Maternal Immune Activation Research Articles

The Importance of Including Maternal Immune Activation in Animal Models of Hypoxic–Ischemic Encephalopathy

The Importance of Including Maternal Immune Activation in Animal Models of Hypoxic–Ischemic Encephalopathy

Prenatal drivers of microglia vulnerability in the adult.

Environmental insults during early development heavily affect brain trajectories. Among these, maternal infections, high-fat diet regimens, and sleep disturbances pose a significant risk for neurodevelopmental derangements in the offspring. Notably, scattered evidence is starting to emerge that also paternal lifestyle habits may impact the offspring development. Given their key role in controlling neurogenesis, synaptogenesis and shaping neuronal circuits, microglia represent the most likely suspects of mediating the detrimental effects of prenatal insults. For some of these environmental triggers, like maternal infections, ample literature evidence demonstrates the central role of microglia, also delineating the specific transcriptomic and proteomic profiles induced by these insults. In other contexts, the analysis of microglia is still in its infancy. Fostering these studies is needed to define microglia as potential therapeutic target in the frame of disorders consequent to maternal immune activation.

Maternal Immune Activation and Child Brain Development: A Longitudinal Population-based Multimodal Neuroimaging study

Maternal Immune Activation (MIA) has been hypothesized to have an adverse effect on child neurodevelopment, but only a few neuroimaging studies have been performed to date, mostly in neonates. In this population-based cohort study, we investigated the association between MIA and multiple neuroimaging modalities depicting brain development from childhood to adolescence. We used data of mother-child pairs from the Generation R Study. To define our exposure, we measured IL-1β, IL-6, IL-17a, IL-23 and IFN-γ, and CRP at two time points during pregnancy. Given that levels of these 5 cytokines were highly correlated, we were able to compute a Cytokine index. We used multiple brain imaging modalities as outcomes, encompassing global and regional measures of brain morphology (structural MRI, volume, n=3,295), white matter microstructure (diffusion MRI, FA and MD, n=3,267), and functional connectivity (functional MRI, graph theory measures and network-level connectivity, n=2,914) at child mean ages 10 and 14 years. We performed mixed-effects models using the child's age as continuous time variable. We found no significant association or time interaction between MIA and any neuroimaging outcomes in children over time. These associations were similar for the Cytokine index, CRP, and individual cytokines. We observed no evidence for differential effects of timing of prenatal MIA or child sex after multiple testing correction. This longitudinal population-based study reports no evidence for an association between MIA and child brain development in the general population. Our findings differ from prior research in neonates showing structural and functional brain abnormalities after MIA.

Sex-specific associations between maternal prenatal inflammation and offspring cortical morphology in youth: A harmonised study across four birth cohorts

Maternal immune activation (MIA) during pregnancy is implicated in offspring psychiatric disorders. However, it is unknown to what extent MIA affects neurodevelopment, particularly cerebrocortical anatomy, in the general population, and whether effects differ by sex. The current study used vertex-wise statistics to examine the association between maternal prenatal CRP, an archetypal systemic inflammatory marker, and offspring cortical thickness, surface area, and volume, in 2,635 mother–child dyads (5.4–26.5 years) from three population-based cohorts, and one clinical cohort enriched for presence of inflammation markers.Maternal CRP within a normal physiological range (<10 mg/L) exhibited sex-specific quadratic associations with cortical morphological measures in 2 regions in males and 1 region in females at childhood. Elevated (>10 mg/L) CRP was associated with regional cortical morphology in females and in a pooled sample of sexes. Overall, MIA is associated with cortical development in a regional and sex-specific manner in studies spanning childhood to adulthood.

Glia dysfunction in schizophrenia: evidence of possible therapeutic effects of nervonic acid in a preclinical model.

Neuroinflammation may inhibit oligodendrocyte and astrocyte differentiation, which causes demyelination and synaptic degeneration. The myelin component nervonic acid (NA) may improve demyelinating and neurodegenerative diseases. This study firstly explored relationships between glial cell dysfunction and demyelination or synaptic degeneration in schizophrenia patients, and secondly determined nervonic acid therapeutic effects in a preclinical schizophrenia model of mice. Plasma samples were collected from 18 male healthy controls and 18 male schizophrenic patients (diagnosed by DSM-V) at aged 18-55. Mouse brain samples were collected from a maternal immune activation (MIA) model of schizophrenia via injecting 5mg/kg polyinosinic-polycytidylic acid. Male mouse offspring (age 2.5months, n = 12) were treated by clozapine (15mg/kg/day) or fed 0.5% NA for 6weeks. Cytokine and dopamine (DA) concentrations, and glial phenotypes and myelin markers were measured in both human plasma and mouse brain samples. In patient plasma, increased proinflammatory cytokines were associated with reactive microglia (Iba-1) up-regulation, while decreased anti-inflammatory cytokines were related to microglia (CD206) downregulation. Decreased astrocyte marker (p11) concentrations were accompanied by reduced concentrations of oligodendrocyte and synaptic markers. However, NA and DA contents were increased. Compared with control mice, SZ-like behaviors appeared in MIA male mice. Changes in microglia and astrocytes markers, and cytokine concentrations in the frontal cortex were consistent with those observed in patients' plasma. Hippocampal oligodendrocyte and synaptic marker expression were also decreased. DA content and DA/metabolite (DAPOC) were increased in MIA mouse brains. Most of these changes were normalized by both clozapine and NA. Even though some NA effects were more pronounced than clozapine, only clozapine restored cytokine function. The data suggest a possible therapeutic route for schizophrenia patients.

Transient CSF1R inhibition ameliorates behavioral deficits in Cntnap2 knockout and valproic acid-exposed mouse models of autism

Microglial abnormality and heterogeneity are observed in autism spectrum disorder (ASD) patients and animal models of ASD. Microglial depletion by colony stimulating factor 1-receptor (CSF1R) inhibition has been proved to improve autism-like behaviors in maternal immune activation mouse offspring. However, it is unclear whether CSF1R inhibition has extensive effectiveness and pharmacological heterogeneity in treating autism models caused by genetic and environmental risk factors. Here, we report pharmacological functions and cellular mechanisms of PLX5622, a small-molecule CSF1R inhibitor, in treating Cntnap2 knockout and valproic acid (VPA)-exposed autism model mice. For the Cntnap2 knockout mice, PLX5622 can improve their social ability and reciprocal social behavior, slow down their hyperactivity in open field and repetitive grooming behavior, and enhance their nesting ability. For the VPA model mice, PLX5622 can enhance their social ability and social novelty, and alleviate their anxiety behavior, repetitive and stereotyped autism-like behaviors such as grooming and marble burying. At the cellular level, PLX5622 restores the morphology and/or number of microglia in the somatosensory cortex, striatum, and hippocampal CA1 regions of the two models. Specially, PLX5622 corrects neurophysiological abnormalities in the striatum of the Cntnap2 knockout mice, and in the somatosensory cortex, striatum, and hippocampal CA1 regions of the VPA model mice. Incidentally, microglial dynamic changes in the VPA model mice are also reported. Our study demonstrates that microglial depletion and repopulation by transient CSF1R inhibition is effective, and however, has differential pharmacological functions and cellular mechanisms in rescuing behavioral deficits in the two autism models.

In Utero Exposure to Maternal COVID-19 and Offspring Neurodevelopment Through Age 24 Months

In utero exposure to maternal infections has been associated with abnormal neurodevelopment among offspring. The emergence of a new, now endemic infection (SARS-CoV-2) warrants investigating developmental implications for exposed offspring. To assess whether in utero exposure to maternal COVID-19 is associated with abnormal neurodevelopmental scores among children ages 12, 18, and 24 months. Data were ascertained from the ASPIRE (Assessing the Safety of Pregnancy in the Coronavirus Pandemic) trial, a prospective cohort of pregnant individuals aged 18 years or older who were enrolled before 10 weeks' gestation and their children. Individuals were recruited online from May 14, 2020, to August 23, 2021, using the Society for Assisted Reproductive Technology and BabyCenter, an online media platform. Participants from all 50 states and Puerto Rico completed activities remotely. In utero exposure to COVID-19. Birth mothers completed the Ages & Stages Questionnaires, Third Edition, a validated screening tool for developmental delays, at 12, 18, and 24 months' post partum. A score below the cutoff in any domain (communication, gross motor, fine motor, problem-solving, and social skills) was considered an abnormal developmental screen (scores range from 0 to 60 in each domain, with higher scores indicating less risk for neurodevelopmental delay). The cohort included 2003 pregnant individuals (mean [SD] age, 33.3 [4.2] years) enrolled before 10 weeks' gestation and who completed study activities; 1750 (87.4%) had earned a college degree. Neurodevelopmental outcomes were available for 1757 children at age 12 months, 1522 at age 18 months, and 1523 at age 24 months. The prevalence of abnormal screens for exposed vs unexposed offspring at age 12 months was 64 of 198 (32.3%) vs 458 of 1559 (29.4%); at age 18 months, 36 of 161 (22.4%) vs 279 of 1361 (20.5%); and at age 24 months, 29 of 151 (19.2%) vs 230 of 1372 (16.8%). In an adjusted mixed-effects logistics regression model, no difference in risk of abnormal neurodevelopmental screens was observed at age 12 months (adjusted risk ratio [ARR], 1.07 [95% CI, 0.85-1.34]), age 18 months (ARR, 1.15 [95% CI, 0.84-1.57]), or age 24 months (ARR, 1.01 [95% CI, 0.69-1.48]). Supplemental analyses did not identify differential risk based on trimester of infection, presence vs absence of fever, or breakthrough infection following vaccination vs primary infection. In this cohort study of pregnant individuals and offspring, exposure to maternal COVID-19 was not associated with abnormal neurodevelopmental screening results through 24 months' post partum. Continued study of diverse groups of children is needed because, among other factors, evidence suggests sensitivity of the developing fetal brain to maternal immune activation.

Embryo-restricted responses to maternal IL-17A promote neurodevelopmental disorders in mouse offspring.

Prenatal imprinting to interleukin 17A (IL-17A) triggers behavioral disorders in offspring. However, reported models of maternal immune activation utilizing immunostimulants, lack specificity to elucidate the anatomical compartments of IL-17A's action and the distinct behavioral disturbances it causes. By combining transgenic IL-17A overexpression with maternal deficiency in its receptor, we established a novel model of prenatal imprinting to maternal IL-17A (acronym: PRIMA-17 model). This model allowed us to study prenatal imprinting established exclusively through embryo-restricted IL-17A responses. We demonstrated a transfer of transgenic IL-17A across the placental barrier, which triggered the development of selected behavioral deficits in mouse offspring. More specifically, embryonic responses to IL-17A resulted in communicative impairment in early-life measured by reduced numbers of nest retrieval calls. In adulthood, IL-17A-imprinted offspring displayed an increase in anxiety-like behavior. We advocate our PRIMA-17 model as a useful tool to study neurological deficits in mice.

8611 Maternal Immune Activation During Mid-Gestation Leads to Impaired Neuroendocrine Stress Response and Blood-Brain Barrier Integrity in a Sex-Dependent Manner

Abstract Disclosure: J.A. Sheng: None. S.A. Tobet: None. Background and Hypothesis: Maternal immune activation (MIA) has been associated with increased risk for neuropsychiatric diseases in the offspring. Recently, our lab demonstrated toll-like receptor 7 (TLR7) activation during impaired stress-related behaviors (anxiety-, anhedonia-, social-like) (Sheng et al., 2023, Front. Neurosci.). Stress-related behaviors are regulated by neurons in the paraventricular nucleus of the hypothalamus (PVN), an anatomic region involved in the hypothalamic-pituitary-adrenal (HPA) stress response. We hypothesize immune system activation by TLR7 during mid-gestation impairs PVN neuroendocrine stress response and brain vasculature. Methods: Timed-pregnant female mice were administered the TLR7 agonist Resiquimod (RQ) or vehicle saline on embryonic day 12.5. Adult offspring underwent 20-minute acute restraint stress with 80-minutes of recovery to examine plasma corticosterone (ELISA assay) as an indicator of HPA function. Mice were transcardially perfused with fluorescein isothiocyanate (FITC; 100mg/mL) to visualize blood vessel integrity (FITC leakage; Frahm &amp; Tobet, 2015, Brain Struct. Funct.). Sections through the PVN of offspring were also immunolabeled for Glial Fibrillary Acidic Protein (GFAP; astrocytic end feet) and IBA-1 (microglia). Only data from brains of offspring that did not undergo restraint stress are presented for baseline changes in blood-brain barrier components by MIA. Results: Plasma corticosterone was elevated in RQ-offspring (males p&amp;lt;0.0001, females p&amp;lt;0.01 vs. VEH) following stressor and recovery, suggesting delayed negative feedback to the HPA axis. Blood-brain barrier integrity diminished in RQ-adult offspring who showed greater FITC leakage in the PVN as indicated by an increase in the ratio of extravascular to intravascular FITC (males p&amp;lt;0.001, females p&amp;lt;0.01). GFAP+ coverage of FITC-labeled vessels was greater in the PVN only in RQ males compared to VEH (p&amp;lt;0.001). Microglia were examined in relation to vasculature, and data show more IBA-1+ cells in the PVN with close proximity (within 2µm) to blood vessels after maternal injection of RQ in females compared to VEH (p&amp;lt;0.05). In RQ-adult males, the average size of IBA-1+ cells in the PVN were greater than VEH counterparts (p&amp;lt;0.05), but number and proximity of IBA-1+ cells to blood vessels were unchanged. No changes in these measures were seen in control brain regions. Conclusions: This study provides support for sex-dependent influences of fetal immune antecedents on brain development and adult neuroendocrine function that could indicate a locus for increased susceptibility to adult neuropsychiatric disorders. While the current experiments found significant post-pubertal changes selectively in adult PVN, ongoing studies are examining whether these effects are evident prior to puberty. Supported by ORWH-NIMH U54 SCORE-MH118919. Presentation: 6/1/2024

Associations of inflammation related prenatal adversities with neurodevelopment of offspring in one year: a longitudinal prospective birth cohort study

BackgroundThe recent Maternal Immune Activation (MIA) theory suggests maternal systemic inflammation may serve as a mediator in associations between prenatal maternal adversities and neurodevelopmental diseases in offspring. Given the co-exposure to multiple adversities may be experienced by pregnant person, it is unclear whether a quantitative index can be developed to characterize the inflammation related exposure level, and whether this index is associated with neurodevelopmental delays in offspring.MethodsBased on Jiangsu Birth Cohort (JBC), a total of 3051 infants were included in the analysis. Inflammation related Prenatal Adversity Index (IPAI) was constructed using maternal data. Neurodevelopmental outcomes were assessed using the Bayley Scales of Infant and Toddler Development, third edition, screening test in one year. Multivariate linear regression and Poisson regression model were performed to analyze the associations between IPAI and neurodevelopment in offspring.ResultsCompared with “low IPAI” group, offspring with “high IPAI” have lower scores of cognition, receptive communication, expressive communication, and fine motor. The adjusted β were − 0.23 (95%CI: -0.42, -0.04), -0.47 (95%CI: -0.66, -0.28), -0.30 (95%CI: -0.49, -0.11), and − 0.20 (95%CI: -0.33, -0.06). Additionally, the elevated risk for noncompetent development of cognition and receptive communication among “high IPAI” group was observed. The relative risk [RR] and 95% confidence interval [CI] were 1.35 (1.01, 1.69) and 1.37 (1.09, 1.72).ConclusionsOur results revealed a significant association between higher IPAI and lower scores across cognition, receptive communication, expressive communication, and fine motor domains, and an increased risk of noncompetent development in the cognition and receptive communication domains.

Prenatal immune activation in rats and adult exposure to inescapable shocks reveal sex-dependent effects on fear conditioning that might be relevant for schizophrenia

Prenatal infection is considered a relevant factor for neurodevelopmental alterations and psychiatric diseases. Administration of bacterial and viral components during pregnancy in rodents results in maternal immune activation (MIA), leading to schizophrenia-like neurochemical and behavioral changes. Despite some evidence for abnormal fear conditioning in schizophrenia, only a few animal studies have focused on this issue. Therefore, we addressed the impact of the administration of the viral mimetic polyI:C to pregnant Long-Evans rats on the adult offspring response to inescapable shocks (IS) and contextual fear conditioning. In males, polyI:C induced a greater endocrine (plasma ACTH) response to IS and both polyI:C and IS enhanced fear conditioning and generalization to a completely different novel environment (hole-board), with no additive effects, probably due to a ceiling effect. In contrast, a modest impact of polyI:C and a lower impact of IS on contextual fear conditioning and generalization was observed in females. Thus, the present results demonstrate that polyI:C dramatically affected fear response to IS in adult males and support the hypothesis that males are more sensitive than females to this treatment. This model might allow to explore neurobiological mechanisms underlying abnormal responsiveness to fear conditioning and stressors in schizophrenia.

The association between maternal immune activation and brain structure and function in human offspring: a systematic review.

Maternal immune activation (MIA) during pregnancy, as a result of infectious or inflammatory stimuli, has gained increasing attention for its potential role in adverse child neurodevelopment, with studies focusing on associations in children born preterm. This systematic review summarizes research on the link between several types of prenatal MIA and subsequent child structural and/or functional brain development outcomes. We identified 111 neuroimaging studies in five MIA areas: inflammatory biomarkers (n = 13), chorioamnionitis (n = 18), other types of infections (n = 18), human immunodeficiency virus (HIV) (n = 42), and Zika virus (n = 20). Overall, there was large heterogeneity in the type of MIA exposure examined and in study methodology. Most studies had a prospective single cohort design and mainly focused on potential effects on the brain up to one year after birth. The median sample size was 53 participants. Severe infections, i.e., HIV and Zika virus, were associated with various types of cerebral lesions (e.g., microcephaly, atrophy, or periventricular leukomalacia) that were consistently identified across studies. For less severe infections and chronic inflammation, findings were generally inconsistent and mostly included deviations in white matter structure/function. Current findings have been mainly observed in the infants' brain, presenting an opportunity for future studies to investigate whether these associations persist throughout development. Additionally, the inconsistent findings, encompassing both regions of interest and null results, call into question whether prenatal exposure to less severe infections and chronic inflammation exerts a small effect or no effect on child brain development.

Autophagy defects at weaning impair complement-dependent synaptic pruning and induce behavior deficits

Autophagy is crucial for synaptic plasticity and the architecture of dendritic spines. However, the role of autophagy in schizophrenia (SCZ) and the mechanisms through which it affects synaptic function remain unclear. In this study, we identified 995 single nucleotide polymorphisms (SNPs) across 19 autophagy-related genes that are associated with SCZ. Gene Set Enrichment Analysis (GSEA) of data from the Gene Expression Omnibus public database revealed defective autophagy in patients with SCZ. Using a maternal immune activation (MIA) rat model, we observed that autophagy was downregulated during the weaning period, and early-life activation of autophagy with rapamycin restored abnormal behaviors and electrophysiological deficits in adult rats. Additionally, inhibition of autophagy with 3-Methyladenine (3-MA) during the weaning period resulted in aberrant behaviors, abnormal electrophysiology, increased spine density, and reduced microglia-mediated synaptic pruning. Furthermore, 3-MA treatment significantly decreased the expression and synaptosomal content of complement, impaired the recognition of C3b and CR3, indicating that autophagy deficiency disrupts complement-mediated synaptic pruning. Our findings provide evidence for a significant association between SCZ and defective autophagy, highlighting a previously underappreciated role of autophagy in regulating the synaptic and behavioral deficits induced by MIA.

Maternal immune activation alters temporal Precision of spike generation of CA1 pyramidal neurons by Unbalancing GABAergic inhibition in the Offspring

Infection during pregnancy represents a risk factor for neuropsychiatric disorders associated with neurodevelopmental alterations. A growing body of evidence from rodents and non-human primates shows that maternal inflammation induced by viral or bacterial infections results in several neurobiological alterations in the offspring. These changes may play an important role in the pathophysiology of psychiatric disorders like schizophrenia and autism spectrum disorders, whose clinical features include impairments in cognitive processing and social performance. Such alterations are causally associated with the maternal inflammatory response to infection rather than with the infection itself. Previously, we reported that CA1 pyramidal neurons of mice exposed to MIA exhibit increased excitability accompanied by a reduction in dendritic complexity. However, potential alterations in cellular and synaptic rules that shape the neuronal computational properties of the offspring remain to be determined. In this study, using mice as subjects, we identified a series of cellular and synaptic alterations endured by CA1 pyramidal neurons of the dorsal hippocampus in a lipopolysaccharide-induced maternal immune activation (MIA) model. Our data indicate that MIA reshapes the excitation-inhibition balance by decreasing the perisomatic GABAergic inhibition predominantly mediated by cholecystokinin-expressing Interneurons but not parvalbumin-expressing interneurons impinging on CA1 pyramidal neurons. These alterations yield a dysregulated amplification of the temporal and spatial synaptic integration. In addition, MIA-exposed offspring displayed social and anxiety-like abnormalities. These findings collectively contribute to understanding the cellular and synaptic alterations underlying the behavioral symptoms present in neurodevelopmental disorders associated with MIA.

A Novel Non-Invasive Murine Model of Neonatal Hypoxic-Ischemic Encephalopathy Demonstrates Developmental Delay and Motor Deficits with Activation of Inflammatory Pathways in Monocytes.

Neonatal hypoxic-ischemic encephalopathy (HIE) occurs in 1.5 per 1000 live births, leaving affected children with long-term motor and cognitive deficits. Few animal models of HIE incorporate maternal immune activation (MIA) despite the significant risk MIA poses to HIE incidence and diagnosis. Our non-invasive model of HIE pairs late gestation MIA with postnatal hypoxia. HIE pups exhibited a trend toward smaller overall brain size and delays in the ontogeny of several developmental milestones. In adulthood, HIE animals had reduced strength and gait deficits, but no difference in speed. Surprisingly, HIE animals performed better on the rotarod, an assessment of motor coordination. There was significant upregulation of inflammatory genes in microglia 24 h after hypoxia. Single-cell RNA sequencing (scRNAseq) revealed two microglia subclusters of interest following HIE. Pseudobulk analysis revealed increased microglia motility gene expression and upregulation of epigenetic machinery and neurodevelopmental genes in macrophages following HIE. No sex differences were found in any measures. These results support a two-hit noninvasive model pairing MIA and hypoxia as a model for HIE in humans. This model results in a milder phenotype compared to established HIE models; however, HIE is a clinically heterogeneous injury resulting in a variety of outcomes in humans. The pathways identified in our model of HIE may reveal novel targets for therapy for neonates with HIE.

Sex-Specific Behavioral and Molecular Responses to Maternal Lipopolysaccharide-Induced Immune Activation in a Murine Model: Implications for Neurodevelopmental Disorders.

Maternal immune activation (MIA) during pregnancy has been increasingly recognized as a critical factor in the development of neurodevelopmental disorders, with potential sex-specific impacts that are not yet fully understood. In this study, we utilized a murine model to explore the behavioral and molecular consequences of MIA induced by lipopolysaccharide (LPS) administration on embryonic day 12.5. Our findings indicate that male offspring exposed to LPS exhibited significant increases in anxiety-like and depression-like behaviors, while female offspring did not show comparable changes. Molecular analyses revealed alterations in pro-inflammatory cytokine levels and synaptic gene expression in male offspring, suggesting that these molecular disruptions may underlie the observed behavioral differences. These results emphasize the importance of considering sex as a biological variable in studies of neurodevelopmental disorders and highlight the need for further molecular investigations to understand the mechanisms driving these sex-specific outcomes. Our study contributes to the growing evidence that prenatal immune challenges play a pivotal role in the etiology of neurodevelopmental disorders and underscores the potential for sex-specific preventative approaches of MIA.

Profiling metabolome of mouse embryonic cerebrospinal fluid following maternal immune activation

The embryonic cerebrospinal fluid (eCSF) plays an essential role in the development of the central nervous system (CNS), influencing processes from neurogenesis to lifelong cognitive functions. An important process affecting eCSF composition is inflammation. Inflammation during development can be studied using the maternal immune activation (MIA) mouse model, which displays altered cytokine eCSF composition and mimics neurodevelopmental disorders including autism spectrum disorder (ASD). The limited nature of eCSF as a biosample restricts its research and has hindered our understanding of the eCSF’s role in brain pathologies. Specifically, investigation of the small molecule composition of the eCSF is lacking, leaving this aspect of the eCSF composition under-studied. We report here the eCSF metabolome as a resource for investigating developmental neuropathologies from a metabolic perspective. Our reference metabolome includes comprehensive MS1 and MS2 datasets and evaluates two mouse strains (CD-1 and C57Bl/6) and two developmental time points (E12.5 and E14.5). We illustrate the reference metabolome’s utility by using untargeted metabolomics to identify eCSF-specific compositional changes following MIA. We uncover MIA-relevant metabolic pathways as differentially abundant in eCSF and validate changes in glucocorticoid and kynurenine pathways through targeted metabolomics approaches. Our resource will guide future studies into the causes of MIA neuropathology and the impact of eCSF composition on brain development.

Effects of Maternal Immune Activation on Tryptophan Metabolism in Rat Placenta and Decidua

Effects of Maternal Immune Activation on Tryptophan Metabolism in Rat Placenta and Decidua

Maternal immune activation exerts long-term effects on activity and sleep in male offspring mice.

Exposure to infectious or non-infectious immune activation during early development is a serious risk factor for long-term behavioural dysfunctions. Mouse models of maternal immune activation (MIA) have increasingly been used to address neuronal and behavioural dysfunctions in response to prenatal infections. One commonly employed MIA model involves administering poly(I:C) (polyriboinosinic-polyribocytdilic acid), a synthetic analogue of double-stranded RNA, during gestation, which robustly induces an acute viral-like inflammatory response. Using electroencephalography (EEG) and infrared (IR) activity recordings, we explored alterations in sleep/wake, circadian and locomotor activity patterns on the adult male offspring of poly(I:C)-treated mothers. Our findings demonstrate that these offspring displayed reduced home cage activity during the (subjective) night under both light/dark or constant darkness conditions. In line with this finding, these mice exhibited an increase in non-rapid eye movement (NREM) sleep duration as well as an increase in sleep spindles density. Following sleep deprivation, poly(I:C)-exposed offspring extended NREM sleep duration and prolonged NREM sleep bouts during the dark phase as compared with non-exposed mice. Additionally, these mice exhibited a significant alteration in NREM sleep EEG spectral powerunder heightened sleep pressure. Together, our study highlights the lasting effects of infection and/or immune activation during pregnancy on circadian activity and sleep/wake patterns in the offspring.

Poly (I:C)-induced maternal immune activation generates impairment of reversal learning performance in offspring.

Maternal immune activation (MIA) induces a variety of behavioral and brain abnormalities in offspring of rodent models, compatible with neurodevelopmental disorders, such as schizophrenia or autism. However, it remains controversial whether MIA impairs reversal learning, a basic expression of cognitive flexibility that seems to be altered in schizophrenia. In the present study, MIA was induced by administration of a single dose of polyriboinosinic-polyribocytidylic acid (Poly (I:C) (5 mg/kg i.p.)) or saline to mouse pregnant dams in gestational day (GD) 9.5. Immune activation was monitored through changes in weight and temperature. The offspring were evaluated when they reached adulthood (8 weeks) using a touchscreen-based system to investigate the effects of Poly (I:C) on discrimination and reversal learning performance. After an initial pre-training, mice were trained to discriminate between two different stimuli, of which only one was rewarded (acquisition phase). When the correct response reached above 80% values for two consecutive days, the images were reversed (reversal phase) to assess the adaptation capacity to a changing environment. Maternal Poly (I:C) treatment did not interfere with the learning process but induced deficits in reversal learning compared to control saline animals. Thus, the accuracy in the reversal phase was lower, and Poly (I:C) animals required more sessions to complete it, suggesting impairments in cognitive flexibility. This study advances the knowledge of how MIA affects behavior, especially cognitive domains that are impaired in schizophrenia. The findings support the validity of the Poly (I:C)-based MIA model as a tool to develop pharmacological treatments targeting cognitive deficits associated with neurodevelopmental disorders.