ZBP1 可防止 mtDNA 诱导的衰竭心脏中的心肌炎症。

BACKGROUND: Mitochondrial DNA (mtDNA)-induced myocardial inflammation is intimately involved in cardiac remodeling. ZBP1 (Z-DNA binding protein 1) is a pattern recognition receptor positively regulating inflammation in response to mtDNA in inflammatory cells, fibroblasts, and endothelial cells. However, the role of ZBP1 in myocardial inflammation and cardiac remodeling remains unclear. The aim of this study was to elucidate the role of ZBP1 in mtDNA-induced inflammation in cardiomyocytes and failing hearts. METHODS: mtDNA was administrated into isolated cardiomyocytes. Myocardial infarctionwas conducted in wild type and ZBP1 knockout mice. RESULTS: We here found that, unlike in macrophages, ZBP1 knockdown unexpectedly exacerbated mtDNA-induced inflammation such as increases in IL (interleukin)-1β and IL-6, accompanied by increases in RIPK3 (receptor interacting protein kinase 3), phosphorylated NF-κB (nuclear factor-κB), and NLRP3 (nucleotide-binding domain and leucine-rich-repeat family pyrin domain containing 3) in cardiomyocytes. RIPK3 knockdown canceled further increases in phosphorylated NF-κB, NLRP3, IL-1β, and IL-6 by ZBP1 knockdown in cardiomyocytes in response to mtDNA. Furthermore, NF-κB knockdown suppressed such increases in NLRP3, IL-1β, and IL-6 by ZBP1 knockdown in response to mtDNA. CpG-oligodeoxynucleotide, a Toll-like receptor 9 stimulator, increased RIPK3, IL-1β, and IL-6 and ZBP1 knockdown exacerbated them. Dloop, a component of mtDNA, but not and , components of nuclear DNA, was increased in cytosolic fraction from noninfarcted region of mouse hearts after myocardial infarction compared with control hearts. Consistent with this change, ZBP1, RIPK3, phosphorylated NF-κB, NLRP3, IL-1β, and IL-6 were increased in failing hearts. ZBP1 knockout mice exacerbated left ventricular dilatation and dysfunction after myocardial infarction, accompanied by further increases in RIPK3, phosphorylated NF-κB, NLRP3, IL-1β, and IL-6. In histological analysis, ZBP1 knockout increased interstitial fibrosis and myocardial apoptosis in failing hearts. CONCLUSIONS: Our study reveals unexpected protective roles of ZBP1 against cardiac remodeling as an endogenous suppressor of mtDNA-induced myocardial inflammation.

背景：线粒体 DNA（mtDNA）诱导的心肌炎症与心脏重构密切相关。ZBP1（Z-DNA 结合蛋白 1）是一种模式识别受体，可正向调节炎症细胞、成纤维细胞和内皮细胞中 mtDNA 诱导的炎症。然而，ZBP1 在心肌炎症和心脏重构中的作用尚不清楚。本研究旨在阐明 ZBP1 在心肌细胞和衰竭心脏中 mtDNA 诱导的炎症中的作用。

方法：将 mtDNA 给予分离的心肌细胞。在野生型和 ZBP1 敲除小鼠中进行心肌梗死。

结果：与巨噬细胞不同，我们发现，ZBP1 敲低出乎意料地加剧了 mtDNA 诱导的炎症，如白细胞介素（IL）-1β和 IL-6 的增加，同时 RIPK3（受体相互作用蛋白激酶 3）、磷酸化 NF-κB（核因子-κB）和 NLRP3（核苷酸结合域和富含亮氨酸重复家族吡咯烷域包含 3）增加。在 mtDNA 刺激下，RIPK3 敲低可取消 ZBP1 敲低进一步增加的心肌细胞中磷酸化 NF-κB、NLRP3、IL-1β和 IL-6。此外，NF-κB 敲低抑制了 mtDNA 刺激下 ZBP1 敲低引起的 NLRP3、IL-1β 和 IL-6 的增加。CpG-寡脱氧核苷酸，一种 Toll 样受体 9 刺激物，增加了 RIPK3、IL-1β 和 IL-6，而 ZBP1 敲低则加剧了这些作用。与对照组心脏相比，心肌梗死后非梗死区小鼠心脏胞质部分 Dloop（线粒体 DNA 的一个组成部分）增加，而和（核 DNA 的组成部分）则没有增加。与这种变化一致，ZBP1、RIPK3、磷酸化 NF-κB、NLRP3、IL-1β 和 IL-6 在衰竭心脏中增加。ZBP1 敲除小鼠在心肌梗死后左心室扩张和功能障碍加重，同时 RIPK3、磷酸化 NF-κB、NLRP3、IL-1β 和 IL-6 进一步增加。组织学分析显示，ZBP1 敲除增加了衰竭心脏中的间质纤维化和心肌细胞凋亡。

结论：本研究揭示了 ZBP1 作为 mtDNA 诱导的心肌炎症的内源性抑制因子，具有出人意料的保护心脏重构的作用。