Department of Medicine, National Jewish Health, Denver, Colorado, USA.
The Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA.
Thorax. 2020 Sep;75(9):717-724. doi: 10.1136/thoraxjnl-2019-214158. Epub 2020 Jun 4.
Parkin (Park2), an E3 ubiquitin ligase, is critical to maintain mitochondrial function by regulating mitochondrial biogenesis and degradation (mitophagy), but recent evidence suggests the involvement of Parkin in promoting inflammation. In the present study, we determined if Parkin regulates airway mitochondrial DNA (mtDNA) release and inflammatory responses to type 2 cytokine interleukin (IL)-13 and allergens.
We measured Parkin mRNA expression in brushed bronchial epithelial cells and mtDNA release in the paired bronchoalveolar lavage fluid (BALF) from normal subjects and asthmatics. Parkin-deficient primary human tracheobronchial epithelial (HTBE) cells generated using the CRISPR-Cas9 system were stimulated with IL-13. To determine the function of Parkin, Parkin knockout (PKO) and wild-type (WT) mice were treated with IL-13 or allergen (house dust mite, HDM) in the presence or absence of mtDNA isolated from normal mouse lungs.
Parkin mRNA expression in asthmatic airway epithelium was upregulated, which positively correlated with the levels of released mtDNA in BALF. IL-13-stimulated HTBE cells increased Parkin expression. Moreover, IL-13 induced mtDNA release in Parkin-sufficient, but not in Parkin-deficient HTBE cells. PKO (vs WT) mice attenuated airway mtDNA release and inflammation following IL-13 or HDM treatments. mtDNA amplified airway inflammation in mice treated with IL-13 or HDM. Notably, Parkin also mediated mtDNA-induced exacerbation of airway inflammation.
Our research findings suggest that Parkin promotes mtDNA release and inflammation in airways, thus improving our understanding of the complex role of Parkin and mitochondrial dysfunction in asthma pathogenesis.
Parkin（Park2）是一种 E3 泛素连接酶，通过调节线粒体生物发生和降解（自噬）对维持线粒体功能至关重要，但最近的证据表明 Parkin 参与了促进炎症的过程。在本研究中，我们确定 Parkin 是否调节气道线粒体 DNA（mtDNA）释放以及对 2 型细胞因子白细胞介素（IL）-13 和过敏原的炎症反应。
我们测量了正常受试者和哮喘患者刷取的支气管上皮细胞中的 Parkin mRNA 表达以及配对支气管肺泡灌洗液（BALF）中的 mtDNA 释放。使用 CRISPR-Cas9 系统生成的 Parkin 缺陷型原代人气管支气管上皮（HTBE）细胞接受 IL-13 刺激。为了确定 Parkin 的功能，Parkin 敲除（PKO）和野生型（WT）小鼠在存在或不存在从正常小鼠肺中分离的 mtDNA 的情况下接受 IL-13 或过敏原（屋尘螨，HDM）处理。
哮喘气道上皮中的 Parkin mRNA 表达上调，与 BALF 中释放的 mtDNA 水平呈正相关。IL-13 刺激 HTBE 细胞增加了 Parkin 的表达。此外，IL-13 诱导 Parkin 充足但 Parkin 缺陷的 HTBE 细胞释放 mtDNA。PKO（与 WT 相比）小鼠减轻了 IL-13 或 HDM 处理后的气道 mtDNA 释放和炎症。扩增的气道 mtDNA 加剧了接受 IL-13 或 HDM 治疗的小鼠的炎症。值得注意的是，Parkin 还介导了 mtDNA 诱导的气道炎症加重。
我们的研究结果表明，Parkin 促进气道中的 mtDNA 释放和炎症，从而加深了我们对 Parkin 和线粒体功能障碍在哮喘发病机制中的复杂作用的理解。
