Studies on the bone resorption of radicular cyst

虽然根性囊肿的扩张被归因于渗透压，但更多的生理学解释出现了，如骨细胞吸收和结缔组织破坏。近年来，从感染的根管和牙源性脓肿中分离到了多种厌氧菌。本研究采用人工合成的蛋白酶底物，评价了从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，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分泌前列腺素E2（NPGE 2）和蛋白酶的影响。B。endodontalis（B.e）产生甘氨酸原肽酶和激肽释放酶样蛋白酶，B.牙龈炎产生胰蛋白酶样蛋白酶、激肽释放酶样蛋白酶和甘氨酸原肽酶; B.产组织蛋白酶H样蛋白酶和甘氨酸原肽酶。根囊肿的致病菌B.e可诱导人牙龈成纤维细胞合成PGE 2，而人牙龈癌细胞系（Ca 9-22：鳞状内皮细胞）不合成PGE 2。此外，B.e刺激单层培养的人牙龈细胞分泌纤溶酶，也刺激Ca 9-22分泌弹性蛋白酶。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，间接方式，B.e刺激牙龈成纤维细胞产生PGE 2和纤溶酶以及牙龈内皮细胞产生弹性蛋白酶。由于PGE 2是骨吸收的有效介质，并且弹性蛋白酶抑制来自多形性胶质细胞的胶原酶抑制剂TIMP的活性，因此这种微生物可能在根囊肿的形成或生长中起重要作用。

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.