Page 151 - Helicobacter pylori and Gastric Cancer: From Tumor microenvironment to Immunotherapy

presence of a healthy gut microbiome is necessary to maintain immune homeostasis. As such the dysbiosis that results from prolonged stay in space may affect the health of astronauts causing higher susceptibility to opportunistic infections, reactivation of latent infections, induction of IBS and increased potential to develop diabetes or even cancer.
A possible explanation as to why this dysbiosis occurs in space is the lack of microbial challenge while staying on board a space craft. Due to the confinement of the living space, a strict hygiene regime is maintained. This does not only concern the living quarters but also the food astronauts eat and the air they breathe. Not risking the chance to get sick by microbial infection, limits the natural competition commensal microbes would normally experience by intake of pathogenic microbes. Consequential some may experience a potential growth advantage altering the balance of the gut flora.
The deleterious effect of prolonged stay in space on the microbiome may be countered by measures such as diet based therapies. These diets include vegetables, fresh fruits and fiber rich diets which enhanced the growth of butyrate-producing bacteria potentially reversing the profile of metabolites associated with human disease. This hypothesis is currently being tested by NASA using a combination of metabolomics, metatranscriptomics, 16s taxonomic profiling and immunological approaches. Alternatively the gut flora may be supplemented by probiotics or possibly fecal transplant pills. However, effects of such strategies still require investigation. Spaceflight long journey to the Mars by astronauts present a lot of challenges of which one among them is their inability to maintain a healthy microbiome population. This microbiome that forms the normal biota of the human intestine helps in protecting the host from infectious diseases, enhance immunity and breakdown of food; A wide range of condition may arise due to imbalance in microbiome compositions these include syndrome of irritable bowel[46, 47], different cancer type[47] and depression[48]. During spaceflight travel, there is a paradigm shift from healthy to disease state which translates to decrease in microbiome diversity and enhance inflammation. cosmic radiation and Stress are among typical conditions experience during space flight travels[49, 50]. Changed in physiology of bacteria and promotion of dysbiosis of microbiome status[49].
A successful return mission to the planet Mars takes more than a thousand days considering the most optimal conditions, a duration for which a healthy microbiome is imperative. It is therefore that space agencies have prioritized investigations on maintaining a healthy and balanced microbiome. Questions that need answering are:
Health from above?
Health from above?
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