Goppelt-Struebe M, Wiedemann T, Heusinger-Ribeiro J, Vucadinovic M, Rehm M, Pröls F
Medizinische Klinik IV, Universität Erlangen-Nürnberg, Erlangen, and Institut für Anatomie II, Albert-Ludwigs Universität Freiburg, Freiburg, Germany.
Kidney Int. 2000 Jun;57(6):2229-38. doi: 10.1046/j.1523-1755.2000.00083.x.
Glomerular inflammation is characterized by a consecutive infiltration of immunoreactive cells. To mimic the early phase of glomerular injury, a coculture system of platelets and rat renal mesangial cells was established. As prototypes, the inflammation-related proteins cyclooxygenase-2 (Cox-2) and the chemotactic protein osteopontin (OPN) were investigated.
The expression of OPN and Cox-2 mRNA and protein was determined by Northern and Western blot analyses.
Coincubation of platelets and mesangial cells led to a rapid, transient induction of Cox-2 mRNA, which peaked at two hours, whereas OPN and monocyte chemoattractant protein-1 (MCP-1) were induced at later time points. The induction of Cox-2 mRNA was concentration dependent and highly reproducible when platelets of different donors were investigated. Partial Cox-2 induction was observed when supernatants of preactivated platelets were incubated with mesangial cells. The inhibition of the signaling pathways of platelet-derived growth factor (PDGF) and epidermal growth factor (EGF) or interference with Gi-protein signaling partially inhibited platelet-induced Cox-2 expression. Down-regulation of protein kinase C (PKC), which is a common signaling module in many pathways leading to Cox-2 induction, almost completely abrogated platelet-induced Cox-2 expression. The time pattern of Cox-2 and OPN expression suggested that Cox-2 might play a role in OPN induction. The up-regulation of OPN was dependent on de novo protein synthesis and was induced by high levels of exogenous prostaglandin E2 (PGE2; 10 micromol/L). Endogenous PGE2, however, proved not to be essential for OPN mRNA expression, because inhibition of Cox activity did not change OPN mRNA levels. Dexamethasone inhibited Cox-2 mRNA induction but increased OPN mRNA and protein expression.
These data indicate that Cox-2 and OPN are independently up-regulated upon interaction of platelets and mesangial cells.
肾小球炎症的特征是免疫反应细胞的连续浸润。为模拟肾小球损伤的早期阶段，建立了血小板与大鼠肾系膜细胞的共培养系统。作为原型，研究了炎症相关蛋白环氧合酶-2（Cox-2）和趋化蛋白骨桥蛋白（OPN）。
通过Northern和Western印迹分析确定OPN和Cox-2 mRNA及蛋白的表达。
血小板与系膜细胞共孵育导致Cox-2 mRNA快速、短暂诱导，在两小时达到峰值，而OPN和单核细胞趋化蛋白-1（MCP-1）在较晚时间点被诱导。当研究不同供体的血小板时，Cox-2 mRNA的诱导呈浓度依赖性且高度可重复。当预激活血小板的上清液与系膜细胞孵育时，观察到部分Cox-2诱导。血小板衍生生长因子（PDGF）和表皮生长因子（EGF）信号通路的抑制或对Gi蛋白信号的干扰部分抑制了血小板诱导的Cox-2表达。蛋白激酶C（PKC）的下调几乎完全消除了血小板诱导的Cox-2表达，PKC是许多导致Cox-2诱导的信号通路中的常见信号模块。Cox-2和OPN表达的时间模式表明Cox-2可能在OPN诱导中起作用。OPN的上调依赖于从头合成蛋白，并由高水平的外源性前列腺素E2（PGE2；10微摩尔/升）诱导。然而，内源性PGE2被证明对OPN mRNA表达不是必需的，因为Cox活性的抑制并未改变OPN mRNA水平。地塞米松抑制Cox-2 mRNA诱导，但增加OPN mRNA和蛋白表达。
这些数据表明，在血小板与系膜细胞相互作用时，Cox-2和OPN被独立上调。
