Angiotensin-(1-7) stimulates cholesterol efflux from angiotensin II-treated cholesterol-loaded THP-1 macrophages through the suppression of p38 and c-Jun N-terminal kinase signaling.

Abstract

Angiotensin II (Ang II) and Ang-(1-7) are key effector peptides of the renin-angiotensin system. The present study aimed to investigate the effects of Ang-(1-7) on Ang II-stimulated cholesterol efflux and the associated molecular mechanisms. Differentiated THP-1 macrophages were treated with Ang II (1 µM) and/or Ang-(1-7) (10 and 100 nM) for 24 h and the cholesterol efflux and gene expression levels were assessed. Pharmacological inhibition of peroxisome proliferator-activated receptor (PPAR)γ and mitogen-activated protein kinases (MAPKs) were performed to identify the signaling pathways involved. The results demonstrated that Ang II significantly inhibited the cholesterol efflux from cholesterol-loaded THP-1 macrophages. Treatment with Ang-(1-7) led to a dose-dependent restoration of cholesterol efflux in the Ang II-treated cells. The co-treatment with Ang-(1-7) and Ang II significantly increased the expression levels of adenosine triphosphate (ATP)-binding cassette (ABC)A1 and ABCG1 compared with treatment with Ang II alone. This was coupled with increased expression levels of PPARγ and liver X receptor (LXR)α. The pharmacological inhibition of PPARγ significantly (P<0.05) eliminated the Ang-(1-7)-mediated induction of ABCA1 and ABCG1 mRNA expression. Treatment with Ang-(1-7) caused the inactivation of c-Jun N-terminal kinases (JNK) and p38 MAPK signaling in the Ang II-treated THP-1 macrophages. In addition, the inhibition of JNK or p38 MAPK signaling using specific pharmacological inhibitors mimicked the Ang-(1-7)-induced expression of PPARγ and LXRα. In conclusion, the data demonstrated that treatment with Ang-(1-7) promoted cholesterol efflux in Ang II-treated THP-1 macrophages, partly through inactivation of p38 and JNK signaling and by inducing the expression of PPARγ and LXRα. Ang (1-7) may, therefore, have therapeutic benefits for the treatment of atherosclerosis.