The synthetic triterpenoid TP-222 inhibits RANKL stimulation of osteoclastogenesis and matrix metalloproteinase-9 expression.
OBJECTIVE
Receptor activator of nuclear factor-kappaB ligand (RANKL) promotes osteoclast differentiation from monocyte precursors by inducing a cohort of genes, including tartrate-resistant acid phosphatase (TRAP) and matrix metalloproteinase-9 (MMP-9). A family of synthetic triterpenoids with antiinflammatory and pro-apoptotic properties was described to modulate differentiation in monocytic cell lineages. We therefore investigated the ability of the potent and bioavailable synthetic triterpenoid TP-222 to inhibit RANKL-induced osteoclast formation and MMP-9 expression from monocytic precursor cells.


METHODS
Osteoclast formation was assayed by staining for TRAP-positive multinucleated cells. MMP-9 expression was measured by quantitative RT-PCR, Western blot, immunohistochemistry, and gel zymography. In vivo effects of TP-222 were assessed by daily intraperitoneal injection of 4-week-old mice for 7 days followed by measurement of osteoclast number and MMP-9 expression at the cartilage/bone junction of the epiphyseal growth plate.


RESULTS
RANKL promoted and TP-222 (300 nM) inhibited osteoclast formation in cultures of RAW264.7 cells or bone marrow-derived monocytes. RANKL also induced MMP-9 expression in RAW264.7 cells and this was reduced by concurrent or subsequent addition of TP-222. TP-222 treatment significantly reduced the mean number of osteoclasts present at the cartilage/bone interface compared to vehicle-injected control mice. Morphometric analyses of tissue sections showed that TP-222 treatment reduced the amount of immunoreactive MMP-9 present in both mononucleated pre-osteoclasts and osteoclasts.


CONCLUSIONS
Our data demonstrate that TP-222 inhibits osteoclast formation and MMP-9 expression in vitro and in vivo, and suggest that triterpenoids may be useful compounds for modulating bone resorption diseases.
Fava
Roy A
RA
Research Service, Veterans Affairs Medical Center, White River Junction, Vermont, USA.
Elliott
Sarah
S
Raymond
Lauren
L
Mollmark
Jessica
J
Hays
Ezra
E
Honda
Tadashi
T
Gribble
Gordon W
GW
Sporn
Michael B
MB
Vincenti
Matthew P
MP
D000818:Animals; D001854:Bone Marrow Cells / Q000187:drug effects / Q000378:metabolism; D001862:Bone Resorption / Q000188:drug therapy / Q000201:enzymology; D002452:Cell Count; D002460:Cell Line; D004338:Drug Combinations; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D007274:Injections, Intraperitoneal; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism; D009569:Nitric Oxide / Q000037:antagonists & inhibitors; D010010:Osteoclasts / Q000187:drug effects* / Q000201:enzymology; D010012:Osteogenesis / Q000187:drug effects; D053245:RANK Ligand / Q000037:antagonists & inhibitors*; D012333:RNA, Messenger / Q000378:metabolism; D014315:Triterpenes / Q000494:pharmacology*
D004338:Drug Combinations; D004791:Enzyme Inhibitors; D053245:RANK Ligand; D012333:RNA, Messenger; D014315:Triterpenes; C520592:triterpenoid TP-222; D009569:Nitric Oxide; D020780:Matrix Metalloproteinase 9