Salivary antimicrobial protein and stress biomarkers are elevated during a 6-month mission to the International Space Station.

Author: Nadia H. Agha, et al. (2019) J Appl Physiol.

ABSTRACT: As the international space community plans for manned missions to Mars, spaceflight associated immune dysregulation has been identified as a potential risk to the health and safety of the flight crew. There is a need to determine if salivary antimicrobial proteins – which act as a first line of innate immune defense against multiple pathogens – are altered in response to long duration (>6- months) missions. We collected 7 consecutive days of whole and sublingual saliva samples from 8 international space station (ISS) crewmembers and 7 ground-based controls at 9 separate mission time points; ~180 and ~60 days before launch (L-180/L-60), on orbit at flight day ~10 and ~90 (FD10/FD90) and ~1-day before return (R-1), and at R+0, R+18, R+33 and R+66 days after returning to Earth. We found that salivary sIgA, lysozyme, LL-37, and the cortisol to DHEA ratio were elevated in the ISS crew before (L-180) and during (FD10/FD90) the mission. ‘Rookie’ crewmembers embarking on their first spaceflight mission had lower levels of salivary sIgA, but increased levels of α-amylase, lysozyme and LL-37 during and after the mission compared to the ‘veteran’ crew who had previously flown. Latent herpesvirus reactivation was distinct to the ~6-month mission crewmembers who performed extravehicular activity (‘spacewalks’). Crewmembers who shed at least one latent virus had higher cortisol levels compared to those who did not shed. We conclude that long duration spaceflight alters the concentration and/or secretion of several antimicrobial proteins in saliva, some of which are related to crewmember flight experience, biomarkers of stress and latent viral reactivation. View Abstract Keywords: salivary antimicrobial proteins, immune dysregulation, latent viral reactivation, herpesvirus, astronauts

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