Administration of molecular hydrogen during pregnancy improves behavioral abnormalities of offspring in a maternal immune activation model

Interleukin-17A stimulation induces alterations in Microglial microRNA expression profiles

BACKGROUND

Increased maternal interleukin (IL)-17A and activated microglia are pivotal factors contributing to the pathological phenotypes of maternal immune activation (MIA), developing neurodevelopmental disorders in offspring. This study aimed to determine whether IL-17A affects the microglial microRNA (miRNA) profiles.

METHODS

The miRNA expression profiles of primary cultured microglia stimulated with recombinant IL-17A were examined comprehensively using miRNA sequencing and validated through qRT-PCR. The expressions of miRNAs target genes identified using bioinformatics, were investigated in microglia transfected with mimic miRNA. The target gene's expression was also examined in the fetal brains of the MIA mouse model induced by maternal lipopolysaccharide (LPS) administration.

RESULTS

Primary cultured microglia expressed the IL-17A receptor and increased proinflammatory cytokines and nitric oxide synthase 2 upon treatment with IL-17A. Among the three miRNAs with |log2FC | >1, only mmu-miR-206-3p expression was significantly up-regulated by IL-17A. Transfection with the mmu-miR-206-3p mimic resulted in a significant decrease in the expression of Hdac4 and Igf1, target genes of mmu-miR-206-3p. Hdac4 expression also significantly decreased in the LPS-induced MIA model.

CONCLUSIONS

IL-17A affected microglial miRNA profiles with upregulated mmu-miR-206-3p. These findings suggest that targeting the IL-17A/mmu-miR-206-3p pathway may be a new strategy for predicting MIA-related neurodevelopmental deficits and providing preventive interventions.

IMPACT

Despite the growing evidence of interleukin (IL)-17A and microglia in the pathology of maternal immune activation (MIA), the downstream of IL-17A in microglia is not fully known. IL-17A altered microRNA profiles and upregulated the mmu-miR-206-3p expression in microglia. The mmu-miR-206-3p reduced autism spectrum disorder (ASD) related gene expressions, Hdac4 and Igf1. The Hdac4 expression was also reduced in the brain of MIA offspring. The hsa-miR-206 sequence is consistent with that of mmu-miR-206-3p. This study may provide clues to pathological mechanisms leading to predictions and interventions for ASD children born to mothers with IL-17A-related disorders.

Molecular hydrogen has a positive impact on pregnancy maintenance through enhancement of mitochondrial function and immunomodulatory effects on T cells

AIMS

Molecular hydrogen (H₂) has attracted growing interest because of its implications in various diseases. However, the molecular mechanisms underlying the remarkable effect of a small amount of H₂ remain elusive. No knowledge has been available on the role of H₂ in the etiology of pregnancy disorders or its direct influence on human immune cells. Since maternal immunity, T cells in particular, plays a critical role in pregnancy maintenance. We investigated the effects of H₂ on T cells and its relation to preterm birth (PTB).

MAIN METHODS

Exhaled H₂ concentrations in pregnant women were measured and correlated with cytokine concentrations in maternal and umbilical cord blood. H₂ was added to T cells collected from healthy donors, and differentiation and proliferation were examined. Energy metabolism was also examined. H₂ was administered to mice and cytokine expression was compared.

KEY FINDINGS

Our prospective observational study revealed that maternal production of H₂ is significantly lower in pregnant women with PTB, suggesting its potential as a biomarker for predicting PTB. We found that H₂ has clear associations with several maternal cytokines, and acts as an immunomodulator by exerting mitochondrial function in human T cells. Moreover, in vivo administration of H₂ to pregnant mice regulated inflammatory responses and reduced PTB caused by T cell activation, which further supports the notion that H₂ may contribute to prolonged gestation through its immunomodulatory effect.

SIGNIFICANCE

Measuring maternal H₂-production could be a potential clinical tool in the management of PTB, and H₂ may have positive impact on pregnancy maintenance.

Impact of Maternal Immune Activation on Nonhuman Primate Prefrontal Cortex Development: Insights for Schizophrenia

Late adolescence is a period of dynamic change in the brain as humans learn to navigate increasingly complex environments. In particular, prefrontal cortical (PFC) regions undergo extensive remodeling as the brain is fine-tuned to orchestrate cognitive control over attention, reasoning, and emotions. Late adolescence also presents a uniquely vulnerable period as neurodevelopmental illnesses, such as schizophrenia, become evident and worsen into young adulthood. Challenges in early development, including prenatal exposure to infection, may set the stage for a cascade of maladaptive events that ultimately result in aberrant PFC connectivity and function before symptoms emerge. A growing body of research suggests that activation of the mother's immune system during pregnancy may act as a disease primer, in combination with other environmental and genetic factors, contributing to an increased risk of neurodevelopmental disorders, including schizophrenia. Animal models provide an invaluable opportunity to examine the course of brain and behavioral changes in offspring exposed to maternal immune activation (MIA). Although the vast majority of MIA research has been carried out in rodents, here we highlight the translational utility of the nonhuman primate (NHP) as a model species more closely related to humans in PFC structure and function. In this review, we consider the protracted period of brain and behavioral maturation in the NHP, describe emerging findings from MIA NHP offspring in the context of rodent preclinical models, and lastly explore the translational relevance of the NHP MIA model to expand understanding of the etiology and developmental course of PFC pathology in schizophrenia.

Ex vivo 1H-MRS brain metabolic profiling in a two-hit model of neurodevelopmental disorders: Prenatal immune activation and peripubertal stress

Prenatal infections are environmental risk factors for neurodevelopmental disorders. In addition, traumatic experiences during adolescence in individuals exposed to infections during gestation could increase the risk of schizophrenia. It is of the most crucial importance to discover potential markers of the disease in its early stages or before its onset, so that therapeutic strategies may be implemented. In the present study, we combined a proposed two-hit model of schizophrenia-related symptoms with proton magnetic resonance spectroscopy (¹H-MRS) to discover potential biomarkers. To this end, we i.p. injected 100 μg/kg/ml of lipopolysaccharide (LPS) or saline on gestational days 15 and 16 to pregnant rats. Their male offspring were then subjected to five episodes of stress or handling on alternate days during postnatal days (PND) 28-38. Once the animals reached adulthood (PND70), we evaluated prepulse inhibition (PPI). At PND90, we performed an ex vivo ¹H-MRS study in the cortex and striatum. While we did not detect alterations in PPI at the age tested, we found neurochemical disturbances induced by LPS, stress or (more interestingly) their interaction. LPS decreased glucose levels in the cortex and striatum and altered glutamate, glutamine and N-acetylaspartate levels. Glutamate and glutamine levels in the left (but not right) striatum were differentially affected by prenatal LPS exposure in a manner that depended on stress experiences. These results suggest that alterations in the glutamate cycle in the striatum could be used as early markers of developmental disorders.

Ratiometric Detection of Hypochlorous Acid in Brain Tissues of Neuroinflammation and Maternal Immune Activation Models with a Deep-Red/Near-Infrared Emitting Probe

Reactive oxygen species (ROS) produced by an inflammatory response in the brain are associated with various neurological disorders. To investigate ROS-associated neuroinflammatory diseases, fluorescent probes with practicality are in demand. We have investigated hypochlorous acid, an important ROS, in the brain tissues of neuroinflammation and maternal immune activation (MIA) model mice, using a new fluorescent probe. The probe has outstanding features over many known probes, such as providing two bright ratio signals in cells and tissues in deep-red/near-infrared wavelength regions with a large spectral separation, in addition to being strongly fluorescent, photo- and chemo-stable, highly selective and sensitive, fast responding, and biocompatible. We have found that the level of hypochlorous acid in the brain tissue of a neuroinflammatory mouse model was higher (2.7-4.0-fold) compared with that in normal brain tissue. Furthermore, the level of hypochlorous acid in the brain tissue of a MIA mouse model was higher (1.2-1.3-fold) compared with that in the normal brain tissue. The "robust" probe provides a practical tool for studying ROS-associated neurological disorders.

Prenatal Molecular Hydrogen Administration Ameliorates Several Findings in Nitrofen-Induced Congenital Diaphragmatic Hernia

Oxidative stress plays a pathological role in pulmonary hypoplasia and pulmonary hypertension in congenital diaphragmatic hernia (CDH). This study investigated the effect of molecular hydrogen (H₂), an antioxidant, on CDH pathology induced by nitrofen. Sprague-Dawley rats were divided into three groups: control, CDH, and CDH + hydrogen-rich water (HW). Pregnant dams of CDH + HW pups were orally administered HW from embryonic day 10 until parturition. Gasometric evaluation and histological, immunohistochemical, and real-time polymerase chain reaction analyses were performed. Gasometric results (pH, pO_2, and pCO₂ levels) were better in the CDH + HW group than in the CDH group. The CDH + HW group showed amelioration of alveolarization and pulmonary artery remodeling compared with the CDH group. Oxidative stress (8-hydroxy-2′-deoxyguanosine-positive-cell score) in the pulmonary arteries and mRNA levels of protein-containing pulmonary surfactant that protects against pulmonary collapse (surfactant protein A) were significantly attenuated in the CDH + HW group compared with the CDH group. Overall, prenatal H₂ administration improved respiratory function by attenuating lung morphology and pulmonary artery thickening in CDH rat models. Thus, H₂ administration in pregnant women with diagnosed fetal CDH might be a novel antenatal intervention strategy to reduce newborn mortality due to CDH.

Multiple cytokine analysis in gastroschisis: Association with adverse outcomes including fetal brain damage

OBJECTIVES

To investigate the distribution of multiple cytokines in gastroschisis and reveal its association with clinical outcomes, including gastrointestinal disorders and fetal brain damage caused by chronic inflammation in gastroschisis.

METHODS

We obtained amniotic fluid and arterial cord blood from 10 patients with gastroschisis, and evaluated the profile of 40 cytokines via multiplex immunoassay. The possible relationship of the cytokines with the time taken to attain full enteral nutrition and cord S100B, a surrogate marker of brain damage, was estimated. Associations among the relevant cytokines were also assessed.

RESULTS

Although clinical characteristics in our cohort had no relevance, several cytokines in cord blood, especially IL-2, IL-8, CCL1, CCL7, CXCL1, CXCL2, and CXCL6, were clearly elevated in patients who took a longer time to attain full enteral nutrition, whereas only IL-16 in cord blood was significantly related to cord S100B and strongly correlation with cord S100B levels. Moreover, our data indicated that IL-16 was considerably less correlated with the other cytokines associated with adverse outcomes.

CONCLUSIONS

We investigated the cytokine characteristics of both amniotic fluid and cord blood in gastroschisis, and found that certain cytokines could affect the adverse outcomes, including fetal brain damage. These findings provide important information that could further clarify the pathophysiology of gastroschisis and propose a novel clinical implication of gastroschisis that could be used to predict adverse outcomes, especially neurodevelopmental disorders.

A standardized social preference protocol for measuring social deficits in mouse models of autism

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by social communication deficits and other behavioral abnormalities. The three-chamber social preference test is often used to assess social deficits in mouse models of ASD. However, varying and often contradicting phenotypic descriptions of ASD mouse models can be found in the scientific literature, and the substantial variability in the methods used by researchers to assess social deficits in mice could be a contributing factor. Here we describe a standardized three-chamber social preference protocol, which is sensitive and reliable at detecting social preference deficits in several mouse models of ASD. This protocol comprises three phases that can all be completed within 1 d. The test mouse is first habituated to the apparatus containing two empty cups in the side chambers, followed by the pre-test phase in which the mouse can interact with two identical inanimate objects placed in the cups. During the test phase, the mouse is allowed to interact with a social stimulus (an unfamiliar wild-type (WT) mouse) contained in one cup and a novel non-social stimulus contained in the other cup. The protocol is thus designed to assess preference between social and non-social stimuli under conditions of equal salience. The broad implementation of the three-chamber social preference protocol presented here should improve the accuracy and consistency of assessments for social preference deficits associated with ASD and other psychiatric disorders.

Hydrogen: A Novel Option in Human Disease Treatment

H₂ has shown anti-inflammatory and antioxidant ability in many clinical trials, and its application is recommended in the latest Chinese novel coronavirus pneumonia (NCP) treatment guidelines. Clinical experiments have revealed the surprising finding that H₂ gas may protect the lungs and extrapulmonary organs from pathological stimuli in NCP patients. The potential mechanisms underlying the action of H₂ gas are not clear. H₂ gas may regulate the anti-inflammatory and antioxidant activity, mitochondrial energy metabolism, endoplasmic reticulum stress, the immune system, and cell death (apoptosis, autophagy, pyroptosis, ferroptosis, and circadian clock, among others) and has therapeutic potential for many systemic diseases. This paper reviews the basic research and the latest clinical applications of H₂ gas in multiorgan system diseases to establish strategies for the clinical treatment for various diseases.

Maternal Immune Activation by Poly I:C as a preclinical Model for Neurodevelopmental Disorders: A focus on Autism and Schizophrenia

Maternal immune activation (MIA) in response to a viral infection during early and mid-gestation has been linked through various epidemiological studies to a higher risk for the child to develop autism or schizophrenia-related symptoms.. This has led to the establishment of the pathogen-free poly I:C-induced MIA animal model for neurodevelopmental disorders, which shows relatively high construct and face validity. Depending on the experimental variables, particularly the timing of poly I:C administration, different behavioural and molecular phenotypes have been described that relate to specific symptoms of neurodevelopmental disorders such as autism spectrum disorder and/or schizophrenia. We here review and summarize epidemiological evidence for the effects of maternal infection and immune activation, as well as major findings in different poly I:C MIA models with a focus on poly I:C exposure timing, behavioural and molecular changes in the offspring, and characteristics of the model that relate it to autism spectrum disorder and schizophrenia.

Hydrogen gas protects against delayed encephalopathy after acute carbon monoxide poisoning in a rat model

Objective: The protective effects of 2%-4% hydrogen gas in delayed encephalopathy after acute carbon monoxide poisoning (DEACMP) have been previously reported. This study aimed to assess the neuroprotective effects of high concentration hydrogen (HCH) on DEACMP.Methods: A total of 36 male Sprague-Dawley rats were divided into 3 groups. In the DEACMP group, rats were exposed to CO to induce CO poisoning; in the HCH group, the animals were exposed to 67% H₂ and 33% O₂ at 3,000 mL/min for 90 min immediately after CO poisoning. Neurological function was evaluated at 1 and 9 days after poisoning. Then, the contents of malondialdehyde, 3-nitrotyrosine and 8-hydroxy-2-deoxyguanosine, as well as superoxide dismutase activity in the serum, cortex and hippocampus were detected by ELISA. Additionally, the mRNA and protein expression levels of Nrf2 and downstream genes were detected by RT-PCR and Western blotting, respectively.Results: Our results showed that CO poisoning significantly impaired neurological function which was improved over time, and HCH markedly attenuated neurological impairment following CO poisoning. In addition, CO poisoning resulted in increased levels of malondialdehyde, 3-nitrotyrosine and 8-hydroxy-2-deoxyguanosine and markedly reduced superoxide dismutase activity at 1 and 9 days, which were significantly inhibited by HCH at 9 days. Finally, CO poisoning increased the mRNA and protein levels of Nrf2 and downstream genes, and HCH further induced the anti-oxidative capability.Conclusion: These findings indicate the neuroprotective effects of HCH on DEACMP, which are related to the activation of Nrf2 signaling pathway.

Influence of poly(I:C) variability on thermoregulation, immune responses and pregnancy outcomes in mouse models of maternal immune activation

Maternal immune activation (MIA) models that are based on administration of the viral mimetic, poly(I:C), are widely used as experimental tools to study neuronal and behavioral dysfunctions in relation to immune-mediated neurodevelopmental disorders and mental illnesses. Evidence from investigations in non-pregnant rodents suggests that different poly(I:C) products can vary in terms of their immunogenicity, even if they are obtained from the same vendor. The present study aimed at extending these findings to pregnant mice, while also controlling various poly(I:C) products for potential contamination with lipopolysaccharide (LPS). We found significant variability between different batches of poly(I:C) potassium salt obtained from the same vendor (Sigma-Aldrich) in terms of the relative amount of dsRNA fragments in the high molecular weight range (1000-6000 nucleotides long) and with regards to their effects on maternal thermoregulation and immune responses in maternal plasma, placenta and fetal brain. Batches of poly(I:C) potassium salt containing larger amounts of high molecular weight fragments induced more extensive effects on thermoregulation and immune responses compared to batches with minimal amounts of high molecular weight fragments. Consistent with these findings, poly(I:C) enriched for high molecular weight dsRNA (HMW) caused larger maternal and placental immune responses compared to low molecular weight (LMW) poly(I:C). These variable effects were unrelated to possible LPS contamination. Finally, we found marked variability between different batches of the poly(I:C) potassium salt in terms of their effects on spontaneous abortion rates. This batch-to-batch variability was confirmed by three independent research groups using distinct poly(I:C) administration protocols in mice. Taken together, the present data confirm that different poly(I:C) products can induce varying immune responses and can differentially affect maternal physiology and pregnancy outcomes. It is therefore pivotal that researchers working with poly(I:C)-based MIA models ascertain and consider the precise molecular composition and immunogenicity of the product in use. We recommend the establishment of reference databases that combine phenotype data with empirically acquired quality information, which can aid the design, implementation and interpretation of poly(I:C)-based MIA models.

Brain changes in a maternal immune activation model of neurodevelopmental brain disorders

The developing brain is sensitive to a variety of insults. Epidemiological studies have identified prenatal exposure to infection as a risk factor for a range of neurological disorders, including autism spectrum disorder and schizophrenia. Animal models corroborate this association and have been used to probe the contribution of gene-environment interactions to the etiology of neurodevelopmental disorders. Here we review the behavior and brain phenotypes that have been characterized in MIA offspring, including the studies that have looked at the interaction between maternal immune activation and genetic risk factors for autism spectrum disorder or schizophrenia. These phenotypes include behaviors relevant to autism, schizophrenia, and other neurological disorders, alterations in brain anatomy, and structural and functional neuronal impairments. The link between maternal infection and these phenotypic changes is not fully understood, but there is increasing evidence that maternal immune activation induces prolonged immune alterations in the offspring's brain which could underlie epigenetic alterations which in turn may mediate the behavior and brain changes. These concepts will be discussed followed by a summary of the pharmacological interventions that have been tested in the maternal immune activation model.