CD4+ T cell heterogeneity and clonal expansion depend on gestational age and is altered in preeclampsia by single cell RNA sequence

The adequate balance between proinflammatory CD4+ T cells subsets and regulatory T cells (Tregs) in feto-maternal interface are important for maintaining healthy pregnancy. However, diversity of CD4+ T cells and Tregs in feto-maternal interface have not been fully understood. We utilized single-cell RNA sequences and T cell receptor analysis to study human CD4+ T cell at feto-maternal interface from healthy early gestation, healthy late gestation and preeclampsia. We identified 13 decidual CD4+ T cell subsets with unique phenotypes. Among them, one effector subset, one memory subset and FOXP3+Tregs showed distinctive change in gene expression pattern in accordance with gestational age and preeclampsia. Clonally expanded FOXP3+Tregs showed increased signatures of Treg exhaustion in preeclampsia.