Schizophrenia and viral infection during neurodevelopment: a focus on mechanisms

Inflammation and viral infection as disease modifiers in schizophrenia

Numerous studies have now implicated a role for inflammation in schizophrenia. However, many aspects surrounding this aspect of the disease are still controversial. This controversy has been driven by conflicting evidence on the role of both pro-and anti-inflammatory factors and by often contentious findings concerning cytokine and immune cell profiles in the central nervous system and periphery. Current evidence supports the point that interleukin-6 is elevated in CSF, but does not support activation of microglia, resident macrophage-like cells in the brain. Furthermore, the mechanisms involving transit of the peripheral immune system factors across the blood brain barrier to central parenchyma have still not been completely elucidated. This process appears to involve perivascular macrophages and accompanying dendritic cells retained in the parenchyma by the chemokine and cytokine composition of the surrounding milieu. In addition, a number of studies have shown that this can be modulated by infection with viruses such as herpes simplex virus type I which may disrupt antigen presentation in the perivascular space, with long-lasting consequences. In this review article, we discuss the role of inflammation and viral infection as potential disease modifiers in schizophrenia. The primary viral hit may occur in the fetus in utero, transforming the immune response regulatory T-cells or the virus may secondarily remain latent in immune cells or neurons and modify further immune responses in the developing individual. It is hoped that unraveling this pathway further and solidifying our understanding of the pathophysiological mechanisms involved will pave the way for future studies aimed at identification and implementation of new biomarkers and drug targets. This may facilitate the development of more effective personalized therapies for individuals suffering with schizophrenia.

Microglia and microbiome in schizophrenia: can immunomodulation improve symptoms?

In this overview, influences of microglia activation and disturbances of the microbiome in the devastating disorder schizophrenia are discussed. Despite previous assumptions of a primary neurodegenerative character of this disorder, current research underlines the important autoimmunological and inflammatory processes here. Early disturbances of microglial cells as well as cytokines could lead to weakness of the immunological system in the prodromal phase and then fully manifest in patients with schizophrenia. Measurements of microbiome features might allow identifying the prodromal phase. In conclusion, such thinking would imply several new therapeutic options regulating immune processes by old or new anti-inflammatory agents in patients.

Reduced sociability in a prenatal immune activation model: Modulation by a chronic blonanserin treatment through the amygdala-hippocampal axis

The environmental disturbances in a critical neurodevelopmental period exert organizational effects on brain intrinsic plasticity including excitatory and inhibitory (E/I) neurotransmission those can cause the onset of psychiatric illness. We previously reported that treatment of neural precursor cells with N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 induced reduction of GABAergic interneuron differentiation, and these changes recovered by atypical antipsychotic blonanserin treatment in vitro. However, it remains unclear how this treatment affects neural circuit changes in hippocampus and amygdala, which might contribute to the prevention of onset process of schizophrenia. To elucidate the pathogenic/preventive mechanisms underlying prenatal environmental adversity-induced schizophrenia in more detail, we administered poly (I:C) followed by antipsychotics and examined alterations in social/cognitive behaviors, GABA/glutamate-related gene expressions with cell density and E/I ratio, and brain-derived neurotrophic factor (Bdnf) transcript levels, particularly in limbic areas. Treatment with antipsychotic blonanserin ameliorated impaired social/cognitive behaviors and increased parvalbumin (PV)-positive (+) cell density and its mRNA levels as well as Bdnf with long 3'UTR mRNA levels, particularly in the dorsal hippocampus, in rats exposed to maternal immune activation (MIA). Low dose of blonanserin and haloperidol altered GABA and glutamate-related mRNA levels, the E/I ratio, and Bdnf long 3'UTR mRNA levels in the ventral hippocampus and amygdala, but did not attenuate behavioral impairments. These results strongly implicate changes in PV expression, PV(+) GABAergic interneuron density, and Bdnf long 3'UTR expression levels, particularly in the dorsal hippocampus, in the pathophysiology and treatment responses of MIA-induced schizophrenia and highlight the therapeutic potential of blonanserin for developmental stress-related schizophrenia.

Sex Differences in Neurodevelopmental Disorders: A Key Role for the Immune System

Sex differences are prominent defining features of neurodevelopmental disorders. Understanding the sex biases in these disorders can shed light on mechanisms leading to relative risk and resilience for the disorders, as well as more broadly advance our understanding of how sex differences may relate to brain development. The prevalence of neurodevelopmental disorders is increasing, and the two most common neurodevelopmental disorders, Autism Spectrum Disorder (ASD) and Attention-Deficit/Hyperactivity Disorder (ADHD) exhibit male-biases in prevalence rates and sex differences in symptomology. While the causes of neurodevelopmental disorders and their sex differences remain to be fully understood, increasing evidence suggests that the immune system plays a critical role in shaping development. In this chapter we discuss sex differences in prevalence and symptomology of ASD and ADHD, review sexual differentiation and immune regulation of neurodevelopment, and discuss findings from human and rodent studies of immune dysregulation and perinatal immune perturbation as they relate to potential mechanisms underlying neurodevelopmental disorders. This chapter will give an overview of how understanding sex differences in neuroimmune function in the context of neurodevelopmental disorders could lend insight into their etiologies and better treatment strategies.

Maternal immune activation as an epidemiological risk factor for neurodevelopmental disorders: Considerations of timing, severity, individual differences, and sex in human and rodent studies

Epidemiological evidence suggests that one's risk of being diagnosed with a neurodevelopmental disorder (NDD)-such as autism, ADHD, or schizophrenia-increases significantly if their mother had a viral or bacterial infection during the first or second trimester of pregnancy. Despite this well-known data, little is known about how developing neural systems are perturbed by events such as early-life immune activation. One theory is that the maternal immune response disrupts neural processes important for typical fetal and postnatal development, which can subsequently result in specific and overlapping behavioral phenotypes in offspring, characteristic of NDDs. As such, rodent models of maternal immune activation (MIA) have been useful in elucidating neural mechanisms that may become dysregulated by MIA. This review will start with an up-to-date and in-depth, critical summary of epidemiological data in humans, examining the association between different types of MIA and NDD outcomes in offspring. Thereafter, we will summarize common rodent models of MIA and discuss their relevance to the human epidemiological data. Finally, we will highlight other factors that may interact with or impact MIA and its associated risk for NDDs, and emphasize the importance for researchers to consider these when designing future human and rodent studies. These points to consider include: the sex of the offspring, the developmental timing of the immune challenge, and other factors that may contribute to individual variability in neural and behavioral responses to MIA, such as genetics, parental age, the gut microbiome, prenatal stress, and placental buffering.

Could CRP be a differential biomarker of illness stages in schizophrenia? A systematic review and meta-analysis

BACKGROUND

Patients with schizophrenia display peripheral inflammation but the impact of illness phase is not clear. Our meta-analysis investigated the difference in CRP levels between patients with schizophrenia and controls according to their illness phase.

METHODS

After a systematic search, all studies measuring CRP in patients with schizophrenia and controls were included. Standardized mean differences were calculated between patients and controls according to illness phase. The influence of sociodemographic and clinical variables on our results was investigated using a meta-regression analysis.

RESULTS

Fifty studies were included in this meta-analysis. Patients with schizophrenia had higher CRP levels than controls in the acute (p < 0.00001) and stable (p < 0.00001) stage of their disease. Patients with acute exacerbation of schizophrenia had higher CRP levels than stable patients (p = 0.02) but this difference did not persist when considering antipsychotic-medicated patients in both phases. Meta-regressions found that the increase of CRP in acutely ill patients as compared to controls was influenced by age (p < 0.01), BMI (p = 0.01) and first episode (p = 0.02), whereas the increase in CRP levels of stable patients as compared to controls was moderated by BMI (p = 0.004).

CONCLUSIONS

In conclusion, this meta-analysis provides strong evidence that patients with schizophrenia have higher CRP levels than controls, but also show an increase in inflammatory response in the acute stage of the disease as compared to the stable stage. CRP could thus be considered as a state marker and a trait marker of the disease.

Consequences of Viral Infection and Cytokine Production During Pregnancy on Brain Development in Offspring

Infections during pregnancy can seriously damage fetal neurodevelopment by aberrantly activating the maternal immune system, directly impacting fetal neural cells. Increasing evidence suggests that these adverse impacts involve alterations in neural stem cell biology with long-term consequences for offspring, including neurodevelopmental disorders such as autism spectrum disorder, schizophrenia, and cognitive impairment. Here we review how maternal infection with viruses such as Influenza A, Cytomegalovirus, and Zika during pregnancy can affect the brain development of offspring by promoting the release of maternal pro-inflammatory cytokines, triggering neuroinflammation of the fetal brain, and/or directly infecting fetal neural cells. In addition, we review insights into how these infections impact human brain development from studies with animal models and brain organoids. Finally, we discuss how maternal infection with SARS-CoV-2 may have consequences for neurodevelopment of the offspring.

Understanding the Role of the Gut Microbiome in Brain Development and Its Association With Neurodevelopmental Psychiatric Disorders

The gut microbiome has a tremendous influence on human physiology, including the nervous system. During fetal development, the initial colonization of the microbiome coincides with the development of the nervous system in a timely, coordinated manner. Emerging studies suggest an active involvement of the microbiome and its metabolic by-products in regulating early brain development. However, any disruption during this early developmental process can negatively impact brain functionality, leading to a range of neurodevelopment and neuropsychiatric disorders (NPD). In this review, we summarize recent evidence as to how the gut microbiome can influence the process of early human brain development and its association with major neurodevelopmental psychiatric disorders such as autism spectrum disorders, attention-deficit hyperactivity disorder, and schizophrenia. Further, we discuss how gut microbiome alterations can also play a role in inducing drug resistance in the affected individuals. We propose a model that establishes a direct link of microbiome dysbiosis with the exacerbated inflammatory state, leading to functional brain deficits associated with NPD. Based on the existing research, we discuss a framework whereby early diet intervention can boost mental wellness in the affected subjects and call for further research for a better understanding of mechanisms that govern the gut-brain axis may lead to novel approaches to the study of the pathophysiology and treatment of neuropsychiatric disorders.

Microglial A20 Protects the Brain from CD8 T-Cell-Mediated Immunopathology

Tumor-necrosis-factor-alpha-induced protein 3 (TNFAIP3), or A20, is a ubiquitin-modifying protein and negative regulator of canonical nuclear factor κB (NF-κB) signaling. Several single-nucleotide polymorphisms in TNFAIP3 are associated with autoimmune diseases, suggesting a role in tissue inflammation. While the role of A20 in peripheral immune cells has been well investigated, less is known about its role in the central nervous system (CNS). Here, we show that microglial A20 is crucial for maintaining brain homeostasis. Without microglial A20, CD8⁺ T cells spontaneously infiltrate the CNS and acquire a viral response signature. The combination of infiltrating CD8⁺ T cells and activated A20-deficient microglia leads to an increase in VGLUT1⁺ terminals and frequency of spontaneous excitatory currents. Ultimately, A20-deficient microglia upregulate genes associated with the antiviral response and neurodegenerative diseases. Together, our data suggest that microglial A20 acts as a sensor for viral infection and a master regulator of CNS homeostasis.

The Inflamed Brain in Schizophrenia: The Convergence of Genetic and Environmental Risk Factors That Lead to Uncontrolled Neuroinflammation

Schizophrenia is a disorder with a heterogeneous etiology involving complex interplay between genetic and environmental risk factors. The immune system is now known to play vital roles in nervous system function and pathology through regulating neuronal and glial development, synaptic plasticity, and behavior. In this regard, the immune system is positioned as a common link between the seemingly diverse genetic and environmental risk factors for schizophrenia. Synthesizing information about how the immune-brain axis is affected by multiple factors and how these factors might interact in schizophrenia is necessary to better understand the pathogenesis of this disease. Such knowledge will aid in the development of more translatable animal models that may lead to effective therapeutic interventions. Here, we provide an overview of the genetic risk factors for schizophrenia that modulate immune function. We also explore environmental factors for schizophrenia including exposure to pollution, gut dysbiosis, maternal immune activation and early-life stress, and how the consequences of these risk factors are linked to microglial function and dysfunction. We also propose that morphological and signaling deficits of the blood-brain barrier, as observed in some individuals with schizophrenia, can act as a gateway between peripheral and central nervous system inflammation, thus affecting microglia in their essential functions. Finally, we describe the diverse roles that microglia play in response to neuroinflammation and their impact on brain development and homeostasis, as well as schizophrenia pathophysiology.

Maternal inflammation has a profound effect on cortical interneuron development in a stage and subtype-specific manner

Severe infections during pregnancy are one of the major risk factors for cognitive impairment in the offspring. It has been suggested that maternal inflammation leads to dysfunction of cortical GABAergic interneurons that in turn underlies cognitive impairment of the affected offspring. However, the evidence comes largely from studies of adult or mature brains and how the impairment of inhibitory circuits arises upon maternal inflammation is unknown. Here we show that maternal inflammation affects multiple steps of cortical GABAergic interneuron development, i.e., proliferation of precursor cells, migration and positioning of neuroblasts, as well as neuronal maturation. Importantly, the development of distinct subtypes of cortical GABAergic interneurons was discretely impaired as a result of maternal inflammation. This translated into a reduction in cell numbers, redistribution across cortical regions and layers, and changes in morphology and cellular properties. Furthermore, selective vulnerability of GABAergic interneuron subtypes was associated with the stage of brain development. Thus, we propose that maternally derived insults have developmental stage-dependent effects, which contribute to the complex etiology of cognitive impairment in the affected offspring.

The association between antibodies to neurotropic pathogens and bipolar disorder : A study in the Dutch Bipolar (DB) Cohort and meta-analysis

Exposure to neurotropic pathogens has been hypothesized to be a risk factor for the development of bipolar disorder (BD). However, evidence so far is inconsistent. We, therefore, analyzed the seroprevalence and titer levels of IgG antibodies against several herpesviruses and Toxoplasma gondii (T. gondii) in plasma of 760 patients with a bipolar disorder, 144 first-degree matched relatives and 132 controls of the Dutch Bipolar (DB) Cohort using ELISA. In addition, we performed a literature-based meta-analysis on the seroprevalence of IgG antibodies against these pathogens (n = 14). Our results in the DB Cohort and subsequent meta-analysis (n = 2364 BD patients, n = 5101 controls) show no association between exposure to herpesviruses and bipolar disorder (HSV-1 [adjusted OR 0.842, 95% CI 0.567-1.230], HSV-2 [adjusted OR 0.877, 95% CI 0.437-1.761], CMV [adjusted OR 0.884 95% CI 0.603-1.295], EBV [adjusted OR 0.968 95% CI 0.658-1.423]). In the DB Cohort, we did not find an association between bipolar disorder and T. gondii titer or seroprevalence either [adjusted OR 1.018, 95% CI 0.672-1.542]. The overall OR was not significant for T. gondii [OR: 1.4, 95% CI 0.95-1.90, p = 0.09), but subgroup analyses in age groups below 40 years showed a significantly increased seroprevalence of T. gondii IgGs in BD [OR: 1.8 (95% CI 1.10-2.89, p = 0.021]. Our meta-analysis indicates that T. gondii exposure may be a risk factor for BD in certain subpopulations.

Preventing childhood and lifelong disability: Maternal dietary supplementation for perinatal brain injury

The majority of brain injuries that lead to cerebral palsy, developmental disability, and mental health disorders have their onset in utero. These lifelong conditions come with great economic and emotional burden as they impact function in nearly all domains of affected individuals' lives. Unfortunately, current therapeutic options are limited. There remains a focus on rescue, rehabilitation, and regeneration after the injury has occurred, rather than aiming to prevent the initial injury. Prevention would imply treating the mother during pregnancy to alter the fetal environment and in turn, treat the fetus. Fear of harming the developing fetus remains as a result of errors of the past such as the release of thalidomide. In this review, we outline evidence from animal studies and clinical trials that have explored maternal dietary supplementation with natural health products (including nutraceuticals and functional foods) for perinatal brain injury prevention. Namely, we discuss magnesium sulphate, creatine, choline, melatonin, resveratrol and broccoli sprouts/sulforaphane. Although clinical trials have only been completed in this realm for magnesium sulphate, results in animal models have been promising, suggesting that this is a productive avenue for further research. Natural health products may provide safe, effective, affordable, and easily accessible prevention of fetal brain injury and resulting lifelong disabilities.

Inflammation in Schizophrenia: Pathogenetic Aspects and Therapeutic Considerations

This paper discusses the current evidence from animal and human studies for a central role of inflammation in schizophrenia. In animal models, pre- or perinatal elicitation of the immune response may increase immune reactivity throughout life, and similar findings have been described in humans. Levels of pro-inflammatory markers, such as cytokines, have been found to be increased in the blood and cerebrospinal fluid of patients with schizophrenia. Numerous epidemiological and clinical studies have provided evidence that various infectious agents are risk factors for schizophrenia and other psychoses. For example, a large-scale epidemiological study performed in Denmark clearly showed that severe infections and autoimmune disorders are such risk factors. The vulnerability-stress-inflammation model may help to explain the role of inflammation in schizophrenia because stress can increase pro-inflammatory cytokines and may even contribute to a chronic pro-inflammatory state. Schizophrenia is characterized by risk genes that promote inflammation and by environmental stress factors and alterations of the immune system. Typical alterations of dopaminergic, serotonergic, noradrenergic, and glutamatergic neurotransmission described in schizophrenia have also been found in low-level neuroinflammation and consequently may be key factors in the generation of schizophrenia symptoms. Further support for the relevance of a low-level neuroinflammatory process in schizophrenia is provided by the loss of central nervous system volume and microglial activation demonstrated in neuroimaging studies. Last but not least, the benefit of anti-inflammatory medications found in some studies and the intrinsic anti-inflammatory and immunomodulatory effects of antipsychotics provide further support for the role of inflammation in this debilitating disease.

Olfactory deficit as a result of clozapine withdrawal syndrome in an animal model of schizophrenia: preliminary results

Clozapine is an antipsychotic that produces serious withdrawal effects in schizophrenic patients. Olfactory deficits are well known as part of negative symptoms, but it is not known whether antipsychotic use and/or withdrawal are implicated. Then, we tested clozapine withdrawal in association with two widely used schizophrenia models: Neonatal immune challenge by Polycitidilic-polyinosinic acid (polyI:C) and ketamine. PolyI:C (or saline) was injected subcutaneously in neonatal period, dose of 5 mg/kg from 2 to 6 Post Natal Days, and ketamine or saline at the dose 25mg/kg intraperitoneally (i.p.), daily for 7 days from 53 to 60 post natal day. Clozapine 10mg/kg (or saline) was administered i.p. from 46 to 60 post natal day. Olfactory discrimination test (sensorial and cognitive deficit) was performed at 61 post natal day, 24h after the last injections. The association of PolyI:C, ketamine and clozapine disrupted Olfactory Discrimination, equating time in familiar and non-familiar compartments. PolyI:C plus ketamine increased crossings between compartments. It was produced, for the first time, an olfactory deficit induced by clozapine withdrawal in Wistar rats subjected to schizophrenia animal models.

Protein-C Reactive as Biomarker Predictor of Schizophrenia Phases of Illness? A Systematic Review

BACKGROUND

Schizophrenia is a complex illness in which genetic, environmental, and epigenetic components have been implicated. However, recently, psychiatric disorders appear to be related to a chronic inflammatory state, at the level of specific cerebral areas which have been found as well impaired and responsible for schizophrenia symptomatology. Hence, a role of inflammatory mediators and cytokines has been as well defined. Accordingly, the role of an acute inflammatory phase protein, the C-reactive protein (CRP) has been recently investigated.

OBJECTIVE

The objective of the present study is to evaluate how PCR may represent a biomarker in schizophrenia, i.e. correlated with illness phases and/or clinical manifestation and/or psychopathological severity.

METHODS

A systematic review was here carried out by searching the following keywords ((C-reactive protein AND ((schizophrenia) OR (psychotic disorder))) for the topics 'PCR' and 'Schizophrenia', by using MESH terms.

RESULTS

An immune dysfunction and inflammation have been described amongst schizophrenic patients. Findings reported elevated CRP levels in schizophrenia, mainly correlated with the severity of illness and during the recrudescent phase. CRP levels are higher when catatonic features, negative symptomatology and aggressiveness are associated. CRP levels appeared not to be related to suicidal behaviour and ideation.

CONCLUSION

CRP and its blood levels have been reported higher amongst schizophrenic patients, by suggesting a role of inflammation in the pathogenesis of schizophrenia. Further studies are needed to better understand if CRP may be considered a biomarker in schizophrenia.

Immunological aspects of the treatment of depression and schizophrenia

Schizophrenia and major depression (MD) have been associated with immune system dysfunction. One example of this is the altered level of cytokines—important inflammatory mediators—in blood, and a proinflammatory immune state has been described in some subgroups of patients. A knock to the immune system in early life might trigger a life-long increased immune reactivity, and infections and autoimmune disorders are now known to be risk factors for development of schizophrenia and MD. Pro- and anti-inflammatory cytokines mediate indoleamine 2,3-dioxygenase activity; this enzyme drives metabolism of tryptophan and kynurenin in the central nervous system and degrades serotonin. Alterations of serotonergic, noradrenergic, and glutamatergic neurotransmission have been associated with low-level neuroinflammation, and anti-inflammatory compounds have a therapeutic benefit in MD and schizophrenia, as shown in meta-analyses. Moreover, antidepressants and antipsychotics have intrinsic immunomodulatory effects. With evidence pointing to the role inflammatory processes play in the pathogenesis of major psychiatric disorders, this review will look at various immunological aspects of treatment of such disorders.

Maternal immune activation during pregnancy in rats impairs working memory capacity of the offspring

Maternal immune activation during pregnancy is an environmental risk factor for psychiatric illnesses such as schizophrenia in the offspring. Patients with schizophrenia display an array of cognitive symptoms, including impaired working memory capacity. Rodent models have been developed to understand the relationship between maternal immune activation and the cognitive symptoms of schizophrenia. The present experiment was designed to test whether maternal immune activation with the viral mimetic polyinosinic:polycytidylic acid (polyI:C) during pregnancy affects working memory capacity of the offspring. Pregnant Long Evans rats were treated with either saline or polyI:C (4mg/kg; i.v.) on gestational day 15. Male offspring of the litters (2-3months of age) were subsequently trained on a nonmatching-to-sample task with odors. After a criterion was met, the rats were tested on the odor span task, which requires rats to remember an increasing span of different odors to receive food reward. Rats were tested using delays of approximately 40s during the acquisition of the task. Importantly, polyI:C- and saline-treated offspring did not differ in performance of the nonmatching-to-sample task suggesting that both groups could perform a relatively simple working memory task. In contrast, polyI:C-treated offspring had reduced span capacity in the middle and late phases of odor span task acquisition. After task acquisition, the rats were tested using the 40s delay and a 10min delay. Both groups showed a delay-dependent decrease in span, although the polyI:C-treated offspring had significantly lower spans regardless of delay. Our results support the validity of the maternal immune activation model for studying the cognitive symptoms of neurodevelopmental disorders such as schizophrenia.

Lifetime Modulation of the Pain System via Neuroimmune and Neuroendocrine Interactions

Chronic pain is a debilitating condition that still is challenging both clinicians and researchers. Despite intense research, it is still not clear why some individuals develop chronic pain while others do not or how to heal this disease. In this review, we argue for a multisystem approach to understand chronic pain. Pain is not only to be viewed simply as a result of aberrant neuronal activity but also as a result of adverse early-life experiences that impact an individual's endocrine, immune, and nervous systems and changes which in turn program the pain system. First, we give an overview of the ontogeny of the central nervous system, endocrine, and immune systems and their windows of vulnerability. Thereafter, we summarize human and animal findings from our laboratories and others that point to an important role of the endocrine and immune systems in modulating pain sensitivity. Taking "early-life history" into account, together with the past and current immunological and endocrine status of chronic pain patients, is a necessary step to understand chronic pain pathophysiology and assist clinicians in tailoring the best therapeutic approach.

Common infections with polyomaviruses and herpesviruses and neuropsychological development at 4 years of age, the Rhea birth cohort in Crete, Greece

BACKGROUND

Viral infections of the central nervous system may have detrimental effects for the developing brain, but the effects of less virulent common infections are unclear. We aim to investigate the impact of common viral infections of early childhood on neuropsychological performance of children at age four.

METHODS

We used cross-sectional data on 674 children participating at the 4 years of age follow-up of the Rhea birth cohort in Crete, Greece. Blood levels of IgG antibodies to 10 polyomaviruses (BKPyV, JCPyV, KIPyV, WUPyV, HPyV6, HPyV7, TSPyV, MCPyV, HPyV9, and HPyV10) and four herpesviruses [Epstein-Barr virus (EBV), cytomegalovirus (CMV), herpes simplex virus-1 (HSV-1), and herpes simplex virus-2 (HSV-2)] were measured using multiplex serology. Child's neuropsychological development at age four was assessed using the McCarthy Scales of Children's Abilities, the Attention-Deficit Hyperactivity Disorder Test (ADHDT), and the Strengths and Difficulties Questionnaire (SDQ). Multiple linear regression models were used to explore the associations.

RESULTS

Seroprevalence to polyomaviruses ranged from 21% for HPyV9 to 82% for HPyV10. Seroprevalence for EBV was 53%, for CMV 26%, for HSV-1 3.6%, and for HSV-2 1.5%. Children seropositive to ≥8 polyomaviruses had lower score in ADHDT inattention subscale [β = -1.28 (95% CI: -2.56, -0.001)] and lower score in SDQ hyperactivity-inattention subscale [β = -.99 (95% CI: -1.60, -0.37)] versus children seropositive to ≤3 polyomaviruses. Seropositivity to BKPyV, a potential neurotropic virus, was associated with higher score in ADHDT inattention subscale [β = .87 (95% CI: 0.03, 1.71)].

CONCLUSIONS

These findings suggest that acquisition of polyomaviruses during development may influence behavioral outcomes in early childhood.

Epigenetic Treatment of Persistent Viral Infections

Preclinical Research Approximately 2,500 years ago, Hippocrates used the word herpes as a medical term to describe lesions that appeared to creep or crawl on the skin, advocating heat as a possible treatment. During the last 50 years, pharmaceutical research has made great strides, and therapeutic options have expanded to include small molecule antiviral agents, protease inhibitors, preventive vaccines for a handful of the papillomaviruses, and even cures for hepatitis C virus infections. However, effective treatments for persistent and recurrent viral infections, particularly the highly prevalent herpesviruses, continue to represent a significant unmet medical need, affecting the majority of the world's population. Exploring the population diversity of the human microbiome and the effects its compositional variances have on the immune system, health, and disease are the subjects of intense investigational research and study. Among the collection of viruses, bacteria, fungi, and single-cell eukaryotes that comprise the human microbiome, the virome has been grossly understudied relative to the influence it exerts on human pathophysiology, much as mitochondria have until recently failed to receive the attention they deserve, given their critical biomedical importance. Fortunately, cellular epigenetic machinery offers a wealth of druggable targets for therapeutic intervention in numerous disease indications, including those outlined above. With advances in synthetic biology, engineering our body's commensal microorganisms to seek out and destroy pathogenic species is clearly on the horizon. This is especially the case given recent breakthroughs in genetic manipulation with tools such as the CRISPR/Cas (clustered regularly interspaced short palindromic repeats/CRISPR-associated) gene-editing platforms. Tying these concepts together with our previous work on the microbiome and neurodegenerative and neuropsychiatric diseases, we suggest that, because mammalian cells respond to a viral infection by triggering a cascade of antiviral innate immune responses governed substantially by the cell's mitochondria, small molecule carnitinoids represent a new class of therapeutics with potential widespread utility against many infectious insults. Drug Dev Res 78 : 24-36, 2017.   © 2016 Wiley Periodicals, Inc.

Timing of Maternal Immunization Affects Immunological and Behavioral Outcomes of Adult Offspring in Siberian Hamsters (Phodopus sungorus)

Maternal influences are an important contributing factor to offspring survival, development, and behavior. Common environmental pathogens can induce maternal immune responses and affect subsequent development of offspring. There are likely sensitive periods during pregnancy when animals are particularly vulnerable to environmental disruption. Here we characterize the effects of maternal immunization across pregnancy and postpartum on offspring physiology and behavior in Siberian hamsters (Phodopus sungorus). Hamsters were injected with the antigen keyhole limpet hemocyanin (KLH) (1) prior to pairing with a male (premating), (2) at separation (postmating), (3) at midpregnancy, or (4) after birth (lactation). Maternal food intake, body mass, and immunity were monitored throughout gestation, and litters were measured weekly for growth until adulthood when social behavior, hormone concentrations, and immune responses were determined. We found that immunizations altered maternal immunity throughout pregnancy and lactation. The effects of maternal treatment differed between male and female offspring. Aggressive behavior was enhanced in offspring of both sexes born to mothers treated postmating and thus early in pregnancy relative to other stages. In contrast, maternal treatment and maternal stage differentially affected innate immunity in males and females. Offspring cortisol, however, was unaffected by maternal treatment. Collectively, these data demonstrate that maternal immunization affects offspring physiology and behavior in a time-dependent and sex-specific manner. More broadly, these findings contribute to our understanding of the effects of maternal immune activation, whether it be from environmental exposure or immunization, on immunological and behavioral responses of offspring.

Disrupted Circadian Rhythm as a Common Player in Developmental Models of Neuropsychiatric Disorders

The environment in which individuals develop and mature is critical for their physiological and psychological outcome; in particular, the intrauterine environment has reached far more clinical relevance given its potential influence on shaping brain function and thus mental health. Gestational stress and/or maternal infection during pregnancy has been related with an increased incidence of neuropsychiatric disorders, including depression and schizophrenia. In this framework, the use of animal models has allowed a formal and deep investigation of causal determinants. Despite disruption of circadian clocks often represents a hallmark of several neuropsychiatric disorders, the relationship between disruption of brain development and the circadian system has been scarcely investigated. Nowadays, there is an increasing amount of studies suggesting a link between circadian system malfunction, early-life insults and the appearance of neuropsychiatric diseases at adulthood. Here, we briefly review evidence from clinical literature and animal models suggesting that the exposure to prenatal insults, i.e. severe gestational stress or maternal immune activation, changes the foetal hormonal milieu increasing the circulating levels of both glucocorticoids and pro-inflammatory cytokines. These two biological events have been reported to affect genes expression in experimental models and critically interfere with brain development triggering and/or exacerbating behavioural anomalies in the offspring. Herein, we highlight the importance to unravel the individual components of the body circadian system that might also be altered by prenatal insults and that may be causally associated with the disruption of neural and endocrine developmental programming.

The Antipsychotic Effects of Omega-3 Fatty Acids in Rats

BACKGROUND

In humans, omega-3 fatty acids are necessary for cell membranes, brain function and nerve transmission continuation. When animals are exposed to a new environment-or as a result of an apomorphine application that creates an agonistic effect on D1 and D2 receptors-they display behavioral reactions like rearing and stereotypy. This study aims to reveal the possible antipsychotic and oxidative effects of omega-3 fatty acids by comparing with chlorpromazine, a conventional antipsychotic drug, through evaluating the novelty-induced rearing and apomorphine-induced stereotypic behaviors, as well as malondialdehyde and glutathione levels in rats.

METHODS

Twenty-eight, adult, male, Wistar rats were used in the study. Briefly, 4 groups of rats (n = 7) were administered docosahexaenoic acid (DHA) + eicosapentaenoic acid (EPA) (300 mg/kg; DHA: 120 mg/kg + EPA: 180 mg/kg intraperitoneally [IP]), DHA + EPA (150 mg/kg; DHA: 60 mg/kg + EPA: 90 mg/kg IP), chlorpromazine (1 mg/kg, IP) and isotonic saline (1 mL/kg, IP). One hour later, apomorphine (2 mg/kg, subcutaneously) was administered to each rat. After the apomorphine administration, rats were observed for stereotypic behavior.

RESULTS

This study shows that omega-3 fatty acids, "similar to antipsychotics," reversed the psychotic like effects, increase of oxidants and decrease of antioxidants that are composed experimentally in rats.

CONCLUSIONS

The application of omega-3 fatty acids has antipsychotic effects and causes an oxidative imbalance. This study adds new evidence to the current literature regarding the possible antipsychotic effects of omega-3 fatty acids.

The role of inflammation in schizophrenia

High levels of pro-inflammatory substances such as cytokines have been described in the blood and cerebrospinal fluid of schizophrenia patients. Animal models of schizophrenia show that under certain conditions an immune disturbance during early life, such as an infection-triggered immune activation, might trigger lifelong increased immune reactivity. A large epidemiological study clearly demonstrated that severe infections and autoimmune disorders are risk factors for schizophrenia. Genetic studies have shown a strong signal for schizophrenia on chromosome 6p22.1, in a region related to the human leucocyte antigen (HLA) system and other immune functions. Another line of evidence demonstrates that chronic (dis)stress is associated with immune activation. The vulnerability-stress-inflammation model of schizophrenia includes the contribution of stress on the basis of increased genetic vulnerability for the pathogenesis of schizophrenia, because stress may increase pro-inflammatory cytokines and even contribute to a lasting pro-inflammatory state. Immune alterations influence the dopaminergic, serotonergic, noradrenergic, and glutamatergic neurotransmission. The activated immune system in turn activates the enzyme indoleamine 2,3-dioxygenase (IDO) of the tryptophan/kynurenine metabolism which influences the serotonergic and glutamatergic neurotransmission via neuroactive metabolites such as kynurenic acid. The described loss of central nervous system volume and the activation of microglia, both of which have been clearly demonstrated in neuroimaging studies of schizophrenia patients, match the assumption of a (low level) inflammatory neurotoxic process. Further support for the inflammatory hypothesis comes from the therapeutic benefit of anti-inflammatory medication. Metaanalyses have shown an advantageous effect of cyclo-oxygenase-2 inhibitors in early stages of schizophrenia. Moreover, intrinsic anti-inflammatory, and immunomodulatory effects of antipsychotic drugs are known since a long time. Anti-inflammatory effects of antipsychotics, therapeutic effects of anti-inflammtory compounds, genetic, biochemical, and immunological findings point to a major role of inflammation in schizophrenia.

Heightened fear in response to a safety cue and extinguished fear cue in a rat model of maternal immune activation

Maternal immune activation (MIA) during pregnancy is an environmental risk factor for psychiatric illnesses such as schizophrenia and autism in the offspring. Hence, changes in an array of behaviors, including behavioral flexibility, consistent with altered functioning of cortico-limbic circuits have been reported in rodent models of MIA. Surprisingly, previous studies have not examined the effect of MIA on the extinction of fear conditioning which depends on cortico-limbic circuits. Thus, we tested the effects of treating pregnant Long Evans rats with the viral mimetic polyI:C (gestational day 15; 4 mg/kg; i.v.) on fear conditioning and extinction in the male offspring using two different tasks. In the first experiment, we observed no effect of polyI:C treatment on the acquisition or extinction of a classically conditioned fear memory in a non-discriminative auditory cue paradigm. However, polyI:C-treated offspring did increase contextual freezing during the recall of fear extinction in this non-discriminative paradigm. The second experiment utilized a recently developed task to explicitly test the ability of rats to discriminate among cues signifying fear, reward, and safety; a task that requires behavioral flexibility. To our surprise, polyI:C-treated rats acquired the task in a manner similar to saline-treated rats. However, upon subsequent extinction training, they showed significantly faster extinction of the freezing response to the fear cue. In contrast, during the extinction recall test, polyI:C-treated offspring showed enhanced freezing behavior before and after presentation of the fear cue, suggesting an impairment in their ability to regulate fear behavior. These behavioral results are integrated into the literature suggesting impairments in cortico-limbic brain function in the offspring of rats treated with polyI:C during pregnancy.

The different effects of LPS and poly I:C prenatal immune challenges on the behavior, development and inflammatory responses in pregnant mice and their offspring

In recent years, in vivo animal models of prenatal infection have been developed in an attempt to recreate behavioral and neuropathological features associated to a number of neurological and neuropsychiatric disorders. However, these models are still in their emerging phase and a better understanding of how these types of infections relate to adult-onset of brain-related disorders is needed. Here, we undertook an extensive behavioral characterization of both pregnant females and their pups following late gestational exposure (from gestational days (GD) 15-17) to either lipopolysaccharide (LPS; 120μg/kg i.p.) or polyinosinic:polycytidylic acid (poly I:C; 5mg/kg i.v.). We observed that both LPS and poly I:C treatments produced anxiety-like behaviors in treated pregnant females, although to a lesser extent with LPS. LPS injections, but not poly I:C, led to reduced food intake and consequently decreased weight gain in pregnant dams. In pups, poly I:C treatments triggered a delay in growth and sensorimotor development, as evaluated by righting, geotaxis and grasping reflexes. At the cellular level, both toxins induced an initial inflammatory response while only LPS reduced the expression of brain cell markers in foetuses (GFAP and NeuN), which was no longer observable at postnatal day (PnD) 10. Higher levels of IL-2, IL-5 and IL-6 in plasma and an upregulation of the metabotropic receptor 5 (mGluR5) in foetal brains of 10-day-old offspring prenatally exposed to poly I:C was also observed. Interestingly, the increased mGluR5 expression correlated with impairments of the righting reflex. This study is the first to directly compare reflex development following LPS and poly I:C prenatal immune challenges in mice and sheds light onto the different patterns of behavior and pathology in dams and their offspring.

Immunology of schizophrenia

Increased proinflammatory markers like cytokines have been described in the blood and cerebrospinal fluid of patients suffering from schizophrenia. Animal models have shown that a hit in early life to the immune system might trigger a lifelong increased immune reactivity. Many epidemiological and clinical studies show the role of various infectious agents as risk factors for schizophrenia with overlap to other psychoses. The first large-scale epidemiological study in psychiatry from Denmark clearly demonstrates severe infections and autoimmune disorders during lifetime to be risk factors for schizophrenia. Genetic studies have shown the strongest signal for schizophrenia on chromosome 6p22.1, in a region related to the major histocompatibility complex and other immune functions. The vulnerability-stress-inflammation model is important as stress may increase proinflammatory cytokines and even contribute to a lasting proinflammatory state. The immune system itself is considered an important further piece in the puzzle, as in autoimmune disorders in general, which are always linked to three factors: genes, the environment and the immune system. Alterations of dopaminergic, serotonergic, noradrenergic and glutamatergic neurotransmission have been shown with low-level neuroinflammation and may directly be involved in the generation of schizophrenic symptoms. Loss of central nervous system volume and microglial activation has been demonstrated in schizophrenia in neuroimaging studies, which supports the assumption of a low-level neuroinflammatory process. Further support comes from the therapeutic benefit of anti-inflammatory medications in specific studies and the anti-inflammatory and immunomodulatory intrinsic effects of antipsychotics.

Antioxidants as potential therapeutics for neuropsychiatric disorders

Oxidative stress has been implicated in the pathophysiology of many neuropsychiatric disorders such as schizophrenia, bipolar disorder, major depression etc. Both genetic and non-genetic factors have been found to cause increased cellular levels of reactive oxygen species beyond the capacity of antioxidant defense mechanism in patients of psychiatric disorders. These factors trigger oxidative cellular damage to lipids, proteins and DNA, leading to abnormal neural growth and differentiation. Therefore, novel therapeutic strategies such as supplementation with antioxidants can be effective for long-term treatment management of neuropsychiatric disorders. The use of antioxidants and PUFAs as supplements in the treatment of neuropsychiatric disorders has provided some promising results. At the same time, one should be cautious with the use of antioxidants since excessive antioxidants could dangerously interfere with some of the protective functions of reactive oxygen species. The present article will give an overview of the potential strategies and outcomes of using antioxidants as therapeutics in psychiatric disorders.

Combination of neonatal PolyI:C and adolescent phencyclidine treatments is required to induce behavioral abnormalities with overexpression of GLAST in adult mice

Cumulative incidences of multiple risk factors are related to pathology of psychiatric disorders. The present study was designed to examine combinative effects of a neonatal immune challenge with adolescent abused substance treatment on the psychological behaviors and molecular expressions in the adult. C57BL/6J mice were neonatally treated, with polyriboinosinic-polyribocytidylic acid (PolyI:C: 5mg/kg) during postnatal days (PD) 2-6, then with phencyclidine (PCP: 10mg/kg) during adolescence (PD35-41). Locomotor activity was analyzed to evaluate sensitivity to PCP on PD35 and PD41. Emotional and cognitive tests were carried out on PD42-48. Neonatal PolyI:C treatment markedly enhanced sensitivity to PCP- and methamphetamine-induced hyperactivity in the adolescent. Mice treated with both neonatal PolyI:C and adolescent PCP (PolyI:C/PCP) showed social deficit and object recognition memory impairment. The expression of glutamate/aspartate transporter (GLAST) in the prefrontal cortex (PFC) was significantly increased in the (PolyI:C/PCP)-treated mice. Infusion of glutamate transporter inhibitor (DL-TBOA: 1 nmol/bilaterally) into the PFC reversed the object recognition impairment in the (PolyI:C/PCP)-treated mice. These results indicate that the combined treatment of neonatal PolyI:C with adolescent PCP leads to behavioral abnormalities, which were associated with increase of GLAST expression in the adult PFC.

DISC1: a key lead in studying cortical development and associated brain disorders

For the past decade, DISC1 has been studied as a promising lead to understand the biology underlying major mental illnesses, such as schizophrenia. Consequently, many review articles on DISC1 have been published. In this article, rather than repeating comprehensive overviews of research articles, we will introduce the utility of DISC1 in the study of cortical development in association with a wide range of developmental brain disorders. Cortical development involves cell autonomous and cell nonautonomous mechanisms as well as host responses to environmental factors, all of which involve DISC1 function. Thus, we will discuss the significance of DISC1 in forming an overall understanding of multiple mechanisms that orchestrate corticogenesis and can serve as therapeutic targets in diseases caused by abnormal cortical development.

Early childhood infections and risk of schizophrenia

The association between early childhood infections and the risk of schizophrenia is not clear, and this study aimed to investigate the association between childhood infections and the risk of schizophrenia in a population-based Australia male cohort. A population-based cohort of males born between 1980 and 1984 in Western Australia was identified using birth registry records and followed-up until December 31st, 2009 or death using linked health data available through the Western Australian Data Linkage System. The associations between hospitalized infections occurring during 0-3yr of age and risk of schizophrenia were assessed with stratified analysis and multivariate logistic regression models. Analysis was further repeated to assess the effect of hospitalized intestinal infections (gastroenteritis) and respiratory infections. It was observed that male participants with two or more hospitalizations for infections before the age of three had an 80% higher risk of schizophrenia, and these findings remained when the analysis was limited to intestinal infections and acute respiratory infections. These findings support the hypothesis that infections during early childhood may lead to the onset of schizophrenia in later life.

Explorando o componente inflamatório da esquizofrenia

A esquizofrenia é uma doença heterogênea caracterizada por um conjunto de manifestações clínicas. Um grande número de estudos ao longo dos últimos 20 anos apontou para anormalidades no sistema imune em pacientes que sofrem dessa condição. Em adição, tem sido mostrado que a psicose e a disfunção cognitiva associadas com a esquizofrenia estão ligadas a doenças autoimunes. Aqui, revisamos a evidência que sugere que um status pró-inflamatório do sistema imune induz sintomas psicopatológicos e pode estar envolvido na fisiopatologia dessa principal doença mental. Também propomos que futuros estudos pré-clínicos e clínicos deveriam levar em conta tais causas predefinidas e o status do componente inflamatório. Estratificação de pacientes e estratégias de medicina personalizadas baseadas no direcionamento ao componente inflamatório da doença poderiam ajudar na redução de sintomas e da progressão da doença. Por fim, isso poderia levar a novos conceitos na identificação de alvos moleculares em esquizofrenia e estratégias de descoberta de drogas.

Early cognitive experience prevents adult deficits in a neurodevelopmental schizophrenia model

Brain abnormalities acquired early in life may cause schizophrenia, characterized by adulthood onset of psychosis, affective flattening, and cognitive impairments. Cognitive symptoms, like impaired cognitive control, are now recognized to be important treatment targets but cognition-promoting treatments are ineffective. We hypothesized that cognitive training during the adolescent period of neuroplastic development can tune compromised neural circuits to develop in the service of adult cognition and attenuate schizophrenia-related cognitive impairments that manifest in adulthood. We report, using neonatal ventral hippocampus lesion rats (NVHL), an established neurodevelopmental model of schizophrenia, that adolescent cognitive training prevented the adult cognitive control impairment in NVHL rats. The early intervention also normalized brain function, enhancing cognition-associated synchrony of neural oscillations between the hippocampi, a measure of brain function that indexed cognitive ability. Adolescence appears to be a critical window during which prophylactic cognitive therapy may benefit people at risk of schizophrenia.

The immune system and developmental programming of brain and behavior

The brain, endocrine, and immune systems are inextricably linked. Immune molecules have a powerful impact on neuroendocrine function, including hormone-behavior interactions, during health as well as sickness. Similarly, alterations in hormones, such as during stress, can powerfully impact immune function or reactivity. These functional shifts are evolved, adaptive responses that organize changes in behavior and mobilize immune resources, but can also lead to pathology or exacerbate disease if prolonged or exaggerated. The developing brain in particular is exquisitely sensitive to both endogenous and exogenous signals, and increasing evidence suggests the immune system has a critical role in brain development and associated behavioral outcomes for the life of the individual. Indeed, there are associations between many neuropsychiatric disorders and immune dysfunction, with a distinct etiology in neurodevelopment. The goal of this review is to describe the important role of the immune system during brain development, and to discuss some of the many ways in which immune activation during early brain development can affect the later-life outcomes of neural function, immune function, mood and cognition.

Child intellectual development in relation to cytokine levels in umbilical cord blood

Although cytokines play a dual role in the developing neurologic system and in prenatal immune reactions, relations between fetal cytokine levels and child intellectual development remain unknown. The authors investigated associations between umbilical cord serum cytokine concentrations and intellectual outcomes in 369 children within a prospective cohort study, the Eunice Kennedy Shriver National Institute of Child Health and Human Development-University of Alabama Infant Growth Study (1985-1988). Concentrations of interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), and interleukins 4, 10, and 12p70 were determined. The Wechsler Preschool and Primary Scale of Intelligence-Revised was administered at age 5 years, producing verbal and performance intelligence quotients (VIQ and PIQ); associations with each cytokine were evaluated using linear and logistic regression. Log-unit increases in IFN-γ (adjusted odds ratio (aOR) = 0.67, 95% confidence interval (CI): 0.46, 0.98) and interleukin-12p70 (aOR = 0.43, 95% CI: 0.21, 0.87) were inversely associated with low PIQ (score <70). One log-unit increase in TNF-α was associated with a reduced odds ratio for low VIQ (score <70) among preterm children (aOR = 0.11, 95% CI: 0.01, 0.94) and an elevated odds ratio for low VIQ among small-for-gestational-age children (aOR = 3.96, 95% CI: 0.99, 15.9). IFN-γ, which is involved in neurogenesis and perinatal adaptive immunity, may be related to fetal neurologic development overall, while TNF-α may be a marker of intellectual development in vulnerable subgroups.

IL-28B genetic variant is associated with the risk of schizophrenia in the Chinese Han population

Schizophrenia is a severe psychiatric disorder. Although its exact cause is unknown, it is widely accepted that environmental factors and genes integrate in the pathogenesis of schizophrenia. 19q13, which contains IL-28B, is a newly identified potential susceptibility locus. IL-28B is a cytokine that functionally has anti-viral activity, but, structurally, is related to the interleukin-10 family. Both virus infection and cytokine changes have been documented in schizophrenia. We selected the single-nucleotide polymorphism rs8099917, which is associated with IL-28B gene expression, to study its relationship to the susceptibility to schizophrenia. A total of 256 Chinese patients with schizophrenia and 329 healthy controls were studied. Both genotype and allele frequencies showed significant differences between patients and normal subjects (p=0.03 and p=0.04, respectively). Our study suggested that the frequency of allele T was a risk factor for the susceptibility of schizophrenia (odds ratio [OR]=1.76, 95% confidence interval [CI]=1.03-3.03). When all subjects were grouped by symptoms, both the genotype and the allele frequency were associated with patients having disorganized speech (genotype: χ(2)=5.75, p=0.02; allele: χ(2)=5.41, p=0.02, OR=3.67, 95% CI=1.14-11.82) and negative symptoms (genotype: χ(2)=5.09, p=0.02; allele: χ(2)=4.80, p=0.03, OR=1.95, 95% CI=1.06-3.56) as well as cognitive symptoms (genotype: χ(2)=5.97, p=0.02; allele: χ(2)=5.53, p=0.02, OR=2.04, 95% CI=1.11-3.74). The results in this study may lead to a better understanding of the etiology of schizophrenia.

Animal models of prenatal immune challenge and their contribution to the study of schizophrenia: a systematic review

Prenatal immune challenge (PIC) in pregnant rodents produces offspring with abnormalities in behavior, histology, and gene expression that are reminiscent of schizophrenia and autism. Based on this, the goal of this article was to review the main contributions of PIC models, especially the one using the viral-mimetic particle polyriboinosinic-polyribocytidylic acid (poly-I:C), to the understanding of the etiology, biological basis and treatment of schizophrenia. This systematic review consisted of a search of available web databases (PubMed, SciELO, LILACS, PsycINFO, and ISI Web of Knowledge) for original studies published in the last 10 years (May 2001 to October 2011) concerning animal models of PIC, focusing on those using poly-I:C. The results showed that the PIC model with poly-I:C is able to mimic the prodrome and both the positive and negative/cognitive dimensions of schizophrenia, depending on the specific gestation time window of the immune challenge. The model resembles the neurobiology and etiology of schizophrenia and has good predictive value. In conclusion, this model is a robust tool for the identification of novel molecular targets during prenatal life, adolescence and adulthood that might contribute to the development of preventive and/or treatment strategies (targeting specific symptoms, i.e., positive or negative/cognitive) for this devastating mental disorder, also presenting biosafety as compared to viral infection models. One limitation of this model is the incapacity to model the full spectrum of immune responses normally induced by viral exposure.

Structural abnormalities in the cuneus associated with Herpes Simplex Virus (type 1) infection in people at ultra high risk of developing psychosis

It has been suggested that some cases of schizophrenia may be caused by an interaction between physiological risk factors and exposure to certain neurotropic infectious agents such as Herpes Simplex Virus type 1 (HSV1). This study investigated whether HSV1 exposure was associated with structural brain abnormalities in individuals who, because of genetic or other factors, were deemed at ultra high risk (UHR) of developing psychosis. Twenty-five UHR individuals with a history of HSV1 exposure (HSV1+), 33 UHR participants without a history of HSV1 exposure (HSV1-) and 19 healthy controls participated in the study. All participants underwent a T1-weighted structural MRI scan, and HSV1 exposure was determined based on the presence of IgG class antibodies in the blood serum. Voxel based morphometry revealed that the HSV1+ participants exhibited volumetric gray matter reductions in the cuneus, relative to both the HSV1--and healthy control participants (p<0.05, small volume corrected for familywise error). The results of the study suggest that a history of HSV1 infection is associated with volumetric gray matter reductions in individuals at ultra-high risk for developing psychosis, and are consistent with previous studies that have identified structural gray matter abnormalities in HSV1-infected patients with established schizophrenia.

Altered object-in-place recognition memory, prepulse inhibition, and locomotor activity in the offspring of rats exposed to a viral mimetic during pregnancy

Infection during pregnancy (i.e., prenatal infection) increases the risk of psychiatric illnesses such as schizophrenia and autism in the adult offspring. The present experiments examined the effects of prenatal immune challenge on behavior in three paradigms relevant to these disorders: prepulse inhibition (PPI) of the acoustic startle response, locomotor responses to an unfamiliar environment and the N-methyl-d-aspartate antagonist MK-801, and three forms of recognition memory. Pregnant Long-Evans rats were exposed to the viral mimetic polyinosinic-polycytidylic acid (PolyI:C; 4 mg/kg, i.v.) on gestational day 15. Offspring were tested for PPI and locomotor activity before puberty (postnatal days (PNDs)35 and 36) and during young adulthood (PNDs 56 and 57). Four prepulse-pulse intervals (30, 50, 80, and 140 ms) were employed in the PPI test. Recognition memory testing was performed using three different spontaneous novelty recognition tests (object, object location, and object-in-place recognition) after PND 60. Regardless of sex, offspring of PolyI:C-treated dams showed disrupted PPI at 50-, 80-, and 140-ms prepulse-pulse intervals. In the prepubescent rats, we observed prepulse facilitation for the 30-ms prepulse-pulse interval trials that was selectively retained in the adult PolyI:C-treated offspring. Locomotor responses to MK-801 were significantly reduced before puberty, whereas responses to an unfamiliar environment were increased in young adulthood. Both male and female PolyI:C-treated offspring showed intact object and object location recognition memory, whereas male PolyI:C-treated offspring displayed significantly impaired object-in-place recognition memory. Females were unable to perform the object-in-place test. The present results demonstrate that prenatal immune challenge during mid/late gestation disrupts PPI and locomotor behavior. In addition, the selective impairment of object-in-place recognition memory suggests tasks that depend on prefrontal cortex may be particularly vulnerable following prenatal immune challenge.

Study of HLA Class I gene in Indian schizophrenic patients of Siliguri, West Bengal

The authors studied the prevalence of the human leukocyte antigen (HLA) Class I gene in 136 (85 male, 51 female) India-born schizophrenia patients residing in and around the Siliguri subdivision of West Bengal by the PCR-SSP method. The control group consisted of 150 age- and sex-matched healthy individuals from the same ethnic group as the patients. Increased frequency of HLA A*03 as well as decreased frequencies of HLA A*31 and HLA B*51, was noted. The study suggests the possible existence of a susceptibility locus for schizophrenia within the HLA region.

Tracing the development of psychosis and its prevention: what can be learned from animal models

Schizophrenia (SCZ) is a neurodevelopmental disorder manifested symptomatically after puberty whose pharmacotherapy remains unsatisfactory. In recent years, longitudinal structural neuroimaging studies have revealed that neuroanatomical aberrations occur in this disorder and in fact precede symptom onset, raising the exciting possibility that SCZ can be prevented. There is some evidence that treatment with atypical antipsychotic drugs (APDs) prior to the development of the full clinical phenotype reduces the risk of transition to psychosis, but results remain controversial. It remains unknown whether progressive structural brain aberrations can be halted. Given the diagnostic, ethical, clinical and methodological problems of pharmacological and imaging studies in patients, getting such information remains a major challenge. Animal neurodevelopmental models of SCZ are invaluable for investigating such questions because they capture the notion that the effects of early brain damage are progressive. In recent years, data derived from such models have converged on key neuropathological and behavioral deficits documented in SCZ attesting to their strong validity, and making them ideal tools for evaluating progression of pathology following in-utero insults as well as its prevention. We review here our recent studies that use longitudinal in vivo structural imaging to achieve this aim in the prenatal immune stimulation model that is based on the association of prenatal infection and increased risk for SCZ. Pregnant rats were injected on gestational day 15 with the viral mimic polyriboinosinic-polyribocytidylic acid (poly I:C) or saline. Male and female offspring were imaged and tested behaviorally on postnatal days (PNDs) 35, 46, 56, 70 and 90. In other experiments, offspring of poly I:C- and saline-treated dams received the atypical antipsychotic drugs (APDs) clozapine or risperidone in two developmental windows: PND 34-47 and PND 48-61, and underwent behavioral testing and imaging at adulthood. Prenatal poly I:C-induced interference with fetal brain development led to aberrant postnatal brain development as manifested in structural abnormalities in the hippocampus, the striatum, the prefrontal cortex and lateral ventricles (LV), as seen in SCZ. The specific trajectories were region-, age- and sex-specific, with females having delayed onset of pathology compared to males. Brain pathology was accompanied by development of behavioral abnormalities phenotypic of SCZ, attentional deficit and hypersensitivity to amphetamine, with same sex difference. Hippocampal volume loss and LV volume expansion as well as behavioral abnormalities were prevented in the offspring of poly I:C mothers who received clozapine or risperidone during the asymptomatic period of adolescence (PND 34-47). Administration at a later window, PNDs 48-61, exerted sex-, region- and drug- specific effects. Our data show that prenatal insult leads to progressive postnatal brain pathology, which gradually gives rise to "symptoms"; that treatment with atypical APDs can prevent both brain and behavioral pathology; and that the earlier the intervention, the more pathological outcomes can be prevented.

Antibodies to infectious agents and the positive symptom dimension of subclinical psychosis: The TRAILS study

Infections have been suggested to play a role in the etiology of schizophrenia, but the evidence for this has been inconsistent. Schizophrenia patients have an increased risk of infections as a result of hospitalizations or life style factors. Therefore a study on early subclinical manifestations of psychosis in relation to virus infections is warranted. We examined whether serum antibodies against human Herpes viruses and Toxoplasma gondii were associated with subclinical symptoms of psychosis in adolescents. Data were collected as part of the TRacking Adolescents' Individual Lives Survey (TRAILS) cohort, a large prospective cohort of Dutch adolescents. A total of 1176 participants with an available Community Assessment of Psychic Experiences (CAPE) and an available blood sample were included in this analysis. Solid-enzyme immunoassay methods were used to measure the presence of immunoglobulin G (IgG) antibodies in serum to the Herpes virus family and to T. gondii. There was no significant association between serologic evidence of infection with human Herpes viruses or T. gondii and the risk of subclinical positive experience of psychosis. Subjects with a positive serological reaction to Epstein-Barr Virus (EBV) had higher scores on the positive dimension of psychosis measured by CAPE (b=0.03, P=0.02). This significant association was observed in males, but not in females. The current study suggests that there is no significant association between serological evidence of infection to human Herpes viruses and positive subclinical experience of psychosis, whereas there was an association between EBV infection and subclinical psychotic symptoms in boys.

Maternal influenza viral infection causes schizophrenia-like alterations of 5-HT₂A and mGlu₂ receptors in the adult offspring

Epidemiological studies indicate that maternal influenza viral infection increases the risk for schizophrenia in the adult offspring. The serotonin and glutamate systems are suspected in the etiology of schizophrenia, as well as in the mechanism of action of antipsychotic drugs. The effects of hallucinogens, such as psilocybin and mescaline, require the serotonin 5-HT(2A) receptor, and induce schizophrenia-like psychosis in humans. In addition, metabotropic glutamate receptor mGlu(2/3) agonists show promise as a new treatment for schizophrenia. Here, we investigated the level of expression and behavioral function of 5-HT(2A) and mGlu(2) receptors in a mouse model of maternal influenza viral infection. We show that spontaneous locomotor activity is diminished by maternal infection with the mouse-adapted influenza A/WSN/33 (H1N1) virus. The behavioral responses to hallucinogens and glutamate antipsychotics are both affected by maternal exposure to influenza virus, with increased head-twitch response to hallucinogens and diminished antipsychotic-like effect of the glutamate agonist. In frontal cortex of mice born to influenza virus-infected mothers, the 5-HT(2A) receptor is upregulated and the mGlu(2) receptor is downregulated, an alteration that may be involved in the behavioral changes observed. Additionally, we find that the cortical 5-HT(2A) receptor-dependent signaling pathways are significantly altered in the offspring of infected mothers, showing higher c-fos, egr-1, and egr-2 expression in response to the hallucinogenic drug DOI. Identifying a biochemical alteration that parallels the behavioral changes observed in a mouse model of prenatal viral infection may facilitate targeting therapies for treatment and prevention of schizophrenia.

Prenatal exposure to a viral mimetic alters behavioural flexibility in male, but not female, rats

Current understanding of the etiology of neurodevelopmental disorders is limited; however, recent epidemiological studies demonstrate a strong correlation between prenatal infection during pregnancy and the development of schizophrenia in adult offspring. In particular, schizophrenia patients subjected to prenatal infection exhibit impairments in executive functions greater than schizophrenia patients not exposed to an infection while in utero. Acute prenatal treatment of rodents with the viral mimetic polyinosinic-polycytidylic acid (PolyI:C) induces behavioural and neuropathological alterations in the adult offspring similar to schizophrenia. However, impairments on tasks of executive function that involve the prefrontal cortex (PFC) have been rarely examined for the prenatal infection model. Hence, we investigated the effects of acute prenatal injection of PolyI:C (4.0 mg/kg, i.v., gestational day 15) on strategy set-shifting and reversal learning in an operant-based task. Our results show male, but not female, PolyI:C-treated adult offspring require more trials to reach criterion and perseverate during set-shifting. An opposite pattern was seen on the reversal day where the PolyI:C-treated male rats made fewer regressive errors. Females took more pre-training days and were slower to respond during the trials when compared to males regardless of prenatal treatment. The present findings validate the utility of the prenatal infection model for examining alterations of executive function, one of the most prominent cognitive symptoms of schizophrenia.

Viral infection and neural stem/progenitor cell's fate: implications in brain development and neurological disorders

Viral infections in the prenatal (during pregnancy) and perinatal period have been a common cause of brain malformation. Besides the immediate neurological dysfunctions, virus infections may critically affect CNS development culminating in long-term cognitive deficits. Most of these neurotropic viruses are most damaging at a critical stage of the host, when the brain is in a dynamic stage of development. The neuropathology can be attributed to the massive neuronal loss induced by the virus as well as lack of CNS repair owing to a deficit in the neural stem/progenitor cell (NSPC) pool or aberrant formation of new neurons from NSPCs. Being one of the mitotically active populations in the post natal brain, the NSPCs have emerged as the potential targets of neurotropic viruses. The NSPCs are self-renewing and multipotent cells residing in the neurogenic niches of the brain, and, therefore, hampering the developmental fate of these cells may adversely affect the overall neurogenesis pattern. A number of neurotropic viruses utilize NSPCs as their cellular reservoirs and often establish latent and persistent infection in them. Both HIV and Herpes virus infect NSPCs over long periods of time and reactivation of the virus may occur later in life. The virus infected NSPCs either undergoes cell cycle arrest or impaired neuronal or glial differentiation, all of which leads to impaired neurogenesis. The disturbances in neurogenesis and CNS development following neurotropic virus infections have direct implications in the viral pathogenesis and long-term neurobehavioral outcome in infected individuals.

Prenatal interaction of mutant DISC1 and immune activation produces adult psychopathology

BACKGROUND

Gene-environment interactions (GEI) are involved in the pathogenesis of mental diseases. We evaluated interaction between mutant human disrupted-in-schizophrenia 1 (mhDISC1) and maternal immune activation implicated in schizophrenia and mood disorders.

METHODS

Pregnant mice were treated with saline or polyinosinic:polycytidylic acid at gestation day 9. Levels of inflammatory cytokines were measured in fetal and adult brains; expression of mhDISC1, endogenous DISC1, lissencephaly type 1, nuclear distribution protein nudE-like 1, glycoprotein 130, growth factor receptor-bound protein 2, and glycogen synthase kinase-3beta were assessed in cortical samples of newborn mice. Tissue content of monoamines, volumetric brain abnormalities, dendritic spine density in the hippocampus, and various domains of the mouse behavior repertoire were evaluated in adult male mice.

RESULTS

Prenatal interaction produced anxiety, depression-like responses, and altered social behavior that were accompanied by decreased reactivity of the hypothalamic-pituitary-adrenal axis, attenuated serotonin neurotransmission in the hippocampus, reduced enlargement of lateral ventricles, decreased volumes of amygdala and periaqueductal gray matter and density of spines on dendrites of granule cells of the hippocampus. Prenatal interaction modulated secretion of inflammatory cytokines in fetal brains, levels of mhDISC1, endogenous mouse DISC1, and glycogen synthase kinase-3beta. The behavioral effects of GEI were observed only if mhDISC1 was expressed throughout the life span.

CONCLUSIONS

Prenatal immune activation interacted with mhDISC1 to produce the neurobehavioral phenotypes that were not seen in untreated mhDISC1 mice and that resemble aspects of major mental illnesses. Our DISC1 mouse model is a valuable system to study GEI relevant to mental illnesses.