Speg interactions that regulate the stability of excitation-contraction coupling protein complexes in triads and dyads.

Here we show that striated muscle preferentially expressed protein kinase α (Spegα) maintains cardiac function in hearts with Spegß deficiency. Speg is required for stability of excitation-contraction coupling (ECC) complexes and interacts with esterase D (Esd), Cardiomyopathy-Associated Protein 5 (Cmya5), and Fibronectin Type III and SPRY Domain Containing 2 (Fsd2) in cardiac and skeletal muscle. Mice with a sequence encoding a V5/HA tag inserted into the first exon of the Speg gene (HA-Speg mice) display a >90% decrease in Spegß but Spegα is expressed at ~50% of normal levels. Mice deficient in both Spegα and Speg ß (Speg KO mice) develop a severe dilated cardiomyopathy and muscle weakness and atrophy, but HA-Speg mice display mild muscle weakness with no cardiac involvement. Spegα in HA-Speg mice suppresses Ca2+ leak, proteolytic cleavage of Jph2, and disruption of transverse tubules. Despite it's low levels, HA-Spegß immunoprecipitation identified Esd, Cmya5 and Fsd2 as Spegß binding partners that localize to triads and dyads to stabilize ECC complexes. This study suggests that Spegα and Spegß display functional redundancy, identifies Esd, Cmya5 and Fsd2 as components of both cardiac dyads and skeletal muscle triads and lays the groundwork for the identification of new therapeutic targets for centronuclear myopathy.

Salutary effects of moderate but not high intensity aerobic exercise training on the frequency of peripheral T-cells associated with immunosenescence in older women at high risk of breast cancer: a randomized controlled trial.

BACKGROUND: Immunosenescence is described as age-associated changes within the immune system that are responsible for decreased immunity and increased cancer risk. Physically active individuals have fewer 'senescent' and more naïve T-cells compared to their sedentary counterparts, but it is not known if exercise training can rejuvenate 'older looking' T-cell profiles. We determined the effects of 12-weeks supervised exercise training on the frequency of T-cell subtypes in peripheral blood and their relationships with circulating levels of the muscle-derived cytokines (i.e. 'myokines') IL-6, IL-7, IL-15 and osteonectin in older women at high risk of breast cancer. The intervention involved 3 sessions/week of either high intensity interval exercise (HIIT) or moderate intensity continuous exercise (MICT) and were compared to an untrained control (UC) group. RESULTS: HIIT decreased total granulocytes, CD4+ T-cells, CD4+ naïve T-cells, CD4+ recent thymic emigrants (RTE) and the CD4:CD8 ratio after training, whereas MICT increased total lymphocytes and CD8 effector memory (EM) T-cells. The change in total T-cells, CD4+ naïve T-cells, CD4+ central memory (CM) T-cells and CD4+ RTE was elevated after MICT compared to HIIT. Changes in [Formula: see text] after training, regardless of exercise prescription, was inversely related to the change in highly differentiated CD8+ EMRA T-cells and positively related to changes in ß2-adrenergic receptor (ß2-AR) expression on CM CD4+ and CM CD8+ T-cells. Plasma myokine levels did not change significantly among the groups after training, but individual changes in IL-7 were positively related to changes in the number of ß2-AR expressing CD4 naïve T cells in both exercise groups but not controls. Further, CD4 T-cells and CD4 naive T-cells were negatively related to changes in IL-6 and osteonectin after HIIT but not MICT, whereas CD8 EMRA T-cells were inversely related to changes in IL-15 after MICT but not HIIT. CONCLUSIONS: Aerobic exercise training alters the frequency of peripheral T-cells associated with immunosenescence in middle aged/older women at high risk of breast cancer, with HIIT (pro-senescent) and MICT (anti-senescent) evoking divergent effects. Identifying the underlying mechanisms and establishing whether exercise-induced changes in peripheral T-cell numbers can alter the risk of developing breast cancer warrants investigation.

FcεRIγ-negative NK cells persist in vivo and enhance efficacy of therapeutic monoclonal antibodies in multiple myeloma.

Monoclonal antibodies (mAbs) are a central component of therapy for hematologic malignancies. Widely used mAb agents in multiple myeloma (MM) include daratumumab and elotuzumab. However, not all patients respond to these agents, and resistance is a significant clinical issue. A recently discovered subset of human natural killer (NK) cells lacking expression of FcεRIγ (g-NK cells) was found to have a multifold increase in antibody-dependent effector functions after CD16 crosslinking. In this study, we tested the capacity of g-NK cells to enhance the efficacy of therapeutic mAbs against MM. In vitro, we found that g-NK cells have strikingly superior anti-myeloma cytotoxicity compared with conventional NK (cNK) cells when combined with daratumumab or elotuzumab (∼sixfold; P < .001). In addition, g-NK cells naturally expressed minimal surface CD38 and SLAMF7, which reduced the incidence of therapeutic fratricide. In tumor-naïve murine models, the persistence of g-NK cells in blood and spleen was >10 times higher than that of cNK cells over 31 days (P < .001). In vivo efficacy studies showed that the combination of daratumumab and g-NK cells led to a >99.9% tumor reduction (by flow cytometry analysis) compared with the combination of daratumumab and cNK cells (P < .001). Moreover, treatment with daratumumab and g-NK cells led to complete elimination of myeloma burden in 5 of 7 mice. Collectively, these results underscore the unique ability of g-NK cells to potentiate the activity of therapeutic mAbs and overcome limitations of current off-the-shelf NK cell therapies without the need for cellular irradiation or genetic engineering.

The effects of normoxic endurance exercise on erythropoietin (EPO) production and the impact of selective ß1 and non-selective ß1 + ß2 adrenergic receptor blockade.

PURPOSE: Habitual endurance exercise results in increased erythropoiesis, which is primarily controlled by erythropoietin (EPO), yet studies demonstrating upregulation of EPO via a single bout of endurance exercise have been equivocal. This study compares the acute EPO response to 30 min of high versus 90 min of moderate-intensity endurance exercise and whether that response can be upregulated via selective adrenergic receptor blockade. METHODS: Using a counterbalanced, cross-over design, fifteen participants (age 28 ± 8) completed two bouts of running (30-min, high intensity vs 90-min, moderate intensity) matched for overall training stress. A separate cohort of fourteen participants (age 31 ± 6) completed three bouts of 30-min high-intensity cycling after ingesting the preferential ß1-adrenergic receptor (AR) antagonist bisoprolol, the non-preferential ß1 + ß2 antagonist nadolol or placebo. Venous blood was collected before, during, and after exercise, and serum EPO levels were determined by ELISA. RESULTS: No detectable EPO response was observed during or after high intensity running, however, in the moderate-intensity trial EPO was significantly elevated at both during-exercise timepoints (+ 6.8% ± 2.3% at 15 min and + 8.7% ± 2.2% at 60 min). No significant change in EPO was observed post-cycling or between the trials involving ßAR blockade. CONCLUSION: Neither training mode (running or cycling), nor beta-blockade significantly influenced the EPO response to 30 min of high-intensity exercise, however, 90 min of moderate-intensity running elevated EPO during exercise, returning to baseline immediately post-exercise. Identifying the optimal mode, duration and intensity required to evoke an EPO response to exercise may help tailor exercise prescriptions designed to maximize EPO response for both performance and clinical applications.

The impact of high-intensity interval exercise training on NK-cell function and circulating myokines for breast cancer prevention among women at high risk for breast cancer.

PURPOSE: Preclinical evidence suggests that natural killer cell (NK-cell) function and myokines facilitate the protective effects of exercise for breast cancer prevention. Since higher-intensity exercise acutely promotes greater mobilization and larger changes in NK-cell cytotoxicity than lower-intensity, high-intensity interval training (HIIT) might offer increased immune protection compared to moderate-intensity continuous-training (MICT). This study compared a 12-week HIIT program to a 12-week MICT program and usual care on changes in resting NK-cell function and circulating myokines among women at high risk for breast cancer. METHODS: Thirty-three women were randomized to HIIT, MICT, or usual care, for a supervised exercise intervention. Blood was collected at baseline and end-of-study. The cytotoxic activity of CD3-/CD56+ NK-cells against the K562 target cell line in vitro was determined by flow cytometry. Circulating myokines (IL-15, IL-6, irisin, OSM, osteonectin, IL-7) were assessed with luminex multiplex assays and ELISA. One-way ANOVA and paired sample t-tests assessed between- and within-group differences, respectively. Pearson correlation coefficients determined relationships between baseline fitness and change variables. RESULTS: Significant differences were not observed between groups for change in NK-cell function or circulating myokines (p > 0.05). Significant correlations were only observed for baseline peak aerobic capacity (ml/kg/min) and change in NK-cell-specific lysis (r = - 0.43, p = 0.02) and hemacytotoxicity for the total sample (r = - 0.46, p = 0.01). CONCLUSION: Our findings suggest that exercise intensity may not significantly impact change in resting NK-cell function and circulating myokines among women at high risk for breast cancer. Structured exercise training may have a larger impact on NK-cell function in those with lower levels of cardiorespiratory fitness. CLINICAL TRIAL REGISTRATION: NCT02923401; Registered on October 4, 2016.

MyoSight-semi-automated image analysis of skeletal muscle cross sections.

BACKGROUND: Manual analysis of cross-sectional area, fiber-type distribution, and total and centralized nuclei in skeletal muscle cross sections is tedious and time consuming, necessitating an accurate, automated method of analysis. While several excellent programs are available, our analyses of skeletal muscle disease models suggest the need for additional features and flexibility to adequately describe disease pathology. We introduce a new semi-automated analysis program, MyoSight, which is designed to facilitate image analysis of skeletal muscle cross sections and provide additional flexibility in the analyses. RESULTS: We describe staining and imaging methods that generate high-quality images of immunofluorescent-labelled cross sections from mouse skeletal muscle. Using these methods, we can analyze up to 5 different fluorophores in a single image, allowing simultaneous analyses of perinuclei, central nuclei, fiber size, and fiber-type distribution. MyoSight displays high reproducibility among users, and the data generated are in close agreement with data obtained from manual analyses of cross-sectional area (CSA), fiber number, fiber-type distribution, and number and localization of myonuclei. Furthermore, MyoSight clearly delineates changes in these parameters in muscle sections from a mouse model of Duchenne muscular dystrophy (mdx). CONCLUSIONS: MyoSight is a new program based on an algorithm that can be optimized by the user to obtain highly accurate fiber size, fiber-type identification, and perinuclei and central nuclei per fiber measurements. MyoSight combines features available separately in other programs, is user friendly, and provides visual outputs that allow the user to confirm the accuracy of the analyses and correct any inaccuracies. We present MyoSight as a new program to facilitate the analyses of fiber type and CSA changes arising from injury, disease, exercise, and therapeutic interventions.

Adaptive thermogenesis enhances the life-threatening response to heat in mice with an Ryr1 mutation.

Mutations in the skeletal muscle Ca2+ release channel, the type 1 ryanodine receptor (RYR1), cause malignant hyperthermia susceptibility (MHS) and a life-threatening sensitivity to heat, which is most severe in children. Mice with an MHS-associated mutation in Ryr1 (Y524S, YS) display lethal muscle contractures in response to heat. Here we show that the heat response in the YS mice is exacerbated by brown fat adaptive thermogenesis. In addition, the YS mice have more brown adipose tissue thermogenic capacity than their littermate controls. Blood lactate levels are elevated in both heat-sensitive MHS patients with RYR1 mutations and YS mice due to Ca2+ driven increases in muscle metabolism. Lactate increases brown adipogenesis in both mouse and human brown preadipocytes. This study suggests that simple lifestyle modifications such as avoiding extreme temperatures and maintaining thermoneutrality could decrease the risk of life-threatening responses to heat and exercise in individuals with RYR1 pathogenic variants.

The effects of ß1 and ß1+2 adrenergic receptor blockade on the exercise-induced mobilization and ex vivo expansion of virus-specific T cells: implications for cellular therapy and the anti-viral immune effects of exercise.

The adoptive transfer of donor-derived virus-specific T cells (VSTs) is an effective treatment for infections following allogeneic hematopoietic cell transplantation. Acute exercise mobilizes effector lymphocytes and VSTs to the circulation and augments the ex vivo manufacture of VSTs. This study determined if ß2 adrenergic receptor (AR) signaling precipitated the VST response to acute exercise. Healthy participants (n = 12) completed 30 min of steady-state cycling exercise after ingesting a placebo, a ß1 + 2 AR antagonist (nadolol) or a ß1 AR antagonist (bisoprolol). Circulating VSTs to cytomegalovirus (CMV), Epstein-Barr virus (EBV), and adenovirus (AdV) antigens were enumerated before and after exercise, and peripheral blood mononuclear cells were cultured with viral peptides for 8 days to expand multi-VSTs. Compared with placebo, nadolol blunted the exercise-induced mobilization of CMV-VSTs (Δ VSTs/100,000 CD3+ T cells = 93 ± 104 vs. 22 ± 91 for placebo and nadolol, respectively; p = 0.036), while bisoprolol did not, despite both drugs evoking similar reductions in exercising heart rate and blood pressure. Circulating AdV and EBV VSTs (VSTs/mL blood) only increased after exercise with placebo. Although not significant, nadolol partially mitigated exercise-induced increases in multi-VST expansion, particularly in participants that demonstrated an exercise-induced increase in VST expansion. We conclude that exercise-induced enhancements in VST mobilization and expansion are at least partially ß2 AR mediated, thus highlighting a role for the ß2 AR in targeted therapy for the augmentation of VST immune cell therapeutics in the allogeneic adoptive transfer setting. Moreover, long-term regular exercise may provide additional viral protection in the host through frequent ß2 AR-dependent mobilization and redistribution of VSTs cumulated with each bout of exercise.

Exercise as a countermeasure for latent viral reactivation during long duration space flight.

Latent viral reactivation is a commonly reported manifestation of immune system dysregulation during spaceflight. As physical fitness and exercise training have been shown to benefit multiple arms of the immune system, we hypothesized that higher levels of preflight physical fitness and/or maintaining fitness during a mission would protect astronauts from latent viral reactivation. Standardized tests of maximal strength, muscular endurance, flexibility, and cardiorespiratory fitness (CRF) were performed in 22 international space station (ISS) crewmembers before and after a ~6-month mission. Reactivation of cytomegalovirus (CMV), Epstein-Barr virus (EBV), and varicella zoster virus (VZV) was determined in crewmembers and ground-based controls before, during, and after spaceflight. Crewmembers with higher CRF before spaceflight had a 29% reduced risk of latent viral reactivation compared to crew with lower CRF. Higher preflight upper body muscular endurance was associated with a 39% reduced risk of viral reactivation, a longer time to viral reactivation, and lower peak viral DNA concentrations, particularly for EBV and VZV. Latent viral reactivation rates were highest in crew with lower preflight CRF and higher levels of CRF deconditioning on return to Earth. We conclude that physical fitness may protect astronauts from latent viral reactivation during long duration spaceflight missions.

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

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 whether salivary antimicrobial proteins, which act as a first line of innate immune defense against multiple pathogens, are altered in response to long-duration (>6 mo) missions. We collected 7 consecutive days of whole and sublingual saliva samples from eight International Space Station (ISS) crewmembers and seven ground-based control subjects at nine mission time points, ~180 and ~60 days before launch (L-180/L-60), on orbit at flight days ~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 secretory (s)IgA, lysozyme, LL-37, and the cortisol-to-dehydroepiandrosterone 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 with the "veteran" crew who had previously flown. Latent herpesvirus reactivation was distinct to the ~6-mo mission crewmembers who performed extravehicular activity ("spacewalks"). Crewmembers who shed at least one latent virus had higher cortisol levels than 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.NEW & NOTEWORTHY Spaceflight-associated immune dysregulation may jeopardize future exploration-class missions. Salivary antimicrobial proteins act as a first line of innate immune defense. We report here that several of these proteins are elevated in astronauts during an International Space Station mission, particularly in those embarking on their first space voyage. Astronauts who shed a latent herpesvirus also had higher concentrations of salivary cortisol compared with those who did not shed. Stress-relieving countermeasures are needed to preserve immunity and prevent viral reactivation during prolonged voyages into deep space.

NK cell function is impaired during long-duration spaceflight.

Maintaining astronaut health during space travel is paramount for further human exploration of the solar system beyond Earth's orbit. Of concern are potential dysregulations in immunity, which could increase the likelihood of cancer and latent viral reactivation. Natural killer (NK) cells are critical effectors of the innate immune system, and their function and phenotype are important to immunosurveillance of nascent tumors and latent viral infections. We compared changes in NK cell phenotype and function in eight crew members who completed an ~6-mo mission to the International Space Station (ISS) with healthy controls who remained on Earth. Assessments were made before (180 and 60 days before launch), during [flight day + 90 days (FD+90) and 1 day before return (R-1)], and after the mission (at R+0, R+18, R+33, and R+66). These samples, plus an additional in-flight sample (FD+180), were collected from a crew member who spent 340 days (~1 yr) on the ISS. NK cell cytotoxic activity (NKCA) against K562 leukemia targets in vitro was reduced by ~50% at FD+90 in ISS crew but not controls. This decrease was more pronounced in "rookie" compared with "veteran" crew members. The ~1-yr mission crew member did not show declines in NKCA against K562 until late in the mission (R-1 and R+0). NK cell numbers, expression of activating and inhibitory receptors, target cell binding, and expression and degranulation of perforin and granzyme B were unaltered with spaceflight. Similarly, when we exposed an immortalized NK cell line (NK-92) to sera collected at different mission time points (before, during, and after flight), there was no effect on NKCA. This is the first study to report impaired NK cell function during long-duration space travel. Countermeasures may be needed to mitigate immune system impairment in exploration class mission crew during long-duration spaceflight missions. NEW & NOTEWORTHY Immune system impairment may inhibit future human space exploration missions to Mars. Natural killer (NK) cells are key components of immunity and vital for tumor surveillance and the prevention of latent virus reactivation. We report that NK cell function is impaired in astronauts during an ~6-mo orbital space mission compared with preflight levels and ground-based controls. Declines in NK cell function were more marked in first-time "rookie" fliers. Countermeasures are needed to preserve NK cell-mediated immunity during spaceflight.

Systemic ß-Adrenergic Receptor Activation Augments the ex vivo Expansion and Anti-Tumor Activity of Vγ9Vδ2 T-Cells.

TCR-gamma delta (γδ) T-cells are considered important players in the graft-vs.-tumor effect following allogeneic hematopoietic cell transplantation (alloHCT) and have emerged as candidates for adoptive transfer immunotherapy in the treatment of both solid and hematological tumors. Systemic ß-adrenergic receptor (ß-AR) activation has been shown to mobilize TCR-γδ T-cells to the blood, potentially serving as an adjuvant for alloHCT and TCR-γδ T-cell therapy. We investigated if systemic ß-AR activation, using acute dynamic exercise as an experimental model, can increase the mobilization, ex vivo expansion, and anti-tumor activity of TCR-γδ T-cells isolated from the blood of healthy humans. We also sought to investigate the ß-AR subtypes involved, by administering a preferential ß1-AR antagonist (bisoprolol) and a non-preferential ß1 + ß2-AR antagonist (nadolol) prior to exercise as part of a randomized placebo controlled cross-over experiment. We found that exercise mobilized TCR-γδ cells to blood and augmented their ex vivo expansion by ~182% compared to resting blood when stimulated with IL-2 and ZOL for 14-days. Exercise also increased the proportion of CD56+, NKG2D+/CD62L-, CD158a/b/e+ and NKG2A- cells among the expanded TCR-γδ cells, and increased their cytotoxic activity against several tumor target cells (K562, U266, 221.AEH) in vitro by 40-60%. Blocking NKG2D on TCR-γδ cells in vitro eliminated the augmented cytotoxic effects of exercise against U266 target cells. Furthermore, administering a ß1 + ß2-AR (nadolol), but not a ß1-AR (bisoprolol) antagonist prior to exercise abrogated the exercise-induced enhancement in TCR-γδ T-cell mobilization and ex vivo expansion. Furthermore, nadolol completely abrogated while bisoprolol partially inhibited the exercise-induced increase in the cytotoxic activity of the expanded TCR-γδ T-cells. We conclude that acute systemic ß-AR activation in healthy donors markedly augments the mobilization, ex vivo expansion, and anti-tumor activity of TCR-γδ T-cells and that some of these effects are due to ß2-AR signaling and phenotypic shifts that promote a dominant activating signal via NKG2D. These findings highlight ß-ARs as potential targets to favorably alter the composition of allogeneic peripheral blood stem cell grafts and improve the potency of TCR-γδ T-cell immune cell therapeutics.

ß2-Adrenergic receptor signaling mediates the preferential mobilization of differentiated subsets of CD8+ T-cells, NK-cells and non-classical monocytes in response to acute exercise in humans.

Acute exercise preferentially mobilizes cytotoxic T-cells, NK-cells and non-classical monocytes to the bloodstream under the influence of hemodynamic forces and/or ß2-adrenergic receptor (ß2-AR) signaling. However, the relative contribution of these mechanisms to the redeployment of the most exercise-responsive cell types is largely unknown. We determined the lymphocyte and monocyte subtypes mobilized to blood during exercise via ß2-AR signaling whilst controlling for ß1-AR mediated reductions in hemodynamic forces. In a randomized, double blind, complete cross-over design, 14 healthy cyclists exercised for 30-minutes at +10% of blood lactate threshold after ingesting: (1) a placebo, (2) a ß1-preferential antagonist (10 mg bisoprolol), or (2) a non-preferential ß1 + ß2-antagonist (80 mg nadolol) across three trials separated by >7-days. Bisoprolol was administered to reduce hemodynamic forces (heart rate and blood pressure) during exercise to levels comparable with nadolol but without blocking ß2-ARs. The mobilization of total NK-cells, terminally differentiated (CD57+) NK-cells, central memory, effector memory and CD45RA+ effector memory CD8+ T-cells; non-classical monocytes; and γδ T-cells were significantly blunted or abrogated under nadolol compared to both bisoprolol and placebo, indicating that the exercise-induced mobilization of these cell types to the blood is largely influenced by ß2-AR signaling. Nadolol failed to inhibit the mobilization of classical monocytes, CD4+ T-cells (and their subsets) or naïve CD8+ T-cells, indicating that these cell types are mobilized with exercise independently of the ß2-AR. We conclude that the preferential mobilization of NK-cells, non-classical monocytes and differentiated subsets of CD8+ T-cells with exercise is largely dependent on catecholamine signaling through the ß2-AR. These findings provide mechanistic insights by which distinct lymphocyte and monocyte subtypes are preferentially mobilized to protect the host from anticipated injury or infection in response to an acute stress response.

A single exercise bout augments adenovirus-specific T-cell mobilization and function.

Adoptive transfer of virus-specific T-cells (VSTs) effectively treats viral infections following allogeneic hematopoietic stem cell transplantation (alloHSCT), but logistical difficulties have limited widespread availability of VSTs as a post-transplant therapeutic. A single exercise bout mobilizes VSTs specific for latent herpesviruses (i.e. CMV and EBV) to peripheral blood and augments their ex vivo expansion. We investigated whether exercise exerts similar effects on T-cells specific for a NON-latent virus such as adenovirus, which is a major contributor to infection-related morbidity and mortality after alloHSCT. Thirty minutes of cycling exercise increased circulating adenovirus-specific T-cells 2.0-fold and augmented their ex vivo expansion by ~33% compared to rest without altering antigen and MHC-specific autologous target cell killing capabilities. We conclude that exercise is a simple and economical adjuvant to boost the isolation and manufacture of therapeutic VSTs specific to latent and non-latent viruses from healthy donors.

Vigorous exercise mobilizes CD34+ hematopoietic stem cells to peripheral blood via the ß2-adrenergic receptor.

Acute dynamic exercise mobilizes CD34+ hematopoietic stem cells (HSCs) to the bloodstream, potentially serving as an economical adjuvant to boost the collection of HSCs from stem cell transplant donors. The mechanisms responsible for HSC mobilization with exercise are unknown but are likely due to hemodynamic perturbations, endogenous granulocyte-colony stimulating factor (G-CSF), and/or ß2-adrenergic receptor (ß2-AR) signaling. We characterized the temporal response of HSC mobilization and plasma G-CSF following exercise, and determined the impact of in vivo ß-AR blockade on the exercise-induced mobilization of HSCs. Healthy runners (n = 15) completed, in balanced order, two single bouts of steady state treadmill running exercise at moderate (lasting 90-min) or vigorous (lasting 30-min) intensity. A separate cohort of healthy cyclists (n = 12) completed three 30-min cycling ergometer trials at vigorous intensity after ingesting: (i) 10 mg bisoprolol (ß1-AR antagonist); (ii) 80 mg nadolol (ß1 + ß2-AR antagonist); or (iii) placebo, in balanced order with a double-blind design. Blood samples collected before, during (runners only), immediately after, and at several points during exercise recovery were used to determine circulating G-CSF levels (runners only) and enumerate CD34+ HSCs by flow cytometry (runners and cyclists). Steady state vigorous but not moderate intensity exercise mobilized HSCs, increasing the total blood CD34+ count by ∼4.15 ±â€¯1.62 Δcells/µl (+202 ±â€¯92%) compared to resting conditions. Plasma G-CSF increased in response to moderate but not vigorous exercise. Relative to placebo, nadolol and bisoprolol lowered exercising heart rate and blood pressure to comparable levels. The number of CD34+ HSCs increased with exercise after the placebo and bisoprolol trials, but not the nadolol trial, suggesting ß2-AR signaling mediated the mobilization of CD34+ cells [Placebo: 2.10 ±â€¯1.16 (207 ±â€¯69.2%), Bisoprolol 1.66 ±â€¯0.79 (+163 ±â€¯29%), Nadolol: 0.68 ±â€¯0.54 (+143 ±â€¯36%) Δcells/µL]. We conclude that the mobilization of CD34+ HSCs with exercise is not dependent on circulating G-CSF and is likely due to the combined actions of ß2-AR signaling and hemodynamic shear stress.

Moderate-intensity, premeal cycling blunts postprandial increases in monocyte cell surface CD18 and CD11a and endothelial microparticles following a high-fat meal in young adults.

High-fat meals promote transient increases in proatherogenic factors, implicating the postprandial state in cardiovascular disease (CVD) progression. Although low-grade inflammation is associated with CVD, little research has assessed postprandial inflammation. Because of its anti-inflammatory properties, premeal exercise may counteract postprandial inflammation. The purpose of this study was to determine postprandial alterations in monocytes and circulating markers of endothelial stress and inflammation following a high-fat meal in young adults with or without premeal cycle exercise. Each subject completed two trials and was randomized to rest or cycle at a moderate intensity prior to eating a high-fat meal. Flow cytometry was used to assess monocyte cell surface receptor expression and concentration of endothelial microparticles (EMP). Plasma cytokines were assessed using Luminex MagPix. Statistical analysis was completed using separate linear mixed models analyses with first-order autoregressive (AR(1)) heterogeneous covariance structure. Significance was set at P ≤ 0.05. Percentage increases in classic monocyte CD11a and CD18 were greater overall in the postprandial period in the meal-only condition compared with the meal + exercise condition (P < 0.05). EMP concentration was 47% greater 3 h after the meal compared with premeal values in the meal-only condition (P < 0.05); no significant increase was observed in the meal + exercise condition. Premeal cycling blunted postprandial increases in EMP and CD11a and CD18. Acute, moderate-intensity exercise may help counteract possibly deleterious postprandial monocyte and endothelial cell activation.

Effects of exercise on weight loss and monocytes in obese mice.

Obesity causes innate immune dysfunction, contributing to increased disease risk. Weight loss from a combination of caloric restriction and exercise is the most effective treatment of obesity. We compared forced and voluntary exercise as weight-loss treatments in diet-induced obese (DIO) mice and assessed the effects of weight loss on monocyte concentration and cell-surface expression of Toll-like receptor (TLR) 2, TLR4, CD80, and CD86. DIO CD1 male mice were allocated randomly to 1 of 3 groups (n = 6 per group): voluntary wheel running (VEX); forced treadmill running (FEX); and sedentary (S). A fourth (control) group (CN, n = 6) of nonDIO mice was included also. During the 8-wk weight-loss treatment, all 4 groups consumed a low-fat (10% fat) diet. Nonlethal saphenous vein blood samples collected at baseline, week 4, and week 8 were analyzed by flow cytometry to assess monocyte concentration and functional receptor expression. The VEX and FEX groups lost significantly more body weight (36% and 27%, respectively) over the 8 wk of treatment than did other groups. VEX mice ran 4.4 times more than did FEX animals. VEX mice had higher monocyte concentrations (48% and 58%, respectively) than did the CN and FEX groups. Compared with baseline, week 8 cell-surface expression of TLR2 (22%), TLR4 (33%), and CD86 (18%) was increased in VEX mice. At week 4, CD80 expression was 42% greater for VEX than S mice. The present study confirms that short-term exercise and low-fat diet consumption cause significant weight loss and altered immune profiles.