Effects of simulated Martian environmental stressors on specific human pathogen–immune system interactions

Human missions to Mars can bring health risks for the crew for example by bacterial pathogens which make up the human microbiome. Our research exposed the bacteria Klebsiella pneumoniae and Serratia marcescens to Mars simulated conditions in order to examine their interaction with human immune cells. The bacteria were exposed to several extreme conditions including UV radiation, desiccation and atmospheric conditions. The experimental approach employed analyzed cytokine secretion, reactive oxygen species (ROS) production, phagocytosis in peripheral blood mononuclear cells (PBMCs) as well as flow cytometry measurements on the bacterial cells. Our results showed that cytokine secretion by PBMCs is altered, and that the exposure of the bacteria to desiccation reduces cytokine and ROS release. These results are indicative of an impaired innate immune recognition. When the bacteria were regrown in the growth media, the immune response by PBMCs was partially restored. Furthermore, flow cytometry indicated that both complexity and size of the bacterial cell was altered for K. pneumoniae and S. marcescens. Our research show that the exposure of the bacteria to the Martian conditions alters their morphology and physiology thereby affecting immune recognition and response. The results of our research are summarized in this repository.