A randomised clinical trial of methotrexate points to possible efficacy and adaptive immune dysfunction in psychosis

Efficacy and safety of drugs for psoriasis patients with mental disorders: A systematic review

BACKGROUND

The emergence of biological agents and small molecule drugs has revolutionized the treatment landscape for psoriasis, yet there remains a lack of systematic reviews elucidating the efficacy and safety of drugs for patients with psoriasis and mental disorders (MDs). The aim was to systemically evaluate the efficacy and safety of FDA-approved psoriasis drugs on MD symptoms and MD drugs on psoriasis symptoms.

METHODS

We conducted comprehensive literature searches of the PubMed, Embase, and Cochrane Library from inception to March 24, 2024, identifying 116 relevant studies for inclusion.

RESULTS

Our review encompasses 62 clinical trials and 54 case reports/series. Analyses of clinical trials revealed a positive impact of psoriasis drugs on MD, with notable exceptions including lithium and benzodiazepine receptor agonists, which exhibited adverse effects on psoriasis. Furthermore, analysis of case reports/series highlighted the efficacy of drugs such as apremilast, etanercept, infliximab, and secukinumab in ameliorating MD symptoms, contrasting with detrimental effects observed with methotrexate (MTX), cyclosporine, adalimumab, and secukinumab. Notably, tumor necrosis factor alpha (TNF-α) inhibitors and interleukin inhibitors demonstrated superior efficacy compared to conventional treatments. In the anxiety group, secukinumab showed the largest effective size as assessed by the Hospital Anxiety and Depression Scale - Anxiety (HADS-A) index; In the depression group, ixekizumab showed the largest effective size assessed by the 16-item Quick Inventory of Depressive Symptomology - Self-Report (QIDS-SR16) index.

LIMITATIONS

The extracted data cannot be meta-analyzed, as the measurement scale is not uniform.

CONCLUSIONS

This systematic review provides robust evidence regarding treatment options for individuals with psoriasis and MD, emphasizing the potential benefits of specific drugs in managing both conditions concurrently.

Protein Profiles and Novel Molecular Biomarkers of Schizophrenia Based on 4D-DIA Proteomics

Schizophrenia is a severe psychological disorder. The current diagnosis mainly relies on clinical symptoms and lacks laboratory evidence, which makes it very difficult to make an accurate diagnosis especially at an early stage. Plasma protein profiles of schizophrenia patients were obtained and compared with healthy controls using 4D-DIA proteomics technology. Furthermore, 79 DEPs were identified between schizophrenia and healthy controls. GO functional analysis indicated that DEPs were predominantly associated with responses to toxic substances and platelet aggregation, suggesting the presence of metabolic and immune dysregulation in patients with schizophrenia. KEGG pathway enrichment analysis revealed that DEPs were primarily enriched in the chemokine signaling pathway and cytokine receptor interactions. A diagnostic model was ultimately established, comprising three proteins, namely, PFN1, GAPDH and ACTBL2. This model demonstrated an AUC value of 0.972, indicating its effectiveness in accurately identifying schizophrenia. PFN1, GAPDH and ACTBL2 exhibit potential as biomarkers for the early detection of schizophrenia. The findings of our studies provide novel insights into the laboratory-based diagnosis of schizophrenia.

The expression of immune related genes and potential regulatory mechanisms in schizophrenia

OBJECTIVE

This study aimed to investigate the role of immune dysfunction in the pathogenesis of schizophrenia through single-cell transcriptome and bulk RNA data analyses.

METHODS

The single-cell RNA sequencing (scRNA-seq) was selected to assess the cellular composition and gene expression profiles of the brain tissue. Further, bulk RNA sequencing data was utilized to corroborate findings from the single-cell analyses and provide additional insights into the molecular changes associated with the disease. Gene-drug interaction data was also included to identify potential therapeutic drugs targeting these dysregulated immune-related genes in schizophrenia.

RESULTS

We discovered significant differences in cellular composition within schizophrenia tissue, including increased infiltration of fibroblasts, horizontal basal cells, monocytes, mesenchymal cells, and smooth muscle cells. The investigation of immune-related genes revealed significantly different expression of genes such as S100A2, CCL14, IGHA1, BPIFA1, GDF15, IL32, BPIFB2, HLA-DRA, S100A8, PTX3, TPM2, TNFRSF12A, GREM1 and others. These genes possibly contribute to the progression of schizophrenia through various pathways such as humoral immune response, IL-17 signaling pathway, adaptive immune response, antigen processing and presentation, and gut IgA production. Our findings also suggest possible transcriptional regulation in schizophrenia's immune dysfunction by transcription factors in monocytes, neutrophils, endothelial cells, and epithelial cells. Lastly, potential therapeutic drugs were identified through gene-drug interaction data, such as those targeting HLA-A and HLAB.

CONCLUSION

The cellular heterogeneity and immune-related gene dysregulation play important roles in schizophrenia, which provides a foundation for understanding the pathogenesis and developing new treatment methods.

Add-on Sodium Benzoate and N-Acetylcysteine in Patients With Early Schizophrenia Spectrum Disorder: A Multicenter, Double-Blind, Randomized Placebo-Controlled Feasibility Trial

Background and Hypothesis

Oxidative stress pathways may play a role in schizophrenia through direct neuropathic actions, microglial activation, inflammation, and by interfering with NMDA neurotransmission. N-acetylcysteine (NAC) has been shown to improve negative symptoms of schizophrenia, however, results from trials of other compounds targeting NMDA neurotransmission have been mixed. This may reflect poor target engagement but also that risk mechanisms act in parallel. Sodium Benzoate (NaB) could have an additive with NAC to act on several pathophysiological mechanisms implicated in schizophrenia.

Study Design

A multicenter, 12 weeks, 2 × 2 factorial design, randomized double-blind placebo-controlled feasibility trial of NaB and NAC added to standard treatment in 68 adults with early schizophrenia. Primary feasibility outcomes included recruitment, retention, and completion of assessments as well as acceptability of the study interventions. Psychosis symptoms, functioning, and cognitive assessments were also assessed.

Study Results

We recruited our desired sample (n = 68) and retained 78% (n = 53) at 12 weeks, supporting the feasibility of recruitment and retention. There were no difficulties in completing clinical outcome schedules. Medications were well tolerated with no dropouts due to side effects. This study was not powered to detect clinical effect and as expected no main effects were found on the majority of clinical outcomes.

Conclusions

We demonstrated feasibility of conducting a clinical trial of NaB and NAC. Given the preliminary nature of this study, we cannot draw firm conclusions about the clinical efficacy of either agent, and a large-scale trial is needed to examine if significant differences between treatment groups emerge.

Trial Registration

ClinicalTrials.gov: NCT03510741.

Novel pharmacotherapy targeting the positive symptoms of schizophrenia

INTRODUCTION

The severity of positive symptoms in schizophrenia is associated with poor prognosis. About one-third of schizophrenia patients partially respond to treatment with available antipsychotics. The purpose of the present manuscript is to provide an updated overview of novel pharmacotherapy targeting positive symptoms in schizophrenia.

AREAS COVERED

A comprehensive research on the main database sources (PubMed, PsychINFO, Isi Web of Knowledge, MEDLINE, and EMBASE) was performed to obtain original articles published till 31st January 2023 about new pharmacological strategies for the treatment of positive symptoms in schizophrenia.

EXPERT OPINION

The most promising compounds include: lamotrigine, pro-cognitive-compounds (donepezil - in the short term, idazoxan and piracetam) and drugs acting partially or totally outside the Central Nervous System (CNS) (anti-inflammatory drugs: celecoxib, methotrexate; cardiovascular compounds: L-theanine, mononitrate isosorbide, propentofylline, sodium nitroprusside; metabolic regulators: diazoxide, allopurinol; others: bexarotene, raloxifene [in women]). The effectiveness of the latter compounds indicates that other biological systems, such as immunity or metabolism can be object of future research to identify pharmacological targets for positive symptoms of schizophrenia. Mirtazapine could be useful for treating negative symptoms without increasing the risk of a worsening of delusions/hallucinations. Nevertheless, the lack of replication of studies prevents to draw definitive conclusions and future studies are needed to confirm the findings presented in this overview.

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.

Immune System and Brain/Intestinal Barrier Functions in Psychiatric Diseases: Is Sphingosine-1-Phosphate at the Helm?

Over the past few decades, extensive research has shed light on immune alterations and the significance of dysfunctional biological barriers in psychiatric disorders. The leaky gut phenomenon, intimately linked to the integrity of both brain and intestinal barriers, may play a crucial role in the origin of peripheral and central inflammation in these pathologies. Sphingosine-1-phosphate (S1P) is a bioactive lipid that regulates both the immune response and the permeability of biological barriers. Notably, S1P-based drugs, such as fingolimod and ozanimod, have received approval for treating multiple sclerosis, an autoimmune disease of the central nervous system (CNS), and ulcerative colitis, an inflammatory condition of the colon, respectively. Although the precise mechanisms of action are still under investigation, the effectiveness of S1P-based drugs in treating these pathologies sparks a debate on extending their use in psychiatry. This comprehensive review aims to delve into the molecular mechanisms through which S1P modulates the immune system and brain/intestinal barrier functions. Furthermore, it will specifically focus on psychiatric diseases, with the primary objective of uncovering the potential of innovative therapies based on S1P signaling.

Regulatory T cells mediate insomnia-related psychotic symptoms and cognitive impairment in chronic schizophrenia patients

Insomnia occurs frequently in schizophrenia patients and is often accompanied with severe psychotic symptoms and cognition impairment. Moreover, chronic insomnia is associated with immune alterations. This study explored the correlations between insomnia and clinical manifestations of schizophrenia and analyzed mediation effects of regulatory T cells (Tregs) on these correlations. In a total of 655 chronic schizophrenia patients, 70 persons (10.69%) had an ISI (Insomnia Severity Index) score >7 and were referred to as Insomnia group. Compared to non-Insomnia group, Insomnia group presented more severe psychotic symptoms (assessed by PANSS) and cognitive impairment (assessed by RBANS). The total effect of ISI on PANSS/RBANS total score was not significant due to the mediation effects by Tregs, in which Tregs strongly mediated the effect of ISI on PANSS total score in negative direction but mediated the effect of ISI on RBANS total score in positive direction. Pearson Correlation Coefficient revealed negative correlations between Tregs and PANSS total score or disorganization subscale of PANSS. Positive correlations existed between Tregs and RBANS total score, between Tregs and the subscales of attention, delayed memory, or language of RBANS. These mediation effects of Tregs on insomnia-related psychotic symptoms and cognitive impairment in chronic schizophrenia patients point to a potential therapeutic strategy of modulating Tregs for the patients.

Is It Time for a Paradigm Shift in the Treatment of Schizophrenia? The Use of Inflammation-Reducing and Neuroprotective Drugs-A Review

Comprehending the pathogenesis of schizophrenia represents a challenge for global mental health. To date, although it is evident that alterations in dopaminergic, serotonergic, and glutamatergic neurotransmission underlie the clinical expressiveness of the disease, neuronal disconnections represent only an epiphenomenon. In recent years, several clinical studies have converged on the hypothesis of microglia hyperactivation and a consequent neuroinflammatory state as a pathogenic substrate of schizophrenia. Prenatal, perinatal, and postnatal factors can cause microglia to switch from M2 anti-inflammatory to M1 pro-inflammatory states. A continuous mild neuroinflammatory state progressively leads to neuronal loss, a reduction in dendritic spines, and myelin degeneration. The augmentation of drugs that reduce neuroinflammation to antipsychotics could be an effective therapeutic modality in managing schizophrenia. This review will consider studies in which drugs with anti-inflammatory and neuroprotective properties have been used in addition to antipsychotic treatment in patients with schizophrenia.

A new era for schizophrenia drug development - Lessons for the future

For many patients and their treating clinicians, the pharmacological management of psychotic symptoms centres on trying to find a regime that balances efficacy and quality of life, impairing side effects associated with dopamine antagonism. Recent reports of a positive Phase III study from Karuna Therapeutics indicate that the first primarily non-dopamine-based treatment for schizophrenia may come to market soon with the potential for substantially reduced or differentiated side effects. Against a background of repeated failures, Karuna's success promises a desperately needed new treatment option for patients. It also reflects some hard-won lessons about the methodology for schizophrenia drug development. Teaser A positive Phase II study and positive media report from a Phase III study with xanomeline/trospium may herald the first truly new treatment option for schizophrenia patients in decades. This drug's journey to this point reflects some hard-won lessons about the methodology for schizophrenia drug development.

The association between schizophrenia and white blood cells count: a bidirectional two-sample Mendelian randomization study

BACKGROUND

Positive associations between the risk of schizophrenia and the level of white blood cells (WBC) count have been suggested by observational studies. However, the causality of this association is still unclear.

METHODS

We used a group of bidirectional two-sample Mendelian randomization (MR) analyses to estimate the causal relationship between schizophrenia and WBC count traits (i.e., WBC count, lymphocyte count, neutrophil count, basophil count, eosinophil count, and monocyte count). The threshold of FDR-adjusted P < 0.05 was considered as showing potential evidence of a causal effect. Instrument variables were included based on the genome-wide significance threshold (P < 5 × 10^- 8) and linkage disequilibrium (LD) clumping (r² < 0.01). In total, 81, 95, 85, 87, 76, and 83 schizophrenia-related single nucleotide polymorphisms (SNPs) were used as genetic instruments from Psychiatric Genomics Consortium for six WBC count traits, respectively. And in reverse MR analysis, 458, 206, 408, 468, 473, and 390 variants extracted from six WBC count traits were utilized as genetic instruments, which were obtained from a recent large-scale Genome-Wide Association Study (GWAS).

RESULTS

Genetically predicted schizophrenia was positively associated with the level of WBC count [odds ratio (OR) 1.017, 95% confidence interval (CI) 1.008-1.026; P = 7.53 × 10^- 4], basophil count (OR 1.014, 95%CI 1.005-1.022; P = 0.002), eosinophil count (OR 1.021, 95%CI 1.011-1.031; P = 2.77 × 10^- 4), monocyte count (OR 1.018, 95%CI 1.009-1.027; P = 4.60 × 10^- 4), lymphocyte count (OR 1.021, 95%CI 1.012-1.030; P = 4.51 × 10^- 5), and neutrophil count (OR 1.013, 95%CI 1.005-1.022; P = 0.004). WBC count traits are not associated with the risk of schizophrenia in our reverse MR results.

CONCLUSION

Schizophrenia is associated with elevated levels of WBC count (i.e., higher WBC count, lymphocyte count, neutrophil count, basophil count, eosinophil count, and monocyte count).

Anti-inflammatory medications for the treatment of mental disorders: A scoping review

This scoping review assessed the effect of anti-inflammatory medications in mental disorders. A search in Medline and the Cochrane database focusing on randomised controlled trials and systematic reviews identified 53 primary research articles, conducted in major depression, bipolar disorder, schizophrenia and somatic symptom disorders and related disorders (SSRD). The findings suggest that there is scope to consider the use of anti-inflammatory agents in mental disorders, however, not as a one-size-fits-all solution. Treatment could be especially helpful in subgroups with evidence of baseline inflammation. Anti-inflammatory medications that seem mostly effective in bipolar disorder or major depressive disorder, such as Celecoxib, Pioglitazone and statins, may differ from the ones with indications of effectiveness in schizophrenia, such as Minocycline and Aspirin. This might suggest a different underlying mechanism for treatment success in those two main illness groups. Further studies with larger sample sizes are needed that take levels of inflammation markers into account.

The Interrelation between Interleukin-2 and Schizophrenia

Interleukin-2 (IL-2) is a growth factor that regulates T-cell autocrine secretion and has long been considered to be closely related to immune response. With the advance in neuroinflammation theory and immunology research on schizophrenia, it is interesting and meaningful to discuss the possible role of IL-2 in schizophrenia. Here, we reviewed a series of studies published from the 1990s and found that IL-2 was closely associated with schizophrenia. For example, IL-2 is responsible for mediating toxic reactions, which are the causes of schizophrenia symptoms in patients, and such symptoms resolve after discontinuation of the drug. In addition, we focused on the changes of IL-2 in the onset, progression and treatment of schizophrenia and the possible mechanisms by which IL-2 affects schizophrenia. Our review suggests that IL-2 is associated with schizophrenia and plays a role in its pathogenesis, and progression IL-2 and sIL-2R could serve as potential biomarkers of schizophrenia.

Associations between psoriasis and mental illness: an update for clinicians

OBJECTIVE

This review explores the association between psoriasis and mental illness and the potential underlying pathophysiologic explanations for this association.

METHOD

Using a search via the MEDLINE database in December 2020, eligible studies with a focus on systematic reviews, meta-analyses, and randomized control trials (RCTs) were retrieved and reviewed.

RESULTS

Psoriasis patients are 1.5 times more likely to show depressive symptoms and experience a higher prevalence of anxiety symptoms (20-50%) than individuals without psoriasis. Schizophrenia (2.82%) and suicidal ideation (12.7%) are found to be more prevalent among psoriasis patients than among the general population. Pro-inflammatory markers, which play an important role in the pathophysiology of psoriasis, have been shown to be elevated in patients with depression, anxiety, and schizophrenia; this suggests shared inflammatory pathways may be involved.

CONCLUSIONS

There is an elevated burden of psychiatric co-morbidity in psoriasis patients which may be explained by an inflammatory model. We recommend that clinicians conduct universal screening of depression, anxiety, and suicidality among their psoriasis patients and remain vigilant for any symptoms of severe psychiatric conditions such as schizophrenia. Collaboration between dermatologists, psychiatrists and primary care physicians is essential in supporting psychological wellbeing and clinical outcomes for psoriasis patients.

The evolution of knowledge on genes associated with human diseases

Thousands of biomedical scientific articles, including those describing genes associated with human diseases, are published every week. Computational methods such as text mining and machine learning algorithms are now able to automatically detect these associations. In this study, we used a cognitive computing text-mining application to construct a knowledge network comprising 3,723 genes and 99 diseases. We then tracked the yearly changes on these networks to analyze how our knowledge has evolved in the past 30 years. Our systems approach helped to unravel the molecular bases of diseases and detect shared mechanisms between clinically distinct diseases. It also revealed that multi-purpose therapeutic drugs target genes that are commonly associated with several psychiatric, inflammatory, or infectious disorders. By navigating this knowledge tsunami, we were able to extract relevant biological information and insights about human diseases.

Antipsychotic-induced gastrointestinal hypomotility and the alteration in gut microbiota in patients with schizophrenia

AIM

Gut microbiota play an important role in the pathogenesis of gut hypomotility and are critical for the production of the intestinal immune system and the maintenance of the intestinal homeostasis. Patients with psychotic disorders are at a high risk of antipsychotic-induced constipation. However, the mechanisms might be more than neurotransmission properties of antipsychotics.

METHODS

We recruited a total of 45 patients with constipation according to Rome IV criteria and objective test for colonic motility and the other 45 gender- and age-matching patients without constipation and investigated their differences in composition of gut microbiota. The demographic and serum metabolic indices were collected. The subjective constipation assessment scale (CAS) and the Bristol stool classification (BSS) were also used to evaluate the degree of constipation in both groups. The fecal samples were analysed using the 16S rRNA gene sequencing.

RESULTS

The constipation group had a significantly increased alpha diversity in Observed species, Chao 1, and ACE as compared to the non-constipation group. At the phylum levels, the relative abundances of Bacteroidetes and Fusobacteria decreased significantly, while those of Firmicutes, Verrucomicrobia, and Synergistetes increased significantly in the constipation group. At the genus level, the relative abundances of Christensenella and Desulfovibrio were higher in the constipation group. The α-diversity indices of gut microbiota were correlated positively with the levels of serum total bile acid and correlated negatively with BSS scores. The BSS scores were positively correlated with the relative abundance of Bacteroidetes but negatively correlated with the relative abundance of Firmicutes. PICRUSt analysis revealed the potential metabolic pathways of lipopolysaccharide, vitamin B6, riboflavin, pyruvate, and propionate functions.

CONCLUSIONS

The alternation of the gut microbiota in schizophrenia patients with antipsychotic-induced constipation indicates antipsychotic agents might affect gastrointestinal motility via varying microbiome-related metabolites, and the specific bacteria, such as Synergistetes which might act as an anti-inflammatory factor in the healthy human gut, related to colonic transit motility seem inconsistent to the findings from previous literature in gastroenterology. However, the causal effects are still unknown. Our study provides a new possibility to understand the mechanisms of antipsychotic-induced constipation.

T regulatory cells as a potential therapeutic target in psychosis? Current challenges and future perspectives

Many studies have reported that patients with psychosis, even before drug treatment, have mildly raised levels of blood cytokines relative to healthy controls. In contrast, there is a remarkable scarcity of studies investigating the cellular basis of immune function and cytokine changes in psychosis. The few flow-cytometry studies have been limited to counting the proportion of the major classes of monocyte and lymphocytes without distinguishing their pro- and anti-inflammatory subsets. Moreover, most of the investigations are cross-sectional and conducted with patients on long-term medication. These features make it difficult to eliminate confounding of illness-related changes by lifestyle factors, disease duration, and long exposure to antipsychotics. This article focuses on regulatory T cells (Tregs), cornerstone immune cells that regulate innate and adaptive immune forces and neuro-immune interactions between astrocytes and microglia. Tregs are also implicated in cardio-metabolic disorders that are common comorbidities of psychosis. We have recently proposed that Tregs are hypofunctional ('h-Tregs') in psychosis driven by our clinical findings and other independent research. Our h-Treg-glial imbalance hypothesis offers a new account for the co-occurrence of systemic immune dysregulation and mechanisms of psychosis development. This article extends our recent review, the h-Treg hypothesis, to cover new discoveries on Treg-based therapies from pre-clinical findings and their clinical implications. We provide a detailed characterisation of Treg studies in psychosis, identifying important methodological limitations and perspectives for scientific innovation. The outcomes presented in this article reaffirms our proposed h-Treg state in psychosis and reveals emerging preclinical research suggesting the potential benefit of Treg-enhancing therapies. There is a clear need for longitudinal studies conducted with drug-naïve or minimally treated patients using more sophisticated techniques of flow-cytometry, CyTOF expression markers, and in vitro co-culture assays to formally test the suppressive capacity of Tregs. Investment in Treg research offers major potential benefits in targeting emerging immunomodulatory treatment modalities on person-specific immune dysregulations.

Depression and suicidal ideation in schizophrenia spectrum disorder: a cross-sectional study from a lower middle-income country

OBJECTIVES

Depression has long been considered a significant feature of schizophrenia and is associated with more frequent psychotic episodes, increased service utilisation, substance misuse, poor quality of life and completed suicide. However, there is a distinct lack of literature on this comorbidity from low- and middle-income countries or non-western cultural backgrounds.

METHODS

This is a cross-sectional analysis of baseline data from a large randomised controlled trial, examining the prevalence of depression and suicidal ideation in patients with schizophrenia spectrum disorder. A total of 298 participants were recruited from inpatient and outpatient psychiatric units in Karachi, Pakistan. Participants completed the Calgary Depression Scale for Schizophrenia (CDSS), Positive and Negative Syndrome Scale (PANSS), Euro Qol (EQ-5D) and Social Functioning Scale (SFS).

RESULTS

Data indicate that 36% of participants in the study were depressed and 18% endorsed suicidal ideation. Depression was associated with higher positive symptom scores and reduced quality of life, but no significant difference in negative symptoms and social functioning.

CONCLUSIONS

Depression and suicidal ideation are prevalent in Pakistani patients diagnosed with schizophrenia spectrum disorder. Evaluation of depressive symptoms in this group may help identify individuals at higher risk of completed suicide, allowing for targeted interventions to improve outcomes.Key pointsTo our knowledge, this is the first study describing the prevalence of depression and suicidal ideation in individuals with schizophrenia from Pakistan.Our data indicate that 36% of individuals with schizophrenia in our sample were depressed and 18% endorsed suicidal ideation.Depression in schizophrenia was associated with poorer quality of life and higher positive symptom burden.This study adds to the scarce literature from low- and middle-income countries where the burden of mental illness is great and where the majority of suicide deaths occur.Addressing social inequality, food insecurity, high rates of unemployment and low levels of literacy in these settings may have a profound effect on population mental health and suicide risk.

Repurposing Immunomodulatory Imide Drugs (IMiDs) in Neuropsychiatric and Neurodegenerative Disorders

Neuroinflammation represents a common trait in the pathology and progression of the major psychiatric and neurodegenerative disorders. Neuropsychiatric disorders have emerged as a global crisis, affecting 1 in 4 people, while neurological disorders are the second leading cause of death in the elderly population worldwide (WHO, 2001; GBD 2016 Neurology Collaborators, 2019). However, there remains an immense deficit in availability of effective drug treatments for most neurological disorders. In fact, for disorders such as depression, placebos and behavioral therapies have equal effectiveness as antidepressants. For neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease, drugs that can prevent, slow, or cure the disease have yet to be found. Several non-traditional avenues of drug target identification have emerged with ongoing neurological disease research to meet the need for novel and efficacious treatments. Of these novel avenues is that of neuroinflammation, which has been found to be involved in the progression and pathology of many of the leading neurological disorders. Neuroinflammation is characterized by glial inflammatory factors in certain stages of neurological disorders. Although the meta-analyses have provided evidence of genetic/proteomic upregulation of inflammatory factors in certain stages of neurological disorders. Although the mechanisms underpinning the connections between neuroinflammation and neurological disorders are unclear, and meta-analysis results have shown high sensitivity to factors such as disorder severity and sample type, there is significant evidence of neuroinflammation associations across neurological disorders. In this review, we summarize the role of neuroinflammation in psychiatric disorders such as major depressive disorder, generalized anxiety disorder, post-traumatic stress disorder, and bipolar disorder, as well as in neurodegenerative disorders, such as Parkinson's disease and Alzheimer's disease, and introduce current research on the potential of immunomodulatory imide drugs (IMiDs) as a new treatment strategy for these disorders.

Impaired regulatory T cell control of astroglial overdrive and microglial pruning in schizophrenia

It is widely held that schizophrenia involves an active process of peripheral inflammation that induces or reflects brain inflammation with activation of microglia, the brain's resident immune cells. However, recent in vivo radioligand binding studies and large-scale transcriptomics in post-mortem brain report reduced markers of microglial inflammation. The findings suggest a contrary hypothesis; that microglia are diverted into their non-inflammatory synaptic remodelling phenotype that interferes with neurodevelopment and perhaps contributes to the relapsing nature of schizophrenia. Recent discoveries on the regulatory interactions between micro- and astroglial cells and immune regulatory T cells (Tregs) cohere with clinical omics data to suggest that: i) disinhibited astrocytes mediate the shift in microglial phenotype via the production of transforming growth factor-beta, which also contributes to the disturbances of dopamine and GABA function in schizophrenia, and ii) systemically impaired functioning of Treg cells contributes to the dysregulation of glial function, the low-grade peripheral inflammation, and the hitherto unexplained predisposition to auto-immunity and reduced life-expectancy in schizophrenia, including greater COVID-19 mortality.

Monocyte Transcriptional Profiling Highlights a Shift in Immune Signatures Over the Course of Illness in Schizophrenia

With advanced understanding of the intricate interplay between the immune and central nervous systems in neurological and neuropsychiatric illness, there is renewed interest in the potential contribution of immune dysregulation to the development and progression of schizophrenia. To inform this line of inquiry requires a more nuanced understanding of specific immune changes throughout the course of illness. Here, we utilized a genome-wide sequencing approach to transcriptionally profile circulating monocytes in participants with chronic schizophrenia. These myeloid cells, isolated from whole blood samples, are highly plastic with potentially important disease-modifying functions. Differential gene expression and gene set enrichment analyses, focusing on established monocyte phenotypic signatures, including those related to proinflammatory ("M1-like") and protective or tissue remodeling ("M2-like") functions, were carried out. We demonstrate an overall enrichment of both "M1-like" (interferon-alpha, interferon-gamma, lipopolysaccharide acute) and "M2-like" (endotoxin tolerance, glucocorticoid acute) monocyte signatures in the participants with schizophrenia compared to non-psychiatric controls. There was no enrichment of the "M1-like" chronic stress signature or the "M2-like" interleukin-4 signature. Using the Molecular Signatures Database Hallmark gene sets list, the "interferon response" was most strongly enriched in schizophrenia compared to controls. Additionally, an exploratory subgroup analysis based on illness duration suggests a shift in monocyte phenotype with illness progression. Specifically, the "M1-like" interferon-gamma signature shows decreased enrichment accompanied by increased enrichment of opposing "M2-like" signatures in participants with a medium illness duration shifting to a strong enrichment of interferon response signatures only in participants with a long illness duration. These findings related to circulating immune cell phenotype have potentially important implications for understanding the role of immune dysregulation in schizophrenia and are a critical consideration for future study design and immune-targeting treatment strategies.