Cytokine Level Changes in Schizophrenia Patients with and without Metabolic Syndrome Treated with Atypical Antipsychotics

Global Prevalence of Metabolic Syndrome in Schizophrenia Patients: A Systematic Review and Meta-Analysis

The prevalence of metabolic syndrome in patients with schizophrenia has significantly increased and can be associated with severe complications such as chronic diseases and mortality. Despite numerous studies, a comprehensive estimate of the prevalence of metabolic syndrome in schizophrenia patients is lacking. Therefore, this study aimed to estimate the global prevalence of metabolic syndrome in schizophrenia patients through a systematic review and meta-analysis. This study was conducted as a systematic review and meta-analysis based on PRISMA guidelines without time restrictions until April 1, 2024. Relevant articles were identified through searches in databases including Scopus, Web of Science (WoS), PubMed, Science Direct, Embase, and Google Scholar, using key terms combined with AND & OR operators. After removing duplicates and conducting primary and secondary screening, 12 studies were included in the meta-analysis. Data were analysed using the random-effects model in Comprehensive Meta-Analysis Version 2 software. This analysis included 12 studies with 1,953 participants. The pooled prevalence of metabolic syndrome was 41.3% (95% CI: 28.8-55.1), with significant heterogeneity (I2: 96.3%). The highest prevalence was reported in France (79.1%) and the lowest in China (18.03%). Over one-third of patients with schizophrenia are affected by metabolic syndrome. Hence, greater attention should be paid to the prevention and reduction of complications and mortality associated with metabolic syndrome in schizophrenia patients.

Effects of 6-week olanzapine treatment on serum IL-2, IL-4, IL-8, IL-10, and TNF-α levels in drug-naive individuals with first-episode schizophrenia

BACKGROUND

Schizophrenia is a complex neuropsychiatric disorder. Growing evidence indicates that the activation of the inflammatory response system with interleukin (IL)-2, IL-4, IL-8, IL-10, and tumor necrosis factor-alpha (TNF-α) plays an important role in the pathogenesis of schizophrenia,. However, clinical data on cytokine levels in patients with schizophrenia treated with antipsychotics are inconsistent or inconclusive. In this study, we have examined inflammatory factors' alterations and their relationship to changes in clinical symptoms before and after olanzapine treatment of drug-naive patients with first-episode schizophrenia.

METHODS

We recruited 142 hospitalized patients with first-episode schizophrenia as a study group; blood samples were collected, and the patients were assessed for clinical symptoms at baseline and after 6 weeks of olanzapine treatment. One hundred individuals with no history of mental illness were also recruited as healthy controls. Blood samples were collected, and the serum levels of IL-2, IL-4, IL-8, IL-10, and TNF-α were determined using an enzyme cycling assay. The severity of clinical symptoms was assessed according to the Positive and Negative Syndrome Scale (PANSS).

RESULTS

Individuals with schizophrenia had lower IL-8 levels and higher IL-10 levels than healthy controls (P < 0.001). Positive correlations were detected between serum IL-2 and IL-10 concentrations and each subscale of the PANSS (all P < 0.05). Moreover, a negative correlation existed between the serum IL-8 concentration and the PANSS negative score (r = - 0.172, P = 0.040). After 6 weeks of treatment, serum IL-8 levels in the patient group were lower than at baseline (P < 0.001), whereas serum IL-10 and TNF-α levels were higher than at baseline (all P < 0.05). Therefore, serum IL-10 can be determined as an independent risk factor for outcome in patients with first-episode schizophrenia (P = 0.02, OR = 2.327). Furthermore, serum IL-2, IL-10, and TNF-α levels were significantly lower, whereas the serum IL-8 level was significantly higher (P < 0.001) in the healthy control group than in the "response" and "no-response" treatment groups respectively.

CONCLUSIONS

Our results indicate that serum IL-2, IL-8, IL-10, and TNF-α levels may be involved in the pathophysiological mechanisms of schizophrenia and correlate with the effects of olanzapine.

Association of Peripheral Inflammatory Biomarkers and Growth Factors Levels with Sex, Therapy and Other Clinical Factors in Schizophrenia and Patient Stratification Based on These Data

Multiple lines of evidence are known to confirm the pro-inflammatory state of some patients with schizophrenia and the involvement of inflammatory mechanisms in the pathogenesis of psychosis. The concentration of peripheral biomarkers is associated with the severity of inflammation and can be used for patient stratification. Here, we analyzed changes in serum concentrations of cytokines (IL-1β, IL-2, IL-4, IL-6, IL-10, IL-21, APRIL, BAFF, PBEF/Visfatin, IFN-α, and TNF-α) and growth/neurotrophic factors (GM-CSF, NRG1-β1, NGF-β, and GDNF) in patients with schizophrenia in an exacerbation phase. IL-1β, IL-2, IL-4, IL-6, BAFF, IFN-α, GM-CSF, NRG1-β1, and GDNF increased but TNF-α and NGF-β decreased in schizophrenia compared to healthy individuals. Subgroup analysis revealed the effect of sex, prevalent symptoms, and type of antipsychotic therapy on biomarker levels. Females, patients with predominantly negative symptoms, and those taking atypical antipsychotics had a more pro-inflammatory phenotype. Using cluster analysis, we classified participants into "high" and "low inflammation" subgroups. However, no differences were found in the clinical data of patients in these subgroups. Nevertheless, more patients (17% to 25.5%) than healthy donors (8.6% to 14.3%) had evidence of a pro-inflammatory condition depending on the clustering approach used. Such patients may benefit from personalized anti-inflammatory therapy.

The Influence of Antipsychotic Treatment on the Activity of Abzymes Targeting Myelin and Levels of Inflammation Markers in Patients with Schizophrenia

Catalytic antibodies, or abzymes, are capable of not only binding but also hydrolyzing various proteins. Previously, an increase in the level of myelin basic protein (MBP)-hydrolyzing activity of antibodies was shown in patients with a number of neurological and mental disorders, including schizophrenia. Furthermore, antipsychotic therapy is known to induce a change in cytokine levels in patients with schizophrenia, which affects regulation of the immune response and inflammatory status. This study investigated the influence of typical and atypical antipsychotics on catalytic antibody activity and the 10 major pro- and anti-inflammatory serum cytokine levels. The study included 40 patients with schizophrenia: 15 treated with first-generation antipsychotics and 25 treated with atypical antipsychotics for 6 weeks. It was found that treatment with atypical antipsychotics changed the levels of some pro-inflammatory cytokines. Antipsychotic therapy also caused a significant decrease in MBP-hydrolyzing activity in patients with schizophrenia (p = 0.0002), and associations of catalytic activity with interleukins were observed.

Serum Growth Factors in Schizophrenia Patients

Some hypotheses include schizophrenia as a neurodevelopmental disorder, which indicates a special role in growth factors and neuroglia in the development of schizophrenia symptoms. Growth factors are cytokine molecules that play an important role in the regulation of tissue nucleation, cell development, survival, and migration of all tissues in organisms, including the brain and nervous system. The aim of the study was to determine the serum concentration of six growth factors (EGF, VEGF, FGF-2, TGF-α, PDGF-AA, PDGF-AB/BB) in schizophrenia patients and to identify the correlations with clinical characteristics. After signing an informed consent form, 236 schizophrenia patients (F20 according to the ICD-10) and 102 healthy people were recruited in the study. In patients with schizophrenia, we observed a significant elevation in the TGF-α and PDGF-AA serum levels. The duration of schizophrenia was significantly positively correlated with the FGF-2 level. The PANSS total score had a positive correlation with the FGF-2 level and a negative correlation with the TGF-α level. Our results and literature indicate the involvement of growth factors in the mechanisms of development of schizophrenia. Combined biomarker screening seems to be necessary to improve diagnosis and clinical follow-up of patients with severe mental illnesses.

Cell Adhesion Molecules in Schizophrenia Patients with Metabolic Syndrome

Metabolic syndrome (MetS) is a common comorbidity of schizophrenia and significantly shortens life expectancy of the patients. Intercellular (ICAM), vascular (VCAM), and neural (NCAM) cell adhesion molecules (CAMs) mediate neuroinflammatory processes, and their soluble forms (e.g., sICAM) in plasma are present in parallel with their cell-bound forms. In this study, their serum levels were examined in 211 white Siberian patients with paranoid schizophrenia (82 patients with and 129 without MetS according to the 2005 International Diabetes Federation criteria). Serum levels of CAMs were determined with Magpix and Luminex 200 (Luminex, Austin, TX, USA) using xMAP Technology. The level of sICAM-1 was significantly higher and that of sVCAM-1 significantly lower in patients with MetS compared to patients without MetS. Levels of NCAM did not differ between the groups. More pronounced Spearman’s correlations between CAMs, age, duration of schizophrenia, and body–mass index were observed among patients without MetS than among patients with MetS. Our results are consistent with MetS’s being associated with endothelial dysfunction along with other components of inflammation. Through these endothelial components of peripheral inflammatory processes, MetS might induce intracerebral neuroinflammatory changes, but further investigation is needed to confirm this.

Cytokines as Potential Biomarkers of Clinical Characteristics of Schizophrenia

Immune activation plays a major role in the pathogenesis of schizophrenia, as confirmed by many studies, systematic reviews, and meta-analyses. The important role of neuroinflammation in the formation of the relation between impaired neurobiological processes and schizophrenia psychopathology is being actively discussed. We quantified serum concentrations of 22 cytokines in 236 patients with schizophrenia and 103 mentally and somatically healthy individuals by a multiplex assay. We found higher TGF-α (p = 0.014), IFN-γ (p = 0.036), IL-5 (p < 0.001), IL-6 (p = 0.047), IL-8 (p = 0.005), IL-10 (p <0.001), IL-15 (p = 0.007), IL-1RA (p = 0.007), and TNF-α (p < 0.001) levels in patients with schizophrenia than in healthy individuals. Subgroup analysis revealed a much greater number of statistically significant differences in cytokine levels among females than among males. Patients with a continuous course of schizophrenia showed statistically significantly higher levels of IL-12p70 (p = 0.019), IL-1α (p = 0.046), and IL-1β (p = 0.035) compared with patients with an episodic course. Most cytokines were positively correlated with positive, general, and total PANSS scores. In patients with a duration of schizophrenia of 10 years or more, the level of IL-10 was higher than that in patients with a disease duration of 5 years or less (p = 0.042). Thus, an imbalance in cytokines was revealed in patients with schizophrenia, depending on sex and clinical characteristics of the disease.

Metabolic Hormones in Schizophrenia Patients with Antipsychotic-Induced Metabolic Syndrome

Metabolic syndrome (MetS) is a common complication of schizophrenia that is quite exacerbated by long-term use of (atypical) antipsychotics. The mechanism of MetS has neuronal, neuroendocrine, and neuroimmunological components and shows some overlap with those of aspects of schizophrenia. We examined 195 patients with schizophrenia (90 with and 105 without MetS) for the association of serum levels of ghrelin, insulin, and leptin with metabolic abnormalities. Serum glucose levels and lipid profiles were routinely measured with colorimetric enzymatic methods and hormone levels with multiplex analyzers. Leptin levels were highly significantly increased (p < 0.001) in people with MetS (9.966 [5.882; 21.496] vs. 6.35 [2.005; 11.753], Me [Q1; Q3]) and ghrelin levels were actually significantly decreased (p = 0.045). Insulin levels did not differ significantly between those with and without MetS (p = 0.162). In Spearman’s correlation analysis between the hormone levels, body characteristics, and biochemical parameters, significant correlations were seen somewhat more often in people without MetS than in those with MetS and also less often for ghrelin than for the other hormones. We conclude that evidence exists for a role in the development of MetS especially for leptin, but that less is supporting a role for ghrelin.

Cytokine Imbalance as a Biomarker of Treatment-Resistant Schizophrenia

Treatment-resistant schizophrenia (TRS) is an important and unresolved problem in biological and clinical psychiatry. Approximately 30% of cases of schizophrenia (Sch) are TRS, which may be due to the fact that some patients with TRS may suffer from pathogenetically “non-dopamine” Sch, in the development of which neuroinflammation is supposed to play an important role. The purpose of this narrative review is an attempt to summarize the data characterizing the patterns of production of pro-inflammatory and anti-inflammatory cytokines during the development of therapeutic resistance to APs and their pathogenetic and prognostic significance of cytokine imbalance as TRS biomarkers. This narrative review demonstrates that the problem of evaluating the contribution of pro-inflammatory and anti-inflammatory cytokines to maintaining or changing the cytokine balance can become a new key in unlocking the mystery of “non-dopamine” Sch and developing new therapeutic strategies for the treatment of TRS and psychosis in the setting of acute and chronic neuroinflammation. In addition, the inconsistency of the results of previous studies on the role of pro-inflammatory and anti-inflammatory cytokines indicates that the TRS biomarker, most likely, is not the serum level of one or more cytokines, but the cytokine balance. We have confirmed the hypothesis that cytokine imbalance is one of the most important TRS biomarkers. This hypothesis is partially supported by the variable response to immunomodulators in patients with TRS, which were prescribed without taking into account the cytokine balance of the relation between serum levels of the most important pro-inflammatory and anti-inflammatory cytokines for TRS.

Metabolic syndrome in patients with schizophrenia: Why should we care

Metabolic syndrome (MS) is a serious disease in patients with schizophrenia; it is necessary to evaluate the characteristics and influencing factors of MS to provide reliable evidence for the management of schizophrenia. Patients with schizophrenia treated in our hospital from January 1, 2018, to March 31, 2021, were selected. The characteristics and treatment details of MS and no-MS patients were evaluated. Pearson correlation analyses were applied for analyzing MS and related characteristics. Logistic regression analyses were conducted to evaluate the risk factors of MS in patients with schizophrenia. A total of 465 patients with schizophrenia were included, the incidence of MS in patients with schizophrenia was 18.06%. Pearson correlation analyses had found that age (r = 0.621), waist circumference (r = 0.744), body mass index (r = 0.691), diabetes (r = 0.598), course of disease (r = 0.504), triglyceride (r = 0.532), high-density lipoprotein cholesterol (r = -0.518), low-density lipoprotein cholesterol (r = 0.447), and total cholesterol (r = 0.523) were correlated with MS (all P < .05). Logistic regression analyses showed that age ≥55 years (odds ratio [OR]: 2.012, 95% confidence interval [CI]: 1.425-3.196), waist circumference ≥80 cm (OR: 1.944, 95% CI: 1.081-3.172), body mass index ≥24.5 kg/m2 (OR: 2.451, 95% CI: 1.825-3.108), diabetes (OR: 2.301, 95% CI: 1.944-2.881), course of disease ≥15 years (OR: 1.804, 95% CI: 1.236-2.845), triglyceride ≥1.5 mmol/L (OR: 2.032, 95% CI: 1.614-3.079), high-density lipoprotein cholesterol ≤0.8 mmol/L (OR: 1.226, 95% CI: 1.102-1.845), low-density lipoprotein cholesterol ≥2 mmol/L (OR: 1.759, 95% CI: 1.236-1.987), and total cholesterol ≥4.5 mmol/L (OR: 1.664, 95% CI: 1.422-1.852) were the risk factors of MS in patients with schizophrenia (all P < .05). MS is very common in patients with schizophrenia, which may be associated with many possible risk factors, and early interventions and nursing care targeted at those influencing factors are needed to improve the prognosis of schizophrenia.

The Gender-Specific Association of DRD2 Polymorphism with Metabolic Syndrome in Patients with Schizophrenia

Background: Metabolic syndrome is widespread in patients with schizophrenia receiving long-term antipsychotic therapy. Dopamine D2 receptors play an important role in mediating both the therapeutic actions of antipsychotics and their side effects. The present study examined the association of two polymorphisms of the DRD2 gene with metabolic syndrome in patients with schizophrenia. Methods: We examined 517 patients from several regions of Siberia (Russia) with a clinical diagnosis of schizophrenia. Genotyping of two single nucleotide polymorphisms rs1799732 and rs4436578 of the dopamine D2 receptor gene (DRD2) was performed in a population of 471 patients. The results were analyzed using chi-square tests. Results: Functional polymorphism rs1799732 of the DRD2 gene is associated with drug-induced metabolic syndrome in women with schizophrenia. Conclusions: Our results show that the DRD2 gene may be involved in the pathogenesis of metabolic disorders in patients with schizophrenia. Further analysis of possible genetic markers will allow for personalized treatment with minimal side effects and optimal efficacy. This which seems relevant in light of the recent focus on improving the quality of life and ensuring a high level of social adaptation of patients with schizophrenia.

Immuno-metabolic profile of patients with psychotic disorders and metabolic syndrome. Results from the FACE-SZ cohort

Background

Metabolic syndrome (MetS) is a highly prevalent and harmful medical disorder often comorbid with psychosis where it can contribute to cardiovascular complications. As immune dysfunction is a key shared component of both MetS and schizophrenia (SZ), this study investigated the relationship between immune alterations and MetS in patients with SZ, whilst controlling the impact of confounding clinical characteristics including psychiatric symptoms and comorbidities, history of childhood maltreatment and psychotropic treatments.

Method

A total of 310 patients meeting DSM-IV criteria for SZ or schizoaffective disorders (SZA), with or without MetS, were systematically assessed and included in the FondaMental Advanced Centers of Expertise for Schizophrenia (FACE-SZ) cohort. Detailed clinical characteristics of patients, including psychotic symptomatology, psychiatric comorbidities and history of childhood maltreatment were recorded and the serum levels of 18 cytokines were measured. A penalized regression method was performed to analyze associations between inflammation and MetS, whilst controlling for confounding factors.

Results

Of the total sample, 25% of patients had MetS. Eight cytokines were above the lower limit of detection (LLOD) in more than 90% of the samples and retained in downstream analysis. Using a conservative Variable Inclusion Probability (VIP) of 75%, we found that elevated levels of interleukin (IL)-6, IL-7, IL-12/23 p40 and IL-16 and lower levels of tumor necrosis factor (TNF)-α were associated with MetS. As for clinical variables, age, sex, body mass index (BMI), diagnosis of SZ (not SZA), age at the first episode of psychosis (FEP), alcohol abuse, current tobacco smoking, and treatment with antidepressants and anxiolytics were all associated with MetS.

Conclusion

We have identified five cytokines associated with MetS in SZ suggesting that patients with psychotic disorders and MetS are characterized by a specific “immuno-metabolic” profile. This may help to design tailored treatments for this subgroup of patients with both psychotic disorders and MetS, taking one more step towards precision medicine in psychiatry.

Schizophrenia and Alarmins

Schizophrenia, consisting of a group of severe psychiatric disorders with a complex etiology, is a leading cause of disability globally. Due to the lack of objective indicators, accurate diagnosis and selection of effective treatments for schizophrenia remain challenging. The association between schizophrenia and alarmins levels has been proposed for many years, but without solid evidence. Alarmins are prestored molecules that do not require processing and can be released upon cell death or damage, making them an ideal candidate for an early initiator of inflammation. Immunological biomarkers seem to be related to disease progression and treatment effectiveness. Several studies suggest strong associations among the high-mobility group box 1 protein (HMGB1), interleukin-1α, interleukin-33, S100B, heat-shock proteins, and uric acid with schizophrenic disorders. The purpose of this review is to discuss the evidence of central and peripheral immune findings in schizophrenia, their potential causes, and the effects of immunomodulatory therapies on symptoms and outline potential applications of these markers in managing the illness. Although there are currently no effective markers for diagnosing or predicting treatment effects in patients with schizophrenia, we believe that screening immune-inflammatory biomarkers that are closely related to the pathological mechanism of schizophrenia can be used for early clinical identification, diagnosis, and treatment of schizophrenia, which may lead to more effective treatment options for people with schizophrenia.

Influence of antipsychotics on metabolic syndrome risk in patients with schizophrenia

OBJECTIVE

Many studies so far have shown that antipsychotic therapy may have an effect on the development of metabolic syndrome in patients diagnosed with schizophrenia. Our goal was to determine whether our respondents are at risk for developing metabolic syndrome and who is more predisposed to it.

METHODS

In a stable phase, 60 patients diagnosed with schizophrenia were equally divided into three groups according to the drug (risperidone, clozapine, and aripiprazole monotherapy). Control group had 20 healthy examinees. Patients were evaluated first using The Positive and Negative Syndrome Scale (PANSS). Prolactin, lipid status, glycemia, insulin, cytokine values (IL-33, TGF-β, and TNF-α) and C-reactive protein (CRP) were measured. Also, Body mass index (BMI), Homeostatic Model Assesment for Insulin Resistance (HOMA index), waist and hip circumference (WHR) and blood pressure (TA) measurement were performed in the study.

RESULTS

Patients treated with risperidone compared to healthy control subjects and aripiprazol group of patients had statistically significant difference in prolactin levels. In clozapine group compared to healthy control group values of HDL cholesterol and glucose level were statistically significant different. In aripiprazole group compared to healthy control group value of BMI was statistically significant different. Statistically significant correlations were found in TNF-α with glucose and HOMA index in risperidone treated patients and with BMI in clozapine group of patients; IL-33 with glucose in risperidone and with BMI in clozapine group of patients and TGF-β with glucose in risperidone group, with insulin and HOMA index in clozapine group and statistically significant negative correlation with LDL cholesterol in aripiprazole group of patients.

CONCLUSION

Patients on risperidone and clozapine therapy may be at greater risk of developing metabolic syndrome than patients treated with aripiprazole. Statistically significant difference in concentration of TNF-α and TGF-β was in the group of patients treated with risperidone compared to healthy control group.