Comparing treatment options for chronic inflammatory neuropathies and choosing the right treatment plan

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.

Immunoglobulin use in neurology: a practical approach

Human immunoglobulin, delivered either intravenously (IVIg) or subcutaneously, is used to treat a range of immune-mediated neurological disorders. It has a role in acute or subacute inflammatory disease control and as a maintenance therapy in chronic disease management. This review considers mechanisms of IVIg action and the evidence for IVIg in neurological conditions. We use Guillain-Barré syndrome and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) as frameworks to demonstrate an approach to IVIg use in acute and chronic dysimmune neurological conditions across two different healthcare systems: the UK and Australia. We highlight the benefits and limitations of IVIg and focus on practical considerations such as informed consent, managing risks and adverse effects, optimal dosing and monitoring response. We use these basic clinical practice principles to discuss the judicious use of an expensive and scarce blood product with international relevance.

Cytokines and chemokines in patients with chronic inflammatory demyelinating polyradiculoneuropathy and multifocal motor neuropathy: A systematic review

Advances in the understanding of cytokines have revolutionized mechanistic treatments for chronic inflammatory and autoimmune diseases, as exemplified by rheumatoid arthritis. We conducted a systematic literature review on the role of cytokines and chemokines in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and multifocal motor neuropathy (MMN). Ovid Medline, EMBASE and Web of Science were searched until August 31, 2022 for human studies investigating cytokines levels in CIDP or MMN. Fifty-five articles on 1061 CIDP patients and 86 MMN patients were included, with a median of 18 patients per study (range 3-71). Studies differed in the inclusion criteria, type of assay, manufacturer, control subjects, and tested biological material. Only a minority of studies reported data on disease activity. Interleukin (IL)-6, IL-17, CXCL10, and tumor necrosis factor alpha (TNF-α), were elevated in CIDP compared to controls in most of the studies. IL-6 and TNF-α levels are also correlated with disability. In MMN patients, IL-1Ra was elevated in the majority of the reports. While acknowledging the challenges in comparing studies and the various limitations of the studies, including small patient numbers, particularly in MMN, our review suggests that IL-6, IL-17, CXCL10, and TNF-α might play a role in CIDP pathogenesis. Larger studies are needed in MMN.

Outcome in chronic inflammatory demyelinating polyneuropathy: A systematic review and meta-analysis

INTRODUCTION/AIMS

Outcomes in chronic inflammatory demyelinating polyneuropathy (CIDP) have been reported in longitudinal and cross-sectional studies. A considerable variation in long-term disease outcome has appeared in those reports. To overcome this uncertainty, a systematic review and meta-analysis was conducted on CIDP outcomes, including the parameters of case fatality rate, ambulation, physical ability, and remission.

METHODS

In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a systematic search was conducted in PubMed and EMBASE (OVID) for reports with at least 2 years of follow-up on patients with active or previously active CIDP that were published no later than May 12, 2022. Studies were appraised for quality using the Joanna Briggs Institute Critical Appraisal Checklist for studies reporting prevalence data. Pooled analyses were conducted and the results were visualized using forest plots. The study protocol was registered prospectively on PROSPERO (CRD42021266903).

RESULTS

A total of 1290 titles were identified. Sixty-nine full-text articles were screened and 21 studies with 1199 patients were selected for the data analysis. The pooled case fatality rate was 3.3% (95% confidence interval [CI], 1.9% to 5.7%). The pooled fraction of nonambulatory patients was 8.2% (95% CI, 5.7% to 11.6%) and, overall, 47.1% (95% CI, 39.5% to 54.9%) of CIDP patients had a good outcome without disability. The pooled rate of remission was 40.8% (95% CI, 30.6% to 51.8%).

DISCUSSION

Future research is warranted on how to prevent long-term impairment in CIDP. Care should be taken in developing clinical strategies to avoid immunomodulating therapy in the many patients in remission.

Chronic Immune-Mediated Polyneuropathies

This article discusses the chronic immune-mediated polyneuropathies, a broad category of acquired polyneuropathies that encompasses chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), the most common immune-mediated neuropathy, the CIDP variants, and the vasculitic neuropathies. Polyneuropathies associated with rheumatological diseases and systemic inflammatory diseases, such as sarcoidosis, will also be briefly covered. These patients' history, examination, serum studies, and electrodiagnostic studies, as well as histopathological findings in the case of vasculitis, confirm the diagnosis and differentiate them from the more common length-dependent polyneuropathies. Prompt identification and initiation of treatment is imperative for these chronic immune-mediated polyneuropathies to prevent disability and even death.

Chronic Inflammatory Demyelinating Polyradiculoneuropathy and Its Variants

PURPOSE OF REVIEW

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and its variants comprise a group of immune-mediated neuropathies with distinctive clinical presentations and electrodiagnostic features. Prompt recognition of these treatable disorders is mandatory as delays result in significant disability and morbidity. This article highlights the clinical presentation, pathophysiology, diagnostic evaluation, and treatment approach of these polyneuropathies.

RECENT FINDINGS

The spectrum of CIDP is expanding with the recent characterization of neuropathies associated with nodal and paranodal antibodies. These neuropathies are distinguished by their unique presentations and are often refractory to IV immunoglobulin (IVIg) therapy. Subcutaneous immunoglobulins have recently been approved as a treatment option for CIDP and join corticosteroids, IVIg, and plasma exchange as first-line treatment.

SUMMARY

CIDP is characterized by progressive symmetric proximal and distal weakness, large fiber sensory loss, and areflexia, with clinical nadir reached more than 8 weeks after symptom onset. Autoimmune demyelinating neuropathies fall on a continuum, with differences in the type of nerve fibers affected and pattern of deficits. Distinguishing between typical CIDP and its variants allows for selection of the most appropriate treatment.

Sustained response to subcutaneous immunoglobulins in chronic ataxic neuropathy with anti-disialosyl IgM antibodies (CANDA): report of two cases and review of the literature

INTRODUCTION

Chronic ataxic neuropathy with anti-disialosyl IgM antibodies (CANDA) is a rare disorder for which the pathological, neurophysiological, and therapeutic evidence remains anecdotal and controversial.

METHODS

This report on CANDA focuses on the neurophysiological patterns and treatment responses shared by two cases. One patient underwent nerve ultrasound follow-up. A comprehensive review of the literature highlighted the diverse experiences with different treatment options.

RESULTS

Response to different therapies was similar in both patients: intravenous immunoglobulins achieved a favorable response albeit with significant wearing-off fluctuations; treatment with subcutaneous immunoglobulins (SCIg) was an effective alternative leading to a clinical response for at least 2 years. Rituximab, which was trialed in both patients, was not continued long enough to determine its efficacy in modifying the disease course and/or modulating responsiveness to immunoglobulins. Steroids caused clinical worsening in both patients.

CONCLUSIONS

Immunoglobulin therapy appeared as the most effective in the treatment of these two patients. SCIg provided an effective treatment option for the long-term management of CANDA.

Guidelines on the Use of Therapeutic Apheresis in Clinical Practice - Evidence-Based Approach from the Writing Committee of the American Society for Apheresis: The Eighth Special Issue

The American Society for Apheresis (ASFA) Journal of Clinical Apheresis (JCA) Special Issue Writing Committee is charged with reviewing, updating and categorizing indications for the evidence-based use of therapeutic apheresis (TA) in human disease. Since the 2007 JCA Special Issue (Fourth Edition), the committee has incorporated systematic review and evidence-based approaches in the grading and categorization of apheresis indications. This Eighth Edition of the JCA Special Issue continues to maintain this methodology and rigor in order to make recommendations on the use of apheresis in a wide variety of diseases/conditions. The JCA Eighth Edition, like its predecessor, continues to apply the category and grading system definitions in fact sheets. The general layout and concept of a fact sheet that was introduced in the Fourth Edition, has largely been maintained in this edition. Each fact sheet succinctly summarizes the evidence for the use of TA in a specific disease entity or medical condition. The Eighth Edition comprises 84 fact sheets for relevant diseases and medical conditions, with 157 graded and categorized indications and/or TA modalities. The Eighth Edition of the JCA Special Issue seeks to continue to serve as a key resource that guides the utilization of TA in the treatment of human disease.

Therapeutic Plasma Exchange in Guillain-Barre Syndrome and chronic inflammatory demyelinating polyradiculoneuropathy

Therapeutic plasma exchange (TPE) has been used as a treatment modality in many autoimmune disorders, including neurological conditions, such as Guillain-Barre syndrome (GBS) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). The American Society for Apheresis (ASFA) publishes its guidelines on the use of therapeutic apheresis every 3 years based on published evidence to assist physicians with both the medical and technical aspects of apheresis consults. The ASFA Guidelines included the use of TPE in both GBS and CIDP as an acceptable first-line therapy, either alone and/or in conjunction with other therapeutic modalities. In this article, we briefly reviewed GBS and CIDP, discussed the role of apheresis in these conditions as well as various technical aspects of the TPE procedure, such as apheresis calculation, number of volume exchange, replacement fluid, and management of potential complications.

Outcomes after single-cycle rituximab monotherapy in patients with anti-MAG polyneuropathy: A bi-center experience with an average follow-up of 11 years

Rituximab is efficacious in myelin-associated glycoprotein (MAG) polyneuropathy, but the question on timing of retreatments is open. We studied 21 anti-MAG polyneuropathy patients who responded to a first cycle of rituximab, were followed-up for an average of 11.2 years, and were retreated only when relapsing. Baseline serum B-cell-activating factor (BAFF) levels were measured. Clinical improvements lasted on average 6 years, and as many as 71% of the patients resulted long-lasting responders. Severity of disease and high serum BAFF levels (cut-off ≥860 pg/mL for relapse risk) at onset seemed to predict worse prognosis. Measurements of these variables could help deal with the issue of maintenance rituximab therapy in MAG polyneuropathy.

Polyneuropathies

BACKGROUND

Polyneuropathies (peripheral neuropathies) are the most common type of disorder of the peripheral nervous system in adults, and specifically in the elderly, with an estimated prevalence of 5-8%, depending on age. The options for treatment depend on the cause, which should therefore be identified as precisely as possible by an appropriate diagnostic evaluation.

METHODS

This review is based on the current guidelines and on large-scale cohort studies and randomized, controlled trials published from 2000 to 2017, with an emphasis on non-hereditary types of polyneuropathy, that were retrieved by a selective search in PubMed.

RESULTS

Diabetes is the most common cause of polyneuropathy in Europe and North America. Alcohol-associated polyneuropathy has a prevalence of 22-66% among persons with chronic alcoholism. Because of the increasing prevalence of malignant disease and the use of new chemotherapeutic drugs, chemotherapy-induced neuropathies (CIN) have gained in clinical importance; their prevalence is often stated to be 30-40%, with high variation depending on the drug(s) and treatment regimen used. Polyneuropathy can also arise from genetic causes or as a consequence of vitamin deficiency or overdose, exposure to toxic substances and drugs, and a variety of immunological processes. About half of all cases of polyneu - ropathy are associated with pain. Neuropathic pain can be treated symptomatically with medication. Exercise, physiotherapy, and ergotherapy can also be beneficial, depending on the patient's symptoms and functional deficits.

CONCLUSION

A timely diagnosis of the cause of polyneuropathy is a prerequisite for the initiation of appropriate specific treatment. Patients with severe neuropathy of unidentified cause should be referred to a specialized center for a thorough diagnostic evaluation.

Immunoglobulin Treatment in Neuromuscular Medicine

Intravenous immunoglobulin (IVIg) is used in the treatment of autoimmune diseases, including immune-mediated central and peripheral nervous system disorders. This article will review the indications, proposed mechanism of actions, and administration of immunoglobulin treatment in various neuropathies, neuromuscular junction disorders, and myopathies. IVIg may have more than one mechanism of action to alter the pathogenesis of underlying neuromuscular disease. IVIg treatment has been used as a first-line treatment in Guillain-Barre syndrome, chronic inflammatory demyelinating polyradiculoneuropathy, multifocal motor neuropathy, and second-line off-label treatment in medically refractory cases of polymyositis, dermatomyositis, and myasthenia gravis. IVIg is a well-tolerated and effective treatment for these neuromuscular diseases. With this review article, we hope to increase clinicians' awareness of the indications and efficiencies of IVIg in a broad spectrum of neuromuscular diseases.

The role of plasma exchange in the management of autoimmune disorders

Therapeutic plasma exchange (TPE) has been mainly used in the treatment of autoimmune diseases. The main mechanisms of action of TPE include the removal of circulating autoantibodies, immune complexes, complement components, cytokines and adhesion molecules, along with sensitization of antibody-producing cells to immunosuppressant agents. TPE is useful in autoimmune haematological, renal, rheumatic and neurological diseases, and is recommended for acute disorders, together with relapsed or worsened chronic diseases that are often unresponsive to conventional treatments. The American Society for Apheresis and the British Society of Haematology have published guidelines on the clinical use of apheresis procedures, indicating the different levels of efficacy of TPE. Based on the evidence from current literature and our personal experience, this review discusses the indications and the suggested regimens for TPE in autoimmune haematological and non-haematological disorders.

FTY720 controls disease severity and attenuates sciatic nerve damage in chronic experimental autoimmune neuritis

Background

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an autoimmune-mediated inflammatory disease of the peripheral nervous system characterized by a response directed against certain myelin proteins and for which therapies are limited. Previous studies have suggested a beneficial role of FTY720, a sphingosine 1-phosphate (S1P) receptor agonist, known to deplete lymphocytes from the peripheral blood by sequestering them into lymph nodes, in the treatment of experimental autoimmune neuritis (EAN). Therefore, we investigated whether FTY720 is also beneficial in chronic experimental autoimmune neuritis (c-EAN), a recently developed rat model mimicking human CIDP.

Methods

c-EAN was induced in Lewis rats by immunization with S-palm P0(180–199) peptide. Rats were treated with FTY720 (1 mg/kg) or vehicle intraperitoneally once daily from the onset of clinical signs for 18 days; clinical signs were assessed daily until 60 days post-immunization (dpi). Electrophysiological and histological features were examined at different time points. We also evaluated the serum levels of different pro- and anti-inflammatory cytokines by ELISA or flow cytometry at 18, 40, and 60 dpi.

Results

Our data demonstrate that FTY720 decreased the severity and abolished the chronicity of the disease in c-EAN rats. Therapeutic FTY720 treatment reversed electrophysiological and histological anomalies, suggesting that myelinated fibers were subsequently preserved, it inhibited macrophage and IL-17⁺ cell infiltration in PNS, and it significantly reduced circulating pro-inflammatory cytokines.

Conclusions

FTY720 treatment has beneficial effects on c-EAN, a new animal model mimicking human CIDP. We have shown that FTY720 is an effective immunomodulatory agent, improving the disease course of c-EAN, preserving the myelinated fibers, attenuating the axonal degeneration, and decreasing the number of infiltrated inflammatory cells in peripheral nerves. These data confirm the interest of testing FTY720 or molecules targeting S1P in human peripheral neuropathies.

Electronic supplementary material

The online version of this article (10.1186/s12974-019-1441-4) contains supplementary material, which is available to authorized users.

Conventional and unconventional therapies in typical and atypical chronic inflammatory demyelinating polyneuropathy with different clinical course of progression

Intravenous immunoglobulin (IVIG), corticosteroids and therapeutic plasma exchange (TPE) are evidence-based conventional treatments for chronic inflammatory demyelinating polyneuropathy (CIDP). In many centres, unconventional treatments are frequently used as alternatives. We evaluated the outcome of conventional and unconventional therapies in 31 CIDP patients. Overall response rate with conventional first-line immunotherapies was 77% (20/26), comparable between IVIG and corticosteroids (80% vs 70%). Use of TPE was limited. Treatment response among typical and atypical CIDP were comparable (76 vs 80%). Non-responders were patients with progressive form of typical CIDP and DADS. Majority (21/26, 81%) of patients with persistent neurological deficits received maintenance therapy. Two subgroups of patients frequently treated with maintenance immunosuppressants were those with improving or stable disease following first-line treatment (12, 57%) and those with progressive form of CIDP (2, 10%). Primary indications for immunosuppressant use were corticosteroids-sparing and additional immunosuppression effects. Nine (64%) patients with improving or stable disease given azathioprine were taken off corticosteroids after a median duration of 14 months (range 12-108). Two (14%) eventually achieved cure or clinical remission without treatment. Maintenance IVIg was given to 6 (29%) relapsing CIDP patients; none of achieved cure or remission after similar median duration of treatment. Less potent immunosuppressant drugs (azathioprine, mycophenolate mofetil, and methotrexate) were frequently used, with moderate adverse effect profiles. In resource limited setting, unconventional treatments were commonly used among CIDP patients with different clinical course of progression. In most cases, careful risk-benefit re-assessment is required to justify its further use.