Zarlingo T J, Eis A L, Brockman D E, Kossenjans W, Myatt L
Department of Obstetrics and Gynaecology, University of Cincinnati, College of Medicine, Ohio, USA.
Placenta. 1997 Sep;18(7):511-20. doi: 10.1016/0143-4004(77)90004-2.
The presence and immunolocalization of type II (inducible or macrophage) and type III (endothelial) nitric oxide synthase (NOS) isoforms were compared in the term placentae of humans, rhesus monkeys, baboons, guinea-pigs, rats and sheep using isoform specific antibodies. In the human placenta, intense immunohistochemical staining for type III NOS was seen in syncytiotrophoblast with weaker staining in vascular endothelial cells. Only vascular endothelial cells showed positive III NOS staining in rhesus monkey, baboon, guinea-pig, rat and sheep placentae. No positive type III NOS immunostaining was seen in trophoblast from any non-human placentae. Western blotting revealed a 135-kDa type III NOS species in placental homogenates, semi-purified by ADP-sepharose affinity chromatography, from all the species tested confirming antibody specificity. Type II NOS immunostaining was localized to certain villous stromal cells which also stained for CD14 (a monocyte/macrophage marker) in the placenta of humans, rhesus monkeys, baboons and sheep. No specific immunohistochemical staining for type II NOS or CD14 was noted in the two rodent species, guinea-pig and rat. On Western blots, a 130-kDa type II NOS species was identified in semi-purified placental homogenates of every species except guinea-pig, although weak bands were seen for rhesus monkey and baboon. The failure of the antibodies to show type II NOS in the rat placenta by immunohistochemistry may be due to a difference in antigen conformation from Western blots. As only human placental syncytiotrophoblast expresses type III NOS, the putative functions ascribed to this isoform in syncytiotrophoblast, i.e., to prevent platelet and leucocyte aggregation in the intervillous space and adhesion to the trophoblast surface or to mediate peptide hormone release from trophoblast, may be unique to humans. Alternatively, syncytiotrophoblast-derived NO may fulfill some other unknown function. The similar pattern of expression of type II NOS in those species with villous fetomaternal interdigitation and multivillous fetomaternal blood flow interrelations may represent a more universal role in surveillance and/or protection against maternal insults or pathogens by immunologic activation and subsequent synthesis of nitric oxide which exerts a cytostatic/cytotoxic response.
使用亚型特异性抗体，比较了人类、恒河猴、狒狒、豚鼠、大鼠和绵羊足月胎盘组织中Ⅱ型（诱导型或巨噬细胞型）和Ⅲ型（内皮型）一氧化氮合酶（NOS）亚型的存在情况及免疫定位。在人类胎盘中，Ⅲ型NOS的免疫组化染色在合体滋养层细胞中呈强阳性，在血管内皮细胞中染色较弱。在恒河猴、狒狒、豚鼠、大鼠和绵羊胎盘中，仅血管内皮细胞显示Ⅲ型NOS染色阳性。在任何非人胎盘的滋养层细胞中均未观察到Ⅲ型NOS免疫染色阳性。蛋白质印迹法显示，通过ADP-琼脂糖亲和层析半纯化的所有受试物种胎盘匀浆中均存在一种135 kDa的Ⅲ型NOS蛋白条带，证实了抗体的特异性。Ⅱ型NOS免疫染色定位于人类、恒河猴、狒狒和绵羊胎盘中某些绒毛基质细胞，这些细胞也表达CD14（一种单核细胞/巨噬细胞标志物）。在豚鼠和大鼠这两种啮齿类动物中未观察到Ⅱ型NOS或CD14的特异性免疫组化染色。在蛋白质印迹法中，除豚鼠外，在每个物种半纯化的胎盘匀浆中均鉴定出一条130 kDa的Ⅱ型NOS蛋白条带，尽管在恒河猴和狒狒中可见较弱的条带。免疫组化未能在大鼠胎盘中显示Ⅱ型NOS，可能是由于抗原构象与蛋白质印迹法不同。由于只有人类胎盘合体滋养层细胞表达Ⅲ型NOS，因此该亚型在合体滋养层细胞中假定的功能，即防止绒毛间隙中的血小板和白细胞聚集以及黏附于滋养层表面，或介导滋养层细胞释放肽类激素，可能是人类特有的。或者，合体滋养层细胞衍生的NO可能具有其他未知功能。在那些具有绒毛母胎相互交错和多绒毛母胎血流相互关系的物种中，Ⅱ型NOS的相似表达模式可能代表了通过免疫激活和随后合成一氧化氮发挥细胞生长抑制/细胞毒性反应，在监测和/或抵御母体损伤或病原体方面发挥更普遍的作用。
