table2_The Protective Effects of Shengmai Formula Against Myocardial Injury Induced by Ultrafine Particulate Matter Exposure and Myocardial Ischemia are Mediated by the PI3K/AKT/p38 MAPK/Nrf2 Pathway.docx

Background and Purpose: Ultrafine particulate matter (UFPM) induces oxidative stress (OS) and is considered to be a risk factor of myocardial ischemia (MI). Shengmai formula (SMF) is a traditional Chinese medicine with antioxidant properties and has been used to treat cardiovascular diseases for a long time. The aim of this study was to explore the protective role of SMF and the mechanism by which it prevents myocardial injury in UFPM-exposed rats with MI.
Methods: An MI rat model was established. Animals were randomly divided into five groups: sham, UFPM + MI, SMF (1.08 mg/kg⋅d) + UFPM + MI, SMF (2.16 mg/kg⋅d) + UFPM + MI, and SMF (4.32 mg/kg⋅d) + UFPM + MI. SMF or saline was administrated 7 days before UFPM instillation (100 μg/kg), followed by 24 h of ischemia. Physiological and biochemical parameters were measured, and histopathological examinations were conducted to evaluate myocardial damage. We also explored the potential mechanism of the protective role of SMF using a system pharmacology approach and an in vitro myoblast cell model with small molecule inhibitors.
Results: UFPM produced myocardial injuries on myocardial infarct size; serum levels of LDH, CK-MB, and cardiac troponin; and OS responses in the rats with MI. Pretreatment with SMF significantly attenuated these damages via reversing the biomarkers. SMF also improved histopathology induced by UFPM and significantly altered the PI3K/AKT/MAPK and OS signaling pathways. The expression patterns of Cat, Gstk1, and Cyba in the UFPM model group were reversed in the SMF-treated group. In in vitro studies, SMF attenuated UFPM-induced reactive oxygen species production, mitochondrial damage, and OS responses. The PI3K/AKT/p38 MAPK/Nrf2 pathway was significantly changed in the SMF group compared with that in the UFPM group, whereas opposite results were obtained for pathway inhibition.
Conclusion: These findings indicate that SMF prevents OS responses and exerts beneficial effects against myocardial injury induced by UFPM + MI in rats. Furthermore, the PI3K/AKT/p38 MAPK/Nrf2 signaling pathway might be involved in the protective effects of SMF.

背景与目的：超细颗粒物（Ultrafine Particulate Matter, UFPM）可诱导氧化应激（Oxidative Stress, OS），被认为是心肌缺血（Myocardial Ischemia, MI）的危险因素。生脉方（Shengmai Formula, SMF）是一种具有抗氧化活性的传统中药，长期以来被用于心血管疾病的治疗。本研究旨在探究生脉方的心肌保护作用，及其缓解暴露于UFPM的MI模型大鼠心肌损伤的潜在分子机制。
研究方法：本研究构建了MI大鼠模型，将实验动物随机分为5组：假手术组、UFPM+MI组、低剂量SMF（1.08 mg/kg·d）+UFPM+MI组、中剂量SMF（2.16 mg/kg·d）+UFPM+MI组、高剂量SMF（4.32 mg/kg·d）+UFPM+MI组。在UFPM滴注（100 μg/kg）前7天给予受试动物SMF或生理盐水灌胃，随后持续缺血24小时。检测各组大鼠的生理与生化指标，并开展组织病理学检查以评估心肌损伤程度。本研究同时采用系统药理学方法及构建携带小分子抑制剂的体外成肌细胞模型，进一步探究生脉方发挥心肌保护作用的潜在机制。
研究结果：UFPM可加重MI模型大鼠的心肌梗死面积，升高血清乳酸脱氢酶（LDH）、肌酸激酶同工酶MB（CK-MB）及心肌肌钙蛋白水平，并诱导机体产生氧化应激反应。经生脉方预处理后，上述病理损伤均得到显著缓解，相关生物标志物水平恢复至正常范围。生脉方同时改善了UFPM诱导的心肌组织病理学异常，并显著调控PI3K/AKT/MAPK及氧化应激信号通路的活性。在UFPM模型组中，Cat、Gstk1及Cyba的基因表达模式在SMF干预组中发生显著逆转。体外实验结果显示，生脉方可抑制UFPM诱导的活性氧（Reactive Oxygen Species, ROS）生成、线粒体损伤及氧化应激反应。与UFPM组相比，SMF干预组的PI3K/AKT/p38 MAPK/Nrf2通路活性发生显著改变，而采用通路抑制剂处理则得到相反的实验结果。
结论：本研究结果表明，生脉方可有效抑制氧化应激反应，对暴露于UFPM合并MI的大鼠心肌损伤发挥显著的保护作用。此外，PI3K/AKT/p38 MAPK/Nrf2信号通路可能参与介导了生脉方的心肌保护效应。