Abstract:

Objective　Ventilator-associated pneumonia (VAP) is the most common infectious disease in mechanically ventilated patients, which seriously decreases the prognosis of critically ill patients, but its pathogenesis is still unclear. This study investigated the effect of mesenchymal stem cells (MSCs) on the inflammatory response of alveolar epithelial cells during VAP development. Methods　This study was conducted from May 2020 to March 2023. In this study, VAP rat animal model was established and MSCs were extracted and identified. Fifteen rats were randomly divided into 3 groups: a control group, a VAP group, and a VAP+MSCs group. The alveolar epithelial cells of the control group and the VAP group were cultured alone in the incubator, and the alveolar epithelial cells of the VAP+MSCs group were co-cultured with the MSCs in the incubator. After 48 hours, the expressions of phosphatidylinositol 3-kinase (PI3K), serine/threonine protein kinase (Akt), and downstream inflammatory factors [tumor necrosis factor-α (TNF-α), interleukin-1α (IL-1α), and γ-interferon (IFN-γ)] were detected by real-time fluorescence quantitative nucleic acid amplification assay (qPCR) and enzyme-linked immunosorbent assay (ELISA). Independent sample t test and one-way analysis of variance were used. Results　The results of qPCR and ELISA showed that the expression levels of PI3K, Akt, and downstream inflammatory factors (TNF-α, IL-1α, and IFN-γ) were the lowest in the control group; the mRNA expression levels of PI3K, Akt, and downstream inflammatory factors (TNF-α, IL-1α, and IFN-γ) in the VAP group were higher than those in the other two groups; the levels of inflammatory factors in the VAP+MSCs group were higher than those in the control group, but were lower than those in the VAP group, with statistically significant differences (all P<0.05). Conclusion　MSCs may inhibit the inflammatory factor expression in alveolar epithelial cells by inhibiting the PI3K/Akt signaling pathway, thus achieving the inhibition or mitigation of VAP.

Key words:

Ventilator-associated pneumonia, Mesenchymal stem cells, Lung injury, PI3K/Akt, Animal experiment

摘要：

目的　呼吸机相关性肺炎（VAP）是机械通气患者最常见的感染性疾病，严重影响重症患者的预后，但其发病机制目前仍未完全清晰。本文针对VAP发生时，间充质干细胞（MSCs）对肺泡上皮细胞的炎症反应的影响进行研究。方法　本研究实施于2020年5月至2023年3月。本研究建立VAP大鼠动物模型并提取、鉴定MSCs，取SPF级健康雄性大鼠15只，体质量180～200 g，随机分为空白对照组、VAP组和VAP+MSCs组。空白对照组、VAP组的肺泡上皮细胞单独在培养箱内培养，VAP+MSCs组的肺泡上皮细胞与MSCs在培养箱内共培养，48 h后通过实时荧光定量核酸扩增检测系统（qPCR）及酶联免疫吸附法（ELISA）检测3组磷脂酰肌醇3-激酶（PI3K）、丝氨酸/苏氨酸蛋白激酶（Akt）以及下游炎症因子［肿瘤坏死因子-α（TNF-α）、白细胞介素1α（IL-1α）、γ-干扰素（IFN-γ）］的表达情况。采用独立样本t检验、单因素方差分析。结果　qPCR及ELISA检测结果显示空白对照组PI3K、Akt以及下游炎症因子TNF-α、IL-1α、IFN-γ表达水平最低；VAP组PI3K、Akt以及下游炎症因子TNF-α、IL-1α、IFN-γ mRNA表达水平最高，高于另外两组；而VAP+MSCs组炎症因子水平虽高于空白对照组，但较VAP组下降，差异均有统计学意义（均P<0.05）。结论　在VAP发生过程中MSCs可能通过抑制PI3K/Akt信号通路抑制肺泡上皮细胞炎症因子表达，从而达到抑制或减轻VAP的作用。

关键词:

呼吸机相关性肺炎, 间充质干细胞, 肺损伤, PI3K/Akt, 动物实验