Amniotic fluid exosome proteomic profile exhibits unique pathways of term and preterm labor

Our objective was to determine the amniotic fluid-derived exosomal proteomic profile in patients who had spontaneous preterm birth (PTB) or preterm premature rupture of membranes (pPROM), compared to those who delivered at term. A cross-sectional study of a retrospective cohort was used to quantify and determine the protein content of exosomes present in amniotic fluid, in PTB or pPROM, and normal term labor (TL) or term not in labor (TNIL) pregnancies. Exosomes were isolated by differential centrifugation and quantified using nanocrystals (Qdot®) coupled to CD63 and placental alkaline phosphatase (PLAP) by fluorescence nanoparticle tracking analysis. The exosomal proteomic profile was identified by Liquid chromatography-mass spectrometry (LC-MS/MS) and a small ion library was constructed to quantify the proteomic data by SWATH analysis. Ingenuity Pathway Analysis determined canonical pathways and biofunctions associated with dysregulated proteins. Amniotic fluid exosomes have similar shape and quantity regardless of the conditions; however, PLAP/CD63 ratio for TL, PTB and pPROM were significantly higher (∼3.8-, ∼4.4-, and ∼3.5-fold, respectively) compared to TNIL. The PLAP/CD63 ratio was also significantly higher (∼1.3-fold) in PTB compared to pPROM. Biological functions are primarily indicating non-specific inflammatory response regardless of condition but unique profiles were also identified in cases (PTB and pPROM) compared to term. Amniotic fluid exosomes provide information specific to normal and abnormal parturition. Inflammatory marker enrichment and its uniqueness in term and preterm pregnancies support the value of exosomes in determining underlying physiology associated with term and preterm parturition