IgG is transported across the mouse yolk sac independently of FcγRIIb
IgG is transported across the mouse yolk sac independently of FcγRIIb
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DOI：
10.1016/j.jri.2009.10.008
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发表时间：
2010-03-01
影响因子：
3.4
通讯作者：
Anderson, Clark L.
中科院分区：
文献类型：
--
作者：
Mohanty, Sudhasri;Kim, Jonghan;Anderson, Clark L.
虽然普遍认为人合体滋养层和小鼠卵黄囊内胚层的FcRn是主要的IgG转运蛋白，但在人胎盘内皮中发现不同的Fc受体Fc γ RIIb（RIIb）表明存在额外的IgG转运蛋白。在小鼠中测试我们的假设，我们发现，虽然RIIb在卵黄囊脉管系统中表达，但野生型小鼠（RIIb（+/+））和在编码RIIb的基因中具有无效突变的小鼠（RIIb（-/-）小鼠）的胎儿中的IgG浓度没有不同，因此我们拒绝了我们关于卵黄囊RIIb在小鼠子宫内转运IgG的假设。然而，小鼠卵黄囊中的毛细血管床在结构上比人胎盘中的毛细血管床更复杂，由三种类型的细胞组成：RIIb阴性内皮细胞、也表达4种巨噬细胞标志物中的2种但不表达内皮细胞或周细胞标志物的独特的RIIb承载细胞和周细胞。在人胎盘中，RIIb的b2同种型在小鼠卵黄囊中占优势。值得注意的是，在每个卵黄囊绒毛中仅发现单个毛细血管通道而不是2个具有环的通道，这沿着毛细血管内红细胞，表明血液流动是蠕动的，由周细胞介导。目前尚不清楚人胎盘绒毛中的RIIb是否可能介导IgG转运功能，因为小鼠卵黄囊等效物不能这样做。(C)2009爱思唯尔爱尔兰有限公司保留所有权利。
While generally accepted that FcRn of the human syncytiotrophoblast and the mouse yolk sac endoderm is the major IgG transporter, the finding of a different Fc receptor Fc gamma RIIb (RIIb) in the human placental endothelium has suggested the existence of an additional IgG transporter. Testing our hypothesis in mouse, we found that while RIIb is expressed in the yolk sac vasculature, IgG concentrations in fetuses of wild-type mice (RIIb(+/+)) and mice with a null mutation in the gene encoding RIIb (RIIb(-/-) mice) are not different, and we thus reject our hypothesis that yolk sac RIIb transports IgG in utero in the mouse. However, the capillary bed in the mouse yolk sac is structurally more complex than in human placenta, consisting of three types of cells: an RIIb-negative endothelium, a unique RIIb-bearing cell that also expresses 2 out of 4 macrophage markers but not endothelial cell or pericyte markers, and pericytes. As in the human placenta the b2 isoform of RIIb predominates in the mouse yolk sac. Remarkably only a single capillary channel rather than 2 channels with a loop is found in each yolk sac villus, which, along with intracapillary erythrocytes, suggests that blood flow is peristaltic, mediated by pericytes. It is not clear whether RIIb in the human placental villus might mediate an IgG transport function in light of the mouse yolk sac equivalent failing to do so. (C) 2009 Elsevier Ireland Ltd. All rights reserved.