acid-phosphatase and Atherosclerosis

Vascular calcification is a hallmark of atherosclerosis, a major cause of morbidity and mortality in the United States. We have previously reported that the osteogenic transcription factor Runx2 is an essential and sufficient regulator of calcification of vascular smooth muscle cells (VSMC) in vitro.. To determine the contribution of osteogenic differentiation of VSMC to the pathogenesis of vascular calcification and the function of VSMC-derived Runx2 in regulating calcification in vivo.. SMC-specific Runx2-deficient mice, generated by breeding SM22α-Cre mice with the Runx2 exon 8 floxed mice, exhibited normal aortic gross anatomy and expression levels of SMC-specific marker genes. Runx2 deficiency did not affect basal SMC markers, but inhibited oxidative stress-reduced expression of SMC markers. High-fat-diet-induced vascular calcification in vivo was markedly inhibited in the Runx2-deficient mice in comparison with their control littermates. Runx2 deficiency inhibited the expression of receptor activator of nuclear factor κB ligand, which was accompanied by decreased macrophage infiltration and formation of osteoclast-like cells in the calcified lesions. Coculture of VSMC with bone marrow-derived macrophages demonstrated that the Runx2-deficient VSMC failed to promote differentiation of macrophages into osteoclast-like cells.. These data have determined the importance of osteogenic differentiation of VSMC in the pathogenesis of vascular calcification in mice and defined the functional role of SMC-derived Runx2 in regulating vascular calcification and promoting infiltration of macrophages into the calcified lesion to form osteoclast-like cells. Our studies suggest that the development of vascular calcification is coupled with the formation of osteoclast-like cells, paralleling the bone remodeling process.

Topics: Acid Phosphatase; Animals; Atherosclerosis; Bone Remodeling; Calcinosis; Cell Differentiation; Cells, Cultured; Coculture Techniques; Core Binding Factor Alpha 1 Subunit; Diet, High-Fat; Disease Models, Animal; Exons; Female; Isoenzymes; Macrophages; Male; Mice; Mice, Knockout; Muscle, Smooth, Vascular; Mutagenesis; Osteoclasts; RANK Ligand; Tartrate-Resistant Acid Phosphatase

Clinical and experimental studies demonstrate the important roles of vascular smooth muscle cells (VSMC) in the pathogenesis of atherosclerosis. We have previously determined that the osteogenic transcription factor Runx2 is essential for VSMC calcification. The present study characterized Runx2-regulated signals and their potential roles in vascular calcification.. In vivo studies with atherogenic apolipoprotein E(-/-) mice demonstrated that increased oxidative stress was associated with upregulation of Runx2 and receptor activator of nuclear factor κB ligand (RANKL), which colocalized in the calcified atherosclerotic lesions and were juxtaposed to infiltrated macrophages and osteoclast-like cells that are positively stained for an osteoclast marker, tartrate-resistant acid phosphatase. Mechanistic studies using RNA interference, a luciferase reporter system, chromatin immunoprecipitation, and electrophoretic mobility shift assays indicated that Runx2 regulated the expression of RANKL via a direct binding to the 5'-flanking region of the RANKL. Functional characterization revealed that RANKL did not induce VSMC calcification, nor was RANKL required for oxidative stress-induced VSMC calcification. Using a coculture system, we demonstrated that VSMC-expressed RANKL induced migration as well as differentiation of bone marrow-derived macrophages into multinucleated, tartrate-resistant acid phosphatase-positive osteoclast-like cells. These effects were inhibited by the RANKL antagonist osteoprotegerin and with VSMC deficient in Runx2 or RANKL.. We demonstrate that Runx2 directly binds to the promoter and controls the expression of RANKL, which mediates the crosstalk between calcifying VSMC and migration and differentiation of macrophages into osteoclast-like cells in the atherosclerotic lesions. Our studies provide novel mechanistic insights into the regulation and function of VSMC-derived RANKL in the pathogenesis of atherosclerosis and vascular calcification.

Topics: Acid Phosphatase; Animals; Atherosclerosis; Calcinosis; Cell Differentiation; Cell Movement; Core Binding Factor Alpha 1 Subunit; Gene Expression Regulation; Isoenzymes; Macrophages; Mice; Mice, Inbred C57BL; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Osteoclasts; Oxidative Stress; Promoter Regions, Genetic; Protein Binding; RANK Ligand; Tartrate-Resistant Acid Phosphatase; Vascular Diseases

To study the most frequent markers of mineral-bone metabolism in young hemodialysis (HD) patients in order to detect any metabolism changes that could lead to the atherosclerosis and extravascular calcification frequently observed in chronic kidney disease (CKD) patients and estimate their potential prognostic significance.. We measured serum levels of intact-PTH (iPTH), Osteoprotegerin (OPG), total soluble receptor activator of nuclear factor-κB ligand (sRANKL), tartrate-resistant acid phosphatase (TRAP-5b), osteocalcin (Oc), bone-specific alkaline phosphatase (BAP), calcium, phosphorus, 25(OH)D(3) and 1,25 (0H)(2)D(3) in young HD patients and controls. In comparison to controls, serum OPG, iPTH, BAP, phosphorus, and osteocalcin levels were higher whereas 25(OH)D(3) and 1,25(OH)(2)D(3) were lower in HD patients.. In conclusion, our results indicate that bone formation and resorption parameters are already altered in young HD subjects. These changes may lead to vascular calcifications and cardiovascular complications, given that elevated OPG levels predict cardiovascular events in HD patients. Furthermore, low levels of vitamin D metabolites have been associated with the presence of vascular calcification.

Topics: Acid Phosphatase; Adolescent; Adult; Alkaline Phosphatase; Atherosclerosis; Biomarkers; Bone and Bones; Bone Density; Calcifediol; Calcitriol; Calcium; Case-Control Studies; Humans; Isoenzymes; Kidney Failure, Chronic; Osteocalcin; Osteoprotegerin; Parathyroid Hormone; Phosphorus; Prognosis; RANK Ligand; Renal Dialysis; Tartrate-Resistant Acid Phosphatase; Young Adult

Carbonic anhydrases (CA) play a central role in osteoclast function and bone remodeling by catalyzing the formation of bicarbonate and proton from carbon dioxide. According to previous histochemical studies, advanced atherosclerotic plaques share similarities with bone. However, whether CAs are expressed in plaques is not known.. Whole genome expression array of arterial samples (n = 24) confirmed that several genes indicating osteoblastogenesis and osteoclastogenesis were up-regulated in plaques when compared to control vessel samples from internal thoracic arteries (n = 6), including CA2 and CA12, expression of which was also verified with quantitative reverse transcription polymerase chain reaction (RT-PCR). In atherosclerotic plaques there was 11.6-fold (P < 0.0001) and 11.4-fold (P < 0.0001) up-regulation of CA2 and CA12, compared to controls, respectively. According to quantitative PCR, CA2 expression was elevated in carotid (12.3-fold, P < 0.0001), femoral (13.2-fold, P < 0.01), and aortic plaques (7.5-fold, P < 0.0001). CA12 expression was elevated in carotid (11.6-fold, P < 0.0001), femoral (11.5-fold, P < 0.01), and aortic plaques (9.7-fold, P < 0.0001). CAII, CAXII, and CD68 and tartrate-resistant acid phosphatase (TRAP), a marker of osteoclast-like cells, were found to be co-localized in multinucleated giant cells in the atherosclerotic plaques using immunohistochemistry and double-staining immunofluorescence analysis.. The present findings provide evidence for the involvement of CAs in advanced atherosclerosis in osteoclast-like cells of monocyte-macrophage lineage.

Topics: Acid Phosphatase; Aged; Aged, 80 and over; Antigens, CD; Antigens, Differentiation, Myelomonocytic; Atherosclerosis; Carbonic Anhydrase II; Carbonic Anhydrases; Female; Gene Expression Profiling; Genome-Wide Association Study; Giant Cells; Humans; Isoenzymes; Macrophages; Male; Middle Aged; Monocytes; Osteoclasts; Reverse Transcriptase Polymerase Chain Reaction; Tartrate-Resistant Acid Phosphatase; Up-Regulation

Topics: Acid Phosphatase; Alkaline Phosphatase; Animals; Arteriosclerosis; Atherosclerosis; Lagomorpha; Rabbits