Single-cell transcriptomic analysis of decidual immune cell landscape in the occurrence of adverse pregnancy outcomes induced by Toxoplasma gondii infection

Toxoplasma gondii (T. gondii) is an obligate intracellular parasite that can lead to adverse pregnancy outcomes, particularly in early pregnancy. Previous studies have illustrated the landscape of decidual immune cells. However, the landscape of decidual immune cells in the maternal–fetal microenvironment during T. gondii infection remains unknown. In this study, we employed single-cell RNA sequencing to analyze the changes in human decidual immune cells following T. gondii infection. Our results showed that the proportion of 17 decidual immune cell clusters and the expression levels of 21 genes were changed after T. gondii infection. Differential gene analysis demonstrated that T. gondii infection induced the differential expression of 279, 312, and 380 genes in decidual NK, dMf, and dT cells, respectively. Our findings first revealed that several previously unknown molecules in decidual immune cells changed following T. gondii infection. This result revealed that the function of maternal–fetal immune tolerance declined, whereas the killing ability of decidual immune cells enhanced, eventually contributing to the occurrence of adverse pregnancy outcomes. The results of this study provide a valuable resource for uncovering several novel molecules that play an important role in the occurrence of abnormal pregnancy outcomes induced by T. gondii infection. Overall design: In the present study, human decidual tissues from seven healthy pregnant women during first trimester were collected and then purified mononuclear cells. The purified cells were infected with T. gondii and analyzed with scRNA-seq.