Sung M.
Sookmyung Women s University, South Korea

Gut microbiota has emerged as one of the key environmental factors closely related with obesity. Recent studies have showed that diet-induced alterations of gut microbiota composition play a pivotal role in the development of metabolic diseases. However, studies also suggest that the relationship between the microbiota and obesity is complex with contradictory findings relating to the nature of shift in the relative contribution of phyla to the microbiota composition in obesity. Also, it is not still clear whether changes in gut microbiota are induced by dietary perturbations. In this study, we investigated whether dietary fat intake and age would affect gut microbiota, permeability, and inflammation.

C57BL/6J mice were randomly assigned to either normal fat diet or high-fat diet group. After 10 weeks, a half of mice in each group were switched to either high-fat diet or normal fat diet feeding for additional 10 weeks. Microbiome composition and diversity were analyzed by 16S rRNA-based pyrosequencing. Colonic mRNA expressions of tight junction proteins and inflammatory cytokines were measured by real-time quantitative polymerase chain reaction. We determined the association between the alterations of gut microbiota composition and colonic inflammatory cytokines.

The main bacterial phyla of mice were Frimicutes, Bacteroidetes, and Actinobacteria. Diversity of gut microbiota was reduced in mice fed high-fat diet compared to those of mice fed normal fat diet. In mice fed high-fat diet for 20 weeks, the proportions of Actinobacteria and Firmicutes increased while the proportion of Bacteroidetes decreased compared to mice fed normal fat diet for 20 weeks. The proportions of Firmicutes and Bacteroidetes were significantly associated with age whereas the proportion of Actinobacteria was significantly associated with dietary fat content and age. The correlation data indicated that the relative abundance of Actinobacteria and Firmicutes was positively associated with body weight. Actinobacteria was positively associated with colonic inflammatory cytokines. In addition, we found that high-fat diet was negatively associated with the expressions of tight junction proteins while it was positively associated with the expression of inflammatory cytokines. These results indicate that changes in the expression of tight junction 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. Future studies are needed to investigate whether gut microbiota associated with dietary fat intake would have a modulatory effect on obesity-induced diseases [This study was supported by the Mid-Career Research Program 2012R1A2A2A01046228 NRF].

Keywords: Gut microbiota, Probiotics, High-fat diet, Age, Gut permeability, Colonic inflammation

Sung M. (2016). Effects of dietary fat intake and age on gut microbiota and colonic inflammation in C57BL/6J mice. Conference Proceedings of IPC2016. Paper presented at the International Scientific Conference on Probiotics and Prebiotics, Budapest (p. 118.). IPC2016

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