Background and aims: Angiotensin II (Ang II) is a bioactive peptide that is related to cardiovascular disease such as atherosclerosis, whereas angiotensin-(1-7) (Ang-(1-7)) is a counter-regulator of angiotensin II, which protects against cardiovascular disease. Matrix metalloproteinase 8 (MMP-8) is thought to participate in plaque destabilization though degradation of extracellular matrix, improving the development of atherosclerosis. Whether Ang-(1-7) modulates Ang II-induced MMP-8 remains unclear. In this study, we investigated the effect of Ang-(1-7) on Ang II-induced MMP-8 expression in smooth muscle cells.
Methods: Smooth muscle cells were treated with Ang II, Ang-(1-7) and their antagonists. In addition, ApoE knockout mice were fed a high fat diet and subcutaneously injected with Ang II, Ang-(1-7), Ang II+Ang-(1-7) (±A779).
Results: We found that Ang II increased MMP-8 mRNA and protein expression in vascular smooth muscle cells, while Ang-(1-7) alone had no effect. However, Ang-(1-7) inhibited Ang II-induced MMP-8 expression. The inhibitory effect of Ang-(1-7) could be abolished by the competitive antagonist of Ang-(1-7) at the MAS receptor. Furthermore, Ang II induced p38 MAPK activation, and this was inhibited by the treatment of Ang-(1-7). Ang II-induced MMP-8 expression could be attenuated by the p38 MAPK inhibitor SB203580. Ang-(1-7) also significantly suppressed Ang II-induced MMP-8 in both atherosclerotic plaques and serum in ApoE-/- mice. The atherosclerotic plaques in mice treated with Ang-(1-7) and Ang II appeared to be more stable with more type I collagen contents than those in mice treated with Ang II.
Conclusions: Our results suggest that Ang-(1-7) plays an important role in protecting against atherosclerosis via counter-regulation of Ang II-induced MMP-8.
Keywords: Angiotensin; Matrix metalloproteinase-8; Smooth muscle cell.
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