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证据表明血管紧张素 II 并不直接刺激 MD2-TLR4 先天炎症途径。

Evidence that angiotensin II does not directly stimulate the MD2-TLR4 innate inflammatory pathway.

机构信息

Hypertension & Vascular Research Center, Wake Forest University School of Medicine, Winston-Salem, NC, USA.

Hypertension & Vascular Research Center, Wake Forest University School of Medicine, Winston-Salem, NC, USA.

出版信息

Peptides. 2021 Feb;136:170436. doi: 10.1016/j.peptides.2020.170436. Epub 2020 Nov 9.

Abstract

The renin-angiotensin system (RAS) plays a critical role in the regulation of blood pressure. Inappropriate activation of the RAS, particularly stimulation of the ACE-Ang II-AT receptor axis is a key factor in hypertension and ATR antagonists (ARBs) are first line therapies in the treatment of cardiovascular disease (CVD). Accumulating evidence suggests that the Ang II-ATR axis may stimulate both innate and adaptive immune systems. Indeed, recent studies suggest that Ang II stimulates inflammatory events in an ATR-independent manner by binding the MD2 accessory protein of the TLR4 complex in renal NRK-52E cells. Direct Ang II stimulation of the TLR4 complex is clinically relevant as ARBs increase circulating Ang II levels. Thus, the current study further investigated Ang II stimulation of the TLR4 pathway to release of the pro-inflammatory cytokine CCL2 under identical conditions to the TLR4 ligands LPS and palmitate in the NRK-52E cells. Although LPS (1 ng/mL) and palmitate (100 μM) stimulated CCL2 release 20-fold, Ang II (0.1-10 μM) failed to induce CCL2 release. Both the LPS and palmitate CCL2 responses were abolished by the TLR4 inhibitor Tak242 and significantly reduced by the MD2 inhibitor L48H37. Ang II (1 μM) had no additive effects on LPS (1 ng/mL) or palmitate (100 μM), and the ARB candesartan failed to attenuate CCL2 release to either agent alone. Ang II also failed to induce the release of the putative TLR4 ligand HMBG1. These studies failed to confirm that Ang II directly stimulates the MD2-TLR4 complex to induce cytokine release in NRK-52E cells.

摘要

肾素-血管紧张素系统(RAS)在血压调节中起着关键作用。RAS 的不适当激活,特别是 ACE-Ang II-AT 受体轴的刺激,是高血压的一个关键因素,而血管紧张素受体拮抗剂(ARBs)是心血管疾病(CVD)治疗的一线药物。越来越多的证据表明,Ang II-ATR 轴可能刺激先天和适应性免疫系统。事实上,最近的研究表明,Ang II 通过在肾 NRK-52E 细胞中与 TLR4 复合物的 MD2 辅助蛋白结合,以非 ATR 依赖的方式刺激炎症事件。ARB 会增加循环 Ang II 水平,因此直接刺激 TLR4 复合物与临床相关。因此,本研究在与 TLR4 配体 LPS 和棕榈酸相同的条件下,进一步研究了 Ang II 对 TLR4 途径的刺激,以释放促炎细胞因子 CCL2,在 NRK-52E 细胞中。尽管 LPS(1ng/mL)和棕榈酸(100μM)刺激 CCL2 释放 20 倍,但 Ang II(0.1-10μM)未能诱导 CCL2 释放。TLR4 抑制剂 Tak242 消除了 LPS(1ng/mL)和棕榈酸(100μM)的 CCL2 反应,而 MD2 抑制剂 L48H37 则显著降低了该反应。Ang II(1μM)对 LPS(1ng/mL)或棕榈酸(100μM)没有附加作用,ARB 坎地沙坦也不能单独减轻对这两种药物的 CCL2 释放。Ang II 也未能诱导假定的 TLR4 配体 HMBG1 的释放。这些研究未能证实 Ang II 直接刺激 MD2-TLR4 复合物诱导 NRK-52E 细胞中细胞因子的释放。

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