Yang Qin, Pröll Maren J, Salilew-Wondim Dessie, Zhang Rui, Tesfaye Dawit, Fan Huitao, Cinar Mehmet U, Große-Brinkhaus Christine, Tholen Ernst, Islam Mohammad A, Hölker Michael, Schellander Karl, Uddin Muhammad J, Neuhoff Christiane
1 Department of Animal Breeding and Husbandry, Institute of Animal Science, University of Bonn, Germany.
2 Department of Basic Medical Sciences, and Purdue Center for Cancer Research, Purdue University, USA.
Innate Immun. 2016 Nov;22(8):682-695. doi: 10.1177/1753425916669418. Epub 2016 Sep 30.
Pulmonary alveolar macrophages (AMs) are important in defense against bacterial lung inflammation. Cluster of differentiation 14 (CD14) is involved in recognizing bacterial lipopolysaccharide (LPS) through MyD88-dependent and TRIF pathways of innate immunity. Sulforaphane (SFN) shows anti-inflammatory activity and suppresses DNA methylation. To identify CD14 epigenetic changes by SFN in the LPS-induced TRIF pathway, an AMs model was investigated in vitro. CD14 gene expression was induced by 5 µg/ml LPS at the time point of 12 h and suppressed by 5 µM SFN. After 12 h of LPS stimulation, gene expression was significantly up-regulated, including TRIF, TRAF6, NF-κB, TRAF3, IRF7, TNF-α, IL-1β, IL-6, and IFN-β. LPS-induced TRAM, TRIF, RIPK1, TRAF3, TNF-α, IL-1β and IFN-β were suppressed by 5 µM SFN. Similarly, DNMT3a expression was increased by LPS but significantly down-regulated by 5 µM SFN. It showed positive correlation of CD14 gene body methylation with in LPS-stimulated AMs, and this methylation status was inhibited by SFN. This study suggests that SFN suppresses CD14 activation in bacterial inflammation through epigenetic regulation of CD14 gene body methylation associated with DNMT3a. The results provide insights into SFN-mediated epigenetic down-regulation of CD14 in LPS-induced TRIF pathway inflammation and may lead to new methods for controlling LPS-induced inflammation in pigs.
肺泡巨噬细胞（AMs）在抵御细菌性肺部炎症中起重要作用。分化簇14（CD14）通过天然免疫的髓样分化因子88（MyD88）依赖途径和TIR结构域衔接蛋白诱导干扰素β（TRIF）途径参与识别细菌脂多糖（LPS）。萝卜硫素（SFN）具有抗炎活性并能抑制DNA甲基化。为了确定SFN在LPS诱导的TRIF途径中对CD14表观遗传变化的影响，在体外研究了AMs模型。在12小时时间点，5μg/ml LPS诱导CD14基因表达，而5μM SFN抑制该表达。LPS刺激12小时后，包括TRIF、肿瘤坏死因子受体相关因子6（TRAF6）、核因子κB（NF-κB）、TRAF3、干扰素调节因子7（IRF7）、肿瘤坏死因子-α（TNF-α）、白细胞介素-1β（IL-1β）、白细胞介素-6（IL-6）和干扰素-β（IFN-β）在内的基因表达显著上调。5μM SFN抑制LPS诱导的TRAM、TRIF、受体相互作用蛋白激酶1（RIPK1）、TRAF3、TNF-α、IL-1β和IFN-β。同样，LPS使DNA甲基转移酶3a（DNMT3a）表达增加，但5μM SFN使其显著下调。结果显示，在LPS刺激的AMs中，CD14基因体甲基化呈正相关，且这种甲基化状态被SFN抑制。本研究表明，SFN通过对与DNMT3a相关的CD14基因体甲基化进行表观遗传调控，在细菌性炎症中抑制CD14激活。这些结果为SFN介导的LPS诱导的TRIF途径炎症中CD14表观遗传下调提供了见解，并可能为控制猪LPS诱导炎症带来新方法。
