Abstract
Under physiological conditions, matrix metalloproteinases (MMPs) are involved in the remodeling and turnover of periodontal tissue and their activity is tightly regulated by tissue inhibitors of metalloproteinases (TIMPs). Disturbances in the balance between MMPs and TIMPs may result in excessive tissue destruction. We previously used an engineered human oral mucosa (EHOM) model to demonstrate that Porphyromonas gingivalis, a major etiological agent of periodontitis, infiltrates connective tissue and induces significant loss of attachment of the stratified epithelium from the basement membrane. The aim of the present study was to investigate the effect of P. gingivalis on the expression and production of MMP‐2, MMP‐9, TIMP‐1, and TIMP‐2 by oral fibroblasts and epithelial cells. The EHOM model was infected with P. gingivalis ATCC 33277 or its derivative gingipain‐null mutant (KDP128) for different periods of time. MMP and TIMP mRNA expression was evaluated by reverse transcription‐polymerase chain reaction (RT‐PCR) analysis, while protein secretion into the culture medium was assessed by enzyme‐linked immunosorbent assays. P. gingivalis significantly up‐regulated MMP‐2 and MMP‐9 mRNA expression by oral epithelial cells. This MMP gene activation was paralleled by TIMP‐2 gene activation. However, only MMP‐9 mRNA expression was significantly enhanced by the gingipain‐null mutant. At 8 and 24 h post‐infection, P. gingivalis increased significantly the MMP‐9 protein level compared to the uninfected EHOM model. The present study reports the ability of P. gingivalis to regulate MMP and TIMP production by oral cells, a phenomenon that may contribute to tissue destruction. J. Cell. Physiol. 211: 56–62, 2007. © 2007 Wiley‐Liss, Inc.