MiR-9394b from Lactobacillus paracasei extracellular vesicles targets iNOS to reprogram host NO-ornithine metabolism and ameliorate ulcerative colitis

ABSTRACT:

Background Probiotics have attracted considerable interest for ulcerative colitis (UC); however, their efficacy is highly strain-specific and the underlying molecular mechanisms remain incompletely understood.

Results Accumulating evidence indicates that bacterial extracellular vesicles (BEVs) function as important effector carriers by delivering regulatory cargos to host cells. In this study, we investigated lactobacilli isolated from infant intestinal contents and screened four strains in a DSS-induced murine colitis model. Oral administration of Lactobacillus paracasei (LPC) or its extracellular vesicles (LPC-EVs) markedly alleviated colitis severity, as evidenced by reduced histopathological damage, restoration of intestinal epithelial barrier integrity, and suppression of TLR4/NF-κB–associated inflammatory responses. Untargeted metabolomics further demonstrated that LPC-EVs reshaped host arginine metabolism, characterized by increased ornithine levels. In vitro assays showed efficient uptake of LPC-EVs by intestinal epithelial cells; their bioactivity was markedly diminished or abolished after RNase treatment, supporting an RNA cargo–dependent mechanism. miRNA sequencing identified miR-9394b as a highly enriched candidate key cargo in LPC-EVs. Mechanistic analyses suggested that miR-9394b can target inducible nitric oxide synthase (iNOS), thereby suppressing excessive nitric oxide (NO) production, enhancing ornithine availability, and promoting epithelial repair.

Conclusion In this study, we report for the first time that the Lactobacillus paracasei–EV–miR-9394b–iNOS/NO–ornithine metabolic regulatory axis contributes to UC amelioration, providing mechanistic and theoretical support for EV cargos targeting host metabolism and promoting mucosal repair.

INSTRUMENT(S): Liquid Chromatography MS - negative - reverse-phase, Liquid Chromatography MS - positive - reverse-phase

PROVIDER: MTBLS13753 | MetaboLights | 2026-01-23

REPOSITORIES: MetaboLights