Nobody likes being ill at work. Waking up with a fever, many of us would just take the day off. But what if your work happens to be 220 miles above the earth’s surface, and you live there too? This is the reality for astronauts at the International Space Station. Space flight affects the human body in many different ways, from loss of muscle and bone mass on long journeys to motion sickness, and it looks like it affects the immune system too. The team of astronauts which returned from the International Space Station this week, including British astronaut Tim Peake, brought with them data and samples which could help us understand this effect.
Infections are a risk for space travel, 15 out of 29 Apollo astronauts suffered infections during or directly after their missions. This might be partly due to the slightly stressful experience of being propelled out of the atmosphere at 9 times the speed of a rifle bullet, but that’s not the full story. The white blood cells of the immune system just don’t work as well at in low gravity, and scientists are working hard to try to understand why. Most experiments on the immune system in space have focused on white blood cells called T-cells. In one study scientists led by Dr. Millie Hughes Fulford and Dr. Augusto Cogili took T cells from human blood to the International Space Station. There they gave them treatments to switch them on and looked at the changes in gene expression of the cells. A quick explanation: Cells don’t use all of their genes all of the time. It’s as if they carry around a huge recipe book but only actually cook a selection of the dishes they need at any one time. If the DNA recipe is being read we can find a copy of it (think of it as the scribbled post-it note you take into the kitchen with you) called RNA, which is ‘read’ to make the final protein. Using a technique called a microarray, researchers can identify the different RNAs inside a cell at a certain time, to find out what recipes the cell is cooking. In space it turns out that T cells make less of the proteins needed to fight infections. This could contribute to the lower activity of the immune system in space. Other experiments, either in space or using simulators on earth, have shown that in microgravity (very low gravity) immune cells also communicate differently, change shape and even die more often.
This isn’t just important for astronauts, the immune effects of microgravity are similar to the effect of aging on the immune system. The ongoing NASA project ‘T cell activation in aging’ looks at T cells both in microgravity at the space station and in aging individuals. The goal is to better understand what makes the immune system less effective in both situations. The Immuno-2 project which Tim Peake and the team worked on looks beyond T cells to the immune system as a whole. As well as preventing immune system side effect of long term space flight but there is the hope that knowledge from these studies could enhance our understanding of immunosuppressive diseases like HIV/AIDs. So as well as being incredibly exciting this research could help people both on earth and far beyond. One small step for scientists, one giant leap for science?
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