title: The expression of MMP-8 in human odontoblasts and dental pulp cells is down-regulated by TGF-beta1.
abstract: Recent findings show that matrix metalloproteinase-8 (MMP-8) is expressed, in addition to neutrophils, by human chondrocytes, cultured fibroblasts, and endothelial cells. We investigated the expression of MMP-8 in other human mesenchyme-derived cells, odontoblasts, and pulp tissue. Odontoblasts and pulp tissue were collected from extracted human teeth for MMP-8 mRNA analysis with reverse-transcription/polymerase chain-reaction (RT-PCR) and Southern blot. The expression, localization, and secretion of MMP-8 protein were studied with Western blot, immunohistochemistry, and immunofluorometric assay. The effect of TGF-beta1 (10 ng/mL) on the expression, secretion, and concentration of secreted MMP-8 was studied by odontoblast and pulp tissue culture methods (Tjäderhane et al., 1998a). RT-PCR demonstrated MMP-8 mRNA expression in native and cultured odontoblasts and pulp tissue and cultured pulp fibroblasts, with a 522-bp transcript comparable with that of bone marrow cells. The specificity of PCR was confirmed with Southern blot. Western blot with MMP-8-specific antibody detected 65- and 50-kDa proteins in native samples, representing latent and active forms of mesenchymal-type MMP-8, and in the conditioned odontoblast culture media, 50-kDa protein was observed. TGF-beta down-regulated the MMP-8 mRNA and concentration of secreted protein in both cultures. Immunohistochemical staining detected MMP-8 in odontoblasts. These findings indicate that mesenchyme-derived cells of the dentin-pulp complex express, synthesize, and activate MMP-8, which may, in concert with odontoblast-derived gelatinases, participate in organization of dentin organic matrix prior to mineralization.
authors.affiliation: Institute of Dentistry, University of Oulu, Finland. Ist@cc.oulu.fi
authors.forename: H
authors.initials: H
authors.lastname: Palosaari
authors.forename: J
authors.initials: J
authors.lastname: Wahlgren
authors.forename: M
authors.initials: M
authors.lastname: Larmas
authors.forename: H
authors.initials: H
authors.lastname: Rönkä
authors.forename: T
authors.initials: T
authors.lastname: Sorsa
authors.forename: T
authors.initials: T
authors.lastname: Salo
authors.forename: L
authors.initials: L
authors.lastname: Tjäderhane
mesh_terms: D015139:Blotting, Southern / Q000379:methods; D015153:Blotting, Western / Q000379:methods; D018929:Cell Culture Techniques / Q000379:methods; D002478:Cells, Cultured; D003782:Dental Pulp / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015536:Down-Regulation / Q000187:drug effects / Q000502:physiology*; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D015200:Fluoroimmunoassay / Q000379:methods; D006801:Humans; D007150:Immunohistochemistry; D020784:Matrix Metalloproteinase 8 / Q000187:drug effects / Q000378:metabolism*; D009804:Odontoblasts / Q000187:drug effects / Q000378:metabolism*; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
chemical_list: D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D020784:Matrix Metalloproteinase 8