Abstract
Oxidative stress compromises intestinal barrier function and antioxidant defense in weaned piglets, causing substantial economic losses in the pig industry. Probiotic interventions to improve gut health are considered a highly promising solution; research indicates that certain Lactobacillus species can promote the proliferation of Lgr5+ stem cells and activate the AhR/STAT3 pathway by modulating microbiota metabolism, thereby enhancing intestinal barrier and antioxidant function. Although Limosilactobacillus mucosae (L. mucosae) has demonstrated antioxidant properties in rodent models, its involvement in modulating intestinal stem cell (ISC) fate in piglets, as well as the associated mechanisms, remains unclear. We hypothesized that L. mucosae could alleviate oxidative stress in weaned piglets by modulating intestinal microbiota and activating the aryl hydrocarbon receptor/signal transducer and activator of transcription 3 (AhR/STAT3) signaling-mediated intestinal epithelial renewal. We compared the gut microbiota composition between Hezuo pigs (a subgroup of the plateau-type Tibetan breed) and Landrace × Yorkshire (LY) pigs, and isolated L. mucosae LM410 from Hezuo pigs. The strain was evaluated for acid and bile tolerance, antioxidant activity, and inhibitory properties. Subsequently, a 14-day animal trial was conducted using Duroc × Landrace × Yorkshire (DLY) weaned piglets orally administered with 1 × 109 CFU/mL L. mucosae LM410. Intestinal morphology, barrier integrity, immune responses, antioxidant capacity and cecal microbiota composition and metabolic pathways were assessed. We found that Hezuo pigs harbored a higher abundance of L. mucosae in the gut compared with LY pigs. The isolate L. mucosae LM410 from Hezuo pigs, demonstrated strong acid and bile salt tolerance, as well as antioxidant and antimicrobial activities, and effectively improved intestinal morphology, barrier integrity, immune responses, and antioxidant capacity in DLY weaned piglets. Mechanistically, L. mucosae LM410 reshaped the cecal microbiota by enriching short-chain fatty acid (SCFA)-producing bacteria and upregulating the tyrosine metabolic pathway. Concomitantly, L. mucosae LM410 activated the AhR/STAT3 signaling axis, which likely promoted ISC proliferation and differentiation into goblet cells. These findings demonstrate for the first time that L. mucosae may enhance piglet antioxidant defense through coordinated cecal microbiome remodeling, upregulation of tyrosine metabolism and AhR/STAT3-driven epithelial renewal, providing a theoretical foundation for developing L. mucosae LM410 as a candidate probiotic to improve piglet health.