Age-Related Changes in the Gut Microbiota Promote Atrial Fibrillation

Abstract Background: Aging is the most significant contributor to the increasing prevalence of atrial fibrillation (AF). The gut microbiota dysbiosis is involved in age-associated diseases. However, whether age-associated gut microbial dysbiosis contributes to AF is still unknown. The aim of this study was to evaluate the effect of gut microbiota on the susceptibility of aging-induced AF and to elucidate the underlying mechanisms. Results: The gut microbiota profiling of fecal samples in aged (22-24 months old) and young (2-3 months old) rats was performed by 16S ribosomal RNA gene analysis. A rat model of fecal microbiota transplantation (FMT) was established for analyzing the possible role of age-associated gut microbial dysbiosis in AF. Here, we found that aging process led to marked shift of the microbiota spectrum. The microbiota in young rats following FMT resembled that of aged microbiota and transmitted the increased AF susceptibility by elevation of circulating lipopolysaccharide (LPS). The mechanism for LPS-driven atrial pro-arrhythmic action was dependent on the activation of atrial nucleotide binding and oligomerization domain-like receptor family pyrin domain-containing (NLRP3)-inflammasome. Inhibition of inflammasome by MCC950 resulted in lower atrial fibrosis and AF susceptibility. In addition, atrial fibrosis, plasma LPS concentration, plasma glucose to oral glucose tolerance test (OGTT), intestinal permeability, and gut pathology were significantly increased in elderly human subjects. Finally, altering the microbiota in aged recipient to resemble that of young restored the intestinal barrier dysfunction and LPS and impaired glucose tolerance, and the worse outcomes of aged dysbiosis on atrial fibrosis and AF susceptibility were abrogated. Conclusions: These data suggest that age-associated microbial dysbiosis induces circulating LPS and impairs glucose tolerance, and thereby promotes AF susceptibility through enhanced activity of atrial NLRP3-inflammasome.