Roles of matrix metalloproteinase-9 and tissue inhibitors of metalloproteinases 1 in acute encephalopathy following prolonged febrile seizures

Serum matrix metallopeptidase-9 levels in infantile epileptic spasms syndrome of unknown etiology

PURPOSE

Epileptic spasms are the primary symptom of infantile epileptic spasms syndrome (IESS); however, their direct impact on blood-brain barrier (BBB) function is unknown. Matrix metallopeptidase-9 (MMP-9), degrades type IV collagen, a key component of the blood-brain barrier, while tissue inhibitor of metalloproteinase-1 (TIMP-1) suppresses its activity, protecting BBB integrity. This study aimed to assess serum MMP-9 and TIMP-1 levels in patients with IESS of unknown etiology.

METHODS

We prospectively assessed serum MMP-9 and TIMP-1 levels prior to administering vigabatrin or adrenocorticotropic hormone therapy in patients with IESS of unknown etiology at Saitama Children's Medical Center between February 2012 and December 2023. We compared these biomarkers between patients with epileptic spasms and age-matched controls and performed a curve regression analysis between the biomarkers and the frequency of epileptic spasms. Additionally, we assessed whether MMP-9 and TIMP-1 levels were diagnostic predictors of IESS.

RESULTS

This study included 22 patients with IESS (11 males) and 12 controls. Serum MMP-9 and MMP-9/TIMP-1 ratios were higher in patients with IESS than in controls (p < 0.001 and p = 0.002, respectively). A high frequency of epileptic spasms also led to higher serum MMP-9 levels (y = 0.0871x2 + 0.195x + 195.15, R² = 0.77, p < 0.001). Using MMP >188 ng/mL as the cutoff level, the sensitivity for diagnosing IESS was 95.5 %, the specificity was 75.0 %, the positive likelihood ratio was 3.82 (95 % confidence interval (CI) 1.43-10.22), and the relative risk was 8.75 (95 % CI 1.36-56.5).

CONCLUSION

Patients with IESS had elevated serum MMP-9 levels, suggesting an association between epileptic spasms and blood-brain barrier dysfunction. MMP-9 level measurement may be useful for diagnosing suspected patients.

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

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

Saccharomyces Boulardii alleviates neuroinflammation and oxidative stress in PTZ-kindled seizure rat model

Previous research have reported that modulating the gut microbiome composition by fecal microbiota transplantation and probiotic administration can alleviate seizure occurrence and severity. Saccharomyces boulardii (SB) is a yeast probiotic that has demonstrated ameliorating effects on anxiety, memory and cognitive deficit, and brain amyloidogenesis. In this research, our goal was to examine the anti-seizure effects of SB on the pentylenetetrazole (PTZ)-kindled male Wistar rats. The animals were randomly categorized into four test groups. The rats were orally administered with saline (control and PTZ groups) or S. boulardii (SB + PTZ and SB groups) for 57 days. From the 29th day of the experiment, the animals received intraperitoneally saline (control and SB groups) or PTZ (PTZ and SB + PTZ groups) on alternate days for 30 days. The administration dose of SB and PTZ was 1010 CFU/ml/day and 35 mg/kg, respectively. We assessed animal seizure behavior, neuroinflammation, oxidative stress, and the levels of matrix metalloproteinase-9 (MMP-9) and brain-derived neurotrophic factor (BDNF) in the hippocampus tissue. S. boulardii hindered the PTZ-induced kindling development. SB treatment elevated glutathione (GSH) and total antioxidant capacity (TAC) and reduced malondialdehyde (MDA) levels. SB also lessened the hippocampal levels of BDNF and MMP-9. Following SB supplementation, proinflammatory cytokines interleukin-1 beta (IL-1β) and IL-6 were lowered, and anti-inflammatory cytokine IL-10 was enhanced. Overall, our data indicated, for the first time, the positive impact of SB on the PTZ-kindled seizure rat model. The anti-seizure activity of SB was mediated by modulating oxidative stress, neuroinflammation, and MMP-9 and BDNF levels.

Meta-analysis of MMP-9 levels in the serum of patients with epilepsy

Background

Epilepsy's pathogenesis and progression are significantly influenced by neuroinflammation, blood-brain barrier function, and synaptic remodeling function. Matrix metalloproteinase 9 (MMP-9), as a critical factor, may contribute to the development of epilepsy through one or more of the above-mentioned pathways. This study aims to evaluate and quantify the correlation between MMP-9 levels and epilepsy.

Methods

We conducted a comprehensive search of Embase, Web of Science, PubMed, Cochrane Library, WanFang DATA, VIP, and the CNKI to identify studies that investigate the potential association between MMP-9 and epilepsy. The data were independently extracted by two researchers and assessed for quality using the Cochrane Collaboration tool. The extracted data were analyzed using Stata 15 and Review Manager 5.4. The study protocol was registered prospectively at PROSPERO, ID: CRD42023468493.

Results

Thirteen studies with a total of 756 patients and 611 matched controls met the inclusion criteria. Eight of these studies reported total serum MMP-9 levels, and the other five studies were used for a further subgroup analysis. The meta-analysis indicated that the serum MMP-9 level was higher in epilepsy patients (SMD = 4.18, 95% confidence interval = 2.18-6.17, p < 0.00001) compared with that in the control group. Publication bias was not detected according to Begg's test. The subgroup analysis of country indicated that the epilepsy patients in China, Poland, and Egypt had higher levels of serum MMP-9 than the control group, with the increase being more pronounced in Egypt. The subgroup analysis of the age category demonstrated that the serum MMP-9 levels of the adult patients with epilepsy were significantly higher than those of the matched controls. However, the serum MMP-9 levels did not significantly differ in children with epilepsy. The subgroup analysis of the seizure types demonstrated substantial difference in the MMP-9 levels between patients of seizure-free epilepsy (patients who have been seizure-free for at least 7 days) and the control group. Meanwhile, the serum MMP-9 level in patients with epileptic seizures was significantly higher than that in the control group. The subgroup analysis based on seizure duration in patients showed that the serum MMP-9 levels at 1-3, 24, and 72 h after seizure did not exhibit significant differences between female and male patients with epilepsy when compared with the control group. The serum MMP-9 levels at 1-3 and 24 h were significantly higher than those of the matched controls. Nevertheless, the serum MMP-9 level at 72 h was not significantly different from that in the control group.

Conclusion

This meta-analysis presents the first comprehensive summary of the connection between serum MMP-9 level and epilepsy. The MMP-9 levels in epilepsy patients are elevated. Large-scale studies with a high level of evidence are necessary to determine the exact relationship between MMP-9 and epilepsy.

A serial analysis of serum aspartate aminotransferase levels in patients with acute encephalopathy with biphasic seizures and late reduced diffusion and prolonged febrile seizure

BACKGROUND

There are no established biomarkers for diagnosing acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) in the early acute phase, called "the 1st seizure phase". Based on our clinical experience, we hypothesized that serial examinations of blood levels of aspartate aminotransferase (AST) in children with febrile convulsive status epilepticus (FCSE) revealed higher levels in patients with AESD in the 1st seizure phase than in those with prolonged febrile seizures (PFs).

METHODS

To test our presented hypothesis, we retrospectively investigated changes in serum AST in patients with FCSE due to AESD (n = 11) or PFs (n = 27) who were serially examined within 48 h of the onset of convulsions.

RESULTS

The rate of increase in AST was significantly higher in patients with AESD than in those with PFs. The rate of increase in AST correlated with previously reported scoring systems, i.e., Yokochi and Tottori scores, for the prediction of AESD. A positive correlation between the rate of increase in AST and creatinine levels in the first examination were observed; however, creatinine levels did not significantly differ between the AESD and PFs groups in the first or second examination. Blood levels of pH, ammonia, and sugar in the first examination and C-reactive protein in the second examination were significantly higher in the AESD group than in the PFs group.

CONCLUSIONS

The present study revealed that the rate of increase in AST was significantly higher in patients with AESD than in those with PFs. A novel predictive scoring system needs to be established in combination with the rate of increase in AST and reported clinical parameters, which will improve the prognosis of patients with FCSE.

Blood-Brain Barrier-Associated Proteins Are Elevated in Serum of Epilepsy Patients

Blood-brain barrier (BBB) dysfunction emerges as one of the mechanisms underlying the induction of seizures and epileptogenesis. There is growing evidence that seizures also affect BBB, yet only scarce data is available regarding serum levels of BBB-associated proteins in chronic epilepsy. In this study, we aimed to assess serum levels of molecules associated with BBB in patients with epilepsy in the interictal period. Serum levels of MMP-9, MMP-2, TIMP-1, TIMP-2, S100B, CCL-2, ICAM-1, P-selectin, and TSP-2 were examined in a group of 100 patients who were seizure-free for a minimum of seven days and analyzed by ELISA. The results were compared with an age- and sex-matched control group. Serum levels of MMP-9, MMP-2, TIMP-1, TIMP-2 and S100B were higher in patients with epilepsy in comparison to control group (p < 0.0001; <0.0001; 0.001; <0.0001; <0.0001, respectively). Levels of CCL-2, ICAM-1, P-selectin and TSP-2 did not differ between the two groups. Serum levels of MMP-9, MMP-2, TIMP-1, TIMP-2 and S100B are elevated in patients with epilepsy in the interictal period, which suggests chronic processes of BBB disruption and restoration. The pathological process initiating epilepsy, in addition to seizures, is probably the factor contributing to the elevation of serum levels of the examined molecules.

CD147 and MMPs as key factors in physiological and pathological processes

Cluster of differentiation 147 (CD147) or extracellular matrix metalloproteinase inducer (EMMPRIN) is a transmembrane glycoprotein that induces the synthesis of matrix metalloproteinases (MMPs). MMPs, as zinc-dependent proteases and versatile enzymes, play critical roles in the degradation of the extracellular matrix (ECM) components, cleaving of the receptors of cellular surfaces, signaling molecules, and other precursor proteins, which may lead to attenuation or activation of such targets. CD147 and MMPs play essential roles in physiological and pathological conditions and any disorder in the expression, synthesis, or function of CD147 and MMPs may be associated with various types of disease. In this review, we have focused on the roles of CD147 and MMPs in some major physiological and pathological processes.

Early Phase Increase in Serum TIMP-1 in Patients with Acute Encephalopathy with Biphasic Seizures and Late Reduced Diffusion

BACKGROUND

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is the most frequent subtype of acute encephalopathy syndrome among Japanese children. Exanthem subitum is the most common causative infectious disease of AESD. We herein retrospectively analyzed serum and cerebrospinal fluid (CSF) concentrations of matrix metalloproteinase-9 (MMP-9), tissue inhibitor matrix metalloproteinase-1 (TIMP-1), and seven cytokines in patients with AESD or prolonged febrile seizure (FS) to assess the pathophysiology of AESD and detect biomarkers for diagnosing AESD in the early phase.

METHODS

Serum and CSF samples were obtained from 17 patients with AESD (1st seizure phase group, n = 7; 2nd seizure phase group, n = 10) and 8 with FS. The concentrations of MMP-9, TIMP-1, and seven cytokines were measured by enzyme-linked immunosorbent assays or cytometric bead arrays.

RESULTS

Serum concentrations of TIMP-1 were significantly higher in the 1st seizure phase group than in the 2nd seizure phase group. No significant differences were observed in serum concentrations of MMP-9 or the MMP-9/TIMP-1 ratio.

CONCLUSIONS

The MMP-9-independent increase in circulating TIMP-1 concentrations observed in the present study may be associated with the pathophysiology of AESD in the 1st seizure phase.

Altered Extracellular Matrix as an Alternative Risk Factor for Epileptogenicity in Brain Tumors

Seizures are one of the most common symptoms of brain tumors. The incidence of seizures differs among brain tumor type, grade, location and size, but paediatric-type diffuse low-grade gliomas/glioneuronal tumors are often highly epileptogenic. The extracellular matrix (ECM) is known to play a role in epileptogenesis and tumorigenesis because it is involved in the (re)modelling of neuronal connections and cell-cell signaling. In this review, we discuss the epileptogenicity of brain tumors with a focus on tumor type, location, genetics and the role of the extracellular matrix. In addition to functional problems, epileptogenic tumors can lead to increased morbidity and mortality, stigmatization and life-long care. The health advantages can be major if the epileptogenic properties of brain tumors are better understood. Surgical resection is the most common treatment of epilepsy-associated tumors, but post-surgery seizure-freedom is not always achieved. Therefore, we also discuss potential novel therapies aiming to restore ECM function.

Blood biomarkers in epilepsy

Robust and accessible biomarkers are greatly needed in epilepsy. Diagnostic and prognostic precision in the clinic needs to improve, and there is a need for objective quantification of seizure burden. In recent years, there have been advances in the development of accessible and cost-effective blood-based biomarkers in neurology, and these are increasingly studied in epilepsy. However, the field is in its infancy and specificity and sensitivity for most biomarkers in most clinical situations are not known. This review describes advancements regarding human blood biomarkers in epilepsy. Examples of biochemical markers that have been shown to have higher blood concentrations in study subjects with epilepsy include brain proteins like S100B or neuronal specific enolase, and neuroinflammatory proteins like interleukins, and tumor necrosis factor-alpha. Some of the blood biomarkers also seem to reflect seizure duration or frequency, and levels decrease in response to treatment with antiseizure medication. For most biomarkers, the literature contains seemingly conflicting results. This is to be expected in an emerging field and could reflect different study populations, sampling or analysis techniques, and epilepsy classification. More studies are needed with emphasis put on the classification of epilepsy and seizure types. More standardized reporting could perhaps decrease result heterogeneity and increase the potential for data sharing and subgroup analyses.

Serum matrix metallopeptidase-9 and tissue inhibitor of metalloproteinase-1 levels may predict response to adrenocorticotropic hormone therapy in patients with infantile spasms

OBJECTIVE

To evaluate whether serum matrix metallopeptidase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) levels predict response to adrenocorticotropic hormone (ACTH) therapy in patients with infantile spasms.

METHODS

We prospectively evaluated patients with infantile spasms who were referred to Saitama Children's Medical Center from January 2011 to December 2020. We measured Q-albumin and serum MMP-9 and TIMP-1 levels before ACTH therapy. Patients were divided into three groups based on the etiology of their infantile spasms: those with an unknown etiology and normal development (unknown-normal group); those with a structural and acquired etiology (structural-acquired group); and those with a structural and congenital, genetic, metabolic, or unknown etiology with developmental delay (combined-congenital group). Responders were defined as those having complete cessation of spasms for more than 3 months with the resolution of hypsarrhythmia on electroencephalography during ACTH therapy.

RESULTS

We collected serum from 36 patients with West syndrome and five patients with infantile spasms without hypsarrhythmia before ACTH therapy. Twenty-three of 41 patients (56.1%) were responders, including 8/8 (100%) in the unknown-normal group, 6/9 (66.7%) in the structural-acquired group, and 9/24 (37.5%) in the combined-congenital group. The serum MMP-9 level and MMP-9/TIMP-1 ratio were significantly higher in responders than in nonresponders (P = 0.001 for both).

CONCLUSION

A therapeutic response to ACTH was associated with a higher serum MMP-9 level and higher MMP-9/TIMP-1 ratio in patients with infantile spasms. Therefore, these biomarkers may predict responses to ACTH therapy in this patient population.

Predicting the Onset of Acute Encephalopathy With Biphasic Seizures and Late Reduced Diffusion by Using Early Laboratory Data

Background: Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) often causes various neurological sequelae, necessitating early and objective differentiation of AESD from a febrile seizure (FS). Therefore, we developed a scoring system that predicts AESD onset using only early laboratory data. Methods: We selected patients with AESD or FS admitted to the Tottori University Hospital between November 2005 and September 2020 and collected laboratory data from onset to discharge in patients with FS and from onset to the second neurological events in patients with AESD. Results: We identified 18 patients with AESD and 181 patients with FS. In comparison with patients with FS, patients with AESD showed statistically significant increases in ammonia (NH3), blood sugar (BS), and serum creatinine (Cr) levels, and the white blood cell (WBC) count, and a significant decrease in pH at <3 h from onset. We set the cut-off values and adjusted the weight of each of these parameters based on data obtained <3 h from onset and proposed a scoring system for predicting AESD. This system showed 91% sensitivity and 94% specificity for distinguishing AESD from FS. These accuracies were only slightly improved by the addition of information related to consciousness and seizure duration (sensitivity, 91%; specificity, 96%). Conclusion: NH3, BS, and Cr levels, WBC count, and pH were significantly different between patients with AESD and patients with FS at <3 h from seizure onset. This scoring system using these data may enable the prediction of AESD onset for patients under sedation or without precise clinical information.

Microglial Displacement of GABAergic Synapses Is a Protective Event during Complex Febrile Seizures

Complex febrile seizures (FSs) lead to a high risk of intractable temporal lobe epilepsy during adulthood, yet the pathological process of complex FSs is largely unknown. Here, we demonstrate that activated microglia extensively associated with glutamatergic neuronal soma displace surrounding GABAergic presynapses in complex FSs. Patch-clamp electrophysiology establishes that the microglial displacement of GABAergic presynapses abrogates a complex-FS-induced increase in GABAergic neurotransmission and neuronal excitability, whereas GABA exerts an excitatory action in this immature stage. Pharmacological inhibition of microglial displacement of GABAergic presynapses or selective ablation of microglia in CD11b^DTR mice promotes the generation of complex FSs. Blocking or deleting the P2Y₁₂ receptor (P2Y₁₂R) reduces microglial displacement of GABAergic presynapses and shortens the latency of complex FSs. Together, microglial displacement of GABAergic presynapses, regulated by P2Y₁₂R, reduces neuronal excitability to mitigate the generation of complex FSs. Microglial displacement is a protective event during the pathological process of complex FSs.

Pro-inflammatory cytokines, but not brain- and extracellular matrix-derived proteins, are increased in the plasma following electrically induced kindling of seizures

Background

The aim of the study was to evaluate the brain-derived proteins, extracellular matrix-derived protein and cytokines as potential peripheral biomarkers of different susceptibility to seizure development in an animal model of epilepsy evoked by chronic focal electrical stimulation of the brain.

Methods

The plasma levels of IL-1β (interleukin 1β), IL-6 (interleukin 6), UCH-L1 (ubiquitin C-terminal hydrolase 1), MMP-9 (matrix metalloproteinase 9), and GFAP (glial fibrillary acidic protein) were assessed. The peripheral concentrations of the selected proteins were analyzed according to the status of kindling and seizure severity parameters. In our study, increased concentrations of plasma IL-1β and IL-6 were observed in rats subjected to hippocampal kindling compared to sham-operated rats.

Results

Animals that developed tonic–clonic seizures after the last stimulation had higher plasma concentrations of IL-1β and IL-6 than sham-operated rats and rats that did not develop seizure. Elevated levels of IL-1β and IL-6 were observed in rats that presented more severe seizures after the last five stimulations compared to sham-operated animals. A correlation between plasma IL-1β and IL-6 concentrations was also found. On the other hand, the plasma levels of the brain-derived proteins UCH-L1, MMP-9, and GFAP were unaffected by kindling status and seizure severity parameters.

Conclusions

The plasma concentrations of IL-1β and IL-6 may have potential utility as peripheral biomarkers of immune system activation in the course of epilepsy and translational potential for future clinical use. Surprisingly, markers of cell and nerve ending damage (GFAP, UCH-L1 and MMP-9) may have limited utility.

Serum matrix metallopeptidase-9 and tissue inhibitor of metalloproteinase-1 levels in autoimmune encephalitis

OBJECTIVE

Some pediatric patients with autoimmune encephalitis (AE) experience sequelae in spite of immunotherapy. In this study, we aimed to evaluate the association of serum matrix metallopeptidase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) levels with the neurological prognosis of AE.

METHODS

We retrospectively included 13 patients with AE who had been referred to Saitama Children's Medical Center from February 2011 to May 2019. We compared serum MMP-9 levels, TIMP-1 levels, and MMP-9/TIMP-1 ratio in the acute period (within 30 days from the onset of AE) and subacute period (30-day period following the acute period). We also compared these biomarker levels between patients with (group A) and without sequelae (group B). Sequelae were evaluated at discharge or the last visit.

RESULTS

Group A (median age, 7.8 years; range, 5.3-10.7 years) and group B (median age, 13.3 years; range, 11.1-15.4 years) had 6 patients each; 1 patient was excluded because the time of AE onset was unknown. In the acute period, there were no significant differences in MMP-9 levels, TIMP-1 levels, and MMP-9/TIMP-1 ratio between groups A and B. In the subacute period, serum MMP-9/TIMP-1 ratio was higher in group A than in group B (p < 0.01). There were no significant differences in MMP-9 and TIMP-1 levels between groups A and B.

CONCLUSIONS

Patients with sequelae of AE showed a high MMP-9/TIMP-1 ratio in the subacute period. Our study demonstrates that elevation of serum MMP-9/TIMP-1 ratio in the subacute period may be a predictive factor of sequelae of AE.

Elevated Serum Matrix Metalloproteinase-9, Interleukin-6, Hypersensitive C-Reactive Protein, and Homocysteine Levels in Patients with Epilepsy

Neuroinflammation contributes to the occurrence and development of epilepsy. However, several inflammatory factors that are important for facilitating the diagnosis to reduce or prevent seizures need to be further studied. This study is aimed to explore serum levels of matrix metalloproteinase-9 (MMP-9), interleukin-6 (IL-6), hypersensitive C-reactive protein (hs-CRP), and homocysteine (HCY) in epilepsy patients and the relationship of them with epilepsy. Epilepsy patients (n = 101) in the Second Xiangya Hospital from January 2017 to August 2018 were allocated to the epilepsy groups, which were divided into idiopathic epilepsy group (n = 43) and symptomatic epilepsy group (n = 58) according to the pathogeny. Healthy individuals (n = 50) were allocated to the control group. The concentrations of serum MMP-9, IL-6, hs-CRP, and HCY in all samples were detected by enzyme-linked immunosorbent assay, chemiluminescence method, latex-enhanced immunoturbidimetry, and enzyme circulation method. The levels of serum MMP-9, IL-6, hs-CRP, and HCY in epilepsy patients were higher than those in the control group (P < 0.05, P < 0.01, P < 0.01, and P < 0.01, respectively). The levels of serum MMP-9, IL-6, hs-CRP, and HCY in the symptomatic epilepsy group were higher than those in the control group (P < 0.01 or P < 0.05, respectively). The levels of serum MMP-9, IL-6, and hs-CRP in idiopathic epilepsy patients were higher than those in the control group (P < 0.01 or P < 0.05, respectively). The serum HCY level in the idiopathic epilepsy group was lower than that in the symptomatic epilepsy group (P < 0.01). MMP-9, IL-6, hs-CRP, and HCY may be recommended as the state biomarker to distinguish etiology of epilepsy. We hope our study could provide help in some ways for clinical diagnosis and treatment.

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.

The role of UCH-L1, MMP-9, and GFAP as peripheral markers of different susceptibility to seizure development in a preclinical model of epilepsy

In our study, we assessed the potency of the brain-derived proteins ubiquitin carboxy-terminal hydrolase L1 (UCH-L1), matrix metalloproteinase 9 (MMP-9), glial fibrillary acidic protein (GFAP) and the immune activation indicators interleukin 1β (IL-1β) and interleukin 6 (IL-6) as peripheral biomarkers of different susceptibilities to kindling in a preclinical model. We observed increased plasma UCH-L1 levels in kindled vs. control animals. Furthermore, MMP-9 and IL-1β concentrations were the lowest in rats resistant to kindling. In summary, UCH-L1 is an indicator of neuronal loss and BBB disruption after seizure. MMP-9 and IL-1β may indicate resistance to kindling. UCH-L1, MMP-9 and IL-1β may have utility as peripheral biomarkers with translational potency in the clinic.

Advances in the Potential Biomarkers of Epilepsy

Epilepsy is a group of chronic neurological disorders characterized by recurrent, spontaneous, and unpredictable seizures. It is one of the most common neurological disorders, affecting tens of millions of people worldwide. Comprehensive studies on epilepsy in recent decades have revealed the complexity of epileptogenesis, in which immunological processes, epigenetic modifications, and structural changes in neuronal tissues have been identified as playing a crucial role. This review discusses the recent advances in the biomarkers of epilepsy. We evaluate the possible molecular background underlying the clinical changes observed in recent studies, focusing on therapeutic investigations, and the evidence of their safety and efficacy in the human population. This article reviews the pathophysiology of epilepsy, including recent reports on the effects of oxidative stress and hypoxia, and focuses on specific biomarkers and their clinical implications, along with further perspectives in epilepsy research.

Early Intervention With Adrenocorticotropin for Acute Encephalopathy-Associated Epileptic Spasms: Report of Two Cases

PURPOSE

Acute encephalopathy with biphasic seizures and reduced diffusion (AESD) is a leading cause of childhood-onset encephalopathy in Japan. Children with AESD frequently develop intractable epilepsy, whereas their treatment options remain to be determined.

METHOD

We present 2 unrelated girls, who developed AESD at 25 months (case 1) and 12 months of age (case 2). Both cases underwent intensive cares from the first day of illness, whereas severe neurological impairments were left on discharge. They showed repeated signs of epileptic spasms at 2 months (case 1) and 8 months (case 2) after the onset of AESD. Video-monitoring electroencephalograms (EEG) detected the recurrent attacks accompanying slow-wave bursts and transient suppressions of the precedent epileptiform discharges, as typically observed in epileptic spasms.

RESULTS

Intramuscular injection of adrenocorticotropic hormone (ACTH, 0.0125 mg/kg/d) was introduced within 1 month from the onset of epileptic spasms and continued for 2 weeks. The ACTH treatment disrupted the paroxysmal activity in EEG, and it has relieved these patients from epileptic seizures for more than 1 year.

CONCLUSION

This report illustrates the potential efficacy of ACTH for a group of children with epileptic spasms after AESD.

Pathophysiology of Trans-Synaptic Adhesion Molecules: Implications for Epilepsy

Chemical synapses are specialized interfaces between neurons in the brain that transmit and modulate information, thereby integrating cells into multiplicity of interacting neural circuits. Cell adhesion molecules (CAMs) might form trans-synaptic complexes that are crucial for the appropriate identification of synaptic partners and further for the establishment, properties, and dynamics of synapses. When affected, trans-synaptic adhesion mechanisms play a role in synaptopathies in a variety of neuropsychiatric disorders including epilepsy. This review recapitulates current understanding of trans-synaptic interactions in pathophysiology of interneuronal connections. In particular, we discuss here the possible implications of trans-synaptic adhesion dysfunction for epilepsy.

Early prognostic factors for acute encephalopathy with reduced subcortical diffusion

OBJECTIVE

The aim of this study was to determine the prognostic factors for acute encephalopathy with reduced diffusion (AED) during the acute phase through retrospective case evaluation.

METHODS

The participants included 23 patients with AED. The diagnosis of AED was based on their clinical course and radiological findings. We divided the patients into severe and non-severe groups based on the neurodevelopmental outcome. The severe group included seven patients (median age, 21 months; range, 6-87 months) and the non-severe group included 16 patients (19 months, 9-58 months). Clinical symptoms, laboratory data and electroencephalogram (EEG) findings within 48 h from the initial seizure onset were compared between the two groups to identify neurological outcome predictors.

RESULTS

The incidence of coma 12-24 h after onset, serum creatinine (Cr) levels within 2 h after onset, maximum aspartate aminotransferase (AST) levels within 24 h after onset, and the rate of electrographic seizures in EEG were significantly higher in the severe group (Coma, 80%; Cr, 0.40 mg/dl, 0.37-0.73; AST, 363 IU/L, 104-662; electrographic seizures, 80%) than the non-severe group (Coma, 0%; Cr, 0.29 mg/dL, 0.19-0.45; AST, 58.5 IU/L, 30-386; electrographic seizures, 0%).

CONCLUSIONS

Coma 12-24 h after onset, elevation of Cr levels within 2 h after onset, elevation of AST levels within 24 h after onset, and non-convulsive status epileptics (NCSE) in comatose patients were early predictors of severe AED. Patients in a coma after a febrile seizure should be checked for NCSE signs in EEG to terminate NCSE without delay.

Elevation of MMP-9 Levels Promotes Epileptogenesis After Traumatic Brain Injury

Posttraumatic epilepsy (PTE) is a recurrent seizure disorder that often develops secondary to traumatic brain injury (TBI) that is caused by an external mechanical force. Recent evidence shows that the brain extracellular matrix plays a major role in the remodeling of neuronal connections after injury. One of the proteases that is presumably responsible for this process is matrix metalloproteinase-9 (MMP-9). The levels of MMP-9 are elevated in rodent brain tissue and human blood samples after TBI. However, no studies have described the influence of MMP-9 on the development of PTE. The present study used controlled cortical impact (CCI) as a mouse model of TBI. We examined the detailed kinetics of MMP-9 levels for 1 month after TBI and observed two peaks after injury (30 min and 6 h after injury). We tested the hypothesis that high levels of MMP-9 predispose individuals to the development of PTE, and MMP-9 inhibition would protect against PTE. We used transgenic animals with either MMP-9 knockout or MMP-9 overexpression. MMP-9 overexpression increased the number of mice that exhibited TBI-induced spontaneous seizures, and MMP-9 knockout decreased the appearance of seizures. We also evaluated changes in responsiveness to a single dose of the chemoconvulsant pentylenetetrazol. MMP-9-overexpressing mice exhibited a significantly shorter latency between pentylenetetrazol administration and the first epileptiform spike. MMP-9 knockout mice exhibited the opposite response profile. Finally, we found that the occurrence of PTE was correlated with the size of the lesion after injury. Overall, our data emphasize the contribution of MMP-9 to TBI-induced structural and physiological alterations in brain circuitry that may lead to the development of PTE.

Proteolytic Remodeling of Perineuronal Nets: Effects on Synaptic Plasticity and Neuronal Population Dynamics

The perineuronal net (PNN) represents a lattice-like structure that is prominently expressed along the soma and proximal dendrites of parvalbumin- (PV-) positive interneurons in varied brain regions including the cortex and hippocampus. It is thus apposed to sites at which PV neurons receive synaptic input. Emerging evidence suggests that changes in PNN integrity may affect glutamatergic input to PV interneurons, a population that is critical for the expression of synchronous neuronal population discharges that occur with gamma oscillations and sharp-wave ripples. The present review is focused on the composition of PNNs, posttranslation modulation of PNN components by sulfation and proteolysis, PNN alterations in disease, and potential effects of PNN remodeling on neuronal plasticity at the single-cell and population level.

Activity-dependent proteolytic cleavage of cell adhesion molecules regulates excitatory synaptic development and function

Activity-dependent remodeling of neuronal connections is critical to nervous system development and function. These processes rely on the ability of synapses to detect neuronal activity and translate it into the appropriate molecular signals. One way to convert neuronal activity into downstream signaling is the proteolytic cleavage of cell adhesion molecules (CAMs). Here we review studies demonstrating the mechanisms by which proteolytic processing of CAMs direct the structural and functional remodeling of excitatory glutamatergic synapses during development and plasticity. Specifically, we examine how extracellular proteolytic cleavage of CAMs switches on or off molecular signals to 1) permit, drive, or restrict synaptic maturation during development and 2) strengthen or weaken synapses during adult plasticity. We will also examine emerging studies linking improper activity-dependent proteolytic processing of CAMs to neurological disorders such as schizophrenia, brain tumors, and Alzheimer's disease. Together these findings suggest that the regulation of activity-dependent proteolytic cleavage of CAMs is vital to proper brain development and lifelong function.

Matrix Metalloproteinase 9 in Epilepsy: The Role of Neuroinflammation in Seizure Development

Matrix metalloproteinase 9 is a proteolytic enzyme which is recently one of the more often studied biomarkers. Its possible use as a biomarker of neuronal damage in stroke, heart diseases, tumors, multiple sclerosis, and epilepsy is being widely indicated. In epilepsy, MMP-9 is suggested to play a role in epileptic focus formation and in the stimulation of seizures. The increase of MMP-9 activity in the epileptic focus was observed both in animal models and in clinical studies. MMP-9 contributes to formation of epileptic focus, for example, by remodeling of synapses. Its proteolytic action on the elements of blood-brain barrier and activation of chemotactic processes facilitates accumulation of inflammatory cells and induces seizures. Also modification of glutamatergic transmission by MMP-9 is associated with seizures. In this review we will try to recapitulate the results of previous studies about MMP-9 in terms of its association with epilepsy. We will discuss the mechanisms of its actions and present the results revealed in animal models and clinical studies. We will also provide a comparison of the results of various studies on MMP-9 levels in the context of its possible use as a biomarker of the activity of epilepsy.

Matrix metalloproteinases in the brain and blood-brain barrier: Versatile breakers and makers

Matrix metalloproteinases are versatile endopeptidases with many different functions in the body in health and disease. In the brain, matrix metalloproteinases are critical for tissue formation, neuronal network remodeling, and blood-brain barrier integrity. Many reviews have been published on matrix metalloproteinases before, most of which focus on the two best studied matrix metalloproteinases, the gelatinases MMP-2 and MMP-9, and their role in one or two diseases. In this review, we provide a broad overview of the role various matrix metalloproteinases play in brain disorders. We summarize and review current knowledge and understanding of matrix metalloproteinases in the brain and at the blood-brain barrier in neuroinflammation, multiple sclerosis, cerebral aneurysms, stroke, epilepsy, Alzheimer's disease, Parkinson's disease, and brain cancer. We discuss the detrimental effects matrix metalloproteinases can have in these conditions, contributing to blood-brain barrier leakage, neuroinflammation, neurotoxicity, demyelination, tumor angiogenesis, and cancer metastasis. We also discuss the beneficial role matrix metalloproteinases can play in neuroprotection and anti-inflammation. Finally, we address matrix metalloproteinases as potential therapeutic targets. Together, in this comprehensive review, we summarize current understanding and knowledge of matrix metalloproteinases in the brain and at the blood-brain barrier in brain disorders.

The multifaceted role of metalloproteinases in physiological and pathological conditions in embryonic and adult brains

Matrix metalloproteinases (MMPs) are a large family of ubiquitous extracellular endopeptidases, which play important roles in a variety of physiological and pathological conditions, from the embryonic stages throughout adult life. Their extraordinary physiological "success" is due to concomitant broad substrate specificities and strict regulation of their expression, activation and inhibition levels. In recent years, MMPs have gained increasing attention as significant effectors in various aspects of central nervous system (CNS) physiology. Most importantly, they have been recognized as main players in a variety of brain disorders having different etiologies and evolution. A common aspect of these pathologies is the development of acute or chronic neuroinflammation. MMPs play an integral part in determining the result of neuroinflammation, in some cases turning its beneficial outcome into a harmful one. This review summarizes the most relevant studies concerning the physiology of MMPs, highlighting their involvement in both the developing and mature CNS, in long-lasting and acute brain diseases and, finally, in nervous system repair. Recently, a concerted effort has been made in identifying therapeutic strategies for major brain diseases by targeting MMP activities. However, from this revision of the literature appears clear that MMPs have multifaceted functional characteristics, which modulate physiological processes in multiple ways and with multiple consequences. Therefore, when choosing MMPs as possible targets, great care must be taken to evaluate the delicate balance between their activation and inhibition and to determine at which stage of the disease and at what level they become active in order maximize chances of success.

Evaluation of serum matrix metalloproteinase-3 as a biomarker for diagnosis of epilepsy

OBJECTIVE

Reliable molecular biomarkers for epilepsy have yet to be identified. The present study aims to evaluate the utility of serum metalloproteinase-3 as a diagnostic biomarker for epilepsy.

METHODS

Serum MMP-3 levels were assessed in 227 individuals with epilepsy and 97 healthy control subjects. Individuals in the control group had no complaints or signs of any neurological disorder for at least 12months before serum collection. The Luminex FLEXMAP 3D assay was used to determine serum MMP-3 levels.

RESULTS

Compared with controls, subjects with epilepsy had significantly lower serum MMP-3 concentrations (p<0.05). Serum MMP-3 concentrations were significantly higher in males than in females (p<0.001). Furthermore, Serum MMP-3 concentrations were strongly correlated with age in both epileptic and control groups. For these reasons, ROC curve analyses were performed in age-matched and gender matched groups. In the population aged 20-40years, when cut-off values of 23.87ng/ml and 12.31ng/ml were chosen for MMP-3 in males and females respectively, the sensitivity and specificity for patients with epilepsy versus controls were 72.22% and 76.67% for males, and 45% and 94.12% for females. And when cut-off MMP-3 concentrations of 20.70ng/ml and 10.92ng/ml were chosen for the ≥40years age group, the sensitivity and specificity to distinguish between epileptic and control subjects were 85.71% and 47.62% versus 85.62% and 100% for male and female groups, respectively.

CONCLUSIONS

MMP-3 is reduced in epilepsy patients compared to healthy controls. The potential of MMP-3 as an epilepsy biomarker is limited to certain age brackets and depends on the gender.

MMP-9 in translation: from molecule to brain physiology, pathology, and therapy

Matrix metalloproteinase-9 (MMP-9) is a member of the metzincin family of mostly extracellularly operating proteases. Despite the fact that all of these enzymes might be target promiscuous, with largely overlapping catalogs of potential substrates, MMP-9 has recently emerged as a major and apparently unique player in brain physiology and pathology. The specificity of MMP-9 may arise from its very local and time-restricted actions, even when released in the brain from cells of various types, including neurons, glia, and leukocytes. In fact, the quantity of MMP-9 is very low in the naive brain, but it is markedly activated at the levels of enzymatic activity, protein abundance, and gene expression following various physiological stimuli and pathological insults. Neuronal MMP-9 participates in synaptic plasticity by controlling the shape of dendritic spines and function of excitatory synapses, thus playing a pivotal role in learning, memory, and cortical plasticity. When improperly unleashed, MMP-9 contributes to a large variety of brain disorders, including epilepsy, schizophrenia, autism spectrum disorder, brain injury, stroke, neurodegeneration, pain, brain tumors, etc. The foremost mechanism of action of MMP-9 in brain disorders appears to be its involvement in immune/inflammation responses that are related to the enzyme's ability to process and activate various cytokines and chemokines, as well as its contribution to blood-brain barrier disruption, facilitating the extravasation of leukocytes into brain parenchyma. However, another emerging possibility (i.e., the control of MMP-9 over synaptic plasticity) should not be neglected. The translational potential of MMP-9 has already been recognized in both the diagnosis and treatment domains. The most striking translational aspect may be the discovery of MMP-9 up-regulation in a mouse model of Fragile X syndrome, quickly followed by human studies and promising clinical trials that have sought to inhibit MMP-9. With regard to diagnosis, suggestions have been made to use MMP-9 alone or combined with tissue inhibitor of matrix metalloproteinase-1 or brain-derived neurotrophic factor as disease biomarkers. MMP-9, through cleavage of specific target proteins, plays a major role in synaptic plasticity and neuroinflammation, and by those virtues contributes to brain physiology and a host of neurological and psychiatric disorders. This article is part of the 60th Anniversary special issue.

Serum matrix metalloproteinase-2: A potential biomarker for diagnosis of epilepsy

OBJECTIVES

In this study, we evaluate the utility of serum metalloproteinase-2 (MMP-2) as a biomarker for the diagnosis of epilepsy.

METHODS

We assessed serum MMP-2 levels in 233 epileptic and 97 healthy control subjects. Control subjects had no complaints or signs of neurological disorders for at least 12 months prior to serum collection. Serum MMP-2 levels were determined using the Luminex technology.

RESULTS

Compared with controls, subjects with epilepsy had significantly lower serum MMP-2 concentrations (P<0.05). There was no significant difference between males and females in either group (P>0.05). Serum MMP-2 concentrations were highly correlated with age in both groups, and this correlation was strongest for males. When an MMP-2 cut-off value of 175.40ng/ml was used, the sensitivity for distinguishing subjects with epilepsy from controls was 71.13% and the specificity was 62.66%.

CONCLUSIONS

Our results reveal that serum MMP-2 may be a potential biomarker for the diagnosis of epilepsy.

In Sickness and in Health: Perineuronal Nets and Synaptic Plasticity in Psychiatric Disorders

Rapidly emerging evidence implicates perineuronal nets (PNNs) and extracellular matrix (ECM) molecules that compose or interact with PNNs, in the pathophysiology of several psychiatric disorders. Studies on schizophrenia, autism spectrum disorders, mood disorders, Alzheimer's disease, and epilepsy point to the involvement of ECM molecules such as chondroitin sulfate proteoglycans, Reelin, and matrix metalloproteases, as well as their cell surface receptors. In many of these disorders, PNN abnormalities have also been reported. In the context of the “quadripartite” synapse concept, that is, the functional unit composed of the pre- and postsynaptic terminals, glial processes, and ECM, and of the role that PNNs and ECM molecules play in regulating synaptic functions and plasticity, these findings resonate with one of the most well-replicated aspects of the pathology of psychiatric disorders, that is, synaptic abnormalities. Here we review the evidence for PNN/ECM-related pathology in these disorders, with particular emphasis on schizophrenia, and discuss the hypothesis that such pathology may significantly contribute to synaptic dysfunction.

A delicate balance: role of MMP-9 in brain development and pathophysiology of neurodevelopmental disorders

The extracellular matrix (ECM) is a critical regulator of neural network development and plasticity. As neuronal circuits develop, the ECM stabilizes synaptic contacts, while its cleavage has both permissive and active roles in the regulation of plasticity. Matrix metalloproteinase 9 (MMP-9) is a member of a large family of zinc-dependent endopeptidases that can cleave ECM and several cell surface receptors allowing for synaptic and circuit level reorganization. It is becoming increasingly clear that the regulated activity of MMP-9 is critical for central nervous system (CNS) development. In particular, MMP-9 has a role in the development of sensory circuits during early postnatal periods, called ‘critical periods.’ MMP-9 can regulate sensory-mediated, local circuit reorganization through its ability to control synaptogenesis, axonal pathfinding and myelination. Although activity-dependent activation of MMP-9 at specific synapses plays an important role in multiple plasticity mechanisms throughout the CNS, misregulated activation of the enzyme is implicated in a number of neurodegenerative disorders, including traumatic brain injury, multiple sclerosis, and Alzheimer’s disease. Growing evidence also suggests a role for MMP-9 in the pathophysiology of neurodevelopmental disorders including Fragile X Syndrome. This review outlines the various actions of MMP-9 during postnatal brain development, critical for future studies exploring novel therapeutic strategies for neurodevelopmental disorders.

Matrix metalloproteinases and epileptogenesis

Matrix metalloproteinases are vital drivers of synaptic remodeling in health and disease. It is suggested that at early stages of epileptogenesis, inhibition of matrix metalloproteinases may help ameliorate cell death, aberrant network rewiring, and neuroinflammation and prevent development of epilepsy.

Serum and cerebrospinal fluid levels of visinin-like protein-1 in acute encephalopathy with biphasic seizures and late reduced diffusion

BACKGROUND

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) has recently been recognized as an encephalopathy subtype. Typical clinical symptoms of AESD are biphasic seizures, and MRI findings show reduced subcortical diffusion during clustering seizures with unconsciousness after the acute phase. Visinin-like protein-1 (VILIP-1) is a recently discovered protein that is abundant in the central nervous system, and some reports have shown that VILIP-1 may be a prognostic biomarker of conditions such as Alzheimer's disease, stroke, and brain injury.

METHODS

However, there have been no reports regarding serum and cerebrospinal fluid (CSF) levels of VILIP-1 in patients with AESD. We measured the serum and CSF levels of VILIP-1 in patients with AESD, and compared the levels to those in patients with prolonged febrile seizures (FS).

RESULTS

Both serum and CSF levels of VILIP-1 were significantly higher in patients with AESD than in patients with prolonged FS. Serum and CSF VILIP-1 levels were normal on day 1 of AESD.

CONCLUSIONS

Our results suggest that both serum and CSF levels of VILIP-1 may be one of predictive markers of AESD.

Matrix metalloproteinase-9 involvement in the structural plasticity of dendritic spines

Dendritic spines are the locus for excitatory synaptic transmission in the brain and thus play a major role in neuronal plasticity. The ability to alter synaptic connections includes volumetric changes in dendritic spines that are driven by scaffolds created by the extracellular matrix (ECM). Here, we review the effects of the proteolytic activity of ECM proteases in physiological and pathological structural plasticity. We use matrix metalloproteinase-9 (MMP-9) as an example of an ECM modifier that has recently emerged as a key molecule in regulating the morphology and dysmorphology of dendritic spines that underlie synaptic plasticity and neurological disorders, respectively. We summarize the influence of MMP-9 on the dynamic remodeling of the ECM via the cleavage of extracellular substrates. We discuss its role in the formation, modification, and maintenance of dendritic spines in learning and memory. Finally, we review research that implicates MMP-9 in aberrant synaptic plasticity and spine dysmorphology in neurological disorders, with a focus on morphological abnormalities of dendritic protrusions that are associated with epilepsy.

Roles of matrix metalloproteinases and their targets in epileptogenesis and seizures

Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) remodel the pericellular environment by regulating the cleavage of extracellular matrix proteins, cell surface components, neurotransmitter receptors, and growth factors, which together regulate cell adhesion, synaptogenesis, synaptic plasticity, and long-term potentiation. Increased MMP activity and dysregulation of the balance between MMPs and TIMPs have also been implicated in various pathological conditions. Recent studies have suggested that prolonged seizures are associated with high MMP levels in serum and neural tissues, and certain extracellular macromolecule targets may influence the pathogenesis of epilepsy and seizure. In this review, we discuss the roles of MMP activation in animal models of epilepsy.

Matrix metalloproteinase-9 (MMP-9) in human intractable epilepsy caused by focal cortical dysplasia

Focal cortical dysplasia (FCD) is a developmental brain disorder characterized by localized abnormalities of cortical layering and neuronal morphology. It is associated with pharmacologically intractable forms of epilepsy in both children and adults. The mechanisms that underlie FCD-associated seizures and lead to the progression of the disease are unclear. Matrix metalloproteinases (MMPs) are enzymes that are able to influence neuronal function through extracellular proteolysis in various normal and pathological conditions. The results of experiments that have used rodent models showed that extracellular MMP-9 can play an important role in epileptogenesis. However, no studies have shown that MMP-9 is involved in the pathogenesis of human epilepsy. The aim of the present study was to determine whether MMP-9 plays a role in intractable epilepsy. Using an unbiased antibody microarray approach, we found that up regulation of MMP-9 is prominent and consistent in FCD tissue derived from epilepsy surgery, regardless of the patient's age. Additionally, an up regulation of MMP-1, -2, -8, -10, and -13 was found but was either less pronounced or limited only to adult cases. In the dysplastic cortex, immunohistochemistry revealed that the highest MMP-9 immuno reactivity occurred in the cytoplasm of abnormal neurons and balloon cells. The neuronal over expression of MMP-9 also occurred in sclerotic hippocampi that were excised together with the dysplastic cortex, but sclerotic hippocampi were free of dysplastic features. In both locations, MMP-9 was also found in reactive astrocytes, albeit to a lesser extent. At the subcellular level, increased MMP-9 immunoreactivity was prominently upregulated at synapses. Thus, although upregulation of the enzyme in FCD is not causally linked to the developmental malformation, it may be a result of ongoing abnormal synaptic plasticity. The present findings support the hypothesis of the pathogenic role of MMP-9 in human epilepsy and may stimulate discussions about whether MMPs could be novel therapeutic targets for intractable epilepsy.

Neural functions of matrix metalloproteinases: plasticity, neurogenesis, and disease

The brain changes in response to experience and altered environment. To do that, the nervous system often remodels the structures of neuronal circuits. This structural plasticity of the neuronal circuits appears to be controlled not only by intrinsic factors, but also by extrinsic mechanisms including modification of the extracellular matrix. Recent studies employing a range of animal models implicate that matrix metalloproteinases regulate multiple aspects of the neuronal development and remodeling in the brain. This paper aims to summarize recent advances of our knowledge on the neuronal functions of matrix metalloproteinases and discuss how they might relate in neuronal disease.

Matrix metalloproteinases contribute to neuronal dysfunction in animal models of drug dependence, Alzheimer's disease, and epilepsy

Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) remodel the pericellular environment by regulating the cleavage of extracellular matrix proteins, cell surface components, neurotransmitter receptors, and growth factors that mediate cell adhesion, synaptogenesis, synaptic plasticity, and long-term potentiation. Interestingly, increased MMP activity and dysregulation of the balance between MMPs and TIMPs have also been implicated in various pathologic conditions. In this paper, we discuss various animal models that suggest that the activation of the gelatinases MMP-2 and MMP-9 is involved in pathogenesis of drug dependence, Alzheimer's disease, and epilepsy.

Matrix metalloproteinase-9 contributes to kindled seizure development in pentylenetetrazole-treated mice by converting pro-BDNF to mature BDNF in the hippocampus

Recurrent seizure activity has been shown to induce a variety of permanent structural changes in the brain. Matrix metalloproteinases (MMPs) function to promote neuronal plasticity, primarily through cleavage of extracellular matrix proteins. Here, we investigated the role of MMP-9 in the development of pentylenetetrazole (PTZ)-induced kindled seizure in mice. Repeated treatment with PTZ (40 mg/kg) produced kindled seizure, which was accompanied by enhanced MMP-9 activity and expression in the hippocampus. No change in MMP-9 activity was observed in the hippocampi of mice with generalized tonic seizure following single administration of PTZ (60 mg/kg). MMP-9 colocalized with the neuronal marker NeuN and the glial marker GFAP in the dentate gyrus of the kindled mouse hippocampus. Coadministration of diazepam or MK-801 with PTZ inhibited the development of kindling and the increased MMP-9 levels in the hippocampus. Marked suppression of kindled seizure progression in response to repeated PTZ treatment was observed in MMP-9((-/-)) mice compared with wild-type mice, an observation that was accompanied by decreased hippocampal levels of mature brain-derived neurotrophic factor. Microinjecting the BDNF scavenger TrkB-Fc into the right ventricle before each PTZ treatment significantly suppressed the development of kindling in wild-type mice, whereas no effect was observed in MMP-9((-/-)) mice. On the other hand, bilateral injections of pro-BDNF into the hippocampal dentate gyrus significantly enhanced kindling in wild-type mice but not MMP-9((-/-)) mice. These findings suggest that MMP-9 is involved in the progression of behavioral phenotypes in kindled mice because of conversion of pro-BDNF to mature BDNF in the hippocampus.