Angiotensin converting enzyme 2 (ACE2) is a terminal carboxypeptidase, which cleaves single terminal residues from several bioactive peptides such as Angiotensin II (AngII). Many investigations indicated that ACE2 functions in angiotensin system and plays a crucial role in inflammatory lung diseases. However, the mechanism behind the involvement of ACE2 in inflammatory lung disease has not been fully elucidated. In this study, BEAS-2B cells were treated with gradient concentration of AngII and lipopolysaccharide (LPS) to induce inflammatory condition. Quantitative RT-PCR was performed to detect the level of ACE2 and miR-143-3p. Western blotting and immunofluorescence assays were performed to measure the expression of related proteins. The levels of inflammatory cytokines and cell viability were respectively measured by ELISA and CCK-8 kits. And ACE2 activity was detected by corresponding commercial kits. Bioinformatics methods were employed to predict the potential microRNA targeting ACE2, which was then confirmed by dual luciferase reporter assay. The results showed that ACE2 expression and activity were time-dependently decreased in LPS group for the first 12 h, after which this tendency was reversed. AngII addition enhanced these effects, compared with LPS group. Additionally, the lowest ACE2 activity level was found in both LPS and AngII + LPS groups at 6 h. The number of nuclei and the ACE2 expression were decreased in LPS groups at 6 h and further reduced by addition of AngII, detected by immunofluorescence. Moreover, ACE2 was validated to be a direct target of miR-143-3p. Pretreatment of AngII and LPS regulated the activity of ACE2, increased the expression of proinflammatory cytokines and cell apoptosis and regulated the expression of Bax, Bcl-2 and cleaved caspase-3 in BEAS-2B cells, which could be reversed by transfecting miR-143-3p inhibitor. The results collectively suggest that AngII promotes LPS-induced inflammation by regulating miR-143-3p in BEAS-2B cells. Therefore, miR-143-3p is considered a potential molecular target for the treatment of lung inflammation.

血管紧张素转化酶 2 (ACE2) 是一种末端羧肽酶，可从多种生物活性肽（如血管紧张素 II (AngII)）中切割单个末端残基。许多研究表明，ACE2 在血管紧张素系统中发挥作用，在炎症性肺病中起关键作用。然而，ACE2参与炎症性肺病的机制尚未完全阐明。在本研究中，BEAS-2B 细胞用梯度浓度的 AngII 和脂多糖 (LPS) 处理以诱导炎症状态。进行定量 RT-PCR 以检测 ACE2 和 miR-143-3p 的水平。进行蛋白质印迹和免疫荧光测定以测量相关蛋白质的表达。分别用ELISA和CCK-8试剂盒测定炎性细胞因子水平和细胞活力。并通过相应的商业试剂盒检测ACE2活性。生物信息学方法被用来预测潜在的靶向 ACE2 的 microRNA，然后通过双荧光素酶报告基因分析证实了这一点。结果表明，LPS组ACE2的表达和活性在前12小时呈时间依赖性降低，之后这种趋势被逆转。与 LPS 组相比，AngII 添加增强了这些效果。此外，在 6 小时时，LPS 和 AngII + LPS 组的 ACE2 活性水平最低。通过免疫荧光检测，LPS 组的细胞核数量和 ACE2 表达在 6 小时时降低，并且通过添加 AngII 进一步降低。此外，ACE2 被证实是 miR-143-3p 的直接靶标。AngII 和 LPS 的预处理调节了 ACE2 的活性，增加促炎细胞因子的表达和细胞凋亡，并调节 BEAS-2B 细胞中 Bax、Bcl-2 和 cleaved caspase-3 的表达，这可以通过转染 miR-143-3p 抑制剂来逆转。结果共同表明，AngII通过调节BEAS-2B细胞中的miR-143-3p来促进LPS诱导的炎症。因此，miR-143-3p被认为是治疗肺部炎症的潜在分子靶点。