Angiogenic and immune signatures in plasma of young relatives at familial high-risk for psychosis and first-episode patients: A preliminary study

Immune and oxidative stress biomarkers in pediatric psychosis and psychosis-risk: Meta-analyses and systematic review

OBJECTIVE

While genetic and cohort studies suggest immune and reduction/oxidation (redox) alterations occur in psychosis, less is known about potential alterations in children and adolescents.

METHODS

We conducted a systematic review to identify immune and redox biomarker studies in children and adolescents (mean age ≤ 18 years old) across the psychosis spectrum: from psychotic like experiences, which are common in children, to threshold psychotic disorders like schizophrenia. We conducted meta-analyses when at least three studies measured the same biomarker.

RESULTS

The systematic review includes 38 pediatric psychosis studies. The meta-analyses found that youth with threshold psychotic disorders had higher neutrophil/lymphocyte ratio (Hedge's g = 0.40, 95 % CI 0.17 - 0.64), tumor necrosis factor (Hedge's g = 0.38, 95 % CI 0.06 - 0.69), C-reactive protein (Hedge's g = 0.38, 95 % CI 0.05 - 0.70), interleukin-6 (Hedge's g = 0.35; 95 % CI 0.11 - 0.64), and total white blood cell count (Hedge's g = 0.29, 95 % CI 0.12 - 0.46) compared to youth without psychosis. Other immune and oxidative stress meta-analytic findings were very heterogeneous.

CONCLUSION

Results from several studies are consistent with the hypothesis that signals often classified as "proinflammatory" are elevated in threshold pediatric psychotic disorders. Data are less clear for immune markers in subthreshold psychosis and redox markers across the subthreshold and threshold psychosis spectrum. Immune and redox biomarker intervention studies are lacking, and research investigating interventions targeting the immune system in threshold pediatric psychosis is especially warranted.

Peripheral inflammatory subgroup differences in anterior Default Mode network and multiplex functional network topology are associated with cognition in psychosis

INTRODUCTION

High-inflammation subgroups of patients with psychosis demonstrate cognitive deficits and neuroanatomical alterations. Systemic inflammation assessed using IL-6 and C-reactive protein may alter functional connectivity within and between resting-state networks, but the cognitive and clinical implications of these alterations remain unknown. We aim to determine the relationships of elevated peripheral inflammation subgroups with resting-state functional networks and cognition in psychosis spectrum disorders.

METHODS

Serum and resting-state fMRI were collected from psychosis probands (schizophrenia, schizoaffective, psychotic bipolar disorder) and healthy controls (HC) from the B-SNIP1 (Chicago site) study who were stratified into inflammatory subgroups based on factor and cluster analyses of 13 cytokines (HC Low n = 32, Proband Low n = 65, Proband High n = 29). Nine resting-state networks derived from independent component analysis were used to assess functional and multilayer connectivity. Inter-network connectivity was measured using Fisher z-transformation of correlation coefficients. Network organization was assessed by investigating networks of positive and negative connections separately, as well as investigating multilayer networks using both positive and negative connections. Cognition was assessed using the Brief Assessment of Cognition in Schizophrenia. Linear regressions, Spearman correlations, permutations tests and multiple comparison corrections were used for analyses in R.

RESULTS

Anterior default mode network (DMNa) connectivity was significantly reduced in the Proband High compared to Proband Low (Cohen's d = -0.74, p = 0.002) and HC Low (d = -0.85, p = 0.0008) groups. Inter-network connectivity between the DMNa and the right-frontoparietal networks was lower in Proband High compared to Proband Low (d = -0.66, p = 0.004) group. Compared to Proband Low, the Proband High group had lower negative (d = 0.54, p = 0.021) and positive network (d = 0.49, p = 0.042) clustering coefficient, and lower multiplex network participation coefficient (d = -0.57, p = 0.014). Network findings in high inflammation subgroups correlate with worse verbal fluency, verbal memory, symbol coding, and overall cognition.

CONCLUSION

These results expand on our understanding of the potential effects of peripheral inflammatory signatures and/or subgroups on network dysfunction in psychosis and how they relate to worse cognitive performance. Additionally, the novel multiplex approach taken in this study demonstrated how inflammation may disrupt the brain's ability to maintain healthy co-activation patterns between the resting-state networks while inhibiting certain connections between them.

Brain microvascular endothelial cells and blood-brain barrier dysfunction in psychotic disorders

Although there is convergent evidence for blood-brain barrier (BBB) dysfunction and peripheral inflammation in schizophrenia (SZ) and bipolar disorder (BD), it is unknown whether BBB deficits are intrinsic to brain microvascular endothelial cells (BMECs) or arise via effects of peripheral inflammatory cytokines. We examined BMEC function using stem cell-based models to identify cellular and molecular deficits associated with BBB dysfunction in SZ and BD. Induced pluripotent stem cells (iPSCs) from 4 SZ, 4 psychotic BD and 4 healthy control (HC) subjects were differentiated into BMEC-"like" cells. Gene expression and protein levels of tight junction proteins were assessed. Transendothelial electrical resistance (TEER) and permeability were assayed to evaluate BBB function. Cytokine levels were measured from conditioned media. BMECs derived from human iPSCs in SZ and BD did not show differences in BBB integrity or permeability compared to HC BMECs. Outlier analysis using TEER revealed a BBB-deficit (n = 3) and non-deficit (n = 5) group in SZ and BD lines. Stratification based on BBB function in SZ and BD patients identified a BBB-deficit subtype with reduced barrier function, tendency for increased permeability to smaller molecules, and decreased claudin-5 (CLDN5) levels. BMECs from the BBB-deficit group show increased matrix metallopeptidase 1 (MMP1) activity, which correlated with reduced CLDN5 and worse BBB function, and was improved by tumor necrosis factor α (TNFα) and MMP1 inhibition. These results show potential deficits in BMEC-like cells in psychotic disorders that result in BBB disruption and further identify TNFα and MMP1 as promising targets for ameliorating BBB deficits.

Serum Levels of Tumor Necrosis Factor-α and Vascular Endothelial Growth Factor in the Subtypes of Clinical High Risk Individuals: A Prospective Cohort Study

Introduction

Numerous studies have established the roles of inflammation and angioneurins in the pathogenesis of schizophrenia (SCZ). This study aimed to compare the serum levels of tumour necrosis factor (TNF)-α and vascular endothelial growth factor (VEGF) in patients at clinical high risk (CHR) for psychosis or SCZ at baseline and one year after treatment.

Methods

A total of 289 CHR participants from the Shanghai At Risk for Psychosis Extended Program (SHARP) were tracked for a year. They were divided into two and four subtypes based on symptom severity according to the Structured Interview for Prodromal Syndromes (SIPS) and received standard medical care. At baseline and one-year follow-up, TNF-α and VEGF were detected using enzyme-linked immunosorbent assay, and pathological features were assessed using the Global Assessment of Function (GAF) score.

Results

Baseline TNF-α levels did not differ significantly, while VEGF levels were lower in patients with more severe symptoms. VEGF showed a negative correlation with negative features, both overall (r = -0.212, p = 0.010) and in the subgroup with higher positive scores (r = -0.370, p = 0.005). TNF-α was positively correlated with negative symptoms in the subgroup with higher negative scores (r = 0.352, p = 0.002). A three-way multivariate analysis of variance demonstrated that participants in Subtype 1 of positive or negative symptoms performed better than those in Subtype 2, with significant main effects and interactions of group and both cytokines.

Discussion

TNF-α and VEGF levels are higher and lower, respectively, in CHR patients with more severe clinical symptoms, particularly negative symptoms, which point to a worsening inflammatory and vascular status in the brain.

Peripheral inflammation is associated with impairments of inhibitory behavioral control and visual sensorimotor function in psychotic disorders

Elevated markers of peripheral inflammation are common in psychosis spectrum disorders and have been associated with brain anatomy, pathology, and physiology as well as clinical outcomes. Preliminary evidence suggests a link between inflammatory cytokines and C-reactive protein (CRP) with generalized cognitive impairments in a subgroup of individuals with psychosis. Whether these patients with elevated peripheral inflammation demonstrate deficits in specific cognitive domains remains unclear. To examine this, seventeen neuropsychological and sensorimotor tasks and thirteen peripheral inflammatory and microvascular markers were quantified in a subset of B-SNIP consortium participants (129 psychosis, 55 healthy controls). Principal component analysis was conducted across the inflammatory markers, resulting in five inflammation factors. Three discrete latent cognitive domains (Visual Sensorimotor, General Cognitive Ability, and Inhibitory Behavioral Control) were characterized based on the neurobehavioral battery and examined in association with inflammation factors. Hierarchical clustering analysis identified cognition-sensitive high/low inflammation subgroups. Among persons with psychotic disorders but not healthy controls, higher inflammation scores had significant associations with impairments of Inhibitory Control (R2 = 0.100, p-value = 2.69e-4, q-value = 0.004) and suggestive associations with Visual Sensorimotor function (R2 = 0.039, p-value = 0.024, q-value = 0.180), but not with General Cognitive Ability (R2 = 0.015, p-value = 0.162). Greater deficits in Inhibitory Control were observed in the high inflammation patient subgroup, which represented 30.2 % of persons with psychotic disorders, as compared to the low inflammation psychosis subgroup. These findings indicate that inflammation dysregulation may differentially impact specific neurobehavioral domains across psychotic disorders, particularly performance on tasks requiring ongoing behavioral monitoring and control.

Serum immune markers and transition to psychosis in individuals at clinical high risk

Individuals at clinical high risk (CHR) for psychosis have been found to have altered cytokine levels, but whether these changes are related to clinical outcomes remains unclear. We addressed this issue by measuring serum levels of 20 immune markers in 325 participants (n = 269 CHR, n = 56 healthy controls) using multiplex immunoassays, and then followed up the CHR sample to determine their clinical outcomes. Among 269 CHR individuals, 50 (18.6 %) developed psychosis by two years. Univariate and machine learning techniques were used to compare levels of inflammatory markers in CHR subjects and healthy controls, and in CHR subjects who had (CHR-t), or had not (CHR-nt) transitioned to psychosis. An ANCOVA identified significant group differences (CHR-t, CHR-nt and controls) and post-hoc tests indicated that VEGF levels and the IL-10/IL-6 ratio were significantly higher in CHR-t than CHR-nt, after adjusting for multiple comparisons. Using a penalised logistic regression classifier, CHR participants were distinguished from controls with an area-under the curve (AUC) of 0.82, with IL-6 and IL-4 levels the most important discriminating features. Transition to psychosis was predicted with an AUC of 0.57, with higher VEGF level and IL-10/IL-6 ratio the most important discriminating features. These data suggest that alterations in the levels of peripheral immune markers are associated with the subsequent onset of psychosis. The association with increased VEGF levels could reflect altered blood-brain-barrier (BBB) permeability, while the link with an elevated IL-10/IL-6 ratio points to an imbalance between anti- and pro-inflammatory cytokines.

Regional and Sex-Specific Alterations in the Visual Cortex of Individuals With Psychosis Spectrum Disorders

BACKGROUND

Impairments of the visual system are implicated in psychotic disorders. However, studies exploring visual cortex (VC) morphology in this population are limited. Using data from the Bipolar-Schizophrenia Network on Intermediate Phenotypes consortium, we examined VC structure in psychosis probands and their first-degree relatives (RELs), sex differences in VC measures, and their relationships with cognitive and peripheral inflammatory markers.

METHODS

Cortical thickness, surface area, and volume of the primary (Brodmann area 17/V1) and secondary (Brodmann area 18/V2) visual areas and the middle temporal (V5/MT) region were quantified using FreeSurfer version 6.0 in psychosis probands (n = 530), first-degree RELs (n = 544), and healthy control subjects (n = 323). Familiality estimates were determined for probands and RELs. General cognition, response inhibition, and emotion recognition functions were assessed. Systemic inflammation was measured in a subset of participants.

RESULTS

Psychosis probands demonstrated significant area, thickness, and volume reductions in V1, V2, and MT, and their first-degree RELs demonstrated area and volume reductions in MT compared with control subjects. There was a higher degree of familiality for VC area than thickness. Area and volume reductions in V1 and V2 were sex dependent, affecting only female probands in a regionally specific manner. Reductions in some VC regions were correlated with poor general cognition, worse response inhibition, and increased C-reactive protein levels.

CONCLUSIONS

The visual cortex is a site of significant pathology in psychotic disorders, with distinct patterns of area and thickness changes, sex-specific and regional effects, potential contributions to cognitive impairments, and association with C-reactive protein levels.

Inflammation subtypes in psychosis and their relationships with genetic risk for psychiatric and cardiometabolic disorders

Cardiometabolic disorders have known inflammatory implications, and peripheral measures of inflammation and cardiometabolic disorders are common in persons with psychotic disorders. Inflammatory signatures are also related to neurobiological and behavioral changes in psychosis. Relationships between systemic inflammation and cardiometabolic genetic risk in persons with psychosis have not been examined. Thirteen peripheral inflammatory markers and genome-wide genotyping were assessed in 122 participants (n ​= ​86 psychosis, n ​= ​36 healthy controls) of European ancestry. Cluster analyses of inflammatory markers classified higher and lower inflammation subgroups. Single-trait genetic risk scores (GRS) were constructed for each participant using previously reported GWAS summary statistics for the following traits: schizophrenia, bipolar disorder, major depressive disorder, coronary artery disease, type-2 diabetes, low-density lipoprotein, high-density lipoprotein, triglycerides, and waist-to-hip ratio. Genetic correlations across traits were quantified. Principal component (PC) analysis of the cardiometabolic GRSs generated six PC loadings used in regression models to examine associations with inflammation markers. Functional module discovery explored biological mechanisms of the inflammation association of cardiometabolic GRS genes. A subgroup of 38% persons with psychotic disorders was characterized with higher inflammation status. These higher inflammation individuals had lower BACS scores (p ​= ​0.038) compared to those with lower inflammation. The first PC of the cardiometabolic GRS matrix was related to higher inflammation status in persons with psychotic disorders (OR ​= ​2.037, p ​= ​0.001). Two of eight modules within the functional interaction network of cardiometabolic GRS genes were enriched for immune processes. Cardiometabolic genetic risk may predispose some individuals with psychosis to elevated inflammation which adversely impacts cognition associated with illness.

Inflammatory Subtypes in Antipsychotic-Naïve First-Episode Schizophrenia are Associated with Altered Brain Morphology and Topological Organization

BACKGROUND

Peripheral inflammation is implicated in schizophrenia, however, not all individuals demonstrate inflammatory alterations. Recent studies identified inflammatory subtypes in chronic psychosis with high inflammation having worse cognitive performance and displaying neuroanatomical enlargement compared to low inflammation subtypes. It is unclear if inflammatory subtypes exist earlier in the disease course, thus, we aim to identify inflammatory subtypes in antipsychotic naïve First-Episode Schizophrenia (FES).

METHODS

12 peripheral inflammatory markers, clinical, cognitive, and neuroanatomical measures were collected from a naturalistic study of antipsychotic-naïve FES patients. A combination of unsupervised principal component analysis and hierarchical clustering was used to categorize inflammatory subtypes from their cytokine data (17 FES High, 30 FES Low, and 33 healthy controls (HCs)). Linear regression analysis was used to assess subtype differences. Neuroanatomical correlations with clinical and cognitive measures were performed using partial Spearman correlations. Graph theoretical analyses were performed to assess global and local network properties across inflammatory subtypes.

RESULTS

The FES High group made up 36% of the FES group and demonstrated significantly greater levels of IL1β, IL6, IL8, and TNFα compared to FES Low, and higher levels of IL1β and IL8 compared to HCs. FES High had greater right parahippocampal, caudal anterior cingulate, and bank superior sulcus thicknesses compared to FES Low. Compared to HCs, FES Low showed smaller bilateral amygdala volumes and widespread cortical thickness. FES High and FES Low groups demonstrated less efficient topological organization compared to HCs. Individual cytokines and/or inflammatory signatures were positively associated with cognition and symptom measures.

CONCLUSIONS

Inflammatory subtypes are present in antipsychotic-naïve FES and are associated with inflammation-mediated cortical expansion. These findings support our previous findings in chronic psychosis and point towards a connection between inflammation and blood-brain barrier disruption. Thus, identifying inflammatory subtypes may provide a novel therapeutic avenue for biomarker-guided treatment involving anti-inflammatory medications.

Quantifying Retinal Microvascular Morphology in Schizophrenia Using Swept-Source Optical Coherence Tomography Angiography

BACKGROUND

Retinovascular changes are reported on fundus imaging in schizophrenia (SZ). This is the first study to use swept-source optical coherence tomography angiography (OCT-A) to comprehensively examine retinal microvascular changes in SZ.

METHODS

This study included 30 patients with SZ/schizoaffective disorder (8 early and 15 chronic) and 22 healthy controls (HCs). All assessments were performed at Beth Israel Deaconess Medical Center and Massachusetts Eye and Ear. All participants underwent swept-source OCT-A of right (oculus dextrus [OD]) and left (oculus sinister [OS]) eye, clinical, and cognitive assessments. Macular OCT-A images (6 × 6 mm) were collected with the DRI Topcon Triton for superficial, deep, and choriocapillaris vascular regions. Microvasculature was quantified using vessel density (VD), skeletonized vessel density (SVD), fractal dimension (FD), and vessel diameter index (VDI).

RESULTS

Twenty-one HCs and 26 SZ subjects were included. Compared to HCs, SZ patients demonstrated higher overall OD superficial SVD, OD choriocapillaris VD, and OD choriocapillaris SVD, which were primarily observed in the central, central and outer superior, and central and outer inferior/superior, respectively. Early-course SZ subjects had significantly higher OD superficial VD, OD choriocapillaris SVD, and OD choriocapillaris FD compared to matched HCs. Higher bilateral (OU) superficial VD correlated with lower Positive and Negative Syndrome Scale (PANSS) positive scores, and higher OU deep VDI was associated with higher PANSS negative scores.

CONCLUSIONS AND RELEVANCE

These results suggest the presence of microvascular dysfunction associated with early-stage SZ. Clinical associations with microvascular alterations further implicate this hypothesis, with higher measures being associated with worse symptom severity and functioning in early stages and with lower symptom severity and better functioning in later stages.

Network Association of Biochemical and Inflammatory Abnormalities With Psychiatric Symptoms in First-Episode Schizophrenia Patients

BACKGROUND

Cardiovascular disease (CVD) risk factors such as dyslipidemia and systemic aberrant inflammatory processes may occur in patients with psychotic disorders, which may cause increased mortality. The interplay between immune and metabolic markers and its contribution to the clinical symptoms of schizophrenia (SCZ) remain unclear. This study aimed to examine the association of a series of inflammatory factors, plasma biochemical indicators, and SCZ clinical symptomatology with the severity of SCZ symptoms.

METHODS

A total of 115 participants, including 79 first-episode drug-naïve patients with SCZ and 36 healthy controls, were enrolled in this study. Semi-structured interviews were used to collect sociodemographic data, family history of SCZ, and medical and psychiatric history. The Brief Psychiatric Rating Scale (BPRS) and the Positive and Negative Syndrome Scale (PANSS) were administered by a clinical psychiatrist to evaluate the symptom severity of patients with SCZ. Plasma inflammatory cytokines were measured by a fully automated electrochemiluminescent immunoassay (Meso Scale Discovery).

RESULTS

Blood routine, biochemical, and inflammation cytokine test results showed that the levels of white blood cell count, neutrophil count, natrium, CRP, IL-8, IL-6, IL-13, and IL-16 significantly increased in the case group than in the healthy controls (p < 0.05), whereas levels of red blood cell count, hemoglobin concentration, mean corpuscular hemoglobin concentration, total protein, albumin, total bile acid, high-density lipoprotein (HDL), apolipoprotein A1, blood urea nitrogen, kalium and IL-15 were lower than in the healthy controls (p < 0.05). Correlation network analysis results shown that the natrium, HDL and red blood cell count were the top 3 factors closely to with BPRS and PANSS related clinical symptoms among of correlation network (degree = 4). ROC curve analysis explored the IL-16, IL-8, IL-13, IL-15, natrium, and HDL had highly sensitivity and specificity to the predictive validity and effectiveness for SCZ symptoms.

CONCLUSION

Our study revealed a complex interactive network correlation among the cardiovascular risk factors, biological immunity profiles, and psychotic symptoms in first-episode patients. Abnormal inflammatory factors and CVD risk factors had high sensitivity and specificity for predicting SCZ symptoms. Generally, our study provided novel information on the immune-related mechanisms involved in early CVD risk in patients with psychotic disorders.

IL-17 and TNF-β: Predictive biomarkers for transition to psychosis in ultra-high risk individuals

BACKGROUND

Dysregulation of immunity, such as levels of inflammatory factors, has been regarded as a sign of schizophrenia. Changes in cytokine levels are not only described in the early onset of disease, but also observed in ultra-high risk (UHR) individuals. This study aimed to investigate the potential of cytokines as biomarkers for psychotic disorders and in individuals at UHR of developing a psychotic disorder in the future.

METHODS

The Luminex liquid chip technology was used to detect the concentrations of Interferon-gamma (INF-γ), Interleukin (IL)-2, Interleukin (IL)-4, Interleukin (IL)-6, Interleukin (IL)-17, Interleukin-1beta (IL-1β), and Tumor Necrosis Factor-beta (TNF-β) in the plasma of all subjects. Meanwhile, the plasma level of Tumor Necrosis Factor-Alpha (TNF-α) was measured with the enzyme-linked immunosorbent assay (ELISA) kits. Then, the levels of these cytokines were compared among patients with Drug-naïve first-episode schizophrenia (FES; n = 40), UHR population (UHR; n = 49), and healthy controls (HCs; n = 30). Baseline cytokine levels were compared among UHR individuals who later transitioned (UHR-T; n = 14), those who did not transition (UHR-NT; n = 35), and HCs (n = 30).

RESULTS

Our analysis results showed that IL-1β levels were significantly higher in UHR group than HC group (p = 0.015). Meanwhile, TNF-α concentration was significantly increased in FES group compared with HC group (p = 0.027). IL-17 (p = 0.04) and TNF-β (p = 0.008) levels were significantly higher in UHR-T group compared with UHR-NT group.

CONCLUSION

In conclusion, our findings suggest that the immuno-inflammatory activation level is increased in the early stage of psychosis before psychotic conversion and the Drug-naïve FES. IL-1β and TNF-α are the representatives of the specific biomarkers for UHR and FES, respectively. IL-17 and TNF-β may be the potential selective predictive biomarkers for future transition in UHR individuals.

Multivariate relationships between peripheral inflammatory marker subtypes and cognitive and brain structural measures in psychosis

Elevations in peripheral inflammatory markers have been reported in patients with psychosis. Whether this represents an inflammatory process defined by individual or subgroups of markers is unclear. Further, relationships between peripheral inflammatory marker elevations and brain structure, cognition, and clinical features of psychosis remain unclear. We hypothesized that a pattern of plasma inflammatory markers, and an inflammatory subtype established from this pattern, would be elevated across the psychosis spectrum and associated with cognition and brain structural alterations. Clinically stable psychosis probands (Schizophrenia spectrum, n = 79; Psychotic Bipolar disorder, n = 61) and matched healthy controls (HC, n = 60) were assessed for 15 peripheral inflammatory markers, cortical thickness, subcortical volume, cognition, and symptoms. A combination of unsupervised exploratory factor analysis and hierarchical clustering was used to identify inflammation subtypes. Levels of IL6, TNFα, VEGF, and CRP were significantly higher in psychosis probands compared to HCs, and there were marker-specific differences when comparing diagnostic groups. Individual and/or inflammatory marker patterns were associated with neuroimaging, cognition, and symptom measures. A higher inflammation subgroup was defined by elevations in a group of 7 markers in 36% of Probands and 20% of HCs. Probands in the elevated inflammatory marker group performed significantly worse on cognitive measures of visuo-spatial working memory and response inhibition, displayed elevated hippocampal, amygdala, putamen and thalamus volumes, and evidence of gray matter thickening compared to the proband group with low inflammatory marker levels. These findings specify the nature of peripheral inflammatory marker alterations in psychotic disorders and establish clinical, neurocognitive and neuroanatomic associations with increased inflammatory activation in psychosis. The identification of a specific subgroup of patients with inflammatory alteration provides a potential means for targeting treatment with anti-inflammatory medications.

Involvement of vascular endothelial growth factor in schizophrenia

Vascular endothelial growth factor (VEGF), which acts as an angiogenic and neurotrophic factor, is involved the regulation of cerebral blood volume and flow in Schizophrenia (SCZ). Several evidence indicates that modification of brain blood circulation due to alterations in the VEGF system affects cognitive performance and brain function in patients with SCZ. The aim of this study is: 1) To analyze the literature data concerning the role of VEGF in modulating the angiogenic response in SCZ. These data are controversial because some studies found elevated VEGF serum levels of VEGF in patients with SCZ, whereas others demonstrated no significant differences between SCZ patients and controls. 2)To analyze the role of VEGF as a predictive factor on the effects of antipsychotics agents used in the treatment of SCZ. In this context, high VEGF levels, associated to better responses to antipsychotics, might be predictive of the use of first generation antipsycotic drugs, whereas low VEGF levels, expression of resistance to therapy, might be predictive for the use of second generation antipsycotic drugs.

Immune-inflammatory markers and psychosis risk: A systematic review and meta-analysis

Subclinical inflammation has been associated with psychosis; however, it remains unknown whether this phenomenon appears also in the premorbid phase. Therefore, we performed a systematic review and meta-analysis of studies comparing peripheral blood levels of C-reactive protein (CRP) and cytokines between individuals at risk of psychosis and controls. Moreover, we tested the hypothesis that the levels of these markers may be different in high-risk converters versus non-converters. Two independent reviewers searched electronic databases until Dec 16th, 2020. After reviewing publication records, 16 studies (548 high-risk individuals and 559 controls) were included. Random-effects meta-analyses with Hedges' g as the effect size estimate were performed. Individuals at clinical risk of psychosis had significantly higher levels of interleukin-6 (IL-6) compared to controls (g = 0.33, 95%CI: 0.06-0.60, p = 0.018). Heterogeneity was not significant in this subgroup analysis. Changes in the levels of IL-6 in subjects at familial risk of psychosis were not significant (g = 0.04, 95%CI: -0.24 to 0.31, p = 0.798). The use of antidepressants was associated with significantly higher levels of IL-6 in high-risk individuals (Beta = 1.56, 95%CI: 0.60-2.53, p = 0.001). No significant differences in the levels of immune-inflammatory markers were found between high-risk converters and non-converters. Our findings suggest that individuals at clinical risk of psychosis show subclinical inflammation in terms of elevated IL-6 levels. This phenomenon might be related to the use of antidepressants. The present meta-analysis does not support the usefulness of single immune-inflammatory markers in predicting transition to psychosis.

The Candidate Schizophrenia Risk Gene Tmem108 Regulates Glucose Metabolism Homeostasis

BACKGROUND

Schizophrenia (SCZ) is a severe psychiatric disease affected by genetic factors and environmental contributors, and premorbid abnormality of glucose metabolism is one of the SCZ characteristics supposed to contribute to the disease's pathological process. Transmembrane protein 108 (Tmem108) is a susceptible gene associated with multiple psychiatric diseases, including SCZ. Moreover, Tmem108 mutant mice exhibit SCZ-like behaviors in the measurement of sensorimotor gating. However, it is unknown whether Tmem108 regulates glucose metabolism homeostasis while it involves SCZ pathophysiological process.

RESULTS

In this research, we found that Tmem108 mutant mice exhibited glucose intolerance, insulin resistance, and disturbed metabolic homeostasis. Food and oxygen consumption decreased, and urine production increased, accompanied by weak fatigue resistance in the mutant mice. Simultaneously, the glucose metabolic pathway was enhanced, and lipid metabolism decreased in the mutant mice, consistent with the elevated respiratory exchange ratio (RER). Furthermore, metformin attenuated plasma glucose levels and improved sensorimotor gating in Tmem108 mutant mice.

CONCLUSIONS

Hyperglycemia occurs more often in SCZ patients than in control, implying that these two diseases share common biological mechanisms, here we demonstrate that the Tmem108 mutant may represent such a comorbid mechanism.

Meta-analysis of cytokine and C-reactive protein levels in high-risk psychosis

OBJECTIVE

Schizophrenia is associated with aberrant blood cytokine and C-reactive protein (CRP) levels. However, less is known about alterations in these markers prior to the onset of psychosis. We performed a meta-analysis of blood cytokines and CRP in subjects at high-risk for psychosis.

METHOD

We identified articles by systematic searches of PubMed, PsycINFO, and Web of Science databases, and the reference lists of identified studies. Eight studies met the inclusion criteria, including seven studies of high-risk psychosis versus controls, and four studies of high-risk subjects who converted to a psychotic disorder versus non-converters.

RESULTS

Blood IL-6 levels were significantly higher (SMD = 0.31, 95% CI 0.02-0.59, p = 0.04) and blood IL-1β levels were significantly lower (SMD = -0.66, 95% CI -1.27 to -0.05, p = 0.05) in subjects at high-risk for psychosis versus controls. Between-study heterogeneity was not significant for either IL-1β or IL-6, and there was no evidence of publication bias. There was a non-significant trend for higher blood IL-12 levels in converters versus non-converters (SMD = 0.86, 95% CI -0.06-1.79, p = 0.07).

CONCLUSION

We found limited evidence for blood cytokine and CRP alterations in subjects at high-risk for psychosis. Our findings should be interpreted with caution in light of a small number of studies, cumulative sample size, and heterogeneity of high-risk criteria, but warrant investigation in larger samples. This includes studies of subjects at high-risk of developing psychosis and controls, as well as the potential of inflammation as a predictor of conversion to psychosis. These findings have important potential implications for our understanding of the pathophysiology of schizophrenia.

Vascular endothelial growth factor in major depressive disorder, schizophrenia, and bipolar disorder: A network meta-analysis

The peripheral levels of vascular endothelial growth factor (VEGF) have been studied in major psychiatric diseases compared with healthy controls (HCs), but the results were inconsistent. Moreover, few studies have compared VEGF levels between these psychiatric diseases. The aim of the present study was to compare blood VEGF levels in major depressive disorder (MDD), schizophrenia (SCZ), bipolar disorder either in a manic episode, a depressive episode, or a euthymic state, and HC. We supposed that VEGF levels may be elevated in some of these diseases as a potential biomarker. In this study, forty-four studies with 6343 participants were included, and network meta-analysis was used to synthesize evidence from both direct and indirect comparisons. The main analysis showed that no significant differences were found between these groups. Subgroup analysis found that patients with MDD may have higher blood VEGF levels than patients with SCZ when the levels were measured through ELISA, and VEGF levels were increased in medication-treated MDD patients compared with HCs. Taken together, blood VEGF levels may be unaltered in these psychiatric disorders, while detection of VEGF in blood by ELISA may a feasible way to distinguish MDD and SCZ. Further replicated studies with larger samples are needed.

The Role of Brain Microvascular Endothelial Cell and Blood-Brain Barrier Dysfunction in Schizophrenia

BACKGROUND

Despite decades of research, little clarity exists regarding pathogenic mechanisms related to schizophrenia. Investigations on the disease biology of schizophrenia have primarily focused on neuronal alterations. However, there is substantial evidence pointing to a significant role for the brain's microvasculature in mediating neuroinflammation in schizophrenia.

SUMMARY

Brain microvascular endothelial cells (BMEC) are a central element of the microvasculature that forms the blood-brain barrier (BBB) and shields the brain against toxins and immune cells via paracellular, transcellular, transporter, and extracellular matrix proteins. While evidence for BBB dysfunction exists in brain disorders, including schizophrenia, it is not known if BMEC themselves are functionally compromised and lead to BBB dysfunction.

KEY MESSAGES

Genome-wide association studies, postmortem investigations, and gene expression analyses have provided some insights into the role of the BBB in schizophrenia pathophysiology. However, there is a significant gap in our understanding of the role that BMEC play in BBB dysfunction. Recent advances differentiating human BMEC from induced pluripotent stem cells (iPSC) provide new avenues to examine the role of BMEC in BBB dysfunction in schizophrenia.

Altered structural connectivity and cytokine levels in Schizophrenia and Genetic high-risk individuals: Associations with disease states and vulnerability

BACKGROUND

Alterations of white matter (WM) integrity have been observed in both schizophrenia (SZ) and individuals at genetic high risk for SZ (GHR-SZ); however, the molecular mechanisms underlying WM disruption remain unclear. Cytokines are chemical messengers of the immune system that are closely related to inflammation and neurogenesis in the brain. This study aimed to identify abnormalities in WM integrity, cytokine levels, and their association in SZ and GHR-SZ.

METHODS

A total of 355 participants (126 with SZ, 99 GHR-SZ, and 130 healthy controls [HCs]) were recruited. All participants underwent diffusion tensor imaging and blood samples were obtained from 113 participants within 24 h of imaging.

RESULTS

In SZ, there was decreased fractional anisotropy(FA) in the genu and body of the corpus callosum (GCC/BCC), anterior corona radiata, anterior and posterior limbs of the internal capsule (ALIC/PLIC), superior fronto-occipital fasciculus, external capsule, and fornix, and elevated IL-6 levels. In both SZ and GHR-SZ, decreased FA in the splenium of the corpus callosum (SCC), posterior corona radiate (PCR), and posterior thalamic radiation (PTR) was observed, and elevated leptin levels were present. Additionally, the IL-6 levels were negatively correlated with FA in the GCC and ALIC in SZ, and leptin levels were negatively correlated with the SCC, PCR, and PTR in SZ and GHR-SZ.

CONCLUSIONS

Abnormal WM integrity in SZ may reflect the state of disease and is associated with increased IL-6 levels. In addition, these leptin-associated WM integrity abnormalities in both SZ and GHR-SZ may reflect a genetic vulnerability to SZ.

S-Adenosine Methionine (SAMe) and Valproic Acid (VPA) as Epigenetic Modulators: Special Emphasis on their Interactions Affecting Nervous Tissue during Pregnancy

S-adenosylmethionine (SAMe) is involved in many transmethylation reactions in most living organisms and is also required in the synthesis of several substances such as monoamine neurotransmitters and the N-methyl-D-aspartate (NMDA) receptor. Due to its important role as an epigenetic modulator, we discuss in some length the process of DNA methylation and demethylation and the critical periods of epigenetic modifications in the embryo, fetus, and thereafter. We also discuss the effects of SAMe deficiency and the attempts to use SAMe for therapeutic purposes such as the treatment of major depressive disorder, Alzheimer disease, and other neuropsychiatric disorders. SAMe is an approved food additive and as such is also used during pregnancy. Yet, there seems to scanty data on the possible effects of SAMe on the developing embryo and fetus. Valproic acid (VPA) is a well-tolerated and effective antiepileptic drug that is also used as a mood stabilizer. Due to its high teratogenicity, it is contraindicated in pregnancy. A major mechanism of its action is histone deacetylase inhibition, and therefore, it acts as an epigenetic modulator, mainly on the brain. This prompted clinical trials using VPA for additional indications i.e., treating degenerative brain disease such as Alzheimer disease, dementia, HIV, and even cancer. Therefore, we discuss the possible effects of VPA and SAMe on the conceptus and early postnatally, during periods of susceptibility to epigenetic modifications. VPA is also used as an inducer of autistic-like behavior in rodents and was found by us to modify gene expression when administered during the first postnatal week but not when administered to the pregnant dams on day 12 of gestation. In contrast, SAMe modified gene expression when administered on day 12 of pregnancy but not postnatally. If administered together, VPA prevented the changes in gene expression induced by prenatal SAMe administration, and SAMe prevented the gene expression changes and autistic-like behavior induced by early postnatal VPA. It is concluded that both VPA and SAMe are powerful epigenetic modifiers with antagonistic actions on the brain that will probably be used in the future more extensively for the treatment of a variety of epigenetic diseases of the nervous system.

Prenatal S-Adenosine Methionine (SAMe) Induces Changes in Gene Expression in the Brain of Newborn Mice That Are Prevented by Co-Administration of Valproic Acid (VPA)

In previous studies, we produced changes in gene expression in the brain of mice by early postnatal administration of valproic acid (VPA), with distinct differences between genders. The addition of S-adenosine methionine (SAMe) normalized the expression of most genes in both genders, while SAMe alone induced no changes. We treated pregnant dams with a single injection of VPA on day 12.5 of gestation, or with SAMe during gestational days 12–14, or by a combination of VPA and SAMe. In the frontal half of the brain, we studied the expression of 770 genes of the pathways involved in neurophysiology and neuropathology using the NanoString nCounter method. SAMe, but not VPA, induced statistically significant changes in the expression of many genes, with differences between genders. The expression of 112 genes was changed in both sexes, and another 170 genes were changed only in females and 31 only in males. About 30% of the genes were changed by more than 50%. One of the most important pathways changed by SAMe in both sexes was the VEGF (vascular endothelial growth factor) pathway. Pretreatment with VPA prevented almost all the changes in gene expression induced by SAMe. We conclude that large doses of SAMe, if administered prenatally, may induce significant epigenetic changes in the offspring. Hence, SAMe and possibly other methyl donors may be epigenetic teratogens.

Overdispersed gene expression in schizophrenia

Schizophrenia (SCZ) is a severe, highly heterogeneous psychiatric disorder with varied clinical presentations. The polygenic genetic architecture of SCZ makes identification of causal variants a daunting task. Gene expression analyses hold the promise of revealing connections between dysregulated transcription and underlying variants in SCZ. However, the most commonly used differential expression analysis often assumes grouped samples are from homogeneous populations and thus cannot be used to detect expression variance differences between samples. Here, we applied the test for equality of variances to normalized expression data, generated by the CommonMind Consortium (CMC), from brains of 212 SCZ and 214 unaffected control (CTL) samples. We identified 87 genes, including VEGFA (vascular endothelial growth factor) and BDNF (brain-derived neurotrophic factor), that showed a significantly higher expression variance among SCZ samples than CTL samples. In contrast, only one gene showed the opposite pattern. To extend our analysis to gene sets, we proposed a Mahalanobis distance-based test for multivariate homogeneity of group dispersions, with which we identified 110 gene sets with a significantly higher expression variability in SCZ, including sets of genes encoding phosphatidylinositol 3-kinase (PI3K) complex and several others involved in cerebellar cortex morphogenesis, neuromuscular junction development, and cerebellar Purkinje cell layer development. Taken together, our results suggest that SCZ brains are characterized by overdispersed gene expression-overall gene expression variability among SCZ samples is significantly higher than that among CTL samples. Our study showcases the application of variability-centric analyses in SCZ research.

The psychosis risk timeline: can we improve our preventive strategies? Part 3: primary common pathways and preventive strategies

Psychosis is a recognised feature of several psychiatric disorders and it causes patients significant distress and morbidity. It is therefore important to keep knowledge of possible risk factors for psychosis up to date and to have an overview model on which further learning can be structured. This article concludes a three-part series. It gives a review of evidence regarding common pathways by which many risk factors come together to influence the development of psychosis and finalises our suggested overview model, a psychosis risk timeline. The three primary pathways considered are based on the major themes identified in this narrative review of recent literature and they focus on neurological, neurochemical and inflammatory changes. We link each back to the factors discussed in the first and second parts of this series that alter psychosis risk through different mechanisms and at different stages throughout life. We then consider and summarise key aspects of this complex topic with the aim of providing current and future clinicians with a model on which to build their knowledge and begin to access and understand current psychosis research and implications for future preventive work.

LEARNING OBJECTIVES

After reading this article you will be able to: •

DECLARATION OF INTEREST

None.

Increased risk of type 2 diabetes among the siblings of patients with schizophrenia

BACKGROUND

Research suggests an association between metabolic disorders, such as type 2 diabetes mellitus (T2DM), and schizophrenia. However, the risk of metabolic disorders in the unaffected siblings of patients with schizophrenia remains unclear.

METHODS

Using the Taiwan National Health Insurance Research Database, 3135 unaffected siblings of schizophrenia probands and 12,540 age-/sex-matched control subjects were included and followed up to the end of 2011. Individuals who developed metabolic disorders during the follow-up period were identified.

RESULTS

The unaffected siblings of schizophrenia probands had a higher prevalence of T2DM (3.4% vs. 2.6%, p = 0.010) than the controls. Logistic regression analyses with the adjustment of demographic data revealed that the unaffected siblings of patients with schizophrenia were more likely to develop T2DM (odds ratio [OR]: 1.39, 95% confidence interval [CI]: 1.10-1.75) later in life compared with the control group. Moreover, only female siblings of schizophrenia probands had an increased risk of hypertension (OR: 1.47, 95% CI: 1.07-2.01) during the follow-up compared with the controls.DiscussionThe unaffected siblings, especially sisters, of schizophrenia probands had a higher prevalence of T2DM and hypertension compared with the controls. Our study revealed a familial link between schizophrenia and T2DM in a large sample. Additional studies are required to investigate the shared pathophysiology of schizophrenia and T2DM.

Association of Choroid Plexus Enlargement With Cognitive, Inflammatory, and Structural Phenotypes Across the Psychosis Spectrum

OBJECTIVE

The choroid plexus is an important physiological barrier and produces CSF and neurotrophic, angiogenic, and inflammatory factors involved in brain development. Choroid plexus abnormalities have been implicated in both schizophrenia and bipolar disorder. A previous choroid plexus transcriptomic analysis of schizophrenia identified an upregulation of immune and inflammatory genes that correlated with peripheral inflammatory markers. The purpose of this study was to examine choroid plexus volume in probands across the psychosis spectrum and in their first-degree and axis II cluster A relatives, as well as choroid plexus familiality and choroid plexus covariance with clinical, cognitive, brain, and peripheral marker measures.

METHODS

Choroid plexus volume was quantified (using FreeSurfer) in psychosis probands, their first-degree and axis II cluster A relatives, and healthy control subjects, organized by DSM-IV-TR diagnosis. Analyte, structural connectivity, and genotype data were collected from a subset of study subjects.

RESULTS

Choroid plexus volume was significantly larger in probands compared with first-degree relatives or healthy control subjects; first-degree relatives had intermediate enlargement compared with healthy control subjects; and total choroid plexus volume was significantly heritable. Larger volume was associated with worse cognition, smaller total gray matter and amygdala volume, larger lateral ventricle volume, and lower structural connectivity in probands. Associations between larger volume and higher levels of interleukin 6 in probands was also observed.

CONCLUSIONS

These findings suggest the involvement of the choroid plexus across the psychosis spectrum with a potential pathophysiological mechanism involving the neuroimmune axis, which functions in maintaining brain homeostasis and interacting with the peripheral immune and inflammatory system. The choroid plexus may be an important target in future research.

Risk of cardiometabolic diseases among siblings of patients with bipolar disorder

BACKGROUND

Cardiometabolic diseases are suggested to be associated with bipolar disorder. However, the risk of metabolic disorders in unaffected siblings of patients with bipolar disorder remains unclear.

METHODS

From the Taiwan National Health Insurance Research Database, 7,225 unaffected siblings of bipolar probands and 28,900 age-/sex-/income-/residence-matched control individuals were included and followed until the end of 2011. Individuals who developed metabolic disorders during the follow-up period were identified.

RESULTS

The unaffected siblings of bipolar probands had a higher prevalence of dyslipidemia (5.4% vs. 4.5%, p = 0.001), younger age at diagnosis of type 2 diabetes mellitus (34.81 vs. 37.22, p = 0.024), and higher prevalence of any stroke (1.5% vs. 1.1%, p = 0.007) than the controls. Moreover, only male siblings of bipolar probands had an increased risk of dyslipidemia (odds ratio [OR]: 1.28, 95% confidence interval [CI]: 1.10-1.48) and higher rates of any stroke (OR: 1.38, 95% CI: 1.02-1.85) and ischemic stroke (OR: 2.43, 95% CI: 1.60-3.70) during the follow-up compared with the controls.

DISCUSSION

Unaffected siblings of bipolar patients, particularly brothers, had a higher prevalence of dyslipidemia and ischemic stroke compared with the controls. The result suggests the familial association between cardiometabolic diseases and bipolar disorder. Further research may be necessary to identify this shared etiology between the disorders.

Preventing discrimination based on psychiatric risk biomarkers

Recent studies have identified genomic and nongenomic psychiatric risk biomarkers (PRBs; e.g., genomic variants, blood analytes, gray matter volume). PRBs may soon become a powerful tool for improving psychiatric care and prevention. PRB research and its translation to clinical care, however, may prove to be a double-edged sword. Mental health stigma and discrimination are already widespread, and data caution that biological explanations of psychiatric disorders can exacerbate these stigmatizing attitudes, increasing the desire for social distance and heightening the perceived dangerousness of the patient. As a reaction to the Human Genome Project and historical concerns about eugenics, the international community mobilized to establish legislation to prevent genomic discrimination. But in most countries, these laws are limited to few contexts (e.g., employment, health insurance), and very few countries protect against discrimination based on nongenomic risk biomarkers. Like genomic PRBs, nongenomic PRBs provide information regarding risk for stigmatized psychiatric disorders and have similar-and in some cases greater-predictive value. Numerous large-scale neuroscience and neurogenomics projects are advancing the identification and translation of PRBs. The prospect of PRB-based stigma however, threatens to undermine the potential benefits of this research. Unbridaled by nonexistent or limited PRB anti-discrimination protections, the threat of PRB-based stigma and discrimination may lead many to forego PRB testing, even if shown to have clinical utility. To maximize the clinical and social benefits of PRB-based technologies, educational campaigns should address mental health and PRB stigma, and lawmakers should carefully consider expanding legislation that prohibits PRB-based discrimination.

Peripheral Biomarkers for First-Episode Psychosis-Opportunities from the Neuroinflammatory Hypothesis of Schizophrenia

OBJECTIVE

Schizophrenia is a disabling disorder of unknown aetiology, lacking definite diagnostic method and cure. A reliable biological marker of schizophrenia is highly demanded, for which traceable immune mediators in blood could be promising candidates. We aimed to gather the best findings of neuroinflammatory markers for first-episode psychosis (FEP).

METHODS

We performed an extensive narrative review of online literature on inflammation-related markers found in human FEP patients only.

RESULTS

Changes to cytokine levels have been increasingly reported in schizophrenia. The peripheral levels of IL-1 (or its receptor antagonist), soluble IL-2 receptor, IL-4, IL-6, IL-8, and TNF-α have been frequently reported as increased in FEP, in a suggestive continuum from high-risk stages for psychosis. Microglia and astrocytes establish the link between this immune signalling and the synthesis of noxious tryptophan catabolism products, that cause structural damage and directly hamper normal neurotransmission. Amongst these, only 3-hydroxykynurenine has been consistently described in the blood of FEP patients.

CONCLUSION

Peripheral molecules stemming from brain inflammation might provide insightful biomarkers of schizophrenia, as early as FEP or even prodromal phases, although more time- and clinically-adjusted studies are essential for their validation.

Association of baseline inflammatory markers and the development of negative symptoms in individuals at clinical high risk for psychosis

Negative symptoms are common in individuals at clinical high-risk (CHR) for psychosis and are associated with worse functional outcomes. Inflammation may be one mechanism underlying negative symptoms. Inflammatory markers are altered in individuals at CHR and are associated with negative symptoms in patients with schizophrenia. We thus hypothesized that baseline inflammatory markers would predict the development of negative symptoms in individuals at CHR for psychosis. Thirty seven individuals from the North American Prodromal Longitudinal Study who met CHR criteria were included in the study. Inflammatory cytokines, including interferon (IFN)-λ, Interleukin (IL)-1β, IL-1 receptor antagonist (IL-1RA), IL-4, IL-6, IL-8, IL-10, and tumor necrosis factor (TNF) were measured at baseline. Negative symptoms as measured by the Scale of Prodromal Symptoms, were measured at baseline and six and twelve months. Associations between inflammatory markers and the trajectory of negative symptoms (slope) over the first year of follow-up, were assessed using linear regression models controlling for age, sex, race and depressive symptom severity (as assessed by the Calgary Depression Scale for Schizophrenia). Baseline TNF (beta = 0.361, p = 0.007) and IL-6 (beta = -0.306, p = 0.026) predicted negative symptoms slopes, along with depressive symptom severity at baseline (beta = -0.596, p = 0.000). These findings demonstrate that inflammatory cytokines may underlie the development of negative symptoms in some individuals at CHR for psychosis. TNF predicted the development of negative symptoms independent of baseline depression. Given the heterogeneity of the CHR population, the comorbidity of negative symptoms and depression in this population, and the particular challenges in treating negative symptoms, immune markers could represent potential biomarkers that underlie the development of negative symptoms, representing a potential treatment target.

Are the Cognitive Alterations Present in Children Born From Preeclamptic Pregnancies the Result of Impaired Angiogenesis? Focus on the Potential Role of the VEGF Family

Evidence from clinical studies has proposed that children born from preeclamptic women have a higher risk of suffering neurological, psychological, or behavioral alterations. However, to date, the mechanisms behind these outcomes are poorly understood. Here, we speculate that the neurodevelopmental alterations in the children of preeclamptic pregnancies result from impaired angiogenesis. The pro-angiogenic factors vascular endothelial growth factor (VEGF) and placental growth factor (PlGF) are key regulators of both vascular and neurological development, and it has been widely demonstrated that umbilical blood of preeclamptic pregnancies contains high levels of soluble VEGF receptor type 1 (sFlt-1), a decoy receptor of VEGF. As a consequence, this anti-angiogenic state could lead to long-lasting neurological outcomes. In this non-systematic review, we propose that alterations in the circulating concentrations of VEGF, PlGF, and sFlt-1 in preeclamptic pregnancies will affect both fetal cerebrovascular function and neurodevelopment, which in turn may cause cognitive alterations in post-natal life.

VEGFA GENE variation influences hallucinations and frontotemporal morphology in psychotic disorders: a B-SNIP study

Vascular endothelial growth factor A (VEGFA) dysfunction may contribute to a number of pathological processes that characterize psychotic disorders. However, the influence of VEGFA gene variants on clinical and neuroimaging phenotypes in psychotic disorders has yet to be shown. In the present study, we examined whether different VEGFA gene variants influence psychosis risk, symptom severity, cognition, and brain volume. The study group included 480 probands (Bipolar I disorder with psychosis, n = 205; Schizoaffective disorder, n = 112; Schizophrenia, n = 163) and 126 healthy controls that were recruited across six sites in the B-SNIP consortium. VEGFA variants identified for analysis (rs699947, rs833070, and rs2146323) were quantified via SNP chip array. We assessed symptoms and cognition using standardized clinical and neuropsychological batteries. The dorsolateral prefrontal cortex (DLPFC), medial temporal lobe, and hippocampal volumes were quantified using FreeSurfer. In our sample, VEGFA rs2146323 A- carriers showed reduced odds of being a proband (p = 0.037, OR = 0.65, 95% CI = 0.43-0.98) compared to noncarriers, but not for rs699947 or rs833070. In probands, rs2146323 A- carriers demonstrated fewer hallucinations (p = 0.035, Cohen's d = 0.194), as well as significantly greater DLPFC (p < 0.05, Cohen's d = -0.21) and parahippocampal volumes (p < 0.01, Cohen's d = -0.27). No clinical or neuroimaging associations were identified for rs699947 or rs833070. In general, we found that the three SNPs exhibited several significant negative relationships between psychosis symptoms and brain structure. In the probands and control groups, positive relationships were identified between several cognitive and brain volume measures. The findings suggest VEGFA effects in the DLPFC and hippocampus found in animals may also extend to humans. VEGFA variations may have important implications in identifying dimensional moderators of function that could be targeted through VEGFA-mediated interventions.

Vascular endothelial growth factor in patients with schizophrenia: A systematic review and meta-analysis

BACKGROUND

Accumulating evidence indicates that schizophrenia might be accompanied by abnormal vascularization. Vascular endothelial growth factor (VEGF) is one of key molecules involved in the development of vessels with vasodilatory activities.

OBJECTIVES

We aimed to perform a systematic review and meta-analysis of studies investigating serum or plasma levels of VEGF in patients with schizophrenia and first-episode psychosis (FEP).

METHODS

Electronic databases were searched from their inception until 18th Apr 2018. Meta-analysis was performed using random-effects models with Hedges' g as the effect size estimate. Quality assessment was performed using the Newcastle-Ottawa Scale.

RESULTS

We included 15 eligible studies, representing 982 patients and 791 healthy controls. Main analysis revealed no significant differences in VEGF levels between patients and controls (g = 0.10, 95%CI = -0.24-0.45, p = .553). Subgroup analysis demonstrated unaltered levels of VEGF in FEP patients (g = 0.03, 95%CI = -0.53-0.59, p = .911), including antipsychotic-naïve individuals (g = 0.34, 95%CI = -0.07-0.74, p = .103). However, the levels of VEGF were significantly higher in medicated multiple-episode schizophrenia (MES) patients (g = 0.45, 95%CI = 0.03-0.87, p = .036) compared to controls. Heterogeneity across studies was significant in the majority of analyses, except for the analysis of antipsychotic-naïve FEP patients. Tests of asymmetry were insignificant, indicating a lack of publication bias.

LIMITATIONS

Main limitations of our meta-analysis include inability to address medication effects exhaustively and relatively low number of studies in subgroup analyses.

CONCLUSIONS

Our results indicate elevated levels of VEGF in MES patients that are unaltered in FEP individuals. Longitudinal studies are required to disentangle whether elevated levels of VEGF in MES patients reflect illness progression, comorbid physical health impairments or appear due to medication effects.

Altered serum levels of vascular endothelial growth factor in first-episode drug-naïve and chronic medicated schizophrenia

There is much evidence of a relationship between alterations in the brain's regional cellular energy metabolism and blood flow in schizophrenic. Vascular endothelial growth factor (VEGF) plays a role in the pathogenesis of neuropsychiatric illnesses. So, we compared serum VEGF levels in drug-naïve first-episode psychotic (FEP) and chronically medicated schizophrenic to examine if a correlation existed between VEGF and psychopathological symptoms. The serum VEGF levels were assessed in 46 FEP patients, 47 chronic medicated patients and 50 healthy controls. Symptoms of schizophrenia were evaluated with the Positive and Negative Syndrome Scale (PANSS) and sandwich enzyme-linked immunosorbent assay (ELISA) was used to measure serum VEGF levels. VEGF levels were significantly lower in FEP patients compared to both chronically medicated schizophrenic patients and healthy controls, while VEGF levels in chronically medicated patients were markedly higher than in healthy controls. Furthermore, a significant correlation was detected between the levels and the PANSS negative subscale among patient groups. However, no significant correlation was observed between VEGF and clinical variables in patients. This study suggested that imbalanced neurotrophic factors may be associated with the onset of schizophrenia, but subsequent increased VEGF may be related to medication or other factors in disease progression.

A pilot study assessing retinal pathology in psychosis using optical coherence tomography: Choroidal and macular thickness

Mounting evidence supports a genetic-vascular-inflammatory etiology of schizophrenia. The retina provides an indirect assessment of inflammation and degeneration in the brain. In particular, the use of spectral domain optical coherence tomography (SD-OCT) has emerged as a powerful tool for examining single retinal nerve cell layers and the choroid, the vascular layer supplying the outer retina. In this study, choroidal and macular thicknesses were measured in six patients with psychosis with either schizophrenia or bipolar disorder, and in 18 age- and sex-matched healthy controls. Mean choroidal thickness was reduced in psychosis, though not significantly so. There was a statistically significant decrease in macular thickness in psychosis patients predominantly affecting the inner layers of the macula. Significant macular thinning may signal vascular, inflammatory, or degenerative processes that may also be occurring in the brain. This is one of the first studies to examine choroidal thickness in psychosis. Further studies are needed to determine whether the retinal changes in psychosis are correlated with microvascular dysfunction, neuroinflammation, and neurodegeneration.

Baseline serum vascular endothelial growth factor levels predict treatment response to antipsychotic medication in patients with schizophrenia

Vascular endothelial growth factor (VEGF) is implicated in angiogenesis, blood flow, and neuroplasticity, which have previously been shown to contribute to schizophrenia and the mechanisms of action of antipsychotic medication. The aim of the present study was to investigate whether baseline serum VEGF levels predict treatment responses to antipsychotic medication. Drug-free adults with schizophrenia were administered monotherapy with atypical antipsychotic drugs for 6 weeks. Participants' psychiatric symptoms were assessed using the positive and negative symptom scale (PANSS) before and after treatment. Blood samples for VEGF measurements were collected from 201 participants comprising 83 healthy controls and 118 patients (i.e. only on admission). Baseline VEGF levels in adults with schizophrenia were significantly lower than those in the control group (t = 3.656, df = 199, P < 0.001). In particular, pretreatment VEGF levels were significantly higher in patients responding to drug treatment at follow-up (≥ 50% reduction in initial PANSS total) (t = 4.743, df = 116, P < 0.001). The predictive power of serum VEGF levels was investigated using receiver operating characteristic curves. The area under the curve was 0.774 (95% confidence interval 0.688-0.846); for fixed specificity of 78.8%, the corresponding sensitivity was 63.5%. Results from this preliminary experiment suggest high baseline serum concentrations of VEGF may predict a better response to antipsychotic medications in adults with schizophrenia. Further studies using larger sample sizes are needed to verify the findings.

Immune and metabolic alterations in first episode psychosis (FEP) patients

The molecular underpinnings associated to first episode psychosis (FEP) remains to be elucidated, but compelling evidence supported an association of FEP with blood alterations in biomarkers related to immune system, growth factors and metabolism regulators. Many of these studies have not been already confirmed in larger samples or have not considered the FEP diagnostic subgroups. In order to identify biochemical signatures of FEP, the serum levels of the growth factors BDNF and VEGF, the immune regulators IL-1RA, IL-6, IL-10 and IL-17, RANTES/CCL5, MIP-1b/CCL4, IL-8 and the metabolic regulators C-peptide, ghrelin, GIP, GLP-1, glucagon, insulin, leptin, PAI-1, resistin and visfatin were analysed in 260 subjects collected in the GET UP project. The results indicated an increase of MIP-1b/CCL4, VEGF, IL-6 and PAI-1, while IL-17, ghrelin, glucagon and GLP-1 were decreased in the whole sample of FEP patients (p < 0.01 for all markers except for PAI-1 p < 0.05). No differences were evidenced for these markers among the diagnostic groups that constitute the FEP sample, whereas IL-8 is increased only in patients with a diagnosis of affective psychosis. The principal component analysis (PCA) and variable importance analysis (VIA) indicated that MIP-1b/CCL4, ghrelin, glucagon, VEGF and GLP-1 were the variables mostly altered in FEP patients. On the contrary, none of the analysed markers nor a combination of them can discriminate between FEP diagnostic subgroups. These data evidence a profile of immune and metabolic alterations in FEP patients, providing new information on the molecular mechanism associated to the psychosis onset for the development of preventive strategies and innovative treatment targets.

Can antibiotics cause a psychosis?: Case report and review of the literature

It is relatively unknown that some of the possible side effects of antibiotic treatment can be transient psychotic episodes and other encephalopathies such as seizure disorders. Since these are rare events, there have not been many studies about them, nor is there a clear understanding of the underlying basis for these symptoms. This phenomenon was recently brought to our attention by a patient whose case history is discussed here. For the past few years, he has been diagnosed at different times with schizophrenia, schizoaffective disorder, bipolar disorder with psychosis, temporal lobe epilepsy, and psychogenic nonepileptic seizures. He was seen by a neurologist and placed on carbamazepine, which by his admittance helped him tremendously. During this same time period, psychiatrists placed him on various antipsychotic medications as well. The patient researched many medical conditions and came to the conclusion that his symptoms are caused by a large dose of an "antibiotic" given to him on his first day of basic training for the military, the so called "peanut butter shot", although he has not been able to convince his physicians of this theory. Whether or not this patient has a chronic schizophrenia-like illness or an adverse reaction to antibiotics, this case is presented so that clinicians are aware that neurological and psychiatric side effects can occur as rare reactions to antibiotic therapy and that treatment with an anti-seizure drug concurrently used as a mood stabilizer may be warranted in such cases.

Neurotrophic and inflammatory markers in bipolar disorder: A prospective study

Altered neurotrophic signaling is thought to impair neuroplasticity in bipolar disorder (BD). Brain-derived neurotrophic factor (BDNF) is proposed as a neurotrophic marker in BD. However, the current evidence for its use in monitoring disease activity and illness progression is conflicting and an exploration of additional neurotrophic markers is needed. This prospective case-control study investigated mood-specific changes in potential neurotrophic markers and their association to inflammatory activity. Patients with BD were included during an acute mood episode, either depressive (n=35) or (hypo)manic (n=32). Fifty-nine patients (88%) and 29 healthy controls (97%) completed the study. Peripheral blood levels of BDNF, vascular endothelial growth factor A (VEGF), soluble fms-like tyrosine kinase-1 (sFlt-1) and tumor necrosis factor alpha (TNF-α) were measured at baseline and after 2 months. Biomarker levels in patients were compared to controls and correlated to HDRS-17 and YMRS total scores and the PANSS positive subscale scores. Linear mixed model analysis revealed no significant differences in neurotrophic markers between patients and controls. We found significantly increased TNF-α levels in patients and a subsequent normalization during euthymia. None of the biomarkers strongly correlated to mood symptom severity. Despite standardized methodological practices, BDNF and VEGF levels had a wide distribution range. We need a better understanding of methodological aspects influencing the analysis of neurotrophic factors to improve future research on markers for mood state monitoring and illness progression in BD.

Microvascular anomaly conditions in psychiatric disease. Schizophrenia - angiogenesis connection

Schizophrenia (SZ) is a severe mental disorder with unknown etiology and elusive neuropathological and neurobiological features have been a focus of many theoretical hypotheses and empirical studies. Current genetic and neurobiology information relevant to SZ implicates neuronal developmental and synaptic plasticity abnormalities, and neurotransmitter, microglial and oligodendrocytes dysfunction. Several recent theories have highlighted the neurovascular unit as a potential contributor to the pathophysiology of SZ. We explored the biological plausibility of a link between SZ and the neurovascular system by examining insights gained from genetic, neuroimaging and postmortem studies, which include gene expression and neuropathology analyses. We also reviewed information from animal models of cerebral angiogenesis in order to understand better the complex interplay between angiogenic and neurotrophic factors in development, vascular endothelium/blood brain barrier remodeling and maintenance, all of which contribute to sustaining adequate regional blood flow and safeguarding normal brain function. Microvascular and hemodynamic alterations in SZ highlight the importance of further research and reveal the neurovascular unit as a potential therapeutic target in SZ.

Microvascular anomaly conditions in psychiatric disease. Schizophrenia - angiogenesis connection

Schizophrenia (SZ) is a severe mental disorder with unknown etiology and elusive neuropathological and neurobiological features have been a focus of many theoretical hypotheses and empirical studies. Current genetic and neurobiology information relevant to SZ implicates neuronal developmental and synaptic plasticity abnormalities, and neurotransmitter, microglial and oligodendrocytes dysfunction. Several recent theories have highlighted the neurovascular unit as a potential contributor to the pathophysiology of SZ. We explored the biological plausibility of a link between SZ and the neurovascular system by examining insights gained from genetic, neuroimaging and postmortem studies, which include gene expression and neuropathology analyses. We also reviewed information from animal models of cerebral angiogenesis in order to understand better the complex interplay between angiogenic and neurotrophic factors in development, vascular endothelium/blood brain barrier remodeling and maintenance, all of which contribute to sustaining adequate regional blood flow and safeguarding normal brain function. Microvascular and hemodynamic alterations in SZ highlight the importance of further research and reveal the neurovascular unit as a potential therapeutic target in SZ.

Association of sFlt-1 and worsening psychopathology in relatives at high risk for psychosis: A longitudinal study

BACKGROUND

Angiogenic dysfunction and abnormalities in psychopathology and brain structure have been reported in schizophrenia, but their relationships are mostly unknown. We recently demonstrated that sFlt-1, anti-angiogenic factor, was significantly elevated in patients at familial high-risk for psychosis (FHR). We hypothesized that elevated sFlt-1 correlates with baseline and longitudinal changes in psychopathology, cognition, and brain structure.

METHODS

Plasma sFlt-1 in FHR (n=35) and HC (n=39) was obtained at baseline. Schizotypal, cognitive, soft neurologic signs, and structural brain imaging (1.5T T1-weighted MRI, FreeSurfer software) measures were obtained in both groups. Longitudinal clinical and brain structural measures were obtained in a subgroup of FHR patients. Baseline data analysis used correlations between sFlt-1 and clinical/imaging measures and adjusted for multiple corrections. Linear mixed-effects models described differences in trajectories between high sFlt-1 and low sFlt-1.

RESULTS

Baseline sFlt-1 was significantly correlated with soft neurologic signs (r=0.27, p=0.02) and right entorhinal volume (r=0.50, p=0.02), but not other baseline clinical/brain structural measures. Longitudinal examination of the FHR group (sFlt-1 high, n=14; sFlt-1 low, n=14) demonstrated that high sFlt-1 was significantly associated with worsening schizotypal symptoms (t=2.4, p=0.018). Reduced right hippocampal/parahippocampal volume/thickness trajectories were observed in high versus low sFlt-1 groups.

CONCLUSIONS

The findings from this FHR study demonstrate that peripheral markers of angiogenic dysfunction can predict longitudinal clinical and brain structural changes. Also, these findings further support the hypothesis of altered microvascular circulation in schizophrenia and those at risk.

Phenotyping Multiple Subsets of Immune Cells In Situ in Formalin-Fixed, Paraffin-Embedded Tissue Sections

Some somatic illnesses such as peripheral tumours can present with psychiatric symptoms. Many of these are characterized by changes in biomarkers related to the inflammation or immune response. Here, we describe a multispectral imaging protocol that can be used to phenotype immune and other cell types through simultaneous imaging of multiple proteins in sections of peripheral solid tumours and other tissues. This approach can also be used to assess the spatial organization of these cells within the tissue.