Jans Dominique M, Martinet Wim, Fillet Marianne, Kockx Mark M, Merville Marie-Paule, Bult Hidde, Herman Arnold G, De Meyer Guido R Y
Division of Pharmacology, University of Antwerp, Antwerp, Belgium.
J Cardiovasc Pharmacol. 2004 Mar;43(3):462-70. doi: 10.1097/00005344-200403000-00019.
Recently, we showed that platelet phagocytosis occurs in human atherosclerotic plaques and leads to foam cell formation. Platelet phagocytosis, resulting in macrophage activation and iNOS induction, was associated with the formation of amyloid-beta peptide (Abeta) via proteolytic cleavage of platelet-derived amyloid precursor protein (APP), possibly by secretases. To test the involvement of gamma-secretase in this process, we used indomethacin, ibuprofen, and sulindac sulfide, non-steroidal anti-inflammatory drugs (NSAIDs) known to alter the gamma-secretase cleaving site of APP, on their ability to inhibit macrophage activation evoked by platelet phagocytosis. J774 macrophages were incubated with human platelets or lipopolysaccharide (LPS) with or without NSAIDs. Nitrite was quantified as a measure for inducible nitric oxide synthase (iNOS) activity. Indomethacin, ibuprofen, sulindac sulfide, and meloxicam concentration-dependently reduced nitrite production by macrophages incubated with platelets, but did not alter LPS-induced iNOS activity or platelet uptake. However, acetylsalicylic acid and naproxen, two NSAIDs without effect on the gamma-secretase cleaving site of APP, did not affect nitrite production in either platelet- or LPS-stimulated macrophages. Surface-enhanced laser desorption/ionization time-of-flight mass-spectrometry demonstrated time-dependent formation of Abeta-containing peptides after platelet phagocytosis, which could be inhibited by indomethacin. In conclusion, these results point to the involvement of gamma-secretase in macrophage activation following platelet phagocytosis.
最近，我们发现人类动脉粥样硬化斑块中存在血小板吞噬现象，并会导致泡沫细胞形成。血小板吞噬会引发巨噬细胞活化和诱导型一氧化氮合酶（iNOS）的产生，这与通过蛋白酶（可能是分泌酶）对血小板衍生的淀粉样前体蛋白（APP）进行蛋白水解切割从而形成β淀粉样肽（Aβ）有关。为了测试γ-分泌酶在这一过程中的作用，我们使用了吲哚美辛、布洛芬和舒林酸硫化物，这些非甾体抗炎药（NSAIDs）已知会改变APP的γ-分泌酶切割位点，来检测它们抑制血小板吞噬引起的巨噬细胞活化的能力。将J774巨噬细胞与人类血小板或脂多糖（LPS）一起孵育，同时添加或不添加NSAIDs。亚硝酸盐被定量作为诱导型一氧化氮合酶（iNOS）活性的指标。吲哚美辛、布洛芬、舒林酸硫化物和美洛昔康能浓度依赖性地降低与血小板一起孵育的巨噬细胞产生的亚硝酸盐，但不会改变LPS诱导的iNOS活性或血小板摄取。然而，乙酰水杨酸和萘普生这两种对APP的γ-分泌酶切割位点没有影响的NSAIDs，对血小板或LPS刺激的巨噬细胞中的亚硝酸盐产生均无影响。表面增强激光解吸/电离飞行时间质谱法显示，血小板吞噬后含Aβ肽呈时间依赖性形成，这一过程可被吲哚美辛抑制。总之，这些结果表明γ-分泌酶参与了血小板吞噬后的巨噬细胞活化过程。
