Induction of MMP-2 at the interface between epithelial cells and fibroblasts from human periodontal ligament.
OBJECTIVE
MMP-2 can degrade type IV collagen and MMP-14 can activate pro MMP-2. The present study was undertaken to examine the expression of MMP-2 and MMP-14 with respect to interaction between the cells of the epithelial rests of Malassez and fibroblasts from human periodontal ligament.


METHODS
Explants of human periodontal ligament tissues produced outgrowths containing both putative epithelial rests of Malassez cells and human periodontal ligament fibroblasts after incubation in a modified serum-free medium. The distribution and expression of MMP-2 and MMP-14 were analysed using immunohistochemistry, in situ hybridization and RT-PCR analysis. The conditioned media and cell extracts were collected for western blot analysis for MMP-2.


RESULTS
Putative epithelial rests of Malassez cells at the interface between the cells of the epithelial rests of Malassez and fibroblasts expressed MMP-2 and MMP-14 strongly. However, in situ hybridization analysis revealed that human periodontal ligament fibroblasts expressed MMP-2 mRNA while putative epithelial rests of Malassez cells expressed MMP-14 mRNA at the interface. The RT-PCR analysis showed that the expression of MMP-2 mRNA was significantly higher when putative epithelial rests of Malassez cells and human periodontal ligament fibroblasts were cultured together than when cultured alone. Western blot analysis showed that the active form of MMP-2 was detected at higher levels in the conditioned medium of the co-cultured cells.


CONCLUSIONS
These findings indicate that putative epithelial rests of Malassez cells stimulate the production of MMP-2 in human periodontal ligament fibroblasts. Up-regulated proMMP-2 bound by MMP-14 expressed in epithelial rests of Malassez cells can degrade matrix molecules, such as type IV collagen, in the basal membrane between putative epithelial rests of Malassez cells and human periodontal ligament fibroblasts.
Shimonishi
M
M
Division of Comprehensive Dentistry, Tohoku University Dental Hospital, Sendai, Japan. shimo@ddh.tohoku.ac.jp
Takahashi
I
I
Terao
F
F
Komatsu
M
M
Kikuchi
M
M
D000293:Adolescent; D000328:Adult; D053523:Amelogenin / Q000032:analysis; D001485:Basement Membrane / Q000201:enzymology; D015153:Blotting, Western; D018929:Cell Culture Techniques; D018920:Coculture Techniques; D024141:Collagen Type IV / Q000032:analysis; D017077:Culture Media, Conditioned; D016895:Culture Media, Serum-Free; D004792:Enzyme Precursors / Q000032:analysis / Q000378:metabolism; D004847:Epithelial Cells / Q000201:enzymology; D005110:Extracellular Space / Q000201:enzymology; D005347:Fibroblasts / Q000201:enzymology; D018093:Gelatinases / Q000032:analysis / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D053511:Matrix Metalloproteinase 14 / Q000032:analysis / Q000378:metabolism; D020778:Matrix Metalloproteinase 2 / Q000032:analysis / Q000378:metabolism*; D010513:Periodontal Ligament / Q000166:cytology* / Q000201:enzymology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation; D055815:Young Adult
D053523:Amelogenin; D024141:Collagen Type IV; D017077:Culture Media, Conditioned; D016895:Culture Media, Serum-Free; D004792:Enzyme Precursors; D018093:Gelatinases; C069860:progelatinase; C522361:MMP2 protein, human; D020778:Matrix Metalloproteinase 2; C507086:MMP14 protein, human; D053511:Matrix Metalloproteinase 14