Reduced intestinal epithelial mitochondrial function enhances in vitro interleukin-8 production in response to commensal Escherichia coli
Reduced intestinal epithelial mitochondrial function enhances in vitro interleukin-8 production in response to commensal Escherichia coli
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DOI：
10.1007/s00011-018-1172-5
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发表时间：
2018-07
影响因子：
6.7
通讯作者：
A. Saxena;F. Lopes;D. McKay
中科院分区：
文献类型：
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作者：
A. Saxena;F. Lopes;D. McKay
上皮线粒体氧化磷酸化解偶联导致上皮屏障功能降低，其特征为非侵袭性大肠杆菌的内化增加及其跨上皮的易位。我们假设细胞内肠道细菌负荷的增加会激活肠上皮细胞，并有可能促进炎症。体外用二硝基苯酚（DNP）和双水杨酸E处理人结肠来源的上皮细胞系。大肠杆菌（菌株F18，HB 101）引起白细胞介素（IL-8）的产生增加，这在来自细菌的条件培养基、脂多糖或惰性珠粒中未观察到。IL-8应答通过用细胞松弛素-D（阻断F-肌动蛋白重排）、氯喹（阻断吞噬体酸化）和MyD 88抑制剂（阻断TLR信号传导）共处理而被抑制，这与TLR信号传导介导细菌内化后的IL-8合成一致。使用靶向抗氧化剂mitoTEMPO或U 0126阻断ERK 1/2 MAPK信号传导抑制DNP+E。大肠杆菌诱导的IL-8产生。NOD 2（细菌的细胞内传感器）或ATG 16 L1（自噬蛋白）基因的突变是克罗恩病的易感特征，当暴露于DNP +大肠杆菌时，与野生型细胞相比，缺乏这两种蛋白质的上皮细胞显示出IL-8的产生增强。因此，代谢应激干扰正常的上皮-细菌相互作用，导致由于细菌摄取到肠上皮细胞中而增加的IL-8产生：这种潜在的促炎事件在缺乏NOD 2或ATG 16 L1的细胞中增强，这有利于肠上皮细胞内细菌的存活增加。我们推测，通过增加上皮通透性和IL-8的产生，肠上皮细胞中线粒体功能的降低将有助于肠道炎症性疾病的启动、病理生理学和再激活。
Uncoupling of oxidative phosphorylation in epithelial mitochondria results in decreased epithelial barrier function as characterized by increased internalization of non-invasiveEscherichia coliand their translocation across the epithelium. We hypothesized that the increased burden of intracellular commensal bacteria would activate the enterocyte, with the potential to promote inflammation. Treatment of human colon-derived epithelial cell lines in vitro with dinitrophenol (DNP) and commensalE. coli(strains F18, HB101) provoked increased production of interleukin (IL-8), which was not observed with conditioned medium from the bacteria, lipopolysaccharide or inert beads. The IL-8 response was inhibited by co-treatment with cytochalasin-D (blocks F-actin rearrangement), chloroquine (blocks phagosome acidification) and a MyD88 inhibitor (blocks TLR signaling), consistent with TLR-signaling mediating IL-8 synthesis subsequent to bacterial internalization. Use of the mitochondria-targeted antioxidant, mitoTEMPO, or U0126 to block ERK1/2 MAPK signalling inhibited DNP+E. coli-evoked IL-8 production. Mutations in the NOD2 (the intracellular sensor of bacteria) or ATG16L1 (autophagy protein) genes are susceptibility traits for Crohn’s, and epithelia lacking either protein displayed enhanced IL-8 production in comparison to wild-type cells when exposed to DNP +E coli. Thus, metabolic stress perturbs the normal epithelial–bacterial interaction resulting in increased IL-8 production due to uptake of bacteria into the enterocyte: this potentially pro-inflammatory event is enhanced in cells lacking NOD2 or ATG16L1 that favor increased survival of bacteria within the enterocyte. We speculate that by increasing epithelial permeability and IL-8 production, reduced mitochondria function in the enteric epithelium would contribute to the initiation, pathophysiology, and reactivation of inflammatory disease in the gut.