Mechanism of LPS-induced macrophage-derived exosomes promoting macrophage anti-Mycobacterium tuberculosis autophagy

Objective To investigate the effect and mechanism of LPS-induced macrophage-derived exosomes on macrophage anti-Mycobacterium tuberculosis (M.tb) autophagy.

Methods H37Ra-infected macrophages were induced by THP-1 cells, and macrophage exosomes were extracted and identified; LPS-induced macrophage exosomes were extracted and co-cultured with H37Ra infected macrophages.The exosomes were labeled with Dil fluorescence, and the absorption of exosomes was observed under fluorescence microscope.The effects of exosomes on macrophages' anti-M.tb autophagy were determined by fluorescent quantitative PCR, flow cytometry, Western blotting and other methods.

Results The macrophage exosomes stimulated by LPS were successfully extracted and identified.There was no significant change in the autophagy level of macrophages that absorbed ordinary exosomes.The autophagy level of macrophages that absorbed LPS-induced exosomes was significantly increased.The effect of promoting macrophage autophagy disappeared when exosomes inhibitor was added during coculture; after the macrophages infected with H37Ra absorbed LPS-induced exosomes, the autophagy level was enhanced, and the killing ability of M.tb and the secretion of human interleukin-12 were significantly increased.

Conclusions LPS-induced macrophage-derived exosomes can promote macrophage anti-M.tb autophagy.