Section of Anaesthetics, Pain Medicine and Intensive Care, Faculty of Medicine, Imperial College London, Chelsea and Westminster Hospital, London, United Kingdom.
Am J Physiol Lung Cell Mol Physiol. 2011 May;300(5):L781-9. doi: 10.1152/ajplung.00326.2010. Epub 2011 Mar 4.
TNF plays a crucial role in the pathogenesis of acute lung injury. However, the expression profile of its two receptors, p55 and p75, on pulmonary endothelium and their influence on TNF signaling during lung microvascular inflammation remain uncertain. Using flow cytometry, we characterized the expression profile of TNF receptors on the surface of freshly harvested pulmonary endothelial cells (PECs) from mice and found expression of both receptors with dominance of p55. To investigate the impact of stimulating individual TNF receptors, we treated wild-type and TNF receptor knockout mice with intravenous TNF and determined surface expression of adhesion molecules (E-selectin, VCAM-1, ICAM-1) on PECs by flow cytometry. TNF-induced upregulation of all adhesion molecules was substantially attenuated by absence of p55, whereas lack of p75 had a similar but smaller effect that varied between adhesion molecules. Selective blockade of individual TNF receptors by specific antibodies in wild-type primary PEC culture confirmed that the in vivo findings were due to direct effects of TNF receptor inhibition on endothelium and not other cells (e.g., circulating leukocytes). Finally, we found that PEC surface expression of p55 dramatically decreased in the early stages of endotoxemia following intravenous LPS, while no change in p75 expression was detected. These data demonstrate a crucial in vivo role of p55 and an auxiliary role of p75 in TNF-mediated adhesion molecule upregulation on PECs. It is possible that the importance of the individual receptors varies at different stages of pulmonary microvascular inflammation following changes in their relative expression.
TNF 在急性肺损伤的发病机制中起着至关重要的作用。然而，其两种受体（p55 和 p75）在肺内皮细胞上的表达谱及其对肺微血管炎症中 TNF 信号的影响尚不清楚。使用流式细胞术，我们对从小鼠中收获的新鲜肺内皮细胞（PECs）表面 TNF 受体的表达谱进行了特征描述，发现两种受体均有表达，p55 占优势。为了研究刺激单个 TNF 受体的影响，我们用静脉内 TNF 处理野生型和 TNF 受体敲除小鼠，并通过流式细胞术测定 PEC 上粘附分子（E-选择素、VCAM-1、ICAM-1）的表面表达。TNF 诱导的所有粘附分子的上调均因缺乏 p55 而显著减弱，而缺乏 p75 则具有相似但较小的作用，且在不同的粘附分子之间存在差异。在野生型原代 PEC 培养物中用特异性抗体选择性阻断单个 TNF 受体，证实了体内发现是由于 TNF 受体抑制对内皮细胞的直接作用，而不是其他细胞（例如循环白细胞）所致。最后，我们发现静脉内 LPS 后内毒素血症早期 PEC 表面的 p55 表达急剧下降，而 p75 表达无变化。这些数据表明，p55 在 TNF 介导的 PEC 上粘附分子上调中具有重要的体内作用，而 p75 则具有辅助作用。在肺微血管炎症的不同阶段，由于其相对表达的变化，单个受体的重要性可能会有所不同。
