Decidual NK response to infection

蜕膜NK细胞(DNK)，母胎界面最大的母体免疫细胞群 妊娠早期，直接接触胎儿绒毛外滋养细胞(EVT)，它侵入蜕膜以 重建血管系统以建立对胎盘的血液供应。DNK与EVT的直接接触 挑战母体免疫系统，母体免疫系统必须耐受胎儿细胞，但仍能保护免受感染。多么 DNK保护胎盘和胎儿免受感染的机制尚不清楚。临床上最有意义的感染 胎盘和胎儿是由细胞内的病原体(细菌、寄生虫和病毒)引起的，针对这些病原体的杀手 淋巴细胞(NK和细胞毒性T淋巴细胞)是系统保护性免疫的关键。在怀孕的前三个月， 当感染对胎儿造成最严重的后果时，蜕膜中的T细胞很少。虽然DNK 有细胞毒颗粒，表达所有的细胞毒分子，并杀伤常规的NK细胞靶点，其杀伤细胞 与外周血NK细胞相比，其活性降低。此外，尽管DNK与EVT建立了联系，但他们 不要脱颗粒或杀戮 人巨细胞病毒感染的EVT。这些发现强调了 母体免疫细胞清除胎盘感染，防止病原体传播给未出生的婴儿。 这一提议研究了我们最近发现的一种新颖而令人兴奋的机制，即DNK通过这种机制杀死L. 滋养层内的单核细胞增多症(LM)，而不会杀死宿主细胞。DNK表达大量颗粒溶素 (GNLY)，一种在细胞毒颗粒和胞浆中都发现的抗菌肽，它优先破坏 相对于哺乳动物而言，微生物的膜。我们的初步数据表明，DNK建立了纳米管 与室上性心动过速的细胞质连接。没有形成常规的免疫突触或脱颗粒，DNK 通过纳米管将GNLY转移到EVT，但不转移其他细胞毒性分子(穿孔素、颗粒酶)，这将杀死 宿主细胞。这一机制为妊娠防御的免疫困境提供了一个很好的解决方案 抗感染，同时保持对胎儿和胎盘的耐受性。据我们所知，这是第一次 纳米管具有免疫功能的证据。纳米管转移GNLY和潜在的其他生物活性 从DNK到EVT的分子有助于控制细胞内感染，并可以调节滋养层功能。我们的 目标是证实我们的初步数据显示，细胞内的微生物，而不是胎儿细胞，被 不依赖穿孔素和颗粒酶的GNLY的DNK转移；识别哪些被感染的母婴细胞 DNK在胎盘中的保护作用及通过什么机制；探讨纳米管的作用机制 形成，哪些分子被转移，哪些病原体在怀孕中重要是易感的。这个 GNLY和DNK在人胎盘组织外植体和小鼠体内的保护作用也将通过以下方法进行评估 比较GNLY转基因(TG)小鼠和未感染的WT小鼠的妊娠结局 快递GNLY。这些外植体和体内研究将调查怀孕的三种病原体--LM，B组 链球菌(GBS)和弓形虫。

Decidual NK cells (dNK), the largest population of maternal immune cells at the maternal-fetal interface in the first trimester of pregnancy, directly contact fetal extravillous trophoblasts (EVT), which invade the decidua to remodel the vasculature to establish the blood supply to the placenta. The direct contact between dNK and EVT challenges the maternal immune system, which must tolerate fetal cells, but still protect against infection. How dNK protect the placenta and fetus from infection is not well understood. Most clinically significant infections of the placenta and fetus are caused by intracellular pathogens (bacteria, parasites and viruses), for which killer lymphocytes (NK and cytotoxic T lymphocytes) are key to systemic protective immunity. In the first trimester, when infection has the most serious fetal consequences, there are few T cells in the decidua. Although dNK have cytotoxic granules, express all the cytotoxic molecules, and kill conventional NK cell targets, their cytolytic activity is reduced compared to peripheral blood NK cells. Moreover, although dNK form contacts with EVT, they do not degranulate or kill human cytomegalovirus-infected EVT. These findings emphasize the difficulties of maternal immune cells to clear placental infections and prevent transmission of pathogens to the unborn child. This proposal investigates a novel and exciting mechanism we recently discovered by which dNK kill L. monocytogenes (Lm) inside trophoblasts, without killing the host cell. dNK express large amounts of granulysin (GNLY), an antimicrobial peptide found both in cytotoxic granules and the cytosol that preferentially disrupts microbial, relative to mammalian, membranes. Our preliminary data suggest that dNK establish nanotube cytoplasmic connections to EVT. Without forming a conventional immune synapse or degranulating, dNK transfer GNLY via nanotubes to EVT, but not other cytotoxic molecules (perforin, granzymes), which would kill the host cell. This mechanism provides an elegant solution to the immune dilemma of pregnancy – defense against infection while maintaining tolerance of the fetus and placenta. As far as we are aware, this is the first evidence for an immune function of nanotubes. Nanotube transfer of GNLY and potentially other bioactive molecules from dNK to EVT helps control intracellular infection and could regulate trophoblast functions. Our goals are to confirm our preliminary data showing that intracellular microbes, but not fetal cells, are killed by dNK transfer of GNLY, independently of perforin and granzymes; identify which infected maternal and fetal cells in the placenta dNK protect and by what mechanism; explore the mechanism responsible for nanotube formation, which molecules are transferred and which pathogens important in pregnancy are susceptible. The protective role of GNLY and dNK will also be evaluated in human placental tissue explants and in mice by comparing pregnancy outcomes following infection of GNLY-transgenic (Tg) and WT mice, which do not express GNLY. These explant and in vivo studies will investigate three pathogens of pregnancy - Lm, Group B Streptococci (GBS) and Toxoplasma gondii.