infection disrupts the gut-lung axis via microbiota dysbiosis and metabolic reprogramming leading to intestinal barrier impairment in piglets.

Abstract

BACKGROUND: (), is a key respiratory pathogen responsible for Glässer's disease in pigs, characterized by polyserositis, arthritis, and pulmonary lesions. While it disrupts the respiratory microbiota, its impact on the gut-lung axis, a critical pathway for systemic immune and metabolic crosstalk, remains unexplored. METHODS: We established a piglet infection model using the highly virulent G. parasuis strain XX0306 (serotype 5). Systemic effects were investigated through integrated 16S rDNA sequencing of the lung and gut microbiota, complemented by untargeted metabolomics of intestinal contents. We performed histopathological examination and measured serum biomarkers (diamine oxidase and D-lactate) to assess intestinal barrier integrity. Correlation analysis linked microbial shifts to host metabolic alterations. RESULTS: Infection induced profound dysbiosis in both the lung and gut microbiota. Pulmonary microbial diversity and functional potential declined. Gut dysbiosis featured a loss of beneficial bacteria and enrichment of potential pathogens (e.g.,,,). Functional prediction indicated significant alterations in 12 gut microbial metabolic pathways, with downregulated amino acid metabolism and upregulated carbohydrate/lipid metabolism and xenobiotic degradation. Metabolomics identified 30 differentially abundant metabolites (e.g., argininosuccinate, liquiritigenin, citrulline), primarily enriched in cytochrome P450-mediated xenobiotic metabolism and arginine biosynthesis. Argininosuccinate levels correlated with pathogenic genera (,,). Infected piglets exhibited significant intestinal barrier damage, evidenced by elevated serum diamine oxidase (DAO) and D-lactate (D-LA). CONCLUSION: This study demonstrates thatinfection extensively remodels the gut-lung axis microbiota and host metabolome, leading to intestinal barrier impairment. The perturbation of arginine biosynthesis may compromise host immunity. These results provide novel mechanistic insights into the pathogenesis of Glässer's disease.