O-265 Mapping decidualization resistance at multi-omic level
Authors: Munoz Blat I , Perez R , Castillo-Marco N , Cordero T , Monfort R , Satorres E , Gormley M , Fisher S , Roson B , Simon C , Garrido-Gomez T 
Published: July 2024

Abstract

Study question
What are the cellular and molecular features of decidualization resistance (DR) at single-cell resolution?

Summary answer
There is an absence of the stromal-epithelial transition with aberrant crosstalk among cell types in essential pathways (e.g., endoglin, WNT) confirmed at the protein level.

What is known already
DR refers to the inability of the endometrium to undergo decidualization changes preparing the endometrium for a conceptus, noted in disorders like endometriosis, recurrent pregnancy loss, miscarriage and preeclampsia. The molecular mechanisms causing this disorder remains unknown. It has been demonstrated that there is a transcriptomic signature of DR in the endometrium of former preeclampsia patients, during and years after suffering from the disease. Our objective is to dilucidated what is DR at single-cell resolution.

Study design, size, duration
This cross-sectional study compares late secretory phase endometrial biopsies from patients that previously have suffered severe Preeclampsia (sPE). The sample size consisted of 11 sPE patients and 12 control participants for single-cell RNA sequencing (scRNA-seq), 8 sPE patients and 8 controls for spatial transcriptomic mapping covering 95 tissue regions, and 10 sPE patients and 10 controls for proteomic analysis. The study spanned 2 years, from sample collection to omics analysis.

Participants/materials, setting, methods
Late secretory phase endometrial biopsies from sPE patients and controls underwent molecular analyses. Methods included 10x Genomics protocol for single-cell RNA sequencing, MiloR to calculate cell abundance, CellChat to infer cell-to-cell communication and ClusterProfiler for gene ontology. We solved spatial mapping at transcriptomic level using Nanostring. Proteomics data was collected by laser-capture microdissection coupled mass spectrometry. Protein-protein networks, involving PR and ESR1 receptors as master regulators of decidualization, were built using String.

Main results and the role of chance
Initial morphological analyses of endometrial biopsies collected during the late secretory phase revealed gross anatomical defects in glandular morphology that were histologically confirmed. scRNA-seq revealed sPE-associated alterations in cell composition involving stromal and epithelial subtypes, denoting a higher proportion of cells expressing proliferative markers in the stroma (MMP11, SFRP1) and epithelium (IHH, EMID), and a near absent epithelial-stromal transition that is normally linked to decidualization. Further, abnormal abundance and gene dysregulation were detected in the three decidualized stages identified. Mapping cell-cell communication networks confirmed aberrant crosstalk among cell types involved in essential pathways (e.g., endoglin, WNT, SPP1). Spatial transcriptomic in a replication cohort of samples revealed a landscape of dysregulated genes in stromal, luminal and glandular enriched regions, corroborating sPE-associated DR. Laser capture microdissection/mass spectrometry of samples revealed differential protein expression at a global level and confirmed many of the scRNA-seq results, such as sPE-exclusive proteins related to proliferation and the absence of a stromal to epithelial transition at a pathway level. These data lend insights into potential molecular mechanisms underlying the pathogenesis of DR.

Limitations, reasons for caution
DR analysed in this work is associated with sPE but we do not know if this decidualization defect would be the same in other DR associated conditions such as endometriosis, recurrent pregnancy loss, or miscarriage.

Wider implications of the findings
Here we present the most comprehensive snapshot of DR to date, providing a full range of markers potentially responsible for this decidualization disorder linked to sPE. We concluded that stromal and epithelial cell populations are altered revealing a near absence of the stromal-epithelial transition, cellular crosstalk and glandular constitution.

Trial registration number
not aplicable