Assessment of Complement Cascade Components in Patients With Bipolar Disorder

Ketamine's mechanism of action with an emphasis on neuroimmune regulation: can the complement system complement ketamine's antidepressant effects?

Over 300 million people worldwide suffer from major depressive disorder (MDD). Unfortunately, only 30-40% of patients with MDD achieve complete remission after conventional monoamine antidepressant therapy. In recent years, ketamine has revolutionized the treatment of MDD, with its rapid antidepressant effects manifesting within a few hours as opposed to weeks with conventional antidepressants. Many research endeavors have sought to identify ketamine's mechanism of action in mood disorders; while many studies have focused on ketamine's role in glutamatergic modulation, several studies have implicated its role in regulating neuroinflammation. The complement system is an important component of the innate immune response vital for synaptic plasticity. The complement system has been implicated in the pathophysiology of depression, and studies have shown increases in complement component 3 (C3) expression in the prefrontal cortex of suicidal individuals with depression. Given the role of the complement system in depression, ketamine and the complement system's abilities to modulate glutamatergic transmission, and our current understanding of ketamine's anti-inflammatory properties, there is reason to suspect a common link between the complement system and ketamine's mechanism of action. This review will summarize ketamine's anti- inflammatory roles in the periphery and central nervous system, with an emphasis on complement system regulation.

Increased Serum Terminal Complements Complex Levels in Attention Deficit Hyperactivity Disorder Children

Background

Attention deficit hyperactivity disorder (ADHD) is a widespread neuropsychiatric disorder in both children and adolescents, which is associated with social isolation and poor academic performance. Complement proteins are regarded as a major player in inflammation and disease development for several neuropsychiatric diseases such as schizophrenia and bipolar diseases. As clarified by previous data, increased levels of complement molecules and other immunological markers as cytokines were demonstrated in these disorders. Limited studies have investigated complement proteins particularly terminal complement complex or membrane attack complex (C5b-9) among ADHD patients. The present research aims to elucidate the association between C5b-9 complex protein and ADHD.

Methods

This is a cross-sectional study. Sera were collected from Al-Hussain Teaching Medical City in Holy Karbala, Iraq, during 2019-2020. Sera were tested for C5-b9 using commercial kits by enzyme-linked immunosorbent assay (ELISA).

Results

In 90 participants included in the study, a significant increment in C5b-9 levels among ADHD patients (P=0.019) was observed. Patients with positive C5b-9 levels had a 2.76 times higher risk of developing ADHD than control subjects. The diagnostic utility for C5b-9 was statistically significant with 71.11% sensitivity, 55.6% specificity, and a high negative predictive value (97.3%).

Conclusion

The study concluded elevation of the C5b-9 terminal complements complex levels in ADHD patients, which could point to the association of complement proteins as inflammatory markers with the ADHD disease process.

The complement system: a potential target for the comorbidity of chronic pain and depression

The mechanisms of the chronic pain and depression comorbidity have gained significant attention in recent years. The complement system, widely involved in central nervous system diseases and mediating non-specific immune mechanisms in the body, remains incompletely understood in its involvement in the comorbidity mechanisms of chronic pain and depression. This review aims to consolidate the findings from recent studies on the complement system in chronic pain and depression, proposing that it may serve as a promising shared therapeutic target for both conditions. Complement proteins C1q, C3, C5, as well as their cleavage products C3a and C5a, along with the associated receptors C3aR, CR3, and C5aR, are believed to have significant implications in the comorbid mechanism. The primary potential mechanisms encompass the involvement of the complement cascade C1q/C3-CR3 in the activation of microglia and synaptic pruning in the amygdala and hippocampus, the role of complement cascade C3/C3a-C3aR in the interaction between astrocytes and microglia, leading to synaptic pruning, and the C3a-C3aR axis and C5a-C5aR axis to trigger inflammation within the central nervous system. We focus on studies on the role of the complement system in the comorbid mechanisms of chronic pain and depression.

Roles of complement system in psychiatric disorders

The complement system is an important part of the innate immune system, including more than 50 secretory proteins and membrane-bound proteins, and it contributes to the clearance of apoptotic cells and invading pathogens to limit inflammatory immune responses and maintaining brain homeostasis. Complement activity is strictly regulated to protect cells from random attacks or to prevent the deposition of complement proteins in physiological cases. However, overactivation or abnormal regulation of the complement cascade in the brain can lead to neuronal damage and brain dysfunction. Recent studies have pointed out that changes in complement molecules exist in patients with psychiatric diseases and play an important role in the occurrence and development of diseases by regulating the function of neurons and glial cells. Therefore, summarizing the latest research progress of complement system in psychiatric diseases such as schizophrenia, autism spectrum disorder, major depression, bipolar disorder and anxiety disorder can provide new ideas for preventing and controlling psychiatric diseases caused by abnormal activation of complement system.

Association of the plasma complement system with brain volume deficits in bipolar and major depressive disorders

BACKGROUND

Inflammation plays a crucial role in the pathogenesis of major depressive disorder (MDD) and bipolar disorder (BD). This study aimed to examine whether the dysregulation of complement components contributes to brain structural defects in patients with mood disorders.

METHODS

A total of 52 BD patients, 35 MDD patients, and 53 controls were recruited. The human complement immunology assay was used to measure the levels of complement factors. Whole brain-based analysis was performed to investigate differences in gray matter volume (GMV) and cortical thickness (CT) among the BD, MDD, and control groups, and relationships were explored between neuroanatomical differences and levels of complement components.

RESULTS

GMV in the medial orbital frontal cortex (mOFC) and middle cingulum was lower in both patient groups than in controls, while the CT of the left precentral gyrus and left superior frontal gyrus were affected differently in the two disorders. Concentrations of C1q, C4, factor B, factor H, and properdin were higher in both patient groups than in controls, while concentrations of C3, C4 and factor H were significantly higher in BD than in MDD. Concentrations of C1q, factor H, and properdin showed a significant negative correlation with GMV in the mOFC at the voxel-wise level.

CONCLUSIONS

BD and MDD are associated with shared and different alterations in levels of complement factors and structural impairment in the brain. Structural defects in mOFC may be associated with elevated levels of certain complement factors, providing insight into the shared neuro-inflammatory pathogenesis of mood disorders.

Shifting levels of peripheral inflammatory profiles as an indicator for comorbid multiple autoimmune diseases and bipolar disorder: a case report

Autoimmune diseases (AID) cause inflammatory changes in the peripheral blood, which might be a predisposing factor for the development of comorbid bipolar disorder (BD). The levels of peripheral inflammatory indicators and cytokines may also serve as potential biomarkers for predicting BD susceptibility and the efficacy of antipsychotics in patients with AID. Herein, we present the case of a 43-year-old female who has suffered from AID for over 16 years and was recently diagnosed with "bipolar and related disorder due to another medical condition".

Epigenetic Alterations of Brain Non-Neuronal Cells in Major Mental Diseases

The tissue-specific expression and epigenetic dysregulation of many genes in cells derived from the postmortem brains of patients have been reported to provide a fundamental biological framework for major mental diseases such as autism, schizophrenia, bipolar disorder, and major depression. However, until recently, the impact of non-neuronal brain cells, which arises due to cell-type-specific alterations, has not been adequately scrutinized; this is because of the absence of techniques that directly evaluate their functionality. With the emergence of single-cell technologies, such as RNA sequencing (RNA-seq) and other novel techniques, various studies have now started to uncover the cell-type-specific expression and DNA methylation regulation of many genes (e.g., TREM2, MECP2, SLC1A2, TGFB2, NTRK2, S100B, KCNJ10, and HMGB1, and several complement genes such as C1q, C3, C3R, and C4) in the non-neuronal brain cells involved in the pathogenesis of mental diseases. Additionally, several lines of experimental evidence indicate that inflammation and inflammation-induced oxidative stress, as well as many insidious/latent infectious elements including the gut microbiome, alter the expression status and the epigenetic landscapes of brain non-neuronal cells. Here, we present supporting evidence highlighting the importance of the contribution of the brain's non-neuronal cells (in particular, microglia and different types of astrocytes) in the pathogenesis of mental diseases. Furthermore, we also address the potential impacts of the gut microbiome in the dysfunction of enteric and brain glia, as well as astrocytes, which, in turn, may affect neuronal functions in mental disorders. Finally, we present evidence that supports that microbiota transplantations from the affected individuals or mice provoke the corresponding disease-like behavior in the recipient mice, while specific bacterial species may have beneficial effects.

Dysregulation of complement system in neuropsychiatric disorders: A mini review

Complement system is one of the most important defense mechanisms of the innate immune system. In addition to their roles in immune regulation, complement proteins are also involved in neurodevelopment and adult brain plasticity. Complement dysregulation has been shown in neurodevelopmental disorders including schizophrenia and autism spectrum disorder as well as in mood disorders. A number of clinical as well as genetic studies suggest the role of complement proteins in the cortical thinning and excessive synaptic pruning frequently associated with schizophrenia. The changes in complement proteins are also associated with the pathophysiology of autism spectrum disorder, major depressive disorder and bipolar disorder, but warrant further research. In addition, rodent models suggest a strong case for complement system in anxiety-like behavior. In this article, we review the recent findings on the role of complement system in neuropsychiatric disorders. The possible uses for future complement targeted therapies are also discussed.

Charting the proteome landscape in major psychiatric disorders: From biomarkers to biological pathways towards drug discovery

Schizophrenia (SZ), bipolar disorder (BD), and major depressive disorder (MDD) are major mental disorders that affect a significant proportion of the global population. Advancing our knowledge of the pathophysiology of these disorders and identifying biomarkers are urgent needs for developing objective diagnostic tests and new therapeutics. In this study, we performed a systematic review and then extracted, curated, and analyzed proteomics data from published studies, aiming to assess the proteome in peripheral blood of individuals with SZ, BD, or MDD. Then, we performed pathway and network analyses to illuminate the biological themes concatenated by the differentially expressed proteins by systematically interrogating the literature to uncover biological pathways with more robust biological meaning. We identified 486 differentially expressed proteins from 51 studies across the three disorders with 9,423 participants. The great majority of pathways were common to SZ, BD, and MDD. They were related to the immune system, including signaling by interleukins, Toll-like receptor signaling pathway, and complement cascade, and to signal transduction, notably MAPK1/MAPK3 signaling, PI3K-Akt Signaling Pathway, Focal Adhesion-PI3K-Akt-mTOR-signaling, rhodopsin-like receptors, GPCR signaling, and the JAK-STAT signaling pathway. Other shared pathways included advanced glycosylation end-product receptor signaling, Regulation of Insulin-like Growth Factor, cholesterol metabolism, and IL-17 signaling pathway. Pathways shared between SZ and BD were integrin cell-surface interactions, GRB2:SOS provides linkage to MAPK signaling for integrins, and syndecan interactions. Shared between BD and MDD were the NRF2 pathway and signaling by EGFR pathways. Our findings advance our understanding of the protein variations and associations with these disorders, which are useful for accelerating biomarker development and drug discovery.

Psychopathology and Stem Cell Mobilization in Ultra-High Risk of Psychosis and First-Episode Psychosis Patients

Although regenerative and inflammatory processes are involved in the etiopathogenesis of many psychiatric disorders, their roles are poorly understood. We investigate the potential role of stem cells (SC) and factors influencing the trafficking thereof, such as complement cascade (CC) components, phospholipid substrates, and chemokines, in the etiology of schizophrenia. We measured sphingosine-1-phosphate (S1P), stromal-derived factor 1 (SDF-1), and CC cleavage fragments (C3a, C5a, and C5b-C9; also known as the membrane attack complex) in the peripheral blood of 49 unrelated patients: 9 patients with ultra-high risk of psychosis (UHR), 22 patients with first-episode psychosis (FEP), and 18 healthy controls (HC). When compared with the HC group, the UHR and FEP groups had higher levels of C3a. We found no significant differences in hematopoietic SC, very small embryonic-like stem cell (VSEL), C5a, S1P, or SDF-1 levels in the UHR and FEP groups. However, among FEP patients, there was a significant positive correlation between VSELs (CD133+) and negative symptoms. These preliminary findings support the role of the immune system and regenerative processes in the etiology of schizophrenia. To establish the relevance of SC and other factors affecting the trafficking thereof as potential biomarkers of schizophrenia, more studies on larger groups of individuals from across the disease spectrum are needed.

Systematic Review and Meta-Analysis on MS-Based Proteomics Applied to Human Peripheral Fluids to Assess Potential Biomarkers of Bipolar Disorder

Bipolar disorder (BD) is a clinically heterogeneous condition, presenting a complex underlying etiopathogenesis that is not sufficiently characterized. Without molecular biomarkers being used in the clinical environment, several large screen proteomics studies have been conducted to provide valuable molecular information. Mass spectrometry (MS)-based techniques can be a powerful tool for the identification of disease biomarkers, improving prediction and diagnosis ability. Here, we evaluate the efficacy of MS proteomics applied to human peripheral fluids to assess BD biomarkers and identify relevant networks of biological pathways. Following PRISMA guidelines, we searched for studies using MS proteomics to identify proteomic differences between BD patients and healthy controls (PROSPERO database: CRD42021264955). Fourteen articles fulfilled the inclusion criteria, allowing the identification of 266 differentially expressed proteins. Gene ontology analysis identified complement and coagulation cascades, lipid and cholesterol metabolism, and focal adhesion as the main enriched biological pathways. A meta-analysis was performed for apolipoproteins (A-I, C-III, and E); however, no significant differences were found. Although the proven ability of MS proteomics to characterize BD, there are several confounding factors contributing to the heterogeneity of the findings. In the future, we encourage the scientific community to use broader samples and validation cohorts, integrating omics with bioinformatics tools towards providing a comprehensive understanding of proteome alterations, seeking biomarkers of BD, and contributing to individualized prognosis and stratification strategies, besides aiding in the differential diagnosis.

C1q deletion exacerbates stress-induced learned helplessness behavior and induces neuroinflammation in mice

Increased levels of pro-inflammatory cytokines have been reported in postmortem brain samples and in the blood of depressed subjects. However, the inflammatory pathways that lead to depressive-like symptoms are not well understood. Using the learned helplessness (LH) model of depression, we examined the role of C1q, the initiator of classical complement pathway in mediating stress-induced depressive-like behavior in mice. We observed no significant changes in social behavior, despair behavior, spatial memory, and aggressive behavior between the wild type (WT) and C1q knockout (KO) mice. However, C1q deletion exacerbated the inescapable electric foot shock-induced learned helplessness behavior in mice. We found significant reductions in C1q mRNA levels in the prefrontal cortex (PFC) of WT helpless mice as compared to the naïve mice. Increased levels of pro-inflammatory cytokines were found in the PFC of C1q KO mice. These findings suggest that classical complement pathway-mediated learned helplessness behavior is accompanied by neuroinflammatory changes under stressful conditions.

Neuropsychiatric disorders: An immunological perspective

Neuropsychiatric diseases have traditionally been studied from brain, and mind-centric perspectives. However, mounting epidemiological and clinical evidence shows a strong correlation of neuropsychiatric manifestations with immune system activation, suggesting a likely mechanistic interaction between the immune and nervous systems in mediating neuropsychiatric disease. Indeed, immune mediators such as cytokines, antibodies, and complement proteins have been shown to affect various cellular members of the central nervous system in multitudinous ways, such as by modulating neuronal firing rates, inducing cellular apoptosis, or triggering synaptic pruning. These observations have in turn led to the exciting development of clinical therapies aiming to harness this neuro-immune interaction for the treatment of neuropsychiatric disease and symptoms. Besides the clinic, important theoretical fundamentals can be drawn from the immune system and applied to our understanding of the brain and neuropsychiatric disease. These new frameworks could lead to novel insights in the field and further potentiate the development of future therapies to treat neuropsychiatric disease.

Investigation of inflammation related gene polymorphism of the mannose-binding lectin 2 in schizophrenia and bipolar disorder

OBJECTIVES

To investigate the association between mannose-binding lectin 2 (MBL2) codon 54 polymorphism and clinical features of patients diagnosed with schizophrenia (SCZ) or bipolar disorder (BD).

METHODS

One hundred and eighteen patients with SCZ, 100 patients with BD, and 100 healthy volunteers were included in the case-control study. The patients consecutively admitted to the outpatient clinic in December 2017-May 2018 and were evaluated with some scales for clinical parameters. Polymerase chain reaction and RFLP were used to determine MBL2 polymorphism in DNA material.

RESULTS

The MBL2 gene polymorphism distributions in SCZ or BD patients were significantly different from the control group. The heterozygous genotype percentages were significantly higher in the control group than in the SCZ or BD patients (OR: 0.450; 95% Cl: 0.243-0.830; p=0.010; OR: 0.532; 95%Cl: 0.284-0.995; p=0.047, respectively), and there were statistically significant differences in the MBL2 polymorphism distributions between treatment-responsive SCZ or BD patients and treatment-resistant patients diagnosed with SCZ or BD. The heterozygous genotype percentages were also significantly higher in the treatment-responsive group than in the treatment-resistant group in SCZ or BD patients (OR: 7.857; 95% Cl: 1.006-61.363; p=0.023; OR: 8.782; 95% Cl: 1.114-69.197; p=0.016, respectively).

CONCLUSION

The presence of a heterozygous MBL2 genotype seems to be favorable both in terms of the absence of SCZ and BD in the healthy population and treatment response for Turkish patients.

Danger-associated molecular pattern molecules take unexpectedly a central stage in Nlrp3 inflammasome-caspase-1-mediated trafficking of hematopoietic stem/progenitor cells

Like their homing after transplantation to bone marrow (BM), the mobilization of hematopoietic stem/progenitor cells (HSPCs) is still not fully understood, and several overlapping pathways are involved. Several years ago our group proposed that sterile inflammation in the BM microenvironment induced by pro-mobilizing agents is a driving force in this process. In favor of our proposal, both complement cascade (ComC)-deficient and Nlrp3 inflammasome-deficient mice are poor G-CSF and AMD3100 mobilizers. It is also known that the Nlrp3 inflammasome mediates its effects by activating caspase-1, which is responsible for proteolytic activation of interleukin-1β (IL-1β) and interleukin-18 (IL-18) and their release from cells along with several danger-associated molecular pattern molecules (DAMPs). We observed in the past that IL-1β and IL-18 independently promote mobilization of HSPCs. In the current work we demonstrated that caspase-1-KO mice are poor mobilizers, and, to our surprise, administration of IL-1β or IL-18, as in the case of Nlrp3-KO animals, does not correct this defect. Moreover, neither Caspase-1-KO nor Nlrp3-KO mice properly activated the ComC to execute the mobilization process. Interestingly, mobilization in these animals and activation of the ComC were both restored after injection of the DAMP cocktail eATP+HGMB1+S100A9, the components of which are normally released from cells in an Nlrp3 inflammasome-caspase-1-dependent manner. In addition, we report that caspase-1-deficient HSPCs show a decrease in migration in response to BM homing factors and engraft more poorly after transplantation. These results for the first time identify caspase-1 as an orchestrator of HSPC trafficking.

Inflammatory signaling mechanisms in bipolar disorder

Bipolar disorder is a decidedly heterogeneous and multifactorial disease, with a high individual and societal burden. While not all patients display overt markers of elevated inflammation, significant evidence suggests that aberrant immune signaling contributes to all stages of the disease, and likely explains the elevated rates of comorbid inflammatory illnesses seen in this population. While individual systems have been intensely studied and targeted, a relative paucity of attention has been given to the interconnecting role of inflammatory signals therein. This review presents an updated overview of some of the most prominent pathophysiologic mechanisms in bipolar disorder, from mitochondrial, endoplasmic reticular, and calcium homeostasis, to purinergic, kynurenic, and hormonal/neurotransmitter signaling, showing inflammation to act as a powerful nexus between these systems. Several areas with a high degree of mechanistic convergence within this paradigm are highlighted to present promising future targets for therapeutic development and screening.

Peripheral complement proteins in schizophrenia: A systematic review and meta-analysis of serological studies

BACKGROUND

There is renewed focus on the complement system in the pathogenesis of schizophrenia. In addition to providing aetiological insights, consistently dysregulated complement proteins in serum or plasma may have clinical utility as biomarkers.

METHODS

We performed a systematic literature review searching PubMed, Embase and PsycINFO for studies measuring complement system activity or complement protein concentrations in serum or plasma from patients with schizophrenia compared to controls. Random-effects meta-analyses were performed to calculate pooled effect estimates (Hedges' g standardised mean difference [SMD]) for complement proteins whose concentrations were measured in three or more studies. The review was pre-registered on the PROSPERO database (CRD42018109012).

RESULTS

Database searching identified 1146 records. Fifty-eight full-text articles were assessed for eligibility and 24 studies included. Seven studies measured complement system activity. Activity of the classical pathway did not differ between cases and controls in four of six studies, and conflicting results were noted in two studies of alternative pathway activity. Twenty studies quantified complement protein concentrations of which complement components 3 (C3) and 4 (C4) were measured in more than three studies. Meta-analyses showed no evidence of significant differences between cases and controls for 11 studies of C3 (SMD 0.04, 95% confidence interval [CI] -0.29-0.36) and 10 studies of C4 (SMD 0.10, 95% CI -0.21-0.41).

CONCLUSIONS

Serological studies provide mixed evidence regarding dysregulation of the complement system in schizophrenia. Larger studies of a longitudinal nature, focusing on early phenotypes, could provide further insights regarding the potential role of the complement system in psychotic disorders.

ATP-Nlrp3 Inflammasome-Complement Cascade Axis in Sterile Brain Inflammation in Psychiatric Patients and its Impact on Stem Cell Trafficking

Recent evidence indicates that the occurrence of psychiatric disorders in patients is linked to a local “sterile” inflammation of brain or due to a systemic inflammation process that affects the central nervous system. This is supported by the observation that in peripheral blood of psychotic patients are detectable several mediators and markers of inflammation as well as clinical data on correlations between systemic chronic inflammatory processes and psychiatric disorders. This may explain why some reported anti-inflammatory treatment strategies have beneficial effects on ameliorating psychotic events. In this review we will present a concept that aberrant purinergic signaling and increases in extracellular level of adenosine triphosphate (ATP) in the brain parenchyma may lead to activation of Nlrp3 inflammasome in microglia cells and as a consequence microglia released danger associated molecular pattern (DAMP) proteins activate complement cascade (ComC) in mannan binding lectin (MBL) – dependent manner. Activation of ATP-Nlrp3 inflammasome-ComC axis may also orchestrate trafficking of stem cells released from bone marrow into peripheral blood observed in psychotic patients. Based on this, the ATP-Nlrp3 inflammasome-ComC axis may become a target for new therapeutic approaches, which justifies the development and clinical application of efficient anti-inflammatory treatment strategies targeting this axis in psychiatry.

Markers of Regenerative Processes in Patients with Bipolar Disorder: A Case-control Study

Progress in medical science has allowed the discovery of many factors affecting the pathogenesis of bipolar disorder, and among the most recent research directions are found regenerative and inflammatory processes. The role of regenerative processes remains particularly poorly explored, but available data encourage further research, which may explain the pathogenesis of bipolar disorder (BD). The aim of this study was to evaluate the mobilization of stem cells into peripheral blood, in patients with bipolar disorder during stable phase, not treated with lithium salts. The study included 30 unrelated individuals with the diagnosis of bipolar disorder, with disease duration of at least 10 years, not treated with lithium salts for at least five years prior to the study. The control group consisted of 30 healthy subjects, matched for age, sex, body mass index (BMI), origin, socio-demographic factors and nicotine use. Blood samples underwent cytometric analyses to assess concentrations of: Very Small Embryonic Like (VSEL) CD34+, VSEL AC133+, HSC CD34+, HSC AC133+. There were no significant differences in stem cell levels between patients with BD and healthy controls. However, the level of VSEL cells AC133 + was significantly higher in type I BD patients compared to healthy controls. Our results indicate a disturbance in regenerative processes in patients with bipolar disorder.

Complement Activation in 22q11.2 Deletion Syndrome

The 22q11.2 deletion syndrome (22q11.2 del), also known as DiGeorge syndrome, is a genetic disorder with an estimated incidence of 1:3000 to 1:6000 births. These patients may suffer from affection of many organ systems with cardiac malformations, immunodeficiency, hypoparathyroidism, autoimmunity, palate anomalies, and psychiatric disorders being the most frequent. The importance of the complement system in 22q11.2 del has not been investigated. The objective of this study was to evaluate the complement system in relation to clinical and immunological parameters in patients. A national cohort of patients (n = 69) with a proven heterozygous deletion of chromosome 22q11.2 and a group of age and sex matched controls (n = 56) were studied. Functional capacity of the classical, lectin, and alternative pathways of the complement system as well as complement activation products C3bc and terminal complement complex (TCC) were accessed and correlated to clinical features. All patients in our study had normal complement activation in both classical and alternative pathways. The frequency of mannose-binding lectin deficiency was comparable to the normal population. The patients had significantly raised plasma levels of C3bc and a slight, but not significant, increase in TCC compared with controls. This increase was associated with the presence of psychiatric disorders in patients. The present study shows no complement deficiencies in 22q11.2 deletion syndrome. On the contrary, there are signs of increased complement activation in these patients. Complement activation is particularly associated with the presence of psychiatric disorders.

Stem Cells in Psychiatry

The development of regenerative medicine has provided new perspectives in many scientific fields, including psychiatry. Stem cell research is getting us closer to discovering the biological foundation of mental disorders. In this chapter, we consider the information relating to stem cells and factors involved in their trafficking in peripheral blood in some psychiatric disorders (major depressive disorder, bipolar disorder, schizophrenia, anxiety disorder, and alcohol dependence). The authors also include the implementation of current research regarding neurogenesis in adult brain and induced pluripotent stem cells in investigating concerns in etiopathogenesis of mental disorders as well as the implication of research for treatment of these disorders.