Gut microbiota in multiple sclerosis: possible influence of immunomodulators

Abstract

Objectives: Differences in gut bacteria have been described in several autoimmune disorders. In this exploratory pilot study, we compared gut bacteria in patients with multiple sclerosis and healthy controls and evaluated the influence of glatiramer acetate and vitamin D treatment on the microbiota.

Methods: Subjects were otherwise healthy white women with or without relapsing-remitting multiple sclerosis who were vitamin D insufficient. Patients with multiple sclerosis were untreated or were receiving glatiramer acetate. Subjects collected stool at baseline and after 90 days of vitamin D3 (5000 IU/d) supplementation. The abundance of operational taxonomic units was evaluated by hybridization of 16S rRNA to a DNA microarray.

Results: While there was overlap of gut bacterial communities, the abundance of some operational taxonomic units, including Faecalibacterium, was lower in patients with multiple sclerosis. Glatiramer acetate-treated patients with multiple sclerosis showed differences in community composition compared with untreated subjects, including Bacteroidaceae, Faecalibacterium, Ruminococcus, Lactobacillaceae, Clostridium, and other Clostridiales. Compared with the other groups, untreated patients with multiple sclerosis had an increase in the Akkermansia, Faecalibacterium, and Coprococcus genera after vitamin D supplementation.

Conclusions: While overall bacterial communities were similar, specific operational taxonomic units differed between healthy controls and patients with multiple sclerosis. Glatiramer acetate and vitamin D supplementation were associated with differences or changes in the microbiota. This study was exploratory, and larger studies are needed to confirm these preliminary results.

Figure 1

These samples were not available (n=2) or not used (n=1; sample given late) for the pre- vs post-vitamin D supplementation analysis. MS= Multiple sclerosis HC= Healthy control GA= glatiramer acetate *One GA-treated subject (who didn't contribute a pre-vitamin D supplementation sample) took antibiotics for an infection prior to the study (azithromycin for sinus infection), and ** one baseline sample was inadvertently stored at −20° C for several days before being moved to −80° C. There was no apparent impact on results of either affected sample (i.e. they did not appear to be outliers).

Figure 2

PCoA by phenotype and supplementation. Principal component analysis is a transformation of Weighted Unifrac distance, a pair-wise distance between samples based the calculation of the shared branches a the phylogenetic tree of the representative rRNA genes from 19757 operational taxonomic units present in at least one sample, weighted by abundance. HC, healthy control; MS, affected; pre/post, refers to supplementation with Vitamin D. Axis 1: 33% of variation explained. Axis 2: 21% of variation explained. All samples were used to generate the plots; for plot clarity, the excluded sample (late sample from one MS subject) was removed from this figure (see Supplementary Figure 1 for unaltered plot).

Figure 3

Differential clustering based on glatiramer acetate treatment. Principal component analysis is a transformation of Weighted Unifrac distance, a pair-wise distance between samples based the calculation of the shared branches a the phylogenetic tree of the representative rRNA genes from 19757 operational taxonomic units present in at least one sample, weighted by abundance. MS, affected where patients are either on GA or untreated. Axis 1: 33% of variation explained. Axis 2: 21% of variation explained. All samples were used to generate the plots; for plot clarity, the excluded samples (HCs) were removed from this figure (see Supplementary Figure 2 for unaltered plot).

Figure 4

Distribution of change of overall microbial abundance after vitamin D supplementation. Change in relative microbial OTU abundance in fecal samples between pre- and post- vitamin D supplementation samples in each subject group using only OTUs present in both samples. The “*” signifies a significant change in the distribution between HC and untreated.

Figure 5

Distribution of statistically significant changes of OTU abundance in taxa. Change in relative abundance of taxa between the pre- and post- Vitamin D supplement time points where statistically significant changes between (A) untreated MS and healthy control or treated MS and (B) treated MS and untreated MS or healthy control (HC). The “*” signifies a significant change in the distribution between HC and untreated.