Sheng-Jiang Powder and Akkermansia muciniphila interventions in experimental autoimmune encephalomyelitis: microbiota-linked sphingolipid/S1PR1-associated barrier remodeling

Background Sheng-Jiang Powder (SJP) is a classical traditional Chinese medicine formula with reported anti-inflammatory and gut microbiota-modulating activities. However, whether its protective effects in experimental autoimmune encephalomyelitis (EAE) are associated with gut microbial changes, sphingolipid/S1P metabolism, and S1PR1-related barrier signaling remains unclear. Methods EAE was induced in female C57BL/6 mice, with SJP, Akkermansia muciniphila (AKK intervention group), or their combination administered from day 2 after immunization, before the expected onset of clinical signs. Clinical severity, histopathology, inflammatory cytokines, and barrier-related markers were evaluated. Gut microbiota changes were assessed by fluorescence in situ hybridization and 16S rRNA sequencing. Untargeted serum and fecal metabolomic profiles were analyzed by LC–MS. Serum-detected SJP-related compounds were characterized by UPLC–MS/MS and analyzed using network pharmacology. S1PR1-associated signaling was further examined by Western blotting, immunofluorescence, and S1PR1-overexpression experiments in bEnd.3 cells. Results Pre-onset SJP, AKK, and AKK_SJP interventions reduced EAE severity, inflammatory pathology, and serum inflammatory cytokine levels. These effects were accompanied by improved colonic barrier markers, increased Akkermansia -associated mucosal signals, and altered gut microbial profiles. Serum and fecal metabolomic analyses highlighted lipid-related pathways, particularly sphingolipid metabolism and signaling. Serum-detected SJP-related compounds mapped to a candidate network containing S1PR1. In colon and CNS tissues, treatment altered barrier-related markers and S1PR1 expression. In bEnd.3 cells, S1PR1 overexpression reduced ZO-1 expression, whereas SJP-containing serum partially attenuated this change. Conclusions Pre-onset SJP administration alleviated EAE and was accompanied by changes in gut microbial composition, sphingolipid/S1P-related metabolism, S1PR1 expression, and barrier-related markers. AKK-related intervention showed overlapping effects on several microbial, metabolic, and barrier-associated markers.