Background

Commensal gut microbes are known to affect host immune function and may be modifiable. Recent work suggests gut microbiota composition contributes to onset of MS; however, little is known about its contribution to MS disease activity.

Objectives

Estimate the association between gut microbiota and subsequent disease activity among individuals with pediatric-onset MS (pedMS) from the U.S. Network of Pediatric MS Centers.

Methods

Stool samples were collected from cases (MS symptom onset <18 years) and profiled using 16S rRNA sequencing of the V4 region. Amplicon sequence variants (ASVs) were identified using the Divisive Amplicon Denoising Algorithm-2 (DADA2). ASVs present in <20% of samples were removed. ASV clusters (modules) were identified using weighted genetic correlation network analysis (WGCNA) and sparCC transformation of ASV abundance. Cox proportional hazard recurrent event models were used to examine the relationship between individual ASVs and then ASV clusters, adjusted for age, sex, and disease modifying therapy (DMT) use.

Results

Of 53 pedMS cases, 72% were girls. At stool sample collection, the mean age was 15.5 years (SD: 2.7) and disease duration was 1.1 years (SD: 1.0). Less than half (45%) had one relapse and 30% had >1 relapse over the subsequent mean follow-up of 2.5 years (SD:1.3). Over this time, 91% used a DMT. Among 270 individual ASVs included in the analyses, 20 were nominally significant (p<0.05), e.g. the presence of Blautia stercoris was associated with higher relapse risk (hazard ratio [HR]=2.50; 95% confidence interval [CI]=1.43, 4.37). WGCNA identified 6 ASV modules. Higher values of one module’s eigengene was significantly (false discovery rate q<0.2) associated with higher relapse risk (HR=1.23, 95% CI=1.02, 1.50). Four ASVs nominally associated with higher relapse risk were in this module. These included Blautia massiliensis, Dorea longicatena, Coprococcus comes, and an unknown species in genus Subdoligranulum.

Conclusions

We found that a high relative abundance of a gut microbiota species within the Blautia genus, and its interconnected variants, was associated with a higher relapse risk in pedMS cases. While our study represents the largest of its kind in MS, findings need to be replicated. However, Blautia stercoris has been linked to disease activity in other immune-mediated diseases such as systemic lupus erythematosus.

Abstract

Historically, a prodromal period in multiple sclerosis (MS) was not thought to exist. A prodrome can be defined as an early set of signs or symptoms occurring before classical onset of a disease. For a chronic neurological disease such is MS, a prodromal phase could span months or years before ‘MS symptom onset.’ While prodromal phases have been relatively well recognized in other neurological conditions, such as Parkinson disease, the MS prodrome has received little consideration until recently. A better understanding of the MS prodrome could have profound implications for disease prevention and management. Thus, it is important for scientists across all disciplines, from bench researchers to epidemiologists, medical ethicistic, and clinical trialists, as well as clinicians, to be cognizant of this emerging area. However, although the field remains nascent, there is sufficient knowledge of the MS prodrome to affect current practice now, particularly research into risk factors for MS onset. Putative risk factors must be carefully evaluated in light of the MS prodrome. However, much more work is needed before the MS prodrome has direct application to routine clinical practice.

Session Objectives: To summarize and reflect on what is currently known, and not known, about the MS prodrome, and what the implications are for research and future clinical care of person’s with MS.

Background

Metagenomic sequencing reveals the functional potential of the gut microbiome, and may explain how the gut microbiome influences pediatric-onset multiple sclerosis (MS) risk.

Objectives

To examine the gut microbiome functional potential by metagenomic analysis of stool samples from pediatric MS cases and controls using a case-control design.

Methods

Persons ≤21 years old enrolled in the Canadian Pediatric Demyelinating Disease Network who provided a stool sample and were not exposed to antibiotics or corticosteroids 30 days prior were included for study. All MS cases met McDonald criteria, had symptom onset <18 years of age and had either no prior disease-modifying drug (DMD) exposure or were exposed to beta-interferon or glatiramer acetate only. Twenty MS cases were matched to 20 non-affected controls by sex, age (± 3 years), stool consistency (Bristol Stool Scale, BSS) and, when possible, by race. Shotgun metagenomic reads were generated using the Illumina NextSeq platform and assembled using MEGAHIT. Metabolic pathway analysis was used to compare the gut microbiome between cases and controls, as well as cases by DMD status (DMD naïve vs DMD exposed MS cases vs controls). Gene ontology classifications were used to assess α-diversity and differential abundance analyses (based on the negative binomial distribution) reported as age-adjusted log-fold change (LFC) in relative abundance, 95% confidence intervals (CI), and false discovery rate adjusted p-values.

Results

The MS cases were aged 13.6 mean years at symptom onset. On average, MS cases and controls were 16.1 and 15.4 years old at the time of stool collection and 80% of each group were girls. MS cases and controls were similar for body mass index (median: 22.8 and 21.0, respectively), stool consistency (BSS types 1-2: n=4, types 3-5: n=16, for both MS and controls) and race (Caucasian: 11 and 9, respectively). Eight MS cases were DMD naïve. Richness of gene ontology classifications did not differ by disease status or DMD status (all p>0.4). However, differential analysis of metabolic pathways indicated that the relative abundance of tryptophan degradation (via the kynurenine pathway; LFC 13; 95%CI: 8–19; p<0.0005) and cresol degradation (LFC 19; 95%CI: 13–25; p<0.0001) pathways were enriched for MS cases vs controls. Differences by DMD status were also observed, e.g., choline biosynthesis was enriched in DMD exposed vs naïve MS cases (LFC 21; 95%CI: 12–29; p<0.0001).

Conclusions

We observed differences in the functional potential of the gut microbiome of young individuals with MS relative to controls at various metabolic pathways, including enrichment of pathways related to tryptophan and metabolism of industrial chemicals. DMD exposure affected findings, with enrichment of pathways involved in promoting CNS remyelination (e.g., choline).

Abstract

Historically, a prodromal period in multiple sclerosis (MS) was not thought to exist. A prodrome can be defined as an early set of signs or symptoms occurring before classical onset of a disease. For a chronic neurological disease such is MS, a prodromal phase could span months or years before ‘MS symptom onset.’ While prodromal phases have been relatively well recognized in other neurological conditions, such as Parkinson disease, the MS prodrome has received little consideration until recently. A better understanding of the MS prodrome could have profound implications for disease prevention and management. Thus, it is important for scientists across all disciplines, from bench researchers to epidemiologists, medical ethicistic, and clinical trialists, as well as clinicians, to be cognizant of this emerging area. However, although the field remains nascent, there is sufficient knowledge of the MS prodrome to affect current practice now, particularly research into risk factors for MS onset. Putative risk factors must be carefully evaluated in light of the MS prodrome. However, much more work is needed before the MS prodrome has direct application to routine clinical practice.

Session Objectives: To summarize and reflect on what is currently known, and not known, about the MS prodrome, and what the implications are for research and future clinical care of person’s with MS.

Abstract

Historically, a prodromal period in multiple sclerosis (MS) was not thought to exist. A prodrome can be defined as an early set of signs or symptoms occurring before classical onset of a disease. For a chronic neurological disease such is MS, a prodromal phase could span months or years before ‘MS symptom onset.’ While prodromal phases have been relatively well recognized in other neurological conditions, such as Parkinson disease, the MS prodrome has received little consideration until recently. A better understanding of the MS prodrome could have profound implications for disease prevention and management. Thus, it is important for scientists across all disciplines, from bench researchers to epidemiologists, medical ethicistic, and clinical trialists, as well as clinicians, to be cognizant of this emerging area. However, although the field remains nascent, there is sufficient knowledge of the MS prodrome to affect current practice now, particularly research into risk factors for MS onset. Putative risk factors must be carefully evaluated in light of the MS prodrome. However, much more work is needed before the MS prodrome has direct application to routine clinical practice.

Session Objectives: To summarize and reflect on what is currently known, and not known, about the MS prodrome, and what the implications are for research and future clinical care of person’s with MS.