Fetal growth restriction through parental and fetal immune gene variation and intercellular communications cascade. Fetal growth restriction through parental and fetal immune gene variation and intercellular communications cascade

Fetal growth restriction (FGR) affects 5-10% of pregnancies worldwide, and can have serious consequences for both mother and child. Both preventative and treatment strategies are currently largely lacking due to a poor understanding of the pathogenesis of FGR. There is strong genetic evidence for the involvement of KIR and HLA genes in FGR, however, the specific HLA and KIR risk alleles and their functional effects have been difficult to map due to linkage disequilibrium, maternal and paternal influence, and an inability to investigate pathological human pregnancies at critical early gestational stages. Here we demonstrate that the interaction between two defined genes, the maternal KIR2DL1 expressed on uterine natural killer (NK) cells, and the paternally-inherited HLA-C*0501, expressed on fetal trophoblast cells, leads to FGR in a humanised mouse model. We show that the initial KIR2DL1 and C*0501 interaction leads to pathogenic uterine arterial remodeling and a modulation of uterine NK cell function. We delineate how this initial effect cascades to changes in transcriptional expression and intercellular communication in a myriad of cell types and pathways at the maternal-fetal interface. These findings reveal new mechanistic insight into the importance of specific KIR and HLA risk alleles in FGR, and provide new avenues of prevention and treatment to reduce disease burden and improve long-term health outcomes of the child. Overall design: We built a mouse single cell atlas of uterine NK cells at mid-gesttaion (gd9.5), using both full length scRNA-seq and 3’ droplet-based scRNA-Seq, from the three different mating groups: KIR x C*05 (FGR), WT x C*05 (control 1) and C*05/KIR x WT mice (control 2). In the full length scRNA-seq cohort, we had five replicates per mating group; in the 3' droplet-based scRNA-Seq cohort, we had four replicates for WT x C*05 (control 1) and three replicates each for KIR x C*05 (FGR) and C*05/KIR x WT (control 2). We also analysed all cell types at the maternal-fetal interface at mid-gestation using droplet-based scRNA-seq from the three different mating groups, with three replicates per mating group.

胎儿生长受限（Fetal growth restriction, FGR）全球发生率为5%-10%，可对孕产妇及胎儿造成严重不良结局。目前由于对FGR的发病机制认知不足，临床仍缺乏有效的预防与治疗策略。已有充分遗传学证据表明，杀伤细胞免疫球蛋白样受体（Killer Immunoglobulin-like Receptor, KIR）与人类白细胞抗原（Human Leukocyte Antigen, HLA）基因参与FGR的发生发展，但由于连锁不平衡、父母双方的遗传影响，以及无法在妊娠早期关键阶段探究病理性人类妊娠进程，特定HLA、KIR风险等位基因及其功能效应难以被精准定位。本研究证实，在人源化小鼠模型中，子宫自然杀伤（NK）细胞表面表达的母体源性KIR2DL1，与胎儿滋养层细胞表面表达的父系遗传HLA-C*0501之间的相互作用可导致FGR。研究发现，KIR2DL1与HLA-C*0501的初始相互作用可引发病理性子宫动脉重塑，并调节子宫NK细胞的功能。本研究阐明了该初始效应如何级联引发母胎界面多种细胞类型及通路的转录表达改变与细胞间通讯异常。本研究结果为特定KIR与HLA风险等位基因在FGR中的作用机制提供了全新见解，并为降低疾病负担、改善子代长期健康结局提供了全新的预防与治疗思路。

实验设计：本研究针对3组不同交配组合的小鼠——KIR×C*05（FGR组）、野生型（WT）×C*05（对照组1）以及C*05/KIR×WT（对照组2），分别采用全长单细胞RNA测序（single-cell RNA sequencing, scRNA-seq）与3'液滴法单细胞RNA测序，构建妊娠中期（胚胎发育第9.5天，gd9.5）子宫NK细胞的单细胞转录组图谱。在全长scRNA-seq队列中，每组交配组合设置5个生物学重复；在3'液滴法scRNA-seq队列中，WT×C*05（对照组1）设置4个生物学重复，KIR×C*05（FGR组）与C*05/KIR×WT（对照组2）各设置3个生物学重复。此外，本研究采用液滴法scRNA-seq，针对上述3组交配组合的妊娠中期母胎界面所有细胞类型进行分析，每组设置3个生物学重复。