Studies on the bone resorption of radicular cyst

虽然神经根囊肿的扩大被认为是渗透压的作用，但更多的生理解释，如骨细胞吸收和结缔组织的破坏，已经出现。近年来，从感染的牙髓根管和牙源性脓肿中分离出了几种厌氧微生物。本研究利用合成蛋白酶底物对感染根管和牙源性脓肿中分离的各种微生物的蛋白酶活性进行了评价，并检测了微生物对牙龈成纤维细胞和内皮细胞单层培养细胞中前列腺素E2 （NPGE2）和蛋白酶分泌的影响。B. endodontalis （B.e）产生胰酶样蛋白酶、肽肽样蛋白酶和肽肽样酶，B. gingivalis产生胰蛋白酶样蛋白酶、肽肽样蛋白酶和肽肽样酶，B. intermedius产生组织蛋白酶h样蛋白酶和肽肽样酶。被认为是根状囊肿病原体的B.e诱导人牙龈成纤维细胞单层培养物合成PGE2，但人牙龈癌细胞系（Ca 9-22：鳞状内皮细胞）不能合成PGE2。此外，B.e刺激了单层培养的人牙龈细胞的浆蛋白分泌，也刺激了Ca 9-22的弹性蛋白酶分泌。这些数据表明，微生物病原体可能通过产生各种蛋白酶直接介导结缔组织破坏，此外，B.e还间接刺激牙龈成纤维细胞产生PGE2和纤溶酶，牙龈内皮细胞产生elstase。由于PGE2是一种有效的骨吸收介质，而弹性酶可以抑制多形核细胞中胶原酶抑制剂TIMP的活性，因此这种微生物可能在根状囊肿的形成或生长中发挥重要作用。

Although the expansion of radicular cyst has been attributed to osmotic pressure, more physiological explanation, in terms of cellular resorption ob bone and connective tissue destruction, has emerged. Recently, several kinds of anareobic microorganisms have been isolated from infected dencal root canals and odontogenic abscesses. In this study, protease activities of various microorganisms isolated from infected root canals and odontogenic abscesses were evaluated using synthetic protease substrates, and the effect of microorganism on the secretion of prostaglandin E2 NPGE2) and proteased from monolayer culture cells of gingival fibroblasts and endotherial cells were examined. B. endodontalis (B.e) produced gly-pro peptidase and kallikrein-like protease, B. gingivalis produced trypsin-like protease, kallikrein like protease, and gly-pro peptidase, and B. intermedius produced cathepsin H-like protease and gly-pro peptidase. B.e, a putative pathogen of radicular cyst, induced monolayer cultures of human gingival fibroblasts to synthesize PGE2, but those of human gingival carcinoma cell line (Ca 9-22: squamous endothelial cell) did not synthesize PGE2. Furthermore, B.e stimulated the secretion of plasmin from human gingival cells in monolayer cultures, and also stimulated the secretion of elastase from Ca 9-22. These data suggests that one way in which pathogens of microorganisms might directly mediate connective tissue destruction through production of various proteases, furthermore indirect way, B.e stimulated the production of PGE2 and plasmin from gingival fibroblasts and elstase from gingival endothelial cells. Since PGE2 is a potent mediator of bone resorption and elastase inhibits the activity of TIMP, an inhibitor of collagenase, from polymorphonuclear cells, this microorganism may play an important role in the formation or growth of radicular cysts.