Antenatal exposure to chorioamnionitis affects lipid metabolism in 7-week-old sheep

Antenatal diagnosis of chorioamnionitis: A review of the potential role of fetal and placental imaging

Chorioamnionitis is present in up to 70% of spontaneous preterm births. It is defined as an acute inflammation of the chorion, with or without involvement of the amnion, and is evidence of a maternal immunological response to infection. A fetal inflammatory response can coexist and is diagnosed on placental histopathology postnatally. Fetal inflammatory response syndrome (FIRS) is associated with poorer fetal and neonatal outcomes. The only antenatal diagnostic test is amniocentesis which carries risks of miscarriage or preterm birth. Imaging of the fetal immune system, in particular the thymus and the spleen, and the placenta may give valuable information antenatally regarding the diagnosis of fetal inflammatory response. While ultrasound is largely limited to structural information, MRI can complement this with functional information that may provide insight into the metabolic activities of the fetal immune system and placenta. This review discusses fetal and placental imaging in pregnancies complicated by chorioamnionitis and their potential future use in achieving non-invasive antenatal diagnosis. This article is protected by copyright. All rights reserved.

Understanding Host-Pathogen Interactions in Acute Chorioamnionitis Through the Use of Animal Models

Inflammation of the chorion and/or amnion during pregnancy is called chorioamnionitis. Acute chorioamnionitis is implicated in approximately 40% of preterm births and has wide-ranging implications for the mother, fetus, and newborn. Large disease burden and lack of therapeutic approaches drive the discovery programs to define and test targets to tackle chorioamnionitis. Central to the advancement of these studies is the use of animal models. These models are necessary to deepen our understanding of basic mechanisms of host-pathogen interactions central to chorioamnionitis disease pathogenesis. Models of chorioamnionitis have been developed in numerous species, including mice, rabbits, sheep, and non-human primates. The various models present an array of strategies for initiating an inflammatory response and unique opportunities for studying its downstream consequences for mother, fetus, or newborn. In this review, we present a discussion of the key features of human chorioamnionitis followed by evaluation of currently available animal models in light of these features and consideration of how these models can be best applied to tackle outstanding questions in the field.

Chorioamnionitis induces hepatic inflammation and time-dependent changes of the enterohepatic circulation in the ovine fetus

Chorioamnionitis, inflammation of fetal membranes, is an important cause of preterm birth and a risk factor for the development of adverse neonatal outcomes including sepsis and intestinal pathologies. Intestinal bile acids (BAs) accumulation and hepatic cytokine production are involved in adverse intestinal outcomes. These findings triggered us to study the liver and enterohepatic circulation (EHC) following intra-amniotic (IA) lipopolysaccharide (LPS) exposure. An ovine chorioamnionitis model was used in which circulatory cytokines and outcomes of the liver and EHC of preterm lambs were longitudinally assessed following IA administration of 10 mg LPS at 5, 12 or 24h or 2, 4, 8 or 15d before preterm birth. Hepatic inflammation was observed, characterized by increased hepatic cytokine mRNA levels (5h - 2d post IA LPS exposure) and increased erythropoietic clusters (at 8 and 15 days post IA LPS exposure). Besides, 12h after IA LPS exposure, plasma BA levels were increased, whereas gene expression levels of several hepatic BA transporters were decreased. Initial EHC alterations normalized over time. Concluding, IA LPS exposure induces significant time-dependent changes in the fetal liver and EHC. These chorioamnionitis induced changes have potential postnatal consequences and the duration of IA LPS exposure might be essential herein.

The fetal inflammatory response syndrome: the origins of a concept, pathophysiology, diagnosis, and obstetrical implications

The fetus can deploy a local or systemic inflammatory response when exposed to microorganisms or, alternatively, to non-infection-related stimuli (e.g., danger signals or alarmins). The term "Fetal Inflammatory Response Syndrome" (FIRS) was coined to describe a condition characterized by evidence of a systemic inflammatory response, frequently a result of the activation of the innate limb of the immune response. FIRS can be diagnosed by an increased concentration of umbilical cord plasma or serum acute phase reactants such as C-reactive protein or cytokines (e.g., interleukin-6). Pathologic evidence of a systemic fetal inflammatory response indicates the presence of funisitis or chorionic vasculitis. FIRS was first described in patients at risk for intraamniotic infection who presented preterm labor with intact membranes or preterm prelabor rupture of the membranes. However, FIRS can also be observed in patients with sterile intra-amniotic inflammation, alloimmunization (e.g., Rh disease), and active autoimmune disorders. Neonates born with FIRS have a higher rate of complications, such as early-onset neonatal sepsis, intraventricular hemorrhage, periventricular leukomalacia, and death, than those born without FIRS. Survivors are at risk for long-term sequelae that may include bronchopulmonary dysplasia, neurodevelopmental disorders, such as cerebral palsy, retinopathy of prematurity, and sensorineuronal hearing loss. Experimental FIRS can be induced by intra-amniotic administration of bacteria, microbial products (such as endotoxin), or inflammatory cytokines (such as interleukin-1), and animal models have provided important insights about the mechanisms responsible for multiple organ involvement and dysfunction. A systemic fetal inflammatory response is thought to be adaptive, but, on occasion, may become dysregulated whereby a fetal cytokine storm ensues and can lead to multiple organ dysfunction and even fetal death if delivery does not occur ("rescued by birth"). Thus, the onset of preterm labor in this context can be considered to have survival value. The evidence so far suggests that FIRS may compound the effects of immaturity and neonatal inflammation, thus increasing the risk of neonatal complications and long-term morbidity. Modulation of a dysregulated fetal inflammatory response by the administration of antimicrobial agents, anti-inflammatory agents, or cell-based therapy holds promise to reduce infant morbidity and mortality.

A perfect storm: fetal inflammation and the developing immune system

Histologic chorioamnionitis is an inflammatory disorder of the placenta that commonly precedes preterm delivery. Preterm birth related to chorioamnionitis and fetal inflammation has been associated with a risk for serious inflammatory complications in infancy. In addition, preterm infants exposed to chorioamnionitis may be more susceptible to infection in the neonatal intensive care unit and possibly later in life. A significant body of work has established an association between chorioamnionitis and inflammatory processes. However, the potential consequences of this inflammation on postnatal immunity are less understood. In this review, we will discuss current knowledge regarding the effects of fetal exposure to inflammation on postnatal immune responses.

In Utero Exposure to Histological Chorioamnionitis Primes the Exometabolomic Profiles of Preterm CD4+ T Lymphocytes

Histological chorioamnionitis (HCA) is an intrauterine inflammatory condition that increases the risk for preterm birth, death, and disability because of persistent systemic and localized inflammation. The immunological mechanisms sustaining this response in the preterm newborn remain unclear. We sought to determine the consequences of HCA exposure on the fetal CD4+ T lymphocyte exometabolome. We cultured naive CD4+ T lymphocytes from HCA-positive and -negative preterm infants matched for gestational age, sex, race, prenatal steroid exposure, and delivery mode. We collected conditioned media samples before and after a 6-h in vitro activation of naive CD4+ T lymphocytes with soluble staphylococcal enterotoxin B and anti-CD28. We analyzed samples by ultraperformance liquid chromatography ion mobility-mass spectrometry. We determined the impact of HCA on the CD4+ T lymphocyte exometabolome and identified potential biomarker metabolites by multivariate statistical analyses. We discovered that: 1) CD4+ T lymphocytes exposed to HCA exhibit divergent exometabolomic profiles in both naive and activated states; 2) ∼30% of detected metabolites differentially expressed in response to activation were unique to HCA-positive CD4+ T lymphocytes; 3) metabolic pathways associated with glutathione detoxification and tryptophan degradation were altered in HCA-positive CD4+ T lymphocytes; and 4) flow cytometry and cytokine analyses suggested a bias toward a TH1-biased immune response in HCA-positive samples. HCA exposure primes the neonatal adaptive immune processes by inducing changes to the exometabolomic profile of fetal CD4+ T lymphocytes. These exometabolomic changes may link HCA exposure to TH1 polarization of the neonatal adaptive immune response.

Acute and chronic immunomodulatory changes in rat liver after fetal and perinatal asphyxia

Hypoxic-ischemic encephalopathy (HIE) caused by fetal and perinatal asphyxia is an important cause of mortality in the neonatal period. Not only will asphyxia affect the brain but also other organs such as the liver and kidneys. Interestingly, it has been shown that liver damage is proportional to the severity of the asphyctic insult, implying an association between liver impairment and HIE. Accordingly, we investigated in an established rat model the acute and chronic hepatic response to both fetal (FA) and perinatal asphyxia (PA). In addition, we assessed whether fetal asphyctic preconditioning (PC) would have any beneficial effect on the liver. Inflammation, ceramide signaling and hepatocellular damage were analyzed in the livers of newborn and adult rats at several short- and long-term time points after both FA and PA. We found that although FA induced an acute inflammatory response, apoptotic mRNA levels and oxidative DNA damage were decreased at 96 h post FA. Whereas increased IL-6 and IL-10 mRNA levels were observed after PA, the combination of FA and PA (PC) attenuated the inflammatory response. Moreover, 6 h after PA anti-apoptotic genes were downregulated and associated with less lipid peroxidation, while preconditioned animals were comparable to controls. In summary, asphyctic PC seems to have an acute protective effect on the liver by modulating the inflammatory, apoptotic and anti-oxidative response. More insight into the hepatic response to asphyxia is necessary, as disturbed hepatic function is associated with metabolic diseases in later life.