transforming-growth-factor-beta and Seizures

The blood-brain barrier (BBB), a unique anatomical and physiological interface between the central nervous system (CNS) and the peripheral circulation, is essential for the function of neural circuits. Interactions between the BBB, cerebral blood vessels, neurons, astrocytes, microglia, and pericytes form a dynamic functional unit known as the neurovascular unit (NVU). The NVU-BBB crosstalk plays a key role in the regulation of blood flow, response to injury, neuronal firing, and synaptic plasticity. Blood-brain barrier dysfunction (BBBD), a hallmark of brain injury, is a prominent finding in status epilepticus. Blood-brain barrier dysfunction is observed within the first hour of status epilepticus, and in epileptogenic brain regions, may last for months. Blood-brain barrier dysfunction was shown to have a role in astroglial dysfunction, neuroinflammation, increasing neural excitability, reduction of seizure threshold, excitatory synaptogenesis, impaired plasticity, and epileptogenesis. A key signaling pathway associated with BBBD-induced neurovascular dysfunction is the transforming growth factor beta (TGF-β) proinflammatory pathway, activated by the extravasation of serum albumin into the brain when BBB functions are compromised. Specific small molecules blocking TGF-β, and the nonspecific, Food and Drug Administration (FDA) approved blocker and angiotensin antagonist losartan, were shown to reduce BBBD and block epileptogenesis. With these encouraging preclinical data, we have developed imaging approach to quantitatively assess BBBD as a diagnostic, predictive, and pharmacodynamic biomarker after brain injury. Clinical trials in the foreseen future are expected to test the feasibility of BBB-targeted diagnostic coupled therapy in status epileptics and seizure disorders. This article is part of the Special Issue "Proceedings of the 7th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures".

Topics: Animals; Astrocytes; Blood-Brain Barrier; Brain; Humans; Microglia; Neurons; Seizures; Status Epilepticus; Transforming Growth Factor beta

Normal brain functioning emerges from a complex interplay among regions forming networks. In epilepsy, these networks are disrupted causing seizures. Highly connected nodes in these networks are epilepsy surgery targets. Here, we assess whether functional connectivity (FC) using intracranial electroencephalography can quantify brain regions epileptogenicity and predict surgical outcome in children with drug resistant epilepsy (DRE). We computed FC between electrodes on different states (i.e. interictal without spikes, interictal with spikes, pre-ictal, ictal, and post-ictal) and frequency bands. We then estimated the electrodes' nodal strength. We compared nodal strength between states, inside and outside resection for good- (n = 22, Engel I) and poor-outcome (n = 9, Engel II-IV) patients, respectively, and tested their utility to predict the epileptogenic zone and outcome. We observed a hierarchical epileptogenic organization among states for nodal strength: lower FC during interictal and pre-ictal states followed by higher FC during ictal and post-ictal states (p < 0.05). We further observed higher FC inside resection (p < 0.05) for good-outcome patients on different states and bands, and no differences for poor-outcome patients. Resection of nodes with high FC was predictive of outcome (positive and negative predictive values: 47-100%). Our findings suggest that FC can discriminate epileptogenic states and predict outcome in patients with DRE.

Topics: Brain; Child; Drug Resistant Epilepsy; Electrocorticography; Humans; Seizures; Transforming Growth Factor beta; Treatment Outcome

Toll-like receptor 4 (TLR4) signaling plays a detrimental role in traumatic brain injury (TBI) pathology. Pharmacologic or genetic inactivating TLR4 diminish TBI inflammation and neurological complications. Nonetheless, TLR4 priming alleviates TBI inflammation and seizure susceptibility. We investigated impact of postconditioning with TLR4 agonist monophosphoryl lipid A (MPL) on TBI neuroinflammation and epileptogenesis in rats. TBI was induced in temporo-parietal cortex of rats by Controlled Cortical Impact device. Then rats received a single dose (0.1 μg/rat) of MPL by intracerebroventricular injection. After 24 h, CCI-injured rats received intraperitoneal injection of pentylenetetrazole 35 mg/kg once every other day until acquisition of generalized seizures. The injury size, number of survived neurons, and brain protein level of TNF-α, TGF-β, IL-10, and arginase1 (Arg1) were determined. Astrocytes and macrophage/microglia activation/polarization was assessed by double immunostaining with anti GFAP/Arg1 or anti Iba1/Arg1 antibodies. The CCI-injured rats developed generalized seizures after 5.9 ± 1.3 pentylenetetrazole injections (p < 0.001, compared to 12.3 ± 1.4 injections for sham-operated rats). MPL treatment returned the accelerated rate of epileptogenesis in TBI state to the sham-operated level. MPL did not change damage volume but attenuated number of dead neurons (p < 0.01). MPL decreased TNF-α overexpression (6 h post-TBI p < 0.0001), upregulated expression of TGF-β (48 h post-TBI, p < 0.0001), and IL-10 (48 h post-TBI, p < 0.0001) but did not change Arg1 expression. GFAP/Arg1 and Iba1/Arg1 positive cells were detected in TBI area with no significant change following MPL administration. MPL administration after TBI reduces vulnerability to seizure acquisition through down regulating neural death and inflammation, and up-regulating anti-inflammatory cytokines. This capacity along with the clinical safety, makes MPL a potential candidate for development of drugs against neurological deficits of TBI.

Topics: Animals; Brain Injuries, Traumatic; Disease Models, Animal; Inflammation; Interleukin-10; Neuroinflammatory Diseases; Pentylenetetrazole; Rats; Seizures; Toll-Like Receptor 4; Transforming Growth Factor beta; Tumor Necrosis Factor-alpha

DBA/1 mice have a higher susceptibility to generalized audiogenic seizures (AGSz) and seizure-induced respiratory arrest (S-IRA) than C57/BL6 mice. The gene expression profile might be potentially related to this difference. This study aimed to investigate the susceptibility difference in AGSz and S-IRA between DBA/1 and C57BL/6 mice by profiling long noncoding RNAs (lncRNAs) and mRNA expression.. We compared lncRNAs and mRNAs from the brainstem of the two strains with Arraystar Mouse lncRNA Microarray V3.0 (Arraystar, Rockville, MD). Gene Ontology (GO) and pathway analyses were performed to determine the potentially related biological functions and pathways based on differentially expressed mRNAs. qRT-PCR was carried out to validate the results.. A total of 897 lncRNAs and 438 mRNAs were differentially expressed (fold change ≥2, P < 0.05), of which 192 lncRNAs were upregulated and 705 lncRNAs were downregulated. A total of 138 mRNAs were upregulated, and 300 mRNAs were downregulated. In terms of specific mRNAs, Htr5b, Gabra2, Hspa1b and Gfra1 may be related to AGSz or S-IRA. Additionally, lncRNA Neat1 may participate in the difference in susceptibility. GO and pathway analyses suggested that TGF-β signaling, metabolic process and MHC protein complex could be involved in these differences. Coexpression analysis identified 9 differentially expressed antisense lncRNAs and 115 long intergenic noncoding RNAs (lincRNAs), and 2010012P19Rik and its adjacent RNA Tnfsf12-Tnfsf13 may have participated in S-IRA by regulating sympathetic neuron function. The results of the qRT-PCR of five selected lncRNAs (AK038711, Gm11762, 1500004A13Rik, AA388235 and Neat1) and four selected mRNAs (Hspa1b, Htr5b, Gabra2 and Gfra1) were consistent with those obtained by microarray.. We concluded that TGF-β signaling and metabolic process may contribute to the differential sensitivity to AGSz and S-IRA. Among mRNAs, Htr5b, Gabra2, Hspa1b and Gfra1 could potentially influence the susceptibility. LncRNA Neat1 and 2010012P19Rik may also contribute to the different response to sound stimulation. Further studies should be carried out to explore the underlying functions and mechanisms of differentially expressed RNAs.

Topics: Animals; Brain Stem; Mice; Mice, Inbred C57BL; Mice, Inbred DBA; RNA, Long Noncoding; RNA, Messenger; Seizures; Transcriptome; Transforming Growth Factor beta

Zinc-α2-glycoprotein (ZAG) is a 42-kDa protein reported as an anti-inflammatory adipocytokine. Evidences from clinical and experimental studies revealed that brain inflammation plays important roles in epileptogenesis and seizure. Interestingly, closely relationship between ZAG and many important inflammatory mediators has been proven. Our previous study identified ZAG in neurons and found that ZAG is decreased in epilepsy and interacts with TGFβ and ERK. This study aimed to investigate the role of ZAG in seizure and explore its effect on seizure-related neuroinflammation.. We overexpressed AZGP1 in the hippocampus of rats via adeno-associated virus vector injection and observed their seizure behavior and EEG after pentylenetetrazol (PTZ) kindling. The level of typical inflammation mediators including TNFα, IL-6, TGFβ, ERK, and ERK phosphorylation were determined.. The overexpression of AZGP1 reduced the seizure severity, prolonged the latency of kindling, and alleviated epileptiform discharges in EEG changes induced by PTZ. Overexpression of AZGP1 also suppressed the expression of TNFα, IL-6, TGFβ, and ERK phosphorylaton in PTZ-kindled rats.. ZAG may inhibit TGFβ-mediated ERK phosphorylation and inhibit neuroinflammation mediated by TNFα and IL-6, suggesting ZAG may suppress seizure via inhibiting neuroinflammation. ZAG may be a potential and novel therapeutic target for epilepsy.

Topics: Adipokines; Animals; Brain Waves; Carrier Proteins; Convulsants; Cytokines; Disease Models, Animal; eIF-2 Kinase; Electroencephalography; Encephalitis; Gene Expression Regulation; Glycoproteins; Green Fluorescent Proteins; Hippocampus; Kindling, Neurologic; Male; Pentylenetetrazole; Rats; Rats, Sprague-Dawley; RNA, Messenger; Seizures; Signal Transduction; Time Factors; Transduction, Genetic; Transforming Growth Factor beta

Post-injury epilepsy (PIE) is a common complication following brain insults, including ischemic, and traumatic brain injuries. At present, there are no means to identify the patients at risk to develop PIE or to prevent its development. Seizures can occur months or years after the insult, do not respond to anti-seizure medications in over third of the patients, and are often associated with significant neuropsychiatric morbidities. We have previously established the critical role of blood-brain barrier dysfunction in PIE, demonstrating that exposure of brain tissue to extravasated serum albumin induces activation of inflammatory transforming growth factor beta (TGF-β) signaling in astrocytes and eventually seizures. However, the link between the acute astrocytic inflammatory responses and reorganization of neural networks that underlie recurrent spontaneous seizures remains unknown. Here we demonstrate in vitro and in vivo that activation of the astrocytic ALK5/TGF-β-pathway induces excitatory, but not inhibitory, synaptogenesis that precedes the appearance of seizures. Moreover, we show that treatment with SJN2511, a specific ALK5/TGF-β inhibitor, prevents synaptogenesis and epilepsy. Our findings point to astrocyte-mediated synaptogenesis as a key epileptogenic process and highlight the manipulation of the TGF-β-pathway as a potential strategy for the prevention of PIE.

Topics: Animals; Astrocytes; Blood-Brain Barrier; Disease Models, Animal; Epilepsy; Hippocampus; Protein Serine-Threonine Kinases; Receptor, Transforming Growth Factor-beta Type I; Receptors, Transforming Growth Factor beta; Seizures; Serum Albumin; Signal Transduction; Synapses; Transforming Growth Factor beta

Seizures have been shown to upregulate the expression of numerous extracellular matrix molecules. Tenascin C (TNC) is an extracellular matrix protein involved in several physiological roles and in pathological conditions. Though TNC upregulation has been described after excitotoxins injection, to date there is no research work on the signal transduction pathway(s) participating in TNC protein overproduction. The aim of this study was to evaluate the role of TGF-β signaling pathway on TNC upregulation. In this study, we used male rats, which were injected with saline or pilocarpine to induce status epilepticus (SE) and killed 24h, 3 and 7 days after pilocarpine administration. For evaluating biochemical changes, we measured protein content of TNC, TGF-β1 and phospho-Smad2/3 for localization of TNC in coronal brain hippocampus at 24h, 3 and 7 days after pilocarpine-caused SE. We found a significant increase of TNC protein content in hippocampal homogenates after 1, 3, and 7 days of pilocarpine-caused SE, together with an enhancement of TNC immunoreactivity in several hippocampal layers and the dentate gyrus field where more dramatic changes occurred. We also observed a significant enhancement of protein content of both the TGF-β1 and the critical downstream transduction effector phospho-Smad2/3 throughout the chronic exposure. Interestingly, animals injected with SB-431542, a TGF-β-type I receptor inhibitor, decreased TNC content in cytosolic fraction and diminished phospho-Smad2/3 content in both cytoplasmic and nuclear fraction compared with pilocarpine vehicle-injected. These findings suggest the participation of TGF-β signaling pathway on upregulation of TNC which in turn support the idea that misregulation of this signaling pathway produces changes that may contribute to disease.

Topics: Animals; Benzamides; Cell Nucleus; Central Nervous System Agents; Cytoplasm; Dioxoles; Disease Models, Animal; Hippocampus; Male; Phosphorylation; Pilocarpine; Protein Serine-Threonine Kinases; Rats, Wistar; Receptor, Transforming Growth Factor-beta Type I; Receptors, Transforming Growth Factor beta; Seizures; Signal Transduction; Smad2 Protein; Smad3 Protein; Tenascin; Transforming Growth Factor beta; Up-Regulation

We demonstrate the establishment and characterization of a novel virus infection-induced seizure model in C57BL/6 mice.. C57BL/6 mice were infected with Theiler's murine encephalomyelitis virus (TMEV) or mock infected. Mice were followed for seizures, weight change, body temperature, motor function (righting reflex, rotorod) and neurological manifestations (inflammation [perivascular cuffing], pyknotic neurons, transforming growth factor [TGF]-beta expression).. C57BL/6 mice are susceptible to seizures induced by TMEV infection. Approximately 50% of C57BL/6 mice develop transient afebrile seizures. Motor function and coordination are impaired in seized mice. Pyramidal neuron pyknosis and TGF-beta expression correlate with seizure activity in the hippocampus.. The characterization of this model will enable the investigation of viral and immune contributions in the central nervous system to the development of seizure disorders in humans.

Topics: Animals; Brain; Cardiovirus Infections; Epilepsy, Tonic-Clonic; Female; Hippocampus; Immunoenzyme Techniques; Male; Mice; Mice, Inbred C57BL; Mice, Inbred Strains; Motor Skills; Neurons; Postural Balance; Reflex; Seizures; Theilovirus; Transforming Growth Factor beta

In order to evaluate the role of transforming growth factor (TGF)-beta3 in the neurodegenerative process, we examined the levels of mRNA and immunocytochemical distribution for TGF-beta3 in the rat hippocampus after systemic kainic acid (KA) administration. Hippocampal TGF-beta3 mRNA level was reduced 3 h after KA injection. However, the levels of TGF-beta3 mRNA were elevated 1 day post-KA and lasted for at least 30 days. A mild TGF-beta3 immunoreactivity (TGF-beta3-IR) in the Ammon's horn and a moderate TGF-beta3-IR in the dentate granule cells were observed in the normal hippocampus. The CA1 and CA3 neurons lost their TGF-beta3-IR, while TGF-beta3-positive glia-like cells proliferated mainly throughout the CA1 sector and had an intense immunoreactivity at 7, 15 and 30 days after KA. This immunocytochemical distribution of TGF-beta3-positive non-neuronal populations was similar to that of glial fibrillary acidic protein (GFAP)-positive cells. Double labeling immunocytochemical analysis demonstrated colocalization of TGF-beta3- and GFAP-immunoreactivity in the same cells. These findings suggest a compensatory mechanism of astrocytes for the synthesis of TGF-beta3 protein in response to KA-induced neurodegeneration. In addition, exogenous TGF-beta3 (5 or 10 ng/i.c.v.) significantly attenuated KA-induced seizures and neuronal damages in a dose-related manner. Therefore, our results suggest that TGF-beta3 plays an important role in protective mechanisms against KA-induced neurodegeneration.

Topics: Animals; Behavior, Animal; Cell Size; Excitatory Amino Acid Agonists; Glial Fibrillary Acidic Protein; Hippocampus; Immunohistochemistry; Kainic Acid; Male; Neuroglia; Neuroprotective Agents; Rats; Rats, Inbred F344; Seizures; Transforming Growth Factor beta; Transforming Growth Factor beta3

Topics: Activins; Animals; Fibroblast Growth Factor 2; Inhibins; Kainic Acid; Mice; Neurons; Neuroprotective Agents; Seizures; Transforming Growth Factor beta

A number of important neurological diseases, including HIV-1 encephalitis, Alzheimer's disease, and brain trauma, are associated with increased cerebral expression of the multifunctional cytokine transforming growth factor-beta 1 (TGF-beta 1). To determine whether overexpression of TGF-beta 1 within the central nervous system (CNS) can contribute to the development of neuropathological alterations, a bioactive form of TGF-beta 1 was expressed in astrocytes of transgenic mice. Transgenic mice with high levels of cerebral TGF-beta 1 expression developed a severe communicating hydrocephalus, seizures, motor incoordination, and early runting. While unmanipulated heterozygous transgenic mice from a low expressor line showed no such alterations, increasing TGF-beta 1 expression in this line by injury-induced astroglial activation or generation of homozygous offspring did result in the abnormal phenotype. Notably, astroglial overexpression of TGF-beta 1 consistently induced a strong upmodulation of the extracellular matrix proteins laminin and fibronectin in the CNS, particularly in the vicinity of TGF-beta 1-expressing perivascular astrocytes, but was not associated with obvious CNS infiltration by hematogenous cells. While low levels of extracellular matrix protein expression may assist in CNS wound repair and regeneration, excessive extracellular matrix deposition could result in the development of hydrocephalus. As an effective inducer of extracellular matrix components, TGF-beta 1 may also contribute to the development of other neuropathological alterations, eg, the formation of amyloid plaques in Alzheimer's disease.

Topics: Animals; Astrocytes; Brain; Extracellular Matrix Proteins; Gene Expression Regulation; Glial Fibrillary Acidic Protein; Hydrocephalus; Immunoblotting; Immunohistochemistry; Mice; Mice, Inbred BALB C; Mice, Transgenic; Microscopy, Confocal; RNA, Messenger; Seizures; Transforming Growth Factor beta

This study examined TGF-beta 1 mRNA levels and cellular localization in the F344 rat hippocampus following deafferentation or kainic acid (KA)-induced neurodegeneration. By RNA solution hybridization, TGF-beta 1 transcripts were at low prevalence in intact adult rat hippocampus (0.02 pg/microgram total RNA). Four days after unilateral entorhinal cortex lesioning (ECL), TGF-beta 1 mRNA increased threefold in the ipsilateral hippocampus. This increase was localized to the outer molecular layer of the dentate gyrus, where gliosis, synapse loss, and synaptic reorganization occur. TGF-beta 1 mRNA also increased in the hippocampus after KA-induced limbic seizures, particularly in the areas of the hippocampus undergoing neurodegeneration. Microglia [OX-42 immunoreactive (IR) cells] responded to these two lesions with distinct morphological changes. Combined immunocytochemistry-in situ hybridization showed that TGF-beta 1 mRNA was localized to reactive microglia (OX-42-IR, with blunt processes), but not to resting ramified microglia (OX-42-IR, with numerous fine processes) or to astrocytes (GFAP-IR). After ECL, round macrophage-like cells (OX-42-IR with TGF-beta 1 mRNA) were seen at the wound site. Thus, brain macrophage/microglial cells produce TGF-beta 1 mRNA in the hippocampus in response to deafferentation and neurodegeneration.

Topics: Afferent Pathways; Animals; Glial Fibrillary Acidic Protein; Hippocampus; Kainic Acid; Limbic System; Macrophages; Male; Mesoderm; Nerve Degeneration; Rats; Rats, Inbred F344; RNA, Messenger; Seizures; Temporal Lobe; Transforming Growth Factor beta