Cellular functional character of extracellular matrix on dental pulpitis

细胞外基质（extracellular matrix， ECM）在细胞的生长和退化过程中起着重要的作用，由于感染和宿主的免疫反应，ECM被基质金属蛋白酶（matrix metalloproteases, MMPs）破坏。纤溶酶原激活剂（plasminogen activator， PA）对纤溶酶原的有限降解产生纤溶酶，激活潜在的MMPs并刺激激肽的合成。炎症细胞因子如il -1 β、IL-6和tnf - α是由细菌或病毒入侵合成的。研究了各种炎症因子对人牙髓细胞PA/纤溶蛋白系统的影响，并与对牙龈细胞的影响进行了比较，以期对牙髓炎的牙髓细胞进行表征。从同一供体获得的牙髓和牙龈细胞，在含有10%胎牛血清和5% CO_2的α - mem中，37℃培养。两种细胞在含2% PCS的培养基中孵育24小时，并用各种细胞因子（il -1 β， IL-6和tnf - α）处理。用荧光底物测定条件培养基中PA活性。RT-PCR分析tPA mRNA的表达。在IL-6和tnf - α的作用下，牙髓细胞的PA活性和tPA mRNA的表达均高于牙龈细胞。炎症细胞因子（il -1 β、IL-6和tnf - α）通过增强tPA基因表达和MMP-2活性来刺激PA活性，这些细胞因子激活的tPA刺激MMP-9，因此炎症细胞因子可能通过刺激人牙髓细胞的PA/plasmin系统参与细胞外基质降解。牙髓细胞IL-6和tnf - α对pa -纤溶蛋白系统和MMP-9的反应与牙龈细胞不同。牙髓细胞外基质在炎症过程中产生的IL-6和tnf - α对牙髓细胞外基质的破坏更为强烈。

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.