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Space Travel Could Affect Our Immune System

Leon County Judge John Cooper on June 30, 2022, in a screen grab from The Florida Channel.
The Florida Channel
Scanning electron micrograph of T lymphocyte (right), a platelet (center) and a red blood cell (left).

As humans spend more time in space there are questions about how their bodies are being affected. 

Dr. Krishna Komanduri, a researcher at the University of Miami, collaborated on a study that found astronauts returning from space are at greater risk for the reoccurrence of viruses like mononucleosis.

For this week's Health News Florida feature Reporter Brendan Byrne sat down with Komanduri, who explains the study.

Brendan Byrne: So let's first start with these T cells. First of all what are they And how does the body make them?

Krishna Komanduri: cells are the primary cells in our bloodstream that protect us from many different types of infections. So when we get influenza or when we get a common cold the immune cells that are most important in clearing those infections are T cells. So T cells are actually produced in organ called the thymus. The thymus is an organ that sits basically above the heart in the chest.

BB: You looked at a very interesting set of subjects. Go ahead tell me a little bit about that.

KK: We had been interested in studying again the role of the T-cells in typically in patients with diseases like HIV disease or patients with cancer. And we wanted to know how the function of the thymus might actually be important and rebuilding the immune system or helping to preserve the function of the immune system. And we actually had a collaborator who at that time approached our laboratory and approached me because he actually told me that he had some interesting data that individuals who had flown on the shuttle or individuals who had flown on the International Space Station appeared to have evidence of reactivation of viral infections that we typically didn't see in healthy individuals.

BB: What were some of those viruses that were coming back?

KK: Two viruses that are of a class of viruses called herpes viruses and these are viruses that individuals may be familiar with. The first one is Epstein-Barr virus, the virus that causes infectious mononucleosis. The second virus is a virus called cytomegalovirus or CMV and CMV is typically acquired very early in in youth. In the world about 70 to 80 percent of people acquire see any infection at some point. And the interesting thing about both of these viruses is that typically when we get in fact that we don't clear those viruses. Those viruses stay persistent in our bodies for the rest of our lives. And indeed, what keeps the viruses from actually causing serious infection are our T cell.  But what our colleague showed previously was that healthy astronauts had a high degree of very short term reactivation of Epstein-Barr virus and that's adjusted to him that in some way during short term spaceflight that the immune system wasn't doing what it should do and that either the cells that control CMV and EBV the T-cells were either decreased in number transiently which you actually found not to be true or that they effectively became non-functional which he showed was the case that that these cells weren't functioning.

BB: Do You have a hypothesis is too as to what is causing this drop in T cells after being exposed to space travel?

KK: What we think was responsible for this is actually the production of what we call stress steroids. And it turns out that when we measured both urine and blood steroid amounts that the amount of steroid and 15 of the 16 astronauts basically doubled at the time that they returned from spaceflight.

BB: When organizations look towards long term spaceflight is there a desire to get to the bottom of this and make sure that they're staying healthy, specifically with this T cell drop?

KK: It's possible that in long term spaceflight again if you travel to Mars and back that immune function could actually decline if these were persistent and progressive effects that actually lead then to significant changes in immune function in which case then we would need to really find ways to counteract that. We don't know the answer to that. And I think one of the things that this suggests is that further studies are really needed.

Listen to the full interview on Byrne’s “Are We There Yet” podcast.