Mechanism of pregnancy-induced thymus involution and regeneration and medication rules of postpartum prescriptions / 中国中药杂志

In order to prevent the maternal immune defenses to the semi-allogeneic fetus, the maternal body will present a special adaptive immune system change represented by acute thymic involution(ATI) during pregnancy, which can be quickly regenerated after delivery. The ATI during pregnancy is related to the level of sex hormones, which is mainly caused by progesterone. Pregnancy-induced ATI is manifested as the continuous shrinkage of thymus volume, especially the cortex, and the wrinkle and phagocytosis of the subcapsular cortical thymic epithelial cells(cTECs), while other thymic epithelial cells(TECs) remain unchanged. The postpartum thymus is regenerated by the co-mediation of forkhead box N1(FOXN1) as well as its target genes chemokine(C-C motif) ligand 25(CCL25), chemokine(C-X-C motif) ligand 12(CXCL12), δ-like ligand 4(DLL4), cathepsin L(CTSL), and serine protease 16(PRSS16). Once the postpartum thymus is poorly repaired, immune dysfunction of the maternal body and several puerperal diseases will be induced, seriously endangering the survival of the mother and the newborn. In traditional Chinese medicine(TCM), Qi and blood are the cornerstone of pregnancy, and the thymus plays a key role in regulating Qi and blood. The deficiency of Qi and blood during pregnancy and childbirth is closely related to the abnormal ATI during pregnancy and the poor regeneration of the postpartum thymus. Based on this theory, TCM has profound academic ideas and rich clinical experience in postpartum recuperation. Based on the systematic description of the mechanism of ATI regeneration during pregnancy, as well as data mining and analysis of two classic gynecological works of TCM, Wan's Gynecology and Fu Qing-zhu's Treatise on Gynecology, this study found that the commonly used TCM for postpartum included Angelicae Sinensis Radix, Ginseng Radix et Rhizoma, Glycyrrhizae Radix et Rhizoma, and Chuanxiong Rhizoma. Among them, Ginseng Radix et Rhizoma, Angelicae Sinensis Radix, and Chuanxiong Rhizoma are high-frequency TCMs with positive effects on postpartum recovery.However, the mechanism of these TCMs in promoting postpartum thymus regeneration needs further investigation.

Expression of IL-17A during Thymus Regeneration in the Rat / 체질인류학회지

IL-17A is a pro-inflammatroy cytokine secreted by activated T cells. The IL-17 family consist of IL-17A, IL-17B, IL-17C, IL-17D, IL-17E and IL-17F. IL-17A and IL-17F are produced primarily in activated T cells. In contrast, IL-17B, IL-17C, IL-17D and IL-17E are expressed in a wide assortment of tissues. Their functions partially overlap those of IL-17A, although they have not been as thoroughly investigated. The receptor for IL-17A (IL-17R) is widely expressed in a variety of tissues. IL-17A and IL-17E mRNAs were expressed in only EL4 cells. IL-17C mRNA expression was observed in the thymic subcapsular/cortex epithelial cells (SNEC), cortex or cortical reticular cells (CREC), medullary epithelial cells (MEC), medullary interdigitating-like cells (MDC), thymocytes and EL4 cells. However, IL-17C mRNA was not expressed in RAW 264.7 cells. Immunohistochemical study also demonstrated not only the presence of IL-17A mainly in the thymic epithelial cells, but also the upregulated expression of IL-17A in the thymic epithelial cells of the regenerating thymus. Thus, the results of the present study suggest that IL-17A expressed in the thymocytes and thymic epithelial cells could play an important role in the development of new T cells to replace T cells damaged by cyclophosphamide treatment during thymus regeneration.

Characterization of the expression of cytokeratins 5, 8, and 14 in mouse thymic epithelial cells during thymus regeneration following acute thymic involution / 대한해부학회지

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.

Expression of the p75NTR Neurotrophin Receptor in the Thymic Medullary Epithelial Cells and Interdigitating Dendritic Cells during Rat Thymus Regeneration Following Acute Thymic Involution / 대한해부학회지

The existence of a functional link between the nervous and immune systems has been well established. The present study was to characterize the expression of p75NTR during thymus regeneration from acute involution induced by cyclophosphamide in the rat. Immunohistochemical and double immunofluorescence analyses demonstrated that expression of the p75NTR was decreased in the thymic medullary epithelial cells and interdigitating dendritic cells during thymus regeneration. The presence of p75NTR protein in extracts from the control and regenerating rat thymus was confirmed by western blot. Furthermore, RT-PCR analysis supported these results by demonstrating that thymic extracts contain p75NTR mRNA at lower levels during thymus regeneration. Thus, our results suggest that the p75NTR located on the thymic medullary epithelial cells and interdigitating dendritic cells could play a role in the development of new T cells to replace the thymocytes damaged during thymus regeneration