Dietary fat intake and age influence gut microbiota and colonic inflammation in C57BL/6J mice

Abstract

Recent studies have showed that diet-induced alterations of gut microbiota composition play a pivotal role in the development of metabolic diseases. We investigated whether dietary fat and age would affect gut microbiota, permeability and inflammation. C57BL/6J mice were randomly assigned to either normal fat diet (ND) or high-fat diet (HD) group. After 10 wks, a half of mice in each group were switched to either HD or ND feeding for additional 10 wks. Microbiome composition and diversity were analyzed by 16S rRNA-based pyrosequencing. Colonic mRNA expressions of tight junction (TJ) proteins and inflammatory cytokines were measured by qPCR. DNA strand break was determined using comet assay. The main bacterial phyla of mice were Frimicutes, Bacteroidetes, and Actinobacteria. Diversity of gut microbiota was reduced in mice fed HD compared to those of mice fed ND. In mice fed HD for 20 wks, the proportions of Actinobacteria and Firmicutes increased while the proportion of Bacteroidetes decreased compared to mice fed ND for 20wks. The proportions of Firmicutes and Bacteroidetes were related with age while the proportion of Actinobacteria was related with dietary fat content. High-fat diet was negatively associated with the expressions of TJ proteins while it was positively associated with the expression of inflammatory cytokines. Changes in the expression of TJ protein and inflammatory cytokines followed changes in fat content of the diet. Our data showed that both dietary fat intake and age affect gut microbiota composition as well as colonic membrane integrity and inflammation.