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Eleven Million Miles for Science: Mice and their Microbiomes May Hold the Key to Protecting Astronauts from the Effects of Microgravity

The gut microbiome may play a compensatory function for host bone loss, suggesting a direction for future therapeutics.  

Cambridge, Mass. – Astronauts pay a significant physical price to work at the International Space Station, experiencing health problems like sleep deprivation, muscle weakness, vision problems, and bone tissue loss. Many of these problems are caused by microgravity, popularly known as weightlessness. A new study from the Forsyth Institute suggests a novel direction for potentially preventing one effect of microgravity: bone loss. 

The study, “Specific host metabolite and gut microbiome alterations are associated with bone loss during spaceflights,” published in Cell Reports, describes significant changes in the gut microbiome of mice participating in NASA Rodent Research-5, a mission dedicated to examining bone tissue loss in space. The scientists found a significant increase in the diversity of bacteria in space. 

“What is so interesting about this finding,” said Dr. Xuesong He, Senior Science Faculty at the Forsyth Institute, “is that the types of bacteria that increased are known to produce a metabolite that promotes bone growth.” The elevated levels of these bacteria occurred at the same time as bone tissue loss in the mice. 

The gut microbiome plays a significant role in human health and disease, but very little is known of how it will behave in space. “It is very exciting to see such a strong association between the microbial diversity and host bone loss.” said Dr. Wenyuan Shi, Chief Executive Officer of the Forsyth Institute and a collaborator on the study. “It shows the gut microbiome may adapt to compensate for a health problem in the host.”  

University of Washington researchers Dr. Kristopher Kerns and Dr. Jeffrey McLean assisted the team in the analysis of the sequence data that provided insight into the specific bacteria enriched in space and the genes they carry. The capacity for these bacteria to produce secondary metabolites demonstrates that complex interactions between the host and microbiome may include protective mechanisms. “There is strong scientific evidence that adaptive changes in gut microbiome can improve many physiological functions from digestion, immune system, mental health, and weight loss,” said Dr. Benjamin Wu, Chief Scientific Officer at Forsyth. “This exciting paper adds bone metabolism to that list.”  

Whether the increase of this bacterial diversity is caused by decreased bone density or space travel must still be tested. However, this study suggests a promising direction for future therapeutics using these bacteria to lessen or prevent bone loss in astronauts and those with osteoporosis. 

“This work started as a serendipitous side project of my PhD thesis,” said microbiologist Dr. Joseph K. Bedree, the study’s first author. “It sought to ask a simple and open-ended question: ‘how does the microbiome behave in microgravity?’ Often in science, we don’t know where the data will lead us, and we didn’t expect to see the changes in the microbiome and bone homeostasis in this way. This study serves as a reminder that microbiota and their interaction in the mammalian host is quite dynamic and continually offers the unexpected, especially as we continue to learn more about the effects of deep-space travel.”

Other study collaborators include Chia Soo MD, Professor at UCLA Departments of Surgery and Orthopedic Surgery; and Eric Kang Ting, DMD, DMSC, Executive Director of International Orthodontic Foundation and Adjunct Faculty at Forsyth Institute. 

The team used a combination of metabolomics and 16S rRNA gene sequencing to analyze the gut microbiome. 

The work was supported by the Forsyth Pilot grant FPILOT59. 

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