Use of Bed Rest and Head-Down Tilt to Simulate Spaceflight-Induced Immune System Changes

Schmitt, Didier; Schaffar, Laurence; Taylor, Gerald R.; Loftin, Karin C.; Schneider, Victor; Koebel, Anne; Abbal, M.; Sonnenfeld, Gerald; Lewis, Dorothy E.; Reuben, James; Ferebee, Robert N.

doi:10.1089/jir.1996.16.151

Cited by 26 publications

(22 citation statements)

References 20 publications

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“…It seems that bed rest leads to an increase in proinflammatory cytokine secretion as shown during a 113-day HDT bed rest study (Schmitt et al 1996). Time-course measurements, however, are not available in this experiment.…”

Section: Inflammatory Processesmentioning

confidence: 76%

From space to Earth: advances in human physiology from 20 years of bed rest studies (1986–2006)

Traon¹,

et al. 2007

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Bed rest studies of the past 20 years are reviewed. Head-down bed rest (HDBR) has proved its usefulness as a reliable simulation model for the most physiological effects of spaceflight. As well as continuing to search for better understanding of the physiological changes induced, these studies focused mostly on identifying effective countermeasures with encouraging but limited success. HDBR is characterised by immobilization, inactivity, confinement and elimination of Gz gravitational stimuli, such as posture change and direction, which affect body sensors and responses. These induce upward fluid shift, unloading the body's upright weight, absence of work against gravity, reduced energy requirements and reduction in overall sensory stimulation. The upward fluid shift by acting on central volume receptors induces a 10-15% reduction in plasma volume which leads to a now well-documented set of cardiovascular changes including changes in cardiac performance and baroreflex sensitivity that are identical to those in space. Calcium excretion is increased from the beginning of bed rest leading to a sustained negative calcium balance. Calcium absorption is reduced. Body weight, muscle mass, muscle strength is reduced, as is the resistance of muscle to insulin. Bone density, stiffness of bones of the lower limbs and spinal cord and bone architecture are altered. Circadian rhythms may shift and are dampened. Ways to improve the process of evaluating countermeasures--exercise (aerobic, resistive, vibration), nutritional and pharmacological--are proposed. Artificial gravity requires systematic evaluation. This review points to clinical applications of BR research revealing the crucial role of gravity to health.

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Section: Inflammatory Processesmentioning

confidence: 76%

From space to Earth: advances in human physiology from 20 years of bed rest studies (1986–2006)

Traon¹,

et al. 2007

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“…Previous studies have demonstrated that natural killer (NK) cells were seen to decrease in number. 10,12,19 The number and proliferation of lymphocytes has been shown to decrease in bed rest. 19,30 CD3 1 T cells and monocytes indicated a decreased level in bed rest.…”

Section: Introductionmentioning

confidence: 99%

Effects of 60-day bed rest with and without exercise on cellular and humoral immunological parameters

et al. 2014

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Exercise at regular intervals is assumed to have a positive effect on immune functions. Conversely, after spaceflight and under simulated weightlessness (e.g., bed rest), immune functions can be suppressed. We aimed to assess the effects of simulated weightlessness (Second Berlin BedRest Study; BBR2-2) on immunological parameters and to investigate the effect of exercise (resistive exercise with and without vibration) on these changes. Twenty-four physically and mentally healthy male volunteers (20-45 years) performed resistive vibration exercise (n57), resistance exercise without vibration (n58) or no exercise (n59) within 60 days of bed rest. Blood samples were taken 2 days before bed rest, on days 19 and 60 of bed rest. Composition of immune cells was analyzed by flow cytometry. Cytokines and neuroendocrine parameters were analyzed by Luminex technology and ELISA/RIA in plasma. General changes over time were identified by paired t-test, and exercise-dependent effects by pairwise repeated measurements (analysis of variance (ANOVA)). With all subjects pooled, the number of granulocytes, natural killer T cells, hematopoietic stem cells and CD45RA and CD25 co-expressing T cells increased and the number of monocytes decreased significantly during the study; the concentration of eotaxin decreased significantly. Different impacts of exercise were seen for lymphocytes, B cells, especially the IgD 1 subpopulation of B cells and the concentrations of IP-10, RANTES and DHEA-S. We conclude that prolonged bed rest significantly impacts immune cell populations and cytokine concentrations. Exercise was able to specifically influence different immunological parameters. In summary, our data fit the hypothesis of immunoprotection by exercise and may point toward even superior effects by resistive vibration exercise.

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“…Analogous experimental conditions, mainly confinement [9,20,28,30] and head-down tilt bed rest (HDT) [7,12,17,23], have been undertaken in order to differentiate and identify various spaceflight-related factors influencing the immune system. HDT reproduces many of the physiological changes observed in space, such as redistribution of body fluids and cardiovascular deconditioning [2,26], bone demineralization [15,31] and muscle atrophy [6], after several days or weeks.…”

Section: Introductionmentioning

confidence: 99%

“…It seems likely altered immune function plays an important role in the origin of these diseases. In a previous study we showed that immediately after a 4-week HDT, a significant decrease of interleukin-2 (IL-2) secretion by T-lymphocytes occurred in response to low doses of phytohaemagglutinin-P (PHA), whilst an increase in IL-1 secretion was observed during a 119-day-period of HDT [23]. Experiments with anti-orthostatically suspended rodents showed that in vitro immune disturbances occur as well, such as a decrease in interferon-α/β production [4], and in vivo immune changes such as greater sensitivity to viral infection [19].…”

Section: Introductionmentioning

confidence: 99%

Head-down tilt bed rest and immune responses

Schmitt

Schwarzenberg

Tkaczuk

et al. 2000

Pflügers Arch - Eur J Physiol

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BROWSKI. Rat cardiovascular responses to whole body suspension: head-down and non-head-down tilt. J. Appl. Physiol. 73(4): 1504-1509, 1992.-The rat whole body suspension technique mimics responses seen during exposure to microgravity and was evaluated as a model for cardiovascular responses with two series of experiments. In one series, changes were monitored in chronically catheterized rats during 7 days of head-down tilt (HDT) or non-head-down tilt (N-HDT) and after several hours of recovery. Elevations of mean arterial (MAP), systolic, and diastolic pressures of _20% (P < 0.05) in HDT rats began as early as day I and were maintained for the duration of suspension. Pulse pressures were relatively unaffected, but heart rates were elevated _ 10%. During postsuspension (2-7 h), most car-diovascular parameters returned to presuspension levels. N-HDT rats exhibited elevations chiefly on days 3 and 7. In the second series, blood pressure was monitored in 1-and 3-day HDT and N-HDT rats to evaluate responses to rapid head-up tilt. MAP, systolic and diastolic pressures, and HR were elevated (P < 0.05) in HDT and N-HDT rats during head-up tilt after 1 day of suspension, while pulse pressures remained unchanged. HDT rats exhibited elevated pretilt MAP and failed to respond to rapid head-up tilt with further increase of MAP on day 3, indicating some degree of deconditioning. The whole body suspended rat may be useful as a model to better understand responses of rats exposed to microgravity. mean arterial blood pressure; systolic blood pressure; diastolic blood pressure; pulse pressure; heart rate; weightlessness; mi-crogravity

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Use of Bed Rest and Head-Down Tilt to Simulate Spaceflight-Induced Immune System Changes

Cited by 26 publications

References 20 publications

From space to Earth: advances in human physiology from 20 years of bed rest studies (1986–2006)

From space to Earth: advances in human physiology from 20 years of bed rest studies (1986–2006)

Effects of 60-day bed rest with and without exercise on cellular and humoral immunological parameters

Head-down tilt bed rest and immune responses

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