[Tumor necrosis factor and lipopolysaccharide affect periodontal ligament cells expressing osteoprotegerin in vitro].
OBJECTIVE
To investigate the effects of LPS and/or TNF-alpha on periodontal ligament cell (PDLC) proliferation and OPG secretion.


METHODS
Healthy premolars extracted for orthodontic reasons from a 12 years old boy were obtained, and periodontal tissues were collected and cultured to obtain PDLCs. Cloned PDLCs were obtained by means of limited dilutions, and were characterized as follows: alkaline phosphatase activity, collagen III production and bone-like nodules formation. LPS and rhTNF-alpha were added into culture media and their effects on PDLC proliferation and OPG secretion were observed. The OPG concentrations in cell culture supernatants were detected by sandwich ELISA. Living cell numbers were demonstrated by MTT test. The average levels of OPG secretion by a single cell were calculated by dividing OPG concentration with MTT result.


RESULTS
rhTNF-alpha above 10 micro g/L decreased the mtt and opg detecting results, but increased the opg/mtt values (P < 0.05). However, LPS had no effect on mtt, opg or opg/mtt values. Neither it had any interaction with rhTNF-alpha (P > 0.05).


CONCLUSIONS
TNF-alpha prohibits the proliferation of PDLCs but enhances their OPG secretion. However, LPS has no effect on neither side. Our works support the hypothesis that there may be an inverse feedback regulation pattern of increasing periodontal OPG production against local bone resorption activity. PDLCs might not be the natural target cells of LPS' direct cytotoxic effect.
Li
Jing-ping
JP
Department of Periodontics, Guanghua College of Stomatology, Sun Yat-sen University, Guangzhou 510060, China.
Ling
Jun-qi
JQ
D002648:Child; D006023:Glycoproteins / Q000096:biosynthesis* / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008297:Male; D053244:Osteoprotegerin; D010513:Periodontal Ligament / Q000378:metabolism* / Q000473:pathology; D018160:Receptors, Cytoplasmic and Nuclear / Q000096:biosynthesis* / Q000187:drug effects; D018124:Receptors, Tumor Necrosis Factor / Q000096:biosynthesis* / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D006023:Glycoproteins; D008070:Lipopolysaccharides; D053244:Osteoprotegerin; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; C506030:TNFRSF11B protein, human; D014409:Tumor Necrosis Factor-alpha