Minocycline supplementation for treatment of negative symptoms in early-phase schizophrenia: a double blind, randomized, controlled trial

Biological significance and pathophysiological role of Matrix Metalloproteinases in the Central Nervous System

Matrix Metalloproteinases (MMPs), which are endopeptidase reliant on zinc, are low in embryonic tissues but increases in response to a variety of physiological stimulus and pathological stresses. Neuro-glial cells, endothelial cells, fibroblasts, and leucocytes secrete MMPs, which cleave extracellular matrix proteins in a time-dependent manner. MMPs affect synaptic plasticity and the development of short-term memory by controlling the size, shape, and excitatory synapses' function through the lateral diffusion of receptors. In addition, MMPs influence the Extracellular Matrix proteins in the Peri-Neuronal Net at the Neuro-glial interface, which aids in the establishment of long-term memory. Through modulating neuronal, and glial cells migration, differentiation, Neurogenesis, and survival, MMPs impact brain development in mammals. In adult brains, MMPs play a beneficial role in physiological plasticity, which includes learning, memory consolidation, social interaction, and complex behaviors, by proteolytically altering a wide variety of factors, including growth factors, cytokines, receptors, DNA repair enzymes, and matrix proteins. Additionally, stress, depression, addiction, hepatic encephalopathy, and stroke may all have negative effects on MMPs. In addition to their role in glioblastoma development, MMPs influence neurological diseases such as epilepsy, schizophrenia, autism spectrum disorder, brain damage, pain, neurodegeneration, and Alzheimer's and Parkinson's. To help shed light on the potential of MMPs as a therapeutic target for neurodegenerative diseases, this review summarizes their regulation, mode of action, and participation in brain physiological plasticity and pathological damage. Finally, by employing different MMP-based nanotools and inhibitors, MMPs may also be utilized to map the anatomical and functional connectome of the brain, analyze its secretome, and treat neurodegenerative illnesses.

Relationship between blood-based inflammatory indices and clinical score of schizophrenia patients: A cross-sectional study

Schizophrenia is a severe mental disorder that may involve inflammation. Inflammatory indices, such as the neutrophil to lymphocyte ratio (NLR), the monocyte to lymphocyte ratio (MLR), the platelet to lymphocyte ratio (PLR), and the systemic inflammation index (SII), are simple and inexpensive measures of inflammation that have been associated with various diseases. However, few studies have compared these indices and their relationships with clinical symptoms in schizophrenia. We conducted a cross-sectional study of 121 schizophrenia patients (101 males, 20 females). We measured the blood-based inflammatory indices (NLR, MLR, PLR, and SII) and assessed the clinical symptoms of schizophrenia using the Positive and Negative Syndrome Scale (PANSS). Statistical analyses were performed to examine the correlations and effects of the inflammatory indices on PANSS scores. We found that NLR, MLR, PLR, and SII were positively correlated with PANSS total score, PANSS positive score, PANSS negative score, and general psychopathology score (adjusted P < 0.02 for all correlations). Subgroup analysis showed that correlations between inflammatory indices and the clinical scores differed by gender. In males, all inflammatory indices were positively correlated with all clinical scores. On the other hand, in females, only NLR and SII were positively correlated with all clinical scores. After adjusting for confounders, we also found that NLR was a predictor of PANSS total score (β = 23, adjusted P < 0.02), PANSS positive score (β = 2.6, adjusted P = 0.03), PANSS negative score (β = 6.8, adjusted P < 0.02), and PANSS general psychopathology score (β = 13.6, adjusted P < 0.02), while SII was only a predictor for PANSS total score (β = -0.00003, adjusted P = 0.01) and general psychopathology scores (β = -0.00002, adjusted P < 0.02). These findings suggest that inflammation is involved in the pathophysiology and clinical manifestations of schizophrenia, and that blood-based inflammatory indices may serve as screening tools or indicators for the inflammatory status and severity of symptoms of schizophrenia patients.

Pharmacological management of neurocognitive impairment in schizophrenia: A narrative review

BACKGROUND

Cognitive impairment are among the core features of schizophrenia, experienced by up to 75% of patients. Available treatment options for schizophrenia including dopamine antagonists and traditional antipsychotic medications have not been shown to confer significant benefits on cognitive deficits. Contrary to the focus on management of positive symptoms in schizophrenia, cognitive abilities are main predictor of independent living skills, functional abilities, employment, engagement in relapse prevention, and patients' subjective sense of well-being and quality of life. This review aims to provide a summary of recent literature on pharmacological options for the treatment of cognitive deficits in schizophrenia.

METHODS

We conducted a literature search of studies from 2011 to 2021 across four electronic databases including PubMed, PsycInfo, MEDLINE, and Embase. Human studies using a pharmacological treatment for cognitive impairment in schizophrenia were included.

RESULTS

Fifty-eight eligible publications, representing 11 pharmacological classes, were included in this review. Major limitations involved small sample size, methodological limitations as well as heterogeneity of participants and outcome measures.

CONCLUSIONS

Overall evidence remains inconclusive for any pharmacological classes studied for the treatment of cognitive deficits in schizophrenia. Methodological limitations in a majority of the studies rendered their findings preliminary. We further discuss possible explanations for these findings that could guide future research.

Antibiotic exposure is associated with decreased risk of psychiatric disorders

Objective: This study sought to investigate the relationship between antibiotic exposure and subsequent risk of psychiatric disorders. Methods: This retrospective cohort study used a national database of 69 million patients from 54 large healthcare organizations. We identified a cohort of 20,214 (42.5% male; 57.9 ± 15.1 years old [mean ± SD]) adults without prior neuropsychiatric diagnoses who received antibiotics during hospitalization. Matched controls included 41,555 (39.6% male; 57.3 ± 15.5 years old) hospitalized adults without antibiotic exposure. The two cohorts were balanced for potential confounders, including demographics and variables with potential to affect: the microbiome, mental health, medical comorbidity, and overall health status. Data were stratified by age and by sex, and outcome measures were assessed starting 6 months after hospital discharge. Results: Antibiotic exposure was consistently associated with a significant decrease in the risk of novel mood disorders and anxiety and stressor-related disorders in: men (mood (OR 0.84, 95% CI 0.77, 0.91), anxiety (OR 0.88, 95% CI 0.82, 0.95), women (mood (OR 0.94, 95% CI 0.89,1.00), anxiety (OR 0.93, 95% CI 0.88, 0.98), those who are 26-49 years old (mood (OR 0.87, 95% CI 0.80, 0.94), anxiety (OR 0.90, 95% CI 0.84, 0.97)), and in those ≥50 years old (mood (OR 0.91, 95% CI 0.86, 0.97), anxiety (OR 0.92, 95% CI 0.87, 0.97). Risk of intentional harm and suicidality was decreased in men (OR 0.73, 95% CI 0.55, 0.98) and in those ≥50 years old (OR 0.67, 95% CI 0.49, 0.92). Risk of psychotic disorders was also decreased in subjects ≥50 years old (OR 0.83, 95 CI: 0.69, 0.99). Conclusion: Use of antibiotics in the inpatient setting is associated with protective effects against multiple psychiatric outcomes in an age- and sex-dependent manner.

Microglia and cognitive impairment in schizophrenia: translating scientific progress into novel therapeutic interventions

Cognitive impairment is a core clinical feature of schizophrenia, exerting profound adverse effects on social functioning and quality of life in a large proportion of patients with schizophrenia. However, the mechanisms underlying the pathogenesis of schizophrenia-related cognitive impairment are not well understood. Microglia, the primary resident macrophages in the brain, have been shown to play important roles in psychiatric disorders, including schizophrenia. Increasing evidence has revealed excessive microglial activation in cognitive deficits related to a broad range of diseases and medical conditions. Relative to that about age-related cognitive deficits, current knowledge about the roles of microglia in cognitive impairment in neuropsychiatric disorders, such as schizophrenia, is limited, and such research is in its infancy. Thus, we conducted this review of the scientific literature with a focus on the role of microglia in schizophrenia-associated cognitive impairment, aiming to gain insight into the roles of microglial activation in the onset and progression of such impairment and to consider how scientific advances could be translated to preventive and therapeutic interventions. Research has demonstrated that microglia, especially those in the gray matter of the brain, are activated in schizophrenia. Upon activation, microglia release key proinflammatory cytokines and free radicals, which are well-recognized neurotoxic factors contributing to cognitive decline. Thus, we propose that the inhibition of microglial activation holds potential for the prevention and treatment of cognitive deficits in patients with schizophrenia. This review identifies potential targets for the development of new treatment strategies and eventually the improvement of care for these patients. It might also help psychologists and clinical investigators in planning future research.

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.

Connecting Neurobiological Features with Interregional Dysconnectivity in Social-Cognitive Impairments of Schizophrenia

Schizophrenia (SZ) is a devastating psychiatric disorder affecting about 1% of the world's population. Social-cognitive impairments in SZ prevent positive social interactions and lead to progressive social withdrawal. The neurobiological underpinnings of social-cognitive symptoms remain poorly understood, which hinders the development of novel treatments. At the whole-brain level, an abnormal activation of social brain regions and interregional dysconnectivity within social-cognitive brain networks have been identified as major contributors to these symptoms. At the cellular and subcellular levels, an interplay between oxidative stress, neuroinflammation and N-methyl-D-aspartate receptor hypofunction is thought to underly SZ pathology. However, it is not clear how these molecular processes are linked with interregional dysconnectivity in the genesis of social-cognitive symptoms. Here, we aim to bridge the gap between macroscale (connectivity analyses) and microscale (molecular and cellular mechanistic) knowledge by proposing impaired myelination and the disinhibition of local microcircuits as possible causative biological pathways leading to dysconnectivity and abnormal activity of the social brain. Furthermore, we recommend electroencephalography as a promising translational technique that can foster pre-clinical drug development and discuss attractive drug targets for the treatment of social-cognitive symptoms in SZ.

Minocycline as Treatment for Psychiatric and Neurological Conditions: A Systematic Review and Meta-Analysis

Minocycline has anti-inflammatory, antioxidant, and anti-apoptotic properties that explain the renewed interest in its use as an adjunctive treatment for psychiatric and neurological conditions. Following the completion of several new clinical trials using minocycline, we proposed an up-to-date systematic review and meta-analysis of the data available. The PICO (patient/population, intervention, comparison and outcomes) framework was used to search 5 databases aiming to identify randomized controlled trials that used minocycline as an adjunctive treatment for psychiatric and neurological conditions. Search results, data extraction, and risk of bias were performed by two independent authors for each publication. Quantitative meta-analysis was performed using RevMan software. Literature search and review resulted in 32 studies being included in this review: 10 in schizophrenia, 3 studies in depression, and 7 in stroke, with the benefit of minocycline being used in some of the core symptoms evaluated; 2 in bipolar disorder and 2 in substance use, without demonstrating a benefit for using minocycline; 1 in obsessive-compulsive disorder, 2 in brain and spinal injuries, 2 in amyotrophic lateral sclerosis, 1 in Alzheimer’s disease, 1 in multiple systems atrophy, and 1 in pain, with mixes results. For most of the conditions included in this review the data is still limited and difficult to interpret, warranting more well-designed and powered studies. On the other hand, the studies available for schizophrenia seem to suggest an overall benefit favoring the use of minocycline as an adjunctive treatment.

Developmental Manipulation-Induced Changes in Cognitive Functioning

Schizophrenia is a complex neurodevelopmental disorder with as-yet no identified cause. The use of animals has been critical to teasing apart the potential individual and intersecting roles of genetic and environmental risk factors in the development of schizophrenia. One way to recreate in animals the cognitive impairments seen in people with schizophrenia is to disrupt the prenatal or neonatal environment of laboratory rodent offspring. This approach can result in congruent perturbations in brain physiology, learning, memory, attention, and sensorimotor domains. Experimental designs utilizing such animal models have led to a greatly improved understanding of the biological mechanisms that could underlie the etiology and symptomology of schizophrenia, although there is still more to be discovered. The implementation of the Research and Domain Criterion (RDoC) has been critical in taking a more comprehensive approach to determining neural mechanisms underlying abnormal behavior in people with schizophrenia through its transdiagnostic approach toward targeting mechanisms rather than focusing on symptoms. Here, we describe several neurodevelopmental animal models of schizophrenia using an RDoC perspective approach. The implementation of animal models, combined with an RDoC framework, will bolster schizophrenia research leading to more targeted and likely effective therapeutic interventions resulting in better patient outcomes.

Pentoxifylline as an adjunctive in treatment of negative symptoms in chronic schizophrenia: A double-blind, randomized, placebo-controlled trial

AIM

The aim of this study was to explore the effectiveness and safety of pentoxifylline as an adjuvant to risperidone in mitigating the negative symptoms in patients with chronic schizophrenia.

METHODS

In this randomized, placebo-controlled study, eighty outpatients with chronic schizophrenia were given risperidone for 8 weeks along with either pentoxifylline or a placebo. The positive and negative syndrome scale (PANSS) was used to assess patients at the start of the trial, as well as at 2, 4, 6, and 8 weeks. Pre- and posttreatment serum levels of cAMP, TNF-α-, and IL-6 were measured.

RESULTS

The pentoxifylline group revealed a significant effect for time-treatment interaction on PANSS-negative subscale scores (p < 0.001), PANSS general psychopathology subscale scores (p < 0.001), and PANSS total scores (p < 0.001), but not on PANSS-positive subscale scores (p = 0.169). Additionally, when compared to the placebo group, the pentoxifylline group demonstrated a statistically significant increase in cAMP serum level and a statistically significant decrease in TNF-α and IL-6 serum levels.

CONCLUSION

Pentoxifylline adjunctive therapy with risperidone for 8 weeks was found to be promising in mitigating the negative symptoms in patients with chronic schizophrenia.

TRIAL REGISTRATION NUMBER

NCT04094207.

Glutamatergic dysfunction in Schizophrenia

The NMDA-R hypofunction model of schizophrenia started with the clinical observation of the precipitation of psychotic symptoms in patients with schizophrenia exposed to PCP or ketamine. Healthy volunteers exposed to acute low doses of ketamine experienced mild psychosis but also negative and cognitive type symptoms reminiscent of the full clinical picture of schizophrenia. In rodents, acute systemic ketamine resulted in a paradoxical increase in extracellular frontal glutamate as well as of dopamine. Similar increase in prefrontal glutamate was documented with acute ketamine in healthy volunteers with 1H-MRS. Furthermore, sub-chronic low dose PCP lead to reductions in frontal dendritic tree density in rodents. In post-mortem ultrastructural studies in schizophrenia, a broad reduction in dendritic complexity and somal volume of pyramidal cells has been repeatedly described. This most likely accounts for the broad, subtle progressive cortical thinning described with MRI in- vivo. Additionally, prefrontal reductions in the obligatory GluN1 subunit of the NMDA-R has been repeatedly found in post-mortem tissue. The vast 1H-MRS literature in schizophrenia has documented trait-like small increases in glutamate concentrations in striatum very early in the illness, before antipsychotic treatment (the same structure where increased pre-synaptic release of dopamine has been reported with PET). The more recent genetic literature has reliably detected very small risk effects for common variants involving several glutamate-related genes. The pharmacological literature has followed two main tracks, directly informed by the NMDA-R hypo model: agonism at the glycine site (as mostly add-on studies targeting negative and cognitive symptoms); and pre-synaptic modulation of glutamatergic release (as single agents for acute psychosis). Unfortunately, both approaches have failed so far. There is little doubt that brain glutamatergic abnormalities are present in schizophrenia and that some of these are related to the etiology of the illness. The genetic literature directly supports a non- specific etiological role for glutamatergic dysfunction. Whether NMDA-R hypofunction as a specific mechanism accounts for any important component of the illness is still not evident. However, a glutamatergic model still has heuristic value to guide future research in schizophrenia. New tools to jointly examine brain glutamatergic, GABA-ergic and dopaminergic systems in-vivo, early in the illness, may lay the ground for a next generation of clinical trials that go beyond dopamine D2 blockade.

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.

Taurine, an essential β-amino acid insulates against ketamine-induced experimental psychosis by enhancement of cholinergic neurotransmission, inhibition of oxidative/nitrergic imbalances, and suppression of COX-2/iNOS immunoreactions in mice

Cholinergic, oxidative, nitrergic alterations, and neuroinflammation are some key neuropathological features common in schizophrenia disease. They involve complex biological processes that alter normal behavior. The present treatments used in the management of the disorder remain ineffective together with some serious side effects as one of their setbacks. Taurine is a naturally occurring essential β-amino acid reported to elicit antipsychotic property in first episode psychosis in clinical setting, thus require preclinical investigation. Hence, we set out to investigate the effects of taurine in the prevention and reversal of ketamine-induced psychotic-like behaviors and the associated putative neurobiological mechanisms underlying its effects. Adult male Swiss mice were sheared into three separate cohorts of experiments (n = 7): drug alone, preventive and reversal studies. Treatments consisted of saline (10 mL/kg/p.o./day), taurine (50 and 100 mg/kg/p.o./day) and risperidone (0.5 mg/kg/p.o./day) with concomitant ketamine (20 mg/kg/i.p./day) injections between days 8-14, or 14 days entirely. Behavioral hyperactivity, despair, cognitive impairment, and catalepsy were measured. Brain oxidative/nitrergic imbalance, immunoreactivity (COX-2 and iNOS), and cholinergic markers were determined in the striatum, prefrontal-cortex, and hippocampus. Taurine abates ketamine-mediated psychotic-like episodes without cataleptogenic potential. Taurine attenuated ketamine-induced decrease in glutathione, superoxide-dismutase and catalase levels in the striatum, prefrontal-cortex and hippocampus. Also, taurine prevented and reversed ketamine-mediated elevation of malondialdehyde, nitrite contents, acetylcholinesterase activity, and suppressed COX-2 and iNOS expressions in a brain-region dependent manner. Conclusively, taurine insulates against ketamine-mediated psychotic phenotype by normalizing brain central cholinergic neurotransmissions, oxidative, nitrergic and suppression of immunoreactive proteins in mice brains.

A narrative review of treatment interventions to improve cognitive performance in schizophrenia, with an emphasis on at-risk and early course stages

Cognitive dysfunction is a core feature of schizophrenia (SCZ), which unfavorably affects SCZ patients' daily functioning and overall clinical outcome. An increasing body of evidence has shown that cognitive deficits are present not only at the beginning of the illness but also several years before the onset of psychosis. Nonetheless, the majority of treatment interventions targeting cognitive dysfunction in SCZ, using both pharmacological and nonpharmacological approaches, have focused on chronic patients rather than individuals at high risk or in the early stages of the disease. In this article, we provide a narrative review of cognitive interventions in SCZ patients, with a particular focus on pre-emptive interventions in at-risk/early course individuals when available. Furthermore, we discuss current challenges for these pre-emptive treatment interventions and provide some suggestions on how future work may ameliorate cognitive dysfunction in these individuals.

Management of cognitive and negative symptoms in schizophrenia

Currently available antipsychotics provide only modest benefit in managing the cognitive and negative symptoms of schizophrenia even though these symptoms are often the most impairing in patients' daily lives. Certain antipsychotics may have slight benefits over others, and several nonpharmacologic and pharmacologic adjunctive treatments have been evaluated in recent clinical trials. Recently published meta-analyses and clinical studies of such treatments are reviewed. Potential strategies to manage cognitive and negative symptoms, including deprescribing of medications that may exacerbate these symptoms, are described using theoretical case examples.

Improvement of adjunctive berberine treatment on negative symptoms in patients with schizophrenia

The upregulation of immune and inflammatory response may play a role in the negative symptoms of schizophrenia. Berberine is an effective drug with anti-inflammatory property, and may be beneficial for the treatment of negative symptoms. The aim of this study is to test this hypothesis through a randomized, double-blind, placebo-controlled, clinical trial. Eligible patients with schizophrenia were randomized to receive placebo or berberine (900 mg/day) for 8 weeks as adjunctive treatment to single atypical antipsychotic drug. The Positive and Negative Syndrome Scale (PANSS) was used to evaluate clinical symptoms at three time points (baseline, 4th and 8th week). Blood samples were collected at the above three time points to determine the concentrations of inflammatory markers including interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and C-reactive protein (CRP). 59 patients with intention-to-treat were analyzed, 32 in the berberine group and 27 in the placebo group. From the baseline to the 8th week, berberine treatment significantly improved the negative symptom subscale of PANSS (F = 18.981; p < 0.001). From the baseline to the 8th week, the plasma CRP concentration decreased in the berberine group, while increased in the placebo group (F = 5.373; p = 0.024). Furthermore, in the berberine group, the change of CRP concentration was significantly positively correlated with the change of PANSS negative symptom subscale within 8 weeks (r = 0.56; p = 0.002). There was no significant difference in adverse events between the two groups (p's > 0.05). Our study suggests that berberine treatment is well tolerated in patients with schizophrenia. Berberine may improve negative symptoms through anti-inflammatory effect.Trial registration: Clinicaltrials.gov identifier: NCT03548155.

Controlling astrocyte-mediated synaptic pruning signals for schizophrenia drug repurposing with deep graph networks

Schizophrenia is a debilitating psychiatric disorder, leading to both physical and social morbidity. Worldwide 1% of the population is struggling with the disease, with 100,000 new cases annually only in the United States. Despite its importance, the goal of finding effective treatments for schizophrenia remains a challenging task, and previous work conducted expensive large-scale phenotypic screens. This work investigates the benefits of Machine Learning for graphs to optimize drug phenotypic screens and predict compounds that mitigate abnormal brain reduction induced by excessive glial phagocytic activity in schizophrenia subjects. Given a compound and its concentration as input, we propose a method that predicts a score associated with three possible compound effects, i.e., reduce, increase, or not influence phagocytosis. We leverage a high-throughput screening to prove experimentally that our method achieves good generalization capabilities. The screening involves 2218 compounds at five different concentrations. Then, we analyze the usability of our approach in a practical setting, i.e., prioritizing the selection of compounds in the SWEETLEAD library. We provide a list of 64 compounds from the library that have the most potential clinical utility for glial phagocytosis mitigation. Lastly, we propose a novel approach to computationally validate their utility as possible therapies for schizophrenia.

Developments in Biological Mechanisms and Treatments for Negative Symptoms and Cognitive Dysfunction of Schizophrenia

The causal mechanisms and treatment for the negative symptoms and cognitive dysfunction in schizophrenia are the main issues attracting the attention of psychiatrists over the last decade. The first part of this review summarizes the pathogenesis of schizophrenia, especially the negative symptoms and cognitive dysfunction from the perspectives of genetics and epigenetics. The second part describes the novel medications and several advanced physical therapies (e.g., transcranial magnetic stimulation and transcranial direct current stimulation) for the negative symptoms and cognitive dysfunction that will optimize the therapeutic strategy for patients with schizophrenia in future.

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.

Neuroinflammation in schizophrenia: the role of nuclear factor kappa B

Neuroinflammation, particularly in the dorsolateral prefrontal cortex, is well-established in a subset of people with schizophrenia, with significant increases in inflammatory markers including several cytokines. Yet the cause(s) of cortical inflammation in schizophrenia remains unknown. Clues as to potential microenvironmental triggers and/or intracellular deficits in immunoregulation may be gleaned from looking further upstream of effector immune molecules to transcription factors that control inflammatory gene expression. Here, we focus on the 'master immune regulator' nuclear factor kappa B (NF-κB) and review evidence in support of NF-κB dysregulation causing or contributing to neuroinflammation in patients. We discuss the utility of 'immune biotyping' as a tool to analyse immune-related transcripts and proteins in patient tissue, and the insights into cortical NF-κB in schizophrenia revealed by immune biotyping compared to studies treating patients as a single, homogenous group. Though the ubiquitous nature of NF-κB presents several hurdles for drug development, targeting this key immunoregulator with novel or repurposed therapeutics in schizophrenia is a relatively underexplored area that could aid in reducing symptoms of patients with active neuroinflammation.

Cognitive Deficit in Schizophrenia: From Etiology to Novel Treatments

Schizophrenia is a major mental illness characterized by positive and negative symptoms, and by cognitive deficit. Although cognitive impairment is disabling for patients, it has been largely neglected in the treatment of schizophrenia. There are several reasons for this lack of treatments for cognitive deficit, but the complexity of its etiology-in which neuroanatomic, biochemical and genetic factors concur-has contributed to the lack of effective treatments. In the last few years, there have been several attempts to develop novel drugs for the treatment of cognitive impairment in schizophrenia. Despite these efforts, little progress has been made. The latest findings point to the importance of developing personalized treatments for schizophrenia which enhance neuroplasticity, and of combining pharmacological treatments with non-pharmacological measures.

The gut-microbiome as a target for the treatment of schizophrenia: A systematic review and meta-analysis of randomised controlled trials of add-on strategies

The gut-microbiome has been hypothesised as a novel potential target for intervention for schizophrenia. We tested this hypothesis with a systematic review and meta-analysis of studies investigating the efficacy and acceptability of add-on strategies known to affect the gut-microbiome for the treatment of schizophrenia. Following PRISMA guidelines, we searched from inception to August 2019 all the randomised double-blind controlled trials of add-on antibiotics, antimicrobials, pre/probiotics, and faecal transplant in schizophrenia. Primary outcomes were severity of negative symptoms and acceptability of treatment. Data were independently extracted by multiple observers and a random-mixed model was used for the analysis. Heterogeneity was assessed with the I² index. We identified 28 eligible trials: 21 investigated antibiotics, 4 antimicrobials (Artemisinin, Artemether, and Sodium Benzoate), 3 pre/probiotics, none faecal transplant. Results showed no effect of D-Cycloserine (10 studies; SMD, -0.16; 95% CI -0.40, 0.08; P = .20; I²: 28.2%), Minocycline (7 studies; SMD: -0.35; 95% CI -0.70, 0.00; P = .05, I²:77.7%), other antibiotics (2 studies), probiotics alone (1 study), and Artemisinin (1 study) on negative symptoms of schizophrenia when compared to placebo. Limited evidence suggests efficacy on negative symptoms for Sodium benzoate (2 studies; SMD, -0.63; 95%CI -1.03, -0.23; P < .001; I²:0%), Artemether (1 study), and probiotics combined with Vitamin D (1 study) when compared to placebo. Acceptability of intervention was similar to placebo. Negative findings were mainly led by antibiotics trials, with paucity of evidence available on pre/probiotics. There is a need of expanding our knowledge on the clinical relevance of gut-microbiome-host interaction in psychosis before engaging in further trials.

A Characterization of the Effects of Minocycline Treatment During Adolescence on Structural, Metabolic, and Oxidative Stress Parameters in a Maternal Immune Stimulation Model of Neurodevelopmental Brain Disorders

BACKGROUND

Minocycline (MIN) is a tetracycline with antioxidant, anti-inflammatory, and neuroprotective properties. Given the likely involvement of inflammation and oxidative stress (IOS) in schizophrenia, MIN has been proposed as a potential adjuvant treatment in this pathology. We tested an early therapeutic window, during adolescence, as prevention of the schizophrenia-related deficits in the maternal immune stimulation (MIS) animal model.

METHODS

On gestational day 15, Poly I:C or vehicle was injected in pregnant Wistar rats. A total 93 male offspring received MIN (30 mg/kg) or saline from postnatal day (PND) 35-49. At PND70, rats were submitted to the prepulse inhibition test. FDG-PET and T2-weighted MRI brain studies were performed at adulthood. IOS markers were evaluated in frozen brain tissue.

RESULTS

MIN treatment did not prevent prepulse inhibition test behavioral deficits in MIS offspring. However, MIN prevented morphometric abnormalities in the third ventricle but not in the hippocampus. Additionally, MIN reduced brain metabolism in cerebellum and increased it in nucleus accumbens. Finally, MIN reduced the expression of iNOS (prefrontal cortex, caudate-putamen) and increased the levels of KEAP1 (prefrontal cortex), HO1 and NQO1 (amygdala, hippocampus), and HO1 (caudate-putamen).

CONCLUSIONS

MIN treatment during adolescence partially counteracts volumetric abnormalities and IOS deficits in the MIS model, likely via iNOS and Nrf2-ARE pathways, also increasing the expression of cytoprotective enzymes. However, MIN treatment during this peripubertal stage does not prevent sensorimotor gating deficits. Therefore, even though it does not prevent all the MIS-derived abnormalities evaluated, our results suggest the potential utility of early treatment with MIN in other schizophrenia domains.

The effect of berberine adjunctive treatment on glycolipid metabolism in patients with schizophrenia: A randomized, double-blind, placebo-controlled clinical trial

Previous studies have shown that berberine can improve metabolic disturbances in non-psychiatric patients, but no clinical research has been conducted in schizophrenia. This study was a randomized, double-blind, placebo-controlled clinical trial. Eligible patients diagnosed with schizophrenia were randomized to receive placebo or berberine (900mg/day) as an adjunctive treatment for eight weeks. Peripheral glycolipid metabolism parameters were measured at baseline, week 4, and week 8. Sixty-five patients were included, and forty-nine patients completed the 8-week trial. Berberine led to significant declines in total cholesterol, low-density lipoprotein cholesterol, fasting serum insulin, and insulin resistance(all p<0.05) compared with placebo. Baseline body mass index and serum prolactin concentration could predict the effect of berberine on insulin resistance. Berberine adjunctive treatment may reduce the risk of glycolipid metabolic disturbances in patients with schizophrenia.

Towards precision medicine: What are the stratification hypotheses to identify homogeneous inflammatory subgroups

Diverse lines of research testify a link, presumably causal, between immune dysregulation and the development, course and clinical outcome of psychiatric disorders. However, there is a large heterogeneity among the patients' individual immune profile and this heterogeneity prevents the development of precise diagnostic tools and the identification of therapeutic targets. The aim of this review was to delineate possible subgroups of patients on the basis of clinical dimensions, investigating whether they could lead to particular immune signatures and tailored treatments. We discuss six clinical entry points; genetic liability to immune dysregulation, childhood maltreatment, metabolic syndrome, cognitive dysfunction, negative symptoms and treatment resistance. We describe the associated immune signature and outline the effects of anti-inflammatory drugs so far. Finally, we discuss advantages of this approach, challenges and future research directions.

Tetracyclines, a promise for neuropsychiatric disorders: from adjunctive therapy to the discovery of new targets for rational drug design in psychiatry

Major mental disorders, such as schizophrenia, bipolar disorder, and major depressive disorder, represent the leading cause of disability worldwide. Nevertheless, the current pharmacotherapy has several limitations, and a large portion of patients do not respond appropriately to it or remain with disabling symptoms overtime. Traditionally, pharmacological interventions for psychiatric disorders modulate dysfunctional neurotransmitter systems. In the last decades, compelling evidence has advocated for chronic inflammatory mechanisms underlying these disorders. Therefore, the repurposing of anti-inflammatory agents has emerged as an attractive therapeutic tool for mental disorders. Minocycline (MINO) and doxycycline (DOXY) are semisynthetic second-generation tetracyclines with neuroprotective and anti-inflammatory properties. More recently, the most promising results obtained in clinical trials using tetracyclines for major psychiatric disorders were for schizophrenia. In a reverse translational approach, tetracyclines inhibit microglial reactivity and toxic inflammation by mechanisms related to the inhibition of nuclear factor kappa B signaling, cyclooxygenase 2, and matrix metalloproteinases. However, the molecular mechanism underlying the effects of these tetracyclines is not fully understood. Therefore, the present review sought to summarize the latest findings of MINO and DOXY use for major psychiatric disorders and present the possible targets to their molecular and behavioral effects. In conclusion, tetracyclines hold great promise as (ready-to-use) agents for being used as adjunctive therapy for human neuropsychiatric disorders. Hence, the understanding of their molecular mechanisms may contribute to the discovery of new targets for the rational drug design of novel psychoactive agents.

Minocycline in neurodegenerative and psychiatric diseases: An update

BACKGROUND AND PURPOSE

Minocycline is a broad-spectrum antibiotic, effective as a chronic treatment for recurrent bacterial infections. Beyond its antibiotic action, minocycline also has important anti-inflammatory, antioxidant and antiapoptotic properties. Its efficacy has therefore been evaluated in many neurodegenerative and psychiatric diseases that have an inflammatory basis. Our aim was to review preclinical and clinical studies performed in neurological and psychiatric diseases whose treatment involved the use of minocycline and thereby to discern the possible beneficial effect of minocycline in these disorders.

METHODS

Completed and ongoing preclinical studies and clinical trials of minocycline for both neurodegenerative diseases and psychiatric disorders, published from January 1995 to January 2020, were identified through searching relevant databases (https://www.ncbi.nlm.nih.gov/pubmed/, https://clinicaltrials.gov/). A total of 74 preclinical studies and 44 clinical trials and open-label studies were selected.

RESULTS

The results of the nearly 20 years of research identified are diverse. While minocycline mostly proved to be effective in animal models, clinical results showed divergent outcomes, with positive results in some studies counterbalanced by a number of cases with no significant improvements. Specific data for each disease are further individually described in this review.

CONCLUSIONS

Despite minocycline demonstrating antioxidant and anti-inflammatory effects, discrepancies between preclinical and clinical data indicate that we should be cautious in analyzing the outcomes. Improving and standardizing protocols and refining animal models could help us to determine if minocycline really is a useful drug in the treatment of these pathologies.

Efficacy and safety of anti-inflammatory agents in treatment of psychotic disorders - A comprehensive systematic review and meta-analysis

OBJECTIVE

Antipsychotic effects of immunomodulating drugs have been suggested; however, a thorough, comprehensive meta-analysis on the effect and safety of anti-inflammatory add-on treatment on psychotic disorders is lacking.

METHOD

Multiple databases were searched up until February 2020. Only double-blinded, randomized, placebo-controlled clinical trials (RCTs) were included. Primary outcomes were change in total psychopathology and adverse events. Secondary outcomes included, amongst others, positive and negative symptoms, general psychopathology and cognitive domains. We performed random-effects meta-analyses estimating mean differences (MD) and standardized mean differences (SMD) for effect sizes.

RESULTS

Seventy RCTs (N = 4104) were included, investigating either primarily anti-inflammatory drugs, i.e. drugs developed for immunomodulation, such as NSAIDs, minocycline and monoclonal antibodies (k = 15), or drugs with potential anti-inflammatory properties (k = 55), e.g. neurosteroids, N-acetyl cysteine, estrogens, fatty acids, statins, and glitazones. Antipsychotics plus anti-inflammatory treatment, compared to antipsychotics plus placebo, was associated with a PANSS scale MD improvement of -4.57 (95%CI = -5.93 to -3.20) points, corresponding to a SMD effect size of -0.29 (95%CI = -0.40 to -0.19). Trials on schizophrenia (MD = -6.80; 95%CI, -9.08 to -4.52) showed greater improvement (p < 0.01) than trials also including other psychotic disorders. However, primarily anti-inflammatory drugs (MD = 4.00; 95%CI = -7.19 to -0.80) were not superior (p = 0.69) to potential anti-inflammatory drugs (MD = 4.71; 95%CI = -6.26 to -3.17). Furthermore, meta-regression found that smaller studies showed significantly larger effect sizes than the larger studies (p = 0.0085), and only 2 studies had low risk of bias on all domains. Small but significant effects were found on negative symptoms (MD = -1.29), positive symptoms (MD = -0.53), general psychopathology (MD = -1.50) and working memory (SMD = 0.21). No differences were found regarding adverse events, but only 26 studies reported hereon.

CONCLUSIONS

Anti-inflammatory add-on treatment to antipsychotics showed improvement of psychotic disorders; however, no superiority was found in primarily anti-inflammatory drugs, raising the question of the mechanism behind the effect, and treatment effect might be overestimated due to the large number of small studies.

A Gut Feeling: The Importance of the Intestinal Microbiota in Psychiatric Disorders

The intestinal microbiota constitutes a complex ecosystem in constant reciprocal interactions with the immune, neuroendocrine, and neural systems of the host. Recent molecular technological advances allow for the exploration of this living organ and better facilitates our understanding of the biological importance of intestinal microbes in health and disease. Clinical and experimental studies demonstrate that intestinal microbes may be intimately involved in the progression of diseases of the central nervous system (CNS), including those of affective and psychiatric nature. Gut microbes regulate neuroinflammatory processes, play a role in balancing the concentrations of neurotransmitters and could provide beneficial effects against neurodegeneration. In this review, we explore some of these reciprocal interactions between gut microbes and the CNS during experimental disease and suggest that therapeutic approaches impacting the gut-brain axis may represent the next avenue for the treatment of psychiatric disorders.

Effects of Doxycycline in Swiss Mice Predictive Models of Schizophrenia

Schizophrenia patients show very complex symptoms in several psychopathological domains. Some of these symptoms remain poorly treated. Therefore, continued effort is needed to find novel pharmacological strategies for improving schizophrenia symptoms. Recently, minocycline, a second-generation tetracycline, has been suggested as an adjunctive treatment for schizophrenia. The antipsychotic-like effect of doxycycline, a minocycline analog, was investigated here. We found that both minocycline and doxycycline prevented amphetamine-induced prepulse inhibition (PPI) disruption. However, neither of them blocked MK801-induced effects, albeit doxycycline had a modest impact against ketamine-induced effects. Neither c-Fos nor nNOS expression, which was evaluated in limbic regions, were modified after acute or sub-chronic treatment with doxycycline. Therefore, apomorphine inducing either PPI disruption and climbing behavior was not prevented by doxycycline. This result discards a direct blockade of D2-like receptors, also suggested by the lack of doxycycline cataleptic-induced effect. Contrasting, doxycycline prevented SKF 38393-induced effects, suggesting a preferential doxycycline action at D1-like rather than D2-like receptors. However, doxycycline did not bind to the orthosteric sites of D1, D2, D3, D4, 5-HT2A, 5-HT1A, and A2A receptors suggesting no direct modulation of these receptors. Our data corroborate the antipsychotic-like effect of doxycycline. However, these effects are probably not mediated by doxycycline direct interaction with classical receptors enrolled in the antipsychotic effect.

A single administration of the antibiotic, minocycline, reduces fear processing and improves implicit learning in healthy volunteers: analysis of the serum metabolome

Minocycline has shown therapeutic promise in pre-clinical animal models and early phase clinical trials for a variety of psychiatric disorders. Previous studies on minocycline have shown its ability to suppress microglia activity and reduce inflammatory cytokine levels, and its amelioration of depressive-like behaviour in animals and humans. However, the underlying mechanisms that lead to minocycline's psychotropic effects are not clear. In this study, we investigated the psychological and biochemical effects of an acute dose of minocycline or placebo in 40 healthy adult volunteers. Psychological changes in emotional processing, implicit learning, and working memory were assessed. Plasma inflammatory markers, measured with enzyme-linked immunosorbent assays, and serum metabolites, measured with proton nuclear magnetic resonance combined with multi-variate analysis techniques, were also studied. Results showed that minocycline administration decreased fear misclassification and increased contextual learning, which suggested that reducing negative biases and improving cognition, respectively, may underlie the antidepressant actions of this agent. An examination of serum metabolites revealed higher levels of lipoproteins, particularly cholesterol, in the minocycline group. Minocycline also decreased circulating concentrations of the inflammatory marker C-Reactive Peptide, which is consistent with previous research. These effects highlight two important psychological mechanisms that may be relevant to the efficacy of minocycline reported in clinical trials, and also suggest a possible largely unexplored lipid-related biochemical pathway for the action of this drug.

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

BACKGROUND

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

OBJECTIVE

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

RESULTS

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

CONCLUSION

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

Technical and Theoretic Limitations of the Experimental Evidence Supporting a Gut Bacterial Etiology in Mental Illness

The impact of gut bacteria on the brain and behavior has become the subject of intense research. The brain is sensitive to biochemical and physiologic changes in the body, for example, changes in blood oxygenation or nutritional status. The collection of microorganisms residing within the digestive tract (the gut microbiome) is increasingly considered a major contributor to human physiology. These 2 considerations have led to the hypothesis that human psychology, including complex constructs like emotion and mental illness, could be influenced by the composition or function of gut bacteria. Five lines of evidence have been used to support the concept, including human correlational research, probiotic supplementation, antibiotic use, germ-free animal research, and fecal transplantation. Results from these experiments do not provide substantial support for the theory that complex human psychology is under the influence of gut bacteria. Placebo-controlled interventional research in humans, in particular fecal microbiota transplantation, will be required before a stronger conclusion can be reached.

An update on the efficacy of anti-inflammatory agents for patients with schizophrenia: a meta-analysis

BACKGROUND

Accumulating evidence shows that a propensity towards a pro-inflammatory status in the brain plays an important role in schizophrenia. Anti-inflammatory drugs might compensate this propensity. This study provides an update regarding the efficacy of agents with some anti-inflammatory actions for schizophrenia symptoms tested in randomized controlled trials (RCTs).

METHODS

PubMed, Embase, the National Institutes of Health website (http://www.clinicaltrials.gov), and the Cochrane Database of Systematic Reviews were systematically searched for RCTs that investigated clinical outcomes.

RESULTS

Our search yielded 56 studies that provided information on the efficacy of the following components on symptom severity: aspirin, bexarotene, celecoxib, davunetide, dextromethorphan, estrogens, fatty acids, melatonin, minocycline, N-acetylcysteine (NAC), pioglitazone, piracetam, pregnenolone, statins, varenicline, and withania somnifera extract. The results of aspirin [mean weighted effect size (ES): 0.30; n = 270; 95% CI (CI) 0.06-0.54], estrogens (ES: 0.78; n = 723; CI 0.36-1.19), minocycline (ES: 0.40; n = 946; CI 0.11-0.68), and NAC (ES: 1.00; n = 442; CI 0.60-1.41) were significant in meta-analysis of at least two studies. Subgroup analysis yielded larger positive effects for first-episode psychosis (FEP) or early-phase schizophrenia studies. Bexarotene, celecoxib, davunetide, dextromethorphan, fatty acids, pregnenolone, statins, and varenicline showed no significant effect.

CONCLUSIONS

Some, but not all agents with anti-inflammatory properties showed efficacy. Effective agents were aspirin, estrogens, minocycline, and NAC. We observed greater beneficial results on symptom severity in FEP or early-phase schizophrenia.

Adjunctive minocycline for major mental disorders: A systematic review

OBJECTIVES

This meta-analysis of randomized controlled trials (RCTs) examined the efficacy and safety of minocycline for three major mental disorders: schizophrenia, bipolar disorder and major depressive disorder (MDD).

METHODS

A systematic literature search of major electronic databases was conducted. Meta-analysis of clinical efficacy as defined by the respective studies, all-cause discontinuation, adverse drug reactions (ADRs) with standardized mean difference (SMD) and risk ratios (RRs) and their 95% confidence intervals (CI) was conducted using random-effects model. Quality assessment was performed with the Jadad scale and Cochrane risk of bias.

RESULTS

Sixteen RCTs (n=1357) on minocycline (50-300 mg/day) for schizophrenia (13 RCTs, n=1196), bipolar depression (1 RCT, n=49), and MDD (2 RCTs, n=112) were analyzed separately by diagnosis. Twelve RCTs mentioned randomized allocation specifically; the weighted Jadad scores were 4.0. Adjunctive minocycline outperformed placebo in improving total psychopathology [SMD: -0.45 (95%CI: -0.73, -0.16), p=0.002; I²=77%], positive [SMD: -0.15 (95%CI: -0.28, -0.02), p=0.02; I²=0%], negative [SMD: -0.62 (95%CI: -0.95, -0.28), p=0.0003; I²=85%] and general psychopathology scores [SMD: -0.28 (95%CI: -0.53, -0.03), p=0.03; I²=59%] in schizophrenia. Minocycline showed no significant effect on depressive and manic symptoms in both bipolar depression and MDD. Minocycline caused significantly less headache (p=0.02, number-needed-to-harm=14, 95%CI=5-14) than placebo in schizophrenia. All-cause discontinuation and other ADRs were similar between minocycline and placebo in each diagnostic category.

CONCLUSION

In this meta-analysis, adjunctive minocycline appeared to be efficacious and safe for schizophrenia. However, the efficacy of adjunctive minocycline for bipolar depression or MDD could not be demonstrated.

REVIEW REGISTRATION

PROSPERO: CRD42018102483.

The effect of minocycline on amelioration of cognitive deficits and pro-inflammatory cytokines levels in patients with schizophrenia

BACKGROUND

Cognitive deficits of schizophrenia are predictors of poor function, but antipsychotic medication has limited efficacy for cognitive deficits. These deficits in learning and memory may result from activity of pro-inflammatory cytokines, which microglia produce. The microglia inhibitor minocycline might arrest this cytokine damage to the hippocampus and reverse the cognitive deficits of schizophrenia.

METHODS

A double-blind, placebo-controlled study involved 75 patients with schizophrenia who randomly received low dose (100 mg/day) or high dose minocycline (200 mg/day) or placebo added to risperidone. MATRICS Consensus Cognitive Battery (MCCB) was used to assess the cognitive functioning, and serum levels of Interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) were assessed.

RESULTS

Minocycline_{high dose} group was significantly superior to minocycline_{low dose} or placebo group not only for the improvements in cognitive tests' scores as well (P < 0.05), but for IL-1β and IL-6 serum levels reduction (P < 0.01). The amelioration of cognitive deficits with minocycline correlated not only with the remission of negative symptoms, but also with the reduction in serum levels of IL-1β and IL-6.

CONCLUSIONS

Minocycline adjunctive treatment was effective in improving cognitive deficits of patients with schizophrenia. The beneficial effect of minocycline may be related to reducing pro-inflammatory cytokines through microglia inhibition.

Potentially repurposable drugs for schizophrenia identified from its interactome

We previously presented the protein-protein interaction network of schizophrenia associated genes, and from it, the drug-protein interactome which showed the drugs that target any of the proteins in the interactome. Here, we studied these drugs further to identify whether any of them may potentially be repurposable for schizophrenia. In schizophrenia, gene expression has been described as a measurable aspect of the disease reflecting the action of risk genes. We studied each of the drugs from the interactome using the BaseSpace Correlation Engine, and shortlisted those that had a negative correlation with differential gene expression of schizophrenia. This analysis resulted in 12 drugs whose differential gene expression (drug versus normal) had an anti-correlation with differential expression for schizophrenia (disorder versus normal). Some of these drugs were already being tested for their clinical activity in schizophrenia and other neuropsychiatric disorders. Several proteins in the protein interactome of the targets of several of these drugs were associated with various neuropsychiatric disorders. The network of genes with opposite drug-induced versus schizophrenia-associated expression profiles were significantly enriched in pathways relevant to schizophrenia etiology and GWAS genes associated with traits or diseases that had a pathophysiological overlap with schizophrenia. Drugs that targeted the same genes as the shortlisted drugs, have also demonstrated clinical activity in schizophrenia and other related disorders. This integrated computational analysis will help translate insights from the schizophrenia drug-protein interactome to clinical research - an important step, especially in the field of psychiatric drug development which faces a high failure rate.

Supporting microglial niches for therapeutic benefit in psychiatric disorders

Inflammation is an essential tissue response to injury, stress, or infection resulting in debris and/or pathogen clearance intended to promote healing and recovery. Due to the status as an immune 'privileged' tissue, microglia serve as endogenous regulators of inflammation in the central nervous system, but maintain communication with peripheral immune system to enable recruitment of peripheral immune cells in case of injury or infection. While microglia retain the functional capacity for a full range of inflammatory functions - microglia express a range of pattern-recognition receptors and function as innate immune cells, carry out phagocytosis of pathogens, and act as antigen presenting cells - in the healthy central nervous system (CNS) these functions are rarely engaged. Subsequently microglia are being recognized to occupy an increasing number of homeostatic niches, and in many cases have adopted immune or inflammatory mechanisms to carry out these niche functions absent immune activation. These sterile inflammatory functions are challenging long-held views of the role of inflammation in the central nervous system while simultaneously expanding the potential for the development of truly novel therapeutic interventions for a range of neuroinflammatory, neurodegenerative, and neuropsychiatric disorders. In the present review we discuss recent preclinical evidence for conserved niche functions for microglia whose disruption may causally contribute to various psychiatric disorders, and prospective targets for restoring disrupted niches.

Adjunctive use of anti-inflammatory drugs for schizophrenia: A meta-analytic investigation of randomized controlled trials

OBJECTIVE

Recent evidence suggests that adjuvant anti-inflammatory agents could improve the symptoms of patients with schizophrenia. However, the effects of the adjuvant anti-inflammatory agents on cognitive function, general functioning and side effects have not yet been systematically investigated. The present meta-analysis aimed to explore the effects of anti-inflammatory agents in patients with schizophrenia comprehensively.

METHOD

We performed a literature search in online databases, including PubMed, EMBASE and the Cochrane Database of Systematic Reviews. Randomized, placebo-controlled double-blind studies that investigated clinical outcomes including psychopathology, neurocognition, general functioning and extrapyramidal side effects were included. The examined anti-inflammatory agents included aspirin, celecoxib, omega-3 fatty acids, estrogen, selective estrogen receptor modulator, pregnenolone, N-acetylcysteine, minocycline, davunetide and erythropoietin.

RESULTS

Sixty-two double-blind randomized clinical trials studying 2914 patients with schizophrenia met the inclusion criteria for quantitative analysis. Significant overall effects were found for anti-inflammatory agents for reducing total, positive and negative symptom scores in the Positive and Negative Syndrome Scale. Cognitive improvements were significant with minocycline and pregnenolone augmentation therapy. General functioning was significantly enhanced by overall anti-inflammatory agents. There were no significant differences in side effects compared with placebo. Baseline total Positive and Negative Syndrome Scale score and illness duration were identified as moderating factors in the effects of anti-inflammatory augmentation on psychiatric symptom improvements.

CONCLUSION

The comparative evaluation of efficacy and safety supported the use of anti-inflammatory adjuvant therapy over the use of antipsychotics alone. However, future studies could focus on patients with homogeneous clinical profile to figure out more detailed effects of anti-inflammatory therapy.

Pharmacotherapy of schizophrenia: toward a metabolomic-based approach

Approximately 20%-30% of schizophrenia patients are resistant to current standard pharmacotherapies. Recent schizophrenia research aims to identify specific pathophysiological abnormalities and novel targets in the disease, with the goals of identifying at-risk individuals, facilitating diagnosis, prompting early and personalized interventions, and helping predict response to treatment. Metabolomics involves the systematic study of the profile of biochemical alterations early in the course of a given disorder. Major aspects of the schizophrenia metabolome have been characterized, uncovering potential selective biomarkers for the disease that may change how the disorder is diagnosed, and how patients are stratified and treated. This review focuses on the most common metabolomic fingerprints of the different pathways involved in the pathophysiology of schizophrenia, and the potential development of novel metabolomic-related pharmacotherapies for improved treatment of schizophrenia and other related idiopathic psychotic disorders.

Puerarin suppresses cell growth and migration in HPV-positive cervical cancer cells by inhibiting the PI3K/mTOR signaling pathway

Puerarin is an effective component that is present in high concentrations in the Pueraria lobata plant and is extensively distributed throughout nature. Puerarin possesses a number of pharmacological effects and has strong pharmacological activity with few side effects and extensive clinical applications. The aim of the present study was to explore the effects of Puerarin on the apoptosis of human papillomavirus (HPV)-positive cervical cancer cells and the underlying molecular mechanisms. MTT assay, lactate dehydrogenase activity and Annexin V/fluorescein isothiocyanate/propidium iodide analysis were used to analyze cell growth of HPV-positive HeLa cervical cancer cells treated with Puerarin. Western blotting was performed to measure protein expression in the treated cells. Puerarin significantly reduced cell proliferation and induced apoptosis in HeLa cells. In addition, it was observed that Puerarin significantly enhanced caspase-3/9 activities and significantly increased B-cell lymphoma 2-asscoiate X protein expression in HeLa cells. Puerarin suppressed phosphatidylinositol-3 kinase (PI3K), phosphorylated (p)-protein kinase B (Akt) and p-mammalian target of rapamycin (mTOR) protein expression in HeLa cells. These results indicate that Puerarin induces apoptosis in HPV-positive HeLa cervical cancer cells via inhibiting PI3K/Akt/mTOR signaling.

Effect of N-methyl-D-aspartate-receptor-enhancing agents on cognition in patients with schizophrenia: A systematic review and meta-analysis of double-blind randomised controlled trials

BACKGROUND

Multiple N-methyl-d-aspartate (NMDA)-receptor-enhancing agents have demonstrated promising effects for cognition in schizophrenia. However, the results of studies have been conflicting. This updated meta-analysis explored the effect of NMDA-receptor-enhancing agents on cognitive function.

METHODS

We searched PubMed, the Cochrane Collaboration Central Register of Controlled Clinical Trials and Cochrane Systematic Reviews for studies on the effect of NMDA-receptor-enhancing agents on cognitive function in patients with schizophrenia up to September 2018. Double-blind randomised placebo trials with cognition rating scales were included. We pooled studies by using a random-effect model for comparisons with add-on NMDA-receptor-enhancing agents. Cognitive function scores were compared between baseline and subsequent levels, and NMDA-receptor-positive modulators were assessed using the standardised mean difference (SMD) with 95% confidence intervals (CIs). We evaluated statistical heterogeneity through visual inspection of funnel plots and by using the I² statistic.

RESULTS

We identified 25 trials with 1951 participants meeting the inclusion criteria. NMDA-receptor-enhancing agents had a small but nonsignificant effect compared with the placebo on overall cognitive function (SMD = 0.068, CI = -0.056 to 0.193, P = 0.283). We identified trials enrolling patients aged between 30 and 39 years old, which reported significant positive effects (SMD: 0.163, 95% CI: 0.016-0.310, P = 0.030). Men were associated with a smaller effect of NMDA-receptor-positive modulators on overall cognitive function. Moreover, subgroup meta-analysis of cognitive domains revealed that N-acetyl cysteine (NAC) had a significant effect on working memory ( P-value for interaction = 0.038; SMD = 0.679, CI = 0.397-0.961, P < 0.001).

CONCLUSIONS

Our meta-analysis revealed no significant effect of NMDA-enhancing agents on overall cognition. However, subgroup analysis suggested that NMDAR-enhancing agents may benefit young patients with schizophrenia, and NAC may have an effect on working memory. Additional trials with larger samples are suggested to evaluate these cognitive domains and ascertain the possible mechanisms.

The effect of minocycline on symptoms in schizophrenia: Results from a randomized controlled trial

BACKGROUND

Studies have hypothesized that immunological abnormalities might contribute to schizophrenia, and basic science studies, as well as several clinical trials suggest that minocycline could be efficacious in ameliorating both positive and negative symptoms of schizophrenia. In this study we examined the effect of minocycline on schizophrenia in a large randomized controlled trial.

METHODS

We performed a 16-week, multi-center, double-blind, randomized, placebo-controlled study on 200 subjects with schizophrenia or schizoaffective disorder randomized to receive either minocycline (200 mg/day, n = 100), or placebo (n = 100) as an add-on to anti-psychotic treatment. The primary outcome measure was the PANSS total score.

RESULTS

Mixed models for repeated measures showed no significant difference between minocycline and placebo for total PANSS (p = 0.862), PANSS subscales, CGI or BACS.

CONCLUSIONS

Minocycline did not improve symptoms or cognition in schizophrenia.

Therapeutic Potential of the Microbiome in the Treatment of Neuropsychiatric Disorders

The search for rational treatment of neuropsychiatric disorders began with the discovery of chlorpromazine in 1951 and continues to evolve. Day by day, new details of the intestinal microbiota–brain axis are coming to light. As the role of microbiota in the etiopathogenesis of neuropsychiatric disorders is more clearly understood, microbiota-based (or as we propose, “fecomodulation”) treatment options are increasingly discussed in the context of treatment. Although their history dates back to ancient times, the importance of psychobiotics and fecal microbiota transplantation (FMT) has only recently been recognized. Despite there being few preclinical and clinical studies, the evidence gathered to this point suggests that consideration of the microbiome in the treatment of neuropsychiatric disorders represents an area of significant therapeutic potential. It is increasingly hoped that such treatment options will be more reliable in terms of their side effects, cost, and ease of implementation. However, there remains much to be researched. Questions will be answered through germ-free animal experiments and randomized controlled trials. In this article, the therapeutic potential of microbiota-based options in the treatment of neuropsychiatric disorders is discussed in light of recent research.

The antidepressant impact of minocycline in rodents: A systematic review and meta-analysis

Evidence from recent animal studies suggest that minocycline, a broad-spectrum antibiotic capable of regulating immune processes, may possess antidepressant properties. These studies, however, have yet to be comprehensively reviewed. Accordingly, this systematic review and meta-analysis summarizes the extant literature examining the effect of minocycline on depressive-like behavior in rodent models. PubMed, PsycINFO, and Web of Science databases were systematically searched for articles that met prespecified inclusion and exclusion criteria, and standardized mean differences (SMDs) were calculated for each continuous measure of depressive-like behavior. The overall effect of minocycline on depressive-like behavior was estimated using robust variance estimation meta-analysis. Separate subgroup analyses were conducted on diseased vs healthy animal models, different rodent species, and immobility-based vs anhedonia-based measures of depressive-like behavior. A total of 22 preclinical studies (816 animals) were included. Overall, minocycline reduced depressive-like behavior in rodents (SMD = -1.07, 95% CI -1.41--0.74, p < 0.001). Subgroup analyses revealed that minocycline reduced depressive-like behavior in diseased, but not healthy, animal models. Finally, minocycline was found to reduce both immobility-based and anhedonia-based outcomes. These findings suggest that minocycline may be an effective treatment of core depressive symptoms, and that further investigation of minocycline treatment for clinically relevant depression in humans is warranted.

The past and future of novel, non-dopamine-2 receptor therapeutics for schizophrenia: A critical and comprehensive review

Since the discovery of chlorpromazine in the 1950's, antipsychotic drugs have been the cornerstone of treatment of schizophrenia, and all attenuate dopamine transmission at the dopamine-2 receptor. Drug development for schizophrenia since that time has led to improvements in side effects and tolerability, and limited improvements in efficacy, with the exception of clozapine. However, the reasons for clozapine's greater efficacy remain unclear, despite the great efforts and resources invested therewith. We performed a comprehensive review of the literature to determine the fate of previously tested, non-dopamine-2 receptor experimental treatments. Overall we included 250 studies in the review from the period 1970 to 2017 including treatments with glutamatergic, serotonergic, cholinergic, neuropeptidergic, hormone-based, dopaminergic, metabolic, vitamin/naturopathic, histaminergic, infection/inflammation-based, and miscellaneous mechanisms. Despite there being several promising targets, such as allosteric modulation of the NMDA and α7 nicotinic receptors, we cannot confidently state that any of the mechanistically novel experimental treatments covered in this review are definitely effective for the treatment of schizophrenia and ready for clinical use. We discuss potential reasons for the relative lack of progress in developing non-dopamine-2 receptor treatments for schizophrenia and provide recommendations for future efforts pursuing novel drug development for schizophrenia.

A phenotypic Caenorhabditis elegans screen identifies a selective suppressor of antipsychotic-induced hyperphagia

Antipsychotic (AP) drugs are used to treat psychiatric disorders but are associated with significant weight gain and metabolic disease. Increased food intake (hyperphagia) appears to be a driving force by which APs induce weight gain but the mechanisms are poorly understood. Here we report that administration of APs to C. elegans induces hyperphagia by a mechanism that is genetically distinct from basal food intake. We exploit this finding to screen for adjuvant drugs that suppress AP-induced hyperphagia in C. elegans and mice. In mice AP-induced hyperphagia is associated with a unique hypothalamic gene expression signature that is abrogated by adjuvant drug treatment. Genetic analysis of this signature using C. elegans identifies two transcription factors, nhr-25/Nr5a2 and nfyb-1/NFYB to be required for AP-induced hyperphagia. Our study reveals that AP-induced hyperphagia can be selectively suppressed without affecting basal food intake allowing for novel drug discovery strategies to combat AP-induced metabolic side effects.

The benefit of minocycline on negative symptoms of schizophrenia in patients with recent-onset psychosis (BeneMin): a randomised, double-blind, placebo-controlled trial

BACKGROUND

The antibiotic minocycline has neuroprotective and anti-inflammatory properties that could prevent or reverse progressive neuropathic changes implicated in recent-onset schizophrenia. In the BeneMin study, we aimed to replicate the benefit of minocycline on negative symptoms reported in previous pilot studies, and to understand the mechanisms involved.

METHODS

In this randomised, double-blind, placebo-controlled trial, we recruited people with a schizophrenia-spectrum disorder that had begun within the past 5 years with continuing positive symptoms from 12 National Health Service (NHS) trusts. Participants were randomly assigned according to an automated permuted blocks algorithm, stratified by pharmacy, to receive minocycline (200 mg per day for 2 weeks, then 300 mg per day for the remainder of the 12-month study period) or matching placebo, which were added to their continuing treatment. The primary clinical outcome was the negative symptom subscale score of the Positive and Negative Syndrome Scales (PANSS) across follow-ups at months 2, 6, 9, and 12. The primary biomarker outcomes were medial prefrontal grey-matter volume, dorsolateral prefrontal cortex activation during a working memory task, and plasma concentration of interleukin 6. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN49141214, and the EU Clinical Trials register (EudraCT) number is 2010-022463-35I.

FINDINGS

Between April 16, 2013, and April 30, 2015, we recruited 207 people and randomly assigned them to receive minocycline (n=104) or placebo (n=103). Compared with placebo, the addition of minocycline had no effect on ratings of negative symptoms (treatment effect difference -0·19, 95% CI -1·23 to 0·85; p=0·73). The primary biomarker outcomes did not change over time and were not affected by minocycline. The groups did not differ in the rate of serious adverse events (n=11 in placebo group and n=18 in the minocycline group), which were mostly due to admissions for worsening psychiatric state (n=10 in the placebo group and n=15 in the minocycline group). The most common adverse events were gastrointestinal (n=12 in the placebo group, n=19 in the minocycline group), psychiatric (n=16 in placebo group, n=8 in minocycline group), nervous system (n=8 in the placebo group, n=12 in the minocycline group), and dermatological (n=10 in the placebo group, n=8 in the minocycline group).

INTERPRETATION

Minocycline does not benefit negative or other symptoms of schizophrenia over and above adherence to routine clinical care in first-episode psychosis. There was no evidence of a persistent progressive neuropathic or inflammatory process underpinning negative symptoms. Further trials of minocycline in early psychosis are not warranted until there is clear evidence of an inflammatory process, such as microgliosis, against which minocycline has known efficacy.

FUNDING

National Institute for Health Research Efficacy and Mechanism Evaluation (EME) programme, an MRC and NIHR partnership.