Intravenous immunoglobulin treatment in multifocal motor neuropathy

Immunoglobulin Use for the Management of Painful Peripheral Neuropathy: A Systematic Review and Meta-Analysis

BACKGROUND

Immunoglobulins (IG) are widely used for the treatment of a variety of immune-mediated diseases. The exact mechanism of action remains unknown, but IG modulate the expression and function of Fc receptors, interfere with complement activation and production of cytokines, neutralize pathogenic autoantibodies, and affect the activation and effector functions of B and T lymphocytes. Immunoglobulins are usually delivered intravenously, and are effective in ameliorating motor symptoms, and/or preventing disease progression in immune-mediated neuropathies, including Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathy.

OBJECTIVE

The aim of this systematic review and meta-analysis was to study the potential of IG for the treatment of painful peripheral neuropathy (PPN). The outcome of interest was the percentage of patients with PPN who achieved pain relief following IG administration.

METHODS

We performed a systematic literature search on March 17, 2022, in the PubMed database without any publication date restrictions. We also looked for unpublished or ongoing trials in clinicaltrials.org. Pain reduction following IG treatment had to be within the aims (primary or secondary).

RESULTS

The aforementioned literature search strategy revealed five studies (two open-label, three randomized placebo-controlled) eligible to be included. The pooled estimate of the percentage of patients with PPN who received immunoglobulins and reported pain relief was found to be 65% (95% CI 58-71%). The likelihood of achieving pain relief with immunoglobulin treatment was 2.9 times higher (95% CI 1.6-5.2) compared to placebo (p = 0.0003).

CONCLUSION

The use of IG for the treatment of pain due to peripheral neuropathy has a potential therapeutic benefit. Further studies across patients with different types of painful peripheral neuropathy are needed to better characterize this effect. Registration number on PROSPERO: CRD42022319614.

Anti-C2 Antibody ARGX-117 Inhibits Complement in a Disease Model for Multifocal Motor Neuropathy

Background and Objectives

To determine the role of complement in the disease pathology of multifocal motor neuropathy (MMN), we investigated complement activation, and inhibition, on binding of MMN patient-derived immunoglobulin M (IgM) antibodies in an induced pluripotent stem cell (iPSC)-derived motor neuron (MN) model for MMN.

Methods

iPSC-derived MNs were characterized for the expression of complement receptors and membrane-bound regulators, for the binding of circulating IgM anti-GM1 from patients with MMN, and for subsequent fixation of C4 and C3 on incubation with fresh serum. The potency of ARGX-117, a novel inhibitory monoclonal antibody targeting C2, to inhibit fixation of complement was assessed.

Results

iPSC-derived MNs moderately express the complement regulatory proteins CD46 and CD55 and strongly expressed CD59. Furthermore, MNs express C3aR, C5aR, and complement receptor 1. IgM anti-GM1 antibodies in serum from patients with MMN bind to MNs and induce C3 and C4 fixation on incubation with fresh serum. ARGX-117 inhibits complement activation downstream of C4 induced by patient-derived anti-GM1 antibodies bound to MNs.

Discussion

Binding of IgM antibodies from patients with MMN to iPSC-derived MNs induces complement activation. By expressing complement regulatory proteins, particularly CD59, MNs are protected against complement-mediated lysis. Yet, because of expressing C3aR, the function of these cells may be affected by complement activation upstream of membrane attack complex formation. ARGX-117 inhibits complement activation upstream of C3 in this disease model for MMN and therefore represents an intervention strategy to prevent harmful effects of complement in MMN.

Expanding the Role of the Pharmacist: Immunoglobulin Therapy and Disease Management in Neuromuscular Disorders

Immunoglobulin G (IgG) is a commonly used treatment for chronic neuromuscular disorders (NMDs), such as chronic inflammatory demyelinating polyneuropathy and multifocal motor neuropathy. IgG therapy has also shown promise in treating other NMDs including myasthenia gravis, polymyositis, and dermatomyositis. IgG is administered as either intravenous immunoglobulin (IVIg) or subcutaneous immunoglobulin (SCIg), with SCIg use becoming more popular due to the treatment burden associated with IVIg. IVIg requires regular venous access; long infusions (typically 4-6 hours); and can result in systemic adverse events (AEs) for some patients. In contrast, SCIg can be self-administered at home with shorter infusions (approximately 1 hour) and fewer systemic AEs. As patient care shifts toward home-based settings, the role of the pharmacist is paramount in providing a continuation of care and acting as the bridge between patient and clinic. Pharmacists with a good understanding of current recommendations, dosing strategies, and administration routes for IgG therapy are best placed to support patients. The aims of this review are to highlight the evidence supporting IgG therapy in the treatment of NMDs and provide practical information on patient management and IVIg/SCIg dosing in order to guide pharmacists on optimizing clinical outcomes and patient care.

SARS-CoV-2 Inflammatory Syndrome. Clinical Features and Rationale for Immunological Treatment

The current pandemic coronavirus, SARS-CoV-2, is a global health emergency because of its highly contagious nature, the great number of patients requiring intensive care therapy, and the high fatality rate. In the absence of specific antiviral drugs, passive prophylaxis, or a vaccine, the treatment aim in these patients is to prevent the potent virus-induced inflammatory stimuli from leading to the acute respiratory distress syndrome (ARDS), which has a severe prognosis. Here, the mechanism of action and the rationale for employing immunological strategies, which range from traditional chemically synthesized drugs, anti-cytokine antibodies, human immunoglobulin for intravenous use, to vaccines, are reviewed.

SARS-CoV-2 Inflammatory Syndrome. Clinical Features and Rationale for Immunological Treatment

The current pandemic coronavirus, SARS-CoV-2, is a global health emergency because of its highly contagious nature, the great number of patients requiring intensive care therapy, and the high fatality rate. In the absence of specific antiviral drugs, passive prophylaxis, or a vaccine, the treatment aim in these patients is to prevent the potent virus-induced inflammatory stimuli from leading to the acute respiratory distress syndrome (ARDS), which has a severe prognosis. Here, the mechanism of action and the rationale for employing immunological strategies, which range from traditional chemically synthesized drugs, anti-cytokine antibodies, human immunoglobulin for intravenous use, to vaccines, are reviewed.

Clinical Mimickers of Amyotrophic Lateral Sclerosis-Conditions We Cannot Afford to Miss

Giving a diagnosis of amyotrophic lateral sclerosis to a patient is akin to handing out a death certificate. However, not all patients presenting with the classical dysphagia, wasting, and weakness may have motor neuron diseases. In these cases, it is extremely important not to miss little cues which can suggest an alternative diagnosis and in many cases a lease of life in terms of a treatment option. In this review, we consider some clinical scenarios that can present with the same symptom complex as diseases involving motor neurons but have a different anatomical or etiopathological basis and in many cases even a therapeutic option.

Nerve ultrasound as follow-up tool in treated multifocal motor neuropathy

BACKGROUND AND PURPOSE

High-resolution ultrasound is a valuable tool in supporting the diagnosis of multifocal motor neuropathy (MMN) but longitudinal data under therapy are lacking.

METHODS

The change in peripheral nerve ultrasound pattern in patients with MMN was assessed over time. Patients with MMN received a thorough initial examination and follow-up over a period of 6-12 months using high-resolution ultrasound of the cervical roots and the nerves of the arms and legs, nerve conduction studies, Medical Research Council Sum Score (MRCSS) and Rotterdam Inflammatory Neuropathy Cause and Treatment Group (INCAT) score to evaluate changes under treatment. The Ultrasound Pattern Sum Score (UPSS) was used as standardized peripheral nerve ultrasound protocol.

RESULTS

Seventeen patients with MMN received initial examinations of whom 12 were successfully followed up. All patients with MMN showed at least localized but often multifocal peripheral nerve enlargement. An enlarged overall cross-sectional area as well as enlarged single fascicles (>3 mm²) in clinically and electrophysiologically affected (>90%) and unaffected (>70%) nerves were found. The UPSS did not correlate with clinical disability at both visits. However, the change in clinical disability (evaluated as difference in MRCSS) and the change in UPSS correlated significantly inversely (P = 0.004).

CONCLUSIONS

High-resolution sonography of peripheral nerves revealed multifocal nerve enlargement in MMN. Distinct enlargement patterns may support the diagnosis. Ultrasound findings did not correlate well with clinical severity or electrophysiological findings at initial presentation. As changes in UPSS correlated significantly with the clinical course in terms of muscle strength (MRCSS), sonographic assessment may represent a useful tool for therapeutic monitoring.

Is dosing of therapeutic immunoglobulins optimal? A review of a three-decade long debate in europe

The consumption of immunoglobulins (Ig) is increasing due to better recognition of antibody deficiencies, an aging population, and new indications. This review aims to examine the various dosing regimens and research developments in the established and in some of the relevant off-label indications in Europe. The background to the current regulatory settings in Europe is provided as a backdrop for the latest developments in primary and secondary immunodeficiencies and in immunomodulatory indications. In these heterogeneous areas, clinical trials encompassing different routes of administration, varying intervals, and infusion rates are paving the way toward more individualized therapy regimens. In primary antibody deficiencies, adjustments in dosing and intervals will depend on the clinical presentation, effective IgG trough levels and IgG metabolism. Ideally, individual pharmacokinetic profiles in conjunction with the clinical phenotype could lead to highly tailored treatment. In practice, incremental dosage increases are necessary to titrate the optimal dose for more severely ill patients. Higher intravenous doses in these patients also have beneficial immunomodulatory effects beyond mere IgG replacement. Better understanding of the pharmacokinetics of Ig therapy is leading to a move away from simplistic "per kg" dosing. Defective antibody production is common in many secondary immunodeficiencies irrespective of whether the causative factor was lymphoid malignancies (established indications), certain autoimmune disorders, immunosuppressive agents, or biologics. This antibody failure, as shown by test immunization, may be amenable to treatment with replacement Ig therapy. In certain immunomodulatory settings [e.g., idiopathic thrombocytopenic purpura (ITP)], selection of patients for Ig therapy may be enhanced by relevant biomarkers in order to exclude non-responders and thus obtain higher response rates. In this review, the developments in dosing of therapeutic immunoglobulins have been limited to high and some medium priority indications such as ITP, Kawasaki' disease, Guillain-Barré syndrome, chronic inflammatory demyelinating polyradiculoneuropathy, myasthenia gravis, multifocal motor neuropathy, fetal alloimmune thrombocytopenia, fetal hemolytic anemia, and dermatological diseases.

Sera from patients with multifocal motor neuropathy disrupt the blood-nerve barrier

OBJECTIVE

In multifocal motor neuropathy (MMN), the destruction of the blood-nerve barrier (BNB) has been considered to be the key step in the disease process. The purpose of the present study was to ascertain whether sera from patients with MMN can open the BNB, and which component of patient sera is the most important for this disruption.

METHODS

We evaluated the effects of sera from patients with MMN, patients with amyotrophic lateral sclerosis, and control subjects on the expression of tight junction proteins and vascular cell adhesion molecule-1 (VCAM-1), and on the transendothelial electrical resistance (TEER) in human peripheral nerve microvascular endothelial cells (PnMECs).

RESULTS

The sera from patients with MMN decreased the claudin-5 protein expression and the TEER in PnMECs. However, this effect was reversed after application of an anti-vascular endothelial growth factor (anti-VEGF) neutralising antibody. The VEGF secreted by PnMECs was significantly increased after exposure to the sera from patients with MMN. The sera from patients with MMN also increased the VCAM-1 protein expression by upregulating the nuclear factor kappa-B (NF-κB) signalling. The immunoglobulin G purified from MMN sera decreased the expression of claudin-5 and increased the VCAM-1 expression in PnMECs.

CONCLUSIONS

The sera from MMN patients may disrupt the BNB function via the autocrine secretion of VEGF in PnMECs, or the exposure to autoantibodies against PnMECs that are contained in the MMN sera. Autoantibodies against PnMECs in MMN sera may activate the BNB by upregulating the VCAM-1 expression, thereby allowing for the entry of a large number of circulating inflammatory cells into the peripheral nervous system.

Multifocal motor neuropathy

PURPOSE OF REVIEW

Multifocal motor neuropathy (MMN) remains a difficult issue for neurologists, as its clinical and electrophysiological presentation may be atypical, and because no alternative treatment to periodic immunoglobulin infusions has been assessed in its long-term management. This review intends to summarize the most recent advances in the diagnosis and treatment of MMN.

RECENT FINDINGS

Recent reports have focused on atypical onset and unusual clinical presentation. Several sophisticated electrophysiological techniques, as triple stimulation, may help establish the presence of conduction blocks, as well as MRI findings. A recent immunological study focused on the detection of serum IgM binding to NS6S heparin disaccharide. In another research article, it was proposed that the use of combinatorial glycoarray or ELISA may increase the diagnostic sensitivity of antiglycolipid antibody testing. Subcutaneous immunoglobulin may represent an interesting alternative option to intravenous immunoglobulin. Lastly, recently reported open-label clinical trials with complement inhibitors and anti-CD20 monoclonal antibody may constitute a first step for further developments.

SUMMARY

Diagnostic criteria for MMN are well established, but challenging situations still occur. Progresses in neurophysiologic and other laboratory tests may help in clarifying doubtful diagnoses. Current research into the pathophysiology of MMN is required to determine the future treatment targets.

Multifocal motor neuropathy

Multifocal motor neuropathy (MMN) is a chronic immune-mediated neuropathy that is particular for its asymmetric, multifocal, purely motor clinical presentation, often related to the distribution of individual nerves. Upper limbs are usually primarily and more severely affected, but lower limbs may be involved during the course of the disease. The hallmark of the disease is the presence, in electrophysiological studies, of persistent conduction blocks in the affected motor nerves, located outside the usual sites of nerve compression, contrasting with normal sensory nerve conduction velocities. The most typical laboratory finding is the presence of high levels of serum IgM antibodies to the ganglioside GM1, and less frequently to asialo-GM1, GD1a or GM2. These striking features may help distinguishing this neuropathy from both motor neuron disease and other chronic immune-mediated neuropathies. Several randomized controlled trials (RCT) have established the efficacy of high-dose intravenous immunoglobulin (IVIg), as well as subcutaneous immunoglobulin (SCIg). However, this therapy has a short-lasting effect, and need to be maintained with periodic infusions. This disappointing status has led to the search of other immune therapies whose efficacy has not been so far confirmed in RCT. This review intends to summarize current contents in the diagnosis and the treatment of MMN.

Susac syndrome and multifocal motor neuropathy first manifesting in pregnancy

Susac Syndrome (SS) and multifocal motor neuropathy (MMN) are rare autoimmune neurological conditions which can affect women of childbearing years. The effect of pregnancy on these disorders is poorly characterised. We report a case of SS first manifesting in pregnancy with challenges in diagnosis and management and a poor clinical outcome, and a case of MMN manifesting in pregnancy then relapsing in a subsequent pregnancy. A summary of other cases in the literature and the postulated underlying immune mechanisms is presented.

Multifocal motor neuropathy

Multifocal motor neuropathy (MMN) is a rare disorder in which the symptoms are caused by persistent conduction block lesions. The mononeuropathy multiplex progresses over time with increasing axonal loss. The cause of the conduction blocks and axonal loss are not completely understood but immune mechanisms are involved and response to intravenous immunoglobulin has been established. The importance of MMN goes beyond its clinical incidence as the increasing understanding of the pathogenesis of this disorder has implications for other peripheral nerve diseases and for our knowledge of peripheral nerve biology.

Plasma exchange and intravenous immunoglobulins: mechanism of action in immune-mediated neuropathies

Immune-mediated neuropathies are a heterogeneous group of peripheral nerve disorders, which are classified by time course, clinical pattern, affected nerves and pathological features. Plasma exchange (PE) and intravenous immunoglobulins (IVIg) are mainstays in the treatment of immune-mediated neuropathies. Of all treatments currently used, IVIg has probably the widest application range in immune-mediated neuropathies and efficacy has been well documented in several randomized controlled trials for Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathy (CIDP). Beneficial effects of IVIg have also been proven for multifocal motor neuropathy (MMN). Likewise, PE is an established treatment for GBS and CIDP, whereas it is considered to be ineffective in MMN. Different mechanisms of action are sought to be responsible for the immunemodulatory effect of PE and IVIg in autoimmune disorders. Some of those might be important for immune-mediated neuropathies, while others are probably negligible. The aim of this review is to summarize the recent advances in elucidating disease-specific mechanisms of actions of PE and IVIg in the treatment of immune-mediated neuropathies.

Immunomodulatory therapy to achieve maximum efficacy: doses, monitoring, compliance, and self-infusion at home

INTRODUCTION

The Oxford Programme for Immunomodulatory Immunoglobulin Therapy has been operating since 1992 at Oxford Radcliffe Hospitals in the UK. Initially, this program was set up for patients with multifocal motor neuropathy or chronic inflammatory demyelinating poly-neuropathy to receive reduced doses of intravenous immunoglobulin (IVIG) in clinic on a regular basis (usually every 3 weeks). The program then rapidly expanded to include self-infusion at home, which monitoring showed to be safe and effective. It has been since extended to the treatment of other autoimmune diseases in which IVIG has been shown to be efficacious.

METHODS

This review includes details of the program such as the training of patients, dosing with immunoglobulin, and monitoring and compliance for self-infusion at home, with cases to illustrate these points.

RESULTS

In addition, the Evidence for efficacy and the effects of confounding morbidities will be are included described. More recently, subcutaneous immunoglobulin therapy (SCIG) has been used in several chronic autoimmune peripheral neuropathies and in epidermolysis bullosa acquisita, with equally good effect. Trials of SCIG in other autoimmune diseases are planned.