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J Appl Physiol 94: 2095-2103, 2003. First published December 27, 2002; doi:10.1152/japplphysiol.01053.2002
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Vol. 94, Issue 5, 2095-2103, May 2003

HIGHLIGHTED TOPICS
Genetic Models in Applied Physiology
Selected Contribution: Effects of spaceflight on immunity in the C57BL/6 mouse. II. Activation, cytokines, erythrocytes, and platelets

Daila S. Gridley1,2, Gregory A. Nelson1, Luanne L. Peters3, Paul J. Kostenuik4, Ted A. Bateman5,6, Sean Morony4, Louis S. Stodieck5, David L. Lacey4, Steven J. Simske5, and Michael J. Pecaut1

Departments of 1 Radiation Medicine, Radiobiology Program, and 2 Biochemistry and Microbiology, Division of Microbiology and Molecular Genetics, Loma Linda University and Medical Center, Loma Linda, California 92354; 5 Department of Aerospace Engineering, BioServe Space Technologies, University of Colorado, Boulder, Colorado 80309-0429; 6 Bioengineering Department, Clemson University, Clemson, South Carolina 29634; 3 Jackson Laboratory, Bar Harbor, Maine 04609; and 4 Amgen Incorporated, Thousand Oaks, California 91320-1789


    ABSTRACT
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ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES

This portion of the study quantified the effects of a 12-day space shuttle mission (Space Transport System-108/UF-1) on body and lymphoid organ masses, activation marker expression, cytokine secretion, and erythrocyte and thrombocyte characteristics in C57BL/6 mice. Animals in flight (Flt group) had 10-12% lower body mass compared with ground controls housed either in animal enclosure modules or under standard vivarium conditions (P < 0.001) and the smallest thymus and spleen masses. Percentages of CD25+ lymphocytes, CD3+/CD25+ T cells, and NK1.1+/CD25+ natural killer cells from Flt mice were higher compared with both controls (P < 0.05). In contrast, CD71 expression was depressed in the Flt and animal enclosure module control mice compared with vivarium control animals (P < 0.001). Secretion of interferon-gamma , IL-2, and IL-4, but not tumor necrosis factor-alpha and IL-5, by splenocytes from Flt mice was decreased relative to either one or both ground controls (P < 0.05). Flt mice also had high red blood cell and thrombocyte counts compared with both sets of controls; low red blood cell volume and distribution width, percentage of reticulocytes, and platelet volume were also noted (P < 0.05) and were consistent with dehydration. These data indicate that relatively short exposure to the spaceflight environment can induce profound changes that may become significant during long-term space missions.

microgravity; immune system; activation markers; interferon-gamma ; interleukin-2; interleukin-4; red blood cells; thrombocytes


    INTRODUCTION
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ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES

ALTHOUGH VARIOUS ASPECTS OF the space environment can influence many physiological systems (5, 28, 46, 57), immune dysfunction with its potentially serious consequences is a major concern (6, 53, 59). In addition, the phenomenon of "astronaut anemia" has been well described (29, 34), and perturbations in thrombocyte parameters may be associated with poor wound healing in space (17). The combination of weightlessness, radiation, and psychological stress may exert additive or synergistic effects that could severely compromise performance during extended missions in space (62). Because residence on the International Space Station is on-going, and plans for inhabited lunar bases and staffed explorations of Mars are in progress, more information is urgently needed regarding the changes in immune and other body systems so that realistic health risk estimates can be made. The information is also needed so that appropriate countermeasures can be developed to ameliorate any adverse effects that may be significant.

The data obtained over nearly three decades in studies of astronauts and cosmonauts, monkeys, and rats involved in space shuttle, Skylab, Cosmos, and Mir space station missions provide strong evidence for numerous immune and other aberrations. However, the findings have frequently been inconsistent (reviewed in Refs. 22, 37). The apparent discrepancies may well be related to variations in genetic background of humans, experimental animal species, mission length, degree of stress, ambient CO2, lighting and temperature, and specific types of assays used. The complexity of the immune system, with numerous cell types and subtypes capable of producing and responding to an intricate network of multifunctional cytokines, and differences in the microenvironment of circulating vs. fixed cell populations in lymphoid organs are undoubtedly also important factors.

In addition, conclusions from studies regarding changes in immune system structure and function due to spaceflight have been somewhat limited over the years because the reagents and other appropriate tools were not always available, especially with respect to experimental animals. The mouse is a good candidate for immune studies because it has been highly characterized under normal, as well as numerous abnormal, conditions, and a plethora of appropriate reagents are readily available. However, for the relatively few spaceflight studies with rodents, the rat has been consistently selected over the mouse due to lack of space hardware support for mice without astronaut intervention. This handicap has recently been overcome.

The data reported here and in the accompanying paper [part I by Pecaut et al. (45a)] are the first to be obtained from nonneonatal mice exposed to the spaceflight environment. These rodents were flow on the space shuttle Endeavor [Space Transport System (STS)-108/UF-1] to the International Space Station in December 2001. The primary goal of this experiment was to test a potential osteoporosis drug for the biotechnology company Amgen and to examine the degree to which spaceflown mice are a model for osteoporosis. The nonskeletal tissues from calcein (placebo)-treated mice were utilized to further examine the potential for immune-related mouse models. According to published reports, calcein has a half-life measured in minutes (4) and is cleared from blood circulation within a few hours (48). In vivo studies strongly indicate that calcein has no effects on leukocyte population distribution or function (9, 18, 19, 65). Hence, we expected no significant calcein effect on the parameters measured in this study. The data presented here and in the accompanying paper by Pecaut et al. (45a) should facilitate further investigations of spaceflight-induced immune modulation by using wild-type C57BL/6 mice. Inclusion of knockout, transgenic, and hybrid rodents in future studies should lead to identification of specific mechanisms responsible for the observed immune aberrations.


    MATERIALS AND METHODS
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ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES

Animals, food, and water. Female C57BL/6 mice (n = 36; Jackson Laboratory, Bar Harbor, ME) were acclimatized and assigned to three groups (n = 12/group): flight mice housed in animal enclosure module (AEM) hardware [National Aeronautics and Space Administration (NASA) Ames Research Center, Moffett Field, CA], ground controls kept in AEMs, and vivarium controls kept under standard conditions. These three groups are hereafter referred to as Flt, AEM, and Viv, respectively. The Flt group was flown in space shuttle Endeavor (STS-108/UF-1) for nearly 12 days and euthanized within 3.5-5 h after landing. All mice were euthanized with the use of isoflurane at 77 days of age. All mice received rodent chow in the form of large solid bars that had an initial water content of 25% and distilled, autoclaved water ad libitum. The food was weighed immediately before mouse transport to the shuttle and again shortly after landing. Specially designed water-containing bottles were similarly weighed, but with three additional weigh and refill times for the Viv controls. The amounts of food and water consumed per mouse per day within each group were calculated. Further details regarding housing and other environmental conditions are described in the accompanying paper (45a). This study was approved by all appropriate Institutional Animal Care and Use Committees.

Body and organ masses and blood collection. At euthanasia, total body, thymus, and spleen mass were taken. Normalized organ mass (NOM) was calculated: NOM = organ mass (mg)/body mass (g). Whole blood was obtained by cardiac puncture at the time of euthanasia and immediately placed into K2-EDTA-coated microhematocrit tubes and shipped with ice packs by overnight express to Jackson Laboratory for evaluation. Approximately one-third of the spleen was shipped to Loma Linda University in sterile screw-capped tubes containing complete RPMI-1640 medium (with 20% heat-inactivated bovine calf serum) on wet ice. Single-celled suspensions of spleen leukocytes were obtained as described previously (45, 24). Spleen cell viability was manually determined on arrival at Loma Linda University with a hemocytometer by using the Trypan blue exclusion method.

Quantification of activation and proliferation markers. Spleen leukocyte samples were evaluated by using a FACSCalibur flow cytometer (Becton Dickinson, San Jose, CA), as previously described (24, 31, 45). CD45 and side scatter were used for gating the total lymphocyte population. The cells expressing CD25, CD71, CD3/CD25, CD3/CD71, natural killer (NK) 1.1/CD25, and NK1.1/CD71 markers were identified by using four-color, two-tube mixtures of fluorescence-labeled MAb that were specially prepared by Pharmingen (San Diego, CA) in collaboration with Becton Dickinson. One tube contained CD25 * FITC/CD71 * phycoerythrin/CD45 * peridinin chlorophyll/CD3 * allophycocyanin by using MAb derived from clones C2, PK136, 145-2C11, and PC61, respectively. The other tube contained CD71 * FITC/NK1.1 * phycoerythrin/CD3e * peridinin chlorophyll/CD25 * allophycocyanin, with clones in sequence being 7D4, C2, 30-F11, and 145-2C11, respectively. At least 5,000 events per tube were acquired, and analysis was performed by using CellQuest software version 3.1 (Becton Dickinson).

Bead array quantification of cytokines. Spleen leukocytes were counted and diluted with supplemented RPMI-1640 medium (Irvine Scientific) to 1 × 106 cells/ml, and 0.1-ml aliquots were dispensed into wells of 96-well microculture plates. Aliquots of phytohemagglutinin (PHA; Sigma Chemical, St. Louis, MO) were immediately added at 0.1 ml/well. After a 48-h incubation period, the supernatants were aspirated, cells and debris were removed by centrifugation, and the levels of IFN-gamma , TNF-alpha , IL-2, IL-4, and IL-5 were quantified by using the cytometric bead array assay (Becton Dickinson), according to the manufacturer's instructions. Supernatants from nonstimulated cells were collected from three mice per group and tested for background cytokine levels. This assay uses amplified fluorescence detection by flow cytometry to measure soluble analytes in a particle-based immunoassay. The cytometric bead array capture bead mixture is in suspension to allow for the detection of multiple analytes in a small-volume sample. Cytokine concentrations in each test sample were interpolated from the appropriate standard curve.

Hematological analysis. Whole blood samples were diluted 1:4 in PBS at Jackson Laboratory and analyzed by using the Advia 120 hematology system (Bayer, Tarrytown, NY). High-quality samples were available from four to nine mice per group. Results reported here include the following: red blood cell (RBC) and platelet (Plt) counts; Hb concentration; Hct (percentage of whole blood composed of RBC); mean corpuscular volume (MCV, mean volume per RBC); mean Plt volume; RBC distribution width (RDW); mean corpuscular Hb (MCH, mean weight of Hb per RBC); MCH concentration (mean concentration of Hb per RBC); and Hb distribution width (HDW).

Statistical analysis. The data were evaluated by using one-way ANOVA; Tukey's pairwise multiple-comparison test was used to determine significant difference between each set of two groups (SigmaStat software, version 2.03; SPSS, Chicago, IL). P values of <0.05 and <0.1 were selected to indicate significance and a trend, respectively.


    RESULTS
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INTRODUCTION
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Food and water consumption. A main effect of flight condition was observed for both food and water consumption (P < 0.001). Flt and Viv mice ingested similar amounts of food: 2.85 ± 0.05 and 2.81 ± 0.05 g · mouse-1 · day-1, respectively. Both of these groups, however, consumed significantly less (P < 0.001) than the AEM ground controls, which ate 3.74 ± 0.10 g · mouse-1 · day-1. A similar pattern was observed for drinking water, with Flt and Viv animals taking in less than the AEM ground controls (P < 0.005). Mean values for water consumed were 2.57 ± 0.18 (Flt), 2.22 ± 0.18 (Viv), and 4.28 ± 0.20 ml · mouse-1 · day-1 (AEM).

Body and lymphoid organ mass and splenocyte viability. There were no significant differences in total body mass across groups before flight (data not shown). Masses ranged from 18.3 ± 0.2 to 18.6 ± 0.2 g in the Flt and AEM groups, respectively. As indicated in Table 1, there was a main effect of flight condition on total body, spleen, normalized spleen, thymus, and normalized thymus masses (<= P < 0.005). Flt animals weighed significantly less than AEM and Viv controls (P < 0.001 compared with both control groups). There was no difference between the two control groups in this measure. Spleen and normalized spleen masses in Flt animals were significantly decreased compared with that in both ground controls (P < 0.005). However, thymus and normalized thymus masses for Flt animals were significantly lower than for Viv (P < 0.005), but not AEM, mice. There were significant decreases in spleen and thymus masses in AEM compared with Viv controls (P < 0.05). Spleen cell viability was similar among the three groups: 74.8 ± 2.5% (Flt), 73.4 ± 2.5% (AEM), and 71.3 ± 4.4% (Viv).

                              
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  		Table 1.   Body and lymphoid organ masses

Expression of activation and proliferation markers. A main effect of flight condition was observed in the expression of CD25 and CD71 markers, either alone or together with CD3 or NK1.1, by spleen lymphocytes (P < 0.005 for both variables). Figure 1 shows that the percentages of single-positive CD25+ lymphocytes, as well as the cells expressing CD25 together with either CD3 or NK1.1, were significantly higher in Flt mice compared with both control groups (P < 0.05). In contrast, the percentages of single-positive CD71 cells were significantly depressed in both the Flt and AEM groups compared with the Viv control mice (P < 0.001). Mean values for cells with CD3/CD71 were also lower in these two groups compared with the Viv group (P < 0.001), but the difference between Flt and Viv was less than between AEM and Viv. A similar pattern was noted in NK1.1/CD71 expression, with Flt mice having a mean value intermediate between the AEM and Viv controls. In all three groups, the CD3+ and NK1.1+ cells accounted for nearly all of the CD25-expressing population, whereas the majority of lymphocytes with CD71 did not express either CD3 or NK1.1.


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  		Fig. 1.   Expression of activation and proliferation markers by splenic lymphocytes. Identification of lymphocyte populations expressing specific markers was obtained utilizing fluorescence-labeled monoclonal antibodies and flow cytometry. A: CD25 and CD71. B: CD3/CD25 and CD3/CD71. C: NK1.1/CD25 and NK1.1/CD71. Flt, flight group; AEM, ground controls kept in animal enclosure modules; Viv, vivarium controls. Values are means ± SE for 10-12 mice/group. One-way ANOVA: * P < 0.005 and ** P < 0.001 for main effect of flight condition. Significant difference vs. AEM: a P < 0.01, b P < 0.005, c P < 0.001. Significant difference vs. Viv: d P < 0.05, e P < 0.01, f P < 0.001.

Cytokine secretion by activated spleen cells. Flight condition had a main effect on the levels of IFN-gamma , IL-2, and IL-4, but not on TNF-alpha and IL-5, secreted by PHA-activated splenocytes (P < 0.05) (Fig. 2). IFN-gamma and IL-4 concentrations for the Flt group were significantly lower than that for the AEM controls (P < 0.05), and IL-2 concentrations were significantly lower than those for both the AEM and Viv groups (P < 0.001 and P < 0.05, respectively). The IL-2 mean for Viv mice was lower than for AEM mice (P < 0.001). Splenocytes from all groups secreted a similar amount of TNF-alpha . None of the tested cytokines was detected in supernatants from nonstimulated spleen cells, with the exception of IFN-gamma in one of three tested samples from the Viv mice (1.6 pg/ml).


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  		Fig. 2.   Cytokine secretion by activated splenocytes. Supernatants from spleen cells were obtained after 48 h of incubation with phytohemagglutinin. Cytokine concentrations were quantified by flow cytometry utilizing a cytometric bead array assay. Values are means ± SE for 10-12 mice/group. One-way ANOVA: * P < 0.05 and ** P < 0.001 for main effect of flight condition. Significant difference: a P < 0.05 vs. AEM, b P < 0.001 vs. AEM, and c P < 0.05 vs. Viv.

RBC characteristics. Figure 3 shows that flight condition had a significant effect on RBC counts (P < 0.05) and the percentage of reticulocytes (P < 0.005). RBC number was elevated (P < 0.05), and the proportion of reticulocytes was low (P < 0.005), in the Flt group compared with the AEM and Viv groups. Furthermore, a main effect of flight condition was found for RDW, MCV, and HDW (P < 0.05 or less) (Table 2). Pairwise comparisons indicated that the Flt group had significantly lower RDW and MCV than the AEM and Viv groups (P < 0.05 or less); HDW was higher only compared with the Viv mice (P < 0.05 or less), although a trend toward significance was noted compared with the AEM group (P < 0.1) (Table 2). There were no significant differences among groups in Hct, Hb concentration, MCH, and MCH concentration.


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  		Fig. 3.   Erythrocyte counts (A), percentage of reticulocytes (B), hematocrit (C), and hemoglobin (D). Whole blood was evaluated by using an automated procedure (Advia 120 Hematology System). RBC, red blood cell. Values are means ± SE for 4-9 mice/group. One-way ANOVA: * P < 0.05 and ** P < 0.005 for main effect of flight condition. Significant difference vs. AEM and Viv: a P < 0.05 and b P < 0.005.


                              
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  		Table 2.   Additional erythrocyte variables in peripheral blood

Plt characteristics. Flight condition had a main effect on Plt counts and volume (P < 0.001 for both) (Fig. 4). Post hoc Tukey analysis showed that Plt numbers in Flt mice were significantly increased (P < 0.01 or less), whereas the mean Plt volume was reduced (P < 0.05 or less), compared with AEM and Viv animals. The cell volume for the AEM mice was also significantly lower than for animals in the Viv group (P < 0.05).


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  		Fig. 4.   Platelet counts (A) and volume (B). Whole blood was evaluated by using an automated procedure (Advia 120 Hematology System). Values are means ± SE for 4-9 mice/group. * One-way ANOVA, P < 0.001 for main effect of flight condition. Significant difference: a P < 0.05 vs. AEM, b P < 0.05 vs. Viv, c P < 0.01 vs. AEM, d P < 0.001 vs. Viv.


    DISCUSSION
TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES

The results show that Flt mice weighed 12 and 10% less compared with AEM and Viv controls, respectively. This is in agreement with several other studies reporting a loss in body mass of rats after spaceflight (26, 28). It has been proposed that the reduction in body mass may be related to dehydration, less food consumption, and/or chronic elevation in glucocorticoids during flight (22, 26, 28, 54). However, in several other studies, body mass was found to be either increased (12, 46) or similar to that of ground controls (16, 66). The low body mass in our Flt mice may well be related to the relatively high temperatures in the housing modules [discussed in part I by Pecaut et al. (45a)] and concomitant factors such as stress and dehydration. Comprehensive human studies have found that astronauts tend to eat only 40-50% of predicted energy requirements and lose >10% of their preflight body mass (55). Decreases in body fluid and bone, which are seen as early as 1 wk and are still occurring at 312 days into spaceflight, undoubtedly contribute to the weight loss (35, 52).

The data also show that spleen mass, when normalized to body mass, was 18 and 28% lower compared with the two control groups, respectively, and that normalized thymus mass was reduced by ~28% in both the Flt and AEM mice compared with the Viv animals. The findings for the spleen are generally consistent with what has been previously reported for rats (28), although there is variation in the degree of change. For example, a 31% reduction in spleen mass was noted in rats flown for 4 days (STS-41), but Flt animals differed significantly only from the Viv, not AEM, control group. In another study, spleen mass in rats flown for 10 days (STS-57) was 23-28% lower than for control animals, and no difference was noted between AEM and Viv controls. Previous results with regard to the thymus appear to be more variable. Thymus mass or normalized thymus mass has been reported to be decreased (28), increased (46), or similar to controls (12, 16, 23).

Significantly altered patterns of cytokine production have been noted for cells maintained in vitro on board spacecraft and leukocytes obtained from rats, nonhuman primates, astronauts, and cosmonauts (reviewed in Refs. 10, 11, 58). Cytokines secreted by the T helper (Th) 1 and Th2 lymphocyte subsets are especially critical in the generation of effective cell-mediated and humoral immune responses (i.e., Th1 cells secrete cytokines, such as IL-2 and IFN-gamma , that promote T-lymphocyte activation and proliferation, whereas Th2 cells secrete IL-4 and IL-5 that support B-cell production of antibodies). Furthermore, there is increasing evidence that these cells are extremely important in homeostasis, as exemplified by the role of the Th1 subset in the maintenance of tolerance to self-antigens (13). Hence, we assessed splenocyte production of factors characteristic of Th1 (IL-2, IFN-gamma , and TNF-alpha ) and Th2 (IL-4 and IL-5) cells using PHA as the stimulating agent. The data show that only the IL-2 level was significantly reduced in the Flt mice compared with both the AEM and Viv control groups. Studies of flight crewmembers have generally shown diminished capacity to secrete cytokines, including IL-2 (10, 11, 25, 58). In a study with rats, IL-2 secretion by concanavalin A (ConA)-stimulated splenocytes was significantly decreased after the 7-day Cosmos 1557 flight (33). Reduced production of IL-2 (and five other cytokines) was reported in rats euthanized during flight (Spacelab Life Sciences-2 mission) when splenocytes were incubated with ConA (36). Because both PHA and ConA are T-cell antigen receptor-dependent mitogens (41, 43), it seems possible that the low IL-2 was due to suboptimal signal transduction via the T-cell antigen receptor. IL-2 is a major cytokine that stimulates proliferation of cytotoxic and helper T lymphocytes and also increases activities of NK cells and monocyte/macrophages (reviewed in Refs. 21, 61). Low capacity to produce IL-2 could seriously compromise immune defenses against infectious agents during extended space missions. The observation that memory T cells are protected from apoptotic death by IL-2 (40) implies that insufficient amounts of the factor could also endanger responsiveness to recall antigens (e.g., vaccines). However, below-normal IL-2 secretion is not an entirely consistent observation. After the 4-day STS-41 mission, IL-2 production by splenocytes was increased in flight rats (42) compared with ground controls, and, after the 10-day STS-57 mission, there were no differences between flight and control rats in IL-2 levels on stimulation of splenocytes with either PHA or ConA (27).

The degree of change in the expression of surface markers by lymphocytes is dependent on the conditions of the flight, specific type of marker analyzed, and source of the analyzed cells, as well as possibly other variables (reviewed in Ref. 56). In the relatively few studies in which CD25+ cells have been analyzed, no differences have been noted between flight and control rats (42, 27). However, in the present study, a significantly higher proportion of splenocytes from Flt mice expressed CD25, the receptor for IL-2 (IL-2R), compared with both control groups. This finding may reflect a classic upregulation of the IL-2R as compensation for decreased ability to secrete IL-2. This is consistent with the low levels of IL-2 found in the supernatants from the PHA-activated splenocytes from the Flt mice, i.e., as the ability to secrete IL-2 dropped, expression of CD25 was upregulated to make best use of what little IL-2 may become available. In addition, the increase in CD25 expression could be largely accounted for by CD3+ T and, to a much lesser extent, by NK1.1+ NK cells. Taken alone, these findings suggest that immune readiness may have been enhanced by flight conditions, because IL-2R expression is essential for clonal expansion and optimal activity of T cells. However, given that the capacity to produce IL-2 was low in Flt mice, immune responsiveness is unlikely to be enhanced. It is of interest to note here that CD25+ T cells that also express the CD4 marker are resistant to apoptosis and secrete IL-10 (a highly immunosuppressive cytokine) but not IL-2 (44). Unfortunately, simultaneous expression of CD4 and CD25 was not tested for in the present study.

To our knowledge, this is the first time that cells positive for CD71, the transferrin receptor, have been evaluated in experimental animals or humans after flight. The data show that both the Flt and AEM mice had low levels of lymphocytes expressing CD71, either singly or together with CD3 or NK1.1, compared with the Viv controls. Transferrin is a major iron-transport molecule, and numerous cell types that require iron for their development express the transferrin receptor (7). The binding of transferrin to its receptor results in endocytosis of the receptor-ligand-iron complex, thus providing the cell with iron for biosynthesis of iron-containing proteins, as well as other functions. This transferrin-mediated transport system may also be viewed as a defense mechanism, because an abundance of free iron has been associated with a wide range of diseases, including atherosclerosis, cardiomyopathy, arthritis, infection, neurodegeneration, and invasive tumor growth (64). The biological significance, if any, of depressed transferrin-receptor expression by T and NK cells in the present study requires further investigation.

Anemia is among the most consistent findings noted in flight personnel, as well as laboratory animals (2, 8, 15, 20, 39, 47). This condition occurs within 24 h after launch and is frequently symptomatic. In the present study, Flt mice had a significantly increased RBC count, decreased percentage of reticulocytes, and low variation in RBC size (RDW, anisocytosis) and volume (MCV), but there were no differences among groups in Hct or Hb. At least some of these observations may be associated with a reduction in plasma volume due to dehydration (63). In previous investigations, Alfrey and colleagues (1, 2, 50) found that the mechanisms underlying spaceflight anemia include a rapid and selective hemolysis of the most immature (<10 days old) circulating RBCs, i.e., "neocytolysis," and that this phenomenon also occurs in individuals acclimatized to high altitude who descend to sea level, as well as in dialysis patients with kidney disease. On entry into microgravity in space, more centralized pooling of blood occurs. Destruction of young RBCs may be a means of adjusting to this change. Neocytolysis apparently occurs when erythropoietin levels are suppressed below a critical minimum level, a process that may be cytokine induced (2, 51). This latter possibility, however, needs further investigation.

Studies of the effects of microgravity on various physiological systems, as well as observational data, strongly indicate that response to wounding and injury may be impaired in space (32). This suggests that the ability to survive a major physical trauma may be compromised. Studies in flight rats have demonstrated that healing of muscle, bone fractures, and skin is delayed and that response to growth factors, such as PDGF, injected at the wound site is reduced (17, 30, 60). Plts are among the numerous factors involved in the wound-healing process. Recent evidence indicates that they may play a much more important role in inflammation and vascular injury (i.e., in addition to their long-known role in walling off the inflamed area) than previously thought (38). The data presented here show that Flt mice had significantly increased Plt numbers and that their mean volume was low compared with that of both control groups. Thus it appears that lack of enough Plts may not present a problem. It is possible, however, that their functional status is impaired.

As mentioned earlier, the mice in this study, and in part I by Pecaut et al. (45a), were the calcein-injected controls for the osteoporosis drug being tested by Amgen. Although there is very little in the literature regarding the long-term effects of calcein on immunity, <1% of the dose remains free in the blood 2 h after intravenous injection (48), with a half-life of ~7 min (4). In a subcutaneous tumor model, calcein labeling peaked in both the tumor and "normal" underlying muscle tissue ~30 min after intravenous injection. By 65 min, labeling in both tissues was one-half of this peak value (4). In one feasibility study exploring the use of calcein to characterize lymphocyte migration, cells were labeled in vitro with calcein and injected (intravenously) into mice. Flow cytometric analysis of splenocytes labeling positive for calcein indicated that 80-90% were lost from cells within 15 h, with the remaining 10-20% released over the next 2-3 days (65).

However, even if calcein were to remain in the tissues, this highly charged fluorescent probe does not appear to react covalently with intracellular macromolecules or intercalate into cell membranes (49). Calcein does not appear to have an effect on neutrophil (18), macrophage (19), lymphocyte (18, 14), or thymocyte (3) viability. The literature also suggests that this fluorochrome does not affect NK cytotoxicity (9, 49), thymocyte morphology or adhesion to bone marrow stroma (3), mitogen-induced blastogenesis in circulating (18) or splenic (65) lymphocytes, lymphocyte or neutrophil adhesion to endothelial cells (18), neutrophil chemotaxis and superoxide production (18), or macrophage migration and chemotaxis (19). Finally, calcein has been used consistently to label lymphocytes in vivo to study the effects of pharmaceuticals on lymphocyte trafficking among blood, spleen, lymph nodes, and Peyer's patches (14). Given the above observations, it appears highly likely that the differences found between the Flt and ground control groups were due to the spaceflight environment and not calcein.

In summary, the data show that, in the C57BL/6 mouse, a relatively short 12-day flight in space induced significant changes in parameters that can influence immune defense mechanisms, hematopoiesis, and other aspects of health. This first-time immune evaluation of the mouse opens the possibility of expanded research with larger numbers of animals so that statistically significant data are more likely to be obtained. Differences between the two control groups in several of the measurements emphasize the importance of simulating, as closely as possible, spaceflight housing and other environmental conditions when comparisons are made between animals in flight and ground controls. Because it is possible that immune and other aberrations could become progressively more severe, as time spent within the closed environment of a spacecraft increases, greater understanding of the underlying mechanisms is needed so that optimal means of prevention, diagnosis, and treatment can be developed.


    ACKNOWLEDGEMENTS

Many people contributed to the success of this flight. At Loma Linda University, Tamako A. Jones, Anna L. Smith, Radha Dutta-Roy, Melba L. Andres, Glen M. Miller, and Lora Benzatyan all provided valuable technical assistance. Highly significant contributions were also made by Mark Rupert (BioServe Space Technologies, University of Colorado), Dr. Beverly Girten (NASA Ames Research Center), and Katrien Morgan and Gail Clark (Johnson Space Center). In addition, several groups at the Kennedy Space Center were responsible for timely payload turnover, physical installation and removal of commercial biomedical testing module from the space shuttle, and on-site science support. We especially would like to thank Ramona Bober for coordinating all animal activities at hangar L.

Sources of support include NASA cooperative research agreements NCC9-149 and NCC8-242, National Heart, Lung, and Blood Institute Grant HL-64885, Chan Shun International Foundation, the Department of Radiation Medicine of the Loma Linda University Medical Center, and Amgen.


    FOOTNOTES

Address for reprint requests and other correspondence: D. S. Gridley, Chan Shun Pavilion, Rm. A-1010, 11175 Campus St., Loma Linda Univ., Loma Linda, CA 92354 (E-mail: dgridley{at}dominion.llumc.edu).

The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

First published December 27, 2002;10.1152/japplphysiol.01053.2002

Received 18 November 2002; accepted in final form 26 December 2002.


    REFERENCES
TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES

1.   Alfrey, CP, Rice L, Udden MM, and Driscoll TB. Neocytolysis: physiological down-regulator of red-cell mass. Lancet 349: 1389-1390, 1997[Web of Science][Medline].

2.   Alfrey, CP, Udden MM, Leach-Huntoon C, Driscoll T, and Pickett MH. Control of red blood cell mass in spaceflight. J Appl Physiol 81: 98-104, 1996[Abstract/Free Full Text].

3.   Barda-Saad, M, Zhang AS, Zipori D, and Rozenszajn LA. Adhesion of thymocytes to bone marrow stromal cells: regulation by bFGF and IFN-gamma. Stem Cells 15: 229-236, 1997[Medline].

4.   Begu, S, Devoisselle JM, and Mordon S. Noninvasive fluorescent study in situ and in real time of glucose effects on the pharmacokinetic of calcein. J Biomed Opt 7: 609-612, 2002[Web of Science][Medline].

5.   Bikle, DD, Harris J, Halloran BP, and Morey-Holton ER. Altered skeletal pattern of gene expression in response to spaceflight and hindlimb elevation. Am J Physiol Endocrinol Metab 267: E822-E827, 1994[Abstract/Free Full Text].

6.   Blakely, EA, and Fry RJ. Radiation protection in space. Radiat Environ Biophys 34: 129-131, 1995[Web of Science][Medline].

7.   Brock, JH, deSousa M, and Brock JH. Iron in Immunity, Cancer and Inflammation. Chichester, UK: Wiley, 1989, p. 35-53.

8.   Burkovskaya, TE, and Korolkov VI. Hemopoiesis in bone marrow of monkeys after spaceflight. J Gravit Physiol 7: S129-S134, 2000[Medline].

9.   Callewaert, DM, Radcliff G, Waite R, LeFevre J, and Poulik MD. Characterization of effector-target conjugates for cloned human natural killer and human lymphokine activated killer cells by flow cytometry. Cytometry 12: 666-676, 1991[Web of Science][Medline].

10.   Chapes, SK, Morrison DR, Guikema JA, Lewis ML, and Spooner BS. Cytokine secretion by immune cells in space. J Leukoc Biol 52: 104-110, 1992[Abstract].

11.   Chapes, SK, Morrison DR, Guikema JA, Lewis ML, and Spooner BS. Production and action of cytokines in space. Adv Space Res 14: 5-9, 1994[Web of Science][Medline].

12.   Chapes, SK, Simske SJ, Sonnenfeld G, Miller ES, and Zimmerman RJ. Effects of spaceflight and PEG-IL-2 on rat physiological and immunological responses. J Appl Physiol 86: 2065-2076, 1999[Abstract/Free Full Text].

13.   Chatenoud, L, Salomon B, and Bluestone JA. Suppressor T cells-they're back and critical for regulation of autoimmunity! Immunol Rev 182: 149-163, 2001[Web of Science][Medline].

14.   Chiba, K, Yanagawa Y, Masubuchi Y, Kataoka H, Kawaguchi T, Ohtsuki M, and Hoshino Y. FTY720, a novel immunosuppressant, induces sequestration of circulating mature lymphocytes by acceleration of lymphocyte homing in rats. I. FTY720 selectively decreases the number of circulating mature lymphocytes by acceleration of lymphocyte homing. J Immunol 160: 5037-5044, 1998[Abstract/Free Full Text].

15.   Cogoli, A. Hematological and immunological changes during space flight. Acta Astronaut 8: 995-1002, 1981[Web of Science][Medline].

16.   Congdon, CC, Allebban Z, Gibson LA, Kaplansky A, Strickland KM, Jago TL, Johnson DL, Lange RD, and Ichiki AT. Lymphatic tissue changes in rats flown on Spacelab Life Sciences-2. J Appl Physiol 81: 172-177, 1996[Abstract/Free Full Text].

17.   Davidson, JM, Aquino AM, Woodward SC, and Wilfinger WW. Sustained microgravity reduces intrinsic wound healing and growth factor responses in the rat. FASEB J 13: 325-329, 1999[Abstract/Free Full Text].

18.   De Clerck, LS, Bridts CH, Mertens AM, Moens MM, and Stevens WJ. Use of fluorescent dyes in the determination of adherence of human leucocytes to endothelial cells and the effect of fluorochromes on cellular function. J Immunol Methods 172: 115-124, 1994[Web of Science][Medline].

19.   Denholm, EM, and Stankus GP. Differential effects of two fluorescent probes on macrophage migration as assessed by manual and automated methods. Cytometry 19: 366-369, 1995[Web of Science][Medline].

20.   Dong, Q, and Shen XY. [Research proceeding on the effect of microgravity on erythropoiesis]. Space Med Med Eng (Beijing) 14: 298-302, 2001[Medline].

21.   Fehniger, TA, and Caligiuri MA. Ontogeny and expansion of human natural killer cells: clinical implications. Int Rev Immunol 20: 503-534, 2001[Medline].

22.   Gmunder, FK, and Cogoli A. Effect of spaceflight on lymphocyte function and immunity. In: Handbook of Physiology. Environmental Physiology. Bethesda, MD: Am. Physiol. Soc, 1996, vol. II, p. 799-813, sect. 4, chapt. 35.

23.   Gould, CL, Lyte M, Williams J, Mandel AD, and Sonnenfeld G. Inhibited interferon-g but normal interleukin-3 production from rats flown on the space shuttle. Aviat Space Environ Med 58: 983-986, 1987[Medline].

24.   Gridley, DS, Pecaut MJ, Dutta-Roy R, and Nelson GA. Dose and dose rate effects of whole-body proton irradiation on leukocyte populations and lymphoid organs. I. Immunol Lett 80: 55-66, 2002[Web of Science][Medline].

25.   Grigoriev, AI, and Egorov AD. Physiological aspects of adaptation of main human body systems during and after spaceflights. Adv Space Biol Med 2: 43-82, 1992[Medline].

26.   Grindeland, RE, Popova IA, Vasques M, and Arnaud SB. COSMOS 1887 mission overview: effects of microgravity on rat body and adrenal weights and plasma constituents. FASEB J 4: 105-109, 1990[Abstract].

27.   Grove, DS, Pishak SA, and Mastro AM. The effect of a 10-day space flight on the function, phenotype, and adhesion molecule expression of splenocytes and lymph node lymphocytes. Exp Cell Res 219: 102-109, 1995[Web of Science][Medline].

28.   Jahns, G, Meylor J, Fast T, Hawes N, and Zarow G. Rodent growth, behavior, and physiology resulting from flight on the Space Life Sciences-1 mission. In: Proceedings of the 43rd Congress of the International Astronautical Federation Washington, DC: International Astronautical Federation, 1992, p. 1-8.

29.   Johnson, PC. The erythropoietic effects of weightlessness. In: Current Concepts in Erythropoiesis, edited by Dunn CDR. New York: Wiley, 1983, p. 279-300.

30.   Kaplansky, AS, Durnova GN, Burkovskaya TE, and Vorotnikova EV. The effect of microgravity on bone fracture healing in rats flown on Cosmos-2044. Physiologist 34: S196-S199, 1991[Medline].

31.   Kim, DW, Andres ML, Li J, Kajioka EH, Miller GM, Seynhaeve AL, Ten Hagen TL, and Gridley DS. Liposome-encapsulated tumor necrosis factor-alpha enhances the effects of radiation against human colon tumor xenografts. J Interferon Cytokine Res 21: 885-897, 2001[Web of Science][Medline].

32.   Kirkpatrick, AW, Campbell MR, Novinkov OL, Goncharov IB, and Kovachevich, IV Blunt trauma and operative care in microgravity: a review of microgravity physiology and surgical investigations with implications for critical care and operative treatment in space. J Am Coll Surg 184: 441-453, 1997[Web of Science][Medline].

33.   Konstantinova, IV, Rykova MP, Lesnyak AT, and Antropova EA. Immune changes during long-duration missions. J Leukoc Biol 54: 189-201, 1993[Abstract].

34.   Lange, RD, Andrews RB, Gibson LA, Wright P, Dunn CD, and Jones JB. Hematologic parameters of astrorats flown on SL-3. Physiologist 28: S195-S196, 1985[Medline].

35.   Leach, CS, Dietlein LF, Pool SL, and Nicogossian AE. Medical considerations for extending human presence in space. Acta Astronaut 21: 659-666, 1990[Web of Science][Medline].

36.   Lesnyak, A, Sonnenfeld G, Avery L, Konstantinova I, Rykova M, Meshkov D, and Orlova T. Effect of SLS-2 spaceflight on immunologic parameters of rats. J Appl Physiol 81: 178-182, 1996[Abstract/Free Full Text].

37.   Levine, DS, and Greenleaf JE. Immunosuppression during spaceflight deconditioning. Aviat Space Environ Med 69: 172-177, 1998[Medline].

38.   Lindemann, S, Tolley ND, Dixon DA, McIntyre TM, Prescott SM, Zimmerman GA, and Weyrich AS. Activated platelets mediate inflammatory signaling by regulated interleukin 1beta synthesis. J Cell Biol 154: 485-490, 2001[Abstract/Free Full Text].

39.   Markin, A, Strogonova L, Balashov O, Polyakov V, and Tigner T. The dynamics of blood biochemical parameters in cosmonauts during long-term space flights. Acta Astronaut 42: 247-253, 1998[Web of Science][Medline].

40.   Mor, F, and Cohen IR. IL-2 rescues antigen-specific T cells from radiation or dexamethasone-induced apoptosis. Correlation with induction of Bcl-2. J Immunol 156: 515-522, 1996[Abstract].

41.   Moretta, A, Poggi A, Olive D, Bottino C, Fortis C, Pantaleo G, and Moretta L. Selection and characterization of T-cell variants lacking molecules involved in T-cell activation (T3 T-cell receptor, T44, and T11): analysis of the functional relationship among different pathways of activation. Proc Natl Acad Sci USA 84: 1654-1658, 1987[Abstract/Free Full Text].

42.   Nash, PV, and Mastro AM. Variable lymphocyte responses in rats after space flight. Exp Cell Res 202: 125-131, 1992[Web of Science][Medline].

43.   Pantaleo, G, Olive D, Poggi A, Pozzan T, Moretta L, and Moretta A. Antibody-induced modulation of the CD3/T cell receptor complex causes T cell refractoriness by inhibiting the early metabolic steps involved in T cell activation. J Exp Med 166: 619-624, 1987[Abstract/Free Full Text].

44.   Papiernik, M. Natural CD4+ CD25+ regulatory T cells. Their role in the control of superantigen responses. Immunol Rev 182: 180-189, 2001[Web of Science][Medline].

45.   Pecaut, MJ, Nelson GA, and Gridley DS. Dose and dose-rate effects of whole-body gamma -irradiation. I. Lymphocytes and lymphoid organs. In Vivo 15: 195-208, 2001[Web of Science][Medline].

45a.   Pecaut, MJ, Nelson GA, Peters LL, Kostenuik PJ, Bateman TA, Morony S, Stodieck LS, Lacey DL, Simske SJ, and Gridley DS. Effects of spaceflight on immunity in the C57BL/6 mouse. I. Immune population distributions. J Appl Physiol 94: 2085-2094, 2003[Abstract/Free Full Text].

46.   Pecaut, MJ, Simske SJ, and Fleshner M. Spaceflight induces changes in splenocyte subpopulations: effectiveness of ground-based models. Am J Physiol Regul Integr Comp Physiol 279: R2072-R2078, 2000[Abstract/Free Full Text].

47.   Poliakov, VV, Ivanova SM, Noskov VB, Labetskaia OI, Iarlykova IV, Karashtin VV, Legen'kov VI, Sarycheva TG, Shishkanova ZG, and Kozinets GI. Hematological investigations in conditions of long-term space flights. Aviakosm Ekolog Med 32: 9-18, 1998[Medline].

48.   Qi, XR, Maitani Y, and Nagai T. Rates of systemic degradation and reticuloendothelial system uptake of calcein in the dipalmitoylphosphatidylcholine liposomes with soybean-derived sterols in mice. Pharm Res 12: 49-52, 1995[Web of Science][Medline].

49.   Radcliff, G, Waite R, LeFevre J, Poulik MD, and Callewaert DM. Quantification of effector/target conjugation involving natural killer (NK) or lymphokine activated killer (LAK) cells by two-color flow cytometry. J Immunol Methods 139: 281-292, 1991[Web of Science][Medline].

50.   Rice, L, Alfrey CP, Driscoll T, Whitley CE, Hachey DL, and Suki W. Neocytolysis contributes to the anemia of renal disease. Am J Kidney Dis 33: 59-62, 1999[Web of Science][Medline].

51.   Robertson, D, Krantz SB, and Biaggioni I. The anemia of microgravity and recumbency: role of sympathetic neural control of erythropoietin production. Acta Astronaut 33: 137-141, 1994[Web of Science][Medline].

52.   Schneider, V, Oganov V, LeBlanc A, Rakmonov A, Taggart L, Bakulin A, Huntoon C, Grigoriev A, and Varonin L. Bone and body mass changes during space flight. Acta Astronaut 36: 463-466, 1995[Web of Science][Medline].

53.   Setlow, R, Dicello JF, Fry RJM, Little JB, Preston RJ, Smathers JB, and Ullrich RL. Radiation Hazards to Crews of Interplanetary Missions: Biological Issues and Research Strategies. Washington, DC: Space Studies Board, National Research Council, and National Academy Press, 1996, p. 13-34.

54.   Seyle, HA. The Stress of Life. New York: McGraw-Hill, 1976.

55.   Smith, SM, Davis-Street JE, Rice BL, Nillen JL, Gillman PL, and Block G. Nutritional status assessment in semiclosed environments: ground-based and space flight studies in humans. J Nutr 131: 2053-2061, 2001[Abstract/Free Full Text].

56.   Sonnenfeld, G. Effects of space flight on surface marker expression. Adv Space Res 24: 815-820, 1999[Web of Science][Medline].

57.   Sonnenfeld, G, Mandel AD, Konstantinova IV, Berry WD, Taylor GR, Lesnyak AT, Fuchs BB, and Rakhmilevich AL. Spaceflight alters immune cell function and distribution. J Appl Physiol 73: 191S-195S, 1992[Abstract].

58.   Sonnenfeld, G, and Miller ES. The role of cytokines in immune changes induced by spaceflight. J Leukoc Biol 54: 253-258, 1993[Abstract].

59.   Sonnenfeld, G, Schaffar L, Schmitt DA, Peres C, and Miller ES. The Rhesus monkey as a model for testing the immunological effects of space flight. Adv Space Res 14: 395-397, 1994[Medline].

60.   Stauber, WT, Fritz VK, Burkovskaya TE, and Ilyina-Kakueva EI. Effect of spaceflight on the extracellular matrix of skeletal muscle after a crush injury. J Appl Physiol 73: 74S-81S, 1992[Abstract].

61.   Sule, NS, Nerurkar RP, and Kamath S. Interleukin-2 as a therapeutic agent. J Assoc Physicians India 49: 897-900, 2001[Medline].

62.   Todd, P, Pecaut MJ, and Fleshner M. Combined effects of space flight factors and radiation on humans. Mutat Res 430: 211-219, 1999[Web of Science][Medline].

63.   Watenpaugh, DE. Fluid volume control during short-term space flight and implications for human performance. J Exp Biol 204: 3209-3215, 2001[Medline].

64.   Weinberg, ED. Human lactoferrin: a novel therapeutic with broad spectrum potential. J Pharm Pharmacol 53: 1303-1310, 2001[Web of Science][Medline].

65.   Weston, SA, and Parish CR. New fluorescent dyes for lymphocyte migration studies. Analysis by flow cytometry and fluorescence microscopy. J Immunol Methods 133: 87-97, 1990[Web of Science][Medline].

66.   Wronski, TJ, Li M, Shen Y, Miller SC, Bowman BM, Kostenuik P, and Halloran BP. Lack of effect of spaceflight on bone mass and bone formation in group-housed rats. J Appl Physiol 85: 279-285, 1998[Abstract/Free Full Text].

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