Marcos Leite Santoro

Effects of depression on the cytokine profile in drug naïve first-episode psychosis

Schizophrenia is accompanied by alterations in immuno-inflammatory pathways, including abnormalities in cytokine profile. The immune assessment of patients in a first episode of psychosis (FEP) and particularly in drug naïve patients is very important to further elucidate this association. The objectives of this study are to delineate the cytokine profile (IL-2, IL-10, IL-4, IL-6, IFNγ, TNFα and IL-17) in FEP patients (n=55) versus healthy controls (n=57) and to examine whether the presence of depressive symptoms in FEP is accompanied by a specific cytokine profile. We found increased levels of IL-6, IL-10 and TNFα in FEP patients when compared to healthy controls. FEP patients with depression showed higher IL-4 and TNFα levels versus those without depression. Cytokine levels were not correlated to the total PANSS and the positive or negative subscale scores. Our results suggest that FEP is accompanied by a cytokine profile indicative of monocytic and T regulatory cell (Treg) activation. Depression in FEP is accompanied by monocytic and Th-2 activation, whereas FEP without depression is characterized by Treg activation only. In conclusion, depression emerged as a key component explaining the cytokines imbalance in FEP that is responsible for a large part of the immune-inflammatory abnormalities described.

DRD1 rs4532 polymorphism: A potential pharmacogenomic marker for treatment response to antipsychotic drugs

We investigated the association of dopamine receptor D1 gene (DRD1) rs4532 polymorphism with antipsychotic treatment response in schizophrenia. We have analyzed 124 patients with schizophrenia, consisting of 59 treatment resistant (TR) and 65 non-TR. We found an association between G-allele and TR schizophrenia (p=0.001; adjusted OR=2.71). Setting the common AA-genotype as reference, the GG-homozygous presented a five-fold risk compared to AA-homozygous (p=0.010; OR=5.56) with an intermediate result for AG-genotype (p=0.030; adjusted OR=2.64). The DRD1 rs4532 polymorphism showed a dose-response gradient with increased risk for treatment resistance and may be a potential pharmacogenetic marker for antipsychotic drug treatment response.

Changes in gene expression and methylation in the blood of patients with first-episode psychosis

Schizophrenia is a severe mental health disorder with high heritability. The investigation of individuals during their first-episode psychosis (FEP), before the progression of psychotic disorders and especially before treatment with antipsychotic medications, is particularly helpful for understanding this complex disease and for the identification of potential biomarkers. In this study, we compared the expression of genes that are involved in neurotransmission and neurodevelopment of antipsychotic-naive FEP in the peripheral blood of patients (n=51) and healthy controls (n=51). In addition, we investigated the differentially expressed genes with respect to a) DNA methylation, b) the correlation between gene expression and clinical variables (PANSS), and c) gene expression changes after risperidone treatment. Expression levels of 11 genes were quantified with SYBR Green. For methylation analysis, bisulfite sequencing was performed. A significant decrease in GCH1 mRNA levels was observed in FEP patients relative to controls. Also, when we compare the FEP patients after risperidone treatment with controls, this difference remains significant, and no significant differences were observed in GCH1 mRNA levels when comparing patients before and after risperidone treatment. Additionally, although the differences were non-significant after Bonferroni correction, the expression of GCH1 seemed to be correlated with PANSS scores, and the GCH1 promoter region was more methylated in FEP than in controls, thus corroborating the results obtained at the mRNA level. Few studies have been conducted on GCH1, and future studies are needed to clarify its potential role in the progression of schizophrenia.

Depression, Cytokine, and Cytokine by Treatment Interactions Modulate Gene Expression in Antipsychotic Naive First Episode Psychosis

In schizophrenia, genetic and environmental factors affect neurodevelopment and neuroprogressive trajectory. Altered expression of neuro-immune genes and increased levels of cytokines are observed, especially in patients with comorbid depression. However, it remains unclear whether circulating levels of cytokines and expression of these genes are associated, and how antipsychotic treatments impact this association. Relationships between messenger RNA (mRNA) expression of 11 schizophrenia-related genes and circulating levels of cytokines (interleukin (IL)-6, IL-10, and tumor necrosis factor (TNF)-α) were analyzed in 174 antipsychotic naïve first episode psychosis (FEP) and in 77 healthy controls. A subgroup of 72 patients was reassessed after treatment with risperidone. FEP patients were divided into those with and without depression. FEP patients with depression showed increased COMT expression and decreased NDEL1 expression. Increased IL-6 was associated with lowered AKT1 and DROSHA expression, while increased IL-10 was associated with increased NDEL1, DISC1, and MBP expression. IL-6 levels significantly increased the risperidone-induced expression of AKT1, DICER1, DROSHA, and COMT mRNA. The differential mRNA gene expression in FEP is largely associated with increased cytokine levels. While increased IL-6 may downregulate AKT-mediated cellular functions and dysregulate genes involved in microRNA (miRNA) machinery, increased IL-10 has neuroprotective properties. Increased IL-6 levels may prime the expression of genes (AKT1, DICER1, DROSHA, and COMT) in response to risperidone, suggesting that cytokine × treatment × gene interactions may improve cell function profiles. FEP patients with depression show a different gene expression profile reinforcing the theory that depression in FEP is a different phenotype.

Effect of antipsychotic drugs on gene expression in the prefrontal cortex and nucleus accumbens in the spontaneously hypertensive rat (SHR)

Antipsychotic drugs (APDs) are the standard treatment for schizophrenia. The therapeutic effect of these drugs is dependent upon the dopaminergic D2 blockade, but they also modulate other neurotransmitter pathways. The exact mechanisms underlying the clinical response to APDs are not fully understood. In this study, we compared three groups of animals for the expression of 84 neurotransmitter genes in the prefrontal cortex (PFC) and nucleus accumbens (NAcc). Each group was treated with a different APD (risperidone, clozapine or haloperidol), and with a non-treated group of spontaneously hypertensive rats (SHRs), which is an animal model for schizophrenia. This study also explored whether or not differential expression was regulated by DNA methylation in the promoter region (PR). In the clozapine group, we found that Chrng was downregulated in the NAcc and six genes were downregulated in the PFC. In the haloperidol group, Brs3 and Glra1 were downregulated, as was Drd2 in the clozapine group and Drd3, Galr3 and Gabrr1 in the clozapine and haloperidol groups. We also encountered four hypermethylated CG sites in the Glra1 PR, as well as three in the risperidone group and another in the haloperidol group, when compared to non-treated rats. Following the APD treatment, the gene expression results revealed the involvement of genes that had not previously been described, in addition to the activity of established genes. The investigation of the involvement of these novel genes can lead to better understanding about the specific mechanisms of action of the individual APDs studied.

Evaluation of neurotransmitter receptor gene expression identifies GABA receptor changes: A follow-up study in antipsychotic-naïve patients with first-episode psychosis

A study of the gene expression levels in the blood of individuals with schizophrenia in the beginning of the disease, such as first-episode psychosis (FEP), is useful to detect gene expression changes in this disorder in response to treatment. Although a large number of genetic studies on schizophrenia have been conducted, little is known about the effects of antipsychotic treatment on gene expression. The aim of the present study was to examine differences in the gene expression in the blood of antipsychotic-naïve FEP patients before and after risperidone treatment (N = 44) and also to verify the correlation with treatment response. In addition, we determined the correlations between differentially expressed genes and clinical variables. The expression of 40 neurotransmitter and neurodevelopment-associated genes was assessed using the RT2 Profiler PCR Array. The results indicated that the GABRR2 gene was downregulated after risperidone treatment, but no genes were associated with response to treatment and clinical variables after Bonferroni correction. GABRR2 downregulation after treatment can both suggest an effect of risperidone treatment or processes related to disease progression, either not necessarily associated with the improvement of symptoms. Despite this change was observed in blood, this decrease in GABRR2 mRNA levels might be an effect of changes in GABA concentrations or other systems interplay consequently to D2 blockage induced by risperidone, for example. Thus, it is important to consider that antipsychotics or the progression of psychotic disorders might interfere with gene expression.

Expression profile of neurotransmitter receptor and regulatory genes in the prefrontal cortex of spontaneously hypertensive rats: Relevance to neuropsychiatric disorders

The spontaneously hypertensive rat (SHR) strain was shown to be a useful animal model to study several behavioral, pathophysiological and pharmacological aspects of schizophrenia and attention-deficit/hyperactivity disorder. To further understand the genetic underpinnings of this model, our primary goal in this study was to compare the gene expression profile of neurotransmitter receptors and regulators in the prefrontal cortex (PFC) and nucleus accumbens (NAcc) of SHR and Wistar rats (control group). In addition, we investigated DNA methylation pattern of promoter region of the genes differentially expressed. We performed gene expression analysis using a PCRarray technology, which simultaneously measures the expression of 84 genes related to neurotransmission. Four genes were significantly downregulated in the PFC of SHR compared to Wistar rats (Gad2, Chrnb4, Slc5a7, and Qrfpr) and none in nucleus accumbens. Gad2 and Qrfpr have CpG islands in their promoter region. For both, the promoter region was hypomethylated in SHR group, and probably this mechanism is not related with the downregulation of these genes. In summary, we identified genes that are downregulated in the PFC of SHR, and might be related to the behavioral abnormalities exhibited by this strain.

ZDHHC8 gene may play a role in cortical volumes of patients with schizophrenia

ZDHHC8 rs175174 polymorphism is located in 22q11.2 region and its role in brain volume has not been fully addressed. A total of 282 schizophrenia patients and 379 controls were genotyped. A sample of 138 patients underwent brain MRI scan. No association was found between schizophrenia and genotypes. Nevertheless, GG-genotype carriers presented gray matter volume (GMV) reduction in frontal lobe compared to A-allele carriers, and cerebellar hemispheres GMV reductions were found in G-allele carriers compared to AA-genotype. Moreover, A-allele carriers presented posterior brain GMV reductions when compared to GG-genotype. These data suggest that ZDHHC8 may play a role in cortical volumes.

Neurotransmitter receptor and regulatory gene expression in peripheral blood of Brazilian drug-naïve first-episode psychosis patients before and after antipsychotic treatment.

Little is known about how genes expressed in blood relate to schizophrenia or antipsychotic use. We analyzed gene expression in 10 first-episode psychosis patients and nine controls using PCR Arrays. GABRR2 and CHRNA3 were found to be differentially expressed after risperidone treatment. These genes may be regulated by antipsychotic use.

Gene expression alterations related to mania and psychosis in peripheral blood of patients with a first episode of psychosis.

Psychotic disorders affect ~3% of the general population and are among the most severe forms of mental diseases. In early stages of psychosis, clinical aspects may be difficult to distinguish from one another. Undifferentiated psychopathology at the first-episode of psychosis (FEP) highlights the need for biomarkers that can improve and refine differential diagnosis. We investigated gene expression differences between patients with FEP–schizophrenia spectrum (SCZ; N=53) or FEP–Mania (BD; N=16) and healthy controls (N=73). We also verified whether gene expression was correlated to severity of psychotic, manic, depressive symptoms and/or functional impairment. All participants were antipsychotic-naive. After the psychiatric interview, blood samples were collected and the expression of 12 psychotic-disorder-related genes was evaluated by quantitative PCR. AKT1 and DICER1 expression levels were higher in BD patients compared with that in SCZ patients and healthy controls, suggesting that expression of these genes is associated more specifically to manic features. Furthermore, MBP and NDEL1 expression levels were higher in SCZ and BD patients than in healthy controls, indicating that these genes are psychosis related (independent of diagnosis). No correlation was found between gene expression and severity of symptoms or functional impairment. Our findings suggest that genes related to neurodevelopment are altered in psychotic disorders, and some might support the differential diagnosis between schizophrenia and bipolar disorder, with a potential impact on the treatment of these disorders.