Increased high-sensitivity C-reactive protein levels in Taiwanese schizophrenic patients

A systematic review of clozapine-associated inflammation and related monitoring

Clozapine is an effective antipsychotic medication used for treatment-resistant schizophrenia. However, it is underutilized due to rigorous hematologic monitoring requirements and many adverse drug reactions. Publications have highlighted the occurrence of inflammatory reactions, some life-threatening, particularly during the early stages of clozapine treatment. Although guidelines have suggested monitoring for inflammatory processes during clozapine initiation, screening in clinical practice is not universal. This systematic review aimed to investigate the relationship between clozapine and inflammation and assess the importance of monitoring for inflammatory reactions. A comprehensive literature search yielded 6915 unique publication records after removal of duplicates. After a rigorous screening process, 75 publications were included in the review, which focused on three main aspects: (i) the impact of clozapine on inflammatory markers, (ii) monitoring cardiac and other organ function during clozapine-associated inflammatory processes, and (iii) monitoring non-specific signs and symptoms of inflammation. Elevated levels of C-reactive protein (CRP) and several proinflammatory cytokines have been observed in association with clozapine treatment. However, the practicality of measuring specific markers in clinical practice remains uncertain. Current evidence supports monitoring CRP levels during the first 4-8 weeks of treatment, especially to facilitate myocarditis screening. Further research is needed to establish clinically relevant CRP thresholds for intervention. The implementation of monitoring protocols during the early phase of clozapine treatment may mitigate adverse reactions and allow for continued use of clozapine. Future studies should also explore the association between clozapine-associated inflammation and pneumonia, as well as investigate the impact of inflammation on clozapine metabolism to predict the need for dose adjustment. These endeavors may facilitate the development and implementation of evidence-based guidelines for the monitoring of clozapine-associated inflammation.

Could CRP be a differential biomarker of illness stages in schizophrenia? A systematic review and meta-analysis

BACKGROUND

Patients with schizophrenia display peripheral inflammation but the impact of illness phase is not clear. Our meta-analysis investigated the difference in CRP levels between patients with schizophrenia and controls according to their illness phase.

METHODS

After a systematic search, all studies measuring CRP in patients with schizophrenia and controls were included. Standardized mean differences were calculated between patients and controls according to illness phase. The influence of sociodemographic and clinical variables on our results was investigated using a meta-regression analysis.

RESULTS

Fifty studies were included in this meta-analysis. Patients with schizophrenia had higher CRP levels than controls in the acute (p < 0.00001) and stable (p < 0.00001) stage of their disease. Patients with acute exacerbation of schizophrenia had higher CRP levels than stable patients (p = 0.02) but this difference did not persist when considering antipsychotic-medicated patients in both phases. Meta-regressions found that the increase of CRP in acutely ill patients as compared to controls was influenced by age (p < 0.01), BMI (p = 0.01) and first episode (p = 0.02), whereas the increase in CRP levels of stable patients as compared to controls was moderated by BMI (p = 0.004).

CONCLUSIONS

In conclusion, this meta-analysis provides strong evidence that patients with schizophrenia have higher CRP levels than controls, but also show an increase in inflammatory response in the acute stage of the disease as compared to the stable stage. CRP could thus be considered as a state marker and a trait marker of the disease.

Neuroinflammation in schizophrenia: the role of nuclear factor kappa B

Neuroinflammation, particularly in the dorsolateral prefrontal cortex, is well-established in a subset of people with schizophrenia, with significant increases in inflammatory markers including several cytokines. Yet the cause(s) of cortical inflammation in schizophrenia remains unknown. Clues as to potential microenvironmental triggers and/or intracellular deficits in immunoregulation may be gleaned from looking further upstream of effector immune molecules to transcription factors that control inflammatory gene expression. Here, we focus on the 'master immune regulator' nuclear factor kappa B (NF-κB) and review evidence in support of NF-κB dysregulation causing or contributing to neuroinflammation in patients. We discuss the utility of 'immune biotyping' as a tool to analyse immune-related transcripts and proteins in patient tissue, and the insights into cortical NF-κB in schizophrenia revealed by immune biotyping compared to studies treating patients as a single, homogenous group. Though the ubiquitous nature of NF-κB presents several hurdles for drug development, targeting this key immunoregulator with novel or repurposed therapeutics in schizophrenia is a relatively underexplored area that could aid in reducing symptoms of patients with active neuroinflammation.

Association of high-sensitivity C-reactive protein with susceptibility to Schizophrenia in Tunisian population

The pathogenic mechanisms underlying Schizophrenia (SZ), one of the most frequent mental disorders, are complex and poorly understood. Several evidences suggest that inflammatory processes may underpin some of its neurobiological correlates. The aim of this study was: (i) to analyze the potential association between circulating levels of the C-reactive protein (CRP), a crucial inflammatory marker, and Schizophrenia in Tunisian patients and healthy controls (HC) cohorts; (ii) to investigate the genetic diversity of three CRP variants (rs1417938, rs1130864 and rs1205) and; (iii) to analyze a potential relationship between expression and genetic data and clinical and socio demographical characteristics. CRP polymorphisms were exanimated for 155 patients and 203 HC by taqMan5'-nuclease. High-sensitivity CRP (hs-CRP) serum level was measured in 128 clinically stable out-patient SZ patients and 63 HC subjects via an automated biochemical analyzer. We found that hs-CRP levels were significantly higher in SZ patients as compared to HC. No significant differences were found when the proportions of CRP variants were compared in patients and HC. Further analysis according to clinical and socio demographical characteristics revealed a positive association with age and hypertension. Our data on an original Tunisian sample confirm the previous finding in others population groups.

Regulation of inflammatory pathways in schizophrenia: A comparative study with bipolar disorder and healthy controls

Background

Immune-inflammatory processes have been implicated in schizophrenia (SCH), but their specificity is not clear.

Main aim

To identify potential differential intra-/intercellular biochemical pathways controlling immune-inflammatory response and their oxidative-nitrosative impact on SCH patients, compared with bipolar disorder (BD) patients and healthy controls (HC).

Methods

Cross-sectional, naturalistic study of a cohort of SCH patients (n=123) and their controls [BD (n=102) and HC (n=80)].

Statistical analysis

ANCOVA (or Quade test) controlling for age and gender when comparing the three groups, and controlling for age, gender, length of illness, cigarettes per day, and body mass index (BMI) when comparing SCH and BD.

Results

Pro-inflammatory biomarkers: Expression of COX-1 was statistically higher in SCH and BD than HC (P<0.0001; P<0.0001); NFκB and PGE2 were statistically higher in SCH compared with BD (P=0.001; P<0.0001) and HC (P=0.003; P<0.0001); NLRP3 was higher in BD than HC (P=0.005); and CPR showed a gradient among the three groups. Anti-inflammatory biomarkers: BD patients had lower PPARγ and higher 15d-PGJ2 levels than SCH (P=0.005; P=0.008) and HC (P=0.001; P=0.001). Differences between SCH and BD: previous markers of SCH (NFκB and PGE2) and BD (PPARγ and 15d-PGJ2) remained statistically significant and, interestingly, iNOS and COX-2 (pro-inflammatory biomarkers) levels were statistically higher in SCH than BD (P=0.019; P=0.040).

Conclusions

This study suggests a specific immune-inflammatory biomarker pattern for established SCH (NFκB, PGE2, iNOS, and COX-2) that differentiates it from BD and HC. In future, their pharmacological modulation may constitute a promising therapeutic target.

Immunoendocrine Peripheral Effects Induced by Atypical Antipsychotics

Atypical antipsychotics (AAP) or second-generation antipsychotics are the clinical option for schizophrenia treatment during acute psychoses, but they are also indicated for maintenance during lifetime, even though they are being used for other psychiatric conditions in clinical practice such as affective disorders and autism spectrum disorder, among others. These drugs are differentiated from typical antipsychotics based on their clinical profile and are a better choice because they cause fewer side effects regarding extrapyramidal symptoms (EPS). Even though they provide clear therapeutic benefits, AAP induce peripheral effects that trigger phenotypic, functional, and systemic changes outside the Central Nervous System (CNS). Metabolic disease is frequently associated with AAP and significantly impacts the patient's quality of life. However, other peripheral changes of clinical relevance are present during AAP treatment, such as alterations in the immune and endocrine systems as well as the intestinal microbiome. These less studied alterations also have a significant impact in the patient's health status. This manuscript aims to revise the peripheral immunological, endocrine, and intestinal microbiome changes induced by AAP consumption recommended in the clinical guidelines for schizophrenia and other psychiatric disorders.

Decreased Serum Oxytocin and Increased Homocysteine in First-Episode Schizophrenia Patients

Schizophrenia (SZ) is a debilitating and heterogeneous disease. We hypothesized that the oxytocin (OXT) system, inflammation and one-carbon metabolism would have a link with SZ. In this study, serum OXT, OXT receptor (OXTR), interleukin-6 (IL-6), high sensitivity CRP (hsCRP) and homocysteine (Hcy) levels were measured in 52 first-episode schizophrenia (FES) patients and 41 healthy controls (HC) from the Second Xiangya Hospital of Central South University. Meanwhile, the mRNA expressions of OXT and OXTR genes were determined by real-time quantitative PCR. Serum OXT and OXTR levels were significantly lower in FES patients (518.96 ± 22.22 and 174.60 ± 17.11 pg/ml) than the HC group (711.58 ± 40.57 and 252.15 ± 20.62 pg/ml). Serum IL-6 and hsCRP levels showed no difference between the two groups (1.82 ± 0.30 vs. 1.69 ± 0.36 pg/ml, 0.66 (0.22, 1.07) vs. 0.31 (0.13, 0.91) mg/L), but serum Hcy levels were significantly higher in FES patients (20.18 ± 1.83 vs. 15.24 ± 0.82 μmol/ml). The FES patients (0.27 ± 0.02 and 0.20 ± 0.02) have relatively higher mRNA expressions of OXT and OXTR genes than the HC group (0.16 ± 0.01 and 0.14 ± 0.01). In summary, our results suggested the possible function of the OXT system and Hcy in the pathogenesis of SZ.

Elevated levels of C-reactive protein and IL-6 among the antipsychotic medicating schizophrenia patients of Siliguri, West Bengal, India

PURPOSE

Chronic, low-grade inflammation is a proposed etiological factor associated with schizophrenia. Thus, various studies have been conducted to understand the role of inflammatory process in schizophrenia by using inflammatory maker C-reactive protein (CRP) with conflicting findings. Inadvertently, studies of CRP among the Indian schizophrenia patients are very few. Therefore, the present study was undertaken to investigate the role of inflammatory process among Indian Bengalee schizophrenia patients of Siliguri, using the marker CRP and its stimulating cytokine interleukin-6 (IL-6). In addition, the study also intended to investigate the immunomodulatory effect of antipsychotic medication on serum levels of CRP and IL-6.

MATERIALS AND METHODS

The serum levels of CRP and IL-6 were measured by Enzyme-Linked Immunosorbent Assay (ELISA) among 67 antipsychotic medicating, 28 psychotropic medication-free schizophrenia patients, and it was compared with 72 age, sex and ethnicity-matched controls.

RESULTS

A significantly higher level of CRP and IL-6 were recorded among the antipsychotic medicating patients. Although CRP was found to be higher among the psychotropic medication-free patients than the controls, it was not found to be significant. However, a significantly higher level of IL-6 was observed in this group.

CONCLUSIONS

The results provide the evidence for a possible immunomodulatory effect of antipsychotic drugs on CRP. Future investigations including the study of antipsychotics separately may help to understand the differential effects of individual antipsychotics on CRP level. Additional studies with a larger sample size of psychotropic medication-free patients may help to verify the role of inflammation in schizophrenia patients of this region.

Protein-C Reactive as Biomarker Predictor of Schizophrenia Phases of Illness? A Systematic Review

BACKGROUND

Schizophrenia is a complex illness in which genetic, environmental, and epigenetic components have been implicated. However, recently, psychiatric disorders appear to be related to a chronic inflammatory state, at the level of specific cerebral areas which have been found as well impaired and responsible for schizophrenia symptomatology. Hence, a role of inflammatory mediators and cytokines has been as well defined. Accordingly, the role of an acute inflammatory phase protein, the C-reactive protein (CRP) has been recently investigated.

OBJECTIVE

The objective of the present study is to evaluate how PCR may represent a biomarker in schizophrenia, i.e. correlated with illness phases and/or clinical manifestation and/or psychopathological severity.

METHODS

A systematic review was here carried out by searching the following keywords ((C-reactive protein AND ((schizophrenia) OR (psychotic disorder))) for the topics 'PCR' and 'Schizophrenia', by using MESH terms.

RESULTS

An immune dysfunction and inflammation have been described amongst schizophrenic patients. Findings reported elevated CRP levels in schizophrenia, mainly correlated with the severity of illness and during the recrudescent phase. CRP levels are higher when catatonic features, negative symptomatology and aggressiveness are associated. CRP levels appeared not to be related to suicidal behaviour and ideation.

CONCLUSION

CRP and its blood levels have been reported higher amongst schizophrenic patients, by suggesting a role of inflammation in the pathogenesis of schizophrenia. Further studies are needed to better understand if CRP may be considered a biomarker in schizophrenia.

Peripheral blood gene expression of acute phase proteins in people with first episode psychosis

BACKGROUND

There is a growing interest in the association between schizophrenia and the activation of inflammatory system with signs of acute phase (AP) response. Majority of such studies had focused on C-reactive protein (CRP). The aims of the present study were (i) to examine the gene expression profiles of other acute phase proteins (APP), namely haptoglobin (HP), alpha-1 antitrypsin (A1T), and alpha-2 macroglobulin (A2M) in patients with first episode psychosis (FEP) over a period of three months and (ii) to explore the association between APP levels and severity of symptoms.

METHODS

In this study, HP, A1T and A2M gene expression levels from whole blood were measured at recruitment, 1- and 3-month follow-up visits using quantitative PCR (qPCR) in 43 patients with FEP and in 57 healthy controls. Diagnoses was ascertained on the Structured Clinical Interview for DSM-IV-TR. Severity of symptoms in patients was assessed on the Positive and Negative Syndrome Scale (PANSS) and a previously validated 5-factor PANSS structure was applied in the subsequent analyses.

RESULTS

The FEP sample comprised of 28 (65.1%) individuals with schizophrenia, 12 (27.9%) with schizophreniform disorder and 3 (7%) with schizoaffective disorder. HP gene expression level was noted to be significantly higher in patients than controls at all three time points: recruitment (P=0.049), 1-month follow up (P=0.002) and 3-month follow up (P=0.005). PANSS positive, depression, and excitement symptom factors showed significant associations with HP (P=0.002), A1T (P=0.016) and A2M (P=0.034), respectively. These findings remained significant after controlling for age, gender, smoking status and accumulated chlorpromazine dosage.

CONCLUSION

The current study provides information on HP, A1T and A2M gene expression profiles in FEP patients and their associations with psychopathology. This provides support for the hypothesis that inflammation is related to schizophrenia and further encourages studies on immune-inflammatory markers to understand the relationship between inflammation and schizophrenia.

Association between C-reactive protein and risk of schizophrenia: An updated meta-analysis

C-reactive protein (CRP) has been indicated to be associated with the pathogenesis of schizophrenia (SZ) and other psychiatric disorders. The aim of this study is to investigate whether peripheral blood CRP levels are associated with the risk of SZ. We searched literature from databases of Pubmed, Embase and the Cochrane Library from inception to November 1, 2016 for studies that reported serum or plasma CRP levels in patients with SZ and non-SZ controls. At least two reviewers decided on eligibility and extracted data from included studies. Random effects meta-analyses were performed using standardized mean difference (SMD) as the effect estimate of the differences in CRP levels between subjects with SZ and healthy controls. We identified 18 studies representing 1963 patients with SZ and 3683 non-SZ controls. Compared with non-schizophrenics, blood CRP levels were moderately increased in people with SZ (SMD 0.53, 95% CI 0.30 to 0.76) irrespective of study region, sample size of included studies, patient mean age, age of SZ onset and patient body mass index. Publication bias was not detected through Egger's linear regression test (P = 0.292). We noticed that patients in Asia or Africa (n = 6, SMD 0.73, 95% CI 0.26 to 1.21) and whose age less than 30 years (n = 5, SMD 0.76, 95% CI 0.07 to 1.58) had substantially higher CRP levels. Our study provides evidence that higher CRP levels are associated with increased risk of SZ, especially for young adult patients less than 30 years. Further large-scale studies are strongly warranted to further confirm this association.

C-reactive protein and white blood cell levels in schizophrenia, bipolar disorders and depression - associations with mortality and psychiatric outcomes: a population-based study

BACKGROUND

Mental disorders have been associated with increased levels of inflammatory markers, which can affect disease trajectories. We aimed to assess levels of C-reactive protein (CRP) and white blood cells (WBC) across individuals with schizophrenia, bipolar disorder, and depression, and to investigate associations with subsequent psychiatric admission and mortality.

METHODS

We identified all adults in the Central Denmark Region during 2000-2012 with a first diagnosis of schizophrenia, bipolar disorder, or depression and a baseline measurement of CRP and/or WBC count. We followed these individuals until outcome of interest (psychiatric admission or death), emigration or December 31, 2012, using Cox regression analysis to estimate hazard ratios (HRs).

RESULTS

Baseline median CRP differed significantly between mental disorders (P=0.01) being highest in individuals with bipolar disorder (3.5mg/L) (particularly during manic states, 3.9mg/L), followed by schizophrenia (3.1mg/L), and depression (2.8mg/L), while baseline WBC count did not differ (median 7.1×10⁹/L). Elevated CRP levels were associated with increased all-cause mortality by adjusted HRs of 1.56 (95% CI: 1.02-2.38) for levels 3-10mg/L and 2.07 (95% CI: 1.30-3.29) for levels above 10mg/L compared to individuals with levels below 3mg/L. WBC counts were not associated with all-cause mortality. No association was observed between levels of the inflammatory markers and subsequent psychiatric admissions.

CONCLUSIONS

People with severe mental disorders had increased inflammatory markers at first diagnosis, and elevated CRP levels were associated with increased mortality. Thorough screening for physical diseases is of utmost importance among individuals who are diagnosed with severe mental disorder.

A significant causal association between C-reactive protein levels and schizophrenia

Many observational studies have shown elevated blood CRP levels in schizophrenia compared with controls, and one population-based prospective study has reported that elevated plasma CRP levels were associated with late- and very-late-onset schizophrenia. Furthermore, several clinical studies have reported the efficacy of anti-inflammatory drugs on the symptoms in patients with schizophrenia. However, whether elevated CRP levels are causally related to schizophrenia is not still established because of confounding factors and reverse causality. In the present study, we demonstrated that serum CRP levels were significantly higher in patients with schizophrenia than in the controls by conducting a case-control study and a meta-analysis of case-control studies between schizophrenia and serum CRP levels. Furthermore, we provided evidence for a causal association between elevated CRP levels and increased schizophrenia risk by conducting a Mendelian randomization analysis. Our findings suggest that elevated CRP itself may be a causal risk factor for schizophrenia.

C-reactive protein is increased in schizophrenia but is not altered by antipsychotics: meta-analysis and implications

The inflammatory hypothesis of schizophrenia (SZ) posits that inflammatory processes and neural-immune interactions are involved in its pathogenesis, and may underpin some of its neurobiological correlates. SZ is the psychiatric disorder causing the most severe burden of illness, not just owing to its psychiatric impairment, but also owing to its significant medical comorbidity. C-reactive protein (CRP) is a commonly used biomarker of systemic inflammation worldwide. There are some conflicting results regarding the behaviour of CRP in SZ. The aims of this study were to verify whether peripheral CRP levels are indeed increased in SZ, whether different classes of antipsychotics divergently modulate CRP levels and whether its levels are correlated with positive and negative symptomatology. With that in mind, we performed a meta-analysis of all cross-sectional studies of serum and plasma CRP levels in SZ compared to healthy subjects. In addition, we evaluated longitudinal studies on CRP levels before and after antipsychotic use. Our meta-analyses of CRP in SZ included a total of 26 cross-sectional or longitudinal studies comprising 85 000 participants. CRP levels were moderately increased in persons with SZ regardless of the use of antipsychotics and did not change between the first episode of psychosis and with progression of SZ (g=0.66, 95% confidence interval (95% CI) 0.43 to 0.88, P<0.001, 24 between-group comparisons, n=82 962). The extent of the increase in peripheral CRP levels paralleled the increase in severity of positive symptoms, but was unrelated to the severity of negative symptoms. CRP levels were also aligned with an increased body mass index. Conversely, higher age correlated with a smaller difference in CRP levels between persons with SZ and controls. Furthermore, CRP levels did not increase after initiation of antipsychotic medication notwithstanding whether these were typical or atypical antipsychotics (g=0.01, 95% CI -0.20 to 0.22, P=0.803, 8 within-group comparisons, n=713). In summary, our study provides further evidence of the inflammatory hypothesis of SZ. Whether there is a causal relationship between higher CRP levels and the development of SZ and aggravation of psychotic symptoms, or whether they are solely a marker of systemic low-grade inflammation in SZ, remains to be clarified.

Identification of putative biomarkers for HIV-associated neurocognitive impairment in the CSF of HIV-infected patients under cART therapy determined by mass spectrometry

We identified and measured proteins in the cerebral spinal fluid (CSF) involved in HIV-associated neurological disorders. Protein levels were determined by mass spectrometry (MS) in pooled CSF taken from three patient groups (human immunodeficiency virus (HIV)-1-infected patients that developed HIV-associated neurocognitive disorders (HANDs), HIV-1-infected patients without HAND, and healthy controls). Pools were generated from 10 patients each per group. CSF from individual patient groups were digested with trypsin and separately labeled using with isobaric tags for relative and absolute quantitation (iTRAQ). After combining all samples in one, peptides were extensively fractionated by offline two-dimensional separation and identified by tandem MS. One hundred and ninety three proteins were deemed to be interpretable for quantitation based on permutation tests with a 95 % confidence interval with a p value ≤ 0.05. Using a cutoff of 1.5-fold for upregulation and 0.6 for downregulation, 16 proteins were differentially expressed in HIV + HAND (reporter p value ≤0.05) with seven of them previously described as HIV-interacting proteins: endoplasmin, mitochondrial damage mediator-BH3-interacting domanin death agonist, orosomucoid, apolipoprotein E, metalloproteinase inhibitor 2, peroxiredoxin-2, and the nuclear protein, ruvB-like 2. Several previously unidentified proteins with possible neurological implication in HIV patients include forming-binding protein 1, C-reactive protein, leukocyte-associated immunoglobulin receptor 1, renin receptor, mediator of RNA polymerase II transcription subunit 14, multimerin-2, alpha-N-acetylglucosaminidase, caldesmon, and cadherin EGF LAG G-type receptor. Our results suggest that not only a few but possibly a combination of biomarkers that are highly correlated can predict neurocognitive status in HIV-infected patients and might be involved in monocyte or macrophage activation.

Role of C-reactive protein in schizophrenia: an overview

Over the years, schizophrenia is speculated to be associated with immune or inflammatory reactions mediated by cytokines. It is proposed that chronic inflammation might damage the micro-vascular system of brain and hamper cerebral blood flow. Scientific evidence suggests that an increase of stress hormone like norepinephrine may activate the inflammatory arm of the immune system and trigger the expression of genes that cause chronic, low-grade inflammation. Thus, studies were conducted to decipher the potentiality of CRP as a marker for inflammation in schizophrenia. This article reviews the findings of CRP in schizophrenia, and the limitations of the previous studies have been discussed. The importance of simultaneous study of CRP modulating cytokines and CRP gene polymorphism in the study of serum or plasma level of CRP has been emphasized.