Lactobacillus rhamnosus ameliorates experimental autoimmune neuritis via modulation of gut microbiota and metabolites.

BACKGROUND: Guillain-Barre syndrome (GBS), an autoimmune disease of the peripheral nervous system, is hallmarked by demyelination and immune cellular infiltration. Experimental autoimmune neuritis (EAN), considered a GBS prototype model, has been studied for its potential therapeutic benefits from lactobacilli. This study evaluated the protective role of Lactobacillus rhamnosus GG (GG) for treatment in EAN. T cell ratio, inflammation factors, sciatic nerve pathology, intestinal permeability, and gut inflammation were assessed on day 19 post-immunization to evaluate GG's effect on EAN. Fecal metabolomics and 16s rRNA microbiome analysis were conducted to elucidate its mechanism. RESULTS: GG dynamically balanced CD4(+)/CD8(+)T cell ratio, reduced serum IL-1β and TNF-α expression, improved sciatic nerve demyelination and inflammation, and enhanced neurological scores during peak disease period. Intestinal mucosal damage was evident in EAN rats, with downregulated Occludin and ZO-1 and upregulated IL-1β, TNF-α, and Reg3γ. GG treatment restored intestinal mucosal integrity, upregulated Occludin and ZO-1, and downregulated IL-1, TNF-α, and Reg3γ. GG partially rectified the gut microbiota and metabolite imbalance in EAN rats. CONCLUSION: GG mitigates EAN through immune response modulation and inflammation reduction via the gut microbiota and metabolites.