Maternal host responses to poly(I:C) during pregnancy leads to both dysfunctional immune profiles and altered behaviour in the offspring.

Autism spectrum disorder (ASD)-like phenotypes in murine models are linked to elevated pro-inflammatory cytokine profiles caused by maternal immune activation (MIA), but whether MIA alters the immune response in the offspring remains unclear. Polyinosinic:polycytidylic acid (poly:[IC]) was used to induce MIA in immunocompetent and control TLR3-deficient pregnant mice, and cytokine levels were measured in maternal and foetal organs. Furthermore, cytokines and behaviour responses were tested after challenge with lipopolysaccharide in 7-day-old and adult mice. MIA induced on E12 resulted in changes in the cytokine expression profile in maternal and foetal organs and correlated with TNFα and IL-18 dysregulation in immune organs and brains from neonatal mice born to MIA-induced dams. Such changes further correlated with altered behavioural responses in adulthood. MIA induced by pathogens during pregnancy can interfere with the development of the foetal immune and nervous systems leading to dysfunctional immune responses and behaviour in offspring.

Garcia-Valtanen P ，van Diermen BA ，Lakhan N ，Lousberg EL ，Robertson SA ，Hayball JD ，Diener KR ... -  《-》

P2X7 Receptors Drive Poly(I:C) Induced Autism-like Behavior in Mice.

Maternal immune activation (MIA) is a principal environmental risk factor contributing to autism spectrum disorder (ASD), which compromises fetal brain development at critical periods of pregnancy and might be causally linked to ASD symptoms. We report that endogenous activation of the purinergic ion channel P2X7 (P2rx7) is necessary and sufficient to transduce MIA to autistic phenotype in male offspring. MIA induced by poly(I:C) injections to P2rx7 WT mouse dams elicited an autism-like phenotype in their offspring, and these alterations were not observed in P2rx7-deficient mice, or following maternal treatment with a specific P2rx7 antagonist, JNJ47965567. Genetic deletion and pharmacological inhibition of maternal P2rx7s also counteracted the induction of IL-6 in the maternal plasma and fetal brain, and disrupted brain development, whereas postnatal P2rx7 inhibition alleviated behavioral and morphological alterations in the offspring. Administration of ATP to P2rx7 WT dams also evoked autistic phenotype, but not in KO dams, implying that P2rx7 activation by ATP is sufficient to induce autism-like features in offspring. Our results point to maternal and offspring P2rx7s as potential therapeutic targets for the early prevention and treatment of ASD.SIGNIFICANCE STATEMENT Autism spectrum disorder (ASD) is a neurodevelopmental psychiatric disorder caused by genetic and environmental factors. Recent studies highlighted the importance of perinatal risks, in particular, maternal immune activation (MIA), showing strong association with the later emergence of ASD in the affected children. MIA could be mimicked in animal models via injection of a nonpathogenic agent poly(I:C) during pregnancy. This is the first report showing the key role of a ligand gated ion channel, the purinergic P2X7 receptor in MIA-induced autism-like behavioral and biochemical features. We show that genetic or pharmacological inhibition of both maternal and offspring P2X7 receptors could reverse the compromised brain development and autistic phenotype pointing to new possibilities for prevention and treatment of ASD.

Horváth G ，Otrokocsi L ，Beko K ，Baranyi M ，Kittel Á ，Fritz-Ruenes PA ，Sperlágh B ... -  《-》

Impact of maternal immune activation and sex on placental and fetal brain cytokine and gene expression profiles in a preclinical model of neurodevelopmental disorders.

Maternal inflammation during gestation is associated with a later diagnosis of neurodevelopmental disorders including autism spectrum disorder (ASD). However, the specific impact of maternal immune activation (MIA) on placental and fetal brain development remains insufficiently understood. This study aimed to investigate the effects of MIA by analyzing placental and brain tissues obtained from the offspring of pregnant C57BL/6 dams exposed to polyinosinic: polycytidylic acid (poly I: C) on embryonic day 12.5. Cytokine and mRNA content in the placenta and brain tissues were assessed using multiplex cytokine assays and bulk-RNA sequencing on embryonic day 17.5. In the placenta, male MIA offspring exhibited higher levels of GM-CSF, IL-6, TNFα, and LT-α, but there were no differences in female MIA offspring. Furthermore, differentially expressed genes (DEG) in the placental tissues of MIA offspring were found to be enriched in processes related to synaptic vesicles and neuronal development. Placental mRNA from male and female MIA offspring were both enriched in synaptic and neuronal development terms, whereas females were also enriched for terms related to excitatory and inhibitory signaling. In the fetal brain of MIA offspring, increased levels of IL-28B and IL-25 were observed with male MIA offspring and increased levels of LT-α were observed in the female offspring. Notably, we identified few stable MIA fetal brain DEG, with no male specific difference whereas females had DEG related to immune cytokine signaling. Overall, these findings support the hypothesis that MIA contributes to the sex- specific abnormalities observed in ASD, possibly through altered neuron developed from exposure to inflammatory cytokines. Future research should aim to investigate how interactions between the placenta and fetal brain contribute to altered neuronal development in the context of MIA.

Osman HC ，Moreno R ，Rose D ，Rowland ME ，Ciernia AV ，Ashwood P ... -  《Journal of Neuroinflammation》

Long-term altered immune responses following fetal priming in a non-human primate model of maternal immune activation.

Infection during pregnancy can lead to activation of the maternal immune system and has been associated with an increased risk of having an offspring later diagnosed with a neurodevelopmental disorders (NDD) such as autism spectrum disorder (ASD) or schizophrenia (SZ). Most maternal immune activation (MIA) studies to date have been in rodents and usually involve the use of lipopolysaccharide (LPS) or polyinosinic:polycytidylic acid (poly I:C). However, since NDD are based on behavioral changes, a model of MIA in non-human primates could potentially provide data that helps illuminate complex behavioral and immune outputs in human NDD. In this study twenty-one pregnant rhesus macaques were either given three injections over 72 hours of poly I:C-LC, a double stranded RNA analog (viral mimic), or saline as a control. Injections were given near the end of the first trimester or near the end of the second trimester to determine if there were differences in immune output due to the timing of MIA.An additional three non-treated animals were used as controls. The offspring were followed until 4 years of age, with blood collected at the end of their first (year 1) and fourth (year 4) years to assess dynamic cellular immune function. Induced responses from peripheral immune cells were measured using multiplex assays.At one year of age, MIA exposed offspring displayed elevated production of innate inflammatory cytokines including: interleukin (IL)-1β, IL-6, IL-12p40, and tumor necrosis factor (TNF)α at baseline and following stimulation. At four years of age, the MIA exposed offspring continued to display elevated IL-1β, and there was also a pattern of an increased production of T-cell helper type (TH)-2 cytokines, IL-4 and IL-13. Throughout this time period, the offspring of MIA treated dams exhibited altered behavioral phenotypes including increased stereotyped behaviors. During the first two years, stereotyped behaviors were associated with innate cytokine production. Self-directed behaviors were associated with TH2 cytokine production at year 4. Data from this study suggests long-term behavioral and immune activation was present in offspring following MIA. This novel non-human primate model of MIA may provide a relevant clinically translational model to help further elucidate the role between immune dysfunction and complex behavioral outputs following MIA.

Rose DR ，Careaga M ，Van de Water J ，McAllister K ，Bauman MD ，Ashwood P ... -  《-》

The risk for behavioural deficits is determined by the maternal immune response to prenatal immune challenge in a neurodevelopmental model.

Schizophrenia is a highly disabling psychiatric disorder with a proposed neurodevelopmental basis. One mechanism through which genetic and environmental risk factors might act is by triggering persistent brain inflammation, as evidenced by long-lasting neuro-immunological disturbances in patients. Our goal was to investigate whether microglia activation is a neurobiological correlate to the altered behaviour in the maternal immune activation (MIA) model, a well-validated animal model with relevance to schizophrenia. A recent observation in the MIA model is the differential maternal body weight response to the immune stimulus, correlated with a different behavioural outcome in the offspring. Although it is generally assumed that the differences in maternal weight response reflect differences in cytokine response, this has not been investigated so far. Our aim was to investigate whether (i) the maternal weight response to MIA reflects differences in the maternal cytokine response, (ii) the differential behavioural phenotype of the offspring extends to depressive symptoms such as anhedonia and (iii) there are changes in chronic microglia activation dependent on the behavioural phenotype. Based on a dose-response study, MIA was induced in pregnant rats by injecting 4mg/kg Poly I:C at gestational day 15. Serum samples were collected to assess the amount of TNF-α in the maternal blood following MIA. MIA offspring were divided into weight loss (WL; n=14) and weight gain (WG; n=10) groups, depending on the maternal body weight response to Poly I:C. Adult offspring were behaviourally phenotyped for prepulse inhibition, locomotor activity with and without amphetamine and MK-801 challenge, and sucrose preference. Finally, microglia activation was scored on CD11b- and Iba1-immunohistochemically stained sections. Pregnant dams that lost weight following MIA showed increased levels of TNF-α compared to controls, unlike dams that gained weight following MIA. Poly I:C WL offspring showed the most severe behavioural outcome. Poly I:C WG offspring, on the other hand, did not show clear behavioural deficits. Most interestingly a reduced sucrose preference indicative of anhedonia was found in Poly I:C WL but not Poly I:C WG offspring compared to controls. Finally, there were no significant differences in microglia activation scores between any of the investigated groups. The individual maternal immune response to MIA is an important determinant of the behavioural outcome in offspring, including negative symptoms such as anhedonia. We failed to find any significant difference in the level of microglia activation between Poly I:C WL, Poly I:C WG and control offspring.

Missault S ，Van den Eynde K ，Vanden Berghe W ，Fransen E ，Weeren A ，Timmermans JP ，Kumar-Singh S ，Dedeurwaerdere S ... -  《-》