Search for atypical lymphocytes in schizophrenia

Microglia and Other Cellular Mediators of Immunological Dysfunction in Schizophrenia: A Narrative Synthesis of Clinical Findings

Schizophrenia is a complex psychiatric condition that may involve immune system dysregulation. Since most putative disease mechanisms in schizophrenia have been derived from genetic association studies and fluid-based molecular analyses, this review aims to summarize the emerging evidence on clinical correlates to immune system dysfunction in this psychiatric disorder. We conclude this review by attempting to develop a unifying hypothesis regarding the relative contributions of microglia and various immune cell populations to the development of schizophrenia. This may provide important translational insights that can become useful for addressing the multifaceted clinical presentation of schizophrenia.

CD 4+, CD 8+ and CD 19+cell surface antigen and abnormal mitochondria ultrastructure of peripheral blood P-type atypical lymphocytes in patients with schizophrenia

OBJECTIVE

P-type atypical lymphocytes may play important roles in the aetiology and therapy of schizophrenia. However, there is merely a direct immunological characterisation of it. The aim of this study is to explore the surface antigens of these cells and their comparative ultrastructure in schizophrenia.

METHODS

We recruited 25 age-and gender-matched patients with unmedicated schizophrenia, other mental diseases and healthy individuals. Peripheral venous blood was smeared and stained. CD4+, CD8+ and CD19+ cell surface antigen- positive lymphocytes were purified using magnetic beads and prepared for light microscopy and electron microscopy.

RESULTS

The percentages of P-type atypical lymphocytes (34.53% ± 9.92%) were significantly higher (p < 0.0001) in schizophrenia than that of other mental diseases (9.79% ± 3.45%). These cells could present CD4+, CD8+ and CD19+ surface antigens. Their relative ultrastructure differed from that of normal lymphocytes, especially in mitochondria, which showed abundant, aggregated and quite irregular mitochondria; for example, slight dilation of the foci, swelling, degeneration, and even cavity.

CONCLUSIONS

P-type atypical lymphocytes could be found among CD4+, CD8+, and CD19 + lymphocytes with schizophrenia. Their abnormal ultrastructure of mitochondria implied that energy metabolism might play an important role in the aetiology of schizophrenia.

Pharmacotherapy of schizophrenia: immunological aspects and potential role of immunotherapy

INTRODUCTION

Schizophrenia is a complex disorder owing to diversity in clinical phenotypes, overlapping symptoms, and heterogeneous clinical presentation. Even after decades of research, the exact causative mechanisms of schizophrenia are not completely known. Recent evidence indicates the role of immune dysfunction in schizophrenia pathogenesis as observed from alteration in immune cells, increased activity of complement cascade, and development of autoantibodies against neurotransmitter receptors. Immunotherapy involving immunosuppressants and cytokine-targeting drugs, have shown promising results in several clinical studies and it demands further research in this area.

AREAS COVERED

Here, the authors review the immunopathogenesis of schizophrenia, limitations of conventional, and atypical antipsychotic drugs and the potential role and limitations of immunotherapeutic drugs in schizophrenia management.

EXPERT OPINION

Schizophrenia is a complex disorder and poses a challenge to the currently available treatment approaches. Nearly 30% schizophrenia patients exhibit minimal response toward conventional and atypical antipsychotic drugs. Immune system dysfunction plays an important part of schizophrenia pathophysiology and existing monoclonal antibody (mAb) drugs targeting specific components of the immune system are being repositioned in schizophrenia. The authors call upon public and private funders to facilitate urgent and rigorous research efforts in exploring potential role of immunotherapy in schizophrenia.

Roles of inflammation in intrinsic pathophysiology and antipsychotic drug-induced metabolic disturbances of schizophrenia

Schizophrenia is a debilitating psychiatric illness that remains poorly understood. While the bulk of symptomatology has classically been associated with disrupted brain functioning, accumulating evidence demonstrates that schizophrenia is characterized by systemic inflammation and disturbances in metabolism. Indeed, metabolic disease is a major determinant of the high mortality rate associated with schizophrenia. Antipsychotic drugs (APDs) have revolutionized management of psychosis, making it possible to rapidly control psychotic symptoms. This has ultimately reduced relapse rates of psychotic episodes and improved overall quality of life for people with schizophrenia. However, long-term APD use has also been associated with significant metabolic disturbances including weight gain, dysglycemia, and worsening of the underlying cardiometabolic disease intrinsic to schizophrenia. While the mechanisms for these intrinsic and medication-induced metabolic effects remain unclear, inflammation appears to play a key role. Here, we review the evidence for roles of inflammatory mechanisms in the disease features of schizophrenia and how these mechanisms interact with APD treatment. We also discuss the effects of common inflammatory mediators on metabolic disease. Then, we review the evidence of intrinsic and APD-mediated effects on systemic inflammation in schizophrenia. Finally, we speculate about possible treatment strategies. Developing an improved understanding of inflammatory processes in schizophrenia may therefore introduce new, more effective options for treating not only schizophrenia but also primary metabolic disorders.

Meta-analysis of total and differential white blood cell counts in schizophrenia

OBJECTIVE

Schizophrenia is associated with alterations in blood inflammatory markers, including cytokines. Total white blood cell (WBC) count is a marker of low-grade inflammation. We conducted a meta-analysis of total and differential WBC counts in patients with schizophrenia.

METHOD

Articles were identified through a systematic search of PsycINFO, Pub Med, Web of Science, and the associated references. Data were analyzed using a random effects approach.

RESULTS

Twenty-four studies met the inclusion criteria. Blood total WBC, monocytes, and neutrophils were significantly higher in schizophrenia vs. controls with small-to-medium effect sizes (standardized mean difference [SMD] = 0.39-0.53, P < 0.01 for each). In first-episode psychosis compared with controls, neutrophils and monocytes were significantly increased with similar effect sizes (SMD = 0.40-0.41, P ≤ 0.01 for each), and there was a trend for higher total WBC (SMD = 0.46, P = 0.05).

CONCLUSIONS

Consistent with studies of other inflammatory markers, we found evidence for increased total and differential WBC counts in schizophrenia. Our results complement other studies of WBC counts in schizophrenia. These findings are relevant to the pathophysiology and potentially the treatment of schizophrenia.

Reduced regulatory T cells with increased proinflammatory response in patients with schizophrenia

AIM

To investigate whether circulating T cells including regulatory T cells (Treg) and derived cytokines contribute to the immune imbalance observed in schizophrenia.

METHODS

Forty patients with schizophrenia and 40 age, sex, body mass index, education, and smoking status-matched healthy controls (HC) are included in the study. We stained cells with anti-CD14, anti-CD3, anti-CD4, anti-CD8, anti-CD19, anti-CD20, and anti-CD16/56. Peripheral blood mononuclear cells (PBMCs) were isolated and stained with the human FoxP3 kit containing anti-CD4/anti-CD25 and intracellular anti-Foxp3. PBMCs were cultured for 72 h and stimulated with anti-CD3/anti-CD28. Cytokines (IL-2, IL-4, IL-6, IL-10, IFN-γ, TNF-α, and IL-17A) were measured from the culture supernatant and plasma using the Th1/Th2/Th17 cytokine bead array kit.

RESULTS

In comparison with HC, Treg percentages in schizophrenia were higher (1.17 ± 0.63 vs 0.81 ± 0.53, P = 0.005) in unstimulated but lower in the stimulated condition (0.73 ± 0.69 vs 0.97 ± 0.55, P = 0.011). Activated T cell percentages were higher in schizophrenia than HC in unstimulated (2.22 ± 0.78 vs 1.64 ± 0.89, P = 0.001) and stimulated (2.25 ± 1.01 vs 1.72 ± 1.00, P = 0.010) conditions. The culture supernatant levels of IL-6 (7505.17 ± 5170.07 vs 1787.81 ± 1363.32, P < 0.001), IL-17A (191.73 ± 212.49 vs 46.43 ± 23.99, P < 0.001), TNF-α (1557 ± 1059.69 vs 426.57 ± 174.62, P = 0.023), and IFN-γ (3204.13 ± 1397.06 vs 447.79 ± 270.13, P < 0.001); and plasma levels of IL-6 (3.83 ± 3.41vs 1.89 ± 1.14, P = 0.003) and IL-17A (1.20 ± 0.84 vs 0.83 ± 0.53, P = 0.033) were higher in patients with schizophrenia than HC.

CONCLUSION

Our explorative study shows reduced level of Foxp3 expressing Treg in a stimulated condition with induced levels of proinflammatory cytokines in patients with schizophrenia.

B-cells and schizophrenia: A promising link or a finding lost in translation?

Recent genetic studies have suggested a potential role for B-cells in the pathogenesis of schizophrenia. Greater insight in the functioning of B-cells in patients with schizophrenia is therefore of importance. In this narrative review we aim to give an overview of the current literature on B-cells and schizophrenia. We found no evidence for altered numbers of these cells in blood. We did find support for increased levels of B-cell related cytokines and certain autoantibodies. Studies on B-cell development and function, or their numbers in cerebrospinal fluid or brain tissue are very limited. Based on the available data we appraise whether various B-cell mediated pathological mechanisms are likely to play a role in schizophrenia and provide directions for future research.

Decreased IL-1ra and NCAM-1/CD56 Serum Levels in Unmedicated Patients with Schizophrenia Before and After Antipsychotic Treatment

OBJECTIVE

Schizophrenia (SZ) has been associated with the inflammatory-related and immunological pathogenesis. This study investigates the aberration of cytokines in patients with SZ.

METHODS

Thirty patients with SZ without antipsychotic treatment for at least two weeks participated. We measured the serum levels of fourteen cytokines at hospital admission and after 8-week antipsychotic treatment. Severity was measured by expanded version of 24-items brief psychiatric rating scale (BPRS-E). Repeated measure analyses of variance were conducted.

RESULTS

The interleukin-1 receptor antagonist (IL-1ra) was significantly decreased after 8-week antipsychotic treatment than those of before antipsychotic treatment (F=12.15, df=1/30, p=0.002). Neural cell adhesion molecule 1/CD56 (NCAM-1/CD56) was significantly decreased (F=6.61, df=1/30, p=0.016) among those with second-generation antipsychotics but not first-generation antipsychotics treatment. The changes of BPRS-E-manic and BPRS-E-anxiety scores correlated with the baseline IL-1ra (r=-0.393), IL-6 (r=-0.407), and insulin like growth factor binding protein 3 (r=-0.446). Additionally, the changes of BPRS-E and BPRS-E-negative scores correlated with the changes of brain-derived neurotrophic factor (r=0.372) and interferon-gamma (r=0.375).

CONCLUSION

Our study supports that IL-1ra and NCAM-1/CD56 may be considered as markers of developing SZ.

Reduced number of peripheral natural killer cells in schizophrenia but not in bipolar disorder

Overwhelming evidence indicates that subthreshold inflammatory state might be implicated in the pathophysiology of schizophrenia (SCZ) and bipolar disorder (BPD). It has been reported that both groups of patients might be characterized by abnormal lymphocyte counts. However, little is known about alterations in lymphocyte proportions that may differentiate SCZ and BPD patients. Therefore, in this study we investigated blood cell proportions quantified by means of microarray expression deconvolution using publicly available data from SCZ and BPD patients. We found significantly lower counts of natural killer (NK) cells in drug-naïve and medicated SCZ patients compared to healthy controls across all datasets. In one dataset from SCZ patients, there were no significant differences in the number of NK cells between acutely relapsed and remitted SCZ patients. No significant difference in the number of NK cells between BPD patients and healthy controls was observed in all datasets. Our results indicate that SCZ patients, but not BPD patients, might be characterized by reduced counts of NK cells. Future studies looking at lymphocyte counts in SCZ should combine the analysis of data obtained using computational deconvolution and flow cytometry techniques.

A systematic, quantitative review of blood autoantibodies in schizophrenia

OBJECTIVE

Schizophrenia is associated with immune system dysfunction, including an increased prevalence of autoimmune disorders and autoantibodies. We performed a systematic, quantitative review of self-reacting blood antibodies in patients with schizophrenia.

METHOD

We identified articles by searching PubMed, PsychInfo, and ISI, and the reference lists of identified studies.

RESULTS

Eighty-one of 111 studies identified met the inclusion criteria. There was a significant increased prevalence of positive titers for 20 different autoantibodies in patients with schizophrenia compared to controls. The prevalence of positive anti-cardiolipin IgG and NMDA receptor titers was also significantly increased in subjects with first-episode psychosis versus controls (p<0.01). Absolute titers for anti-cardiolipin IgG and IgM, and nerve growth factor were significantly increased in patients with schizophrenia compared to controls (p<0.02 for each).

CONCLUSION

Schizophrenia is associated with an increased prevalence of multiple autoantibodies, although there is marked study heterogeneity, and correlations between autoantibodies and clinical features are inconsistent. This area merits more research evaluation, especially controlling for potential confounding factors such as clinical status, age, genetic background, psychotropic medications, BMI, and smoking.

Meta-analysis of lymphocytes in schizophrenia: clinical status and antipsychotic effects

BACKGROUND

Schizophrenia is associated with immune system dysfunction, including abnormal blood immune cell parameters. We performed a meta-analysis of these associations, considering the effect of clinical status and antipsychotic treatment following an acute exacerbation of psychosis.

METHODS

We identified articles by searching PubMed, PsycINFO, and Thomson Reuters (formerly ISI) Web of Knowledge and the reference lists of identified studies.

RESULTS

Sixteen studies of blood lymphocytes met the inclusion criteria. There was insufficient data for a meta-analysis of the mononuclear phagocytic system. In cross-sectional studies, there was a significant increase in the CD4% and CD56% in acutely relapsed inpatients. Absolute levels of total lymphocytes, CD3, and CD4, and the CD4/CD8 ratio were significantly increased, and the CD3% was significantly decreased in drug-native first-episode psychosis. In longitudinal studies, the CD4/CD8 ratio appeared to be state-related markers, as it decreased following antipsychotic treatment for acute exacerbations of psychosis. Absolute CD56 levels appeared to be a trait marker, as levels significantly increased following antipsychotic treatment for relapse.

CONCLUSIONS

Blood lymphocyte abnormalities in drug-naïve first-episode psychosis suggest an effect that may be independent of antipsychotic medications. While some parameters (CD4/CD8) may be state markers for acute exacerbations of psychosis, others (CD56) may be trait markers; however, more longitudinal studies are needed. Although these findings could provide the basis for future hypothesis testing, a relatively small number of studies and subjects, lack of correlative data with clinical features, and inadequate consideration of potential confounding factors limit the results.

Immunomodulation in schizophrenia: A study among the Indian schizophrenia patients of Siliguri, West Bengal

Authors investigated the circumstantial evidence for autoimmunity in schizophrenia patients of Siliguri by considering the immune parameters like HLA Class I genes, IL-2 and IL6 and T cell subsets. Low resolution PCR-SSP method was applied for typing the HLA genes. Serum levels of IL-2 and IL-6 were measured by ELISA method. The CD4+ and CD8+ subset count were done using flow cytometry. A significant increase in HLA A*03 gene was observed in patients along with the significant decrease of HLA-A*31 and HLA-B*51. Both IL-2 and IL-6 were found to have decreased levels in the patients. Although the mean percentage of CD4+ and CD8+ cells was higher in patients but not significantly higher than controls. These cumulative preliminary findings are suggestive of alterations in the immune system of schizophrenia patients of this region.

Anti-inflammatory signaling in schizophrenia

A great deal of interest has been centered upon activated inflammatory processes in schizophrenia and their contribution to disease-relevant brain and behavioral impairment. In contrast, the role of anti-inflammatory signaling has attracted somewhat less attention in this context. The present article focuses on the emerging role of anti-inflammatory signaling in schizophrenia and discusses the potential influence of altered anti-inflammatory activity on progressive inflammatory processes, physical and metabolic functions, and treatment effects related to the use of conventional antipsychotic drugs and immunomodulatory agents in the pharmacotherapy of schizophrenia. By reviewing existing evidence, it appears that enhanced anti-inflammatory activity has many faces in schizophrenia: On the one hand, it may effectively limit potentially harmful inflammatory processes and may contribute to the improvement of psychopathological symptoms, especially when the anti-inflammatory system is boosted at early stages of the disease. On the other hand, enhanced anti-inflammatory activity may render affected individuals more susceptible to distinct physiological abnormalities such as cardiovascular disease, and may further impede the resistance to specific infectious agents. Therefore, an enhancement of anti-inflammatory signaling in schizophrenia might not simply be said to be either advantageous or disadvantageous, but rather should be interpreted and dealt with in a context-dependent manner. Increased awareness of the multiple roles of anti-inflammatory signaling may readily help to reduce additional health burdens in schizophrenia, and at the same time, may provide opportunities to further explore the benefits associated with anti-inflammatory strategies in the symptomatological and/or preventive treatment of this disorder.

Oxidative stress in schizophrenia: an integrated approach

Oxidative stress has been suggested to contribute to the pathophysiology of schizophrenia. In particular, oxidative damage to lipids, proteins, and DNA as observed in schizophrenia is known to impair cell viability and function, which may subsequently account for the deteriorating course of the illness. Currently available evidence points towards an alteration in the activities of enzymatic and nonenzymatic antioxidant systems in schizophrenia. In fact, experimental models have demonstrated that oxidative stress induces behavioral and molecular anomalies strikingly similar to those observed in schizophrenia. These findings suggest that oxidative stress is intimately linked to a variety of pathophysiological processes, such as inflammation, oligodendrocyte abnormalities, mitochondrial dysfunction, hypoactive N-methyl-d-aspartate receptors and the impairment of fast-spiking gamma-aminobutyric acid interneurons. Such self-sustaining mechanisms may progressively worsen producing the functional and structural consequences associated with schizophrenia. Recent clinical studies have shown antioxidant treatment to be effective in ameliorating schizophrenic symptoms. Hence, identifying viable therapeutic strategies to tackle oxidative stress and the resulting physiological disturbances provide an exciting opportunity for the treatment and ultimately prevention of schizophrenia.

Acute schizophrenia is accompanied by reduced T cell and increased B cell immunity

Previous studies of lymphocyte distribution in schizophrenia have yielded inconsistent results, as summarized in the present study. Based on our own original data, potential confounds that might explain these variations are analyzed and discussed. Blood samples from 26 patients with acute paranoid schizophrenia were investigated in comparison with 32 matched healthy controls by flow cytometry (CD3, CD4, CD8, CD19, and CD56 phenotyping). A subgroup of drug-free patients was followed up after 6 weeks of treatment. Cotinine levels and the free cortisol index (FCI) were provided in order to control for medication, smoking, and stress. Cotinine levels correlated with natural killer (NK) cell counts (CD3⁻/CD56(+): r = -0.383, P = 0.003) while the FCI was related to B cell numbers (CD19(+): r = 0.390, P = 0.003). Considering these covariates, a lower level of T helper cells (P = 0.010), a reduced CD4/CD8 ratio (P = 0.029), and elevated B cells (P = 0.008) were found during acute psychosis. After 6 weeks of medication, an inverse pattern was observed in initially drug-free patients: total T cell (P = 0.005), T helper (P = 0.003), and T suppressor/cytotoxic cells (P = 0.005) increased, while B cell counts declined (P = 0.049). In conclusion, acute paranoid schizophrenia may be accompanied by a reduced T cell defense and a shift towards B cell immunity, which normalizes in response to treatment. In addition to disease stage or subtype and medication, cigarette smoking and stress are important co-factors.

Effects of venlafaxine and fluoxetine on lymphocyte subsets in patients with major depressive disorder: a flow cytometric analysis

BACKGROUND

Studies have yielded conflicting results concerning flow cytometric lymphocyte analyses in patients with depression. Data about the effect of antidepressants on lymphocyte subsets are also contradictory. The aim of this study was to determine effects of venlafaxine versus fluoxetine on lymphocyte subsets in depressive patients.

METHODS

Sixty-nine patients diagnosed with major depressive disorder (MDD) according to DSM-IV and 36 healthy controls are included in the study. Sixty-nine patients were randomized to take fluoxetine (FLX) (n=33) or venlafaxine (VEN) (n=36). Serum lymphocyte subsets included CD3, CD4, CD8, CD16/56, CD19, CD45, Anti-HLA-DR which were measured by flow cytometric analyses at baseline and 6 weeks after the start of treatment. The severity of depression was evaluated with Hamilton rating scale for depression.

RESULTS

At baseline, patients with MDD had significantly lower CD16/56 ratio and higher CD45 ratio compared to the controls. Although numerically higher in the VEN treated patients, treatment response rates between the FLX (53%) and the VEN (75%) groups were not different statistically. CD45 values decreased significantly in the VEN group at the end of the 6 week treatment period whereas no difference was observed in the FLX group. By the 6th week, treatment responders showed a significantly higher CD16/56 ratio than non-responders. Baseline severity of depression and anxiety was positively correlated with baseline CD45 ratio and negatively correlated with baseline CD16/56 ratio. We did not observe consistent changes in the absolute number of circulating B or T cells, nor in the helper/inducer (CD4) or suppressor/cytotoxic (CD8) subsets.

CONCLUSIONS

CD16/56 was lower in patients with MDD and increased in treatment responders at 6th week. CD45 ratio was higher in patients with MDD than healthy subjects; it decreased with antidepressant treatment and was positively correlated with the severity of depression. Antidepressant treatment contributes to immune regulation in patients with major depressive disorder.

Problems and promise of immunological factors as biomarkers for schizophrenia

The complex and multifactorial etiology of psychiatric disorders, and in particular that of schizophrenia, has made it difficult to identify biomarkers suitable for clinical diagnosis. In schizophrenia research, the investigation of immune-related factors has been of central importance in the quest to unravel the disease etiology. However, immunological findings have been controversial, and the importance of an underlying immunopathology in schizophrenia remains to be irrevocably established. Here we review those findings that have been most consistently reported. We further address their potential utility for clinical diagnosis and drug development. We also discuss problems connected to sample collection and preparation, with special focus on their effects on immune-derived parameters. In light of recent findings, we highlight the potential of combining functional cell-based assays with high-throughput multiomics experiments for the discovery of novel biomarkers.

The ultrastructure of lymphocytes in schizophrenia

OBJECTIVE

Replicated abnormalities in schizophrenia include decreased cellular immunity. The aim of the study was to verify whether there are some abnormalities in the ultrastructure of lymphocytes in drug-free schizophrenic patients.

METHOD

Fifty-nine in-patients with paranoid schizophrenia (DSM-IV 295.30) and 31 normal controls were used. Psychosis severity was assessed by the PANSS psychotic cluster. Electron microscopy and morphometric methods were applied to estimate the frequency and ultrastructural parameters of small, large, large activated lymphocytes (LAL) (containing 10 and more mitochondria) and of atypical lymphocytes (lymphoblasts, LB).

RESULTS

The frequency of small lymphocytes in schizophrenic patients was lower and that of large lymphocytes, LAL and LB was higher than in controls (all p= < 0.01). The volume density (Vv) of mitochondria in LAL in individuals with schizophrenia was lower than in controls (p<0.05), correlated negatively with the frequency of LB, Vv and number of lysosomes in LB (all p<0.01) and with the psychosis severity (p<0.05). In schizophrenic patients a trend towards positive correlations between the frequency of LB and psychosis severity were found (p<0.07).

CONCLUSION

The data suggest that the excess of LB in schizophrenic patients is associated with the dysfunction of energy metabolism in LAL, and these abnormalities are related to schizophrenia.