Npp1 promotes atherosclerosis in ApoE knockout mice.

Area of Science:

• Cardiovascular Biology
• Molecular Genetics
• Atherosclerosis Research

Background:

• Ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (NPP1) generates pyrophosphate (PP(i)), an inhibitor of hydroxyapatite deposition.
• NPP1 deficiency is linked to severe arterial calcification and hyperplasia in humans.
• NPP1 influences arterial smooth muscle cell function and osteopontin (OPN) expression, potentially impacting atherogenesis.

Purpose of the Study:

• To investigate the role of NPP1 deficiency in modulating atherogenesis and atherosclerotic plaque calcification.
• To test the hypothesis that NPP1 deficiency impacts the development of atherosclerosis.

Main Methods:

• Generation of Npp1/ApoE double deficient mice by crossing Enpp1 mutant mice with ApoE null mice.
• Feeding mice a high-fat/high-cholesterol diet to induce atherosclerosis.
• Analysis of atherosclerotic lesion area and calcification at multiple time points (13, 18, 23, 28 weeks).
• Assessment of osteopontin (OPN) expression in aortic smooth muscle cells.

Main Results:

• Npp1/ApoE double deficient mice exhibited significantly smaller atherosclerotic lesions compared to ApoE null controls.
• Aortic smooth muscle cells from Npp1 deficient mice showed decreased OPN expression.
• Complete Npp1 deficiency (ttw/ttw) resulted in artery media calcification, while partial deficiency (ttw/+) showed a trend towards increased plaque calcification.

Conclusions:

• NPP1 promotes atherosclerosis in ApoE knockout mice, potentially mediated by OPN expression.
• While NPP1 deficiency reduces atherosclerotic lesions, it can lead to detrimental artery media calcification.
• The dual role of NPP1 in atherosclerosis and calcification warrants further investigation.