To explore the effects of miR-21 on macrophage autophagy, proliferation and apoptosis induced by cigarette smoke extract (CSE).
 Methods: The cells was divided into a control group, a CSE interventine macrophage group (CSE group), and a miR-21 inhibitor+CSE intervention macrophage group (miR-21 inhibitor+CSE group). The expression of miR-21 in the 3 groups was detected by real-time PCR. The effects of miR-21 inhibitor on macrophage autophagy, proliferation and apoptosis were detected by Western blot, MTT assay and flow cytometry.
 Results: Compared with the control group, the levels of miR-21 and autophagy in the CSE group were significantly increased (both P<0.05). The expression of miR-21 in the miR-21 inhibitor+CSE group was significantly lower than that in the CSE group (P<0.05). Compared with the control group, the expressions of macrophage microtubule associated protein 1 light chain 3 alpha (LC3) and autophagy related 7 (ATG7) in the CSE group were increased, which was attenuated by miR-21 inhibitor. Compared with the control group, the macrophage proliferation in the CSE group was inhibited by the miR-21, which could be reversed by adding miR-21 inhibitor; the proliferative rates in the miR-21 inhibitor+CSE group in 2, 3 or 4 days were increased by 1.41, 1.54 or 1.70 times compared with those in the CSE group (all P<0.05). Flow cytometry showed that the apoptosis rate in the control group was (2.57+1.35)%, which was (18.70+2.16)% in the CSE group and (6.28+1.08)% in the miR-21 inhibitor+CSE group (P<0.05).
 Conclusion: CSE intervention macrophage increase the autophagy and apoptosis of macrophages, decrease the cell proliferation by affecting the expression of miR-21 and the level of autophagy in macrophages.
Apoptosis ; drug effects ; Autophagy ; drug effects ; Cell Proliferation ; drug effects ; Cells, Cultured ; Gene Expression Regulation ; drug effects ; Macrophages ; drug effects ; MicroRNAs ; pharmacology ; Smoke