Résumé
Objective:To investigate the effects of Notch1 signaling on histone acetylation of Foxp3 gene and its roles in regulating regulatory T (Treg) cells in children with acute B-cell precursor lymphoblastic leukemia (BCP-ALL).Methods:Blood samples were collected form 38 children with BCP-ALL before treatment and 15 age-matched healthy children (control group). Flow cytometry was performed to detect the proportion of peripheral blood CD4 + CD25 hiFoxp3 + Treg cells and the expression of Foxp3, cytotoxic lymphocyte antigen 4 (CTLA4), glucocorticoid-induced tumor necrosis factor receptor (GITR), CD39 and Notch1 at protein level. Histone 4 acetylation (H4Ac) at Foxp3 gene promoter and the binding abilities of Foxp3 gene promoter to NICD1 and p300 in CD4 + T cells were measured by chromatin immunoprecipitation. Quantitative real-time PCR was performed to detect the expression of Foxp3, presenilin 1 (PSEN1), mastermind-like transcriptional coactivator 1 (MAML1), SKI-interacting protein (SKIP), F-box and WD40 domain protein 7 (FBXW7), glycogen synthase kinase-3 beta (GSK3β) and IKAROS at mRNA level in CD4 + T cells. The concentrations of TGF-β and IL-10 in plasma were evaluated by ELISA. Results:(1) The proportion of peripheral blood CD4 + CD25 hiFoxp3 + Treg cells, the expression of differentiation- and function-associated molecules (Foxp3, CTLA4, GITR and CD39) and the concentrations of TGF-β and IL-10 in plasma were higher in the BCP-ALL group than in the control group ( P<0.05). (2) In children with acute BCP-ALL, H4Ac at Foxp3 promoter and the binding abilities of Foxp3 gene promoter to NICD1 and p300 were significantly increased as compared with those in control group( P<0.05). The binding abilities of Foxp3 gene promoter to NICD1 and p300 were positively correlated with the expression of Foxp3 at mRNA level ( r=0.58 and 0.46, both P<0.05). After competitive inhibition, the three aforementioned indexes in the acute BCP-ALL group were significantly lower than those in untreated group ( P<0.05); the binding ability of Foxp3 gene promoter to NICD1 in the control group was also significantly lower than that in untreated control group ( P<0.05), but no statistical differences in the other two indexes were found between the control groups with or without treatment ( P>0.05). ⑶ Compared with the control group, the expression of Notch1, PSEN1, MAML1 and SKIP in CD4 + T cells were elevated significantly ( P<0.05), while the transcription level of negative regulatory factor FBXW7 was decreased remarkably in children with acute BCP-ALL ( P<0.05). No statistical differences in the expression of GSK3β or IKAROS were found between the two groups ( P>0.05). Conclusions:Overactivation of Notch1 signaling caused by low expression of FBXW7 might be the key factor resulting in histone 4 hyperacetylation at foxp3 gene promoter and Treg cell dysfunction in children with acute BCP-ALL.
Résumé
Objective To investigate the changes of CD4 +CD25highFoxp3 +regulatory T (Treg) cells and their significance in immune escape of childhood B-cell acute lymphocytic leukemia ( B-ALL ) . Methods Forty-two children with B-ALL and twenty-eight age-matched healthy children were enrolled in this study.Flow cytometry analysis was performed to evaluate the proportion of CD 4 +CD25high Foxp3 +Treg cells as well as CD4 +CD25high ICOS+Foxp3 +and CD4 +CD25high ICOS-Foxp3 +subsets in peripheral blood samples.The expression of associated molecules including IL-10, TGF-β, IL-35, TGF-βRII, ICOS and CD28 at protein level were also measured by flow cytometry analysis .The transcription level of Smad3/4, TIEG1 and Itch by CD4 +T cells were determined by quantitative real-time PCR.The concentration of TGF-βin plasma was detected by enzyme-linked immunosorbent assay.Results (1)The proportion of CD4 +CD25highFoxp3 +Treg cells in children with B-ALL were significantly higher than those of health subjects (P0.05).(3)The concentra-tion of TGF-βin plasma from children with B-ALL were higher than those from control group [ ( 25 .83 ± 12.65) ng/ml vs (8.59 ±5.73) ng/ml, P<0.05].The expression of TGF-βRII and its associated mole-cules (Smad3/4, TIEG1 and Itch) by CD4 +T cells were significantly up-regulated.Moreover, an increased expression of ICOS and CD28 by CD4 +CD25highFoxp3 +Treg cells were also observed in children with B-ALL (P<0.05).Conclusion The hyper-activity of TGF-β, ICOS and CD28 signaling might be closely associ-ated with the increased proportion of CD4 +CD25high Foxp3 +Treg cells and the imbalance of its subsets in children with B-ALL.
Résumé
Guided by the study theory of constructivism,we utilize informational environment and resource to design the teaching of “nursing of mental disorders who abuse psychoactive substances”,change teaching methods divorced from reality,advocate situation teaching,recommend student' s initiative and cooperative study and improve the students' practical and innovative ability.