Effective treatment with intravenous immunoglobulins reduces autoreactive T-cell response in patients with CIDP

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.

Molecular, Electrophysiological, and Ultrasonographic Differences in Selected Immune-Mediated Neuropathies with Therapeutic Implications

The spectrum of immune-mediated neuropathies is broad and the different subtypes are still being researched. With the numerous subtypes of immune-mediated neuropathies, establishing the appropriate diagnosis in normal clinical practice is challenging. The treatment of these disorders is also troublesome. The authors have undertaken a literature review of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), Guillain-Barre syndrome (GBS) and multifocal motor neuropathy (MMN). The molecular, electrophysiological and ultrasound features of these autoimmune polyneuropathies are analyzed, highlighting the differences in diagnosis and ultimately treatment. The immune dysfunction can lead to damage to the peripheral nervous system. In practice, it is suspected that these disorders are caused by autoimmunity to proteins located in the node of Ranvier or myelin components of peripheral nerves, although disease-associated autoantibodies have not been identified for all disorders. The electrophysiological presence of conduction blocks is another important factor characterizing separate subgroups of treatment-naive motor neuropathies, including multifocal CIDP (synonyms: multifocal demyelinating neuropathy with persistent conduction block), which differs from multifocal motor neuropathy with conduction block (MMN) in both responses to treatment modalities and electrophysiological features. Ultrasound is a reliable method for diagnosing immune-mediated neuropathies, particularly when alternative diagnostic examinations yield inconclusive results. In overall terms, the management of these disorders includes immunotherapy such as corticosteroids, intravenous immunoglobulin or plasma exchange. Improvements in clinical criteria and the development of more disease-specific immunotherapies should expand the therapeutic possibilities for these debilitating diseases.

Potential therapeutic strategies in chronic inflammatory demyelinating polyradiculoneuropathy

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an autoimmune neuropathy involving peripheral nerve and nerve roots. The pathological hallmark of CIDP is macrophage-induced demyelination. Antibodies against nerve fibers, complement decomposition, abnormalities in plasma and cerebrospinal fluid cytokine profile, and changes of peripheral blood cell proportion were also reported in CIDP patients. These findings in immunopathology provide support for the introduction of potential therapeutic options for the treatment of CIDP. In this review, we systematically listed the potential therapeutic strategies targeting different components of the immune system by comparing the treatment of other autoimmune inflammatory diseases of the nervous system. Several ongoing clinical trials will assess the efficacy and safety of potential CIDP treatments.

Novel Immunological and Therapeutic Insights in Guillain-Barré Syndrome and CIDP

Inflammatory neuropathies are a heterogeneous group of rare diseases of the peripheral nervous system that include acute and chronic diseases, such as Guillain-Barré syndrome (GBS) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). The etiology and pathophysiological mechanisms of inflammatory neuropathies are only partly known, but are considered autoimmune disorders in which an aberrant immune response, including cellular and humoral components, is directed towards components of the peripheral nerve causing demyelination and axonal damage. Therapy of these disorders includes broad-spectrum immunomodulatory and immunosuppressive treatments, such as intravenous immunoglobulin, corticosteroids, or plasma exchange. However, a significant proportion of patients do not respond to any of these therapies, and treatment selection is not optimized according to disease pathophysiology. Therefore, research on disease pathophysiology aiming to reveal clinically and functionally relevant disease mechanisms and the development of new treatment approaches are needed to optimize disease outcomes in CIDP and GBS. This topical review describes immunological progress that may help guide therapeutic strategies in the future in these two disorders.

Correlations between Electrophysiological Parameters, Lymphocyte Distribution and Cytokine Levels in Patients with Chronic Demyelinating Inflammatory Polyneuropathy

The goal of this study was to analyse, in relation to electrophysiological results, the distribution of lymphocyte subpopulations and the level of cytokines in patients with the typical form of chronic demyelinating inflammatory polyneuropathy (CIDP) before immunoglobulin treatment. The study group consisted of 60 patients (52 men, eight women), with a mean age 64.8 ± 11.2, who fulfilled the diagnostic criteria for the typical variant of CIDP, with (23 patients) and without (37 patients) diabetes mellitus. We analysed the results of the neurophysiological tests, and correlated them with the leukocyte subpopulations, and cytokine levels. In CIDP patients, IL-6, IL-2, IL-4 and TNF-α levels were significantly increased compared to the control group. Fifty patients had decreased levels of T CD8+ lymphocytes, and 51 patients had increased levels of CD4+ lymphocytes. An increased CD4+/CD8+ ratio was also found. Negative correlations were observed mainly between compound muscle action potential (CMAP) amplitudes and cytokine levels. The study enabled the conclusion that electrophysiological parameters in CIDP patients are closely related to the autoimmune process, but without any clear differences between patients with and without diabetes mellitus. Correlations found in the study indicated that axonal degeneration might be independent of the demyelinating process and might be caused by direct inflammatory infiltration.

Role of Immunoglobulins in Muscular Dystrophies and Inflammatory Myopathies

Muscular dystrophies and inflammatory myopathies are heterogeneous muscular disorders characterized by progressive muscle weakness and mass loss. Despite the high variability of etiology, inflammation and involvement of both innate and adaptive immune response are shared features. The best understood immune mechanisms involved in these pathologies include complement cascade activation, auto-antibodies directed against muscular proteins or de-novo expressed antigens in myofibers, MHC-I overexpression in myofibers, and lymphocytes-mediated cytotoxicity. Intravenous immunoglobulins (IVIGs) administration could represent a suitable immunomodulator with this respect. Here we focus on mechanisms of action of immunoglobulins in muscular dystrophies and inflammatory myopathies highlighting results of IVIGs from pre-clinical and case reports evidences.

The immune response and aging in chronic inflammatory demyelinating polyradiculoneuropathy

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) consists of various autoimmune subtypes in which the peripheral nervous system (PNS) is attacked. CIDP can follow a relapsing-remitting or progressive course where the resultant demyelination caused by immune cells (e.g., T cells, macrophages) and antibodies can lead to disability in patients. Importantly, the age of CIDP patients has a role in their symptomology and specific variants have been associated with differing ages of onset. Furthermore, older patients have a decreased frequency of functional recovery after CIDP insult. This may be related to perturbations in immune cell populations that could exacerbate the disease with increasing age. In the present review, the immune profile of typical CIDP will be discussed followed by inferences into the potential role of relevant aging immune cell populations. Atypical variants will also be briefly reviewed followed by an examination of the available studies on the immunology underlying them.

Long-term human IgG treatment improves heart and muscle function in a mouse model of Duchenne muscular dystrophy

BACKGROUND

Duchenne muscular dystrophy (DMD) is a progressive muscle-wasting disease caused by mutations in the dystrophin gene, which leads to structural instability of the dystrophin-glycoprotein-complex with subsequent muscle degeneration. In addition, muscle inflammation has been implicated in disease progression and therapeutically addressed with glucocorticosteroids. These have numerous adverse effects. Treatment with human immunoglobulin G (IgG) improved clinical and para-clinical parameters in the early disease phase in the well-established mdx mouse model. The aim of the present study was to confirm the efficacy of IgG in a long-term pre-clinical study in mdx mice.

METHODS

IgG (2 g/kg body weight) or NaCl solution as control was administered monthly over 18 months by intraperitoneal injection in mdx mice beginning at 3 weeks of age. Several clinical outcome measures including endurance, muscle strength, and echocardiography were assessed. After 18 months, the animals were sacrificed, blood was collected for analysis, and muscle samples were obtained for ex vivo muscle contraction tests, quantitative PCR, and histology.

RESULTS

IgG significantly improved the daily voluntary running performance (1.9 m more total daily running distance, P < 0.0001) and slowed the decrease in grip strength by 0.1 mN, (P = 0.018). IgG reduced fatigability of the diaphragm (improved ratio to maximum force by 0.09 ± 0.04, P = 0.044), but specific tetanic force remained unchanged in the ex vivo muscle contraction test. Cardiac function was significantly better after IgG, especially fractional area shortening (P = 0.012). These results were accompanied by a reduction in cardiac fibrosis and the infiltration of T cells (P = 0.0002) and macrophages (P = 0.0027). In addition, treatment with IgG resulted in a significant reduction of the infiltration of T cells (P ≤ 0.036) in the diaphragm, gastrocnemius, quadriceps, and a similar trend in tibialis anterior and macrophages (P ≤ 0.045) in gastrocnemius, quadriceps, tibialis anterior, and a similar trend in the diaphragm, as well as a decrease in myopathic changes as reflected by a reduced central nuclear index in the diaphragm, tibialis anterior, and quadriceps (P ≤ 0.002 in all).

CONCLUSIONS

The present study underscores the importance of an inflammatory contribution to the disease progression of DMD. The data demonstrate the long-term efficacy of IgG in the mdx mouse. IgG is well tolerated by humans and could preferentially complement gene therapy in DMD. The data call for a clinical trial with IgG in DMD.

Autoimmune Peripheral Neuropathies and Contribution of Antiganglioside/Sulphatide Autoantibody Testing

Peripheral immune-mediated polyneuropathies (IMPN) are a diverse group of rare neurological illnesses characterized by nerve damage. Leading morphological features are mostly nerve fibre demyelination or combination of axonal damage and demyelination. There has been remarkable progress in the clinical and electrophysiological categorization of acute (fulminant, life-threatening) and chronic (progressive/remitting-relapsing) immune-mediated neuropathies recently. Besides electrophysiological and morphological makers, autoantibodies against glycolipids or paranodal/nodal molecules have been recommended as candidate markers for IMPN. The progress in testing for autoantibodies (autoAbs) to glycolipids such as gangliosides and sulfatide may have significant implications on the stratification of patients and their treatment response. Thus, this topic was reviewed in a presentation held during the 1st Panhellenic Congress of Autoimmune Diseases, Rheumatology and Clinical Immunology in Portaria, Pelion, Greece. For acute IMPN, often referred to as Guillain-Barré syndrome and its variants, several serological markers including autoAbs to gangliosides and sulphatide have been employed successfully in clinical routine. However, the evolution of serological diagnosis of chronic variants, such as chronic inflammatory demyelinating polyneuropathy or multifocal motor neuropathy, is less satisfactory. Serological diagnostic markers could, therefore, help in the differential diagnosis due to their assumed pathogenic role. Additionally, stratification of patients to improve their response to treatment may be possible. In general, a majority of patients respond well to causal therapy that includes intravenous immunoglobulins and plasmapheresis. As second line therapy options, biologicals (e.g., rituximab) and immunosuppressant or immunomodulatory drugs may be considered when patients do not respond adequately.

Convalescent plasma in Covid-19: Possible mechanisms of action

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible of the coronavirus disease 2019 (COVID-19) pandemic. Therapeutic options including antimalarials, antivirals, and vaccines are under study. Meanwhile the current pandemic has called attention over old therapeutic tools to treat infectious diseases. Convalescent plasma (CP) constitutes the first option in the current situation, since it has been successfully used in other coronaviruses outbreaks. Herein, we discuss the possible mechanisms of action of CP and their repercussion in COVID-19 pathogenesis, including direct neutralization of the virus, control of an overactive immune system (i.e., cytokine storm, Th1/Th17 ratio, complement activation) and immunomodulation of a hypercoagulable state. All these benefits of CP are expected to be better achieved if used in non-critically hospitalized patients, in the hope of reducing morbidity and mortality.

Convalescent plasma in Covid-19: Possible mechanisms of action

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible of the coronavirus disease 2019 (COVID-19) pandemic. Therapeutic options including antimalarials, antivirals, and vaccines are under study. Meanwhile the current pandemic has called attention over old therapeutic tools to treat infectious diseases. Convalescent plasma (CP) constitutes the first option in the current situation, since it has been successfully used in other coronaviruses outbreaks. Herein, we discuss the possible mechanisms of action of CP and their repercussion in COVID-19 pathogenesis, including direct neutralization of the virus, control of an overactive immune system (i.e., cytokine storm, Th1/Th17 ratio, complement activation) and immunomodulation of a hypercoagulable state. All these benefits of CP are expected to be better achieved if used in non-critically hospitalized patients, in the hope of reducing morbidity and mortality.

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Coronavirus disease 19 (COVID-19) is an emerging viral threat with major repercussions for public health.

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There is not specific treatment for COVID-19.

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Convalescent plasma (CP) emerges as the first option of management for hospitalized patients with COVID-19.

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Transference of neutralizing antibodies helps to control COVID-19 infection and modulates inflammatory response.

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Other plasma components may enhance the antiviral and anti-inflammatory properties of CP.

Chronic inflammatory demyelinating polyneuropathy: Plasmapheresis or cyclosporine can be good treatment options in refractory cases

Childhood chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a rare condition, and the optimal treatment strategy is not well established, especially in refractory cases. We analyzed the clinical features and treatment outcomes of 14 cases of childhood CIDP with more than 12 months of follow-up. Of the 14 cases, 10 cases were considered refractory to the conventional first-line treatment. In the monophasic group (n = 6), plasmapheresis resulted in a better treatment response than did IVIG. Monophasic refractory cases (n = 4) were especially responsive to plasmapheresis. In the polyphasic group (n = 8), IVIG and plasmapheresis had comparable effects. Among them six polyphasic patients were refractory to the first-line treatment options and received additional immunosuppressants. Four treatment-refractory polyphasic patients received cyclosporine and achieved successful disease control. With regard to the long-term outcomes, six patients showed minimal symptoms and no relapse within 6 months. Our results suggest that early administration of plasmapheresis in a monophasic course and cyclosporine in a polyphasic course may be effective treatment options for refractory childhood CIDP.

Analysis of anti-ganglioside antibodies by a line immunoassay in patients with chronic-inflammatory demyelinating polyneuropathies (CIDP)

BACKGROUND

Unlike for acute immune-mediated neuropathies (IN), anti-ganglioside autoantibody (aGAAb) testing has been recommended for only a minority of chronic IN yet. Thus, we used a multiplex semi-quantitative line immunoassay (LIA) to search for aGAAb in chronic-inflammatory demyelinating polyneuropathy (CIDP) and its clinical variants.

METHODS

Anti-GAAb to 11 gangliosides and sulfatide (SF) were investigated by LIA in 61 patients with IN (27 typical CIDP, 12 distal-acquired demyelinating polyneuropathy, 6 multifocal-acquired demyelinating sensory/motor polyneuropathy, 10 sensory CIDP, 1 focal CIDP and 5 multifocal-motoric neuropathy), 40 with other neuromuscular disorders (OND) (15 non-immune polyneuropathies, 25 myasthenia gravis), 29 with multiple sclerosis (MS) and 54 healthy controls (HC).

RESULTS

In contrast to IgG, positive anti-GAAB IgM against at least one ganglioside/SF was found in 17/61 (27.9%) IN compared to 2/40 (5%) in OND, 2/29 MS (6.9%) and 4/54 (7.4%) in HC (p=0.001). There was a statistically higher prevalence of anti-sulfatide (aSF) IgM in IN compared to OND (p=0.008). Further, aGM1 IgM was more prevalent in IN compared to OND and HC (p=0.009) as well as GD1b in IN compared to HC (p<0.04). The prevalence of aGM1 IgM in CIDP was lower compared to in multifocal motor neuropathy (MMN) (12% vs. 60%, p=0.027). Patients showing aSF, aGM1 and aGM2 IgM were younger compared to aGAAb negatives (p<0.05). Patients with aSF IgM positivity presented more frequently typical CIDP and MMN phenotypes (p<0.05, respectively).

CONCLUSIONS

The aGAAb LIA revealed an elevated frequency of at least one aGAAb IgM in CIDP/MMN patients. Anti-SF, aGM1 and aGM2 IgM were associated with younger age and anti-SF with IN phenotypes.

Diagnostic insights into chronic-inflammatory demyelinating polyneuropathies

Chronic inflammatory demyelinating polyneuropathy (CIDP) is a rare immune-mediated neuropathy with demyelination of nerve fibers as leading morphological feature. The course of disease can be chronic progressive or remitting relapsing. Whereas for acute immune-mediated neuropathies several serological markers have been identified and used successfully in clinical routine, the serological diagnosis of chronic variants such as CIDP has not yet been evolved satisfactory. The typical CIDP and its various atypical variants are characterized by a certain diversity of clinical phenotype and response to treatment. Thus, diagnostic markers could aid in the differential diagnosis of CIDP variants and stratification of patients for a better treatment response. Most patients respond well to a causal therapy including steroids, intravenous immunoglobulins and plasmapheresis. Apart from electrophysiological and morphological markers, several autoantibodies have been reported as candidate markers for CIDP, including antibodies against glycolipids or paranodal/nodal molecules. The present review provides a summary of the progress in autoantibody testing in CIDP and its possible implication on the stratification of the CIDP variants and treatment response.

Immune Abnormalities in Autism Spectrum Disorder-Could They Hold Promise for Causative Treatment?

Autism spectrum disorders (ASD) are characterized by impairments in language and communication development, social behavior, and the occurrence of stereotypic patterns of behavior and interests. Despite substantial speculation about causes of ASD, its exact etiology remains unknown. Recent studies highlight a link between immune dysfunction and behavioral traits. Various immune anomalies, including humoral and cellular immunity along with abnormalities at the molecular level, have been reported. There is evidence of altered immune function both in cerebrospinal fluid and peripheral blood. Several studies hypothesize a role for neuroinflammation in ASD and are supported by brain tissue and cerebrospinal fluid analysis, as well as evidence of microglial activation. It has been shown that immune abnormalities occur in a substantial number of individuals with ASD. Identifying subgroups with immune system dysregulation and linking specific cellular immunophenotypes to different symptoms would be key to defining a group of patients with immune abnormalities as a major etiology underlying behavioral symptoms. These determinations would provide the opportunity to investigate causative treatments for a defined patient group that may specifically benefit from such an approach. This review summarizes recent insights into immune system dysfunction in individuals with ASD and discusses the potential implications for future therapies.

Trapped in the epineurium: early entry into the endoneurium is restricted to neuritogenic T cells in experimental autoimmune neuritis

Background

Autoimmune polyneuropathies are acquired inflammatory disorders of the peripheral nervous system (PNS) characterized by inflammation, demyelination, and axonal degeneration. Although the pathogenesis has not been fully elucidated, T cells recognizing self-antigens are believed to initiate inflammation in a subgroup of patients. However, the route and time of T cell entry into the PNS have not yet been described in detail. In this study, we analyzed both kinetics as well as localization of retrovirally transfected green fluorescent protein (GFP)-expressing neuritogenic T lymphocytes in experimental autoimmune neuritis (EAN).

Methods

T lymphocytes obtained from rats following EAN induction by immunization with peripheral nerve protein peptide P2_55–78 were retrovirally engineered to express GFP. Non-specific T cells were negatively selected by in vitro restimulation, whereas GFP-expressing neuritogenic T cells (reactive to P2_55–78) were adoptively transferred into healthy rats (AT-EAN). Antigen-specific T cell tracking and localization was performed by flow cytometry and immunohistochemistry during the course of disease.

Results

After induction of autoimmune neuritis, P2-reactive T cells were detectable in the liver, spleen, lymph nodes, lung, peripheral blood, and the sciatic nerves with distinct kinetics. A significant number of GFP⁺ T cells appeared early in the lung with a peak at day four. In the peripheral nerves within the first days, GFP-negative T cells rapidly accumulated and exceeded the number of GFP-expressing cells, but did not enter the endoneurium. Very early after adoptive transfer, T cells are found in proximity to peripheral nerves and in the epineurium. However, only GFP-expressing neuritogenic T cells are able to enter the endoneurium from day five after transfer.

Conclusions

Our findings suggest that neuritogenic T cells invade the PNS early in the course of disease. However, neuritogenic T cells cross the blood-nerve barrier with a certain delay without preference to dorsal roots. Further understanding of the pathophysiological role of autoagressive T cells may help to improve therapeutic strategies in immune-mediated neuropathies.

Neurofascin and Compact Myelin Antigen-Specific T Cell Response Pattern in Chronic Inflammatory Demyelinating Polyneuropathy Subtypes

Objective

The objective of this study is to investigate whether chronic inflammatory demyelinating polyneuropathy (CIDP) and its subtypes differ in their type 1 T-helper (TH1) cell response against nodal/paranodal neurofascin (NF186, NF155) as well as myelin protein zero (P0 180–199) and myelin basic protein (MBP 82–100).

Methods

Interferon-gamma (IFN-γ) enzyme-linked immunospot assay was used to detect antigen-specific T cell responses in 48 patients suffering typical CIDP (n = 18), distal acquired demyelinating polyneuropathy (n = 8), multifocal acquired demyelinating sensory and motor polyneuropathy (MADSAM; n = 9), and sensory CIDP (n = 13) compared to other non-immune polyneuropathy (ON; n = 19) and healthy controls (n = 9).

Results

Compared to controls, MADSAM and sensory CIDP patients showed broadest IFN-γ T cell responses to all four antigens. Positive IFN-γ responses against two or more antigens were highly predictive for CIDP (positive predictive value = 0.95) and were found in 77% of CIDP patients. Patients with limited antigen-specific response were females, more severely affected with neuropathic pain and proximal paresis. The area under the receiver operating characteristics curve (AUC) of NF186 in MADSAM was 0.94 [95% confidential interval (CI) 0.82–1.00] compared to ON. For sensory CIDP, AUC of P0 180–199 was 0.94 (95% CI 0.86–1.00) and for MBP 82–100 0.95 (95% CI 0.88–1.00) compared to ON.

Conclusion

Cell-mediated immune responses to (para)nodal and myelin-derived antigens are common in CIDP. TH1 response against NF186 may be used as a biomarker for MADSAM and TH1 responses against P0 180–199 and MBP 82–100 as biomarkers for sensory CIDP. Larger multicenter studies study are warranted in order to establish these immunological markers as a diagnostic tools.

Neurofascin (NF)155- and NF186-Specific T Cell Response in a Patient Developing a Central Pontocerebellar Demyelination after 10 Years of CIDP

Background

Information and pathobiological understanding about central demyelinating manifestation in patients, who primarily suffer from chronic inflammatory demyelinating polyneuropathy (CIDP), are scarce.

Methods

IFN-γ-response as well as antibodies against the (para)nodal antigens neurofascin (NF)155 and NF 186 had been tested by Elispot assay and ELISA before clinical manifestation and at follow-up.

Case description and results

The patient described here developed a subacute brainstem syndrome more than 10 years after diagnosis of CIDP under low-dose maintenance treatment of intravenous immunoglobulins (IVIG). MRI revealed enhancing right-sided pontocerebellar lesion. CSF examination showed mild pleocytosis and elevated protein, and negative oligoclonal bands. Further diagnostics exclude differential diagnoses such as tuberculoma, sarcoidosis, or metastasis. Specific IFN-γ response against NF155 and NF186 as measured by Elispot assay was elevated before clinical manifestation. NF155 and NF186 antibodies were negative. Escalation of IVIG treatment at 2 g/kg BW followed by 1.4 g/kg BW led to clinical remission albeit to a new asymptomatic central lesion. Follow-up NF155 and NF186-Elispot turned negative.

Conclusion

The case reported here with a delayed central manifestation after an initially typical CIDP and NF155 and NF186 T cell responses does not resemble described cases of combined central and peripheral demyelination but may reflect a novel subtype within the great clinical heterogeneity of CIDP.

Differences in peripheral myelin antigen-specific T cell responses and T memory subsets in atypical versus typical CIDP

Background

Chronic inflammatory demyelinating polyneuropathy (CIDP) is presented by a large heterogeneity of clinical phenotypes. Around 50% of patients suffer from typical CIDP and show better therapy response than atypical variants. The goal of our study was to search for cellular immunological differences in typical versus atypical CIDP in comparison to controls.

Methods

We evaluated 26 (9 typical, 17 atypical) patients with mainly active-unstable CIDP using clinical and immunological examinations (enzyme-linked immunospot assay ELISPOT, fluorescence-activated cell sorting FACS) in comparison to 28 healthy, age-matched controls (HC). Typical or atypical CIDP measurements were compared with HC using Kruskal-Wallis test.

Results

Atypical CIDP patients showed increased frequencies of T cell subsets, especially CD4+ effector memory T cells (TEM) and CD4+ central memory T cells (TCM) as well as a tendency of higher T cell responses against the peripheral myelin antigens of PMP-22, P2, P0 and MBP peptides compared to typical CIDP. Searching for novel auto-antigens, we found that T cell responses against P0 180-199 as well as MBP 82-100 were significantly elevated in atypical CIDP patients vs. HC.

Conclusions

Our results indicate differences in underlying T cell responses between atypical and typical CIDP characterized by a higher peripheral myelin antigen-specific T cell responses as well as a specific altered CD4+ memory compartment in atypical CIDP. Larger multi-center studies study are warranted in order to characterize T cell auto-reactivity in atypical CIDP subgroups in order to establish immunological markers as a diagnostic tool.

Immunomodulation of inflammatory leukocyte markers during intravenous immunoglobulin treatment associated with clinical efficacy in chronic inflammatory demyelinating polyradiculoneuropathy

OBJECTIVE

The objective of the study was to profile leukocyte markers modulated during intravenous immunoglobulin (IVIg) treatment, and to identify markers and immune pathways associated with clinical efficacy of IVIg for chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) with potential for monitoring treatment efficacy.

METHODS

Response to IVIg treatment in newly diagnosed IVIg-naïve and established IVIg-experienced patients was assessed by changes in expression of inflammatory leukocyte markers by flow cytometry. The adjusted INCAT disability and Medical Research Council sum scores defined clinical response.

RESULTS

Intravenous immunoglobulin modulated immunopathogenic pathways associated with inflammatory disease in CIDP. Leukocyte markers of clinical efficacy included reduced CD185⁺ follicular helper T cells, increased regulatory markers (CD23 and CD72) on B cells, and reduction in the circulating inflammatory CD16⁺ myeloid dendritic cell (mDC) population and concomitant increase in CD62L and CD195 defining a less inflammatory lymphoid homing mDC phenotype. A decline in inflammatory CD16⁺ dendritic cells was associated with clinical improvement or stability, and correlated with magnitude of improvement in neurological assessment scores, but did not predict relapse. IVIg also induced a nonspecific improvement in regulatory and reduced inflammatory markers not associated with clinical response.

CONCLUSIONS

Clinically effective IVIg modulated inflammatory and regulatory pathways associated with ongoing control or resolution of CIDP disease. Some of these markers have potential for monitoring outcome.

Stroke induces specific alteration of T memory compartment controlling auto-reactive CNS antigen-specific T cell responses

Whether and when auto-reactivity after stroke occurs is still a matter of debate. By using overlapping 15mer peptide pools consisting of myelin basic protein (MBP) and myelin oligodendrocyte glycoprotein (MOG) we show increased frequencies of immunodominant MOG- and MBP T cell responses in acute ischemic stroke which were associated with reduced frequencies of naïve T cells as well as CD8+ TEMRA cells. Auto-reactive CNS antigen-specific T cells responses as well as alterations of T cell subpopulations normalized in long-term follow up after stroke. Our findings suggest that stroke-induced immunodepression might function as an adaptive mechanism in order to inhibit harmful and long-lasting CNS antigen-specific immune responses.

Transcriptome Analysis of Peripheral Blood in Chronic Inflammatory Demyelinating Polyradiculoneuropathy Patients Identifies TNFR1 and TLR Pathways in the IVIg Response

We have studied the response to intravenous immunoglobulins (IVIg) by a transcriptomic approach in 11 chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) patients (CIDP duration = 6 [0.83-6.5] years). RNA was extracted from cells in whole blood collected before and 3 weeks after IVIg treatment, and hybridized on Illumina chips. After RNA quality controls, gene expression was analyzed using statistical tests fitted for microarrays (R software, limma package), and a pathway analysis was performed using DAVID software. We identified 52 genes with expression that varied significantly after IVIg (fold change [FC] > 1.2, P < 0.001, false discovery rate [FDR] <0.05). Among these 52 genes, 7 were related to immunity, 3 were related to the tumor necrosis factor (TNF)-α receptor 1 (TNFR1) pathway (inhibitor of caspase-activated DNase (ICAD): FC = 1.8, P = 1.7E-7, FDR = 0.004; p21 protein-activated kinase 2 [PAK2]: FC = 1.66, P = 2.6E-5, FDR = 0.03; TNF-α-induced protein 8-like protein 1 [TNFAIP8L1]: P = 1.00E-05, FDR = 0.026), and 2 were related to Toll-like receptors (TLRs), especially TLRs 7 and 9, and were implicated in autoimmunity. These genes were UNC93B1 (FC = 1.6, P = 2E-5, FDR = 0.03), which transports TLRs 7 and 9 to the endolysosomes, and RNF216 (FC = 1.5, P = 1E-05, FDR = 0.03), which promotes TLR 9 degradation. Pathway analysis showed that the TNFR1 pathway was significantly lessened by IVIg (enrichment score = 24, Fischer exact test = 0.003). TNF-α gene expression was higher in responder patients than in nonresponders; however, it decreased after IVIg in responders (P = 0.04), but remained stable in nonresponders. Our data suggest the actions of IVIg on the TNFR1 pathway and an original mechanism involving innate immunity through TLRs in CIDP pathophysiology and the response to IVIg. We conclude that responder patients have stronger inflammatory activity that is lessened by IVIg.

Neuroinflammation in the peripheral nerve: Cause, modulator, or bystander in peripheral neuropathies?

The role of innate and adaptive inflammation as a primary driver or modifier of neuropathy in premorbidly normal nerves, and as a critical player in amplifying neuropathies of other known causes (e.g., genetic, metabolic) is incompletely understood and under-researched, despite unmet clinical need. Also, cellular and humoral components of the adaptive and innate immune system are substantial disease modifying agents in the context of neuropathies and, at least in some neuropathies, there is an identified tight interrelationship between both compartments of the immune system. Additionally, the quadruple relationship between Schwann cell, axon, macrophage, and endoneurial fibroblast, with their diverse membrane bound and soluble signalling systems, forms a distinct focus for investigation in nerve diseases with inflammation secondary to Schwann cell mutations and possibly others. Identification of key immunological effector pathways that amplify neuropathic features and associated clinical symptomatology including pain should lead to realistic and timely possibilities for translatable therapeutic interventions using existing immunomodulators, alongside the development of novel therapeutic targets.

Intravenous immunoglobulin in the treatment of neurologic disorders

Intravenous immunoglobulins (IVIGs) are often used in the treatment of autoimmune disorders and immunodeficiencies, and it has been estimated that neurologic indications can account for up to 43% of IVIG used in clinical practice. In neurologic clinical practice, IVIG is used for acute therapy of newly diagnosed autoimmune disorders or exacerbations of pre-existing conditions, or as long-term maintenance treatment for chronic disorders. IVIG exerts its effects on humoral and cell-based immunity through multiple pathways, without a single dominant mechanism. Clinical use of IVIG has been supported by guidelines from American Academy of Neurology and European Federation of Neurologic Societies. IVIG is generally recommended for the treatment of Guillain-Barre syndrome and chronic inflammatory demyelinating polyneuropathy in adults, multifocal motor neuropathy and myasthenia gravis, and should be considered as a treatment option for dermatomyositis in adults and Lambert-Eaton myasthenic syndrome. Additional potential indications include stiff person syndrome, multiple sclerosis during pregnancy or while breastfeeding, refractory autoimmune epilepsy, and paraneoplastic disorders. Clinical use of IVIG is mostly safe but few adverse effects may still occur with potentially severe complications, including aseptic meningitis and thromboembolism. In addition to intravenous route (IVIG), subcutaneous immunoglobulins have been used as an alternative treatment option, especially in patients with limited intravenous access. Treatment with IVIG is effective in various autoimmune diseases, but its broader use is constrained by limited supply. This review evaluates the use of immunoglobulins in treatment of neurologic diseases.