Combined platelet-to-lymphocyte ratio and blood-brain barrier biomarkers as indicators of disability in acute neuromyelitis optica spectrum disorder

BACKGROUND

Neuromyelitis optica spectrum disorder (NMOSD) is a complex neuroinflammatory disease characterized by severe disability. In this study, we investigated the relationship between cerebrospinal fluid (CSF)/serum albumin quotient (Qalb) and platelet to lymphocyte ratio (PLR) in assessing disease severity.

METHOD

A retrospective analysis of 72 NMOSD patients and 72 healthy controls was conducted, and patients were divided into two groups based on their Expanded Disability Status Scale (EDSS) scores.

RESULTS

NMOSD patients had significantly higher levels of serum PLR, neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), and C-reactive protein (CRP) compared to healthy controls (all P<0.01). Patients in the EDSS≥4 group exhibited significantly elevated levels of Qalb, QIgG, QIgA, QIgM, and PLR (P=0.000, P<0.0001, P=0.0019, P=0.0001, respectively). Spearman's correlation test revealed significant positive associations between Qalb, QIgG, QIgA, QIgM, PLR, and EDSS score. Specifically, Qalb (r=0.571; P<0.001), QIgG (r=0.551; P<0.001), QIgA (r=0.519; P<0.001), and QIgM (r=0.541; P<0.001) demonstrated significant positive correlations with EDSS score, while PLR exhibited a moderate positive correlation (r=0.545; P<0.001) with EDSS score and a mild positive association (r=0.387; P<0.001) with Qalb. The increase of Qalb was positively correlated with the increased EDSS score (r=0.528, P=0.001), as well as the increase of QIgG (r=0.509, P=0.001), and the increase of QIgA (r=0.4989, P=0.03). ROC analysis indicated that Qalb, QIgG, QIgA, QIgM, and PLR levels could effectively serve as indicators of NMOSD severity (all P<0.0001). Multivariate analysis confirmed the independent significance of Qalb and PLR in assessing disease severity (P=0.000).

CONCLUSION

These findings provide valuable insights into the risk and pathogenesis of NMOSD and highlight the potential of Qalb and PLR as independent markers for disease severity assessment in NMOSD patients.

MMP-2-mediated Scube2 degradation promotes blood-brain barrier disruption by blocking the interaction between astrocytes and endothelial cells via inhibiting Sonic hedgehog pathway during early cerebral ischemia

We have previously demonstrated a rapid secretion of matrix metalloproteinase-2 (MMP-2) in the ischemic brain. Since Scube2 can interact with Sonic hedgehog (Shh) to maintain blood-brain barrier (BBB) integrity via regulating the interaction between brain capillary endothelial cells (ECs) and perivascular astrocytes, and it is also a substrate of MMP-2, we hypothesized that the secreted MMP-2 could degrade Scube2 and contribute to ischemic BBB disruption. Using an in vitro ischemic model of 90-min oxygen-glucose deprivation/3-h reoxygenation (OGD/R) and an in vivo mouse stroke model of 90-min middle cerebral artery occlusion (MCAO) with 3-h reperfusion, we established an important role of MMP-2-mediated Scube2 degradation in early ischemic BBB disruption. Exposure of C8-D1A cells and bEnd.3 cells to OGD/R increased MMP secretion in both cells, and C8-D1A cells appeared to secrete more MMPs than bEnd.3 cells. Co-IP and double-immunostaining revealed that Scube2 co-localized well with MMP-2 in C8-D1A cells and could be pulled down by MMP-2 antibodies. In MCAO mice, Scube2 protein showed a drastic reduction in ischemic brain tissue, which was accompanied by suppressed expression of Shh and its downstream molecules. Of note, specific knockdown of astrocytic Scube2 with AAV-shScube2 augmented MCAO-induced Shh suppression and exacerbated BBB leakage and inflammatory reactions in the ischemic brain. Last, incubation of bEnd.3 cells with conditioned medium derived from OGD-treated C8-D1A cells led to a significant inhibition of the Shh pathway in bEnd.3 cells and degradation of VE-cadherin and ZO-1. Inhibition of MMP-2 with SB-3CT or over-expression of Scube2 with plasmids in C8-D1A cells alleviated the above effect of C8-D1A cells-derived conditioned medium. Taken together, our data indicate that ischemia-induced secretion of MMP-2 may contribute to early BBB disruption in ischemic stroke via interrupting the shared Scube2-Shh pathway between brain capillary ECs and perivascular astrocytes.

Intradermal AQP4 peptide immunization induces clinical features of neuromyelitis optica spectrum disorder in mice

We challenged to create a mouse model of neuromyelitis optica spectrum disorder (NMOSD) induced by AQP4 peptide immunization. Intradermal immunization with AQP4 p201-220 peptide induced paralysis in C57BL/6J mice, but not in AQP4 KO mice. AQP4 peptide-immunized mice showed pathological features similar to NMOSD. Administration of anti-IL-6 receptor antibody (MR16-1) inhibited the induction of clinical signs and prevented the loss of GFAP/AQP4 and deposition of complement factors in AQP4 peptide-immunized mice. This novel experimental model may contribute to further understanding the pathogenesis of NMOSD, elucidating the mechanism of action of therapeutic agents, and developing new therapeutic approaches.

Interleukin-6 as a marker of Huntington's disease progression: Systematic review and meta-analysis

Huntington's disease (HD) is a rare, inherited disorder with a broad spectrum of manifestations that vary with disease severity and progression. Although genetic testing can readily confirm the initial diagnosis of HD, markers sensitive to HD progression are needed to aid the development of individual treatment plans. The current analysis aims to identify plasma Interleukin-6 (IL-6) as a marker of disease progression in HD patients. A systematic search of PubMed and Medline from conception through October 2021 was conducted. Studies reporting plasma IL-6 levels of mutation-positive HD patients and healthy controls that met inclusion criteria were selected. The search strategy collected 303 studies, 9 of which met analysis inclusion criteria. From included studies, plasma IL-6 levels of 469 individuals with the HD mutation and 206 healthy controls were collected. Plasma IL-6 levels were meta-analytically compared between healthy controls and individuals with the confirmed HD mutation at all stages of disease and correlated to performance on standardized measures of total cognitive and motor function. Plasma IL-6 was significantly increased in HD groups compared to controls (g = 0.73, 95% CI = 0.31,1.16, P < 0.01) and increased significantly throughout most stages of disease progression, notably between pre-manifest and manifest (g = 0.31, 95% CI = 0.04,0.59, P < 0.05) and early and moderate HD stages (g = 0.52, 95% CI = 0.18,0.86, P < 0.01). Significant correlations between plasma IL-6 levels and HD symptomatic progression were identified, with increased cytokine levels associated with more severe motor impairments (r = 0.179, 95% CI = 0.0479,0.304, P = 0.008) and more extreme disabilities in activities of daily living and/or work tasks (r = -0.229, 95% CI = -0.334, -0.119, P < 0.001). Conclusively, plasma IL-6 levels correlate with disease and motor symptom progression and may act as a viable marker for clinical use. Analysis is limited by small study numbers and highlights the need for future work to identify definitive ranges or rates of change of plasma IL-6 levels that correlate to progressive HD disease states.

Association of cerebrospinal inflammatory profile with radiological features in newly diagnosed treatment-naïve patients with multiple sclerosis

Objective

Multiple sclerosis (MS) is an immune-mediated demyelinating disease of the central nervous system. Without reliable diagnostic biomarkers, the clinical and radiological heterogeneity of MS makes diagnosis difficult. Although magnetic resonance imaging (MRI) is a major diagnostic tool for MS, the association of MRI findings with the inflammatory profile in cerebrospinal fluid (CSF) has been insufficiently investigated. Therefore, we focused on CSF profile of MS patients and examined its association with MRI findings.

Methods

Concentrations of 26 cytokines and chemokines were determined in CSF of 28 treatment-naïve MS patients and 12 disease-control patients with aquaporin-4 antibody-seropositive neuromyelitis optica spectrum disorder (NMOSD).

Results

High levels of interleukin (IL)-6, IL-17A, B-cell activating factor (BAFF), a proliferation inducing ligand (APRIL), and CD40 ligand were correlated with the absence of at least one of the following three MRI findings in MS: an ovoid lesion, three or more periventricular lesions, and a nodular and/or ring-shaped contrast-enhancing lesion. The multivariate analysis revealed that elevated IL-17A was an independent predictor of absence of ovoid lesion and periventricular lesions less than three. MS patients were classified into a group with all three MRI findings (MS-full) and a group with less than three (MS-partial). The discriminant analysis model distinguished three groups: MS-full, MS-partial, and NMOSD, with 98% accuracy.

Conclusion

The CSF inflammatory profile was associated with radiological findings of treatment-naïve MS. This result indicates the possible utility of combined CSF and MRI profiling in identifying different MS phenotypes related to the heterogeneity of underlying immune processes.

Complete Relief of Painful Tonic Seizures in Neuromyelitis Optica Spectrum Disorder by Satralizumab Treatment

Satralizumab, a monoclonal antibody against interleukin-6 receptors, has been approved for the treatment of neuromyelitis optica spectrum disorder (NMOSD). Several reports have described the effectiveness of satralizumab against neuropathic pain in patients with NMOSD, but its effects on painful tonic seizures have not yet been reported. We herein report a Japanese woman with anti-aquaporin-4 antibody-positive NMOSD whose painful tonic seizures completely resolved after six months of satralizumab treatment. In conclusion, interleukin-6 blocking may be effective against painful tonic seizures. This effect may be due to suppression of microglial activation and the resultant neuronal hyperexcitability.

Neuromyelitis Optica Spectrum Disorder: From Basic Research to Clinical Perspectives

Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory disease of the central nervous system characterized by relapses and autoimmunity caused by antibodies against the astrocyte water channel protein aquaporin-4. Over the past decade, there have been significant advances in the biologic knowledge of NMOSD, which resulted in the IDENTIFICATION of variable disease phenotypes, biomarkers, and complex inflammatory cascades involved in disease pathogenesis. Ongoing clinical trials are looking at new treatments targeting NMOSD relapses. This review aims to provide an update on recent studies regarding issues related to NMOSD, including the pathophysiology of the disease, the potential use of serum and cerebrospinal fluid cytokines as disease biomarkers, the clinical utilization of ocular coherence tomography, and the comparison of different animal models of NMOSD.

NMO-IgG induce interleukin-6 release via activation of the NF-κB signaling pathway in astrocytes

Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory demyelinating disorder of the central nervous system (CNS) that frequently affects the optic nerve and spinal cord. Interleukin-6 (IL-6) is considered a key cytokine in the pathogenesis of NMOSD, and the level of IL-6 is significantly increased in the sera and cerebrospinal fluid (CSF) of patients with NMOSD. We have reported that the production of IL-6 depends on the JAK/STAT3 signaling pathway. However, it is not clear whether the NF-κB-dependent inflammatory response stimulated by neuromyelitis optica IgG (NMO-IgG) could also drive the production of IL-6 in astrocytes. In this study, we used an in vitro model of primary rat astrocytes stimulated by NMO-IgG to study the role of the NF-κB signaling pathway in mediating the release of IL-6. First, we confirmed that the level of IL-6 was significantly higher in the sera of NMOSD patients than that of healthy people by humoral fluid analysis and that NMO-IgG can significantly induce the release of IL-6 from astrocytes by enzyme-linked immunosorbent assay (ELISA) and flow cytometry. Then, Western blotting and immunocytochemistry showed that NMO-IgG can activate the intracellular NF-κB signaling pathway. Finally, it was found that S3633, an inhibitor of the NF-κB signaling pathway, can effectively inhibit the increase in IL-6 levels. These results prove that the production of IL-6 is partly mediated by the NF-κB signaling pathway, providing a potential effective strategy for targeted treatment of NMOSD.

Analysis of CSF D-Dimer to Identify Intrathecal Fibrin-Driven Autoimmunity in Patients With Multiple Sclerosis

Background and Objectives

Proteins of the coagulation system contribute to autoimmune inflammation in patients with multiple sclerosis (MS). On blood-brain barrier (BBB) disruption, fibrinogen enters the CNS and is rapidly converted to fibrin, unfolding pleiotropic autoimmune mechanisms. Fibrin accumulation leads to subsequent proteolytic degradation that results in D-dimer generation. The primary objective of this study was to determine intrathecal levels of D-dimer in CSF as a measure of intrathecal coagulation cascade activation and to evaluate its diagnostic utility in patients with MS in contrast to healthy subjects. Key secondary objectives included analysis of CSF D-dimer in differential diagnoses of MS and its relation to routine clinical markers of disease activity.

Methods

Patients admitted for the assessment of suspected MS were prospectively recruited from October 2017 to December 2020. Blood plasma and citrated CSF samples were analyzed using a highly sensitive luminescent oxygen channeling immunoassay. Intrathecal generation of D-dimer was analyzed by adjusting for CSF/serum albumin (Q_alb) and CSF/plasma D-dimer quotients (Q_D-dimer), and corresponding CSF fibrinogen levels were determined. Final diagnoses after full evaluation and clinical data were recorded.

Results

Of 187 patients, 113 patients received a diagnosis of MS or clinically/radiologically isolated syndrome. We found increased intrathecal CSF D-dimer generation levels (Q_D-dimer/Q_alb-index) for patients with relapsing-remitting MS (RRMS; n = 71, median 4.7, interquartile range [IQR] 2.5–8.0) when compared with those for disease controls (n = 22, median 2.6, IQR 2.1–4.8, p = 0.031). Absolute CSF D-dimer values correlated with CSF fibrinogen levels (r = 0.463; p < 0 .001) and CSF leukocytes (r = 0.273; p = 0.003) and were elevated in MS patients with contrast enhancement (CE) compared with MS patients without CE on MRI (n = 48, median 6 ng/mL, and IQR 3–15.25 vs n = 41, median 4 ng/mL, and IQR 2–7; p = 0.026). Exploratory subgroup analyses indicated a correlation of intrathecal inflammatory activity and CSF D-dimer levels.

Discussion

D-dimer in CSF can be reliably determined and correlates with markers of CNS inflammation and CSF fibrinogen levels. Adjusted for BBB dysfunction, CSF D-dimer may allow the identification of intrathecal coagulation cascade activation in patients with MS.

Classification of Evidence

This study provides Class I evidence that CSF D-dimer levels are elevated in patients with RRMS.

Evolution of Anti-B Cell Therapeutics in Autoimmune Neurological Diseases

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

Early Initiation of Tocilizumab Treatment Against Moderate-to-Severe Myelitis in Neuromyelitis Optica Spectrum Disorder

Background

Interleukin-6 receptor blockade is effective in reducing the risk of relapses in neuromyelitis optica spectrum disorder (NMOSD). However, its efficacy during acute attacks of NMOSD remains elusive.

Objective

We investigated the effects of tocilizumab on disability during acute attacks, as well as its maintenance, in patients with moderate-to-severe myelitis.

Methods

Nineteen patients with NMOSD received tocilizumab treatment as add-on to high-dose methylprednisolone (HDMP) in acute myelitis and twenty-two patients who only received HDMP were compared. Disease disability was assessed using a multi-level scaling system that included the expanded disability status scale (EDSS), Hauser ambulation index (HAI), modified Rankin scale (mRS), pain numerical rating scale (NRS), functional assessment of chronic illness therapy-fatigue scale (FACIT-F), activity of daily living (ADL), EuroQol five-dimensions-three-level questionnaire (EQ-5D-3L), and sensory function score and bowel and bladder function score in Kurtzke functional systems scores (FSS).

Results

Improved EDSS, HAI, and mRS, as well as increased ADL and EQ-5D-3L were significant in patients on tocilizumab compared with those on steroids as monotherapy at 3 months (p < 0.05). Both groups of patients showed improved pain, fatigue, sensory function, and autonomic function at follow-ups, compared with baseline respectively. The changes in NRS, FACIT-F, and sensory and autonomic FSS showed no significant differences between the two groups. Tocilizumab significantly lowered the risk of relapses (HR = 0.21, 95% CI 0.06–0.76, p = 0.017) and reduced the annualized relapse rate compared with those by steroids (0.1 ± 0.2 vs 0.5 ± 0.6, p = 0.013).

Conclusion

Early initiation of tocilizumab provided a safe and effective add-on alternative during attacks, and its maintenance contributed to a significant reduction of relapse rate in NMOSD.

A Comprehensive Review on the Role of Genetic Factors in Neuromyelitis Optica Spectrum Disorder

Neuromyelitis optica spectrum disorders (NMOSD) comprise a variety of disorders being described by optic neuritis and myelitis. This disorder is mostly observed in sporadic form, yet 3% of cases are familial NMO. Different series of familial NMO cases have been reported up to now, with some of them being associated with certain HLA haplotypes. Assessment of HLA allele and haplotypes has also revealed association between some alleles within HLA-DRB1 or other loci and sporadic NMO. More recently, genome-wide SNP arrays have shown some susceptibility loci for NMO. In the current manuscript, we review available information about the role of genetic factors in NMO.

New BBB Model Reveals That IL-6 Blockade Suppressed the BBB Disorder, Preventing Onset of NMOSD

Background and Objectives

To evaluate the pathophysiology of neuromyelitis optica spectrum disorder (NMOSD) and the therapeutic mechanism and levels of interleukin-6 (IL-6) blockade (satralizumab), especially with respect to blood-brain barrier (BBB) disruption with the new in vitro and ex vivo human BBB models and in vivo model.

Methods

We constructed new static in vitro and flow-based ex vivo models for evaluating continued barrier function, leukocyte transmigration, and intracerebral transferability of neuromyelitis optica-immunoglobulin G (NMO-IgG) and satralizumab across the BBB using the newly established triple coculture system that are specialized to closely mimic endothelial cell contact of pericytes and endfeet of astrocytes. In the in vivo study, we assessed the effects of an anti–IL-6 receptor antibody for mice (MR16-1) on in vivo BBB disruption in mice with experimental autoimmune encephalomyelitis in which IL-6 concentration in the spinal cord dramatically increases.

Results

In vitro and ex vivo experiments demonstrated that NMO-IgG increased intracerebral transferability of satralizumab and NMO-IgG and that satralizumab suppressed the NMO-IgG–induced transmigration of T cells and barrier dysfunction. In the in vivo study, the blockade of IL-6 signaling suppressed the migration of T cells into the spinal cord and prevented the increased BBB permeability.

Discussion

These results suggest that (1) our triple-cultured in vitro and in ex vivo BBB models are ideal for evaluating barrier function, leukocyte transmigration, and intracerebral transferability; (2) NMO-IgG increased the intracerebral transferability of NMO-IgG via decreasing barrier function and induced secretion of IL-6 from astrocytes causing more dysfunction of the barrier and disrupting controlled cellular infiltration; and (3) satralizumab, which can pass through the BBB in the presence of NMO-IgG, suppresses the BBB dysfunction and the infiltration of inflammatory cells, leading to prevention of onset of NMOSD.

Cognitive Dysfunction after Heart Disease: A Manifestation of the Heart-Brain Axis

The functions of the brain and heart, which are the two main supporting organs of human life, are closely linked. Numerous studies have expounded the mechanisms of the brain-heart axis and its related clinical applications. However, the effect of heart disease on brain function, defined as the heart-brain axis, is less studied even though cognitive dysfunction after heart disease is one of its most frequently reported manifestations. Hypoperfusion caused by heart failure appears to be an important risk factor for cognitive decline. Blood perfusion, the immune response, and oxidative stress are the possible main mechanisms of cognitive dysfunction, indicating that the blood-brain barrier, glial cells, and amyloid-β may play active roles in these mechanisms. Clinicians should pay more attention to the cognitive function of patients with heart disease, especially those with heart failure. In addition, further research elucidating the associated mechanisms would help discover new therapeutic targets to intervene in the process of cognitive dysfunction after heart disease. This review discusses cognitive dysfunction in relation to heart disease and its potential mechanisms.

Therapeutic Response and Possible Biomarkers in Acute Attacks of Neuromyelitis Optica Spectrum Disorders: A Prospective Observational Study

Objective

To explore the outcomes of NMOSD attacks and investigate serum biomarkers for prognosis and severity.

Method

Patients with NMOSD attacks were prospectively and observationally enrolled from January 2019 to December 2020 at four hospitals in Guangzhou, southern China. Data were collected at attack, discharge and 1/3/6 months after acute treatment. Serum cytokine/chemokine and neurofilament light chain (NfL) levels were examined at the onset stage.

Results

One hundred patients with NMOSD attacks were included. The treatment comprised intravenous methylprednisolone pulse therapy alone (IVMP, 71%), IVMP combined with apheresis (8%), IVMP combined with intravenous immunoglobulin (18%) and other therapies (3%). EDSS scores decreased significantly from a medium of 4 (interquartile range 3.0–5.5) at attack to 3.5 (3.0–4.5) at discharge, 3.5 (2.0–4.0) at the 1-month visit and 3.0 (2.0–4.0) at the 3-month visit (p<0.01 in all comparisons). The remission rate was 38.0% at discharge and 63.3% at the 1-month visit. Notably, relapse occurred in 12.2% of 74 patients by the 6-month follow-up. Higher levels of T helper cell 2 (Th2)-related cytokines, including interleukin (IL)-4, IL-10, IL-13, and IL-1 receptor antagonist, predicted remission at the 1-month visit (OR=9.33, p=0.04). Serum NfL levels correlated positively with onset EDSS scores in acute-phase NMOSD (p<0.001, R² = 0.487).

Conclusions

Outcomes of NMOSD attacks were generally moderate. A high level of serum Th2-related cytokines predicted remission at the 1-month visit, and serum NfL may serve as a biomarker of disease severity at attack.

Clinical Trial Registration

https://clinicaltrials.gov/ct2/show/NCT04101058, identifier NCT04101058.

Persistently Gadolinium-Enhancing Lesion Is a Predictor of Poor Prognosis in NMOSD Attack: a Clinical Trial

Gadolinium (Gd)-contrast MRI for reliable detection of blood-brain barrier (BBB) breakdown is widely used in neuromyelitis optica spectrum disorder (NMOSD) attack. Nonetheless, little is known about the predictive role of gadolinium-enhancing lesion in prognosis of NMOSD attack. The aim of this work is to investigate the predictive value of persistently Gd-enhanced lesions to medium-term outcome after attack. Data for this analysis came from an ongoing prospective cohort study (CLUE). NMOSD patients with acute attack were enrolled from January 2019 to March 2020. All patients underwent Gd-contrast MRI at baseline and 1 month, and disability was assessed by Expanded Disability Status Scale (EDSS). Primary outcome was EDSS improvement from baseline to month 6. Multiple logistic regression identified predictors for poor recovery of NMOSD attack. Forty-one participants were analyzed, of which 21 patients had persistently Gd-enhancing lesions. Patients in no enhancement (NE) group showed a significant shift in 6-month EDSS distributions compared with those in persistent enhancement (PE) group (p = 0.005). Poor recovery rate of the PE group was higher than that of the NE group at 6 months (p = 0.033). In patients with aquaporin-4-positive, first-attack, transverse myelitis or in a high-dose steroid treatment subgroup, the improvement of EDSS scores in the PE group was still less compared with that in the NE group (p < 0.05). The presence of persistently Gd-enhancing lesion appears to be associated with poor recovery after attack (OR = 5.473, p = 0.014). Our study found that persistently gadolinium-enhancing lesion is a poor prognosis predictor after NMOSD attack. Trial registration ID: NCT04106830.

Targeting interleukin-6 to treat neuromyelitis optica spectrum disorders: Implications from immunology, the FcRn pathway and clinical experience

Neuromyelitis optica spectrum disorder (NMOSD) is a rare disease of the central nervous system (CNS) that is associated with poor outcomes for patients. Until recently, when complement inhibitors were approved, there was no approved therapy. Most recently, clinical trials of interleukin-6 (IL-6) blockade showed a therapeutic benefit for NMOSD. In this review, we introduce the immunological basis of IL-6 blockade in NMOSD and summarize current knowledge about the clinical use of the IL-6 receptor inhibitors tocilizumab and satralizumab. The aim of extending the half-life of monoclonal antibodies (mAbs) has been actualized by successful clinical translation for Satralizumab, achieved via the neonatal Fc receptor (FcRn) pathway. The basic principles of FcRn are highlighted in this review together with the potential therapeutic benefits of this emerging technology.

B Cells and Antibodies as Targets of Therapeutic Intervention in Neuromyelitis Optica Spectrum Disorders

The first description of neuromyelitis optica by Eugène Devic and Fernand Gault dates back to the 19th century, but only the discovery of aquaporin-4 autoantibodies in a major subset of affected patients in 2004 led to a fundamentally revised disease concept: Neuromyelits optica spectrum disorders (NMOSD) are now considered autoantibody-mediated autoimmune diseases, bringing the pivotal pathogenetic role of B cells and plasma cells into focus. Not long ago, there was no approved medication for this deleterious disease and off-label therapies were the only treatment options for affected patients. Within the last years, there has been a tremendous development of novel therapies with diverse treatment strategies: immunosuppression, B cell depletion, complement factor antagonism and interleukin-6 receptor blockage were shown to be effective and promising therapeutic interventions. This has led to the long-expected official approval of eculizumab in 2019 and inebilizumab in 2020. In this article, we review current pathogenetic concepts in NMOSD with a focus on the role of B cells and autoantibodies as major contributors to the propagation of these diseases. Lastly, by highlighting promising experimental and future treatment options, we aim to round up the current state of knowledge on the therapeutic arsenal in NMOSD.

Novel Neuroprotective Agents to Treat Neonatal Hypoxic-Ischemic Encephalopathy: Inter-Alpha Inhibitor Proteins

Perinatal hypoxia-ischemia (HI) is a major cause of brain injury and mortality in neonates. Hypoxic-ischemic encephalopathy (HIE) predisposes infants to long-term cognitive deficits that influence their quality of life and place a large burden on society. The only approved treatment to protect the brain after HI is therapeutic hypothermia, which has limited effectiveness, a narrow therapeutic time window, and is not considered safe for treatment of premature infants. Alternative or adjunctive therapies are needed to improve outcomes of full-term and premature infants after exposure to HI. Inter-alpha inhibitor proteins (IAIPs) are immunomodulatory molecules that are proposed to limit the progression of neonatal inflammatory conditions, such as sepsis. Inflammation exacerbates neonatal HIE and suggests that IAIPs could attenuate HI-related brain injury and improve cognitive outcomes associated with HIE. Recent studies have shown that intraperitoneal treatment with IAIPs can decrease neuronal and non-neuronal cell death, attenuate glial responses and leukocyte invasion, and provide long-term behavioral benefits in neonatal rat models of HI-related brain injury. The present review summarizes these findings and outlines the remaining experimental analyses necessary to determine the clinical applicability of this promising neuroprotective treatment for neonatal HI-related brain injury.

Satralizumab for the Treatment of Neuromyelitis Optica Spectrum Disorders

OBJECTIVE

To review the pharmacological characteristics, clinical evidence, and place in therapy of satralizumab for the treatment of neuromyelitis optica spectrum disorders (NMOSDs).

DATA SOURCES

A comprehensive literature search was conducted in PubMed (January 2000 to October 15, 2020). Key search terms included satralizumab and neuromyelitis optica spectrum disorders. Other sources were derived from product labeling and ClinicalTrials.gov.

STUDY SELECTION AND DATA EXTRACTION

All English-language articles identified from the data sources were reviewed and evaluated. Phase I, II, and III clinical trials were included.

DATA SYNTHESIS

NMOSD is an autoimmune disease characterized by inflammatory lesions in the optic nerves and spinal cord. Interleukin-6 is involved in the pathogenesis of the disorder. Satralizumab is a humanized monoclonal antibody targeting the interleukin-6 receptor. Phase III trials showed that protocol-defined relapse was 30% for satralizumab and 50% for placebo (P = 0.018) when patients with NMOSD were treated with satralizumab monotherapy; protocol-defined relapse was 20% for satralizumab and 43% for placebo (P = 0.02) when satralizumab was added to immunosuppressant treatment. Satralizumab is generally well tolerated, with common adverse effects including injection-related reaction.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

Satralizumab has the potential to become a valuable treatment option for patients with NMOSD.

CONCLUSION

Satralizumab appears to be safe and effective as monotherapy or in combination with an immunosuppressant for patients with NMOSD and has the potential to become a valuable treatment option for these patients.

Burns Impair Blood-Brain Barrier and Mesenchymal Stem Cells Can Reverse the Process in Mice

Neurological syndromes are observed in numerous patients who suffer burns, which add to the economic burden of societies and families. Recent studies have implied that blood-brain barrier (BBB) dysfunction is the key factor that induces these central nervous system (CNS) syndromes in peripheral traumatic disease, e.g., surgery and burns. However, the effect of burns on BBB and the underlying mechanism remains, largely, to be determined. The present study aimed to investigate the effect of burns on BBB and the potential of umbilical cord-derived mesenchymal stem cells (UC-MSCs), which have strong anti-inflammatory and repairing ability, to protect the integrity of BBB. BBB permeability was evaluated using dextran tracer (immunohistochemistry imaging and spectrophotometric quantification) and western blot, interleukin (IL)-6, and IL-1β levels in blood and brain were measured by enzyme-linked immunosorbent assay. Furthermore, transmission electron microscopy (TEM) was used to detect transcellular vesicular transport (transcytosis) in BBB. We found that burns increased mouse BBB permeability to both 10-kDa and 70-kDa dextran. IL-6 and IL-1β levels increased in peripheral blood and CNS after burns. In addition, burns decreased the level of tight junction proteins (TJs), including claudin-5, occludin, and ZO-1, which indicated increased BBB permeability due to paracellular pathway. Moreover, increased vesicular density after burns suggested increased transcytosis in brain microvascular endothelial cells. Finally, administering UC-MSCs at 1 h after burns effectively reversed these adverse effects and protected the integrity of BBB. These results suggest that burns increase BBB permeability through both paracellular pathway and transcytosis, the potential mechanism of which might be through increasing IL-6 and IL-1β levels and decreasing Mfsd2a level, and appropriate treatment with UC-MSCs can reverse these effects and protect the integrity of BBB after burns.

Quantitative proteomics of cerebrospinal fluid using tandem mass tags in dogs with recurrent epileptic seizures

This prospective study included four dog groups (group A: healthy dogs, groups B: dogs with idiopathic epilepsy under antiepileptic medication (AEM), C: idiopathic epilepsy dogs without AEM administration, D: dogs with structural epilepsy). The purpose of the study was to compare the proteomic profile among the four groups. Samples were analyzed by a quantitative Tandem Mass Tags approach using a Q-Exactive-Plus mass-spectrometer. Identification and relative quantification were performed using Proteome Discoverer, and data were analyzed using R. Gene ontology terms were analyzed based on Canis lupus familiaris database. Data are available via ProteomeXchange with identifier PXD018893. Eighteen proteins were statistically significant among the four groups (P < 0.05). MMP2 and EFEMP2 appeared down-regulated whereas HP and APO-A1 were up-regulated (groups B, D). CLEC3B and PEBP4 were up-regulated whereas APO-A1 was down-regulated (group C). IGLL1 was down-regulated (groups B, C) and up-regulated (group D). EFEMP2 was the only protein detected among the four groups and PEBP4 was significantly different among the epileptic dogs. Western blot and SPARCL immunoassay were used to quantify HP abundance change, validating proteomic analysis. Both, showed good correlation with HP levels identified through proteomic analysis (r = 0.712 and r = 0.703, respectively). SIGNIFICANCE: The proteomic analysis from CSF of dogs with epileptic seizures could reflect that MMP2, HP and APO-A1 may contribute to a blood-brain barrier disruption through the seizure-induced inflammatory process in the brain. MMP2 change may indicate the activation of protective mechanisms within the brain tissue. Antiepileptic medication could influence several cellular responses and alter the CSF proteome composition.

Metabolomic Profiling in Neuromyelitis Optica Spectrum Disorder Biomarker Discovery

There is no specific test for diagnosing neuromyelitis optica spectrum disorder (NMOSD), a disabling autoimmune disease of the central nervous system. Instead, diagnosis relies on ruling out other related disorders with overlapping clinical symptoms. An urgency for NMOSD biomarker discovery is underscored by adverse responses to treatment following misdiagnosis and poor prognosis following the delayed onset of treatment. Pathogenic autoantibiotics that target the water channel aquaporin-4 (AQP4) and myelin oligodendrocyte glycoprotein (MOG) contribute to NMOSD pathology. The importance of early diagnosis between AQP4-Ab⁺ NMOSD, MOG-Ab⁺ NMOSD, AQP4-Ab⁻ MOG-Ab⁻ NMOSD, and related disorders cannot be overemphasized. Here, we provide a comprehensive data collection and analysis of the currently known metabolomic perturbations and related proteomic outcomes of NMOSD. We highlight short chain fatty acids, lipoproteins, amino acids, and lactate as candidate diagnostic biomarkers. Although the application of metabolomic profiling to individual NMOSD patient care shows promise, more research is needed.

Interleukin-6 in neuromyelitis optica spectrum disorder pathophysiology

Neuromyelitis optica spectrum disorder (NMOSD) is a rare autoimmune disorder that preferentially affects the spinal cord and optic nerve. Most patients with NMOSD experience severe relapses that lead to permanent neurologic disability; therefore, limiting frequency and severity of these attacks is the primary goal of disease management. Currently, patients are treated with immunosuppressants. Interleukin-6 (IL-6) is a pleiotropic cytokine that is significantly elevated in the serum and the CSF of patients with NMOSD. IL-6 may have multiple roles in NMOSD pathophysiology by promoting plasmablast survival, stimulating the production of antibodies against aquaporin-4, disrupting blood-brain barrier integrity and functionality, and enhancing proinflammatory T-lymphocyte differentiation and activation. Case series have shown decreased relapse rates following IL-6 receptor (IL-6R) blockade in patients with NMOSD, and 2 recent phase 3 randomized controlled trials confirmed that IL-6R inhibition reduces the risk of relapses in NMOSD. As such, inhibition of IL-6 activity represents a promising emerging therapy for the management of NMOSD manifestations. In this review, we summarize the role of IL-6 in the context of NMOSD.

Differential Effects of MS Therapeutics on B Cells-Implications for Their Use and Failure in AQP4-Positive NMOSD Patients

B cells are considered major contributors to multiple sclerosis (MS) pathophysiology. While lately approved disease-modifying drugs like ocrelizumab deplete B cells directly, most MS medications were not primarily designed to target B cells. Here, we review the current understanding how approved MS medications affect peripheral B lymphocytes in humans. These highly contrasting effects are of substantial importance when considering these drugs as therapy for neuromyelitis optica spectrum disorders (NMOSD), a frequent differential diagnosis to MS, which is considered being a primarily B cell- and antibody-driven diseases. Data indicates that MS medications, which deplete B cells or induce an anti-inflammatory phenotype of the remaining ones, were effective and safe in aquaporin-4 antibody positive NMOSD. In contrast, drugs such as natalizumab and interferon-β, which lead to activation and accumulation of B cells in the peripheral blood, lack efficacy or even induce catastrophic disease activity in NMOSD. Hence, we conclude that the differential effect of MS drugs on B cells is one potential parameter determining the therapeutic efficacy or failure in antibody-dependent diseases like seropositive NMOSD.

Correlation between serum levels of endothelin-1 and disease severity in patients with neuromyelitis optica spectrum disorders

AIMS

Neuromyelitis optica spectrum disorders (NMOSD) are aquaporin-4 antibody-mediated diseases of the central nervous system. Endothelin-1 (ET-1) is an inflammatory cytokine released by vascular endothelial cells and activated astrocytes. Previous studies have reported the aberrant expressions of cytokines/chemokines in patients diagnosed with NMOSD. However, the serum levels of ET-1 in NMOSD patients remain unknown. The purpose of this study was to measure the serum levels of ET-1 and other immune-related cytokines/chemokines in patients with NMOSD, and to investigate the correlation between serum ET-1 levels and clinical characteristics of NMOSD.

METHODS

Thirty-eight patients with NMOSD and twenty-eight healthy controls (HCs) were recruited in this study. The serum concentrations of ET-1 and other cytokines/chemokines were measured, and their correlations to the clinical features of patients with NMOSD were analyzed.

RESULTS

The serum levels of ET-1 in patients with NMOSD were significantly higher than those in HCs (P =  0.0001). The serum concentrations of ET-1 were positively correlated with the Expanded Disability Status Scale score (r = 0.428, P = 0.0183). High-dose intravenous methylprednisolone treatment significantly reduced the levels of ET-1 and interleukin (IL)-6 in blood, but significantly increased the serum concentrations of IL-10 in NMOSD patients. No correlations were found between serum ET-1 levels and the concentrations of other cytokines/chemokines in these patients.

CONCLUSION

ET-1 and IL-6 might exert pro-inflammatory effects in the pathogenesis of NMOSD, whereas IL-10 played an anti-inflammatory role in this process. ET-1 might be a potential biomarker for predicting the severity of NMOSD. However, the serum levels of ET-1 were not correlated with the changes of other cytokines/chemokines in patients with NMOSD. The involvement of ET-1 in the development of NMOSD needs to be further studied.

Peroxisome Proliferator-Activated Receptor γ Agonist Rosiglitazone Protects Blood-Brain Barrier Integrity Following Diffuse Axonal Injury by Decreasing the Levels of Inflammatory Mediators Through a Caveolin-1-Dependent Pathway

Our early experiments confirmed that rosiglitazone (RSG), a peroxisome proliferator-activated receptor γ (PPARγ) agonist, had therapeutic potential for the treatment of diffuse axonal injury (DAI) by inhibiting the expression of amyloid-beta precursor protein and reducing the loss and abnormal phosphorylation of tau, but the underlying mechanisms were not fully defined. In this study, we aimed to investigate a possible role for PPARγ in the protection of blood-brain barrier (BBB) integrity in a rat model of DAI, and the underlying mechanisms. PPAR agonists and antagonists were intraperitoneally injected after DAI. Treatment with RSG ameliorated axonal injury, cell apoptosis, glia activation, and the release of inflammatory factors such as TNF-α, IL-1β, and IL-6. It also increased the expression of tight junction-associated proteins like ZO-1, claudin-5, and occludin-1, whereas the PPARγ antagonist GW9662 had the opposite effects. These effects were also studied in a BBB in vitro model, consisting of a monolayer of human microvascular endothelial cells (HBMECs) subjected to oxygen and glucose deprivation (OGD). Treatment with RSG ameliorated the loss of BBB integrity and the increased permeability induced by OGD by reducing the release of inflammatory factors and maintaining the expression of tight junction-associated proteins. Interestingly, caveolin-1 was found located mainly in endothelial cells, and RSG increased the expression of caveolin-1, which decreased following OGD. In contrast, caveolin-1 siRNA abrogated the protective effects of RSG in the in vitro BBB model. In conclusion, we provide evidence that PPARγ plays an important role in a series of processes associated with DAI, and that the PPARγ agonist RSG can protect BBB integrity by decreasing the levels of inflammatory mediators through a caveolin-1-dependent pathway.

Proportions of Th17 cells and Th17-related cytokines in neuromyelitis optica spectrum disorders patients: A meta-analysis

BACKGROUND

T helper (Th17) cells play an important role in many autoimmune diseases. In this meta-analysis, we aimed to specify the proportion of Th17 cells and the levels of Th17-related cytokines in neuromyelitis optica spectrum disorders (NMOSD) patients, we did this meta-analysis.

METHODS

Using previously reported data from PubMed, EMBASE, and Web of Science and Cochrane, we explored the proportion of Th17 cells in CD4⁺ T cells in peripheral blood (PB) and the level of Th17-related cytokines, such as interleukin (IL)1β, IL6, IL17, IL21, IL22, IL23 and transforming growth factor -beta (TGFβ), in cerebrospinal fluid (CSF), plasma, and serum in NMOSD patients compared to control group and multiple sclerosis (MS) patients.

RESULTS

In total, 38 trials were included for our analysis. Results showed that the proportion of Th17 cells was higher in NMOSD patients than in the control and MS groups. The levels of IL1β, IL6, IL17 and IL21 in CSF and plasma, and IL6, IL21, IL22, and IL23 in the serum were higher in NMOSD patients than in the control group. The levels of IL6 in CSF and serum and IL17 in plasma and serum were higher in NMOSD patients than in MS patients.

CONCLUSION

The proportion of Th17 cells and the levels of Th17-related cytokines was increased in NMOSD patients compared with the control group and MS patients. The results of this meta-analysis indicated that Th17 cells and Th17-associated cytokines may play an essential role in the pathogenesis of NMOSD. PROSPERO registration: CRD42019128785.

Pharmacotherapy for Neuromyelitis Optica Spectrum Disorders: Current Management and Future Options

Neuromyelitis optica (NMO) is an inflammatory and demyelinating disease of the central nervous system. Although the prevalence of NMO is low, the rapid and severe impairment observed in patients has led to extensive development of research in the fields of diagnostic criteria and therapy in the past 15 years. With improved understanding of the pathophysiology of NMO and the role of aquaporin-4 (AQP4) or myelin oligodendrocyte glycoprotein antibodies, numerous therapeutic approaches have been proposed and are currently undergoing evaluation. In this review, we describe the rationale for existing therapeutics and their benefit/risk ratio. We also discuss the pharmacological and clinical interest of future approaches targeting, among others, B or T cells, the blood-central nervous system barrier, complement, polynuclear cells, AQP4-antibody linkage and AQP4 activity. The numerous agents under development are the result of a major collaborative effort all over the world. After the considerable progress on diagnosis, we are now close to class I evidence for a therapeutic effect of several drugs in NMO spectrum disorders, most notably with the anti-interleukin-6 receptor antibody (satralizumab) and anti-complement-5 antibody (eculizumab).

Simulating the Impact of Elevated Levels of Interleukin-6 on the Pharmacokinetics of Various CYP450 Substrates in Patients with Neuromyelitis Optica or Neuromyelitis Optica Spectrum Disorders in Different Ethnic Populations

A physiologically based pharmacokinetic (PBPK) model was used to simulate the impact of elevated levels of interleukin (IL)-6 on the exposure of several orally administered cytochrome P450 (CYP) probe substrates (caffeine, S-warfarin, omeprazole, dextromethorphan, midazolam, and simvastatin). The changes in exposure of these substrates in subjects with rheumatoid arthritis (and hence elevated IL-6 levels) compared with healthy subjects were predicted with a reasonable degree of accuracy. The PBPK model was then used to simulate the change in oral exposure of the probe substrates in North European Caucasian, Chinese, and Japanese population of patients with neuromyelitis optica (NMO) or NMO spectrum disorder with elevated plasma IL-6 levels (up to 100 pg/mL). Moderate interactions [mean AUC fold change, ≤ 2.08 (midazolam) or 2.36 (simvastatin)] was predicted for CYP3A4 probe substrates and weak interactions (mean AUC fold change, ≤ 1.29-1.97) were predicted for CYP2C19, CYP2C9, and CYP2D6 substrates. No notable interaction was predicted with CYP1A2. Although ethnic differences led to differences in simulated exposure for some of the probe substrates, there were no marked differences in the predicted magnitude of the change in exposure following IL-6-mediated suppression of CYPs. Decreased levels of serum albumin (as reported in NMO patients) had little impact on the magnitude of the simulated IL-6-mediated drug interactions. This PBPK modeling approach allowed us to leverage knowledge from different disease and ethnic populations to make predictions of cytokine-related DDIs in a rare disease population where actual clinical studies would otherwise be difficult to conduct.

Mechanisms of Blood-Brain Barrier Disruption in Herpes Simplex Encephalitis

Herpes simplex encephalitis (HSE) is often caused by infection with herpes simplex virus 1 (HSV-1), a neurotropic double-stranded DNA virus. HSE infection always impacts the temporal and frontal lobes or limbic system, leading to edema, hemorrhage, and necrotic changes in the brain parenchyma. Additionally, patients often exhibit severe complications following antiviral treatment, including dementia and epilepsy. HSE is further associated with disruptions to the blood-brain barrier (BBB), which consists of microvascular endothelial cells, tight junctions, astrocytes, pericytes, and basement membranes. Following an HSV-1 infection, changes in BBB integrity and permeability can result in increased movement of viruses, immune cells, and/or cytokines into the brain parenchyma. This leads to an enhanced inflammatory response in the central nervous system and further damage to the brain. Thus, it is important to protect the BBB from pathogens to reduce brain damage from HSE. Here, we discuss HSE and the normal structure and function of the BBB. We also discuss growing evidence indicating an association between BBB breakdown and the pathogenesis of HSE, as well as future research directions and potential new therapeutic targets. Graphical Abstract During herpes simplex encephalitis, the functions and structures of each composition of BBB have been altered by different factors, thus the permeability and integrity of BBB have been broken. The review aim to explore the potential mechanisms and factors in the process, probe the next research targets and new therapeutic targets.

Disruption of blood-brain barrier integrity associated with brain lesions in Chinese neuromyelitis optica spectrum disorder patients

OBJECTIVE

The aims of this study were to report brain characteristic abnormalities and to evaluate the relationship of blood-brain barrier (BBB) disruption and brain lesions in Chinese patients with NMOSD.

METHODS

Brain magnetic resonance imaging characteristics and cerebrospinal fluid (CSF) laboratory tests of 121 patients with NMOSD at acute attack were reviewed retrospectively. Qalb (CSF albumin/serum albumin) was used for assessment of disruption of BBB.

RESULTS

Brain MRI abnormalities were observed in 36.4% (44/121) of the NMOSD patients. Thirty patients (25%) showed typical-NMOSD abnormalities, including dorsal medulla lesions (n = 16, 13.2%), brainstem/cerebellum (n = 11, 9.1%), thalamus/hypothalamus (n = 3, 2.5%), periventricular white matter lesions (n = 4, 3.3%) hemispheric white matter (n = 4, 3.3%). Twenty-five patients (20.7%) had nonspecific lesions. Compared to the NMOSD patients without brain lesion, the proportion of patients who had abnormal BBB permeability was significantly higher in the abnormal brain MRI group (47.7% vs. 27.3%, P < 0.05). BBB permeability was not correlated to distribution of brain lesions or enhancement lesions. Qalb was associated with higher Expanded Disability Status Scale scores (r = 0.689, P < 0.05).

CONCLUSIONS

Brain lesions are common in NMOSD patients. Marker of BBB permeability is associated with brain lesion and EDSS scores of NMOSD.

Blood-Brain Barrier Disruption Induced Cognitive Impairment Is Associated With Increase of Inflammatory Cytokine

Patients with diabetes suffer the higher risk of dementia and the underlying pathological mechanism of cognitive dysfunction in diabetes is not fully understood. In this study, we explore whether the cognitive impairment in the diabetic rat is associated with increased blood brain barrier (BBB) permeability and the change of the inflammatory cytokine. Experimental diabetic rats were induced by single intraperitoneal injection of streptozotocin (STZ). Cognitive function was evaluated by Morris water maze in the normal and the diabetic rats, respectively. The spatial acquisition trials were conducted over five consecutive days and the probe test was performed on day 6, followed by working memory test on the next 4 days. Escape latency was recorded in the acquisition trials and working memory test; time spent in the target quadrant and the number of crossing the former platform were recorded in the probe test. BBB permeability was assessed by measuring the extravasation of IgG. The image of occludin and claudin-5 staining by a confocal microscope were acquired to measure the gap in the tight junction. Cytokines TNF-α, IL-1β and IL-6 mRNA expression were further examined by Real-time PCR. The time spent in the target quadrant within 30 s decreased in the 8-week STZ rats compared to that of the normal rats (p < 0.05), while no difference was seen in the performance of working memory between the diabetic and normal rats. IgG leakage significantly increased in the brain parenchyma of the 8-week STZ rats compared to the normal rats (p < 0.05). The immunostaining of occludin and claudin-5 suggested the gap in the tight junction increased in the 8-week STZ rats compared to the normal rats (p < 0.05). Moreover, TNF-α and IL-6 mRNA also increased in the brain of 8-week STZ rats compared to the normal rats (p < 0.05). These results suggested that loss of BBB integrity might contribute to progressive impairment of cognitive in the diabetic rats. The increase of TNF-α and IL-6 expression might trigger the disruption of BBB in the brain, which eventually caused cognitive impairment in the 8-week STZ rats.

Recombinant rabies virus expressing interleukin-6 enhances the immune response in mouse brain

Rabies, which is caused by the rabies virus (RABV), is an ancient zoonosis that has a high mortality rate. Previous studies have indicated that recombinant RABV expressing canine interleukin-6 (rHEP-CaIL6), induced more virus-neutralizing antibodies than parental RABV in mice following intramuscular immunization. To investigate the immune response induced in the CNS by rHEP-CaIL6 after intranasal or intracranial administration in mice, the permeability of the blood-brain barrier (BBB), the infiltration of CD3 T cells, and innate immune response-related effector molecules in the CNS were examined. It was observed that infection of rHEP-CaIL6 led to enhanced BBB permeability following intranasal infection. More CD3 T cells infiltrated into the central nervous system (CNS) in mice infected with rHEP-CaIL6 than in those infected with the HEP-Flury strain. Furthermore, rHEP-CaIL6 induced an increased expression of innate immune response-related effector molecules, compared with the parental HEP-Flury strain, within the CNS. Taken together, these findings suggest that rHEP-CaIL6 induced stronger immune responses in mice brains, which is more beneficial for virus clearance. These results may also partly illustrate the role of IL6 in RABV infection.

Recombinant thrombomodulin ameliorates experimental autoimmune encephalomyelitis by suppressing high mobility group box 1 and inflammatory cytokines

Recombinant thrombomodulin (rTM) has pleiotrophic properties, including anti-coagulation and anti-inflammation; however, its effectiveness as a treatment for multiple sclerosis (MS) has not been evaluated fully. High mobility group box 1 (HMGB1) and proinflammatory cytokines, working as inflammatory mediators, are reportedly involved in the inflammatory pathogenesis of MS. The aim of this study was to determine whether rTM can be a potential therapeutic agent for experimental autoimmune encephalomyelitis (EAE). EAE mice received rTM treatment (1 mg or 0·1 mg/kg/day) from days 11 to 15 after immunization. The clinical variables, plasma levels of inflammatory cytokines and HMGB1 and pathological findings in EAE were evaluated. rTM administration ameliorated the clinical and pathological severity of EAE. An immunohistochemical study of the spinal cord showed weaker cytoplasmic HMGB1 staining in the rTM-treated EAE mice than in the untreated EAE mice. Plasma levels of inflammatory cytokines and HMGB1 were suppressed by rTM treatment. In conclusion, rTM down-regulated inflammatory mediators in the peripheral circulation and prevented HMGB1 release from nuclei in the central nervous system, suppressing EAE-related inflammation. rTM could have a novel therapeutic potential for patients with MS.

TRPM2 Channel Aggravates CNS Inflammation and Cognitive Impairment via Activation of Microglia in Chronic Cerebral Hypoperfusion

Chronic cerebral hypoperfusion is a characteristic seen in widespread CNS diseases, including neurodegenerative and mental disorders, and is commonly accompanied by cognitive impairment. Recently, several studies demonstrated that chronic cerebral hypoperfusion can induce the excessive inflammatory responses that precede neuronal dysfunction; however, the precise mechanism of cognitive impairment due to chronic cerebral hypoperfusion remains unknown. Transient receptor potential melastatin 2 (TRPM2) is a Ca²⁺-permeable channel that is abundantly expressed in immune cells and is involved in aggravation of inflammatory responses. Therefore, we investigated the pathophysiological role of TRPM2 in a mouse chronic cerebral hypoperfusion model with bilateral common carotid artery stenosis (BCAS). When male mice were subjected to BCAS, cognitive dysfunction and white matter injury at day 28 were significantly improved in TRPM2 knock-out (TRPM2-KO) mice compared with wild-type (WT) mice, whereas hippocampal damage was not observed. There were no differences in blood-brain barrier breakdown and H₂O₂ production between the two genotypes at 14 and 28 d after BCAS. Cytokine production was significantly suppressed in BCAS-operated TRPM2-KO mice compared with WT mice at day 28. In addition, the number of Iba1-positive cells gradually decreased from day 14. Moreover, daily treatment with minocycline significantly improved cognitive perturbation. Surgical techniques using bone marrow chimeric mice revealed that activated Iba1-positive cells in white matter could be brain-resident microglia, not peripheral macrophages. Together, these findings suggest that microglia contribute to the aggravation of cognitive impairment by chronic cerebral hypoperfusion, and that TRPM2 may be a potential target for chronic cerebral hypoperfusion-related disorders.SIGNIFICANCE STATEMENT Chronic cerebral hypoperfusion is manifested in a wide variety of CNS diseases, including neurodegenerative and mental disorders that are accompanied by cognitive impairment; however, the underlying mechanisms require clarification. Here, we used a chronic cerebral hypoperfusion mouse model to investigate whether TRPM2, a Ca²⁺-permeable cation channel highly expressed in immune cells, plays a destructive role in the development of chronic cerebral hypoperfusion-induced cognitive impairment, and propose a new hypothesis in which TRPM2-mediated activation of microglia, not macrophages, specifically contributes to the pathology through the aggravation of inflammatory responses. These findings shed light on the understanding of the mechanisms of chronic cerebral hypoperfusion-related inflammation, and are expected to provide a novel therapeutic molecule for cognitive impairment in CNS diseases.

Profiling of metalloprotease activities in cerebrospinal fluids of patients with neoplastic meningitis

Background

Neoplastic invasion into leptomeninges and subarachnoid space, resulting in neoplastic meningitis (NM) is a fatal complication of advanced solid and hematological neoplasms. Identification of malignant involvement of the cerebrospinal fluid (CSF) early in the disease course has crucial prognostic and therapeutic implications, but remains challenging. As indicators of extracellular matrix (ECM) degradation and breakdown of the blood–brain-barrier, Matrix Metalloproteases (MMPs) and A Disintegrin and Metalloproteases (ADAMs) are potential analytes for cerebral pathophysiology and metastatic dissemination of tumor cells into the CSF.

Methods

We compared protease activities in CSF samples from patients with NM and control individuals using FRET-based metalloprotease substrates with distinct enzyme selectivity profiles in a real-time, multiplex approach termed “proteolytic activity matrix assay” (PrAMA). Protease activity dynamics can be tracked by fluorescence changes over time. By simultaneously monitoring a panel of 5 FRET-substrate cleavages, a proteolytic signature can be identified and analyzed to infer the activities of multiple specific proteases. Distinct patterns of substrate cleavage comparing disease vs. control samples allow rapid, reproducible and sensitive discrimination even in small volumes of CSF.

Results

Individual substrate cleavage rates were linked to distinct proteases, and PrAMA computational inference implied increased activities of MMP-9, ADAM8 and ADAM17 (4–5-fold on average) in CSF samples from NM patients that were inhibitable by the metalloprotease inhibitor batimastat (BB-94). The activities of these proteases correlated with blood–brain barrier impairment. Notably, CSF cell counts were not found to directly reflect the protease activities observed in CSF samples from NM patients; this may explain the frequent clinical observation of negative cytology in NM patients.

Conclusion

PrAMA analysis of CSF samples is a potential diagnostic method for sensitive detection of NM and may be suitable for the clinical routine.

Electronic supplementary material

The online version of this article (doi:10.1186/s12987-017-0070-5) contains supplementary material, which is available to authorized users.