Introduction:

Adverse cardiovascular remodeling is the hallmark of cardiovascular diseases (CVDs) associated with arterial hypertension. Chronic activation of angiotensin II (ANGII) and matrix metalloproteinases (MMPs), particularly MMP-2, greatly contribute to the pathophysiology of CVDs. It has been shown that ANGII regulates MMP-2 in various cells in vitro, including cultured endothelial (ECs) and vascular smooth muscle cells (VSMCs). However, signaling pattern of ANGII in this process has not been studied. Moreover, whether the in vitro effects of ANGII can be extrapolated to in vivo conditions remains elusive.

Aims:

The present study addressed the role and signaling mechanisms of ANGII in regulation of expression and activity of MMP-2 in cultured endothelial and vascular smooth muscle cells (in vitro), as well as in isolated aorta (ex vivo).

Methods:

Cultured rat aortic ECs and VSMCs, as well as rings of freshly isolated rat aorta were stimulated with ANGII for 8 hours. To differentiate the effects of endothelium from those of smooth muscle, rat aorta was also studied following mechanical removal of endothelium. Expression and activity of MMP-2 was assessed with western blot and gelatin zymography, respectively. A similar experimental procedure was used in human umbilical vein endothelial cells (HUVEC). Mitogen activated protein kinase (MAPK) and JAK/STAT pathways were studied as possible signal mechanisms of ANGII.

Results:

ANGII increased expression of MMP-2 in cultured endothelial and smooth muscle cells of rat aorta. This effect was inhibited by losartan^© (ANGII receptor blocker). Signaling pathways largely differed between cell species studied. In rat aortic ECs, MAPK signaling and particularly JNK pathway was involved in the effect of ANGII, whereas in VSMCs JAK/STAT signaling. In HUVEC, ANGII increased expression of MMP-2 through complex JNK and ERK pathways. The results in ex vivo isolated aortic tissue fully supported the findings objectified in cultured cells in vitro. JNK and JAK/STAT inhibitors blunted the ANGII mediated increase of expression and activity of MMP-2 in endothelial and VSMCs of isolated rat aorta, respectively.

Conclusion:

ANGII is an important regulator of MMP-2 in rat aorta and HUVEC. Signaling mechanisms of ANGII are largely distinct between cell species. This knowledge may potentially be used to inhibit MMP-2 (or other MMPs) in a distinct cell type or tissue specifically. Further experiments need to clarify whether there is a modulation of the smooth muscle and interstitial matrix response by the vascular endothelium in response to ANGII.