Background: Airway smooth muscle cells (ASMC) can produce a variety of cytokine during inflammation, causing changes in the components of the extracellular matrix, which are related to airway remodeling. Midkine (MK) can promote the chemotaxis of various inflammatory cells and release inflammatory factors. Whether Notch and Midkine together affect the proliferation and apoptosis of airway smooth muscle cells is unclear.Objective: To study the mechanism of Midkine on LPS-induced acute lung

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... caused by airway smooth muscle cells.Methods: Airway smooth muscle cells were cultured in vitro and divided into 5 groups: control group, lipopolysaccharide group (LPS), Non-targeted siRNA group, MKsiRNA group, Notch inhibitor group (LY411575). The cell proliferation level was detected by CCK-8. The apoptosis level was detected by flow cytometry. The changes of cytokine in the Midkine/Notch2 signaling pathway were detected by Westernblot, qPCR and cellular immunofluorescence.Results: Midkine and Notch2 were highly expressed in the LPS group. MKsiRNA can effectively block the expression of Midkine induced by LPS while down-regulating the expression of Notch2. This result is the same as that of Notch inhibitor (LY411575). Exogenous Midkine promoted the proliferation of airway smooth muscle cells and reduced the rate of apoptosis in the LPS group. When the expression of Midkine was blocked, the proliferation of airway smooth muscle cells in the LPS group was significantly reduced, while apoptosis increased. Inhibiting the expression of Notch, the proliferation of airway smooth muscle cells in the LPS group decreased, and apoptosis increased.Conclusions: Midkine/Notch2 signaling pathway plays an important role in regulating airway smooth muscle cell proliferation and apoptosis in airway inflammation.