Department of Pediatrics, University of California, San Francisco, 513 Parnassus Avenue, HSE1418, Box 1346, San Francisco, CA, 94143-1346, USA.
Department of Surgery, University of California, Davis, Davis, USA.
Sci Rep. 2021 Jan 14;11(1):1468. doi: 10.1038/s41598-020-80882-1.
Normal growth and development of lymphatic structures depends on mechanical forces created by accumulating interstitial fluid. However, prolonged exposure to pathologic mechanical stimuli generated by chronically elevated lymph flow results in lymphatic dysfunction. The mechanisms that transduce these mechanical forces are not fully understood. Our objective was to investigate molecular mechanisms that alter the growth and metabolism of isolated lymphatic endothelial cells (LECs) exposed to prolonged pathologically elevated lymph flow in vivo within the anatomic and physiologic context of a large animal model of congenital heart disease with increased pulmonary blood flow using in vitro approaches. To this end, late gestation fetal lambs underwent in utero placement of an aortopulmonary graft (shunt). Four weeks after birth, LECs were isolated and cultured from control and shunt lambs. Redox status and proliferation were quantified, and transcriptional profiling and metabolomic analyses were performed. Shunt LECs exhibited hyperproliferative growth driven by increased levels of Hypoxia Inducible Factor 1α (HIF-1α), along with upregulated expression of known HIF-1α target genes in response to mechanical stimuli and shear stress. Compared to control LECs, shunt LECs exhibited abnormal metabolism including abnormalities of glycolysis, the TCA cycle and aerobic respiration. In conclusion, LECs from lambs exposed in vivo to chronically increased pulmonary lymph flow are hyperproliferative, have enhanced expression of HIF-1α and its target genes, and demonstrate altered central carbon metabolism in vitro. Importantly, these findings suggest provocative therapeutic targets for patients with lymphatic abnormalities.
正常的淋巴结构生长和发育依赖于由间质液积累产生的机械力。然而，长期暴露于由慢性升高的淋巴流量产生的病理机械刺激会导致淋巴功能障碍。将这些机械力转化为信号的机制尚未完全阐明。我们的目的是研究分子机制，即在先天性心脏病大动物模型中，在增加肺血流量的解剖和生理背景下，体内长时间暴露于病理升高的淋巴流量会改变分离的淋巴内皮细胞（LEC）的生长和代谢，使用体外方法。为此，在妊娠晚期，胎儿羔羊接受了宫内放置的主动脉肺动脉移植物（分流器）。出生后 4 周，从对照和分流羔羊中分离并培养 LEC。定量测定氧化还原状态和增殖，并进行转录谱和代谢组学分析。分流 LEC 表现出由缺氧诱导因子 1α（HIF-1α）水平升高驱动的过度增殖性生长，以及对机械刺激和切应力的已知 HIF-1α靶基因的上调表达。与对照 LEC 相比，分流 LEC 表现出异常代谢，包括糖酵解、三羧酸循环和有氧呼吸的异常。总之，体内暴露于慢性增加的肺淋巴流量的羔羊 LEC 过度增殖，HIF-1α及其靶基因表达增强，并在体外表现出中央碳代谢异常。重要的是，这些发现为淋巴异常患者提供了有前景的治疗靶点。
