ox-LDL induces PiT-1 expression in human aortic valve interstitial cells

Area of Science:

• Cardiovascular Biology
• Molecular Medicine
• Biochemistry

Background:

• Calcific aortic stenosis involves aortic valve interstitial cells (AVICs) changing from myofibroblasts to bone-forming-like cells.
• Oxidized low-density lipoprotein (ox-LDL) is found in calcified aortic valves, a risk factor for stenosis, but its role is unclear.
• Phosphate inorganic transporter 1 (PiT-1) mediates calcium phosphate deposition in aortic valve calcification.

Purpose of the Study:

• To investigate the effect of ox-LDL on human AVICs.
• To examine ox-LDL's impact on the expression of PiT-1 and bone morphogenetic protein 2 (BMP-2).

Main Methods:

• Human AVICs were isolated and cultured.
• Cells were treated with ox-LDL, with or without a PiT-1 inhibitor (phosphonoformate hexahydrate acid).
• PiT-1 and BMP-2 expression levels were analyzed via immunoblot and densitometry.

Main Results:

• Oxidized LDL (ox-LDL) significantly increased the expression of PiT-1 and BMP-2 in AVICs.
• Inhibition of PiT-1 using phosphonoformate hexahydrate acid abolished the ox-LDL-induced increase in BMP-2.
• These findings suggest PiT-1 mediates the osteogenic effects of ox-LDL.

Conclusions:

• Oxidized LDL induces an osteogenic phenotype in human AVICs.
• The phosphate transporter PiT-1 plays a key role in mediating ox-LDL-induced BMP-2 expression.
• These results provide mechanistic insight into the pathogenesis of calcific aortic stenosis.