Serum IL-18 level, clinical symptoms and IL-18-607A/C polymorphism among chronic patients with schizophrenia in a Chinese Han population

Interleukin 18 and the brain: neuronal functions, neuronal survival and psycho-neuro-immunology during stress

Interleukin 18 (IL-18) is a pleiotropic cytokine that regulates peripheral innate and adaptive immune response and is also expressed in the brain. Here, we summarize the current knowledge on the biology of IL-18 in the brain and the efforts to determine its significance concerning neurological and psychiatric conditions. The picture that emerges is that of a heavily regulated molecule that can contribute to neuroinflammatory-mediated neuronal survival but can also serve as a neuromodulator that affects behaviour. We also summarize evidence showing how the brain can control the synthesis of peripheral IL-18 during stress by hormonal and neuronal signalling, regulating tissue-specific promoter usage. We discuss how this may represent one of the mechanisms by which the brain affects immune functions and what its implications are when considering IL-18 as a biomarker of psychiatric conditions.

Expression pattern of long non-coding RNAs in treatment-naïve and medicated schizophrenia patients

Schizophrenia is a disabling mental disorder that affects 1% of people over their lifetime. The etiology and mechanism of schizophrenia are very complex, and many genes are involved in many different signaling pathways in the etiology of this disease. According to recent studies, one of the important mechanisms altered in this disorder is the regulation of immune system and the inflammation mechanism. In the present study, we evaluated the peripheral blood expression pattern of four lncRNAs and three protein-coding genes in the treatment- naïve patients, and medicated patients compared with sex and age-matched controls. In the medicated-patients, expression levels of IFNG, IL18RAP, AC007278.2 were significantly up-regulated (P < 0.05); and the expression level of IFNG-AS1-001 was significantly down-regulated compared to healthy controls (P < 0.05). However, levels of IL18R1, AC007278.3 and IFNG-AS1-003 were not different between these groups. In the treatment-naïve patients, IFNG, IL18R1, IL18RAP, IFNG-AS1-001, AC007278.2, and AC007278.3 were significantly up-regulated compared to controls. On the other hand, IFNG-AS1-003 was significantly down-regulated in the treatment-naïve patients compared to controls. Based on the Spearman correlation matrix, there was a significant correlation between genes in the treatment-naïve patients. We also showed the high sensitivity and specificity of IFNG-AS1-003, IFNG, IL18R1, and AC007278.3 in the identification of treatment-naïve patients from controls. The current study contributes further evidence to the understanding of the role of lncRNAs in the pathogenesis of schizophrenia. Future research is necessary to establish the validity of lncRNAs as peripheral markers for this condition.

Evaluating Single-Nucleotide Polymorphisms in Inflammasome Proteins and Serum Levels of IL-18 and IL-1β in Kidney Interstitial Damage in Anti-Neutrophilic Cytoplasmic Antibody-Associated Vasculitis

The inflammasome regulates the innate inflammatory response and is involved in autoimmune diseases. In this study, we explored the levels of IL-18 and IL-1β in serum and urine and the influence of various single-nucleotide polymorphisms (SNPs) on kidney lesions at diagnosis in patients with ANCA-associated vasculitis (AAV) and their clinical outcomes. Ninety-two patients with renal AAV were recruited, and blood and urine were collected at diagnosis. Serum and urine cytokine levels were measured by ELISA. DNA was extracted and genotyped using TaqMan assays for SNPs in several inflammasome genes. Lower serum IL-18 (p = 0.049) and the IL-18 rs187238 G-carrier genotype (p = 0.042) were associated with severe fibrosis. The IL-18 rs1946518 TT genotype was associated with an increased risk of relapse (p = 0.05), whereas GG was related to better renal outcomes (p = 0.031). The rs187238 GG genotype was identified as a risk factor for mortality within the first year after AAV diagnosis, independent of the requirement for dialysis or lung involvement (p = 0.013). We suggest that decreased cytokine levels could be a surrogate marker of scarring and chronicity of the renal lesions, together with the rs187238 GG genotype. If our results are validated, the rs1946518 TT genotype predicts the risk of relapse and renal outcomes during follow-up.

A double-blind, randomized controlled study of the effects of celecoxib on clinical symptoms and cognitive impairment in patients with drug-naïve first episode schizophrenia: pharmacogenetic impact of cyclooxygenase-2 functional polymorphisms

Chronic low-grade peripheral and central nervous system inflammation may have a role in the pathogenesis of schizophrenia (SCZ). Inhibition of cyclooxygenase-2 (COX2), the arachidonic acid pathway, may inhibit cytokine responses and minimize inflammation. In this study, we added the COX2 inhibitor celecoxib to risperidone monotherapy to examine its efficacy on clinical symptoms and cognitive deficits in drug-naïve first episode (DNFE) SCZ patients. First, we genotyped two polymorphisms (rs5275 and rs689466) in the COX-2 gene in a case-control study of 353 SCZ patients and 422 healthy controls. Ninety patients participated in a 12-week, double-blind, randomized, placebo-controlled trial of celecoxib 400 mg/day. We used the Positive and Negative Syndrome Scale (PANSS) and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) to assess clinical symptoms and cognition. Our results show that the COX2 rs5275 polymorphism was significantly correlated with SCZ and positive symptoms. After 12-week treatment, celecoxib significantly improved the PANSS total and three subscale scores of SCZ patients. Furthermore, patients with the rs5275 TT genotype had greater improvement in PANSS total score than patients carrying the C allele. However, no significant difference in RBANS total and subscale scores existed between the celecoxib and placebo groups at week 12. Our findings suggest that COX2 inhibitors may be promising therapeutics for clinical symptoms rather than cognitive impairment in first episode SCZ patients. COX2 rs5275 gene polymorphism may be implicated in the development and the efficacy of treating clinical symptoms in SCZ.Trial Registration Number: The trial was registered with www.clinicaltrials.gov (NCT00686140).

Association between cognitive function and IL-18 levels in schizophrenia: Dependent on IL18 - 607 A/C polymorphism

Accumulating evidence suggests that immune system dysregulation is associated with debilitating neurodevelopment in schizophrenia (SZ). Cognitive impairment is a persistent feature that occurs during the onset of SZ and persists throughout the course of the disease. Early studies have found that elevated interleukin (IL)- 18 interacts with IL18 polymorphism and is correlated with psychotic symptoms in SZ. This study aimed to investigate whether elevated IL-18 levels interacted with the -607 A/C polymorphism to determine cognitive decline in patients with chronic SZ. We recruited 693 inpatients and 422 healthy controls to measure IL-18 levels and genotype the - 607 A/C polymorphism. Further, cognitive function was measured by the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). We found that IL-18 serum levels were higher in patients than those in healthy controls, and were not associated with IL18 - 607 A/C in combined subjects or either patients or healthy controls, respectively. Moreover, - 607 A/C was correlated with the visuospatial/constructional index only in the patients. In addition, our research found that IL-18 levels were positively correlated to immediate memory only in patients with the C/C genotype, but not in patients with C/A or A/A genotype. This study suggests that the relationship of IL-18 with cognitive function depends on the IL18 - 607 A/C polymorphism of SZ patients.

Association of Single Nucleotide Polymorphisms of Cytokine Genes with Depression, Schizophrenia and Bipolar Disorder

Immune gene variants are known to be associated with the risk of psychiatric disorders, their clinical manifestations, and their response to therapy. This narrative review summarizes the current literature over the past decade on the association of polymorphic variants of cytokine genes with risk, severity, and response to treatment for severe mental disorders such as bipolar disorder, depression, and schizophrenia. A search of literature in databases was carried out using keywords related to depressive disorder, bipolar disorder, schizophrenia, inflammation, and cytokines. Gene lists were extracted from publications to identify common genes and pathways for these mental disorders. Associations between polymorphic variants of the IL1B, IL6, and TNFA genes were the most replicated and relevant in depression. Polymorphic variants of the IL1B, IL6, IL6R, IL10, IL17A, and TNFA genes have been associated with schizophrenia. Bipolar disorder has mainly been associated with polymorphic variants of the IL1B gene. Interestingly, the IL6R gene polymorphism (rs2228145) was associated with all three diseases. Some cytokine genes have also been associated with clinical presentation and response to pharmacotherapy. There is also evidence that some specific polymorphic variants may affect the expression of cytokine genes. Thus, the data from this review indicate a link between neuroinflammation and severe mental disorders.

Effects of brain-derived neurotrophic factor (BDNF) on the Schizophrenia model of animals

BACKGROUND

Schizophrenia（SCZ）is a common clinically chronic psychiatric disease, and there have no effective specific therapeutic drugs in clinical practice currently. Studies have shown that the expression level of brain-derived neurotrophic factor (BDNF) in schizophrenics has decreased, so the expression level of BDNF has always been one of the evaluation indicators of SCZ. The neurotrophic factor hypothesis believes that increase or decrease of the expression level of BDNF may be one of the pathophysiological basis of SCZ.

METHODS

In this study, schizophrenic mice model with MK-801-induced glutamate dysfunction was established, and two doses of BDNF were administered to schizophrenic mice by intranasal administration. The four groups of mice: Control group, Model group, BDNF-20, BDNF-100 performed a series of behavioral tests to explore the effects of BDNF on sensory motor gating, anxiety, depression, social interaction, spontaneous activity, and memory in schizophrenic mice. Transcriptome sequencing of the BDNF high group and Model group in prefrontal cortex and hippocampus, using Metascape for gene function annotation and enrichment pathway analysis, to obtain BDNF transcription regulation information, understand the molecular mechanism of BDNF in SCZ further. Subsequently，immunofluorescence detected the effects of BDNF on neurons and glial cells in the prefrontal cortex and hippocampus.

CONCLUSION

The results show that BDNF can improve the behavior of SCZ by regulating the construction of the nervous system, affecting the growth and distribution of neurons and glial cells, and changing inflammation and apoptosis in the brain.

Increased NLRP3 inflammasome expression in peripheral blood mononuclear cells of patients with schizophrenia: a case-control study

OBJECTIVE

This study aimed to evaluate the gene expression of the P2X purinoceptor 7 (P2X7R)- nod-like receptor pyrin domain-containing protein 3 (NLRP3) signal pathway in peripheral blood mononuclear cells (PBMCs) between schizophrenia (SCZ) patients and healthy controls (HC) to reveal its relationship with clinical variables.

METHODS

Thirty-two SCZ patients and 41 healthy controls were included in this study. The Scale for the Assessment of Positive Symptoms (SAPS) and the Scale for the Assessment of Negative Symptoms (SANS), The Global Assessment of Functioning (GAF) scale and the Functioning Assessment Short Test (FAST) scales were applied. P2X7R, NLRP3, IL-1β and IL-18 gene expression levels were evaluated by real-time polymerase chain reaction in PBMCs.

RESULTS

NLRP3, P2RX7, IL-1β and IL-18 expression levels were significantly higher in PBMCs of SCZ patients than in HC subjects. Negative correlations were found between NLRP3 gene expression levels and GAF and FAST scales scores. There was a negative correlation between IL-18 expression levels and the GAF and FAST scales scores and a positive correlation with the SAPS scale scores.

CONCLUSIONS

Systemic inflammation is implicated in SCZ pathogenesis, according to our findings, which suggest that the NLRP3 pathway may be involved. The NLRP3 inflammasome may serve as a biomarker for SCZ, and its pharmacological regulation may be a promising treatment approach.Key pointsWe hypothesised that the NLRP3 pathway may contribute to the etiopathogenesis of schizophrenia.NLRP3, IL-1β and IL-18 mRNA levels were higher in patients with schizophrenia compared to healthy controls.Negative correlations were found between NLRP3 gene expression levels and GAF and FAST scales scores.There was a negative correlation between IL-18 expression levels and the GAF and FAST scales scores.The SAPS scale scores and IL-18 expression levels had a positive correlation.Given all these findings, it can be stated that NLRP3 inflammasome may play a role in the pathogenesis and symptoms of schizophrenia.

Elevated levels of IL-18 associated with schizophrenia and first episode psychosis: A systematic review and meta-analysis

AIM

To determine whether interleukin 18 (IL-18) is elevated in the blood of schizophrenia (SCZ) and first episode psychosis patients, as well as investigate whether this potential relationship is causal.

METHOD

We conducted a systematic review and meta-analysis of IL-18 levels in the blood of SCZ patients, comprising of both chronic and first episode psychosis (FEP) cohorts. To investigate causality, we undertook the two-sample Mendelian randomization (MR) study.

RESULTS

A total of eight studies were included in our meta-analysis, our results did indeed show an association between elevated levels of IL-18 and SCZ compared to healthy controls (Z = 3.50, P = .0005). This association remained significant in subsequent subgroup analyses for chronic (Z = 3.15, P = .002) and achieved borderline significance in FEP (Z = 1.93, P = .05) SCZ. Our MR analysis failed to detect any causal relationship between IL-18 levels and SCZ.

CONCLUSION

The results of our study demonstrate that even though IL-18 levels are elevated in SCZ patients, IL-18 levels do not seem to cause of the disorder itself. Our findings suggest that IL-18 may have utility as a biomarker of SCZ and aid in research into the early intervention of the disease.

Increased interleukin 18 activity in adolescents with early-onset psychosis is associated with cortisol and depressive symptoms

OBJECTIVE

Evidence indicates that the pathophysiology of adult psychosis involves immune dysregulation, but its associations with stress are often not considered. The inflammatory cytokine interleukin (IL)-18, which is elevated in adult schizophrenia, is suggested to be sensitive to stress. We compared the associations of IL-18 with cortisol and clinical variables in adolescents with early-onset psychosis (EOP) aged 12-18 years and age-matched healthy controls (HC).

METHOD

We measured serum IL-18, IL-18 binding protein (IL-18BP), IL-18 receptor accessory protein (IL-18RAP), IL-18 receptor 1 (IL-18R1) and cortisol, and calculated the IL-18/IL-18BP ratio in patients (n = 31) and HC (n = 60). Psychotic symptoms were assessed using the Positive and Negative Syndrome Scale and depressive symptoms by the Mood and Feelings Questionnaire-Child version (MFQ-C). Bivariate correlation analysis was used to explore relationships between IL-18/IL-18BP ratio and cortisol, depression and other clinical characteristics. Hierarchical multiple linear regression analysis was used to assess their individual contributions to the variance of the IL-18/IL-18BP ratio.

RESULTS

Patients had significantly higher IL-18 levels and IL-18/IL-18BP ratios than HC, but similar IL-18BP, IL-18RAP and IL-18R1. Both cortisol (R² change = 0.05) and the MFQ-C score (R² change = 0.09) contributed significantly to the variance in IL-18/IL-18BP ratios after controlling for confounders.

CONCLUSION

We found increased IL-18 system activity in adolescents with EOP. Cortisol and depressive symptoms each contributed to the variance in the IL-18/IL-18BP ratio. Our findings support activation of inflammatory pathways in adolescent psychosis and suggest interactions between stress, inflammation and depressive symptoms in EOP.

A comprehensive pathway map of IL-18-mediated signalling

Interleukin-18 (IL-18) is a member of the IL-1 family of cytokines and was initially described as an IFN-γ-inducing factor derived from anti-CD3-stimulated T-helper (Th)1 cells. IL-18 plays a significant role in the activation of hematopoietic cell types mediating both Th1 and Th2 responses and is the primary inducer of interferon-γ in these cells. The biological activity of IL-18 is mediated through its binding to the IL-18 receptor complex and activation of nuclear factor-κB (NF-κB), culminating in the production and release of several cytokines, chemokines, and cellular adhesion molecules. In certain cell types, IL-18 also activates mitogen-activated protein kinases (MAPKs) and phosphoinositide 3-kinase/ AKT serine/threonine kinase (PI3K/AKT) signaling modules leading to the production and release of proinflammatory cytokines. IL-18-mediated signaling acts as one of the vital components of the immunomodulatory cytokine networks involved in host defense, inflammation, and tissue regeneration. Albeit its biomedical importance, a comprehensive resource of IL-18 mediated signaling pathway is currently lacking. In this study, we report on the development of an integrated pathway map of IL-18/IL-18R signaling. The pathway map was developed through literature mining from published literature based on manual curation guidelines adapted from NetPath and includes information on 16 protein-protein interaction events, 38 enzyme-catalysis events, 12 protein translocation events, 26 activations/inhibition events, transcriptional regulators, 230 gene regulation events and 84 induced protein expression events. The IL-18 signaling pathway can be freely accessed through the WikiPathways database (https://www.wikipathways.org/index.php/Pathway:WP4754).

Brain, blood, cerebrospinal fluid, and serum biomarkers in schizophrenia

Over the last decade, finding a reliable biomarker for the early detection of schizophrenia (Scz) has been a topic of interest. The main goal of the current review is to provide a comprehensive view of the brain, blood, cerebrospinal fluid (CSF), and serum biomarkers of Scz disease. Imaging studies have demonstrated that the volumes of the corpus callosum, thalamus, hippocampal formation, subiculum, parahippocampal gyrus, superior temporal gyrus, prefrontal and orbitofrontal cortices, and amygdala-hippocampal complex were reduced in patients diagnosed with Scz. It has been revealed that the levels of interleukin 1β (IL-1β), IL-6, IL-8, and TNF-α were increased in patients with Scz. Decreased mRNA levels of brain-derived neurotrophic factor (BDNF), tropomyosin receptor kinase B (TrkB), neurotrophin-3 (NT-3), nerve growth factor (NGF), and vascular endothelial growth factor (VEGF) genes have also been reported in Scz patients. Genes with known strong relationships with this disease include BDNF, catechol-O-methyltransferase (COMT), regulator of G-protein signaling 4 (RGS4), dystrobrevin-binding protein 1 (DTNBP1), neuregulin 1 (NRG1), Reelin (RELN), Selenium-binding protein 1 (SELENBP1), glutamic acid decarboxylase 67 (GAD 67), and disrupted in schizophrenia 1 (DISC1). The levels of dopamine, tyrosine hydroxylase (TH), serotonin or 5-hydroxytryptamine (5-HT) receptor 1A and B (5-HTR1A and 5-HTR1B), and 5-HT1B were significantly increased in Scz patients, while the levels of gamma-aminobutyric acid (GABA), 5-HT transporter (5-HTT), and 5-HT receptor 2A (5-HTR2A) were decreased. The increased levels of SELENBP1 and Glycogen synthase kinase 3 subunit α (GSK3α) genes in contrast with reduced levels of B-cell translocation gene 1 (BTG1), human leukocyte antigen DRB1 (HLA-DRB1), heterogeneous nuclear ribonucleoprotein A3 (HNRPA3), and serine/arginine-rich splicing factor 1 (SFRS1) genes have also been reported. This review covers various dysregulation of neurotransmitters and also highlights the strengths and weaknesses of studies attempting to identify candidate biomarkers.

Cytokines dysregulation in schizophrenia: A systematic review of psychoneuroimmune relationship

INTRODUCTION

Schizophrenia is a multifactorial psychiatric disease with complex interactions among the brain and the immune system. A psycho-immune relationship underling schizophrenia is supported by several studies and integrates a specific area of knowledge - psychoneuroimmunology.

METHODS

A systematic review was performed by 2009 Preferred Reporting Items (PRISMA) recommendations. Based on the inclusion/exclusion criteria, publications with relevant information (evaluated by the Joanna Briggs Institute Critical Appraisals tools to quality assessment) were included.

RESULTS

In this review, we considered the inflammatory activity promoted by cytokine alterations in schizophrenia aetiology, which reflects the systemic comprehension of this disease in opposition to the traditional approach focused solely on the brain. We focus on the analysis of several specific outcomes, such as proinflammatory cytokines, sample sort, laboratory techniques, diagnosis scales and results of each publication.

CONCLUSION

This systematic review confirms the existence of cytokines abnormalities in schizophrenia disease. Immune imbalances such as increased levels of some cytokines (either at protein level or at mRNA expression), cytokine mRNAs, as well as cytokine gene polymorphisms have been reported with a large support in schizophrenia. These findings provide a strong evidence of a concomitant process of inflammatory activity in schizophrenia illness course.

Tumor necrosis factor-alpha -1031T/C polymorphism is associated with cognitive deficits in chronic schizophrenia patients versus healthy controls

Recent compelling research has demonstrated a pathophysiologic role for proinflammatory cytokines of microglial origin in decreasing neurocognitive function. Psychiatric diseases are already known to have reduced cognitive function and are also associated with increased inflammation. To elaborate on these data, our study aims to investigate how a particular polymorphism of the tumor necrosis factor gene, TNF-α -1031T/C, affects neurocognitive performance in patients with schizophrenia. We recruited 905 patients with schizophrenia and 571 healthy control subjects. We employed the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) to test for neurocognitive function and the positive and negative syndrome scale to evaluate schizophrenia severity. The -1031T/C polymorphism was genotyped in both healthy controls and schizophrenic patients. Our results demonstrate that patients with the C allele (either T/C or C/C) possessed increased immediate memory index, visuospatial/constructional index, and RBANS total scores as compared to patients without it (p < .05). In healthy controls, there was no significant difference across genotypes (p > .05). Our findings demonstrate that the TNF-α -1031T/C polymorphism may not play a role in the susceptibility of schizophrenia itself, but may be involved in the cognitive deficits of schizophrenia. This suggests an important role for cytokine signaling in mediating the severity of cognitive dysfunction in schizophrenia.