Biology subjects

Georges, H. M.

Publications and source records attributed to Georges, H. M..

3 recordsLinked to original sources

bioRxiv2025

miR-146a-3p packaged in small extracellular vesicles triggers fetal membrane inflammation in response to viral dsRNA through activation of Toll-like Receptor 7 and 8

Maternal infection and chorioamnionitis are one of the leading causes of preterm birth and neonatal morbidity. The relationship and mechanisms linking bacterial infections and preterm labor are well researched, however, less is known about the mechanisms involved in how viral infections contribute to preterm labor. Previous work from our group demonstrated that following bacterial triggers, fetal membranes (FMs) express elevated miR-146a-3p which in turn acts as an intermediate danger signal by activating TLR8 to induce a robust inflammatory response. Using an established FM explant model system, the role of this and other TLR7/8-activating miRs in the propagation of viral-induced inflammation was investigated. Following exposure to the viral dsRNA mimic and TLR8 agonist, Poly(I:C), expression of FM tissue TLR7/8-activating miRs were not elevated. Despite this, FM secretion of pro-inflammatory IL-6 and IL-8 were increased in response to Poly(I:C) in a TLR7- and TLR8-dependent manner. To investigate alternative methods of miR delivery, small extracellular vesicles (sEVs) from FM supernatants were isolated and found to contain elevated levels of miR-146a-3p and miR-21a under Poly(I:C) conditions. Furthermore, Poly(I:C)-induced IL-6 and IL-8 responses were reduced in the presence of an inhibitor of sEV biogenesis/release, and IL-6 production was reduced in the presence of a miR-146a-3p inhibitor. Together, these data suggests that sEVs produced from virally-stimulated human FMs contain and deliver elevated miR-146a-3p which acts as a danger signal to drive perpetuate inflammation via TLR7 and TLR8 activation. This work demonstrates a novel and important role for sEV packaged TLR7/8 activating-miR-146a-3p in FM inflammatory responses to viral infections.

immunology↗

bioRxiv2024

Buprenorphine Induces Human Fetal Membrane Sterile Inflammation

Opioid-use disorder (OUD) during pregnancy has increased in the United States to critical levels and is a leading cause of maternal morbidity and mortality. Untreated OUD is associated with pregnancy complications in particular, preterm birth. Medications for OUD, such as buprenorphine, are recommended with the added benefit that treatment during pregnancy increases treatment post-partum. However, the rate of preterm birth in individuals using illicit opioids or being treated with opioid agonist therapeutics is double that of the general population. Since inflammation in the placenta and the associated fetal membranes (FM) is a common underlying cause of preterm birth, we sought to determine if the opioid, buprenorphine, induces sterile inflammation in human FMs and to examine the mechanisms involved. Using an established in vitro human FM explant system, we report that buprenorphine significantly increased FM secretion of the inflammatory cytokine IL-6; the neutrophilic chemokine IL-8; and the inflammasome-mediated cytokine IL-1{beta}, mirroring the inflammatory profile commonly seen at the maternal-fetal interface in preterm birth. Other factors that were elevated in FMs exposed to buprenorphine included the mediators of membrane weakening, prostaglandin E2 (PGE2), and matrix metalloproteinases, MMP1 and MMP9. Furthermore, this sterile inflammatory and weakening FM response induced by buprenorphine was mediated in part by innate immune Toll-like receptor 4 (TLR4), the NLRP3 inflammasome, the -opioid receptor, and downstream NF{kappa}B and ERK/JNK/MAPK signaling. This may provide the mechanistic link between opioid use in pregnancy and the elevated risk for preterm birth. Since there are adverse consequences of not treating OUD, our findings may help identify ways to mitigate the impact opioids have on pregnancy outcomes while allowing the continuation of maintenance therapy.

immunology↗

bioRxiv2023

TLR8-Activating miR-146a-3p is an Intermediate Signal Contributing to Fetal Membrane Inflammation in Response to Bacterial LPS

Preterm birth is the largest contributor to neonatal morbidity and is often associated with chorioamnionitis, defined as inflammation/infection of the fetal membranes (FMs). Chorioamnionitis is characterized by neutrophil infiltration of the FMs and is associated with elevated levels of the neutrophil chemoattractant, interleukin (IL)-8, and the proinflammatory cytokine, IL-1{beta}. While FMs can respond to infections through innate immune sensors, such as Toll-like receptors (TLRs), the downstream mechanisms by which chorioamnionitis arises are not fully understood. A novel group of non-classical microRNAs (miR-21a, miR-29a, miR-146a-3p, Let-7b) function as endogenous danger signals by activating the ssRNA viral sensors TLR7 and TLR8. In this study, the pro-inflammatory roles of TLR7/TLR8-activating miRs were examined as mediators of FM inflammation in response to bacterial lipopolysaccharide (LPS) using an in vitro human FM explant system, an in vivo mouse model of pregnancy, and human clinical samples. Following LPS exposure, miR-146a-3p was significantly increased in both human FM explants and in wildtype mouse FMs. Expression of miR-146a-3p was also significantly elevated in FMs from women with preterm birth and chorioamnionitis. FM IL-8 and inflammasome-mediated IL-1{beta} production in response to LPS was dependent on miR-146a-3p and TLR8, downstream of TLR4 activation. In wildtype mice, LPS exposure increased FM IL-8 and IL-1{beta} production and induced preterm birth. In TLR7-/-/TLR8-/-mice, LPS exposure was able to initiate, but not sustain preterm birth, and FM inflammation was reduced. Together, we demonstrate a novel signaling mechanism at the maternal-fetal interface in which TLR8-activating miR-146a-3p acts as an intermediate danger signal to drive FM inflammasome-dependent and -independent mechanisms of inflammation and thus, may play a role in chorioamnionitis and subsequent preterm birth.

immunology↗