Transplantation of Elderly Human Gut Microbiota Into Pigs Reprograms Intestinal Barrier Function, Plasma Metabolome, and Gut Mucosal Transcriptomic Landscape.

The gut microbiota plays a pivotal role in maintaining intestinal homeostasis and regulating host metabolism, yet its composition and function undergo substantial alterations with aging. However, the relationship between age-associated microbial changes and host intestinal physiology remains not fully elucidated. Here, we employed Bama miniature pigs, a model with close gastrointestinal similarity to humans, to investigate the impact of fecal microbiota transplantation (FMT) from young or elderly human donors on gut structure, barrier integrity, plasma metabolites, and intestinal mucosal transcriptomics. FMT resulted in distinct gut microbial profiles, with elderly-donor FMT reducing ileal villus height and tight junction proteins (ZO-1, claudin-1, and occludin) across multiple intestinal segments. At the species level, Phocea massiliensis predominated in young-donor pigs, while Blautia obeum was enriched in elderly-donor pigs. Plasma metabolomic analysis revealed increased 3-methyloxindole, prostaglandin E3, and 2-hydroxybutanoic acid but reduced Tyr-Phe and 2-hydroxyoctadecanoic acid in the elderly group. Among B. obeum-associated metabolites, Tyr-Phe and 2-hydroxyoctadecanoic acid exhibited a positive correlation with certain intestinal tight junction protein levels, whereas prostaglandin E3 showed an inverse correlation. Further validation performed in IPEC-1 cells demonstrated that Tyr-Phe elevated transepithelial electrical resistance (TEER), while prostaglandin E3 lowered this parameter. Transcriptomic profiling identified seven hub genes (MX2, ISG15, IFI6, IFIT1, OAS1, DHX58, ISG12(A)) that were consistently downregulated in the ileal mucosa of pigs receiving elderly-donor microbiota. These findings link age-associated microbiota alterations to coordinated changes in intestinal architecture, barrier integrity, and host metabolic and transcriptional profiles, providing insights into microbial and metabolic features associated with age-related intestinal decline.