Circular RNAs (circRNAs) play important roles in human diseases, including infantile pneumonia. In this article, we aimed to investigate the functions of circ-BICC1 in lipopolysaccharide (LPS)-induced injury of WI-38 cells. Quantitative real-time polymerase chain reaction (qRT-PCR) assay was performed for the levels of circ-BICC1, BICC1, microRNA-338-3p (miR-338-3p), and myeloid differentiation primary response 88 (MYD88). Cell Counting Kit-8 (CCK-8) assay, 5-ethynyl-2’-deoxyuridine (EdU) assay, and flow cytometry analysis were conducted to evaluate cell viability, proliferation, and apoptosis, respectively. Enzyme-linked immunosorbent assay (ELISA) kits were used for the concentrations of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). The levels of oxidative stress markers were detected with commercial kits. Dual-luciferase reporter assay was adopted to analyze the interaction between circ-BICC1 and miR-338-3p, as well as MYD88 and miR-338-3p. Western blot assay was employed for the protein level of MYD88. Circ-BICC1 level was increased in pneumonia patients’ blood samples and LPS-treated WI-38 cells. LPS treatment suppressed WI-38 cell viability and promoted cell apoptosis, inflammation, and oxidative stress. Circ-BICC1 knockdown reversed the effect of LPS-induced WI-38 cell injury. For mechanism analysis, circ-BICC1 could function as the sponge for miR-338-3p and miR-338-3p inhibition reversed the effect of circ-BICC1 knockdown on LPS-induced WI-38 cell injury. MYD88 was identified as the target of miR-338-3p. MiR-338-3p overexpression relieved LPS-induced injury of WI-38 cells, while the impact was abolished by elevating MYD88. Circ-BICC1 silencing remitted LPS-triggered WI-38 cell damage by adsorbing miR-338-3p and regulating MYD88.

环状 RNA (circRNA) 在人类疾病（包括婴儿肺炎）中发挥着重要作用。在本文中，我们旨在研究 circ-BICC1 在脂多糖 (LPS) 诱导的 WI-38 细胞损伤中的作用。对 circ-BICC1、BICC1、microRNA-338-3p (miR-338-3p) 和骨髓分化初级反应 88 (MYD88) 的水平进行了定量实时聚合酶链反应 (qRT-PCR) 测定。细胞计数 Kit-8 (CCK-8) 测定、5-乙炔基-2'-脱氧尿苷 (EdU) 测定和流式细胞术分析分别用于评估细胞活力、增殖和凋亡。酶联免疫吸附测定 (ELISA) 试剂盒用于检测白细胞介素 1β (IL-1β) 和肿瘤坏死因子-α (TNF-α) 的浓度。使用商业试剂盒检测氧化应激标记物的水平。采用双荧光素酶报告基因检测分析 circ-BICC1 和 miR-338-3p，以及 MYD88 和 miR-338-3p 之间的相互作用。MYD88 的蛋白质水平采用蛋白质印迹法测定。肺炎患者的血液样本和 LPS 处理的 WI-38 细胞中的 Circ-BICC1 水平升高。LPS 处理抑制 WI-38 细胞活力并促进细胞凋亡、炎症和氧化应激。Circ-BICC1 敲低逆转了 LPS 诱导的 WI-38 细胞损伤的影响。对于机制分析，circ-BICC1 可以作为 miR-338-3p 的海绵，抑制 miR-338-3p 可以逆转 circ-BICC1 敲低对 LPS 诱导的 WI-38 细胞损伤的影响。MYD88 被确定为 miR-338-3p 的靶标。MiR-338-3p 过表达减轻了 LPS 诱导的 WI-38 细胞损伤，同时通过提高 MYD88 消除了这种影响。