Abstract：
Bleomycin (BLM), a frequently employed chemotherapeutic agent, exhibits restricted clinical utility owing to its pulmonary toxicity. Meanwhile, baicalin (BA)-an active ingredient extracted from the roots of Scutellaria baicalensis Georgi -has been shown to alleviate BLM-induced pulmonary fibrosis (PF). Hence, the objective of this study was to examine the protective effects of BA in the context of BLM-induced early PF in mice and elucidate the underlying mechanism(s). We established an in vivo BLM (3.5 mg/kg)-induced PF murine model and in vitro BLM (35 μM)-damaged MLE-12 cell model. On Day 14 of treatment, the levels of fibrosis and apoptosis were evaluated in mouse lungs via hydroxyproline analysis, western blotting (COL1A1, TGF-β, Bax, Bcl-2, cleaved caspase-3), and Masson, immunohistochemical (α-SMA, AIF, Cyto C), and TUNEL staining. Additionally, in vitro, apoptosis was assessed in MLE-12 cells exposed to BLM for 24 h using the Annexin V/PI assay and western blotting (Bax, Bcl-2, cleaved caspase-3, AIF, Cyto C). To elucidate the role of the mitochondrial ATP-sensitive potassium channel (mitoKATP) in the protective effect of BA, we utilised diazoxide (DZX)-a mitoKATP agonist-and 5-hydroxydecanoate sodium (5-HD)-a mitoKATP inhibitor. Results revealed the involvement of mitoKATP in the protective effect of BA in BLM-induced PF. More specifically, mitoKATP activation can attenuate BLM-induced PF progression and mitigate alveolar epithelial type II cell death by reducing mitochondrial ROS, maintaining the mitochondrial membrane potential, and impeding the mitochondrial apoptotic pathway. Collectively, the findings offer pharmacological support to use BA for the treatment or prevention of BLM-induced PF and suggest that mitoKATP might serve as an effective therapeutic target for this condition.
摘要：
博来霉素（BLM），经常使用的化学治疗剂，由于其肺毒性而表现出有限的临床实用性。同时,黄芩苷（BA）-从黄芩根提取的活性成分-已被证明可以减轻BLM诱导的肺纤维化（PF）。因此，本研究的目的是研究BA在BLM诱导的小鼠早期PF中的保护作用,并阐明其潜在机制.我们建立了体内BLM（3.5mg/kg）诱导的PF小鼠模型和体外BLM（35μM）损伤的MLE-12细胞模型。在治疗的第14天，通过羟脯氨酸分析评估小鼠肺的纤维化和凋亡水平，蛋白质印迹(COL1A1，TGF-β，Bax,Bcl-2,cleavedcaspase-3),和Masson,免疫组织化学(α-SMA，AIF,CytoC),和TUNEL染色。此外,在体外，使用膜联蛋白V/PI测定和蛋白质印迹法（Bax，Bcl-2，caspase-3，AIF，CytoC）。为了阐明线粒体ATP敏感性钾通道（mitoKATP）在BA的保护作用中的作用，我们使用了二氮嗪（DZX）-一种mitoKATP激动剂-和5-羟基癸酸钠（5-HD）-一种mitoKATP抑制剂。结果表明，mitoKATP参与了BA在BLM诱导的PF中的保护作用。更具体地说,mitoKATP激活可以减弱BLM诱导的PF进展，并通过减少线粒体ROS减轻肺泡上皮II型细胞死亡，维持线粒体膜电位，并阻碍线粒体凋亡途径。总的来说，这些发现为使用BA治疗或预防BLM诱导的PF提供了药理学支持,并提示mitoKATP可能作为该疾病的有效治疗靶点.
