Metabolic Reprogramming Driven by Trophoblasts and Decidual XCR1 + PMN‐MDSC Crosstalk Controls Adverse Outcomes Associated With Advanced Maternal Age

ABSTRACT Trophoblast–immune cell communication is crucial during pregnancy, with impairments linked to adverse outcomes. The accumulation of decidual polymorphonuclear myeloid‐derived suppressor cells (dPMN‐MDSCs) in the third trimester is vital for fetal development. This study presents a novel crosstalk mechanism between trophoblasts and dPMN‐MDSCs that improves adverse outcomes associated with advanced maternal age (AMA). A specific dPMN‐MDSC population with high X‐C motif chemokine receptor 1 (XCR1) expression is identified, which interacts with trophoblasts through X‐C motif chemokine ligand 1 (XCL1) during the third trimester. Spontaneous fetal growth restriction observed in AMA and pregnant Xcr1 −/− mice is correlated with the disruption of this interaction. Mechanistically, the deficiency in XCL1–XCR1 expression reduces nuclear FOXO1 levels, thereby impairing the transcription of FOXO1‐driven oxidative phosphorylation genes in decidual XCR1 + PMN‐MDSCs. Restoring the expression of XCL1–XCR1 or FOXO1 in dPMN‐MDSCs mitigates this effect. Crucially, their adoptive transfer or treatment with XCL1/Oltipraz rescues the delayed fetal growth linked to impaired decidual XCR1 + PMN‐MDSCs and metabolic imbalance. Our findings highlight the importance of trophoblast–dPMN‐MDSC communication via the XCL1–XCR1 axis, proposing metabolic reprogramming of dPMN‐MDSCs as a potential immunotherapeutic strategy for AMA‐related adverse outcomes.