Hyperlipidemia promotes osteoclastic potential of bone marrow cells ex vivo.
OBJECTIVE
Osteoporosis is associated epidemiologically with atherosclerosis and hyperlipidemia. We previously found that atherogenic lipids regulate bone formation. To determine whether hyperlipidemia also affects bone resorption, we compared osteoclastogenesis in marrow preosteoclasts derived from hyperlipidemic versus control mice.


METHODS
Nonadherent marrow cells from low-density lipoprotein receptor-/- (LDLR-/-)and C57BL/6J mice were cultured with M-CSF and ligand for receptor activator of nuclear factor-kappaB (RANKL). Functional osteoclastic activity, measured as number of resorption pits, was significantly greater in 12-month-old LDLR-/-. Similar results were obtained in 5- and 10-month-old LDLR-/- versus C57BL/6J mice on a high-fat diet. Osteoclastic differentiation, indicated by tartrate resistant acid phosphatase (TRAP) activity, was significantly greater in the 12-month-old LDLR-/-, and there was a trend toward increased TRAP activity in LDLR-/- on a high-fat diet, at ages 5 and 10 months. Osteoclastic parameters correlated with total serum lipoproteins with a possible threshold effect. Osteoporotic human cortical bone stained positive for lipids in the perivascular space of Haversian canals by oil red O. The presence of lipid hydroperoxides was detected in bone marrow from hyperlipidemic mice.


CONCLUSIONS
Hyperlipidemia may contribute to osteoporosis via increased osteoclastic bone resorption.
Tintut
Yin
Y
Department of Medicine, The David Geffen School of Medicine at UCLA, 10833 LeConte Avenue, Los Angeles, CA 90095-1679, USA. ytintut@mednet.ucla.edu
Morony
Sean
S
Demer
Linda L
LL
D000818:Animals; D001854:Bone Marrow Cells / Q000473:pathology*; D001862:Bone Resorption / Q000473:pathology; D002454:Cell Differentiation / Q000502:physiology*; D002478:Cells, Cultured; D004036:Diet, Atherogenic; D006949:Hyperlipidemias / Q000150:complications / Q000473:pathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D010010:Osteoclasts / Q000473:pathology*; D010024:Osteoporosis / Q000209:etiology / Q000473:pathology; D011973:Receptors, LDL / Q000172:deficiency; D013234:Stem Cells / Q000473:pathology
D011973:Receptors, LDL