title: Effect of solar particle event radiation on gastrointestinal tract bacterial translocation and immune activation.
abstract: Space flight conditions within the protection of Earth's gravitational field have been shown to alter immune responses, which could lead to potentially detrimental pathology. An additional risk of extended space travel outside the Earth's gravitational field is the effect of solar particle event (SPE) radiation exposure on the immune system. Organisms that could lead to infection include endogenous, latent viruses, colonizing pathogenics, and commensals, as well as exogenous microbes present in the spacecraft or other astronauts. In this report, the effect of SPE-like radiation on containment of commensal bacteria and the innate immune response induced by its breakdown was investigated at the radiation energies, doses and dose rates expected during an extravehicular excursion outside the Earth's gravitational field. A transient increase in serum lipopolysaccharide was observed 1 day after irradiation and was accompanied by an increase in acute-phase reactants and circulating proinflammatory cytokines, indicating immune activation. Baseline levels were reestablished by 5 days postirradiation. These findings suggest that astronauts exposed to SPE radiation could have impaired containment of colonizing bacteria and associated immune activation.
authors.affiliation: Division of Infectious Diseases, Department of Medicine, University of Pennsylvania, 3610 Hamilton Walk, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Houping
authors.initials: H
authors.lastname: Ni
authors.forename: Klara
authors.initials: K
authors.lastname: Balint
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhou
authors.forename: Daila S
authors.initials: DS
authors.lastname: Gridley
authors.forename: Casey
authors.initials: C
authors.lastname: Maks
authors.forename: Ann R
authors.initials: AR
authors.lastname: Kennedy
authors.forename: Drew
authors.initials: D
authors.lastname: Weissman
mesh_terms: D000818:Animals; D058491:Bacterial Load / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D005260:Female; D041981:Gastrointestinal Tract / Q000382:microbiology* / Q000528:radiation effects*; D007113:Immunity, Innate / Q000528:radiation effects*; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D011829:Radiation Dosage