Gut microbiome diversity now linked to muscle growth, study suggests

The University of Kentucky team found gut microbiome dysbiosis was linked to blunted muscle development in response to exercise designed to induce robust skeletal muscle adaptation and growth.

“Gut microbiome dysbiosis was associated with blunted fibre-type specific hypertrophy in the soleus and plantaris muscles in response to progressive weighted wheel running (PoWeR),”​ the team writes, led by the study’s senior author, John McCarthy.

“Gut microbiome dysbiosis was associated with impaired PoWeR-induced fibre-type shift and loss of myonuclei accretion in the plantaris muscle.”​

Along with first study author, Taylor Valentino, the team began randomly assigning 42 mice to either untreated (U) or antibiotic-treated (T),  non-running controls (CU or CT, respectively) or progressive weighted wheel running (PoWeR, P) untreated (PU) or antibiotic-treated (PT) groups.

Initial findings revealed a drop in gut microbiome bacterial species in both the CT and PT groups, suggesting antibiotic treatment had a hand in upsetting gut microbiome diversity.

In response to the PoWeR exercise, PT showed less hypertrophy of soleus Type 1 and 2a muscle fibres and plantaris Type 2b/x muscle fibre types compared to PU.

The higher satellite cell and myonuclei abundance of PU plantaris muscle after PoWeR was not observed in PT.

Plantaris muscle​

The team also found the fibre-type shift of PU plantaris muscle to a more oxidative Type 2a fibre composition following PoWeR was blunted in PT.

Additional findings revealed no difference in serum cytokine levels among all groups suggesting gut microbiome disruption did not induce systemic inflammation.

“Antibiotic dysbiosis of the gut microbiome did not impair the exercise-induced fibre type shifts in the soleus muscle but did in the plantaris muscle,”​ the team comments.

“In the soleus, the loss of Type 2a fibres was similar between the PoWeR-trained groups whereas in the plantaris, the higher abundance of Type 2a fibres was significantly less in mice with a suppressed microbiome. ​

“This finding suggests there is some microbial-derived factor(s) that may be necessary to promote the transition to a more oxidative phenotype.”​

The study refers to previous trials in which the microbiome from obese and lean pigs could be transferred to germ free (GF) mice resulting in the development of each pigs’ distinct muscle fibre-type composition.

Further proof came in the form of a study that found GF mice, which had lost the oxidative capacity across different hind limb muscles, had the function partially restored following microbial transfer.

According to the team, these findings along with the results from the current study support the idea that the gut microbiome aids in the transition to a more oxidative phenotype in skeletal muscle.

Muscle mass and function​

Much evidence has been put forward to suggest the gut microbiome’s role in regulating skeletal muscle mass and function, with one study demonstrating the skeletal muscle of GF mice is atrophic compared to specific pathogen free (SPF) mice. Inoculating GF mice with microbiota was able to restore muscle mass.

Exercise has been shown to control microbiome composition with specific microbes linked to an enhanced exercise capacity as well as protection against a range of different pathologies.

These findings have opened up new research areas that now look to utilise the microbiome to address diseases such as cancer, depression, obesity, Parkinson’s and autism.

A better understanding of the gut microbiome’s role in skeletal muscle plasticity could provide new interventions to tackle age-related loss in skeletal muscle mass and function.

Source: The Journal of Physiology​

Published online: https://doi.org/10.1113/JP281788​​

“Dysbiosis of the Gut Microbiome Impairs Mouse Skeletal Muscle Adaptation to Exercise.”​

Authors: Taylor Valentino et al.