Noguchi K, Shitashige M, Ishikawa I
Department of Periodontology, Faculty of Dentistry, Tokyo Medical & Dental University, Japan.
J Periodontol. 1999 Aug;70(8):902-8. doi: 10.1902/jop.1999.70.8.902.
Human periodontal ligament (PDL) cells produce prostaglandin (PG) E2 in response to proinflammatory cytokines. However, the mechanism of PGE2 production is not well understood. The purpose of the present study was to investigate the involvement of cyclooxygenase (COX)-1 and COX-2 in PGE2 production by PDL cells stimulated with a proinflammatory cytokine, interleukin-1alpha (IL-1alpha), and to examine the regulation of PGE2 production by cell-cell interaction of human gingival keratinocytes and PDL cells.
The levels of PGE2 in the culture media of PDL cells stimulated with IL-1alpha or culture media of human gingival keratinocytes were determined by an enzyme-linked immunosorbent assay. Expression of COX-1 and -2 mRNA and protein was studied by Northern blot analysis and Western blot analysis, respectively.
IL-1alpha-stimulated PDL cells produced PGE2 in a time-dependent manner. Indomethacin, a non-selective COX-1/COX-2 inhibitor, and NS-398, a selective COX-2 inhibitor, completely inhibited PGE2 production by the IL-1alpha-stimulated cells. COX-2 mRNA was detected after IL-1alpha stimulation, although it was not detected in unstimulated cells. There was no difference in expression of COX-1 mRNA between unstimulated cells and IL-la-stimulated cells. Expression of COX-2 protein in IL-1alpha-stimulated cells was increased, compared with that in unstimulated cells, whereas COX-1 protein expression was almost the same in both the cells. Treatment of IL-1alpha-stimulated PDL cells with dexamethasone, known to inhibit COX-2 expression, prevented PGE2 production and COX-2 mRNA expression. Addition of the culture media of human gingival keratinocytes to PDL cells increased PGE2 production. The PGE2 production was depressed by treatment of the cells with IL-1 receptor antagonist and anti- IL-1alpha antibody, not with anti-IL-1beta antibody. The PGE2 production was also inhibited by treatment with NS-398 and dexamethasone.
We suggest that PDL cells stimulated with IL-1alpha produce PGE2 through de novo synthesis of COX-2 and that the cell interaction of gingival keratinocytes and PDL cells controls COX-2 expression and PGE2 production via IL-1alpha or 1alpha IL-la-like factor(s). Selective COX-2 inhibitors, which have the advantage of reduced gastric toxicity, may provide a useful approach to treatment of periodontal disease.
人牙周膜（PDL）细胞在促炎细胞因子作用下产生前列腺素（PG）E2。然而，PGE2产生的机制尚未完全明确。本研究旨在探讨环氧化酶（COX）-1和COX-2在促炎细胞因子白细胞介素-1α（IL-1α）刺激的PDL细胞产生PGE2过程中的作用，并研究人牙龈角质形成细胞与PDL细胞的细胞间相互作用对PGE2产生的调节作用。
采用酶联免疫吸附测定法测定IL-1α刺激的PDL细胞培养基或人牙龈角质形成细胞培养基中PGE2的水平。分别通过Northern印迹分析和Western印迹分析研究COX-1和COX-2 mRNA及蛋白的表达。
IL-1α刺激的PDL细胞以时间依赖性方式产生PGE2。非选择性COX-1/COX-2抑制剂吲哚美辛和选择性COX-2抑制剂NS-398完全抑制IL-1α刺激细胞产生PGE2。IL-1α刺激后可检测到COX-2 mRNA，而未刺激的细胞中未检测到。未刺激细胞与IL-1α刺激细胞的COX-1 mRNA表达无差异。与未刺激细胞相比，IL-1α刺激细胞中COX-2蛋白表达增加，而COX-1蛋白表达在两种细胞中几乎相同。用已知可抑制COX-2表达的地塞米松处理IL-1α刺激的PDL细胞，可阻止PGE2产生和COX-2 mRNA表达。将人牙龈角质形成细胞培养基添加到PDL细胞中可增加PGE2产生。用IL-1受体拮抗剂和抗IL-1α抗体处理细胞可抑制PGE2产生，而用抗IL-1β抗体处理则无此作用。用NS-398和地塞米松处理也可抑制PGE2产生。
我们认为，IL-1α刺激的PDL细胞通过COX-2的从头合成产生PGE2，牙龈角质形成细胞与PDL细胞的细胞间相互作用通过IL-1α或IL-1α样因子控制COX-2表达和PGE2产生。具有降低胃毒性优势的选择性COX-2抑制剂可能为牙周疾病的治疗提供一种有用的方法。
