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BackgroundAs remote infections with common herpes viruses are associated with modulation of the risk of multiple sclerosis (MS), we hypothesized that antibody concentrations against these viruses may further modify risk. As many common viruses are first encountered during childhood, pediatric MS offer a unique opportunity to investigate more closely their influence on susceptibility. Our aim was to determine if MS patients who were positive for these viruses had higher levels of antibodies to these viruses. We also assessed whether human leukocyte antigen (HLA)-DRB1*1501 genotype influenced viral antibody levels.MethodsAntibody response levels toward Epstein Barr virus (EBV), cytomegalovirus (CMV), and herpes simplex virus (HSV)-1, and HLA-DRB1*1501 status were determined in pediatric MS patients (n=189) and controls (n=38). Multivariate analyses were used, adjusted for age, gender, race, ethnicity and use of disease-modifying therapies.ResultsThe antibody concentrations against EBV (Epstein-Barr nuclear antigen 1 (EBNA-1), viral capsid antigen (VCA) and early antigen (EA)), CMV and HSV-1 were similar between pediatric MS patients and controls positive for seroconversion against the virus of interest. EBNA-1 humoral responses were higher in HLA-DRB1 positive individuals (p=0.005) whereas other viral humoral responses were similar in HLA-DRB1 positive and negative individuals.ConclusionAmong those positive for EBNA-1, MS patients did not have higher levels of antibody response to EBNA-1: however, titers for EBNA-1 were higher in those who were HLA-DRB1 positive. This suggests that genotype might influence the humoral response to EBV. Whether other genotypes influence antibody response to other viruses remains to be determined.

Reported rates of Epstein–Barr virus (EBV) seropositivity in children meeting multiple sclerosis (MS) diagnostic criteria are considerably lower than those reported in adult‐onset MS, putting in question a requisite role for EBV in MS development. As prior work preceded recognition of myelin oligodendrocyte glycoprotein‐associated disease (MOGAD), we assessed viral serologies in 251 children with incident demyelination and prospectively ascertained diagnoses. When MOGAD was serologically accounted for, the prevalence of EBV infection among MS children exceeded 90%, whereas remote EBV infection was not associated with MOGAD risk. Together, these findings substantiate EBV's role across the MS spectrum, and support distinct pathobiological mechanisms in MS versus MOGAD. ANN NEUROL 2024;95:700–705 [ABSTRACT FROM AUTHOR]

Objective: To identify gut microbiome features associated with MRI lesion burden in persons with pediatric‐onset multiple sclerosis (symptom onset <18 years). Methods: A cross‐sectional study involving the Canadian Paediatric Demyelinating Disease Network study participants. Gut microbiome features (alpha diversity, phylum‐ and genus‐level taxa) were derived using 16S rRNA sequencing from stool samples. T1‐ and T2‐weighted lesion volumes were measured on brain MRI obtained within 6 months of stool sample procurement. Associations between the gut microbiota and MRI metrics (cube‐root‐transformed) were assessed using standard and Lasso regression models. Results: Thirty‐four participants were included; mean ages at symptom onset and MRI were 15.1 and 19.0 years, respectively, and 79% were female. The T1‐ and T2‐weighted lesion volumes were not significantly associated with alpha diversity (age and sex‐adjusted p > 0.08). At the phylum level, high Tenericutes (relative abundance) was associated with higher T1 and T2 volumes (β coefficient = 0.25, 0.37) and high Firmicutes, Patescibacteria or Actinobacteria with lower lesion volumes (β coefficient = −0.30 to −0.07). At the genus level, high Ruminiclostridium, whereas low Coprococcus 3 and low Erysipelatoclostridium were associated with higher lesion volumes. Interpretation: Our study characterized the gut microbiota features associated with MRI lesion burden in pediatric‐onset MS, shedding light onto possible pathophysiological mechanisms. [ABSTRACT FROM AUTHOR]

Objective: The relationship between multiple sclerosis and the gut microbiome has been supported by animal models in which commensal microbes are required for the development of experimental autoimmune encephalomyelitis. However, observational study findings in humans have only occasionally converged when comparing multiple sclerosis cases and controls which may in part reflect confounding by comorbidities and disease duration. The study of microbiome in pediatric‐onset multiple sclerosis offers unique opportunities as it is closer to biological disease onset and minimizes confounding by comorbidities and environmental exposures. Methods: A multicenter case–control study in which 35 pediatric‐onset multiple sclerosis cases were 1:1 matched to healthy controls on age, sex, self‐reported race, ethnicity, and recruiting site. Linear mixed effects models, weighted correlation network analyses, and PICRUSt2 were used to identify microbial co‐occurrence networks and for predicting functional abundances based on marker gene sequences. Results: Two microbial co‐occurrence networks (one reaching significance after adjustment for multiple comparisons; q < 0.2) were identified, suggesting interdependent bacterial taxa that exhibited association with disease status. Both networks indicated a potentially protective effect of higher relative abundance of bacteria observed in these clusters. Functional predictions from the significant network suggested a contribution of short‐chain fatty acid producers through anaerobic fermentation pathways in healthy controls. Consistent family‐level findings from an independent Canadian‐US study (19 case/control pairs) included Ruminococaccaeae and Lachnospiraceae (p < 0.05). Macronutrient intake was not significantly different between cases and controls, minimizing the potential for dietary confounding. Interpretation: Our results suggest that short‐chain fatty acid producers may be important contributors to multiple sclerosis onset. [ABSTRACT FROM AUTHOR]