Atorvastatin Inhibits Hypercholesterolemia-Induced Cellular Proliferation and Bone Matrix Production in the Rabbit Aortic Valve

Background—Despite the common occurrence of aortic stenosis, the cellular causes of the disorder are unknown, in part because of the absence of experimental models. We hypothesized that atherosclerosis and early bone matrix expression in the aortic valve occurs secondary to experimental hypercholesterolemia and that treatment with atorvastatin modifies this transformation. Methods and Results—To test this hypothesis, we developed an experimental hypercholesterolemic rabbit model. New Zealand White rabbits (n=48) were studied: group 1 (n=16), normal diet; group 2 (n=16), 1% (wt/wt) cholesterol diet; and group 3 (n=16), 1% (wt/wt) cholesterol diet plus atorvastatin (3 mg/kg per day). The aortic valves were examined with hematoxylin and eosin stain, Masson trichrome, macrophage (RAM 11), proliferation cell nuclear antigen (PCNA), and osteopontin immunostains. Cholesterol and highly sensitive C-reactive protein (hsCRP) serum levels were obtained by standard assays. Computerized morphometry and digital image analysis were performed for quantifying PCNA (% area). Electron microscopy and immunogold labeling were performed for osteopontin. Semiquantitative RT-PCR was performed for the osteoblast bone markers [alkaline phosphatase, osteopontin, and osteoblast lineage-specific transcription factor (Cbfa-1)]. There was an increase in cholesterol, hsCRP, PCNA, RAM 11, and osteopontin and osteoblast gene markers (alkaline phosphatase, osteopontin, and Cbfa-1) in the cholesterol-fed rabbits compared with control rabbits. All markers except hsCRP were reduced by atorvastatin. Conclusions—These findings of increased macrophages, PCNA levels, and bone matrix proteins in the aortic valve during experimental hypercholesterolemia provide evidence of a proliferative atherosclerosis–like process in the aortic valve associated with the transformation to an osteoblast-like phenotype that is inhibited by atorvastatin.

[1]  M. Lauer,et al.  Effect of Hydroxymethylglutaryl Coenzyme A Reductase Inhibitors on the Progression of Calcific Aortic Stenosis , 2001, Circulation.

[2]  S. Achenbach,et al.  Progression of Aortic Valve Calcification: Association with Coronary Progression of Aortic Valve Calcification Association with Coronary Atherosclerosis and Cardiovascular Risk Factors , 2022 .

[3]  A. Pietroiusti,et al.  C-reactive protein is increased in patients with degenerative aortic valvular stenosis. , 2001, Journal of the American College of Cardiology.

[4]  J. Cheville,et al.  Predicting prostate carcinoma volume and stage at radical prostatectomy by assessing needle biopsy specimens for percent surface area and cores positive for carcinoma, perineural invasion, Gleason score, DNA ploidy and proliferation, and preoperative serum prostate specific antigen , 2001 .

[5]  A. Tajik,et al.  Experimental hypercholesterolemia induces apoptosis in the aortic valve. , 2001, The Journal of heart valve disease.

[6]  S. Grundy,et al.  Effect of Hydroxymethyl Glutaryl Coenzyme A Reductase Inhibitor Therapy on High Sensitive C-Reactive Protein Levels , 2001, Circulation.

[7]  Emile R. Mohler,et al.  Bone Formation and Inflammation in Cardiac Valves , 2001, Circulation.

[8]  G. Karsenty,et al.  The osteoblast: a sophisticated fibroblast under central surveillance. , 2000, Science.

[9]  E. Moran,et al.  Phosphate is a specific signal for induction of osteopontin gene expression. , 2000, Proceedings of the National Academy of Sciences of the United States of America.

[10]  G. Karsenty,et al.  Cbfa1 as a regulator of osteoblast differentiation and function. , 1999, Bone.

[11]  R. Levy,et al.  Identification and characterization of calcifying valve cells from human and canine aortic valves. , 1999, The Journal of heart valve disease.

[12]  J. Egido,et al.  HMG-CoA reductase inhibition by atorvastatin reduces neointimal inflammation in a rabbit model of atherosclerosis. , 1998, Journal of the American College of Cardiology.

[13]  G Burnstock,et al.  Watanabe rabbits with heritable hypercholesterolaemia: a model of atherosclerosis. , 1998, Histology and histopathology.

[14]  A. Iguchi,et al.  Characteristics of macrophage-derived foam cells isolated from atherosclerotic lesions of rabbits. , 1997, Atherosclerosis.

[15]  Makoto Sato,et al.  Targeted Disruption of Cbfa1 Results in a Complete Lack of Bone Formation owing to Maturational Arrest of Osteoblasts , 1997, Cell.

[16]  G. Karsenty,et al.  Osf2/Cbfa1: A Transcriptional Activator of Osteoblast Differentiation , 1997, Cell.

[17]  F. Parhami,et al.  Lipid oxidation products have opposite effects on calcifying vascular cell and bone cell differentiation. A possible explanation for the paradox of arterial calcification in osteoporotic patients. , 1997, Arteriosclerosis, thrombosis, and vascular biology.

[18]  Catherine M. Otto,et al.  Clinical Factors Associated With Calcific Aortic Valve Disease , 1997 .

[19]  E. Mohler,et al.  Detection of osteopontin in calcified human aortic valves. , 1997, Arteriosclerosis, thrombosis, and vascular biology.

[20]  Bonnie K. Lind,et al.  Clinical factors associated with calcific aortic valve disease. Cardiovascular Health Study. , 1997, Journal of the American College of Cardiology.

[21]  Allan Bradley,et al.  Increased bone formation in osteocalcin-deficient mice , 1996, Nature.

[22]  C. Otto,et al.  Apolipoproteins B, (a), and E accumulate in the morphologically early lesion of 'degenerative' valvular aortic stenosis. , 1996, Arteriosclerosis, thrombosis, and vascular biology.

[23]  B. Riggs,et al.  Isolation and characterization of osteoblast precursor cells from human bone marrow , 1996, Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research.

[24]  T. Sebo,et al.  Digital image analysis. , 1995, Mayo Clinic proceedings.

[25]  J. Hoeg,et al.  Detection and quantitation of calcific atherosclerosis by ultrafast computed tomography in children and young adults with homozygous familial hypercholesterolemia. , 1994, Arteriosclerosis and thrombosis : a journal of vascular biology.

[26]  R. Kernoff,et al.  Cell proliferation after balloon injury of iliac arteries in the cholesterol-fed New Zealand White rabbit. , 1994, Arteriosclerosis and thrombosis : a journal of vascular biology.

[27]  S. Schwartz,et al.  Molecular cloning and characterization of 2B7, a rat mRNA which distinguishes smooth muscle cell phenotypes in vitro and is identical to osteopontin (secreted phosphoprotein I, 2aR). , 1991, Biochemical and biophysical research communications.

[28]  M. Solursh,et al.  Bone acidic glycoprotein-75 is a major synthetic product of osteoblastic cells and localized as 75- and/or 50-kDa forms in mineralized phases of bone and growth plate and in serum. , 1990, The Journal of biological chemistry.

[29]  S. Grundy.  Hyperlipoproteinemia: metabolic basis and rationale for therapy. , 1984, The American journal of cardiology.

[30]  B. McManus,et al.  Cardiovascular features of homozygous familial hypercholesterolemia: analysis of 16 patients. , 1984, The American journal of cardiology.