Human gestation-associated tissues express functional cytosolic nucleic acid sensing pattern recognition receptors.

The role of viral infections in adverse pregnancy outcomes has gained interest in recent years. Innate immune pattern recognition receptors (PRRs) and their signalling pathways, that yield a cytokine output in response to pathogenic stimuli, have been postulated to link infection at the maternal-fetal interface and adverse pregnancy outcomes. The objective of this study was to investigate the expression and functional response of nucleic acid ligand responsive Toll-like receptors (TLR-3, -7, -8 and -9), and retinoic acid-inducible gene 1 (RIG-I)-like receptors [RIG-I, melanoma differentiation-associated protein 5 (MDA5) and Laboratory of Genetics and Physiology 2(LGP2)] in human term gestation-associated tissues (placenta, choriodecidua and amnion) using an explant model. Immunohistochemistry revealed that these PRRs were expressed by the term placenta, choriodecidua and amnion. A statistically significant increase in interleukin (IL)-6 and/or IL-8 production in response to specific agonists for TLR-3 (Poly(I:C); low and high molecular weight), TLR-7 (imiquimod), TLR-8 (ssRNA40) and RIG-I/MDA5 (Poly(I:C)LyoVec) was observed; there was no response to a TLR-9 (ODN21798) agonist. A hierarchical clustering approach was used to compare the response of each tissue type to the ligands studied and revealed that the placenta and choriodecidua generate a more similar IL-8 response, while the choriodecidua and amnion generate a more similar IL-6 response to nucleic acid ligands. These findings demonstrate that responsiveness via TLR-3, TLR-7, TLR-8 and RIG-1/MDA5 is a broad feature of human term gestation-associated tissues with differential responses by tissue that might underpin adverse obstetric outcomes.

Bioenergetic analysis of human peripheral blood mononuclear cells.

Leucocytes respond rapidly to pathogenic and other insults, with responses ranging from cytokine production to migration and phagocytosis. These are bioenergetically expensive, and increased glycolytic flux provides adenosine triphosphate (ATP) rapidly to support these essential functions. However, much of this work is from animal studies. To understand more clearly the relative role of glycolysis and oxidative phosphorylation in human leucocytes, especially their utility in a translational research setting, we undertook a study of human peripheral blood mononuclear cells (MNCs) bioenergetics. Glycolysis was essential during lipopolysaccharide (LPS)-mediated interleukin (IL)-1ß, IL-6 and tumour necrosis factor (TNF)-α production, as 2-deoxy-D-glucose decreased significantly the output of all three cytokines. After optimizing cell numbers and the concentrations of all activators and inhibitors, oxidative phosphorylation and glycolysis profiles of fresh and cryopreserved/resuscitated MNCs were determined to explore the utility of MNCs for determining the bioenergetics health profile in multiple clinical settings. While the LPS-induced cytokine response did not differ significantly between fresh and resuscitated cells from the same donors, cryopreservation/resuscitation significantly affected mainly some measures of oxidative phosphorylation, but also glycolysis. Bioenergetics analysis of human MNCs provides a quick, effective means to measure the bioenergetics health index of many individuals, but cryopreserved cells are not suitable for such an analysis. The translational utility of this approach was tested by comparing MNCs of pregnant and non-pregnant women to reveal increased bioenergetics health index with pregnancy but significantly reduced basal glycolysis and glycolytic capacity. More detailed analysis of discrete leucocyte populations would be required to understand the relative roles of glycolysis and oxidative phosphorylation during inflammation and other immune responses.