Common Underlying Mechanisms for Atherosclerosis and Osteoporosis

Like osteogenesis, arterial calcification is a regulated and complex process that involves the interactions of various cells producing matrix vesicles with subsequent mineralization. In fact, cells with osteoblastic potential have been isolated and cloned from bovine aortic media (Watson et al., 1994). These osteoblast-like cells in the vasculature are capable of calcifying vascular cells (Watson et al., 1994) (see Figure 58.1).

Several proteins are involved in both osteoporosis and atherosclerosis, such as osteocalcin (OC), matrix Gla protein (MGP), bone sialoprotein (BSP), bone morpho-genetic protein-2 and -4 (BMP -2, BMP -4), osteonectin (ON), osteopontin (OPN), osteoprotegerin (OPG), and receptor-activated nuclear Factor-Kappa B ligand (RANKL) (Dhore et al., 2001). Involvement of these

Osteoporosis Mechanism

Figure 58.1 Common cellular mechanisms underlying both vascular disease and osteoporosis. NO = Nitric oxide; eNOS = Endothelial nitric oxide synthase; INOS = Inducible nitric oxide synthase; Est = Estrogen; ox-LDL = Oxidized-low-density lipoprotein; HDL = High-density lipoprotein; OPG = osteoprotegerin; RANKL = receptor-activated nuclearfactor-kappa B ligand; RANK = Receptor-activated nuclearfactor-kappa B; BMP = Bone morphogenetic protein; MGP = Matrix Gla protein; OC = Osteocalcin; IL-6 = Interleukin-6; M-CSF = Macrophage-colonystimulating factor; IL-1 = Interleukin-1; TNF = Tumor necrosis factor; PGE2 = Prostaglandin E2; TGFjß = Transforming growth factor-beta; OPN = Osteopontin; CVC = Calcifying vascular cell; OLC = Osteoclast-like cell; Cbfa-1 = core-binding factor-a1; TRAIL = Tumor necrosis factor-related ligand.

Figure 58.1 Common cellular mechanisms underlying both vascular disease and osteoporosis. NO = Nitric oxide; eNOS = Endothelial nitric oxide synthase; INOS = Inducible nitric oxide synthase; Est = Estrogen; ox-LDL = Oxidized-low-density lipoprotein; HDL = High-density lipoprotein; OPG = osteoprotegerin; RANKL = receptor-activated nuclearfactor-kappa B ligand; RANK = Receptor-activated nuclearfactor-kappa B; BMP = Bone morphogenetic protein; MGP = Matrix Gla protein; OC = Osteocalcin; IL-6 = Interleukin-6; M-CSF = Macrophage-colonystimulating factor; IL-1 = Interleukin-1; TNF = Tumor necrosis factor; PGE2 = Prostaglandin E2; TGFjß = Transforming growth factor-beta; OPN = Osteopontin; CVC = Calcifying vascular cell; OLC = Osteoclast-like cell; Cbfa-1 = core-binding factor-a1; TRAIL = Tumor necrosis factor-related ligand.

proteins as well as the inflammatory cytokines in both disease processes suggest a common underlying pathophysiologic mechanism for osteoporosis and atherosclerosis (Dhore et al., 2001). Furthermore, osteoclast-like cells (OLCs) have been found in calcified arteries (Doherty et al., 2002) (see Figure 58.1). These cells may participate in normal mineral homeostasis in the arterial wall or may be recruited for the developing plaque (Doherty et al., 2002). Net calcium deposition occurs as a result of focal imbalance between osteoblast-like cells and OCLs (Doherty et al., 2002). Again this process in the vascular wall maintains similar mechanisms for arterial calcification analogous to those observed in the bone where a delicate balance is kept between osteoblastic and osteoclastic activities (see Figure 58.1).

Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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