Alterations of the gut ecological and functional microenvironment in different stages of multiple sclerosis.
Proc Natl Acad Sci U S A 2020;
117:22402-22412. [PMID:
32839304 PMCID:
PMC7486801 DOI:
10.1073/pnas.2011703117]
[Citation(s) in RCA: 98] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
We have compared gut microbiomes in the different stages of multiple sclerosis (MS) based on both microbial and functional analyses using fecal samples. Together with microbial composition data, metagenomic functional and metabolite data revealed a reduced level of microbial butyrate and propionate biosynthesis in the gut of relapsing remitting MS (RRMS). On the other hand, in the gut of secondary progressive MS (SPMS), we revealed an enhancement in microbial DNA mismatch repair, which was consistent with excessive fecal oxidation shown in sulfur metabolomic analysis. As elevated oxidative stress is closely associated with chronic neuroinflammation and neurodegeneration, the present result opens a way to microbiome data-assisted management of MS, useful for prevention of disease progression.
Multiple sclerosis (MS), an autoimmune disease of the central nervous system, generally starts as the relapsing remitting form (RRMS), but often shifts into secondary progressive MS (SPMS). SPMS represents a more advanced stage of MS, characterized by accumulating disabilities and refractoriness to medications. The aim of this study was to clarify the microbial and functional differences in gut microbiomes of the different stages of MS. Here, we compared gut microbiomes of patients with RRMS, SPMS, and two closely related disorders with healthy controls (HCs) by 16S rRNA gene and whole metagenomic sequencing data from fecal samples and by fecal metabolites. Each patient group had a number of species having significant changes in abundance in comparison with HCs, including short-chain fatty acid (SCFA)-producing bacteria reduced in MS. Changes in some species had close association with clinical severity of the patients. A marked reduction in butyrate and propionate biosynthesis and corresponding metabolic changes were confirmed in RRMS compared with HCs. Although bacterial composition analysis showed limited differences between the patient groups, metagenomic functional data disclosed an increase in microbial genes involved in DNA mismatch repair in SPMS as compared to RRMS. Together with an increased ratio of cysteine persulfide to cysteine in SPMS revealed by sulfur metabolomics, we postulate that excessive DNA oxidation could take place in the gut of SPMS. Thus, gut ecological and functional microenvironments were significantly altered in the different stages of MS. In particular, reduced SCFA biosynthesis in RRMS and elevated oxidative level in SPMS were characteristic.
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