Open AccessPorphyromonas gingivalis Lipids Inhibit Osteoblastic Differentiation and Function
Author(s) -
YuHsiung Wang,
Jin Jiang,
Qiang Zhu,
Amer Z. AlAnezi,
Robert B. Clark,
Xi Jiang,
David W. Rowe,
Frank C. Nichols
Publication year - 2010
Publication title -
infection and immunity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.508
H-Index - 220
eISSN - 1070-6313
pISSN - 0019-9567
DOI - 10.1128/iai.00225-10
Subject(s) - osteoblast , porphyromonas gingivalis , rankl , runx2 , biology , tlr2 , microbiology and biotechnology , chemistry , biochemistry , signal transduction , receptor , in vitro , tlr4 , genetics , activator (genetics) , bacteria
Porphyromonas gingivalis produces unusual sphingolipids that are known to promote inflammatory reactions in gingival fibroblasts and Toll-like receptor 2 (TLR2)-dependent secretion of interleukin-6 from dendritic cells. The aim of the present study was to examine whetherP. gingivalis lipids inhibit osteoblastic function. Total lipids fromP. gingivalis and two fractions, phosphoglycerol dihydroceramides and phosphoethanolamine dihydroceramides, were prepared free of lipid A. Primary calvarial osteoblast cultures derived from 5- to 7-day-old CD-1 mice were used to examine the effects ofP. gingivalis lipids on mineralized nodule formation, cell viability, apoptosis, cell proliferation, and gene expression.P. gingivalis lipids inhibited osteoblast differentiation and fluorescence expression of pOBCol2.3GFP in a concentration-dependent manner. However,P. gingivalis lipids did not significantly alter osteoblast proliferation, viability, or apoptosis. When administered during specific intervals of osteoblast growth,P. gingivalis total lipids demonstrated inhibitory effects on osteoblast differentiation only after the proliferation stage of culture. Reverse transcription-PCR confirmed the downregulation of osteoblast marker genes, including Runx2, ALP, OC, BSP, OPG, and DMP-1, with concurrent upregulation of RANKL, tumor necrosis factor alpha, and MMP-3 genes.P. gingivalis total lipids and lipid fractions inhibited calvarial osteoblast gene expression and functionin vivo , as determined by the loss of expression of another osteoblast differentiation reporter, pOBCol3.6GFPcyan, and reduced uptake of Alizarin complexone stain. Finally, lipid inhibition of mineral nodule formationin vitro was dependent on TLR2 expression. Our results indicate that inhibition of osteoblast function and gene expression byP. gingivalis lipids represents a novel mechanism for altering alveolar bone homeostasis at periodontal disease sites.