Structural resilience of the gut microbiota in adult mice under high-fat dietary perturbations

Abstract

Disruption of the gut microbiota by high-fat diet (HFD) has been implicated in the development of obesity. It remains to be elucidated whether the HFD-induced shifts occur at the phylum level or whether they can be attributed to specific phylotypes; additionally, it is unclear to what extent the changes are reversible under normal chow (NC) feeding. One group (diet-induced obesity, DIO) of adult C57BL/6J mice was fed a HFD for 12 weeks until significant obesity and insulin resistance were observed, and then these mice were switched to NC feeding for 10 weeks. Upon switching to NC feeding, the metabolic deteriorations observed during HFD consumption were significantly alleviated. The second group (control, CHO) remained healthy under continuous NC feeding. UniFrac analysis of bar-coded pyrosequencing data showed continued structural segregation of DIO from CHO on HFD. At 4 weeks after switching back to NC, the gut microbiota in the DIO group had already moved back to the CHO space, and continued to progress along the same age trajectory and completely converged with CHO after 10 weeks. Redundancy analysis identified 77 key phylotypes responding to the dietary perturbations. HFD-induced shifts of these phylotypes all reverted to CHO levels over time. Some of these phylotypes exhibited robust age-related changes despite the dramatic abundance variations in response to dietary alternations. These findings suggest that HFD-induced structural changes of the gut microbiota can be attributed to reversible elevation or diminution of specific phylotypes, indicating the significant structural resilience of the gut microbiota of adult mice to dietary perturbations.

Figure 1

Phenotype changes of mice during dietary alternations. (a) Body weight curve of each group. (b) Glucose tolerance tests (GTTs) were performed for each group. Shown are the calculated areas under the curve (AUC) of blood glucose from the GTT measurements. (a) and (b) for 0–12 weeks, CHO group and DIO group: n=10; for 14–22 weeks, CHO group: n=9, and DIO group: n=8. The data in (a) and (b) are shown as means±s.e.m. *P<0.05, **P<0.01 by one-way ANOVA.

Figure 2

Changes in the richness and diversity of the gut microbiota during dietary alternations. OTU and Shannon diversity index numbers are shown for each group at eight time points (OTU cutoff, 96%). Calculations were performed after rarefying to an equal number of reads (1000) for all samples to control for unequal sampling effort. Data are shown as means±s.e.m., *P<0.05, **P<0.01 by one-way ANOVA.

Figure 3

Trajectory analysis of the gut microbiota during dietary alternations. Weighted UniFrac PCoA of the gut microbiota between different treatment groups at weeks 0, 2, 4, 8, 12, 16, 20 and 22 based on pyrosequencing OTU (96% identity) data. Each point represents the mean principal coordinate (PC) score from all of the mice in a group at one time point, and the error bar represents the s.e.m.

Figure 4

Changes of relative abundance of several important taxa during the trial. (a) Bacteroidetes, (b) Firmicutes, (c) Proteobacteria and (d) Bifidobacterium spp. in the DIO and CHO group at 0, 2, 4, 8, 12, 16, 20 and 22 weeks. DIO group: n=9 at weeks 0, 2, 4, 8 and 12; n=8 at weeks 16 and 22; n=7 at week 20. Control group: n=10 at weeks 0, 2, 4, 8 and 12; n=9 at weeks 16, 20 and 22. Data are shown as means±s.e.m., *P<0.05, **P<0.01 by one-way ANOVA.

Figure 5

Triplot of the RDA of the microbiota composition relative to fat intake, carbohydrate intake and age. Responding OTUs that explained more than 10% of the variability of the samples are indicated by green arrows. First and second ordination axes are plotted, representing 25.7% and 8.3% of the variability in the data set, respectively. Bottom-left, P-value obtained by Monte Carlo Permutation Procedure is reported.

Figure 6

RDA-derived abundance distribution pattern of the 77 key phylotypes responding to fat intake, carbohydrate intake and age. Heat map of the spot corresponds to the bacterial abundance in the sample. Cluster environments from UniFrac were used to group the mice. The OTUs were organized according to their phylogenetic positions. The taxa of the OTUs are shown on the right.