Microgravity induces alterations in the function- ing of immune cell; however, the underlying mechanisms have not yet been identified. In this study, hemocytes (blood cells) of the blue mussel Mytilus edulis were investigated under altered gravity conditions. The study was conducted on the ground in preparation for the BIOLAB TripleLux- B experiment, which will be performed on the International Space Station (ISS). On-line kinetic measurements of reac- tive oxygen species (ROS) production during the oxidative burst and thus cellular activity of isolated hemocytes were performed in a photomultiplier (PMT)-clinostat (simulated microgravity) and in the 1g operation mode of the clino- stat in hypergravity on the Short-Arm Human Centrifuge (SAHC) as well as during parabolic flights. In addition to studies with isolated hemocytes, the effect of altered gravity conditions on whole animals was investigated. For this pur- pose, whole mussels were exposed to hypergravity (1.8 g) on a multi-sample incubator centrifuge (MuSIC) or to simu- lated microgravity in a submersed clinostat. After exposure for 48 h, hemocytes were taken from the mussels and ROS production was measured under 1 g conditions. The results from the parabolic flights and clinostat studies indicate that mussel hemocytes respond to altered gravity in a fast and reversible manner. Hemocytes (after cryo-conservation)exposed to simulated microgravity (μ g), as well as fresh hemocytes from clinorotated animals, showed a decrease in ROS production. Measurements during a permanent exposure of hemocytes to hypergravity (SAHC) show a decrease in ROS production. Hemocytes of mussels mea- sured after the centrifugation of whole mussels did not show an influence to the ROS response at all. Hypergravity dur- ing parabolic flights led to a decrease but also to an increase in ROS production in isolated hemocytes, whereas the cen- trifugation of whole mussels did not influence the ROS response at all. This study is a good example how ground- based facility experiments can be used to prepare for an upcoming ISS experiment, in this case the TRIPLE LUX B experiment.
Research Containing: immune system
Transient gene and microRNA expression profile changes of confluent human fibroblast cells in spaceflight
Microgravity, or an altered gravity environment different from the 1 g of the Earth, has been shown to influence global gene expression patterns and protein levels in cultured cells. However, most of the reported studies that have been conducted in space or by using simulated microgravity on the ground have focused on the growth or differentiation of these cells. It has not been specifically addressed whether nonproliferating cultured cells will sense the presence of microgravity in space. In an experiment conducted onboard the International Space Station, confluent human fibroblast cells were fixed after being cultured in space for 3 and 14 d, respectively, to investigate changes in gene and microRNA (miRNA) expression profiles in these cells. Results of the experiment showed that on d 3, both the flown and ground cells were still proliferating slowly, as measured by the percentage of Ki-67(+) cells. Gene and miRNA expression data indicated activation of NF-kappaB and other growth-related pathways that involve hepatocyte growth factor and VEGF as well as the down-regulation of the Let-7 miRNA family. On d 14, when the cells were mostly nonproliferating, the gene and miRNA expression profile of the flight sample was indistinguishable from that of the ground sample. Comparison of gene and miRNA expressions in the d 3 samples, with respect to d 14, revealed that most of the changes observed on d 3 were related to cell growth for both the flown and ground cells. Analysis of cytoskeletal changes via immunohistochemistry staining of the cells with antibodies for alpha-tubulin and fibronectin showed no difference between the flown and ground samples. Taken together, our study suggests that in true nondividing human fibroblast cells in culture, microgravity experienced in space has little effect on gene and miRNA expression profiles.-Zhang, Y., Lu, T., Wong, M., Wang, X., Stodieck, L., Karouia, F., Story, M., Wu, H. Transient gene and microRNA expression profile changes of confluent human fibroblast cells in spaceflight.
The effect of microgravity on the in vitro NK cell function during six International Space Station Missions
The level of natural killer (NK) cytotoxic activity was measured during co-cultivation of human lymphocytes and target cells (K- 562) in microgravity. Flight experiments were carried out using special instrumentation, the “Fibroblast-1” cassettes, in the frame of Russian scientific program during six ISS missions. Lymphocyte suspensions from human venous blood were used in experiments during short-term flights on six ISS missions (7 –12). Russian space crew members performed the experiments after Soyuz docking. The first step was mixing lymphocytes and 3H-labeled K-562 cells and their incubation at 37°C during 24 hs; the second step was filtration of the cell suspension. The frozen medium and filters were analyzed for the cytokine level and cytotoxic activity after landing. It was found that lympho- cytes with different basal levels of cytotoxic activity kept the ability of recognizing and lysing malignant cells. In micrograv- ity, cytotoxity increased to 160% of the basal levels. Donor indi- vidual features modulated the magnitude of the increase. The measurement of interleukin levels (TNF-α, IL-1, IL-2) in medi- um showed that synthesis of TNF-α increased during cell co-cul- tivation in microgravity. The level of IL-2 was very low in flight and ground control samples. The production of IL-1 by lympho- cytes decreased after in-flight incubation. The results indicate that microgravity did not disturb the cytotoxic function of immune cells in vitro during 24 h incubation with specific target cells.
BACKGROUND: It is currently unknown whether immune system alterations persist during long-duration spaceflight. In this study various adaptive immune parameters were assessed in astronauts at three intervals during 6-month spaceflight on board the International Space Station (ISS). AIMS: To assess phenotypic and functional immune system alterations in astronauts participating in 6-month orbital spaceflight. METHODS: Blood was collected before, during, and after flight from 23 astronauts participating in 6-month ISS expeditions. In-flight samples were returned to Earth within 48 h of collection for immediate analysis. Assays included peripheral leukocyte distribution, T-cell function, virus-specific immunity, and mitogen-stimulated cytokine production profiles. RESULTS: Redistribution of leukocyte subsets occurred during flight, including an elevated white blood cell (WBC) count and alterations in CD8+ T-cell maturation. A reduction in general T-cell function (both CD4+ and CD8+) persisted for the duration of the 6-month spaceflights, with differential responses between mitogens suggesting an activation threshold shift. The percentage of CD4+ T cells capable of producing IL-2 was depressed after landing. Significant reductions in mitogen-stimulated production of IFNγ, IL-10, IL-5, TNFα, and IL-6 persisted during spaceflight. Following lipopolysaccharide (LPS) stimulation, production of IL-10 was reduced, whereas IL-8 production was increased during flight. CONCLUSIONS: The data indicated that immune alterations persist during long-duration spaceflight. This phenomenon, in the absence of appropriate countermeasures, has the potential to increase specific clinical risks for crewmembers during exploration-class deep space missions.
INTRODUCTION: Short-term spaceflight is associated with significant but reversible immunological alterations. However, little information exists on the effects of long-duration spaceflight on neuroimmune responses. METHODS: We collected multiple pre- and postflight samples from Shuttle and International Space Station (ISS) crewmembers in order to compare adrenocortical and immune responses between short- (approximately 11 d) and long-duration (approximately 180 d) spaceflight. RESULTS: In Shuttle crewmembers, increased stress hormone levels and altered leukocyte subsets were observed prior to launch and at landing. Additionally, typical stress-induced shifts in leukocyte and lymphocyte subsets, as well as the percentage of T-cells capable of producing intracellular IFN-gamma were also decreased just before launch and immediately after landing. Plasma IL-10 levels were increased before launch but not postflight. No preflight changes occurred in ISS crewmembers, but long-duration crewmembers exhibited significantly greater spikes in both plasma and urinary cortisol at landing as compared to Shuttle crewmembers. The percentage of T-cells capable of producing intracellular IFN-gamma was decreased in ISS crewmembers. Plasma IL-10 was increased postflight. Unexpectedly, stress-induced shifts in lymphocyte subpopulations were absent after long-duration flights despite significantly increased stress hormones at landing. CONCLUSION: Our results demonstrate significant differences in neuroimmune responses between astronauts flying on short-duration Shuttle missions versus long-duration ISS missions, and they agree with prior studies demonstrating the importance of mission duration in the magnitude of these changes.
Spaceflight effects on the immune system were studied in 30 cosmonauts flown onto the International Space Station (ISS) for long- (125–195 d, n = 15 ) and short-term (8–10 d, n = 15 ) missions. Immunological investigations before launch and after landing were performed by using methods for quantitative and functional evaluation of the immunologically competent cells. Specific assays include: peripheral leukocyte distribution, natural killer (NK) cell cytotoxic activity, phagocytic activity of monocytes and granulocytes, proliferation of T-cells in response to a mitogen, levels of immunoglobulins IgA, IgM, IgG, virus-specific antibody and cytokine in serum. It was noticed that after long-term spaceflights the percentage of NK ( CD 3 – / CD 16 + / CD 56 + ) cells was significantly reduced compared with pre-flight data ( p < 0.05 ) and NK activity was suppressed by 20–85% as compared with pre-flight data in 12 out of 15 cosmonauts. T-lymphocyte activity was decreased by 25–39% as compared with pre-flight data in 5 out of 13 cosmonauts. However, the relative number of CD 3 + , CD 4 + and CD 8 + T-cells did not change. The functional activity of NK and T-cells decreased in some of the cosmonauts after short-term missions. On the other hand, a moderate trend upward of NK cytotoxic activity and proliferative activity of T-cells was observed in some individuals. Concentrations immunoglobulins (IgA, IgM, IgG) and levels of M and G antibodies to herpes simplex virus (HSV), cytomegalovirus (CMV), Epstein–Barr virus (EBV) and herpes virus type 6 (HV6) in serum did not reveal significant changes after long- and short-term flights. Concentrations of cytokines (IL- 1 β , IL-2, IL-4 and TNF- α ) in serum changed in an apparently random manner as compared with values before long- and short-term missions. Despite the fact that many improvements have been made to the living conditions of aboard the ISS our investigations demonstrate the remarkable depression of the immunological function after the ISS missions. These results suggest that the clinical health risk (related to immune dysfunction) will occur during exploration class missions.
Long-duration spaceflight effects on T-cell immunity and cytokine production were studied in 12 Russian cosmonauts flown onto the International Space Station. Specific assays were performed before launch and after landing and included analysis of peripheral leukocyte distribution, analysis of T-cell phenotype, expression of activation markers, apoptosis, proliferation of T cells in response to a mitogen, concentrations of cytokines in supernatants of cell cultures. Statistically significant increase was observed in leukocytes’, lymphocytes’, monocytes’ and granulocytes’ total number, increase in percentage and absolutely number of CD3+CD4+-cells, CD4+CD45RA+-cells and CD4+CD45RA+/CD4+CD45RО+ ratio, CD4+CD25+Bright regulatory cells (p<0,05) in peripheral blood after landing. T-lymphocytes’ capacity to present CD69 and CD25 on its own surfaces was increased for the majority of crewmembers. Analysis of T-cell response to PHA-stimulation in vitro revealed there were some trends toward reduced proliferation of stimulated T-lymphocytes. There was an apparent post flight decrease in secreted IFN-g for the majority of crewmembers and in most instances there was elevation in secreted IL-10. It revealed depression of IFN-g/IL-10 ratio after flight. Correlation analysis according to Spearman’s rank correlation test established significant positive correlations (p<0.05) between cytokine production and T-cell activation (CD25+, CD38+) and negative correlation (p<0.05) between cytokine production and number of bulk memory CD4+T-cells (CD45RO+). Thus, these results suggest that T-cell dysfunction can be conditioned by cytokine dysbalance and could lead to development of disease after long-duration space flights.
Spaceflight alters the migratory ability of stem cell derived keratinocytes resulting in decreased wound healing potential
Spaceflight is known to have detrimental effects on most systems of the human body, including the musculoskeletal system, immune system and cardiovascular system, whilst also impairing many normal physiological processes, such as wound closure. We hypothesized that somatic stem cells, responsible for tissue regeneration, require mechanical stimulation in the form of gravity to regenerate tissues at normal rates, and that spaceflight conditions, specifically microgravity, may interfere with their proliferation and differentiation resulting in the widespread degeneration of tissues observed in space. We investigated this hypothesis by inducing embryonic stem cells to form embryoid bodies, a model of differentiated tissue, in microgravity for 15 days on shuttle mission STS-131. Results show that there was no alteration in the ability of embryoid bodies to adhere to and spread on a collagen matrix upon return to 1g and there was no difference in viability of flight and ground control samples. However, qRT-PCR analysis indicated that many genes involved in maintenance of stem cell pluripotency failed to turn off and differentiation of normal germlayer markers was inhibited following spaceflight, indicating an alteration in the normal differentiation process. This lead us to conduct a more in-depth experiment to analyse the differentiation process in one specific cell type, the keratinocyte, and additionally to investigate the effects of spaceflight on the ability of keratinocytes to conduct effective wound closure.
INTRODUCTION: Immune system dysregulation has been demonstrated to occur during and immediately following spaceflight. If found to persist during lengthy flights, this phenomenon could be a serious health risk to crewmembers participating in lunar or Mars missions. METHODS: A comprehensive postflight immune assessment was performed on 17 short-duration Space Shuttle crewmembers and 8 long-duration International Space Station (ISS) crewmembers. Testing consisted of peripheral leukocyte subset analysis, early T cell activation potential, and intracellular/secreted cytokine profiles. RESULTS: For Shuttle crewmembers, the distribution of the peripheral leukocyte subsets was found to be altered postflight. Early T cell activation was elevated postflight; however, the percentage of T cell subsets capable of being stimulated to produce IL-2 and IFN gamma was decreased. The ratio of secreted IFN gamma:IL-10 following T cell stimulation declined after landing, indicating a Th2 shift. For the ISS crewmembers, some alterations in peripheral leukocyte distribution were also detected after landing. In contrast to Shuttle crewmembers, the ISS crewmembers demonstrated a statistically significant reduction in early T cell activation potential immediately postflight. The percentage of T cells capable of producing IL-2 was reduced, but IFN gamma percentages were unchanged. A reduction in the secreted IFN gamma:IL-10 ratio (Th2 shift) was also observed postflight in the ISS crewmembers. CONCLUSION: These data indicate that consistent peripheral phenotype changes and altered cytokine production profiles occur following spaceflight of both short and long duration; however, functional immune dysregulation may vary related to mission duration. In addition, a detectable Th2 cytokine shift appears to be associated with spaceflight.
BACKGROUND: Dysregulation of the immune system has been shown to occur during spaceflight, although the detailed nature of the phenomenon and the clinical risks for exploration class missions have yet to be established. Also, the growing clinical significance of immune system evaluation combined with epidemic infectious disease rates in third world countries provides a strong rationale for the development of field-compatible clinical immunology techniques and equipment. In July 2002 NASA performed a comprehensive immune assessment on field team members participating in the Haughton-Mars Project (HMP) on Devon Island in the high Canadian Arctic. The purpose of the study was to evaluate the effect of mission-associated stressors on the human immune system. To perform the study, the development of techniques for processing immune samples in remote field locations was required. Ten HMP-2002 participants volunteered for the study. A field protocol was developed at NASA-JSC for performing sample collection, blood staining/processing for immunophenotype analysis, whole-blood mitogenic culture for functional assessments and cell-sample preservation on-location at Devon Island. Specific assays included peripheral leukocyte distribution; constitutively activated T cells, intracellular cytokine profiles, plasma cortisol and EBV viral antibody levels. Study timepoints were 30 days prior to mission start, mid-mission and 60 days after mission completion. RESULTS: The protocol developed for immune sample processing in remote field locations functioned properly. Samples were processed on Devon Island, and stabilized for subsequent analysis at the Johnson Space Center in Houston. The data indicated that some phenotype, immune function and stress hormone changes occurred in the HMP field participants that were largely distinct from pre-mission baseline and post-mission recovery data. These immune changes appear similar to those observed in astronauts following spaceflight. CONCLUSION: The immune system changes described during the HMP field deployment validate the use of the HMP as a ground-based spaceflight/planetary exploration analog for some aspects of human physiology. The sample processing protocol developed for this study may have applications for immune studies in remote terrestrial field locations. Elements of this protocol could possibly be adapted for future in-flight immunology studies conducted during space missions.