Project Results

Vroom et al., 2022

Expression of apoptosis genes under modeled microgravity conditions occurred earlier and at high levels compared to gravity controls, in particular the expression of genes encoding initiator and executioner caspases. Functional assays of these apoptotic proteases revealed heightened activity under modeled microgravity; however, these increases could be mitigated using caspase inhibitors. The outcomes of this study indicated that modeled microgravity alters the expression of both extrinsic and intrinsic apoptosis gene expression and that this process is mediated in part by caspases. Modeled microgravity-associated increases of caspase activity can be pharmacologically inhibited suggesting that perturbations to the normal apoptosis signaling cascade can be mitigated, which may have broader implications for maintaining animal-microbial homeostasis in spaceflight.

Duscher et al., 2024

Results revealed that although the onset of the symbiosis was the major driver in the differential expression of NFκB signaling, the stress of simulated low-shear microgravity also caused a dysregulation of expression. Several genes were expressed at earlier time points suggesting that elements of the E. scolopes NFκB pathway are stress-inducible, whereas expression of other pathway components was delayed. The results provide new insights into the role of NFκB signaling in the squid-vibrio symbiosis, and how the stress of microgravity negatively impacts the host immune response. Together, these results provide a foundation to develop mitigation strategies to maintain host-microbe homeostasis during spaceflight.

About This Project

Astronauts experience dysregulated immune function in space that may be related to their microbial communities, but there is a gap in knowledge on how space impacts microbiomes. Our lab investigates the impact of space-related microgravity, or near weightlessness, on the immune response of a simplified model system: a squid and its beneficial bacteria. In this study, we will analyze the gene expression of two innate immune pathways in the squid in relation to their bacteria in microgravity.

Ask the Scientists

What is the context of this research?

Space flight imposes numerous physical challenges to the human body including dysregulation of the immune system. One area of research that has received little attention is the impact that space flight has on beneficial non-pathogenic microbes that associate with human tissues and regulate various immune responses. In our lab, we use a simplified model system between the Hawaiian bobtail squid, Euprymna scolopes, and its bioluminescent bacterium, Vibrio fischeri, to investigate how beneficial microbes impact innate immune function of their animal host in a space-like environment. This model system has been successfully used in our lab for microgravity experiments and has already been flown into space on the Endeavour STS- 134 and the Atlantis STS-135 space shuttle missions!

What is the significance of this project?

While many studies have investigated the impact of space flight on human physiology & microbial pathogenicity, the effect on beneficial host-microbe interactions and relative immune function has received little attention. The innate immune system is found in all animals, thus the results of this work may be applied to better understand how the immune system of astronauts is affected in space flight, and what role the body's microbial consortium may play in these changes. In addition, by removing gravity as a constant we can address the question of whether gravity obscures aspects or cues of bacteria-induced animal development and innate immune response that may otherwise go undetected under Earth-based conditions.

What are the goals of the project?

We will use the monospecific model between the Hawaiian bobtail squid Euprymna scolopes and its beneficial bacterium Vibrio fischeri to study how mutualistic symbioses are impacted by microgravity. Specifically, we will examine how microgravity alters the expression of squid innate immune system genes in the presence and absence of V. fischeri. All of the experiments with the squid & bacteria in gravity vs. microgravity have been completed and now these experiments are ready to be sequenced. We will extract active transcript RNA (specifically messenger RNA) from the squid in preparation for gene sequencing. The funds raised here will be used for state of the art sequencing technology, NanoString, to achieve high quality and unbiased gene expression data.