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Early tissue damage and microstructural reorganization predict disease severity in experimental epilepsy.

ABSTRACT: Mesial temporal lobe epilepsy (mTLE) is the most common focal epilepsy in adults and is often refractory to medication. So far, resection of the epileptogenic focus represents the only curative therapy. It is unknown whether pathological processes preceding epilepsy onset are indicators of later disease severity. Using longitudinal multi-modal MRI, we monitored hippocampal injury and tissue reorganization during epileptogenesis in a mouse mTLE model. The prognostic value of MRI biomarkers was assessed by retrospective correlations with pathological hallmarks Here, we show for the first time that the extent of early hippocampal neurodegeneration and progressive microstructural changes in the dentate gyrus translate to the severity of hippocampal sclerosis and seizure burden in chronic epilepsy. Moreover, we demonstrate that structural MRI biomarkers reflect the extent of sclerosis in human hippocampi. Our findings may allow an early prognosis of disease severity in mTLE before its first clinical manifestations, thus expanding the therapeutic window.

SUBMITTER: Janz P

PROVIDER: S-EPMC5529108 | biostudies-literature | 2017 Jul

REPOSITORIES: biostudies-literature

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Early tissue damage and microstructural reorganization predict disease severity in experimental epilepsy.

Janz Philipp P Schwaderlapp Niels N Heining Katharina K Häussler Ute U Korvink Jan G JG von Elverfeldt Dominik D Hennig Jürgen J Egert Ulrich U LeVan Pierre P Haas Carola A CA

eLife 20170726

Mesial temporal lobe epilepsy (mTLE) is the most common focal epilepsy in adults and is often refractory to medication. So far, resection of the epileptogenic focus represents the only curative therapy. It is unknown whether pathological processes preceding epilepsy onset are indicators of later disease severity. Using longitudinal multi-modal MRI, we monitored hippocampal injury and tissue reorganization during epileptogenesis in a mouse mTLE model. The prognostic value of MRI biomarkers was as ...[more]

PMID: 28746029

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Project description:Temporal lobe epilepsy (TLE), one of the most common pharmaco-resistant epilepsies, is associated with pathology of paralimbic brain regions, particularly in the mesiotemporal lobe. Cognitive dysfunction in TLE is frequent, and particularly affects episodic memory. Crucially, these difficulties challenge the quality of life of patients, sometimes more than seizures, underscoring the need to assess neural processes of cognitive dysfunction in TLE to improve patient management. Our work harnessed a novel conceptual and analytical approach to assess spatial gradients of microstructural differentiation between cortical areas based on high-resolution MRI analysis. Gradients track region-to-region variations in intracortical lamination and myeloarchitecture, serving as a system-level measure of structural and functional reorganization. Comparing cortex-wide microstructural gradients between 21 patients and 35 healthy controls, we observed a reorganization of this gradient in TLE driven by reduced microstructural differentiation between paralimbic cortices and the remaining cortex with marked abnormalities in ipsilateral temporopolar and dorsolateral prefrontal regions. Findings were replicated in an independent cohort. Using an independent post-mortem dataset, we observed that in vivo findings reflected topographical variations in cortical cytoarchitecture. We indeed found that macroscale changes in microstructural differentiation in TLE reflected increased similarity of paralimbic and primary sensory/motor regions. Disease-related transcriptomics could furthermore show specificity of our findings to TLE over other common epilepsy syndromes. Finally, microstructural dedifferentiation was associated with cognitive network reorganization seen during an episodic memory functional MRI paradigm and correlated with interindividual differences in task accuracy. Collectively, our findings showing a pattern of reduced microarchitectural differentiation between paralimbic regions and the remaining cortex provide a structurally-grounded explanation for large-scale functional network reorganization and cognitive dysfunction characteristic of TLE.

Project description:BackgroundA dietary supplementation with conjugated linoleic acid (CLA) was shown to attenuate inflammation and increase the proportions of circulating regulatory T cells (Tregs) and M2-type macrophages in disease models such as autoimmune encephalitis and arteriosclerosis. Since Tregs and anti-inflammatory (M2-type) macrophages were found to enhance stroke recovery, we hypothesized that CLA-supplementation might improve stroke recovery via immune modulatory effects.MethodsFunctional assessment was performed over 90 days after induction of experimental photothrombotic stroke in wild type mice (n = 37, sham n = 10). Subsequently, immunological characterization of different immunological compartments (n = 16), ex vivo magnetic resonance (MR, n = 12) imaging and immunohistochemical staining (n = 8) was performed. Additionally, we tested the effect of CLA in vitro on peripheral blood mononuclear cells from human stroke patients and healthy controls (n = 12).ResultsMR diffusion tensor imaging (DTI) demonstrated enhanced microstructural reorganization of interhemispheric white matter tracts, dependent on lesion size. Functional recovery over 90 days remained unaffected. Detailed immunological analyses across various compartments revealed no significant long-term immunological alterations due to CLA. However, analyses of human blood samples post-stroke showed reduced levels of pro-inflammatory interferon-γ (IFN-γ) and tumor necrosis factor alpha (TNF-α) release by T-lymphocytes following in vitro treatment with CLA.ConclusionWe aimed to explore the efficacy of a dietary intervention with minimal known side effects that could be accessible to human stroke patients, regardless of the degree of disability, and without the risks associated with aggressive immunomodulatory therapies. Our main findings include improved microstructural reorganization in small infarcts and a reduced inflammatory response of human T cells in vitro.

Project description:BackgroundChronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an autoimmune-mediated inflammatory disease of the peripheral nervous system characterized by a response directed against certain myelin proteins and for which therapies are limited. Previous studies have suggested a beneficial role of FTY720, a sphingosine 1-phosphate (S1P) receptor agonist, known to deplete lymphocytes from the peripheral blood by sequestering them into lymph nodes, in the treatment of experimental autoimmune neuritis (EAN). Therefore, we investigated whether FTY720 is also beneficial in chronic experimental autoimmune neuritis (c-EAN), a recently developed rat model mimicking human CIDP.Methodsc-EAN was induced in Lewis rats by immunization with S-palm P0(180-199) peptide. Rats were treated with FTY720 (1 mg/kg) or vehicle intraperitoneally once daily from the onset of clinical signs for 18 days; clinical signs were assessed daily until 60 days post-immunization (dpi). Electrophysiological and histological features were examined at different time points. We also evaluated the serum levels of different pro- and anti-inflammatory cytokines by ELISA or flow cytometry at 18, 40, and 60 dpi.ResultsOur data demonstrate that FTY720 decreased the severity and abolished the chronicity of the disease in c-EAN rats. Therapeutic FTY720 treatment reversed electrophysiological and histological anomalies, suggesting that myelinated fibers were subsequently preserved, it inhibited macrophage and IL-17+ cell infiltration in PNS, and it significantly reduced circulating pro-inflammatory cytokines.ConclusionsFTY720 treatment has beneficial effects on c-EAN, a new animal model mimicking human CIDP. We have shown that FTY720 is an effective immunomodulatory agent, improving the disease course of c-EAN, preserving the myelinated fibers, attenuating the axonal degeneration, and decreasing the number of infiltrated inflammatory cells in peripheral nerves. These data confirm the interest of testing FTY720 or molecules targeting S1P in human peripheral neuropathies.

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Early tissue damage and microstructural reorganization predict disease severity in experimental epilepsy.

Publications

Early tissue damage and microstructural reorganization predict disease severity in experimental epilepsy.

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