Axonal injury in asymptomatic individuals preceding onset of multiple sclerosis

Temporal Dynamics of Plasma Neurofilament Light in Blood Donors With Preclinical Multiple Sclerosis

BACKGROUND AND OBJECTIVES

Multiple sclerosis (MS) is a CNS disease, characterized by demyelination, inflammation, and neurodegeneration. Recent advances in technology allow measurement of the axonal damage marker neurofilament light chain in peripheral blood. Two studies have shown that patients with MS have elevated neurofilament light levels before their first symptom, but longitudinal studies are lacking. We aimed to investigate the intraindividual neurofilament light dynamics during the presymptomatic phase of MS.

METHODS

The Danish Blood Donor Study (DBDS) has stored plasma samples from blood donors for more than 10 years. We identified DBDS participants, who had subsequently been diagnosed with MS, and included all samples donated before their first demyelinating symptom (median 5.00 samples per case). As controls, we included 2 healthy donors per case. Plasma levels of neurofilament light were measured and compared with quality-of-life data. We used a Bayesian approach to derive estimates for the percentage of cases with presymptomatic increased neurofilament light levels.

RESULTS

We observed that 12 (17%, 95% CI 9%-28%) of 69 presymptomatic MS donors had intermittently increased neurofilament light levels preclinically. Increased levels were present up to 9 years before clinical onset, also in primary progressive MS. Healthy donors and presymptomatic MS donors with and without increased neurofilament light levels reported equally high physical and mental well-being. Model-based estimates suggested that 55% of cases (95% credible interval [28%-87%]) had experienced increased presymptomatic neurofilament light levels.

DISCUSSION

Patients with MS periodically sustain axonal injury up to 9 years before clinical onset, even in primary progressive disease. This most likely represents asymptomatic disease activity. Some or even all patients are affected by this intermittent axonal injury, prompting the need for further studies of the presymptomatic phase in relation to prognosis and as a therapeutic window of opportunity.

Migraine in the multiple sclerosis prodrome: a prospective nationwide cohort study in pregnant women

BACKGROUND

People with multiple sclerosis (MS) have an increased risk of migraine. However, little is known about migraine and other headaches during the prodromal phase (before MS symptom onset). Our objective was to study the risk of migraine in women with MS before MS onset.

METHODS

A nationwide, prospective cohort study of women participating in the Norwegian Mother, Father, and Child cohort study 1999-2008. The women reported the occurrence of migraine and other headaches prior to or during pregnancy. We identified women who later developed MS through data linkage with national health registries in 2018. We excluded women with an established MS diagnosis (n = 125) and women who had experienced their first clinical symptom of MS, but not yet received an MS diagnosis (n = 91). The reference group comprised all other women in the cohort (n = 85,292). We used logistic regression to estimate adjusted odds ratios (aORs) with 95% confidence intervals (95% CIs).

RESULTS

Two hundred and forty-six women developed MS during follow-up. Of these, 116 women had MS symptom onset after 1-5 years, 92 after 6-10 years, and 38 after 10 years. Migraine was more common among women who developed MS compared to the reference group, 18% vs 11%, aOR 1.6 (1.2-2.3), adjusted for age, smoking, socioeconomic status and overweight. The risk of other headaches was similar for women who developed MS compared to the reference group, 29% vs 27%, aOR 1.1 (0.8-1.4). Migraine was reported by 21 of 116 (18%) women with ≤ 5 years until MS symptom onset (aOR 1.7 [1.1-2.8]) and 19 of 92 (21%) women with 6-10 years until MS symptom onset (aOR 1.9 [1.1-2.8]. Only three of 38 (8%) women with > 10 years until MS symptom onset reported migraine, aOR 0.7 (0.2-2.2).

CONCLUSIONS

Women with MS have increased risk of migraine, but not other headaches, up to a decade before the onset of classical MS symptoms. This supports that migraine can be a symptom of the MS prodrome. Special attention in people with migraine may lead to earlier recognition of MS.

An autoantibody signature predictive for multiple sclerosis

Although B cells are implicated in multiple sclerosis (MS) pathophysiology, a predictive or diagnostic autoantibody remains elusive. In this study, the Department of Defense Serum Repository (DoDSR), a cohort of over 10 million individuals, was used to generate whole-proteome autoantibody profiles of hundreds of patients with MS (PwMS) years before and subsequently after MS onset. This analysis defines a unique cluster in approximately 10% of PwMS who share an autoantibody signature against a common motif that has similarity with many human pathogens. These patients exhibit antibody reactivity years before developing MS symptoms and have higher levels of serum neurofilament light (sNfL) compared to other PwMS. Furthermore, this profile is preserved over time, providing molecular evidence for an immunologically active preclinical period years before clinical onset. This autoantibody reactivity was validated in samples from a separate incident MS cohort in both cerebrospinal fluid and serum, where it is highly specific for patients eventually diagnosed with MS. This signature is a starting point for further immunological characterization of this MS patient subset and may be clinically useful as an antigen-specific biomarker for high-risk patients with clinically or radiologically isolated neuroinflammatory syndromes.

Seroreactivity against lytic, latent and possible cross-reactive EBV antigens appears on average 10 years before MS induced preclinical neuroaxonal damage

BACKGROUND

Multiple sclerosis (MS) and presymptomatic axonal injury appear to develop only after an Epstein-Barr virus (EBV) infection. This association remains to be confirmed across a broad preclinical time range, for lytic and latent EBV seroreactivity, and for potential cross-reacting antigens.

METHODS

We performed a case-control study with 669 individual serum samples obtained before clinical MS onset, identified through cross-linkage with the Swedish MS register. We assayed antibodies against EBV nuclear antigen 1 (EBNA1), viral capsid antigen p18, glycoprotein 350 (gp350), the potential cross-reacting protein anoctamin 2 (ANO2) and the level of sNfL, a marker of axonal injury.

RESULTS

EBNA1 (latency) seroreactivity increased in the pre-MS group, at 15-20 years before clinical MS onset, followed by gp350 (lytic) seroreactivity (p=0.001-0.009), ANO2 seropositivity appeared shortly after EBNA1-seropositivity in 16.7% of pre-MS cases and 10.0% of controls (p=0.001).With an average lag of almost a decade after EBV, sNfL gradually increased, mainly in the increasing subgroup of seropositive pre-MS cases (p=8.10-5 compared with non-MS controls). Seropositive pre-MS cases reached higher sNfL levels than seronegative pre-MS (p=0.038). In the EBNA1-seropositive pre-MS group, ANO2 seropositive cases had 26% higher sNfL level (p=0.0026).

CONCLUSIONS

Seroreactivity against latent and lytic EBV antigens, and in a subset ANO2, was detectable on average a decade before the appearance of a gradually increasing axonal injury occurring in the last decade before the onset of clinical MS. These findings strengthen the hypothesis of latent EBV involvement in the pathogenesis of MS.

Adverse Childhood Experiences and the Risk of Multiple Sclerosis Development: A Review of Potential Mechanisms

Adverse childhood experiences (ACEs), such as abuse, neglect, and household dysfunction, contribute to long-term systemic toxic stress and inflammation that may last well into adulthood. Such early-life stressors have been associated with increased susceptibility to multiple sclerosis (MS) in observational studies and with the development of experimental autoimmune encephalomyelitis in animal models. In this review, we summarize the evidence for an ACE-mediated increase in MS risk, as well as the potential mechanisms for this association. ACEs dysregulate neurodevelopment, stress responses, and immune reactivity; they also alter the interplay between the immune system and neural networks. All of this may be relevant for MS risk. We further discuss how ACEs induce epigenetic changes and how the toxic stress caused by ACEs may reactivate the Epstein-Barr Virus (EBV), a key risk factor for MS. We conclude by suggesting new initiatives to obtain further insights into this topic.

Human herpesvirus 6A and axonal injury before the clinical onset of multiple sclerosis

Recent research indicates that multiple sclerosis is preceded by a prodromal phase with elevated levels of serum neurofilament light chain (sNfL), a marker of axonal injury. The effect of environmental risk factors on the extent of axonal injury during this prodrome is unknown. Human herpesvirus 6A (HHV-6A) is associated with an increased risk of developing multiple sclerosis. The objective of this study was to determine if HHV-6A serostatus is associated with the level of sNfL in the multiple sclerosis prodrome, which would support a causative role of HHV-6A. A nested case-control study was performed by crosslinking multiple sclerosis registries with Swedish biobanks. Individuals with biobank samples collected before the clinical onset of multiple sclerosis were included as cases. Controls without multiple sclerosis were randomly selected, matched for biobank, sex, sampling date and age. Serostatus of HHV-6A and Epstein-Barr virus was analysed with a bead-based multiplex assay. The concentration of sNfL was analysed with single molecule array technology. The association between HHV-6A serology and sNfL was assessed by stratified t-tests and linear regressions, adjusted for Epstein-Barr virus serostatus and sampling age. Within-pair ratios of HHV-6A seroreactivity and sNfL were calculated for each case and its matched control. To assess the temporal relationship between HHV-6A antibodies and sNfL, these ratios were plotted against the time to the clinical onset of multiple sclerosis and compared using locally estimated scatterplot smoothing regressions with 95% confidence intervals (CI). Samples from 519 matched case-control pairs were included. In cases, seropositivity of HHV-6A was significantly associated with the level of sNfL (+11%, 95% CI 0.2-24%, P = 0.045) and most pronounced in the younger half of the cases (+24%, 95% CI 6-45%, P = 0.007). No such associations were observed among the controls. Increasing seroreactivity against HHV-6A was detectable before the rise of sNfL (significant within-pair ratios from 13.6 years versus 6.6 years before the clinical onset of multiple sclerosis). In this study, we describe the association between HHV-6A antibodies and the degree of axonal injury in the multiple sclerosis prodrome. The findings indicate that elevated HHV-6A antibodies both precede and are associated with a higher degree of axonal injury, supporting the hypothesis that HHV-6A infection may contribute to multiple sclerosis development in a proportion of cases.

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.

Epstein-Barr virus as a leading cause of multiple sclerosis: mechanisms and implications

Epidemiological studies have provided compelling evidence that multiple sclerosis (MS) is a rare complication of infection with the Epstein-Barr virus (EBV), a herpesvirus that infects more than 90% of the global population. This link was long suspected because the risk of MS increases markedly after infectious mononucleosis (symptomatic primary EBV infection) and with high titres of antibodies to specific EBV antigens. However, it was not until 2022 that a longitudinal study demonstrated that MS risk is minimal in individuals who are not infected with EBV and that it increases over 30-fold following EBV infection. Over the past few years, a number of studies have provided clues on the underlying mechanisms, which might help us to develop more targeted treatments for MS. In this Review, we discuss the evidence linking EBV to the development of MS and the mechanisms by which the virus is thought to cause the disease. Furthermore, we discuss implications for the treatment and prevention of MS, including the use of antivirals and vaccines.