Gene Expression In Pregnancies Research Articles

489. Spatial transcriptomic analysis of placental tissue demonstrates differential gene expression in pregnancies with SARS-CoV-2 infection, SARS-CoV-2 placentitis, and controls

Abstract Background SARS-CoV-2 infection in pregnancy can cause placental abnormalities such as “SARS-CoV-2 placentitis” (histiocytic intervillositis, perivillous fibrin deposition, and villous trophoblast necrosis) that is irrespective of infection severity and associated with stillbirth. Mechanisms of SARS-CoV-2 placental injury are poorly understood. We investigated gene expression through next generation sequencing (NGS)-based spatial transcriptomics of placentas from SARS-CoV-2 infection and controls. Methods Cases of SARS-CoV-2 in pregnancy with normal histopathology [n=4], pandemic timeframe controls with normal histopathology [n=2], and SARS-CoV-2 placentitis [n=3] were examined using Amsterdam Criteria and CD68 staining. RNA was extracted from FFPE tissue and underwent 10x Genomics Visium spatial NGS. Gene expression was analyzed while retaining tissue structure (Fig 1). Sequences and images were processed with Space Ranger 1.3.1 and R Seurat v.4.1.1.51. Raw counts were normalized using SCTransform. The Louvain algorithm and t-SNE algorithm were used for clustering and visualization. Differentially expressed genes were identified with Seurat and MAST. Various downstream pathway and cell type enrichment analyses were performed on transcriptional clusters.Figure 1.Anatomy underlies placental gene expression heterogeneity. Section of a control placenta in H&E (left) and colored spots based on Louvain clustering of gene expression (right). The basal plate (dark blue, #4) is an area of fibrin and decidua adjacent to the uterine wall. Oxygenated maternal blood enters at the basal plate. Areas of terminal villi adjacent to the basal plate (green, #2) receive the highest oxygen with relative hypoxia further from the basal plate (salmon, #0 --> yellow, #1; pink, #5 is a subset of salmon). Stem villi (aqua, #3), which carry fetal blood to and from the placenta, form their own cluster. Results Anatomic structures were related to gene expression clusters (basal plate, villi; Fig 1). Clinical data is in Table 1. Unique clusters were present in controls compared to SARS-CoV-2 placentas with normal histopathology (Fig 2). Genes upregulated in a distinct cluster in controls showed enrichment of macrophages and increased expression of cell regulation and viral responses, such as the interleukin 1 receptor-like 1 (IL1RL1), indicating dysregulation of normal immune responses in SARS-CoV-2 placentas. We found significantly upregulated genes in villous areas of placentitis (neutrophil degranulation and interferon signaling; Fig 3) compared to normal SARS-CoV-2 cases.Table 1.Clinical data and categorization of cases.* Latency = time between SARS-CoV-2 infection and delivery admission. Controls were defined as no SARS-CoV-2 infection in pregnancy, negative SARS-CoV-2 PCR on hospital admission screen, and negative anti-SARS-CoV-2 spike protein IgG/IgM at delivery.Figure 2.Enrichment of macrophages and interleukin 1 receptor-like 1 gene in unique cluster present in control placentas.A) Clusters overlying placental slides are shown. B) Control placentas with normal histopathology (n=2) on left and SARS-CoV-2 (COVID) placentas with normal histopathology on right ((n=4). C) Plot of enriched cell marker genes upregulated in cluster 2 highlights macrophages, MKi67+ progenitor cells, and fibroblasts. D) IL1RL1 gene is shown as an example of the set of genes significantly upregulated in control placentas compared to SARS-CoV-2 placentas.Figure 3.SARS-CoV-2 placentitis cases demonstrate increased expression of acute inflammatory activation compared to SARS-CoV-2 infection cases with normal histopathology.A) Gene expression cluster differences in normal SARS-CoV-2 (COVID) placentas and SARS-CoV-2 placentitis cases are shown. Placentitis shows decreased trophoblast transcripts and increased immune populations. B) Differential gene expression, especially surrounding live villi, demonstrate increased expression of acute inflammatory/immune activation genes including pathways such as neutrophil degranulation and multiple interferon families. Conclusion This spatial transcriptomic analysis shows differential gene expression in control and SARS-CoV-2 placentas. SARS-CoV-2 placentitis demonstrates distinct acute inflammatory activation, providing pathophysiologic insight. Further pathway analysis of SARS-CoV-2-associated placental phenotypes is ongoing. Disclosures All Authors: No reported disclosures

Gestational diabetes is associated with changes in inflammatory gene expression related to human placental macrophages

Gestational diabetes (GDM) is associated with adverse pregnancy outcomes. Metabolic dysfunction with diabetes can alter immune responses. With GDM, changes in the placental immune system are thought to drive pregnancy complications. The objective of this study as to evaluate placental pro and anti-inflammatory gene expression in pregnancies complicated by GDM.

Sex-specific differences in placental global gene expression in pregnancies complicated by asthma

BackgroundChronic maternal asthma is associated with reduced growth of the female fetus and normal growth of the male fetus. The mechanisms that control the differential effects of maternal asthma on the fetus have not been fully elucidated but alterations in placental function may play a role. In the current study we have used microarray platform to examine fetal sex-specific global changes in placental gene expression in pregnancies complicated by asthma as compared to non-asthmatic subjects. MethodsPlacental RNA was extracted from 11 control subjects and 38 asthmatic subjects. Labeled cDNA was hybridized to an oligonucleotide chip with 1700 double spotted well-characterized human genes. Global gene expression data analysis and visualization were performed using the Binary Tree-Structured Vector Quantization (BTSVQ) software. Functional relationships of differentially expressed genes were assessed using protein–protein interaction database I2D, network analysis and visualization software NAViGaTOR and Ingenuity Pathway Analysis software. ResultsOverall, 65 genes were found to be altered in placentae of pregnancies complicated by asthma. Of these, only 6 genes were altered in male placentae. There were 59 gene changes in female placentae of asthmatic mothers relative to control placentae. Some of the sex-specific genes were associated with growth, inflammation and immune pathways. ConclusionThere are sex-specific alterations in placental gene expression in the presence of maternal asthma. Given that many of the identified genes in the female placentae were associated with or involved in cellular growth and tissue development, these may contribute to the sexually dimorphic difference in fetal growth in response to maternal asthma.