长非编码 RNA Sox2OT 通过介导细胞焦亡促进冠状动脉微栓塞诱导的心肌损伤。

OBJECTIVE: As a common complication of coronary microembolization (CME), myocardial injury (MI) implies high mortality. Long non-coding RNAs (lncRNAs) are rarely studied in CME-induced MI. Herein, this study intended to evaluate the role of lncRNA Sox2 overlapping transcript (Sox2OT) in CME-induced MI. METHODS: The CME rat models were successfully established by injection of microemboli. Rat cardiac functions and MI were observed by ultrasonic electrocardiogram, HE staining, and HBFP staining. Functional assays were utilized to test the inflammatory responses, oxidative stress, and pyroptosis using reverse transcription quantitative polymerase chain reaction, Western blotting, immunohistochemistry, immunofluorescence, and ELISA. Dual-luciferase reporter gene assay and RNA immunoprecipitation were conducted to clarify the targeting relations between Sox2OT and microRNA (miRNA)-23b and between miR-23b and toll-like receptor 4 (TLR4). RESULTS: Rat CME disrupted the cardiac functions and induced inflammatory responses and oxidative stress, and activated the nuclear factor-kappa B (NF-κB) pathway and pyroptosis (all P < 0.05). An NF-κB inhibitor downregulated the NF-κB pathway, reduced pyroptosis, and relieved cardiomyocyte injury and pyroptosis. Compared with the sham group (1.05 ± 0.32), lncRNA Sox2OT level (4.41 ± 0.67) in the CME group was elevated (P < 0.05). Sox2OT acted as a competitive endogenous RNA (ceRNA) of miR-23b to regulate TLR4. Silencing of Sox2OT favoured miR-23b binding to 3'UTR of TLR4 mRNA leading to suppressed TLR4-mediated NFKB signalling and pyroptosis in myocardial tissues harvested from CME rat models. In addition, miR-23b overexpression could supplement the cytosolic miR-23b reserves to target TLR-4 and partially reverse Sox2OT-mediated pyroptosis in LPS-treated H9C2 cells. CONCLUSIONS: This study supported that silencing Sox2OT inhibited CME-induced MI by eliminating Sox2OT/miR-23b binding and down-regulating the TLR4/NF-κB pathway. This investigation may provide novel insights for the treatment of CME-induced MI.

目的：作为冠状动脉微栓塞（CME）的常见并发症，心肌损伤（MI）意味着高死亡率。长链非编码 RNA（lncRNA）在 CME 诱导的 MI 中很少被研究。本研究旨在评估 lncRNA Sox2 重叠转录物（Sox2OT）在 CME 诱导的 MI 中的作用。

方法：通过注射微栓塞成功建立 CME 大鼠模型。超声心电图、HE 染色和 HBFP 染色观察大鼠心功能和 MI。逆转录定量聚合酶链反应、Western blot、免疫组织化学、免疫荧光和 ELISA 用于测试炎症反应、氧化应激和细胞焦亡。双荧光素酶报告基因检测和 RNA 免疫沉淀用于阐明 Sox2OT 与 microRNA（miRNA）-23b 以及 miR-23b 与 toll 样受体 4（TLR4）之间的靶向关系。

结果：大鼠 CME 破坏了心脏功能并诱导了炎症反应和氧化应激，激活了核因子-κB（NF-κB）途径和细胞焦亡（均 P<0.05）。NF-κB 抑制剂下调 NF-κB 途径，减少细胞焦亡，并减轻心肌细胞损伤和细胞焦亡。与 sham 组（1.05±0.32）相比，CME 组 lncRNA Sox2OT 水平（4.41±0.67）升高（P<0.05）。Sox2OT 作为 miR-23b 的竞争性内源性 RNA（ceRNA），调节 TLR4。沉默 Sox2OT 有利于 miR-23b 结合 TLR4 mRNA 的 3'UTR，导致心肌组织中 TLR4 介导的 NFKB 信号和细胞焦亡受到抑制。此外，miR-23b 过表达可以补充细胞质 miR-23b 储备，以靶向 TLR-4，并部分逆转 LPS 处理的 H9C2 细胞中 Sox2OT 介导的细胞焦亡。

结论：本研究表明，沉默 Sox2OT 通过消除 Sox2OT/miR-23b 结合并下调 TLR4/NF-κB 途径来抑制 CME 诱导的 MI。这项研究为 CME 诱导的 MI 的治疗提供了新的思路。