Impact of Whole Body Irradiation on the Intestinal Microbiome- Considerations for Space Flight

Paper number

IAC-17,A1,5,11,x38675

Author

Dr. Fathi Karouia, NASA ARC/UCSF, United States

Year

2017

Abstract

Human space travelers experience a unique environment that affects homeostasis and physiologic adaptation. Spaceflight-related changes have been reported in the musculo-skeletal, cardiovascular, neurovestibular, endocrine, and immune systems to just name a few. However, to date, radiation exposure is one of the main limiting factors for long duration space exploration missions and especially a mission to Mars.

Over the past few years through advances in technology, the characterization of the microbiome has revealed a large and complex community of microorganisms living in symbiosis with the human host. However, heterogeneity of the intestinal microbial spectrum in humans has been associated with a variety of diseases and susceptibility to infectious and toxic agents. Limited information is known about the influence of space environment in general and radiation in particular on the immunocompromised microbiome of the astronaut. Furthermore, multiple spaceflight and simulated microgravity experiments have shown changes in phenotypic microbial characteristics such as microbial growth, morphology, metabolism, genetic transfer, antibiotic and stress susceptibility, and an increase in virulence factors.

We now report a study of the bacterial composition of the intestine in C57BL/6TAC mice and the types of microbes entering the body at two time points after the LD 50/30 dose of total body irradiation. Our studies indicate a significant shift in the mouse gut microbial speciation in several bacterial families, with increases in the {\it Turicibacteraceae} and {\it Enterobacteriaceae} and decreases in the {\it Lachnospiraceae} and {\it Ruminococcaceae} families. The findings most relevant to occupational human exposure, would likely relate to the increase in populations of {\it Enterobacteriaceae}, as multiple species within this family are known to produce disease in humans, including abscess formation, bacteremia, sepsis, disseminated toxins and even death. Therefore studies on the impact of the space environment and space radiation in particular on the astronaut’s microbiome composition and pathogeneicity in addition to the development of countermeasures are important steps in order to decrease risks associated with astronaut’s health and mission integrity.

Abstract document

IAC-17,A1,5,11,x38675.brief.pdf

Manuscript document

IAC-17,A1,5,11,x38675.pdf (🔒 authorized access only).

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