TY - JOUR
T1 - Central tolerance is impaired in the middle-aged thymic environment
AU - Lancaster, Jessica N.
AU - Keatinge-Clay, Damaris E.
AU - Srinivasan, Jayashree
AU - Li, Yu
AU - Selden, Hilary J.
AU - Nam, Seohee
AU - Richie, Ellen R.
AU - Ehrlich, Lauren I.R.
N1 - Publisher Copyright:
© 2022 The Authors. Aging Cell published by Anatomical Society and John Wiley & Sons Ltd.
PY - 2022/6
Y1 - 2022/6
N2 - One of the earliest hallmarks of immune aging is thymus involution, which not only reduces the number of newly generated and exported T cells, but also alters the composition and organization of the thymus microenvironment. Thymic T-cell export continues into adulthood, yet the impact of thymus involution on the quality of newly generated T-cell clones is not well established. Notably, the number and proportion of medullary thymic epithelial cells (mTECs) and expression of tissue-restricted antigens (TRAs) decline with age, suggesting the involuting thymus may not promote efficient central tolerance. Here, we demonstrate that the middle-aged thymic environment does not support rapid motility of medullary thymocytes, potentially diminishing their ability to scan antigen presenting cells (APCs) that display the diverse self-antigens that induce central tolerance. Consistent with this possibility, thymic slice assays reveal that the middle-aged thymic environment does not support efficient negative selection or regulatory T-cell (Treg) induction of thymocytes responsive to either TRAs or ubiquitous self-antigens. This decline in central tolerance is not universal, but instead impacts lower-avidity self-antigens that are either less abundant or bind to TCRs with moderate affinities. Additionally, the decline in thymic tolerance by middle age is accompanied by both a reduction in mTECs and hematopoietic APC subsets that cooperate to drive central tolerance. Thus, age-associated changes in the thymic environment result in impaired central tolerance against moderate-avidity self-antigens, potentially resulting in export of increasingly autoreactive naive T cells, with a deficit of Treg counterparts by middle age.
AB - One of the earliest hallmarks of immune aging is thymus involution, which not only reduces the number of newly generated and exported T cells, but also alters the composition and organization of the thymus microenvironment. Thymic T-cell export continues into adulthood, yet the impact of thymus involution on the quality of newly generated T-cell clones is not well established. Notably, the number and proportion of medullary thymic epithelial cells (mTECs) and expression of tissue-restricted antigens (TRAs) decline with age, suggesting the involuting thymus may not promote efficient central tolerance. Here, we demonstrate that the middle-aged thymic environment does not support rapid motility of medullary thymocytes, potentially diminishing their ability to scan antigen presenting cells (APCs) that display the diverse self-antigens that induce central tolerance. Consistent with this possibility, thymic slice assays reveal that the middle-aged thymic environment does not support efficient negative selection or regulatory T-cell (Treg) induction of thymocytes responsive to either TRAs or ubiquitous self-antigens. This decline in central tolerance is not universal, but instead impacts lower-avidity self-antigens that are either less abundant or bind to TCRs with moderate affinities. Additionally, the decline in thymic tolerance by middle age is accompanied by both a reduction in mTECs and hematopoietic APC subsets that cooperate to drive central tolerance. Thus, age-associated changes in the thymic environment result in impaired central tolerance against moderate-avidity self-antigens, potentially resulting in export of increasingly autoreactive naive T cells, with a deficit of Treg counterparts by middle age.
KW - T cell
KW - cellular immunology
KW - central tolerance
KW - immune aging
KW - thymus involution
UR - http://www.scopus.com/inward/record.url?scp=85129840829&partnerID=8YFLogxK
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U2 - 10.1111/acel.13624
DO - 10.1111/acel.13624
M3 - Article
C2 - 35561351
AN - SCOPUS:85129840829
SN - 1474-9718
VL - 21
JO - Aging Cell
JF - Aging Cell
IS - 6
M1 - e13624
ER -