Advances in understanding and treatment of immune-mediated disorders of the peripheral nervous system

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.

Role of prazosin in patients with Guillain-Barré syndrome with sympathetic overactivity: A cohort study

INTRODUCTION/AIMS

In Guillain-Barré syndrome (GBS), patients with dysautonomia demonstrate sympathetic overactivity (SO). This study assessed the role of prazosin (α1-blocker) in the management of SO.

METHODS

This cohort study was conducted from January 2022 to September 2023. Thirty-two GBS patients with SO received prazosin (2.5-10 mg three times a day) (prazosin group). For comparison, we included historical controls that included 33 GBS patients having SO with similar baseline characteristics, including median age and disability, who did not receive prazosin, from a GBS registry of patients admitted during February 2018-December 2021. The primary endpoint was days to resolution of SO. Secondary endpoints were daily fluctuations in the systolic (SBP) and diastolic blood pressure (DBP), duration of hospital stay, in-hospital mortality, and disability at 3 months.

RESULTS

The median ages of both the treatment and the control groups were 36 (IQR 25-49) years and 43 (66.2%) were males. The demographic and clinical parameters were comparable. Prazosin resulted in significantly earlier normalization of SO compared to the control group (median 15 vs. 20 days; p = .01). The mean fluctuations in the SBP and DBP at 15 days were significantly lower in the prazosin group. However, the duration of hospital stay and good recovery at 3 months were comparable. Three patients developed hypotension, while two patients died (ventilator-associated pneumonia) in the prazosin group.

DISCUSSION

This study provides new evidence supporting the role of prazosin in SO, and needs randomized trials to confirm our findings.

P2X7 receptor antagonists modulate experimental autoimmune neuritis via regulation of NLRP3 inflammasome activation and Th17 and Th1 cell differentiation

BACKGROUND

Guillain-Barré syndrome (GBS), a post-infectious, immune-mediated, acute demyelinating disease of the peripheral nerves and nerve roots, represents the most prevalent and severe acute paralyzing neuropathy. Purinergic P2X7 receptors (P2X7R) play a crucial role in central nervous system inflammation. However, little is known about their role in the immune-inflammatory response within the peripheral nervous system.

METHODS

Initially, we assessed the expression of purinergic P2X7R in the peripheral blood of patients with GBS using flow cytometry and qRT-PCR. Next, we explored the expression of P2 X7R in CD4+ T cells, CD8+ T cells, and macrophages within the sciatic nerves and spleens of rats using immunofluorescence labeling and flow cytometry. The P2X7R antagonist brilliant blue G (BBG) was employed to examine its therapeutic impact on rats with experimental autoimmune neuritis (EAN) induced by immunization with the P0180 - 199 peptide. We analyzed CD4+ T cell differentiation in splenic mononuclear cells using flow cytometry, assessed Th17 cell differentiation in the sciatic nerve through immunofluorescence staining, and examined the expression of pro-inflammatory cytokine mRNA using RT-PCR. Additionally, we performed protein blotting to assess the expression of P2X7R and NLRP3-related inflammatory proteins within the sciatic nerve. Lastly, we utilized flow cytometry and immunofluorescence labeling to examine the expression of NLRP3 on CD4+ T cells in rats with EAN.

RESULTS

P2X7R expression was elevated not only in the peripheral blood of patients with GBS but also in rats with EAN. In rats with EAN, inhibiting P2X7R with BBG alleviated neurological symptoms, reduced demyelination, decreased inflammatory cell infiltration of the peripheral nerves, and improved nerve conduction. BBG also limited the production of pro-inflammatory molecules, down-regulated the expression of P2X7R and NLRP3, and suppressed the differentiation of Th1 and Th17 cells, thus protecting against EAN. These effects collectively contribute to modifying the inflammatory environment and enhancing outcomes in EAN rats.

CONCLUSIONS

Suppression of P2X7R relieved EAN manifestation by regulating CD4+ T cell differentiation and NLRP3 inflammasome activation. This finding underscores the potential significance of P2X7R as a target for anti-inflammatory treatments, advancing research and management of GBS.

Lumican, a Multifunctional Cell Instructive Biomarker Proteoglycan Has Novel Roles as a Marker of the Hypercoagulative State of Long Covid Disease

This study has reviewed the many roles of lumican as a biomarker of tissue pathology in health and disease. Lumican is a structure regulatory proteoglycan of collagen-rich tissues, with cell instructive properties through interactions with a number of cell surface receptors in tissue repair, thereby regulating cell proliferation, differentiation, inflammation and the innate and humoral immune systems to combat infection. The exponential increase in publications in the last decade dealing with lumican testify to its role as a pleiotropic biomarker regulatory protein. Recent findings show lumican has novel roles as a biomarker of the hypercoagulative state that occurs in SARS CoV-2 infections; thus, it may also prove useful in the delineation of the complex tissue changes that characterize COVID-19 disease. Lumican may be useful as a prognostic and diagnostic biomarker of long COVID disease and its sequelae.

Current status of Guillain-Barré syndrome (GBS) in China: a 10-year comprehensive overview

Guillain-Barré syndrome (GBS) is an acute inflammatory polyradiculoneuropathy; a disease involving the peripheral nervous system which is the most common cause of acute flaccid paralysis worldwide. So far, it is still lack of a comprehensive overview and understanding of the national epidemiological, clinical characteristics, and the risk factors of GBS in China, as well as differences between China and other countries and regions in these respects. With the global outbreak of the coronavirus disease 2019 (COVID-19), an epidemiological or phenotypic association between severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection and GBS has attracted great attention. In this review, we outlined the current clinical data of GBS in China by retrieving literature, extracting and synthesizing the data of GBS in China from 2010 to 2021. Besides, we compared the characteristics of epidemiology, preceding events and clinical profiles of GBS between China and other countries and regions. Furthermore, in addition to conventional intravenous immunoglobulin (IVIG) and plasma exchange (PE) therapy, the potential therapeutic effects with novel medications in GBS, such as complement inhibitors, etc., have become the research focus in treatments. We found that epidemiological and clinical findings of GBS in China are approximately consistent with those in the International GBS Outcome Study (IGOS) cohort. We provided an overall picture of the present clinical status of GBS in China and summarized the global research progress of GBS, aiming to further understand the characteristics of GBS and improve the future work of GBS worldwide, especially in countries with the middle and low incomes.

Immune-Mediated Neuropathies: Pathophysiology and Management

Dysfunction of the immune system can result in damage of the peripheral nervous system. The immunological mechanisms, which include macrophage infiltration, inflammation and proliferation of Schwann cells, result in variable degrees of demyelination and axonal degeneration. Aetiology is diverse and, in some cases, may be precipitated by infection. Various animal models have contributed and helped to elucidate the pathophysiological mechanisms in acute and chronic inflammatory polyradiculoneuropathies (Guillain-Barre Syndrome and chronic inflammatory demyelinating polyradiculoneuropathy, respectively). The presence of specific anti-glycoconjugate antibodies indicates an underlying process of molecular mimicry and sometimes assists in the classification of these disorders, which often merely supports the clinical diagnosis. Now, the electrophysiological presence of conduction blocks is another important factor in characterizing another subgroup of treatable motor neuropathies (multifocal motor neuropathy with conduction block), which is distinct from Lewis-Sumner syndrome (multifocal acquired demyelinating sensory and motor neuropathy) in its response to treatment modalities as well as electrophysiological features. Furthermore, paraneoplastic neuropathies are also immune-mediated and are the result of an immune reaction to tumour cells that express onconeural antigens and mimic molecules expressed on the surface of neurons. The detection of specific paraneoplastic antibodies often assists the clinician in the investigation of an underlying, sometimes specific, malignancy. This review aims to discuss the immunological and pathophysiological mechanisms that are thought to be crucial in the aetiology of dysimmune neuropathies as well as their individual electrophysiological characteristics, their laboratory features and existing treatment options. Here, we aim to present a balance of discussion from these diverse angles that may be helpful in categorizing disease and establishing prognosis.

Current and Emerging Pharmacotherapeutic Interventions for the Treatment of Peripheral Nerve Disorders

Peripheral nerve disorders are caused by a range of different aetiologies. The range of causes include metabolic conditions such as diabetes, obesity and chronic kidney disease. Diabetic neuropathy may be associated with severe weakness and the loss of sensation, leading to gangrene and amputation in advanced cases. Recent studies have indicated a high prevalence of neuropathy in patients with chronic kidney disease, also known as uraemic neuropathy. Immune-mediated neuropathies including Guillain-Barré syndrome and chronic inflammatory demyelinating polyradiculoneuropathy may cause significant physical disability. As survival rates continue to improve in cancer, the prevalence of treatment complications, such as chemotherapy-induced peripheral neuropathy, has also increased in treated patients and survivors. Notably, peripheral neuropathy associated with these conditions may be chronic and long-lasting, drastically affecting the quality of life of affected individuals, and leading to a large socioeconomic burden. This review article explores some of the major emerging clinical and experimental therapeutic agents that have been investigated for the treatment of peripheral neuropathy due to metabolic, toxic and immune aetiologies.

Assessment of Expression of SOCS Genes in Acquired Immune-Mediated Polyneuropathies

Acquired immune-mediated polyneuropathies are classified to some subtypes among them are acute and chronic inflammatory demyelinating polyradiculoneuropathies (AIDP and CIDP). These two conditions share some common signs and underlying mechanisms. Based on the roles of Suppressor of cytokine signaling (SOCS) genes in the modulation of immune system reactions, these genes might be involved in the pathogenesis of these conditions. We evaluated expression of SOCS1-3 and SOCS5 genes in the leukocytes of 32 cases of CIDP, 19 cases of AIDP and 40 age- and sex-matched controls using real time PCR method. The Bayesian regression model was used to estimate differences in mean values of genes expressions between cases and control group. Expression levels of SOCS1 and SOCS2 were significantly lower in male patients compared with controls. This sex-specific pattern was also observed for SOCS3 down-regulation. Based on the area under curve values in Receiver Operating Characteristics (ROC) curve, diagnostic powers of SOCS1, SOCS2, SOCS3 and SOCS5 genes in the mentioned disorder were 0.61, 0.73, 0.68 and 0.58, respectively. Expression of none of genes was correlated with age of enrolled cases. The current study shows evidences for participation of SOCS genes in the pathophysiology of acquired immune-mediated polyneuropathies.

Associations of Small Fiber Neuropathy with Geriatric Nutritional Risk Index and Arterial Stiffness in Hemodialysis

BACKGROUND

Peripheral neuropathy is a common neurological complication in uremic patients, and quantitative sensory testing (QST) is effective for diagnosis of small fiber neuropathy. Malnutrition and arterial stiffness are prevalent in patients undergoing hemodialysis (HD). The associations of small fiber neuropathy with nutritional status and arterial stiffness remain uncertain in maintenance HD patients.

METHODS

A total of 152 HD patients were included. Geriatric nutritional risk index (GNRI), an indicator of nutritional status, was calculated by serum albumin and actual and ideal body weight. Arterial stiffness was defined as brachial-ankle pulse wave velocity (baPWV) > 1400 cm/s. Small fiber neuropathy was assessed by an abnormal QST threshold of cold and warm sensation in patients' hands or feet. Multivariate forward logistic regression analysis was performed to examine the associations among abnormal QST threshold, GNRI, and arterial stiffness.

RESULTS

baPWV and prevalence of abnormal QST threshold were significantly higher in diabetic patients. Multivariate logistic analyses revealed that older age (OR, 1.081; 95% CI, 1.026-1.139, p = 0.003) and male gender (OR, 4.450; 95% CI, 1.250-15.836, p = 0.021) were associated with abnormal warm threshold of hands. Furthermore, diabetes (OR, 3.966; 95% CI, 1.351-11.819, p = 0.012) and lower GNRI (per 1 unit increase, OR, 0.935, 95% CI, 0.887-0.985, p = 0.012) were associated with abnormal cold threshold of feet. Arterial stiffness (OR, 5.479, 95% CI, 1.132-22.870, p = 0.020) and higher calcium-phosphorus product (OR, 1.071, 95% CI, 1.013-1.132, p = 0.015) were associated with abnormal warm threshold of feet.

CONCLUSIONS

Lower GNRI and arterial stiffness were significantly associated with small fiber neuropathy in patients undergoing HD. Malnutrition risk and vascular factors might play important roles in small fiber neuropathy among patients undergoing HD.

Elevated cerebrospinal fluid levels of beta-2-microglobulin in patients with Guillain-Barré syndrome and their correlations with clinical features

BACKGROUNDS

Beta-2-microglobulin (β2-MG) levels vary in many infectious and autoimmune diseases. We investigated plasma and cerebrospinal fluid (CSF) β2-MG levels in patients with Guillain-Barré syndrome (GBS) and their correlations with clinical parameters.

METHODS

CSF samples from 50 patients with GBS including 19 acute inflammatory demyelinating polyneuropathy (AIDP), 6 acute motor axonal neuropathy (AMAN), 10 acute motor-sensory axonal neuropathy (AMSAN), 7 Miller-Fisher syndrome (MFS), and 8 unclassified patients were collected. Moreover, 23 CSF samples from patients with non-inflammatory neurological disorders (NIND) as controls were collected. Plasma samples from 42 enrolled patients and 29 healthy individuals were also collected. The β2-MG levels were measured by immunoturbidimetry on automatic biochemical analyser. Besides, clinical data were extracted from electronic patient documentation system.

RESULTS

CSF levels of β2-MG, lactate dehydrogenase (LDH), and lactate were significantly increased in patients with GBS (p = 0.004, p = 0.041, p = 0.040, respectively), particularly in patients with AIDP (p < 0.001, p = 0.001, p = 0.015, respectively), whereas no statistically significant difference was found in plasma levels of β2-MG. Furthermore, CSF levels of β2-MG were positively correlated with Hughes functional score (r = 0.493, p = 0.032), LDH (r = 0.796, p < 0.001), and lactate (r = 0.481, p = 0.037) but not with protein (r = - 0.090, p = 0.713) in AIDP patients.

CONCLUSIONS

CSF β2-MG levels may help identify AIDP and indicate clinical severity. CSF LDH and lactate levels correlate with CSF β2-MG levels; interaction among these biomarkers would need further investigation.

Masquerading Guillain-Barré syndrome: uncommon, in-hospital presentation of Miller-Fisher syndrome shadowed by secondary diseases

Presentation of severe pain syndromes prior to onset of motor weakness is an uncommon but documented finding in patients with Guillain-Barré syndrome (GBS). Sciatica in GBS is a difficult diagnosis when patients present with acute radiculopathy caused by herniated disc or spondylolysis. A middle-aged woman was admitted for severe low back pain, symptomatic hyponatraemia, vomiting and constipation. On further investigation, she was diagnosed with radiculopathy, and appropriate treatment was initiated. Brief symptomatic improvement was followed by new-onset weakness in lower limbs, which progressed to involve upper limbs and right extraocular muscles. With progressive, ascending, new-onset motor and sensory deficits and laboratory evidence of demyelination by Nerve Conduction Study, a diagnosis of variant GBS was made. She was treated with intravenous immunoglobulin 2 g/kg over 5 days. The presentation of severe low back pain that was masking an existing aetiology and possible dysautonomia and the unilateral right extraocular muscles instead of bilateral make our case unique and rare.

Th17 cells and their cytokines serve as potential therapeutic target in experimental autoimmune neuritis

BACKGROUND

Accumulating evidence has pointed that T helper 17 cells and their cytokines are pathogenic in Guillain-Barré syndrome (GBS). However, little is known concerning the IL-17 expression change trend during the whole course of disease, and whether drugs specially targeting Th17 cells or their cytokines have potential effects on experimental autoimmune neuritis (EAN) is uncertain.

METHODS

We explored the IL-17 and receptor-related orphan receptor-gamma-t (RORγt) expression change trends in EAN rats to identify the stage of effect of Th17 pathway in EAN, and further, we investigated the effect of RORγt inhibitors by assessing clinical score, histological staining, and IL-17 and RORγt expression change trends in serum and tissues.

RESULTS

The expression level of IL-17 and RORγt in serum and tissues increased with the progression of the disease in the EAN group and decreased after the disease reaching its peak. RORγt-IN-1 treatment strikingly reduced the neurological deficits by ameliorating inflammatory cell infiltration, deceased the serum IL-17 and RORγt levels, and further downregulated the expression of IL-17 and RORγt mRNA in spleen, lymphnodes, and sciatic nerve.

CONCLUSIONS

Th17 cells and their cytokines are closely associated with the onset of GBS and the novel RORγt inhibitors may be prospective strategies in treating GBS.

Elimination of activating Fcγ receptors in spontaneous autoimmune peripheral polyneuropathy model protects from neuropathic disease

Spontaneous autoimmune peripheral polyneuropathy (SAPP) is a reproducible mouse model of chronic inflammatory peripheral neuropathy in female non-obese diabetic mice deficient in co-stimulatory molecule, B7-2 (also known as CD86). There is evidence that SAPP is an interferon-γ, CD4+ T-cell-mediated disorder, with autoreactive T-cells and autoantibodies directed against myelin protein zero involved in its immunopathogenesis. Precise mechanisms leading to peripheral nerve system inflammation and nerve injury including demyelination in this model are not well defined. We examined the role of activating Fc-gamma receptors (FcγRs) by genetically ablating Fcγ-common chain (Fcer1g) shared by all activating FcγRs in the pathogenesis of this model. We have generated B7-2/ Fcer1g-double null animals for these studies and found that the neuropathic disease is substantially ameliorated in these animals as assessed by behavior, electrophysiology, immunocytochemistry, and morphometry. Our current studies focused on characterizing systemic and endoneurial inflammation in B7-2-null and B7-2/ Fcer1g-double nulls. We found that accumulation of endoneurial inflammatory cells was significantly attenuated in B7-2/ Fcer1g-double nulls compared to B7-2-single nulls. Whereas, systemically the frequency of CD4+ regulatory T cells and expression of immunosuppressive cytokine, IL-10, were significantly enhanced in B7-2/ Fcer1g-double nulls. Overall, these findings suggest that elimination of activating FcγRs modulate nerve injury by altering endoneurial and systemic inflammation. These observations raise the possibility of targeting activating FcγRs as a treatment strategy in acquired inflammatory demyelinating neuropathies.

Incidence, Risk Factors, and Outcome of Immune-Mediated Neuropathies (IMNs) following Haploidentical Hematopoietic Stem Cell Transplantation

Immune-mediated neuropathies (IMNs) following hematopoietic stem cell transplantation have been described recently, which, excluding Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathy, may present with atypical patterns. This retrospective, nested, case-control study reviewed data from 3858 patients who received haploidentical hematopoietic stem cell transplantation (haplo-HSCT) during the past 10 years at a single center, and 40 patients (1.04%) with IMN following haplo-HSCT were identified. Chronic graft-versus-host disease (cGVHD) (P = .043) and cytomegalovirus (CMV) viremia (P = .035) were recognized as independent risk factors for the development of IMN after haplo-HSCT. There were no significant differences in overall survival (P = .619), disease-free survival (P = .609), nonrelapse mortality (P = .87), or the incidence of relapse (P = .583) between patients with and without IMN after haplo-HSCT. However, patients with post-transplant IMN were at higher risk of developing cGVHD (P = .012) than patients who did not develop IMN. Twenty-four of the 40 patients with IMN (60%) attained neurologic improvement after treatments including vitamins B₁ and B₁₂ and/or immunomodulatory agents. However, 19 (47.5%) patients still had persistent motor/sensory deficits despite receiving timely treatment. More studies are needed to help develop standardized diagnostic and therapeutic strategies for patients with post-transplant IMN.

Natural Diterpenoid Oridonin Ameliorates Experimental Autoimmune Neuritis by Promoting Anti-inflammatory Macrophages Through Blocking Notch Pathway

The diterpenoid compound, Oridonin, extracted from the Chinese herb, Rabdosia rubescens, possesses multiple biological activities and properties. Oridonin exhibited efficient anti-inflammatory activity by inducing a switch in macrophage polarization to the anti-inflammatory phenotype through inhibition of the Notch pathway in our in vitro study; therefore, its potential therapeutic effects were further investigated in the animal model of human Guillain-Barré syndrome (GBS) and other polyneuropathies - experimental autoimmune neuritis (EAN). Either preventive or therapeutic treatments with Oridonin greatly attenuated disease peak severity, suppressed paraparesis, shortened disease duration, and even delayed EAN onset. Progression of neuropathic pain, demyelination, inflammatory cellular accumulations, and inflammatory cytokines in peripheral nerves were significantly attenuated. Meanwhile, accumulation of immune cells in the spinal roots and microglial activation in the lumbar spinal cord were also reduced. Interestingly, Oridonin treatment significantly increased the proportion of anti-inflammatory macrophages and made them locally dominant among all infiltrated macrophages in the peripheral nerves. The down-regulation of local Notch pathway proteins, together with our in vitro results indicated their possible involvement. Taken together, our results demonstrated that Oridonin effectively suppressed EAN by attenuating local inflammatory reaction and increasing the proportion of immune regulating macrophages in the peripheral nerves, possibly through blockage of the Notch pathway, which suggests Oridonin as a potential therapeutic candidate for human GBS and neuropathies.

Dynamic thiol-disulphide homeostasis in patients with Guillain-Barre Syndrome

OBJECTIVE

The aim of this study was to evaluate dynamic thiol-disulphide homeostasis as a novel oxidative stress parameter in patients with Guillain-Barre syndrome (GBS).

METHODS

A total of 130 participants were included in this study, 70 of whom were diagnosed with GBS. Total thiol (-SH+-S-S-) and native thiol (-SH) levels in serum were measured in all patients and healthy individuals. Amount of dynamic disulphide bond were calculated from these values. In the GBS patients, disability status was determined by the Hughes and Medical Research Center (MRC) sum scores at the time of admission and 3 months thereafter.

RESULTS

Total and native thiol levels were significantly lower in patients with GBS compared with healthy individuals. There was no statistically significant difference in the number of dynamic disulphide bonds between groups. There was a negative correlation between total thiol levels in patients with GBS and Hughes scores at month 3.

DISCUSSION

Oxidative stress is among the molecular changes underlying the pathogenesis of GBS. In this study, we have investigated the dynamic thiol-disulfide homeostasis in patients with epilepsy using a new method in the literature. Also, functional recovery in Guillain-Barré syndrome patients could be promoted by increasing antioxidant activity.

Immune-mediated neuropathies

Since the discovery of an acute monophasic paralysis, later coined Guillain-Barré syndrome, almost 100 years ago, and the discovery of chronic, steroid-responsive polyneuropathy 50 years ago, the spectrum of immune-mediated polyneuropathies has broadened, with various subtypes continuing to be identified, including chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and multifocal motor neuropathy (MMN). In general, these disorders are speculated to be caused by autoimmunity to proteins located at the node of Ranvier or components of myelin of peripheral nerves, although disease-associated autoantibodies have not been identified for all disorders. Owing to the numerous subtypes of the immune-mediated neuropathies, making the right diagnosis in daily clinical practice is complicated. Moreover, treating these disorders, particularly their chronic variants, such as CIDP and MMN, poses a challenge. In general, management of these disorders includes immunotherapies, such as corticosteroids, intravenous immunoglobulin or plasma exchange. Improvements in clinical criteria and the emergence of more disease-specific immunotherapies should broaden the therapeutic options for these disabling diseases.

Immunotherapy of Guillain-Barré syndrome

Guillain-Barré syndrome (GBS), the most common cause of acute neuromuscular weakness and paralysis worldwide, encompasses a group of acute immune-mediated disorders restricted to peripheral nerves and roots. Immune-mediated attack of peripheral nervous system myelin, axons or both is presumed to be triggered by molecular mimicry, with both cell- and humoral-dependent mechanisms implicated in disease pathogenesis. Good circumstantial evidence exists for a pathogenic role for molecular mimicry in GBS pathogenesis, especially with its axonal forms, providing insights that could guide future immunotherapy. Intravenous immunoglobulin (IVIg) and plasma exchange (PE) are the most commonly prescribed immunotherapies for GBS with variable efficacy dependent on GBS subtype, severity at initial presentation and other clinical and electrophysiologic prognostic factors. The mechanisms of action of IVIg and PE are not known definitely. Despite recent significant advances in molecular biology that provide insights into GBS pathogenesis, no advances in therapeutics or significant improvements in patient outcomes have occurred over the past three decades. We summarize the clinical aspects of GBS, its current pathogenesis and immunotherapy, and highlight the potential of leukocyte trafficking inhibitors as novel disease-specific immunotherapeutic drugs.

Beneficial or Harmful Role of Macrophages in Guillain-Barré Syndrome and Experimental Autoimmune Neuritis

Guillain-Barré syndrome (GBS), an immune-mediated demyelinating peripheral neuropathy, is characterized by acute weakness of the extremities and areflexia or hyporeflexia. Experimental autoimmune neuritis (EAN) is a common animal model for GBS, which represents a CD4+ T cell-mediated inflammatory autoimmune demyelination of the peripheral nervous system (PNS), and is used to investigate the pathogenic mechanism of GBS. It has been found that macrophages play a critical role in the pathogenesis of both GBS and EAN. Macrophages have been primarily classified into two major phenotypes: proinflammatory macrophages (M1) and anti-inflammatory macrophages (M2). The two different macrophage subsets M1 and M2 may play a decisive role in initiation and development of GBS and EAN. However, recently, it has been indicated that the roles of macrophages in immune regulation and autoimmune diseases are more complex than those suggested by a simple M1-M2 dichotomy. Macrophages might exert either inflammatory or anti-inflammatory effect by secreting pro- or anti-inflammatory cytokines, and either inducing the activation of T cells to mediate immune response, resulting in inflammation and demyelination in the PNS, or promoting disease recovery. In this review, we summarize the dual roles of macrophages in GBS and EAN and explore the mechanism of macrophage polarization to provide a potential therapeutic approach for GBS in the future.

Beneficial or Harmful Role of Macrophages in Guillain-Barré Syndrome and Experimental Autoimmune Neuritis

Guillain-Barré syndrome (GBS), an immune-mediated demyelinating peripheral neuropathy, is characterized by acute weakness of the extremities and areflexia or hyporeflexia. Experimental autoimmune neuritis (EAN) is a common animal model for GBS, which represents a CD4⁺ T cell-mediated inflammatory autoimmune demyelination of the peripheral nervous system (PNS), and is used to investigate the pathogenic mechanism of GBS. It has been found that macrophages play a critical role in the pathogenesis of both GBS and EAN. Macrophages have been primarily classified into two major phenotypes: proinflammatory macrophages (M1) and anti-inflammatory macrophages (M2). The two different macrophage subsets M1 and M2 may play a decisive role in initiation and development of GBS and EAN. However, recently, it has been indicated that the roles of macrophages in immune regulation and autoimmune diseases are more complex than those suggested by a simple M1-M2 dichotomy. Macrophages might exert either inflammatory or anti-inflammatory effect by secreting pro- or anti-inflammatory cytokines, and either inducing the activation of T cells to mediate immune response, resulting in inflammation and demyelination in the PNS, or promoting disease recovery. In this review, we summarize the dual roles of macrophages in GBS and EAN and explore the mechanism of macrophage polarization to provide a potential therapeutic approach for GBS in the future.

Beneficial or Harmful Role of Macrophages in Guillain-Barré Syndrome and Experimental Autoimmune Neuritis

Guillain-Barré syndrome (GBS), an immune-mediated demyelinating peripheral neuropathy, is characterized by acute weakness of the extremities and areflexia or hyporeflexia. Experimental autoimmune neuritis (EAN) is a common animal model for GBS, which represents a CD4⁺ T cell-mediated inflammatory autoimmune demyelination of the peripheral nervous system (PNS), and is used to investigate the pathogenic mechanism of GBS. It has been found that macrophages play a critical role in the pathogenesis of both GBS and EAN. Macrophages have been primarily classified into two major phenotypes: proinflammatory macrophages (M1) and anti-inflammatory macrophages (M2). The two different macrophage subsets M1 and M2 may play a decisive role in initiation and development of GBS and EAN. However, recently, it has been indicated that the roles of macrophages in immune regulation and autoimmune diseases are more complex than those suggested by a simple M1-M2 dichotomy. Macrophages might exert either inflammatory or anti-inflammatory effect by secreting pro- or anti-inflammatory cytokines, and either inducing the activation of T cells to mediate immune response, resulting in inflammation and demyelination in the PNS, or promoting disease recovery. In this review, we summarize the dual roles of macrophages in GBS and EAN and explore the mechanism of macrophage polarization to provide a potential therapeutic approach for GBS in the future.

Class I PI3K inhibitor ZSTK474 attenuates experimental autoimmune neuritis by decreasing the frequency of Th1/Th17 cells and reducing the production of proinflammatory cytokines

The Class I phosphatidylinositol 3-kinase inhibitor, 2-(2-difluoromethy lbenzimidazol-1-yl)-4,6-dimorpholino-1,3,5-triazine (ZSTK474), has anti-inflammatory and immunoregulatory properties. However, whether it can be used to treat Guillain-Barré syndrome (GBS)-a neuroinflammatory disorder-is unknown. We induced experimental autoimmune neuritis (EAN) in Lewis rats, an established model of GBS. Orally administered ZSTK474 decreased neurological deficits in the GBS model, as demonstrated by diminished inflammatory cell infiltration, and ameliorated demyelination of sciatic nerves. Additionally, ZSTK474 decreased the number of Th1/Th17 cells and levels of the proinflammatory cytokines interleukin (IL)-1α, IL-1β, IL-17, IL-23, interferon-γ, and tumor necrosis factor-α. We propose that the phosphoinositide 3-kinase/AKT/mammalian target of rapamycin complex 1 (PI3K/AKT/mTORC1) pathway likely contributed to the neuroprotective effect of ZSTK474. ZSTK474 effectively decreases the frequency of Th1/Th17 cells, thereby reducing the production of proinflammatory cytokines and successfully alleviating the symptoms of EAN. Thus, the neuroprotective effect of ZSTK474 indicates its potential utility as anti-inflammatory therapy for GBS.

PR-957, a selective inhibitor of immunoproteasome subunit low-MW polypeptide 7, attenuates experimental autoimmune neuritis by suppressing Th17-cell differentiation and regulating cytokine production

Experimental autoimmune neuritis (EAN) is a CD4⁺ T-cell-mediated autoimmune inflammatory demyelinating disease of the peripheral nervous system. It has been replicated in an animal model of human inflammatory demyelinating polyradiculoneuropathy, Guillain-Barré syndrome. In this study, we evaluated the therapeutic efficacy of a selective inhibitor of the immunoproteasome subunit, low-MW polypeptide 7 (PR-957) in rats with EAN. Our results showed that PR-957 significantly delayed onset day, reduced severity and shortened duration of EAN, and alleviated demyelination and inflammatory infiltration in sciatic nerves. In addition to significantly regulating expression of the cytokine profile, PR-957 treatment down-regulated the proportion of proinflammatory T-helper (T_h)17 cells in sciatic nerves and spleens of rats with EAN. Data presented show the role of PR-957 in the signal transducer and activator of transcription 3 (STAT3) pathway. PR-957 not only decreased expression of IL-6 and IL-23 but also led to down-regulation of STAT3 phosphorylation in CD4⁺ T cells. Regulation of the STAT3 pathway led to a reduction in retinoid-related orphan nuclear receptor γ t and IL-17 production. Furthermore, reduction of STAT3 phosphorylation may have directly suppressed T_h17-cell differentiation. Therefore, our study demonstrates that PR-957 could potently alleviate inflammation in rats with EAN and that it may be a likely candidate for treating Guillain-Barré syndrome.-Liu, H., Wan, C., Ding, Y., Han, R., He, Y., Xiao, J., Hao, J. PR-957, a selective inhibitor of immunoproteasome subunit low-MW polypeptide 7, attenuates experimental autoimmune neuritis by suppressing T_h17-cell differentiation and regulating cytokine production.

The pathogenic relevance of αM-integrin in Guillain-Barré syndrome

The molecular determinants and mechanisms involved in leukocyte trafficking across the blood-nerve barrier (BNB) in the acute inflammatory demyelinating polyradiculoneuropathy (AIDP) variant of Guillain-Barré syndrome are incompletely understood. Prior work using a flow-dependent in vitro human BNB model demonstrated a crucial role for α_M-integrin (CD11b)-intercellular adhesion molecule-1 interactions in AIDP patient leukocyte trafficking. The aim of this study is to directly investigate the biological relevance of CD11b in AIDP pathogenesis. Immunohistochemistry was performed on three AIDP patient sural nerve biopsies to evaluate endoneurial leukocyte CD11b expression. A severe murine experimental autoimmune neuritis (sm-EAN) model was utilized to determine the functional role of CD11b in leukocyte trafficking in vivo and determine its effect on neurobehavioral measures of disease severity, electrophysiological assessments of axonal integrity and myelination and histopathological measures of peripheral nerve inflammatory demyelination. Time-lapse video microscopy and electron microscopy were employed to observe structural alterations at the BNB during AIDP patient leukocyte trafficking in vitro and in situ, respectively. Large clusters of endoneurial CD11b+ leukocytes associated with demyelinating axons were observed in AIDP patient sural nerves. Leukocyte CD11b expression was upregulated during sm-EAN. 5 mg/kg of a function-neutralizing monoclonal rat anti-mouse CD11b antibody administered after sm-EAN disease onset significantly ameliorated disease severity, as well as electrophysiological and histopathological parameters of inflammatory demyelination compared to vehicle- and isotype antibody-treated mice. Consistent with in vitro observations of leukocyte trafficking at the BNB, electron micrographs of AIDP patient sural nerves demonstrated intact electron-dense endoneurial microvascular intercellular junctions during paracellular mononuclear leukocyte transmigration. Our data support a crucial pathogenic role of CD11b in AIDP leukocyte trafficking, providing a potential therapeutic target for demyelinating variants of Guillain-Barré syndrome.

Programmed Death Ligand 1 Plays a Neuroprotective Role in Experimental Autoimmune Neuritis by Controlling Peripheral Nervous System Inflammation of Rats

Programmed death 1 (PD-1; CD279), a member of the CD28 family, is an inhibitory receptor on T cells and is responsible for T cell dysfunction in infectious diseases and cancers. The ligand for PD-1, programmed death ligand 1 (PD-L1; also known as B7-H1, CD274), is a member of the B7 family. The engagement of PD-1 with programmed death ligand can downregulate autoreactive T cells that participate in multiple autoimmune diseases. Experimental autoimmune neuritis (EAN) is an animal model of Guillain-Barré syndrome, and the pathogenesis of EAN is mediated principally through T cells and macrophages. In this study, we investigated the effects of PD-L1 in EAN rats. For preventative and therapeutic management, we administered PD-L1, which successfully decreased the severity of EAN; it alleviated the neurologic course of EAN, as well as inhibited the infiltration of inflammatory cells and demyelination of sciatic nerves. Our data revealed that PD-L1 treatment inhibited lymphocyte proliferation and altered T cell differentiation by inducing decreases in IFN-γ⁺CD4⁺ Th1 cells and IL-17⁺CD4⁺ Th17 cells and increases in IL-4⁺CD4⁺ Th2 cells and Foxp3⁺CD4⁺ regulatory T cells. The expression levels of p-STAT3 and Foxp3 were significantly different in PD-L1-treated groups compared with the control group. Additionally, PD-L1 regulated the expression of Foxp3 and p-STAT3 in EAN, probably by inhibiting PI3K/AKT/mTOR signaling expression. In summary, PD-L1 is a potentially useful agent for the treatment of EAN because of its anti-inflammatory and neuroprotective effects.

[Systemic vasculitic neuropathy diagnosed by means of (18)F-FDG PET CT]

We report a 43-year-old man experienced numbness in the distal portion of both legs, which progressed over following two months. Neurological examination showed hypesthesia and muscle weakness in the distal portion of both legs. No abnormal findings were seen on blood test and whole-body contrast enhanced computed tomography (CT). Histopathological findings of the sural nerve and the peroneus brevis muscle showed decreased myelinated nerve fibers with scattered myelin ovoids, vascular occlusion in the epineurium, and inflammatory cell around the arteriole in the muscle bundle. These findings suggested falling in the category as non-systemic vasculitic neuropathy (NSVN). (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) revealed the increase of FDG uptake in the rectum. Inflammatory cell infiltration was found around the arteriole with fibrinoid necrosis in the histopathological specimen of the rectal mucosal biopsy. This result represented the diagnosis as systemic vasculitis. The diagnosis of NSVN may depend on the sensitivity of diagnostic procedure, and (18)F-FDG PET CT might be a useful tool to detect small or medium-sized vasculitis.

Modeling leukocyte trafficking at the human blood-nerve barrier in vitro and in vivo geared towards targeted molecular therapies for peripheral neuroinflammation

Peripheral neuroinflammation is characterized by hematogenous mononuclear leukocyte infiltration into peripheral nerves. Despite significant clinical knowledge, advancements in molecular biology and progress in developing specific drugs for inflammatory disorders such as rheumatoid arthritis, inflammatory bowel disease, and multiple sclerosis, there are currently no specific therapies that modulate pathogenic peripheral nerve inflammation. Modeling leukocyte trafficking at the blood-nerve barrier using a reliable human in vitro model and potential intravital microscopy techniques in representative animal models guided by human observational data should facilitate the targeted modulation of the complex inflammatory cascade needed to develop safe and efficacious therapeutics for immune-mediated neuropathies and chronic neuropathic pain.

A comparison between plasmapheresis and intravenous immunoglobulin in children with Guillain-Barré syndrome in Upper Egypt

OBJECTIVE

The aim of our study is to assess the clinico-electrophysiological profile of children with Guillain-Barré syndrome (GBS) in Upper Egypt and to compare the efficacy of plasmapheresis versus other treatment modalities.

PATIENTS AND METHODS

This was a retrospective study of children from January 2010 to October 2014 diagnosed as GBS. It included 62 cases.

RESULTS

Acute inflammatory demyelinating polyradiculoneuropathy (AIDP) was the most prevalent type of GBS in our locality. As regards the treatment, 32 cases received plasmapheresis while 30 patients received intravenous immunoglobulin. We found a significant decrease in the duration of hospitalization and a significant increase in the number of children with complete recovery in cases treated with plasmapheresis.

CONCLUSION

GBS is not uncommon in children of Upper Egypt, with AIDP the most prevalent type. Plasmapheresis is the best treatment modalities for GBS as it reduces the duration of hospital stay and hastens the recovery of those children.

Dimethyl Fumarate Ameliorates Lewis Rat Experimental Autoimmune Neuritis and Mediates Axonal Protection

BACKGROUND

Dimethyl fumarate is an immunomodulatory and neuroprotective drug, approved recently for the treatment of relapsing-remitting multiple sclerosis. In view of the limited therapeutic options for human acute and chronic polyneuritis, we used the animal model of experimental autoimmune neuritis in the Lewis rat to study the effects of dimethyl fumarate on autoimmune inflammation and neuroprotection in the peripheral nervous system.

METHODS AND FINDINGS

Experimental autoimmune neuritis was induced by immunization with the neuritogenic peptide (amino acids 53-78) of P2 myelin protein. Preventive treatment with dimethyl fumarate given at 45 mg/kg twice daily by oral gavage significantly ameliorated clinical neuritis by reducing demyelination and axonal degeneration in the nerve conduction studies. Histology revealed a significantly lower degree of inflammatory infiltrates in the sciatic nerves. In addition, we detected a reduction of early signs of axonal degeneration through a reduction of amyloid precursor protein expressed in axons of the peripheral nerves. This reduction correlated with an increase of nuclear factor (erythroid derived 2)-related factor 2 positive axons, supporting the neuroprotective potential of dimethyl fumarate. Furthermore, nuclear factor (erythroid derived 2)-related factor 2 expression in Schwann cells was only rarely detected and there was no increase of Schwann cells death during EAN.

CONCLUSIONS

We conclude that immunomodulatory and neuroprotective dimethyl fumarate may represent an innovative therapeutic option in human autoimmune neuropathies.

Inflammatory neuropathies: pathology, molecular markers and targets for specific therapeutic intervention

Inflammatory neuropathies encompass groups of heterogeneous disorders characterized by pathogenic immune-mediated hematogenous leukocyte infiltration of peripheral nerves, nerve roots or both, with resultant demyelination or axonal degeneration or both. Inflammatory neuropathies may be divided into three major disease categories: Guillain-Barré syndrome (particularly the acute inflammatory demyelinating polyradiculoneuropathy variant), chronic inflammatory demyelinating polyradiculoneuropathy and nonsystemic vasculitic neuropathy (or peripheral nerve vasculitis). Despite major advances in molecular biology, pathology and genetics, the pathogenesis of these disorders remains elusive. There is insufficient knowledge on the mechanisms of hematogenous leukocyte trafficking into the peripheral nervous system to guide the development of specific molecular therapies for immune-mediated inflammatory neuropathies compared to disorders such as psoriasis, inflammatory bowel disease, rheumatoid arthritis or multiple sclerosis. The recent isolation and characterization of human endoneurial endothelial cells that form the blood-nerve barrier provides an opportunity to elucidate leukocyte-endothelial cell interactions critical to the pathogenesis of inflammatory neuropathies at the interface between the systemic circulation and peripheral nerve endoneurium. This review discusses our current knowledge of the classic pathological features of inflammatory neuropathies, attempts at molecular classification and genetic determinants, the utilization of in vitro and in vivo animal models to determine pathogenic mechanisms at the interface between the systemic circulation and the peripheral nervous system relevant to these disorders and prospects for future potential molecular pathology biomarkers and targets for specific therapeutic intervention.

Lymphoma-associated dysimmune polyneuropathies

Lymphoma consists of a variety of malignancies of lymphocyte origin. A spectrum of clinical peripheral neuropathy syndromes with different disease mechanisms occurs in about 5% of lymphoma patients. There exists a complex inter-relationship between lymphoproliferative malignancies and autoimmunity. An imbalance in the regulation of the immune system presumably underlies various immune-mediated neuropathies in patients with lymphoma. This article reviews lymphoma and more-or-less well-defined dysimmune neuropathy subgroups that are caused by humoral and/or cell-mediated immune disease mechanisms directed against known or undetermined peripheral nerve antigens.

The Pentapeptide QYNAD Does Not Inhibit Neuronal Network Activity

Background:

Controversial data was published about the sodium channel-blocking effect of the endogenous pentapeptide QYNAD, which is elevated in patients with multiple sclerosis and Guillain-Barré-syndrome. In some experiments with single cells and nerve preparations QYNAD inhibited sodium currents to the same extent as the known sodium channel blocker lidocaine whereas in other laboratory testing QYNAD failed to show any effect at all.

Methods:

Micro-electrode arrays with cultured neuronal networks are highly suitable to determine neuroactive activity of applied substances. The impact on electrophysiological parameter changes was compared between QYNAD and the established sodium channel blockers lidocaine and tetrodotoxin (TTX).

Results:

QYNAD did not alter network activity whereas the sodium channel blockers lidocaine (IC50 14.9 µM) and tetrodotoxin (IC50 1.1 nM) reversibly decreased network activity in similar concentrations as in patch-clamp experiments. This decrease of spontaneous electrophysiological activity was achieved by prolonging the interburst-interval.

Conclusion:

Although QYNAD might have mild effects on single-cell sodium currents, there is no significant effect on neuronal network function. These results raise concerns about QYNAD exhibiting a relevant impact on functional disability of the central nervous system in patients.

ADAM17 at the interface between inflammation and autoimmunity

The discovery of the disintegrin and metalloproteinase 17 (ADAM17), originally identified as tumor necrosis factor-a converting enzyme (TACE) for its ability as sheddase of TNF-α inspired scientists to attempt to elucidate the molecular mechanisms underlying ADAM17 implication in diseased conditions. In recent years, it has become evident that this protease can modify many non matrix substrates, such as cytokines (e.g. TNF-α), cytokine receptors (e.g. IL-6R and TNF-R), ligands of ErbB (e.g. TGF-α and amphiregulin) and adhesion proteins (e.g. Lselectin and ICAM-1). Several recent studies have described experimental model system to better understand the role of specific signaling molecules, the interplay of different signals and tissue interactions in regulating ADAM17-dependent cleavage of most relevant substrates in inflammatory diseases. The central question is whether ADAM17 can influence the outcome of inflammation and if so, how it performs this regulation in autoimmunity, since inflammatory autoimmune diseases are often characterized by deregulated metalloproteinase activities. This review will explore the latest research on the influence of ADAM17 on the progression of inflammatory processes linked to autoimmunity and its role as modulator of inflammation.

Contrasting immune responses mediate Campylobacter jejuni-induced colitis and autoimmunity

Campylobacter jejuni is a leading cause of foodborne enteritis that has been linked to the autoimmune neuropathy, Guillain Barré syndrome (GBS). C57BL/6 interleukin (IL)-10(+/+) and congenic IL-10(-/-) mice serve as C. jejuni colonization and colitis models, respectively, but a mouse model for GBS is lacking. We demonstrate that IL-10(-/-) mice infected with a C. jejuni colitogenic human isolate had significantly upregulated type 1 and 17 but not type 2 cytokines in the colon coincident with infiltration of phagocytes, T cells and innate lymphoid cells (ILCs). Both ILC and T cells participated in interferon-γ (IFN-γ), IL-17, and IL-22 upregulation but in a time- and organ-specific manner. T cells were, however, necessary for colitis as mice depleted of Thy-1(+) cells were protected while neither Rag1(-/-) nor IL-10R blocked Rag1(-/-) mice developed colitis after infection. Depleting IFN-γ, IL-17, or both significantly ameliorated colitis and drove colonic responses toward type 2 cytokine and antibody induction. In contrast, C. jejuni GBS patient strains induced mild colitis associated with blunted type 1/17 but enhanced type 2 responses. Moreover, the type 2 but not type 1/17 antibodies cross-reacted with peripheral nerve gangliosides demonstrating autoimmunity.

Laquinimod exerts strong clinical and immunomodulatory effects in Lewis rat experimental autoimmune neuritis

Laquinimod is an immunomodulatory drug with neuroprotective potential. We used the animal model of experimental autoimmune neuritis (EAN) in the Lewis rat to study the effects of laquinimod treatment. After immunization with the neuritogenic peptide aa 53-78 of P2 myelin protein, preventive therapy with 12.5mg/kg laquinimod once daily inhibited neuritis in clinical and electrophysiological terms. Histology corroborated a lower degree of inflammatory lesions and demyelination in the sciatic nerve. The proportion of FoxP3-positive regulatory T cells in the peripheral lymph nodes of treated rats remained unchanged. We conclude that laquinimod may represent a therapeutic option in human autoimmune neuropathies.

Risk of Guillain-Barré syndrome following pandemic influenza A(H1N1) 2009 vaccination in Germany

Purpose

A prospective, epidemiologic study was conducted to assess whether the 2009 pandemic influenza A(H1N1) vaccination in Germany almost exclusively using an AS03-adjuvanted vaccine (Pandemrix) impacts the risk of Guillain–Barré syndrome (GBS) and its variant Fisher syndrome (FS).

Methods

Potential cases of GBS/FS were reported by 351 participating hospitals throughout Germany. The self-controlled case series methodology was applied to all GBS/FS cases fulfilling the Brighton Collaboration (BC) case definition (levels 1–3 of diagnostic certainty) with symptom onset between 1 November 2009 and 30 September 2010 reported until end of December 2010.

Results

Out of 676 GBS/FS reports, in 30 cases, GBS/FS (BC levels 1–3) occurred within 150 days following influenza A(H1N1) vaccination. The relative incidence of GBS/FS within the primary risk period (days 5–42 post-vaccination) compared with the control period (days 43–150 post-vaccination) was 4.65 (95%CI [2.17, 9.98]). Similar results were found when stratifying for infections within 3 weeks prior to onset of GBS/FS and when excluding cases with additional seasonal influenza vaccination. The overall result of temporally adjusted analyses supported the primary finding of an increased relative incidence of GBS/FS following influenza A(H1N1) vaccination.

Conclusions

The results indicate an increased risk of GBS/FS in temporal association with pandemic influenza A(H1N1) vaccination in Germany. © 2014 The Authors. Pharmacoepidemiology and Drug Safety published by John Wiley & Sons, Ltd.

Erythropoietin-derived nonerythropoietic peptide ameliorates experimental autoimmune neuritis by inflammation suppression and tissue protection

Experimental autoimmune neuritis (EAN) is an autoantigen-specific T-cell-mediated disease model for human demyelinating inflammatory disease of the peripheral nervous system. Erythropoietin (EPO) has been known to promote EAN recovery but its haematopoiesis stimulating effects may limit its clinic application. Here we investigated the effects and potential mechanisms of an EPO-derived nonerythropoietic peptide, ARA 290, in EAN. Exogenous ARA 290 intervention greatly improved EAN recovery, improved nerve regeneration and remyelination, and suppressed nerve inflammation. Furthermore, haematopoiesis was not induced by ARA 290 during EAN treatment. ARA 290 intervention suppressed lymphocyte proliferation and altered helper T cell differentiation by inducing increase of Foxp3+/CD4+ regulatory T cells and IL-4+/CD4+ Th2 cells and decrease of IFN-γ+/CD4+ Th1 cells in EAN. In addition, ARA 290 inhibited inflammatory macrophage activation and promoted its phagocytic activity. In vitro, ARA 290 was shown to promote Schwann cell proliferation and inhibit its inflammatory activation. In summary, our data demonstrated that ARA 290 could effectively suppress EAN by attenuating inflammation and exerting direct cell protection, indicating that ARA 290 could be a potent candidate for treatment of autoimmune neuropathies.

Accumulation of fascin+ cells during experimental autoimmune neuritis

BACKGROUND

Experimental autoimmune neuritis (EAN) is a well-known animal model of human demyelinating polyneuropathies and is characterized by inflammation and demyelination in the peripheral nervous system. Fascin is an evolutionarily highly conserved cytoskeletal protein of 55 kDa containing two actin binding domains that cross-link filamentous actin to hexagonal bundles.

METHODS

Here we have studied by immunohistochemistry the spatiotemporal accumulation of Fascin + cells in sciatic nerves of EAN rats.

RESULTS

A robust accumulation of Fascin + cell was observed in the peripheral nervous system of EAN which was correlated with the severity of neurological signs in EAN.

CONCLUSION

Our results suggest a pathological role of Fascin in EAN.

VIRTUAL SLIDES

The virtual slides for this article can be found here: http://www.diagnosticphatology.diagnomx.eu/vs/6734593451114811.

Keratan sulfate expression in microglia is diminished in the spinal cord in experimental autoimmune neuritis

Experimental autoimmune neuritis (EAN) is an animal model of Guillain–Barré syndrome, an inflammatory demyelination disease of the peripheral nervous system. Although this disease has been extensively studied on peripheral nerves, the pathology of the central nervous system has not been fully understood. Previous studies demonstrate that expression of keratan sulfate (KS), the sugar chain of proteoglycan, is associated with activated microglia/macrophages accumulated after neuronal injuries. Unexpectedly, we found here that KS is rather diminished in rat EAN. KS was restrictively expressed in microglia in the spinal cord of normal rats. KS was positive in 50% microglia in the ventral horn and 20% in the dorsal horn. In EAN, microglia increased in number and expressed the activation marker CD68, but KS expression was abolished. Concomitantly, pro-inflammatory cytokines, i.e., interferon (IFN)-γ, interleukin (IL)-1β, and tumor necrosis factor (TNF)-α, were increased in the spinal cord of EAN rats, whereas anti-inflammatory cytokines, such as IL-4 and IL-10, were decreased. In addition, silencing of KSGal6ST attenuated KS expression on the primary cultured microglia and upregulated expression of some activation markers (TNF-α, IL-1β, and iNOS) under the stimulation with lipopolysaccharide and IFN-γ. This study demonstrates for the first time a close association of EAN and disappearance of KS on microglia. KS expression could be a useful marker to evaluate the status of polyneuropathy.

Intravenous immunoglobulin preparation attenuates neurological signs in rat experimental autoimmune neuritis with the suppression of macrophage inflammatory protein -1α expression

To clarify the mechanism of action of an intravenous immunoglobulin (IVIG) preparation in chronic inflammatory demyelinating polyneuropathy, the effects of IVIG were investigated using an experimental autoimmune neuropathy model in the rat. IVIG significantly suppressed the progression of neurologic signs and sciatic nerve conduction velocity with the inhibition of inflammatory cell infiltration, mainly of macrophages, to the peripheral nerves. A significant suppressive effect on the expression of macrophage inflammatory protein 1-α (MIP-1α) was simultaneously observed in the nerves. These results suggest that IVIG is effective for inflammatory demyelinating polyneuropathy by inhibiting the chemotactic factor of macrophages.

The role of chemokines in Guillain-Barré syndrome

INTRODUCTION

Chemokines and their receptors are important mediators of inflammation. Guillain-Barré syndrome (GBS) is the most common cause of acute paralysis worldwide. Despite current treatments, outcomes are suboptimal. Specific chemokine receptor antagonists have the potential to be efficacious against pathogenic leukocyte trafficking in GBS.

METHODS

A 36-year literature review was performed to summarize available data on chemokine expression in GBS and its representative animal model, experimental autoimmune neuritis (EAN).

RESULTS

Although there were a few observational human and animal studies demonstrating chemokine ligand/receptor expression in GBS and EAN, in vitro and in vivo functional studies using gene knockouts, neutralizing antibodies, or small molecular antagonists were limited. CCL2-CCR2, CCL5-CCR5, and CXCL10-CXCR3 have been most strongly implicated in EAN and GBS pathogenesis, providing targets for molecular blockade.

CONCLUSIONS

Preclinical human in vitro and in vivo EAN studies are needed to evaluate the potential efficacy of chemokine signaling inhibition in GBS.

A review of the use of biological agents for chronic inflammatory demyelinating polyradiculoneuropathy

Chronic inflammatory demyelinating polyneuropathy (CIDP) is a group of idiopathic, acquired, immune-mediated inflammatory demyelinating diseases of the peripheral nervous system. A majority of patients with CIDP respond to "first-line" treatment with IVIG, plasmapheresis and/or corticosteroids. There exists insufficient evidence to ascertain the benefit of treatment with "conventional" immunosuppressive drugs. The inconsistent efficacy, long-term financial burden and health risks of non-specific immune altering therapy have drawn recurrent attention to the possible usefulness of a variety of biological agents that target key aspects in the CIDP immunopathogenic pathways. This review aims to give an updated account of the scientific rationale and potential use of biological therapeutics in patients with CIDP. No specific treatment recommendations are given. The discovery, development and application of biological markers by modern molecular diagnostic techniques may help identify drug-naïve or treatment-resistant CIDP patients most likely to respond to targeted immunotherapy.

Sphingolipids in neuroinflammation

Sphingolipids, the main component of cellular membranes, are cellular 'jack-of-all-trades', influencing a variety of functions including signal transduction, cell activation, membrane fluidity and cell-cell interactions.In the last few years, sphingolipids have begun to be investigated in the pathophysiology of major diseases of the brain, e.g. multiple sclerosis and dementia. Modulation of neuroinflammatory responses, such as lymphocyte behaviour, is a chance to intervene in the pathways that cause disease. There is much research still to be done in this field, but the prospect of treating previously untreatable medical conditions compels us onwards. Here, we review the current knowledge of the link between sphingolipids and neuroinflammation.