Abstract
INTRODUCTION: Enterotoxigenic Escherichia coli (ETEC) is a globally recognized gastrointestinal pathogen and a major cause of diarrhea in neonatal and post-weaning animals, leading to significant economic losses in pig production. Premature weaning disrupts colonic morphology and barrier integrity, resulting in diarrhea, dehydration, growth retardation, and increased mortality. Linarin, a natural flavonoid derived from wild chrysanthemum, exhibits antioxidant, sedative, and anti-osteoporotic properties, demonstrating potential as a therapeutic agent and functional food ingredient. METHODS: 24 healthy 21-day-old weaned piglets (Duroc × Landrace × Large Yorkshire) were randomly assigned to four groups fed a basal diet (BD) or linarin-supplemented diet (LN) with oral infusion of 10 mL nutrient broth (NB) or 10(⁹) colony-forming units/mL ETEC. Following a 3-day acclimation period, piglets were fed the corresponding diet for 21 days; infusion with ETEC or NB was performed for 3 days on days 8 and 18. Colonic morphology, diarrhea incidence, gene expression, short-chain fatty acids (SCFAs), microbiota composition, and metabolomic profiles were assessed. RESULTS: Linarin supplementation significantly ameliorated colonic crypt hyperplasia, increased goblet cell numbers, and decreased diarrhea incidence following ETEC infusion. It downregulated pro-apoptotic and pro-inflammatory gene expression while upregulating barrier-associated genes. Linarin also significantly increased the concentrations of short-chain fatty acids (acetic, propionic, valeric, and isovaleric acids) in the colon. Integrated analysis of 16S rRNA gene sequencing and non-targeted metabolomics revealed that linarin modulated the intestinal microbiota by altering the relative abundance of key bacterial taxa (Pedosphaera, Fusicatenibacteria, Tyzerella, Sporobacteria, Limosilactobacillus, Senegalimassilia, Catenibacillus, and Bryobacteria), and associated metabolic pathways, including purine and pyrimidine metabolism; steroid, porphyrin, and vitamin biosynthesis; various amino acid and nucleotide metabolic processes; unsaturated fatty acid biosynthesis; and the citric acid cycle. DISCUSSION: These findings indicate that linarin restores colonic barrier function and intestinal microbiota homeostasis, enhancing resistance to ETEC infection along with the development and well-being of piglets after weaning. This study offers a new mechanistic understanding of how linarin confers protection against ETEC, which can promote its widespread application as a natural feed additive to replace antibiotics.