Single-cell transcriptome analyses reveal disturbed decidual homoeostasis in obstetric antiphospholipid syndrome

Objectives Obstetric antiphospholipid syndrome (OAPS) is an autoimmune disease characterised by the presence of antiphospholipid antibodies in circulation and pathological pregnancy. However, the pathogenesis of OAPS remains unknown. We aimed to reveal cellular compositions and molecular features of decidual cells involved in the development of OAPS using single-cell RNA sequencing (scRNA-seq).Methods We performed unbiased scRNA-seq analysis on the first-trimester decidua from five OAPS patients and five healthy controls (HCs), followed by validations with flow cytometry, immunohistochemical staining and immunofluorescence in a larger cohort. Serum chemokines and cytokines were measured by using ELISA.Results A higher ratio of macrophages but a lower ratio of decidual natural killer (dNK) cells was found in decidua from OAPS compared with HCs. Vascular endothelial cells shrinked in OAPS decidua while having upregulated chemokine expression and conspicuous responses to IFN-gamma and TNF-alpha. Macrophages in OAPS had stronger phagocytosis function, complement activation signals and relied more on glycolysis. dNK cells were more activated in OAPS and had enhanced cytotoxicity and IFN-gamma production. Downregulation of granules in OAPS dNK cells could be associated with suppressed glycolysis. Moreover, stromal cells had a prosenescent state with weakened immune surveillance for senescent cells in OAPS. In addition, the cellular interactions between decidual immune cells and those of immune cells with non-immune cells under disease state were altered, especially through chemokines, IFN-gamma and TNF-alpha.Conclusion This study provided a comprehensive decidual cell landscape and identified aberrant decidual microenvironment in OAPS, providing some potential therapeutic targets for this disease.