Tomohiro Ninomiya

Interleukin-1α-dependent Regulation of Matrix Metalloproteinase-9 (MMP-9) Secretion and Activation in the Epithelial Cells of Odontogenic Jaw Cysts:

Interleukin-la (IL-1α) and matrix metalloproteinase-9 (MMP-9) are thought to be involved in odontogenic cyst expansion. In this study, we investigated the effects of IL-1α on the secretion and activation of MMP-9 in odontogenic jaw cysts. An active form of MMP-9 was present in odontogenic keratocyst (6 of 8 cases) fluids more frequently than dentigerous cyst (3 of 10 cases) and radicular cyst (3 of 10 cases) fluids, although proMMP-9 was present in all cyst fluids. Odontogenic keratocyst fragments in explant culture secreted a larger amount of IL-1α than dentigerous cyst and radicular cyst fragments in explant culture, and spontaneously secreted both proMMP-9 and an active form of MMP-9. The fragments of dentigerous cysts and radicular cysts secreted a small amount of proMMP-9, but no active form of MMP-9. Exogenously added recombinant human IL-1α (rhIL-la) increased the secretion and activation of proMMP-9 in the fragments of dentigerous cysts and radicular cysts. The epithelial cells isolated from odontogenic keratocysts secreted IL-la and proMMP-9 without stimulation. Under the cultivation on a fibronectin-coated dish, rhIL-la increased the secretion of proMMP-9 from the epithelial cells in a dose-dependent manner. Moreover, rhIL-la induced the secretion of proMMP-3 and plasminogen activator urokinase (u-PA) from the epithelial cells, and converted the secreted proMMP-3 to the active form in the presence of plasminogen. The secreted proMMP-9 was also activated in the presence of rhIL-la and plasminogen. Hence, our results suggest that IL-1α may up-regulate not only proMMP-9 secretion but also proMMP-9 activation by inducing proMMP-3 and u-PA production in the cyst epithelial cells by autocrine/paracrine regulatory mechanisms.

Signaling Pathways Regulating IL-1α-induced COX-2 Expression

Interleukin-1α(IL-1α) stimulates the production of prostaglandin E2 (PGE2) in odontogenic keratocyst fibroblasts. However, the signaling pathways remain obscure. In this study, we investigated IL-1αsignaling pathways that regulate cyclooxygenase-2 (COX-2) expression in odontogenic keratocyst fibroblasts. IL-1αincreased the expression of COX-2 mRNA and protein, and PGE2 secretion in the fibroblasts. IL-1αincreased the phosphorylation of extracellular signal-regulated protein kinase-1/2 (ERK1/2), p38 mitogen-activated protein kinase (MAPK), and c-Jun N-terminal kinase (JNK). PD-98059, SB-203580, SP-600125, and PDTC—which are inhibitors of ERK1/2, p38, JNK, and nuclear factor-κB (NF-κB), respectively—attenuated the IL-1α-induced COX-2 mRNA expression and activated protein kinase C PGE2 secretion. IL-1α(PKC), and PKC inhibitor staurosporine inhibited IL-1α-induced phosphorylation of ERK1/2, p38, and JNK, and decreased IL-1α-induced COX-2 mRNA expression. Thus, in odontogenic keratocyst fibroblasts, IL-1αmay stimulate COX-2 expression both through the PKC-dependent activation of ERK1/2, p38, and JNK signaling pathways, and through the NF-κB cascade.

Effects of Positive Pressure in Odontogenic Keratocysts

Intracystic fluid pressure is thought to be involved in odontogenic cyst growth. In this study, we investigated the effects of positive pressure on the expression of interleukin-1α (IL-1α), matrix metalloproteinases (MMPs), and prostaglandin E2 (PGE2) in odontogenic keratocysts to determine whether this pressure stimulates inflammatory cytokine production and signaling of osteoclastogenic events. Positive pressure enhanced the expression of IL-1α mRNA and protein in odontogenic keratocyst epithelial cells, and increased the secretion of MMP-1, MMP-2, MMP-3, and PGE2 in a co-culture of odontogenic keratocyst fibroblasts and the epithelial cells. The pressure-induced secretions were inhibited by an interleukin-1 receptor antagonist. Recombinant human interleukin-1α (rhIL-1α) increased the secretion of MMP-1, MMP-2, MMP-3, and PGE2 in the fibroblasts. Furthermore, in the fibroblasts, rhIL-1α enhanced the expression of macrophage colony-stimulating factor (M-CSF) mRNA, and rhIL-1α-induced PGE2 increased the expression of nuclear factor κB ligand (RANKL) mRNA. Thus, positive pressure may play a crucial role in odontogenic keratocyst growth via stimulating the expression of IL-1α in epithelial cells.

Marsupialisation for keratocystic odontogenic tumours in the mandible: longitudinal image analysis of tumour size using 3D visualised CT scans

The purpose of this study was to determine how keratocystic odontogenic tumours (KCOTs) in the mandible are reduced during marsupialisation, and to predict the best time for secondary enucleation by analysing computed tomography (CT) images. 15 patients with KCOTs were treated with marsupialisation surgery, and 42 series of CT data taken during the marsupialisation process were analysed. CT data were reconstructed in three-dimensional (3D) images. The 3D images were used to measure the diameter and volume, and to analyse the changes that occurred after marsupialisation. Marsupialised KCOTs tended to be reduced equally towards the window in the tumour. The amount of volume reduction per day (V(r)) was reduced in proportion to the volume (V) with the formula V(r)=-0.0029×V. The formula manipulation for V was V=V(0)×e(-0.0029t) (t=duration after marsupialisaton (day)). The volume of marsupialised KCOTs was reduced by half over a 239 day cycle. These results demonstrate that the future shape of marsupialised mandibular KCOTs, under good control, could be predicted with significant accuracy using CT data. This prediction could decrease the prolonged marsupialisation state in patients with KCOTs.

Immunohistochemical analysis of interleukin-1α, its type I receptor and antagonist in keratocystic odontogenic tumors

BACKGROUND Interleukin-1 alpha (IL-1 alpha) is thought to play a crucial role in the growth of keratocystic odontogenic tumors (KCOTs) in the jaw. The function of IL-1 alpha is regulated by the local levels of IL-1 alpha, its receptor and receptor antagonist (IL-1Ra) in tissues. In this study, the expression of these proteins was investigated both before and after marsupialization in KCOTs. METHODS The expression of IL-1 alpha, IL-1 receptor type I (IL-1RI) and IL-1Ra was detected immunohistochemically in 10 specimens of KCOTs. RESULTS IL-1 alpha was intensively expressed throughout the epithelium in all cases, while mild expression of IL-1 alpha was detected in the subepithelial layer endothelial cells and fibroblasts. Mild or intensive immunoreactivity for IL-1RI was also observed in the epithelial cells in all cases, and in the endothelial cells and fibroblasts in five cases respectively. The expression of IL-1Ra was detected in the epithelial cells in five cases, and in the endothelial cells and fibroblasts in three cases. After marsupialization, the immunoreactivity for IL-1 alpha and IL-1RI in the epithelial cells decreased, while the immunoreactivity for IL-1Ra in the epithelial cells increased. However, the immunoreactivity for IL-1RI and IL-1Ra in endothelial cells and fibroblasts did not change significantly. CONCLUSION The effects of IL-1 alpha on the epithelial cells might be downregulated after marsupialization by changing the expression levels of IL-1 alpha, IL-1RI and IL-1Ra in the epithelium of KCOTs.