Innate Immune Regulation by HSF1 in Liver Inflammatory Injury

项目摘要 肝脏缺血再灌注损伤（IRI）是一种先天免疫优势的局部无菌性炎症反应， 肝移植、肝切除和出血性肝损伤后肝功能障碍和肝功能衰竭的主要原因 冲击.氧化应激已被认为是肝脏IRI发病机制的重要因素，其中 IR激活肝脏巨噬细胞（枯否细胞）产生活性氧（ROS），导致无菌性 肝脏的炎症ROS是一种内源性的“危险”信号，可以从坏死或应激中释放出来。 细胞以触发NLRP 3炎性体活化。最近的研究表明，NLRP 3的激活 炎性小体需要ROS依赖性NEK 7，一种参与有丝分裂细胞分裂的丝氨酸-苏氨酸激酶。 NEK 7直接与NLRP 3结合并促进炎症反应，这表明NEK 7是一种重要的免疫调节因子。 在炎症反应期间，免疫调节剂触发先天免疫。已经表明， 抗氧化防御系统防止ROS诱导的肝损伤，而NLRP 3衔接蛋白的破坏 ASC减少肝脏IRI中的炎症反应。此外，骨髓特异性HSF 1敲除小鼠（HSF 1 M-1）的骨髓特异性HSF 1基因敲除小鼠（HSF 1 M-1）的骨髓特异 KO）增强NLRP 3功能，并通过转录激活加重IR诱导的肝损伤 因子X-box结合蛋白（XBP 1）。最终，HSF 1激活增加β-连环蛋白活性，导致 减少ROS产生和NLRP 3活化。尽管这些结果指向HSF 1-β-连环蛋白轴 HSF 1作为肝脏炎症损伤中天然免疫的一个新的主开关， 调节NEK 7功能，导致响应IR诱导的应激的NLRP 3活化减少。的 TLR 4/TRAF 6轴介导NOX 2依赖性ROS的产生，这对于激活 TXNIP。TLR信号传导可以与转化生长因子β激活的激酶1（TAK 1）相互作用， NEK 7的活化促进NLRP 3炎性体途径。因此，TXNIP 和TAK 1可能是必需的HSF 1介导的调节NEK 7功能，在肝脏 炎性损伤这项提案的总体目标是剖析的功能和分子机制， IR应激肝脏中NEK 7功能的HSF 1依赖性调节。假设HSF 1调节 在肝IRI中NEK 7介导的先天免疫应答通过：1）控制TAK 1活性;和2）抑制 TXNIP激活。为了检验这一假设，提出了以下具体目标： 其中HSF 1控制IR应激肝脏中的TAK 1-NEK 7相互作用;和ii）确定 HSF 1调节IR应激肝脏中的TXNIP-NEK 7轴。这些研究将增加对 IR诱导肝脏炎症中先天免疫的肝脏调节网络。这些发现也将对 对器官移植和其他器官移植中缺血性组织损伤的治疗调节的影响 不育性炎症疾病状态。

PROJECT SUMMARY Liver ischemia and reperfusion injury (IRI), an innate immunity-dominant local sterile inflammatory response, is a major cause for hepatic dysfunction and failure following liver transplantation, resection, and hemorrhagic shock. Oxidative stress has been recognized as an important factor in the pathogenesis of hepatic IRI, in which IR activates liver macrophages (Kupffer cells) to generate reactive oxygen species (ROS), leading to sterile inflammation in the liver. ROS is an endogenous `danger' signal and can be released from necrotic or stressed cells to trigger NLRP3 inflammasome activation. Recent study revealed that activation of the NLRP3 inflammasome required ROS-dependent NEK7, a serine-threonine kinase involved in mitotic cell division. NEK7 directly binds to NLRP3 and promotes inflammatory response, suggesting that NEK7 is an essential mediator to trigger innate immunity during inflammatory response. It has been shown that activation of antioxidant defense system prevents ROS-induced liver damage whereas disruption of NLRP3 adaptor protein ASC reduces inflammatory response in liver IRI. Moreover, mice with myeloid-specific HSF1 knockout (HSF1M- KO) enhanced NLRP3 functions and exacerbated IR-induced liver damage through activation of transcription factor X-box-binding protein (XBP1). Ultimately, HSF1 activation increased β-catenin activity leading to reduced ROS production and NLRP3 activation. Although these results point towards the HSF1-β-catenin axis as a novel master-switch of innate immunity in liver inflammatory injury, it remains unknown how HSF1 modulates NEK7 function leading to reduced NLRP3 activation in response to IR-induced stress. The TLR4/TRAF6 axis mediates the NOX2-dependent production of ROS, which is crucial for the activation of TXNIP. TLR signaling can interact with transforming growth factor β-activated kinase 1 (TAK1) to initiate inflammatory cascade whereas activation of NEK7 promotes NLRP3 inflammasome pathway. Thus, TXNIP and TAK1 are likely to be essential for the HSF1-mediated regulation of NEK7 functions during liver inflammatory injury. The overall goal of this proposal is to dissect the functions and molecular mechanisms of HSF1-dependent regulation of NEK7 function in IR-stressed livers. The hypothesis is that HSF1 regulates NEK7-mediated innate immune responses in hepatic IRI by: 1) controlling TAK1 activity; and 2) inhibiting TXNIP activation. To test this hypothesis, the following specific aims are proposed: i) dissect mechanisms by which HSF1 controls the TAK1-NEK7 interaction in IR-stressed liver; and ii) determine mechanisms by which HSF1 regulates the TXNIP-NEK7 axis in IR-stressed liver. These studies will increase the understanding of the hepatic regulatory network of innate immunity in IR-induced liver inflammation. These findings will also have far reaching implications for therapeutic modulation of ischemic tissue damage in organ transplantation and other sterile inflammatory disease states.