Toxoplasma gondii infection associated with inflammasome activation and neuronal injury.

Toxoplasma gondii (TOXO) infection typically results in chronic latency due to its ability to form cysts in the brain and other organs. Latent toxoplasmosis could promote innate immune responses and impact brain function. A large body of evidence has linked TOXO infection to severe mental illness (SMI). We hypothesized that TOXO immunoglobulin G (IgG) seropositivity, reflecting previous infection and current latency, is associated with increased circulating neuron-specific enolase (NSE), a marker of brain damage, and interleukin-18 (IL-18), an innate immune marker, mainly in SMI. We included 735 patients with SMI (schizophrenia or bipolar spectrum) (mean age 32 years, 47% women), and 518 healthy controls (HC) (mean age 33 years, 43% women). TOXO IgG, expressed as seropositivity/seronegativity, NSE and IL-18 were measured with immunoassays. We searched for main and interaction effects of TOXO, patient/control status and sex on NSE and IL-18. In the whole sample as well as among patients and HC separately, IL-18 and NSE concentrations were positively correlated (p < 0.001). TOXO seropositive participants had significantly higher NSE (3713 vs. 2200 pg/ml, p < 0.001) and IL-18 levels (1068 vs. 674 pg/ml, p < 0.001) than seronegative participants, and evaluation within patients and HC separately showed similar results. Post-hoc analysis on cytomegalovirus and herpes simplex virus 1 IgG status showed no associations with NSE or IL-18 which may suggest TOXO specificity. These results may indicate ongoing inflammasome activation and neuronal injury in people with TOXO infections unrelated to diagnosis.

Serum autoantibodies against α7-nicotinic receptors in subgroups of patients with bipolar disorder or schizophrenia: clinical features and link with peripheral inflammation.

There is growing evidence that autoantibodies (AAbs) against proteins expressed in the brain are playing an important role in neurological and psychiatric disorders. Here, we explore the presence and the role of peripheral AAbs to the α7-nicotinic acetylcholine receptor (nAChR) in inflammatory subgroups of psychiatric patients with bipolar disorder (BD) or schizophrenia (SCZ) and healthy controls. We have identified a continuum of AAb levels in serum when employing a novel ELISA technique, with a significant elevation in patients compared to controls. Using unsupervised two-step clustering to stratify all the subjects according to their immuno-inflammatory background, we delineate one subgroup consisting solely of psychiatric patients with severe symptoms, high inflammatory profile, and significantly increased levels of anti-nAChR AAbs. In this context, we have used monoclonal mouse anti-human α7-nAChR antibodies (α7-nAChR-mAbs) and shown that TNF-α release was enhanced upon LPS stimulation in macrophages pre-incubated with α7-nAChR-mAbs compared to the use of an isotype control. These findings provide a basis for further study of circulating nicotinic AAbs, and the inflammatory profile observed in patients with major mood and psychotic disorders.

Recent anti-infective exposure as a risk factor for first episode of suicidal thoughts and/or behaviors in pediatric patients.

Objectives: We conducted a retrospective cohort study of medical records from a large, Maryland, U.S.-based cohort of pediatric primary care patients for potential associations between antibacterial, antifungal and antiviral prescriptions and subsequent suicidal thoughts and/or behaviors. Methods: Using first suicide-related diagnosis as the outcome and prior prescription of antibacterial, antifungal, and/or antiviral use as the exposure, we employed a series of multivariate Cox proportional hazards models. These models examined the hazard of developing newly recognized suicidal thoughts and/or behaviors, controlling for age, sex, race, insurance, number of encounters during the study period, prior mood disorder diagnosis and number of chronic health conditions. We constructed the same series of models stratified by the groups with and without a prior recorded mental or behavioral health diagnosis (MBHD). Results: Suicidal thoughts and/or behaviors were associated with the previous prescription of an antibacterial, antifungal and/or antiviral medication (HR 1.31, 95 %-CI 1.05-1.64) as well as the total number of such medications prescribed (HR 1.04, 95 %-CI 1.01-1.08), with the strongest relationship among patients with three or more medications (HR 1.44, 95 %-CI 1.06-1.96). Among individual medications, the strongest association was with antibacterial medication (HR 1.28, 95 %-CI 1.03-1.60). Correlations were strongest among the subgroup of patients with no previous (MBHD). Interpretation: Infections treated with antimicrobial medications were associated with increased risks of a suicide-related diagnosis among patients who had not had a previous mental or behavioral health diagnosis. This group should be considered for increased levels of vigilance as well as interventions directed at suicide screening and prevention. Funding: National Institutes of Health, Stanley Medical Research Institute.

Elevated matrix Metalloproteinase-9 associated with reduced cerebellar perineuronal nets in female mice with toxoplasmosis.

Brain infection by the parasite Toxoplasma gondii is thought to impair learning and memory, although the underlying mechanisms remain largely unknown. Recent studies suggest that perineuronal nets (PNNs) and their key regulator, matrix metalloproteinase-9 (MMP-9), have essential roles in synaptic plasticity associated with learning and memory. We investigated their roles in a chronic toxoplasmosis model using female mice. In mice with a high parasite burden of chronic infection, we found that MMP-9 expression was increased in the peripheral circulation and the brain. A correlation was found between the serum levels of MMP-9 and antibodies to the Toxoplasma matrix antigen MAG1, a surrogate marker for Toxoplasma tissue cysts in the brain. MMP-9 elevation was accompanied by increased expression of its endogenous regulators, TIMP-1 and NGAL. An increase in the levels of GSK-3α/ß was observed, alongside a decrease in inhibitory GSK-3α/ß (Ser-21/Ser-9) phosphorylation. MMP-9 expression was notably associated with the loss of PNNs but increased expression of the synaptic vesicle protein synaptophysin. There was a trend toward a negative correlation between MMP-9 and aggrecan expression, a critical PNN component. Together, these results suggest that chronic Toxoplasma infection can cause an increase in MMP-9 expression, resulting in the degradation of PNNs, which provides a possible mechanism for Toxoplasma-associated deficits in learning and memory.

COVID-19 and Youth Mental Health Disparities: Intersectional Trends in Depression, Anxiety and Suicide Risk-Related Diagnoses.

OBJECTIVES: Mental health disparities were prevalent among racially and ethnically minoritized youth prior to the COVID-19 pandemic. As complete datasets from 2022 become available, we can estimate the extent to which the pandemic further magnified existing inequities. Our objective was to quantify disparities in trajectories of depression, anxiety, and suicide risk-related diagnoses in youth before and after the start of the COVID-19 pandemic, using an intersectional lens of race, ethnicity and gender. METHODS: Using electronic medical record data from one mid-Atlantic health care system (2015-2022), we evaluated changes in annual rates of depression, anxiety and suicide risk-related diagnoses in 29,117 youths, aged 8-20 years, using graphical analysis, comparison of adjusted mean differences (AMD) and adjusted mixed multilevel logistic regression. RESULTS: Almost all racial and gender subgroups had significantly higher rates of depression and anxiety after the start of COVID-19 compared to the years prior, with the greatest changes observed in Hispanic and Asian females. Suicide risk-related diagnoses significantly increased among all female subgroups, with the largest increase among Asian females (AMD 4.8, 95% CI 0.2-9.3) and Black females (AMD 4.6, 95% CI 2.2-6.9). CONCLUSIONS: Rates of depression, anxiety, and suicidal thoughts and/or behaviors in young people continued to increase in the post-pandemic period. Many pre-existing disparities between subgroups, especially females, significantly widened, highlighting the importance of using an intersectional lens. Urgent action is warranted, including universal screening of pediatric patients for suicide risk, broadening effective treatment and support options in minoritized patients, and increasing support services to patients and families.

Dysregulation of Microbiota in Patients With First-Episode Psychosis Is Associated With Symptom Severity and Treatment Response.

BACKGROUND: The gut microbiome has been implicated in the pathogenesis of mental disorders where the gut-brain axis acts as a bidirectional communication network. METHODS: Herein, we investigated the compositional and functional differences of gut microbiome between patients with first-episode psychosis (FEP) (n = 26) and healthy control participants (n = 22) using whole-genome shotgun sequencing. In addition, we assessed the oral microbiome in patients with FEP (n = 13) and listed their taxonomic diversity. RESULTS: Our findings suggest that there is a dysbiosis of gut microbiota in patients with FEP. Relative abundance of Bifidobacterium adolescentis, Prevotella copri, and Turicibacter sanguinis was markedly increased (linear discriminant analysis scores [log10] > 1, and Mann-Whitney U test; false discovery rate-adjusted p values < .05) in the FEP group compared with the healthy control participants. Pathway analysis indicated that several metabolic pathways, particularly deoxyribonucleotide biosynthesis, branched-chain amino acid biosynthesis, tricarboxylic acid cycle, and fatty acid elongation and biosynthesis, were dysregulated in the FEP group compared with the healthy control group. In addition, this preliminary study was able to identify specific gut microbes (at baseline) that were predictive of weight gain in the FEP group at a 1-year follow-up. Bacteroides dorei, Bifidobacterium adolescentis, Turicibacter sanguinis, Roseburia spp., and Ruminococcus lactaris were positively associated (eXtreme gradient boosting, XGBoost regression model, Shapley additive explanations, R2 = 0.82) with weight gain. CONCLUSIONS: Our findings may suggest the involvement of gut microbiota in the pathogenesis of psychosis. The benefit of modulation of the gut microbiome in the treatment of psychotic disorders should be explored further.

Racial and Gender Disparities in Suicide and Mental Health Care Utilization in a Pediatric Primary Care Setting.

PURPOSE: We examined racial and gender disparities in the underrecognition of mental health disorders in adolescents and young adults as defined by a suicide-related diagnosis without a previous mental or behavioral health diagnosis. METHODS: We employed a series of adjusted mixed multilevel logistic regression models to determine the odds of specific mental health diagnoses (anxiety, depression, and suicide-related) in a large, U.S. pediatric ambulatory care group (ages 8-20 years) using Electronic Medical Record Data. RESULTS: Using the reference group of White males, White females had 17% increased odds of having a suicide-related diagnosis (odds ratio (OR) 1.17, 95% confidence intervals (CI) 1.03, 1.34) and Black females had 48% increased odds of suicide-related diagnosis (OR 1.48, 95% CI 1.28, 1.71). Conversely, White females had 75% increased odds of recorded anxiety (OR 1.75, 95% CI 1.62, 1.89), Black males had 62% decreased odds of anxiety (OR 0.38, 95% CI 0.33, 0.42), and Black females had 33% decreased odds of anxiety (OR 0.67, 95% CI 0.60, 0.74). White females had 81% increased odds of having recorded depression (OR 1.81, 95% CI 1.62, 2.04) and Black females had 80% increased odds of underrecognized need for mental or behavioral health diagnosis services (OR 1.80, 95% CI 1.53, 2.13) as defined by a suicide-related diagnosis without a previous mental health diagnosis. DISCUSSION: Black adolescents and young adult patients are either not accessing or identified as needing mental health services at the same rates as their White peers, and Black females are experiencing the most underrecognition of need for mental health services.

Inflammatory Conditions During Pregnancy and Risk of Autism and Other Neurodevelopmental Disorders.

Background: Maternal inflammation can result from immune dysregulation and metabolic perturbations during pregnancy. Whether conditions associated with inflammation during pregnancy increase the likelihood of autism spectrum disorder (ASD) or other neurodevelopmental disorders (DDs) is not well understood. Methods: We conducted a case-control study among children born in California from 2011 to 2016 to investigate maternal immune-mediated and cardiometabolic conditions during pregnancy and risk of ASD (n = 311) and DDs (n = 1291) compared with children from the general population (n = 967). Data on maternal conditions and covariates were retrieved from electronic health records. Maternal genetic data were used to assess a causal relationship. Results: Using multivariable logistic regression, we found that mothers with asthma were more likely to deliver infants later diagnosed with ASD (odds ratio [OR] = 1.62, 95% CI: 1.15-2.29) or DDs (OR = 1.30, 95% CI: 1.02-1.64). Maternal obesity was also associated with child ASD (OR = 1.51, 95% CI: 1.07-2.13). Mothers with both asthma and extreme obesity had the greatest odds of delivering an infant later diagnosed with ASD (OR = 16.9, 95% CI: 5.13-55.71). These increased ASD odds were observed among female children only. Polygenic risk scores for obesity, asthma, and their combination showed no association with ASD risk. Mendelian randomization did not support a causal relationship between maternal conditions and ASD. Conclusions: Inflammatory conditions during pregnancy are associated with risk for neurodevelopmental disorders in children. These risks do not seem to be due to shared genetic risk; rather, inflammatory conditions may share nongenetic risk factors with neurodevelopmental disorders. Children whose mothers have both asthma and obesity during pregnancy may benefit from earlier screening and intervention.

Levels of Matrix Metalloproteinase 9 Are Elevated in Persons With Schizophrenia or Bipolar Disorder: The Role of Modifiable Factors.

Background: Matrix metalloproteinases (MMPs) are a diverse set of enzymes associated with inflammation. MMP-9 is of particular interest because it has been associated with autoimmune and cardiopulmonary disorders, tobacco smoking, and obesity, prevalent in psychiatric populations. Methods: Sensitive enzyme immunoassays measured MMP-9 in blood samples from 1121 individuals (mean age = 35.6 [SD = 13.0] years; 47.7% male; 440 with schizophrenia, 399 with bipolar disorder, and 282 without a psychiatric disorder). We estimated the odds of diagnosis associated with MMP-9, demographic variables, tobacco smoking, and obesity, and also the partial explained variance using regression methods. We also determined the association between psychiatric medications and MMP-9 levels. Results: Individuals with elevated MMP-9 levels had higher odds of schizophrenia or bipolar disorder compared with the nonpsychiatric group adjusted for demographic variables. Partial correlation analyses indicated the demographic-adjusted variance associated with MMP-9, smoking, obesity, and their interaction explained 59.6% for schizophrenia and 39.9% for bipolar disorder. Levels of MMP-9 were substantially lower in individuals receiving valproate, particularly relatively high doses. Conclusions: Individuals with higher levels of MMP-9 have significantly higher odds of schizophrenia or bipolar disorder. Individuals receiving valproate had substantially lower levels of MMP-9, possibly related to its ability to inhibit histone deacetylation. A substantial portion of the variance in clinical disorders associated with MMP-9 can be attributed to smoking or obesity. Interventions to reduce smoking and obesity might reduce the morbidity and mortality associated with elevated MMP-9 levels and improve the health outcomes of individuals with these disorders.

Prospects and Pitfalls of Plasma Complement C4 in Schizophrenia: Building a Better Biomarker.

Complex brain disorders like schizophrenia may have multifactorial origins related to mis-timed heritable and environmental factors interacting during neurodevelopment. Infections, inflammation, and autoimmune diseases are over-represented in schizophrenia leading to immune system-centered hypotheses. Complement component C4 is genetically and neurobiologically associated with schizophrenia, and its dual activity peripherally and in the brain makes it an exceptional target for biomarker development. Studies to evaluate the biomarker potential of plasma or serum C4 in schizophrenia do so to understand how peripheral C4 might reflect central nervous system-derived neuroinflammation, synapse pruning, and other mechanisms. This effort, however, has produced mostly conflicting results, with peripheral C4 sometimes elevated, reduced, or unchanged between comparison groups. We undertook a pilot biomarker development study to systematically identify sociodemographic, genetic, and immune-related variables (autoimmune, infection-related, gastrointestinal, inflammatory), which may be associated with plasma C4 levels in schizophrenia (SCH; n = 335) and/or in nonpsychiatric comparison subjects (NCs; n = 233). As with previously inconclusive studies, we detected no differences in plasma C4 levels between SCH and NCs. In contrast, levels of general inflammation, C-reactive protein (CRP), were significantly elevated in SCH compared to NCs (ANOVA, F = 20.74, p < 0.0001), suggestive that plasma C4 and CRP may reflect different sources or causes of inflammation. In multivariate regressions of C4 gene copy number variants, plasma C4 levels were correlated only for C4A (not C4B, C4L, C4S) and only in NCs (R Coeff = 0.39, CI = 0.01-0.77, R2 = 0.18, p < 0.01; not SCH). Other variables associated with plasma C4 levels only in NCs included sex, double-stranded DNA IgG, tissue-transglutaminase (TTG) IgG, and cytomegalovirus IgG. Toxoplasma gondii IgG was the only variable significantly correlated with plasma C4 in SCH but not in NCs. Many variables were associated with plasma C4 in both groups (body mass index, race, CRP, N-methyl-D-aspartate receptor (NMDAR) NR2 subunit IgG, TTG IgA, lipopolysaccharide-binding protein (LBP), and soluble CD14 (sCD14). While the direction of most C4 associations was positive, autoimmune markers tended to be inverse, and associated with reduced plasma C4 levels. When NMDAR-NR2 autoantibody-positive individuals were removed, plasma C4 was elevated in SCH versus NCs (ANOVA, F = 5.16, p < 0.02). Our study was exploratory and confirmation of the many variables associated with peripheral C4 requires replication. Our preliminary results point toward autoimmune factors and exposure to the pathogen, T. gondii, as possibly significant contributors to variability of total C4 protein levels in plasma of individuals with schizophrenia.

Suppressed immune and metabolic responses to intestinal damage-associated microbial translocation in myalgic encephalomyelitis/chronic fatigue syndrome.

The etiology and mechanism of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) are poorly understood and no biomarkers have been established. Specifically, the relationship between the immunologic, metabolic, and gastrointestinal abnormalities associated with ME/CFS and their relevance to established symptoms of the condition remain unclear. Relying on data from two independent pairs of ME/CFS and control cohorts, one at rest and one undergoing an exercise challenge, we identify a state of suppressed acute-phase innate immune response to microbial translocation in conjunction with a compromised gut epithelium in ME/CFS. This immunosuppression, along with observed enhancement of compensatory antibody responses to counter the microbial translocation, was associated with and may be mediated by alterations in glucose and citrate metabolism and an IL-10 immunoregulatory response. Our findings provide novel insights into mechanistic pathways, biomarkers, and potential therapeutic targets in ME/CFS, including in the context of exertion, with relevance to both intestinal and extra-intestinal symptoms.

Cytomegalovirus antibodies are associated with mood disorders, suicide, markers of neuroinflammation, and microglia activation in postmortem brain samples.

Cytomegalovirus (CMV) is a common, neurotrophic herpesvirus that can be reactivated by inflammation and cause central nervous system disease. We hypothesize that CMV may contribute to the neuroinflammation that underlies some psychiatric disorders by (1) exacerbating inflammation through the induction of anti-viral immune responses, and (2) translating peripheral inflammation into neuroinflammation. We investigated whether the presence of anti-CMV antibodies in blood were associated with mental illness, suicide, neuroinflammation, and microglial density in the dorsolateral prefrontal cortex (DLPFC) in postmortem samples. Data (n = 114 with schizophrenia; n = 78 with bipolar disorder; n = 87 with depression; n = 85 controls) were obtained from the Stanley Medical Research Institute. DLPFC gene expression data from a subset of 82 samples were categorized into "high" (n = 30), and "low" (n = 52) inflammation groups based on a recursive two-step cluster analysis using expression data for four inflammation-related genes. Measurements of the ratio of non-ramified to ramified microglia, a proxy of microglial activation, were available for a subset of 49 samples. All analyses controlled for age, sex, and ethnicity, as well as postmortem interval, and pH for gene expression and microglial outcomes. CMV seropositivity significantly increased the odds of a mood disorder diagnosis (bipolar disorder: OR = 2.45; major depression: OR = 3.70) and among the psychiatric samples, of suicide (OR = 2.09). Samples in the upper tercile of anti-CMV antibody titers were more likely to be members of the "high" inflammation group (OR = 4.41, an effect driven by schizophrenia and bipolar disorder samples). CMV positive samples also showed an increased ratio of non-ramified to ramified microglia in layer I of the DLPFC (Cohen's d = 0.81) as well as a non-significant increase in this ratio for the DLPFC as a whole (d = 0.56). The results raise the possibility that the reactivation of CMV contributes to the neuroinflammation that underlies some cases of psychiatric disorders.

Immune cell subsets in patients with bipolar disorder or schizophrenia with history of childhood maltreatment.

A history of Childhood Maltreatment (CM) has been repeatedly associated with an increased risk of developing bipolar disorders (BD) or schizophrenia (SZ). The impact of severe stress induced by CM has been proposed to be mediated by elevated inflammation reflected by dysregulated inflammatory processes. Little is known about the potential impact of CM on lymphocyte subpopulations or the role of pre-existing infections on CM physiological consequences. This study therefore explored the role of CM and past infection exposure impact on lymphocyte subpopulations to give an indication of their relevance as stressors in the pathoetiology of major mood and psychotic disorders. 118 adult patients with SZ, and 152 with BD were included in the analysis. CM history was assessed by the Childhood Trauma Questionnaire (CTQ), with current and past psychiatric symptomatology also evaluated. Circulating immune cell subsets were analyzed using flow cytometry-based analysis. Past exposure to common infectious stigma including toxoplasma, cytomegalovirus (CMV) and Epstein-Barr virus (EBV) were measured by solid phase-enzyme microplate and ELISA immunoassays. The relationship between CM, biological phenotypes (including immune cell subsets distribution and past infectious status) and clinical phenotypes were analyzed using univariate and multivariate analyses. BD patients with, versus without, CM had higher levels of CD3+CD8+ cytotoxic T cells and CMV antibodies along with decreased levels of CD45RA+CCR7+CD8+ naïve CD8+ T cells, and a more severe clinical profile. CMV antibody levels were inversely associated with the CD3 + CD8 + lymphocyte subset level. SZ patients with, versus without, CM, showed lower levels of CD14 + monocytes and no specific clinical characteristics. The accumulation of different types of maltreatment associated with increased body mass index and CMV autoantibodies as well as decreased levels of CD14 + monocytes. In both BD and SZ, further analysis according to the type and the number of CM subtypes showed association with specific changes in lymphocyte cell subsets, clinical profile, and infectious stigma. Adults with BD or SZ exposed to CM exhibit specific immune cell subset profiles, clinical features, and stigma of past infections. In BD, our data indicate an interplay between CM and CMV infections, which may possibly contribute to premature aging and cellular senescence, both of which have previously been shown to associate with mood disorders. Longitudinal studies of CM-exposed patients are required to clarify the interactions of CM and viral infections, including as to the pathophysiological processes driving patient symptomatology.

Association of common infections with cognitive performance in the Baltimore Epidemiologic Catchment Area study follow-up.

INTRODUCTION: Growing evidence suggests that some common infections are causally associated with cognitive impairment; however, less is known about the burden of multiple infections. METHODS: We investigated the cross-sectional association of positive antibody tests for herpes simplex virus, cytomegalovirus (CMV), Epstein-Barr virus (EBV), varicella zoster virus (VZV), and Toxoplasma gondii (TOX) with Mini-Mental State Examination (MMSE) and delayed verbal recall performance in 575 adults aged 41-97 from the Baltimore Epidemiologic Catchment Area Study. RESULTS: In multivariable-adjusted zero-inflated Poisson (ZIP) regression models, positive antibody tests for CMV (p = .011) and herpes simplex virus (p = .018) were individually associated with poorer MMSE performance (p = .011). A greater number of positive antibody tests among the five tested was associated with worse MMSE performance (p = .001). DISCUSSION: CMV, herpes simplex virus, and the global burden of multiple common infections were independently associated with poorer cognitive performance. Additional research that investigates whether the global burden of infection predicts cognitive decline and Alzheimer's disease biomarker changes is needed to confirm these findings.

Immunotherapy targeting the PD-1 pathway alleviates neuroinflammation caused by chronic Toxoplasma infection.

Toxoplasma gondii can infect the host brain and trigger neuroinflammation. Such neuroinflammation might persist for years if the infection is not resolved, resulting in harmful outcomes for the brain. We have previously demonstrated the efficacy of immunotherapy targeting the programmed cell death protein 1 (PD-1) pathway on clearance of Toxoplasma tissue cysts. We aimed to test whether parasite clearance would lead to the resolution of neuroinflammation in infected brains. We established chronic Toxoplasma infection in BALB/c mice using the cyst-forming Prugniaud strain. Mice then received αPD-L1 or isotype control antibodies. After completion of the therapy, mice were euthanized six weeks later. The number of brain tissue cysts, Toxoplasma-specific CD8 + T cell proliferation and IFN-γ secretion, serum cytokine and chemokine levels, and CNS inflammation were measured. In αPD-L1-treated mice, we observed reduced brain tissue cysts, increased spleen weight, elevated IFN-γ production by antigen-specific CD8 + T cells, and a general increase in multiple serum cytokines and chemokines. Importantly, αPD-L1-treated mice displayed attenuation of meningeal lymphocytes, reactive astrocytes, and C1q expression. The reduction in inflammation-related proteins is correlated with reduced parasite burden. These results suggest that promoting systemic immunity results in parasite clearance, which in turn alleviates neuroinflammation. Our study may have implications for some brain infections where neuroinflammation is a critical component.

Cigarette smoking is associated with Herpesviruses in persons with and without serious mental illness.

INTRODUCTION: Herpesviruses are recognized as major causes of human diseases. Following initial infection, Herpesviruses can undergo cycles of reactivation controlled largely by the immune system. Cigarette smoking is an important modulator of the immune system particularly in individuals with serious mental illness where smoking is associated with increased rates of cardiopulmonary diseases and mortality. However, the effect of smoking on Herpesviruses has not been extensively studied. METHODS: In this nested cohort study, cigarette smoking was assessed in 1323 persons with serious mental illness or without a psychiatric disorder ascertained in a psychiatric health care system and the adjacent community. Participants provided a blood sample from which were measured IgG class antibodies to five human Herpesviruses: Cytomegalovirus (CMV), Epstein Barr Virus (EBV), Herpes Simplex Virus-Type 1 (HSV-1); Varicella Zoster Virus (VZV); and Human Herpes Virus-Type 6 (HHV-6). The associations between smoking variables and antibody levels to the Herpesviruses were analyzed among diagnostic groups in multiple regression models adjusted for age, sex, and race. RESULTS: Current smoking was significantly associated with higher levels of antibodies to CMV (coefficient .183, 95% CI .049, .317, p<.001, q<.007) and the three EBV proteins (EBV NA -(coefficient .088, 95% CI .032, .143, p = .002, q<.014; EBV Virion - coefficient .100, 95% CI .037, .163, p = .002, q<.014; and EBV VCA - coefficient .119, 95% CI .061, .177, p = .00004, q<.0016). The amount of cigarettes smoked was also correlated with higher levels of antibodies to the three EBV proteins. Interaction analyses indicated that the association between cigarette smoking and levels of antibodies to CMV and EBV was independent of diagnostic group. Cigarette smoking was not significantly associated with the level of antibodies to HSV-1, VZV, or HHV-6. CONCLUSIONS: Individuals who smoke cigarettes have increased levels of IgG antibodies to CMV and EBV. Cigarette smoking may be a contributory factor in the relationship between CMV, EBV and chronic somatic disorders associated with these viruses.

Therapeutic Implications of the Microbial Hypothesis of Mental Illness.

There is increasingly compelling evidence that microorganisms may play an etiological role in the emergence of mental illness in a subset of the population. Historically, most work has focused on the neurotrophic herpesviruses, herpes simplex virus type 1 (HSV-1), cytomegalovirus (CMV), and Epstein-Barr virus (EBV) as well as the protozoan, Toxoplasma gondii. In this chapter, we provide an umbrella review of this literature and additionally highlight prospective studies that allow more mechanistic conclusions to be drawn. Next, we focus on clinical trials of anti-microbial medications for the treatment of psychiatric disorders. We critically evaluate six trials that tested the impact of anti-herpes medications on inflammatory outcomes in the context of a medical disorder, nine clinical trials utilizing anti-herpetic medications for the treatment of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) or schizophrenia, and four clinical trials utilizing anti-parasitic medications for the treatment of schizophrenia. We then turn our attention to evidence for a gut dysbiosis and altered microbiome in psychiatric disorders, and the potential therapeutic effects of probiotics, including an analysis of more than 10 randomized controlled trials of probiotics in the context of schizophrenia, bipolar disorder (BD), and major depressive disorder (MDD).

Herpesvirus Infections in the Human Brain: A Neural Cell Model of the Complement System Derived from Induced Pluripotent Stem Cells.

BACKGROUND: Herpesviruses alter cognitive functions in humans following acute infections; progressive cognitive decline and dementia have also been suggested. It is important to understand the pathogenic mechanisms of such infections. The complement system - comprising functionally related proteins integral for systemic innate and adaptive immunity - is an important component of host responses. The complement system has specialized functions in the brain. Still, the dynamics of the brain complement system are still poorly understood. Many complement proteins have limited access to the brain from plasma, necessitating synthesis and specific regulation of expression in the brain; thus, complement protein synthesis, activation, regulation, and signaling should be investigated in human brain-relevant cellular models. Cells derived from human-induced pluripotent stem cells (hiPSCs) could enable tractable models. METHODS: Human-induced pluripotent stem cells were differentiated into neuronal (hi-N) and microglial (hi-M) cells that were cultured with primary culture human astrocyte-like cells (ha-D). Gene expression analyses and complement protein levels were analyzed in mono- and co-cultures. RESULTS: Transcript levels of complement proteins differ by cell type and co-culture conditions, with evidence for cellular crosstalk in co-cultures. Hi-N and hi-M cells have distinct patterns of expression of complement receptors, soluble factors, and regulatory proteins. hi-N cells produce complement factor 4 (C4) and factor B (FB), whereas hi-M cells produce complement factor 2 (C2) and complement factor 3 (C3). Thus, neither hi-N nor hi-M cells can form either of the C3-convertases - C4bC2a and C3bBb. However, when hi-N and hi-M cells are combined in co-cultures, both types of functional C3 convertase are produced, indicated by elevated levels of the cleaved C3 protein, C3a. CONCLUSIONS: hiPSC-derived co-culture models can be used to study viral infection in the brain, particularly complement receptor and function in relation to cellular "crosstalk." The models could be refined to further investigate pathogenic mechanisms.

Non-SARS Coronaviruses in Individuals with Psychiatric Disorders.

BACKGROUND: The pandemic caused by severe acute respiratory syndrome-Coronavirus-2 (SARS-CoV-2) has highlighted the importance of coronaviruses in human health. Several seasonal, non-SARS Coronaviruses are endemic in most areas of the world. In a previous study, we found that the level of antibodies to these seasonal Coronaviruses was elevated in persons with a recent onset of psychosis. In the current study, the level of antibodies to seasonal Coronaviruses was compared between individuals with psychiatric disorders and a non-psychiatric comparison group. METHODS: Participants (N = 195) were persons with a diagnosis of schizophrenia, bipolar disorder, major depressive disorder, or without a psychiatric disorder. Each participant had a blood sample drawn from which were measured IgG antibodies to the spike proteins in four non-SARS Coronaviruses, 229E, HKU1, NL63, and OC43, using a multiplex electrochemiluminescence assay. Linear regression models were employed to compare the levels of antibodies between each psychiatric group and the comparison group adjusting for demographic variables. Logistic regression models were employed to calculate the odds ratios associated with increased levels of antibodies to each seasonal Coronavirus based on the 50th percentile level of the comparison group. RESULTS: The schizophrenia group had significantly increased levels of antibodies to the seasonal Coronaviruses OC43 and NL63. This group also had increased odds of having elevated antibody levels to OC43. The major depression group showed a significantly lower level of antibodies to Coronavirus 229E. There were no significant differences between any of the psychiatric groups and the comparison group in the levels of antibodies to seasonal Coronaviruses 229E or HKU1. CONCLUSIONS: The elevated level of antibodies to OC43 and NL63 in the schizophrenia group indicates increased exposure to these agents and raises the possibility that Coronaviruses may contribute to the etiopathology of this disorder. The cause-and-effect relationship between seasonal Coronaviruses and psychiatric disorders should be the subject of additional investigations focusing on longitudinal cohort studies.