BACKGROUND AMP-activated protein kinase (AMPK) exerts its anti-inflammatory effects by suppressing redox-sensitive nuclear factor kappa B (NF-κB) and pro-inflammatory cytokines including TNF-α. However, it is unclear whether AMPK regulates anti-inflammatory cytokine expressions in the presence of oxidative stress-induced inflammation. We sought to elucidate the mechanisms whereby AMPK regulates inflammatory cytokine expressions under NADPH oxidase (NOX)-induced oxidative stress. METHODS HT-29 human colonic epithelial cells transfected with AMPKα shRNA and mouse models with AMPKα knocked out in epithelial cells (AMPKαfl/fl-Vil-Cre) or macrophages (AMPKαfl/fl-Lyz2-Cre) were used to examine the effects of AMPK and NOX on signaling pathways and cytokine expressions. RESULTS In HT-29 cells, 5-hydroxytryptamine (5-HT)-induced NOX activity was enhanced by AMPKα silencing, and resulted in inflammatory cell death. AMPKα deletion specific for colon epithelial cells (AMPKαfl/fl-Vil-Cre) or macrophages (AMPKαfl/fl-Lyz2-Cre) intensified 5-HT- or dextran sulfate sodium (DSS)-induced upregulations of NOX2, TNF-α, and IL-6, but completely abolished basal and 5-HT- or DSS-induced upregulation of IL-10 in colon epithelium. Furthermore, 5-HT- and DSS-induced changes were accompanied by marked upregulations of increased inflammatory signaling pathways linked to NF-κB, AP-1, and STAT3 transcription factors, and to GATA, a cell fate-directing signaling. In addition, AMPKα deletion significantly fortified 5-HT- or DSS-induced downregulations of cytoprotective signaling pathways (Nrf2, HIF-1α, and KLF4). CONCLUSION Basal AMPKα maintains an anti-inflammatory state by inhibiting NOX, balancing pro-/anti-inflammatory signaling pathways, and directing IL-10 production. When these regulatory roles of AMPK are diminished by oxidative stress, colon epithelium undergoes inflammation despite IL-10 production.

中文翻译：

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AMPK对于IL-10表达以及维持炎症和细胞保护信号之间的平衡至关重要。

背景技术AMP激活的蛋白激酶（AMPK）通过抑制氧化还原敏感的核因子κB（NF-κB）和促炎细胞因子（包括TNF-α）发挥抗炎作用。然而，尚不清楚在氧化应激诱导的炎症存在下，AMPK是否调节抗炎细胞因子的表达。我们试图阐明在NADPH氧化酶（NOX）诱导的氧化应激下AMPK调节炎症细胞因子表达的机制。方法采用AMPKαshRNA转染的HT-29人结肠上皮细胞和在上皮细胞（AMPKαfl/ fl-Vil-Cre）或巨噬细胞（AMPKαfl/ fl-Lyz2-Cre）中敲除的AMPKα小鼠模型来检测AMPK的作用。和NOX在信号通路和细胞因子表达中的作用。结果在HT-29细胞中，AMPKα沉默增强了5-羟色胺（5-HT）诱导的NOX活性，并导致炎性细胞死亡。结肠上皮细胞（AMPKαfl/ fl-Vil-Cre）或巨噬细胞（AMPKαfl/ fl-Lyz2-Cre）特有的AMPKα缺失会增强5-HT-或葡聚糖硫酸钠（DSS）诱导的NOX2，TNF-α和IL-6，但完全消除了结肠上皮中基础和5-HT-或DSS诱导的IL-10上调。此外，5-HT和DSS诱导的变化伴随着与NF-κB，AP-1和STAT3转录因子以及细胞命运指导信号GATA相关的炎性信号通路的明显上调。此外，AMPKα缺失显着增强了5-HT或DSS诱导的细胞保护信号通路（Nrf2，HIF-1α和KLF4）的下调。结论基础AMPKα通过抑制NOX，平衡促炎/抗炎信号通路和指导IL-10的产生来维持抗炎状态。当AMPK的这些调节作用由于氧化应激而减弱时，尽管产生IL-10，结肠上皮也会发生炎症。