Ludwig Boltzmann Institute for Lung Vascular Research, Graz, Austria.
Division of Pharmacology and.
Am J Respir Cell Mol Biol. 2020 Jul;63(1):104-117. doi: 10.1165/rcmb.2019-0303OC.
The extracellular matrix (ECM) increasingly emerges as an active driver in several diseases, including idiopathic pulmonary arterial hypertension (IPAH). The basement membrane (BM) is a specialized class of ECM proteins. In pulmonary arteries, the BM is in close contact and direct proximity to vascular cells, including endothelial cells. So far, the role of the BM has remained underinvestigated in IPAH. Here, we aimed to shed light on the involvement of the BM in IPAH, by addressing its structure, composition, and function. On an ultrastructural level, we observed a marked increase in BM thickness in IPAH pulmonary vessels. BM composition was distinct in small and large vessels and altered in IPAH. Proteoglycans were mostly responsible for distinction between smaller and larger vessels, whereas BM collagens and laminins were more abundantly expressed in IPAH. Type IV collagen and laminin both strengthened endothelial barrier integrity. However, only type IV collagen concentration dependently increased cell adhesion of both donor and IPAH-derived pulmonary arterial endothelial cells (PAECs) and induced nuclear translocation of mechanosensitive transcriptional coactivator of the hippo pathway YAP (Yes-activated protein). On the other hand, laminin caused cytoplasmic retention of YAP in IPAH PAECs. Accordingly, silencing of COL4A5 and LAMC1, respectively, differentially affected tight junction formation and barrier integrity in both donor and IPAH PAECs. Collectively, our results highlight the importance of a well-maintained BM homeostasis. By linking changes in BM structure and composition to altered endothelial cell function, we here suggest an active involvement of the BM in IPAH pathogenesis.
细胞外基质（ECM）在多种疾病中越来越成为一个活跃的驱动因素，包括特发性肺动脉高压（IPAH）。基膜（BM）是一类特殊的 ECM 蛋白。在肺血管中，BM 与血管细胞，包括内皮细胞密切接触和直接毗邻。到目前为止，BM 在 IPAH 中的作用仍未得到充分研究。在这里，我们旨在通过探讨 BM 的结构、组成和功能，阐明其在 IPAH 中的作用。在超微结构水平上，我们观察到 IPAH 肺血管中 BM 厚度明显增加。BM 的组成在小血管和大血管中存在差异，并且在 IPAH 中发生了改变。糖胺聚糖主要负责区分较小和较大的血管，而 BM 胶原和平滑肌层蛋白在 IPAH 中表达更为丰富。IV 型胶原和平滑肌层蛋白都增强了内皮屏障的完整性。然而，只有 IV 型胶原浓度依赖性地增加了供体和 IPAH 来源的肺动脉内皮细胞（PAEC）的细胞黏附，并诱导 hippo 通路机械敏感转录共激活因子 YAP（Yes 激活蛋白）的核转位。另一方面，在 IPAH PAEC 中，层粘连蛋白导致 YAP 滞留在细胞质中。因此，COL4A5 和 LAMC1 的沉默分别对供体和 IPAH PAEC 中紧密连接的形成和屏障的完整性产生了不同的影响。总之，我们的结果强调了维持 BM 内稳态的重要性。通过将 BM 结构和组成的变化与内皮细胞功能的改变联系起来，我们提出 BM 在内皮细胞功能障碍中的作用，这表明其在 IPAH 发病机制中具有重要作用。
