Plasma levels of mature brain-derived neurotrophic factor (BDNF) and matrix metalloproteinase-9 (MMP-9) in treatment-resistant schizophrenia treated with clozapine

Gut-brain barrier dysfunction bridge autistic-like behavior in mouse model of maternal separation stress: A behavioral, histopathological, and molecular study

Autism spectrum disorder (ASD) is a fast-growing neurodevelopmental disorder throughout the world. Experiencing early life stresses (ELS) like maternal separation (MS) is associated with autistic-like behaviors. It has been proposed that disturbance in the gut-brain axis-mediated psychiatric disorders following MS. The role of disruption in the integrity of gut-brain barrier in ASD remains unclear. Addressing this knowledge gap, in this study we aimed to investigate role of the gut-brain barrier integrity in mediating autistic-like behaviors in mouse models of MS stress. To do this, mice neonates are separated daily from their mothers from postnatal day (PND) 2 to PND 14 for 3 hours. During PND58-60, behavioral tests related to autistic-like behaviors including three-chamber sociability, shuttle box, and resident-intruder tests were performed. Then, prefrontal cortex (PFC), hippocampus, and colon samples were dissected out for histopathological and molecular evaluations. Results showed that MS is associated with impaired sociability and social preference indexes, aggressive behaviors, and impaired passive avoidance memory. The gene expression of CLDN1 decreased in the colon, and the gene expression of CLDN5, CLDN12, and MMP9 increased in the PFC of the MS mice. MS is associated with decrease in the diameter of CA1 and CA3 areas of the hippocampus. In addition, MS led to histopathological changes in the colon. We concluded that, probably, disturbance in the gut-brain barrier integrities mediated the autistic-like behavior in MS stress in mice.

Matrix metalloproteinase 9 (MMP-9) activity, hippocampal extracellular free water, and cognitive deficits are associated with each other in early phase psychosis

Increasing evidence points toward the role of the extracellular matrix, specifically matrix metalloproteinase 9 (MMP-9), in the pathophysiology of psychosis. MMP-9 is a critical regulator of the crosstalk between peripheral and central inflammation, extracellular matrix remodeling, hippocampal development, synaptic pruning, and neuroplasticity. Here, we aim to characterize the relationship between plasma MMP-9 activity, hippocampal microstructure, and cognition in healthy individuals and individuals with early phase psychosis. We collected clinical, blood, and structural and diffusion-weighted magnetic resonance imaging data from 39 individuals with early phase psychosis and 44 age and sex-matched healthy individuals. We measured MMP-9 plasma activity, hippocampal extracellular free water (FW) levels, and hippocampal volumes. We used regression analyses to compare MMP-9 activity, hippocampal FW, and volumes between groups. We then examined associations between MMP-9 activity, FW levels, hippocampal volumes, and cognitive performance assessed with the MATRICS battery. All analyses were controlled for age, sex, body mass index, cigarette smoking, and years of education. Individuals with early phase psychosis demonstrated higher MMP-9 activity (p < 0.0002), higher left (p < 0.05) and right (p < 0.05) hippocampal FW levels, and lower left (p < 0.05) and right (p < 0.05) hippocampal volume than healthy individuals. MMP-9 activity correlated positively with hippocampal FW levels (all participants and individuals with early phase psychosis) and negatively with hippocampal volumes (all participants and healthy individuals). Higher MMP-9 activity and higher hippocampal FW levels were associated with slower processing speed and worse working memory performance in all participants. Our findings show an association between MMP-9 activity and hippocampal microstructural alterations in psychosis and an association between MMP-9 activity and cognitive performance. Further, more extensive longitudinal studies should examine the therapeutic potential of MMP-9 modulators in psychosis.

Variations to plasma H2O2 levels and TAC in chronical medicated and treatment-resistant male schizophrenia patients: Correlations with psychopathology

Accumulating evidence suggests that imbalanced oxidative stress (OS) may contribute to the mechanism of schizophrenia. The aim of the present study was to evaluate the associations of OS parameters with psychopathological symptoms in male chronically medicated schizophrenia (CMS) and treatment-resistant schizophrenia (TRS) patients. Levels of hydrogen peroxide (H2O2), hydroxyl radical (·OH), peroxidase (POD), α-tocopherol (α-toc), total antioxidant capacity (TAC), matrix metalloproteinase-9 (MMP-9), and tissue inhibitor of metalloproteinases-1 (TIMP-1) were assayed in males with CMS and TRS, and matched healthy controls. Schizophrenia symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS). The results demonstrated significant differences in the variables H2O2 (F = 5.068, p = 0.008), ·OH (F = 31.856, p < 0.001), POD (F = 14.043, p < 0.001), α-toc (F = 3.711, p = 0.027), TAC (F = 24.098, p < 0.001), and MMP-9 (F = 3.219, p = 0.043) between TRS and CMS patients and healthy controls. For TRS patients, H2O2 levels were correlated to the PANSS positive subscale (r = 0.386, p = 0.032) and smoking (r = -0,412, p = 0.021), while TAC was significantly negatively correlated to the PANSS total score (r = -0.578, p = 0.001) and POD and TAC levels were positively correlated to body mass index (r = 0.412 and 0.357, p = 0.021 and 0.049, respectively). For patients with CMS, ·OH levels and TAC were positively correlated to the PANSS general subscale (r = 0.308, p = 0.031) and negatively correlated to the PANSS total score (r = -0.543, p < 0.001). Furthermore, H2O2, α-toc, and ·OH may be protective factors against TRS, and POD was a risk factor. Patients with CMS and TRS exhibit an imbalance in OS, thus warranting future investigations.

Behavioral and transcriptional effects of repeated electroconvulsive seizures in the neonatal MK-801-treated rat model of schizophrenia

RATIONALE

Electroconvulsive therapy (ECT) is an effective treatment modality for schizophrenia. However, its antipsychotic-like mechanism remains unclear.

OBJECTIVES

To gain insight into the antipsychotic-like actions of ECT, this study investigated how repeated treatments of electroconvulsive seizure (ECS), an animal model for ECT, affect the behavioral and transcriptomic profile of a neurodevelopmental animal model of schizophrenia.

METHODS

Two injections of MK-801 or saline were administered to rats on postnatal day 7 (PN7), and either repeated ECS treatments (E10X) or sham shock was conducted daily from PN50 to PN59. Ultimately, the rats were divided into vehicle/sham (V/S), MK-801/sham (M/S), vehicle/ECS (V/E), and MK-801/ECS (M/E) groups. On PN59, prepulse inhibition and locomotor activity were tested. Prefrontal cortex transcriptomes were analyzed with mRNA sequencing and network and pathway analyses, and quantitative real-time polymerase chain reaction (qPCR) analyses were subsequently conducted.

RESULTS

Prepulse inhibition deficit was induced by MK-801 and normalized by E10X. In M/S vs. M/E model, Egr1, Mmp9, and S100a6 were identified as center genes, and interleukin-17 (IL-17), nuclear factor kappa B (NF-κB), and tumor necrosis factor (TNF) signaling pathways were identified as the three most relevant pathways. In the V/E vs. V/S model, mitophagy, NF-κB, and receptor for advanced glycation end products (RAGE) pathways were identified. qPCR analyses demonstrated that Igfbp6, Btf3, Cox6a2, and H2az1 were downregulated in M/S and upregulated in M/E.

CONCLUSIONS

E10X reverses the behavioral changes induced by MK-801 and produces transcriptional changes in inflammatory, insulin, and mitophagy pathways, which provide mechanistic insight into the antipsychotic-like mechanism of ECT.

Levels of Matrix Metalloproteinase 9 Are Elevated in Persons With Schizophrenia or Bipolar Disorder: The Role of Modifiable Factors

Background

Matrix metalloproteinases (MMPs) are a diverse set of enzymes associated with inflammation. MMP-9 is of particular interest because it has been associated with autoimmune and cardiopulmonary disorders, tobacco smoking, and obesity, prevalent in psychiatric populations.

Methods

Sensitive enzyme immunoassays measured MMP-9 in blood samples from 1121 individuals (mean age = 35.6 [SD = 13.0] years; 47.7% male; 440 with schizophrenia, 399 with bipolar disorder, and 282 without a psychiatric disorder). We estimated the odds of diagnosis associated with MMP-9, demographic variables, tobacco smoking, and obesity, and also the partial explained variance using regression methods. We also determined the association between psychiatric medications and MMP-9 levels.

Results

Individuals with elevated MMP-9 levels had higher odds of schizophrenia or bipolar disorder compared with the nonpsychiatric group adjusted for demographic variables. Partial correlation analyses indicated the demographic-adjusted variance associated with MMP-9, smoking, obesity, and their interaction explained 59.6% for schizophrenia and 39.9% for bipolar disorder. Levels of MMP-9 were substantially lower in individuals receiving valproate, particularly relatively high doses.

Conclusions

Individuals with higher levels of MMP-9 have significantly higher odds of schizophrenia or bipolar disorder. Individuals receiving valproate had substantially lower levels of MMP-9, possibly related to its ability to inhibit histone deacetylation. A substantial portion of the variance in clinical disorders associated with MMP-9 can be attributed to smoking or obesity. Interventions to reduce smoking and obesity might reduce the morbidity and mortality associated with elevated MMP-9 levels and improve the health outcomes of individuals with these disorders.

Disability and quality of life in patients with treatment-resistant schizophrenia on long- term clozapine therapy

Objectives

To assess disability and quality of life (QOL) in treatment resistant schizophrenia (TRS) on long term clozapine therapy and assess their correlation with positive, negative and cognitive symptoms.

Methodology

Disability and QOL in forty patients with TRS (as per modified Kane's criteria) were assessed using World Health Organization Disability Assessment Schedule 2.0 and World Health Organization Quality of Life-BREF. Scale for assessment of positive symptoms, scale for assessment of negative symptoms and Addenbrooke's cognitive examination-III were used to assess positive, negative and cognitive symptoms. Medication adherence rating scale assessed medication adherence.

Results

Disability and QOL correlated significantly with medication adherence, negative and cognitive symptoms but not with positive symptoms. Subgroup analysis revealed significant difference between medication adherence (good vs poor) and cognitive (impairment vs non-impairment) groups.

Conclusion

Negative and cognitive symptoms, and medication adherence correlated with disability and QOL.

Characterization of early psychosis patients carrying a genetic vulnerability to redox dysregulation: a computational analysis of mechanism-based gene expression profile in fibroblasts

In view of its heterogeneity, schizophrenia needs new diagnostic tools based on mechanistic biomarkers that would allow early detection. Complex interaction between genetic and environmental risk factors may lead to NMDAR hypofunction, inflammation and redox dysregulation, all converging on oxidative stress. Using computational analysis, the expression of 76 genes linked to these systems, known to be abnormally regulated in schizophrenia, was studied in skin-fibroblasts from early psychosis patients and age-matched controls (N = 30), under additional pro-oxidant challenge to mimic environmental stress. To evaluate the contribution of a genetic risk related to redox dysregulation, we investigated the GAG trinucleotide polymorphism in the key glutathione (GSH) synthesizing enzyme, glutamate-cysteine-ligase-catalytic-subunit (gclc) gene, known to be associated with the disease. Patients and controls showed different gene expression profiles that were modulated by GAG-gclc genotypes in combination with oxidative challenge. In GAG-gclc low-risk genotype patients, a global gene expression dysregulation was observed, especially in the antioxidant system, potentially induced by other risks. Both controls and patients with GAG-gclc high-risk genotype (gclcGAG-HR) showed similar gene expression profiles. However, under oxidative challenge, a boosting of other antioxidant defense, including the master regulator Nrf2 and TRX systems was observed only in gclcGAG-HR controls, suggesting a protective compensation against the genetic GSH dysregulation. Moreover, RAGE (redox/inflammation interaction) and AGMAT (arginine pathway) were increased in the gclcGAG-HR patients, suggesting some additional risk factors interacting with this genotype. Finally, the use of a machine-learning approach allowed discriminating patients and controls with an accuracy up to 100%, paving the way towards early detection of schizophrenia.

Relation between Selected Sleep Parameters, Depression, Anti-Tumor Necrosis Factor Therapy, and the Brain-Derived Neurotrophic Factor Pathway in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) patients often have sleep and mood disorders. Brain-derived neurotrophic factor (BDNF) and proBDNF were shown to modulate interactions between the central nervous system and the gastrointestinal tract, possibly contributing to psychological issues. Anti-tumor necrosis factor (TNF) therapy in IBD can alter BDNF expression and further affect the brain-gut axis. Eighty IBD patients and 44 healthy controls (HCs) were enrolled and divided into subsets based on disease activity and condition (ulcerative colitis (UC)/Crohn's disease (CD)). Questionnaires evaluating sleep parameters and depression as well as venous blood were collected. The IBD group had a lower expression of BDNF mRNA, but higher proBDNF and BDNF protein concentration than HCs. The UC group had a higher BDNF protein concentration than the CD. BDNF protein was positively correlated to sleep efficiency in the IBD group. Depression severity was associated positively with BDNF mRNA and negatively with BDNF protein in the remission group. Anti-TNF therapy enhanced BDNF mRNA expression. The BDNF pathway might be disturbed in IBD, linking it to sleep disorders and depression. Systemic inflammation could be the main cause of this disruption. BDNF mRNA is a more reliable parameter than protein due to numerous post-translational modifications.

Longitudinal Changes in BDNF and MMP-9 Protein Plasma Levels in Children after Cochlear Implantation

Congenitally deaf children who undergo cochlear implantation before 1 year of age develop their auditory skills faster than children who are implanted later. In this longitudinal study, a cohort of 59 implanted children were divided into two subgroups according to their ages at implantation-below or above 1 year old-and the plasma levels of matrix metalloproteinase-9 (MMP-9), brain-derived neurotrophic factor (BDNF), and pro-BDNF were measured at 0, 8, and 18 months after cochlear implant activation, while auditory development was simultaneously evaluated using the LittlEARs Questionnaire (LEAQ). A control group consisted of 49 age-matched healthy children. We identified statistically higher BDNF levels at 0 months and at the 18-month follow-ups in the younger subgroup compared to the older one and lower LEAQ scores at 0 months in the younger subgroup. Between the subgroups, there were significant differences in the changes in BDNF levels from 0 to 8 months and in LEAQ scores from 0 to 18 months. The MMP-9 levels significantly decreased from 0 to 18 months and from 0 to 8 months in both subgroups and from 8 to 18 months only in the older one. For all measured protein concentrations, significant differences were identified between the older study subgroup and the age-matched control group.

Peripheral biomarkers of treatment-resistant schizophrenia: Genetic, inflammation and stress perspectives

Treatment-resistant schizophrenia (TRS) often results in severe disability and functional impairment. Currently, the diagnosis of TRS is largely exclusionary and emphasizes the improvement of symptoms that may not be detected early and treated according to TRS guideline. As the gold standard, clozapine is the most prescribed selection for TRS. Therefore, how to predict TRS in advance is critical for forming subsequent treatment strategy especially clozapine is used during the early stage of TRS. Although mounting studies have identified certain clinical factors and neuroimaging characteristics associated with treatment response in schizophrenia, the predictors for TRS remain to be explored. Biomarkers, particularly for peripheral biomarkers, show great potential in predicting TRS in view of their predictive validity, noninvasiveness, ease of testing and low cost that would enable their widespread use. Recent evidence supports that the pathogenesis of TRS may be involved in abnormal neurotransmitter systems, inflammation and stress. Due to the heterogeneity of TRS and the lack of consensus in diagnostic criteria, it is difficult to compare extensive results among different studies. Based on the reported neurobiological mechanisms that may be associated with TRS, this paper narratively reviews the updates of peripheral biomarkers of TRS, from genetic and other related perspectives. Although current evidence regarding biomarkers in TRS remains fragmentary, when taken together, it can help to better understand the neurobiological interface of clinical phenotypes and psychiatric symptoms, which will enable individualized prediction and therapy for TRS in the long run.

The Role of Brain-Derived Neurotrophic Factor in Immune-Related Diseases: A Narrative Review

Brain-derived neurotrophic factor (BDNF) is a neurotrophin regulating synaptic plasticity, neuronal excitability, and nociception. It seems to be one of the key molecules in interactions between the central nervous system and immune-related diseases, i.e., diseases with an inflammatory background of unknown etiology, such as inflammatory bowel diseases or rheumatoid arthritis. Studies show that BDNF levels might change in the tissues and serum of patients during the course of these conditions, e.g., affecting cell survival and modulating pain severity and signaling pathways involving different neurotransmitters. Immune-related conditions often feature psychiatric comorbidities, such as sleep disorders (e.g., insomnia) and symptoms of depression/anxiety; BDNF may be related as well to them as it seems to exert an influence on sleep structure; studies also show that patients with psychiatric disorders have decreased BDNF levels, which increase after treatment. BDNF also has a vital role in nociception, particularly in chronic pain, hyperalgesia, and allodynia, participating in the formation of central hypersensitization. In this review, we summarize the current knowledge on BDNF's function in immune-related diseases, sleep, and pain. We also discuss how BDNF is affected by treatment and what consequences these changes might have beyond the nervous system.

Unraveiling the correlation among neurodevelopmental and inflammatory biomarkers in patients with chronic schizophrenia

INTRODUCTION

Nuclear distribution element like-1 (Ndel1) is a cytosolic oligopeptidase, which was suggested as a potential biomarker of aberrant neurodevelopment and early stage of schizophrenia (SCZ). The involvement of Ndel1 in neurite outgrowth, neuronal migration and neurodevelopment was demonstrated. Moreover, Ndel1 cleaves neuropeptides, including the endogenous antipsychotic peptide neurotensin, and lower Ndel1 activity was reported in SCZ patients compared with healthy controls (HCs). Changes in brain-derived neurotrophic factor (BDNF) and inflammatory cytokines levels were also implicated in SCZ.

OBJECTIVE

This preliminary study aimed to investigate the interactions between these immune and neurodevelopmental/neurotrophic biomarkers, namely BDNF and the recently identified SCZ biomarker Ndel1.

RESULTS

We observed lower Ndel1 activity and IL-4 levels, and higher BDNF levels, in plasma of SCZ (N = 23) compared with HCs (N = 29). Interestingly, significant correlation between Ndel1 activity and IL-4 levels was observed in SCZ, while no correlation with any other evaluated interleukins (namely IL-2, IL-8, IL-10 and IL-17A) or BDNF levels was noticed.

CONCLUSION

Although this hypothesis needs to be further explored for a better understanding of the mechanisms by which these altered pathways are associated to each other in SCZ, we suggest that Ndel1 and the inflammatory marker IL-4 are directly correlated.

Schizophrenia-derived hiPSC brain microvascular endothelial-like cells show impairments in angiogenesis and blood-brain barrier function

Schizophrenia (SZ) is a complex neuropsychiatric disorder, affecting 1% of the world population. Long-standing clinical observations and molecular data have pointed to a possible vascular deficiency that could be acting synergistically with neuronal dysfunction in SZ. As SZ is a neurodevelopmental disease, the use of human-induced pluripotent stem cells (hiPSC) allows disease biology modeling while retaining the patient's unique genetic signature. Previously, we reported a VEGFA signaling impairment in SZ-hiPSC-derived neural lineages leading to decreased angiogenesis. Here, we present a functional characterization of SZ-derived brain microvascular endothelial-like cells (BEC), the counterpart of the neurovascular crosstalk, revealing an intrinsically defective blood-brain barrier (BBB) phenotype. Transcriptomic assessment of genes related to endothelial function among three control (Ctrl BEC) and five schizophrenia patients derived BEC (SZP BEC), revealed that SZP BEC have a distinctive expression pattern of angiogenic and BBB-associated genes. Functionally, SZP BEC showed a decreased angiogenic response in vitro and higher transpermeability than Ctrl BEC. Immunofluorescence staining revealed less expression and altered distribution of tight junction proteins in SZP BEC. Moreover, SZP BEC's conditioned media reduced barrier capacities in the brain microvascular endothelial cell line HCMEC/D3 and in an in vivo permeability assay in mice. Overall, our results describe an intrinsic failure of SZP BEC for proper barrier function. These findings are consistent with the hypothesis tracing schizophrenia origins to brain development and BBB dysfunction.

Exploring the intersection of the microbiome and the developing brain: Impacts on schizophrenia risk

Recent findings show that the perinatal maternal and infant microbiomes have profound potential to impact long term health outcomes. Of particular interest are the ways in which the microbiome influences the developing brain during one of its most critical windows. Schizophrenia and psychosis risk are strongly connected to disruptions in perinatal neurodevelopment. In this review we present an overview of critical aspects in development of both the microbiome and brain, discuss their overlap, and consider what role the microbiome plays in schizophrenia risk during the perinatal window. Considering this, we discuss ways in which expecting and new mothers may reduce offspring schizophrenia risk.

The tetrapartite synapse in neuropsychiatric disorders: Matrix metalloproteinases (MMPs) as promising targets for treatment and rational drug design

Inflammation and an exacerbated immune response are widely accepted contributing mechanisms to the genesis and progression of major neuropsychiatric disorders. However, despite the impressive advances in understanding the neurobiology of these disorders, there is still no approved drug directly linked to the regulation of inflammation or brain immune responses. Importantly, matrix metalloproteinases (MMPs) comprise a group of structurally related endopeptidases primarily involved in remodeling extracellular matrix (ECM). In the central nervous system (CNS), these proteases control synaptic plasticity and strength, patency of the blood-brain barrier, and glia-neuron interactions through cleaved and non-cleaved mediators. Several pieces of evidence have pointed to a complex scenario of MMPs dysregulation triggered by neuroinflammation. Furthermore, major psychiatric disorders' affective symptoms and neurocognitive abnormalities are related to MMPs-mediated ECM changes and neuroglia activation. In the past decade, research efforts have been directed to broad-spectrum MMPs inhibitors with frustrating clinical results. However, in the light of recent advances in combinatorial chemistry and drug design technologies, specific and CNS-oriented MMPs modulators have been proposed as a new frontier of therapy for regulating ECM properties in the CNS. Therefore, here we aim to discuss the state of the art of MMPs and ECM abnormalities in major neuropsychiatric disorders, namely depression, bipolar disorder, and schizophrenia, the possible neuro-immune interactions involved in this complex scenario of MMPs dysregulation and propose these endopeptidases as promising targets for rational drug design.

Changes in serum levels of brain-derived neurotrophic factor with electroconvulsive therapy and pharmacotherapy and its clinical correlates in male schizophrenia patients

OBJECTIVES

It has been postulated that neurotrophin dysregulation leads to disorganisation in neuronal networks, which results in schizophrenia. The current study sets out to evaluate if the finding of lower brain-derived neurotrophic factor (BDNF) levels in schizophrenia patients could be confirmed in an independent cohort and to investigate if the BDNF levels can be altered with different treatment modalities such as electroconvulsive therapy (ECT) and/or antipsychotic pharmacotherapy (PT).

METHODS

A total of 54 male patients with schizophrenia and 35 healthy controls were included in the study. Schizophrenia patients were subdivided into two groups as the ones who underwent ECT + PT and only PT. Clinical and sociodemographic data questionnaire, Positive and Negative Syndrome Scale (PANSS) and blood sample collection for BDNF assessment were applied to all patients (on first and last days of admissions) and healthy participants (on the day of the interview). Then, clinical parameters and blood sample outcomes were statistically analysed.

RESULTS

Mean BDNF levels of healthy individuals were significantly higher than mean pre- and post-treatment BDNF levels in both PT only and ECT + PT groups. While serum BDNF levels did not increase after ECT + PT, there was a trend level increase in the PT only group. There was no significant correlation between the changes in serum BDNF levels with total PANSS scores in either group after treatment.

CONCLUSIONS

We could confirm previously suggested data of lower serum BDNF levels in schizophrenia patients compared to healthy population but we could not find significant increase in serum BDNF levels with ECT + PT or only PT as some previous studies suggested.

Matrix metalloproteinase-3 serum levels in schizophrenic patients

OBJECTIVES

It has been reported that matrix metalloproteinase, MMP-3 may play a significant role in the pathophysiology of mental disorders. However, there are no data on the level of MMP-3 in people suffering from schizophrenia, or its influence on the mental state of these people. The aim of this study was to investigate the effect of an antipsychotic treatment on the blood levels of MMP-3, as well as investigating its relationship with insight into schizophrenia.

METHODS

Thirty people with schizophrenia were included in the study. The concentration of MMP-3 in the blood serum was assessed using enzyme-linked immunosorbent assay. Insight into the disease was assessed using the Beck Cognitive Insight Scale.

RESULTS

The antipsychotic treatment applied decreased the levels of MMP-3 in patients with schizophrenia (p = 0.005), however, the statistically significant interaction (p = 0.02) indicates that the decrease only concerned men. There was also a statistically significant correlation between the level of MMP-3 and insight into the disease (p = 0.02).

CONCLUSION

MMP-3 may be associated with gender, treatment and symptoms in schizophrenic patients.KEY POINTSMMP3 could be used as a potential biomarker for schizophrenia.The level of MMP-3 decreased due to the applied antipsychotic treatment.The higher the level of MMP-3 in a group of people with schizophrenia, the better insight into their disease.

Prospective cohort study reveals MMP-9, a neuroplasticity regulator, as a prediction marker of cochlear implantation outcome in prelingual deafness treatment

Because of vast variability of cochlear implantation outcomes in prelingual deafness treatment, identification of good and poor performers remains a challenging task. To address this issue, we investigated genetic variants of matrix metalloproteinase 9 (MMP9) and brain-derived neurotrophic factor (BDNF) and plasma levels of MMP-9, BDNF, and pro-BDNF that have all been implicated in neuroplasticity after sensory deprivation in the auditory pathway. We recruited a cohort of prelingually deaf children, all implanted before the age of 2, and carried out a prospective observation (N = 61). Next, we analyzed the association between (i) functional MMP9 (rs20544, rs3918242, rs2234681) and BDNF (rs6265) gene variants (and their respective protein levels) and (ii) the child’s auditory development as measured with the LittlEARS Questionnaire (LEAQ) before cochlear implant (CI) activation and at 8 and 18 months post-CI activation. Statistical analyses revealed that the plasma level of MMP-9 measured at implantation in prelingually deaf children was significantly correlated with the LEAQ score 18 months after CI activation. In the subgroup of DFNB1-related deafness (N = 40), rs3918242 of MMP9 was significantly associated with LEAQ score at 18 months after CI activation; also, according to a multiple regression model, the ratio of plasma levels of pro-BDNF/BDNF measured at implantation was a significant predictor of overall LEAQ score at follow-up. In the subgroup with DFNB1-related deafness, who had CI activation after 1 year old (N = 22), a multiple regression model showed that rs3918242 of MMP9 was a significant predictor of overall LEAQ score at follow-up.

Association of BDNF and MMP-9 single-nucleotide polymorphisms with the clinical phenotype of schizophrenia

OBJECTIVE

Schizophrenia is a highly polygenic psychiatric disorder; however, the complex genetic architecture underlying the pathogenesis remains elusive. Brain-derived neurotrophic factor (BDNF), a neurotrophin, and matrix metalloproteinase 9 (MMP-9), a gelatinase B, are the promising candidate genes for schizophrenia. To shed new light on the relationship between the single-nucleotide polymorphisms (SNPs) of BDNF and MMP-9 and the clinical variability of schizophrenia phenotype, this study aims to evaluate the relationship, and provide more definitive evidence for the relationship with various clinical features of schizophrenia.

METHODS

A case-control association study was performed, and one hundred and five subjects of Chinese Han population were enrolled, including 55 schizophrenia patients (SP) and 50 healthy controls (HC). The BDNF rs6265 196 G > A and MMP-9 rs3918242 -1562C > T SNPs were genotyped using PCR-RFLP assay. The Positive and Negative Syndrome Scale (PANSS) was used to assess the clinical symptoms of patients with schizophrenia.

RESULTS

Compared with HC, the frequency of SP carrying BDNF rs6265 GG/GA genotype was significantly higher than HC, and the frequency of SP carrying BDNF rs6265 AA genotype was significantly lower than HC (p < 0.01). With regards to MMP-9 rs3918242 -1562C > T SNP, no significant difference was observed between the control and SP. BDNF GG genotype showed significantly higher PANSS and positive symptoms score than GA and AA genotypes (P < 0.01). MMP-9 CC genotype showed significantly higher PANSS and general score than CT and TT genotypes (P < 0.05).

CONCLUSION

BDNF rs6265 196 G > A and MMP-9 rs3918242-1562C > T SNPs are related to the clinical features of schizophrenia and could be a useful biomarker for the changes, remission or deterioration of clinical status of schizophrenia.

The association of matrix metalloproteinase 9 (MMP9) with hippocampal volume in schizophrenia: a preliminary MRI study

Matrix metalloproteinases 9 (MMP9) are enzymes involved in regulating neuroplasticity in the hippocampus. This, combined with evidence for disrupted hippocampal structure and function in schizophrenia, has prompted our current investigation into the relationship between MMP9 and hippocampal volumes in schizophrenia. 34 healthy individuals (mean age = 32.50, male = 21, female = 13) and 30 subjects with schizophrenia (mean age = 33.07, male = 19, female = 11) underwent a blood draw and T1-weighted magnetic resonance imaging. The hippocampus was automatically segmented utilizing FreeSurfer. MMP9 plasma levels were measured with ELISA. ANCOVAs were conducted to compare MMP9 plasma levels (corrected for age and sex) and hippocampal volumes between groups (corrected for age, sex, total intracranial volume). Spearman correlations were utilized to investigate the relationship between symptoms, medication, duration of illness, number of episodes, and MMP9 plasma levels in patients. Last, we explored the correlation between MMP9 levels and hippocampal volumes in patients and healthy individuals separately. Patients displayed higher MMP9 plasma levels than healthy individuals (F(1, 60) = 21.19, p < 0.0001). MMP9 levels correlated with negative symptoms in patients (R = 0.39, p = 0.035), but not with medication, duration of illness, or the number of episodes. Further, patients had smaller left (F(1,59) = 9.12, p = 0.0040) and right (F(1,59) = 6.49, p = 0.013) hippocampal volumes. Finally, left (R = -0.39, p = 0.034) and right (R = -0.37, p = 0.046) hippocampal volumes correlated negatively with MMP9 plasma levels in patients. We observe higher MMP9 plasma levels in SCZ, associated with lower hippocampal volumes, suggesting involvement of MMP9 in the pathology of SCZ. Future studies are needed to investigate how MMP9 influences the pathology of SCZ over the lifespan, whether the observed associations are specific for schizophrenia, and if a therapeutic modulation of MMP9 promotes neuroprotective effects in SCZ.

FEATURES OF SOCIAL DYSFUNCTION, ASSESSMENT OF LEVELS OF SOCIAL FRUSTRATION AND SATISFACTION WITH THE QUALITY OF MEDICAL CARE IN PATIENTS WITH SCHIZOPHRENIA ON THE BACKGROUND OF SOMATIC COMORBIDITY

OBJECTIVE

The aim: To study the features of social dysfunction, assess the levels of social frustration and satisfaction with the quality of medical care in patients with schizophrenia on the background of somatic comorbidity.

PATIENTS AND METHODS

Materials and methods: The study included 105 patients (55 women - 52.38% and 50 men - 47.61%) with a verified diagnosis of schizophrenia (F20.0-F20.3). The psychopathological condition of patients was assessed according to the "Positive and Negative Syndrome Scale" (PANSS). A special psychodiagnostic technique by L. I. Wasserman in the modification of V.V. Boiko was used to assess the level of social frustration. Peculiarities of social dysfunction were assessed based on the "Personal and Social Performance scale" (PSP). "The Health Resource Use Questionnaire" was used to obtain the information about the coverage of this patient with primary or specialized somatic care during the last three months. General and systematic examination of the patient was also performed, physical methods of diagnosis (palpation, percussion, auscultation) were applied, body mass index was calculated. Consultations of specialists, instrumental (ECG, ultrasound, Echo-CS, etc.) and laboratory diagnostic methods were prescribed depending on the detection or suspicion of concomitant somatic pathology.

RESULTS

Results: The results showed significant social isolation of the respondents, their contacts were limited to communication with relatives and friends. This was confirmed by the data of social functioning on the PSP scale, according to which the most pronounced violations in the examined patients were found in the areas of "personal and social relationships", "socially useful activities, including work and study". It should be noted that the higher the rates of social dysfunction, the stronger the level of frustration (p<0.05). In particular, the low level of satisfaction with the field of medical services due to its inaccessibility, according to respondents, attracts attention. According to the relatives, the main reason for this restriction was the patients' lack of awareness of their condition, neglect and indifference.

CONCLUSION

Conclusions: Further attention is required to develop strategies to improve comorbid treatment in the patients with schizophrenia regardless of whether this situation is the result of negative attitude of health professionals towards patients with mental illness, or the result of the patients' ignorance of their physical condition, or other factors.

Role of matrix metalloproteinase-9 in neurodevelopmental deficits and experience-dependent plasticity in Xenopus laevis

Matrix metalloproteinase-9 (MMP-9) is a secreted endopeptidase targeting extracellular matrix proteins, creating permissive environments for neuronal development and plasticity. Developmental dysregulation of MMP-9 may also lead to neurodevelopmental disorders (ND). Here, we test the hypothesis that chronically elevated MMP-9 activity during early neurodevelopment is responsible for neural circuit hyperconnectivity observed in Xenopus tadpoles after early exposure to valproic acid (VPA), a known teratogen associated with ND in humans. In Xenopus tadpoles, VPA exposure results in excess local synaptic connectivity, disrupted social behavior and increased seizure susceptibility. We found that overexpressing MMP-9 in the brain copies effects of VPA on synaptic connectivity, and blocking MMP-9 activity pharmacologically or genetically reverses effects of VPA on physiology and behavior. We further show that during normal neurodevelopment MMP-9 levels are tightly regulated by neuronal activity and required for structural plasticity. These studies show a critical role for MMP-9 in both normal and abnormal development.

Kinetics of serum brain-derived neurotrophic factor (BDNF) concentration levels in epileptic patients after generalized tonic-clonic seizures

OBJECTIVE

Epilepsy is a chronic neurological disorder characterized by the periodic and unpredictable occurrence of seizures. The serum level of brain-derived neurotrophic factor (BDNF) has been suggested to be a potential biomarker that could detect differences in epilepsy patients. Although there is considerable neurobiological evidence linking BDNF to epilepsy, only a small number of studies investigated the relationship between BDNF serum levels and epilepsy, and these studies obtained inconsistent results. The aim of this study was to elucidate BDNF serum levels in epilepsy cases.

METHODS

Collectively, group of 143 patients (n = 143) were included in this study and subsequently divided into two groups consisting of individuals after singular generalized tonic-clonic seizures (n = 50) and patients with chronic epilepsy (n = 93). The samples from patients with acute epilepsy were collected 1-3 hours and 72 h after seizure, and a single collection was performed from patients with chronic epilepsy. These samples were compared to the control group (n = 48) using ELISA.

RESULTS

In the present study, we observed a significant decrease of BDNF serum levels in patients after generalized tonic-clonic seizures compared to the control group. Furthermore, the observed decrease of BDNF levels in this group was sustained at 1 and 72 h after seizure insult. We did not show the relationship between BDNF levels and age, etiology of epilepsy and the duration of illness.

SIGNIFICANCE

Our results and the findings of previous studies indicate that the serum BDNF level significantly decreases after seizures and should be considered when measuring BDNF in patients with chronic epilepsy. It might be also influenced by neurodegenerative processes, which may be involved in the etiopathogenesis of particular epilepsy syndromes.

Novel matrix metalloproteinase inhibitors: an updated patent review (2014 - 2020)

Introduction: Matrix MetalloProteinases (MMPs) are key enzymes in several pathophysiological processes connected to the extracellular matrix (ECM) degradation. Earlier clinical trials evaluating broad spectrum MMP inhibitors as cancer therapeutics failed to succeed, resulting in toxic side effects, such as musculoskeletal pain and inflammation, due to poor selectivity. As it is now recognized that some MMPs are essential for tumor progression and metastasis, but others play host-protective functions, selective MMP inhibitors are needed, and their interest has grown also for therapeutic applications beyond cancer, such as infectious, inflammatory and neurological diseases. Areas covered: This updated review describes patents concerning MMP inhibitors published within January 2014 and June 2020, with therapeutic applications spanning from cancer to inflammatory and neurological disorders. Expert opinion: Although the number of patents has decreased with respect to the previous decade, new applications provide selective matrix metalloproteinase inhibitors for therapeutic treatments beyond cancer. For several applications, the need of selective inhibitors resulted in the development of new non-hydroxamate compounds, paving the way towards a renewed interest towards MMPs as therapeutic targets. In particular, inhibitors able to cross the blood-brain barrier have been disclosed and proposed for the treatment of neurological conditions, infections, wound healing and cancer.

Matrix metalloproteinase-9 increases the risk of cognitive impairment in schizophrenia

PURPOSE OF THE ARTICLE

Synaptic plasticity is known to play role in pathogenesis of schizophrenia. Cognitive impairment is one of the complications of schizophrenia, leading to poor quality of life. Matrix metalloprotease-9 (MMP-9) and neurotrophin-3 (NT-3) are markers of synaptic plasticity, widely investigated in neuropsychiatric disorders. The objective of the study was to investigate the levels of MMP-9 and NT-3 and their association with cognitive impairment in schizophrenia.

MATERIAL AND METHODS

124 schizophrenia patients and 124 controls were enrolled in the study. MMP-9 and NT-3 were estimated in both the groups using ELISA. Cognition was assessed using Addenbrooke cognitive examination-III (ACE-III) and disease severity was assessed using PANSS.

RESULTS

MMP-9 (p = .003) and NT -3 (p < .001) were found to be elevated in schizophrenia cases compared to controls. There was significant association of MMP-9 with fluency (r = -0.195, p = .030), language (r = -0.196, p = .029) and total ACE-III scores (r = -0.197, p = .029). Also we observed that MMP-9 increases the risk of cognitive impairment in schizophrenia patients (OR = 2.509, CI= 1.215 - 5.18, p = .013).

CONCLUSION

MMP-9 and NT-3 are elevated in schizophrenia. MMP-9 was associated with fluency and language component of cognition and increases the risk of cognitive impairment in schizophrenia.

Matrix Metalloproteinase 9 Blood Alterations in Patients With Schizophrenia Spectrum Disorders: A Systematic Review and Meta-Analysis

BACKGROUND

Matrix metalloproteinase 9 (MMP-9), an extracellular network protease implicated in glutamatergic signaling, may be part of the pathophysiology of schizophrenia spectrum disorders (SSD).

METHODS

We performed a systematic review in PubMed/Embase until July 15, 2020, conducting a random-effects meta-analysis of studies comparing MMP-9 blood levels in SSD vs healthy controls (HCs) and psychiatric controls (PCs), calculating between-group differences in standardized mean differences (SMDs) ± 95% confidence intervals (CIs). Meta-regression analyses included sex, age, illness duration, antipsychotic dose, and Positive and Negative Syndrome Scale (PANSS) total/subscales. Subgroup analyses included first-episode patients (FEP) vs non-FEP, each vs HCs and vs PCs, and blood sample type. Study quality was assessed using the Newcastle-Ottawa scale.

RESULTS

Four, five, and two trials were rated as high, fair, and low quality. In 11 studies (n = 1443), 643 patients (age = 36.7 ± 14.1 years, females = 42.9%) were compared with HCs (n = 631), with 4 studies including also 169 PCs. MMP-9 levels were higher in SSD vs HCs (SMD = 0.52, 95%CI = 0.20-0.85, P = .002), but not in PCs vs HCs (n = 132, after removing one implausible outlier [SMD = 0.33, 95%CI = -0.16 to 0.85, P = .082]). MMP-9 differences between SSD and HCs were associated with higher PANSS total (coefficient = 0.02, 95%CI = 0.01-0.02, P < .001), PANSS positive (coefficient = 0.08, 95%CI = 0.02-0.13, P = .006), and PANSS general scores (coefficient = 0.02, 95%CI = 0.01-0.03, P < .001). MMP-9 level differences vs HCs did not vary significantly between FEP (n = 103, SMD = 0.44, 95%CI = 0.15-0.72, P = .71) and non-FEP patients (n = 466, SMD = 0.59, 95%CI = 0.38-0.80; P = .34) (FEP vs non-FEP: P = .39). In four high-quality studies, MMP-9 levels remained significantly higher in SSD vs HCs (SMD = 0.82, 95%CI = 0.03-1.61).

CONCLUSIONS

Findings suggest MMP-9 upregulation in SSD, requiring further validation and understanding of related pathways.

Aberrant glycosylation in schizophrenia: a review of 25 years of post-mortem brain studies

Glycosylation, the enzymatic attachment of carbohydrates to proteins and lipids, regulates nearly all cellular processes and is critical in the development and function of the nervous system. Axon pathfinding, neurite outgrowth, synaptogenesis, neurotransmission, and many other neuronal processes are regulated by glycans. Over the past 25 years, studies analyzing post-mortem brain samples have found evidence of aberrant glycosylation in individuals with schizophrenia. Proteins involved in both excitatory and inhibitory neurotransmission display altered glycans in the disease state, including AMPA and kainate receptor subunits, glutamate transporters EAAT1 and EAAT2, and the GABA_A receptor. Polysialylated NCAM (PSA-NCAM) and perineuronal nets, highly glycosylated molecules critical for axonal migration and synaptic stabilization, are both downregulated in multiple brain regions of individuals with schizophrenia. In addition, enzymes spanning several pathways of glycan synthesis show differential expression in brains of individuals with schizophrenia. These changes may be due to genetic predisposition, environmental perturbations, medication use, or a combination of these factors. However, the recent association of several enzymes of glycosylation with schizophrenia by genome-wide association studies underscores the importance of glycosylation in this disease. Understanding how glycosylation is dysregulated in the brain will further our understanding of how this pathway contributes to the development and pathophysiology of schizophrenia.

Platelets Selectively Regulate the Release of BDNF, But Not That of Its Precursor Protein, proBDNF

Background

Brain-derived neurotrophic factor (BDNF) plays a role in synaptic plasticity and neuroprotection. BDNF has well-established pro-survival effects, whereas its precursor protein, proBDNF, induces apoptosis. Thus, it has been suggested that the proBDNF/BDNF ratio could be an indicator of neuronal health. Access to neurons is, understandably, limited. Because of their similarities, platelets have been put forward as a non-invasive biomarker of neuronal health; indeed, they store large quantities of BDNF and can release it into circulation upon activation, similarly to neurons. However, whether platelets also express the precursor proBDNF protein remains unknown. We therefore sought to characterize proBDNF levels in human platelets and plasma.

Methods

The presence of proBDNF was assessed by immunoblotting, cell fractionation, flow cytometry, and confocal microscopy in washed platelets from 10 healthy volunteers. Platelets from 20 independent healthy volunteers were activated with several classical agonists and the release of BDNF and proBDNF into plasma was quantified by ELISA.

Results

Platelets expressed detectable levels of proBDNF (21 ± 13 fmol/250 x 10⁶ platelets). ProBDNF expression was mainly localized in the intracellular compartment. The proBDNF to BDNF molar ratio was ~1:5 in platelets and 10:1 in plasma. In stark contrast to the release of BDNF during platelet activation, intraplatelet and plasma concentrations of proBDNF remained stable following stimulation with classical platelet agonists, consistent with non-granular expression.

Conclusions

Platelets express both the mature and the precursor form of BDNF. Whether the intraplatelet proBDNF to BDNF ratio could be used as a non-invasive biomarker of cognitive health warrants further investigation.

MMP9/RAGE pathway overactivation mediates redox dysregulation and neuroinflammation, leading to inhibitory/excitatory imbalance: a reverse translation study in schizophrenia patients

Various mechanisms involved in schizophrenia pathophysiology, such as dopamine dysregulation, glutamate/NMDA receptor dysfunction, neuroinflammation or redox imbalance, all appear to converge towards an oxidative stress "hub" affecting parvalbumine interneurones (PVI) and their perineuronal nets (PNN) (Lancet Psychiatry. 2015;2:258-70); (Nat Rev Neurosci. 2016;17:125-34). We aim to investigate underlying mechanisms linking oxidative stress with neuroinflammatory and their long-lasting harmful consequences. In a transgenic mouse of redox dysregulation carrying a permanent deficit of glutathione synthesis (gclm-/-), the anterior cingulate cortex presented early in the development increased oxidative stress which was prevented by the antioxidant N-acetylcysteine (Eur J Neurosci. 2000;12:3721-8). This oxidative stress induced microglia activation and redox-sensitive matrix metalloproteinase 9 (MMP9) stimulation, leading to the receptor for advanced glycation end-products (RAGE) shedding into soluble and nuclear forms, and subsequently to nuclear factor-kB (NF-kB) activation and secretion of various cytokines. Blocking MMP9 activation prevented this sequence of alterations and rescued the normal maturation of PVI/PNN, even if performed after an additional insult that exacerbated the long term PVI/PNN impairments. MMP9 inhibition thus appears to be able to interrupt the vicious circle that maintains the long-lasting deleterious effects of the reciprocal interaction between oxidative stress and neuroinflammation, impacting on PVI/PNN integrity. Translation of these experimental findings to first episode patients revealed an increase in plasma soluble RAGE relative to healthy controls. This increase was associated with low prefrontal GABA levels, potentially predicting a central inhibitory/excitatory imbalance linked to RAGE shedding. This study paves the way for mechanistically related biomarkers needed for early intervention and MMP9/RAGE pathway modulation may lead to promising drug targets.

Blood-brain barrier pathology in patients with severe mental disorders: a systematic review and meta-analysis of biomarkers in case-control studies

Background

Blood-brain barrier (BBB) pathology may be associated with mental disorders. The aim of this systematic review and meta-analysis is to identify, evaluate and summarize available evidence on whether potential biomarkers of BBB pathology are altered in patients with schizophrenia spectrum disorders, major depression and bipolar disorder compared to healthy controls.

Methods

The primary outcome is blood S100B, while secondary outcomes include biomarkers in blood and/or cerebrospinal fluid, i.e. albumin ratio, fibrinogen, immunoglobulin G, glial fibrillary acidic protein, amyloid beta (Aβ), matrix metalloproteinases (MMPs), tissue inhibitors of metalloproteinases, endothelial glycocalyx constituents, and cell adhesion molecules (CAMs). A systematic search in PubMed, Embase and PsycINFO resulted in 131 eligible studies, of which 93 were included in the meta-analysis. Meta- and subgroup analyses were undertaken using random-effects modelling. The protocol was a priori registered on PROSPERO (CRD42020152721).

Results

S100B was increased in schizophrenia spectrum disorders (24 studies; 1107 patients; standardized mean difference (SMD) ​= ​0.82; 95% confidence interval (CI) ​= ​0.51 to 1.13; I² ​= ​90%), major depression (13 studies; 584 patients; SMD ​= ​0.57; 95% CI ​= ​0.31 to 0.83; I² ​= ​73%) and bipolar disorder (4 studies; 142 patients; SMD ​= ​0.55; 95% CI ​= ​0.16 to 0.94; I² ​= ​48%). Similarly, numerous secondary outcomes, including albumin ratio, fibrinogen, Aβ, MMPs and CAMs, were altered. Results of the included studies varied considerably, and important confounders were often not accounted for.

Conclusions

The findings implicate occurrence of BBB pathology in patients with schizophrenia spectrum disorders, major depression and bipolar disorder compared to healthy controls. However, definite conclusions cannot be drawn, mainly because the investigated biomarkers are indirect measures of BBB pathology.

•

The blood-brain barrier (BBB) can be studied indirectly through markers in blood and CSF.

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Markers of BBB pathology were altered in schizophrenia, depression and bipolar disorder.

•

The findings implicate occurrence of BBB pathology in patients compared to controls.

•

BBB pathology is expected to contribute to the pathogenesis of severe mental disorders.

A conceptualized model linking matrix metalloproteinase-9 to schizophrenia pathogenesis

Matrix metalloproteinase 9 (MMP-9) is an extracellularly operating zinc-dependent endopeptidase that is commonly expressed in the brain, other tissues. It is synthesized in a latent zymogen form known as pro-MMP-9 that is subsequently converted to the active MMP-9 enzyme following cleavage of the pro-domain. Within the central nervous system, MMP-9 is localized and released from neurons, astrocytes and microglia where its expression levels are modulated by cytokines and growth factors during both normal and pathological conditions as well as by reactive oxygen species generated during oxidative stress. MMP-9 is involved in a number of key neurodevelopmental processes that are thought to be affected in schizophrenia, including maturation of the inhibitory neurons that contain the calcium-binding protein parvalbumin, developmental formation of the specialized extracellular matrix structure perineuronal net, synaptic pruning, and myelination. In this context, the present article provides a narrative synthesis of the existing evidence linking MMP-9 dysregulation to schizophrenia pathogenesis. We start by providing an overview of MMP-9 involvement in brain development and physiology. We then discuss the potential mechanisms through which MMP-9 dysregulation may affect neural circuitry maturation as well as how these anomalies may contribute to the disease process of schizophrenia. We conclude by articulating a comprehensive, cogent, and experimentally testable hypothesis linking MMP-9 to the developmental pathophysiologic cascade that triggers the onset and sustains the chronicity of the illness.

Plasma levels of matrix metalloproteinase-9 (MMP-9) are associated with cognitive performance in patients with schizophrenia

Aim

Matrix metalloproteinase‐9 (MMP‐9) has been shown to modulate synaptic plasticity and may contribute to the pathophysiology of schizophrenia. This study investigated the peripheral levels of MMP‐9 and its association with cognitive functions in patients with schizophrenia to see the possible involvement of MMP‐9 in pathophysiology of schizophrenia, especially in cognitive decline.

Methods

We measured the plasma levels of MMP‐9 in 257 healthy controls and 249 patients with schizophrenia, including antipsychotic drug–free patients. We also explored the possible association between plasma MMP‐9 levels and cognitive performance in healthy controls and patients with schizophrenia using the Wechsler Adult Intelligence Scale, Third Edition (WAIS‐ III), the Wechsler Memory Scale‐Revised (WMS‐R), and the Rey Auditory Verbal Learning Test (AVLT).

Results

We found that the plasma levels of MMP‐9 were significantly higher in patients with schizophrenia, including antipsychotic drug–free patients, than in healthy controls. We found a significant negative association between plasma MMP‐9 levels and cognitive performance in controls and patients with schizophrenia.

Conclusion

Together, these convergent data suggest a possible biological mechanism for schizophrenia, whereby increased MMP‐9 levels are associated with cognitive impairment.

Plasma levels of MMP‐9 were significantly higher in patients with schizophrenia and significant negative association between plasma MMP‐9 levels and cognitive performance was observed in controls and patients with schizophrenia.

The Clinical Effect of Electroconvulsive Therapy and Its Relationship with Serum Levels of MMP-9 and CXCL12 in Patients with Mania

INTRODUCTION

Electroconvulsive therapy (ECT) is a non-pharmacological method for the treatment of psychiatric disorders. The precise biochemical mechanism of the effects of ECT is not clear, and since the two factors including matrix metalloproteinase-9 (MMP-9) and stromal cell-derived factor-1 alpha (CXCL12) play an important role in improving nerve damage, the effects of ECT and its relation with serum levels of MMP-9 and CXCL12 in patients with mania were investigated in this study.

METHODS

In this before and after intervention study, the patients with mania, referring to the Qods Hospital in Sanandaj, were selected by the census method during the years 2015-2018. Young's test was performed 24 hrs before and after the first, third, and sixth sessions of ECT. For biochemical analysis, 3 mL of peripheral blood were taken prior to any anesthesia and 6 hrs after the first, third, and sixth sessions. Data were analyzed by two-way ANOVA and Pearson correlation coefficient by using the SPSS16 software.

RESULTS

The results showed a significant decrease in Young's test scores during the first to the sixth session of ECT (P≤0.05). Although the levels of CXCL12 were slightly increased after the sixth course of ECT, they were not significant. Moreover, there were no significant relationship between the Young's test score and the serum levels of both MMP-9 and CXCL12 (P≥0.05).

CONCLUSION

ECT improved patients clinically, but this effect was independent of serum levels of MMP-9 and CXCL12, and possibly other biochemical factors are involved in this pathway.

Does metabolic status affect serum levels of BDNF and MMP-9 in patients with schizophrenia?

The purpose of the article: Brain-derived neurotrophic factor (BDNF) and matrix metalloproteinase-9 (MMP-9) are involved in the processes of neurogenesis, synaptic plasticity, learning and memory. Growing number of studies shows a relationship between BDNF or MMP-9 and schizophrenia. Also, BDNF and MMP-9 levels may be affected by metabolic parameters, such as obesity or dyslipidemia. Our hypothesis is that alterations of BDNF or MMP-9 levels in schizophrenia might be secondary to metabolic abnormalities, often found among schizophrenia patients. Materials and methods: We have compared BDNF and MMP-9 between patients with schizophrenia (n = 64, age 49 ± 8.2 y) and healthy controls (n = 32, age 51 ± 8.9 y) in the context of cardio-metabolic parameters. Serum levels of BDNF and MMP-9 were measured using ELISA test, body composition parameters were determined using bioelectric impedance analysis. Results and conclusions: Our results showed significantly lowered serum BDNF concentration in the schizophrenia group (schizophrenia: 23.8 ± 7.83 ng/mL, control: 27.69 ± 8.11 ng/mL, p = 0.03). Serum MMP-9 concentration in schizophrenia group did not differ compared with the control group (schizophrenia: 456.8 ± 278.4 ng/mL, control: 341.5 ± 162.4 ng/mL, p = 0.07). After adjusting for age, all anthropometric parameters, body composition and laboratory tests BDNF were still significantly lower in the schizophrenia group. However, MMP-9 became significantly elevated in the schizophrenia group after adjusting for several anthropometric and body composition covariates. Our results confirmed reduced serum BDNF concentration in patients with schizophrenia. Also, this reduction seems to be independent of metabolic abnormalities. On the other hand, our hypothesis that MMP-9 level in schizophrenia is altered due to metabolic abnormalities might be true.

MMPs in learning and memory and neuropsychiatric disorders

Matrix metalloproteinases (MMPs) are a group of over twenty proteases, operating chiefly extracellularly to cleave components of the extracellular matrix, cell adhesion molecules as well as cytokines and growth factors. By virtue of their expression and activity patterns in animal models and clinical investigations, as well as functional studies with gene knockouts and enzyme inhibitors, MMPs have been demonstrated to play a paramount role in many physiological and pathological processes in the brain. In particular, they have been shown to influence learning and memory processes, as well as major neuropsychiatric disorders such as schizophrenia, various kinds of addiction, epilepsy, fragile X syndrome, and depression. A possible link connecting all those conditions is either physiological or aberrant synaptic plasticity where some MMPs, e.g., MMP-9, have been demonstrated to contribute to the structural and functional reorganization of excitatory synapses that are located on dendritic spines. Another common theme linking the aforementioned pathological conditions is neuroinflammation and MMPs have also been shown to be important mediators of immune responses.

Increased plasma Brain-Derived Neurotrophic Factor (BDNF) levels in females with schizophrenia

Brain-Derived Neurotrophic Factor (BDNF) acts as a critical regulator of synaptogenesis and synaptic plasticity. Sex differences have been demonstrated in many aspects of schizophrenia. This study tested for sex-specific differences in peripheral BDNF levels in people with schizophrenia and healthy controls. We measured circulating plasma BDNF levels in 95 people with schizophrenia and 80 healthy controls. Plasma BDNF levels were significantly elevated in females with schizophrenia compared to males with schizophrenia and to female healthy controls. These results suggest that sex differences in peripheral BDNF levels may contribute to other sex related differences in schizophrenia.

[Electroconvulsive therapy in treatment of resistant schizophrenia: biological markers of efficacy and safety]

AIM

To evaluate clinical and biological efficacy and safety of electroconvulsive therapy (ECT) in patients with treatment-resistant paranoid schizophrenia.

MATERIAL AND METHODS

Determination of CNS specific biological markers (BDNF, NSE, S100B), together with markers of inflammation and CNS alteration (IL-2, CPK, CPK-MB), and clinical evaluation were performed in two groups of patients: the ECT + antipsychotic treatment group (n=66) and the antipsychotic treatment group (n=32).

RESULTS AND CONCLUSION

In the ECT + antipsychotic treatment group, the more pronounced reduction of psychotic symptoms has been revealed compared with subjects on antipsychotic treatment as monotherapy. Patients receiving ECT showed no increase in plasma levels of inflammation and CNS alteration biomarkers (NSE, S100B, CPK, CPK-MB, IL-2). The plasma level of BDNF, capable to characterize both the efficacy and safety of antipsychotic therapy, had a more pronounced upward trend in subjects with combined electroconvulsive and antipsychotic treatment, which may indicate good tolerability and high effectiveness of ECT.

Effect of lurasidone vs olanzapine on neurotrophic biomarkers in unmedicated schizophrenia: A randomized controlled trial

Neurotrophic factors like Brain-Derived Neurotrophic Factor (BDNF), Neurotrophin 3 (NT3) and Nerve Growth Factor (NGF), play a role in neuroplasticity and neurogenesis contributing to the pathogenesis of schizophrenia. The objective of the present study was to investigate and compare the effect of olanzapine and lurasidone on the change in serum neurotrophins in patients with schizophrenia. The present study was a randomized, open-label, active-controlled, parallel design clinical trial. After randomization baseline evaluations of serum BDNF, NGF, NT3, Positive and Negative Syndrome Scale (PANSS) scoring, Social and Occupational Functioning Assessment Scale (SOFAS) scoring of 101 unmedicated schizophrenia patients were done. Patients were reassessed after 6 weeks of monotherapy with olanzapine or lurasidone. Serum BDNF increased after treatment with both the drug groups but rise with olanzapine was found to be significantly higher (916.22; 95 %CI: 866.07 to 966.37; p < 0.001) in comparison to lurasidone. Increase in levels NGF and NT3 was also observed but there was no significant difference between the groups (NGF: 2.32; CI: 3.54 to -3.53; p = 0.57 and NT3: 0.99; CI: 2.11 to 0.14; p = 0.086). The difference in improvement in PANSS and SOFASS with both the drugs was not statistically significant. Both the drugs alleviate the symptoms of schizophrenia but olanzapine was better tolerated. Our findings suggest that increase in serum BDNF with olanzapine monotherapy is significantly higher than that with lurasidone but there is no significant difference in change in serum NGF and NT3. TRIAL REGISTRATION: ClinicalTrials.gov identifier: (NCT03304457).

Vitamin D in Synaptic Plasticity, Cognitive Function, and Neuropsychiatric Illness

Over a billion people worldwide are affected by vitamin D deficiency. Although vitamin D deficiency is associated with impaired cognition, the mechanisms mediating this link are poorly understood. The extracellular matrix (ECM) has now emerged as an important participant of synaptic plasticity and a new hypothesis is that vitamin D may interact with aggregates of the ECM, perineuronal nets (PNNs), to regulate brain plasticity. Dysregulation of PNNs caused by vitamin D deficiency may contribute to the presentation of cognitive deficits. Understanding the molecular mechanisms underpinning the role of vitamin D in brain plasticity and cognition could help identify ways to treat cognitive symptoms in schizophrenia and other neuropsychiatric conditions.

Sialic Acids in Neurology

Sialic acid (Sia) is involved in many biological activities and commonly occurs as a monosialyl residue at the nonreducing terminal end of glycoconjugates. The loss of activity of UDP-GlcNAc2-epimerase/ManNAc kinase, which is a key enzyme in Sia biosynthesis, is lethal to the embryo, which clearly indicates the importance of Sia in embryogenesis. Occasionally, oligo/polymeric Sia structures such as disialic acid (diSia), oligosialic acid (oligoSia), and polysialic acid (polySia) occur in glycoconjugates. In particular, polySia, a well-known epitope that commonly occurs in neuroinvasive bacteria and vertebrate brains, is one of the most well-known and biologically/neurologically important glycotopes in vertebrates. The biological effects of polySia, especially on neural cell-adhesion molecules, have been well studied, and in-depth knowledge regarding polySia has been accumulated. In addition, the importance of diSia and oligoSia epitopes has been reported. In this chapter, the recent advances in the study of diSia, oligoSia, and polySia residues in glycoproteins in neurology, and their history, definition, occurrence, analytical methods, biosynthesis, and biological functions evaluated by phenotypes of gene-targeted mice, biochemical features, and related diseases are described.

Elevated brain-derived neurotrophic factor (BDNF) serum levels in an acute episode of schizophrenia in polish women: Correlation with clinical and metabolic parameters

Brain-derived neurotrophic factor (BDNF) has been implicated in the pathogenesis of psychiatric disorders. Schizophrenia is associated with metabolic abnormalities and BDNF regulates energy homeostasis and glucose metabolism in peripheral tissues. The aim of this study was to examine serum levels of BDNF in schizophrenic women during 8 weeks of treatment and control group, and its correlation with clinical and metabolic parameters. The study was performed on a group of 96 women: 55 diagnosed with paranoid schizophrenia according to DSM-IV criteria, and 41 healthy controls. Positive and Negative Syndrome Scale (PANSS) was used to assess the severity of schizophrenia. BDNF serum levels and metabolic parameters: fasting serum glucose, total cholesterol, triglyceride (TG), high-density lipoprotein (HDL-C), low-density lipoprotein (LDL-C) were measured at baseline and week 8 of treatment. BDNF serum levels were significantly elevated in medicated patients with schizophrenia comparing to controls. After 8 weeks of antipsychotic treatment, BDNF levels did not significantly change. Increase in TG and TG/HDL-C ratio and a decrease in HDL-C was detected in medicated patients. Correlation between BDNF and lipid profile as well as symptoms severity was found. In our study we detected abnormalities in BDNF levels and lipid profile in medicated schizophrenic women in Polish population.

DNA Methylation and Gene Expression of Matrix Metalloproteinase 9 Gene in Deficit and Non-deficit Schizophrenia

The biological pathology of deficit schizophrenia (DS) remains unclear. Matrix metalloproteinase 9 (MMP9) might be associated with neural plasticity and glutamate regulation, involved in schizophrenia pathogenesis. This study explores gene expression and DNA methylation of MMP9 in peripheral blood mononuclear cells (PBMCs) and their relationship with clinical symptoms in DS and non-deficit schizophrenia (NDS). Pyrosequencing was used to determine DNA methylation at CpG sites in exon 4 and exon 5 of MMP9 in 51 DS patients, 53 NDS patients and 50 healthy subjects (HC). RT-qPCR was used to detect MMP9 expression. Clinical symptoms were assessed by BPRS, SANS and SAPS scales. MMP9 expression in PBMCs was significantly higher in DS than NDS and HC subjects. Compared to NDS patients, DS patients had significantly lower DNA methylation at individual CpG sites in exon 4 and exon 5 of MMP9. Correlation analysis showed that DNA methylation in exon 4 was negatively correlated with gene expression in DS group. Positive correlation was found between MMP9 expression and negative symptoms in total schizophrenic patients. The social amotivation factor of SANS and negative syndrome of BPRS was negatively correlated with DNA methylation of CpG5-1 in DS patients but not in NDS patients. DS patients showed a specific abnormality of peripheral MMP9 expression and DNA methylation, indicating a pathological mechanism underlying DS as a specific subgroup of schizophrenia.

The neurobiological hypothesis of neurotrophins in the pathophysiology of schizophrenia: A meta-analysis

BACKGROUND

Schizophrenia is associated with patterns of aberrant neurobiological circuitry. The disease complexity is mirrored by multiple biological interactions known to contribute to the disease pathology. One potential contributor is the family of neurotrophins which are proteins involved in multiple functional processes in the nervous system, with crucial roles in neurodevelopment, synaptogenesis and neuroplasticity. With these roles in mind, abnormal neurotrophin profiles have been hypothesized to contribute to the pathology of schizophrenia.

METHODS

We performed a systematic review and a meta-analysis to scrutinize the neurobiological hypothesis of neurotrophins in schizophrenia, examining the correlation between peripheral levels of brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), neurotrophin-3 (NT-3) and neurotrophin 4/5 (NT-4/5) associated with schizophrenia.

RESULTS

Fifty-two studies were reviewed and twenty-two studies were included in this meta-analysis. Using a random effects model, we confirmed that decreased levels of neurotrophins (BDNF, NGF and NT-4/5) were associated with schizophrenia (Hedges's g = -0.846; SE = 0.058; 95% confidence interval: -0.960 to -0.733; Z-value = -14.632; p-value = 0.000). Subgroup analysis indicated that neurotrophin levels are significantly decreased in both medicated and drug-näive patients. Meta-regression of continuous variables such as mean age, duration of illness and PANSS total score did not show significant effects (p > 0.05) in relation to neurotrophins levels.

DISCUSSION

We confirm that decreased peripheral neurotrophin levels are significantly associated with schizophrenia, thereby confirming the neurobiological hypothesis of neurotrophins in schizophrenia. Low levels of neurotrophins in peripheral blood of patients with schizophrenia may explain, in part, the pathophysiology of schizophrenia.

Perineuronal nets in brain physiology and disease

Perineuronal nets (PNNs) in the brain are condensed glycosaminoglycan-rich extracellular matrix structures with heterogeneous composition yet specific organization. They typically assemble around a subset of fast-spiking interneurons that are implicated in learning and memory. Owing to their unique structural organization, PNNs have neuroprotective capacities but also participate in signal transduction and in controlling neuronal activity and plasticity. In this review, we define PNN structure in detail and describe its various biochemical and physiological functions. We further discuss the role of PNNs in brain disorders such as schizophrenia, bipolar disorder, Alzheimer disease and addictions. Lastly, we describe therapeutic approaches that target PNNs to alter brain physiology and counter brain dysfunction.

Clozapine Pharmacogenetic Studies in Schizophrenia: Efficacy and Agranulocytosis

Clozapine is an efficacious atypical antipsychotic for treatment-refractory schizophrenia. Clinical response and appearance of adverse events vary among individual patients receiving clozapine, with genetic and non-genetic factors potentially contributing to individual variabilities. Pharmacogenetic studies investigate associations between genetic variants and drug efficacy and toxicity. To date, most pharmacogenetic studies of clozapine have been conducted through candidate gene approaches. A recent advance in technology made it possible to perform comprehensive genetic mapping underlying clinical phenotypes and outcomes, which allow novel findings beyond biological hypotheses based on current knowledge. In this paper, we will summarize the studies on clozapine pharmacogenetics that have extensively examined clinical response and agranulocytosis. While there is still limited evidence on clozapine efficacy, recent genome-wide studies provide further evidence of the involvement of the human leukocyte antigen (HLA) region in clozapine-induced agranulocytosis.

The Perineuronal 'Safety' Net? Perineuronal Net Abnormalities in Neurological Disorders

Perineuronal nets (PNN) are extracellular matrix (ECM) assemblies that preferentially ensheath parvalbumin (PV) expressing interneurons. Converging evidence indicates that PV cells and PNN are impaired in a variety of neurological disorders. PNN development and maintenance is necessary for a number of processes within the CNS, including regulation of GABAergic cell function, protection of neurons from oxidative stress, and closure of developmental critical period plasticity windows. Understanding PNN functions may be essential for characterizing the mechanisms of altered cortical excitability observed in neurodegenerative and neurodevelopmental disorders. Indeed, PNN abnormalities have been observed in post-mortem brain tissues of patients with schizophrenia and Alzheimer’s disease. There is impaired development of PNNs and enhanced activity of its key regulator matrix metalloproteinase-9 (MMP-9) in Fragile X Syndrome, a common genetic cause of autism. MMP-9, a protease that cleaves ECM, is differentially regulated in a number of these disorders. Despite this, few studies have addressed the interactions between PNN expression, MMP-9 activity and neuronal excitability. In this review, we highlight the current evidence for PNN abnormalities in CNS disorders associated with altered network function and MMP-9 levels, emphasizing the need for future work targeting PNNs in pathophysiology and therapeutic treatment of neurological disorders.

Blood-brain barrier regulation in psychiatric disorders

The blood-brain barrier (BBB) is a dynamic interface between the peripheral blood supply and the cerebral parenchyma, controlling the transport of material to and from the brain. Tight junctions between the endothelial cells of the cerebral microvasculature limit the passage of large, negatively charged molecules via paracellular diffusion whereas transcellular transportation across the endothelial cell is controlled by a number of mechanisms including transporter proteins, endocytosis, and diffusion. Here, we review the evidence that perturbation of these processes may underlie the development of psychiatric disorders including schizophrenia, autism spectrum disorder (ASD), and affective disorders. Increased permeability of the BBB appears to be a common factor in these disorders, leading to increased infiltration of peripheral material into the brain culminating in neuroinflammation and oxidative stress. However, although there is no common mechanism underpinning BBB dysfunction even within each particular disorder, the tight junction protein claudin-5 may be a clinically relevant target given that both clinical and pre-clinical research has linked it to schizophrenia, ASD, and depression. Additionally, we discuss the clinical significance of the BBB in diagnosis (genetic markers, dynamic contrast-enhanced-magnetic resonance imaging, and blood biomarkers) and in treatment (drug delivery).

A normal genetic variation modulates synaptic MMP-9 protein levels and the severity of schizophrenia symptoms

Matrix metalloproteinase 9 (MMP‐9) has recently emerged as a molecule that contributes to pathological synaptic plasticity in schizophrenia, but explanation of the underlying mechanisms has been missing. In the present study, we performed a phenotype‐based genetic association study (PGAS) in > 1,000 schizophrenia patients from the Göttingen Research Association for Schizophrenia (GRAS) data collection and found an association between the MMP‐9 rs20544 C/T single‐nucleotide polymorphism (SNP) located in the 3′untranslated region (UTR) and the severity of a chronic delusional syndrome. In cultured neurons, the rs20544 SNP influenced synaptic MMP‐9 activity and the morphology of dendritic spines. We demonstrated that Fragile X mental retardation protein (FMRP) bound the MMP‐9 3′UTR. We also found dramatic changes in RNA structure folding and alterations in the affinity of FMRP for MMP‐9 RNA, depending on the SNP variant. Finally, we observed greater sensitivity to psychosis‐related locomotor hyperactivity in Mmp‐9 heterozygous mice. We propose a novel mechanism that involves MMP‐9‐dependent changes in dendritic spine morphology and the pathophysiology of schizophrenia, providing the first mechanistic insights into the way in which the single base change in the MMP‐9 gene (rs20544) influences gene function and results in phenotypic changes observed in schizophrenia patients.