The fetal origins of mental illness

[Immunopsychiatry and SARS-CoV-2 pandemic: Links and possible consequences]

OBJECTIVE

The SARS-CoV-2 (or COVID-19) pandemic has been propagating since December 2019, inducing a drastic increase in the prevalence of anxious and depressive disorders in the general population. Psychological trauma can partly explain these disorders. However, since psychiatric disorders also have an immuno-inflammatory component, the direct effects of the virus on the host's immune system, with a marked inflammatory response, but also the secondary inflammation to these psychosocial stressors, may cause the apparition or the worsening of psychiatric disorders. We describe here the probable immunopsychiatric consequences of the SARS-CoV-2 pandemic, to delineate possible screening actions and care that could be planned.

METHOD

Data from previous pandemics, and existing data on the psychopathological consequences of the SARS-CoV-2 pandemic, allowed us to review the possible immunopsychiatric consequences of the SARS-CoV-2 pandemic, on the gestational environment, with the risk of consecutive neurodevelopmental disorders for the fetus on one hand, on the children and adults directly infected being at increased risks of psychiatric disorders on the other hand.

RESULTS

As in previous pandemics, the activation of the immune system due to psychological stress and/or to infection during pregnancy, might lead to an increased risk of neurodevelopmental disorders for the fetus (schizophrenia and autism spectrum disorders). Furthermore, in individuals exposed to psychological trauma and/or infected by the virus, the risk of psychiatric disorders, especially mood disorders, is probably increased.

CONCLUSION

In this context, preventive measures and specialized care are necessary. Thus, it is important to propose a close follow-up to the individuals who have been infected by the virus, in order to set up the earliest care possible. Likewise, in pregnant women, screening of mood disorders during the pregnancy or the postpartum period must be facilitated. The follow-up of the babies born during the pandemic must be strengthened to screen and care for possible neurodevelopmental disorders.

Does the human placenta express the canonical cell entry mediators for SARS-CoV-2?

The pandemic of coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has affected more than 10 million people, including pregnant women. To date, no consistent evidence for the vertical transmission of SARS-CoV-2 exists. The novel coronavirus canonically utilizes the angiotensin-converting enzyme 2 (ACE2) receptor and the serine protease TMPRSS2 for cell entry. Herein, building upon our previous single-cell study (Pique-Regi et al., 2019), another study, and new single-cell/nuclei RNA-sequencing data, we investigated the expression of ACE2 and TMPRSS2 throughout pregnancy in the placenta as well as in third-trimester chorioamniotic membranes. We report that co-transcription of ACE2 and TMPRSS2 is negligible in the placenta, thus not a likely path of vertical transmission for SARS-CoV-2. By contrast, receptors for Zika virus and cytomegalovirus, which cause congenital infections, are highly expressed by placental cell types. These data show that the placenta minimally expresses the canonical cell-entry mediators for SARS-CoV-2.

Maternal Immune Activation Sensitizes Male Offspring Rats to Lipopolysaccharide-Induced Microglial Deficits Involving the Dysfunction of CD200-CD200R and CX3CL1-CX3CR1 Systems

Early life challenges resulting from maternal immune activation (MIA) may exert persistent effects on the offspring, including the development of psychiatric disorders, such as schizophrenia. Recent evidence has suggested that the adverse effects of MIA may be mediated by neuron-microglia crosstalk, particularly CX3CL1-CX3CR1 and CD200-CD200R dyads. Therefore, the present study assessed the behavioural parameters resembling schizophrenia-like symptoms in the adult male offspring of Sprague-Dawley rats that were exposed to MIA and to an additional acute lipopolysaccharide (LPS) challenge in adulthood, according to the "two-hit" hypothesis of schizophrenia. Simultaneously, we aimed to clarify the role of the CX3CL1-CX3CR1 and CD200-CD200R axes and microglial reactivity in the brains of adult offspring subjected to MIA and the "second hit" wit LPS. In the present study, MIA generated a range of behavioural changes in the adult male offspring, including increased exploratory activity and anxiety-like behaviours. The most intriguing finding was observed in the prepulse inhibition (PPI) test, where the deficit in the sensorimotor gating was age-dependent and present only in part of the rats. We were able to distinguish the occurrence of two groups: responsive and non-responsive (without the deficit). Concurrently, based on the results of the biochemical studies, MIA disrupted mainly the CD200-CD200R system, while the changes of the CX3CL1-CX3CR1 axis were less evident in the frontal cortex of adult non-responsive offspring. MIA markedly affected the immune regulators of the CD200-CD200R pathway as we observed an increase in cortical IL-6 release in the responsive group and IL-4 in the non-responsive offspring. Importantly, the "second hit" generated disturbances at the behavioural and biochemical levels mostly in the non-responsive adult animals. Those offspring were characterized both by disturbed PPI and "priming" microglia. Altogether, the exposure to MIA altered the immunomodulatory mechanisms, including the CD200-CD200R axis, in the brain and sensitized animals to subsequent immunological challenges, leading to the manifestation of schizophrenia-like alterations.

Contributions of maternal and fetal antiviral immunity in congenital disease

Viral infections during pregnancy can have devastating consequences on pregnancy outcomes, fetal development, and maternal health. In this review, we examine fetal and maternal immune defense mechanisms that mediate resistance against viral infections and discuss the range of syndromes that ensue when such mechanisms fail, from fetal developmental defects to establishment of chronic infection. Further, we highlight the role of maternal immune activation, or uncontrolled inflammation triggered by viral infections during pregnancy, and its potential downstream pathological effects, including tissue damage and fetal demise. Insights into the respective contributions of direct viral toxicity versus fetal and maternal immune responses that underlie the pathogenesis of congenital disease will guide future treatment strategies.

The effect of intrauterine inflammation on mTOR signaling in mouse fetal brain

Fetuses exposed to an inflammatory environment are predisposed to long-term adverse neurological outcomes. However, the mechanism by which intrauterine inflammation (IUI) is responsible for abnormal fetal brain development is not fully understood. The mechanistic target of rapamycin (mTOR) signaling pathway is closely associated with fetal brain development. We hypothesized that mTOR signaling might be involved in fetal brain injury and malformation when fetuses are exposed to the IUI environment. A well-established IUI model was utilized by intrauterine injection of lipopolysaccharide (LPS) to explore the effect of IUI on mTOR signaling in mouse fetal brains. We found that microglia activation in LPS fetal brains was increased, as demonstrated by elevated Iba-1 protein level and immunofluorescence density. LPS fetal brains also showed reduced neuronal cell counts, decreased cell proliferation demonstrated by low Ki67-positive density, and elevated neuron apoptosis evidenced by high expression of cleaved Caspase 3. Furthermore, we found that mTOR signaling in LPS fetal brains was elevated at 2 hr after LPS treatment, declined at 6 hr and showed overall inhibition at 24 hr. In summary, our study revealed that LPS-induced IUI leads to increased activation of microglia cells, neuronal damage, and dynamic alterations in mTOR signaling in the mouse fetal brain. Our findings indicate that abnormal changes in mTOR signaling may underlie the development of future neurological complications in offspring exposed to prenatal IUI.

COVID-19 in Patients with Solid Organ Transplantation: A Systematic Review

The novel coronavirus, SARS-CoV-2, is causing a pandemic of unknown precedent, with huge healthcare challenges and worldwide disruptions to economic and social life. Lung transplant recipients and other solid organ transplant (SOT) recipients are immunosuppressed, and therefore are generally considered at an increased risk for severe infections. Given the current gap in knowledge and evidence regarding the best management of these patients, we conducted a systematic review of studies on SARS-CoV-2 infections and Coronavirus Disease 2019 (COVID-19) in SOT recipients, to evaluate the association between immunosuppression in these patients, SARS-CoV-2 infection and COVID-19 outcomes. The focus was the severity of the disease, the need for mechanical ventilation and intensive care unit (ICU) admissions, and rate of death. The literature search was conducted repeatedly between 16 March and 8 April 2020. We searched original papers, observational studies, case reports, and meta-analyses published between 2019 and 2020 using two databases (PubMed, Google Scholar) with the search terms: [transplant OR immunosuppression] AND [COVID-19 OR SARS-CoV-2]. Further inclusion criteria were publications in English, French, German and Italian, and reference to humans. We also searched the reference lists of the studies encountered. From an initial search of PubMed and Google Scholar, 19 potential articles were retrieved, of which 14 were excluded after full-text screening (not being case reports or case series), leaving 5 studies for inclusion. No further studies were identified from the bibliographies of retrieved articles. Based on the limited research, no firm conclusions can be made concerning SOT recipients, but the current evidence suggests that immunosuppression is most likely associated with a better outcome of SARS-CoV-2 infection and COVID-19 because it prevents hyperinflammation (cytokine storm) in this particular population. There is a need for further research that would allow results to be adjusted for other factors potentially impacting COVID-19 severity and outcome.

Prenatal and perinatal risk and protective factors for psychosis: a systematic review and meta-analysis

BACKGROUND

Prenatal and perinatal insults are implicated in the aetiopathogenesis of psychotic disorders but the consistency and magnitude of their associations with psychosis have not been updated for nearly two decades. The aim of this systematic review and meta-analysis was to provide a comprehensive and up-to-date synthesis of the evidence on the association between prenatal or perinatal risk and protective factors and psychotic disorders.

METHODS

In this systematic review and meta-analysis, we searched the Web of Science database for articles published up to July 20, 2019. We identified cohort and case-control studies examining the association (odds ratio [OR]) between prenatal and perinatal factors and any International Classification of Diseases (ICD) or Diagnostic and Statistical Manual of Mental Disorders (DSM) non-organic psychotic disorder with a healthy comparison group. Other inclusion criteria were enough data available to do the analyses, and non-overlapping datasets. We excluded reviews, meta-analyses, abstracts or conference proceedings, and articles with overlapping datasets. Data were extracted according to EQUATOR and PRISMA guidelines. Extracted variables included first author, publication year, study type, sample size, type of psychotic diagnosis (non-affective psychoses or schizophrenia-spectrum disorders, affective psychoses) and diagnostic instrument (DSM or ICD and version), the risk or protective factor, and measure of association (primary outcome). We did random-effects pairwise meta-analyses, Q statistics, I² index, sensitivity analyses, meta-regressions, and assessed study quality and publication bias. The study protocol was registered at PROSPERO, CRD42017079261.

FINDINGS

152 studies relating to 98 risk or protective factors were eligible for analysis. Significant risk factors were: maternal age younger than 20 years (OR 1·17) and 30-34 years (OR 1·05); paternal age younger than 20 years (OR 1·31) and older than 35 years (OR 1·28); any maternal (OR 4·60) or paternal (OR 2·73) psychopathology; maternal psychosis (OR 7·61) and affective disorder (OR 2·26); three or more pregnancies (OR 1·30); herpes simplex 2 (OR 1·35); maternal infections not otherwise specified (NOS; OR 1·27); suboptimal number of antenatal visits (OR 1·83); winter (OR 1·05) and winter to spring (OR 1·05) season of birth in the northern hemisphere; maternal stress NOS (OR 2·40); famine (OR 1·61); any famine or nutritional deficits in pregnancy (OR 1·40); maternal hypertension (OR 1·40); hypoxia (OR 1·63); ruptured (OR 1·86) and premature rupture (OR 2·29) of membranes; polyhydramnios (OR 3·05); definite obstetric complications NOS (OR 1·83); birthweights of less than 2000 g (OR 1·84), less than 2500 g (OR 1·53), or 2500-2999 g (OR 1·23); birth length less than 49 cm (OR 1·17); small for gestational age (OR 1·40); premature birth (OR 1·35), and congenital malformations (OR 2·35). Significant protective factors were maternal ages 20-24 years (OR 0·93) and 25-29 years (OR 0·92), nulliparity (OR 0·91), and birthweights 3500-3999 g (OR 0·90) or more than 4000 g (OR 0·86). The results were corrected for publication biases; sensitivity and meta-regression analyses confirmed the robustness of these findings for most factors.

INTERPRETATION

Several prenatal and perinatal factors are associated with the later onset of psychosis. The updated knowledge emerging from this study could refine understanding of psychosis pathogenesis, enhance multivariable risk prediction, and inform preventive strategies.

FUNDING

None.

Schizophrenia and Influenza at the Centenary of the 1918-1919 Spanish Influenza Pandemic: Mechanisms of Psychosis Risk

Associations between influenza infection and psychosis have been reported since the eighteenth century, with acute "psychoses of influenza" documented during multiple pandemics. In the late 20th century, reports of a season-of-birth effect in schizophrenia were supported by large-scale ecological and sero-epidemiological studies suggesting that maternal influenza infection increases the risk of psychosis in offspring. We examine the evidence for the association between influenza infection and schizophrenia risk, before reviewing possible mechanisms via which this risk may be conferred. Maternal immune activation models implicate placental dysfunction, disruption of cytokine networks, and subsequent microglial activation as potentially important pathogenic processes. More recent neuroimmunological advances focusing on neuronal autoimmunity following infection provide the basis for a model of infection-induced psychosis, potentially implicating autoimmunity to schizophrenia-relevant protein targets including the N-methyl-D-aspartate receptor. Finally, we outline areas for future research and relevant experimental approaches and consider whether the current evidence provides a basis for the rational development of strategies to prevent schizophrenia.

Hsp90 and complex birth defects: A plausible mechanism for the interaction of genes and environment

How genes and environment interact to cause birth defects is not well understood, but key to developing new strategies to modify risk. The threshold model has been proposed to represent this complex interaction. This model stipulates that while environmental exposure or genetic mutation alone may not result in a defect, factors in combination increase phenotypic variability resulting in more individuals crossing the disease threshold where birth defects manifest. Many environmental factors that contribute to birth defects induce widespread cellular stress and misfolding of proteins. Yet, the impact of the stress response on the threshold model is not typically considered in discephering the etiology of birth defects. This mini-review will explore a potential mechanism for gene-environment interactions co-opted from studies of evolution. This model stipulates that heat shock proteins that mediate the stress response induced by environmental factors can influence the number of individuals that cross disease thresholds resulting in increased incidence of birth defects. Studies in the field of evolutionary biology have demonstrated that heat shock proteins and Hsp90 in particular provide a link between environmental stress, genotype and phenotype. Hsp90 is a highly expressed molecular chaperone that assists a wide variety of protein clients with folding and conformational changes needed for proper function. Hsp90 also chaperones client proteins with potentially deleterious amino acid changes to suppress variation caused by genetic mutations. However, upon exposure to stress, Hsp90 abandons its normal physiological clients and is diverted to assist with the misfolded protein response. This can impact the activity of signaling pathways that involve Hsp90 clients as well as unmask suppressed protein variation, essentially creating complex traits in a single step. In this capacity Hsp90 acts as an evolutionary capacitor allowing stored variation to accumulate and then become expressed in times of stress. This mechanism provides a substrate which natural selection can act upon at the population level allowing survival of the species with selective pressure. However, at the level of the individual, this mechanism can result in simultaneous expression of deleterious variants as well as reduced activity of a variety of Hsp90 chaperoned pathways, potentially shifting phenotypic variability over the disease threshold resulting in birth defects.

Understanding the role of sleep and its disturbances in Autism spectrum disorder

BACKGROUND

Several studies have established a positive relationship between sleep difficulties and symptomatology in ASD children. The rationale for this review is to describe and discuss the sleep difficulties, which are one of the significant complications associated with autism spectrum disorder (ASD).

PURPOSE

Many types of sleep disorders have been reported in ASD individuals, but still lack a comprehensive study and in-depth analysis. Despite the contribution of sleep problems to the overall symptoms of ASD, the symptoms of disturbed sleep experienced by many affected patients have only recently started to receive attention from clinicians and family members.

MATERIALS AND METHODS

This narrative overview has been prepared based on searching standard research databases with specific keywords; b. Additional search was made using the bibliographies of the retrieved articles; and c. author's collection of relevant peer-reviewed articles. Once selected, manuscripts are then compared and summarized based on the author's perspective. Results are based on a qualitative rather than a quantitative level.

RESULTS

This article highlights the role of sleep in the brain and neural development of children and emphasizes that the intensity of sleep problems is associated with an increased occurrence of ASD symptoms. It also suggests the significance of treating sleep problems in ASD individuals.

CONCLUSIONS

The review provides broader perspectives and a better understanding of sleep problems in pathophysiology, mechanism, and management with respect to ASD individuals. Finally, the implications for clinical practice and future agendas have also been discussed.

Birth weight, family history of diabetes and diabetes onset in schizophrenia

INTRODUCTION

The prevalence of diabetes in schizophrenia is twice that in the general population, but there are few reliable predictors of which individuals will develop glucose dysregulation.

OBJECTIVE

To test if abnormal birth weight (either too low or too high) and parental diabetes, both variables that can be ascertained in the clinic, can predict diabetes onset in patients with schizophrenia.

RESEARCH DESIGN AND METHODS

Electronic records of a cohort of 190 clozapine-treated patients (37% treated for more than 20 years) and Cox regression survival analysis (with any type of glucose dysregulation as the event) to account for differences in length of treatment before the event and age at clozapine treatment initiation.

RESULTS

Age at clozapine initiation (Exp(B)=1.098; p<0.001), family history of diabetes (Exp(B)=2.299; p=0.049) and birth weight² (Exp(B)=0.999; p=0.013) were significant predictors of glucose dysregulation onset, while gender was not (Exp(B)=0.1.350; p=0.517). Among individuals with 10 years of follow-up, 80% of those with both abnormal birth weight and a family history of diabetes developed diabetes compared with 56% with only abnormal birth weight, 40% with only a family history of diabetes and 20% in those with neither.

CONCLUSIONS

Since 48% of cases had at least one risk factor and 6% had both risk factors, there is a substantial proportion of patients for whom preventive strategies could be implemented.

Cytomegalovirus Seropositivity and Suicidal Behavior: A Mini-Review

Background and objectives: In recent years, a growing body of research has focused on identifying possible biological markers for suicidal behavior, including infective and immunological markers. In this paper, our aim was to review available evidence concerning the association between cytomegalovirus (CMV) infection and suicide. Materials and Methods: A systematic search according to the PRISMA statement was performed on Pubmed. After the screening procedure, we identified five relevant papers. Results: We found inconsistent evidence linking CMV infection and suicide, with some papers reporting an association between CMV seropositivity and suicidal behavior, and others not finding the association. Conclusions: With the evidence available presently, it is not possible to infer whether there is a correlation between suicide and CMV infection.

Bacterial peptidoglycans as novel signaling molecules from microbiota to brain

Mounting evidence indicates that gut microbiota exerts a broad range of effects on host physiology and development beyond the gastrointestinal tract, including the modulation of brain development. However, the mechanisms mediating the interactions between the microbiota and the developing brain are still poorly understood. Pattern recognition receptors of the innate immune system that recognize microbial products, such as peptidoglycans have emerged as potential key regulators of gut microbiome-brain interactions. Peptidoglycan-sensing molecules are expressed in the placenta and brain during specific time windows of development. Moreover, peptidoglycans are ubiquitously present in circulation and can cross the blood brain barrier. This review brings together the current evidence supporting a broad function of peptidoglycans well beyond host's immunity, extending to neurodevelopment and behavior.