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

NMOSD and MOGAD: an evolving disease spectrum

Neuromyelitis optica (NMO) spectrum disorder (NMOSD) is a relapsing inflammatory disease of the CNS, characterized by the presence of serum aquaporin 4 (AQP4) autoantibodies (AQP4-IgGs) and core clinical manifestations such as optic neuritis, myelitis, and brain or brainstem syndromes. Some people exhibit clinical characteristics of NMOSD but test negative for AQP4-IgG, and a subset of these individuals are now recognized to have serum autoantibodies against myelin oligodendrocyte glycoprotein (MOG) - a condition termed MOG antibody-associated disease (MOGAD). Therefore, the concept of NMOSD is changing, with a disease spectrum emerging that includes AQP4-IgG-seropositive NMOSD, MOGAD and double-seronegative NMOSD. MOGAD shares features with NMOSD, including optic neuritis and myelitis, but has distinct pathophysiology, clinical profiles, neuroimaging findings (including acute disseminated encephalomyelitis and/or cortical encephalitis) and biomarkers. AQP4-IgG-seronegative NMOSD seems to be a heterogeneous condition and requires further study. MOGAD can manifest as either a monophasic or a relapsing disease, whereas NMOSD is usually relapsing. This Review summarizes the history and current concepts of NMOSD and MOGAD, comparing epidemiology, clinical features, neuroimaging, pathology and immunology. In addition, we discuss new monoclonal antibody therapies for AQP4-IgG-seropositive NMOSD that target complement, B cells or IL-6 receptors, which might be applied to MOGAD in the near future.

CCL4 as a potential serum factor in differential diagnosis of central nervous system inflammatory diseases and gliomas

Computed tomography (CT) scans and magnetic resonance imaging (MRI) are commonly utilized to detect brain gliomas and central nervous system inflammation diseases. However, there are instances where depending solely on medical imaging for a precise diagnosis may result in unsuitable medications or treatments. Pathological analysis is regarded as the definitive method for diagnosing brain gliomas or central nervous system inflammation diseases. To achieve this, a craniotomy or stereotaxic biopsy is necessary to collect brain tissue, which can lead to complications such as cerebral hemorrhage, neurological deficits, cerebrospinal fluid leaks, and cerebral edema. Consequently, the advancement of non-invasive or minimally invasive diagnostic techniques is currently a high priority. This study included samples from four glioma patients and five patients with central nervous system inflammatory diseases, comprising both serum and paired cerebrospinal fluid (CSF). A total of 40 human cytokines were identified in these samples. We utilized a receiver operating characteristic (ROC) analysis to assess the sensitivity and specificity for distinguishing central nervous system inflammation diseases and gliomas. Additionally, we examined the correlation of these factors between serum and CSF in the patients. Ultimately, the identified factors were validated using serum from patients with clinically confirmed gliomas and central nervous system inflammation diseases followed by detection and statistical analysis through ELISA. The levels of serum factors IL-4, IFN-α, IFN-γ, IL-6, TNF-α, CCL4, CCL11, and VEGF were found to be significantly higher in gliomas compared with inflammatory diseases of the central nervous system (p < 0.05). Furthermore, a strong correlation was observed between the levels of CCL4 in serum and CSF, with a correlation coefficient of r = 0.92 (95% CI = 0.20-0.99, p = 0.027). We gathered more clinical samples to provide further validation of the abundance of CCL4 expression. A clinical study analyzing serum samples from 19 glioma patients and 22 patients with central nervous system inflammation diseases revealed that CCL4 levels were notably elevated in the inflammatory group compared with the glioma group (p < 0.001). These results suggest that assessing serum CCL4 levels may be useful in distinguishing those patients for clinical diagnostic purposes.

Lycium barbarum glycopeptide ameliorates motor and visual deficits in autoimmune inflammatory diseases

BACKGROUND

Lycium barbarum glycopeptide (LbGp), extracted from the traditional Chinese medicine (TCM) of Lycium barbarum (LB), provides a neuroprotective effect against neurodegenerative and neuroimmune disorders contributing to its immunomodulatory and anti-inflammatory roles. Neuromyelitis optica spectrum disorders (NMOSD) is an autoimmune-mediated central nervous system (CNS) demyelinating disease, clinically manifested as transverse myelitis (TM) and optic neuritis. However, no drug has been demonstrated to be effective in relieving limb weakness and visual impairment of NMOSD patients.

PURPOSE

This study investigates the potential role of LbGp in ameliorating pathologic lesions and improving neurological dysfunction during NMOSD progression, and to elucidate the underlying mechanisms for the first time.

STUDY DESIGN

We administrate LbGp in experimental NMOSD models in ex vivo and in vivo to explore its effect on NMOSD.

METHODS

To evaluate motor function, both rotarod and gait tasks were performed in systemic NMOSD mice models. Furthermore, we assessed the severity of NMO-like lesions of astrocytes, organotypic cerebellar slices, as well as brain, spinal cord and optic nerve sections from NMOSD mouse models with LbGp treatment by immunofluorescent staining. In addition, demyelination levels in optic nerve were measured by G-ratio through Electro-microscopy (EM). And inflammation response was explored through detecting the protein levels of proinflammatory cytokines and NF-κB signaling in astrocytic culture medium and spinal cord homogenates respectively by Elisa and by Western blotting.

RESULTS

LbGp could significantly reduce astrocytes injury, demyelination, and microglial activation in NMOSD models. In addition, LbGp also improved locomotor and visual dysfunction through preventing neuron and retinal ganglion cells (RGCs) from inflammatory attack in a systemic mouse model. Mechanistically, LbGp inhibits proinflammatory factors release via inhibition of NF-κB signaling in NMOSD models.

CONCLUSION

This study provides evidence to develop LbGp as a functional TCM for the clinical treatment of NMOSD.

hUC-MSCs-derived MFGE8 ameliorates locomotor dysfunction via inhibition of ITGB3/ NF-κB signaling in an NMO mouse model

Neuromyelitis optica (NMO) is a severe autoimmune inflammatory disease of the central nervous system that affects motor function and causes relapsing disability. Human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) have been used extensively in the treatment of various inflammatory diseases, due to their potent regulatory roles that can mitigate inflammation and repair damaged tissues. However, their use in NMO is currently limited, and the mechanism underlying the beneficial effects of hUC-MSCs on motor function in NMO remains unclear. In this study, we investigate the effects of hUC-MSCs on the recovery of motor function in an NMO systemic model. Our findings demonstrate that milk fat globule epidermal growth 8 (MFGE8), a key functional factor secreted by hUC-MSCs, plays a critical role in ameliorating motor impairments. We also elucidate that the MFGE8/Integrin αvβ3/NF-κB signaling pathway is partially responsible for structural and functional recovery, in addition to motor functional enhancements induced by hUC-MSC exposure. Taken together, these findings strongly support the involvement of MFGE8 in mediating hUC-MSCs-induced improvements in motor functional recovery in an NMO mouse model. In addition, this provides new insight on the therapeutic potential of hUC-MSCs and the mechanisms underlying their beneficial effects in NMO.

Tocilizumab treatment in neuromyelitis optica spectrum disorders: Updated meta-analysis of efficacy and safety

This systematic review and meta-analysis summarize the efficacy and safety of Tocilizumab (TCZ) in treating NMOSD and investigates the factors that affect its efficacy. TCZ is the first monoclonal antibody against the IL-6 receptor for treating NMOSD, and its efficacy and safety vary in different studies. We collected English-language research literature until January 1, 2023, by searching databases such as PubMed, MEDLINE, Embase, Cochrane Library, and clinicaltrials.gov, and identified 9 studies involving 153 patients (139 female and 14 male) that met our inclusion criteria. In these studies, the average ARR ratio and EDSS score reduction values in the TCZ treatment group were -1.34 (95 % CI, -1.60 to -1.09) and -0.81 (95 % CI, -1.04 to -0.58), respectively. Based on the data we have collected, compared to the AQP4-IgG negative NMOSD patients, TCZ demonstrates a more pronounced effectiveness in AQP4-IgG positive NMOSD patients. The study also found that the effectiveness of TCZ in reducing NMOSD patients' ARR ratio was related to gender, race, and TCZ dosage, while the effectiveness of reducing EDSS score was not related to these factors. Among the 153 patients receiving TCZ treatment, 101 (66 %) experienced mild adverse reactions, and one patient experienced a severe adverse reaction (facial cellulitis). The comprehensive data indicate that TCZ treatment can reduce the frequency of NMOSD relapses, improve patients' neurological function, and have good safety. The effectiveness of TCZ in reducing NMOSD patients' ARR ratio is related to multiple factors.

Advanced glycation end products initiate the mutual promoting cycle between centrosome amplification and the release of inflammatory cytokines in human vascular endothelial cells

Inflammation is implicated in the development of diabetic complications including vascular pathology. Centrosome is known to play a role in cell secretion. We have reported that diabetes can trigger centrosome amplification (CA). Thus, in the present study, we investigated the relationship between CA and the release of proinflammatory cytokines interleukin-1β, tumor necrosis factor-α and interleukin-6 in hCMEC/D3 human endothelial cells treated with advanced glycation end products (AGEs). We found that AGEs induced CA via PLK4 and increased the biosynthesis of the three cytokines via NF-κB. Importantly, treatment of the cells with AGEs also increased the release of the three cytokines. Inhibiting CA by knockdown of polo like kinase 4 (PLK4) attenuated the cytokine release but not their biosynthesis. Knockdown of the cytokines inhibited the CA, while addition of the cytokines individually to the cell culture increased the protein level of PLK4 and CA to a moderate level. Addition of the three cytokines together into the cell culture markedly enhanced the CA, to a level higher than that in the AGEs-treated group. In conclusion, our results provide the direct evidence that the cytokines can induce CA, and suggest that there is a mutual promoting cycle between CA and cytokine release in the treated samples. It is proposed that the cycle of CA-cytokine release is a candidate biological link between diabetes and its complications such as vascular pathologies.

Profile and potential role of novel metabolite biomarkers, especially indoleacrylic acid, in pathogenesis of neuromyelitis optica spectrum disorders

Background: Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune central nervous system (CNS) inflammatory and demyelinating disorder that can lead to serious disability and mortality. Humoral fluid biomarkers with specific, convenient, and efficient profiles that could characterize and monitor disease activity or severity are very useful. We aimed to develop a sensitive and high-throughput liquid chromatography-tandem mass spectrometry (LC-MS)/MS-based analytical method for novel biomarkers finding in NMOSD patients and verified its function tentatively. Methods: Serum samples were collected from 47 NMOSD patients, 18 patients with other neurological disorders (ONDs), and 35 healthy controls (HC). Cerebrospinal fluid (CSF) samples were collected from 18 NMOSD and 17 OND patients. Three aromatic amino acids (phenylalanine, tyrosine, and tryptophan) and nine important metabolites that included phenylacetylglutamine (PAGln), indoleacrylic acid (IA), 3-indole acetic acid (IAA), 5-hydroxyindoleacetic acid (HIAA), hippuric acid (HA), I-3-carboxylic acid (I-3-CA), kynurenine (KYN), kynurenic acid (KYNA), and quinine (QUIN) were analyzed by using the liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based method. The profile of IA was further analyzed, and its function was verified in an astrocyte injury model stimulated by NMO-IgG, which represents important events in NMOSD pathogenesis. Results: In the serum, tyrosine and some of the tryptophan metabolites IA and I-3-CA decreased, and HIAA increased significantly in NMOSD patients. The CSF levels of phenylalanine and tyrosine showed a significant increase exactly during the relapse stage, and IA in the CSF was also increased markedly during the relapse and remission phases. All conversion ratios had similar profiles with their level fluctuations. In addition, the serum IA levels negatively correlated with glial fibrillary acidic protein (GFAP), and neurofilament light (NfL) levels in the serum of NMOSD patients were measured by using ultra-sensitive single-molecule arrays (Simoa). IA showed an anti-inflammatory effect in an in vitro astrocyte injury model. Conclusion: Our data suggest that essential aromatic amino acid tryptophan metabolites IA in the serum or CSF may serve as a novel promising biomarker to monitor and predict the activity and severity of NMOSD disease. Supplying or enhancing IA function can promote anti-inflammatory responses and may have therapeutic benefits.

Central nervous system demyelinating diseases: glial cells at the hub of pathology

Inflammatory demyelinating diseases (IDDs) are among the main causes of inflammatory and neurodegenerative injury of the central nervous system (CNS) in young adult patients. Of these, multiple sclerosis (MS) is the most frequent and studied, as it affects about a million people in the USA alone. The understanding of the mechanisms underlying their pathology has been advancing, although there are still no highly effective disease-modifying treatments for the progressive symptoms and disability in the late stages of disease. Among these mechanisms, the action of glial cells upon lesion and regeneration has become a prominent research topic, helped not only by the discovery of glia as targets of autoantibodies, but also by their role on CNS homeostasis and neuroinflammation. In the present article, we discuss the participation of glial cells in IDDs, as well as their association with demyelination and synaptic dysfunction throughout the course of the disease and in experimental models, with a focus on MS phenotypes. Further, we discuss the involvement of microglia and astrocytes in lesion formation and organization, remyelination, synaptic induction and pruning through different signaling pathways. We argue that evidence of the several glia-mediated mechanisms in the course of CNS demyelinating diseases supports glial cells as viable targets for therapy development.

Targeting chemoattractant chemokine (C-C motif) ligand 2 derived from astrocytes is a promising therapeutic approach in the treatment of neuromyelitis optica spectrum disorders

Introduction

Aquaporin-4 immunoglobulin G (AQP4-IgG)-induced astrocytes injury is a key mechanism in the pathogenesis of neuromyelitis spectrum disorder (NMOSD), and although CCL2 is involved, its specific role has not been reported. We aimed to further investigate the role and potential mechanisms of CCL2 in AQP4-IgG-induced astrocyte injury.

Methods

First, we evaluated CCL2 levels in paired samples of subject patients by automated microfluidic platform, Ella®. Second, we knock down astrocyte's CCL2 gene in vitro and in vivo to define the function of CCL2 in AQP4-IgG-induced astrocyte injury. Third, astrocyte injury and brain injury in live mice were assessed by immunofluorescence staining and 7.0T MRI, respectively. Western blotting and high-content screening were conducted to clarify the activation of inflammatory signaling pathways, and changes in CCL2 mRNA and cytokine/chemokines were measured by qPCR technique and flow cytometry, respectively.

Results

There were greatly higher CSF-CCL2 levels in NMOSD patients than that in other non-inflammatory neurological diseases (OND) groups. Blocking astrocyte CCL2 gene expression can efficiently mitigate AQP4-IgG-induced damage in vitro and in vivo. Interestingly, prevention of CCL2 expression could decrease other inflammatory cytokines released, including IL-6 and IL-1β. Our data suggest that CCL2 involves in the initiation and plays a pivotal role in AQP4-IgG-damaged astrocytes.

Discussion

Our results indicate that CCL2 may serve as a promising candidate target for inflammatory disorder therapy, including NMOSD.

The circadian rhythms regulated by Cx43-signaling in the pathogenesis of Neuromyelitis Optica

Introduction

Neuromyelitis Optica (NMO) is an inflammatory demyelinating disease of the central nervous system (CNS). NMO manifests as selective and severe attacks on axons and myelin of the optic nerve and spinal cord, resulting in necrotic cavities. The circadian rhythms are well demonstrated to profoundly impact cellular function, behavior, and disease. This study is aimed to explore the role and molecular basis of circadian rhythms in NMO.

Methods

We used an Aquaporin 4(AQP4) IgG-induced NMO cell model in isolated astrocytes. The expression of Cx43 and Bmal1 were detected by real-time PCR and Western Blot. TAT-Gap19 and DQP-1105 were used to inhibit Cx43 and glutamate receptor respectively. The knockdown of Bmal1 were performed with the shRNA containing adenovirus. The levels of glutamate, anterior visual pathway (AVP), and vasoactive intestinal peptide (VIP) were quantified by ELISA kits.

Results

We found that Bmal1 and Clock, two essential components of the circadian clock, were significantly decreased in NMO astrocytes, which were reversed by Cx43 activation (linoleic acid) or glutamate. Moreover, the expression levels of Bmal1 and Clock were also decreased by Cx43 blockade (TAT-Gap19) or glutamate receptor inhibition (DQP-1105). Furthermore, adenovirus-mediated Bmal1 knockdown by shRNA (Ad-sh-Bmal1) dramatically decreased the levels of glutamate, AVP, and VIP from neurons, and significantly down-regulated the protein level of Cx43 in NMO astrocytes with Cx43 activation (linoleic acid) or glutamate treatment. However, Bmal1 knockdown did not alter these levels in normal astrocytes with Cx43 blockade (TAT-Gap19) or glutamate receptor inhibition (DQP-1105).

Discussion

Collectively, these results suggest that Cx43-glutamate signaling would be a critical upstream regulator that contributes to the NMO-induced rhythmic damage in SCN astrocytes.