Monocyte/macrophage regulation of vascular calcification in vitro.
BACKGROUND
Calcification is a common complication of atherosclerosis and other chronic inflammatory processes that involves infiltration of monocytes and accumulation of macrophages.


RESULTS
To determine whether these cells modulate vascular calcification in vitro, calcifying vascular cells (CVCs), a subpopulation of osteoblast-like cells derived from the artery wall, were cocultured with human peripheral blood monocytes for 5 days. Results showed that alkaline phosphatase (ALP) activity, a marker of osteoblastic differentiation, was significantly greater in cocultures than in cultures of CVCs or monocytes alone. Both ALP activity and matrix mineralization increased in proportion to the number of monocytes added. Activation of monocyte/macrophages (M/Ms) by oxidized LDL further increased ALP activity in cocultures. However, neither conditioned medium from oxidized-LDL-activated M/Ms or transwell coculture had this effect on CVCs, which suggests a need for cell-to-cell contact. In contrast, conditioned medium from lipopolysaccharide-activated M/Ms increased ALP activity of CVCs. ELISA showed that lipopolysaccharide-activated M/Ms secreted tumor necrosis factor-alpha, and neutralizing antibody to tumor necrosis factor-alpha attenuated the induction of ALP activity by the conditioned media.


CONCLUSIONS
These results suggest that M/Ms enhance in vitro vascular calcification via 2 independent mechanisms: cell-cell interaction and production of soluble factors such as tumor necrosis factor-alpha.
Tintut
Yin
Y
Department of Medicine, UCLA School of Medicine, Los Angeles, California, USA.
Patel
Jignesh
J
Territo
Mary
M
Saini
Trishal
T
Parhami
Farhad
F
Demer
Linda L
LL
D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001011:Aorta / Q000166:cytology / Q000378:metabolism*; D001161:Arteriosclerosis / Q000150:complications; D002114:Calcinosis / Q000150:complications / Q000378:metabolism*; D002417:Cattle; D002450:Cell Communication / Q000187:drug effects; D002452:Cell Count; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D018920:Coculture Techniques; D017077:Culture Media, Conditioned / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D008077:Lipoproteins, LDL / Q000494:pharmacology; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009000:Monocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010006:Osteoblasts / Q000166:cytology / Q000201:enzymology*; D013234:Stem Cells / Q000166:cytology / Q000201:enzymology; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
D017077:Culture Media, Conditioned; D008070:Lipopolysaccharides; D008077:Lipoproteins, LDL; D014409:Tumor Necrosis Factor-alpha; C099252:oxidized low density lipoprotein; D000469:Alkaline Phosphatase