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

The expanding clinical and genetic spectrum of DYNC1H1-related disorders

Intracellular trafficking involves an intricate machinery of motor complexes, including the dynein complex, to shuttle cargo for autophagolysosomal degradation. Deficiency in dynein axonemal chains, as well as cytoplasmic light and intermediate chains, have been linked with ciliary dyskinesia and skeletal dysplasia. The cytoplasmic dynein 1 heavy chain protein (DYNC1H1) serves as a core complex for retrograde trafficking in neuronal axons. Dominant pathogenic variants in DYNC1H1 have been previously implicated in peripheral neuromuscular disorders (NMD) and neurodevelopmental disorders (NDD). As heavy-chain dynein is ubiquitously expressed, the apparent selectivity of heavy chain dyneinopathy for motor neuronal phenotypes remains currently unaccounted for. Here, we aimed to evaluate the full DYNC1H1-related clinical, molecular and imaging spectrum, including multisystem features and novel phenotypes presenting throughout life. We identified 47 cases from 43 families with pathogenic heterozygous variants in DYNC1H1 (aged 0-59 years) and collected phenotypic data via a comprehensive standardized survey and clinical follow-up appointments. Most patients presented with divergent and previously unrecognized neurological and multisystem features, leading to significant delays in genetic testing and establishing the correct diagnosis. Neurological phenotypes include novel autonomic features, previously rarely described behavioral disorders, movement disorders and periventricular lesions. Sensory neuropathy was identified in nine patients (median age of onset 10.6 years), of which five were only diagnosed after the second decade of life, and three had a progressive age-dependent sensory neuropathy. Novel multisystem features included primary immunodeficiency, bilateral sensorineural hearing loss, organ anomalies and skeletal manifestations, resembling the phenotypic spectrum of other dyneinopathies. We also identified an age-dependent biphasic disease course with developmental regression in the first decade and, following a period of stability, neurodegenerative progression after the second decade of life. Of note, we observed several cases in whom neurodegeneration appeared to be prompted by intercurrent systemic infections with double-stranded DNA viruses (Herpesviridae) or single-stranded RNA viruses (Ross River fever, SARS-CoV-2). Moreover, the disease course appeared to be exacerbated by viral infections regardless of age and/or severity of neurodevelopmental disorder manifestations, indicating a role of dynein in anti-viral immunity and neuronal health. In summary, our findings expand the clinical, imaging and molecular spectrum of pathogenic DYNC1H1 variants beyond motor neuropathy disorders and suggest a life-long continuum and age-related progression due to deficient intracellular trafficking. This study will facilitate early diagnosis and improve counselling and health surveillance of affected patients.

Multiple sclerosis and infection: history, EBV, and the search for mechanism

SUMMARYInfection has long been hypothesized as the cause of multiple sclerosis (MS), and recent evidence for Epstein-Barr virus (EBV) as the trigger of MS is clear and compelling. This clarity contrasts with yet uncertain viral mechanisms and their relation to MS neuroinflammation and demyelination. As long as this disparity persists, it will invigorate virologists, molecular biologists, immunologists, and clinicians to ascertain how EBV potentiates MS onset, and possibly the disease's chronic activity and progression. Such efforts should take advantage of the diverse body of basic and clinical research conducted over nearly two centuries since the first clinical descriptions of MS plaques. Defining the contribution of EBV to the complex and multifactorial pathology of MS will also require suitable experimental models and techniques. Such efforts will broaden our understanding of virus-driven neuroinflammation and specifically inform the development of EBV-targeted therapies for MS management and, ultimately, prevention.

Human herpesvirus 6 (HHV-6) encephalitis secondary to chimeric antigen receptor (CAR)-T cell therapy

BACKGROUND

Human herpesvirus (HHV)-6 encephalitis secondary to chimeric antigen receptor (CAR)-T cell therapyis relatively rare in clinical practice and needs to be differentiated from immune effector cell-associatedneurotoxicity syndrome (ICANS).

METHODS

We retrospectively reported a case of HHV-6 encephalitis secondary to CAR-T cell therapy.

RESULTS

A male patient from China with diffuse large B-cell lymphoma underwent chimeric CAR-T cell therapy anddeveloped a generalized rash on the 8th day, followed by cognitive changes, memory loss, and disorientation onthe 14th day after CAR-T cell therapy. Initially, ICANS was suspected. A lumbar puncture was performed on the 18th day. The cerebrospinal fluid (CSF) analysis revealed slightly elevated protein levels and a high presence of HHV-6B sequences by mNGS. Brain MRI showed bilateral hippocampal abnormalities. The patient was ultimatelydiagnosed with HHV-6 encephalitis and treated with ganciclovir and dexamethasone. After one week of treatment,follow-up CSF analysis showed a reduction in HHV-6B sequences. The patient was discharged with improvedmemory and orientation.

CONCLUSION

HHV-6 encephalitis secondary to CAR-T cell therapy may be easily confused with ICANS. Timely andaggressive diagnostic procedures, such as mNGS of CSF and cranial imaging, along with prompt antiviral therapy,are crucial for improving patient outcomes.

Neuroaxonal damage in natalizumab-treated MS patients: The role of JCV antibody titres

BACKGROUND

While John Cunningham virus (JCV) is known to cause neuronal damage in progressive multifocal leukoencephalopathy (PML) among natalizumab-treated MS patients, its association with axonal loss in non-PML conditions remains unclear.

METHODS

In a cohort of 128 natalizumab-treated MS patients, serum neurofilament (sNfL) levels and JCV antibody titres were measured.

RESULTS

Among 128 patients (mean age = 38.4 years, 71.9% female), 51 (40%) were JCV positive. NfL levels increased by 15.3% for JCV index <0.7 (95% confidence interval [CI] = 0.963-1.381), by 18.6% for index 0.7-1.5 (95% CI = 1.009-1.394) and by 21.1% for index >1.5 (95% CI = 1.040-1.409) compared to JCV negative patients.

CONCLUSION

These findings indicate a potential link between JCV burden and neuroaxonal degeneration in natalizumab-treated MS patients.

Rubella virus seropositivity after infection or vaccination as a risk factor for multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) is a demyelinating disease affecting millions of people worldwide. Hereditary susceptibility and environmental factors contribute to disease risk. Infection with Epstein-Barr virus (EBV) and human herpesvirus 6A (HHV-6A) have previously been associated with MS risk. Other neurotropic viruses, such as rubella virus (RV), are possible candidates in MS aetiopathogenesis, but previous results are limited and conflicting.

METHODS

In this nested case-control study of biobank samples in a Swedish cohort, we analysed the serological response towards RV before the clinical onset of MS with a bead-based multiplex assay in subjects vaccinated and unvaccinated towards RV. The association between RV seropositivity and MS risk was analysed with conditional logistic regression.

RESULTS

Seropositivity towards RV was associated with an increased risk of MS for unvaccinated subjects, even when adjusting for plausible confounders including EBV, HHV-6A, cytomegalovirus and vitamin D (adjusted odds ratio [AOR] = 4.0, 95% confidence interval [CI] 1.8-8.8). Cases also had stronger antibody reactivity towards rubella than controls, which was not seen for other neurotropic viruses such as herpes simplex or varicella zoster. Furthermore, we observed an association between RV seropositivity and MS in vaccinated subjects. However, this association was not significant when adjusting for the aforementioned confounders (AOR = 1.7, 95% CI 1.0-2.9).

CONCLUSIONS

To our knowledge, these are the first reported associations between early RV seropositivity and later MS development. This suggests a broadening of the virus hypothesis in MS aetiology, where molecular mimicry between rubella epitopes and human central nervous system molecules could be an attractive possible mechanism.

Endogenous retroviruses in multiple sclerosis: A network-based etiopathogenic model

The present perspective article proposes an etiopathological model for multiple sclerosis pathogenesis and progression associated with the activation of human endogenous retroviruses. We reviewed preclinical, clinical, epidemiological, and evolutionary evidence indicating how the complex, multi-level interplay of genetic traits and environmental factors contributes to multiple sclerosis. We propose that endogenous retroviruses transactivation acts as a critical node in disease development. We also discuss the rationale for combined anti-retroviral therapy in multiple sclerosis as a disease-modifying therapeutic strategy. Finally, we propose that the immuno-pathogenic process triggered by endogenous retrovirus activation can be extended to aging and aging-related neurodegeneration. In this regard, endogenous retroviruses can be envisioned to act as epigenetic noise, favoring the proliferation of disorganized cellular subpopulations and accelerating system-specific "aging". Since inflammation and aging are two sides of the same coin (plastic dis-adaptation to external stimuli with system-specific degree of freedom), the two conditions may be epiphenomenal products of increased epigenomic entropy. Inflammation accelerates organ-specific aging, disrupting communication throughout critical systems of the body and producing symptoms. Overlapping neurological symptoms and syndromes may emerge from the activity of shared molecular networks that respond to endogenous retroviruses' reactivation.

Cytomegalovirus, Epstein-Barr Virus, Herpes Simplex Virus, and Varicella Zoster Virus Infection Dynamics in People with Multiple Sclerosis from Northern Italy

Previous exposure to Epstein-Barr virus (EBV) is strongly associated with the development of multiple sclerosis (MS). By contrast, past cytomegalovirus (CMV) infection may have no association, or be negatively associated with MS. This study aimed to investigate the associations of herpesvirus infections with MS in an Italian population. Serum samples (n = 200) from Italian people with multiple sclerosis (PwMS) classified as the relapsing-and-remitting clinical phenotype and (n = 137) healthy controls (HCs) were obtained from the CRESM Biobank, Orbassano, Italy. Both PwMS and HCs samples were selected according to age group (20-39 years, and 40 or more years) and sex. EBV virus capsid antigen (VCA) IgG, EBV nucleic acid-1 antigen (EBNA-1) IgG, CMV IgG, herpes simplex virus (HSV) IgG, and varicella zoster virus (VZV) IgG testing was undertaken using commercial ELISAs. EBV VCA IgG and EBNA-1 IgG seroprevalences were 100% in PwMS and 93.4% and 92.4%, respectively, in HCs. EBV VCA IgG and EBNA-1 IgG levels were higher (p < 0.001) in PwMS compared with HCs. For PwMS, the EBNA-1 IgG levels decreased with age, particularly in females. The CMV IgG seroprevalence was 58.7% in PwMS and 62.9% in HCs. CMV IgG seroprevalence increased with age. The HSV IgG seroprevalence was 71.2% in PwMS and 70.8% in HCs. HSV IgG levels were lower (p = 0.0005) in PwMS compared with HCs. VZV IgG seroprevalence was 97.5% in PwMS and 98.5% in HCs. In the population studied, several herpesvirus infections markers may have been influenced by the age and sex of the groups studied. The lack of a negative association of MS with CMV infection, and the observation of lower levels of HSV IgG in PwMS compared with HCs are findings worthy of further investigation.

Peripheral GFAP and NfL as early biomarkers for dementia: longitudinal insights from the UK Biobank

BACKGROUND

Peripheral glial fibrillary acidic protein (GFAP) and neurofilament light chain (NfL) are sensitive markers of neuroinflammation and neuronal damage. Previous studies with highly selected participants have shown that peripheral GFAP and NfL levels are elevated in the pre-clinical phase of Alzheimer's disease (AD) and dementia. However, the predictive value of GFAP and NfL for dementia requires more evidence from population-based cohorts.

METHODS

This was a prospective cohort study to evaluate UK Biobank participants enrolled from 2006 to 2010 using plasma GFAP and NfL measurements measured by Olink Target Platform and prospectively followed up for dementia diagnosis. Primary outcome was the risk of clinical diagnosed dementia. Secondary outcomes were cognition. Linear regression was used to assess the associations between peripheral GFAP and NfL with cognition. Cox proportional hazard models with cross-validations were used to estimate associations between elevated GFAP and NfL with risk of dementia. All models were adjusted for covariates.

RESULTS

A subsample of 48,542 participants in the UK Biobank with peripheral GFAP and NfL measurements were evaluated. With an average follow-up of 13.18 ± 2.42 years, 1312 new all-cause dementia cases were identified. Peripheral GFAP and NfL increased up to 15 years before dementia diagnosis was made. After strictly adjusting for confounders, increment in NfL was found to be associated with decreased numeric memory and prolonged reaction time. A greater annualized rate of change in GFAP was significantly associated with faster global cognitive decline. Elevation of GFAP (hazard ratio (HR) ranges from 2.25 to 3.15) and NfL (HR ranges from 1.98 to 4.23) increased the risk for several types of dementia. GFAP and NfL significantly improved the predictive values for dementia using previous models (area under the curve (AUC) ranges from 0.80 to 0.89, C-index ranges from 0.86 to 0.91). The AD genetic risk score and number of APOE*E4 alleles strongly correlated with GFAP and NfL levels.

CONCLUSIONS

These results suggest that peripheral GFAP and NfL are potential biomarkers for the early diagnosis of dementia. In addition, anti-inflammatory therapies in the initial stages of dementia may have potential benefits.

Serologic Response to the Epstein-Barr Virus Peptidome and the Risk for Multiple Sclerosis

Importance

It remains unclear why only a small proportion of individuals infected with the Epstein-Barr virus (EBV) develop multiple sclerosis (MS) and what the underlying mechanisms are.

Objective

To assess the serologic response to all EBV peptides before the first symptoms of MS occur, determine whether the disease is associated with a distinct immune response to EBV, and evaluate whether specific EBV epitopes drive this response.

Design, Setting, and Participants

In this prospective, nested case-control study, individuals were selected among US military personnel with serum samples stored in the US Department of Defense Serum Repository. Individuals with MS had serum collected at a median 1 year before onset (reported to the military in 2000-2011) and were matched to controls for age, sex, race and ethnicity, blood collection, and military branch. No individuals were excluded. The data were analyzed between September 1, 2022, and August 31, 2023.

Exposure

Antibodies (enrichment z scores) to the human virome measured using VirScan (phage-displayed immunoprecipitation and sequencing).

Main Outcome and Measure

Rate ratios (RRs) for MS for antibodies to 2263 EBV peptides (the EBV peptidome) were estimated using conditional logistic regression, adjusting for total anti-EBV nuclear antigen 1 (EBNA-1) antibodies, which have consistently been associated with a higher MS risk. The role of antibodies against other viral peptides was also explored.

Results

A total of 30 individuals with MS were matched with 30 controls. Mean (SD) age at sample collection was 27.8 (6.5) years; 46 of 60 participants (76.7%) were male. The antibody response to the EBV peptidome was stronger in individuals with MS, but without a discernible pattern. The antibody responses to 66 EBV peptides, the majority mapping to EBNA antigens, were significantly higher in preonset sera from individuals with MS (RR of highest vs lowest tertile of antibody enrichment, 33.4; 95% CI, 2.5-448.4; P for trend = .008). Higher total anti-EBNA-1 antibodies were also associated with an elevated MS risk (top vs bottom tertile: RR, 27.6; 95% CI, 2.3-327.6; P for trend = .008). After adjusting for total anti-EBNA-1 antibodies, risk estimates from most EBV peptides analyses were attenuated, with 4 remaining significantly associated with MS, the strongest within EBNA-6/EBNA-3C, while the association between total anti-EBNA-1 antibodies and MS persisted.

Conclusion and Relevance

These findings suggest that antibody response to EBNA-1 may be the strongest serologic risk factor for MS. No single EBV peptide stood out as being selectively targeted in individuals with MS but not controls. Larger investigations are needed to explore possible heterogeneity of anti-EBV humoral immunity in MS.