About this Research Topic
The thymus is the primary lymphoid organ specialized in the development of a diverse repertoire of non-self-reactive T lymphocytes. Thymic epithelial cells represent the main cell type devoted to the development, as well as the positive and negative selection of thymocytes. In order for T cells to be properly selected, they need to interact with highly specialized subsets of thymic epithelial cells both in the cortex and medulla of the thymus. On the other hand, to fully mature and differentiate in all the specific subpopulations, thymic epithelial cells need to interact with thymocytes. This interaction between thymocytes and thymic epithelial cells is called thymic cross-talk and is critical for the correct function of both cell populations. For this reason, genetic defects or injuries causing the lack or malfunctioning of the thymic cross-talk result in defective T cell development and ultimately lead to immunodeficiency or immune-dysregulation. A thorough understanding of all the molecules and pathways involved in the thymic crosstalk would thus shed new light on the biology of thymic epithelial cells and T lymphocytes and form the basis for the development of innovative therapies for the treatment of thymic-derived immune defects.
While hematopoietic-intrinsic defects have been well characterized throughout the years, the study of thymic epithelial cells has been more complex, particularly in humans. This is due to the low number of these cells in the thymus and the difficulty in isolating them from the thymic tissue without altering their features. For these reasons, the majority of the knowledge gained on thymic epithelial cells comes from mouse models carrying mutations in genes that are critical for the function of these cells. However, more recently, the use of newborn screening and next generation sequencing for the diagnosis of genetic diseases has brought to light several new genes that are critical for the thymic epithelial cells’ function. Additionally, the development of novel techniques allowing for the study of cells in situ, or for high throughput studies with a limited number of cells (e.g. single cell RNAseq), has given the field of thymic epithelial biology a tremendous boost.
This Research Topic aims at reporting new insights on thymic epithelial cell development and function, focusing in particular on their phenotypic and molecular characterization. We welcome Review and Original Research articles reporting recent efforts in the study of thymic epithelial cells, both in humans and mouse models. Studies using imaging and next generation gene expression techniques will be particularly welcome. Potential topics include, but are not limited to, the following subtopics:
1. Studies on mouse models of diseases involving thymic epithelial cells
2. Studies on human thymic epithelial cells from normal donors and patients with primary and secondary thymic defects
Keywords: thymus, thymic epithelial cells, immunodeficiency, immune dysregulation
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