OxLDL-stimulated macrophage exosomes promote proatherogenic vascular smooth muscle cell viability and invasion via delivering miR-186-5p then inactivating SHIP2 mediated PI3K/AKT/mTOR pathway

The current study aimed to investigate the implication of microRNA (miRNA) profile in the linkage between oxidized low-density-lipoprotein (oxLDL)-stimulated-macrophages (MФ) exosomes and vascular smooth muscle cells (VSMCs) during atherosclerosis. VSMCs were treated by oxLDL-stimulated-MФ with/without GW4869. MiRNA profile in oxLDL-stimulated-MФ and untreated-MФ was detected by microarray, then candidate miRNAs were proposed to RT-qPCR and functional validation in VSMCs. MiR-186-5p mimic/inhibitor was transfected into oxLDL-stimulated-MФ, then its exosomes were used to VSMCs. Subsequently, miR-186-5p, SHIP2 and PI3K/AKT/mTOR pathway were modified alone or in combination in VSMCs. VSMCs viability, invasion and apoptosis were detected. OxLDL-stimulated-MФ induced VSMCs viability, invasion, but repressed apoptosis (all P < 0.01); while after GW4869 treatment to delete exosomes, its effect was weakened (all P < 0.05). Totally 45 dysregulated miRNAs were identified in oxLDL-stimulated-MФ versus untreated-MФ. The top-three dysregulated miRNAs (miR-186-5p, miR-21-5p, miR-320b) were elevated in VSMCs after oxLDL-stimulated-MФ treatment (all P < 0.001); while only miR-186-5p mimic greatly enhanced VSMCs viability and invasion (both P < 0.01). Furthermore, miR-186-5p-overexpressed oxLDL-stimulated-MФ exosomes promoted VSMCs viability, invasion, repressed apoptosis, while miR-186-5p-knockdown oxLDL-stimulated-MФ exosomes exhibited opposite effect (all P < 0.05). MiR-186-5p negatively regulated SHIP2 in VSMCs and bound SHIP2 via luciferase-reporter-gene assay (all P < 0.05). SHIP2 overexpression decreased VSMCs viability, invasion, PI3K/AKT/mTOR pathway, increased apoptosis, and attenuated miR-186-5p-overexpression's effect on these functions (all P < 0.05). Besides, PI3K activator (740 Y-P) weakened SHIP2-overexpression's effect on VSMCs viability, invasion and apoptosis (all P < 0.05). In conclusion, oxLDL-stimulated-MФ exosomes deliver miR-186-5p to inactivate SHIP2 mediated PI3K/AKT/mTOR pathway, then promote cell viability and invasion in VSMCs to accelerate atherosclerosis.