Serum Neurofilament Light Chain Levels and Myelin Oligodendrocyte Glycoprotein Antibodies in Pediatric Acquired Demyelinating Syndromes

Role of soluble biomarkers in treating multiple sclerosis and neuroinflammatory conditions

Multiple sclerosis (MS) is a complex, chronic immune-mediated disease characterized by acute and progressive inflammatory damage of the central nervous system. MS manifests clinically with unpredictable neurological symptoms from focal inflammatory attacks as well as gradual neurodegeneration which contribute significantly to long-term disability progression. As treatment options advance, developing more personalized strategies capture heterogeneous mechanisms of injury which may be targeted or predict outcomes has been a focus of ongoing investigation. The role of soluble biomarkers has emerged as a pivotal tool to assist in these goals. Early promising candidates include neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP); these intermediate filaments that are expressed in neurons and astrocytes, respectively, are reliably measurable from blood samples and can reveal clinical and subclinical changes, as well as predict progression. Changes in these biomarkers can indicate a response to therapy, thus potentially be used as endpoints in clinical trials. Furthermore, recent research has identified a potential role of these and other soluble biomarkers in other neuroimmunological conditions including neuromyelitis spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein associated disease (MOGAD), autoimmune encephalitis, neurosarcoidosis, neuropsychiatric involvement in connective tissue disorders and vasculitides, and a host of neurodegenerative conditions. By integrating biomarker analysis into routine clinical assessments, healthcare providers may move toward a more nuanced and individualized care model, better equipped to meet the challenges posed by these multifaceted diseases. Understanding the dynamics of these biomarkers has many applications that can improve personalized medicine in MS.

The utility of serum neurofilament light chain in MOGAD: Current insights and future directions

BACKGROUND

Serum neurofilament light chain (sNfL) has become an increasingly established biomarker for monitoring in multiple sclerosis (MS). Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is a demyelinating disorder distinct from MS in terms of pathophysiology and treatment options, also presenting with demyelinating attacks that can result in permanent disability. Given its unpredictable disease course, the need for biomarkers reflective of the risk for poor clinical recovery or relapsing course is pressing. The purpose of this review is to summarize the current knowledge on sNfL levels in people with MOGAD, assess their utility for clinical practice and gain insights for future research.

METHODS

Embase, MEDLINE, Scopus, and CINAHL databases were searched following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations. Keywords used in the search included: (myelin oligodendrocyte glycoprotein OR MOG OR MOGAD) AND (neurofilament* OR neuro filament* OR NfL OR sNfL). This initial search generated 195 reports, 23 of which were original research articles investigating NfL levels in MOGAD patients, therefore meeting our inclusion criteria.

RESULTS

422 MOGAD patients were involved across all studies. Most studies revealed higher sNfL in MOGAD patients (n = 292) than in healthy controls (n = 3,172) with one study finding higher sNfL in MOGAD only during relapse. sNfL levels during attacks were similar when comparing MOGAD (n = 94) to MS (n = 256) and MOGAD (n = 149) to APQ4+ neuromyelitis optica spectrum disorder (APQ4+ NMOSD) (n = 214). MOGAD patients with brain lesions on magnetic resonance imaging (MRI) during a recent attack (n = 69 samples) had higher sNfL levels than patients without brain lesions (n = 78 samples). Median sNfL concentration was higher following clinical attacks (n = 69 samples) than in remission (n = 83 samples) in 3/5 studies. sNfL were higher at disease onset than subsequent attacks in 2 studies (n = 133 samples). Onset sNfL levels were not predictive of the likelihood of future relapse (relapsing: n = 15, monophasic: n = 18). A positive correlation was found between sNfL levels and attack severity assessed through various disability scales (n = 202), but not with the severity of acute or residual visual acuity (n = 45 eyes), or with residual retinal thickness among subjects with the optic neuritis (ON) phenotype (n = 11 eyes). The sGFAP/sNfL ratio showed utility in discriminating MOGAD from other autoimmune demyelinating diseases in two studies (MOGAD: n = 56, APQ4+ NMOSD: n = 66, MS: n = 31).

DISCUSSION

sNfL levels at presentation have limited utility in distinguishing MOGAD from other demyelinating disorders, but their combination with other biomarkers might improve their diagnostic utility. sNfL levels are higher in brain/spinal cord presentations than optic neuritis, correlating with clinical severity of these phenotypes but less so with the severity of visual outcome. Further studies should clarify the utility of sNfL as a biomarker for MOGAD, particularly in relation to long-term outcomes and imaging markers of central nervous system damage. Standardized sNfL testing parameters will improve study comparability and clinical application.

Assessment of axonal injury in multiple sclerosis: combined analysis of serum light-chain neurofilaments and diffusion tensor imaging

Background

Multiple sclerosis (MS) is a chronic neuroinflammatory condition characterised by demyelination and axonal damage in the central nervous system. Diffusion tensor imaging (DTI) enables non-invasive investigation of microstructural white matter alterations, while serum neurofilament light chain (NFL) holds promise as a fluid biomarker of axonal injury.

Objectives

To use DTI and serum NFL measurements to evaluate white matter pathology in patients with MS and explore the relationship between in vivo imaging and biochemical indicators of axonal damage.

Methods

41 patients with relapse-remitting MS and 41 age-matched healthy controls underwent brain MRI including DTI acquisition. Serum samples were analysed for NFL concentrations using ELISA. Region of interest analysis was conducted to derive DTI metrics including fractional anisotropy, mean diffusivity, axial diffusivity and radial diffusivity. Correlational analyses were used to explore the associations between the imaging and biochemical indices.

Results

Patients exhibited significantly elevated serum NFL levels and altered DTI metrics compared with controls, indicative of axonal/myelin pathology. DTI parameters were positively correlated with serum NFL concentration (p value<0.0001). Visual analogue scale scores demonstrated a significant positive relationship between DTI metrics and NFL, validating their potential as radiological and fluid-based markers of symptom severity.

Conclusions

Combined DTI and serum NFL measurements may enhance the evaluation of axonal injury in MS by providing complementary in vivo and biochemical perspectives. The corresponding changes observed between the modalities support their utility as non-invasive biomarkers reflecting pathophysiological processes and clinical status in MS. Larger validation cohorts are needed to determine the clinical applicability.

Serum levels of neurofilament light chains in pediatric multiple sclerosis: a systematic review and meta-analysis

BACKGROUND

Multiple sclerosis is a neuro-inflammatory disease that affects adults and children and causes somatic and cognitive symptoms. Diagnosis after the first clinical symptoms is challenging, involves laboratory and magnetic resonance imaging work-up and is often inconclusive unless subsequent clinical attacks occur. Neurofilament light chains are structural proteins within neurons. Levels of this marker in cerebrospinal fluid, plasma and serum are consistently higher in patients with an initial clinical demyelinating attack that later go on to develop multiple sclerosis. Evidence concerning serum levels of this biomarker in children with multiple sclerosis is scarce. Our aim is to review and analyze the evidence available for patients with multiple sclerosis, under the age of 18.

METHODS

We conducted a systematic search of PubMed/Medline, Embase, Cochrane Database, and ProQuest. Human studies that provided data on serum levels of Neurofilament light chains in pediatric patients with MS, measured at the time of the first demyelinating attack and before treatment were included in meta-analysis.

RESULTS

Three studies satisfied the inclusion criteria. 157 pediatric patients with multiple sclerosis and 270 hospital-based controls that did not present with this condition were included in the analysis. A fixed effects meta-analysis showed that the standardized mean difference between patients and controls is 1.82, with a 95% confidence interval of [1.56-2.08].

CONCLUSION

Pediatric patients with multiple sclerosis show higher levels of serum neurofilament light chains at their first clinical demyelinating attack compared to pediatric hospital-based controls.

High serum neurofilament levels are observed close to disease activity events in pediatric-onset MS and MOG antibody-associated diseases

BACKGROUND

Serum neurofilament light chain (sNfL) is an emerging multiple sclerosis (MS) biomarker which measures neuro-axonal damage. However, understanding its temporal association with disease activity in pediatric-onset MS (POMS) and Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) remains limited.

OBJECTIVE

To investigate the association of sNfL levels and time from disease activity in children with MS and MOGAD.

METHODS

POMS and MOGAD cases with onset before 18 years of age were enrolled at the University of California San Francisco (UCSF) Regional Pediatric MS Center. Frequency-matched healthy subjects were recruited from general pediatric clinics. Serum samples were tested for MOG-IgG at Mayo Clinic using a live cell-based fluorescent activated cell sorting assay. sNfL levels were measured using single-molecule array (Simoa) technology measured in pg/mL. Data on demographics, clinical features, MRI, CSF, and treatment data were collected by chart review.

RESULTS

We included 201 healthy controls healthy controls, 142 POMS, and 20 confirmed MOGAD cases with available sNfL levels. The median (IQR) age at the time of sampling was 15.6 (3.9), 15.5 (3.1), and 8.8 (4.1) years for controls, POMS, and MOGAD, respectively. Median sNfL levels (pg/ml) were higher in POMS (19.6) and MOGAD (32.7) cases compared to healthy controls (3.9) (p<0.001). sNfL levels ≥100 pg/ml were only detected within four months of a clinical event or MRI activity in both POMS and MOGAD cases. In addition, sNfL levels were higher in POMS patients with new/enlarged T2 and gadolinium-enhanced lesions than those without MRI activity within four months of sampling in POMS cases.

CONCLUSION

High sNfL levels were observed close to clinical or MRI events in POMS and MOGAD. Our findings support sNfL as a biomarker of disease activity in pediatric demyelinating disorders.

Linking Plasma Amyloid Beta and Neurofilament Light Chain to Intracortical Myelin Content in Cognitively Normal Older Adults

Evidence suggests that lightly myelinated cortical regions are vulnerable to aging and Alzheimer’s disease (AD). However, it remains unknown whether plasma markers of amyloid and neurodegeneration are related to deficits in intracortical myelin content, and whether this relationship, in turn, is associated with altered patterns of resting-state functional connectivity (rs-FC). To shed light into these questions, plasma levels of amyloid-β fragment 1–42 (Aβ_1–42) and neurofilament light chain (NfL) were measured using ultra-sensitive single-molecule array (Simoa) assays, and the intracortical myelin content was estimated with the ratio T1-weigthed/T2-weighted (T1w/T2w) in 133 cognitively normal older adults. We assessed: (i) whether plasma Aβ_1–42 and/or NfL levels were associated with intracortical myelin content at different cortical depths and (ii) whether cortical regions showing myelin reductions also exhibited altered rs-FC patterns. Surface-based multiple regression analyses revealed that lower plasma Aβ_1–42 and higher plasma NfL were associated with lower myelin content in temporo-parietal-occipital regions and the insular cortex, respectively. Whereas the association with Aβ_1–42 decreased with depth, the NfL-myelin relationship was most evident in the innermost layer. Older individuals with higher plasma NfL levels also exhibited altered rs-FC between the insula and medial orbitofrontal cortex. Together, these findings establish a link between plasma markers of amyloid/neurodegeneration and intracortical myelin content in cognitively normal older adults, and support the role of plasma NfL in boosting aberrant FC patterns of the insular cortex, a central brain hub highly vulnerable to aging and neurodegeneration.

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.