Page 148 - Helicobacter pylori and Gastric Cancer: From Tumor microenvironment to Immunotherapy

Historical background of the concept that microgravity influences human host defense.
Probably ever since the early days of a space probe, it has been suggested that extra- atmospheric humans suffer from the reduced immune function. Although, as a consequence of the secrecy concerning this topic during the Cold War era actual medical data and scientific reporting on the early space exploration is difficult or even impossible to obtain (especially from the ex-Soviet Union). Some scarce scientific reports and informal communication do suggest, with regard to the Russian experience, immune dysfunction was a concern [11] and in the American experience it certainly was: the Mercury program-flown chimpanzee Enos died in 1962 from Shigella infection, quite soon after his space trip on November 29, 1961 (although now many investigators doubt whether his death was related to his space travel). Likewise, the death of the pig-tailed monkey Bonnie on biosatellite 3 (the first primate satellite) raised, at the time, wide-spread concern concerning the immunological safety of space travel. Although now many feel that the death of Bonnie is to be attributed to “over- instrumentation” of the unfortunate animal[12]. Minor bacterial and viral infections were not uncommon. Among the Apollo astronauts, a range of diseases was reported, mainly of the eyes, skin and respiratory tract (including stomatitis, pharyngitis, recurrent inguinal and axillary infections). The astronaut Fred Haise developed a Pseudomonas aeruginosa urinary tract infection on Apollo, and this case was prominently suggested at that time to be a space-travel specific increased susceptibility towards viral infection via a publication in the authoritative medical journal JAMA[13]. Thus at that time, space-travel was associated with the diminished functioning of the immune system. However, the effect of space travel is probably not blank immunosuppression, and when appropriate measures are taken such as vigilant hygiene (which is relatively easy in the confined and isolated setting of space going vehicle) and a proper pre-flight medical examination of the crew, acute immunosuppression-related medical problems remain quite rare. Nevertheless, overt signs of mild immune suppressions are evident, for example, the re-activation of the varicella-zoster virus[14], herpes virus[15], and Epstein-Barr virus[16], but remain subclinical. It cannot be excluded, however, that during a long-term mission, like the proposed manned flight to Mars, diminished immunity could become a problem. And thus in the context of such long-duration space flight, knowledge on the molecular mechanisms that are responsible for space travel-associated immunosuppression have a practical importance that exceeds the scientifically fundamental question as to the interaction of the gravitational earth field and the human immune system.
Chapter 7
Chapter 7
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