Koyo Takimoto1, Nobuyuki Kawashima2, Noriyuki Suzuki1, Yu Koizumi1, Mioko Yamamoto1, Misako Nakashima3, Hideaki Suda1. 1. Department of Pulp Biology and Endodontics, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan. 2. Department of Pulp Biology and Endodontics, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan. Electronic address: kawashima.n.endo@tmd.ac.jp. 3. Department of Dental Regenerative Medicine, Center of Advanced Medicine for Dental and Oral Diseases, National Center for Geriatrics and Gerontology, Research Institute, Aichi, Japan.
Abstract
INTRODUCTION: Matrix metalloproteinase (MMP)-3 is a member of the MMP family that degrades the extracellular matrix. Application of MMP-3 to injured pulp tissue induces angiogenesis and wound healing, but its anti-inflammatory effects are still unclear. Here, we evaluated the anti-inflammatory functions of MMP-3 in vitro and in vivo. METHODS: Nitric oxide and inflammatory mediator synthesis in macrophages activated by lipopolysaccharide (LPS) was measured in the presence or absence of MMP-3. The mouse Mmp3 (mMmp3) expression vector containing full length cDNA sequence of mMmp3 or cDNA sequence of mMmp3 missing the signal peptide and pro-peptide regions was transfected to RAW264, a mouse macrophage cell line, and NO synthesis and inflammatory mediator expression were evaluated. Pulpal inflammation was histologically and immunohistochemically evaluated in a rat model of incisor pulpitis induced by the application of LPS for 9 hours in the presence or absence of MMP-3. RESULTS: NO and pro-inflammatory mediator synthesis promoted by LPS was significantly down-regulated by MMP-3 in vitro. The full length of mMmp3 down-regulated the LPS-induced NO synthesis and chemical mediator mRNA expression, however the mMmp3 missing the signal peptide failed to block the NO synthesis induced by LPS. The numbers of major histocompatibility complex class II+ and CD68+ cells, which infiltrated into the rat incisor pulp tissues in response to the topical application of LPS, were significantly decreased by the application of MMP-3 in vivo. CONCLUSIONS: These results indicate that MMP-3 possesses anti-inflammatory functions, suggesting its potential utility as an anti-inflammatory agent for pulpal inflammation.
INTRODUCTION:Matrix metalloproteinase (MMP)-3 is a member of the MMP family that degrades the extracellular matrix. Application of MMP-3 to injured pulp tissue induces angiogenesis and wound healing, but its anti-inflammatory effects are still unclear. Here, we evaluated the anti-inflammatory functions of MMP-3 in vitro and in vivo. METHODS:Nitric oxide and inflammatory mediator synthesis in macrophages activated by lipopolysaccharide (LPS) was measured in the presence or absence of MMP-3. The mouseMmp3 (mMmp3) expression vector containing full length cDNA sequence of mMmp3 or cDNA sequence of mMmp3 missing the signal peptide and pro-peptide regions was transfected to RAW264, a mouse macrophage cell line, and NO synthesis and inflammatory mediator expression were evaluated. Pulpal inflammation was histologically and immunohistochemically evaluated in a rat model of incisor pulpitis induced by the application of LPS for 9 hours in the presence or absence of MMP-3. RESULTS: NO and pro-inflammatory mediator synthesis promoted by LPS was significantly down-regulated by MMP-3 in vitro. The full length of mMmp3 down-regulated the LPS-induced NO synthesis and chemical mediator mRNA expression, however the mMmp3 missing the signal peptide failed to block the NO synthesis induced by LPS. The numbers of major histocompatibility complex class II+ and CD68+ cells, which infiltrated into the rat incisor pulp tissues in response to the topical application of LPS, were significantly decreased by the application of MMP-3 in vivo. CONCLUSIONS: These results indicate that MMP-3 possesses anti-inflammatory functions, suggesting its potential utility as an anti-inflammatory agent for pulpal inflammation.