Gu Baihan, Alexander J Steven, Gu Yang, Zhang Yanping, Lewis David F, Wang Yuping
Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center, Shreveport, 71130, USA.
Lymphat Res Biol. 2006 Spring;4(1):11-7. doi: 10.1089/lrb.2006.4.11.
Lymphatic vascular endothelial hyaluronan receptor-1 (LYVE-1) is a selective marker for lymphatic endothelium and a homolog of CD44, the hyaluronan (HA) receptor. HA in the extracellular matrix plays roles in tissue remodeling, development, and homeostasis, and as an HA receptor, LYVE-1 mediated HA metabolism might regulate these events. Currently, little is known about the lymphatic character within the human placenta. This study therefore determined LYVE-1 and other lymphatic markers in human placentas.
Placentas and villous tissue were fixed and immunostained for human LYVE-1 and CD44 and examined by RT-PCR. LYVE-1 was expressed at both protein and mRNA levels in trophoblast cells (TC) and in villous core endothelium (VCE). Predominant protein expression for LYVE-1 was observed in syncytiotrophoblast cells (TCs) of preterm placentas. Neither mRNA or protein for CD44 was expressed. Other blood and lymphatic-lineage molecules (VEGF-A, -C, and -D, Flt-1, KDR, Flt-4, and Prox-1) were examined by RT-PCR. VEGF-A, VEGF-D, and Flt-1 mRNA were observed in TCs and VCEs, while mRNA for VEGF-C, KDR, and Flt-4 was mainly observed in VCEs. Prox-1 was found at the mRNA, but not protein level in TCs and VCEs. Our findings indicate (1) the importance of LYVE-1, but not CD44, in regulation of HA metabolism in the maternal-fetal interface and fetal circulation, and (2) possible dual blood and lymphatic phenotypic characteristics in fetal endothelium. These results provide new insights into HA metabolism and lymphatic-lineage molecule expression in the human placenta.
淋巴管内皮透明质酸受体-1（LYVE-1）是淋巴管内皮的一种选择性标志物，也是透明质酸（HA）受体CD44的同源物。细胞外基质中的HA在组织重塑、发育和内环境稳定中发挥作用，作为HA受体，LYVE-1介导的HA代谢可能调节这些过程。目前，关于人胎盘内的淋巴管特征知之甚少。因此，本研究确定了人胎盘中LYVE-1和其他淋巴管标志物。
胎盘和绒毛组织固定后，进行人LYVE-1和CD44免疫染色，并通过逆转录聚合酶链反应（RT-PCR）检测。LYVE-1在滋养层细胞（TC）和绒毛核心内皮细胞（VCE）中均有蛋白和mRNA水平的表达。在早产胎盘的合体滋养层细胞（TCs）中观察到LYVE-1主要的蛋白表达。未检测到CD44的mRNA或蛋白表达。通过RT-PCR检测其他血液和淋巴管谱系分子（血管内皮生长因子A、C和D、Flt-1、KDR、Flt-4和Prox-1）。在TC和VCE中观察到血管内皮生长因子A、血管内皮生长因子D和Flt-1的mRNA，而血管内皮生长因子C、KDR和Flt-4的mRNA主要在VCE中观察到。在TC和VCE中，Prox-1在mRNA水平上有表达，但在蛋白水平上未检测到。我们的研究结果表明：（1）LYVE-1而非CD44在母胎界面和胎儿循环中HA代谢调节中的重要性；（2）胎儿内皮细胞可能具有血液和淋巴管双重表型特征。这些结果为人类胎盘HA代谢和淋巴管谱系分子表达提供了新的见解。
