Cytokines dysregulation in schizophrenia: A systematic review of psychoneuroimmune relationship

Systemic inflammation and grey matter volume in schizophrenia and bipolar disorder: Moderation by childhood trauma severity

BACKGROUND

Elevated levels of systemic inflammation are consistently reported in both schizophrenia (SZ) and bipolar-I disorder (BD), and are associated with childhood trauma exposure. We tested whether childhood trauma exposure moderates associations between systemic inflammation and brain morphology in people with these diagnoses.

METHODS

Participants were 55 SZ cases, 52 BD cases and 59 healthy controls (HC) who underwent magnetic resonance imaging. Systemic inflammation was measured using a composite z-score derived from serum concentrations of interleukin 6, tumor necrosis factor alpha and C-reactive protein. Indices of grey matter volume covariation (GMC) were derived from independent component analysis. Childhood trauma was measured using the Childhood Trauma Questionnaire (CTQ Total score).

RESULTS

A series of moderated moderation analyses indicated that increased systemic inflammation were associated with increased GMC in the striatum and cerebellum among all participants. Severity of childhood trauma exposure moderated the relationship between systemic inflammation and GMC in one component, differently among the groups. Specifically, decreased GMC in the PCC/precuneus, parietal lobule and postcentral gyrus, and increased GMC in the left middle temporal gyrus was associated with increased systemic inflammation in HC individuals exposed to high (but not low or average) levels of trauma and in SZ cases exposed to low (but not average or high) levels of trauma, but not in BD cases.

CONCLUSIONS

Increased systemic inflammation is associated with grey matter changes in people with psychosis, and these relationships may be partially and differentially moderated by childhood trauma exposure according to diagnosis.

Potential Transdiagnostic Lipid Mediators of Inflammatory Activity in Individuals With Serious Mental Illness

Mental disorders are heterogeneous and psychiatric comorbidities are common. Previous studies have suggested a link between inflammation and mental disorders. This link can manifest as increased levels of proinflammatory mediators in circulation and as signs of neuroinflammation. Furthermore, there is strong evidence that individuals suffering from psychiatric disorders have increased risk of developing metabolic comorbidities. Our group has previously shown that, in a cohort of low-functioning individuals with serious mental disorders, there is increased expression of genes associated with the NLRP3 inflammasome, a known sensor of metabolic perturbations, as well as increased levels of IL-1-family cytokines. In the current study, we set out to explore the interplay between disease-specific changes in lipid metabolism and known markers of inflammation. To this end, we performed mass spectrometry-based lipidomic analysis of plasma samples from low-functioning individuals with serious mental disorders (n = 39) and matched healthy controls (n = 39). By identifying non-spurious immune-lipid associations, we derived a partial correlation network of inflammatory markers and molecular lipids. We identified levels of lipids as being altered between individuals with serious mental disorders and controls, showing associations between lipids and inflammatory mediators, e.g., osteopontin and IL-1 receptor antagonist. These results indicate that, in low-functioning individuals with serious mental disorders, changes in specific lipids associate with immune mediators that are known to affect neuroinflammatory diseases.

The Differences between Gluten Sensitivity, Intestinal Biomarkers and Immune Biomarkers in Patients with First-Episode and Chronic Schizophrenia

Schizophrenia is a heterogeneous disorder without a fully elucidated etiology and mechanisms. One likely explanation for the development of schizophrenia is low-grade inflammation, possibly caused by processes in the gastrointestinal tract related to gluten sensitivity. The aims of this study were to: (1) compare levels of markers of gluten sensitivity, inflammation and gut permeability, and (2) determine associations between gluten sensitivity, inflammation, and intestinal permeability in patients with first-episode/chronic (FS/CS) schizophrenia and healthy individuals (HC). The total sample comprised 162 individuals (52 FS; 50 CS, and 60 HC). The examination included clinical variables, nutritional assessment, and serum concentrations of: high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), soluble CD14 (sCD14), anti-Saccharomyces cerevisiae antibody (ASCA), antigliadin antibodies (AGA) IgA/IgG, antibodies against tissue transglutaminase 2 (anti-tTG) IgA, anti-deamidated gliadin peptides (anti-DGP) IgG. A significant difference between groups was found in sCD14, ASCA, hs-CRP, IL-6 and AGA IgA levels. AGA IgG/IgA levels were higher in the FS (11.54%; 30.77%) and CS (26%; 20%) groups compared to HC. The association between intestinal permeability and inflammation in the schizophrenic patients only was noted. The risk for developing schizophrenia was odds ratio (OR) = 4.35 (95% confidence interval (CI 1.23-15.39) for AGA IgA and 3.08 (95% CI 1.19-7.99) for positive AGA IgG. Inflammation and food hypersensitivity reactions initiated by increased intestinal permeability may contribute to the pathophysiology of schizophrenia. The immune response to gluten in FS differs from that found in CS.

Large-Scale Evidence for an Association Between Peripheral Inflammation and White Matter Free Water in Schizophrenia and Healthy Individuals

INTRODUCTION

Clarifying the role of neuroinflammation in schizophrenia is subject to its detection in the living brain. Free-water (FW) imaging is an in vivo diffusion-weighted magnetic resonance imaging (dMRI) technique that measures water molecules freely diffusing in the brain and is hypothesized to detect inflammatory processes. Here, we aimed to establish a link between peripheral markers of inflammation and FW in brain white matter.

METHODS

All data were obtained from the Australian Schizophrenia Research Bank (ASRB) across 5 Australian states and territories. We first tested for the presence of peripheral cytokine deregulation in schizophrenia, using a large sample (N = 1143) comprising the ASRB. We next determined the extent to which individual variation in 8 circulating pro-/anti-inflammatory cytokines related to FW in brain white matter, imaged in a subset (n = 308) of patients and controls.

RESULTS

Patients with schizophrenia showed reduced interleukin-2 (IL-2) (t = -3.56, P = .0004) and IL-12(p70) (t = -2.84, P = .005) and increased IL-6 (t = 3.56, P = .0004), IL-8 (t = 3.8, P = .0002), and TNFα (t = 4.30, P < .0001). Higher proinflammatory signaling of IL-6 (t = 3.4, P = .0007) and TNFα (t = 2.7, P = .0007) was associated with higher FW levels in white matter. The reciprocal increases in serum cytokines and FW were spatially widespread in patients encompassing most major fibers; conversely, in controls, the relationship was confined to the anterior corpus callosum and thalamic radiations. No relationships were observed with alternative dMRI measures, including the fractional anisotropy and tissue-related FA.

CONCLUSIONS

We report widespread deregulation of cytokines in schizophrenia and identify inflammation as a putative mechanism underlying increases in brain FW levels.

The Psychopharmacology of Obsessive-Compulsive Disorder: A Preclinical Roadmap

This review evaluates current knowledge about obsessive-compulsive disorder (OCD), with the goal of providing a roadmap for future directions in research on the psychopharmacology of the disorder. It first addresses issues in the description and diagnosis of OCD, including the structure, measurement, and appropriate description of the disorder and issues of differential diagnosis. Current pharmacotherapies for OCD are then reviewed, including monotherapy with serotonin reuptake inhibitors and augmentation with antipsychotic medication and with psychologic treatment. Neuromodulatory therapies for OCD are also described, including psychosurgery, deep brain stimulation, and noninvasive brain stimulation. Psychotherapies for OCD are then reviewed, focusing on behavior therapy, including exposure and response prevention and cognitive therapy, and the efficacy of these interventions is discussed, touching on issues such as the timing of sessions, the adjunctive role of pharmacotherapy, and the underlying mechanisms. Next, current research on the neurobiology of OCD is examined, including work probing the role of various neurotransmitters and other endogenous processes and etiology as clues to the neurobiological fault that may underlie OCD. A new perspective on preclinical research is advanced, using the Research Domain Criteria to propose an adaptationist viewpoint that regards OCD as the dysfunction of a normal motivational system. A systems-design approach introduces the security motivation system (SMS) theory of OCD as a framework for research. Finally, a new perspective on psychopharmacological research for OCD is advanced, exploring three approaches: boosting infrastructure facilities of the brain, facilitating psychotherapeutic relearning, and targeting specific pathways of the SMS network to fix deficient SMS shut-down processes. SIGNIFICANCE STATEMENT: A significant proportion of patients with obsessive-compulsive disorder (OCD) do not achieve remission with current treatments, indicating the need for innovations in psychopharmacology for the disorder. OCD may be conceptualized as the dysfunction of a normal, special motivation system that evolved to manage the prospect of potential danger. This perspective, together with a wide-ranging review of the literature, suggests novel directions for psychopharmacological research, including boosting support systems of the brain, facilitating relearning that occurs in psychotherapy, and targeting specific pathways in the brain that provide deficient stopping processes in OCD.

Improving Therapeutic Interventions of Schizophrenia with Advances in Stem Cell Technology

Although historic documents posit schizophrenia to the beginnings of mankind, its diagnosis remains poorly defined, currently relying on unspecific clinical symptoms; and controversies still maintain its origin under intense debate. This review aimed at quantitatively assessing the preferential forefronts of clinical trials towards the treatment of schizophrenia from inception till present, according to clinicaltrials.gov database registry. Towards that end study status and study phase classifications were used as criteria for progress in the field. Study groups by sex and age together with countries and organisms involved in the studies were used as indicators of the populations studied and as evidence of main promoter institutions, in both, pharmacological and drug-free protocols. The findings clearly show a decline of active clinical research with small synthetic compounds and limited numbers of novel initiatives, mostly based on drug-free alternatives with expected reduced secondary effects. A paucity of sex- and age-oriented designs is detected, and it is proposed that future clinical trials should set their basis on data obtained from patient-derived induced pluripotent stem cells, brain organoid systems and human brain circuitry platforms. Only individual precision medical approaches may turn effective for the treatment of this complex and highly incapacitating disease.

Effect of the C-reactive protein gene on risk and clinical characteristics of schizophrenia in winter-born individuals

C-reactive protein (CRP) levels are elevated in a subset of schizophrenia patients and correlated with more severe symptoms, which makes CRP a potential theranostic biomarker for the disease. However, genotypes associated with higher CRP concentrations have the protective effect against schizophrenia. To resolve this discrepancy, more research on the role of CRP in schizophrenia is needed. The present study aimed to investigate the effects on schizophrenia of the CRP gene in combination with season of birth (SOB), the known risk factor for the disease. We first examined the impact of seasonality on schizophrenia risk in the Russian population, using samples of 2452 patients and 1203 controls, and then assessed the CRP rs2794521 polymorphism × SOB interaction effect on the disease risk, age-of-onset and symptoms severity in 826 patients and 476 controls. An excess of winter births in patients was not significant. At the same time, we found that winter-born patients carrying the CRP GG genotype, which is associated with low transcriptional activity, had an earlier age at onset than the other patients. The findings are in line with the protective role of high active CRP genetic variants in the development of schizophrenia and provide support for the hypothesis that this effect of CRP takes place early in life.

A transnosographic approach of negative symptoms pathophysiology in schizophrenia and depressive disorders

BACKGROUND

Negative Symptoms (blunted affect, alogia, anhedonia, avolition and asociality) are observed in schizophrenia but also in depressive disorders.

OBJECTIVE

To gather cognitive, neuroanatomical, neurofunctional and neurobiological knowledge of negative symptoms in studies on schizophrenia, depressive disorder, and transnosographic studies.

RESULTS

Blunted affect in schizophrenia is characterized by amygdala hyperactivation and frontal hypoactivation, also found in depressive disorder. Mirror neurons, may be related to blunted affect in schizophrenia. Alogia may be related to cognitive dysfunction and basal ganglia area impairments in schizophrenia. Data surrounding alogia in depressive disorder is scarce; wider speech deficits are often studied instead. Consummatory Anhedonia may be less affected than Anticipatory Anhedonia in schizophrenia. Anhedonia is associated with reward impairments and altered striatal functions in both diagnostics. Amotivation is associated with Corticostriatal Hypoactivation in both disorders. Anhedonia and amotivation are transnosographically associated with dopamine dysregulation. Asociality may be related to oxytocin.

CONCLUSION

Pathophysiological hypotheses are specific to each dimension of negative symptoms and overlap across diagnostic boundaries, possibly underpinning the observed clinical continuum.

The role of the retinoids in schizophrenia: genomic and clinical perspectives

Signalling by retinoid compounds is vital for embryonic development, with particular importance for neurogenesis in the human brain. Retinoids, metabolites of vitamin A, exert influence over the expression of thousands of transcripts genome wide, and thus, act as master regulators of many important biological processes. A significant body of evidence in the literature now supports dysregulation of the retinoid system as being involved in the aetiology of schizophrenia. This includes mechanistic insights from large-scale genomic, transcriptomic and, proteomic studies, which implicate disruption of disparate aspects of retinoid biology such as transport, metabolism, and signalling. As a result, retinoids may present a valuable clinical opportunity in schizophrenia via novel pharmacotherapies and dietary intervention. Further work, however, is required to expand on the largely observational data collected thus far and confirm causality. This review will highlight the fundamentals of retinoid biology and examine the evidence for retinoid dysregulation in schizophrenia.

Association between childhood trauma exposure and pro-inflammatory cytokines in schizophrenia and bipolar-I disorder

BACKGROUND

Elevated levels of pro-inflammatory cytokines are consistently reported in schizophrenia (SZ) and bipolar-I disorder (BD), as well as among individuals who have been exposed to childhood trauma. However, higher levels of inflammatory markers in these disorders are yet to be investigated with respect to levels of exposure to different types of childhood trauma.

METHODS

Participants were 68 cases with a diagnosis of schizophrenia/schizoaffective disorder (SZ), 69 cases with a diagnosis of psychotic BD and 72 healthy controls (HC). Serum levels of interleukin 6 (IL-6), tumour necrosis factor-α (TNF-α) and C-reactive protein (CRP) were quantified, and childhood trauma exposure was assessed with the Childhood Trauma Questionnaire.

RESULTS

The SZ group had significantly higher levels of IL-6, TNF-α and CRP when compared with the HC group (all p < 0.05, d = 0.41-0.63), as well as higher levels of TNF-α when compared with the BD group (p = 0.014, d = 0.50); there were no differences between the BD and HC groups for any markers. Exposure to sexual abuse was positively associated (standardised β = 0.326, t = 2.459, p = 0.018) with levels of CRP in the SZ group, but there were no significant associations between any form of trauma exposure and cytokine levels in the HC or BD groups.

CONCLUSIONS

These results contribute to the evidence for a chronic state of inflammation in SZ but not BD cases. Differential associations between trauma exposure and levels of pro-inflammatory cytokines across the diagnostic categories suggest that trauma may impact biological (stress and immune) systems differently in these patient groups.

Increased inflammasome activity in markedly ill psychiatric patients: An explorative study

The aim of this study was to investigate inflammatory perturbations in 40 patients with severe and complex psychiatric disorders by studying the activity of the NLRP3 inflammasome, with a trans-diagnostic approach. Gene expression of CASP1, NLRP3, PYCARD, IL1B, IL1RN, TNF showed a significant increase in the patient group compared to a matched control group. Plasma levels of IL1Ra, IL-18, TNF, IL-6 and CRP were increased in the patient group. Within the patient group, increased gene expression of inflammatory markers correlated with increased disease severity. The findings support the inflammation hypothesis for markedly ill psychiatric patients across diagnostic groups.

The Effects of Exercise on IL-6 Levels and Cognitive Performance in Patients with Schizophrenia

Exercise plays an important role in brain plasticity, leading to improvements in cognitive function and delaying the cognitive deterioration of healthy people. These effects can be observed in individuals with schizophrenia through improvements in their performance in cognitive tasks and a decrease in the symptomology of the disease. In this review we examine the current evidence for the roles that exercise and the immune system play in patients with schizophrenia, and specifically analyze the interleukin-6 (IL-6) pathway as a potential mechanism resulting in these positive effects. Inflammation and high levels of IL-6 are associated with both the severity of schizophrenia and the cognitive impairment suffered throughout the disease. Performing regular exercise can modulate IL-6 by lowering its basal levels and by causing lower acute increases in the plasma levels of this cytokine in response to exercise (an anti-inflammatory response to physical exertion). Although there is evidence for the positive effects of physical exercise on schizophrenia, more studies will be required to better understand how variation in different exercise parameters affects both the acute and chronic plasma levels of IL-6.

Early Senescence and Leukocyte Telomere Shortening in SCHIZOPHRENIA: A Role for Cytomegalovirus Infection?

Schizophrenia is a severe, chronic mental disorder characterized by delusions and hallucinations. Several evidences support the link of schizophrenia with accelerated telomeres shortening and accelerated aging. Thus, schizophrenia patients show higher mortality compared to age-matched healthy donors. The etiology of schizophrenia is multifactorial, involving genetic and environmental factors. Telomere erosion has been shown to be accelerated by different factors including environmental factors such as cigarette smoking and chronic alcohol consumption or by psychosocial stress such as childhood maltreatment. In humans, telomere studies have mainly relied on measurements of leukocyte telomere length and it is generally accepted that individuals with short leukocyte telomere length are considered biologically older than those with longer ones. A dysregulation of both innate and adaptive immune systems has been described in schizophrenia patients and other mental diseases supporting the contribution of the immune system to disease symptoms. Thus, it has been suggested that abnormal immune activation with high pro-inflammatory cytokine production in response to still undefined environmental agents such as herpesviruses infections can be involved in the pathogenesis and pathophysiology of schizophrenia. It has been proposed that chronic inflammation and oxidative stress are involved in the course of schizophrenia illness, early onset of cardiovascular disease, accelerated aging, and premature mortality in schizophrenia. Prenatal or neonatal exposures to neurotropic pathogens such as Cytomegalovirus or Toxoplasma gondii have been proposed as environmental risk factors for schizophrenia in individuals with a risk genetic background. Thus, pro-inflammatory cytokines and microglia activation, together with genetic vulnerability, are considered etiological factors for schizophrenia, and support that inflammation status is involved in the course of illness in schizophrenia.

Cytokine profiles and diagnoses in elderly, hospitalized psychiatric patients

BACKGROUND

There is a paucity of studies on inflammatory markers in elderly psychiatric patients. Hence, our study was undertaken to investigate cytokines as biomarkers in diagnostically unselected elderly patients admitted to a psychiatric hospital.

METHODS

Demographic data, clinical data and blood samples, including 27 cytokines, were collected from 98 patients above 60 years, consecutively admitted to a psychiatric hospital in Tromsø, Norway (69°N).

RESULTS

The most common diagnosis was Recurrent depressive disorder (26.5%), the second most common was dementia in Alzheimer's disease (20.4%). The most frequent somatic disease was cardiovascular disease (28%). No statistical association (p < 0.01) was found between cytokines and gender, age, BMI, anti-inflammatory drugs, psychotropic drugs, reason for admittance, smoking, vitamin supplements, alcohol consumption, length of stay, somatic disease (present/not-present) or psychiatric diagnoses. However, when allocating patients to two groups, depression and no depression, we found higher levels of 10 cytokines in the no depression group (FDR-p < 0.0044). Possibly, this could in part be explained by the higher prevalence of cardiovascular disease (CVD) and dementia in the no depression group, as these factors were significant predictors of patients being categorized as not depressed in a logistic regression. In addition, other unknown factors might have contributed to the association between no depression and elevated cytokines. On the other hand, the high level of psychiatric and somatic comorbidity in the study population may have led to increased levels of cytokines in general, possibly diluting the potential effect of other factors, depression included, on the cytokine levels. The size of the study, and particularly the size of the subgroups, represents a limitation of the study, as do the general heterogeneity and the lack of a control group.

CONCLUSIONS

There was no significant difference in cytokine levels between various psychiatric diagnoses in hospitalized elderly psychiatric patients. This indicates that previous findings of correlations between cytokines and various psychiatric disorders in highly selected adult cases might not be applicable to elderly psychiatric inpatients. Further immunological studies are needed on gerontopsychiatric patients in general and gerontopsychiatric patients with specific disorders, preferably with patients that are physically healthy.

TRIAL REGISTRATION

Retrospectively registered in the ISRCTN registry study, with study ID ISRCTN71047363 .

An Integrative Approach to Neuroinflammation in Psychiatric disorders and Neuropathic Pain

Neuroinflammation is a complex process involving both the peripheral circulation and the Central Nervous System (CNS) and is considered to underlie many CNS disorders including depression, anxiety, schizophrenia, and pain. Stressors including early-life adversity, psychosocial stress, and infection appear to prime microglia toward a pro-inflammatory phenotype. Subsequent inflammatory challenges then drive an exaggerated neuroinflammatory response involving the upregulation of pro-inflammatory mediators that is associated with CNS dysfunction. Several pharmacologic inhibitors of pro-inflammatory cytokines including TNF-α and IL-1β show good clinical efficacy in terms of ameliorating neuroinflammatory processes. Mind/body and plant-based interventions such as yoga, breathing exercises, meditation, and herbs/spices have also been demonstrated to reduce pro-inflammatory cytokines and have a positive impact on depression, anxiety, cognition, and pain. As the intricate connections between the immune system and the nervous system continue to be elucidated, successful therapies for reducing neuroinflammation will likely involve an integrated approach combining drug therapy with nonpharmacologic interventions.

Research Progress in Biological Studies of Schizophrenia in China in 2017

Schizophrenia is a severe mental disorder and its etiology and pathological mechanism are unknown. This article mainly introduces the progress of biological studies of schizophrenia in China in 2017, including neuroimaging, genetics, and immunology studies. It also introduces the research progress of high-risk psychotic syndrome and physiotherapy.

Altered Serum Tumor Necrosis Factor and Interleukin-1β in First-Episode Drug-Naive and Chronic Schizophrenia

Objective: Abnormality of the immune system might play a significant role in the pathogenesis of schizophrenia. We want to identity whether the serum TNF-α and IL-1β levels were changed in FEDN patients and CP and to investigate the relationship between both cytokines and psychopathological symptoms.

Methods: We recruited 69 FEDN patients, 87 CP and 61 healthy controls. Schizophrenia symptomatology was evaluated with the Positive and Negative Syndrome Scale (PANSS), the Scale for the Assessment of Negative Symptoms (SANS) and Clinical Global Impression Scale (CGI). Serum TNF-α and IL-1β levels were examined using sandwich enzyme-linked immunosorbent assay (ELISA).

Results: TNF-α and IL-1β levels in CP were significantly higher compared to healthy controls, but TNF-α and IL-1β levels in FEDN patients were significantly lower than in both CP and healthy controls. A moderate correlation between serum TNF-α or IL-1β levels and PANSS negative subscore was found in CP. But there was no correlation between altered cytokines and clinical symptoms in FEDN patients.

Conclusions: Increased TNF-α and IL-1β levels in chronic patients may be associated with the progression, psychotropic drugs or other factors occur during chronic stage. Immune modulating treatments may become a new strategy of therapy for this subgroup of patients.

Peripheral Etanercept Administration Normalizes Behavior, Hippocampal Neurogenesis, and Hippocampal Reelin and GABAA Receptor Expression in a Preclinical Model of Depression

Depression is a serious psychiatric disorder frequently comorbid with autoimmune disorders. Previous work in our lab has demonstrated that repeated corticosterone (CORT) injections in rats reliably increase depressive-like behavior, impair hippocampal-dependent memory, reduce the number and complexity of adult-generated neurons in the dentate gyrus, decrease hippocampal reelin expression, and alter markers of GABAergic function. We hypothesized that peripheral injections of the TNF-α inhibitor etanercept could exert antidepressant effects through a restoration of many of these neurobiological changes. To test this hypothesis, we examined the effect of repeated CORT injections and concurrent injections of etanercept on measures of object-location and object-in-place memory, forced-swim test behavior, hippocampal neurogenesis, and reelin and GABA β2/3 immunohistochemistry. CORT increased immobility behavior in the forced swim test and impaired both object-location and object-in-place memory, and these effects were reversed by etanercept. CORT also decreased both the number and complexity of adult-generated neurons, but etanercept restored these measures back to control levels. Finally, CORT decreased the number of reelin and GABA β2/3-ir cells within the subgranular zone of the dentate gyrus, and etanercept restored these to control levels. These novel results demonstrate that peripheral etanercept has antidepressant effects that are accompanied by a restoration of cognitive function, hippocampal neurogenesis, and GABAergic plasticity, and suggest that a normalization of reelin expression in the dentate gyrus could be a key component underlying these novel antidepressant effects.

Constructing the Immune Signature of Schizophrenia for Clinical Use and Research; An Integrative Review Translating Descriptives Into Diagnostics

Schizophrenia is considered a syndrome comprised by several disease phenotypes, covering a range of underlying pathologies. One of these disease mechanisms seems to involve immune dysregulation and neuroinflammation. While the current dopamine receptor-blocking antipsychotic drugs decrease psychotic symptoms and prevent relapse in the majority of patients with schizophrenia, there is a huge need to explore new treatment options that target other pathophysiological pathways. Such studies should aim at identifying robust biomarkers in order to diagnose and monitor the immune biophenotype in schizophrenia and develop better selection procedures for clinical trials with anti-inflammatory and immune-modulating drugs. In this focused review, we describe available methods to assess inflammatory status and immune disturbances in vivo. We also outline findings of immune disturbances and signs of inflammation at cellular, protein, and brain imaging levels in patients with schizophrenia. Furthermore, we summarize the results from studies with anti-inflammatory or other immune-modulating drugs, highlighting how such studies have dealt with participant selection. Finally, we propose a strategy to construct an immune signature that may be helpful in selecting and monitoring participants in studies with immune modulating drugs and also applicable in regular clinical work.