About this Research Topic
The thymus is an essential organ necessary for supporting the development of T cells throughout life. In this tissue, an individualized repertoire of T cells is formed, dependent on the specificity of T cell receptor (TCR) interactions with self-peptide/MHC complexes. Given such important functions, it is remarkable that the thymus exhibits dramatic variations in size and consequently, T cell output over the lifespan of an individual. For example, the thymus can undergo a transient and sometimes massive reduction in overall size and cellularity, with losses of 90% of developing thymocytes not uncommon. This can ensue following diverse events, including infections, stress coupled to corticosteroid elevations involving the hypothalamus-pituitary-adrenal axis, various chemotherapy treatments, radiation exposure, malnutrition, alcoholism, and pregnancy. Chronic stress often leads to permanent changes in the tissue, reducing the development of helper, cytotoxic and regulatory T cells. In several congenic syndromes including 22q11.2 deletion syndrome (DiGeorge syndrome) and individuals harboring mutations in the Forkhead Box N1 transcription factor (FOXN1) mutations, the thymus may fail to develop entirely, leading to a severe combined immunodeficiency (SCID). The natural aging process also contributes to a gradual and “permanent” hypoplasia of the thymus. This is noted by the substantial adipogenesis and epithelial to mesenchymal transitions in the thymus in elderly people.
The aim of the current Research Topic is to present new findings pertaining to the specification of the thymus, the various stresses and biological responses that modulate thymic functions, and the diverse clinical conditions that impact T cell development. We welcome authors to submit Review and Original Research articles focusing on, but not limited to, the following topics:
1. New approaches to regenerate thymic functions, including thymic organoids for transplant purposes
2. New insights on the specification of the thymus at various stages of life
Keywords: thymopoiesis, T cell development, thymus regeneration, tissue regeneration, thymic hypoplasia
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