Activation of the IL-1β/CXCL1/MMP-10 axis in chorioamnionitis induced by inactivated Group B Streptococcus

Sex-Specific Dysconnective Brain Injuries and Neuropsychiatric Conditions such as Autism Spectrum Disorder Caused by Group B Streptococcus-Induced Chorioamnionitis

Global health efforts have increased against infectious diseases, but issues persist with pathogens like Group B Streptococcus (GBS). Preclinical studies have elaborated on the mechanistic process of GBS-induced chorioamnionitis and its impact on the fetal programming of chronic neuropsychiatric diseases. GBS inoculation in rodents demonstrated the following: (i) silent and self-limited placental infection, similar to human chorioamnionitis; (ii) placental expression of chemokines attracting polymorphonuclear (PMN) cells; (iii) in vitro cytokine production; (iv) PMN infiltration in the placenta (histologic hallmark of human chorioamnionitis), linked to neurobehavioral impairments like cerebral palsy and autism spectrum disorders (ASD); (v) upregulation of interleukin-1β (IL-1β) in the placenta and fetal blood, associated with higher ASD risk in humans; (vi) sex-specific effects, with higher IL-1β release and PMN recruitment in male placenta; (vii) male offspring exhibiting ASD-like traits, while female offspring displayed attention deficit and hyperactivity disorder (ADHD)-like traits; (viii) IL-1 and/or NF-kB blockade alleviate placental and fetal inflammation, as well as subsequent neurobehavioral impairments. These findings offer potential therapeutic avenues, including sex-adapted anti-inflammatory treatment (e.g., blocking IL-1; repurposing of FDA-approved IL-1 receptor antagonist (IL-1Ra) treatment). Blocking the IL-1 pathway offers therapeutic potential to alleviate chorioamnionitis-related disabilities, presenting an opportunity for a human phase II RCT that uses IL-1 blockade added to the classic antibiotic treatment of chorioamnionitis.

Matrix metalloproteinases in preterm prelabor rupture of membranes in the setting of chorioamnionitis: A scoping review

Fetal or gestational membranes extend from the placenta to enclose the fetus and amniotic fluid. While the membranes spontaneously rupture at term in normal pregnancies, they can rupture prematurely before the onset of labor, termed preterm prelabor rupture of membranes (PPROM). PPROM can be triggered by bacterial infection or sterile inflammation in the membranes, known as chorioamnionitis (CAM). The membranes derive their tensile strength from a collagen-rich extracellular matrix (ECM); as such, understanding the enzymes and processes that can degrade the membrane ECM are of paramount importance. Matrix metalloproteinases (MMPs) are a class of enzymes capable of degrading collagen and other components of the ECM, and can be induced by inflammation. We used a scoping review to address the question of how MMP activity is associated with PPROM, particularly their induction due to sterile or nonsterile CAM. We have found that the most studied MMPs in PPROM were MMPs 2, 8, and 9. Additionally, some MMPs are constitutively active, while others are induced by inflammation. Mechanistic studies of the pathways that induce MMP activation are sparse, and this area is ripe for future studies. Targeting MMP activation could be a future strategy to delay or prevent PPROM.

PSB0788 ameliorates maternal inflammation-induced periventricular leukomalacia-like injury

Studies have shown that periventricular leukomalacia (PVL) is a distinctive form of cerebral white matter injury that pertains to myelination disturbances. Maternal inflammation is a main cause of white matter injury. Intrauterine inflammation cellular will be propagated to the developing brain by the entire maternal-placental-fetal axis, and triggers neural immune injury. As a low-affinity receptor, adenosine A_2B receptor (A_2BAR) requires high concentrations of adenosine to be significantly activated in pathological conditions. We hypothesized that in the maternal inflammation-induced PVL model, a selective A_2BAR antagonist PSB0788 had the potential to prevent the injury. In this work, a total of 18 SD pregnant rats were divided into three groups, and treated with intraperitoneal injection of phosphate buffered saline (PBS), lipopolysaccharide (LPS), or LPS+PSB0788. Placental infection was determined by H&E staining and the inflammatory condition was determined by ELISA. Change of MBP, NG2 and CC-1 in the brain of the rats' offspring were detected by western blot and immunohistochemistry. Furthermore, LPS-induced maternal inflammation reduced the expression of MBP, which related to the decrease in the numbers of OPCs and mature oligodendrocytes in neonate rats. After treatment with PSB0788, the levels of MBP proteins increased in the rats' offspring, improved the remyelination. In conclusion, our study shows that the selective A_2BAR antagonist PSB0788 plays an important role in promoting the normal development of OPCs in vivo by the maternal inflammation-induced PVL model. Future studies will focus on the mechanism of PSB0788 in this model.

Animal Models of Chorioamnionitis: Considerations for Translational Medicine

Preterm birth is defined as any birth occurring before 37 completed weeks of gestation by the World Health Organization. Preterm birth is responsible for perinatal mortality and long-term neurological morbidity. Acute chorioamnionitis is observed in 70% of premature labor and is associated with a heavy burden of multiorgan morbidities in the offspring. Unfortunately, chorioamnionitis is still missing effective biomarkers and early placento- as well as feto-protective and curative treatments. This review summarizes recent advances in the understanding of the underlying mechanisms of chorioamnionitis and subsequent impacts on the pregnancy outcome, both during and beyond gestation. This review also describes relevant and current animal models of chorioamnionitis used to decipher associated mechanisms and develop much needed therapies. Improved knowledge of the pathophysiological mechanisms underpinning chorioamnionitis based on preclinical models is a mandatory step to identify early in utero diagnostic biomarkers and design novel anti-inflammatory interventions to improve both maternal and fetal outcomes.

Protective Effects of Interleukin-1 Blockade on Group B Streptococcus-Induced Chorioamnionitis and Subsequent Neurobehavioral Impairments of the Offspring

Group B Streptococcus (GBS) is one of the most common bacteria isolated in human chorioamnionitis. Placental infection due to GBS is a major risk factor for fetal organ injuries, preterm birth, perinatal morbidity and mortality, and life-long multiorgan morbidities. Preclinical and clinical studies have shown that GBS-induced infection drives polymorphonuclear (PMN) cell infiltration within the placenta, the hallmark of human chorioamnionitis. In preclinical and clinical studies, the upregulation of interleukin(IL)-1β in the placenta and maternal/fetal blood was associated with a high risk of neurodevelopmental impairments in the progeny. We hypothesized that targeted IL-1 blockade administered to the dam alleviates GBS-induced chorioamnionitis and the downstream fetal inflammatory response syndrome (FIRS). IL-1 receptor antagonist (IL-1Ra) improved the gestational weight gain of GBS-infected dams and did not worsen the infectious manifestations. IL-1Ra reduced the IL-1β titer in the maternal sera of GBS-infected dams. IL-1Ra decreased the levels of IL-1β, IL-6, chemokine (C-X-C motif) ligand 1 (CXCL1), and polymorphonuclear (PMN) infiltration in GBS-infected placenta. IL-1Ra treatment reduced the IL-1β titer in the fetal sera of GBS-exposed fetuses. IL-1 blockade also alleviated GBS-induced FIRS and subsequent neurobehavioral impairments of the offspring without worsening the outcome of GBS infection. Altogether, these results showed that IL-1 plays a key role in the physiopathology of live GBS-induced chorioamnionitis and consequent neurobehavioral impairments.

Sustained peripheral immune hyper-reactivity (SPIHR): an enduring biomarker of altered inflammatory responses in adult rats after perinatal brain injury

Background

Chorioamnionitis (CHORIO) is a principal risk factor for preterm birth and is the most common pathological abnormality found in the placentae of preterm infants. CHORIO has a multitude of effects on the maternal–placental–fetal axis including profound inflammation. Cumulatively, these changes trigger injury in the developing immune and central nervous systems, thereby increasing susceptibility to chronic sequelae later in life. Despite this and reports of neural–immune changes in children with cerebral palsy, the extent and chronicity of the peripheral immune and neuroinflammatory changes secondary to CHORIO has not been fully characterized.

Methods

We examined the persistence and time course of peripheral immune hyper-reactivity in an established and translational model of perinatal brain injury (PBI) secondary to CHORIO. Pregnant Sprague–Dawley rats underwent laparotomy on embryonic day 18 (E18, preterm equivalent). Uterine arteries were occluded for 60 min, followed by intra-amniotic injection of lipopolysaccharide (LPS). Serum and peripheral blood mononuclear cells (PBMCs) were collected at young adult (postnatal day P60) and middle-aged equivalents (P120). Serum and PBMCs secretome chemokines and cytokines were assayed using multiplex electrochemiluminescent immunoassay. Multiparameter flow cytometry was performed to interrogate immune cell populations.

Results

Serum levels of interleukin-1β (IL-1β), IL-5, IL-6, C–X–C Motif Chemokine Ligand 1 (CXCL1), tumor necrosis factor-α (TNF-α), and C–C motif chemokine ligand 2/monocyte chemoattractant protein-1 (CCL2/MCP-1) were significantly higher in CHORIO animals compared to sham controls at P60. Notably, CHORIO PBMCs were primed. Specifically, they were hyper-reactive and secreted more inflammatory mediators both at baseline and when stimulated in vitro. While serum levels of cytokines normalized by P120, PBMCs remained primed, and hyper-reactive with a robust pro-inflammatory secretome concomitant with a persistent change in multiple T cell populations in CHORIO animals.

Conclusions

The data indicate that an in utero inflammatory insult leads to neural–immune changes that persist through adulthood, thereby conferring vulnerability to brain and immune system injury throughout the lifespan. This unique molecular and cellular immune signature including sustained peripheral immune hyper-reactivity (SPIHR) and immune cell priming may be a viable biomarker of altered inflammatory responses following in utero insults and advances our understanding of the neuroinflammatory cascade that leads to perinatal brain injury and later neurodevelopmental disorders, including cerebral palsy.

Pathogenic mechanism, detection methods and clinical significance of group B Streptococcus

Group B Streptococcus (GBS) is the main pathogen of perinatal infection. It can lead to adverse pregnancy, maternal infection, premature delivery, abortion, stillbirth and a series of adverse maternal and infant outcomes such as neonatal sepsis, meningitis or pneumonia during delivery. In order to reduce the infection of perinatal pregnant and the adverse pregnancy outcome, more attention should be paid in the clinical practice, screening efforts, universal detection of GBS infection for pregnant women and preventive treatment for the possible mother infant infection. In this study, the biological characteristics, immunophenotype, major pathogenic mechanism, laboratory test methods and clinical significance of GBS are summarized.

NLRP3 inflammasome function and pyroptotic cell death in human placental Hofbauer cells

Alterations in the number and protein/gene expression of Hofbauer cells (HBCs) may play a role in microbial-driven/cytokine-mediated placental inflammation, and in subsequent pregnancy complications such as villitis, histologic chorioamnionitis, and the fetal inflammatory response syndrome. Pyroptosis is an inflammatory form of cell death mediated by the inflammasome, a multi-protein complex which drives the processing and secretion of interleukin 1 beta (IL-1β). Pyroptosis can be triggered by bacterial lipopolysaccharide (LPS) and adenosine triphosphate (ATP) in non-placental macrophages through activation of the NLRP3 inflammasome. However, the role of inflammasome activation and pyroptosis in HBC pathophysiology remains unclear. HBCs isolated from human term placentas were treated with or without LPS or ATP, alone or in combination. Treatment of HBCs with both LPS and ATP induced the rapid secretion of high levels of IL-1β and at the same time, cell death associated with nuclear condensation and cellular swelling. HBC treatment with both LPS and ATP induced caspase-1 activation, gasdermin D (GSDMD) cleavage, which mediates pyroptosis, and IL-1β processing. Caspase-1 activation, GSDMD cleavage, IL-1β processing, and IL-1β secretion were all significantly reduced following NLRP3 knockdown; inhibition of caspase-1; and inhibition of P2X7, the receptor that mediates K⁺ efflux. Together, our data indicate that LPS and ATP treatment stimulated NLRP3 inflammasome activation and pyroptosis in HBCs leading to the rapid release of IL-1β. Since the localization of HBCs confers a unique ability to influence microbial-associated placental and fetal inflammation, these studies suggest a key role for the inflammasome and pyroptosis in mediating HBC driven inflammation.

Ampicillin Treatment Increases Placental Interleukin-1 Beta Concentration and Polymorphonuclear Infiltration in Group B Streptococcus-Induced Chorioamnionitis: A Preclinical Study

BACKGROUND

Antibiotic therapy during preterm labor with intact membranes has been associated with an increased risk of neonatal death.

OBJECTIVES

Using an established rat model of group B Streptococcus (GBS)-induced chorioamnionitis, we hypothesized that ampicillin treatment increases placental inflammation, as shown in other bacterial infections.

METHODS

At gestational day 19, 19 Lewis dams were intraperitoneally (i.p.) inoculated by 108 CFU of β-hemolytic serotype Ia GBS (strain #16955 susceptible to ampicillin). Dams were treated i.p. with either 200 mg/kg of ampicillin (n = 9) or 0.9% saline (n = 10) at 48 and 60 h post-GBS inoculation. Cesarean sections were performed 72 h post-GBS inoculation.

RESULTS

Ampicillin treatment was associated with an increased number of polymorphonuclear cells (PMN) infiltrating the decidua (mean 1,536 vs. 532 PMN/mm2; p < 0.001) and a higher placental concentration of IL-1β (mean 26.4 vs. 7.9 pg/mg; p < 0.01) compared to saline-treated dams. These effects were observed in dams without GBS bacteremia. Conversely, ampicillin treatment was associated with a decreased placental concentration of proinflammatory cytokines in dams with GBS bacteremia.

CONCLUSIONS

Ampicillin increases placental inflammation in a rat model of GBS-induced chorioamnionitis without bacteremia. This proinflammatory effect of ampicillin could be due to bacterial lysis. Our findings do not query the intrapartum antibiotic prophylaxis against GBS disease. They pave the way for future preclinical studies combining anti-inflammatory treatments and antibiotic therapy for GBS-induced chorioamnionitis.

Average and time-specific maternal prenatal inflammatory biomarkers and the risk of labor epidural associated fever

Background

The use of labor epidural analgesia has been associated with intrapartum fever, known as labor epidural associated fever (LEAF). LEAF is most commonly non-infectious in origin and associated with elevated inflammatory cytokines.

Methods

The LIFECODES pregnancy cohort was designed to prospectively collect data to evaluate the association of maternal inflammatory biomarkers with preterm birth in women who delivered between 2007 and 2008 at Brigham and Women’s Hospital. Our secondary analysis of the data from the cohort identified 182 women for whom inflammatory biomarkers (i.e. interleukin-10, interleukin-1β, interleukin-6, tumor necrosis factor-α and C-reactive protein) collected longitudinally over four prenatal visits was available. Maternal temperature and other clinical variables were abstracted from medical records. The primary outcome, the presence of LEAF, was defined as oral temperature ≥ 38°C (≥100.4°F) after epidural analgesia initiation. Multivariable logistic regression estimated the association between inflammatory biomarker concentrations and the odds of developing an intrapartum fever after adjusting for a number of potential confounders.

Results

Women who developed LEAF were more likely to have a longer duration of epidural analgesia, whereas women who did not develop LEAF were more likely to have induced labor and positive or unknown Group B Streptococcus colonization status. However, no differences were seen by nulliparity, mode of delivery, white blood cell count at admission, baseline temperature, length of rupture of membranes and number of cervical exams performed during labor. Unadjusted and multivariable logistic regression models did not provide evidence for or exclude an association between individual maternal inflammatory biomarkers and the odds of developing LEAF, regardless of visit time-period.

Conclusion

The predictive value of maternal inflammatory biomarkers measured during early- and mid-pregnancy for the risk of developing LEAF cannot be excluded.

Granulocyte macrophage colony stimulating factor (GM-CSF), the critical intermediate of inflammation-induced fetal membrane weakening, primarily exerts its weakening effect on the choriodecidua rather than the amnion

INTRODUCTION

We have previously demonstrated two associations of PPROM, (1) inflammation/infection (modeled by tumor necrosis factor (TNF)) and (2) decidual bleeding (modeled by thrombin), both decrease fetal membrane (FM) rupture strength in-vitro. Furthermore, Granulocyte-Macrophage-Colony-Stimulating-Factor (GM-CSF) induced by both TNF and thrombin is a critical intermediate, necessary and sufficient for weakening by either agent. The amnion is the strength component of FM and must weaken for FM to rupture. It is unclear whether GM-CSF weakens amnion (AM) directly, or initially targets choriodecidua (CD) which secondarily releases agents to act on amnion.

METHODS

Full thickness FM fragments were treated with/without GM-CSF. Some were preincubated with alpha-lipoic acid (LA), a known inhibitor of FM weakening. The FM fragments were then strength-tested. Separately, FM fragments were initially separated to AM and CD. AM fragments were cultured with Medium ± GM-CSF and then strength-tested. In other experiments, CD fragments were cultured with Medium, GM-CSF, LA, or LA + GM-CSF. Conditioned medium from each group was then incubated with AM. AM was then strength-tested. Matrix Metalloproteinases (MMPs) and Tissue Inhibitors of Matrix Metalloproteinases (TIMPs) were analyzed by Mutiplex Elisa.

RESULTS

GM-CSF weakened intact FM which was blocked by LA. GM-CSF did not weaken isolated AM. However, GM-CSF conditioned CD media weakened AM and this weakening was inhibited by LA. GM-CSF treatment of CD increased MMPs 2, 9, and 10, and decreased TIMPs 1-3. LA reversed these effects.

CONCLUSIONS

GM-CSF does not weaken amnion directly; GM-CSF acts on CD to increase proteases and decrease anti-proteases which secondarily weaken the amnion.

The feto-maternal immune response to equine placentitis

PROBLEM

Ascending placentitis is one of the leading causes of abortion in the horse. Minimal work has focused on its effect on fetal fluids or the antenatal immune response of the fetus.

METHODOLOGY

Placentitis was induced via transcervical inoculation of Streptococcus equi ssp Zooepidemicus, and fluids/serum/tissues were collected 4-6 days later following euthanasia. Cytokine concentrations were detected using a multiplex immunoassay within fetal fluids (amniotic and allantoic) and serum (maternal and fetal) in inoculated and control mares. In addition, tissues from fetal (spleen, liver, lung, umbilicus, amnioallantois) and maternal (spleen, liver, lung, chorioallantois, endometrium) origin were analyzed in inoculated and control mares utilizing qPCR for expression of cytokines.

RESULTS

No difference in cytokine concentrations in maternal or fetal serum was noted between inoculated and control mares. Concentrations of IL-1β, IL-6, IL-10, and GRO were upregulated in the amniotic fluid following inoculation, with a trend toward higher IL-6 concentration in allantoic fluid. The amnioallantoic tissue separating the two fluids had higher expression of IL-1β and IL-6 following inoculation, while chorioallantois and endometrium upregulated IL-1β and IL-8 expression. IL-1β was upregulated in the maternal spleen following inoculation. Fetal spleens were upregulated in expression of IL-1β, GRO, and IL-6, while IL-6 was higher in fetal liver after inoculation than in controls.

CONCLUSION

The maternal response to placentitis is primarily pro-inflammatory while the fetus appears to play a regulatory role in this inflammation. Additionally, amniotic fluid sampling may be more diagnostic of ascending placentitis than circulating cytokines.

Biomechanical and functional properties of trophoblast cells exposed to Group B Streptococcus in vitro and the beneficial effects of uvaol treatment

BACKGROUND

Group B streptococcus (GBS) is the main bacteria that infects pregnant women and can cause abortion and chorioamnionitis. The impact of GBS effects on human trophoblast cells remains largely elusive, and actions toward anti-inflammatory strategies in pregnancy are needed. A potent anti-inflammatory molecule, uvaol is a triterpene from olive oil and its functions in trophoblasts are unknown. We aimed to analyze biomechanical and functional effects of inactivated GBS in trophoblast cells, with the addition of uvaol to test potential benefits.

METHODS

HTR-8/SVneo cells were treated with uvaol and incubated with inactivated GBS. Cell viability and death were analyzed. Cellular elasticity and topography were accessed by atomic force microscopy. Nitrite production was evaluated by Griess reaction. Nuclear translocation of NFkB p65 was detected by immunofluorescence and Th1/Th2 cytokines by bead-based multiplex assay.

RESULTS

GBS at 10⁸ CFU increased cell death, which was partially prevented by uvaol. Cell stiffness, cytoskeleton organization and morphology were changed by GBS, and uvaol partially restored these alterations. Nuclear translocation of NFkB p65 began 15 min after GBS incubation and uvaol inhibited this process. GBS decreased IL-4 secretion and increased IL-1β, IFN-γ and IL-2, whereas uvaol reverted this.

CONCLUSIONS

The increased inflammation and cell death caused by GBS correlated with biomechanical and cytoskeleton changes found in trophoblast cells, while uvaol was effective its protective role.

GENERAL SIGNIFICANCE

Uvaol is a natural anti-inflammatory product efficient against GBS-induced inflammation and it has potential to be acquired through diet in order to prevent GBS deleterious effects in pregnancy.

Sex-specific maternofetal innate immune responses triggered by group B Streptococci

Group B Streptococcus (GBS) is one of the most common bacteria isolated in human chorioamnionitis, which is a major risk factor for premature birth and brain injuries. Males are at greater risk than females for developing lifelong neurobehavioural disorders, although the origins of this sex bias remain poorly understood. We previously showed that end-gestational inflammation triggered by GBS led to early neurodevelopmental impairments mainly in the male rat progeny. Identifying key inflammatory players involved in maternofetal immune activation by specific pathogens is critical to develop appropriate novel therapeutic interventions. We aimed to map out the GBS-induced profile of innate immune biomarkers in the maternal-placental-fetal axis, and to compare this immune profile between male and female tissues. We describe here that the GBS-induced immune signalling involved significantly higher levels of interleukin (IL)-1β, cytokine-induced neutrophil chemoattractant-1 (CINC-1/CXCL1) and polymorphonuclear cells (PMNs) infiltration in male compared to female maternofetal tissues. Although male - but not female - fetuses presented increased levels of IL-1β, fetuses from both sexes in-utero exposed to GBS had increased levels of TNF-α in their circulation. Levels of IL-1β detected in fetal sera correlated positively with the levels found in maternal circulation. Here, we report for the first time that the maternofetal innate immune signalling induced by GBS presents a sexually dichotomous profile, with more prominent inflammation in males than females. These sex-specific placental and fetal pro-inflammatory responses are in keeping with the higher susceptibility of the male population for preterm birth, brain injuries and neurodevelopmental disorders such as cerebral palsy and autism spectrum disorders.

CXCR2 Blockade Mitigates Neural Cell Injury Following Preclinical Chorioamnionitis

Minimizing central nervous system (CNS) injury from preterm birth depends upon identification of the critical pathways that underlie essential neurodevelopmental and CNS pathophysiology. While chorioamnionitis (CHORIO), is a leading cause of preterm birth, the precise mechanism linking prenatal brain injury and long-term CNS injury is unknown. The chemokine (C-X-C motif) ligand 1 (CXCL1) and its cognate receptor, CXCR2, are implicated in a variety of uterine and neuropathologies, however, their role in CNS injury associated with preterm birth is poorly defined. To evaluate the putative efficacy of CXCR2 blockade in neural repair secondary to CHORIO, we tested the hypothesis that transient postnatal CXCR2 antagonism would reduce neutrophil activation and mitigate cerebral microstructural injury in rats. To this end, a laparotomy was performed on embryonic day 18 (E18) in Sprague Dawley rats, with uterine arteries transiently occluded for 60 min, and lipopolysaccharide (LPS, 4 μg/sac) injected into each amniotic sac. SB225002, a CXCR2 antagonist (3 mg/kg), was administered intraperitoneally from postnatal day 1 (P1)-P5. Brains were collected on P7 and P21 and analyzed with western blot, immunohistochemistry and ex vivo diffusion tensor imaging (DTI). Results demonstrate that transient CXCR2 blockade reduced cerebral neutrophil activation (myeloperoxidase expression/MPO) and mitigated connexin43 expression, indicative of reduced neuroinflammation at P7 (p < 0.05 for all). CXCR2 blockade also reduced alpha II-spectrin calpain-mediated cleavage, improved pNF/NF ratio, and minimized Iba1 and GFAP expression consistent with improved neuronal and axonal health and reduced gliosis at P21. Importantly, DTI revealed diffuse white matter injury and decreased microstructural integrity following CHORIO as indicated by lower fractional anisotropy (FA) and elevated radial diffusivity (RD) in major white matter tracts (p < 0.05). Early postnatal CXCR2 blockade also reduced microstructural abnormalities in white matter and hippocampus at P21 (p < 0.05). Together, these data indicate that transient postnatal blockade of CXCR2 ameliorates perinatal abnormalities in inflammatory signaling, and facilitates neural repair following CHORIO. Further characterization of neuroinflammatory signaling, specifically via CXCL1/CXCR2 through the placental-fetal-brain axis, may clarify stratification of brain injury following preterm birth, and improve use of targeted interventions in this highly vulnerable patient population.

Causal role of group B Streptococcus-induced acute chorioamnionitis in intrauterine growth retardation and cerebral palsy-like impairments

Chorioamnionitis and intrauterine growth retardation (IUGR) are risk factors for cerebral palsy (CP). Common bacteria isolated in chorioamnionitis include group B Streptococcus (GBS) serotypes Ia and III. Little is known about the impact of placental inflammation induced by different bacteria, including different GBS strains. We aimed to test the impact of chorioamnionitis induced by two common GBS serotypes (GBSIa and GBSIII) on growth and neuromotor outcomes in the progeny. Dams were exposed at the end of gestation to either saline, inactivated GBSIa or GBSIII. Inactivated GBS bacteria invaded placentas and triggered a chorioamnionitis featured by massive polymorphonuclear cell infiltrations. Offspring exposed to GBSIII - but not to GBSIa - developed IUGR, persisting beyond adolescent age. Male rats in utero exposed to GBSIII traveled a lower distance in the Open Field test, which was correlating with their level of IUGR. GBSIII-exposed rats presented decreased startle responses to acoustic stimuli beyond adolescent age. GBS-exposed rats displayed a dysmyelinated white matter in the corpus callosum adjacent to thinner primary motor cortices. A decreased density of microglial cells was detected in the mature corpus callosum of GBSIII-exposed males - but not females - which was correlating positively with the primary motor cortex thickness. Altogether, our results demonstrate a causal link between pathogen-induced acute chorioamnionitis and (1) IUGR, (2) serotype- and sex-specific neuromotor impairments and (3) abnormal development of primary motor cortices, dysmyelinated white matter and decreased density of microglial cells.

Chorioamnionitis exposure remodels the unique histone modification landscape of neonatal monocytes and alters the expression of immune pathway genes

Chorioamnionitis is an intrauterine infection involving inflammation of the chorion, amnion, and placenta. It leads to a fetal systemic inflammatory response that can alter the transcription of neonatal immune genes. We have previously shown that neonatal monocytes gain the activating histone tail modification H3K4me3 at promoter sites of immunologically important genes as development progresses from preterm neonate to adult. In this study, we applied ChIP-seq and RNA-seq to evaluate the impact of chorioamnionitis on the neonatal monocyte H3K4me3 histone modification landscape over the course of fetal and neonatal immune system development. Chorioamnionitis exposure in neonatal monocytes resulted in a net increase in total monocyte H3K4me3, primarily in introns and intergenic regions. Immune gene expression was decreased in chorioamnionitis-exposed monocytes, with the majority of enriched transcripts falling into pathways that are not linked to the immune system. Over half of all neonatal monocyte H3K4me3 peaks, independent of their location, were associated with active gene transcription. Overall, chorioamnionitis exposure resulted in the global remodeling of the neonatal monocyte H3K4me3 landscape and changes in the expression of known immune genes. These changes resulted in a less robust inflammatory response upon exposure to a secondary challenge, which may explain why chorioamnionitis-exposed neonates have an increased risk of sepsis. DATABASE: ChIP-seq data for U30/O30/Term: GEO GSE81957 ChIP-seq data for U30C/O30C/TermC: GEO GSE111873 RNA-seq data for U/L/CU/CL: GEO GSE111927.

Hyperactive behavior in female rats in utero-exposed to group B Streptococcus-induced inflammation

Group B Streptococcus (GBS) is one the most common bacterium responsible of maternal infections during pregnancy. Offspring in utero-exposed to GBS-induced placental inflammation displayed sex-specific forebrain injuries. Sex differences have been reported in several neuropsychiatric disorders. Hence, we hypothesized that female rats in utero-exposed to GBS may present sex-specific neurobehavioral impairments. Lewis rats were injected intraperitoneally every 12 h from gestational day (G) 19 to G22 with either saline (controls) or inactivated serotype Ia GBS (10⁹ CFU). Before puberty, no difference in terms of spontaneous motor activity, exploratory or anxiety-related behaviors was noticed between experimental conditions. During puberty, GBS-exposed females - but not males - performed worse than same-sex controls in a forced motor task. During adulthood, GBS-exposed females - but not males - displayed increased spontaneous locomotor activity and decreased inhibition. In conclusion, our findings show for the first time that adult females - but not males - in utero-exposed to GBS-induced inflammation presented a hyperactive and disinhibited phenotype emerging after puberty.

Placenta immune infiltrates and perinatal outcomes

Pregnancy is a state of immunotolerance and loss of this immunotolerance may lead to fetal rejection, pregnancy complications, and neonatal complications. Immunobiology of pregnancy is complex and involves unique immune cell populations specific to pregnancy, changes in mucosal immune cells and peripheral immune system, and reciprocal adaptations between the mother and the fetus. The mechanisms required for sustaining a healthy feto-placental barrier and a healthy pregnancy such as activation of regulatory immune responses with a predominance of regulatory T cells lead to immune evasion and propagation of cancer. It is intriguing to note that the immune pathways which are effective in limiting or eliminating cancer form the very basis for loss of feto-maternal tolerance. In this article, we aim to compare and contrast immunobiology of healthy and pathological pregnancies mirroring with cancer immunobiology with a focus on immune checkpoint receptors.

Group B Streptococcal Maternal Colonization and Neonatal Disease: Molecular Mechanisms and Preventative Approaches

Group B Streptococcus (GBS) colonizes the gastrointestinal and vaginal epithelium of a significant percentage of healthy women, with potential for ascending intrauterine infection or transmission during parturition, creating a risk of serious disease in the vulnerable newborn. This review highlights new insights on the bacterial virulence determinants, host immune responses, and microbiome interactions that underpin GBS vaginal colonization, the proximal step in newborn infectious disease pathogenesis. From the pathogen perspective, the function GBS adhesins and biofilms, β-hemolysin/cytolysin toxin, immune resistance factors, sialic acid mimicry, and two-component transcriptional regulatory systems are reviewed. From the host standpoint, pathogen recognition, cytokine responses, and the vaginal mucosal and placental immunity to the pathogen are detailed. Finally, the rationale, efficacy, and potential unintended consequences of current universal recommended intrapartum antibiotic prophylaxis are considered, with updates on new developments toward a GBS vaccine or alternative approaches to reducing vaginal colonization.

Preclinical chorioamnionitis dysregulates CXCL1/CXCR2 signaling throughout the placental-fetal-brain axis

In the United States, perinatal brain injury (PBI) is a major cause of infant mortality and childhood disability. For a large proportion of infants with PBI, central nervous system (CNS) injury begins in utero with inflammation (chorioamnionitis/CHORIO) and/or hypoxia-ischemia. While studies show CHORIO contributes to preterm CNS injury and is also a common independent risk factor for brain injury in term infants, the molecular mechanisms mediating inflammation in the placental-fetal-brain axis that result in PBI remain a gap in knowledge. The chemokine (C-X-C motif) ligand 1 (CXCL1), and its cognate receptor, CXCR2, have been clinically implicated in CHORIO and in mature CNS injury, although their specific role in PBI pathophysiology is poorly defined. Given CXCL1/CXCR2 signaling is essential to neural cell development and neutrophil recruitment, a key pathological hallmark of CHORIO, we hypothesized CHORIO would upregulate CXCL1/CXCR2 expression in the placenta and fetal circulation, concomitant with increased CXCL1/CXCR2 signaling in the developing brain, immune cell activation, neutrophilia, and microstructural PBI. On embryonic day 18 (E18), a laparotomy was performed in pregnant Sprague Dawley rats to induce CHORIO. Specifically, uterine arteries were occluded for 60min to induce placental transient systemic hypoxia-ischemia (TSHI), followed by intra-amniotic injection of lipopolysaccharide (LPS). Pups were born at E22. Placentae, serum and brain were collected along an extended time course from E19 to postnatal day (P)15 and analyzed using multiplex electrochemiluminescence (MECI), Western blot, qPCR, flow cytometry (FC) and diffusion tensor imaging (DTI). Results demonstrate that compared to sham, CHORIO increases placental CXCL1 and CXCR2 mRNA levels, concomitant with increased CXCR2⁺ neutrophils. Interestingly, pup serum CXCL1 expression in CHORIO parallels this increase, with sustained elevation through P15. Analyses of CHORIO brains reveal similarly increased CXCL1/CXCR2 expression through P7, together with increased neutrophilia, microgliosis and peripheral macrophages. Similar to the placenta, cerebral neutrophilia was defined by increased CXCR2 surface expression and elevated myeloperoxidase expression (MPO), consistent with immune cell activation. Evaluation of microstructural brain injury at P15 with DTI reveals aberrant microstructural integrity in the callosal and capsular white matter, with reduced fractional anisotropy in superficial and deep layers of overlying cortex. In summary, using an established model of CHORIO that exhibits mature CNS deficits mimicking those of preterm survivors, we show CHORIO induces injury throughout the placental-fetal-brain axis with a CXCL1/CXCR2 inflammatory signature, neutrophilia, and microstructural abnormalities. These data are concomitant with abnormal cerebral CXCL1/CXCR2 expression, and support temporal aberrations in CXCL1/CXCR2 and neutrophil dynamics in the placental-fetal-brain axis following CHORIO. These investigations define novel targets for directed therapies for infants at high risk for PBI.