Mizumura Kenji, Ozoe Ryosuke, Nemoto Yosuke, Furusho Naho, Kurosawa Yusuke, Kozu Yutaka, Oki Takashi, Maruoka Shuichiro, Gon Yasuhiro
Division of Respiratory Medicine, Department of Internal Medicine, Nihon University School of Medicine, Tokyo, Japan.
Int J Chron Obstruct Pulmon Dis. 2025 Aug 1;20:2685-2695. doi: 10.2147/COPD.S523610. eCollection 2025.
Chronic obstructive pulmonary disease (COPD) is characterized by airway inflammation and structural changes in the lungs, including emphysema. Cigarette smoke exposure induces mitochondrial damage, necroptosis-mediated pulmonary epithelial cell death, and emphysematous changes. However, the association between these events and airway inflammation remains unclear. Here, we focused on mitochondrial DNA (mtDNA) as a second messenger linking mitochondrial damage to airway inflammation, aiming to elucidate the mechanisms underlying extracellular mtDNA release and its role in airway inflammation.
Human bronchial epithelial BEAS-2B cells were exposed to cigarette smoke extract and the release of mtDNA into the cytoplasm and extracellular space was examined. Real-time polymerase chain reaction was used to measure mtDNA levels. To examine the involvement of necroptosis, a necroptosis inhibitor (Nec-1) and mitochondria-targeted antioxidant (MitoQ) were used. To evaluate the inflammatory response induced by extracellular mtDNA, we quantified the levels of specific cytokines-interleukin (IL)-6 and IL-8-in the cell culture supernatants after mtDNA transfection, as these mediators are widely accepted as key markers of inflammation in bronchial epithelial cells.
Cigarette smoke extract treatment induced the translocation of mtDNA from the mitochondria to the cytoplasm in BEAS-2B cells, followed by its extracellular release. Nec-1 and MitoQ inhibited the extracellular release of mtDNA without affecting its cytoplasmic translocation. Introducing mtDNA into BEAS-2B cells markedly elevated IL-6 and IL-8 levels, indicating that mtDNA may play a pro-inflammatory role.
Necroptosis facilitated the release of extracellular mtDNA after cigarette smoke extract exposure, establishing a connection between mitochondrial damage and airway inflammation. mtDNA acted as a pro-inflammatory mediator by inducing cytokine production in pulmonary epithelial cells. These findings suggest that targeting necroptosis could offer a novel therapeutic strategy for COPD by addressing both airway inflammation and structural lung damage.
慢性阻塞性肺疾病（COPD）的特征是气道炎症和肺部结构改变，包括肺气肿。接触香烟烟雾会导致线粒体损伤、坏死性凋亡介导的肺上皮细胞死亡以及肺气肿改变。然而，这些事件与气道炎症之间的关联仍不清楚。在此，我们聚焦于线粒体DNA（mtDNA）作为将线粒体损伤与气道炎症联系起来的第二信使，旨在阐明细胞外mtDNA释放的机制及其在气道炎症中的作用。
将人支气管上皮BEAS - 2B细胞暴露于香烟烟雾提取物中，检测mtDNA向细胞质和细胞外空间的释放。采用实时聚合酶链反应测量mtDNA水平。为了研究坏死性凋亡的参与情况，使用了坏死性凋亡抑制剂（Nec - 1）和线粒体靶向抗氧化剂（MitoQ）。为了评估细胞外mtDNA诱导的炎症反应，我们在mtDNA转染后对细胞培养上清液中特定细胞因子白细胞介素（IL）-6和IL - 8的水平进行了定量，因为这些介质被广泛认为是支气管上皮细胞炎症的关键标志物。
香烟烟雾提取物处理诱导BEAS - 2B细胞中mtDNA从线粒体转运至细胞质，随后释放到细胞外。Nec - 1和MitoQ抑制了mtDNA的细胞外释放，而不影响其向细胞质的转运。将mtDNA导入BEAS - 2B细胞显著提高了IL - 6和IL - 8水平，表明mtDNA可能发挥促炎作用。
坏死性凋亡促进了香烟烟雾提取物暴露后细胞外mtDNA的释放，建立了线粒体损伤与气道炎症之间的联系。mtDNA通过诱导肺上皮细胞产生细胞因子而作为促炎介质发挥作用。这些发现表明，靶向坏死性凋亡可能为COPD提供一种新的治疗策略，既能解决气道炎症又能解决肺部结构损伤问题。
