Cellular functional character of extracellular matrix on dental pulpitis

由于感染和宿主免疫反应，细胞外基质(ECM)在细胞的生长和退化中起重要作用，基质金属蛋白酶(MMPs)破坏ECM。纤溶酶是由纤溶酶原激活剂(PA)有限降解纤溶酶原而产生的，它激活潜伏的MMPs，刺激激动素的合成。炎性细胞因子如IL-1β、IL-6和TNF-α是通过细菌或病毒入侵而合成的。为了研究牙髓细胞在牙髓炎中的作用，观察了不同炎性细胞因子对人牙髓细胞PA/纤溶酶系统的影响，并与对人牙龈细胞的影响进行了比较。取同一供体的牙髓和牙龈细胞，在含10%胎牛血清的α-MEM和5%CO_2的空气中培养37℃。将处于融合阶段的两种细胞在含有2%PCS的培养液中孵育24小时，并用不同的细胞因子(IL-1β、IL-6和TNF-α)处理。用荧光底物法检测条件培养液中PA活性。逆转录聚合酶链式反应(RT-PCR)分析tPA基因的表达。IL-6和TNF-α共同孵育时，牙髓细胞的PA活性和tPA mRNA的表达均高于牙周细胞。炎性细胞因子(IL-1β、IL-6和TNF-α)通过增强tPA基因表达和基质金属蛋白酶-2活性来刺激PA活性，而由这些细胞因子激活的tPA则刺激基质金属蛋白酶-9，因此炎性细胞因子可能通过刺激人牙髓细胞的PA/纤溶酶系统参与细胞外基质的降解。牙髓细胞对PA-纤溶酶系统和基质金属蛋白酶-9的反应与牙龈细胞不同。炎症过程中产生的IL-6和TNF-α对牙髓细胞外基质的损伤更为严重。

The extracellular matrix (ECM) plays an important role in the growth and degeneration of cells As a result of infection and host immunoreaction, ECM is damaged by matrix metalloproteases (MMPs). Plasmin, which is produced from limited degradation of plasminogen by plasminogen activator (PA), activated latent MMPs and stimulates the synthesis of kinin. The inflammatory cytokines such as IL-1beta, IL-6 and TNF-alpha are synthesized by invasion of bacteria or virus. The effect of various inflammatory cytokines on the PA/plasmin system in human dental pulp cells was examined and compared with the effect on human gingival cells in order to characterize dental pulp cells in pulpitis. Dental pulp and gingival cells which were obtained from same donor were cultured in alpha-MEM with 10 % fetal calf serum and under 5 % CO_2 in air at 37 ℃. Both cells in a con fluent-stage were incubated for 24 h in medium containing 2 % PCS and treated with various cytokines (IL-1beta, IL-6 and TNF-alpha). The PA activity in conditioned medium was measured using fluorescent substrate. The expression of tPA mRNA was analyzed by RT-PCR. The PA activity of dental pulp cells was higher and the expression of tPA mRNA was stronger than that of gingival cells when both cells were incubated with IL-6 and TNF-alpha. The inflammatory cytokines (IL-1beta, IL-6 and TNF-alpha) stimulated PA activity via an enhancement of tPA gene expression and MMP-2 activity, and tPA activated by these cytokines stimulated MMP-9, Thus the inflammatory cytokines may be involved in extracellular matrix degradation through a stimulation of the PA/plasmin system of human dental pulp cells. Dental pulp cells were different from gingival cells in the response of the IL-6 and TNF-alpha to PA-plasmin system and MMP-9. The extracellular matrix of dental pulp is more strongly damaged through IL-6 and TNF-alpha produced in progress of inflammation.