Nascimento-Silva V, Arruda M A, Barja-Fidalgo C, Villela C G, Fierro I M
Departmento de Farmacologia e Psicobiologia, Universidade do Estado do Rio de Janeiro, Brazil.
Am J Physiol Cell Physiol. 2005 Sep;289(3):C557-63. doi: 10.1152/ajpcell.00045.2005. Epub 2005 May 18.
Lipoxins (LX) and aspirin-triggered LX (ATL) are eicosanoids generated during inflammation via transcellular biosynthetic routes that elicit distinct anti-inflammatory and proresolution bioactions, including inhibition of leukocyte-mediated injury, stimulation of macrophage clearance of apoptotic neutrophils, repression of proinflammatory cytokine production, and inhibition of cell proliferation and migration. Recently, it was reported that aspirin induces heme oxygenase-1 (HO-1) expression on endothelial cells (EC) in a COX-independent manner, what confers protection against prooxidant insults. However, the underlying mechanisms remain unclear. In this study, we investigated whether an aspirin-triggered lipoxin A(4) stable analog, 15-epi-16-(para-fluoro)-phenoxy-lipoxin A(4) (ATL-1) was able to induce endothelial HO-1. Western blot analysis showed that ATL-1 increased HO-1 protein expression associated with increased mRNA levels on EC in a time- and concentration-dependent fashion. This phenomenon appears to be mediated by the activation of the G protein-coupled LXA(4) receptor because pertussis toxin and Boc-2, a receptor antagonist, significantly inhibited ATL-1-induced HO-1 expression. We demonstrate that treatment of EC with ATL-1 inhibited VCAM and E-selectin expression induced by TNF-alpha or IL-1beta. This inhibitory effect of the analog is modulated by HO-1 because it was blocked by SnPPIX, a competitive inhibitor that blocks HO-1 activity. Our results establish that ATL-1 induces HO-1 in human EC, revealing an undescribed mechanism for the anti-inflammatory activity of these lipid mediators.
脂氧素（LX）和阿司匹林触发的脂氧素（ATL）是在炎症过程中通过跨细胞生物合成途径产生的类二十烷酸，它们引发不同的抗炎和促消退生物活性，包括抑制白细胞介导的损伤、刺激巨噬细胞清除凋亡的中性粒细胞、抑制促炎细胞因子的产生以及抑制细胞增殖和迁移。最近，有报道称阿司匹林以一种不依赖环氧化酶（COX）的方式诱导内皮细胞（EC）中血红素加氧酶-1（HO-1）的表达，这赋予了对促氧化剂损伤的保护作用。然而，其潜在机制仍不清楚。在本研究中，我们调查了一种阿司匹林触发的脂氧素A4稳定类似物，15-表-16-（对氟）-苯氧基-脂氧素A4（ATL-1）是否能够诱导内皮细胞HO-1。蛋白质印迹分析表明，ATL-1以时间和浓度依赖性方式增加EC上与mRNA水平升高相关的HO-1蛋白表达。这种现象似乎是由G蛋白偶联的LXA4受体的激活介导的，因为百日咳毒素和受体拮抗剂Boc-2显著抑制了ATL-1诱导的HO-1表达。我们证明用ATL-1处理EC可抑制由肿瘤坏死因子-α（TNF-α）或白细胞介素-1β（IL-1β）诱导的血管细胞黏附分子（VCAM）和E-选择素的表达。该类似物的这种抑制作用由HO-1调节，因为它被阻断HO-1活性的竞争性抑制剂锡原卟啉（SnPPIX）所阻断。我们的结果表明，ATL-1在人EC中诱导HO-1，揭示了这些脂质介质抗炎活性的一种未被描述的机制。
