Thymic Regeneration in Mice and Humans Following Sex Steroid Ablation

Fletcher, Anne; Reiseger, Jessica Jane; Vlahos, Katerina; Seach, Natalie Louise; Dudakov, Jarrod A; Chidgey, Ann Patricia; Boyd, Richard

doi:10.1007/978-1-4020-9063-9_74

Cited by 1 publication

(3 citation statements)

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“…A comparable age-related decrease in the thymic weight in Ox and control rats, with a less pronounced decline of the thymocyte number in Ox rats, strongly suggested a more profound loss of stromal tissue in these rats. Considering that the thymic atrophy is initiated in the thymic stromal cells, 23 the previous observation may be taken as indicative of the age-related thymic involution. To further clarify the role of stromal changes in thymic involution, we measured pan-cytokeratin+ area in thymic sections of both Ox and control rats.…”

Section: Discussionmentioning

confidence: 99%

“…55 The changes in the most immature thymocyte subpopulations from Ox rats are in keeping with the data indicating that, although thymic atrophy is initiated in thymic stromal cells, thymic regeneration requires some direct effects on thymocytes and/or thymocyte bone marrow precursors, most likely a positive feedback loop which requires expansion of progenitors and downstream thymocytes in order to expand stromal cells. 23 Moreover, considering changes in thymocyte apoptosis, it may be speculated that a diminished thymocyte apoptosis contributed to the unaltered numbers of the most mature thymocytes in two-month-old Ox rats. The unaltered frequency of TN cell descendants, i.e.…”

Section: Discussionmentioning

confidence: 99%

“…This seems to be particularly important in light of numerous experimental attempts to prevent or diminish the undesirable effect of thymic involution on immune system. 23 Therefore, in this study, we examined the influence of ovarian hormones on rat thymus size and, in particular, T-cell differentiation/maturation reshaping from peripubertal to middle-age, in detail. The study included hormonally replete 1-month-old (immature), immunologically and sexually mature 2-month-old (young adult) 24 and 11-month-old (middle-aged) rats showing clear signs of reproductive ageing, 22 as well as adult age-matched rats Ox at the age of 1 month.…”

Section: Introductionmentioning

confidence: 99%

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Ovarian hormone withdrawal in prepubertal developmental stage does not prevent thymic involution in rats

Arsenović-Ranin

Perišić

Bufan

et al. 2013

Exp Biol Med (Maywood)

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The study was undertaken to assess the effects of ovarian hormone withdrawal in prepubertal age on thymopoiesis in 2- (young) and 11-month-old (middle-aged) rats. In ovariectomized (Ox) rats, irrespective of age, thymic weight and cellularity were greater than in age-matched controls, but the values of both parameters exhibited the age-related decline. In addition, although thymopoietic efficiency was increased in both groups of Ox rats when compared with age-matched controls, thymopoiesis exhibited the age-related decline mirrored in the lower numbers of both CD4+ and CD8+ recent thymic emigrants in peripheral blood. This reflected the prethymic changes affecting bone marrow progenitor generation/entry and the thymic alterations encompassing the impaired progenitor progression through early pre-T-cell receptor developmental stages (defined by CD45RC/CD2 expression) and, possibly, a more pronounced decrease in the proliferation of the most mature thymocytes. Apart from the changes at thymocyte level, in Ox rats the age-related alterations in thymic stroma (substantiated in a prominent loss of thymic epithelial cells) were registered. Ovariectomy-induced changes in thymic lymphoid and epithelial component, most probably, influenced each other leading to the increase in thymic expression of interleukin-6 and interleukin-7 mRNAs along with time after ovariectomy. Collectively, the study showed that the withdrawal of ovarian hormones in prepubertal age increases the efficiency of thymopoiesis in young adult rats, but does not prevent decline in thymopoiesis occurring with age.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%