Midkine ameliorates LPS-induced apoptosis of airway smooth muscle cells via the Notch2 pathway

Objective: To evaluate the effect of midkine on lipopolysaccharide (LPS)-induced airway smooth muscle cells (ASMCs). Methods: LPS-stimulated acute lung injury model was used to analyze the effect of midkine on ASMCs in vitro. Recombinant midkine and midkine siRNA were used to investigate the role of Notch2 signaling pathway. Cell proliferation was assessed using Cell Counting Kit-8 assay. Additionally, apoptosis was measured by flow cytometry and protein and mRNA expression of midkine and Notch2 was assessed by Western blotting and qPCR, respectively. Immunofluorescence analysis was also conducted. Results: LPS increased the mRNA and protein expression of midkine and Notch2. Midkine silencing reduced LPS-induced midkine and Notch2 expression. In addition, midkine silencing further reduced the viability and increased apoptosis of ASMCs induced by LPS, which was attenuated by recombinant midkine. Conclusions: The midkine/Notch2 signaling pathway plays a regulatory role in ASMC proliferation and apoptosis in airway inflammation.