Sato Akira, Yokoyama Izumi, Ebina Keiichi
Faculty of Pharmacy, Iwaki Meisei University, 5-5-1, Chuodai-Iino, Iwaki, Fukushima 970-8551, Japan.
Faculty of Pharmacy, Iwaki Meisei University, 5-5-1, Chuodai-Iino, Iwaki, Fukushima 970-8551, Japan.
Eur J Pharmacol. 2015 Oct 5;764:202-207. doi: 10.1016/j.ejphar.2015.06.062. Epub 2015 Jul 2.
Platelet-activating factor (PAF), a potent lipid mediator, is implicated in many inflammatory diseases, and therefore may serve as a direct target for anti-inflammatory drugs. We previously reported that synthetic biotinylated peptides having a Tyr-Lys-Asp-Gly sequence markedly inhibit PAF-induced inflammation by direct binding, and that two synthetic fluorescence-labelled heptapeptides (Lys-Trp-Tyr-Lys-Asp-Gly-Asp and D-Lys-Trp-Tyr-Lys-Asp-Gly-Asp) with high stability in plasma specifically bind to PAF-like lipids (oxidized- and lyso-phosphatidylchoine). In this study, synthetic heptapeptides (Lys-Trp-Tyr-Lys-Asp-Gly-Asp) coupled to a biotin molecule through the N-terminal amino group and ε-amino group of N-terminus Lys, (Btn)KP6 and K(Btn)P6, respectively, and their biotinylated peptides substituted with D-Lys at the N-terminus, (Btn)dKP6 and dK(Btn)P6, respectively, were investigated for their effects on PAF-induced inflammation. In the experiments using a rat model of hind paw oedema, (Btn)KP6, K(Btn)P6, (Btn)dKP6, and dK(Btn)P6 significantly inhibited PAF-induced paw oedema, with the highest inhibitory effect exhibited by dK(Btn)P6. The inhibitory effect of D-Tyr-D-Lys-D-Asp-Gly tetrapeptide on PAF-induced paw oedema was much lower than that of Tyr-Lys-Asp-Gly tetrapeptide. In the experiments using tryptophan fluorescence spectroscopy, (Btn)KP6, K(Btn)P6, (Btn)dKP6, and dK(Btn)P6 bound to PAF dose-dependently, with dK(Btn)P6 showing the strongest binding affinity, indicating that its affinity appears to be closely correlated with its inhibitory effect on PAF-induced inflammation. These results suggest that direct binding of (Btn)KP6, K(Btn)P6, (Btn)dKP6, and dK(Btn)P6 to PAF can lead to marked inhibition of PAF-induced inflammation, and these agents, particularly dK(Btn)P6, may be useful as anti-inflammatory drugs targeting PAF with high stability in plasma.
血小板活化因子（PAF）是一种强效脂质介质，与多种炎症性疾病有关，因此可能成为抗炎药物的直接靶点。我们之前报道过，具有Tyr-Lys-Asp-Gly序列的合成生物素化肽通过直接结合显著抑制PAF诱导的炎症，并且两种在血浆中具有高稳定性的合成荧光标记七肽（Lys-Trp-Tyr-Lys-Asp-Gly-Asp和D-Lys-Trp-Tyr-Lys-Asp-Gly-Asp）特异性结合PAF样脂质（氧化型和溶血磷脂酰胆碱）。在本研究中，分别通过N端氨基和N端Lys的ε-氨基与生物素分子偶联的合成七肽（Lys-Trp-Tyr-Lys-Asp-Gly-Asp），即(Btn)KP6和K(Btn)P6，以及在N端被D-Lys取代的其生物素化肽，即(Btn)dKP6和dK(Btn)P6，被研究了它们对PAF诱导炎症的影响。在使用大鼠后爪水肿模型的实验中，(Btn)KP6、K(Btn)P6、(Btn)dKP6和dK(Btn)P6显著抑制PAF诱导的爪水肿，其中dK(Btn)P6表现出最高的抑制作用。D-Tyr-D-Lys-D-Asp-Gly四肽对PAF诱导的爪水肿的抑制作用远低于Tyr-Lys-Asp-Gly四肽。在使用色氨酸荧光光谱的实验中，(Btn)KP6、K(Btn)P6、(Btn)dKP6和dK(Btn)P6与PAF呈剂量依赖性结合，dK(Btn)P6显示出最强的结合亲和力，表明其亲和力似乎与其对PAF诱导炎症的抑制作用密切相关。这些结果表明，(Btn)KP6、K(Btn)P6、(Btn)dKP6和dK(Btn)P6与PAF的直接结合可导致PAF诱导炎症的显著抑制，并且这些药物，特别是dK(Btn)P6，可能作为在血浆中具有高稳定性的靶向PAF的抗炎药物有用。
