共 53 条
Treatment of mice with 2,3,7,8-tetrachlorodibenzo-p-dioxin leads to aryl hydrocarbon receptor-dependent nuclear translocation of NF-κB and expression of Fas ligand in thymic stromal cells and consequent apoptosis in T cells
被引:75
作者:
Camacho, IA
Singh, N
Hegde, VL
Nagarkatti, M
Nagarkatti, PS
机构:
[1] Virginia Commonwealth Univ, Med Ctr, Dept Pharmacol & Toxicol, Richmond, VA 23298 USA
[2] Virginia Commonwealth Univ, Med Ctr, Dept Microbiol & Immunol, Richmond, VA 23298 USA
关键词:
D O I:
10.4049/jimmunol.175.1.90
中图分类号:
R392 [医学免疫学];
Q939.91 [免疫学];
学科分类号:
100102 ;
摘要:
We investigated the role of aryl hydrocarbon receptor (AhR) in the regulation of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)induced apoptosis in thymic T cells. AhR knockout (KO) mice were resistant to TCDD-induced thymic atrophy and apoptosis when compared with the AhR wild-type mice. TCDD triggered the expression of several apoptotic genes, including FasL in AhR wild-type but not AhRKO mice. TCDD-induced increase in FasL was seen only in thymic stromal but not thymic T cells. When TCDD-exposed stromal cells were mixed with untreated thymic T cells, increased apoptosis was detected in T cells that involved Fas-FasL interactions. Thus, apoptosis in T cells was not detected when TCDD-treated stromal cells from FasL-defective or AhRKO mice were mixed with wild-type T cells or when TCDD-exposed wild-type stromal cells were mixed with Fas-deficient T cells. TCDD treatment, in vivo and in vitro, led to colocalization and translocation of NF-kappa B subunits (p50, p65) to the nucleus in stromal but not T cells from AhR wild-type mice. NF-kappa B activation was not observed in stromal cells isolated from TCDD-treated AhRKO mice. Mutations in NF-kappa B-binding sites on the FasL promoter showed that TCDD regulates FasL promoter activity through NF-kappa B. TCDD treatment in vivo caused activation of the death receptor and mitochondrial pathways of apoptosis. Cross-talk between the two pathways was not necessary for apoptosis inasmuch as TCDD-treated Bid KO mice showed thymic atrophy and increased apoptosis, similar to the wild-type mice. These findings demonstrate that AhR regulates FasL and NF-kappa B in stromal cells, which in turn plays a critical role in initiating apoptosis in thymic T cells.
引用
收藏
页码:90 / 103
页数:14
相关论文