Endothelial cell tolerance to lipopolysaccharide challenge is induced by monophosphoryl lipid A.
Endothelial cell tolerance to lipopolysaccharide challenge is induced by monophosphoryl lipid A.
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DOI：
10.1042/cs20150592
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发表时间：
2016-03
期刊：
影响因子：
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通讯作者：
Sherwood ER
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文献类型：
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作者：
Stark RJ;Choi H;Koch SR;Fensterheim BA;Lamb FS;Sherwood ER
先前暴露于脂多糖（LPS）对随后的LPS攻击产生降低的或“耐受的”炎症反应，然而LPS的强效促炎作用限制了其临床益处。佐剂单磷酰脂质A（MPLA）是一种弱的Toll样受体4（TLR 4）激动剂，其诱导的炎症可忽略不计，但保留了有效的免疫调节特性。我们推测用MPLA预处理可以抑制内皮细胞对二次LPS刺激的炎症反应。将人脐静脉内皮细胞（HUVEC）暴露于MPLA（10 μg/ml）、LPS（100 ng/ml）或溶媒对照。然后洗涤HUVEC并在培养物中保持24小时，然后用LPS（100 ng/ml）攻击。收集上清液，并在存在或不存在关键TLR 4信号传导蛋白的siRNA抑制剂的情况下检查细胞因子的产生。用MPLA预处理减弱了IL-6的产生，以与LPS相似的程度进行第二次LPS攻击。MyD 88 siRNA的应用显著降低了MPLA诱导的耐受性，而TRIF siRNA没有效果。内皮细胞中的耐受表型与LPS致敏的HUVECs中IKK、p38和JNK磷酸化减少和IRAK-M表达增强相关，但在MPLA致敏的细胞中则较少。相反，MPLA引发的HUVEC表现出增强的ERK磷酸化。与耐受性主要依赖于TRIF的白细胞相反，MyD 88信号传导介导内皮细胞中的内毒素耐受性。最重要的是，MPLA，一种具有宽治疗窗的疫苗佐剂，诱导内皮细胞对LPS的耐受。
Prior exposure to lipopolysaccharide (LPS) produces a reduced or “tolerant” inflammatory response to subsequent challenges with LPS, however the potent pro-inflammatory effects of LPS limit its clinical benefit. The adjuvant Monophosphoryl lipid A (MPLA) is a weak toll-like receptor 4 (TLR4) agonist that induces negligible inflammation but retains potent immunomodulatory properties. We postulated that pre-treatment with MPLA would inhibit the inflammatory response of endothelial cells to secondary LPS challenge. Human umbilical vein endothelial cells (HUVECs), were exposed to MPLA (10 µg/ml), LPS (100 ng/ml) or vehicle control. HUVECs were then washed and maintained in culture for 24 hours before being challenged with LPS (100 ng/ml). Supernatants were collected and examined for cytokine production in the presence or absence of siRNA inhibitors of critical TLR4 signaling proteins. Pretreatment with MPLA attenuated IL-6 production to secondary LPS challenge to a similar degree as LPS. The application of MyD88 siRNA dramatically reduced MPLA-induced tolerance while TRIF siRNA had no effect. The tolerant phenotype in endothelial cells was associated with reduced IKK, p38 and JNK phosphorylation and enhanced IRAK-M expression for LPS primed HUVECs, but less so in MPLA primed cells. Instead, MPLA-primed HUVECs demonstrated enhanced ERK phosphorylation. In contrast to leukocytes in which tolerance is largely TRIF-dependent, MyD88 signaling mediated endotoxin tolerance in endothelial cells. Most importantly, MPLA, a vaccine adjuvant with a wide therapeutic window, induced tolerance to LPS in endothelial cells.