A defective lysophosphatidic acid-autophagy axis increases miscarriage risk by restricting decidual macrophage residence.

ABSTRACT

Massive infiltrated and enriched decidual macrophages (dMφ) have been widely regarded as important regulators of maternal-fetal immune tolerance and trophoblast invasion, contributing to normal pregnancy. However, the characteristics of metabolic profile and the underlying mechanism of dMφ residence remain largely unknown. Here, we observe that dMφ display an active glycerophospholipid metabolism. The activation of ENPP2-lysophosphatidic acid (LPA) facilitates the adhesion and retention, and M2 differentiation of dMφ during normal pregnancy. Mechanistically, this process is mediated through activation of the LPA receptors (LPAR1 and PPARG/PPARγ)-DDIT4-macroautophagy/autophagy axis, and further upregulation of multiple adhesion factors (e.g., cadherins and selectins) in a CLDN7 (claudin 7)-dependent manner. Additionally, poor trophoblast invasion and placenta development, and a high ratio of embryo loss are observed in Enpp2±, lpar1-/- or PPARG-blocked pregnant mice. Patients with unexplained spontaneous abortion display insufficient autophagy and cell residence of dMφ. In therapeutic studies, supplementation with LPA or the autophagy inducer rapamycin significantly promotes dMφ autophagy and cell residence, and improves embryo resorption in Enpp2± and spontaneous abortion mouse models, which should be dependent on the activation of DDIT4-autophagy-CLDN7-adhesion molecules axis. This observation reveals that inactivation of ENPP2-LPA metabolism and insufficient autophagy of dMφ result in resident obstacle of dMφ and further increase the risk of spontaneous abortion, and provides potential therapeutic strategies to prevent spontaneous abortion.Abbreviations ACTB actin beta; ADGRE1/F4/80 adhesion G protein-coupled receptor E1; Atg5 autophagy related 5; ATG13 autophagy related 13; BECN1 beclin 1; CDH1/E-cadherin cadherin 1; CDH5/VE-cadherin cadherin 5; CFSE carboxyfluorescein succinimidyl ester; CLDN7 claudin 7; CSF1/M-CSF colony stimulating factor 1; CSF2/GM-CSF colony stimulating factor 2; Ctrl control; CXCL10/IP-10 chemokine (C-X-C) ligand 10; DDIT4 DNA damage inducible transcript 4; dMφ decidual macrophage; DSC decidual stromal cells; ENPP2/ATX ectonucleotide pyrophosphatase/phosphodiesterase 2; Enpp2± Enpp2 heterozygous knockout mouse; ENPP2i/PF-8380 ENPP2 inhibitor; EPCAM epithelial cell adhesion molecule; ESC endometrial stromal cells; FGF2/b-FGF fibroblast growth factor 2; GAPDH glyceraldehyde-3-phosphate dehydrogenase; GPCPD1 glycerophosphocholine phosphodiesterase 1; HE heterozygote; HIF1A hypoxia inducible factor 1 subunit alpha; HNF4A hepatocyte nuclear factor 4 alpha; HO homozygote; ICAM2 intercellular adhesion molecule 2; IL interleukin; ITGAV/CD51 integrin subunit alpha V; ITGAM/CD11b integrin subunit alpha M; ITGAX/CD11b integrin subunit alpha X; ITGB3/CD61 integrin subunit beta 3; KLRB1/NK1.1 killer cell lectin like receptor B1; KRT7/cytokeratin 7 keratin 7; LPA lysophosphatidic acid; LPAR lysophosphatidic acid receptor; lpar1-/- lpar1 homozygous knockout mouse; LPAR1i/AM966 LPAR1 inhibitor; LY6C lymphocyte antigen 6 complex, locus C1; LYPLA1 lysophospholipase 1; LYPLA2 lysophospholipase 2; Lyz2 lysozyme 2; MAP1LC3B microtubule associated protein 1 light chain 3 beta; MARVELD2 MARVEL domain containing 2; 3-MA 3-methyladenine; MBOAT2 membrane bound O-acyltransferase domain containing 2; MGLL monoglyceride lipase; MRC1/CD206 mannose receptor C-type 1; MTOR mechanistic target of rapamycin kinase; NP normal pregnancy; PDGF platelet derived growth factor; PLA1A phospholipase A1 member A; PLA2G4A phospholipase A2 group IVA; PLPP1 phospholipid phosphatase 1; pMo peripheral blood monocytes; p-MTOR phosphorylated MTOR; PPAR peroxisome proliferator activated receptor; PPARG/PPARγ peroxisome proliferator activated receptor gamma; PPARGi/GW9662 PPARG inhibitor; PTPRC/CD45 protein tyrosine phosphatase receptor type, C; Rapa rapamycin; RHEB Ras homolog, mTORC1 binding; SA spontaneous abortion; SELE selectin E; SELL selectin L; siCLDN7 CLDN7-silenced; STAT signal transducer and activator of transcription; SQSTM1 sequestosome 1; TJP1 tight junction protein 1; VCAM1 vascular cell adhesion molecule 1; WT wild type.