右美托咪定通过抑制小窝蛋白-1下游信号通路减轻脂多糖诱导的大鼠急性肺损伤。
Dexmedetomidine attenuates lipopolysaccharide induced acute lung injury in rats by inhibition of caveolin-1 downstream signaling.
机构信息
Department of anesthesia, Huzhou maternal & child health care hospital, wuxing area NO.2 East Street, Huzhou City, 313000 Zhejiang province, China.
Department of anesthesia, Huzhou maternal & child health care hospital, wuxing area NO.2 East Street, Huzhou City, 313000 Zhejiang province, China.
出版信息
Biomed Pharmacother. 2019 Oct;118:109314. doi: 10.1016/j.biopha.2019.109314. Epub 2019 Aug 10.
OBJECTIVE
Toll-like receptor 4(TLR-4)/nuclear factor-kappa B(NF-κB) pathway plays an important role in inducing acute lung injury (ALI). Studies have proved Dexmedetomidine (Dex) inhibits inflammatory response to mitigate lipopolysaccharide (LPS)-induced ALI and protect against multiorgan injury in various scenarios via restraining TLR-4/NF-κB signaling pathway. Many of the known downstream molecules have been orientated with a protein caveolin-1(Cav-1), which is supposed to take part in regulating TLR4-mediated inflammatory responses. However, its mechanisms have not been confirmed. The aim of this study is to evaluate the protective effects and potential mechanisms of Dex against LPS-induced ALI in male rats.
METHODS
Male rats received tail-vein injection of LPS to form ALI model. Rats were administrated with intraperitoneal injection Dex0.5 h before ALI. At 6 h after LPS injection, bronchoalveolar lavage fluid (BALF) and lung tissue were harvested. We stained the lung tissue sections with hematoxylin eosin (HE) staining to observe the histopathological damage and measure the ALI pathology score. We also measured the wet-to-dry(W/D) weight ratio of lung tissue. Lung myeloperoxidase (MPO) and inflammatory cytokines in the BALF were detected by Enzyme-linked immunosorbent assay(ELISA). Protein levels of Cav-1, TLR-4 and NF-κB in lung tissue were tested by immunohistochemistry method. The mRNA expression of Cav-1, TLR4 and the NF-κB in lung tissue were measured to determine the related mechanisms by quantitative real-time polymerase chain reaction(RT-PCR).
RESULTS
It was indicated that Dex pretreatment markedly mitigated pathomorphologic changes and pathological lung injury scores. Besides, Dex pretreatment obviously decreased the W/D weight ratio of lung tissue, attenuated MPO activity significantly, along with LPS-stimulated augment of lung inflammatory cells infiltration in BALF. Moreover, compared with LPS model group, Dex pretreatment apparently increased the protein levels of Cav-1 downregulated by sepsis and decreased the protein levels of TLR-4 and NF-κB in lung tissue. Furthermore, Dex pretreatment apparently upregulated the expression of Cav-1 mRNA, restrained TLR4 and NF-κB mRNA.
CONCLUSION
Dex pretreatment protects against LPS-induced ALI via inhibiting the activation of the TLR-4/NF-kB signaling pathway by upregulating the expression of Cav-1 downregulated by sepsis.
目的
Toll 样受体 4（TLR-4）/核因子-κB（NF-κB）通路在诱导急性肺损伤（ALI）中起重要作用。研究证实，右美托咪定（Dex）通过抑制 TLR-4/NF-κB 信号通路，抑制炎症反应，减轻脂多糖（LPS）诱导的 ALI，并在各种情况下防止多器官损伤。许多已知的下游分子已定向于一种蛋白质 caveolin-1（Cav-1），它被认为参与调节 TLR4 介导的炎症反应。然而，其机制尚未得到证实。本研究旨在评估 Dex 对雄性大鼠 LPS 诱导的 ALI 的保护作用及其潜在机制。
方法
雄性大鼠尾静脉注射 LPS 形成 ALI 模型。在 ALI 前 0.5 h 给予大鼠腹腔注射 Dex。LPS 注射后 6 h 采集支气管肺泡灌洗液（BALF）和肺组织。用苏木精-伊红（HE）染色对肺组织切片进行染色，观察组织病理学损伤，并测量 ALI 病理评分。还测量肺组织的湿重/干重（W/D）比值。通过酶联免疫吸附试验（ELISA）检测 BALF 中的肺髓过氧化物酶（MPO）和炎症细胞因子。用免疫组织化学法检测肺组织中 Cav-1、TLR-4 和 NF-κB 的蛋白水平。通过定量实时聚合酶链反应（RT-PCR）测定肺组织中 Cav-1、TLR4 和 NF-κB 的 mRNA 表达，以确定相关机制。
结果
结果表明，Dex 预处理可显著减轻病理形态改变和肺损伤评分。此外，Dex 预处理明显降低了肺组织的 W/D 重量比，显著减弱了 MPO 活性，并减轻了 LPS 刺激引起的 BALF 中肺炎症细胞浸润。此外，与 LPS 模型组相比，Dex 预处理明显增加了脓毒症下调的 Cav-1 蛋白水平，并降低了肺组织中 TLR-4 和 NF-κB 的蛋白水平。此外，Dex 预处理明显上调了 Cav-1 mRNA 的表达，抑制了 TLR4 和 NF-κB mRNA 的表达。
结论
Dex 预处理通过上调脓毒症下调的 Cav-1 表达，抑制 TLR-4/NF-kB 信号通路的激活，对 LPS 诱导的 ALI 起保护作用。
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