Sleep disruption and its effect on lymphocyte redeployment following an acute bout of exercise

Influence of sleep on physiological systems in atherosclerosis

Sleep is a fundamental requirement of life and is integral to health. Deviation from optimal sleep associates with numerous diseases including those of the cardiovascular system. Studies, spanning animal models to humans, show that insufficient, disrupted or inconsistent sleep contribute to poor cardiovascular health by disrupting body systems. Fundamental experiments have begun to uncover the molecular and cellular links between sleep and heart health while large-scale human studies have associated sleep with cardiovascular outcomes in diverse populations. Here, we review preclinical and clinical findings that demonstrate how sleep influences the autonomic nervous, metabolic and immune systems to affect atherosclerotic cardiovascular disease.

Sleep restoration by optogenetic targeting of GABAergic neurons reprograms microglia and ameliorates pathological phenotypes in an Alzheimer's disease model

BACKGROUND

Alzheimer's disease (AD) patients exhibit memory disruptions and profound sleep disturbances, including disruption of deep non-rapid eye movement (NREM) sleep. Slow-wave activity (SWA) is a major restorative feature of NREM sleep and is important for memory consolidation.

METHODS

We generated a mouse model where GABAergic interneurons could be targeted in the presence of APPswe/PS1dE9 (APP) amyloidosis, APP-GAD-Cre mice. An electroencephalography (EEG) / electromyography (EMG) telemetry system was used to monitor sleep disruptions in these animals. Optogenetic stimulation of GABAergic interneurons in the anterior cortex targeted with channelrhodopsin-2 (ChR2) allowed us to examine the role GABAergic interneurons play in sleep deficits. We also examined the effect of optogenetic stimulation on amyloid plaques, neuronal calcium as well as sleep-dependent memory consolidation. In addition, microglial morphological features and functions were assessed using confocal microscopy and flow cytometry. Finally, we performed sleep deprivation during optogenetic stimulation to investigate whether sleep restoration was necessary to slow AD progression.

RESULTS

APP-GAD-Cre mice exhibited impairments in sleep architecture including decreased time spent in NREM sleep, decreased delta power, and increased sleep fragmentation compared to nontransgenic (NTG) NTG-GAD-Cre mice. Optogenetic stimulation of cortical GABAergic interneurons increased SWA and rescued sleep impairments in APP-GAD-Cre animals. Furthermore, it slowed AD progression by reducing amyloid deposition, normalizing neuronal calcium homeostasis, and improving memory function. These changes were accompanied by increased numbers and a morphological transformation of microglia, elevated phagocytic marker expression, and enhanced amyloid β (Aβ) phagocytic activity of microglia. Sleep was necessary for amelioration of pathophysiological phenotypes in APP-GAD-Cre mice.

CONCLUSIONS

In summary, our study shows that optogenetic targeting of GABAergic interneurons rescues sleep, which then ameliorates neuropathological as well as behavioral deficits by increasing clearance of Aβ by microglia in an AD mouse model.

Review on the Effect of Exercise Training on Immune Function

Exercise training is not only a necessary means to improve the level of exercise, but also an important means to improve the body's immunity. Different time, intensity, items, and forms of exercise training have different effects on the body's immune function. As a double-edged sword to improve the body's immune function, exercise training is a different reaction mechanism of different immune cells after exercise training. This paper combined with foreign scholars' studies on the immune function of the body of literature from different exercise intensity, different time, different sports, different movement forms, and different external environment such as angle of view for athletes body's immune cells and humoral immunity summarized the various indexes such as combing, in order to help academia, medicine, and sports. It provides enlightenment to the contemporary public on how to participate in sports training more healthily.

Supplemental Protein and a Multinutrient Beverage Speed Wound Healing after Acute Sleep Restriction in Healthy Adults

BACKGROUND

Physiologic and psychologic stress slow healing from experimental wounds by impairing immune function.

OBJECTIVES

We aimed to determine whether supplemental protein and multinutrient supplementation improved wound healing markers after acute stress induced by acute sleep restriction.

METHODS

In this single-blind, crossover study in generally healthy young adults (18 males/2 females; mean ± SD age: 19.7 ± 2.30 y), experimental wounds were created by removing the top layer of forearm blisters induced via suction after 48 h of 72-h sleep restriction (2-h nightly sleep), a protocol previously shown to delay wound healing. Skin barrier restoration (measured by transepidermal water loss) assessed wound healing ≤10 d postblistering, and local immune responses were evaluated by serial measurement of cytokine concentrations in fluid collected at wound sites for 48 h postblistering. Participants consumed controlled, isocaloric diets with either 0.900 g · kg-1 · d-1 protein plus placebo (PLA) or 1.50 g · kg-1 · d-1 protein plus multinutrient beverage [l-arginine: 20.0 g/d; l-glutamine: 30.0 g/d; omega-3 (n-3) fatty acids: 1.00 g/d; zinc sulfate: 24.0 mg/d; cholecalciferol: 800 IU/d; and vitamin C: 400 mg/d] (NUT) during sleep restriction and for 4 d afterwards.

RESULTS

Skin barrier restoration (primary outcome) was shorter for NUT (median: 3.98 d; IQR: 1.17 d) than for PLA (median: 5.25 d; IQR: 1.05 d) (P = 0.001). Cytokines from wound fluid (secondary outcome) increased over time (main effect of time P ≤ 0.001), except IL-13 (P = 0.07); however, no effects of treatment were observed.

CONCLUSIONS

Supplemental nutrition may promote wound healing after sleep restriction in healthy adults including military personnel, the latter of which also have a high incidence of wounds and infection.This trial was registered at clinicaltrials.gov as NCT03525184.

The Importance of Sleep and Circadian Rhythms for Vaccination Success and Susceptibility to Viral Infections

Sleep and circadian rhythms are closely involved in the immune system and its regulation. Here, we describe this relationship and provide recommendations regarding the influence of sleep and circadian rhythms on vaccination success. We review studies investigating how viral susceptibility is influenced by changes in immunological parameters as a consequence of sleep deprivation. Short sleep duration and poor sleep efficiency both appear to be strong factors leading to greater vulnerability. In addition, both sleep duration and the time of day of the vaccination seem to be associated with the magnitude of the antibody response after vaccination. Based on these findings, a recommendation would consist of a sleep duration of 7 h or more every night to both reduce the risk of infection and to optimize the efficacy of vaccination with respect to circadian timing. Improving sleep quality and its circadian timing can potentially play a role in preventing infection and in vaccination benefits. In conclusion, sufficient (or longer) sleep duration is important in both reducing susceptibility to infection and increasing antibody response after vaccination.

Effect of Exercise on Acute Senescent Lymphocyte Counts: A Systematic Review and Meta-Analysis

BACKGROUND

Highly differentiated, senescent lymphocytes are pro-inflammatory and contribute to age-related systemic inflammation, called inflammageing. There are several reports of acute changes in senescent lymphocyte counts post exercise, which potentially have consequences for systemic inflammation. However, there is little consensus since the studies differ with respect to participants, exercise protocols, cellular markers assessed, and the time point of assessment post exercise.

OBJECTIVE

We performed a systematic review and meta-analysis to assess the impact of exercise on senescent lymphocyte counts in blood immediately, 1 h and 2 h post exercise.

METHODS

The search was performed in PubMed (MEDLINE), Web of Science, Embase, Scopus, and Cochrane, on January 11, 2021. The 13 studies selected tested aerobic exercise effects, mainly in young men. They assessed the counts of lymphocytes (CD4 T cells, CD8 T cells, and NK cells), with the following immune cell marker combinations: KLRG1+, CD57+ (only NK cells), EMRA T cells (CD45RA+CCR7-CD28-CD27-), CD28-CD27-, KLRG1+CD28-, and CD28-. Independent extraction of articles was done by 2 researchers.

RESULTS

Standardized mean difference (SMD) and 95% confidence interval between baseline and post exercise showed significant increase (SMD >0.9, p < 0.003) in all types of senescent lymphocytes counts immediately post exercise. At 1 h post exercise, senescent CD4 T cells returned to baseline values (p = 0.74), CD8 T cells were reduced (-0.26 [-0.41; -0.11], p = 0.001), and senescent NK cells were raised (0.62 [0.14; 1.10], p = 0.01) above baseline. By 2 h post exercise, senescent CD4 T cells were reduced (-0.94 [-1.40; -0.48], p < 0.001), CD8 T cells remained below baseline (-0.53 [-1.04; -0.009], p = 0.04), and NK cells had returned to baseline values (-0.29 [-0.64; 0.07], p = 0.11). The main determinants of heterogeneity between studies were cytomegalovirus (CMV) serostatus and the characteristics of exercise protocols. CMV+ individuals had a higher immediate lymphocytosis and 1 h post lymphopenia than CMV- individuals. Exercise performed at higher intensities and shorter durations led to higher magnitude of change in senescent lymphocyte counts at all time-points.

CONCLUSION

The differing effects of exercise on senescent NK cells and CD4 and CD8 T cells suggest differing susceptibility to factors modulating lymphocyte extravasation such as adrenaline and exercise intensity.

Overnight Immune Regulation and Subjective Measures of Sleep: A Three Night Observational Study in Adolescent Track and Field Athletes

To ensure health maintenance of young athletes, immunological stress due to physical exercise has to be balanced for performance development and health maintenance. Sleep is an important influencing factor for immune regulation because of its regenerating effect. In an attempt to assess overnight immune regulation, this observational study aimed to examine associations between changes in capillary immunological blood markers and measures of sleep in adolescent athletes. Over a period of three nights, 12 male (n = 6) and female (n = 6) adolescent track and field athletes aged 16.4 ± 1.1 years were monitored for their sleep behavior (e.g., sleep duration, sleep depth) and immune regulation by using subjective (e.g., sleep) and objective (capillary blood markers) measurement tools. Over the 4 day (three nights), athletes followed their daily routines (school, homework, free time activities, and training). Training was performed for different disciplines (sprint, hurdles, and long-jump) following their daily training routines. Training included dynamic core stability training, coordination training, speed training, resistance training, and endurance training. Capillary blood samples were taken 30-45 min after the last training session (10:00-12:00 a.m. or 5:00-6:00 p.m.) and every morning between 7:00 and 10:00 a.m. Changes in capillary blood markers from post-training to the next morning and morning-to-morning fluctuations in capillary blood markers were analyzed over a three-night period using a generalized estimating equations (GEE) statistical approach. Associations of overnight changes with measures of sleep were analyzed using GEE. We found significant decreases in white blood cell count (WBC), granulocytes (GRAN), granulocytes% (GRAN%), monocytes (MID), and granulocyte-lymphocyte-ratio. In contrast, lymphocytes% (LYM%) increased significantly and systemic inflammation index showed no difference from post-training to the next morning. Furthermore, there was a significant decrease in WBC and GRAN between morning 1 and morning 3. At morning 4, values returned to baseline (morning 1), irrespective if athletes performed a training session or rested on day 3. Furthermore, sleep duration was significantly and negatively associated with changes in WBC (βz = -0.491) and lymphocytes (βz = -0.451). Our results indicate that overnight sleep duration is an important parameter of immunological overnight regulation for adolescent athletes.

Influence of Exercise on Exhausted and Senescent T Cells: A Systematic Review

The impaired effector function of exhausted and senescent T cells is implicated in cancer progression and inadequate vaccine responses. Exercise has been shown to improve cancer therapy and vaccine efficacy, most likely by improving immune function. However, given inconsistent terminology and definitions, the interactions between exercise and exhausted and senescent T cells remain unclear. We therefore performed a systematic review to investigate the effect of exercise on senescent and exhausted CD8⁺ T cell populations clearly defined by protein surface markers. Thirty articles were included, with the majority (n = 24) reporting senescent T cell populations defined according to a variety of surface markers. Repeated exercise was shown to be beneficial through limiting the accumulation of senescent and exhausted CD8⁺ T cells. This outcome is likely related to exercise-induced preferential mobilization of senescent T cells promoting apoptosis in the peripheral blood compartment. Future studies need to determine the clinical relevance of this effect in cancer prevention and vaccine efficacy. Data regarding exercise and exhausted T cells are limited due to a lack of available high-quality studies. Future studies require the control of confounding variables such as sex and cytomegalovirus (CMV) status, and consistent definitions of exhausted and senescent T cell populations to improve comparisons between studies and interventions.

One night of sleep fragmentation does not affect exercise-induced leukocyte trafficking or mitogen-stimulated leukocyte oxidative burst in healthy men

PURPOSE

This study examined whether one night of sleep fragmentation alters circulating leukocyte counts and mitogen-stimulated oxidative burst by leukocytes at rest and in response to an acute bout of vigorous exercise.

METHODS

In a randomised crossover design, nine healthy men (mean ± SD: age 22 ± 2 years; BMI 24.9 ± 1.9 kg/m²) were exposed to one night of fragmented or uninterrupted sleep before cycling for 45 min at 71% ± 4% V̇O_2peak. Finger-tip blood samples were collected at rest, immediately post-exercise and one-hour post-exercise. Total leukocytes, lymphocytes, monocytes and neutrophils were counted. Leukocyte oxidative burst was assessed in whole blood by measuring Reactive Oxygen Species (ROS) production with luminol-amplified chemiluminescence after stimulation with phorbol 12-myristate 13-acetate (PMA).

RESULTS

Exercise elicited the expected trafficking pattern of leukocytes, lymphocytes, monocytes and neutrophils. Compared to rest, PMA-stimulated ROS production was increased one-hour post-exercise (+73% ± 65%; p = 0.019; data combined for fragmented and uninterrupted sleep). There were no statistically significant effects of fragmented sleep on leukocyte, lymphocyte, monocyte, and neutrophil counts or on ROS production at rest, immediately post-exercise or one-hour post-exercise (p > 0.05). However, with fragmented sleep, there was a +10% greater lymphocytosis immediately post-exercise (fragmented +40% ± 37%; uninterrupted +30% ± 35%; p = 0.51) and a -19% smaller neutrophilia by one-hour post-exercise (fragmented +103% ± 88%; uninterrupted +122% ± 131%; p = 0.72).

CONCLUSION

Fragmented sleep did not substantially alter the magnitude or pattern of exercise-induced leukocyte trafficking or mitogen-stimulated oxidative burst by leukocytes.

COVID-19: Sleep, Circadian Rhythms and Immunity - Repurposing Drugs and Chronotherapeutics for SARS-CoV-2

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has affected nearly 28 million people in the United States and has caused more than five hundred thousand deaths as of February 21, 2021. As the novel coronavirus continues to take its toll in the United States and all across the globe, particularly among the elderly (>65 years), clinicians and translational researchers are taking a closer look at the nexus of sleep, circadian rhythms and immunity that may contribute toward a more severe coronavirus disease-19 (COVID-19). SARS-CoV-2-induced multi-organ failure affects both central and peripheral organs, causing increased mortality in the elderly. However, whether differences in sleep, circadian rhythms, and immunity between older and younger individuals contribute to the age-related differences in systemic dysregulation of target organs observed in SARS-CoV-2 infection remain largely unknown. Current literature demonstrates the emerging role of sleep, circadian rhythms, and immunity in the development of chronic pulmonary diseases and respiratory infections in human and mouse models. The exact mechanism underlying acute respiratory distress syndrome (ARDS) and other cardiopulmonary complications in elderly patients in combination with associated comorbidities remain unclear. Nevertheless, understanding the critical role of sleep, circadian clock dysfunction in target organs, and immune status of patients with SARS-CoV-2 may provide novel insights into possible therapies. Chronotherapy is an emerging concept that is gaining attention in sleep medicine. Accumulating evidence suggests that nearly half of all physiological functions follow a strict daily rhythm. However, healthcare professionals rarely take implementing timed-administration of drugs into consideration. In this review, we summarize recent findings directly relating to the contributing roles of sleep, circadian rhythms and immune response in modulating infectious disease processes, and integrate chronotherapy in the discussion of the potential drugs that can be repurposed to improve the treatment and management of COVID-19.

Immune Response of Elite Enduro Racers to Laboratory and Racing Environments: The Influence of Training Impulse and Vibration

Introduction: Understanding the sport-specific immune response elicited during both training and competition is imperative to maximise athlete health and performance. Despite a growing population of professional enduro mountain bike athletes, little is known about the recovery of the immune system following enduro racing events. Methods: Nine international level elite enduro mountain bike athletes (age 24.3 ± 2.4 years, height 178.5 ± 8.7 cm, mass 76.5 ± 12.5 kg) completed a laboratory-based maximal exercise test (LAB) on a cycle ergometer and competed in an international mountain bike enduro race event (RACE). Blood samples were taken before, immediately after, and 1 h after LAB and before, 1 h after, and 17 h after RACE. Leukocyte subsets were enumerated using seven-colour flow cytometry. Lucia’s training impulse (LuTRIMP) and vibration exposure (VIB) were quantified during RACE. Results: Seven participants were included in the final analyses. There was a significant (p < 0.05) increase in neutrophil count alongside a reduction of cytotoxic lymphocyte cell subsets of both the innate (CD3⁻/CD56⁺ NK-cells and CD3⁻/CD56^dim NK-cells) and adaptive (CD8⁺/CD62L⁻/CD45RA⁻ T-cells and CD8⁺/CD27⁺/CD28⁻ T-cells) components of the immune system one hour after RACE. All cell counts returned to baseline values 17 h afterwards (p > 0.05). Cell subset redistribution from pre- to post-one-hour time points (%Δpre-post1h) in cell subsets with potent effector functions (Neutrophils, CD3⁻/CD56⁺ NK-cells, CD8⁺/CD62L⁻/CD45RA⁻ T-cells, CD8⁺/CD27⁺/CD28⁻ T-cells, and CD3⁻/CD56^dim/CD57⁻ NK-cells) was significantly greater at RACE than LAB (p < 0.05). VIB was shown to be a superior predictor of %Δpre-post1h CD4⁺ T-cells, CD4⁺ early T-cells, CD4⁺ naïve T-cells, and NK cells as compared with LuTRIMP on its own (ΔR² = 0.63 − 0.89, p < 0.05). Conclusions: The race event offers a greater challenge to the immune system than LAB, and potentially, whole body vibration is a key component of training load measurement in mountain bike applications.

Does exercise attenuate age- and disease-associated dysfunction in unconventional T cells? Shining a light on overlooked cells in exercise immunology

Unconventional T Cells (UTCs) are a unique population of immune cells that links innate and adaptive immunity. Following activation, UTCs contribute to a host of immunological activities, rapidly responding to microbial and viral infections and playing key roles in tumor suppression. Aging and chronic disease both have been shown to adversely affect UTC numbers and function, with increased inflammation, change in body composition, and physical inactivity potentially contributing to the decline. One possibility to augment circulating UTCs is through increased physical activity. Acute exercise is a potent stimulus leading to the mobilization of immune cells while the benefits of exercise training may include anti-inflammatory effects, reductions in fat mass, and improved fitness. We provide an overview of age-related changes in UTCs, along with chronic diseases that are associated with altered UTC number and function. We summarize how UTCs respond to acute exercise and exercise training and discuss potential mechanisms that may lead to improved frequency and function.

Perfect timing: circadian rhythms, sleep, and immunity - an NIH workshop summary

Recent discoveries demonstrate a critical role for circadian rhythms and sleep in immune system homeostasis. Both innate and adaptive immune responses - ranging from leukocyte mobilization, trafficking, and chemotaxis to cytokine release and T cell differentiation -are mediated in a time of day-dependent manner. The National Institutes of Health (NIH) recently sponsored an interdisciplinary workshop, "Sleep Insufficiency, Circadian Misalignment, and the Immune Response," to highlight new research linking sleep and circadian biology to immune function and to identify areas of high translational potential. This Review summarizes topics discussed and highlights immediate opportunities for delineating clinically relevant connections among biological rhythms, sleep, and immune regulation.

The Sleep-Immune Crosstalk in Health and Disease

Sleep and immunity are bidirectionally linked. Immune system activation alters sleep, and sleep in turn affects the innate and adaptive arm of our body's defense system. Stimulation of the immune system by microbial challenges triggers an inflammatory response, which, depending on its magnitude and time course, can induce an increase in sleep duration and intensity, but also a disruption of sleep. Enhancement of sleep during an infection is assumed to feedback to the immune system to promote host defense. Indeed, sleep affects various immune parameters, is associated with a reduced infection risk, and can improve infection outcome and vaccination responses. The induction of a hormonal constellation that supports immune functions is one likely mechanism underlying the immune-supporting effects of sleep. In the absence of an infectious challenge, sleep appears to promote inflammatory homeostasis through effects on several inflammatory mediators, such as cytokines. This notion is supported by findings that prolonged sleep deficiency (e.g., short sleep duration, sleep disturbance) can lead to chronic, systemic low-grade inflammation and is associated with various diseases that have an inflammatory component, like diabetes, atherosclerosis, and neurodegeneration. Here, we review available data on this regulatory sleep-immune crosstalk, point out methodological challenges, and suggest questions open for future research.

Older men display elevated levels of senescence-associated exercise-responsive CD28null angiogenic T cells compared with younger men

Aging is associated with elevated cardiovascular disease risk. As a result of aging, endothelial dysfunction develops, partly due to a reduction in vascular regenerative ability. CD31+ T cells (angiogenic T cells; TANG ) possess highly angiogenic capabilities; however, these cells are significantly reduced in older populations. In addition, older populations possess significantly higher senescent and highly differentiated T-cell levels in circulation, and these are reported to be highly exercise responsive. We investigated whether older adults display greater levels of circulating senescent (CD28null ) TANG cells and whether these cells were more exercise responsive than CD28+ TANG cells. Young (18-25 years; n = 9) and older (60-75 years; n = 10) healthy men undertook a 30-min cycling bout at 70% V˙O2 peak, with circulating TANG cells (CD3+  CD31+  CD28+/null ; including CD4+ and CD8+ subsets) measured preexercise, postexercise, and 1 h post exercise by flow cytometry. Older adults displayed reduced basal levels of TANG cells (mean ± SEM: 410 ± 81 vs. 784 ± 118 cells·μL, P = 0.017), despite a greater proportion of these cells being CD28null (26.26 ± 5.08 vs. 13.36 ± 2.62%, P = 0.044). Exercise significantly increased the circulating number of TANG cells in both young and older men. However, in older men alone, exercise preferentially mobilized CD28null CD8+ TANG cells compared with CD28+ TANG cells (time × phenotype interaction: P = 0.022; Δ74 ± 29 vs. Δ27 ± 15 cells·μL, P = 0.059), with no such difference observed between these phenotypes in the young population. In conclusion, this is the first study to demonstrate that despite observing lower circulating numbers of TANG cells, older adults display greater levels of senescent TANG cells in comparison with younger individuals, and these cells are more exercise responsive than CD28+ TANG cells. Lower number of circulating TANG and greater levels of senescent-associated CD28null TANG may contribute to greater CVD risk with advancing age.

Recovery of the immune system after exercise

The notion that prolonged, intense exercise causes an "open window" of immunodepression during recovery after exercise is well accepted. Repeated exercise bouts or intensified training without sufficient recovery may increase the risk of illness. However, except for salivary IgA, clear and consistent markers of this immunodepression remain elusive. Exercise increases circulating neutrophil and monocyte counts and reduces circulating lymphocyte count during recovery. This lymphopenia results from preferential egress of lymphocyte subtypes with potent effector functions [e.g., natural killer (NK) cells, γδ T cells, and CD8⁺ T cells]. These lymphocytes most likely translocate to peripheral sites of potential antigen encounter (e.g., lungs and gut). This redeployment of effector lymphocytes is an integral part of the physiological stress response to exercise. Current knowledge about changes in immune function during recovery from exercise is derived from assessment at the cell population level of isolated cells ex vivo or in blood. This assessment can be biased by large changes in the distribution of immune cells between blood and peripheral tissues during and after exercise. Some evidence suggests that reduced immune cell function in vitro may coincide with changes in vivo and rates of illness after exercise, but more work is required to substantiate this notion. Among the various nutritional strategies and physical therapies that athletes use to recover from exercise, carbohydrate supplementation is the most effective for minimizing immune disturbances during exercise recovery. Sleep is an important aspect of recovery, but more research is needed to determine how sleep disruption influences the immune system of athletes.