Hindlimb Suspension and SPE-Like Radiation Impairs Clearance of Bacterial Infections

Minghong Li,Jenine K Sanzari,Yu Zhou,Veronica Holmes,Drew Weissman,Ann R Kennedy,Houping Ni,Nandu Goswami

doi:10.1371/journal.pone.0085665

Minghong Li, Jenine K Sanzari + Show 6 more

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https://doi.org/10.1371/journal.pone.0085665

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Journal: PloS one	Publication Date: Jan 15, 2014
Citations: 82	License type: CC BY 4.0

Affiliation: University of Pennsylvania

Abstract

A major risk of extended space travel is the combined effects of weightlessness and radiation exposure on the immune system. In this study, we used the hindlimb suspension model of microgravity that includes the other space stressors, situational and confinement stress and alterations in food intake, and solar particle event (SPE)-like radiation to measure the combined effects on the ability to control bacterial infections. A massive increase in morbidity and decrease in the ability to control bacterial growth was observed using 2 different types of bacteria delivered by systemic and pulmonary routes in 3 different strains of mice. These data suggest that an astronaut exposed to a strong SPE during extended space travel is at increased risk for the development of infections that could potentially be severe and interfere with mission success and astronaut health.

Highlights

A major risk of extended space travel is the combined effects of weightlessness and radiation exposure on the immune system
To accurately measure the effect of the hindlimb suspension model of microgravity and stress and SPElike radiation on the ability of different strains of mice to effectively clear a challenge with bacteria previously demonstrated to cause infections in astronauts, hindlimb suspended and/or irradiated mice were exposed 5 days later to Pseudomonas aeruginosa delivered intraperitoneally (IP) or Klebsiella pneumoniae delivered by inhalation
Mice had blood drawn at various times before and after bacterial challenge and were followed for a total of 5 days after bacterial challenge (Figure 1)

Summary

Introduction

A major risk of extended space travel is the combined effects of weightlessness and radiation exposure on the immune system. Space flight has been shown to alter immune responses, certain of which could lead to potentially detrimental pathology. The consistent effects on the immune system observed during space travel, far, are a reduction in peripheral T-cell counts; a decrease in NK cell number and functionality [12,13]; decreases, sometimes severe, in cell-mediated immunity with altered cytokine production [13,14]; and normal levels of serum immunoglobulins [13]. An increased susceptibility to infection under space flight conditions has been observed [15,16,17,18,19,20,21]. The main concerns of an impaired immune system in the closed environment of a spacecraft is the altered ability to control bacterial, fungal, viral, and parasitic invasions [9,12,13,22] and the loss of immunosurveillance leading to tumor growth [23]

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Conclusion