Placental Exosomal miR-24-1-5p in LPS-Induced Inflammation

Intra-amniotic infection (IAI) is associated with substantial maternal and neonatal risks, yet the immunoregulatory role of the human placenta remains incompletely understood. We established an in vitro IAI model by co-culturing term human placental explants with lipopolysaccharide (LPS) and monitored temporal changes in inflammatory cytokines. Prolonged LPS exposure induced an early pro-inflammatory phase followed by an anti-inflammatory phase characterized by decreased TNF-a/IL-10 and IL-1ß/IL-1Ra ratios. Placenta-derived exosomes (Pd-Exos) were isolated from culture supernatants and subjected to miRNA sequencing, which identified miR-24-1-5p as a key upregulated miRNA in Pd-Exos from LPS-treated explants (1-LPS-Pd-Exos). After uptake by THP-1–derived macrophages, exosomal miR-24-1-5p targeted TNFAIP8, promoted macrophage apoptosis, and suppressed TNF-a and IL-1ß expression, thereby contributing to placental endotoxin tolerance. Overall design: Term placental explants from uncomplicated elective cesarean deliveries were cultured ex vivo either in complete medium (control) or in complete medium supplemented with 1 µg/mL LPS. After 18 h of culture, placenta-derived exosomes (Pd-Exos) were isolated from the supernatants of four control explants and four matched LPS-treated explants (1-LPS-Pd-Exos). Total exosomal RNA was extracted and subjected to small RNA library preparation and high-throughput miRNA sequencing. Differential expression analysis was performed between Pd-Exos and 1-LPS-Pd-Exos to identify miRNAs associated with placental endotoxin tolerance.