Antipsychotics' effects on blood levels of cytokines in schizophrenia: a meta-analysis

Development of an anti-inflammatory diet for first-episode psychosis (FEP): a feasibility study protocol

Background

Evidence suggests inflammation plays a role in the pathophysiology of psychosis even in early illness, indicating a potential avenue for anti-inflammatory interventions that simultaneously address high rates of metabolic disease in this population. The aim of this study is to design a novel anti-inflammatory diet intervention (DI) that is feasible to implement in a first-episode psychosis (FEP) population.

Methods

Eligible FEP Participants are aged 15-30. The DI is currently being refined through a multi-phase process that includes the recruitment of focus groups that provide insight into feasibility of measures and nutritional education, as well as the implementation of the DI. The phases in the study are the Development Phase, Formative Phase, and the Feasibility Phase.

Results

The Development phase has resulted in the creation of a flexible DI for FEP based on existing research on nutritional health and informed by providers. This study has just completed the Formative phase, recruiting eligible participants to join focus groups that gleaned information about dietary habits, preferences, and food environments to further refine the DI.

Conclusion

Findings from earlier phases have advised the current Feasibility Phase in which this novel DI is being administered to a small cohort of FEP participants (N = 12) to determine acceptability of the DI from a lived experience perspective. Naturalistic changes in inflammatory biomarkers, metabolic health, and symptoms will also be measured.

The neutrophil-lymphocyte ratio in first-episode medication-naïve patients with schizophrenia: A 12-week longitudinal follow-up study

Inflammation has been related to schizophrenia (SZ). The neutrophil-to-lymphocyte ratio (NLR) is an inexpensive inflammatory marker, however, its potential predictive value in patients with SZ has not been extensively investigated. This study aimed to examine whether NLR could predict the clinical response to antipsychotics in this population. One hundred and ninety-five medication-naïve first-episode schizophrenia (MNFES) patients were recruited and received treatment with risperidone for 12 weeks in the present study. Clinical symptoms were evaluated at week 0 and the end of 12 weeks of treatment using the PANSS scales. Complete blood counts were determined at baseline. We found that baseline NEU counts and NLR were positively associated with improvements in clinical symptoms in patients. In addition, MNFES patients with higher baseline NLR values showed a better treatment response to antipsychotics. Linear regression analysis revealed a predictive role of baseline NLR for the improvements of clinical symptoms in SZ patients. Our findings demonstrate that higher NLR was related to better improvements in symptoms after 12 weeks of treatment with antipsychotics, which renders it a promising biomarker of the response to antipsychotics in clinical practice.

Antipsychotic Use for ICU Delirium and Associated Inflammatory Markers

Purpose: We sought to evaluate critically ill patients with delirium to evaluate inflammatory cytokine production and delirium progression and the role of antipsychotics. Materials and Methods: Adult critically ill patients with confirmed delirium according to a positive CAM-ICU score were included and IL-6 and IL-8 levels were trended for 24 h in this single-center, prospective, observational cohort study. Results: A total of 23 patients were consented and had blood samples drawn for inclusion. There was no difference in IL-6 and IL-8 levels at baseline, 4 to 8 h, and 22 to 28 h after enrollment when comparing patients based on antipsychotic exposure. We identified 2 patient clusters based on age, APACHE III, need for mechanical ventilation, and concomitant infection. In cluster 1, 5 (33.3%) patients received antipsychotics versus 5 (62.5%) patients in cluster 2 (P = .18). Patients in cluster 1 had more co-inflammatory conditions (P < .0001), yet numerically lower baseline IL-6 (P = .18) and IL-8 levels (P = .80) compared to cluster 2. Patients in cluster 1 had a greater median number of delirium-free days compared to cluster 2 (17.0 vs 6.0 days; P = .05). Conclusions: In critically ill patients with delirium, IL-6 and IL-8 levels were variable and antipsychotics were not associated with improvements in delirium or inflammatory markers.

Anti-SFT2D2 autoantibodies alter dendrite spine and cause psychotic behavior in mice

BACKGROUND

Autoimmunity plays an important role in schizophrenia (SCZ). Autoantibodies against SFT2D2 have been reported in patients with SCZ; however, the specific mechanism remains unclear. This study aimed to describe an autoimmune model, namely, mice immunized against SFT2D2-peptides.

METHODS

ApoE-/- and WT mice (C57BL/6) were immunized four times (day 0, day 14, day 21, day 35) with SFT2D2 peptide or KLH via subcutaneous injection. Behavioral tests were conducted after the third immunization, and immunochemistry of brain tissue were performed after the sacrifice of the mice.

RESULTS

Active immunization with KLH-coupled SFT2D2-derived peptides in both WT and ApoE-/- (compromised blood-brain barrier) mice led to high circulating levels of anti-SFT2D2 IgG. While there was no detectable deficit in WT mice, impaired pre-pulse inhibition, motor impairments, and reduced cognition in ApoE-/- mice, without signs of anxiety and depression were observed. In addition, immunohistochemical assays demonstrated that activated microglia and astrocytes were increased but neuronal dendritic spine densities were decreased, accompanied by increased expression of complement molecule C4 across brain regions in ApoE-/- mice.

CONCLUSIONS

In model mice with compromised blood-brain barrier, endogenous anti-SFT2D2 IgG can activate glial cells and modulate synaptic plasticity, and induce a series of psychosis-like changes. These antibodies may reveal valuable therapeutic targets, which may improve the treatment strategies for a subgroup of SCZ patients.

Immune and oxidative stress biomarkers in pediatric psychosis and psychosis-risk: Meta-analyses and systematic review

OBJECTIVE

While genetic and cohort studies suggest immune and reduction/oxidation (redox) alterations occur in psychosis, less is known about potential alterations in children and adolescents.

METHODS

We conducted a systematic review to identify immune and redox biomarker studies in children and adolescents (mean age ≤ 18 years old) across the psychosis spectrum: from psychotic like experiences, which are common in children, to threshold psychotic disorders like schizophrenia. We conducted meta-analyses when at least three studies measured the same biomarker.

RESULTS

The systematic review includes 38 pediatric psychosis studies. The meta-analyses found that youth with threshold psychotic disorders had higher neutrophil/lymphocyte ratio (Hedge's g = 0.40, 95 % CI 0.17 - 0.64), tumor necrosis factor (Hedge's g = 0.38, 95 % CI 0.06 - 0.69), C-reactive protein (Hedge's g = 0.38, 95 % CI 0.05 - 0.70), interleukin-6 (Hedge's g = 0.35; 95 % CI 0.11 - 0.64), and total white blood cell count (Hedge's g = 0.29, 95 % CI 0.12 - 0.46) compared to youth without psychosis. Other immune and oxidative stress meta-analytic findings were very heterogeneous.

CONCLUSION

Results from several studies are consistent with the hypothesis that signals often classified as "proinflammatory" are elevated in threshold pediatric psychotic disorders. Data are less clear for immune markers in subthreshold psychosis and redox markers across the subthreshold and threshold psychosis spectrum. Immune and redox biomarker intervention studies are lacking, and research investigating interventions targeting the immune system in threshold pediatric psychosis is especially warranted.

Vitamin D Deficiency Participates in Depression of Patients with Diabetic Peripheral Neuropathy by Regulating the Expression of Pro-Inflammatory Cytokines

Objective

Vitamin D deficiency is associated with patients with diabetic peripheral neuropathy (DPN), and low levels of vitamin D are common in patients with depression. Depression is common in DPN patients and the definite pathogenesis remains unclear. This study aimed to determine vitamin D deficiency in the onset of depression in DPN and evaluate the effect of vitamin D supplementation on depression.

Methods

A total of 192 patients with DPN were enrolled in this study. Clinical and laboratory information was collected. Chemiluminescent immunoassay was used to measure the level of 25(OH)D. Enzyme-linked immunosorbent assay was employed to measure the concentrations of interleukin (IL)-1β, tumor necrosis factor-α (TNF-α), and IL-17A. Subjects with low 25(OH)D received 5000IU vitamin D daily for 12 weeks. Depression scores and levels of 25(OH)D, IL-1β, TNF-α, and IL-17A were re-evaluated after supplementation.

Results

The incidence of vitamin D deficiency and depression was high in DPN patients. Compared with vitamin D sufficient participants, Hamilton Depression Rating Scale (HAMD) scores and the levels of inflammatory markers IL-1β, TNF-α, and IL-17A were significantly higher in insufficient group (all p<0.05). HAMD score, IL-1β, TNF-α, and IL-17A were negatively correlated with 25(OH)D (all p<0.05). A linear relationship existed among IL-1β, TNF-α, IL-17A, and 25(OH)D (p<0.05). HAMD scores, IL-1β, TNF-α, and IL-17A were all reduced significantly after supplementation of vitamin D (p<0.05). Binary logistic analysis revealed that vitamin D insufficiency was an independent risk factor for depression in patients with DPN. Receiver operating characteristic (ROC) curve analysis showed a high sensitivity (87.20%) of 25(OH)D in discriminating DPN patients with depression.

Conclusion

Vitamin D deficiency participated in occurrence of depression in DPN patients and could be mediated, at least in part, by upregulation of pro-inflammatory cytokines. Vitamin D supplementation may be effective in improving depressive symptoms in DPN patients.

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

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

Inflammatory markers of symptomatic remission at 6 months in patients with first-episode schizophrenia

Neuroinflammation contributes to the pathophysiology of various mental illnesses including schizophrenia. We investigated peripheral inflammatory cytokines as a biomarker for predicting symptomatic remission in patients with first-episode schizophrenia. The study included 224 patients aged 15-60 years who fulfilled the criteria for schizophrenia spectrum disorder with a treatment duration ≤6 months. Serum levels of tumor necrosis factor (TNF) -α, interferon-γ, interleukin (IL)-1α, IL-1β, IL-6, IL-8, IL-10, and IL-12 were measured. Psychotic symptoms, depressive symptoms, and general functioning were assessed using the Positive and Negative Syndrome Scale, Beck Depression Inventory (BDI), Calgary Depression Scale for Schizophrenia, and Personal and Social Performance scale, respectively. Duration of untreated psychosis (DUP) was also recorded. We investigated the factors associated with remission for each sex in logistic regression analysis. In total, 174 patients achieved remission at the 6-month follow-up (females, 83.5%; males, 70.9%). Remission was associated with older age and lower BDI scores in male patients and with lower TNF-α levels and shorter DUP in female patients. Our findings suggest that peripheral inflammatory cytokines may impede early symptomatic remission in female patients with schizophrenia. In addition, depressive symptoms in males and long DUP in females may be poor prognostic factors for early remission in patients with first-episode psychosis.

Anti-Inflammatory Effects of Peripheral Dopamine

Dopamine is synthesized in the nervous system where it acts as a neurotransmitter. Dopamine is also synthesized in a number of peripheral organs as well as in several types of cells and has organ-specific functions and, as demonstrated more recently, is involved in the regulation of the immune response and inflammatory reaction. In particular, the renal dopaminergic system is very important in the regulation of sodium transport and blood pressure and is particularly sensitive to stimuli that cause oxidative stress and inflammation. This review is focused on how dopamine is synthesized in organs and tissues and the mechanisms by which dopamine and its receptors exert their effects on the inflammatory response.

Arterial Stiffness in Patients with Bipolar Disorder

Objective

Bipolar disorder (BD) is an inflammatory and metabolic disease. The disease and the drugs used to treat it may affect cardiovascular disease (CVD) risk. The aim of this study is to investigate arterial stiffness in patients with BD and compare them with healthy controls.

Methods

Thirty-nine patients with BD type I in remission and 39 healthy control subjects were included in the study. Carotid and femoral artery intima-media thickness (IMT) and arterial thickness parameters were measured by Doppler ultrasonography.

Results

The elastic modulus value of the carotid artery was significantly higher in the patients than in the control group (p = 0.015). Although the IMT of both carotid and femoral artery was thicker in patients than in healthy control subjects, this difference was not statistically significant (p = 0.105; p = 0.391). There was a significant positive correlation between chlorpromazine equivalent dose and femoral elastic modulus value (p = 0.021, r = 0.539). There was a positive correlation between lithium equivalent dose and carotid compliance; a significant negative correlation between lithium equivalent dose and carotid elastic modulus was also determined (both p = 0.007, r = 0.466; p = 0.027, r = -0.391, respectively). No predictor was observed between drug dose and arterial stiffness parameters.

Conclusion

Arterial stiffness might be investigated for its potential to reduce CVD risk in patients with BD. Given the established CVD complications in this patient population, further studies are needed to determine whether the results are specific to antipsychotic treatment or BD and to clarify the potential arterial protective effects of mood stabilizers.

Counting the Toll of Inflammation on Schizophrenia-A Potential Role for Toll-like Receptors

Toll-like receptors (TLRs) are a family of pattern recognition receptors (PRRs) that are ubiquitously expressed in the human body. They protect the brain and central nervous system from self and foreign antigens/pathogens. The immune response elicited by these receptors culminates in the release of cytokines, chemokines, and interferons causing an inflammatory response, which can be both beneficial and harmful to neurodevelopment. In addition, the detrimental effects of TLR activation have been implicated in multiple neurodegenerative diseases such as Alzheimer's, multiple sclerosis, etc. Many studies also support the theory that cytokine imbalance may be involved in schizophrenia, and a vast amount of literature showcases the deleterious effects of this imbalance on cognitive performance in the human population. In this review, we examine the current literature on TLRs, their potential role in the pathogenesis of schizophrenia, factors affecting TLR activity that contribute towards the risk of schizophrenia, and lastly, the role of TLRs and their impact on cognitive performance in schizophrenia.

Transcriptional level of inflammation markers associates with short-term brain structural changes in first-episode schizophrenia

BACKGROUND

Inflammation has been implicated in the pathology of schizophrenia and may cause neuronal cell death and dendrite loss. Neuroimaging studies have highlighted longitudinal brain structural changes in patients with schizophrenia, yet it is unclear whether this is related to inflammation. We aim to address this question, by relating brain structural changes with the transcriptional profile of inflammation markers in the early stage of schizophrenia.

METHODS

Thirty-eight patients with first-episode schizophrenia and 51 healthy controls were included. High-resolution T1-weighted magnetic resonance imaging (MRI) and clinical assessments were performed at baseline and 2 ~ 6 months follow-up for all subjects. Changes in the brain structure were analyzed using surface-based morphological analysis and correlated with the expression of immune cells-related gene sets of interest reported by previous reviews. Transcriptional data were retrieved from the Allen Human Brain Atlas. Furthermore, we examined the brain structural changes and peripheral inflammation markers in association with behavioral symptoms and cognitive functioning in patients.

RESULTS

Patients exhibited accelerated cortical thickness decrease in the left frontal cortices, less decrease or an increase in the superior parietal lobule and right lateral occipital lobe, and increased volume in the bilateral pallidum, compared with controls. Changes in cortical thickness correlated with the transcriptional level of monocyte across cortical regions in patients (r = 0.54, p < 0.01), but not in controls (r =  - 0.05, p = 0.76). In addition, cortical thickness change in the left superior parietal lobule positively correlated with changes in digital span-backward test scores in patients.

CONCLUSIONS

Patients with schizophrenia exhibit regional-specific cortical thickness changes in the prefrontal and parietooccipital cortices, which is related to their cognitive impairment. Inflammation may be an important factor contributing to cortical thinning in first-episode schizophrenia. Our findings suggest that the immunity-brain-behavior association may play a crucial role in the pathogenesis of schizophrenia.

Associations between plasma inflammatory markers and psychotic disorder, depressive disorder and generalised anxiety disorder in early adulthood: A nested case-control study

BACKGROUND

Low-grade inflammation may occur in association with several mental disorders of early adulthood, though associations with markers of chronic inflammation such as soluble urokinase plasminogen activator receptor (suPAR) are less well-established. We aimed to examine associations between acute and chronic inflammatory markers and mental disorders, as well as psychiatric co-morbidity, in young adults aged 24 years in the Avon Longitudinal Study of Parents and Children.

METHODS

Included were 781 participants (of 4019 who attended at age 24 years) who completed psychiatric assessments and provided plasma samples. Of these, 377 met criteria for psychotic disorder, depressive disorder or generalised anxiety disorder and 404 did not. Plasma concentrations of IFN-γ, IL-6, IL-8, IL-10, TNF-α, CRP, sVCAM1, sICAM1, suPAR and alpha-2-macroglobulin were measured using immunoassays. Logistic regression compared standardised inflammatory marker levels in cases and controls. Negative binomial regression evaluated associations between inflammatory markers and co-morbidity (number of mental disorders). Models were adjusted for sex, body mass index, cigarette smoking, cannabis use and employment status, then additionally for childhood trauma.

RESULTS

For psychotic disorder, there was evidence for associations with IL-6 (odds ratio[OR] 1.68, 95 %CI 1.20-2.34) and suPAR (OR 1.74, 95 %CI 1.17-2.58). There was weaker evidence for an association between suPAR and depressive disorder (OR 1.31, 95 %CI 1.05-1.62). There was little evidence for associations between inflammatory markers and generalised anxiety disorder. There was weak evidence for an association between suPAR and co-morbidity (β 0.10, 95 %CI 0.01-0.19). There was little evidence for additional confounding by childhood trauma.

CONCLUSIONS

There was evidence that 24-year-olds with psychotic disorder had raised plasma IL-6 and suPAR concentrations compared to controls. These findings have implications regarding the role of inflammation in mental disorders in early adulthood.

The association between peripheral inflammation, brain glutamate and antipsychotic response in Schizophrenia: Data from the STRATA collaboration

Glutamate and increased inflammation have been separately implicated in the pathophysiology of schizophrenia and the extent of clinical response to antipsychotic treatment. Despite the mechanistic links between pro-inflammatory and glutamatergic pathways, the relationships between peripheral inflammatory markers and brain glutamate in schizophrenia have not yet been investigated. In this study, we tested the hypothesis that peripheral levels of pro-inflammatory cytokines would be positively associated with brain glutamate levels in schizophrenia. Secondary analyses determined whether this relationship differed according to antipsychotic treatment response. The sample consisted of 79 patients with schizophrenia, of whom 40 were rated as antipsychotic responders and 39 as antipsychotic non-responders. Brain glutamate levels were assessed in the anterior cingulate cortex (ACC) and caudate using proton magnetic resonance spectroscopy (1H-MRS) and blood samples were collected for cytokine assay on the same study visit (IL-6, IL-8, IL-10, TNF- α and IFN-γ). Across the whole patient sample, there was a positive relationship between interferon-gamma (IFN-γ) and caudate glutamate levels (r = 0.31, p = 0.02). In the antipsychotic non-responsive group only, there was a positive relationship between interleukin-8 (IL-8) and caudate glutamate (r = 0.46, p = 0.01). These findings provide evidence to link specific peripheral inflammatory markers and caudate glutamate in schizophrenia and may suggest that this relationship is most marked in patients who show a poor response to antipsychotic treatment.

Effects of a six-month yoga intervention on the immune-inflammatory pathway in antipsychotic-stabilized schizophrenia patients: A randomized controlled trial

BACKGROUND

Schizophrenia is a complex neuropsychiatric disorder for which several etiopathological theories have been proposed, one of the prominent ones being immune dysfunction. Recent studies on yoga as an add-on therapy have shown improvement in negative symptoms, cognition, and quality of life in schizophrenia patients. However, the biological mechanism/s of action of yoga in schizophrenia are not clear. The current study was aimed at exploring the effects of long-term (6 months) add-on yoga therapy on the immune inflammatory pathway in schizophrenia patients.

METHODS

Sixty schizophrenia patients were randomized to add-on yoga therapy (YT=30) and treatment-as-usual (TAU=30) groups of which 21 patients in YT and 20 in TAU group completed the study. Blood samples and clinical assessments were obtained at baseline and at the end of 6 months. The plasma levels of nine cytokines (IL-2, IL-4, IL-5, IL-10, IL-12(p70), IL-13, GM-CSF, IFN-γ, and TNF-α) were quantified using multiplex suspension array. The clinical assessments included SAPS, SANS, BPRS, PSS, CGI, SOFS and WHOQUOL-BREF.

RESULTS

Patients in the yoga group showed significant reductions in plasma TNF-α (Z = 2.99, p = 0.003) and IL-5 levels (Z = 2.20, p = 0.03) and greater clinical improvements in SAPS, SANS, PSS, and SOFS scores as compared to TAU group. Further, plasma TNF-α levels exhibited a positive correlation with negative symptoms (r_s =0.45, p = 0.02) and socio-occupational functioning (r_s =0.61, p = 0.002) in the YT group.

CONCLUSIONS

The findings of the study suggest that improvements in schizophrenia psychopathology with yoga interventions are associated with immuno-modulatory effects.

Inflammatory cytokines and white matter microstructure in the acute phase of first-episode psychosis: A longitudinal study

OBJECTIVES

Schizophrenia-related psychosis is associated with abnormalities in white matter (WM) microstructure and structural brain dysconnectivity. However, the pathological process underlying such changes is unknown. We sought to investigate the potential association between peripheral cytokine levels and WM microstructure during the acute phase of first-episode psychosis (FEP) in a cohort of drug-naïve patients.

METHODS

Twenty-five non-affective FEP patients and 69 healthy controls underwent MRI scanning and blood collection at study entry. After achieving clinical remission, 21 FEP were reassessed; 38 age and biological sex-matched controls also had a second assessment. We measured fractional anisotropy (FA) of selected WM regions-of-interest (ROIs) and plasma levels of four cytokines (IL-6, IL-10, IFN-γ, and TNF-α).

RESULTS

At baseline (acute psychosis), the FEP group showed reduced FA relative to controls in half the examined ROIs. Within the FEP group, IL-6 levels were negatively correlated with FA values. Longitudinally, patients showed increments of FA in several ROIs affected at baseline, and such changes were associated with reductions in IL-6 levels.

CONCLUSIONS

A state-dependent process involving an interplay between a pro-inflammatory cytokine and brain WM might be associated with the clinical manifestation of FEP. This association suggests a deleterious effect of IL-6 on WM tracts during the acute phase of psychosis.

Alteration patterns of peripheral concentrations of cytokines and associated inflammatory proteins in acute and chronic stages of schizophrenia: a systematic review and network meta-analysis

BACKGROUND

Immune system dysfunction is considered to play an aetiological role in schizophrenia spectrum disorders, with substantial alterations in the concentrations of specific peripheral inflammatory proteins, such as cytokines. However, there are inconsistencies in the literature over which inflammatory proteins are altered throughout the course of illness. Through conducting a systematic review and network meta-analysis, this study aimed to investigate the patterns of alteration that peripheral inflammatory proteins undergo in both acute and chronic stages of schizophrenia spectrum disorders, relative to a healthy control population.

METHODS

In this systematic review and meta-analysis, we searched PubMed, PsycINFO, EMBASE, CINAHL, and the Cochrane Central Register of Controlled Trials from inception to March 31, 2022, for published studies reporting peripheral inflammatory protein concentrations in cases of people with schizophrenia-spectrum disorders and healthy controls. Inclusion criteria were: (1) observational or experimental design; (2) a population consisting of adults diagnosed with schizophrenia-spectrum disorders with a specified indicator of acute or chronic stage of illness; (3) a comparable healthy control population without mental illness; (4) a study outcome measuring the peripheral protein concentration of a cytokine, associated inflammatory marker, or C-reactive protein. We excluded studies that did not measure cytokine proteins or associated biomarkers in blood. Mean and SDs of inflammatory marker concentrations were extracted directly from full-text publshed articles; articles that did not report data as results or supplementary results were excluded (ie, authors were not contacted) and grey literature and unpublished studies were not sought. Pairwise and network meta-analyses were done to measure the standardised mean difference in peripheral protein concentrations between three groups: individuals with acute schizophrenia-spectrum disorder, individuals with chronic schizophrenia-spectrum disorder, and healthy controls. This protocol was registered on PROSPERO, CRD42022320305.

FINDINGS

Of 13 617 records identified in the database searches, 4492 duplicates were removed, 9125 were screened for eligibility, 8560 were excluded after title and abstract screening, and three were excluded due to limited access to the full-text article. 324 full-text articles were then excluded due to inappropriate outcomes, mixed or undefined schizophrenia cohorts, or duplicate study populations, five were removed due to concerns over data integrity, and 215 studies were included in the meta-analysis. 24 921 participants were included, with 13 952 adult cases of schizophrenia-spectrum disorder and 10 969 adult healthy controls (descriptive data for the entire cohort were not available for age, numbers of males and females, and ethnicity). Concentration of interleukin (IL)-1β, IL-1 receptor antagonist (IL-1RA), soluble interleukin-2 receptor (sIL-2R), IL-6, IL-8, IL-10, tumour necrosis factor (TNF)-α, and C-reactive protein were consistently elevated in both individuals with acute schizophrenia-spectrum disorder and chronic schizophrenia-spectrum disorder, relative to healthy controls. IL-2 and interferon (IFN)-γ were significantly elevated in acute schizophrenia-spectrum disorder, while IL-4, IL-12, and IFN-γ were significantly decreased in chronic schizophrenia-spectrum disorder. Sensitivity and meta-regression analyses revealed that study quality and a majority of the evaluated methodological, demographic, and diagnostic factors had no significant impact on the observed results for most of the inflammatory markers. Specific exceptions to this included: methodological factors of assay source (for IL-2 and IL-8), assay validity (for IL-1β), and study quality (for transforming growth factor-β1); demographic factors of age (for IFN-γ, IL-4, and IL-12), sex (for IFN-γ and IL-12), smoking (for IL-4), and BMI (for IL-4); and diagnostic factors including diagnostic composition of schizophrenia-spectrum cohort (for IL-1β IL-2, IL-6, and TNF-α), antipsychotic-free cases (for IL-4 and IL-1RA), illness duration (for IL-4), symptom severity (for IL-4), and subgroup composition (for IL-4).

INTERPRETATION

Results suggest that people with schizophrenia-spectrum disorders have a baseline level of inflammatory protein alteration throughout the illness, as reflected by consistently elevated pro-inflammatory proteins, hypothesised here as trait markers (eg, IL-6), while those with acute psychotic illness might have superimposed immune activity with increased concentrations of hypothesised state markers (eg, IFN-γ). Further research is required to determine whether these peripheral alterations are reflected within the central nervous system. This research facilitates an entry point in understanding how clinically relevant inflammatory biomarkers might one day be useful to the diagnosis and prognostication of schizophrenia-spectrum disorders.

FUNDING

None.

Anti-inflammatory effects of 2nd generation antipsychotics in patients with schizophrenia: A systematic review and meta-analysis

BACKGROUND

Schizophrenia is a major psychiatric disorder with unknown aetiology. Recent evidence suggests a potential role for cytokines in its pathophysiology and that antipsychotic medication may alter this. While the aetiology of schizophrenia remains only partly understood, an altered immune function representing an important avenue of further discovery. In this systematic review and meta-analysis we focus on the specific effects of second generation antipsychotics risperidone and clozapine on inflammatory cytokines.

METHODS

A defined systematic search of PubMed and Web of Science databases was performed to identify relevant studies published between Jan 1900 and May 2022. After screening of 2969 papers, 43 studies (27 single-arm and 8 dual-arm) were included that consisted of a total of 1421 patients with schizophrenia in the systematic review. From these, twenty studies (4 dual-arm; 678 patients) had data available on which a meta-analysis could be carried out.

RESULTS

Our meta-analysis showed a significant reduction of pro-inflammatory cytokines post-risperidone treatment in the absence of a similar association with clozapine. Subgroup analyses (First episode v chronic) demonstrated that duration of illness influenced the extent of cytokine alteration; risperidone treatment produced significant cytokine changes (lowered IL-6 and TNF-α) in chronic patients but not in first-episode psychosis (FEP) patients.

CONCLUSION

Varying treatment effects on cytokines can be observed by the use of different antipsychotic drugs. The cytokine alterations post-treatment are influenced by the specific antipsychotic drugs and patient status. This may explain disease progression in certain patient groups and influence therapeutic choices in the future.

The relationship between inflammatory biomarkers and cognitive dysfunction in patients with schizophrenia: A systematic review and meta-analysis

BACKGROUND

Schizophrenia is a complex psychiatric disorder that includes positive and negative symptoms but also debilitating cognitive deficits. Current pharmacological interventions do not target these deficits. Recent evidence suggests a connection between some inflammatory markers (including C-reactive protein) and cognitive impairment, but did not address other inflammatory markers. In the current study, we try to fill the gap by focusing on the association of Interleukin-6 (IL-6), IL-1β, Tumor Necrosis Factor-α and CRP with cognitive dysfunction.

METHODS

PUBMED and Web of Science databases were searched for all studies published until July 2022. A total of 25 studies were included in an analysis of the association between cognitive performance and variation in IL-6, IL-1β, TNF-α and CRP.

RESULTS

A total of 2398 patients were included in this study. Meta-analyses results showed a significant inverse relationship between performance in five cognitive domains (attention-processing speed, executive function, working memory, verbal and visual learning and memory) and systemic IL-6, IL-1β, TNF-α and CRP plasma levels in patients with schizophrenia. The meta-analyses results showed a significant decline in the cognitive performances with the evaluated inflammatory markers with effect sizes ranging from -0.136 to -0.181 for IL-6, -0.188 to -0.38 for TNF-α -0.372 to -0.476 for IL-1β and - 0.168 to -0.311 for CRP.

CONCLUSION

Findings from the current study shows that cognitive deficits are reflective of elevated proinflammatory biomarkers (IL-6, IL-1β, TNF-α and CRP) levels. The results obtained indicate relatedness between inflammation and cognitive decline in patients with schizophrenia. Understanding the underlying pathways between them could have a significant impact on the disease progression and quality of life in schizophrenia patients.

Neutrophil gelatinase-associated lipocalin (NGAL) and tumor necrosis factor-α (TNF-α) levels in patients with schizophrenia

RATIONALE

Although the immune system is thought to contribute to the etiology of schizophrenia, the mechanism has not been elucidated. Clarifying the relationship between them is important in terms of diagnosis, treatment, and prevention approaches.

OBJECTIVE

In this study, it is aimed to determine whether there is any difference in serum levels of neutrophil gelatinase-associated lipocalin (NGAL) and tumor necrosis factor-alpha (TNF-α) in the group of patients with schizophrenia and healthy volunteers, whether these values are changed by medical treatment, whether there is any relation between these values and the severity of the symptoms of patients with schizophrenia, and whether NGAL can be used as a biomarker in the diagnosis and the follow-up of the schizophrenia.

METHODS

A total of 64 patients who were hospitalized in the Psychiatry Clinic of Ankara City Hospital and diagnosed with schizophrenia and 55 healthy volunteers were included in the study. A sociodemographic information form was given to all participants and TNF-α and NGAL values were measured. Positive and Negative Symptoms Rating Scale (PANSS) were applied to the schizophrenia group on admission and follow-up. TNF-α and NGAL levels were re-measured in the 4th week after the start of antipsychotic treatment.

RESULTS

As a result of the present study, it was found that NGAL levels decreased significantly after antipsychotic treatment of schizophrenia patients hospitalized with exacerbation. There was no significant correlation between NGAL and TNF-α levels among schizophrenia and the control group.

CONCLUSION

In psychiatric diseases, especially schizophrenia, there may be differences in immune and inflammatory markers compared to the healthy population. After treatment, the NGAL levels of the patients at follow-up were reduced compared to the levels at admission. It can be thought that NGAL may be related to psychopathology in schizophrenia and antipsychotic treatment. This is the first follow-up study for NGAL levels in schizophrenia.

Longitudinal study of inflammation and relapse in schizophrenia

INTRODUCTION

The clinical course of schizophrenia is often characterized by recurrent relapses. Blood inflammatory markers are altered in acute psychosis, and may be state markers for illness relapse in schizophrenia. Few studies have investigated longitudinal, intra-individual changes in inflammatory markers as a predictor of relapse. In the present study, we explored this association in a relapse prevention trial in patients with schizophrenia.

METHODS

We analyzed blood inflammatory markers in 200 subjects, with a mean 11 samples per subject, during the 30 month Preventing Relapse in schizophrenia: Oral Antipsychotics Compared to Injectable: eValuating Efficacy (PROACTIVE) trial. Associations between longitudinal changes in inflammatory markers and relapse were analyzed using a within-subjects design.

RESULTS

70 (35 %) of subjects relapsed during the study period. There were no significant differences in mean inflammatory marker levels based on relapse status (yes/no). Baseline levels of inflammatory markers did not predict incident relapse. Among subjects who relapsed, there was a significant decrease in mean blood IL-6 (n = 38, p = 0.019) and IFN-γ (n = 44, p = 0.012) levels from the visit before the relapse to the visit after relapse.

CONCLUSION

Although there was some evidence for inflammation as a potential state marker for acute psychosis, we did not find significant evidence for its utility as a relapse-predictive marker.

Anti-inflammatory properties of commonly used psychiatric drugs

Mental health and neurodevelopmental disorders are extremely common across the lifespan and are characterized by a complicated range of symptoms that affect wellbeing. There are relatively few drugs available that target disease mechanisms for any of these disorders. Instead, therapeutics are focused on symptoms and syndromes, largely driven by neurotransmitter hypotheses, such as serotonin or dopamine hypotheses of depression. Emerging evidence suggests that maternal inflammation during pregnancy plays a key role in neurodevelopmental disorders, and inflammation can influence mental health expression across the lifespan. It is now recognized that commonly used psychiatric drugs (anti-depressants, anti-psychotics, and mood stabilizers) have anti-inflammatory properties. In this review, we bring together the human evidence regarding the anti-inflammatory mechanisms for these main classes of psychiatric drugs across a broad range of mental health disorders. All three classes of drugs showed evidence of decreasing levels of pro-inflammatory cytokines, particularly IL-6 and TNF-α, while increasing the levels of the anti-inflammatory cytokine, IL-10. Some studies also showed evidence of reduced inflammatory signaling via nuclear factor- (NF-)κB and signal transducer and activator of transcription (STAT) pathways. As researchers, clinicians, and patients become increasingly aware of the role of inflammation in brain health, it is reassuring that these psychiatric drugs may also abrogate this inflammation, in addition to their effects on neurotransmission. Further studies are required to determine whether inflammation is a driver of disease pathogenesis, and therefore should be a therapeutic target in future clinical trials.

C-Reactive Protein (CRP): A Potent Inflammation Biomarker in Psychiatric Disorders

An increasing number of studies have investigated the role of inflammation in psychiatric disorders, by demonstrating how an altered/dysfunctional immunological and inflammatory system may underpin a psychiatric condition. Particularly, several studies specifically investigated the role of a neuroinflammatory biomarker, named C-reactive protein (CRP), in psychiatric disorders. Overall, even though scientific literature so far published still does not appear definitive, CRP is more likely reported to be elevated in several psychiatric disorders, including schizophrenia, mood disorders, anxiety disorders and post-traumatic stress disorder. Moreover, a low-grade inflammation (CRP >3 mg/L) has been more likely observed in a subgroup of patients affected with a more severe psychopathological symptomatology, more treatment resistance and worst clinical mental illness course, strengthening the hypothesis of the need for a different clinical and prognostic characterization based on this concomitant neuroinflammatory predisposition. However, even though further research studies are needed to confirm this preliminary evidence, CRP may represent a potential clinical routine biomarker which could be integrated in the clinical routine practice to better characterize clinical picture and course as well as address clinicians towards a personalized treatment.

Systematic Review and Meta-Analysis of Damage Associated Molecular Patterns HMGB1 and S100B in Schizophrenia

OBJECTIVE

Immune system dysregulation is hypothesised to be central to the aetiopathogenesis of schizophrenia; however, the role of sterile inflammation remains unclear. Damage associated molecular patterns are key initiators of sterile inflammation and are detectable in peripheral blood.

METHODS

A defined systematic search of the Web of Science, PubMed, and Scopus was performed to identify adult case-control studies published between January 1990 and June 2022. Three studies consisting of 242 cases and 83 controls met inclusion for the systematic review and meta-analysis of HMGB1 while twenty-eight studies consisting of 1,544 cases and 1,248 healthy controls were included for S100B.

RESULTS

A significant standardised mean difference in peripheral S100B and HMGB1 concentrations was detected between cases and controls. S100B subgroup analysis determined the largest significant effect size for unmedicated individuals diagnosed with schizophrenia.

CONCLUSION

This study provides evidence that peripheral S100B and HMGB1 concentrations are elevated in individuals diagnosed with schizophrenia when compared with healthy controls. These results should be interpreted with caution as significant heterogeneity was present during meta-analysis of S100B in the entire sample and in sub-group analysis. The persistence of significant heterogeneity throughout subgroup analysis indicates that the current diagnostic groupings may be a barrier to understanding human behaviours and emotions.

Composite immune marker scores associated with severe mental disorders and illness course

Background

Low-grade inflammation has been implicated in the pathophysiology of severe mental disorders (SMDs) and a link between immune activation and clinical characteristics is suggested. However, few studies have investigated how patterns across immune markers are related to diagnosis and illness course.

Methods

A total of 948 participants with a diagnosis of schizophrenia (SCZ, N = 602) or bipolar (BD, N = 346) spectrum disorder, and 814 healthy controls (HC) were included. Twenty-five immune markers comprising cell adhesion molecules (CAMs), interleukin (IL)-18-system factors, defensins, chemokines and other markers, related to neuroinflammation, blood-brain barrier (BBB) function, inflammasome activation and immune cell orchestration were analyzed. Eight immune principal component (PC) scores were constructed by PC Analysis (PCA) and applied in general linear models with diagnosis and illness course characteristics.

Results

Three PC scores were significantly associated with a SCZ and/or BD diagnosis (HC reference), with largest, however small, effect sizes of scores based on CAMs, BBB markers and defensins (p < 0.001, partial η2 = 0.02-0.03). Number of psychotic episodes per year in SCZ was associated with a PC score based on IL-18 system markers and the potential neuroprotective cytokine A proliferation-inducing ligand (p = 0.006, partial η2 = 0.071).

Conclusion

Analyses of composite immune markers scores identified specific patterns suggesting CAMs-mediated BBB dysregulation pathways associated with SMDs and interrelated pro-inflammatory and neuronal integrity processes associated with severity of illness course. This suggests a complex pattern of immune pathways involved in SMDs and SCZ illness course.

Neutrophil-lymphocyte ratios as inflammatory biomarkers in psychiatric patients

PURPOSE

There is a growing amount of evidence to suggest that inflammation may have a role in the onset and prognosis of psychiatric disorders. We reviewed the literature of studies investigating neutrophil-lymphocyte ratios (NLR), a biomarker of inflammation, in both adult and youth psychiatric populations. The limitations of NLR, in addition to the potential mechanisms underlying its relationship with psychiatric disorders, are also discussed.

RECENT FINDINGS

Unlike in the general population, NLR is elevated in a proportion of adult patients with schizophrenia, major depressive disorder and bipolar disorder, though associations with symptom severity and other clinical parameters are less clear. When compared to baseline, reductions in NLR are sometimes reported after treatment and remission. Results in youth populations largely resemble findings obtained from adult samples, even though youth studies are far fewer in number.

SUMMARY

The consistent findings of elevated NLR across the reviewed psychiatric disorders suggest that abnormal NLR is not specific to any one disorder but may reflect a pathological brain process that leads to brain dysfunction. These findings support hypotheses of neuroinflammation being important to the etiology of psychiatric disorders. More research is needed to further elucidate the relationship between specific diagnostic and behavioural constructs and NLR. Future work is also needed to determine the specific neuroinflammatory mechanisms that give rise to specific disorders.

Quetiapine Ameliorates MIA-Induced Impairment of Sensorimotor Gating: Focus on Neuron-Microglia Communication and the Inflammatory Response in the Frontal Cortex of Adult Offspring of Wistar Rats

The maternal immune activation produced by the systemic administration of lipopolysaccharide (LPS) in rats provides valuable insights into the basis of behavioural schizophrenia-like disturbances and biochemical changes in the brains of the offspring, such as microglial activation. Regarding therapy, antipsychotics continually constitute the cornerstone of schizophrenia treatment. To their various efficacy and side effects, as well as not fully recognised mechanisms of action, further characteristics have been suggested, including an anti-inflammatory action via the impact on neuron–microglia axes responsible for inhibition of microglial activation. Therefore, in the present study, we sought to determine whether chronic treatment with chlorpromazine, quetiapine or aripiprazole could influence schizophrenia-like behavioural disturbances at the level of sensorimotor gating in male offspring prenatally exposed to LPS. Simultaneously, we wanted to explore if the chosen antipsychotics display a positive impact on the neuroimmunological parameters in the brains of these adult animals with a special focus on the ligand-receptor axes controlling neuron–microglia communication as well as pro- and anti-inflammatory factors related to the microglial activity. The results of our research revealed the beneficial effect of quetiapine on deficits in sensorimotor gating observed in prenatally LPS-exposed offspring. In terms of axes controlling neuron–microglia communication and markers of microglial reactivity, we observed a subtle impact of quetiapine on hippocampal Cx3cl1 and Cx3cr1 levels, as well as cortical Cd68 expression. Hence, further research is required to fully define and explain the involvement of quetiapine and other antipsychotics in Cx3cl1-Cx3cr1 and/or Cd200-Cd200r axes modulation and inflammatory processes in the LPS-based model of schizophrenia-like disturbances.

Retinal layers and associated clinical factors in schizophrenia spectrum disorders: a systematic review and meta-analysis

INTRODUCTION

The retina shares structural and functional similarities with the brain. Furthermore, structural changes in the retina have been observed in patients with schizophrenia spectrum disorders (SSDs). This systematic review and meta-analysis investigated retinal abnormalities and their association with clinical factors for SSD.

METHODS

Studies related to retinal layers in SSD patients were retrieved from PubMed, Scopus, Web of Science, Cochrane Controlled Register of Trials, International Clinical Trials Registry Platform, and PSYNDEX databases from inception to March 31, 2021. We screened and assessed the eligibility of the identified studies. EZR ver.1.54 and the metafor package in R were used for the meta-analysis and a random-effects or fixed-effects model was used to report standardized mean differences (SMDs).

RESULTS

Twenty-three studies (2079 eyes of patients and 1571 eyes of controls) were included in the systematic review and meta-analysis. The average peripapillary retinal nerve fiber layer (pRNFL) thickness, average macular thickness (MT), and macular ganglion cell layer-inner plexiform layer (GCL-IPL) thickness were significantly lower in patients than in controls (n = 14, 6, and 3, respectively; SMD = -0.33, -0.49, and -0.43, respectively). Patients also had significantly reduced macular volume (MV) compared to controls (n = 7; SMD = -0.53). The optic cup volume (OCV) was significantly larger in patients than in controls (n = 3; SMD = 0.28). The meta-regression analysis indicated an association between several clinical factors, such as duration of illness and the effect size of the pRNFL, macular GCL-IPL, MT, and MV.

CONCLUSION

Thinning of the pRNFL, macular GCL-IPL, MT, and MV and enlargement of the OCV in SSD were observed. Retinal abnormalities may be applicable as state/trait markers in SSDs. The accumulated evidence was mainly cross-sectional and requires verification by longitudinal studies to characterize the relationship between OCT findings and clinical factors.

Effects of Dexamethasone and Pentoxifylline on Mania-like and Depression-like Behaviors in Rats

Several studies support the notion that inflammation plays a role in the pathophysiology and treatment approaches of psychiatric illnesses, particularly mood disorders. Congruently, classic anti-inflammatory drugs were found efficacious in randomized clinical trials of patients with mood disorders. Moreover, accumulating data indicate that psychotropic drugs exhibit some anti-inflammatory effects. This study was undertaken to examine the efficacy of dexamethasone (a potent corticosteroid) and pentoxifylline (a methylxanthine drug with proven anti-tumor necrosis factor-α inhibitory activity) in behavioral models in rats, which were treated intraperitoneally with either dexamethasone or pentoxifylline for two weeks and then subjected to a battery of behavioral tests. Treatment with pentoxifylline, but not dexamethasone, was associated with antidepressant-like and anti-manic-like effects. The beneficial behavioral effects of pentoxifylline were accompanied by a prominent reduction in pro-inflammatory mediator levels in the brain. For the first time, the current work proves the efficacy of pentoxifylline against both mania-like and depressive-like behaviors. These results suggest that pentoxifylline may be a promising therapeutic intervention for patients with mood disorders. Taking into account the excellent tolerability profile of pentoxifylline in humans, it is warranted to conduct randomized clinical trials to investigate its therapeutic efficacy in patients with psychiatric disorders.

Linking Inflammation, Aberrant Glutamate-Dopamine Interaction, and Post-synaptic Changes: Translational Relevance for Schizophrenia and Antipsychotic Treatment: a Systematic Review

Evidence from clinical, preclinical, and post-mortem studies supports the inflammatory/immune hypothesis of schizophrenia pathogenesis. Less evident is the link between the inflammatory background and two well-recognized functional and structural findings of schizophrenia pathophysiology: the dopamine-glutamate aberrant interaction and the alteration of dendritic spines architecture, both believed to be the “quantal” elements of cortical-subcortical dysfunctional network. In this systematic review, we tried to capture the major findings linking inflammation, aberrant glutamate-dopamine interaction, and post-synaptic changes under a direct and inverse translational perspective, a paramount picture that at present is lacking. The inflammatory effects on dopaminergic function appear to be bidirectional: the inflammation influences dopamine release, and dopamine acts as a regulator of discrete inflammatory processes involved in schizophrenia such as dysregulated interleukin and kynurenine pathways. Furthermore, the link between inflammation and glutamate is strongly supported by clinical studies aimed at exploring overactive microglia in schizophrenia patients and maternal immune activation models, indicating impaired glutamate regulation and reduced N-methyl-D-aspartate receptor (NMDAR) function. In addition, an inflammatory/immune-induced alteration of post-synaptic density scaffold proteins, crucial for downstream NMDAR signaling and synaptic efficacy, has been demonstrated. According to these findings, a significant increase in plasma inflammatory markers has been found in schizophrenia patients compared to healthy controls, associated with reduced cortical integrity and functional connectivity, relevant to the cognitive deficit of schizophrenia. Finally, the link between altered inflammatory/immune responses raises relevant questions regarding potential new therapeutic strategies specifically for those forms of schizophrenia that are resistant to canonical antipsychotics or unresponsive to clozapine.

Association between psychiatric hospitalizations of patients with schizophrenia and polygenic risk scores based on genes with altered expression by antipsychotics

OBJECTIVE

To test whether a schizophrenia polygenic risk score (PRS) based on the subset of polymorphisms that affect brain expression of genes with altered expression by antipsychotics (exprAP PRS) is associated with psychiatric readmission of patients with schizophrenia.

METHODS

The study involved 427 patients with schizophrenia. Genes with altered expression by antipsychotics were extracted from the Comparative Toxigenomics Database. ExprAP PRS was estimated using the clumping and thresholding (p < 0.05) method. Two additional PRS were tested based on subsets of exprAP polymorphisms whose schizophrenia risk allele has the same (unrestored PRS) or opposite (restored PRS) direction of effect on gene expression than antipsychotics. A general SCZ PRS was tested for comparison. Logistic and ordinal regression were used to test for association of each PRS with ever readmission and admission history, an outcome based on length and number of admissions, respectively. Webgestalt was used for Gene Ontology enrichment analysis.

RESULTS

ExprAP PRS was associated with ever readmission (OR = 1.48, 95%CI:1.10-1.97) and admission history (OR = 1.30, 95%CI 1.07-1.57). SCZ PRS (OR = 1.22, 95%CI: 1.01-1.48) and unrestored PRS (OR = 1.26, 95%CI 1.04-1.53) were only associated with admission history. Genes at exprAP PRS were enriched in regulation of cytokine production.

CONCLUSION

Our findings suggest that PRS based on genes with altered expression by antipsychotics may be better predictors of readmission than SCZ PRS, warranting further investigation in larger cohorts of patients. The action of antipsychotics may be related to brain gene expression, mainly in genes involved in immunity.

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.

Association between Peripheral Inflammatory Cytokines and Cognitive Function in Patients with First-Episode Schizophrenia

In this study, we investigated the impact of inflammatory cytokines on the cognitive performance of patients with schizophrenia. The included patients met the criteria for schizophrenia spectrum disorder and were aged between 15 and 40 years, with a duration of illness ≤1 year. Plasma tumor necrosis factor (TNF)-α; interferon-γ; and interleukin (IL)-1β, IL-6, IL-8, IL-10, and IL-12 levels were measured. A computerized neurocognitive battery, measures for social cognitive function, and clinical measures were administered. A total of 174 patients with first-episode psychosis were enrolled. The TNF-α level was negatively correlated with scores on the digit span, verbal learning, and Wisconsin card sorting tests, and the number of correct responses on the continuous performance test (CR-CPT), whereas a positive correlation was detected with the trail making test (TMT)-B time. The interferon-γ level was negatively correlated with performance on the false belief and visual learning tests. The IL-1β level was positively correlated with the TMT-A time and CPT reaction time, whereas it was negatively correlated with the CR-CPT and performance on the visual learning and social cognitive tests. The IL-12 level was negatively correlated with the CR-CPT and false belief test. Our results suggest that proinflammatory cytokines are associated with cognitive impairment in patients with schizophrenia.

Plasma complement component 4 alterations in patients with schizophrenia before and after antipsychotic treatment

This study was performed to investigate the plasma C4 level and the influence of antipsychotic medication in schizophrenic patients. Thirty-six schizophrenic patients were followed-up for a mean of four weeks. The plasma level of C4 in schizophrenia was significantly higher than that in healthy controls at baseline, and was significantly decreased after antipsychotic treatment. CRP at both baseline and follow-up in patients were comparable to that in healthy controls. Our findings indicate that the plasma level of C4 is increased in schizophrenia patients at the acute stage of illness and can be decreased by antipsychotic medication.

Immune System Abnormalities in Schizophrenia: An Integrative View and Translational Perspectives

The immune system is generally known to be the primary defense mechanism against pathogens. Any pathological conditions are reflected in anomalies in the immune system parameters. Increasing evidence suggests the involvement of immune dysregulation and neuroinflammation in the pathogenesis of schizophrenia. In this systematic review, we summarized the available evidence of abnormalities in the immune system in schizophrenia. We analyzed impairments in all immune system components and assessed the level of bias in the available evidence. It has been shown that schizophrenia is associated with abnormalities in all immune system components: from innate to adaptive immunity and from humoral to cellular immunity. Abnormalities in the immune organs have also been observed in schizophrenia. Evidence of increased C-reactive protein, dysregulation of cytokines and chemokines, elevated levels of neutrophils and autoantibodies, and microbiota dysregulation in schizophrenia have the lowest risk of bias. Peripheral immune abnormalities contribute to neuroinflammation, which is associated with cognitive and neuroanatomical alterations and contributes to the pathogenesis of schizophrenia. However, signs of severe inflammation are observed in only about 1/3 of patients with schizophrenia. Immunological parameters may help identify subgroups of individuals with signs of inflammation who well respond to anti-inflammatory therapy. Our integrative approach also identified gaps in knowledge about immune abnormalities in schizophrenia, and new horizons for the research are proposed.

Low-Dose Aspirin Augments the Anti-Inflammatory Effects of Low-Dose Lithium in Lipopolysaccharide-Treated Rats

Mounting evidence suggests that immune-system dysfunction and inflammation play a role in the pathophysiology and treatment of mood-disorders in general and of bipolar disorder in particular. The current study examined the effects of chronic low-dose aspirin and low-dose lithium (Li) treatment on plasma and brain interleukin-6 and tumor necrosis factor-α production in lipopolysaccharide (LPS)-treated rats. Rats were fed regular or Li-containing food (0.1%) for six weeks. Low-dose aspirin (1 mg/kg) was administered alone or together with Li. On days 21 and 42 rats were injected with 1 mg/kg LPS or saline. Two h later body temperature was measured and rats were sacrificed. Blood samples, the frontal-cortex, hippocampus, and the hypothalamus were extracted. To assess the therapeutic potential of the combined treatment, rats were administered the same Li + aspirin protocol without LPS. We found that the chronic combined treatment attenuated LPS-induced hypothermia and significantly reduced plasma and brain cytokine level elevation, implicating the potential neuroinflammatory diminution purportedly present among the mentally ill. The combined treatment also significantly decreased immobility time and increased struggling time in the forced swim test, suggestive of an antidepressant-like effect. This preclinical evidence provides a potential approach for treating inflammation-related mental illness.

Association between C-reactive protein levels and antipsychotic treatment during 12 months follow-up period after acute psychosis

BACKGROUND

A potential role of inflammatory pathways in the pathology of schizophrenia has been suggested for at least a subgroup of patients. Elevated levels of the inflammatory marker C-reactive protein (CRP) have been observed, with associations to pathogenesis and symptoms. The current evidence regarding effects of antipsychotics on CRP levels is ambiguous.

OBJECTIVES

To examine and compare the influence on CRP levels of three pharmacologically diverse new generation antipsychotics during a one-year follow-up in schizophrenia spectrum disorder.

METHODS

In a multicenter, pragmatic and rater-blinded randomized trial, the effects of amisulpride, aripiprazole and olanzapine were compared in 128 patients with schizophrenia spectrum disorder. All had positive symptoms of psychosis at study entry. Clinical and laboratory assessments including the measurement of CRP levels were conducted at baseline, and 1, 3, 6, 12, 26, 39, and 52 weeks thereafter.

RESULTS

For all antipsychotic drugs analysed together, there was an increase in CRP levels during the one-year follow-up. Aripiprazole, as opposed to amisulpride and olanzapine, was associated with a reduced CRP level after one week, after which the CRP level caught up with the other drugs. Compared to those previously exposed to antipsychotic drugs, antipsychotic-naïve patients had lower CRP levels at all follow-up time points, but with the same temporal patterns of change.

CONCLUSION

Treatment with amisulpride, aripiprazole and olanzapine showed different effects on CRP levels in patients with schizophrenia spectrum disorders, modified by previous antipsychotics exposure status. This finding suggests that antipsychotic drugs may vary with respect to their influence on pro-inflammatory pathways.

TRIAL REGISTRATION

ClinicalTrials.gov ID: NCT01446328; URL: http://www.

CLINICALTRIALS

gov/.

The association between cytokines and psychomotor speed in a spectrum of psychotic disorders: A longitudinal study

Background

In schizophrenia, impaired psychomotor speed is a common symptom predicting worse functional outcome. Inflammation causes changes in white matter integrity, which may lead to reduced psychomotor speed. Therefore, we wanted to investigate if peripheral inflammation assessed with cytokines affected performance on psychomotor speed in patients with a spectrum of psychotic disorders.

Methods

The current study is a prospective cohort study, including participants from a pragmatic, randomised controlled trial comparing three atypical antipsychotics in patients with a spectrum of psychotic disorders. For the purposes of this sub-study, we analysed drug treatment groups collectively. Psychomotor speed was assessed at baseline, and at weeks 6, 12, 26 and 52 of follow-up, using the neuropsychological tests trail making test (TMT) A and B, and symbol coding. Serum concentration of the following cytokines were measured: interleukin (IL)-β, IL-2, IL-4, IL-6, IL-10, IL12 p70, IL-17a, interferon (IFN)-γ and tumor necrosis factor (TNF)-α. Blood samples were collected at baseline and after 1, 3, 6, 12, 26, 39 and 52 weeks. We analysed the effect of cytokines levels on psychomotor speed over time in linear mixed effects models.

Results

In our linear mixed effects models controlling for possible confounders, IFN-γ had a significant negative effect on TMT-A and symbol coding performance. None of the other tests for psychomotor speed were significantly associated with cytokines. Overall psychomotor speed performance increased significantly across the study period while cytokine levels remained stable.

Conclusion

Our study indicates a negative association between IFN-γ and psychomotor speed, which might be of importance when understanding the mechanisms behind psychomotor deviations in psychotic disorders.

•

The cytokine interferon (IFN) – γ is related to psychomotor speed in patients with psychotic disorders.

•

For majority of cytokines, we found no significant association with psychomotor speed.

•

Cytokines remained stable during the study period of 52 weeks.

Targeting neurotransmitter-mediated inflammatory mechanisms of psychiatric drugs to mitigate the double burden of multimorbidity and polypharmacy

The increased incidence of multimorbidities and polypharmacy is a major concern, particularly in the growing aging population. While polypharmacy can be beneficial, in many cases it can be more harmful than no treatment, especially in individuals suffering from psychiatric disorders, who have elevated risks of multimorbidity and polypharmacy. Age-related chronic inflammation and immunopathologies might contribute to these increased risks in this population, but the optimal clinical management of drug-drug interactions and the neuro-immune mechanisms that are involved warrants further investigation. Given that neurotransmitter systems, which psychiatric medications predominantly act on, can influence the development of inflammation and the regulation of immune function, it is important to better understand these interactions to develop more successful strategies to manage these comorbidities and complicated polypharmacy. I propose that expanding upon research in translationally relevant human in vitro models, in tandem with other preclinical models, is critical to defining the neurotransmitter-mediated mechanisms by which psychiatric drugs alter immune function. This will define more precisely the interactions of psychiatric drugs and other immunomodulatory drugs, used in combination, enabling identification of novel targets to be translated into more efficacious diagnostic, preventive, and therapeutic interventions. This interdisciplinary approach will aid in better precision polypharmacy for combating adverse events associated with multimorbidity and polypharmacy in the future.

Safety and Efficacy of Combined Low-Dose Lithium and Low-Dose Aspirin: A Pharmacological and Behavioral Proof-of-Concept Study in Rats

Despite established efficacy in bipolar disorder patients, lithium (Li) therapy has serious side effects, particularly chronic kidney disease. We examined the safety and behavioral effects of combined chronic low-dose aspirin plus low-dose Li in rats to explore the toxicity and therapeutic potential of this treatment. Rats were fed regular or Li-containing food (0.1% [low-dose, LLD-Li] or 0.2% [standard-dose, STD-Li]) for six weeks. Low-dose aspirin (1 mg/kg) was administered alone or together with Li. Renal function and gastric mucosal integrity were assessed. The effects of the combination treatment were evaluated in depression-like and anxiety-like behavioral models. Co-treatment with aspirin did not alter plasma Li levels. Chronic STD-Li treatment resulted in significant polyuria and polydipsia, elevated blood levels of creatinine and cystatin C, and increased levels of kidney nephrin and podocin—all suggestive of impaired renal function. Aspirin co-treatment significantly damped STD-Li-induced impairments in kidney parameters. There were no gastric ulcers or blood loss in any treatment group. Combined aspirin and LLD-Li resulted in a significant increase in sucrose consumption, and in the time spent in the open arms of an elevated plus-maze compared with the LLD-Li only group, suggestive of antidepressant-like and anxiolytic-like effects, respectively. Thus, we demonstrate that low-dose aspirin mitigated the typical renal side effects of STD-Li dose and enhanced the beneficial behavioral effects of LLD-Li therapy without aggravating its toxicity.

Repurposing haloperidol for the treatment of rheumatoid arthritis: an integrative approach using data mining techniques

Introduction

Treatment of rheumatoid arthritis (RA) has advanced with the introduction of biological disease-modifying antirheumatic drugs. However, more than 20% of patients with RA still have moderate or severe disease activity. Hence, novel antirheumatic drugs are required. Recently, drug repurposing, a process of identifying new indications for existing drugs, has received great attention. Furthermore, a few reports have shown that antipsychotics are capable of affecting several cytokines that are also modulated by existing antirheumatic drugs. Therefore, we investigated the association between antipsychotics and RA by data mining using real-world data and bioinformatics databases.

Methods

Disproportionality and sequence symmetry analyses were employed to identify the associations between the investigational drugs and RA using the US Food and Drug Administration Adverse Event Reporting System (2004-2016) and JMDC administrative claims database (January 2005-April 2017; JMDC Inc., Tokyo, Japan), respectively. The reporting odds ratio (ROR) and information component (IC) were used in the disproportionality analysis to indicate a signal. The adjusted sequence ratio (SR) was used in the sequence symmetry analysis to indicate a signal. The bioinformatics analysis suite, BaseSpace Correlation Engine (Illumina, CA, USA) was employed to explore the molecular mechanisms associated with the potential candidates identified by the drug-repurposing approach.

Results

A potential inverse association between the antipsychotic haloperidol and RA, which exhibited significant inverse signals with ROR, IC, and adjusted SR, was found. Furthermore, the results suggested that haloperidol may exert antirheumatic effects by modulating various signaling pathways, including cytokine and chemokine signaling, major histocompatibility complex class-II antigen presentation, and Toll-like receptor cascade pathways.

Conclusion

Our drug-repurposing approach using data mining techniques identified haloperidol as a potential antirheumatic drug candidate.

Neurodevelopmental Disorders (NDD) Caused by Genomic Alterations of the Ubiquitin-Proteasome System (UPS): the Possible Contribution of Immune Dysregulation to Disease Pathogenesis

Over thirty years have passed since the first description of ubiquitin-positive structures in the brain of patients suffering from Alzheimer’s disease. Meanwhile, the intracellular accumulation of ubiquitin-modified insoluble protein aggregates has become an indisputable hallmark of neurodegeneration. However, the role of ubiquitin and a fortiori the ubiquitin-proteasome system (UPS) in the pathogenesis of neurodevelopmental disorders (NDD) is much less described. In this article, we review all reported monogenic forms of NDD caused by lesions in genes coding for any component of the UPS including ubiquitin-activating (E1), -conjugating (E2) enzymes, ubiquitin ligases (E3), ubiquitin hydrolases, and ubiquitin-like modifiers as well as proteasome subunits. Strikingly, our analysis revealed that a vast majority of these proteins have a described function in the negative regulation of the innate immune response. In this work, we hypothesize a possible involvement of autoinflammation in NDD pathogenesis. Herein, we discuss the parallels between immune dysregulation and neurodevelopment with the aim at improving our understanding the biology of NDD and providing knowledge required for the design of novel therapeutic strategies.

BDNF in antipsychotic naive first episode psychosis: Effects of risperidone and the immune-inflammatory response system

Brain-derived neurotrophic factor (BDNF) and the immune-inflammatory response system (IRS) have been implicated in the pathophysiology of schizophrenia. However, no research examined the associations between BDNF and immune activation both before and after treatment in antipsychotic-naïve first episode psychosis (AN-FEP). This study aims to examine serum BDNF levels and their association with IRS and the compensatory immune-regulatory reflex system (CIRS) in AN-FEP before and after risperidone treatment. We included 31 AN-FEP and 22 healthy controls. AN-FEP showed reduced levels of BDNF as compared to controls, and BDNF levels normalized after treatment with risperidone. BDNF levels were inversely correlated with a greater IRS response. Higher levels of IRS/CIRS biomarkers were associated with lower levels of BDNF including M1 macrophage, T-helper (Th)-1, Th-2, and Th-17, and T-regulatory (Treg) cell responses. Our findings indicate that AN-FEP is characterized by decreased levels of BDNF, which are normalized after treatment with risperidone. BDNF levels were inversely associated with activated immune-inflammatory pathways. The findings support the hypothesis that, increased IRS is linked to neurotoxicity, and that a decrease in BDNF may be part of the IRS/CIRS responses in FEP and, thus, be involved in the development of psychosis.

The Role of Cytokines in the Pathogenesis of Schizophrenia

Schizophrenia is a chronic mental illness of unknown etiology. A growing and compelling body of evidence implicates immunologic dysfunction as the key element in its pathomechanism. Cytokines, whose altered levels have been increasingly reported in various patient populations, are the major mediators involved in the coordination of the immune system. The available literature reports both elevated levels of proinflammatory as well as reduced levels of anti-inflammatory cytokines, and their effects on clinical status and neuroimaging changes. There is evidence of at least a partial genetic basis for the association between cytokine alterations and schizophrenia. Two other factors implicated in its development include early childhood trauma and disturbances in the gut microbiome. Moreover, its various subtypes, characterized by individual symptom severity and course, such as deficit schizophrenia, seem to differ in terms of changes in peripheral cytokine levels. While the use of a systematic review methodology could be difficult due to the breadth and diversity of the issues covered in this review, the applied narrative approach allows for a more holistic presentation. The aim of this narrative review was to present up-to-date evidence on cytokine dysregulation in schizophrenia, its effect on the psychopathological presentation, and links with antipsychotic medication. We also attempted to summarize its postulated underpinnings, including early childhood trauma and gut microbiome disturbances, and propose trait and state markers of schizophrenia.

Is TGF-β1 a Biomarker of Huntington's Disease Progression?

Huntington's disease (HD) is an autosomal dominant genetic disease that can be divided into preclinical and symptomatic stages. Due to the diverse HD phenotype, there is an urgent need to identify markers that would independently assess its severity. The aim of this study was to evaluate the use of plasma levels of TGF-β1 in the assessment of HD severity. One hundred HD patients and 40 healthy volunteers were included in the study. All HD patients underwent neurological and cognitive function assessment. TGF-β1 levels were determined in the plasma of all patients. The correlations between TGF-β1 levels and clinical profile and HD severity were also investigated. In symptomatic patients, cognitive decline was demonstrated, while in preclinical patients, no symptoms were found. Plasma levels of TGF-β1 in HD patients did not differ significantly from the control group and did not change with the progression of the disease. In addition, TGF-β1 levels also did not correlate with the severity of motor dysfunction. Positive correlations between plasma TGF-β1 concentration and intensity of cognitive impairment were found, but only in the early disease stage. There was no clear benefit in assessing plasma TGF-β1 levels in HD patients as a marker of disease severity.

Analysis of cognitive impairment in schizophrenia based on machine learning: Interaction between psychological stress and immune system

The interaction between psychological stress and immune system may be associated with the cognitive impairment of schizophrenia. To employ machine learning algorithms to examine patterns of stress-immune networks with cognitive impairment in chronic schizophrenia, we selected cortisol, tumor necrosis factor (TNF) - α, interleukin (IL) - 2, IL-6 and IL-8 as biochemical indices reflecting the dysfunctional response to psychological stress and immune system in patients with schizophrenia. Basedon 14 kinds of interactions of above five variables, we were able to classify 37 chronic schizophrenia patients and 35 age and gender-matched healthy controls by using decision tree (DT) (Accuracy = 93.1%, Sensitivity = 97.3%, Specificity = 88.6%), random forest (RF) (Accuracy = 94.4%, Sensitivity = 91.9%, Specificity = 97.1%) and support vector machines (SVM) (Accuracy = 98.6%, Sensitivity = 100.0%, Specificity = 97.1%), which indicating that cortisol × TNF-α × IL-8 was the top risk factor for identifying chronic schizophrenia. Furthermore, we found that cortisol × TNF-α × IL-8 was positively correlated with PANSS cognitive subscore. Multiple stepwise linear regression analysis confirmed that PANSS cognitive subscore was correlated with duration of illness and cortisol × TNF-α × IL-8. The results suggest that the glucocorticoid-immune relationship may have an effect on the cognitive impairment of patients.

A Meta-Analysis of the Influence of Antipsychotics on Cytokines Levels in First Episode Psychosis

Background: Cytokines have a major impact on the neurotransmitter networks that are involved in schizophrenia pathophysiology. First Episode Psychosis (FEP) patients exhibit abnormalities in cytokines levels prior to the start of treatment. Previous studies showed that antipsychotic treatment modulates cytokines levels. The aim of this meta-analysis is to further investigate this relationship. Methods: Several online databases were searched. For meta-analysis of selected studies, we analysed variables containing the number of cases, mean and standard deviation of IL-1β, IL-2, IL-4, IL-6, IL-10, IL-17, TNF-α, IFN-γ levels before, and after, antipsychotic treatment. Results: 12 studies were included in the meta-analysis. Our main results demonstrate that, in FEP patients, antipsychotic treatment is related to decreased concentrations of pro-inflammatory IL-1β, IL-6, IFN-γ, TNF-α and anti-inflammatory IL-4, IL-10 cytokines. On the other hand, levels of pro-inflammatory IL-2 and IL-17 remain unaffected. Conclusions: When compared with other meta-analyses of studies involving FEP individuals, results we obtained are consistent regarding decrease in IL-1β, IL-6. Comparing outcomes of our study with meta-analyses of schizophrenic subjects, in general, our results are consistent in IL-1β, IL-6, TNF-α, IFN-γ, IL-2. Our meta-analysis is the only one which indicates a decrease in anti-inflammatory IL-10 in FEP patients after antipsychotic treatment.

Alarmins (IL-33, sST2, HMGB1, and S100B) as potential biomarkers for schizophrenia

There is growing evidence that immune/inflammatory processes are related to the etiology of schizophrenia. Danger-/damage-associated molecular patterns (DAMPs), also called alarmins, are recognized as inflammatory mediators that play an important role in the development of many infection-induced or sterile inflammatory diseases. The importance of DAMPs particles in various mental disorders is still not clear. Therefore, this study aimed to evaluate serum levels of the most promising alarmins (IL-33, sST2, HMGB1, and S100B), as potent schizophrenia biomarkers. Sixty-eight adult patients with chronic schizophrenia and twenty-nine healthy volunteers were included in this prospective study. Enzyme-linked immunosorbent assay (ELISA) was used to assess the serum concentration of IL-33, sST2, HMGB1, and S100B. We documented that the serum levels of IL-33 (p = 0.006), sST2 (p = 0.02), HMGB1 (p = 0.01), and S100B (p = 0.04) are significantly higher in patients with schizophrenia than in healthy subjects. In male, but not in female, patients with schizophrenia, we found a significant difference in the serum IL-33, sST2, and HMGB1 concentrations as compared to the healthy men. In both male and female patients with schizophrenia, there was no significant difference in the serum concentrations of S100B in comparison to control subjects. In patients with schizophrenia, no significant correlations were noticed neither between any studied alarmins and PANSS scores nor between CDSS scores. Given that all investigated alarmins participate in the course of the neuroinflammatory process, they might be considered as biomarkers of neuroinflammatory process underlying schizophrenia. Based on our observations, it seems that the most useful biological indicator of schizophrenia would be IL-33.

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

The present study aims at comparing the change in cytokine levels in schizophrenia patients treated with atypical antipsychotics, with or without metabolic syndrome (MetS). The study included 101 patients with schizophrenia, 38 with and 63 without MetS, who received risperidone, quetiapine, olanzapine or aripiprazole for six weeks. We analyzed the concentration of 21 cytokines in the serum patients. The treatment with atypical antipsychotics changed some proinflammatory cytokine levels. It led to increased IFN-α2 (p = 0.010), IL-1α (p = 0.024) and IL-7 (p = 0.017) levels in patients with MetS, whereas the same treatment led to decreased levels of IFN-γ (p = 0.011), IL-1β (p = 0.035), IL-12р40 (p = 0.011), IL-17A (p = 0.031), IL-6 (p = 0.043) and TNF-α (p = 0.012) in individuals without MetS. Our results demonstrated the effects of atypical antipsychotics on the immune–inflammatory parameters, depending on the metabolic disturbances in schizophrenia patients.