Neonatal pneumonia (NP) is a frequently occurring illness during the neonatal phase. The study investigated the molecular process and the role of microRNA (miR)-29a-3p in NP. Peripheral blood was collected from NP patients and healthy newborns. Human lung fibroblasts cell line (WI-38) were treated with lipopolysaccharide (LPS)) to establish a cellular model for NP. Then, miR-29a-3p and Krüppel-like Factor 4 (KLF4) levels were detected by RT-qPCR or Western blot. The relationship between miR-29a-3p and KLF4 was confirmed by dual luciferase reporter gene assay. Cell survival was assessed using the CCK-8 assay, whereas the levels of interleukin-6, tumor necrosis factor-α, and IL-1β were quantified using ELISA. Additionally, apoptosis was evaluated through flow cytometry. Meanwhile, Bax and Bcl-2 were detected by RT-qPCR. Neonatal rats were administered LPS intraperitoneally (3 mg/kg) to induce NP, and pathological injury and inflammatory reaction were analyzed. MiR-29a-3p was elevated but KLF4 was silenced in NP patient's serum, LPS-treated WI-38 cell line, and LPS-treated newborn rats. Silence of miR-29a-3p or elevation of KLF4 constrained cell proliferation with inflammation of LPS-treated WI-38 cell line. MiR-29a-3p immediately targeted KLF4. Additionally, silence of miR-29a-3p alleviated LPS-stimulated lung injury and inflammation in neonatal rats. The protective action of silenced miR-29a-3p in LPS-treated WI-38 cell line and newborn rats was turned around by silencing KLF4. This study demonstrates originally that miR-29a-3p boosts inflammatory damage in NP via targeting KLF4, offering a basis for clinically diagnosing and treating NP.
Keywords: Krüppel-like factor 4; MicroRNA; Neonate; Pneumonia.