Differences in the distribution of lesions and the repair processes underlying demyelination by Schwann cells may determine the differences among subtypes. In particular, the preferential involvement of proximal and distal nerve segments has been suggested to occur in typical CIDP, whereas the involvement of the middle nerve segments is conspicuous in MADSAM. These findings suggest that humoral rather than cellular immunity predominates in the former because nerve roots and neuromuscular junctions lack blood-nerve barriers. Treatment for CIDP consists of intravenous immunoglobulin (IVIg) therapy, steroids, and plasma exchange, either alone or in combination. However, patients with anti-neurofascin 155 and contactin 1 antibodies are refractory to IVIg. It has been suggested that rituximab, a monoclonal antibody to CD20, could have efficacy in these patients. Further studies are needed to validate the CIDP subtypes defined by the EFNS/PNS from the viewpoint of pathogenesis and establish therapeutic strategies based on the pathophysiologies specific to each subtype.

Association between chronic inflammatory demyelinating polyneuropathy and gastrointestinal malignancies

Chronic inflammatory demyelinating polyneuropathy (CIDP) is an uncommon and under-recognized immune-mediated disorder of the peripheral nervous system. It is associated with both infectious and non-infectious etiologies and presents in several variant forms. In rare instances, CIDP has been reported in association with gastrointestinal (esophageal, hepatic, colorectal, and pancreatic) malignancies. The diagnosis of malignancy is typically preceded by weeks to months by that of CIDP, though the inverse may also be seen. As with other etiologies of CIDP, cases associated with gastrointestinal malignancies are often treated with corticosteroids, intravenous immunoglobulins, and/or plasma exchange, with improvement or resolution of neurological symptoms in the majority of cases. In this review, we provide a practical overview of CIDP, with an emphasis on recognizing the clinical association between CIDP and gastrointestinal malignancies.

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

OBJECTIVE

To characterize the frequency and patterns of optic, trigeminal, and facial nerve involvement by neuroimaging and electrophysiology in IgG4 anti-neurofascin 155 antibody-positive (NF155⁺ ) chronic inflammatory demyelinating polyneuropathy (CIDP).

METHODS

Thirteen IgG4 NF155⁺ CIDP patients with mean onset age of 34 years (11 men) were subjected to neurological examination, blink reflex, and visual-evoked potential (VEP) testing, and axial and/or coronal T2-weighted head magnetic resonance imaging (MRI).

RESULTS

Among 13 patients, facial sensory impairment, facial weakness, and apparent visual impairment were observed in three (23.1%), two (15.4%), and two (15.4%) patients, respectively. All 12 patients tested had blink reflex abnormalities: absent and/or delayed R1 in 11 (91.7%), and absent and/or delayed R2 in 10 (83.3%). R1 latencies had strong positive correlations with serum anti-NF155 antibody levels (r = 0.9, P ≤ 0.0001 on both sides) and distal and F wave latencies of the median and ulnar nerves. Absent and/or prolonged VEPs were observed in 10/13 (76.9%) patients and 17/26 (65.4%) eyes. On MRI, hypertrophy, and high signal intensity of trigeminal nerves were detected in 9/13 (69.2%) and 10/13 (76.9%) patients, respectively, whereas optic nerves were normal in all patients. The intra-orbital trigeminal nerve width on coronal sections showed a significant positive correlation with disease duration.

INTERPRETATION

Subclinical demyelination frequently occurs in the optic, trigeminal, and facial nerves in IgG4 NF155⁺ CIDP, suggesting that both central and peripheral myelin structures of the cranial nerves are involved in this condition, whereas nerve hypertrophy only develops in myelinated peripheral nerve fibers.

NK cell markers predict the efficacy of IV immunoglobulins in CIDP

Objective

To assess whether IV immunoglobulins (IVIgs) as a first-line treatment for chronic inflammatory demyelinating polyneuropathy (CIDP) have a regulative effect on natural killer (NK) cells that is related to clinical responsiveness to IVIg.

Methods

In a prospective longitudinal study, we collected blood samples of 29 patients with CIDP before and after initiation of IVIg treatment for up to 6 months. We used semiquantitative PCR and flow cytometry in the peripheral blood to analyze the effects of IVIg on the NK cells. The results were correlated with clinical aspects encompassing responsiveness.

Results

We found a reduction in the expression of several typical NK cell genes 1 day after IVIg administration. Flow cytometry furthermore revealed a reduced cytotoxic CD56^dim NK cell population, whereas regulatory CD56^bright NK cells remained mostly unaffected or were even increased after IVIg treatment. Surprisingly, the observed effects on NK cells almost exclusively occurred in IVIg-responsive patients with CIDP.

Conclusions

The correlation between the altered NK cell population and treatment efficiency suggests a crucial role for NK cells in the still speculative mode of action of IVIg treatment. Analyzing NK cell subsets after 24 hours of treatment initiation appeared as a predictive marker for IVIg responsiveness. Further studies are warranted investigating the potential of NK cell status as a routine parameter in patients with CIDP before IVIg therapy.

Classification of evidence

This study provides Class I evidence that NK cell markers predict clinical response to IVIg in patients with CIDP.

Cranial nerve involvement in typical and atypical chronic inflammatory demyelinating polyneuropathies

BACKGROUND AND PURPOSE

Cranial nerve palsy is occasionally present in patients with chronic inflammatory demyelinating polyneuropathy (CIDP), but its prevalence, characteristics and relations with the CIDP subtypes have rarely been investigated. The aim of this study was to systematically assess cranial nerve involvement in typical and atypical CIDP.

METHODS

Clinical data were reviewed in 132 consecutive patients with CIDP, including typical CIDP (n = 89), multifocal acquired demyelinating sensory and motor neuropathy (MADSAM) (n = 31), distal acquired demyelinating symmetric (DADS) (n = 9) and others (n = 3).

RESULTS

The frequency of cranial nerve palsy was 11% in typical CIDP, 48% in MADSAM and 11% in DADS. Facial and bulbar palsy was most frequently present (9%), followed by ocular motor nerve palsy (5%). Bilateral involvement was seen in all typical CIDP and DADS patients, whereas 80% of MADSAM patients had unilateral palsy. The presence of cranial nerve involvement was associated with more severe limb muscle weakness in typical CIDP, but not in MADSAM. Cranial nerve palsy fully recovered in 90% of typical CIDP and in 67% of MADSAM patients.

CONCLUSION

Amongst the CIDP subtypes, cranial palsy is frequent and unilateral in MADSAM, and less frequent and bilateral in typical CIDP and DADS. In typical CIDP, facial and bulbar palsy reflects more severe and extensive inflammation.

Effects of microRNA-338 Transfection into Sciatic Nerve on Rats with Experimental Autoimmune Neuritis

Nerve demyelination or axonal lesions are characteristic of experimental autoimmune neuritis (EAN). Previous studies have demonstrated that microRNA-338 can regulate the differentiation and maturation of oligodendrocytes and Schwann cells and promote injured peripheral nerves in rats. In this study, we used microRNA-338 coded lentivirus vector (miR-338-LV) in a Lewis rat EAN model, in with the conjunction P0 peptide 180-199 which was injected into the footpads of animals to induce immunization. The clinical scores of miR-338-LV and intravenous immunoglobulin (IVIg) (positive drug) groups were significantly superior to those of untreated group at disease peak and disease plateau (p < 0.05). The nerve conduction velocity and the compound nerve action potential amplitude of miR-338-LV and IVIg groups increased significantly compared to those of the untreated group at disease peak (p < 0.01). At disease peak, myelin swelling, cavity formation, and lamellae separation showed improvement in miR-338-LV and IVIg groups compared to untreated group. S100 and NF200 expression in miR-338-LV and IVIg groups increased compared to that in untreated group. Iba1 and S100 co-expression in Schwann cells in miR-338-LV and IVIg groups decreased compared to that in untreated group, which was indicative of the reduced conversion of Schwann cells into inflammatory cells. Overall, miR-338-LV in sciatic nerves might improve neuromuscular function in EAN by inhibiting the conversion of Schwann cells into inflammatory cells.

Dramatic clinical response to ultra-high dose IVIg in otherwise treatment resistant inflammatory neuropathies

BACKGROUND

Intravenous immunoglobulin (IVIg) has short and long-term efficacy in both chronic inflammatory demyelinating polyneuropathy (CIDP) and multifocal motor neuropathy with conduction block (MMNCB). There is potential for under and over-treatment if trial regimens are strictly adhered to in clinical practice where titrating dose to clinical response is recommended.

METHODS

We report the response to high-dose IVIg (>2 g/kg/6 weeks) in a subgroup of patients with definite CIDP or MMNCB who were unresponsive to 'usual' dosing. IVIg frequency and dosing was determined for each individual by subjective and objective outcome measures for impairment, grip strength, and activity and participation.

RESULTS

Six patients (three with chronic inflammatory demyelinating polyneuropathy (CIDP), three with MMN) were included. Two patients (one CIDP and one MMNCB) returned to full-time work on fractionated IVIg doses of 5 g/kg/month and 9 g/kg/month. Patient three (CIDP) failed numerous other immunosuppressants but responded to short-term fractionated 4 g/kg/month of IVIg. Patient four has severe, refractory, childhood-onset CIDP, remains stable but dependent currently on 6.9 g/kg/month of IVIg. Patients five and six, both with MMNCB, required short term 4.5-5 g/kg/month to recover significant bilateral hand strength. No IVIg-related adverse events occurred in any individual.

CONCLUSIONS

These six cases demonstrate the safety and effectiveness of a treatment approach that includes individualised but evidence-based clinical assessment and, when necessary, high-doses of IVIg to restore patients' strength and ability to participate in activities of daily activities. Careful patient selection is important.

An international multicenter efficacy and safety study of IqYmune in initial and maintenance treatment of patients with chronic inflammatory demyelinating polyradiculoneuropathy: PRISM study

This prospective, multicenter, single‐arm, open‐label phase 3 study aimed to evaluate the efficacy and safety of IqYmune in patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Patients received one induction dose of 2 g/kg and then seven maintenance doses of 1 g/kg at 3‐week intervals. The primary endpoint was the responder rate at the end of study (EOS), defined as an improvement of ≥1 point on the adjusted inflammatory neuropathy cause and treatment (INCAT) disability scale. The responder rate was compared with the responder rate of a historical placebo group (33.3%). Secondary endpoints included changes from baseline to EOS of adjusted INCAT disability score, grip strength, Medical Research Council (MRC) sum score, Rasch‐modified MRC sum score, Rasch‐built overall disability scale score and the clinical global impression. Forty‐two patients, including 23 Ig‐naïve and 19 Ig‐pre‐treated, were included in the efficacy set. The overall response rate at EOS was 76.2% (95% confidence interval [60.5%‐87.9%]). The superiority of IqYmune compared to the historical placebo control was demonstrated (P < .0001). The responder rate was numerically higher in Ig‐pre‐treated than in Ig‐naïve patients but confidence intervals were overlapping (84.2% [60.4%‐96.6%] vs 69.6% [47.1%‐86.8%]). All secondary endpoints confirmed this conclusion. The median time to response was 15 weeks [8.9‐19.1 weeks]. A total of 156 adverse events including five serious were considered related to IqYmune, 87.2% were mild. Neither hemolysis nor signs of renal or hepatic impairment were observed. These results demonstrate that IqYmune is an effective and well‐tolerated treatment in patients with CIDP.

[A case of neurofascin-155 antibody-positive chronic inflammatory demyelinating polyradiculoneuropathy successfully treated with Cyclosporine A]

A 41-year-old man noticed numbness of the fingers and toes, and gradually developed limb weakness and sensory impairment. The patient was diagnosed with typical chronic inflammatory demyelinating polyradiculoneuropathy. Over the course of clinical diagnosis, the limb and trunk ataxia, and finger tremor became prominent, and the presence anti-neurofascin-155 antibody was examined and confirmed positive. The effects of corticosteroids, intravenous immunoglobulin, and plasma apheresis were limited, and the disease progressed slowly and noticeably. Therefore, cyclosporine was introduced as treatment, and the patient's weakness and ataxia significantly improved. Rituximab treatment is expected to be effective in patients with the same antibody and immunosuppressant treatment may be useful in intractable cases.

Demyelinating polyneuropathy and lymphoplasmacytic lymphoma coexisting in 36-year-old man: A case report

BACKGROUND

Lymphoplasmacytic lymphoma is a rare non-Hodgkin’s lymphoma, occurring mostly in the elderly. It develops slowly and leads to malignant proliferation of lymphoid line cells in the bone marrow, lymph nodes and spleen. It may also affect nerve roots and meninges; some patients develop sensorimotor polyneuropathy which may precede general symptoms of lymphoma.

CASE SUMMARY

We present a case of a 36-year-old man diagnosed in 2012 with chronic inflammatory demyelinating polyneuropathy (CIDP), then he was hospitalized in 2019 due to progressive symptoms of heart failure and significant weight loss over the previous four months. Based on clinical and laboratory findings a diagnosis of lymphoplasmacytic lymphoma was suspected and confirmed by bone marrow flow cytometry. There was no improvement in the results of laboratory tests and the patient's condition after immediate implementation of chemotherapy. Patient died on the fifth day of treatment.

CONCLUSION

While CIDP and malignant disease co-occurrence is rare, it should be suspected and investigated in patients with atypical neuropathy symptoms.