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

Infections in long-duration space missions

As government space agencies and private companies announce plans for deep space exploration and colonisation, prioritisation of medical preparedness is becoming crucial. Among all medical conditions, infections pose one of the biggest threats to astronaut health and mission success. To gain a comprehensive understanding of these risks, we review the measured and estimated incidence of infections in space, effect of space environment on the human immune system and microbial behaviour, current preventive and management strategies for infections, and future perspectives for diagnosis and treatment. This information will enable space agencies to enhance their comprehension of the risk of infection in space, highlight gaps in knowledge, aid better crew preparation, and potentially contribute to sepsis management in terrestrial settings, including not only isolated or austere environments but also conventional clinical settings.

Physical exercise, the immune system and infection risk: implications for prehabilitation and rehabilitation for solid organ transplantation candidates and recipients

PURPOSE OF REVIEW

Solid organ transplantation recipients have an increased risk of infection, exacerbated by immunosuppressant medications that need to finely balance suppression of the immune system to prevent allograft rejection while avoiding over-suppression leading to infections and malignancy. Exercise modulates immune functions, with moderate-intensity activities particularly associated with enhanced antiviral immunity and reduced infection incidence. However, investigations of the effects of exercise and physical activity on immune function and infection risk posttransplantation are scarce. This review highlights areas where the relationship between exercise, immune function and infection risk has greatest potential for benefit for solid organ transplantation and therefore greatest need for investigation.

RECENT FINDINGS

Moderate and higher intensity exercise do not appear to cause adverse immunological effects in kidney transplantation recipients, although evidence from other organ transplantation is lacking. Evidence from healthy younger and older adults suggests that regular exercise can reduce risk of respiratory infections and latent herpesvirus reactivation and improves antibody responses to vaccination, which is of great importance for organ transplantation recipients.

SUMMARY

There is a strong need for research to investigate the role of exercise on immune function and infection risk in solid organ transplantation to improve both allograft survival and long-term health of the recipient.

Using single-sample networks to identify the contrasting patterns of gene interactions and reveal the radiation dose-dependent effects in multiple tissues of spaceflight mice

Transcriptome profiles are sensitive to space stressors and serve as valuable indicators of the biological effects during spaceflight. Herein, we transformed the expression profiles into gene interaction patterns by single-sample networks (SSNs) and performed the integrated analysis on the 301 spaceflight and 290 ground control samples, which were obtained from the GeneLab platform. Specifically, an individual SSN was established for each sample. Based on the topological structures of 591 SSNs, the differentially interacted genes (DIGs) were identified between spaceflights and ground controls. The results showed that spaceflight disrupted the gene interaction patterns in mice and resulted in significant enrichment of biological processes such as protein/amino acid metabolism and nucleic acid (DNA/RNA) metabolism (P-value < 0.05). We observed that the mice exposed to radiation doses within the three intervals (4.66-7.14, 7.592-8.295, 8.49-22.099 mGy) exhibited similar gene interaction patterns. Low and medium doses resulted in changes to the circadian rhythm, while the damaging effects on genetic material became more pronounced in higher doses. The gene interaction patterns in response to space stressors varied among different tissues, with the spleen, lung, and skin being the most responsive to space radiation (P-value < 0.01). The changes observed in gene networks during spaceflight conditions might contribute to the development of various diseases, such as mental disorders, depression, and metabolic disorders, among others. Additionally, organisms activated specific gene networks in response to virus reactivation. We identified several hub genes that were associated with circadian rhythms, suggesting that spaceflight could lead to substantial circadian rhythm dysregulation.

Long-term human spaceflight and inflammaging: Does it promote aging?

Spaceflight and its associated stressors, such as microgravity, radiation exposure, confinement, circadian derailment and disruptive workloads represent an unprecedented type of exposome that is entirely novel from an evolutionary stand point. Within this perspective, we aimed to review the effects of prolonged spaceflight on immune-neuroendocrine systems, brain and brain-gut axis, cardiovascular system and musculoskeletal apparatus, highlighting in particular the similarities with an accelerated aging process. In particular, spaceflight-induced muscle atrophy/sarcopenia and bone loss, vascular and metabolic changes, hyper and hypo reaction of innate and adaptive immune system appear to be modifications shared with the aging process. Most of these modifications are mediated by molecular events that include oxidative and mitochondrial stress, autophagy, DNA damage repair and telomere length alteration, among others, which directly or indirectly converge on the activation of an inflammatory response. According to the inflammaging theory of aging, such an inflammatory response could be a driver of an acceleration of the normal, physiological rate of aging and it is likely that all the systemic modifications in turn lead to an increase of inflammaging in a sort of vicious cycle. The most updated countermeasures to fight these modifications will be also discussed in the light of their possible application not only for astronauts' benefit, but also for older adults on the ground.

Are Skeletal Muscle Changes during Prolonged Space Flights Similar to Those Experienced by Frail and Sarcopenic Older Adults?

Microgravity exposure causes several physiological and psychosocial alterations that challenge astronauts' health during space flight. Notably, many of these changes are mostly related to physical inactivity influencing different functional systems and organ biology, in particular the musculoskeletal system, dramatically resulting in aging-like phenotypes, such as those occurring in older persons on Earth. In this sense, sarcopenia, a syndrome characterized by the loss in muscle mass and strength due to skeletal muscle unloading, is undoubtedly one of the most critical aging-like adverse effects of microgravity and a prevalent problem in the geriatric population, still awaiting effective countermeasures. Therefore, there is an urgent demand to identify clinically relevant biological markers and to underline molecular mechanisms behind these effects that are still poorly understood. From this perspective, a lesson from Geroscience may help tailor interventions to counteract the adverse effects of microgravity. For instance, decades of studies in the field have demonstrated that in the older people, the clinical picture of sarcopenia remarkably overlaps (from a clinical and biological point of view) with that of frailty, primarily when referred to the physical function domain. Based on this premise, here we provide a deeper understanding of the biological mechanisms of sarcopenia and frailty, which in aging are often considered together, and how these converge with those observed in astronauts after space flight.

Actividad física en mujeres jóvenes chilenas durante el confinamiento por COVID-19

Objetivo: El presente estudio da respuesta a la pregunta: ¿Existen diferencias en el nivel de actividad física de mujeres chilenas antes y durante el confinamiento por COVID-19? Método: El estudio tiene un diseño no experimental longitudinal de tendencia con un n=1.051 mujeres chilenas jóvenes. Se midieron las diferencias en el nivel de actividad física entre los grupos pre (preCOVID) y post (COVID-19); y de la muestra COVID-19 con los datos teóricos tanto de estudios de actividad física previos como de encuestas nacionales gubernamentales. Resultados: las mujeres del grupo COVID-19 presentan niveles de actividad física significativamente más bajos que las mujeres de la muestra preCOVID-19; y que las muestras de mujeres de estudios empíricos anteriores. Conclusión: en tiempos de COVID-19 las mujeres jóvenes chilenas presentan un nivel de actividad física significativamente menor en tiempos previos al confinamiento.

Salivary immunity of elite collegiate American football players infected with SARS-CoV-2 normalizes following isolation

The impact of COVID-19 on systemic immunity in the general population has been well characterized, however the short-term effects of COVID-19 infection on innate salivary immunity in elite-level athletes are unknown. Therefore, this study aimed to determine whether elite college football athletes had altered salivary immunity following the CDC-recommended isolation post-SARS-CoV-2 infection. Salivary samples were obtained from fourteen elite football players who tested positive for SARS-CoV-2 (n = 14), immediately after CDC-recommended isolation (average days = 14 ± 2 days) and fifteen controls who remained uninfected with SARS-CoV-2. Biomarkers of innate salivary immunity (sIgA and alpha-amylase), antimicrobial proteins (AMPs, i.e., HNP1-3, lactoferrin, LL-37) and lung inflammation (SPA, SPLI, and Neutrophil Elastase-alpha-1-antitrypsin complex) were measured. Independent student t-tests were used to determine changes in biomarkers between groups. Although all AMP levels were within normal range, Human Neutrophil Defensin 1-3 concentrations and secretion rates were higher in SARS-CoV-2+ compared to SARS-CoV-2-. This suggests that the CDC-recommended isolation period is sufficient to ensure that athletes' salivary immunity is not compromised upon return to sports, and athletes post-COVID-19 infection do not appear to be at greater risk for secondary infection than those with no history of COVID-19.

Spaceflight Virology: What Do We Know about Viral Threats in the Spaceflight Environment?

Viruses constitute a significant part of the human microbiome, so wherever humans go, viruses are brought with them, even on space missions. In this mini review, we focus on the International Space Station (ISS) as the only current human habitat in space that has a diverse range of viral genera that infect microorganisms from bacteria to eukaryotes. Thus, we have reviewed the literature on the physical conditions of space habitats that have an impact on both virus transmissibility and interaction with their host, which include UV radiation, ionizing radiation, humidity, and microgravity. Also, we briefly comment on the practices used on space missions that reduce virus spread, that is, use of antimicrobial surfaces, spacecraft sterilization practices, and air filtration. Finally, we turn our attention to the health threats that viruses pose to space travel. Overall, even though efforts are taken to ensure safe conditions during human space travel, for example, preflight quarantines of astronauts, we reflect on the potential risks humans might be exposed to and how those risks might be aggravated in extraterrestrial habitats.

The Future of Personalized Medicine in Space: From Observations to Countermeasures

The aim of personalized medicine is to detach from a “one-size fits all approach” and improve patient health by individualization to achieve the best outcomes in disease prevention, diagnosis and treatment. Technological advances in sequencing, improved knowledge of omics, integration with bioinformatics and new in vitro testing formats, have enabled personalized medicine to become a reality. Individual variation in response to environmental factors can affect susceptibility to disease and response to treatments. Space travel exposes humans to environmental stressors that lead to physiological adaptations, from altered cell behavior to abnormal tissue responses, including immune system impairment. In the context of human space flight research, human health studies have shown a significant inter-individual variability in response to space analogue conditions. A substantial degree of variability has been noticed in response to medications (from both an efficacy and toxicity perspective) as well as in susceptibility to damage from radiation exposure and in physiological changes such as loss of bone mineral density and muscle mass in response to deconditioning. At present, personalized medicine for astronauts is limited. With the advent of longer duration missions beyond low Earth orbit, it is imperative that space agencies adopt a personalized strategy for each astronaut, starting from pre-emptive personalized pre-clinical approaches through to individualized countermeasures to minimize harmful physiological changes and find targeted treatment for disease. Advances in space medicine can also be translated to terrestrial applications, and vice versa. This review places the astronaut at the center of personalized medicine, will appraise existing evidence and future preclinical tools as well as clinical, ethical and legal considerations for future space travel.

Exercise and adrenergic regulation of immunity

Exercise training has a profound impact on immunity, exerting a multitude of positive effects in indications such as immunosenescence, cancer, viral infections and inflammatory diseases. The immune, endocrine and central nervous systems work in a highly synergistic manner and it has become apparent that catecholamine signaling through leukocyte β-adrenergic receptors (β-ARs) is a key mechanism by which exercise mediates improvements in immune function to help mitigate numerous disease conditions. Central to this is the preferential mobilization and redistribution of effector lymphocytes with potent anti-viral and anti-tumor activity, their interaction with muscle-derived cytokines, and the effects of catecholamine signaling on mitochondrial biogenesis, immunometabolism and the resulting inflammatory response. Here, we review the impact of acute and chronic exercise on adrenergic regulation of immunity in the context of aging, cancer, viral infections and inflammatory disease. We also put forth our contention that exercise interventions designed to improve immunity, prevent disease and reduce inflammation should consider the catecholamine-AR signaling axis as a therapeutic target and ask whether or not the adrenergic signaling machinery can be 'trained' to improve immune responses to stress, disease or during the normal physiological process of aging. Finally, we discuss potential strategies to augment leukocyte catecholamine signaling to boost the effects of exercise on immunity in individuals with desensitized β-ARs or limited exercise tolerance.

Cardiorespiratory Fitness, Inflammation, and the Incident Risk of Pneumonia

INTRODUCTION

Both inflammation and cardiorespiratory fitness (CRF) are associated with the risk of respiratory infections. To clarify the hypothesis that CRF attenuates the incident risk of pneumonia due to inflammation, we conducted a prospective study examining the independent and joint associations of inflammation and CRF on the risk of pneumonia in a population sample of 2041 middle-aged men.

METHODS

Cardiorespiratory fitness was directly measured as peak oxygen uptake (V˙o2peak) during progressive exercise testing to volitional fatigue, and categorized into tertiles. Inflammation was defined by high-sensitivity C-reactive protein (hsCRP). Pneumonia cases were identified by internal medicine physicians using the International Classification of Diseases codes in clinical practice.

RESULTS

During a median follow-up of 27 yr, 432 pneumonia cases were recorded. High hsCRP and CRF were associated with a higher risk (HR = 1.38; 95% CI, 1.02-1.88) and a lower risk of pneumonia (HR = 0.55; CI, 0.39-0.76) after adjusting for potential confounders, respectively. Compared with normal hsCRP-Fit, moderate to high hsCRP-Unfit had an increased risk of pneumonia (HR = 1.63; CI, 1.21-2.20), but moderate to high hsCRP-Fit was not associated with an increased risk of pneumonia (HR = 1.25; CI, 0.93-1.68).

CONCLUSIONS

High CRF attenuates the increased risk of pneumonia due to inflammation. These findings have potential implications for the prevention of respiratory infection characterized by systemic inflammation, such as coronavirus disease-2019 (COVID-19).

Effects of Low Dose Space Radiation Exposures on the Splenic Metabolome

Future space missions will include a return to the Moon and long duration deep space roundtrip missions to Mars. Leaving the protection that Low Earth Orbit provides will unavoidably expose astronauts to higher cumulative doses of space radiation, in addition to other stressors, e.g., microgravity. Immune regulation is known to be impacted by both radiation and spaceflight and it remains to be seen whether prolonged effects that will be encountered in deep space can have an adverse impact on health. In this study, we investigated the effects in the overall metabolism of three different low dose radiation exposures (γ-rays, 16O, and 56Fe) in spleens from male C57BL/6 mice at 1, 2, and 4 months after exposure. Forty metabolites were identified with significant enrichment in purine metabolism, tricarboxylic acid cycle, fatty acids, acylcarnitines, and amino acids. Early perturbations were more prominent in the γ irradiated samples, while later responses shifted towards more prominent responses in groups with high energy particle irradiations. Regression analysis showed a positive correlation of the abundance of identified fatty acids with time and a negative association with γ-rays, while the degradation pathway of purines was positively associated with time. Taken together, there is a strong suggestion of mitochondrial implication and the possibility of long-term effects on DNA repair and nucleotide pools following radiation exposure.

The effects of β1 and β1+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 β2 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 β1 + 2 AR antagonist (nadolol) or a β1 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 β2 AR mediated, thus highlighting a role for the β2 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 β2 AR-dependent mobilization and redistribution of VSTs cumulated with each bout of exercise.

Exercise and well-being during COVID 19 - time to boost your immunity

INTRODUCTION

The COVID-19 pandemic is causing devastating global morbidity and mortality. Worldwide measures are taken to prevent human to human transmission and improve general health. Public lifestyle and health are affected by social distancing and isolation. A strong host immune response to the novel coronavirus is a key factor, for protection against infection and avoiding reaching severe stages of the disease.

AREAS COVERED

Pathophysiology and the human immune response of similar coronaviruses have been previously described. The novel coronavirus has distinct clinical stages related to the immune response. Exercise improves host innate immunity and affords protection to viral infections. Exercise also mitigates the negative effects of isolation including stress, anxiety, and sedentarism, all of which further reduces immunity and increases non-communicable disease risk.

EXPERT OPINION

Improving host immunity and mitigating the negative effects of isolation via physical activity is strongly justified. Exercise should be done in moderate intensities and volumes during the current pandemic, which is a nutritionally, psychologically, socially challenging environment in the presence of a virulent viral organism. Proactively creating innovative health promotion models with technology and government involvement with the best available evidence should be encouraged to reduce physical inactivity during the current COVID-19 pandemic and after.

Coronavirus disease-2019: A tocsin to our aging, unfit, corpulent, and immunodeficient society

Acute and chronic respiratory illnesses cause widespread morbidity and mortality, and this class of illness now includes the novel coronavirus severe acute respiratory syndrome that is causing coronavirus disease-2019 (COVID-19). The world is experiencing a major demographic shift toward an older, obese, and physically inactive populace. Risk factor assessments based on pandemic data indicate that those at higher risk for severe illness from COVID-19 include older males, and people of all ages with obesity and related comorbidities such as hypertension and type 2 diabetes. Aging in and of itself leads to negative changes in innate and adaptive immunity, a process termed immunosenescence. Obesity causes systemic inflammation and adversely impacts immune function and host defense in a way that patterns immunosenescence. Two primary prevention strategies to reduce the risk for COVID-19 at both the community and individual levels include mitigation activities and the adoption of lifestyle practices consistent with good immune health. Animal and human studies support the idea that, in contrast to high exercise workloads, regular moderate-intensity physical activity improves immunosurveillance against pathogens and reduces morbidity and mortality from viral infection and respiratory illnesses including the common cold, pneumonia, and influenza. The odds are high that infectious disease pandemics spawned by novel pathogens will continue to inflict morbidity and mortality as the world's population becomes older and more obese. COVID-19 is indeed a wake-up call, a tocsin, to the world that primary prevention countermeasures focused on health behaviors and hygiene demand our full attention and support.