PDF(Pubmed)
Abstract：
Earlier studies from our lab identified endoplasmic reticulum (ER) chaperone BiP/GRP78, an important component of MAM, to be a novel determinant of endothelial cell (EC) dysfunction associated with acute lung injury (ALI). Sigma1R (Sig1R) is another unique ER receptor chaperone that has been identified to associate with BiP/GRP78 at the MAM and is known to be a pluripotent modulator of cellular homeostasis. However, it is unclear if Sig1R also plays a role in regulating the EC inflammation and permeability associated with ALI. Our data using human pulmonary artery endothelial cells (HPAECs) showed that siRNA-mediated knockdown of Sig1R potentiated LPS-induced the expression of proinflammatory molecules ICAM-1, VCAM-1 and IL-8. Consistent with this, Sig1R agonist, PRE-084, known to activate Sig1R by inducing its dissociation from BiP/GRP78, blunted the above response. Notably, PRE-084 failed to blunt LPS-induced inflammatory responses in Sig1R-depleted cells, confirming that the effect of PRE-084 is driven by Sig1R. Furthermore, Sig1R antagonist, NE-100, known to inactivate Sig1R by blocking its dissociation from BiP/GRP78, failed to block LPS-induced inflammatory responses, establishing that dissociation from BiP/GRP78 is required for Sig1R to exert its anti-inflammatory action. Unlike Sig1R, the siRNA-mediated knockdown or Subtilase AB-mediated inactivation of BiP/GRP78 protected against LPS-induced EC inflammation. Interestingly, the protective effect of BiP/GRP78 knockdown or inactivation was abolished in cells that were depleted of Sig1R, confirming that BiP/GRP78 knockdown/inactivation-mediated suppression of EC inflammation is mediated via Sig1R. In view of these findings, we determined the in vivo relevance of Sig1R in a mouse model of sepsis-induced ALI. The intraperitoneal injection of PRE-084 mitigated sepsis-induced ALI, as evidenced by a decrease in ICAM-1, IL-6 levels, lung PMN infiltration, and lung vascular leakage. Together, these data evidence a protective role of Sig1R against endothelial dysfunction associated with ALI and identify it as a viable target in terms of controlling ALI in sepsis.
摘要：
我们实验室的早期研究确定了内质网（ER）伴侣BiP/GRP78，MAM的重要组成部分，成为与急性肺损伤（ALI）相关的内皮细胞（EC）功能障碍的新决定因素。Sigma1R（Sig1R）是另一种独特的ER受体伴侣，已被鉴定为在MAM与BiP/GRP78结合，并且已知是细胞稳态的多能调节剂。然而,目前尚不清楚Sig1R是否也在调节与ALI相关的EC炎症和通透性中发挥作用。我们使用人肺动脉内皮细胞（HPAECs）的数据显示，siRNA介导的Sig1R敲低可增强LPS诱导的促炎分子ICAM-1，VCAM-1和IL-8的表达。与此一致，Sig1R激动剂,已知通过诱导Sig1R从BiP/GRP78解离而激活Sig1R的PRE-084减弱了上述反应。值得注意的是,PRE-084未能减弱LPS诱导的Sig1R耗尽细胞的炎症反应，确认PRE-084的作用是由Sig1R驱动的。此外，Sig1R拮抗剂，NE-100，已知通过阻断其与BiP/GRP78的解离而使Sig1R失活，未能阻断LPS诱导的炎症反应，确定从BiP/GRP78解离是Sig1R发挥其抗炎作用所必需的。不像Sig1R,siRNA介导的敲低或枯草杆菌酶AB介导的BiP/GRP78失活保护免受LPS诱导的EC炎症。有趣的是,BiP/GRP78敲低或失活的保护作用在Sig1R耗尽的细胞中被消除，确认BiP/GRP78敲低/失活介导的EC炎症抑制是经由Sig1R介导的。鉴于这些发现,我们确定了Sig1R在脓毒症诱导的ALI小鼠模型中的体内相关性。腹膜内注射PRE-084减轻了脓毒症诱导的ALI，如ICAM-1，IL-6水平降低所证明，肺PMN浸润，和肺血管渗漏。一起,这些数据证明Sig1R对与ALI相关的内皮功能障碍具有保护作用,并将其确定为控制脓毒症ALI的可行靶标.
