Exercise attenuates PCB-induced changes in the mouse gut microbiome

Abstract

Background: The gut microbiome, a dynamic bacterial community that interacts with the host, is integral to human health because it regulates energy metabolism and immune functions. The gut microbiome may also play a role in risks from environmental toxicants.

Objectives: We investigated the effects of polychlorinated biphenyls (PCBs) and exercise on the composition and structure of the gut microbiome in mice.

Methods: After mice exercised voluntarily for 5 weeks, they were treated by oral gavage with a mixture of environmentally relevant PCB congeners (PCB153, PCB138, and PCB180; total PCB dose, 150 µmol/kg) for 2 days. We then assessed the microbiome by determination of 16S rRNA using microarray analysis.

Results: Oral exposure to PCBs significantly altered the abundance of the gut microbiome in mice primarily by decreasing the levels of Proteobacteria. The activity level of the mice correlated with a substantial shift in abundance, biodiversity, and composition of the microbiome. Importantly, exercise attenuated PCB-induced changes in the gut microbiome.

Conclusions: Our results show that oral exposure to PCBs can induce substantial changes in the gut microbiome, which may then influence their systemic toxicity. These changes can be attenuated by behavioral factors, such as voluntary exercise.

Figure 1

Experimental design indicating treatment and sampling times.

Figure 2

Exercise alters the structure and composition of the gut microbiome. (A) PCoA based on unweighted Unifrac distance between exercised and sedentary mice (PCoA1, 33% of variation; PCoA2, 15% of variation). (B) PCoA and (C) HC‑AN analysis based on weighted Unifrac distance between exercised and sedentary mice of the 2,510 taxa with significant abundance differences across at least one of the categories (PCoA1, 84% of variation; PCoA2, 6% of variation).

Figure 3

Exercise prevents PCB-induced alterations of the gut microbiome. (A) PCoA and (B) HC‑AN analysis based on weighted Unifrac distance of the 1,568 taxa with significant differences in abundance in at least one of the categories (PCoA1, 71% of variation; PCoA2, 11% of variation). (C) Proteobacteria content in vehicle-treated control and PCB-treated sedentary and exercised mice; values are mean ± SE of pooled taxa in phylum Proteobacteria. *p < 0.05 compared with controls.