The matrix metalloproteinase inhibitor marimastat inhibits seizures in a model of kainic acid-induced status epilepticus

Unraveling the role of plasma proteins in dementia: insights from two cohort studies in the UK, with causal evidence from Mendelian randomization

Population-based proteomics offer a groundbreaking avenue to predict dementia onset. This study employed a proteome-wide, data-driven approach to investigate protein-dementia associations in 229 incident all-cause dementia (ACD) among 3,249 participants from the English Longitudinal Study of Ageing (ELSA) over a median 9.8-year follow-up, then validated in 1,506 incident ACD among 52,745 individuals from the UK Biobank (UKB) over median 13.7 years. NEFL and RPS6KB1 were robustly associated with incident ACD; MMP12 was associated with vascular dementia in ELSA. Additional markers EDA2R and KIM1 (HAVCR1) were identified from sensitivity analyses. Combining NEFL and RPS6KB1 with other factors yielded high predictive accuracy (area under the curve (AUC)=0.871) for incident ACD. Replication in the UKB confirmed associations between identified proteins with various dementia subtypes. Results from reverse Mendelian Randomization also supported the role of several proteins as early dementia biomarkers. These findings underscore proteomics' potential in identifying novel risk screening targets for dementia.

Potential of Neuroinflammation-Modulating Strategies in Tuberculous Meningitis: Targeting Microglia

Tuberculous meningitis (TBM) is the most severe complication of tuberculosis (TB) and is associated with high rates of disability and mortality. Mycobacterium tuberculosis (M. tb), the infectious agent of TB, disseminates from the respiratory epithelium, breaks through the blood-brain barrier, and establishes a primary infection in the meninges. Microglia are the core of the immune network in the central nervous system (CNS) and interact with glial cells and neurons to fight against harmful pathogens and maintain homeostasis in the brain through pleiotropic functions. However, M. tb directly infects microglia and resides in them as the primary host for bacillus infections. Largely, microglial activation slows disease progression. The non-productive inflammatory response that initiates the secretion of pro-inflammatory cytokines and chemokines may be neurotoxic and aggravate tissue injuries based on damages caused by M. tb. Host-directed therapy (HDT) is an emerging strategy for modulating host immune responses against diverse diseases. Recent studies have shown that HDT can control neuroinflammation in TBM and act as an adjunct therapy to antibiotic treatment. In this review, we discuss the diverse roles of microglia in TBM and potential host-directed TB therapies that target microglia to treat TBM. We also discuss the limitations of applying each HDT and suggest a course of action for the near future.

Matrix Metalloproteinase-9 Contributes to Epilepsy Development after Ischemic Stroke in Mice

Epilepsy, a neurological disorder affecting over 50 million individuals globally, is characterized by an enduring predisposition and diverse consequences, both neurobiological and social. Acquired epilepsy, constituting 30% of cases, often results from brain-damaging injuries like ischemic stroke. With one third of epilepsy cases being resistant to existing drugs and without any preventive therapeutics for epileptogenesis, identifying anti-epileptogenic targets is crucial. Stroke being a leading cause of acquired epilepsy, particularly in the elderly, prompts the need for understanding post-stroke epileptogenesis. Despite the challenges in studying stroke-evoked epilepsy in rodents due to poor long-term survival rates, in this presented study the use of an animal care protocol allowed for comprehensive investigation. We highlight the role of matrix metalloproteinase-9 (MMP-9) in post-stroke epileptogenesis, emphasizing MMP-9 involvement in mouse models and its potential as a therapeutic target. Using a focal Middle Cerebral Artery occlusion model, this study demonstrates MMP-9 activation following ischemia, influencing susceptibility to seizures. MMP-9 knockout reduces epileptic features, while overexpression exacerbates them. The findings show that MMP-9 is a key player in post-stroke epileptogenesis, presenting opportunities for future therapies and expanding our understanding of acquired epilepsy.

Synthesis and Characterization of a Novel Concentration-Independent Fluorescent Chloride Indicator, ABP-Dextran, Optimized for Extracellular Chloride Measurement

GABA, the primary inhibitory neurotransmitter, stimulates GABAA receptors (GABAARs) to increase the chloride conductance of the cytosolic membrane. The driving forces for membrane chloride currents are determined by the local differences between intracellular and extracellular chloride concentrations (Cli and Clo, respectively). While several strategies exist for the measurement of Cli, the field lacks tools for non-invasive measurement of Clo. We present the design and development of a fluorescent lifetime imaging (FLIM)-compatible small molecule, N(4-aminobutyl)phenanthridiunium (ABP) with the brightness, spectral features, sensitivity to chloride, and selectivity versus other anions to serve as a useful probe of Clo. ABP can be conjugated to dextran to ensure extracellular compartmentalization, and a second chloride-insensitive counter-label can be added for ratiometric imaging. We validate the utility of this novel sensor series in two sensor concentration-independent modes: FLIM or ratiometric intensity-based imaging.

Matrix metalloproteinase-9: A magic drug target in neuropsychiatry?

Neuropsychiatric conditions represent a major medical and societal challenge. The etiology of these conditions is very complex and combines genetic and environmental factors. The latter, for example, excessive maternal or early postnatal inflammation, as well as various forms of psychotrauma, often act as triggers leading to mental illness after a prolonged latent period (sometimes years). Matrix metalloproteinase-9 (MMP-9) is an extracellularly and extrasynaptic operating protease that is markedly activated in response to the aforementioned environmental insults. MMP-9 has also been shown to play a pivotal role in the plasticity of excitatory synapses, which, in its aberrant form, has repeatedly been implicated in the etiology of mental illness. In this conceptual review, we evaluate the experimental and clinical evidence supporting the claim that MMP-9 is uniquely positioned to be considered a drug target for ameliorating the adverse effects of environmental insults on the development of a variety of neuropsychiatric conditions, such as schizophrenia, bipolar disorder, major depression, autism spectrum disorders, addiction, and epilepsy. We also identify specific challenges and bottlenecks hampering the translation of knowledge on MMP-9 into new clinical treatments for the conditions above and suggest ways to overcome these barriers.

Repurposing of antiangiogenic agents for treatment of vascular anomalies

Vascular anomalies (VA) are developmental anomalies of veins, arteries, lymphatics or capillaries thought to be caused by mutations in genes that drive angiogenesis. Treatments targeting these genes are limited. We review the literature for conventional medications and products from traditional medicine cultures that have been found to have antiangiogenic activity. Fewer than 50 drugs with credible human activity in VA were identified and include β blockers, monoclonal antibodies, microtubule inhibitors, multi-kinase inhibitors, PIK3CA- and RAS-MAPK pathway inhibitors, and thalidomides. Other drug categories of potential interest are ACE-inhibitors, antifungals, antimalarials, MMP9-inhibitors, and over-the-counter compounds used in Eastern traditional medicine. Low toxicity for some offers the possibility of combined use with known effective agents. In addition to already familiar drugs, others with antiangiogenic capabilities already in use in children or adults may deserve further attention for repurposing for VA.

NTSR1 glycosylation and MMP dependent cleavage generate three distinct forms of the protein

NTSR1 abnormal expression by cancer cells makes it a strategic target for antitumoral therapies, such as compounds that use NTSR1 binding probes to deliver cytotoxic agents to tumor cells. Success of these therapies relies on NTSR1 protein availability and accessibility; therefore, understanding the protein's biology is crucial. We studied NTSR1 protein in exogenously and endogenously expressing non-tumoral and tumoral cells. We found NTSR1 to be expressed as three distinct protein forms: the NTSR1-high form, a glycosylated protein; the NTSR1-low form, a N-terminally cleaved and de-glycosylated protein; and the NTSR1-LP protein with the MW size predicted by its NTSR1 amino acid sequence. We show that the NTSR1-high form is cleaved by MMPs to generate the NTSR1-low form, a process that is promoted by the Neurotensin (NTS) ligand. In addition, NTS induced the internalization of plasma membrane localized NTSR1 and degradation of NTSR1-low form via the proteasome. Importantly, we found NTSR1-low form to be the most abundant form in the tumoral cells and in PDAC Patient Derived Xenograft, demonstrating its physiopathological relevance. Altogether, our work provides important technical and experimental tools as well as new crucial insights into NTSR1 protein biology that are required to develop clinically relevant NTSR1 targeting anti-tumoral therapies.

Converging Mechanisms of Epileptogenesis and Their Insight in Glioblastoma

Glioblastoma (GBM) is the most common and advanced form of primary malignant tumor occurring in the adult central nervous system, and it is frequently associated with epilepsy, a debilitating comorbidity. Seizures are observed both pre- and post-surgical resection, indicating that several pathophysiological mechanisms are shared but also prompting questions about how the process of epileptogenesis evolves throughout GBM progression. Molecular mutations commonly seen in primary GBM, i.e., in PTEN and p53, and their associated downstream effects are known to influence seizure likelihood. Similarly, various intratumoral mechanisms, such as GBM-induced blood-brain barrier breakdown and glioma-immune cell interactions within the tumor microenvironment are also cited as contributing to network hyperexcitability. Substantial alterations to peri-tumoral glutamate and chloride transporter expressions, as well as widespread dysregulation of GABAergic signaling are known to confer increased epileptogenicity and excitotoxicity. The abnormal characteristics of GBM alter neuronal network function to result in metabolically vulnerable and hyperexcitable peri-tumoral tissue, properties the tumor then exploits to favor its own growth even post-resection. It is evident that there is a complex, dynamic interplay between GBM and epilepsy that promotes the progression of both pathologies. This interaction is only more complicated by the concomitant presence of spreading depolarization (SD). The spontaneous, high-frequency nature of GBM-associated epileptiform activity and SD-associated direct current (DC) shifts require technologies capable of recording brain signals over a wide bandwidth, presenting major challenges for comprehensive electrophysiological investigations. This review will initially provide a detailed examination of the underlying mechanisms that promote network hyperexcitability in GBM. We will then discuss how an investigation of these pathologies from a network level, and utilization of novel electrophysiological tools, will yield a more-effective, clinically-relevant understanding of GBM-related epileptogenesis. Further to this, we will evaluate the clinical relevance of current preclinical research and consider how future therapeutic advancements may impact the bidirectional relationship between GBM, SDs, and seizures.

Considering the Role of Extracellular Matrix Molecules, in Particular Reelin, in Granule Cell Dispersion Related to Temporal Lobe Epilepsy

The extracellular matrix (ECM) of the nervous system can be considered as a dynamically adaptable compartment between neuronal cells, in particular neurons and glial cells, that participates in physiological functions of the nervous system. It is mainly composed of carbohydrates and proteins that are secreted by the different kinds of cell types found in the nervous system, in particular neurons and glial cells, but also other cell types, such as pericytes of capillaries, ependymocytes and meningeal cells. ECM molecules participate in developmental processes, synaptic plasticity, neurodegeneration and regenerative processes. As an example, the ECM of the hippocampal formation is involved in degenerative and adaptive processes related to epilepsy. The role of various components of the ECM has been explored extensively. In particular, the ECM protein reelin, well known for orchestrating the formation of neuronal layer formation in the cerebral cortex, is also considered as a player involved in the occurrence of postnatal granule cell dispersion (GCD), a morphologically peculiar feature frequently observed in hippocampal tissue from epileptic patients. Possible causes and consequences of GCD have been studied in various in vivo and in vitro models. The present review discusses different interpretations of GCD and different views on the role of ECM protein reelin in the formation of this morphological peculiarity.

Expression changes in ion channel and immunity genes are associated with glioma-related epilepsy in patients with diffuse gliomas

BACKGROUND

Glioma-related epilepsy (GRE) is a common symptom in patients with diffuse gliomas. However, the underlying mechanisms of GRE remain unclear. The current study aimed to investigate the underlying epileptogenic mechanisms of GRE through RNA sequencing analysis.

METHODS

Demographic, RNA sequencing, and follow-up data of 643 patients were reviewed. Patients were divided into test and validation groups (223 and 420 patients, respectively) by different time periods for RNA sequencing. The differentially expressed genes (DEGs) associated with preoperative GRE were identified using R software. Functional enrichment analysis was subsequently performed, and tissue-infiltrating immune cells were also estimated. Weighted correlation network analysis (WGCNA) was conducted to further identify key modules exhibiting the highest correlation with preoperative GRE. Overlapping genes between the DEG set and key gene set identified by WGCNA were selected and verified in the validation cohort. The protein-protein interaction (PPI) network analysis was then constructed to identify hub genes for preoperative GRE.

RESULTS

A total of 219 DEGs were identified, among which 112 were upregulated and 107 downregulated in patients with GRE. Functional enrichment analysis revealed that upregulated DEGs were related to ion channel activity, while downregulated genes were related to immunity. Forty-two genes were further selected from overlapping DEGs and the key gene set. Among these genes, 31 genes showed significant differences in the validation cohort. Finally, the PPI network analysis identified six genes, including SCN3B, KCNIP2, KCNJ11, VEGFA, MMP9, and ANXA2, as hub genes for GRE.

CONCLUSION

The current study revealed that ion channel activity and immunity dysfunction in diffuse glioma patients contributed to the occurrence of GRE, and SCN3B might be a shared therapeutic target for both diffuse gliomas and GRE. These findings could improve the understanding of the mechanisms of GRE and promote individualized medications for glioma management.

Insight into the structural requirements of gelatinases (MMP-2 and MMP-9) inhibitors by multiple validated molecular modelling approaches: Part II

Inhibition of the matrix metalloproteinases (MMPs) is effective against metastasis of secondary tumours. Previous MMP inhibitors have failed in clinical trials due to their off-target toxicity in solid tumours. Thus, newer MMP inhibitors now have paramount importance. Here, different molecular modelling techniques were applied on a dataset of 110 gelatinase (MMP-2 and MMP-9) inhibitors. The objectives of the present study were to identify structural fingerprints for gelatinase inhibition and also to develop statistically validated QSAR models for the screening and prediction of different derivatives as MMP-2 (gelatinase A) and MMP-9 (gelatinase B) inhibitors. The Bayesian classification study provided the ROC values for the training set of 0.837 and 0.815 for MMP-2 and MMP-9, respectively. The linear model also produced the leave-one-out cross-validated Q² of 0.805 (eq. 1, MMP-2) and 0.724 (eq. 2, MMP-9), an r² of 0.845 (eq. 1, MMP-2) and 0.782 (eq. 2, MMP-9), an r²_Pred of 0.806 (eq. 1, MMP-2) and 0.732 (eq. 2, MMP-9). Similarly, non-linear learning models were also statistically significant and reliable. Overall, this study may help in the rational design of newer compounds with higher gelatinase inhibition to fight against both primary and secondary cancers in future.