Trivedi Anjali, Lu Tyler M, Summers Barbara, Kim Kihwan, Rhee Alexander J, Houghton Sean, Byers Derek E, Lis Raphaël, Reed Hasina Outtz
Department of Medicine, Division of Pulmonary and Critical Care, Weill Cornell Medicine, New York, NY, United States.
Ansary Stem Cell Institute, Division of Regenerative Medicine, Department of Medicine, Weill Cornell Medicine, New York, NY, United States.
Front Cell Dev Biol. 2024 Feb 19;12:1344070. doi: 10.3389/fcell.2024.1344070. eCollection 2024.
The lymphatic vasculature regulates lung homeostasis through drainage of fluid and trafficking of immune cells and plays a key role in the response to lung injury in several disease states. We have previously shown that lymphatic dysfunction occurs early in the pathogenesis of chronic obstructive pulmonary disease (COPD) caused by cigarette smoke (CS) and that this is associated with increased thrombin and fibrin clots in lung lymph. However, the direct effects of CS and thrombin on lymphatic endothelial cells (LECs) in COPD are not entirely clear. Studies of the blood vasculature have shown that COPD is associated with increased thrombin after CS exposure that causes endothelial dysfunction characterized by changes in the expression of coagulation factors and leukocyte adhesion proteins. Here, we determined whether similar changes occur in LECs. We used an cell culture system and treated human lung microvascular lymphatic endothelial cells with cigarette smoke extract (CSE) and/or thrombin. We found that CSE treatment led to decreased fibrinolytic activity in LECs, which was associated with increased expression of plasminogen activator inhibitor 1 (PAI-1). LECs treated with both CSE and thrombin together had a decreased expression of tissue factor pathway inhibitor (TFPI) and increased expression of adhesion molecules. RNA sequencing of lung LECs isolated from mice exposed to CS also showed upregulation of prothrombotic and inflammatory pathways at both acute and chronic exposure time points. Analysis of publicly available single-cell RNA sequencing of LECs as well as immunohistochemical staining of lung tissue from COPD patients supported these data and showed increased expression of inflammatory markers in LECs from COPD patients compared to those from controls. These studies suggest that in parallel with blood vessels, the lymphatic endothelium undergoes inflammatory changes associated with CS exposure and increased thrombin in COPD. Further research is needed to unravel the mechanisms by which these changes affect lymphatic function and drive tissue injury in COPD.
淋巴脉管系统通过液体引流和免疫细胞运输来调节肺的稳态，并在多种疾病状态下对肺损伤的反应中起关键作用。我们之前已经表明，在由香烟烟雾（CS）引起的慢性阻塞性肺疾病（COPD）发病机制中，早期会出现淋巴功能障碍，且这与肺淋巴中凝血酶和纤维蛋白凝块增加有关。然而，CS和凝血酶对COPD中淋巴管内皮细胞（LEC）的直接影响尚不完全清楚。对血管系统的研究表明，CS暴露后COPD与凝血酶增加有关，凝血酶会导致内皮功能障碍，其特征是凝血因子和白细胞粘附蛋白表达发生变化。在此，我们确定LEC中是否会发生类似变化。我们使用了一种细胞培养系统，并用香烟烟雾提取物（CSE）和/或凝血酶处理人肺微血管淋巴管内皮细胞。我们发现，CSE处理导致LEC中的纤溶活性降低，这与纤溶酶原激活物抑制剂1（PAI-1）表达增加有关。同时用CSE和凝血酶处理的LEC组织因子途径抑制剂（TFPI）表达降低，粘附分子表达增加。对暴露于CS的小鼠分离出的肺LEC进行RNA测序也显示，在急性和慢性暴露时间点，促血栓形成和炎症途径均上调。对公开可用的LEC单细胞RNA测序分析以及COPD患者肺组织的免疫组织化学染色支持了这些数据，并表明与对照组相比，COPD患者LEC中炎症标志物的表达增加。这些研究表明，与血管类似，在COPD中，淋巴管内皮会发生与CS暴露和凝血酶增加相关的炎症变化。需要进一步研究来阐明这些变化影响淋巴功能并导致COPD组织损伤的机制。
