Potential Role of CHI3L1+ Astrocytes in Progression in MS

Invasive growth of brain metastases is linked to CHI3L1 release from pSTAT3-positive astrocytes

BACKGROUND

Compared to minimally invasive brain metastases (MI BrM), highly invasive (HI) lesions form abundant contacts with cells in the peritumoral brain parenchyma and are associated with poor prognosis. Reactive astrocytes (RAs) labeled by phosphorylated STAT3 (pSTAT3) have recently emerged as a promising therapeutic target for BrM. Here, we explore whether the BrM invasion pattern is influenced by pSTAT3+ RAs and may serve as a predictive biomarker for STAT3 inhibition.

METHODS

We used immunohistochemistry to identify pSTAT3+ RAs in HI and MI human and patient-derived xenograft (PDX) BrM. Using PDX, syngeneic, and transgenic mouse models of HI and MI BrM, we assessed how pharmacological STAT3 inhibition or RA-specific STAT3 genetic ablation affected BrM growth in vivo. Cancer cell invasion was modeled in vitro using a brain slice-tumor co-culture assay. We performed single-cell RNA sequencing of human BrM and adjacent brain tissue.

RESULTS

RAs expressing pSTAT3 are situated at the brain-tumor interface and drive BrM invasive growth. HI BrM invasion pattern was associated with delayed growth in the context of STAT3 inhibition or genetic ablation. We demonstrate that pSTAT3+ RAs secrete Chitinase 3-like-1 (CHI3L1), which is a known STAT3 transcriptional target. Furthermore, single-cell RNA sequencing identified CHI3L1-expressing RAs in human HI BrM. STAT3 activation, or recombinant CHI3L1 alone, induced cancer cell invasion into the brain parenchyma using a brain slice-tumor plug co-culture assay.

CONCLUSIONS

Together, these data reveal that pSTAT3+ RA-derived CHI3L1 is associated with BrM invasion, implicating STAT3 and CHI3L1 as clinically relevant therapeutic targets for the treatment of HI BrM.

Astrocyte-derived CHI3L1 signaling impairs neurogenesis and cognition in the demyelinated hippocampus

Cognitive dysfunction is a feature in multiple sclerosis (MS), a chronic inflammatory demyelinating disorder. A notable aspect of MS brains is hippocampal demyelination, which is closely associated with cognitive decline. However, the mechanisms underlying this phenomenon remain unclear. Chitinase-3-like (CHI3L1), secreted by activated astrocytes, has been identified as a biomarker for MS progression. Our study investigates CHI3L1's function within the demyelinating hippocampus and demonstrates a correlation between CHI3L1 expression and cognitive impairment in patients with MS. Activated astrocytes release CHI3L1 in reaction to induced demyelination, which adversely affects the proliferation and differentiation of neural stem cells and impairs dendritic growth, complexity, and spine formation in neurons. Our findings indicate that the astrocytic deletion of CHI3L1 can mitigate neurogenic deficits and cognitive dysfunction. We showed that CHI3L1 interacts with CRTH2/receptor for advanced glycation end (RAGE) by attenuating β-catenin signaling. The reactivation of β-catenin signaling can revitalize neurogenesis, which holds promise for therapy of inflammatory demyelination.

Single-cell analysis of anti-BCMA CAR T cell therapy in patients with central nervous system autoimmunity

Chimeric antigen receptor (CAR) T cell immunotherapy for the treatment of neurological autoimmune diseases is promising, but CAR T cell kinetics and immune alterations after treatment are poorly understood. Here, we performed single-cell multi-omics sequencing of paired cerebrospinal fluid (CSF) and blood samples from patients with neuromyelitis optica spectrum disorder (NMOSD) treated with anti-B cell maturation antigen (BCMA) CAR T cells. Proliferating cytotoxic-like CD8+ CAR T cell clones were identified as the main effectors in autoimmunity. Anti-BCMA CAR T cells with enhanced features of chemotaxis efficiently crossed the blood-CSF barrier, eliminated plasmablasts and plasma cells in the CSF, and suppressed neuroinflammation. The CD44-expressing early memory phenotype in infusion products was potentially associated with CAR T cell persistence in autoimmunity. Moreover, CAR T cells from patients with NMOSD displayed distinctive features of suppressed cytotoxicity compared with those from hematological malignancies. Thus, we provide mechanistic insights into CAR T cell function in patients with neurological autoimmune disease.

Synaptic injury in the inner plexiform layer of the retina is associated with progression in multiple sclerosis

While neurodegeneration underlies the pathological basis for permanent disability in multiple sclerosis (MS), predictive biomarkers for progression are lacking. Using an animal model of chronic MS, we find that synaptic injury precedes neuronal loss and identify thinning of the inner plexiform layer (IPL) as an early feature of inflammatory demyelination-prior to symptom onset. As neuronal domains are anatomically segregated in the retina and can be monitored longitudinally, we hypothesize that thinning of the IPL could represent a biomarker for progression in MS. Leveraging our dataset with over 800 participants enrolled for more than 12 years, we find that IPL atrophy directly precedes progression and propose that synaptic loss is predictive of functional decline. Using a blood proteome-wide analysis, we demonstrate a strong correlation between demyelination, glial activation, and synapse loss independent of neuroaxonal injury. In summary, monitoring synaptic injury is a biologically relevant approach that reflects a potential driver of progression.

Recently Updated Role of Chitinase 3-like 1 on Various Cell Types as a Major Influencer of Chronic Inflammation

Chitinase 3-like 1 (also known as CHI3L1 or YKL-40) is a mammalian chitinase that has no enzymatic activity, but has the ability to bind to chitin, the polymer of N-acetylglucosamine (GlcNAc). Chitin is a component of fungi, crustaceans, arthropods including insects and mites, and parasites, but it is completely absent from mammals, including humans and mice. In general, chitin-containing organisms produce mammalian chitinases, such as CHI3L1, to protect the body from exogenous pathogens as well as hostile environments, and it was thought that it had a similar effect in mammals. However, recent studies have revealed that CHI3L1 plays a pathophysiological role by inducing anti-apoptotic activity in epithelial cells and macrophages. Under chronic inflammatory conditions such as inflammatory bowel disease and chronic obstructive pulmonary disease, many groups already confirmed that the expression of CHI3L1 is significantly induced on the apical side of epithelial cells, and activates many downstream pathways involved in inflammation and carcinogenesis. In this review article, we summarize the expression of CHI3L1 under chronic inflammatory conditions in various disorders and discuss the potential roles of CHI3L1 in those disorders on various cell types.

A rapid review of differences in cerebrospinal neurofilament light levels in clinical subtypes of progressive multiple sclerosis

Background

Multiple sclerosis (MS) is divided into three clinical phenotypes: relapsing-remitting MS (RRMS), secondary progressive MS (SPMS), and primary progressive MS (PPMS). It is unknown to what extent SPMS and PPMS pathophysiology share inflammatory or neurodegenerative pathological processes. Cerebrospinal (CSF) neurofilament light (NfL) has been broadly studied in different MS phenotypes and is a candidate biomarker for comparing MS subtypes.

Research question

Are CSF NfL levels different among clinical subtypes of progressive MS?

Methods

A search strategy identifying original research investigating fluid neurodegenerative biomarkers in progressive forms of MS between 2010 and 2022 was applied to Medline. Identified articles underwent title and abstract screen and full text review against pre-specified criteria. Data abstraction was limited to studies that measured NfL levels in the CSF. Reported statistical comparisons of NfL levels between clinical phenotypes were abstracted qualitatively.

Results

18 studies that focused on investigating direct comparisons of CSF NfL from people with MS were included in the final report. We found NfL levels were typically reported to be higher in relapsing and progressive MS compared to healthy controls. Notably, higher NfL levels were not clearly associated with progressive MS subtypes when compared to relapsing MS, and there was no observed difference in NfL levels between PPMS and SPMS in articles that separately assessed these phenotypes.

Conclusion

CSF NfL levels distinguish individuals with MS from healthy controls but do not differentiate MS subtypes. Broad biological phenotyping is needed to overcome limitations of current clinical phenotyping and improve biomarker translatability to decision-making in the clinic.

Body fluid markers for multiple sclerosis and differential diagnosis from atypical demyelinating disorders

INTRODUCTION

Body fluid markers could be helpful to predict the conversion into clinically definite multiple sclerosis (MS) in people with a first demyelinating event of the central nervous system (CNS). Consequently, biomarkers such as oligoclonal bands, which are integrated in the current MS diagnostic criteria, could assist early MS diagnosis.

AREAS COVERED

This review examines existing knowledge on a broad spectrum of body fluid markers in people with a first CNS demyelinating event, explores their potential to predict conversion to MS, to assess MS disease activity, as well as their utility to differentiate MS from atypical demyelinating disorders such as neuromyelitis optica spectrum disorder and myelin oligodendrocyte glycoprotein associated disease.

EXPERT OPINION

This field of research has shown a dramatic increase of evidence, especially in the last decade. Some biomarkers are already established in clinical routine (e.g. oligoclonal bands) while others are currently implemented (e.g. kappa free light chains) or considered as breakthroughs (e.g. neurofilament light). Determination of biomarkers poses challenges for continuous monitoring, especially if exclusively detectable in cerebrospinal fluid. A handful of biomarkers are measurable in blood which holds a significant potential.

YKL-40 as a biomarker in various inflammatory diseases: A review

YKL-40 or Chitinase-3-Like Protein 1 (CHI3L1) is a highly conserved glycoprotein that binds heparin and chitin in a non-enzymatic manner. It is a member of the chitinase protein family 18, subfamily A, and unlike true chitinases, YKL-40 is a chitinase-like protein without enzymatic activity for chitin. Although its accurate function is yet unknown, the pattern of its expression in the normal and disease states suggests its possible engagement in apoptosis, inflammation and remodeling or degradation of the extracellular matrix. During an inflammatory response, YKL-40 is involved in a complicated interaction between host and bacteria, both promoting and attenuating immune response and potentially being served as an autoantigen in a vicious circle of autoimmunity. Based on its pathophysiology and mechanism of action, the aim of this review was to summarize research on the growing role of YKL-40 as a persuasive biomarker for inflammatory diseases' early diagnosis, prediction and follow-up (e.g., cardiovascular, gastrointestinal, endocrinological, immunological, musculoskeletal, neurological, respiratory, urinary, infectious) with detailed structural and functional background of YKL-40.

Serum glial fibrillary acidic protein and disability progression in progressive multiple sclerosis

OBJECTIVE

Progression prediction is a significant unmet need in people with progressive multiple sclerosis (pwPMS). Studies on glial fibrillary acidic protein (GFAP) have either been limited to single center with relapsing MS or were based solely on Expanded Disability Status Scale (EDSS), which limits its generalizability to state-of-the-art clinical settings and trials applying combined outcome parameters.

METHODS

Serum GFAP and NfL (neurofilament light chain) were investigated in EmBioProMS participants with primary (PP) or secondary progressive MS. Six months confirmed disability progression (CDP) was defined using combined outcome parameters (EDSS, timed-25-foot walk test (T25FW), and nine-hole-peg-test (9HPT)).

RESULTS

243 subjects (135 PPMS, 108 SPMS, age 55.5, IQR [49.7-61.2], 135 female, median follow-up: 29.3 months [17.9-40.9]) were included. NfL (age-) and GFAP (age- and sex-) adjusted Z scores were higher in pwPMS compared to HC (p < 0.001 for both). 111 (32.8%) CDP events were diagnosed in participants with ≥3 visits (n = 169). GFAP Z score >3 was associated with higher risk for CDP in participants with low NfL Z score (i.e., ≤1.0) (HR: 2.38 [1.12-5.08], p = 0.025). In PPMS, GFAP Z score >3 was associated with higher risk for CDP (HR: 2.88 [1.21-6.84], p = 0.016). Risk was further increased in PPMS subjects with high GFAP when NfL is low (HR: 4.31 [1.53-12.13], p = 0.006).

INTERPRETATION

Blood GFAP may help identify pwPPMS at risk of progression. Combination of high GFAP and low NfL levels could distinguish non-active pwPMS with particularly high progression risk.

Soluble TREM2 triggers microglial dysfunction in neuromyelitis optica spectrum disorders

Microglia-mediated neuroinflammation contributes to acute demyelination in neuromyelitis optica spectrum disorders (NMOSD). Soluble triggering receptor expressed on myeloid cells 2 (sTREM2) in the CSF has been associated with microglial activation in several neurodegenerative diseases. However, the basis for this immune-mediated attack and the pathophysiological role of sTREM2 in NMOSD remain to be elucidated. Here, we performed Mendelian randomization analysis and identified a genetic association between increased CSF sTREM2 and NMOSD risk. CSF sTREM2 was elevated in patients with NMOSD and was positively correlated with neural injury and other neuroinflammation markers. Single-cell RNA sequencing of human macrophage/microglia-like cells in CSF, a proxy for microglia, showed that increased CSF sTREM2 was positively associated with microglial dysfunction in patients with NMOSD. Furthermore, we demonstrated that sTREM2 is a reliable biomarker of microglial activation in a mouse model of NMOSD. Using unbiased transcriptomic and lipidomic screens, we identified that excessive activation, overwhelmed phagocytosis of myelin debris, suppressed lipid metabolism and enhanced glycolysis underlie sTREM2-mediated microglial dysfunction, possibly through the nuclear factor kappa B (NF-κB) signalling pathway. These molecular and cellular findings provide a mechanistic explanation for the genetic association between CSF sTREM2 and NMOSD risk and indicate that sTREM2 could be a potential biomarker of NMOSD progression and a therapeutic target for microglia-mediated neuroinflammation.

The Peripheral Profile of the Chitinase 3-like-1 in Benign Multiple Sclerosis - A Single Centre's Experience

BACKGROUND

A limited subgroup of multiple sclerosis (MS) patients present with a longterm disease evolution characterized by a limited disease progression, known as benign MS (BMS). Chitinase 3-like-1 (CHI3L1) levels are sensitive to inflammatory processes and may play a role in the pathogenesis of MS. In this observational, cross-sectional study, we aimed to evaluate the implications of serum CHI3L1 and inflammatory cytokines in BMS patients treated with interferon β-1b for over a decade.

METHODS

We collected serum samples from 17 BMS patients and 17 healthy controls (HC) to measure serum CHI3L1 levels and a Th17 panel of inflammatory cytokines. Serum levels of CHI3L1 were analysed using the sandwich ELISA method and the Th17 panel was assessed using the multiplex XMap technology on a Flexmap 3D Analyzer.

RESULTS

Serum CHI3L1 levels did not differ significantly from HC. We identified a positive correlation between CHI3L1 levels and relapses during treatment.

CONCLUSION

Our findings suggest that there are no differences in serum CHI3L1 levels between BMS patients and HC. However, serum CHI3L1 levels are sensitive to clinical inflammatory activity and may be associated with relapses in BMS patients.

How Early Is Early Multiple Sclerosis?

The development and further optimization of the diagnostic criteria for multiple sclerosis (MS) emphasize the establishment of an early and accurate diagnosis. So far, numerous studies have revealed the significance of early treatment administration for MS and its association with slower disease progression and better late outcomes of the disease with regards to disability accumulation. However, according to current research results, both neuroinflammatory and neurodegenerative processes may exist prior to symptom initiation. Despite the fact that a significant proportion of individuals with radiologically isolated syndrome (RIS) progress to MS, currently, there is no available treatment approved for RIS. Therefore, our idea of "early treatment administration" might be already late in some cases. In order to detect the individuals who will progress to MS, we need accurate biomarkers. In this review, we present notable research results regarding the underlying pathology of MS, as well as several potentially useful laboratory and neuroimaging biomarkers for the identification of high-risk individuals with RIS for developing MS. This review aims to raise clinicians' awareness regarding "subclinical" MS, enrich their understanding of MS pathology, and familiarize them with several potential biomarkers that are currently under investigation and might be used in clinical practice in the future for the identification of individuals with RIS at high risk for conversion to definite MS.

CHI3L1 signaling impairs hippocampal neurogenesis and cognitive function in autoimmune-mediated neuroinflammation

Chitinase-3-like protein 1 (CHI3L1) is primarily secreted by activated astrocytes in the brain and is known as a reliable biomarker for inflammatory central nervous system (CNS) conditions such as neurodegeneration and autoimmune disorders like neuromyelitis optica (NMO). NMO is an astrocyte disease caused by autoantibodies targeting the astroglial protein aquaporin 4 (AQP4) and leads to vision loss, motor deficits, and cognitive decline. In this study examining CHI3L1's biological function in neuroinflammation, we found that CHI3L1 expression correlates with cognitive impairment in our NMO patient cohort. Activated astrocytes secrete CHI3L1 in response to AQP4 autoantibodies, and this inhibits the proliferation and neuronal differentiation of neural stem cells. Mouse models showed decreased hippocampal neurogenesis and impaired learning behaviors, which could be rescued by depleting CHI3L1 in astrocytes. The molecular mechanism involves CHI3L1 engaging the CRTH2 receptor and dampening β-catenin signaling for neurogenesis. Blocking this CHI3L1/CRTH2/β-catenin cascade restores neurogenesis and improves cognitive deficits, suggesting the potential for therapeutic development in neuroinflammatory disorders.

Postoperative serum CHI3L1 level is associated with postoperative cognitive dysfunction in elderly patients after hip fracture surgery: A prospective observational study

Objectives

Postoperative cognitive dysfunction (POCD) is a common postoperative complication in older patients. Chitinase-3-like-1 protein (CHI3L1) is identified as a neuroinflammatory biomarker and impairs cognitive function. This study aimed to evaluate the association between serum levels of CHI3L1 and POCD and explore the levels of interleukin-6 (IL-6), IL-1β and C-reactive protein (CRP) in the elderly after total hip arthroplasty (THA).

Patients and methods

A total of 76 elderly patients undergoing THA were enrolled in the prospective observational study. Serum CHI3L1 levels were measured 1 day before and 1 day after surgery and other perioperative factors were also noted. The correlations between mediators of inflammation in the two groups were compared via Spearman correlation coefficients. The receiver operating characteristic (ROC) curves were implemented to analyze the predictive values of serum CHI3L1 and other inflammatory factors for POCD. And factors associated with POCD were analyzed by univariate and multivariate logistics.

Results

POCD was observed in 31.6% of patients 1 week after surgery. Postoperative serum CHI3L1 levels were higher in POCD patients than in non-POCD patients [1348.26(778.46-1889.77) VS 2322.86(1686.88-2517.35) ng/ml, P < 0.001]. Postoperative serum CHI3L1 level was positively correlated with postoperative IL-6 level (r = 0.284, P = 0.013). Compared with IL-6, IL-1β, and CRP, postoperative CHI3L1 level has the highest predictive value for POCD with the area under the curve (AUC) value of 0.779 according to the ROC curve. By the multivariate logistic regression analysis, elevated postoperative serum CHI3L1 level was found to be an independent risk factor for POCD 1 week after surgery (odds ratio = 1.204, 95% confidence interval = 1.087-1.332, P = 0.001).

Conclusion

Postoperative elevated serum CHI3L1 level was significantly associated with the incident of POCD, and positively correlated with postoperative IL-6 level in the elderly after THA. This biomarker may have potential utility for further elucidating the etiology of POCD.

Astrocytic Chitinase-3-like protein 1 in neurological diseases: Potential roles and future perspectives

Chitinase-3-like protein 1 (CHI3L1) is a secreted glycoprotein characterized by its ability to regulate multiple biological processes, such as the inflammatory response and gene transcriptional signaling activation. Abnormal CHI3L1 expression has been associated with multiple neurological disorders and serves as a biomarker for the early detection of several neurodegenerative diseases. Aberrant CHI3L1 expression is also reportedly associated with brain tumor migration and metastasis, as well as contributions to immune escape, playing important roles in brain tumor progression. CHI3L1 is synthesized and secreted mainly by reactive astrocytes in the central nervous system. Thus, targeting astrocytic CHI3L1 could be a promising approach for the treatment of neurological diseases, such as traumatic brain injury, ischemic stroke, Alzheimer's disease, Parkinson's disease, multiple sclerosis, amyotrophic lateral sclerosis, and glioma. Based on current knowledge of CHI3L1, we assume that it acts as a molecule mediating several signaling pathways driving the initiation and progression of neurological disorders. This narrative review is the first to introduce the potential roles of astrocytic CHI3L1 in neurological disorders. We also equally explore astrocytic CHI3L1 mRNA expression under physiological and pathological conditions. Inhibiting CHI3L1 and disrupting its interaction with its receptors through multiple mechanisms of action are briefly discussed. These endeavors highlight the pivotal roles of astrocytic CHI3L1 in neurological disorders and could contribute to the development of effective inhibitors based on the strategy of structure-based drug discovery, which could be an attractive therapeutic approach for neurological disease treatment.

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.

Biomarkers in autoimmune diseases of the central nervous system

The autoimmune diseases of the central nervous system (CNS) represent individual heterogeneity with different disease entities. Although clinical and imaging features make it possible to characterize larger patient cohorts, they may not provide sufficient evidence to detect disease activity and response to disease modifying drugs. Biomarkers are becoming a powerful tool due to their objectivity and easy access. Biomarkers may indicate various aspects of biological processes in healthy and/or pathological states, or as a response to drug therapy. According to the clinical features described, biomarkers are usually classified into predictive, diagnostic, monitoring and safety biomarkers. Some nerve injury markers, humoral markers, cytokines and immune cells in serum or cerebrospinal fluid have potential roles in disease severity and prognosis in autoimmune diseases occurring in the CNS, which provides a promising approach for clinicians to early intervention and prevention of future disability. Therefore, this review mainly summarizes the potential biomarkers indicated in autoimmune disorders of the CNS.

Recent Progress in the Identification of Early Transition Biomarkers from Relapsing-Remitting to Progressive Multiple Sclerosis

Despite extensive research into the pathophysiology of multiple sclerosis (MS) and recent developments in potent disease-modifying therapies (DMTs), two-thirds of relapsing-remitting MS patients transition to progressive MS (PMS). The main pathogenic mechanism in PMS is represented not by inflammation but by neurodegeneration, which leads to irreversible neurological disability. For this reason, this transition represents a critical factor for the long-term prognosis. Currently, the diagnosis of PMS can only be established retrospectively based on the progressive worsening of the disability over a period of at least 6 months. In some cases, the diagnosis of PMS is delayed for up to 3 years. With the approval of highly effective DMTs, some with proven effects on neurodegeneration, there is an urgent need for reliable biomarkers to identify this transition phase early and to select patients at a high risk of conversion to PMS. The purpose of this review is to discuss the progress made in the last decade in an attempt to find such a biomarker in the molecular field (serum and cerebrospinal fluid) between the magnetic resonance imaging parameters and optical coherence tomography measures.

An Association of Chitinase-3 Like-Protein-1 With Neuronal Deterioration in Multiple Sclerosis

Elevated levels of Chitinase-3-like protein-1 (CHI3L1) in cerebrospinal fluid have previously been linked to inflammatory activity and disease progression in multiple sclerosis (MS) patients. This study aimed to investigate the presence of CHI3L1 in the brains of MS patients and in the cuprizone model in mice (CPZ), a model of toxic/metabolic demyelination and remyelination in different brain areas. In MS gray matter (GM), CHI3L1 was detected primarily in astrocytes and in a subset of pyramidal neurons. In neurons, CHI3L1 immunopositivity was associated with lipofuscin-like substance accumulation, a sign of cellular aging that can lead to cell death. The density of CHI3L1-positive neurons was found to be significantly higher in normal-appearing MS GM tissue compared to that of control subjects (p  =  .014). In MS white matter (WM), CHI3L1 was detected in astrocytes located within lesion areas, as well as in perivascular normal-appearing areas and in phagocytic cells from the initial phases of lesion development. In the CPZ model, the density of CHI3L1-positive cells was strongly associated with microglial activation in the WM and choroid plexus inflammation. Compared to controls, CHI3L1 immunopositivity in WM was increased from an early phase of CPZ exposure. In the GM, CHI3L1 immunopositivity increased later in the CPZ exposure phase, particularly in the deep GM region. These results indicate that CHI3L1 is associated with neuronal deterioration, pre-lesion pathology, along with inflammation in MS.

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.

Toward a Combination of Biomarkers for Molecular Characterization of Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune disease affecting the central nervous system associated with chronic inflammation, demyelination, and axonal damage. MS is a highly heterogeneous disease that leads to discrepancies regarding the clinical appearance, progression, and therapy response of patients. Therefore, there is a strong unmet need for clinically relevant biomarkers capable of recapitulating the features of the disease. Experimental autoimmune encephalomyelitis (EAE) is a valuable model for studying the pathophysiology of MS as it recapitulates the main hallmarks of the disease: inflammation, blood-brain barrier (BBB) disruption, gliosis, myelin damage, and repair mechanisms. In this study, we used the EAE-PLP animal model and established a molecular RNA signature for each phase of the disease (onset, peak, remission). We compared variances of expression of known biomarkers by RT-qPCR in the brain and spinal cord of sham and EAE animals monitoring each of the five hallmarks of the disease. Using magnetic cell isolation technology, we isolated microglia and oligodendrocytes of mice of each category, and we compared the RNA expression variations. We identify genes deregulated during a restricted time frame, and we provide insight into the timing and interrelationships of pathological disease processes at the organ and cell levels.

Pathogenic autoantibodies in multiple sclerosis - from a simple idea to a complex concept

The role of autoantibodies in multiple sclerosis (MS) has been enigmatic since the first description, many decades ago, of intrathecal immunoglobulin production in people with this condition. Some studies have indicated that MS pathology is heterogeneous, with an antibody-associated subtype - characterized by B cells (in varying quantities), antibodies and complement - existing alongside other subtypes with different pathologies. However, subsequent evidence suggested that some cases originally diagnosed as MS with autoantibody-mediated demyelination were more likely to be neuromyelitis optica spectrum disorder or myelin oligodendrocyte glycoprotein antibody-associated disease. These findings raise the important question of whether an autoantibody-mediated MS subtype exists and whether pathogenic MS-associated autoantibodies remain to be identified. Potential roles of autoantibodies in MS could range from specific antibodies defining the disease to a non-disease-specific amplification of cellular immune responses and other pathophysiological processes. In this Perspective, we review studies that have attempted to identify MS-associated autoantibodies and provide our opinions on their possible roles in the pathophysiology of MS.

Patient's perspective in clinical practice to assess and predict disability in multiple sclerosis

The information provided by a person with multiple sclerosis (MS) may anticipate changes in the course of the disease. To explore the role of a set of standardized patient-reported outcomes (PRO) in predicting disability progression in MS an observational study was conducted in two cohorts of 30 and 86 persons with progressive MS (pwPMS) and relapsing MS (pwRMS), respectively. The associations between baseline clinical, biochemical variables and results on MS quality of life scale (MusiQol), Modified Fatigue Impact Scale (MFIS) and Beck Depression Inventory II (BDI-II) were analyzed. The progression of disability after 2 years of follow-up in pwRMS was investigated. We show that PRO differentiated pwRMS and pwPMS cohorts with lower MusiQoL and higher MFIS and BDI-II scores in the latter. Only MFIS was correlated with disability in pwRMS and high scores in the physical MFIS domain associated with worse performance in 9HPT, and a trend in T25FW and SDMT. Instead, the cognitive MFIS domain was correlated with CHI3L1 in cerebrospinal fluid, a biomarker of progression. At the end of the study, global MFIS and BDI-II were found to be independent risk factors for disability independent of relapse. Although all PRO measures explored were altered in pwPMS, baseline MFIS discriminated current and prospective disability in pwRMS, identifying patients at risk of progression.

Lesion environments direct transplanted neural progenitors towards a wound repair astroglial phenotype in mice

Neural progenitor cells (NPC) represent potential cell transplantation therapies for CNS injuries. To understand how lesion environments influence transplanted NPC fate in vivo, we derived NPC expressing a ribosomal protein-hemagglutinin tag (RiboTag) for transcriptional profiling of transplanted NPC. Here, we show that NPC grafted into uninjured mouse CNS generate cells that are transcriptionally similar to healthy astrocytes and oligodendrocyte lineages. In striking contrast, NPC transplanted into subacute CNS lesions after stroke or spinal cord injury in mice generate cells that share transcriptional, morphological and functional features with newly proliferated host astroglia that restrict inflammation and fibrosis and isolate lesions from adjacent viable neural tissue. Our findings reveal overlapping differentiation potentials of grafted NPC and proliferating host astrocytes; and show that in the absence of other interventions, non-cell autonomous cues in subacute CNS lesions direct the differentiation of grafted NPC towards a naturally occurring wound repair astroglial phenotype.

IL-2, IL-6 and chitinase 3-like 2 might predict early relapse activity in multiple sclerosis

Background

The possibility to better predict the severity of the disease in a patient newly diagnosed with multiple sclerosis would allow the treatment strategy to be personalized and lead to better clinical outcomes. Prognostic biomarkers are highly needed.

Objective

To assess the prognostic value of intrathecal IgM synthesis, cerebrospinal fluid and serum IL-2, IL-6, IL-10, chitinase 3-like 2 and neurofilament heavy chains obtained early after the onset of the disease.

Methods

58 patients after the first manifestation of multiple sclerosis were included. After the initial diagnostic assessment including serum and cerebrospinal fluid biomarkers, all patients initiated therapy with either glatiramer acetate, teriflunomide, or interferon beta. To assess the evolution of the disease, we followed the patients clinically and with MRI for two years.

Results

The IL-2:IL-6 ratio (both in cerebrospinal fluid) <0.48 (p = 0.0028), IL-2 in cerebrospinal fluid ≥1.23pg/ml (p = 0.026), and chitinase 3-like 2 in cerebrospinal fluid ≥7900pg/ml (p = 0.033), as well as baseline EDSS ≥1.5 (p = 0.0481) and age <22 (p = 0.0312), proved to be independent markers associated with shorter relapse free intervals.

Conclusion

The IL-2:IL-6 ratio, IL-2, and chitinase 3-like 2 (all in cerebrospinal fluid) might be of value as prognostic biomarkers in early phases of multiple sclerosis.

Fluid phase biomarkers in multiple sclerosis

PURPOSE OF REVIEW

Multiple sclerosis (MS) is highly heterogenic disorder with respect to clinical course, diagnosis, and treatment response. There is an urgent need to search for simply and reliable fluid body biomarker which would assist the diagnosis and prediction of clinical and treatment prognosis.

RECENT FINDINGS

'Traditional' MS biomarkers, with exception of cerebrospinal fluid oligoclonal bands, still are having limited clinical value. Therefore, there is growing interest in novel molecules and ingredients. The most robust results have been generated with regard to cerebrospinal fluid and serum levels of neurofilament light chains (NfL). However, there are still some limitations related to specificity of NfL which delays its use in everyday practice. We present a new approach to search for biomarkers involving extracellular RNA, particularly microRNA (miRNA), and small extracellular vesicles. MiRNA represents an important molecular mechanism influencing gene expression, including those involved in MS pathogenesis and extracellular vesicles transfer multiple cargo, including myelin molecules from parental cells of central nervous system to the long-distance targets.

SUMMARY

MiRNAs which control gene expression in cells involved in autoimmune processes in MS as well as extracellular vesicles transferring myelin content might generate a new promising categories of biomarkers of MS.

Biological Markers in Early Multiple Sclerosis: the Paved Way for Radiologically Isolated Syndrome

Radiologically Isolated Syndrome (RIS) is characterized by MRI-typical brain lesions fulfilling the 2009 Okuda criteria, detected in patients without clinical conditions suggestive of MS. Half of all RIS patients convert to MS within 10 years. The individual course of the disease, however, is highly variable with 12% of RIS converting directly to progressive MS. Demographic and imaging markers have been associated with the risk of clinical MS in RIS: male sex, younger age, infra-tentorial, and spinal cord lesions on the index scan and gadolinium-enhancing lesions on index or follow-up scans. Although not considered as a distinct MS phenotype, RIS certainly shares common pathological features with early active and progressive MS. In this review, we specifically focus on biological markers that may help refine the risk stratification of clinical MS and disability for early treatment. Intrathecal B-cell activation with cerebrospinal fluid (CSF) oligoclonal bands, elevated kappa free light chains, and cytokine production is specific to MS, whereas neurofilament light chain (NfL) levels reflect disease activity associated with neuroaxonal injury. Specific microRNA profiles have been identified in RIS converters in both CSF and blood. CSF levels of chitinases and glial acidic fibrillary protein (GFAP) reflecting astrogliosis might help predict the evolution of RIS to progressive MS. Innovative genomic, proteomic, and metabolomic approaches have provided several new candidate biomarkers to be explored in RIS. Leveraging data from randomized controlled trials and large prospective RIS cohorts with extended follow-up to identify, as early as possible, biomarkers for predicting greater disease severity would be invaluable for counseling patients, managing treatment, and monitoring.

Update on Multiple Sclerosis Molecular Biomarkers to Monitor Treatment Effects

Multiple sclerosis (MS) is an inflammatory and neurodegenerative disease of the central nervous system characterized by broad inter- and intraindividual heterogeneity. The relapse rate, disability progression, and lesion load assessed through MRI are used to detect disease activity and response to treatment. Although it is possible to standardize these characteristics in larger patient groups, so far, this has been difficult to achieve in individual patients. Easily detectable molecular biomarkers can be powerful tools, permitting a tailored therapy approach for MS patients. However, only a few molecular biomarkers have been routinely used in clinical practice as the validation process, and their transfer into clinical practice takes a long time. This review describes the characteristics of an ideal MS biomarker, the challenges of establishing new biomarkers, and promising molecular biomarkers from blood or CSF samples used to monitor MS treatment effects in clinical practice.