Cerebrospinal fluid levels of CXCL13 are elevated in neuromyelitis optica

Soluble biomarkers for Neuromyelitis Optica Spectrum Disorders: a mini review

The Neuromyelitis Optica Spectrum Disorders (NMOSD) constitute a spectrum of rare autoimmune diseases of the central nervous system characterized by episodes of transverse myelitis, optic neuritis, and other demyelinating attacks. Previously thought to be a subtype of multiple sclerosis, NMOSD is now known to be a distinct disease with unique pathophysiology, clinical course, and treatment options. Although there have been significant recent advances in the diagnosis and treatment of NMOSD, the field still lacks clinically validated biomarkers that can be used to stratify disease severity, monitor disease activity, and inform treatment decisions. Here we review many emerging NMOSD biomarkers including markers of cellular damage, neutrophil-to-lymphocyte ratio, complement, and cytokines, with a focus on how each biomarker can potentially be used for initial diagnosis, relapse surveillance, disability prediction, and treatment monitoring.

Interactions Between Extracellular Vesicles and Autophagy in Neuroimmune Disorders

Neuroimmune disorders, such as multiple sclerosis, neuromyelitis optica spectrum disorder, myasthenia gravis, and Guillain-Barré syndrome, are characterized by the dysfunction of both the immune system and the nervous system. Increasing evidence suggests that extracellular vesicles and autophagy are closely associated with the pathogenesis of these disorders. In this review, we summarize the current understanding of the interactions between extracellular vesicles and autophagy in neuroimmune disorders and discuss their potential diagnostic and therapeutic applications. Here we highlight the need for further research to fully understand the mechanisms underlying these disorders, and to develop new diagnostic and therapeutic strategies.

CXCL13 in Cerebrospinal Fluid: Clinical Value in a Large Cross-Sectional Study

C-X-C-motif chemokine ligand 13 (CXCL13) in cerebrospinal fluid (CSF) is increasingly used in clinical routines, although its diagnostic specificity and divergent cut-off values have been defined so far mainly for neuroborreliosis. Our aim was to evaluate the value of CSF-CXCL13 as a diagnostic and treatment response marker and its role as an activity marker in a larger disease spectrum, including neuroborreliosis and other neuroinflammatory and malignant CNS-disorders. Patients who received a diagnostic lumbar puncture (LP) (n = 1234) between July 2009 and January 2023 were included in our retrospective cross-sectional study. The diagnostic performance of CSF-CXCL13 for acute neuroborreliosis was highest at a cut-off of 428.92 pg/mL (sensitivity: 92.1%; specificity: 96.5%). In addition, CXCL13 levels in CSF were significantly elevated in multiple sclerosis with clinical (p = 0.001) and radiographic disease activity (p < 0.001). The clinical utility of CSF-CXCL13 appears to be multifaceted. CSF-CXCL13 is significantly elevated in patients with neuroborreliosis and shows a rapid and sharp decline with antibiotic therapy, but it is not specific for this disease and is also highly elevated in less common subacute neuroinfectious diseases, such as neurosyphilis and cryptococcal meningitis or in primary/secondary B-cell lymphoma.

Update on the diagnosis and treatment of neuromyelits optica spectrum disorders (NMOSD) - revised recommendations of the Neuromyelitis Optica Study Group (NEMOS). Part I: Diagnosis and differential diagnosis

The term 'neuromyelitis optica spectrum disorders' (NMOSD) is used as an umbrella term that refers to aquaporin-4 immunoglobulin G (AQP4-IgG)-positive neuromyelitis optica (NMO) and its formes frustes and to a number of closely related clinical syndromes without AQP4-IgG. NMOSD were originally considered subvariants of multiple sclerosis (MS) but are now widely recognized as disorders in their own right that are distinct from MS with regard to immunopathogenesis, clinical presentation, optimum treatment, and prognosis. In part 1 of this two-part article series, which ties in with our 2014 recommendations, the neuromyelitis optica study group (NEMOS) gives updated recommendations on the diagnosis and differential diagnosis of NMOSD. A key focus is on differentiating NMOSD from MS and from myelin oligodendrocyte glycoprotein antibody-associated encephalomyelitis (MOG-EM; also termed MOG antibody-associated disease, MOGAD), which shares significant similarity with NMOSD with regard to clinical and, partly, radiological presentation, but is a pathogenetically distinct disease. In part 2, we provide updated recommendations on the treatment of NMOSD, covering all newly approved drugs as well as established treatment options.

Novel CSF Biomarkers Tracking Autoimmune Inflammatory and Neurodegenerative Aspects of CNS Diseases

The accurate diagnosis of neuroinflammatory (NIDs) and neurodegenerative (NDDs) diseases and the stratification of patients into disease subgroups with distinct disease-related characteristics that reflect the underlying pathology represents an unmet clinical need that is of particular interest in the era of emerging disease-modifying therapies (DMT). Proper patient selection for clinical trials and identifying those in the prodromal stages of the diseases or those at high risk will pave the way for precision medicine approaches and halt neuroinflammation and/or neurodegeneration in early stages where this is possible. Towards this direction, novel cerebrospinal fluid (CSF) biomarker candidates were developed to reflect the diseased organ's pathology better. Μisfolded protein accumulation, microglial activation, synaptic dysfunction, and finally, neuronal death are some of the pathophysiological aspects captured by these biomarkers to support proper diagnosis and screening. We also describe advances in the field of molecular biomarkers, including miRNAs and extracellular nucleic acids known as cell-free DNA and mitochondrial DNA molecules. Here we review the most important of these novel CSF biomarkers of NIDs and NDDs, focusing on their involvement in disease development and emphasizing their ability to define homogeneous disease phenotypes and track potential treatment outcomes that can be mirrored in the CSF compartment.

Serum and Cerebrospinal Fluid Biomarkers in Neuromyelitis Optica Spectrum Disorder and Myelin Oligodendrocyte Glycoprotein Associated Disease

The term neuromyelitis optica spectrum disorder (NMOSD) describes a group of clinical-MRI syndromes characterized by longitudinally extensive transverse myelitis, optic neuritis, brainstem dysfunction and/or, less commonly, encephalopathy. About 80% of patients harbor antibodies directed against the water channel aquaporin-4 (AQP4-IgG), expressed on astrocytes, which was found to be both a biomarker and a pathogenic cause of NMOSD. More recently, antibodies against myelin oligodendrocyte glycoprotein (MOG-IgG), have been found to be a biomarker of a different entity, termed MOG antibody-associated disease (MOGAD), which has overlapping, but different pathogenesis, clinical features, treatment response, and prognosis when compared to AQP4-IgG-positive NMOSD. Despite important refinements in the accuracy of AQP4-IgG and MOG-IgG testing assays, a small proportion of patients with NMOSD still remain negative for both antibodies and are called “seronegative” NMOSD. Whilst major advances have been made in the diagnosis and treatment of these conditions, biomarkers that could help predict the risk of relapses, disease activity, and prognosis are still lacking. In this context, a number of serum and/or cerebrospinal fluid biomarkers are emerging as potentially useful in clinical practice for diagnostic and treatment purposes. These include antibody titers, cytokine profiles, complement factors, and markers of neuronal (e.g., neurofilament light chain) or astroglial (e.g., glial fibrillary acidic protein) damage. The aim of this review is to summarize current evidence regarding the role of emerging diagnostic and prognostic biomarkers in patients with NMOSD and MOGAD.

A comprehensive review on the role of chemokines in the pathogenesis of multiple sclerosis

Multiple sclerosis (MS) as a chronic inflammatory disorder of the central nervous system (CNS) is thought to be caused by the abnormal induction of immune responses. Chemokines as molecules that can engage leukocytes into the location of inflammation, actively participate in the pathogenesis of MS. Several members of this family of chemo attractants have been shown to be dysregulated in the peripheral blood, cerebrospinal fluid or CNS lesions of MS patients. Studies in animal models of MS particularly experimental autoimmune encephalomyelitis have indicated the critical roles of chemokines in the pathophysiology of MS. In the current review, we summarize the data regarding the role of CCL2, CCL3, CCL4, CCL11, CCL20, CXCL1, CXCL2, CXCL8, CXCL10, CXCL12 and CXCL13 in the pathogenesis of MS.

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.

Anti-NMDA Receptor Encephalitis: Efficacy of Treatment for Male Patients and miRNA Biomarker

BACKGROUND

Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis is an acute form of encephalitis. Treatments for the anti-NMDA receptor encephalitis usually include steroids, intravenous immunoglobulin, plasma exchange, plasmapheresis, rituximab, cyclophosphamide and tumor resection.

OBJECTIVE

We aimed to compare the efficacy of the treatments including intravenous immunoglobulin, plasma exchange, plasmapheresis, rituximab or cyclophosphamide for male anti- NMDA receptor encephalitis patients without tumor and to discuss potential biomarkers for this disease.

METHOD

The Fisher exact test and the contingency table analysis were used to analyze the treatment efficacy for 43 male and 76 female patients. In addition, a hierarchical tree method was adopted to analyze the difference in the treatment efficacy between male and female patients.

RESULTS

The p-values of testing whether the efficacy rate of plasmapheresis (or plasma exchange) for the male patient is greater than a threshold are significantly different from the pvalues for the other two treatments. In addition, the hierarchical tree method shows that the treatment strategy associating with early recovery is different for male and female patients.

CONCLUSION

The results revealed that the efficacy rate of plasmapheresis (or plasma exchange) is not inferior to that of intravenous immunoglobulin and rituximab (or cyclophosphamide) for male patients without tumor. In addition, B-cell attracting C-X-C motif chemokine 13 (CXCL13) and microRNA let-7b have the potential to be the treatment response biomarkers for anti-NMDA receptor encephalitis. They may not be useful prognostic biomarkers for this encephalitis unless they are not biomarkers for other autoimmune encephalitides.

Rheumatoid Meningitis a Rare Extra-Articular Manifestation of Rheumatoid Arthritis: Report of 6 Cases and Literature Review

Objectives. Central neurological manifestations of rheumatoid arthritis (RA) like rheumatoid meningitis (RM) are rare, little known and have a high rate of morbi-mortality. METHODS. We described six cases of RM that were directly related to RA activity after exhaustive assessment. RESULTS. They were mainly women, aged of 50 to 69. All were positive for anti-cyclic citrullinated peptide antibodies and half for rheumatoid factors. RA activity, duration, and treatments were heterogeneous including oral steroids, conventional synthetic disease modifying anti-rheumatic drugs (DMARDs) and biologic DMARDs. Symptoms were various, with acute or progressive beginning; main were: generalized or focal seizure (4/6), fever (3/6), headaches (3/6), and frontal syndrome (2/6). Imaging lesions were four leptomeningitis, one pachymeningitis, and one association of both. MRI usually showed hypersignal in various territories in T2-FLAIR (fluid attenuated inversion recovery) mode, and enhancement in T1-weighted mode after gadolinium injection. All patients had lumbar puncture that found sterile cerebrospinal fluid, no neoplasic cell, elevated cell count in 5/6 cases and elevated proteins concentration in 3/6 cases. Cerebral biopsy was possible for three patients, and definitively confirmed the diagnosis of aseptic lepto- or pachymenintis, excluding vasculitis and lymphoma. Different treatments were used like intravenous high dose steroids, immunoglobulins or biologic DMARDs, with variable clinical and imaging outcome: one death, one complete recovery, and four recoveries with sequelae. Conclusions. Clinical symptoms, imaging, lumbar puncture, and serological studies are often nonspecific, only histologic examination can confirm the diagnosis of RM. Any central neurological manifestation in RA patients, even in quiescent and ancient RA, should warn the physician.

Multi-marker algorithms based on CXCL13, IL-10, sIL-2 receptor, and β2-microglobulin in cerebrospinal fluid to diagnose CNS lymphoma

Tumor biopsy is essential for the definitive diagnosis of central nervous system (CNS) lymphoma. However, the biopsy procedure carries the risk of complications such as bleeding, convulsions, and infection. Cerebrospinal fluid (CSF) β2‐microglobulin (β2‐MG), soluble IL‐2 receptor (sIL‐2R), and interleukin‐10 (IL‐10) are known to be useful diagnostic biomarkers for CNS lymphoma. The C‐X‐C motif chemokine ligand 13 (CXCL13) was recently reported to be another useful biomarker for CNS lymphoma. The purpose of this study is to establish a diagnostic algorithm that can avoid biopsy by combining these diagnostic biomarkers. In the first, we conducted a case‐control study (n = 248) demonstrating that the CSF CXCL13 concentration was significantly increased in CNS lymphoma patients compared with various other brain diseases (AUC = 0.981). We established a multi‐marker diagnostic model using CSF CXCL13, IL‐10, β2‐MG, and sIL‐2R from the results of the case‐control study and then applied the model to a prospective study (n = 104) to evaluate its utility. The multi‐marker diagnostic algorithms had excellent diagnostic performance: the sensitivity, specificity, positive predictive value, and negative predictive value were 97%, 97%, 94%, and 99%, respectively. In addition, CSF CXCL13 was a prognostic biomarker for CNS lymphoma patients. Our study suggests that multi‐marker algorithms are important diagnostic tools for patients with CNS lymphoma.

Cytokines and chemokines expression in serum of patients with neuromyelitis optica

OBJECTIVE

To study the differences in immunopathogenesis based on chemokine profile in neuromyelitis optica patients positive for AQP4 antibodies or MOG antibodies.

PATIENTS AND METHODS

We measured 52 cytokines/chemokines using ELISA in 59 serum samples, which were divided into three groups according to CBA results: HCs (n=16), AQP4+ (n=20) and MOG+ (n=23). The regression equation (R ²>0.98) of the standard curve was calculated according to the standard concentration and the corresponding A value. And then the corresponding sample concentration was calculated according to the A value of the sample.

RESULTS

Eleven of 52 measured serum cytokine/chemokines (CCL22/MDC, CCL13/MCP-4, CCL21/6Ckine, CCL27/CTACK, CCL8/MCP-2, CXCL14/BRAK, Contactin-1, Kallilrein 6/Neurosin, Midkine, VCAM-1 and Fas) were significantly different between MOG+ group and controls. Ten of 52 measured serum cytokine/chemokines (CCL1/I-309, CCL22/MDC, CCL28, CCL17/TARC, CCL27/CTACK, CXCL2/GRO beta, Contactin-1, Midkine, Chemerin and Synuclein-alpha) were significantly different between AQP4+ group and controls. There was no difference between serum AQP4+ and MOG+ groups for CC chemokines. All measured chemokines CXC except CXCL6/GCP-2 showed no significant differences in serum AQP4+ group compared to MOG+ group. However, there was significant difference between serum AQP4+ and MOG+ groups for C5/C5a and Midkine. C5/C5a and Midkine were significantly higher in AQP4+ group compared to MOG+ group (P<0.05).

CONCLUSION

Our findings suggest that the differences of mean concentration in CXCL6/GCP-2, Midkine and C5/C5a probably reveal different immunologic mechanism between AQP4+ NMO and MOG+ NMO. This cytokine/chemokine profiling provides new insight into NMO pathogenesis associated with MOG antibody seropositivity and provides guidance to monitor inflammation and response to treatment in a way.

Resolution of inflammation in neuromyelitis optica spectrum disorders

BACKGROUND

Neuromyelitis optica spectrum disorders (NMOSD) are a spectrum of neuroinflammatory disorders associated with autoimmune antibodies against aquaporin-4 (AQP4). Accumulating evidence suggests that inflammation is involved in NMOSD pathogenesis. Resolution of inflammation, which is a highly regulated process mediated by specialized pro-resolving lipid mediators (SPMs) is important to prevent over-responsive inflammation. Deficiency in resolution of inflammation may lead to or accelerates inflammatory diseases. However, whether resolution of inflammation is impaired in NMOSD is not known. The objective of this study was to analyze the levels of SPMs in the serum and cerebrospinal fluid (CSF) of NMOSD patients, and to explore the roles of SPMs in clinical features of NMOSD.

METHODS

Thirty-five patients with NMOSD, 34 patients with multiple sclerosis, and 36 patients with non-inflammatory neurological diseases were enrolled in this study. Pro-resolving mediators including Annexin A1 (ANXA1) and resolvin D1 (RvD1), as well as pro-inflammatory lipid mediator leukotriene B4 (LTB4) levels were analyzed by enzyme-linked immunosorbent assay. Pro- and anti-inflammatory cytokines as well as chemokine levels were analyzed using cytometric beads array (CBA).

RESULTS

Our results showed RvD1 levels were significantly decreased, whereas LTB4 levels were significantly increased in the CSF of NMOSD patients. AQP4-IgG titer was negatively correlated with RvD1 levels in the CSF of NMOSD patients.

CONCLUSIONS

Decreased RvD1 levels indicate impaired resolution of inflammation in NMOSD patients. AQP4-IgG may contribute to increased inflammation and lead to unresolved inflammation in NMOSD.

Utility and Safety of Intrathecal Methotrexate Treatment in Severe Anti-N-methyl-D-aspartate Receptor Encephalitis: A Pilot Study

Background:

Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is a treatable autoimmune neurologic syndrome that occurs with or without tumor association. However, some severe cases are refractory to systemic immunotherapy. This pilot study aimed to evaluate the utility and safety of intrathecal methotrexate injection for severe patients with anti-NMDAR encephalitis who did not respond to first-line immunotherapy.

Methods:

Intrathecal injections with methotrexate and dexamethasone were performed weekly in four legible patients within consecutive 4 weeks. Cerebrospinal fluid (CSF) was collected at baseline and each time of intrathecal injection for identification of anti-NMDAR antibody titers.

Results:

Significant clinical improvement was observed in three patients associated with a stepwise decrease of CSF anti-NMDAR antibody titers (maximum: 1/320 to minimum: 1/10). After 2 months of follow-up, they were able to follow simple commands and had appropriate interactions with people (modified Rankin scale [mRS] of 0–2). At 12 months of follow-up, they all had returned to most activities of daily life (mRS of 0), and no relapses were reported. One patient showed no clinical improvement and died of neurologic complications.

Conclusions:

Intrathecal treatment may be a potentially useful supplementary therapy in severely affected patients with anti-NMDAR encephalitis. Further large cohort study and animal experiment may help us elaborate the utility of intrathecal injection of methotrexate and its mechanism of action.

Elevated C-X-C motif ligand 13 and B-cell-activating factor levels in neuromyelitis optica during remission

BACKGROUND

Discovery of specific antibodies against astrocytic water channel aquaporin-4 (AQP4), which is produced by plasma cells, in the serum of neuromyelitis optica (NMO) confirmed the pathogenic role of B cells in NMO. C-X-C motif ligand 13 (CXCL13) and B-cell-activating factor (BAFF) are two crucial factors for antibody production. Relevant studies have focused on the acute phase of NMO. However, CXCL13 and BAFF levels during remission, remain to be elucidated.

OBJECTIVE

To evaluate serum levels of CXCL13 and BAFF in NMO and multiple sclerosis (MS) patients during remission and explore their correlation with immunosuppressive agents and clinical features in NMO.

METHODS

Serum CXCL13 and BAFF were measured by enzyme-linked immunosorbent assay (ELISA) in NMO patients, MS patients, and controls.

RESULTS

Serum CXCL13 levels of NMO patients (n = 24) were significantly higher than those of controls (n = 22) (p = .001), but CXCL13 levels of MS patients (n = 20) and controls (n = 22) did not differ significantly (p = .279). Although the three groups showed no differences in serum BAFF levels, serum BAFF levels of NMO patients without immunosuppressive treatment (n = 8) were significantly elevated compared with those of NMO patients with immunosuppressive therapy (n = 16) (p = .003) and controls (n = 22) (p = .024). In NMO patients, CXCL13 levels were correlated with onset age (p = .026) and duration to the last relapse (p = .003).

CONCLUSION

During remission, serum CXCL13 and BAFF levels have not decreased to normal in NMO patients, and B-cell-related autoimmune response persists. Immunosuppressive therapy decreased serum BAFF levels, but did not affect CXCL13 expression.

B Cell, Th17, and Neutrophil Related Cerebrospinal Fluid Cytokine/Chemokines Are Elevated in MOG Antibody Associated Demyelination

BACKGROUND

Myelin oligodendrocyte glycoprotein antibody (MOG Ab) associated demyelination represents a subgroup of autoimmune demyelination that is separate from multiple sclerosis and aquaporin 4 IgG-positive NMO, and can have a relapsing course. Unlike NMO and MS, there is a paucity of literature on immunopathology and CSF cytokine/chemokines in MOG Ab associated demyelination.

AIM

To study the differences in immunopathogenesis based on cytokine/chemokine profile in MOG Ab-positive (POS) and -negative (NEG) groups.

METHODS

We measured 34 cytokines/chemokines using multiplex immunoassay in CSF collected from paediatric patients with serum MOG Ab POS [acute disseminated encephalomyelitis (ADEM = 8), transverse myelitis (TM = 2) n = 10] and serum MOG Ab NEG (ADEM = 5, TM = 4, n = 9) demyelination. We generated normative data using CSF from 20 non-inflammatory neurological controls.

RESULTS

The CSF cytokine and chemokine levels were higher in both MOG Ab POS and MOG Ab NEG demyelination groups compared to controls. The CSF in MOG Ab POS patients showed predominant elevation of B cell related cytokines/chemokines (CXCL13, APRIL, BAFF and CCL19) as well as some of Th17 related cytokines (IL-6 AND G-CSF) compared to MOG Ab NEG group (all p<0.01). In addition, patients with elevated CSF MOG antibodies had higher CSF CXCL13, CXCL12, CCL19, IL-17A and G-CSF than patients without CSF MOG antibodies.

CONCLUSION

Our findings suggest that MOG Ab POS patients have a more pronounced CNS inflammatory response with elevation of predominant humoral associated cytokines/chemokines, as well as some Th 17 and neutrophil related cytokines/chemokines suggesting a differential inflammatory pathogenesis associated with MOG antibody seropositivity. This cytokine/chemokine profiling provides new insight into disease pathogenesis, and improves our ability to monitor inflammation and response to treatment. In addition, some of these molecules may represent potential immunomodulatory targets.

Hypersensitivity Responses in the Central Nervous System

Immune-mediated tissue damage or hypersensitivity can be mediated by autospecific IgG antibodies. Pathology results from activation of complement, and antibody-dependent cellular cytotoxicity, mediated by inflammatory effector leukocytes include macrophages, natural killer cells, and granulocytes. Antibodies and complement have been associated to demyelinating pathology in multiple sclerosis (MS) lesions, where macrophages predominate among infiltrating myeloid cells. Serum-derived autoantibodies with predominant specificity for the astrocyte water channel aquaporin-4 (AQP4) are implicated as inducers of pathology in neuromyelitis optica (NMO), a central nervous system (CNS) demyelinating disease where activated neutrophils infiltrate, unlike in MS. The most widely used model for MS, experimental autoimmune encephalomyelitis, is an autoantigen-immunized disease that can be transferred to naive animals with CD4⁺ T cells, but not with antibodies. By contrast, NMO-like astrocyte and myelin pathology can be transferred to mice with AQP4–IgG from NMO patients. This is dependent on complement, and does not require T cells. Consistent with clinical observations that interferon-beta is ineffective as a therapy for NMO, NMO-like pathology is significantly reduced in mice lacking the Type I IFN receptor. In MS, there is evidence for intrathecal synthesis of antibodies as well as blood–brain barrier (BBB) breakdown, whereas in NMO, IgG accesses the CNS from blood. Transfer models involve either direct injection of antibody and complement to the CNS, or experimental manipulations to induce BBB breakdown. We here review studies in MS and NMO that elucidate roles for IgG and complement in the induction of BBB breakdown, astrocytopathy, and demyelinating pathology. These studies point to significance of T-independent effector mechanisms in neuroinflammation.

Investigations on CXCL13 in anti-N-methyl-D-aspartate receptor encephalitis: a potential biomarker of treatment response

IMPORTANCE

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a severe but treatable autoimmune encephalitis affecting mainly young adults and children. The lack of suitable biomarkers of disease activity makes treatment decisions and identification of relapses challenging.

OBJECTIVE

To determine the levels of the B-cell-attracting C-X-C motif chemokine 13 (CXCL13) in serum samples and cerebrospinal fluid (CSF) of patients with anti-NMDAR encephalitis and whether they can be used as biomarkers of treatment response and outcome.

DESIGN, SETTINGS, AND PARTICIPANTS

Retrospective cohort study of 167 patients consecutively diagnosed as having anti-NMDAR encephalitis between May 1, 2008, and January 31, 2013. Concentration of CXCL13 was determined with enzyme-linked immunosorbent assay in all available patients' samples (272 CSF and 55 serum samples). Samples from 25 patients with noninflammatory neurological disorders and 9 with neuroborreliosis served as controls. Expression of CXCL13 in the brain biopsy of a patient with anti-NMDAR encephalitis was determined by immunohistochemistry.

MAIN OUTCOMES AND MEASURES

Percentage of patients with anti-NMDAR encephalitis and elevated CXCL13 in CSF.

RESULTS

Compared with control individuals, 70% of patients with early-stage anti-NMDAR encephalitis had increased CXCL13 in CSF (>7 pg/mL; P < .001) but none in serum samples (>1047 pg/mL; P > .99). High concentration of CSF CXCL13 was associated with the presence of prodromal fever or headache (P = .01), limited response to therapy (P = .003), clinical relapses (P = .03), and intrathecal NMDAR-antibody synthesis (P < .001). Among patients with monophasic disease assessed 2 to 6 months after starting treatment, 10 of 15 with limited treatment response vs 0 of 13 with favorable response had increased CSF CXCL13 (specificity, 100%; 95% CI, 75-100 and sensitivity, 67%; 95% CI, 38-88; P = .02). Six of 12 patients had elevated CSF CXCL13 at relapse including 3 with previously normal levels. In brain, abundant mononuclear cells in perivascular infiltrates and scattered intraparenchymal microglia expressed CXCL13.

CONCLUSIONS AND RELEVANCE

Seventy percent of patients with early-stage anti-NMDAR encephalitis had increased CSF CXCL13 concentration that correlated with intrathecal NMDAR-antibody synthesis. Prolonged or secondary elevation of CXCL13 was associated with limited response to treatment and relapses. CXCL13 is a potentially useful biomarker of treatment response and outcome in anti-NMDAR encephalitis.

Biomarkers for neuromyelitis optica

Neuromyelitis optica (NMO) is an acquired, heterogeneous inflammatory disorder, which is characterized by recurrent optic neuritis and longitudinally extensive spinal cord lesions. The discovery of the serum autoantibody marker, anti-aquaporin 4 (anti-AQP4) antibody, revolutionizes our understanding of pathogenesis of NMO. In addition to anti-AQP4 antibody, other biomarkers for NMO are also reported. These candidate biomarkers are particularly involved in T helper (Th)17 and astrocytic damages, which play a critical role in the development of NMO lesions. Among them, IL-6 in the peripheral blood is associated with anti-AQP4 antibody production. Glial fibrillary acidic protein (GFAP) in CSF demonstrates good correlations with clinical severity of NMO relapses. Detecting these useful biomarkers may be useful in the diagnosis and evaluation of disease activity of NMO. Development of compounds targeting these biomarkers may provide novel therapeutic strategies for NMO. This article will review the related biomarker studies in NMO and discuss the potential therapeutics targeting these biomarkers.

Cytokines and chemokines in neuromyelitis optica: pathogenetic and therapeutic implications

Neuromyelitis optica (NMO) is characterized by severe optic neuritis and longitudinally extensive transverse myelitis. The discovery of an NMO-specific autoantibody to the aquaporin-4 (AQP4) water channel has improved knowledge of NMO pathogenesis. Many studies have focused on inflammatory and pathological biomarkers of NMO, including cytokines and chemokines. Increased concentrations of T helper (Th)17- and Th2-related cytokines and chemokines may be essential factors for developing NMO inflammatory lesions. For example, interleukin-6 could play important roles in NMO pathogenesis, as it is involved in the survival of plasmablasts that produce anti-AQP4 antibody in peripheral circulation and in the enhancement of inflammation in the central nervous system. Therefore, assessment of these useful biomarkers may become a supportive criterion for diagnosing NMO. Significant advances in the understanding of NMO pathogenesis will lead to the development of novel treatment strategies. This review focuses on the current advances in NMO immunological research, particularly that of cytokines and chemokines.

Cerebrospinal fluid CXCL13 is a prognostic marker for aseptic meningitis

In exceptional cases, patients with aseptic meningitis eventually develop aseptic meningoencephalitis. To find a candidate marker for the development of aseptic meningoencephalitis in adult patients diagnosed with aseptic meningitis, we compared 12 different cytokines/chemokines in cerebrospinal fluid (CSF) from 5 patients with aseptic meningoencephalitis, 8 patients with aseptic meningitis, and 8 patients with control disease. Only the CXCL13 concentration was significantly elevated in the CSF of the group with aseptic meningoencephalitis compared with the group with aseptic meningitis. Thus, CSF CXCL13 may be a useful marker for predicting the prognosis of aseptic meningitis.

Type-I interferons suppress microglial production of the lymphoid chemokine, CXCL13

Lymphoid chemokines are crucial for the development and maintenance of lymphoid organs, but their ectopic expression in non-lymphoid tissues is implicated in both local response to infection and chronic organ-specific autoimmunity. Production of one such chemokine, C-X-C motif ligand 13 (CXCL13), within the central nervous system (CNS) has been linked to the pathogenesis of multiple sclerosis (MS), although little is known about factors controlling its expression in different neural cell types and across a range of disease states. We provoked acute neuroinflammation in experimental animals without causing any associated demyelination using neuroadapted Sindbis virus (NSV) to better understand the sources and regulators of this chemokine in the CNS. We found that mice genetically deficient in the transcription factor, interferon (IFN) regulatory factor-7 (IRF7), made significantly higher CXCL13 protein levels in the CNS compared with wild-type (WT) controls. Microglia proved to be the main producer of CXCL13 in the brain during infection of both WT and IRF7^−/− mice, and primary microglia cultured in vitro generated CXCL13 following stimulation with either virus particles or synthetic Toll-like receptor (TLR) ligands. Microglia cultured from IRF7^−/− mice selectively overproduced CXCL13, and manipulation of extracellular type-I IFN levels demonstrated the existence of a negative feedback loop whereby type-I IFN receptor signaling specifically suppressed microglial CXCL13 release. Since IFN-β is used to treat patients with relapsing-remitting MS and yet acts through unknown mechanisms, we speculate that suppressed lymphoid chemokine production by microglia could contribute to its therapeutic effects.

Monitoring neuromyelitis optica activity

Neuromyelitis optica (NMO) is a demyelinating and inflammatory disease essentially restricted to the spinal cord and the optic nerves. Emerging evidence indicates that serum antiaquaporin-4 (AQP4) antibodies have a critical role in its pathogenesis. NMO courses with multiple relapses, often leading to severe disability. Management of NMO focuses on the effective treatment of acute attacks and the prevention of relapses. The latter is currently attempted with immunosuppressive drugs. Although several factors have been associated with disease activity, especially serum levels of anti-AQP4 IgG, no single one of them has been proved clinically useful for guiding treatment. New drugs that target specifically AQP4 antibodies and complement activation are being developed; they may prove to be more efficient with fewer side effects.

CXCL13 is a biomarker of inflammation in multiple sclerosis, neuromyelitis optica, and other neurological conditions

CXCL13, a B-cell chemokine, has been proposed as a biomarker in a variety of conditions, some of which can mimic multiple sclerosis and can have very high levels. In this case-control study, cerebrospinal fluid (CSF) CXCL13 was elevated in multiple sclerosis, neuromyelitis optica and other inflammatory neurological controls compared with noninflammatory controls. Levels did not differentiate disease groups. For all subjects taken together, CSF CXCL13 correlated with CSF WBC, oligoclonal band numbers, CSF protein, EDSS, and neurofilament levels. In subgroup analyses, CSF CXCL13 correlated with CSF WBC in neuromyelitis optica and IgG index in multiple sclerosis. Additionally, serum CXCL13 was elevated in neuromyelitis optica.

Cerebrospinal fluid IL-12p40, CXCL13 and IL-8 as a combinatorial biomarker of active intrathecal inflammation

Diagnosis and management of the neuroinflammatory diseases of the central nervous system (CNS) are hindered by the lack of reliable biomarkers of active intrathecal inflammation. We hypothesized that measuring several putative inflammatory biomarkers simultaneously will augment specificity and sensitivity of the biomarker to the clinically useful range. Based on our pilot experiment in which we measured 18 inflammatory biomarkers in 10-fold concentrated cerebrospinal fluid (CSF) derived from 16 untreated patients with highly active multiple sclerosis (MS) we selected a combination of three CSF biomarkers, IL-12p40, CXCL13 and IL-8, for further validation.Concentrations of IL-12p40, CXCL13 and IL-8 were determined in a blinded fashion in CSF samples from an initial cohort (n = 72) and a confirmatory cohort (n = 167) of prospectively collected, untreated subjects presenting for a diagnostic work-up of possible neuroimmunological disorder. Diagnostic conclusion was based on a thorough clinical workup, which included laboratory assessment of the blood and CSF, neuroimaging and longitudinal follow-up. Receiver operating characteristic (ROC) curve analysis in conjunction with principal component analysis (PCA), which was used to combine information from all three biomarkers, assessed the diagnostic value of measured biomarkers.Each of the three biomarkers was significantly increased in MS and other inflammatory neurological disease (OIND) in comparison to non-inflammatory neurological disorder patients (NIND) at least in one cohort. However, considering all three biomarkers together improved accuracy of predicting the presence of intrathecal inflammation to the consistently good to excellent range (area under the ROC curve = 0.868-0.924).Future clinical studies will determine if a combinatorial biomarker consisting of CSF IL-12p40, CXCL13 and IL-8 provides utility in determining the presence of active intrathecal inflammation in diagnostically uncertain cases and in therapeutic development and management.

Molecular pathogenesis of neuromyelitis optica

Neuromyelitis optica (NMO) is a rare autoimmune disorder, distinct from multiple sclerosis, causing inflammatory lesions in the optic nerves and spinal cord. An autoantibody (NMO IgG) against aquaporin-4 (AQP4), a water channel expressed on astrocytes is thought to be causative. Peripheral production of the antibody is triggered by an unknown process in genetically susceptible individuals. Anti-AQP4 antibody enters the central nervous system (CNS) when the blood brain barrier is made permeable and has high affinity for orthogonal array particles of AQP4. Like other autoimmune diseases, Th17 cells and their effector cytokines (such as interleukin 6) have been implicated in pathogenesis. AQP4 expressing peripheral organs are not affected by NMO IgG, but the antibody causes extensive astrocytic loss in specific regions of the CNS through complement mediated cytotoxicity. Demyelination occurs during the inflammatory process and is probably secondary to oligodendrocyte apoptosis subsequent to loss of trophic support from astrocytes. Ultimately, extensive axonal injury leads to severe disability. Despite rapid advances in the understanding of NMO pathogenesis, unanswered questions remain, particularly with regards to disease mechanisms in NMO IgG seronegative cases. Increasing knowledge of the molecular pathology is leading to improved treatment strategies.

Impaired regulatory function and enhanced intrathecal activation of B cells in neuromyelitis optica: distinct from multiple sclerosis

BACKGROUND

The effective treatment of neuromyelitis optica (NMO) with rituximab has suggested an important role for B cells in NMO pathogenesis.

OBJECTIVE

To explore the antibody-independent function of B cells in NMO and relapsing-remitting multiple sclerosis (RRMS).

METHODS

Fifty-one NMO patients and 42 RRMS patients in an acute relapse phase and 37 healthy controls (HC) were enrolled in the study. The B cell expression of B cell activating factor receptor (BAFF-R), CXCR5 and very late antigen-4 (VLA-4), the B cell production of interleukin (IL)-10 and interferon (IFN)-γ and the proportion of circulating memory and CD19(+)CD24(high)CD38(high) regulatory B cells were evaluated by flow cytometry. The cerebrospinal fluid (CSF) levels of BAFF and CXCL13 were determined by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The CD19(+)CD24(high)CD38(high) regulatory B cell levels and the B cell expression of IL-10 were significantly lower in NMO patients than in RRMS patients and the HC. In aquaporin-4 antibody (AQP4-ab)-positive NMO patients, the B cell IL-10 production and CD19(+)CD24(high)CD38(high) regulatory B cell levels were even lower than in AQP4-ab-negative NMO patients. The CSF BAFF and CXCL13 levels were significantly higher in NMO patients than in patients with RRMS and other non-inflammatory neurologic diseases (ONDs).

CONCLUSIONS

The immuno-regulatory properties of B cells are significantly impaired in NMO patients and particularly in AQP4-ab-positive NMO patients. The elevated CSF levels of BAFF and CXCL13 in NMO suggest an enhanced intrathecal B cell recruitment and activation. Our results further define the distinct immunological nature of NMO and RRMS from the B cell perspective.