Gene Expression Modified: Unveiling Vulnerability to Infections in Space Travel

In the realm beyond Earth, the absence of gravity poses a significant hazard to the well-being of astronauts, particularly during extended missions. Gaining insights into the response of the human body to the space environment is essential for long-term space exploration and the development of countermeasures to safeguard astronaut health.

Previous scientific investigations have provided evidence of the impact of microgravity on various aspects of the human body, including alterations in brain structure and decreased bone density.

A recent study has shed light on how space travel can induce changes in gene expression within white blood cells (WBCs), which are responsible for combating infections. These modifications have the potential to weaken the immune systems of astronauts, thereby making them more susceptible to infections.

Infections in space

The occurrence of infections in space has already been documented through previous studies, highlighting the heightened vulnerability of astronauts to such ailments.

Astronauts residing aboard the International Space Station (ISS) frequently report experiencing skin rashes, respiratory ailments, and other non-respiratory disorders. Furthermore, it has been observed that astronauts shed a higher number of live virus particles, including Epstein-Barr, varicella-zoster, and herpes-simplex-1 viruses, while in a microgravity environment.

These infections suggest a compromised immune system as a result of space travel. However, the specific factors contributing to this immunological deficiency in space are still under investigation. Researchers from the University of Ottawa have highlighted that changes in gene expression may be one of the potential causes for such space-related infections.

According to Odette Laneuville, an associate professor at the University of Ottawa’s Department of Biology and the lead author of the study, they have demonstrated that the expression of numerous genes associated with immune functions rapidly declines when astronauts enter space, while the opposite trend is observed upon their return to Earth following six months aboard the ISS.

Astronaut gene analysis

However, what causes these changes in gene expression? It appears that microgravity is the influencing factor. In the absence of normal gravity, leukocytes experience a shift in fluids, with blood plasma moving from the lower to the upper body. This fluid shift can result in a decrease in plasma volume by around 10 percent to 15 percent within the first few days in space.

However, based on this observation, the research team put forward the hypothesis that this fluid shift might be responsible for the alterations in gene expression. To investigate this, the researchers conducted a study analyzing the gene expression of leukocytes (white blood cells) in 14 astronauts, including three women and eleven men. These astronauts had served on the space station for durations ranging from 4.5 to 6.5 months between 2015 and 2019.

Throughout the study period, the researchers collected four milliliters of blood from each astronaut at ten different time points: before the flight, four times during the flight, and five times after landing. The leukocytes were isolated from each blood sample to examine any changes in gene expression.

In fact the findings revealed that as many as 15,410 genes exhibited distinct expression patterns in leukocytes. Among these genes, two clusters—composed of 247 and 29 genes, respectively—showed significant changes in their expression levels that occurred in a synchronized manner across the study period.

International Space Station

In the 247-gene cluster, expression levels decreased upon the astronaut’s arrival at the International Space Station (ISS) and then increased again upon their return to Earth. Conversely, the 29-gene cluster demonstrated the opposite pattern of expression, with levels increasing in space and decreasing after landing.

The study’s results also bring some positive findings. Analysis of the samples revealed that the majority of genes in both gene clusters returned to their pre-flight levels within a year after the astronauts’ return to Earth. In certain cases, gene expression even normalized within a few weeks.

However, the researchers caution that astronauts may still face an elevated susceptibility to infections for at least a month following their return to Earth.

These findings will serve as valuable insights for developing effective strategies and countermeasures to address this health concern for future astronauts.

The study’s outcomes have been published in the journal Frontiers in Immunology.

Read the original article on Interesting Engineering.

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