Complement 3 and metabolic syndrome induced by clozapine: a cross-sectional study and retrospective cohort analysis

Complement Activation Products in Patients with Chronic Schizophrenia

Evidence suggests a role of the immune system in the pathogenesis of a number of mental conditions, including schizophrenia (SCH). In terms of physiology, aside from its crucial protective function, the complement cascade (CC) is a critical element of the regeneration processes, including neurogenesis. Few studies have attempted to define the function of the CC components in SCH. To shed more light on this topic, we compared the levels of complement activation products (CAP) (C3a, C5a and C5b-9) in the peripheral blood of 62 patients with chronic SCH and disease duration of ≥ 10 years with 25 healthy controls matched for age, sex, BMI and smoking status. Concentrations of all the investigated CAP were elevated in SCH patients. However, after controlling for potential confounding factors, significant correlations were observed between SCH and C3a (M = 724.98 ng/mL) and C5a (M = 6.06 ng/mL) levels. In addition, multivariate logistic regression showed that C3a and C5b-9 were significant predictors of SCH. There were no significant correlations between any CAP and SCH symptom severity or general psychopathology in SCH patients. However, two significant links emerged between C3a and C5b-9 and global functioning. Increased levels of both complement activation products in the patient group as compared to healthy controls raise questions concerning the role of the CC in the etiology of SCH and further demonstrate dysregulation of the immune system in SCH patients.

Differing Prevalence and Correlates of Metabolic Syndromes Between Chlorpromazine and Clozapine: A 10-year Retrospective Study of a Male Chinese Cohort

BACKGROUND

Antipsychotics are known to be associated with metabolic syndromes (MetS). Chlorpromazine (CPZ) and Clozapine (CLZ) are currently the most commonly used antipsychotics in low-income districts of China. However, potential differences in the long-term effects of CPZ and CLZ on MetS in schizophrenia inpatients are not well understood. Here, we aimed to identify any MetS profile differences between long-term schizophrenia patients who were prescribed either CPZ or CLZ at a primary psychiatric hospital.

METHODS

We recruited a total of 204 male schizophrenia patients who received either CPZ or CLZ. We measured their weight, height, body mass index (BMI), waist circumference (WC), diastolic blood pressure (DBP), and systolic blood pressure (SBP), as well as their biochemical indicators, including fasting blood glucose (FBS), triglycerides (TG), cholesterol (TC), high-density lipoprotein cholesterol (HDL-c) and low-density lipoprotein cholesterol (LDL-c).

RESULTS

The MetS prevalence in the CPZ and CLZ groups was 31% and 37.5%, respectively. The CLZ group had significantly higher DBP levels and a higher incidence of dyslipidemia (HDL-c) but lower HDL-c and TC levels than the CPZ group. We also determined that smoking history, BMI, and duration of hospitalisation were risk factors for the development of MetS. Moreover, we found that CPZ and CLZ were correlated with the same risk for developing MetS and that BMI was a vital risk factor of MetS for both the CPZ and CLZ groups.

CONCLUSION

Long-term CPZ and CLZ prescriptions were associated with similar profiles for developing MetS of schizophrenia patients.

Clozapine's multiple cellular mechanisms: What do we know after more than fifty years? A systematic review and critical assessment of translational mechanisms relevant for innovative strategies in treatment-resistant schizophrenia

Almost fifty years after its first introduction into clinical care, clozapine remains the only evidence-based pharmacological option for treatment-resistant schizophrenia (TRS), which affects approximately 30% of patients with schizophrenia. Despite the long-time experience with clozapine, the specific mechanism of action (MOA) responsible for its superior efficacy among antipsychotics is still elusive, both at the receptor and intracellular signaling level. This systematic review is aimed at critically assessing the role and specific relevance of clozapine's multimodal actions, dissecting those mechanisms that under a translational perspective could shed light on molecular targets worth to be considered for further innovative antipsychotic development. In vivo and in vitro preclinical findings, supported by innovative techniques and methods, together with pharmacogenomic and in vivo functional studies, point to multiple and possibly overlapping MOAs. To better explore this crucial issue, the specific affinity for 5-HT₂R, D1R, α_2c, and muscarinic receptors, the relatively low occupancy at dopamine D2R, the interaction with receptor dimers, as well as the potential confounder effects resulting in biased ligand action, and lastly, the role of the moiety responsible for lipophilic and alkaline features of clozapine are highlighted. Finally, the role of transcription and protein changes at the synaptic level, and the possibility that clozapine can directly impact synaptic architecture are addressed. Although clozapine's exact MOAs that contribute to its unique efficacy and some of its severe adverse effects have not been fully understood, relevant information can be gleaned from recent mechanistic understandings that may help design much needed additional therapeutic strategies for TRS.

Associations Between Genotype and Peripheral Complement Proteins in First-Episode Psychosis: Evidences From C3 and C4

Schizophrenia is a common neuropsychiatric disorder with complex pathophysiology. Recent reports suggested that complement system alterations contributed to pathological synapse elimination that was associated with psychiatric symptoms in schizophrenia. Complement component 3 (C3) and complement component 4 (C4) play central roles in complement cascades. In this study, we compared peripheral C3 and C4 protein levels between first-episode psychosis (FEP) and healthy control (HC). Then we explored whether single nucleotide polymorphisms (SNPs) at C3 or C4 genes affect peripheral C3 or C4 protein levels. In total, 181 FEPs and 204 HCs were recruited after providing written informed consent. We measured serum C3 and C4 protein levels using turbidimetric inhibition immunoassay and genotyped C3 and C4 polymorphisms using the Sequenom MassArray genotyping. Our results showed that three SNPs were nominally associated with schizophrenia (rs11569562/C3: A > G, p = 0.048; rs2277983/C3: A > G, p = 0.040; rs149898426/C4: G > A, p = 0.012); one haplotype was nominally associated with schizophrenia, constructed by rs11569562–rs2277983–rs1389623 (GGG, p = 0.048); FEP had higher serum C3 and C4 (both p < 0.001) levels than HC; rs1389623 polymorphisms were associated with elevated C3 levels in our meta-analysis (standard mean difference, 0.50; 95% confidence interval, 0.30 to 0.71); the FEP with CG genotype of rs149898426 had higher C4 levels than that with GG genotypes (p = 0.005). Overall, these findings indicated that complement system altered in FEP and rs149898426 of C4 gene represented a genetic risk marker for schizophrenia likely through mediating complement system. Further studies with larger sample sizes needs to be validated.

Clinical, Biochemical and Genetic Variables Associated With Metabolic Syndrome in Patients With Schizophrenia Spectrum Disorders Using Second-Generation Antipsychotics: A Systematic Review

Background: Individuals with severe mental illness experience increased morbidity and mortality compared to the general population. Adverse effects of antipsychotics, including weight gain, may contribute to the development of metabolic syndrome (MetS), which is associated with increased risks of all-cause and cardiovascular disease mortality. We aim to provide a comprehensive overview of clinical, biochemical and genetic factors associated with MetS among patients with schizophrenia spectrum disorders using second-generation antipsychotics (SGA). Methods: A literature search was performed in Pubmed and Embase to identify all cohort studies, cross-sectional studies and clinical trials investigating associations with MetS in patients with schizophrenia spectrum disorders using SGAs. We extracted and enumerated clinical, biochemical and genetic factors reported to be associated with MetS. We defined factors associated with MetS as factors being reported as associated with MetS in two or more studies. Results: 58 studies were included in this review (n = 12,123). In total, 62 factors were found to be associated with increased risk of MetS. Thirty one out of 58 studies investigated factors that were reported as associated with MetS in two or more studies. With regard to clinical factors, we found gender, higher age, concomitant use of mood stabilizers, higher baseline and current BMI, earlier SGA exposure, higher dose, longer duration of treatment, psychosis and tobacco smoking to be significantly associated with MetS. Furthermore, the biochemical factors hypo-adiponectinemia, elevated levels of C-reactive protein (CRP) and higher white blood cell (WBC) count were identified as factors associated with MetS. Among pharmacogenetic factors, the rs1414334 C-allele of the HTR2C-gene was associated with MetS in patients using SGA. Conclusion: In this systematic review investigating clinical, biochemical and genetic factors associated with MetS in patients using SGAs we found that higher age, higher baseline BMI, higher current BMI and male as well as female gender were positively associated with MetS across all antipsychotics. This study may set the stage for the application of clinical, biochemical and genetic factors to predict the risk of developing MetS in patients using SGAs. Future research is needed to determine which patients using SGAs are at risk to develop MetS in clinical practice.

Omega-3 fatty acids ameliorate cognitive dysfunction in schizophrenia patients with metabolic syndrome

Our previous study showed that metabolic abnormalities reduced the levels of brain-derived neurotrophic factor (BDNF) and deteriorated cognitive performance in patients with schizophrenia. Inflammation may play a key role in this process. Omega-3 fatty acids have been documented to ameliorate inflammation. Therefore, we hypothesized that omega-3 fatty acids may be of value in enhancing BDNF levels and improving cognitive function in patients with schizophrenia with metabolic syndrome (MetS). We recruited 80 patients with both schizophrenia and MetS who received long-term olanzapine monotherapy. The enzyme-linked immunosorbent assay was used to measure the plasma levels of C-reactive protein (CRP), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α). The patients were randomly assigned to the OMG-3 group (n = 40) or the placebo group (n = 40). Of the 80 patients who consented to the study, 72 completed this 12-week RCT. The primary outcome was the changes from baseline to 12 weeks in clinical characteristics and the levels of BDNF, CRP, IL-6 and TNF-α. There was a significant correlation between omega-3 fatty acid treatment and enhanced delayed memory factor in the RBANS assessment (F_group×time = 6.82; df = 1, 66; P = 0.01) when the patients completed this study. Along with cognitive improvement, omega-3 fatty acids enhanced BDNF (F_group×time = 4.93; df = 1, 66; P = 0.03) and reduced CRP (F_group×time = 17.11; df = 1, 66; P < 0.01), IL-6 (F_group×time = 9.71; df = 1, 66; P < 0.004) and TNF-α (F_group×time = 6.71; df = 1, 66; P = 0.012) levels after 12 weeks of treatment. The changes in BDNF levels are negatively correlated with the changes in TNF-α levels (r = -0.37, P = 0.03) but not with the changes in CRP and IL-6 levels. Our findings provide suggestive evidence that omega-3 fatty acids have beneficial effects on cognitive function in patients with MetS, which is paralleled by enhanced BDNF levels.

Pharmacogenetics of Antipsychotic Drug Treatment: Update and Clinical Implications

Numerous genetic variants have been shown to be associated with antipsychotic response and adverse effects of schizophrenia treatment. However, the clinical application of these findings is limited. The aim of this narrative review is to summarize the most recent publications and recommendations related to the genetics of antipsychotic treatment and shed light on the clinical utility of pharmacogenetics/pharmacogenomics (PGx). We reviewed the literature on PGx studies with antipsychotic drugs (i.e., antipsychotic response and adverse effects) and commonly used commercial PGx tools for clinical practice. Publications and reviews were included with emphasis on articles published between January 2015 and April 2018. We found 44 studies focusing on antipsychotic response and 45 studies on adverse effects (e.g., antipsychotic-induced weight gain, movement disorders, hormonal abnormality, and clozapine-induced agranulocytosis/granulocytopenia), albeit with mixed results. Overall, several gene variants related to antipsychotic response and adverse effects in the treatment of patients with schizophrenia have been reported, and several commercial pharmacogenomic tests have become available. However, further well-designed investigations and replication studies in large and well-characterized samples are needed to facilitate the application of PGx findings to clinical practice.

Association Between SIRT1, Cytokines, and Metabolic Syndrome in Schizophrenia Patients With Olanzapine or Clozapine Monotherapy

Objective: Previous studies consistently showed the interaction between Sirtuin 1 (SIRT1) and immune inflammation is significantly related to metabolic abnormalities, but their role in the pathogenesis of metabolic syndrome caused by second-generation antipsychotics (SGAs) in schizophrenia patients largely remains unknown. Hence, the present study aimed to fill this gap. Methods: A total of 54 schizophrenia patients with olanzapine or clozapine monotherapy [metabolic syndrome (MetS)/non-MetS patients, 27/27] and 67 healthy subjects were recruited in the present study. The Positive and Negative Syndrome Scale was used, and the plasma levels of SIRT1, interleukin 6 (IL-6), IL-8, IL-10, and tumor necrosis factor α (TNF-α) were measured. Results: The results showed that schizophrenia patients treated with olanzapine or clozapine (both MetS and non-MetS groups) had significantly higher plasma levels of IL-6, IL-10, and TNF-α compared to normal controls (all P < 0.05). Moreover, the MetS patients exhibited markedly lower plasma levels of SIRT1 and higher plasma levels of IL-6 than non-MetS patients and normal controls (all P < 0.05). However, there were no significant differences in IL-8 levels between groups. Our correlation analysis showed that SIRT1 was significantly correlated with diastolic blood pressure, triglyceride, and high-density lipoprotein cholesterol in schizophrenia patients. The stepwise logistic regression analysis further identified the IL-6 × SIRT1 (β = -0.463, t = 10.040, P = 0.002) as the influencing factor for the MetS in the patients. Conclusion: Our preliminary findings suggest that SIRT1 interacted with inflammatory cytokines associated with MetS in schizophrenia patients treated with SGA monotherapy.

Effects of omega-3 fatty acids on metabolic syndrome in patients with schizophrenia: a 12-week randomized placebo-controlled trial

RATIONALE

Individuals with schizophrenia are at increased risk of developing metabolic syndrome (MetS) due to their lifestyle and antipsychotic treatment. Our previous study showed that patients with both schizophrenia and MetS present an increased expression and production of tumor necrosis factor-alpha (TNF-alpha). Omega-3 fatty acids have a documented role in suppressing TNF-alpha; therefore, we hypothesized that they may be of value in relieving inflammation and improving metabolic disturbance in patients with both schizophrenia and MetS.

OBJECTIVES

This study employed a randomized placebo-controlled trial to investigate the effects of omega-3 fatty acids on MetS in patients with schizophrenia.

METHODS

We recruited 80 patients with both schizophrenia and MetS who received long-term olanzapine monotherapy. The patients were randomly assigned to the OMG-3 group (n = 40) or the placebo group (n = 40).

RESULTS

Patients with both schizophrenia and MetS had significantly higher levels of TNF-alpha than the control subjects (Z = - 4.37, P < 0.01). There was a significant correlation between omega-3 fatty acid treatment and reduced triglyceride (TG) levels (F_{group × time} = 13.42; df = 1, 66; P < 0.01) when the patients completed this study. Along with metabolic improvement, omega-3 fatty acids decreased TNF-alpha levels after 12 weeks of treatment (F_{group × time} = 6.71; df = 1, 66; P = 0.012). We also found that the extent of TNF-alpha decrease was significantly correlated with that of TG decrease (r = 0.38, P = 0.001).

CONCLUSIONS

Our findings provide suggestive evidence that omega-3 fatty acids have beneficial effects on TG metabolism in patients with both schizophrenia and MetS that parallel decreased inflammation levels.

Identification of risk factors for suicidal ideation in patients with schizophrenia

Patients with schizophrenia have a high risk for suicide, and therefore, identification of risk factors for suicidal ideation (SI) may be helpful to reduce suicide rate. This study aimed to detect which clinical symptoms and biochemical parameters were most strongly associated with SI. A total of 174 patients and 35 healthy controls were enrolled in our study. Patients were evaluated by the Positive and Negative Syndrome Scale (PANSS), Scale of Assessment Negative Symptoms (SANS) and the Calgary Depression Scale for Schizophrenia (CDSS) for psychiatric and depressive symptoms, and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) for cognitive function. We examined the levels of prolactin (PRL) and metabolic parameters in all participants. Our results showed a significantly increased level of PRL in patients compared to the controls before (t = 10.414, P < 0.001) and after (F = 31.308, P < 0.001) covariates were controlled for. In addition, we found that patients with SI had significantly higher PRL levels than those without SI (t = 2.586, P = 0.011). And there were positive correlations between serum PRL levels (r = 0.194, P = 0.010), serum fasting triglyceride levels (TG) (r = 0.188, P = 0.013), and RBANS visuospatial skill subscores (r = 0.162, P = 0.036) and SI severity. Finally, the stepwise multiple linear regression analysis revealed that SI severity was significantly associated with PRL levels, fasting TG levels and RBANS visuospatial skill subscores. This study provides support that greater cognitive ability, specifically visuospatial skill, PRL and TG, may confer an elevated risk for more severe SI in schizophrenia patients.

New findings in pharmacogenetics of schizophrenia

PURPOSE OF REVIEW

This review highlights recent advances in the investigation of genetic factors for antipsychotic response and side effects.

RECENT FINDINGS

Antipsychotics prescribed to treat psychotic symptoms are variable in efficacy and propensity for causing side effects. The major side effects include tardive dyskinesia, antipsychotic-induced weight gain (AIWG), and clozapine-induced agranulocytosis (CIA). Several promising associations of polymorphisms in genes including HSPG2, CNR1, and DPP6 with tardive dyskinesia have been reported. In particular, a functional genetic polymorphism in SLC18A2, which is a target of recently approved tardive dyskinesia medication valbenazine, was associated with tardive dyskinesia. Similarly, several consistent findings primarily from genes modulating energy homeostasis have also been reported (e.g. MC4R, HTR2C). CIA has been consistently associated with polymorphisms in the HLA genes (HLA-DQB1 and HLA-B). The association findings between glutamate system genes and antipsychotic response require additional replications.

SUMMARY

The findings to date are promising and provide us a better understanding of the development of side effects and response to antipsychotics. However, more comprehensive investigations in large, well characterized samples will bring us closer to clinically actionable findings.

Genetic variants impacting metabolic outcomes among people on clozapine: a systematic review and meta-analysis

Clozapine is the gold standard medication for treatment refractory schizophrenia, but unfortunately, its use is also associated with many adverse metabolic side effects. There may be a strong genetic component to the development of these adverse effects. We undertook a systematic review to examine the evidence for genetic variation being associated with secondary metabolic outcomes in patients with schizophrenia on clozapine, under both longitudinal and cross-sectional study designs. We limited studies to those examining patients definitely taking clozapine, unlike prior reviews that have examined metabolic effects of patients taking a range of antipsychotic medications. We found associations with outcomes such as increases in BMI and metabolic syndrome for variants in genes such as LEP and HTR2C. Meta-analysis of rs381328 in HTR2C revealed that the presence of the T allele led to a 0.63 kg/m² (95% CI - 1.06 to - 0.19; p = 0.005) decrease in BMI compared to the C allele. Study and population heterogeneity and lack of statistical power among reviewed articles mean that evidence is lacking to warrant prophylactic genotyping of patients commencing clozapine to predict those at increased risk of developing adverse metabolic effects. Further efforts to establish collaborative consortia, consensus around study design and replication studies in independent populations should be encouraged.

Metabolic adverse effects of olanzapine on cognitive dysfunction: A possible relationship between BDNF and TNF-alpha

OBJECTIVE

There is accumulating evidence indicating that long-term treatment with second-generation antipsychotics (SGAs) results in metabolic syndrome (MetS) and cognitive impairment. This evidence suggests an intrinsic link between antipsychotic-induced MetS and cognitive dysfunction in schizophrenia patients. Olanzapine is a commonly prescribed SGA with a significantly higher MetS risk than that of most antipsychotics. In this study, we hypothesized that olanzapine-induced MetS may exacerbate cognitive dysfunction in patients with schizophrenia.

METHODS

A sample of 216 schizophrenia patients receiving long-term olanzapine monotherapy were divided into two groups, MetS and non-MetS, based on the diagnostic criteria of the National Cholesterol Education Program's Adult Treatment Panel III. We also recruited 72 healthy individuals for a control group. Cognitive function was evaluated using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Plasma brain-derived neurotrophic factor (BDNF) and tumor necrosis factor-alpha (TNF-alpha) were measured by an enzyme-linked immunosorbent assay for 108 patients and 47 controls.

RESULTS

Among the 216 schizophrenia patients receiving olanzapine monotherapy, MetS was found in 95/216 (44%). Patients with MetS had more negative symptoms, higher total scores in PANSS (Ps<0.05) and lower immediate memory, attention, delayed memory and total scores in RBANS (Ps<0.01). Stepwise multivariate linear regression analysis revealed that increased glucose was the independent risk factor for cognitive dysfunction (t=-2.57, P=0.01). Patients with MetS had significantly lower BDNF (F=6.49, P=0.012) and higher TNF-alpha (F=5.08, P=0.026) levels than those without MetS. There was a negative correlation between the BDNF and TNF-alpha levels in the patients (r=-0.196, P=0.042).

CONCLUSION

Our findings provide evidence suggesting that the metabolic adverse effects of olanzapine may aggravate cognitive dysfunction in patients with schizophrenia through an interaction between BDNF and TNF-alpha.

Identification of IL6 as a susceptibility gene for major depressive disorder

Our previous work implied that interleukin 6 (IL6) may be a biological marker for major depressive disorder (MDD). In this study, we performed a comprehensive genetic study to determine the association between the gene encoding IL6 (IL6) and MDD in Han Chinese. There were 50 drug-naïve MDD patients and 50 healthy controls undergoing an mRNA expression study. A sample of 772 patients with MDD and 759 healthy controls were used for genetic analysis. Next, we performed an eQTL analysis to identify whether risk SNP(s) is associated with IL6 expression in brain. Our results showed that patients with MDD have higher levels of IL6 than healthy controls (P = 0.008). The SNP rs1800797 has a significant association with MDD (P = 0.01) in a dominant model. The eQTL analysis showed a marginally significant association between the rs1800797 and IL6 expression in the frontal cortex (P = 0.087). Our preliminary findings are suggestive of an association between rs1800797 and the risk of MDD. Further investigations are required to evaluate this association in larger samples to increase statistical power, and to examine the correlation between rs1800797 and IL6 methylation patterns.