Abstract:

Objective To explore the regulatory role of mitogen ⁃activated protein kinase kinase kinase kinase 4（Map4k4）in the formation of vulnerable plaques in atherosclerosis（AS）induced by angiotensin Ⅱ（AngⅡ）. Methods Thirty⁃two ApoE-/- mice were randomly divided into four groups（8 in each group）：control，AngⅡ， AngⅡ+shMap4k4 and AngⅡ+Map4k4. Oil red O staining（lipid），Masson staining（collagen），α⁃actin immuno⁃ fluorescence staining（smooth muscle cells）and F4/80 staining（macrophages）were used to detect the stability of aortic sinus plaque. The expression of Map4k4 was analyzed by immunofluorescence and Western blot. Map4k4 knockdown or overexpression macrophages were constructed in vitro to confirm the role of Map4k4 in AngⅡ⁃in⁃ duced apoptosis. Results The atherosclerotic plaque vulnerability and macrophage apoptosis were promoted in ApoE-/- mice by Ang Ⅱ（P < 0.05），accompanied by the upregulation of Map4k4 expression. Compared with the AngⅡ group（P < 0.05），the AS plaque vulnerability［（1.22 ± 0.06）vs.（0.49 ± 0.04）］and macrophage apoptosis ［（8.42 ± 0.40）vs.（3.49 ± 0.31）］of the Ang Ⅱ+shMap4k4 group were significantly reduced（P < 0.05），while the above indicators of the Ang Ⅱ+Map4k4 group were significantly enhanced［（1.22 ± 0.06）vs.（1.45 ± 0.05）； （8.42 ± 0.40）vs（. 14.11 ± 0.78），P < 0.05］. In vitro experiments showed that Map4k4 knockdown effectively atten⁃ uated the increased expression of c⁃Caspase3 and Bax protein induced by AngⅡ（P < 0.05），and enhanced the expression of Bcl ⁃2 protein（P < 0.05）. The overexpression of Map4k4 further enhanced the induction of Ang Ⅱ （P < 0.05）. Conclusion Ang Ⅱ via upregulating Map4k4 expression promotes macrophage apoptosis so as to promote vulnerable plaque formation in AS.

Key words:

mitogen?activated protein kinase kinase kinase kinase 4, angiotensin Ⅱ, atherosclerosis, vulnerable plaques, macrophage