It’s not all equal: a multiphasic theory of thymic involution

Aw, Danielle; Palmer, Donald B.

doi:10.1007/s10522-011-9349-0

Cited by 22 publications

(29 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Indeed, several studies using a variety of thymic indices (cellularity, epithelial space, number of recent thymic emigrants) have observed that thymic involution occurs early in life, prior to puberty and that the rate of decline is not linear, but appears to be phasic. In mice, thymic cellularity begins to decrease within the first few weeks after birth (37, 45, 53, 85) and a similar picture is evident in human (51, 52, 86), equine (87), and zebrafish (88) thymus.…”

Section: Kinetics Of Age-associated Thymic Involutionmentioning

confidence: 73%

“…Indeed, the onset of thymic involution occurs much earlier than most acknowledged features of aging and interestingly, microarray analysis of the aged thymic revealed limited overlap with genes normally associated with aging (7). Thus, we propose that there are at least two phases in thymic involution: the first occurring in early life which would be referred to as “growth-dependent thymic involution,” as it is associated with this period of physiological growth and development and another termed “age-dependent thymic involution” linked to the age-related changes that are occurring in various body systems (85). …”

Section: Kinetics Of Age-associated Thymic Involutionmentioning

confidence: 99%

See 1 more Smart Citation

The Effect of Age on Thymic Function

Palmer¹

2013

Front. Immunol.

Self Cite

363

296

View full text Add to dashboard Cite

Age-related regression of the thymus is associated with a decline in naïve T cell output. This is thought to contribute to the reduction in T cell diversity seen in older individuals and linked with increased susceptibility to infection, autoimmune disease, and cancer. Thymic involution is one of the most dramatic and ubiquitous changes seen in the aging immune system, but the mechanisms which underlying this process are poorly understood. However, a picture is emerging, implicating the involvement of both extrinsic and intrinsic factors. In this review we assess the role of the thymic microenvironment as a potential target that regulates thymic involution, question whether thymocyte development in the aged thymus is functionally impaired, and explore the kinetics of thymic involution.

show abstract

Section: Kinetics Of Age-associated Thymic Involutionmentioning

confidence: 73%

Section: Kinetics Of Age-associated Thymic Involutionmentioning

confidence: 99%

The Effect of Age on Thymic Function

Palmer¹

2013

Front. Immunol.

Self Cite

363

296

View full text Add to dashboard Cite

show abstract

“…Therefore it cannot be simply considered an aging phenomenon, but, more likely, the result of tightly regulated mechanisms many of which are still elusive (Aronson 1991;Aw and Palmer 2012). Even within mammals, thymic involution seems to follow different patterns.…”

Section: Thymic Maturation or Thymic Involution: A Process Far Beyondmentioning

confidence: 99%

Thymic Maturation and Programmed Cell Death

et al. 2014

View full text Add to dashboard Cite

The thymus plays a crucial role in the development and maintenance of the immune system, being the main site of T cell differentiation and maturation throughout life. Associated to dramatic structural changes, its function seems to markedly diminish with time, never the less, there are several data indicating that, despite organ atrophy, at least part of the thymus remains active throughout one's lifetime. In the last decades, several studies, aiming to understand the significance of age-dependent changes in thymic structure and function, highlighted the concept that developmental and maturational stages strongly depend on the balanced and coordinated occurrence of life and death options. In particular, programmed cell death represents a fundamental requirement in order to assure a proper functionality of the immune response and to avoid the formation of uncontrolled and potentially self-damaging lymphocytic clones. By contrast, the time-dependent thymic atrophy is due to progressive replacing of lymphoid with adipose tissue. In the light of the increased knowledge on the factors/mechanisms controlling the process of adipogenesis, it could be suggested that fat accumulation in the thymic stroma might not be considered a passive, deleterious consequence of aging, but instead a potential source of molecules with various biological functions. Therefore, thymus represents a very interesting model in terms of energy expenditure and trade off, tissue homeostasis, immune defence and disease escape. The implications of changes in thymic structure, in the ratio of proliferation and programmed cell death as well as the occurrence of fat involution still represent an open question and will be discussed in the present chapter.

show abstract

“…Thymic weight has been shown to increase in dogs between 1 and 6 months of age [32], after which time a reduction in thymic weight seems to correlate with atrophy of the thymic cortex in dogs up to 2 years of age [33], but longitudinal studies of dogs beyond this age are lacking. However, similarities between the profile of sj-TREC in Labrador retriever dogs and that seen in other species suggests that the canine thymus is likely to demonstrate the same the same multi-phasic involution observed in other vertebrates [34]. Thus adding further to the evidence that the age-related decline of the thymus is an evolutionary conserved event [4].…”

Section: Discussionmentioning

confidence: 99%

An Age-Associated Decline in Thymic Output Differs in Dog Breeds According to Their Longevity

et al. 2016

Self Cite

View full text Add to dashboard Cite

The age associated decline in immune function is preceded in mammals by a reduction in thymic output. Furthermore, there is increasing evidence of a link between immune competence and lifespan. One approach to determining thymic output is to quantify signal joint T cell receptor excision circles (sj-TRECs), a method which has been developed and used in several mammalian species. Life expectancy and the rate of aging vary in dogs depending upon their breed. In this study, we quantified sj-TRECs in blood samples from dogs of selected breeds to determine whether there was a relationship between longevity and thymic output. In Labrador retrievers, a breed with a median expected lifespan of 11 years, there was an age-associated decline in sj-TREC values, with the greatest decline occurring before 5 years of age, but with sj-TREC still detectable in some geriatric animals, over 13 years of age. In large short-lived breeds (Burnese mountain dogs, Great Danes and Dogue de Bordeaux), the decline in sj-TREC values began earlier in life, compared with small long-lived breeds (Jack Russell terriers and Yorkshire terriers), and the presence of animals with undetectable sj-TRECs occurred at a younger age in the short-lived breeds. The study findings suggest that age-associated changes in canine sj-TRECs are related to breed differences in longevity, and this research highlights the use of dogs as a potential model of immunosenescence.

show abstract

It’s not all equal: a multiphasic theory of thymic involution

Cited by 22 publications

References 40 publications

The Effect of Age on Thymic Function

The Effect of Age on Thymic Function

Thymic Maturation and Programmed Cell Death

An Age-Associated Decline in Thymic Output Differs in Dog Breeds According to Their Longevity

Contact Info

Product

Resources

About