Peptidoglycan經由EP2/EP4受器調控RAW 264.7巨噬細胞介白素-6的生成

Peptidoglycan (PGN)為革?氏陽性菌細胞壁成分之一，本?文主要是探討PGN在RAW 264.7巨噬細胞中誘導interleukin-6 (IL-6)釋放的訊號傳遞?徑。PGN以濃?及時間相關方式?激IL-6的釋放，同時也以時間相關方式?激PGE2及cAMP產生。PGN調控IL-6產生能被非選擇性cyclooxygenase (COX)的抑制劑indomethacin、選擇性COX-2抑制劑NS398、EP拮抗劑AH6809、EP4拮抗劑AH23848及protein kinase A (PKA)抑制劑KT5720所抑制，但卻?受非選擇性nitric oxide synthase (NOS)抑制劑NG-Nitro-L-arginine methyl ester (L-NAME)影響。此外，PGE2、EP2致效劑butaprost及EP2/EP4致效劑misoprostol皆能?激RAW 264.7巨噬細胞IL-6的釋放，然而EP1/EP3致效劑sulprostone則沒有反應。另外，PGN能以時間相關方式?激IκB kinaseα/β (IKKα/β)活化、p65上Ser276磷酸化及NF-κB/DNA複合體產生。而由PGN調控IKKα/β的活化及p65上Ser276磷酸化也能被NS398及KT5720所抑制。當直接給予細胞PGE2或PKA活化劑8-bromo-cAMP也?能以時間相關方式?激IKKα/β磷酸化。另一方面，由PGN引發κB-luciferase活性的增加可被indomethacin、NS398、AH6809、AH23848及KT5720所抑制。由這以上這些實驗結果顯示，在RAW 264.7巨噬細胞當中，PGN會經由調控COX-2表現而?激PGE2產生，而PGE2能進一步活化其受器EP2及EP4使細胞內cAMP上升、PKA的活化、IKKα/β活化、p65磷酸化及NF-κB活化進而調控IL-6的產生。然而，PGN誘發nitric oxide的釋放並沒有?與在PGN誘發IL-6釋放的訊號傳遞?徑之中。

關鍵字

介白素-6 ；巨噬細胞；發炎反應

並列摘要

In this study, we investigated the signaling pathway involved in interleukin-6 (IL-6) production caused by peptidoglycan (PGN), a cell wall component of the gram-positive bacterium, Staphylococcus aureus, in RAW 264.7 macrophages. PGN caused concentration- and time-dependent increases in IL-6 production, and a time-dependent increase in the formation of PGE2 and cAMP. PGN-mediated IL-6 production was inhibited by a non-selective cyclooxygenase (COX) inhibitor (indomethacin), a selective COX-2 inhibitor (NS398), an EP2 antagonist (AH6809), an EP4 antagonist (AH23848), and a protein kinase A (PKA) inhibitor (KT5720), but not by a non-selective nitric oxide synthase (NOS) inhibitor (NG-nitro-L-arginine methyl ester, L-NAME). Furthermore, PGE2, an EP2 agonist (butaprost), and an EP2/EP4 agonist(misoprostol) all induced IL-6 production, whereas an EP1/EP3 agonist(sulprostone) did not. PGN caused time-dependent activations of IκB kinase α/β (IKKα/β), p65 phosphorylation at Ser276, and the formation of an NF-κB-specific DNA-protein complex. PGN-mediated IKKα/β activation and p65 phosphorylation at Ser276 was inhibited by NS398 and KT5720. Both PGE2 and the direct PKA activator, 8-bromo-cAMP, also caused IKKα/β phosphorylation in a time-dependent manner. The PGN-induced increase in κB-luciferase activity was inhibited by indomethacin, NS398, AH6809, AH23848, and KT5720. These results suggest that PGN-induced IL-6 production involves COX-2-generated PGE2, activation of EP2 and EP4 receptors, intracellular cAMP formation, PKA activation, IKKα/β activation, p65 Ser276 phosphorylation, and NF-κB activation. However, PGN-induced nitric oxide release was not involved in the signaling pathway of PGN induced IL-6 production.

並列關鍵字

Interleukin-6 ； Macrophage ； Inflammation

參考文獻

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國際替代計量

Peptidoglycan經由EP2/EP4受器調控RAW 264.7巨噬細胞介白素-6的生成

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