Department of Trauma Intensive Care Unit, The First Affiliated Hospital of Hainan Medical University, Haikou, China.
Key Laboratory of Emergency and Trauma of Ministry of Education, Hainan Medical University, Haikou, China.
Front Immunol. 2020 Aug 13;11:1829. doi: 10.3389/fimmu.2020.01829. eCollection 2020.
Sepsis is the leading cause of death in intensive care units. MicroRNA-34a (miR-34a) is involved in sepsis progression, while its underlying mechanisms on sepsis-induced lung injury remain obscure. Oxidative stress, pyroptosis, and inhibition of autophagy can result in organ injury. MiR-34a has been reported to regulate oxidative stress and autophagy via inhibiting silent information regulator T1 (SIRT1) and autophagy gene 4B (ATG4B) signaling. This study aimed at identifying the function of miR-34a in oxidative stress, inflammation, pyroptosis, and autophagy in sepsis-induced lung injury. Male 8-week-old C57BL/6 mice were subjected to cecal ligation and puncture and treated with miR-34a antagomir/agomir. Survival ( = 10), histopathological changes ( = 6), and lung wet-to-dry ratio ( = 6) were recorded and assayed. Other detection ( = 6) was performed to investigate the level of oxidative stress, inflammation, pyroptosis, and autophagy in lung tissues. Results showed that miR-34a down-regulation ameliorated lung injury in septic mice as reflected by decreased lung injury scores (decrease from 3.00 ± 0.32 to 2.00 ± 0.32) and wet-to-dry ratio (0.36-fold decrease). MiR-34a down-regulation also decreased reactive oxygen species accumulation (0.36-fold decrease), and promoted superoxide dismutase activity and the expression of SIRT1 (1.24-fold increase), heme oxygenase-1 and nuclear factor erythroid 2 like 2 to inhibit oxidative stress in septic mice. Moreover, miR-34a down-regulation suppressed inflammatory response and pyroptosis in septic mice, as evidenced by decreased level of pro-inflammatory factors including tumor necrosis factor α, interleukin-6 (IL-6), IL-1β, and IL-18, activity of caspase-1 (0.51-fold decrease) and expression of nucleotide-binding domain and leucine-rich repeat protein-3 (0.48-fold decrease), apoptosis-associated speck-like protein containing a CARD, cleaved-caspase-1, and cleaved-gasdermin D (0.36-fold decrease), and increased level of anti-inflammatory factors IL-10. MiR-34a down-regulation also enhanced autophagy in septic mice as evidenced by more autolysosomes and elevated expressions of ATG4B (0.90-fold increase), beclin1, ATG9, and LC3 II/I. Among these experiments, miR-34a up-regulation showed opposite effects on oxidative stress, inflammatory response, pyroptosis, and autophagy in septic mice. Additionally, miR-34a could bind to the 3'-untranslated region of SIRT1 and ATG4B. In conclusion, our findings demonstrated that miR-34a was implicated in oxidative stress, inflammation, pyroptosis, and autophagy in the development of sepsis. MiR-34a inhibition had a potential to alleviate sepsis-induced lung injury.
脓毒症是重症监护病房死亡的主要原因。微小 RNA-34a（miR-34a）参与脓毒症的进展，但其在脓毒症诱导的肺损伤中的潜在机制尚不清楚。氧化应激、细胞焦亡和自噬抑制可导致器官损伤。有报道称，miR-34a 通过抑制沉默信息调节因子 T1（SIRT1）和自噬基因 4B（ATG4B）信号通路来调节氧化应激和自噬。本研究旨在确定 miR-34a 在脓毒症诱导的肺损伤中的氧化应激、炎症、细胞焦亡和自噬中的作用。雄性 8 周龄 C57BL/6 小鼠进行盲肠结扎和穿刺，并给予 miR-34a 反义寡核苷酸/激动剂处理。记录和检测（= 10）生存情况、组织病理学变化（= 6）和肺湿干重比（= 6）。进行其他检测（= 6）以研究肺组织中氧化应激、炎症、细胞焦亡和自噬的水平。结果表明，下调 miR-34a 可减轻脓毒症小鼠的肺损伤，表现为肺损伤评分（从 3.00±0.32 降低至 2.00±0.32）和湿干重比（降低 0.36 倍）降低。miR-34a 下调还可减少活性氧（ROS）积累（降低 0.36 倍），并促进超氧化物歧化酶活性和 SIRT1 的表达（增加 1.24 倍）、血红素加氧酶-1 和核因子红细胞 2 样 2 以抑制脓毒症小鼠的氧化应激。此外，下调 miR-34a 可抑制脓毒症小鼠的炎症反应和细胞焦亡，表现为促炎因子水平（肿瘤坏死因子-α、白细胞介素-6（IL-6）、白细胞介素-1β和白细胞介素-18）降低，半胱氨酸天冬氨酸蛋白酶-1 活性（降低 0.51 倍）和核苷酸结合域和富含亮氨酸重复蛋白 3（NLRP3）表达（降低 0.48 倍）、凋亡相关斑点样蛋白包含 CARD、裂解半胱氨酸天冬氨酸蛋白酶-1 和裂解 gasdermin D（降低 0.36 倍），以及抗炎因子 IL-10 水平升高。miR-34a 下调还可增强脓毒症小鼠的自噬，表现为自噬溶酶体增多，ATG4B（增加 0.90 倍）、beclin1、ATG9 和 LC3 II/I 的表达增加。在这些实验中，上调 miR-34a 对脓毒症小鼠的氧化应激、炎症反应、细胞焦亡和自噬有相反的作用。此外，miR-34a 可以与 SIRT1 和 ATG4B 的 3'-非翻译区结合。总之，我们的研究结果表明，miR-34a 参与了脓毒症的氧化应激、炎症、细胞焦亡和自噬的发展。抑制 miR-34a 有潜力减轻脓毒症引起的肺损伤。
