Association of common copy number variants at the glutathione S-transferase genes and rare novel genomic changes with schizophrenia

The importance of oxidative biomarkers in diagnosis, treatment, and monitoring schizophrenia patients

INTRODUCTION

The etiology of schizophrenia (SCZ), an incredibly complex disorder, remains multifaceted. Literature suggests the involvement of oxidative stress (OS) in the pathophysiology of SCZ.

OBJECTIVES

Determination of selected OS markers and brain-derived neurotrophic factor (BDNF) in patients with chronic SCZ and those in states predisposing to SCZ-first episode psychosis (FP) and ultra-high risk (UHR).

MATERIALS AND METHODS

Determination of OS markers and BDNF levels by spectrophotometric methods and ELISA in 150 individuals (116 patients diagnosed with SCZ or in a predisposed state, divided into four subgroups according to the type of disorder: deficit schizophrenia, non-deficit schizophrenia, FP, UHR). The control group included 34 healthy volunteers.

RESULTS

Lower activities of analyzed antioxidant enzymes and GSH and TAC concentrations were found in all individuals in the study group compared to controls (p < 0.001). BDNF concentration was also lower in all groups compared to controls except in the UHR subgroup (p = 0.01). Correlations were observed between BDNF, R-GSSG, GST, GPx activity, and disease duration (p < 0.02). A small effect of smoking on selected OS markers was also noted (rho<0.06, p < 0.03).

CONCLUSIONS

OS may play an important role in the pathophysiology of SCZ before developing the complete clinical pattern of the disorder. The redox imbalance manifests itself with such severity in individuals with SCZ and in a state predisposing to the development of this psychiatric disease that natural antioxidant systems become insufficient to compensate against it completely. The discussed OS biomarkers may support the SCZ diagnosis and predict its progression.

microRNA and the Post-Transcriptional Response to Oxidative Stress during Neuronal Differentiation: Implications for Neurodevelopmental and Psychiatric Disorders

Oxidative stress is one of the most important environmental exposures associated with psychiatric disorders, but the underlying molecular mechanisms remain to be elucidated. In a previous study, we observed a substantial alteration of the gene expression landscape in neuron-like cells that were differentiated from SH-SY5Y cells after or during exposure to oxidative stress, with a subset of dysregulated genes being enriched for neurodevelopmental processes. To further explore the regulatory mechanisms that might account for such profound perturbations, we have now applied small RNA-sequencing to investigate changes in the expression of miRNAs. These molecules are known to play crucial roles in brain development and response to stress through their capacity to suppress gene expression and influence complex biological networks. Through these analyses, we observed more than a hundred differentially expressed miRNAs, including 80 previously reported to be dysregulated in psychiatric disorders. The seven most influential miRNAs associated with pre-treatment exposure, including miR-138-5p, miR-96-5p, miR-34c-5p, miR-1287-5p, miR-497-5p, miR-195-5p, and miR-16-5p, supported by at least 10 negatively correlated mRNA connections, formed hubs in the interaction network with 134 genes enriched with neurobiological function, whereas in the co-treatment condition, miRNA-mRNA interaction pairs were enriched in cardiovascular and immunity-related disease ontologies. Interestingly, 12 differentially expressed miRNAs originated from the DLK1-DIO3 location, which encodes a schizophrenia-associated miRNA signature. Collectively, our findings suggest that early exposure to oxidative stress, before and during prenatal neuronal differentiation, might increase the risk of mental illnesses in adulthood by disturbing the expression of miRNAs that regulate neurodevelopmentally significant genes and networks.

Connecting Neurobiological Features with Interregional Dysconnectivity in Social-Cognitive Impairments of Schizophrenia

Schizophrenia (SZ) is a devastating psychiatric disorder affecting about 1% of the world's population. Social-cognitive impairments in SZ prevent positive social interactions and lead to progressive social withdrawal. The neurobiological underpinnings of social-cognitive symptoms remain poorly understood, which hinders the development of novel treatments. At the whole-brain level, an abnormal activation of social brain regions and interregional dysconnectivity within social-cognitive brain networks have been identified as major contributors to these symptoms. At the cellular and subcellular levels, an interplay between oxidative stress, neuroinflammation and N-methyl-D-aspartate receptor hypofunction is thought to underly SZ pathology. However, it is not clear how these molecular processes are linked with interregional dysconnectivity in the genesis of social-cognitive symptoms. Here, we aim to bridge the gap between macroscale (connectivity analyses) and microscale (molecular and cellular mechanistic) knowledge by proposing impaired myelination and the disinhibition of local microcircuits as possible causative biological pathways leading to dysconnectivity and abnormal activity of the social brain. Furthermore, we recommend electroencephalography as a promising translational technique that can foster pre-clinical drug development and discuss attractive drug targets for the treatment of social-cognitive symptoms in SZ.

Glutathione S-Transferase M1/T1 Polymorphisms and Schizophrenia Risk: A New Method for Quality Assessment and a Systematic Review

BACKGROUND

GST genes were reported to be involved in susceptibility to mental disorder. The results between deletions of GST genes and schizophrenia were inconclusive and confusing. Therefore, we performed this updated meta-analysis to outline the association using a new method for quality assessment.

METHODS

Sixteen reported studies were selected, and the overall OR and 95% CI were calculated and analyzed by Review Manager 5.4 and STATE 12. The Newcastle-Ottawa Quality Assessment Scale (NOS) for case-control studies was rewritten to evaluate the quality of published studies, as there was no "Exposure" in these studies and other factors should be suggested to assess the quality.

RESULTS

There was no significant association between deletions of GST genes and SZ risk (p > 0.05 in Random model). We also failed to find a significant relation between null genotypes and SZ risk in East Asian population. Based on further analysis of PCR methods, GSTM1 null was weakly associated with SZ risk in 8 studies using multiplex PCR (OR = 1.17, 95% CI = 1.00-1.37, p = 0.05), but GSTT1 null was a protective factor for SZ risk (OR = 0.73, 95% CI = 0.56-0.94, p = 0.02). When stratified by rewritten NOS stars and deductions, GSTM1 null was significantly associated with SZ risk in 9 studies with high quality (OR = 1.24, 95% CI = 1.08-1.43, p = 0.002), and in 10 studies with no deductions (OR = 1.20, 95% CI = 1.05-1.38, p = 0.007).

CONCLUSION

GSTM1 null genotype may be a genetic risk factor for SZ in studies using multiplex PCR and high-quality studies. However, GSTT1 null might be a protective factor. Besides, we provided a new method for quality assessment and it was useful and should be promoted in further analysis.

Oxidative Stress and Emergence of Psychosis

Treatment and prevention strategies for schizophrenia require knowledge about the mechanisms involved in the psychotic transition. Increasing evidence suggests a redox imbalance in schizophrenia patients. This narrative review presents an overview of the scientific literature regarding blood oxidative stress markers’ evolution in the early stages of psychosis and chronic patients. Studies investigating peripheral levels of oxidative stress in schizophrenia patients, first episode of psychosis or UHR individuals were considered. A total of 76 peer-reviewed articles published from 1991 to 2022 on PubMed and EMBASE were included. Schizophrenia patients present with increased levels of oxidative damage to lipids in the blood, and decreased levels of non-enzymatic antioxidants. Genetic studies provide evidence for altered antioxidant functions in patients. Antioxidant blood levels are decreased before psychosis onset and blood levels of oxidative stress correlate with symptoms severity in patients. Finally, adjunct treatment of antipsychotics with the antioxidant N-acetyl cysteine appears to be effective in schizophrenia patients. Further studies are required to assess its efficacy as a prevention strategy. Redox imbalance might contribute to the pathophysiology of emerging psychosis and could serve as a therapeutic target for preventive or adjunctive therapies, as well as biomarkers of disease progression.

Glutamatergic dysfunction is associated with phenotypes of VGF-overexpressing mice

VGF nerve growth factor inducible (VGF) is a neuropeptide precursor, which is induced by several neurotrophic factors, including nerve growth factor and brain-derived neurotrophic factor. Clinically, an upregulation of VGF levels has been reported in the cerebrospinal fluid and prefrontal cortex of patients with schizophrenia. In our previous study, mice overexpressing VGF exhibited schizophrenia-related behaviors. In the current study, we characterized the biochemical changes in the brains of VGF-overexpressing mice. Metabolomics analysis of neurotransmitters revealed that glutamic acid and N-acetyl-L-aspartic acid were increased in the striatum of VGF-overexpressing mice. Additionally, the present study revealed that MK-801, which causes the disturbance in glutamic acid metabolism, increased the expression level of VGF-derived peptide (NAPP129, named VGF20), and VGF-overexpressing mice had higher sensitivity to MK-801. These results suggest that VGF may modulate the regulation of glutamic acid levels and the degree of glutamic acid signaling.

Caught in vicious circles: a perspective on dynamic feed-forward loops driving oxidative stress in schizophrenia

A growing body of evidence has emerged demonstrating a pathological link between oxidative stress and schizophrenia. This evidence identifies oxidative stress as a convergence point or "central hub" for schizophrenia genetic and environmental risk factors. Here we review the existing experimental and translational research pinpointing the complex dynamics of oxidative stress mechanisms and their modulation in relation to schizophrenia pathophysiology. We focus on evidence supporting the crucial role of either redox dysregulation, N-methyl-D-aspartate receptor hypofunction, neuroinflammation or mitochondria bioenergetics dysfunction, initiating "vicious circles" centered on oxidative stress during neurodevelopment. These processes would amplify one another in positive feed-forward loops, leading to persistent impairments of the maturation and function of local parvalbumin-GABAergic neurons microcircuits and myelinated fibers of long-range macrocircuitry. This is at the basis of neural circuit synchronization impairments and cognitive, emotional, social and sensory deficits characteristic of schizophrenia. Potential therapeutic approaches that aim at breaking these different vicious circles represent promising strategies for timely and safe interventions. In order to improve early detection and increase the signal-to-noise ratio for adjunctive trials of antioxidant, anti-inflammatory and NMDAR modulator drugs, a reverse translation of validated circuitry approach is needed. The above presented processes allow to identify mechanism based biomarkers guiding stratification of homogenous patients groups and target engagement required for successful clinical trials, paving the way towards precision medicine in psychiatry.

Mitochondrial, exosomal miR137-COX6A2 and gamma synchrony as biomarkers of parvalbumin interneurons, psychopathology, and neurocognition in schizophrenia

Early detection and intervention in schizophrenia requires mechanism-based biomarkers that capture neural circuitry dysfunction, allowing better patient stratification, monitoring of disease progression and treatment. In prefrontal cortex and blood of redox dysregulated mice (Gclm-KO ± GBR), oxidative stress induces miR-137 upregulation, leading to decreased COX6A2 and mitophagy markers (NIX, Fundc1, and LC3B) and to accumulation of damaged mitochondria, further exacerbating oxidative stress and parvalbumin interneurons (PVI) impairment. MitoQ, a mitochondria-targeted antioxidant, rescued all these processes. Translating to early psychosis patients (EPP), blood exosomal miR-137 increases and COX6A2 decreases, combined with mitophagy markers alterations, suggest that observations made centrally and peripherally in animal model were reflected in patients' blood. Higher exosomal miR-137 and lower COX6A2 levels were associated with a reduction of ASSR gamma oscillations in EEG. As ASSR requires proper PVI-related networks, alterations in miR-137/COX6A2 plasma exosome levels may represent a proxy marker of PVI cortical microcircuit impairment. EPP can be stratified in two subgroups: (a) a patients' group with mitochondrial dysfunction "Psy-D", having high miR-137 and low COX6A2 levels in exosomes, and (b) a "Psy-ND" subgroup with no/low mitochondrial impairment, including patients having miR-137 and COX6A2 levels in the range of controls. Psy-D patients exhibited more impaired ASSR responses in association with worse psychopathological status, neurocognitive performance, and global and social functioning, suggesting that impairment of PVI mitochondria leads to more severe disease profiles. This stratification would allow, with high selectivity and specificity, the selection of patients for treatments targeting brain mitochondria dysregulation and capture the clinical and functional efficacy of future clinical trials.

[Oxidative stress in schizophrenia as a promising target for psychopharmacotherapy]

Until now, only dopamine receptor blockers are used for psychopharmacotherapy of schizophrenia, despite the active search for alternative pharmacological agents and a lot of research. However, most of these studies concerned molecules that somehow affect various neurotransmitter receptors. In addition, various anti-inflammatory drugs have been studied quite actively. At the same time, attempts to correct oxidative stress are given significantly less attention, although the emergence of the latter is facilitated by completely different pathophysiological processes and environmental factors associated with the development of schizophrenia. NMDA receptor blockage, vitamin D deficiency, social isolation, chronic stress in adolescence, inflammation, perinatal infection etc. - all this can ultimately lead to the occurrence of oxidative stress. However, there is a significant difference in the severity of this process depending on the stage of the course of schizophrenia, which probably partially explains the heterogeneity of results of the studies on the oxidative stress biomarkers in this disorder. In order to overcome these methodological problems, it seems promising to conduct double-blind studies of the effectiveness of antioxidants in schizophrenia with the selection of groups of patients taking into account the stage of the disorder and the level of certain biomarkers of oxidative stress (F2-isoprostanes, 8-oxodG, 8-oxoGuo). The optimal pharmacological agents for such studies are N-acetylcysteine due to the positive results of previous studies, and melatonin as an antioxidant with a unique activity profile.

Chromosomal Microarray Analysis as First-Tier Genetic Test for Schizophrenia

Schizophrenia is a chronic, devastating mental disorder with complex genetic components. Given the advancements in the molecular genetic research of schizophrenia in recent years, there is still a lack of genetic tests that can be used in clinical settings. Chromosomal microarray analysis (CMA) has been used as first-tier genetic testing for congenital abnormalities, developmental delay, and autism spectrum disorders. This study attempted to gain some experience in applying chromosomal microarray analysis as a first-tier genetic test for patients with schizophrenia. We consecutively enrolled patients with schizophrenia spectrum disorder from a clinical setting and conducted genome-wide copy number variation (CNV) analysis using a chromosomal microarray platform. We followed the 2020 “Technical Standards for the interpretation and reporting of constitutional copy-number variants: a joint consensus recommendation of the American College of Medical Genetics and Genomics (ACMG) and the Clinical Genome Resource (ClinGen)” to interpret the clinical significance of CNVs detected from patients. We recruited a total of 60 patients (36 females and 24 males) into this study. We detected three pathogenic CNVs and one likely pathogenic CNV in four patients, respectively. The detection rate was 6.7% (4/60, 95% CI: 0.004–0.13), comparable with previous studies in the literature. Also, we detected thirteen CNVs classified as uncertain clinical significance in nine patients. Detecting these CNVs can help establish the molecular genetic diagnosis of schizophrenia patients and provide helpful information for genetic counseling and clinical management. Also, it can increase our understanding of the pathogenesis of schizophrenia. Hence, we suggest CMA is a valuable genetic tool and considered first-tier genetic testing for schizophrenia spectrum disorders in clinical settings.

Xenobiotic transport and metabolism in the human brain

Organisms have metabolic pathways responsible for eliminating endogenous and exogenous toxicants. Generally, we associate the liver par excellence as the organ in charge of detoxifying the body; however, this process occurs in all tissues, including the brain. Due to the presence of the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCSFB), the Central Nervous System (CNS) is considered a partially isolated organ, but similar to other organs, the CNS possess xenobiotic transporters and metabolic pathways associated with the elimination of xenobiotic agents. In this review, we describe the different systems related to the detoxification of xenobiotics in the CNS, providing examples in which their association with neurodegenerative processes is suspected. The CNS detoxifying systems include carrier-mediated, active efflux and receptor-mediated transport, and detoxifying systems that include phase I and phase II enzymes, as well as those enzymes in charge of neutralizing compounds such as electrophilic agents, reactive oxygen species (ROS), and free radicals, which are products of the bioactivation of xenobiotics. Moreover, we discuss the differential expression of these systems in different regions of the CNS, showing the different detoxifying needs and the composition of each region in terms of the cell type, neurotransmitter content, and the accumulation of xenobiotics and/or reactive compounds.

The conserved ASTN2/BRINP1 locus at 9q33.1-33.2 is associated with major psychiatric disorders in a large pedigree from Southern Spain

We investigated the genetic causes of major mental disorders (MMDs) including schizophrenia, bipolar disorder I, major depressive disorder and attention deficit hyperactive disorder, in a large family pedigree from Alpujarras, South of Spain, a region with high prevalence of psychotic disorders. We applied a systematic genomic approach based on karyotyping (n = 4), genotyping by genome-wide SNP array (n = 34) and whole-genome sequencing (n = 12). We performed genome-wide linkage analysis, family-based association analysis and polygenic risk score estimates. Significant linkage was obtained at chromosome 9 (9q33.1–33.2, LOD score = 4.11), a suggestive region that contains five candidate genes ASTN2, BRINP1, C5, TLR4 and TRIM32, previously associated with MMDs. Comprehensive analysis associated the MMD phenotype with genes of the immune system with dual brain functions. Moreover, the psychotic phenotype was enriched for genes involved in synapsis. These results should be considered once studying the genetics of psychiatric disorders in other families, especially the ones from the same region, since founder effects may be related to the high prevalence.

Additive effect of glutathione S-transferase T1 active genotype and infection with Toxoplasma gondii for increasing the risk of schizophrenia

PURPOSE

To determine if Toxoplasma gondii (T. gondii) infection may play a role in the development of schizophrenia in genetically susceptible persons with regard to genes encoding glutathione S-transferase T1 (GSTT1) and M1 (GSTM1).

METHODS

A total of 78 cases with psychiatric diagnosis of schizophrenia were compared with 91 healthy controls. For detection of IgG antibodies, enzyme-linked immunosorbent assay was used. Genotyping of GSTM1 and GSTT1 was performed by multiplex PCR. Chi-square and logistic regression were used for statistical analyses.

RESULTS

A higher frequency of the GSTT1 active gene in schizophrenic patients was observed. When risk categories based on the combination of T. gondii status and GSTs polymorphisms were compared, risk of schizophrenia increased in T. gondii positive/GSTT1 absent subjects (OR = 4.75, p = 0.05) compared with T. gondii negative/GSTT1 absent group. When T. gondii positive subjects had the GSTT1 active genotype, the risk increased linearly (OR = 10.20, p < 0.001). Odds ratio in T. gondii positive groups were almost the same in combination with the GSTM1 active genotype (OR = 4.45, p = 0.003) or null genotype (OR = 4.37, p = 0.006).

CONCLUSIONS

Our results showed an additive effect for T. gondii and GSTT1 active genotype as risk factors for schizophrenia in Iranian population. This is a small pilot study and replicating the study with larger groups of patients in multinational investigation to clarify these findings is recommended.

Oxidative Stress-Related Mechanisms in Schizophrenia Pathogenesis and New Treatment Perspectives

Schizophrenia is recognized to be a highly heterogeneous disease at various levels, from genetics to clinical manifestations and treatment sensitivity. This heterogeneity is also reflected in the variety of oxidative stress-related mechanisms contributing to the phenotypic realization and manifestation of schizophrenia. At the molecular level, these mechanisms are supposed to include genetic causes that increase the susceptibility of individuals to oxidative stress and lead to gene expression dysregulation caused by abnormal regulation of redox-sensitive transcriptional factors, noncoding RNAs, and epigenetic mechanisms favored by environmental insults. These changes form the basis of the prooxidant state and lead to altered redox signaling related to glutathione deficiency and impaired expression and function of redox-sensitive transcriptional factors (Nrf2, NF-κB, FoxO, etc.). At the cellular level, these changes lead to mitochondrial dysfunction and metabolic abnormalities that contribute to aberrant neuronal development, abnormal myelination, neurotransmitter anomalies, and dysfunction of parvalbumin-positive interneurons. Immune dysfunction also contributes to redox imbalance. At the whole-organism level, all these mechanisms ultimately contribute to the manifestation and development of schizophrenia. In this review, we consider oxidative stress-related mechanisms and new treatment perspectives associated with the correction of redox imbalance in schizophrenia. We suggest that not only antioxidants but also redox-regulated transcription factor-targeting drugs (including Nrf2 and FoxO activators or NF-κB inhibitors) have great promise in schizophrenia. But it is necessary to develop the stratification criteria of schizophrenia patients based on oxidative stress-related markers for the administration of redox-correcting treatment.

N-acetyl-cysteine in Schizophrenia: Potential Role on the Sensitive Cysteine Proteome

BACKGROUND

N-acetyl-cysteine (NAC) has shown widespread utility in different psychiatric disorders, including a beneficial role in schizophrenic patients. Although the replenishment of glutathione and the antioxidant activity of NAC have been suggested as the mechanisms that improve such a wide range of disorders, none seems to be sufficiently specific to explain these intriguing effects. A sensitive cysteine proteome is emerging as a functional and structural network of interconnected Sensitive Cysteine-containing Proteins (SCCPs) that together with reactive species and the cysteine/ glutathione cycles can regulate the bioenergetic metabolism, the redox homeostasis and the cellular growth, differentiation and survival, acting through different pathways that are regulated by the same thiol radical in cysteine residues.

OBJECTIVE

Since this sensitive cysteine network has been implicated in the pathogenesis of Parkinson's and Alzheimer's diseases, I have reviewed if the proteins that play a role in schizophrenia can be classified as SCCPs.

RESULTS

The results show that the principal proteins playing a role in schizophrenia can be classified as SCCPs, suggesting that the sensitive cysteine proteome (cysteinet) is defective in this type of psychosis.

CONCLUSION

The present review proposes that there is a deregulation of the sensitive cysteine proteome in schizophrenia as the consequence of a functional imbalance among different SCCPs, which play different functions in neurons and glial cells. In this context, the role of NAC to restore and prevent schizophrenic disorders is discussed.

MMP9/RAGE pathway overactivation mediates redox dysregulation and neuroinflammation, leading to inhibitory/excitatory imbalance: a reverse translation study in schizophrenia patients

Various mechanisms involved in schizophrenia pathophysiology, such as dopamine dysregulation, glutamate/NMDA receptor dysfunction, neuroinflammation or redox imbalance, all appear to converge towards an oxidative stress "hub" affecting parvalbumine interneurones (PVI) and their perineuronal nets (PNN) (Lancet Psychiatry. 2015;2:258-70); (Nat Rev Neurosci. 2016;17:125-34). We aim to investigate underlying mechanisms linking oxidative stress with neuroinflammatory and their long-lasting harmful consequences. In a transgenic mouse of redox dysregulation carrying a permanent deficit of glutathione synthesis (gclm-/-), the anterior cingulate cortex presented early in the development increased oxidative stress which was prevented by the antioxidant N-acetylcysteine (Eur J Neurosci. 2000;12:3721-8). This oxidative stress induced microglia activation and redox-sensitive matrix metalloproteinase 9 (MMP9) stimulation, leading to the receptor for advanced glycation end-products (RAGE) shedding into soluble and nuclear forms, and subsequently to nuclear factor-kB (NF-kB) activation and secretion of various cytokines. Blocking MMP9 activation prevented this sequence of alterations and rescued the normal maturation of PVI/PNN, even if performed after an additional insult that exacerbated the long term PVI/PNN impairments. MMP9 inhibition thus appears to be able to interrupt the vicious circle that maintains the long-lasting deleterious effects of the reciprocal interaction between oxidative stress and neuroinflammation, impacting on PVI/PNN integrity. Translation of these experimental findings to first episode patients revealed an increase in plasma soluble RAGE relative to healthy controls. This increase was associated with low prefrontal GABA levels, potentially predicting a central inhibitory/excitatory imbalance linked to RAGE shedding. This study paves the way for mechanistically related biomarkers needed for early intervention and MMP9/RAGE pathway modulation may lead to promising drug targets.

ROS-Mediated Therapeutic Strategy in Chemo-/Radiotherapy of Head and Neck Cancer

Head and neck cancer is a highly genetic and metabolic heterogeneous collection of malignancies of the lip, oral cavity, salivary glands, pharynx, esophagus, paranasal sinuses, and larynx with five-year survival rates ranging from 12% to 93%. Patients with head and neck cancer typically present with advanced stage III, IVa, or IVb disease and are treated with comprehensive modality including chemotherapy, radiotherapy, and surgery. Despite advancements in treatment modality and technique, noisome recurrence, invasiveness, and resistance as well as posttreatment complications severely influence survival rate and quality of life. Thus, new therapeutic strategies are urgently needed that offer enhanced efficacy with less toxicity. ROS in cancer cells plays a vital role in regulating cell death, DNA repair, stemness maintenance, metabolic reprogramming, and tumor microenvironment, all of which have been implicated in resistance to chemo-/radiotherapy of head and neck cancer. Adjusting ROS generation and elimination to reverse the resistance of cancer cells without impairing normal cells show great hope in improving the therapeutic efficacy of chemo-/radiotherapy of head and neck cancer. In the current review, we discuss the pivotal and targetable redox-regulating system including superoxide dismutases (SODs), tripeptide glutathione (GSH), thioredoxin (Trxs), peroxiredoxins (PRXs), nuclear factor erythroid 2-related factor 2/Kelch-like ECH-associated protein 1 (Nrf2/keap1), and mitochondria electron transporter chain (ETC) complexes and their roles in regulating ROS levels and their clinical significance implicated in chemo-/radiotherapy of head and neck cancer. We also summarize several old drugs (referred to as the non-anti-cancer drugs used in other diseases for a long time) and small molecular compounds as well as natural herbs which effectively modulate cellular ROS of head and neck cancer to synergize the efficacy of conventional chemo-/radiotherapy. Emerging interdisciplinary techniques including photodynamic, nanoparticle system, and Bio-Electro-Magnetic-Energy-Regulation (BEMER) therapy are promising measures to broaden the potency of ROS modulation for the benefit of chemo-/radiotherapy in head and neck cancer.

Oxidation-reduction mechanisms in psychiatric disorders: A novel target for pharmacological intervention

While neurotransmitter dysfunction represents a key component in mental illnesses, there is now a wide agreement for a central pathophysiological hub that includes hormones, neuroinflammation, redox mechanisms as well as oxidative stress. With respect to oxidation-reduction (redox) mechanisms, preclinical and clinical evidence suggests that an imbalance in the pro/anti-oxidative homeostasis toward the increased production of substances with oxidizing potential may contribute to the etiology and manifestation of different psychiatric disorders. The substantial and continous demand for energy renders the brain highly susceptible to disturbances in its energy supply, especially following exposure to stressful events, which may lead to overproduction of reactive oxygen and nitrogen species under conditions of perturbed antioxidant defenses. This will eventually induce different molecular alterations, including extensive protein and lipid peroxidation, increased blood-brain barrier permeability and neuroinflammation, which may contribute to the changes in brain function and morphology observed in mental illnesses. This view may also reconcile different key concepts for psychiatric disorders, such as the neurodevelopmental origin of these diseases, as well as the vulnerability of selective cellular populations that are critical for specific functional abnormalities. The possibility to pharmacologically modulate the redox system is receiving increasing interest as a novel therapeutic strategy to counteract the detrimental effects of the unbalance in brain oxidative mechanisms. This review will describe the main mechanisms and mediators of the redox system and will examine the alterations of oxidative stress found in animal models of psychiatric disorders as well as in patients suffering from mental illnesses, such as schizophrenia and major depressive disorder. In addition, it will discuss studies that examined the effects of psychotropic drugs, including antipsychotics and antidepressants, on the oxidative balance as well as studies that investigated the effectiveness of a direct modulation of oxidative mechanisms in counteracting the behavioral and functional alterations associated with psychiatric disorders, which supports the promising role of the redox system as a novel therapeutic target for the improved treatment of brain disorders.

Unravelling the genetic basis of schizophrenia and bipolar disorder with GWAS: A systematic review

OBJECTIVES

To systematically review findings of GWAS in schizophrenia (SZ) and in bipolar disorder (BD); and to interpret findings, with a focus on identifying independent replications.

METHOD

PubMed search, selection and review of all independent GWAS in SZ or BD, published since March 2011, i.e. studies using non-overlapping samples within each article, between articles, and with those of the previous review (Li et al., 2012).

RESULTS

From the 22 GWAS included in this review, the genetic associations surviving standard GWAS-significance were for genetic markers in the regions of ACSL3/KCNE4, ADCY2, AMBRA1, ANK3, BRP44, DTL, FBLN1, HHAT, INTS7, LOC392301, LOC645434/NMBR, LOC729457, LRRFIP1, LSM1, MDM1, MHC, MIR2113/POU3F2, NDST3, NKAPL, ODZ4, PGBD1, RENBP, TRANK1, TSPAN18, TWIST2, UGT1A1/HJURP, WHSC1L1/FGFR1 and ZKSCAN4. All genes implicated across both reviews are discussed in terms of their function and implication in neuropsychiatry.

CONCLUSION

Taking all GWAS to date into account, AMBRA1, ANK3, ARNTL, CDH13, EFHD1 (albeit with different alleles), MHC, PLXNA2 and UGT1A1 have been implicated in either disorder in at least two reportedly non-overlapping samples. Additionally, evidence for a SZ/BD common genetic basis is most strongly supported by the implication of ANK3, NDST3, and PLXNA2.

VGF has Roles in the Pathogenesis of Major Depressive Disorder and Schizophrenia: Evidence from Transgenic Mouse Models

Mental disorders, such as major depressive disorder and schizophrenia, are complex multigenetic conditions, but focused studies of single genes might reveal genes involved in the pathogenesis of mental disorders, including major depressive disorder and schizophrenia. Several candidate genes have been identified using transgenic mice. VGF nerve growth factor inducible (VGF) is a neuropeptide expression of which is induced by nerve growth factor (NGF). VGF is robustly and exclusively synthesized in neuronal and neuroendocrine cells. In central nervous system (CNS), VGF is extensively expressed especially in the cerebral cortex, hippocampus, and hypothalamus. VGF has many roles in the CNS, such as promotion of synaptic plasticity, neurogenesis, and neurite outgrowth. In clinical studies, altered expression and genetic mutations of VGF have been reported in patients with major depressive disorder and schizophrenia. On this basis, studies using transgenic mice to overexpress or knockout VGF have been performed to investigate the roles of upregulation or downregulation of VGF. In this review, we will discuss studies of the roles of VGF using transgenic mice and its relevance to pathologies in major depressive disorder and schizophrenia.

Glutathione S-transferases promote proinflammatory astrocyte-microglia communication during brain inflammation

Astrocytes and microglia play critical roles in brain inflammation. Here, we report that glutathione S-transferases (GSTs), particularly GSTM1, promote proinflammatory signaling in astrocytes and contribute to astrocyte-mediated microglia activation during brain inflammation. In vivo, astrocyte-specific knockdown of GSTM1 in the prefrontal cortex attenuated microglia activation in brain inflammation induced by systemic injection of lipopolysaccharides (LPS). Knocking down GSTM1 in astrocytes also attenuated LPS-induced production of the proinflammatory cytokine tumor necrosis factor-α (TNF-α) by microglia when the two cell types were cocultured. In astrocytes, GSTM1 was required for the activation of nuclear factor κB (NF-κB) and the production of proinflammatory mediators, such as granulocyte-macrophage colony-stimulating factor (GM-CSF) and C-C motif chemokine ligand 2 (CCL2), both of which enhance microglia activation. Our study suggests that GSTs play a proinflammatory role in priming astrocytes and enhancing microglia activation in a microglia-astrocyte positive feedback loop during brain inflammation.

Impaired Cerebellar Development in Mice Overexpressing VGF

VGF nerve growth factor inducible (VGF) is a neuropeptide precursor induced by brain-derived neurotrophic factor and nerve growth factor. VGF is increased in the prefrontal cortex and cerebrospinal fluid in schizophrenia patients. In our previous study, VGF-overexpressing mice exhibited schizophrenia-like behaviors and smaller brain weights. Brain developmental abnormality is one cause of mental illness. Research on brain development is important for discovery of pathogenesis of mental disorders. In the present study, we investigated the role of VGF on cerebellar development. We performed a histological analysis with cerebellar sections of adult and postnatal day 3 mice by Nissl staining. To investigate cerebellar development, we performed immunostaining with antibodies of immature and mature granule cell markers. To understand the mechanism underlying these histological changes, we examined MAPK, Wnt, and sonic hedgehog signaling by Western blot. Finally, we performed rotarod and footprint tests using adult mice to investigate motor function. VGF-overexpressing adult mice exhibited smaller cerebellar sagittal section area. In postnatal day 3 mice, a cerebellar sagittal section area reduction of the whole cerebellum and external granule layer and a decrease in the number of mature granule cells were found in VGF-overexpressing mice. Additionally, the number of proliferative granule cell precursors was lower in VGF-overexpressing mice. Phosphorylation of Trk and Erk1 were increased in the cerebellum of postnatal day 3 VGF-overexpressing mice. Adult VGF-overexpressing mice exhibited motor disability. All together, these findings implicate VGF in the development of cerebellar granule cells via promoting MAPK signaling and motor function in the adult stage.

N-acetylcysteine add-on treatment leads to an improvement of fornix white matter integrity in early psychosis: a double-blind randomized placebo-controlled trial

Mechanism-based treatments for schizophrenia are needed, and increasing evidence suggests that oxidative stress may be a target. Previous research has shown that N-acetylcysteine (NAC), an antioxidant and glutathione (GSH) precursor almost devoid of side effects, improved negative symptoms, decreased the side effects of antipsychotics, and improved mismatch negativity and local neural synchronization in chronic schizophrenia. In a recent double-blind randomized placebo-controlled trial by Conus et al., early psychosis patients received NAC add-on therapy (2700 mg/day) for 6 months. Compared with placebo-treated controls, NAC patients showed significant improvements in neurocognition (processing speed) and a reduction of positive symptoms among patients with high peripheral oxidative status. NAC also led to a 23% increase in GSH levels in the medial prefrontal cortex (GSH_mPFC) as measured by ¹H magnetic resonance spectroscopy. A subgroup of the patients in this study were also scanned with multimodal MR imaging (spectroscopy, diffusion, and structural) at baseline (prior to NAC/placebo) and after 6 months of add-on treatment. Based on prior translational research, we hypothesized that NAC would protect white matter integrity in the fornix. A group × time interaction indicated a difference in the 6-month evolution of white matter integrity (as measured by generalized fractional anisotropy, gFA) in favor of the NAC group, which showed an 11% increase. The increase in gFA correlated with an increase in GSH_mPFC over the same 6-month period. In this secondary study, we suggest that NAC add-on treatment may be a safe and effective way to protect white matter integrity in early psychosis patients.

N-acetylcysteine in a Double-Blind Randomized Placebo-Controlled Trial: Toward Biomarker-Guided Treatment in Early Psychosis

Biomarker-guided treatments are needed in psychiatry, and previous data suggest oxidative stress may be a target in schizophrenia. A previous add-on trial with the antioxidant N-acetylcysteine (NAC) led to negative symptom reductions in chronic patients. We aim to study NAC's impact on symptoms and neurocognition in early psychosis (EP) and to explore whether glutathione (GSH)/redox markers could represent valid biomarkers to guide treatment. In a double-blind, randomized, placebo-controlled trial in 63 EP patients, we assessed the effect of NAC supplementation (2700 mg/day, 6 months) on PANSS, neurocognition, and redox markers (brain GSH [GSHmPFC], blood cells GSH levels [GSHBC], GSH peroxidase activity [GPxBC]). No changes in negative or positive symptoms or functional outcome were observed with NAC, but significant improvements were found in favor of NAC on neurocognition (processing speed). NAC also led to increases of GSHmPFC by 23% (P = .005) and GSHBC by 19% (P = .05). In patients with high-baseline GPxBC compared to low-baseline GPxBC, subgroup explorations revealed a link between changes of positive symptoms and changes of redox status with NAC. In conclusion, NAC supplementation in a limited sample of EP patients did not improve negative symptoms, which were at modest baseline levels. However, NAC led to some neurocognitive improvements and an increase in brain GSH levels, indicating good target engagement. Blood GPx activity, a redox peripheral index associated with brain GSH levels, could help identify a subgroup of patients who improve their positive symptoms with NAC. Thus, future trials with antioxidants in EP should consider biomarker-guided treatment.

Treatment in early psychosis with N-acetyl-cysteine for 6months improves low-level auditory processing: Pilot study

Sensory impairments constitute core dysfunctions in schizophrenia. In the auditory modality, impaired mismatch negativity (MMN) has been observed in chronic schizophrenia and may reflect N-methyl-d-aspartate (NMDA) hypo-function, consistent with models of schizophrenia based on oxidative stress. Moreover, a recent study demonstrated deficits in the N100 component of the auditory evoked potential (AEP) in early psychosis patients. Previous work has shown that add-on administration of the glutathione precursor N-acetyl-cysteine (NAC) improves the MMN and clinical symptoms in chronic schizophrenia. To date, it remains unknown whether NAC also improves general low-level auditory processing and if its efficacy would extend to early-phase psychosis. We addressed these issues with a randomized, double-blind study of a small sample (N=15) of early psychosis (EP) patients and 18 healthy controls from whom AEPs were recorded during an active, auditory oddball task. Patients were recorded twice: once prior to NAC/placebo administration and once after six months of treatment. The N100 component was significantly smaller in patients before NAC administration versus controls. Critically, NAC administration improved this AEP deficit. Source estimations revealed increased activity in the left temporo-parietal lobe in patients after NAC administration. Overall, the data from this pilot study, which call for replication in a larger sample, indicate that NAC improves low-level auditory processing in early psychosis.

The coupling of low-level auditory dysfunction and oxidative stress in psychosis patients

Patients diagnosed with schizophrenia often present with low-level sensory deficits. It is an open question whether there is a functional link between these deficits and the pathophysiology of the disease, e.g. oxidative stress and glutathione (GSH) metabolism dysregulation. Auditory evoked potentials (AEPs) were recorded from 21 psychosis disorder patients and 30 healthy controls performing an active, auditory oddball task. AEPs to standard sounds were analyzed within an electrical neuroimaging framework. A peripheral measure of participants' redox balance, the ratio of glutathione peroxidase and glutathione reductase activities (GPx/GR), was correlated with the AEP data. Patients displayed significantly decreased AEPs over the time window of the P50/N100 complex resulting from significantly weaker responses in the left temporo-parietal lobe. The GPx/GR ratio significantly correlated with patients' brain activity during the time window of the P50/N100 in the medial frontal lobe. We show for the first time a direct coupling between electrophysiological indices of AEPs and peripheral redox dysregulation in psychosis patients. This coupling is limited to stages of auditory processing that are impaired relative to healthy controls and suggests a link between biochemical and sensory dysfunction. The data highlight the potential of low-level sensory processing as a trait-marker of psychosis.

Rare Genome-Wide Copy Number Variation and Expression of Schizophrenia in 22q11.2 Deletion Syndrome

OBJECTIVE

Chromosome 22q11.2 deletion syndrome (22q11.2DS) is associated with a more than 20-fold increased risk for developing schizophrenia. The aim of this study was to identify additional genetic factors (i.e., "second hits") that may contribute to schizophrenia expression.

METHOD

Through an international consortium, the authors obtained DNA samples from 329 psychiatrically phenotyped subjects with 22q11.2DS. Using a high-resolution microarray platform and established methods to assess copy number variation (CNV), the authors compared the genome-wide burden of rare autosomal CNV, outside of the 22q11.2 deletion region, between two groups: a schizophrenia group and those with no psychotic disorder at age ≥25 years. The authors assessed whether genes overlapped by rare CNVs were overrepresented in functional pathways relevant to schizophrenia.

RESULTS

Rare CNVs overlapping one or more protein-coding genes revealed significant between-group differences. For rare exonic duplications, six of 19 gene sets tested were enriched in the schizophrenia group; genes associated with abnormal nervous system phenotypes remained significant in a stepwise logistic regression model and showed significant interactions with 22q11.2 deletion region genes in a connectivity analysis. For rare exonic deletions, the schizophrenia group had, on average, more genes overlapped. The additional rare CNVs implicated known (e.g., GRM7, 15q13.3, 16p12.2) and novel schizophrenia risk genes and loci.

CONCLUSIONS

The results suggest that additional rare CNVs overlapping genes outside of the 22q11.2 deletion region contribute to schizophrenia risk in 22q11.2DS, supporting a multigenic hypothesis for schizophrenia. The findings have implications for understanding expression of psychotic illness and herald the importance of whole-genome sequencing to appreciate the overall genomic architecture of schizophrenia.

Oxidative stress, prefrontal cortex hypomyelination and cognitive symptoms in schizophrenia

Schizophrenia (SZ) is a neurodevelopmental disorder with a broad symptomatology, including cognitive symptoms that are thought to arise from the prefrontal cortex (PFC). The neurobiological aetiology of these symptoms remains elusive, yet both impaired redox control and PFC dysconnectivity have been recently implicated. PFC dysconnectivity has been linked to white matter, oligodendrocyte (OL) and myelin abnormalities in SZ patients. Myelin is produced by mature OLs, and OL precursor cells (OPCs) are exceptionally susceptible to oxidative stress. Here we propose a hypothesis for the aetiology of cognitive symptomatology in SZ: the redox-induced prefrontal OPC-dysfunctioning hypothesis. We pose that the combination of genetic and environmental factors causes oxidative stress marked by a build-up of reactive oxygen species that, during late adolescence, impair OPC signal transduction processes that are necessary for OPC proliferation and differentiation, and involve AMP-activated protein kinase, Akt-mTOR-P70S6K and peroxisome proliferator receptor alpha signalling. OPC dysfunctioning coincides with the relatively late onset of PFC myelination, causing hypomyelination and disruption of connectivity in this brain area. The resulting cognitive deficits arise in parallel with SZ onset. Hence, our hypothesis provides a novel neurobiological framework for the aetiology of SZ cognitive symptoms. Future research addressing our hypothesis could have important implications for the development of new (combined) antioxidant- and promyelination-based strategies to treat the cognitive symptoms in SZ.

Oxidative stress-driven parvalbumin interneuron impairment as a common mechanism in models of schizophrenia

Parvalbumin inhibitory interneurons (PVIs) are crucial for maintaining proper excitatory/inhibitory balance and high-frequency neuronal synchronization. Their activity supports critical developmental trajectories, sensory and cognitive processing, and social behavior. Despite heterogeneity in the etiology across schizophrenia and autism spectrum disorder, PVI circuits are altered in these psychiatric disorders. Identifying mechanism(s) underlying PVI deficits is essential to establish treatments targeting in particular cognition. On the basis of published and new data, we propose oxidative stress as a common pathological mechanism leading to PVI impairment in schizophrenia and some forms of autism. A series of animal models carrying genetic and/or environmental risks relevant to diverse etiological aspects of these disorders show PVI deficits to be all accompanied by oxidative stress in the anterior cingulate cortex. Specifically, oxidative stress is negatively correlated with the integrity of PVIs and the extracellular perineuronal net enwrapping these interneurons. Oxidative stress may result from dysregulation of systems typically affected in schizophrenia, including glutamatergic, dopaminergic, immune and antioxidant signaling. As convergent end point, redox dysregulation has successfully been targeted to protect PVIs with antioxidants/redox regulators across several animal models. This opens up new perspectives for the use of antioxidant treatments to be applied to at-risk individuals, in close temporal proximity to environmental impacts known to induce oxidative stress.

Novel genes involved in severe early-onset obesity revealed by rare copy number and sequence variants

Obesity is a multifactorial disorder with high heritability (50–75%), which is probably higher in early-onset and severe cases. Although rare monogenic forms and several genes and regions of susceptibility, including copy number variants (CNVs), have been described, the genetic causes underlying the disease still remain largely unknown. We searched for rare CNVs (>100kb in size, altering genes and present in <1/2000 population controls) in 157 Spanish children with non-syndromic early-onset obesity (EOO: body mass index >3 standard deviations above the mean at <3 years of age) using SNP array molecular karyotypes. We then performed case control studies (480 EOO cases/480 non-obese controls) with the validated CNVs and rare sequence variants (RSVs) detected by targeted resequencing of selected CNV genes (n = 14), and also studied the inheritance patterns in available first-degree relatives. A higher burden of gain-type CNVs was detected in EOO cases versus controls (OR = 1.71, p-value = 0.0358). In addition to a gain of the NPY gene in a familial case with EOO and attention deficit hyperactivity disorder, likely pathogenic CNVs included gains of glutamate receptors (GRIK1, GRM7) and the X-linked gastrin-peptide receptor (GRPR), all inherited from obese parents. Putatively functional RSVs absent in controls were also identified in EOO cases at NPY, GRIK1 and GRPR. A patient with a heterozygous deletion disrupting two contiguous and related genes, SLCO4C1 and SLCO6A1, also had a missense RSV at SLCO4C1 on the other allele, suggestive of a recessive model. The genes identified showed a clear enrichment of shared co-expression partners with known genes strongly related to obesity, reinforcing their role in the pathophysiology of the disease. Our data reveal a higher burden of rare CNVs and RSVs in several related genes in patients with EOO compared to controls, and implicate NPY, GRPR, two glutamate receptors and SLCO4C1 in highly penetrant forms of familial obesity.

Although there is strong evidence for a high genetic component of obesity, the underlying genetic causes are largely unknown, mostly due to the highly heterogeneous nature of the disorder. In this work, we have focused on the most severe end of the spectrum, severe obesity with early-onset in childhood, which is more likely due to genetic alterations. We screened for rare copy number variation (CNV) a sample of 157 Spanish children with early-onset obesity using molecular karyotypes and then studied the genes altered by CNVs in 480 cases and 480 non-obese controls. We identified a higher burden of gain-type CNVs in cases as well as several CNVs and sequence variants that were specific of the obese population. Interestingly, the genes identified shared co-expression partners with known obesity genes. Among those, the genes encoding the neuropeptide Y (NPY), two glutamate receptors (GRIK1, GRM7), the X-linked gastrin-peptide receptor (GRPR), and the organic anion transporter (SLCO4C1) are novel obesity candidate genes that may contribute to highly penetrant forms of familial obesity.

Copy number variations in Saudi family with intellectual disability and epilepsy

Background

Epilepsy is genetically complex but common brain disorder of the world affecting millions of people with almost of all age groups. Novel Copy number variations (CNVs) are considered as important reason for the numerous neurodevelopmental disorders along with intellectual disability and epilepsy. DNA array based studies contribute to explain a more severe clinical presentation of the disease but interoperation of many detected CNVs are still challenging.

Results

In order to study novel CNVs with epilepsy related genes in Saudi family with six affected and two normal individuals with several forms of epileptic seizures, intellectual disability (ID), and minor dysmorphism, we performed the high density whole genome Agilent sure print G3 Hmn CGH 2x 400 K array-CGH chips analysis. Our results showed de novo deletions, duplications and deletion plus duplication on differential chromosomal regions in the affected individuals that were not shown in the normal fathe and normal kids by using Agilent CytoGenomics 3.0.6.6 softwear. Copy number gain were observed in the chromosome 1, 16 and 22 with LCE3C, HPR, GSTT2, GSTTP2, DDT and DDTL genes respectively whereas the deletions observed in the chromosomal regions 8p23-p21 (4303127–4337759) and the potential gene in this region is CSMD1 (OMIM: 612279). Moreover, the array CGH results deletions and duplication were also validated by using primer design of deleted regions utilizing the flanked SNPs using simple PCR and also by using quantitative real time PCR.

Conclusions

We found some of the de novo deletions and duplication in our study in Saudi family with intellectual disability and epilepsy. Our results suggest that array-CGH should be used as a first line of genetic test for epilepsy except there is a strong indication for a monogenic syndrome. The advanced high through put array-CGH technique used in this study aim to collect the data base and to identify new mechanisms describing epileptic disorder, may help to improve the clinical management of individual cases in decreasing the burden of epilepsy in Saudi Arabia.

Redox dysregulation, neuroinflammation, and NMDA receptor hypofunction: A "central hub" in schizophrenia pathophysiology?

Accumulating evidence points to altered GABAergic parvalbumin-expressing interneurons and impaired myelin/axonal integrity in schizophrenia. Both findings could be due to abnormal neurodevelopmental trajectories, affecting local neuronal networks and long-range synchrony and leading to cognitive deficits. In this review, we present data from animal models demonstrating that redox dysregulation, neuroinflammation and/or NMDAR hypofunction (as observed in patients) impairs the normal development of both parvalbumin interneurons and oligodendrocytes. These observations suggest that a dysregulation of the redox, neuroimmune, and glutamatergic systems due to genetic and early-life environmental risk factors could contribute to the anomalies of parvalbumin interneurons and white matter in schizophrenia, ultimately impacting cognition, social competence, and affective behavior via abnormal function of micro- and macrocircuits. Moreover, we propose that the redox, neuroimmune, and glutamatergic systems form a "central hub" where an imbalance within any of these "hub" systems leads to similar anomalies of parvalbumin interneurons and oligodendrocytes due to the tight and reciprocal interactions that exist among these systems. A combination of vulnerabilities for a dysregulation within more than one of these systems may be particularly deleterious. For these reasons, molecules, such as N-acetylcysteine, that possess antioxidant and anti-inflammatory properties and can also regulate glutamatergic transmission are promising tools for prevention in ultra-high risk patients or for early intervention therapy during the first stages of the disease.

Implications for reactive oxygen species in schizophrenia pathogenesis

Oxidative stress is a well-recognized participant in the pathophysiology of multiple brain disorders, particularly neurodegenerative conditions such as Alzheimer's and Parkinson's diseases. While not a dementia, a wide body of evidence has also been accumulating for aberrant reactive oxygen species and inflammation in schizophrenia. Here we highlight roles for oxidative stress as a common mechanism by which varied genetic and epidemiologic risk factors impact upon neurodevelopmental processes that underlie the schizophrenia syndrome. While there is longstanding evidence that schizophrenia may not have a single causative lesion, a common pathway involving oxidative stress opens the possibility for intervention at susceptible phases.

High frequency of CYP2D6 ultrarapid metabolizers in Spain: controversy about their misclassification in worldwide population studies

A high frequency (7-10%) of CYP2D6 ultrarapid metabolizers estimated from the genotype (gUMs) has been claimed to exist among Spaniards and Southern Europeans. However, methodological aspects such as the inclusion of individuals carrying non-active multiplied alleles as gUMs may have led to an overestimation. Thus, this study aimed to analyze the gUM frequency (considering only those carrying more than two active genes) in 805 Spanish healthy volunteers studied for CYP2D6*2, *3, *4, *5, *6, *10, *17, *35, *41, and multiplications. Second, all worldwide studies reporting gUM frequencies were reviewed in order to evaluate potential misclassifications. The gUM frequency in this Spanish population was 5.34%, but increased to 8.3% if all individuals with CYP2D6 multiplications were classified as gUMs without considering the activity of the multiplied alleles. Moreover, among all reviewed worldwide studies only 55.6% precisely determined whether the multiplied alleles were active. Present results suggest that the evaluation of CYP2D6 ultrarapid metabolism should be standarized, and that the frequency of gUMs should be reconsidered in Spaniards and globally.

NMDA Receptor Internalization by Autoantibodies: A Reversible Mechanism Underlying Psychosis?

Since the early 1990s it has been postulated that hypofunction of N-methyl-d-aspartate (NMDA) receptors in brain networks supporting perception and cognition underlies schizophrenic psychosis. Recently, NMDA receptor hypofunction was described in patients with psychotic manifestations who exhibited autoantibodies binding the GluN1 subunit of the receptor, and who improved when the level of these antibodies was lowered by immunomodulation. In this disorder, NMDA receptor antibodies decrease the availability of NMDA receptors by internalizing them. In this opinion article, we review this mechanism as well as data supporting or refuting the possibility that this disorder or similar autoimmune disorders affecting synaptic proteins, which are therefore treatable with immunomodulation, could account for some cases of idiopathic psychosis. We also suggest methodological approaches to clarify this issue.

Glutathione S-Transferase Deletion Polymorphisms in Early-Onset Psychotic and Bipolar Disorders: A Case-Control Study

OBJECTIVE

To examine glutathione S-transferase (GST) deletion polymorphisms in development of early-onset severe mental disorders, with the hypothesis that patients with GSTM1-null and GSTT1-null genotypes will develop psychotic disorders at a younger age.

METHODS

We identified GSTM1 and GSTT1 deletion polymorphisms by multiplex polymerase chain reaction (PCR) in 93 patients with early onset severe mental disorders and 278 control individuals. The diagnoses were confirmed by Schedule for Affective Disorders and Schizophrenia for School-Age Children-Present and Lifetime Version and Schedule for Affective Disorders and Schizophrenia-Life-Time Version (K-SADS-PL) interviews.

RESULTS

Individuals with the GSTM1-null genotype were at 3.36-fold higher risk of developing early-onset severe mental disorders than carriers of a corresponding active genotype. The risk of those disorders was increased by 6.59-fold in patients with GSTM1-null/GSTT1-active genotype. Patients with the GSTM1-null genotype were at approximately 2-fold increased risk for developing early-onset schizophrenia-spectrum disorder (EOS), early-onset bipolar disorder (EOBD) with psychotic symptoms, or early-onset first-episode psychosis (EOFEP), compared with patients with the GSTM1-active genotype.

CONCLUSION

The GSTM1-null genotype might be associated with higher risk for early onset severe mental disorders.

Association of copy number polymorphisms at the promoter and translated region of COMT with Japanese patients with schizophrenia

Chromosome 22q11.2 deletion syndrome and genetic variations including single-nucleotide polymorphism (SNP) and copy number variation (CNV) in catechol-O-methyltransferase (COMT) situated at 22q11.2 remains controversial. Here, the genetic relationship between COMT and Japanese patients with schizophrenia was investigated by examining whether the SNPs correlated with schizophrenia based on a common disease-common variant hypothesis. Additionally, 22q11.2DS were screened based on a common disease-rare variant hypothesis; low-frequency CNVs situated at two COMT promoters and exons were investigated based on the low-frequency variants with an intermediate effect; and positive findings from the first stage were reconfirmed using a second-stage replication study including a larger sample size. Eight SNPs and 10 CNVs were investigated using Taqman SNP and CNV quantitative real-time polymerase chain reaction method. For the first-stage analysis, 513 unrelated Japanese patients with schizophrenia and 705 healthy controls were examined. For the second-stage replication study, positive findings from the first stage were further investigated using a larger sample size, namely 1,854 patients with schizophrenia and 2,137 controls. The first-stage analysis showed significant associations among schizophrenia, intronic SNP rs165774, CNV6 situated at promoter 1, CNV8 at exon 6, and CNV9 at exon 7. The second-stage study showed that intronic SNP rs165774 (χ(2)  = 8.327, P = 0.0039), CNV6 (χ(2)  = 19.66, P = 0.00005), and CNV8 (χ(2)  = 16.57, P = 0.00025) were significantly associated with schizophrenia. Large and rare CNVs as well as low-frequency CNVs and relatively small CNVs, namely <30 kb in COMT, may be genetic risk factors for schizophrenia.

Linking early-life NMDAR hypofunction and oxidative stress in schizophrenia pathogenesis

Molecular, genetic and pathological evidence suggests that deficits in GABAergic parvalbumin-positive interneurons contribute to schizophrenia pathophysiology through alterations in the brain's excitation-inhibition balance that result in impaired behaviour and cognition. Although the factors that trigger these deficits are diverse, there is increasing evidence that they converge on a common pathological hub that involves NMDA receptor hypofunction and oxidative stress. These factors have been separately linked to schizophrenia pathogenesis, but evidence now suggests that they are mechanistically interdependent and contribute to a common schizophrenia-associated pathology.

Glutathione Deficit Affects the Integrity and Function of the Fimbria/Fornix and Anterior Commissure in Mice: Relevance for Schizophrenia

BACKGROUND

Structural anomalies of white matter are found in various brain regions of patients with schizophrenia and bipolar and other psychiatric disorders, but the causes at the cellular and molecular levels remain unclear. Oxidative stress and redox dysregulation have been proposed to play a role in the pathophysiology of several psychiatric conditions, but their anatomical and functional consequences are poorly understood. The aim of this study was to investigate white matter throughout the brain in a preclinical model of redox dysregulation.

METHODS

In a mouse model with impaired glutathione synthesis (Gclm KO), a state-of-the-art multimodal magnetic resonance protocol at high field (14.1 T) was used to assess longitudinally the white matter structure, prefrontal neurochemical profile, and ventricular volume. Electrophysiological recordings in the abnormal white matter tracts identified by diffusion tensor imaging were performed to characterize the functional consequences of fractional anisotropy alterations.

RESULTS

Structural alterations observed at peri-pubertal age and adulthood in Gclm KO mice were restricted to the anterior commissure and fornix-fimbria. Reduced fractional anisotropy in the anterior commissure (-7.5% ± 1.9, P<.01) and fornix-fimbria (-4.5% ± 1.3, P<.05) were accompanied by reduced conduction velocity in fast-conducting fibers of the posterior limb of the anterior commissure (-14.3% ± 5.1, P<.05) and slow-conducting fibers of the fornix-fimbria (-8.6% ± 2.6, P<.05). Ventricular enlargement was found at peri-puberty (+25% ± 8 P<.05) but not in adult Gclm KO mice.

CONCLUSIONS

Glutathione deficit in Gclm KO mice affects ventricular size and the integrity of the fornix-fimbria and anterior commissure. This suggests that redox dysregulation could contribute during neurodevelopment to the impaired white matter and ventricle enlargement observed in schizophrenia and other psychiatric disorders.

Associations of common copy number variants in glutathione S-transferase mu 1 and D-dopachrome tautomerase-like protein genes with risk of schizophrenia in a Japanese population

Oxidative-stress, genetic regions of interest (1p13 and 22q11), and common copy number variations (CNVs) may play roles in the pathophysiology of schizophrenia. In the present study, we confirmed associations between schizophrenia and the common CNVs in the glutathione (GSH)-related genes GSTT1, DDTL, and GSTM1 using quantitative real-time polymerase chain reaction analyses of 620 patients with schizophrenia and in 622 controls. No significant differences in GSTT1 copy number distributions were found between patient groups. However, frequencies of characterized CNVs and assumed gain alleles of DDTL and GSTM1 were significantly higher in patients with schizophrenia. In agreement with a previous report, the present data indicate that gains in the CNV alleles DDTL and GSTM1 are genetic risk factors in Japanese patients with schizophrenia, and suggest involvement of micro-inflammation and oxidative stress in the pathophysiology of schizophrenia.

Genetic Polymorphisms of Glutathione-Related Enzymes (GSTM1, GSTT1, and GSTP1) and Schizophrenia Risk: A Meta-Analysis

The association between polymorphisms of glutathione-related enzyme (GST) genes and the risk of schizophrenia has been investigated in many published studies. However, their results were inconclusive. Therefore, we performed a meta-analysis to explore the association between the GSTM1, GSTT1, and GSTP1 polymorphisms and the risk of schizophrenia. Twelve case-control studies were included in this meta-analysis. The odds ratio (OR) and 95% confidence interval (95% CI) were used to investigate the strength of the association. Our meta-analysis results revealed that GSTM1, GSTT1, and GSTP1 polymorphisms were not related to risk of schizophrenia (p > 0.05 in each model). Further analyses based on ethnicity, GSTM polymorphism showed weak association with schizophrenia in East Asian population (OR = 1.314, 95% CI = 1.025–1.684, p = 0.031). In conclusion, our meta-analysis indicated the GSTM1 polymorphism may be the only genetic risk factor for schizophrenia in East Asian population. However, more meta-analysis with a larger sample size were needed to provide more precise evidence.

Glutathione deficit impairs myelin maturation: relevance for white matter integrity in schizophrenia patients

Schizophrenia pathophysiology implies both abnormal redox control and dysconnectivity of the prefrontal cortex, partly related to oligodendrocyte and myelin impairments. As oligodendrocytes are highly vulnerable to altered redox state, we investigated the interplay between glutathione and myelin. In control subjects, multimodal brain imaging revealed a positive association between medial prefrontal glutathione levels and both white matter integrity and resting-state functional connectivity along the cingulum bundle. In early psychosis patients, only white matter integrity was correlated with glutathione levels. On the other side, in the prefrontal cortex of peripubertal mice with genetically impaired glutathione synthesis, mature oligodendrocyte numbers, as well as myelin markers, were decreased. At the molecular levels, under glutathione-deficit conditions induced by short hairpin RNA targeting the key glutathione synthesis enzyme, oligodendrocyte progenitors showed a decreased proliferation mediated by an upregulation of Fyn kinase activity, reversed by either the antioxidant N-acetylcysteine or Fyn kinase inhibitors. In addition, oligodendrocyte maturation was impaired. Interestingly, the regulation of Fyn mRNA and protein expression was also impaired in fibroblasts of patients deficient in glutathione synthesis. Thus, glutathione and redox regulation have a critical role in myelination processes and white matter maturation in the prefrontal cortex of rodent and human, a mechanism potentially disrupted in schizophrenia.

Inflammation in schizophrenia: A question of balance

In the past decade, there has been renewed interest in immune/inflammatory changes and their associated oxidative/nitrosative consequences as key pathophysiological mechanisms in schizophrenia and related disorders. Both brain cell components (microglia, astrocytes, and neurons) and peripheral immune cells have been implicated in inflammation and the resulting oxidative/nitrosative stress (O&NS) in schizophrenia. Furthermore, down-regulation of endogenous antioxidant and anti-inflammatory mechanisms has been identified in biological samples from patients, although the degree and progression of the inflammatory process and the nature of its self-regulatory mechanisms vary from early onset to full-blown disease. This review focuses on the interactions between inflammation and O&NS, their damaging consequences for brain cells in schizophrenia, the possible origins of inflammation and increased O&NS in the disorder, and current pharmacological strategies to deal with these processes (mainly treatments with anti-inflammatory or antioxidant drugs as add-ons to antipsychotics).

Peripheral markers of oxidative stress and antioxidative defense in euthymia of bipolar disorder--Gender and obesity effects

INTRODUCTION

Oxidative and nitrosative stress are implicated in the pathogenesis of uni- and bipolar disorder. Herein we primarily sought to characterize markers of oxidative/nitrosative stress during euthymia in adults with bipolar disorder (BD). Oxidative markers were further evaluated in this BD sample in synopsis with excess overweight or obesity and/or comorbid metabolic syndrome (MetS).

METHODS

Peripheral markers of oxidative stress [i.e. thiobarbituric acid reactive substance, (TBARS), malondialdehyde (MDA), and carbonyl proteins] and antioxidant markers [e.g. total antioxidative capacity (TAC), superoxide dismutase (SOD), glutathione S-transferase (GST)] were obtained in a cohort of euthymic adults with BD (N=113) and compared to healthy controls (CG) (N=78). Additionally, anthropometric measures included the body mass index (BMI) [kg/m(2)], waist and hip circumference [cm], waist-to-hip-ratio (WHR), waist to height ratio (WtHR) as well as the IDF-defined MetS.

RESULTS

The major finding was a significantly decreased TAC in BD compared to the CG (p<0.01; BD: M 1.18, SD 0.47; CG: M 1.39, SD 0.49). MDA was significantly and TBARS by trend higher in the CG compared to the euthymic bipolar test persons (MDA: p<0.01, BD: M 0.70, SD 0.18; CG: M 0.81, SD 0.25; TBARS: p<0.1, BD: M 0.78, SD 0.28; CG: M 0.76, SD 0.30). The antioxidative enzyme GST was significantly elevated in both patients and controls (BD: M 298.24, SD 133.02; CG: M 307.27 SD 118.18). Subgroup analysis revealed that the CG with concurrent MetS and obesity had significantly elevated TAC when compared to CG without concurrent MetS (p<0.05, no MetS: M 1.33, SD 0.50; MetS: M 1.67, SD 0.32), as well as persons with BD with or without current MetS (no MetS: M 1.18, SD 0.44; MetS: M 1.15, SD 0.49). Significant correlations between GST and anthropometric variables were found in male study participants. Multivariate analysis indicated a significant gender effect concerning TBARS values in all patients and CG (p<0.01, females: M 0.73, SD 0.29; males: M 0.83, SD 0.28).

CONCLUSION

Euthymic bipolar adults exhibit peripheral evidence of a disturbed biosignature of oxidative stress and antioxidative defense. Male test persons showed significantly higher peripheral markers of oxidative stress than women- female sex may exert protective effects. Furthermore, the biosignature of oxidative stress obtained herein was more pronounced in males with concurrent metabolic disorders. Our results further extend knowledge by introducing the moderating influence of gender and obesity on oxidative stress and BD.

Blood-based gene-expression biomarkers of post-traumatic stress disorder among deployed marines: A pilot study

The etiology of post-traumatic stress disorder (PTSD) likely involves the interaction of numerous genes and environmental factors. Similarly, gene-expression levels in peripheral blood are influenced by both genes and environment, and expression levels of many genes show good correspondence between peripheral blood and brain tissues. In that context, this pilot study sought to test the following hypotheses: (1) post-trauma expression levels of a gene subset in peripheral blood would differ between Marines with and without PTSD; (2) a diagnostic biomarker panel of PTSD among high-risk individuals could be developed based on gene-expression in readily assessable peripheral blood cells; and (3) a diagnostic panel based on expression of individual exons would surpass the accuracy of a model based on expression of full-length gene transcripts. Gene-expression levels in peripheral blood samples from 50 U.S. Marines (25 PTSD cases and 25 non-PTSD comparison subjects) were determined by microarray following their return from deployment to war-zones in Iraq or Afghanistan. The original sample was carved into training and test subsets for construction of support vector machine classifiers. The panel of peripheral blood biomarkers achieved 80% prediction accuracy in the test subset based on the expression of just two full-length transcripts (GSTM1 and GSTM2). A biomarker panel based on 20 exons attained an improved 90% accuracy in the test subset. Though further refinement and replication of these biomarker profiles are required, these preliminary results provide proof-of-principle for the diagnostic utility of blood-based mRNA-expression in PTSD among trauma-exposed individuals.

Altered oxygen metabolism associated to neurogenesis of induced pluripotent stem cells derived from a schizophrenic patient

Schizophrenia has been defined as a neurodevelopmental disease that causes changes in the process of thoughts, perceptions, and emotions, usually leading to a mental deterioration and affective blunting. Studies have shown altered cell respiration and oxidative stress response in schizophrenia; however, most of the knowledge has been acquired from postmortem brain analyses or from nonneural cells. Here we describe that neural cells, derived from induced pluripotent stem cells generated from skin fibroblasts of a schizophrenic patient, presented a twofold increase in extramitochondrial oxygen consumption as well as elevated levels of reactive oxygen species (ROS), when compared to controls. This difference in ROS levels was reverted by the mood stabilizer valproic acid. Our model shows evidence that metabolic changes occurring during neurogenesis are associated with schizophrenia, contributing to a better understanding of the development of the disease and highlighting potential targets for treatment and drug screening.