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Abstract <p>This study explores the mechanisms of the modulating effectsof the probiotic strain <i>Enterococcus faecium</i> L-3on the course of experimental allergic/autoimmune encephalomyelitis(EAE) in rats, a widely used model of multiple sclerosis. EAE wasinduced in female Wistar rats by a single subcutaneous injectionof spinal cord homogenate in complete Freund’s adjuvant. After EAEinduction, the rats were divided into two groups, one of which received <i>E. faecium</i> L-3 at a dose of 5 × 10<sup>8</sup> lgCFU/mL from day 2 to day 16 post induction. The effects of <i>E. faecium</i> L-3 were assessed by theseverity of EAE, population composition of immune cells (flow cytometry),cytokine levels (ELISA and RT-PCR), taxonomic composition of thegut microbiome (16S rRNA gene sequencing), and ultrastructural alterationsin the small intestinal epithelium (electron microscopy). Rats treatedwith <i>E. faecium</i> L-3 exhibiteda delay in the onset of neurological symptoms and a reduction intheir severity compared to the untreated group. <i>E. faecium</i> L-3 administration ledto significant changes in the composition of the gut microbiomeduring EAE. At the peak of the disease, probiotic-treated rats showeda higher content of <i>Bacteroidota</i> anda lower content of <i>Bacillota</i> (<i>Firmicutes</i>) compared to the controlgroup. Shifts in the gut microbiome also persisted throughout therecovery phase and were associated with a more complete recovery.Probiotic administration reduced the blood level of the circulatingpro-inflammatory cytokine MCP-1, while simultaneously increasingthe level of the regulatory cytokine TGF-β. Ultrastructural analysisof the intestinal epithelium showed that a course of <i>E. faecium</i> L-3 administration reduced enterocytedamage at the peak of the disease and promoted intestinal mucosarestoration in the recovery phase. The obtained results suggestthat the protective effect of <i>E. faecium</i> L-3in EAE is implemented locally through modulation of the gut microbiomecomposition, stimulation of IL-10 expression in mesenteric lymphnodes, maintenance and restoration of enterocyte integrity in thesmall intestine, and systemically through immunoregulatory mechanismsmediated by TGF-β-producing T cells. Overall, the results indicatethat <i>E. faecium</i> L-3 could bea useful supplement to existing multiple sclerosis treatments afterconfirmation of its protective effect in randomized clinical trials.</p>

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Enterococcus faecium L-3 Ameliorates the Severity of Experimental Allergic Encephalomyelitis in Rats by Influencing Gut Microbiota, Enterocytes, and Immune Functions

  • 期刊论文

  • 发表日期：

    2025年10月1日

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  • I. N. Abdurasulova,
  • A. V. Matsulevich,
  • N. M. Grefner,
  • A. N. Trofimov,
  • I. V. Kudryavtsev,
  • E. I. Ermolenko

摘要

Abstract

This study explores the mechanisms of the modulating effectsof the probiotic strain Enterococcus faecium L-3on the course of experimental allergic/autoimmune encephalomyelitis(EAE) in rats, a widely used model of multiple sclerosis. EAE wasinduced in female Wistar rats by a single subcutaneous injectionof spinal cord homogenate in complete Freund’s adjuvant. After EAEinduction, the rats were divided into two groups, one of which received E. faecium L-3 at a dose of 5 × 108 lgCFU/mL from day 2 to day 16 post induction. The effects of E. faecium L-3 were assessed by theseverity of EAE, population composition of immune cells (flow cytometry),cytokine levels (ELISA and RT-PCR), taxonomic composition of thegut microbiome (16S rRNA gene sequencing), and ultrastructural alterationsin the small intestinal epithelium (electron microscopy). Rats treatedwith E. faecium L-3 exhibiteda delay in the onset of neurological symptoms and a reduction intheir severity compared to the untreated group. E. faecium L-3 administration ledto significant changes in the composition of the gut microbiomeduring EAE. At the peak of the disease, probiotic-treated rats showeda higher content of Bacteroidota anda lower content of Bacillota (Firmicutes) compared to the controlgroup. Shifts in the gut microbiome also persisted throughout therecovery phase and were associated with a more complete recovery.Probiotic administration reduced the blood level of the circulatingpro-inflammatory cytokine MCP-1, while simultaneously increasingthe level of the regulatory cytokine TGF-β. Ultrastructural analysisof the intestinal epithelium showed that a course of E. faecium L-3 administration reduced enterocytedamage at the peak of the disease and promoted intestinal mucosarestoration in the recovery phase. The obtained results suggestthat the protective effect of E. faecium L-3in EAE is implemented locally through modulation of the gut microbiomecomposition, stimulation of IL-10 expression in mesenteric lymphnodes, maintenance and restoration of enterocyte integrity in thesmall intestine, and systemically through immunoregulatory mechanismsmediated by TGF-β-producing T cells. Overall, the results indicatethat E. faecium L-3 could bea useful supplement to existing multiple sclerosis treatments afterconfirmation of its protective effect in randomized clinical trials.