Although there is significant interest in elucidating the role of placenta-derived exosomes (PdEs) during pregnancy, the exosomal profile in pregnancies complicated by gestational diabetes mellitus (GDM) remains to be established. The aim of this study was to compare the gestational-age profile of PdEs in maternal plasma of GDM with normal pregnancies and to determine the effect of exosomes on cytokine release from human umbilical vein endothelial cells. A prospective cohort of patients was sampled at three time points during pregnancy for each patient (i.e., 11–14, 22–24, and 32–36 weeks' gestation). A retrospective stratified study design was used to quantify exosomes present in maternal plasma of normal (n = 13) and GDM (n = 7) pregnancies. Gestational age and pregnancy status were identified as significant factors contributing to variation in plasma exosome concentration (ANOVA, P < 0.05). Post hoc analyses established that PdE concentration increased during gestation in both normal and GDM pregnancies; however, the increase was significantly greater in GDM (∼2.2-fold, ∼1.5-fold, and ∼1.8-fold greater at each gestational age compared with normal pregnancies). Exosomes isolated from GDM pregnancies significantly increased the release of proinflammatory cytokines from endothelial cells. Although the role of exosomes during GDM remains to be fully elucidated, exosome profiles may be of diagnostic utility for screening asymptomatic populations.

Context: Hyperglycemia and hypoxia are risk factors of metabolic complication during pregnancy. The interactions between oxygen and glucose-sensing pathways that regulate exosome bioactivity from placental cells, however, have not been established. Objective: The aim of this study was to test the hypothesis that exosomal signaling by placental cells (defined as the number of exosomes released per unit time and their bioactivity) is responsive to extracellular glucose concentration. Methods: First-trimester primary trophoblast cells were incubated with D-glucose (5 mM or 25 mM) under 1%, 3%, or 8% O2 for 48 hours. Exosomes were isolated from cell-conditioned media by differential and buoyant density centrifugation. The total number of exosome vesicles was determined by quantifying immunoreactive exosomal CD63. The effect of exosomes on cytokine (granulocyte macrophage colony-stimulating factor, IL-2, IL-4, IL-6. IL-8, IL-10, interferon-γ, and TNF-α) release from endothelial cells was established by a protein solution array analysis. Results: Glucose (25 mM) significantly increased the release of exosomes from trophoblast cells at all oxygen tensions tested (by approximately 2-fold when compared with controls, P < .001). Exosomes (100 μg/mL exosomal protein) released from trophoblast cells significantly increased (P < .05) the release of all cytokines from human umbilical vein endothelial cells when compared with the control (ie, cells without exosomes), with the exception of IL-2 and IL-10 (P > .05). Conclusions: The effects of high glucose on exosomes bioactivity may be recapitulated in vivo and is of clinical relevance in association with maternal insulin resistance (resulting in hyperglycemia) and preeclampsia (associated with placental insufficiency and hypoxia).

SUMMARY: The human Ureaplasma species are the most frequently isolated microorganisms from the amniotic fluid and placentae of women who deliver preterm and are also associated with spontaneous abortions or miscarriages, neonatal respiratory diseases, and chorioamnionitis. Despite the fact that these microorganisms have been habitually found within placentae of pregnancies with chorioamnionitis, the role of Ureaplasma species as a causative agent has not been satisfactorily explained. There is also controversy surrounding their role in disease, particularly as not all women infected with Ureaplasma spp. develop chorioamnionitis. In this review, we provide evidence that Ureaplasma spp. are associated with diseases of pregnancy and discuss recent findings which demonstrate that Ureaplasma spp. are associated with chorioamnionitis, regardless of gestational age at the time of delivery. Here, we also discuss the proposed major virulence factors of Ureaplasma spp., with a focus on the multiple-banded antigen (MBA), which may facilitate modulation/alteration of the host immune response and potentially explain why only subpopulations of infected women experience adverse pregnancy outcomes. The information presented within this review confirms that Ureaplasma spp. are not simply “innocent bystanders” in disease and highlights that these microorganisms are an often underestimated pathogen of pregnancy.

Xanthine oxidase (XO) is distributed in mammals largely in the liver and small intestine, but also is highly active in milk where it generates hydrogen peroxide (H₂O₂). Adult human saliva is low in hypoxanthine and xanthine, the substrates of XO, and high in the lactoperoxidase substrate thiocyanate, but saliva of neonates has not been examined. Median concentrations of hypoxanthine and xanthine in neonatal saliva (27 and 19 μM respectively) were ten-fold higher than in adult saliva (2.1 and 1.7 μM). Fresh breastmilk contained 27.3±12.2 μM H₂O₂ but mixing baby saliva with breastmilk additionally generated >40 μM H₂O₂, sufficient to inhibit growth of the opportunistic pathogens Staphylococcus aureus and Salmonella spp. Oral peroxidase activity in neonatal saliva was variable but low (median 7 U/L, range 2–449) compared to adults (620 U/L, 48–1348), while peroxidase substrate thiocyanate in neonatal saliva was surprisingly high. Baby but not adult saliva also contained nucleosides and nucleobases that encouraged growth of the commensal bacteria Lactobacillus, but inhibited opportunistic pathogens; these nucleosides/bases may also promote growth of immature gut cells. Transition from neonatal to adult saliva pattern occurred during the weaning period. A survey of saliva from domesticated mammals revealed wide variation in nucleoside/base patterns. During breast-feeding, baby saliva reacts with breastmilk to produce reactive oxygen species, while simultaneously providing growth-promoting nucleotide precursors. Milk thus plays more than a simply nutritional role in mammals, interacting with infant saliva to produce a potent combination of stimulatory and inhibitory metabolites that regulate early oral–and hence gut–microbiota. Consequently, milk-saliva mixing appears to represent unique biochemical synergism which boosts early innate immunity.