Acid Sphingomyelinase Promotes Endothelial Stress Response in Systemic Inflammation and Sepsis
Acid Sphingomyelinase Promotes Endothelial Stress Response in Systemic Inflammation and Sepsis
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DOI：
10.2119/molmed.2016.00140
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发表时间：
2016-01-01
影响因子：
5.7
通讯作者：
Claus, Ralf A.
中科院分区：
文献类型：
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作者：
Chung, Ha-Yeun;Hupe, Daniel C.;Claus, Ralf A.
脓毒症的病理生理学涉及酸性鞘磷脂酶（SMPD 1）的激活，随后产生生物活性介质神经酰胺。我们在此评估的假设，酶发挥生物学效应，在内皮细胞的应激反应。用脓毒症患者血清刺激人微循环内皮细胞（HMEC-1），测定血浆分泌的鞘磷脂酶活性、神经酰胺生成和脂筏形成。通过免疫染色研究与信号转导相关的受体的聚集。通过药理学抑制测试SMPD 1对于宏域形成的作用。为了证实应激酶的参与，检测了ADAMTS 13表达和细胞毒性方面的直接抑制剂（氨基二膦酸盐）和基因的特异性下调。脓毒症患者的血浆SMPD 1活性和量增加，取决于临床严重程度。在体外用脓毒症患者的血清刺激后，观察到HMEC中鞘磷脂分解为神经酰胺的增加。使用功能性抑制剂（地昔帕明和NB 6）消除了鞘磷脂的水解、受体复合物（如CD 95 L/Fas受体）的聚集以及神经酰胺富集的大结构域的形成。引人注目的是，用从脓毒症患者获得的血清或促炎细胞因子的混合物刺激HMEC导致细胞毒性和ADAMTS 13下调，其使用地昔帕明、氨基二膦酸盐和遗传抑制剂被废除。SMPD 1参与内皮细胞中神经酰胺代谢的失调，导致大结构域形成、细胞毒性和ADAMTS 13表达的下调。功能性抑制剂，如地昔帕明，能够改善脓毒症期间的内皮应激反应，并可能被认为是一种获得良好结局的药物治疗策略。
The pathophysiology of sepsis involves activation of acid sphingomyelinase (SMPD1) with subsequent generation of the bioactive mediator ceramide. We herein evaluate the hypothesis that the enzyme exerts biological effects in endothelial stress response. Plasma-secreted sphingomyelinase activity, ceramide generation and lipid raft formation were measured in human microcirculatory endothelial cells (HMEC-1) stimulated with serum obtained from sepsis patients. Clustering of receptors relevant for signal transduction was studied by immunostaining. The role of SMPD1 for macrodomain formation was tested by pharmacological inhibition. To confirm the involvement of the stress enzyme, direct inhibitors (amino bisphosphonates) and specific downregulation of the gene was tested with respect to ADAMTS13 expression and cytotoxicity. Plasma activity and amount of SMPD1 were increased in septic patients dependent on clinical severity. Increased breakdown of sphingomyelin to ceramide in HMECs was observed following stimulation with serum from sepsis patients in vitro. Hydrolysis of sphingomyelin, clustering of receptor complexes, such as the CD95L/Fas-receptor, as well as formation of ceramide enriched macrodomains were abrogated using functional inhibitors (desipramine and NB6). Strikingly, the stimulation of HMECs with serum obtained from sepsis patients or mixture of proinflammatory cytokines resulted in cytotoxicity and ADAMTS13 downregulation which was abrogated using desipramine, amino bisphosphonates and genetic inhibitors. SMPD1 is involved in the dysregulation of ceramide metabolism in endothelial cells leading to macrodomain formation, cytotoxicity and downregulation of ADAMTS13 expression. Functional inhibitors, such as desipramine, are capable of improving endothelial stress response during sepsis and might be considered as a pharmacological treatment strategy to obtain a favorable outcome.