Epithelial to mesenchymal transition (EMT) of feto-maternal reproductive tissues generates inflammation: a detrimental factor for preterm birth

The relationship between gut microbiota and preterm premature rupture of membranes: Mechanisms of action and clinical applications

Preterm Premature Rupture of Membrane (PPROM) constitutes a prevalent obstetric complication that markedly heightens the risk of neonatal mortality and low birth weight, while also potentially impacting the psychological well-being of the mother. Despite established associations between PPROM and various underlying medical conditions or lifestyle factor, a definitive treatment strategy continues to remain unattainable. Contemporary research indicates that dysbiosis of the gut microbiome may play a significant role in the pathogenesis of PPROM. Consequently, this study endeavors to gather recent findings related to the mechanisms underlying intestinal dysbiosis in relation to PPROM. It aims to offer novel insights into this critical issue. An increasing amount of evidence suggests that specific intestinal bacteria have the capacity to translocate into the vascular system and the amniotic cavity during pregnancy. This happens as a consequence of imbalances or dysbiosis within the gut microbiota. This translocation may be facilitated by the presence of bacteria within the amniotic cavity, modifications in the vaginal microbiota, and activation of the Hypothalamus-Pituitary-Adrenal (HPA) axis, which initiates a physiological cascade that accelerates the progression of PPROM. In light of these findings, the preservation of gut microbial homeostasis, particularly through the application of probiotics or dietary modifications, may serve to alleviate the detrimental effects of dysbiosis on PPROM.

The effect of Polybrominated diphenyl ethers at the fetal blood-brain-barrier: evaluation using a microphysiological system

Background

Glutamate dysregulation leading to neuronal excitotoxicity and neuroinflammation are associated with neurological disorders, specifically autism spectrum disorders (ASD) in preterm neonates. The lack of physiologically relevant in vitro models has limited mechanistic understanding of glutamate dysregulation and neuroinflammation during pregnancy. This study evaluated the effect of environmental pollutant and flame retardant, Polybrominated Diphenyl Ethers (PBDE) 99 and 47, on cell viability, glutamate dysregulation, and neuroinflammation using a microphysiologic system (MPS) of human fetal blood-brain-barrier organ on a chip (FB-OOC).

Methods

The FB-OOC is composed of 3-cell culture chambers, connected by microchannels, containing 1) human brain microvessel endothelial cells (HBMEC), 2) human vascular pericytes (HBVP), and 3) a triculture of neurons, astrocytes, and microglia in a 5:2:1 ratio, respectively. To assess the effect of toxicants on glutamate dysregulation and neuroinflammation, control (standard media) endothelial cells were exposed to PBDE 99 and 47 (150 ng/mL). To mimic the passage of PBDE through the placenta, endothelial cells in FB-OOC were exposed to conditioned PDBE media (1:1) derived from a placenta-OOC. In parallel, triculture cells were directly treated in a 96-well plate. Dextran propagation over 72 h confirmed FB barrier function. The activation status of microglia was determined using immunocytochemistry for CD11 b and Iba1, respectively. Cell morphology (microscopy), cell cytotoxicity (Lactate Dehydrogenase and glutamate assays), and cytokines (multiplex assay) were measured.

Results

Physiologic FB-OOCs were characterized by 1) viable cell cultures expressing standard cell morphologies and cell-specific markers, 2) barrier formation confirmed by decreased dextran propagation over 72 h, and 3) baseline glutamate and pro-inflammatory cytokine production. On-chip PBDE and placenta-derived metabolites of PBDE treatment in the endothelial chamber induced cell cytotoxicity and significant upregulation of glutamate in the triculture but did not induce neuroinflammation nor microglia activation compared to the controls. Conversely, 2D triculture experiments showed direct PBDE treatment-induced significant neuroinflammation (TNF-α, GM-CSF, IL-8) compared to PBDE placenta-derived metabolites or controls.

Conclusion

This study established an FB model that recreated intercellular interactions. We report PBDE-induced glutamate dysregulation, often associated with the development of ASD, independent of neuroinflammation.

Role of E-cadherin in epithelial barrier dysfunction: implications for bacterial infection, inflammation, and disease pathogenesis

Epithelial barriers serve as critical defense lines against microbial infiltration and maintain tissue homeostasis. E-cadherin, an essential component of adherens junctions, has emerged as a pivotal molecule that secures epithelial homeostasis. Lately, its pleiotropic role beyond barrier function, including its involvement in immune responses, has become more evident. Herein, we delve into the intricate relationship between (dys)regulation of epithelial homeostasis and the versatile functionality of E-cadherin, describing complex mechanisms that underlie barrier integrity and disruption in disease pathogenesis such as bacterial infection and inflammation, among others. Clinical implications of E-cadherin perturbations in host pathophysiology are emphasized; downregulation, proteolytic phenomena, abnormal localization/signaling and aberrant immune reactions are linked with a broad spectrum of pathology beyond infectious diseases. Finally, potential therapeutic interventions that may harness E-cadherin to mitigate barrier-associated tissue damage are explored. Overall, this review highlights the crucial role of E-cadherin in systemic health, offering insights that could pave the way for strategies to reinforce/restore barrier integrity and treat related diseases.

Autophagy in reproduction and pregnancy-associated diseases

As advantageous as sexual reproduction is during progeny generation, it is also an expensive and treacherous reproductive strategy. The viviparous eukaryote has evolved to survive stress before, during, and after pregnancy. An important and conserved intracellular pathway for the control of metabolic stress is autophagy. The autophagy process occurs in multiple stages through the coordinated action of autophagy-related genes. This review summarizes the evidence that autophagy is an integral component of reproduction. Additionally, we discuss emerging in vitro techniques that will enable cellular and molecular studies of autophagy and its associated pathways in reproduction. Finally, we discuss the role of autophagy in the pathogenesis and progression of several pregnancy-related disorders such as preterm birth, preeclampsia, and intra-uterine growth restriction, and its potential as a therapeutic target.

Histologic Evidence of Epithelial-Mesenchymal Transition and Autophagy in Human Fetal Membranes

Preterm, prelabor rupture of the human fetal membranes (pPROM) is involved in 40% of spontaneous preterm births worldwide. Cellular-level disturbances and inflammation are effectors of membrane degradation, weakening, and rupture. Maternal risk factors induce oxidative stress (OS), senescence, and senescence-associated inflammation of the fetal membranes as reported mechanisms related to pPROM. Inflammation can also arise in fetal membrane cells (amnion/chorion) due to OS-induced autophagy and epithelial-mesenchymal transition (EMT). Autophagy, EMT, and their correlation in pPROM, along with OS-induced autophagy-related changes in amnion and chorion cells in vitro, were investigated. Immunocytochemistry staining of cytokeratin-18 (epithelial marker)/vimentin (mesenchymal marker) and proautophagy-inducing factor LC3B were performed in fetal membranes from pPROM, term not in labor, and term labor. Ultrastructural changes associated with autophagy were verified by transmission electron microscopy of the fetal membranes and in cells exposed to cigarette smoke extract (an OS inducer). EMT and LC3B staining was compared in the chorion from pPROM versus term not in labor. Transmission electron microscopy confirmed autophagosome formation in pPROM amnion and chorion. In cell culture, autophagosomes were formed in the amnion with OS treatment, while autophagosomes were accumulated in both cell types with autophagy inhibition. This study documents the association between pPROMs and amniochorion autophagy and EMT, and supports a role for OS in inducing dysfunctional cells that increase inflammation, predisposing membranes to rupture.

The Impact of Periodontal Disease on Preterm Birth and Preeclampsia

This review delves into the possible connection between periodontitis and negative pregnancy outcomes, such as preeclampsia and preterm birth. It highlights the potential influence of an unidentified microbial factor on preeclampsia and the effects of inflammatory responses on the rate of preterm births. Furthermore, it underscores the prevalent occurrence of oral ailments within the populace and their significant repercussions on quality of life. Hormonal fluctuations during pregnancy may exacerbate oral conditions such as pregnancy gingivitis and periodontitis, necessitating bespoke therapeutic approaches that take into account potential fetal ramifications. Periodontal disease, characterized by microbial attack and inflammatory response, results in tissue destruction and tooth loss. The oral cavity's susceptibility to bacterial colonization, which is primarily due to its role as a site for food intake, is highlighted. Furthermore, research indicates a correlation between inflammatory responses and factors such as prostaglandin E2 and IL-1β, and preterm birth. Therapeutic interventions are a focus of international research, with efforts being aimed at optimizing outcomes through larger studies involving pregnant women.