Fecal Microbiota Transfer from Young Mice Reverts Vascular Aging Hallmarks and Metabolic Impairments in Aged Mice

As a major risk factor for cardiometabolic diseases, aging refers to a gradual decline in physiological function, characterized with 12 conspicuous hallmarks, like telomere attrition, chronic inflammation, and dysbiosis. Common vascular aging hallmarks include endothelial dysfunction, telomere dysfunction, and vascular inflammation. In this study, we sought to test the hypothesis that young-derived gut microbiota retards vascular aging hallmarks and metabolic impairments in aged hosts. We also aimed to study the therapeutic efficacy of young microbiota in hosts of different ages. Fecal microbiota transplantation (FMT) from young to aged or middle-aged C57BL/6 mice was conducted for 6 consecutive weeks after antibiotic pretreatment. Endothelium-dependent relaxations (EDRs) in mouse arteries were determined by wire myography. Inflammation and AMPK/SIRT1 signaling in mouse aortas and intestines were studied by biochemical assays. The telomere function of aortas and intestines, in terms of telomerase reverse transcriptase expression, telomerase activity, and relative telomere length, were also studied. FMT significantly reverted vascular dysfunction and metabolic impairments in middle-aged mice than in aged mice. Besides, FMT significantly reverted inflammation and telomere dysfunction in aortas and intestines of middle-aged mice. Improved intestinal barrier function and activated AMPK/SIRT1 signaling potentially underlie benefits of FMT. The findings imply gut-vascular connection as potential target against age-associated cardiometabolic disorders, highlight crosstalk among aging hallmarks, and suggest a critical timepoint for efficacy of anti-aging interventions.