RESUMO
BACKGROUND: Autoimmune diseases are a class of diseases that cause a strong immune response to the continuous lack of self-tissue-specific antigens in the thymus. Hypothyroidism and unstable expression of tissue-specific antigens in the thymus can limit the therapeutic effect. The thymus is mainly composed of thymic epithelial cells, but the limited number of mature thymic epithelial cells and thymic epithelial progenitor cells in the thymus has greatly limited related research. OBJECTIVE: To detect the expression of autoimmune regulator (AIRE) when mouse embryonic stem cells were transformed into thymic epithelial progenitor cells. METHODS: A two-step differentiation method was used to induce the differentiation of mouse embryonic stem cells into endoderm and then into thymic epithelial progenitor cells. The cells were collected at 0, 3, and 13 days of induced differentiation. Immunofluorescence, flow cytometry, western blot and real-time PCR were used to detect the expression of cell-associated genes and proteins. RESULTS AND CONCLUSION: Positive expression of OCT4 and SSEA1 was detected by immunofluorescence at 0 day of induction. The double positive expression of SOX17 and FoxA2 was measured by immunofluorescence at 3 days of induction. The positive expression of EpCAM, K5 and K8 were analyzed by flow cytometry at 13 days of induction. During the directional differentiation of mouse embryonic stem cells, real-time PCR indicated that the expression of PAX1, PAX9, FOXN1 and PLET1 showed an increasing trend. The expression of AIRE gene increased significantly at 0, 3, and 13 days of induction. At the same time, the expression of INS2 gene and GAD67 gene also increased. Western blot assay showed that the expression of AIRE protein gradually decreased at 0, 3, and 13 days of induction; however, insulin protein and GAD67 protein were not detected. Overall findings indicate that mouse embryonic stem cells can successfully differentiate into thymic epithelial progenitor cells with highly expressed AIRE gene, which promotes the expression of INS2 and GAD67 genes, and provides an evaluation basis for cell transplantation in the treatment of autoimmune diseases.
RESUMO
The thymus is a central lymphoid organ for T cell development. Thymic epithelial cells (TECs) constitute a major component of the thymic stroma, which provides a specialized microenvironment for survival, proliferation, and differentiation of immature T cells. In this study, subsets of TECs were examined immunohistochemically to investigate their cytokeratin (CK) expression patterns during thymus regeneration following thymic involution induced by cyclophosphamide treatment. The results demonstrated that both normal and regenerating mouse thymuses showed a similar CK expression pattern. The major medullary TECs (mTEC) subset, which is stellate in appearance, exhibited CK5 and CK14 staining, and the minor mTEC subset, which is globular in appearance, exhibited CK8 staining, whereas the vast majority of cortical TECs (cTECs) expressed CK8 during thymus regeneration. Remarkably, the levels of CK5 and CK14 expression were enhanced in mTECs, and CK8 expression was upregulated in cTECs during mouse thymus regeneration after cyclophosphamide-induced acute thymic involution. Of special interest, a relatively high number of CK5+CK8+ TEC progenitors occurred in the thymic cortex during thymus regeneration. Taken together, these findings shed more light on the role of CK5, CK8, and CK14 in the physiology of TECs during mouse thymus regeneration, and on the characterization of TEC progenitors for restoration of the epithelial network and for concomitant regeneration of the adult thymus.