[promotes thymic cortical regeneration in mice with acute thymic involution induced by short-term rapamycin treatment].
Source: PubMed, NCBI / U.S. National Library of Medicine
To investigate the effect ofon thymic cortical regeneration in rapamycin-treated mice and its underlying mechanisms. The chemical components ofwere analyzed using high-resolution liquid chromatography-mass spectrometry (LC-MS) and ultra-performance liquid chromatography (UPLC). Seventy-two 6-8-week-old female BALB/c mice were randomly assigned by weight into six groups (=12 per group): blank control, model control, normal regeneration, andsmall- (1 g/kg), medium- (2 g/kg), and large-dose (4 g/kg) groups. Except for the blank control group, acute thymic involution was induced in all other groups via intraperitoneal injection of rapamycin (1 mg·kg·d) for 3 consecutive days. After modeling, the-treated groups received oral gavage of corresponding doses for 7 days, while the normal regeneration and blank control groups received an equal volume of saline. Body weight and dorsal hair growth were recorded daily. Forelimb grip strength was measured 2 hours after the last administration. Thymic structure and the spatial distribution of thymic epithelial cells (TECs) and thymocytes were assessed by hematoxylin-eosin (HE) and immunofluorescence staining. Development and homeostasis of T-cell subsets in the thymus and peripheral blood were analyzed by flow cytometry and rapid Wright-Giemsa staining. T-cell receptor excision circles (TRECs) in genomic DNA from peripheral blood mononuclear cells were detected by quantitative PCR (qPCR). The mRNA expression levels of thymic functi
Abstract
To investigate the effect ofon thymic cortical regeneration in rapamycin-treated mice and its underlying mechanisms. The chemical components ofwere analyzed using high-resolution liquid chromatography-mass spectrometry (LC-MS) and ultra-performance liquid chromatography (UPLC). Seventy-two 6-8-week-old female BALB/c mice were randomly assigned by weight into six groups (=12 per group): blank control, model control, normal regeneration, andsmall- (1 g/kg), medium- (2 g/kg), and large-dose (4 g/kg) groups. Except for the blank control group, acute thymic involution was induced in all other groups via intraperitoneal injection of rapamycin (1 mg·kg·d) for 3 consecutive days. After modeling, the-treated groups received oral gavage of corresponding doses for 7 days, while the normal regeneration and blank control groups received an equal volume of saline. Body weight and dorsal hair growth were recorded daily. Forelimb grip strength was measured 2 hours after the last administration. Thymic structure and the spatial distribution of thymic epithelial cells (TECs) and thymocytes were assessed by hematoxylin-eosin (HE) and immunofluorescence staining. Development and homeostasis of T-cell subsets in the thymus and peripheral blood were analyzed by flow cytometry and rapid Wright-Giemsa staining. T-cell receptor excision circles (TRECs) in genomic DNA from peripheral blood mononuclear cells were detected by quantitative PCR (qPCR). The mRNA expression levels of thymic function-related genes, inflammatory factors, and Wnt pathway-related genes were measured by quantitative reverse transcription PCR (qRT-PCR). Potential targets and pathways were screened by integrating network pharmacology prediction and molecular docking. Rapamycin successfully induced acute thymic atrophy. The model control group showed an approximately 50% decrease in thymic index (<0.01), significantly weakened grip strength (<0.05), and no obvious hair regeneration. Histologically, the thymic cortical area was reduced, with a blurred corticomedullary junction, disrupted continuity of the cortical TEC (cTEC) cytoplasmic process network, early-stage blockade of thymocyte development, disturbed spatial distribution, and inhibited thymic output. Compared with the normal regeneration group, medium and large doses ofdose-dependently increased the cortical area, significantly enhanced the density of cortical CK8TECs and restored the continuity of their cytoplasmic process network (<0.01), while upregulating the expression of Foxn1 (<0.01) and its downstream target gene Dll4. Regarding thymocyte development,(large dose) significantly increased the proportion of CD3TCRβthymocytes (<0.05), promoted the balanced differentiation of CD4CD8cells into mature single-positive (SP) thymocytes, and re-established normal spatial localization, manifested as increased density of CD8and CD4CD8cells in the cortex and reaggregation of TCRβcells in the medulla. Furthermore,(medium dose) significantly reduced the mRNA levels of thymic pro-inflammatory factors TNF-α, TGF-β, and IGFBP5 (<0.05), thereby improving the local inflammatory microenvironment. For peripheral homeostasis,intervention maintained and increased the proportion of peripheral blood CD3T cells, elevated the percentage of CD34hematopoietic stem cells across all dosage groups (<0.05), and upregulated the expression of the thymic homing factor Ccl25. Mechanistically, network pharmacology predicted the Wnt pathway as a potential target ofactive components. Experimental validation revealed that(medium dose) significantly upregulated Wnt4 mRNA expression, inhibited Gsk3β, and increased CTNNB1 (β-catenin) levels in the thymus (<0.05), indicating activation of the Wnt/CTNNB1/Foxn1 signaling pathway to drive cTEC cytoskeletal repair and thymic regeneration. promotes cortical regeneration and functional recovery after rapamycin-induced acute thymic involution by activating the Wnt/CTNNB1/Foxn1 signaling pathway and improving the thymic inflammatory microenvironment, which collaboratively facilitate cortical thymic epithelial cell cytoskeletal repair and hematopoietic stem cell homing. This suggests its potential benefit for counteracting immune aging.