芳香烃受体
促炎细胞因子
生物
细胞生物学
信号转导
转录因子
PI3K/AKT/mTOR通路
抑制因子
细胞因子
免疫学
生物化学
炎症
基因
作者
Adam Peres,Robert Zamboni,Irah L. King,Joaquı́n Madrenas
标识
DOI:10.1189/jlb.4a0617-218rr
摘要
The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that triggers a broad response, which includes the regulation of proinflammatory cytokine production by monocytes and macrophages. AHR is negatively regulated by a set of genes that it transcriptionally activates, including the AHR repressor (Ahrr) and the cytochrome P450 1 (Cyp1) family, which are critical for preventing exacerbated AHR activity. An imbalance in these regulatory mechanisms has been shown to cause severe defects in lymphoid cells. Therefore, we wanted to assess how AHR activation is regulated in monocytes and macrophages in the context of innate immune responses induced by pathogen-associated molecular patterns (PAMPs). We found that concomitant stimulation of primary human monocytes with PAMPs and the AHR agonist 6-formylindolo(3,2-b)carbazole (FICZ) led to a selective dose-dependent inhibition of Cyp1 family members induction. Two other AHR-dependent genes [Ahrr and NADPH quinone dehydrogenase 1 (Nqo1)] were not affected under these conditions, suggesting a split in the AHR regulation by PAMPs. This down-regulation of Cyp1 family members did not require de novo protein production nor signaling through p38, ERK, or PI3K-Akt-mammalian target of rapamycin (mTOR) pathways. Furthermore, such a split regulation of the AHR response was more apparent in GM-CSF-derived macrophages, a finding corroborated at the functional level by decreased CYP1 activity and decreased proinflammatory cytokine production in response to FICZ and LPS. Collectively, our findings identify a role for pattern recognition receptor (PRR) signaling in regulating the AHR response through selective down-regulation of Cyp1 expression in human monocytes and macrophages.
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