Decreases in thymopoiesis of astronauts returning from space flight

Benjamin, Cara L.; Stowe, Raymond P.; John, Lisa S. St.; Sams, Clarence F.; Mehta, Satish K.; Crucian, Brian; Pierson, Duane L.; Komanduri, Krishna V.

doi:10.1172/jci.insight.88787

Cited by 43 publications

(37 citation statements)

References 40 publications

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“…The phenomenon of thymic atrophy is universally observed, which also includes astronauts, in whom the output of the thymus in diminished post‐return from space flights, probably due to stress‐induced cortisol amounts . As a result, the adaptive immune response may diminish due to lower thymic output, which leads to unfavourable outcomes during various clinical conditions.…”

Section: Resultsmentioning

confidence: 99%

“…Ó 2017 The Foundation for the Scandinavian Journal of Immunology flights, probably due to stress-induced cortisol amounts [10]. As a result, the adaptive immune response may diminish due to lower thymic output, which leads to unfavourable outcomes during various clinical conditions.…”

Section: Resultsmentioning

confidence: 99%

“…The loss in cellularity of the thymus is termed as thymic atrophy, which is a physiological phenomenon and is well known to occur during ageing . In addition, thymic atrophy occurs during numerous scenarios such as stress , malnutrition , infections and cancer therapy . Thymic atrophy may arise due to apoptosis of thymocytes, deterioration of thymic architecture, loss in influx of ETPs to the thymus or a combination of the above scenarios.…”

Section: Introductionmentioning

confidence: 99%

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Thymic Atrophy: Experimental Studies and Therapeutic Interventions

Majumdar

Nandi

2017

Scand J Immunol

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The thymus is essential for T cell development and maturation. It is extremely sensitive to atrophy, wherein loss in cellularity of the thymus and/or disruption of the thymic architecture occur. This may lead to lower na€ ıve T cell output and limited TCR diversity. Thymic atrophy is often associated with ageing. What is less appreciated is that proper functioning of the thymus is critical for reduction in morbidity and mortality associated with various clinical conditions including infections and transplantation. Therefore, therapeutic interventions which possess thymopoietic potential and lower thymic atrophy are required. These treatments enhance thymic output, which is a vital factor in generating favourable outcomes in clinical conditions. In this review, experimental studies on thymic atrophy in rodents and clinical cases where the thymus atrophies are discussed. In addition, mechanisms leading to thymic atrophy during ageing as well as during various stress conditions are reviewed. Therapies such as zinc supplementation, IL7 administration, leptin treatment, keratinocyte growth factor administration and sex steroid ablation during thymic atrophy involving experiments in animals and various clinical scenarios are reviewed. Interventions that have been used across different scenarios to reduce the extent of thymic atrophy and enhance its output are discussed. This review aims to speculate on the roles of combination therapies, which by acting additively or synergistically may further alleviate thymic atrophy and boost its function, thereby strengthening cellular T cell responses.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thymic Atrophy: Experimental Studies and Therapeutic Interventions

Majumdar

Nandi

2017

Scand J Immunol

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“…Many clinical situations associated with aging have been described as possible causes of impaired thymic function, including changes in growth factor and cytokine expression, low hormone production, and bone marrow loss ( 7 , 8 ). TREC quantification has been shown in various studies to be more reliable for evaluation of thymic function ( 9 – 16 ). A series of observations on TREC dynamics during human immunodeficiency virus (HIV) infection and treatment and in autologous and allogeneic hematopoietic stem cell transplantation (HSCT) confirmed the usefulness of TREC analysis as a quantitative marker for thymic function.…”

Section: Introductionmentioning

confidence: 99%

Thymopoiesis in Pre- and Post-Hematopoietic Stem Cell Transplantation

et al. 2018

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Hematopoietic stem cell transplantation (HSCT) is an important therapeutic option for some hematological diseases. However, patients who undergo HSCT acquire a state of immunodeficiency that causes significant mortality. Reconstitution of thymic function is needed to support the immune system. One way to measure thymic function is through T-cell receptor excision circle (TREC) quantification. TRECs are generated by T-cell receptor gene rearrangements during T-cell maturation in the thymus and represent a reliable marker for thymic output. In this study, we aimed to assess aging and malignant hematological diseases as two important factors that may influence thymic output before HSCT. We observed that patients before HSCT presented signal joint TREC (sjTREC) numbers lower than 606.55 copies/μg DNA (low values) compared with healthy individuals, with an odds ratio (OR) of 12.88 [95% confidence interval (CI): 5.26–31.53; p < 0.001]. Our results showed that a group of older individuals (≥50 years old), comprising both healthy individuals and patients, had an OR of 10.07 (95% CI: 2.80–36.20) for low sjTREC values compared with younger individuals (≤24 years old; p < 0.001). Multiple logistic regression analysis confirmed that both older age (≥50 years old) and malignant hematological diseases and their treatments were important and independent risk factors related to thymic function impairment (p < 0.001). The median sjTREC value for patients of all ages was significantly lower than the sjTREC median for the subgroup of older healthy individuals (≥50 years old; p < 0.001). These data suggested that patients before HSCT and healthy individuals exhibited age-dependent thymic impairment, and that prior treatment for hematological diseases may exacerbate aging-related deterioration of natural thymic function. Furthermore, we analyzed these patients 9 months post-HSCT and compared patients who underwent autologous HSCT with those who underwent allogeneic HSCT. Both groups of patients achieved sjTREC copy numbers similar to those of healthy individuals. We did not find a close relationship between impaired thymic function prior to HSCT and worse thymic recovery after HSCT.

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“…• Increase in virulence of microorganisms [26] • Hindering of thymopoiesis significantly [27] • More latent viral reactivation [28] There are more reports about immune system alterations [25,26,29], but some authors have not reported significant changes [30].…”

Section: Immune Systemmentioning

confidence: 99%

Vitamin D in Space

Khoshvaghti¹

2019

Fads and Facts About Vitamin D

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Mankind has explored space since many years ago for distinct purposes. The space environment has its special features including microgravity (weightlessness), radiation, vacuum, and extreme temperature. It is fascinating to hear space traveling or even living on another planet, but it may cause dramatic changes in the human body. The skeleton has the primary role for the human body on the Earth and also in space. Osteoporosis is the principal feature in spaceflights occurring sooner or later. It will pose health risks. The aging of the population is the cause for osteoporosis to be more prevalent in the future. It seems that aging will happen sooner in space for human beings that are accustomed to living on the Earth. A complex of all reported changes that would occur in space, the picture of a closely resembling aged man emerges. Vitamin D can be synthesized and acts as a hormone. Its receptors are evident in more than 30 human tissues. Vitamin D has positive effects on the skeleton and other systems of the body in many regards. Multiple actions have been claimed for vitamin D (real or false), many aspects of which are not fully understood. The issue applies more about the vitamin and space, which has been tried to describe in this chapter.

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Decreases in thymopoiesis of astronauts returning from space flight

Cited by 43 publications

References 40 publications

Thymic Atrophy: Experimental Studies and Therapeutic Interventions

Thymic Atrophy: Experimental Studies and Therapeutic Interventions

Thymopoiesis in Pre- and Post-Hematopoietic Stem Cell Transplantation

Vitamin D in Space

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