Reduced serum TNF alpha level in chronic schizophrenia patients with or without tardive dyskinesia

Immunosenescence-related T cell phenotypes and white matter in schizophrenia patients with tardive dyskinesia

Schizophrenia patients with tardive dyskinesia (TD) are associated with accelerated biological aging, immunological dysfunction, and premature morbidity and mortality. Older individuals are particularly vulnerable to TD development. As a characteristic of immunosenescence, alterations in the relative proportions of naïve or memory T cell subpopulations may be negatively or positively associated with brain structure abnormalities; however, whether these changes are correlated with TD remains unclear. In this study, we investigated correlations between distributions of T cell phenotypes and brain structure abnormalities (especially white matter) in schizophrenia patients with (TD) and without (NTD) TD (n = 50 and 58, respectively) relative to healthy controls (HC, n = 41). Immune markers, including naïve (CD45RA+), memory (CD45RO+), and apoptotic (CD95+) CD4+ and CD8+ T cells, were examined by flow cytometry, as were the intracellular levels of cytokines (interferon (IFN)-γ, interleukin (IL)-6, IL-1β, and tumor necrosis factor (TNF)-α) in CD8 + CD45RA + CD95+ and CD8 + CD45RO + CD95+ T cells. MRI was employed to evaluate the fractional anisotropy (FA) of white matter tracts and subcortical volumes, following published routines. The percentage of CD8 + CD45RO + CD95+ T cells was higher in TD compared with NTD and HC groups and correlated with the choroid plexus volume in TD group. The intracellular level of IFN-γ in CD8 + CD45RO + CD95+ T cells, the FA of the fornix/stria terminalis, and the pallidum volume were correlated with orofacial TD, whereas the FAs of the inferior fronto-occipital fasciculus, cingulum, and superior longitudinal fasciculus were correlated with limb-truncal TD. These findings provide preliminary evidence that the association between immunosenescence-related T cell subpopulations and brain structure may underline the pathological process of TD.

Analysis of schizophrenia-associated genetic markers in the HLA region as risk factors for tardive dyskinesia

OBJECTIVES

The pathology of Tardive Dyskinesia (TD) has yet to be fully understood, but there have been proposed hypotheses for the cause of this condition. Our team previously reported a possible association of TD with the Complement Component C4 gene in the HLA region. In this study, we explored the HLA region further by examining two previously identified schizophrenia-associated HLA-region single-nucleotide polymorphisms (SNPs), namely rs13194504 and rs210133.

METHODS

The SNPs rs13194504 and rs210133 were tested for association with the occurrence and severity of TD in a sample of 172 schizophrenia patients who were recruited for four studies from three different clinical sites in Canada and USA.

RESULTS

The rs13194504 AA genotype was associated with decreased severity for TD as measured by Abnormal Involuntary Movement Scale (AIMS) scores (p = 0.047) but not for TD occurrence. SNP rs210133 was not significantly associated with either TD occurrence or AIMS scores.

CONCLUSION

Our findings suggest that the rs13194504 AA genotype may play a role in TD severity, while SNP rs210133 may not have a major role in the risk or severity of TD.

Acute ketamine induces neuronal hyperexcitability and deficits in prepulse inhibition by upregulating IL-6

Acute ketamine administration results in psychotic symptoms similar to those observed in schizophrenia and is regarded as a pharmacological model of schizophrenia. Accumulating evidence suggests that patients with schizophrenia show increased IL-6 levels in the blood and cerebrospinal fluid and that IL-6 levels are associated with the severity of psychotic symptoms. In the present study, we found that a single ketamine exposure led to increased expression of IL-6 and IL-6Rα, decreased dendritic spine density, increased expression and currents of T-type calcium channels, and increased neuron excitability in the hippocampal CA1 area 12 h after exposure. Acute ketamine administration also led to impaired prepulse inhibition (PPI) 12 h after administration. Additionally, we found that the expression of signaling molecules IKKα/β, NF-κB, JAK2, and STAT3 was upregulated 12 h after a single ketamine injection. The decreases in dendritic spine density, the increases in calcium currents and neuron excitability, and the impairments in PPI were ameliorated by blocking IL-6 or IL-6Rα. Our findings show that blocking IL-6 or its receptor may protect hippocampal neurons from hyperexcitability, thereby ameliorating ketamine-induced psychotic effects. Our study provides additional evidence that targeting IL-6 and its receptor is a potential strategy for treating psychotic symptoms in acute ketamine-induced psychosis and schizophrenia.

Neutrophil gelatinase-associated lipocalin (NGAL) and inflammatory markers in schizophrenia: A comparative analysis of drug-naive schizophrenia patients, remitted patients, and healthy controls

This study aims to examine the plasma concentrations of NGAL and other inflammatory parameters, including TNF-α, IL-1β, and IFN-γ, in schizophrenia patients and healthy volunteers. It also investigates potential associations between these biomarkers and symptom severity in schizophrenia and the utility of NGAL as a potential diagnostic and monitoring biomarker for schizophrenia. The study included 49 drug-naive schizophrenia patients (DNS), 59 patients with schizophrenia in remission (REM) on antipsychotic treatment, and 58 healthy volunteers (HC). The Positive and Negative Symptoms Evaluation Scale (PANSS) was utilized to assess the severity of symptoms in schizophrenia patients. Plasma levels of TNF-α, IL-1β, IFN-γ, and NGAL were measured for all participants. NGAL levels were significantly lower in the DNS group than in HC. Significantly lower TNF-α levels were observed in both the DNS and REM groups compared to the HC group. Notably, a statistically significant positive correlation was detected between TNF-α and NGAL levels. The findings of this study are noteworthy, as they demonstrate that drug-naive individuals with schizophrenia exhibit significantly diminished levels of NGAL and TNF-α compared to healthy controls. These identified biomarkers hold promise for providing valuable insights into the complex and evolving pathophysiology of schizophrenia.

Putative role of immune reactions in the mechanism of tardive dyskinesia

The term extrapyramidal disorders is most often used for conditions such as Parkinson's disease or Huntington's disease, but also refers to a group of extrapyramidal side effects of antipsychotics (EPS), such as tardive dyskinesia (TD). After a brief description of some clinical features of TD, this article summarizes the relatively scarce results of research on a possible link between mainly cytokine levels and TD. This data was found by systematically searching Pubmed and Embase. The limitations of these types of studies are a major obstacle to interpretation. After describing relevant aspects of the neuroinflammatory response and the neuroanatomical backgrounds of EPS, a new hypothesis for the origin of TD is presented with emphasis on dysfunctions in the striosomal compartment of the striatum and the dorsal diencephalic connection system (DDCS). It is postulated that (partly immunologically-induced) increase in oxidative stress and the dopamine-dependent immune response in classic TD proceed primarily via the DDCS, which itself is activated from evolutionarily older parts of the forebrain. Neuroinflammatory responses in the choroid plexus of the third ventricle may contribute due to its proximity to the habenula. It is concluded that direct evidence for a possible role of inflammatory processes in the mechanism of TD is still lacking because research on this is still too much of a niche, but there are indications that warrant further investigation.

Dysfunctional monocytic toll-like receptor 4 signaling pathway and cognitive deficits in chronic schizophrenia patients with tardive dyskinesia

BACKGROUND

Mounting evidence suggests that the innate immune system is disrupted in schizophrenia patients with tardive dyskinesia (TD); however, the role of the toll-like receptor 4 (TLR4) signaling pathway remains unclear METHODS: In this study, we quantified the expression of the monocytic TLR4 signaling pathway using flow cytometry, before and after lipopolysaccharide (LPS) stimulation, in chronic schizophrenia patients with (n=61) and without TD (NTD, n=61) and healthy controls (HCs, n=74). Psychopathological symptoms, the severity of TD, and cognitive function were assessed using the Positive and Negative Syndrome Scale (PANSS), Abnormal Involuntary Movement Scale (AIMS), and MATRICS Consensus Cognitive Battery (MCCB), respectively RESULTS: 1) Both TD and NTD patients showed higher TLR4 signaling pathway activity at baseline than that in HCs, but their responses to LPS were weaker than those in HCs; 2) the alteration of the TLR4 signaling pathway was less severe in TD patients than in NTD patients; 3) TLR4 levels and MCCB scores were negatively correlated at baseline but positively correlated after LPS stimulation in TD patients; 4) there was no correlation between the TLR4 signals and PANSS or AIMS scores.

CONCLUSIONS

Our findings suggested the TLR4 signaling pathway disturbance might be related to cognitive deficits in schizophrenia patients with TD.

N-methyl-D-aspartate receptor antibody and the choroid plexus in schizophrenia patients with tardive dyskinesia

BACKGROUND

Immune disturbance has been postulated to be one of the mechanisms underlying the pathogenesis of tardive dyskinesia (TD). Recently, the role of autoimmune abnormality in TD has been increasingly recognized. Autoantibodies against neuronal N-methyl-D-aspartate receptor (NMDAR) may be cross-reactive in the brain in neuropsychiatric disorders, and the choroid plexus (CP) is a crucial immune barrier in the central nervous system (CNS). We supposed that NMDAR antibodies might underlie the pathophysiological process of TD through the mediation of CP.

METHODS

Serum NMDAR antibody levels were assessed by enzyme-linked immunosorbent assay, CP and ventricle volumes were assessed by magnetic resonance imaging in schizophrenia patients with TD (n = 61), without TD (NTD, n = 61), and in healthy controls (n = 74). Psychopathology and TD severity were assessed by the Positive and Negative Syndrome Scale and Abnormal Involuntary Movement Scale (AIMS).

RESULTS

NMDAR antibody levels were significantly higher, CP volumes were larger in the TD group than in the NTD group (p = 0.022; p = 0.019, respectively). In the TD group, higher NMDAR antibody level was correlated with larger CP volume (β = 0.406, p = 0.002). An elevated NMDAR antibody level and enlarged CP volume were correlated with orofacial AIMS score (β = 0.331, p = 0.011; β = 0.459, p = 3.34 × 10^-4, respectively). In a mediation model, the effect of NMDAR antibody level on the orofacial AIMS score was mediated by the CP volume (indirect effect: β = 0.08, 95% confidence interval = 0.002-0.225; direct effect: β = 0.14, p = 0.154).

CONCLUSIONS

Our findings highlight a potential NMDAR antibody-associated mechanism in orofacial TD, which may be mediated by increased CP volume.

Cytokine Level and Symptoms of Schizophrenia

BACKGROUND: The study was intended to find one of the cytokines, that is, tumor necrosis factor (TNF)-alpha correlation with PANSS scores of people with schizophrenia (PwS) and their differences compared to the healthy people of Malayan- Mongoloid Race. AIM: The aim of this study was providing a profile of TNF-alpha level in PwS of Malayan-Mongoloid race and its correlation with positive and negative symptoms in schizophrenia. METHODS: It was conducted using cross-sectional and following sampling methods, with inclusion and exclusion criteria set for the PwS and control groups. RESULTS: The result was no correlation between TNF-alpha levels with PANSS scores on PwS (p > 0.005), with very weak correlation and positive correlation direction, and there were differences in TNF-alpha levels.between PwS and control groups. CONCLUSION: It can be concluded that the higher levels of TNF-alpha would impact on the severity symptoms experienced by PwS.

Interaction between TNF-α and oxidative stress status in first-episode drug-naïve schizophrenia

There has been evidence that the disturbances of TNF-α and the oxidative stress (OxS) status are involved in the mechanism of schizophrenia. However, the results of their levels in schizophrenia are still controversial, and their interactions have not yet been examined, especially in first-episode drug-naïve (FEDN) patients. We therefore applied Enzyme-linked immunosorbent assays (ELISAs) method to compare peripheral blood serum TNF-α, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), and malondialdehyde (MDA) levels in 119 FEDN patients with schizophrenia and 135 healthy controls. We found that TNF-α and MDA were higher, whereas GSH-Px was lower, in FEDN patients with schizophrenia compared to healthy controls (TNF-α, 2.21 ± 0.33 vs. 2.11 ± 0.36, Bonferroni p = 0.04; MDA, 2.95 ± 0.87 vs. 2.68 ± 0.76, Bonferroni p = 0.04, GSH-Px, 177.33 ± 28.84 vs. 188.32 ± 29.34, Bonferroni p = 0.03). Furthermore, TNF-α levels had an independent positive association with negative symptoms (r = 0.37, Bonferroni p < 0.001). Finally, GSH-Px levels were negatively associated with the presence of schizophrenia (B =-0.014, Wald statistic = 9.22, p = 0.002, 95 %CI = 0.97-0.99), while the interaction of TNF-α with MDA was a risk factor for schizophrenia (B = 0.22, Wald statistic = 10.06, p = 0.002, 95 %CI = 1.09-1.43). Our results suggest that TNF-α and disturbance of oxidative stress status as well as their interaction may be involved in the pathophysiology of schizophrenia.

Association Study of the Complement Component C4 Gene in Tardive Dyskinesia

Tardive dyskinesia (TD) is a movement disorder that may develop in schizophrenia patients being treated long-term with antipsychotic medication. TD interferes with voluntary movements and leads to stigma, and can be associated with treatment non-adherence. The etiology of TD is unclear, but it appears to have a genetic component. There is emerging evidence of immune dysregulation in TD. In the current study, we set out to investigate the complex schizophrenia-associated complement component 4 (C4) gene for possible association with TD occurrence and TD severity as assessed by the Abnormal Involuntary Movement Scale (AIMS) in a sample of 129 schizophrenia patients of European ancestry. We have genotyped the copy numbers of long and short forms of C4A and C4B gene variants in 129 European ancestry patients with schizophrenia or schizoaffective disorder. We did not find predicted C4A or C4B expression to be nominally associated with TD risk or severity. However, we found the number of copies of C4BL to be nominally associated with TD severity (p = 0.020).

Cytokine Alterations in Schizophrenia: An Updated Review

Schizophrenia, a multisystem disorder with an unknown etiology, is associated with several immune dysfunctions, including abnormal levels of circulating cytokines. In this review, we investigated the changes of cytokines in schizophrenic patients, their connection with behavioral symptoms severity and their potential clinical implications. We also assessed the possible causative role of abnormal cytokine levels in schizophrenia pathogenesis. Based on meta-analyses, we categorized cytokines according to their changes in schizophrenic patients into four groups: (1) increased cytokines, including interleukin (IL)-6, tumor necrosis factor (TNF)-α, IL-1β, IL-12, and transforming growth factor (TGF)-β, (2) non-altered cytokines, including IL-2, IL-4, and IL-17, (3) increased or non-altered cytokines, including IL-8 and interferon (IFN)-γ, and (4) IL-10 with increased, decreased, and non-altered levels. Notably, alterations in cytokines may be variable in four different categories of SP, including first-episode and drug-naïve, first-episode and non-drug-naïve, stable chronic, and chronic in acute relapse. Furthermore, disease duration, symptoms severity, incidence of aggression, and cognitive abilities are correlated with levels of certain cytokines. Clinical implications of investigating the levels of cytokine in schizophrenic patients include early diagnosis, novel therapeutic targets development, patient stratification for choosing the best therapeutic protocol, and predicting the prognosis and treatment response. The levels of IL-6, IL-8, IFN-γ, IL-2 are related to the treatment response. The available evidence shows a potential causative role for cytokines in schizophrenia development. There is a substantial need for studies investigating the levels of cytokines before disease development and delineating the therapeutic implications of the disrupted cytokine levels in schizophrenia.

Changes in serum TNF-α, IL-18, and IL-6 concentrations in patients with chronic schizophrenia at admission and at discharge

OBJECTIVE

Schizophrenia is correlated with aberrant cytokine concentrations. The goal of our study was to detect the serum concentrations of tumor necrosis factor (TNF)-α, interleukin (IL)-18, and IL-6 concentrations in patients with chronic schizophrenia in the acute relapse state at admission and at discharge and to analyze the correlations between the three cytokine concentrations with psychosis symptoms.

METHODS

Enzyme-linked immunosorbent assay (ELISA) was used to analyze serum concentrations of TNF-α, IL-18, and IL-6 in 68 patients with chronic schizophrenia at admission and at discharge and in 80 controls. The Positive and Negative Syndrome Scale (PANSS) was used to analyze psychosis symptoms of the patients.

RESULTS

Serum concentrations of TNF-α, IL-18, and IL-6 in patients at admission were significantly elevated compared to those in controls. After treatment, IL-6 concentrations in patients at discharge were significantly reduced compared to those in patients at admission, and IL-6 concentrations showed no significant difference between patients at discharge and controls. In contrast, TNF-α and IL-18 concentrations showed no significant difference between patients at discharge and patients at admission, and TNF-α and IL-18 concentrations in patients at discharge were still significantly elevated compared to those in controls. IL-6 concentrations in patients at admission showed a positive correlation with negative scores, and IL-6 concentrations in patients at discharge showed positive correlations with positive, negative, and total scores. Reduction in IL-6 concentrations showed positive correlations with reduction in positive, negative, and total scores in patients at discharge.

CONCLUSION

Serum concentrations of TNF-α, IL-18, and IL-6 were significantly elevated in patients with chronic schizophrenia in the acute relapse state. After treatment, IL-6 concentrations in patients at discharge were significantly reduced compared to these in patients at admission.

Serum levels of TNF-alpha in patients with chronic schizophrenia during treatment augmentation with sarcosine (results of the PULSAR study)

Sarcosine, glycine transporter inhibitor, increases glycine levels around NMDA receptor, improving primary negative symptoms of schizophrenia. The aim of our study was to find a potential relationship between initial TNF-alpha level, its changes and schizophrenia symptoms severity, resulting from adding sarcosine to a stable antipsychotic treatment. Sixty subjects with stable schizophrenia were randomized to receive either 2 g of sarcosine or placebo and completed a 6-month, double blind, placebo-controlled study. Three patients on sarcosine and one taking placebo did not complete TNF-alpha tests, planned at the beginning, after 6 weeks and after 6 months. For clinical assessments we used PANSS and CDSS scales. No changes in TNF-alpha serum concentrations in both groups at any time-points was noted. The sarcosine group achieved significant improvement in negative symptoms, general psychopathology and total PANSS score group, however without any significant correlations between TNF-alpha levels and PANSS scores in all assessments. Positive correlations between TNF-alpha levels and CDSS score were found in the placebo group and total study group. Initial TNF-alpha concentrations cannot be used as a predictor of the improvement resulting from adding sarcosine. Sarcosine does not significantly affect TNF-alpha levels. TNF-alpha may be involved in mechanisms related to depressive symptomatology in schizophrenia.

Decreased Gray Matter Volume of Cuneus and Lingual Gyrus in Schizophrenia Patients with Tardive Dyskinesia is Associated with Abnormal Involuntary Movement

Tardive dyskinesia (TD) is a devastating motor disorder associated with the etiological process of schizophrenia or antipsychotic medication treatments. To examine whether cerebral morphological changes may manifest in TD, we used voxel-based morphometry to analyze high-resolution T1-weighted brain structural magnetic resonance images from 32 schizophrenics with TD (TD group), 31 schizophrenics without TD (non-TD group), and 32 healthy controls (HC group). We also assessed psychopathological symptoms with the Positive and Negative Syndrome Scale (PANSS), and TD severity with the Abnormal Involuntary Movement Scale (AIMS). We compared gray matter volumes (GMVs) among groups, and tested for correlations between GMV changes and psychopathological symptoms or TD severity. The results showed significant differences in GMV in the frontal and temporal cortices, insula and cerebellum among the three groups. Brainstem and inferior frontal and precentral gyri GMVs were significantly larger, whereas cuneus and lingual gyrus GMVs were significantly smaller in the TD group as compared to non-TD group. Further, the cuneus and lingual gyrus GMVs were positively correlated with AIMS scores in the TD group. The current results suggest that TD may be associated with the alterations in GMV that are different from that of schizophrenics without TD. Further studies are needed to confirm and to examine the functional significance of these structural findings.

Serum TNF-related weak inducer of apoptosis (TWEAK) and TNF-related apoptosis-inducing ligand (TRAIL) levels of patients with bipolar disorder in manic episode, in remission and healthy controls

TNF-related weak inducer of apoptosis (TWEAK) and TNF-related apoptosis-inducing ligand (TRAIL) are members of TNF superfamily, which has various roles in immunologic and inflammatory reactions in the organism. Pathophysiology in bipolar disorder is still under investigation and altered serum levels of cytokines are often encountered. Aim of this study is to detect serum TWEAK and TRAIL levels of patients with bipolar disorder and healthy controls. For this purpose, 55 patients with bipolar disorder -27 manic episode (ME), 28 remission (RE) and 29 healthy controls (HC) were included. TWEAK levels of ME and RE groups were significantly lower than HC. TWEAK levels of bipolar patients (BP) were also lower than HC. TRAIL levels of ME, RE, HC groups and BP, HC groups were statistically similar. In our knowledge, this is the first study concerning about TWEAK and TRAIL levels in bipolar disorder and our results pointed that TWEAK-related immune response might be impaired in bipolar disorder, but our study fails to eradicate the confounders such as medication, smoking and body mass index. Studies having larger samples and limited confounders are needed to be able to evaluate these changes better and detect possible alterations about TRAIL and other TNF superfamily members.

Redox dysregulation, immuno-inflammatory alterations and genetic variants of BDNF and MMP-9 in schizophrenia: Pathophysiological and phenotypic implications

BACKGROUND

Although a clear mechanism underlying the pathophysiology of schizophrenia (SZ) remains elusive, oxidative stress, inflammatory syndrome and immune activation have become an attractive hypothesis for explaining the pathophysiology of SZ. Data from prior studies on the role of matrix metalloproteinase 9 (MMP-9) and brain-derived neurotrophic factor (BDNF) single nucleotide polymorphisms (SNPs) in SZ are contradictory. We aimed to investigate whether oxidative stress, inflammatory and immune activation markers as well as MMP-9 levels may be implicated in SZ pathogenesis. The association of MMP-9 and BDNF SNPs with the clinical expression of SZ was examined.

SUBJECTS AND METHODS

Ninety-four subjects were recruited, including 44 SZ patients and 50 healthy controls. Serum levels of thiobarbituric acid reactive substances (TBARS), protein carbonyl content (PCC), nitrite, C-reactive protein (CRP), interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-α), Beta-2 microglobulin (Β2M), complement component 3 (C3), C4 and MMP-9 were measured. The MMP-9 -1562C>T and BDNF196G>A SNPs were genotyped using polymerase chain reaction-restriction fragment length polymorphism assay. Psychopathology was assessed using the positive and negative syndrome scale (PANSS).

RESULTS

SZ patients showed significantly higher TBARS, PCC, nitrite, CRP, IL-6, TNF-α, Β2M, C3 and MMP-9 levels than controls. In distinguishing SZ patients from healthy controls, CRP and MMP-9 yielded similar discriminatory performance, and both perform better than IL-6, Β2M, C3, nitrite, TBARS, PCC, TNF-α and C4. The MMP-9 -1562C>T SNP genotypes distribution didn't differ significantly between controls and SZ patients. As compared to controls, SZ patients harbor a significantly higher frequency of the BDNF196GG genotype and a lower frequency of the BDNF196GA/AA genotype. Patients carrying the MMP-9 -1562CC or BDNF196GG genotype revealed a significantly higher PANSS than those carrying MMP-9 -1562CT/TT or BDNF196GA/AA genotype. Male gender and the MMP-9 -1562CC genotype were identified as independent predictive factors for higher PANSS.

CONCLUSIONS

Redox dysregulation and alterations in the immuno-inflammatory pathways are major culprits in the pathogenesis of SZ. MMP-9 and BDNF SNPs are associated with the clinical phenotype of SZ and, thus, may be a useful marker predicting the phenotypic expression and prognosis of SZ patients.

Tumor necrosis factor-α and -β genetic polymorphisms as a risk factor in Saudi patients with schizophrenia

BACKGROUND

Schizophrenia is one of the most common devastating psychiatric disorders that negatively affects the quality of life and psychosocial functions. Its etiology involves the interplay of complex polygenic influences and environmental risk factors. Inflammatory markers are well-known etiological factors for psychiatric disorders, including schizophrenia.

OBJECTIVE

The aim of this study was to investigate the association of proinflammatory cytokine genes, tumor necrosis factor (TNF)-α (-308G/A) and TNF-β (+252A/G) polymorphisms with schizophrenia susceptibility.

SUBJECTS AND METHODS

TNF-α and TNF-β genes were amplified using amplification refractory mutation system primers in 180 schizophrenia patients and 200 healthy matched controls recruited from the Psychiatry Clinic of Prince Sultan Military Medical City, Riyadh. The frequencies of alleles and genotypes of TNF-α (-308G/A) and TNF-β (+252A/G) polymorphisms in patients were compared with those in controls.

RESULTS

The frequencies of TNF-α (-308) allele A and genotype GA were significantly higher, while those of allele G and genotype GG were lower in schizophrenia patients as compared to controls, indicating that genotype GA and allele A of TNF-α (-308G/A) may increase susceptibility to schizophrenia, while genotype GG and allele G may reduce it. On the other hand, the distribution of alleles and genotypes of TNF-β (+252A/G) polymorphism does not differ significantly in patients from controls; however, the frequency of genotype GG of TNF-β (+252A/G) was significantly higher in male patients than in female patients. The distribution of TNF-α (-308G/A) and TNF-β (+252A/G) polymorphisms was almost similar in schizophrenia patients with negative or positive symptoms.

CONCLUSION

TNF-α (-308G/A) and TNF-β (+252G/A) polymorphisms may increase the susceptibility to schizophrenia in Saudi patients and could be a potential risk factor for its etiopathogenesis. However, further studies are warranted involving a larger sample size to strengthen our findings.

Inflammation in Schizophrenia: Cytokine Levels and Their Relationships to Demographic and Clinical Variables

OBJECTIVE

Inflammation may play a role in the accelerated physical aging reported in schizophrenia, though biomarker findings and associations with demographic and clinical factors are inconsistent.

METHODS

In a cross-sectional, case-control design, 95 outpatients with schizophrenia (mean age ± SD: 48.1 ± 10.2 years) and 95 demographically comparable healthy comparison subjects (HCs) (mean age ± SD: 48.1 ± 12.1 years) were studied. Sociodemographic and clinical data were collected, and plasma levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interferon-γ (IFN-γ) were assayed. The authors compared cytokine levels, examined demographic and clinical associations, and adjusted for relevant variables with linear models.

RESULTS

Individuals with schizophrenia had higher levels of TNF-α and IL-6 but not IFN-γ than HCs. Age was not related to cytokine levels, and age relationships did not differ between diagnostic groups. Women had higher levels of IL-6. TNF-α and IL-6 levels were significantly correlated with depressive symptoms, and adjustment for depression reduced the group effect for both. Within the HCs, TNF-α levels were associated with physical comorbidity and body mass index. IL-6 levels were significantly correlated with body mass index and within schizophrenia patients, with worse mental and physical well-being. Accounting for physical morbidity and mental well-being reduced group differences in TNF-α and IL-6 levels, respectively. Worse positive symptoms were associated with higher IL-6 levels.

CONCLUSION

Higher TNF-α and IL-6 levels in schizophrenia patients were associated with depression, physical comorbidity, and mental well-being. Further longitudinal studies are warranted to assess inflammation as a potential treatment target for a subgroup of schizophrenia.

Pharmacogenetics of tardive dyskinesia: an updated review of the literature

Tardive dyskinesia (TD) is a serious and potentially irreversible side effect of long-term exposure to antipsychotic medication characterized by involuntary trunk, limb and orofacial muscle movements. Various mechanisms have been proposed for the etiopathophysiology of antipsychotic-induced TD in schizophrenia patients with genetic factors playing a prominent role. Earlier association studies have focused on polymorphisms in CYP2D6, dopamine-, serotonin-, GABA- and glutamate genes. This review highlights recent advances in the genetic investigation of TD. Recent promising findings were obtained with the HSPG2, DPP6, MTNR1A, SLC18A2, PIP5K2A and CNR1 genes. More research, including collection of well-characterized samples, enhancement of genome-wide strategies, gene–gene interaction and epigenetic analyses, is needed before genetic tests with clinical utility can be made available for TD.

Relationship of serum levels of TNF-α, IL-6 and IL-18 and schizophrenia-like symptoms in chronic ketamine abusers

OBJECTIVE

Exposing to NMDAR receptor antagonists, such as ketamine, produces schizophrenia-like symptoms in humans and deteriorates symptoms in schizophrenia patients. Meanwhile, schizophrenia is associated with alterations of cytokines in the immune system. This study aims to examine the serum TNF-α, IL-6 and IL-18 levels in chronic human ketamine users as compared to healthy subjects. The correlations between the serum cytokines levels with the demographic, ketamine use characteristics and psychiatric symptoms were also assessed.

METHODS

155 subjects who fulfilled the criteria of ketamine dependence and 80 healthy control subjects were recruited. Serum TNF-α, IL-6 and IL-18 levels were measured using an enzyme-linked immunosorbent assay (ELISA). The psychiatric symptoms of the ketamine abusers were assessed using the Positive and Negative Syndrome Scale (PANSS).

RESULTS

Serum IL-6 and IL-18 levels were significantly higher, while serum TNF-α level was significantly lower among ketamine users than among healthy controls (p<0.05). Serum TNF-α levels showed a significant negative association with PANSS total score (r=-0.210, p<0.01) and negative subscore (r=-0.300, p<0.01). No significant association was found between PANSS score and serum levels of IL-6 and IL-18.

CONCLUSIONS

Serum levels of TNF-α, IL-6 and IL-18 were altered in chronic ketamine abusers which may play a role in schizophrenia-like symptoms in chronic ketamine abusers.

TNF-related weak inducer of apoptosis (TWEAK) levels in schizophrenia

Members of tumor necrosis factor (TNF) superfamily have roles in many biological events and pathogenesis of central nervous system (CNS) diseases. A relatively recently found member of this family, TNF-related weak inducer of apoptosis (TWEAK) have importance both in development of pathological CNS processes and as a target for the treatment of these diseases. The aim of this study was to investigate whether TWEAK's plasma levels are different in patients with schizophrenia. For this purpose plasma TWEAK levels of 44 patients diagnosed with schizophrenia and control group of 40 healthy individuals were compared. Although numerical difference was found between TWEAK levels of patients and controls it was not statistically significant. When we tested for female and male patients and controls seperately, TWEAK levels of male patients were significantly lower than male controls. As far as we know this is the first study that investigates levels of TWEAK in patients with schizophrenia. Although we did not find statistically significant results in our study, we believe that difference could be found in future studies with higher number of subjects. Researches with non-studied TNF superfamily members like TWEAK and TNF-related apoptosis-inducing ligand (TRAIL) could contribute to the understanding of immune-cytokine related hypotheses of schizophrenia.

IL-6, IL-18, sIL-2R, and TNFα proinflammatory markers in depression and schizophrenia patients who are free of overt inflammation

Major depressive disorder (MDD) and schizophrenia are associated with inflammatory processes. Studies have shown that these disorders exhibit increase in the level of one or more proinflammatory markers. However, these studies did not exclude patients with obvious inflammation (i.e., CRP>6mg/L). Therefore, a comprehensive study should include those inflammatory disorders. In the present study, the inflammatory natures of MDD and schizophrenia were investigated. To achieve this goal, serum levels of interleukin-6 (IL-6), interleukin-18 (IL-18), tumor necrosis factor alpha (TNFα), and soluble interleukin 2 receptor (sIL-2R) in depressed and schizophrenic patients were obtained and compared with those of the control group. Results showed a significant increase (p<0.05) in serum levels of IL-6, IL-18, TNFα, and sIL-2R in MDD and schizophrenic patients compared with the control group. Also patients with schizophrenia group showed higher levels of the inflammatory markers than MDD and control groups. The current study concluded that the immunological response in the MDD and schizophrenic patients groups was significantly stimulated. These disorders may be considered an inflammatory disorder because of elevated levels of proinflammatory cytokines in spite of lacking an overt inflammation. Furthermore results of this study suggested the possibility of the use of anti-inflammatory drugs as adjuvant therapy in schizophrenic and depressive disorders.