Epilepsy is a prevalent chronic neurological disorder affecting 50 million individuals globally, with temporal lobe epilepsy (TLE) being the most common form. Despite advances in antiepileptic drug development, over 30% of patients suffer from drug-resistant epilepsy, which can lead to severe cognitive impairments and adverse psychosocial outcomes.

To explore the role of bone marrow mesenchymal stem cell (BMSC)-derived exosomal miR-203 in the regulation of neuroinflammation in a mouse model of epilepsy, providing a theoretical basis for the development of targeted microRNA delivery therapies for drug-resistant epilepsy.

Adult male C57BL/6 mice were divided into a control group and a TLE model of 30 mice each, and the TLE model group was established by injecting kainic acid. BMSCs were isolated from the mice, and exosomes were purified using ultracentrifugation. Exosomal miR-203 was identified and characterized using high-throughput sequencing and quantitative reverse-transcription polymerase chain reaction. The uptake of exosomes by hippocampal neurons and the subsequent effects on neuroinflammatory markers were assessed using in vitro cell culture models.

Exosomal miR-203 exhibited a significant upregulation in BMSCs derived from epileptic mice. In vitro investigations demonstrated the efficient internalization of these exosomes by hippocampal neurons, resulting in downregulation of suppressor of cytokine signaling 3 expression and activation of the nuclear factor kappaB pathway, ultimately leading to enhanced secretion of pro-inflammatory cytokines.

Our study identifies exosomal miR-203 as a key regulator of neuroinflammation in a mouse model of epilepsy. The findings suggest that targeting miR-203 may offer a novel therapeutic strategy for epilepsy by modulating the suppression of cytokine signaling 3/nuclear factor kappaB pathway, thus providing a potential avenue for the development of cell-free therapeutics.

• Epilepsy
• Neuroinflammation
• MiR-203
• Exosomes
• Bone marrow mesenchymal stem cells
• Suppressor of cytokine signaling
• Nuclear factor kappaB

• MRI
• dog
• epilepsy
• inter-ictal
• normal
• structural

• University of Liverpool

• Cerebrospinal fluid
• epilepsy
• hippocampus
• seizure

• Cats
• Animals
• Retrospective Studies
• Epilepsy/diagnostic imaging
• Epilepsy/veterinary
• Seizures/veterinary
• Hippocampus/diagnostic imaging
• Magnetic Resonance Imaging/veterinary
• Cat Diseases/diagnostic imaging

• CSF
• albumin
• barrier dysfunction
• blood-CSF barrier
• cerebrospinal fluid
• immunoglobulin

• Canine
• Death
• Meningoencephalitis of unknown origin
• Obtundation
• Risk factors

The pathophysiology of changes in magnetic resonance imaging (MRI) detected after a seizure is not fully understood.

To characterize and describe seizure‐induced changes detected by MRI.

Eighty‐one client‐owned dogs diagnosed with idiopathic epilepsy.

Data collected retrospectively from medical records and included anatomical areas affected, T1‐, T2‐weighted and T2‐FLAIR (fluid‐attenuated inversion recovery) appearance, whether changes were unilateral or bilateral, symmetry, contrast enhancement, mass effect, and, gray and white matter distribution. Diffusion‐ and perfusion weighted maps were evaluated, if available.

Seizure‐induced changes were T2‐hyperintense with no suppression of signal on FLAIR. Lesions were T1‐isointense (55/81) or hypointense (26/81), local mass effect (23/81) and contrast enhancement (12/81). The majority of changes were bilateral (71/81) and symmetrical (69/71). The most common areas affected were the hippocampus (39/81) cingulate gyrus (33/81), hippocampus and piriform lobes (32/81). Distribution analysis suggested concurrence between cingulate gyrus and pulvinar thalamic nuclei, the cingulate gyrus and parahippocampal gyrus, hippocampus and piriform lobe, and, hippocampus and parahippocampal gyrus. Diffusion (DWI) characteristics were a mixed‐pattern of restricted, facilitated, and normal diffusion. Perfusion (PWI) showed either hypoperfusion (6/9) or hyperperfusion (3/9).

More areas, than previously reported, have been identified that could incur seizure‐induced changes. Similar to human literature, DWI and PWI changes have been identified that could reflect the underlying metabolic and vascular changes.

• MRI
• canine
• postictal
• seizures

• cerebrospinal fluid
• idiopathic epilepsy
• pleocytosis
• seizure

• MRI
• disease investigation
• dog
• epilepsy
• seizures

• GABA
• canine
• central nervous system
• epilepsy
• feline
• seizure

Epilepsy is one of the most common chronic neurological diseases in veterinary practice. Magnetic resonance imaging (MRI) is regarded as an important diagnostic test to reach the diagnosis of idiopathic epilepsy. However, given that the diagnosis requires the exclusion of other differentials for seizures, the parameters for MRI examination should allow the detection of subtle lesions which may not be obvious with existing techniques. In addition, there are several differentials for idiopathic epilepsy in humans, for example some focal cortical dysplasias, which may only apparent with special sequences, imaging planes and/or particular techniques used in performing the MRI scan. As a result, there is a need to standardize MRI examination in veterinary patients with techniques that reliably diagnose subtle lesions, identify post-seizure changes, and which will allow for future identification of underlying causes of seizures not yet apparent in the veterinary literature.

There is a need for a standardized veterinary epilepsy-specific MRI protocol which will facilitate more detailed examination of areas susceptible to generating and perpetuating seizures, is cost efficient, simple to perform and can be adapted for both low and high field scanners. Standardisation of imaging will improve clinical communication and uniformity of case definition between research studies. A 6–7 sequence epilepsy-specific MRI protocol for veterinary patients is proposed and further advanced MR and functional imaging is reviewed.

This article outlines the consensus proposal on diagnosis of epilepsy in dogs by the International Veterinary Epilepsy Task Force. The aim of this consensus proposal is to improve consistency in the diagnosis of epilepsy in the clinical and research settings. The diagnostic approach to the patient presenting with a history of suspected epileptic seizures incorporates two fundamental steps: to establish if the events the animal is demonstrating truly represent epileptic seizures and if so, to identify their underlying cause. Differentiation of epileptic seizures from other non-epileptic episodic paroxysmal events can be challenging. Criteria that can be used to make this differentiation are presented in detail and discussed. Criteria for the diagnosis of idiopathic epilepsy (IE) are described in a three-tier system. Tier I confidence level for the diagnosis of IE is based on a history of two or more unprovoked epileptic seizures occurring at least 24 h apart, age at epileptic seizure onset of between six months and six years, unremarkable inter-ictal physical and neurological examination, and no significant abnormalities on minimum data base blood tests and urinalysis. Tier II confidence level for the diagnosis of IE is based on the factors listed in tier I and unremarkable fasting and post-prandial bile acids, magnetic resonance imaging (MRI) of the brain (based on an epilepsy-specific brain MRI protocol) and cerebrospinal fluid (CSF) analysis. Tier III confidence level for the diagnosis of IE is based on the factors listed in tier I and II and identification of electroencephalographic abnormalities characteristic for seizure disorders. The authors recommend performing MRI of the brain and routine CSF analysis, after exclusion of reactive seizures, in dogs with age at epileptic seizure onset <6 months or >6 years, inter-ictal neurological abnormalities consistent with intracranial neurolocalisation, status epilepticus or cluster seizure at epileptic seizure onset, or a previous presumptive diagnosis of IE and drug-resistance with a single antiepileptic drug titrated to the highest tolerable dose.

This consensus article represents the basis for a more standardised diagnostic approach to the seizure patient. These recommendations will evolve over time with advances in neuroimaging, electroencephalography, and molecular genetics of canine epilepsy.