Zheng J, Li Y, Sang Y, et al. - Researchers investigated the role of pigment epithelium-derived factor (PEDF) from decidual natural killer (dNK) cells during early pregnancy via studying natural killer (NK) cells from decidua and peripheral blood along with decidual stromal cells (DSCs) isolated from normal pregnancy (NP) during the first trimester (6–10 weeks) and the matched patients suffering recurrent miscarriage (RM). They performed RNA-sequencing analysis of dNK cells to screen for potential key genes involved in RM. Examination was done of the expression of PEDF in dNK cells in NP and RM. To explore the regulatory mechanisms of PEDF at the maternal–foetal interface, establishment of a coculture system with lipopolysaccharide (LPS)-stimulated DSCs and NK cell supernatants derived from NP or RM was done. Women with NP (n = 61) and RM (n = 21) provided peripheral blood and decidual tissues for this study. Flow cytometry, western blot and immunohistochemistry were used to analyze the expression levels of PEDF in NK cells and its receptor on DSCs. They observed markedly higher RNA and protein expression of PEDF in normal dNK cells vs peripheral natural killer (pNK) cells. Compared with pNK cells cultured alone, raised PEDF expression was observed in pNK cells after coculture with DSCs or trophoblast cells. Per outcomes, PEDF from dNK cells checks the LPS-induced apoptosis and inflammation of DSCs to maintain DSCs homoeostasis and immune balance at the maternal–foetal interface during early pregnancy.