AT2 receptor stimulation inhibits phosphate-induced vascular calcification

Area of Science:

• Cardiovascular Biology
• Renal Medicine
• Molecular Pharmacology

Background:

• Vascular calcification is prevalent in atherosclerosis and chronic kidney disease.
• The renin-angiotensin system influences cardiovascular remodeling.
• The role of angiotensin II type 2 receptor (AT2) in vascular calcification is unclear.

Purpose of the Study:

• To investigate the hypothesis that AT2 receptor stimulation inhibits phosphate-induced vascular calcification.
• To explore the underlying molecular mechanisms, including the role of PPAR-γ.

Main Methods:

• In vivo studies using adenine and high-phosphate diet in smooth muscle cell-specific AT2-overexpressing (smAT2-Tg) mice, wild-type, and AT2-knockout (AT2KO) mice.
• Ex vivo culture of thoracic aorta rings.
• In vitro studies using primary vascular smooth muscle cells.
• Assessment of osteogenic and vascular smooth muscle cell marker gene expression.
• Investigation of PPAR-γ involvement using a specific antagonist.

Main Results:

• smAT2-Tg mice exhibited significantly attenuated thoracic aorta calcification compared to wild-type and AT2KO mice.
• Gene expression of osteogenic and vascular smooth muscle cell markers remained unchanged in smAT2-Tg mice but altered in wild-type mice.
• Ex vivo and in vitro studies confirmed reduced calcification in smAT2-Tg derived tissues and cells.
• PPAR-γ antagonism diminished the protective effect of AT2 stimulation against vascular calcification.

Conclusions:

• AT2 receptor activation is an endogenous protective pathway against vascular calcification.
• AT2 stimulation, potentially via PPAR-γ, can inhibit phosphate-induced vascular calcification.
• Targeting AT2 activation may offer a therapeutic strategy to reduce cardiovascular events in chronic kidney disease.