authors: Vezzani A., Lang B., Aronica E.
Cold Spring Harb Perspect Med. 2015 Dec 18; 6(2). pii: a022699. doi: 10.1101/cshperspect.a022699
This review reports the available evidence on the activation of the innate and adaptive branches of the immune system and the related inflammatory processes in epileptic disorders and the putative pathogenic role of inflammatory processes developing in the brain, as indicated by evidence from experimental and clinical research. Indeed, there is increasing knowledge supporting a role of specific inflammatory mediators and immune cells in the generation and recurrence of epileptic seizures, as well as in the associated neuropathology and comorbidities. Major challenges in this field remain: a better understanding of the key inflammatory pathogenic pathways activated in chronic epilepsy and during epileptogenesis, and how to counteract them efficiently without altering the homeostatic tissue repair function of inflammation. The relevance of this information for developing novel therapies will be highlighted.
authors: van Scheppingen J., Iyer AM., Prabowo AS., Mühlebner A., Anink JJ., Scholl T., Feucht M., Jansen FE., Spliet WG., Krsek P., Zamecnik J., Buccoliero AM., Giordano F., Genitori L., Kotulska K., Jozwiak S., Jaworski J., Liszewkska E., van Vliet EA., Aronica E.
Glia. 2016 Mar 25. doi: 10.1002/glia.22983.
Tuberous sclerosis complex (TSC) is a genetic disease presenting with multiple neurological symptoms including epilepsy, mental retardation and autism. Abnormal activation of various inflammatory pathways has been observed in astrocytes in brain lesions associated with TSC. Increasing evidence supports the involvement of miRNAs in the regulation of astrocyte-mediated inflammatory response. To study the role of inflammation-related microRNAs in TSC, we employed real-time qPCR and in situ hybridization to characterize the expression of miR21, miR146a, and miR155 in TSC lesions (cortical tubers and subependymal giant cell astrocytomas, SEGAs). We observed an increased expression of miR21, miR146a, and miR155 in TSC tubers compared with control and perituberal brain tissue. Expression was localized in dysmorphic neurons, giant cells, and reactive astrocytes and positively correlated with IL-1B expression. In addition, cultured human astrocytes and SEGA-derived cell cultures were used to study the regulation of the expression of these miRNAs in response to the proinflammatory cytokine IL-1B and to evaluate the effects of overexpression or knockdown of miR21, miR146a, and miR155 on inflammatory signaling. IL-1B stimulation of cultured glial cells strongly induced intracellular miR21, miR146a, and miR155 expression, as well as miR146a extracellular release. IL-1B signaling was differentially modulated by overexpression of miR155 or miR146a, which resulted in pro- or anti-inflammatory effects, respectively. This study provied supportive evidence that inflammation-related microRNAs play a role in TSC. In particular, miR146a and miR155 appear to be key players in the regulation of astrocyte-mediated inflammatory response, with miR146a as most interesting anti-inflammatory therapeutic candidate.
authors: Mühlebner A., Iyer AM., van Scheppingen J., Anink JJ., Jansen FE., Veersema TJ., Braun KP., Spliet WG., Van Hecke W., Söylemezoglu F., Feucht M., Krsek P., Zamecnik J., Bien CG., Polster T., Coras R., Blümcke I., Aronica E.
J Neurodev Disord. 2016 Apr 2;8:9. doi: 10.1186/s 11689-016-9142-0.
Background: Tuberous sclerosis complex (TSC) is a multisystem disorder that results from mutations in the TSC1 or TSC genes, leading to constitutive activation of the mammalian target of rapamycin (mTOR) signaling pathway. Cortical tubers represent typical lesions of the central nervous system (CNS) in TSC. The pattern of cortical layering disruption observed in brain tissue of TSC patients is not yet fully understood, and little is known about the origin and phenotype of individual abnormal cell types recognized in tubers.
Methods: In the present study, we aimed to characterize dysmorphic neurons (DNs) and giant cells (GCs) of cortical tubers using neocortical layer-specific markers (NeuN, SMI32, Tbr1, Satb2, Cux2, ER81 and RORB) and to compare the features with the histo-morphologically similar focal cortical dysplacia (FCD) type IIb. We studied a cohort of nine surgically resected cortical tubers, five FCD type IIb, and four samples using immunohistochemistry and in situ hybridization.
Results: Cortical tuber displayed a prominent cell loss in all cortical layers. Moreover, we observed altered proportions of layer-specific markers within the dysplastic region. DNs, in both tubers and FCD type IIb, were found positive for different cortical layer markers, regardless of their laminar location, and their immunophenotype resembles that of cortical projection neurons.
Conclusions: These findings demonstrate that, similar to FCD type IIb, cortical layering is markedly disturbed in cortical tubers of TSC patients. Distribution of these disturbances is comparable in all tubers and suggests a dysmaturation affecting early and late migratory patterns, with a more severe impairment of the late stage of maturation.
Authors: Businaro R., Corsi M., Azzara G., Di Raimo T., Laviola G., Romano E., Ricci L., Maccarrone M., Aronica E., Fuso A., Ricci S.
Journal of Neuroinflammation (2016) 13:2. DOI: 10.1186/s12974-015-0466-6
Background: Autism spectrum disorder (ASD) is a neurodevelopmental disease which affects 1 in 88 children. Its etiology remains basically unknown, but it is apparent that neuroinflammation is involved in disease development. Great attention has been focused on pro-inflammatory cytokines, and several studies have reported their dysfunction unbalance in serum as well as in the brain. The present work aimed at evaluating putative dysregulation of interleukin-18 (IL-18), a pro-inflammatory cytokine of the IL-1 family in the sera of patients with ASD of different grades, compared to healthy controls, as well as in postmortem brain samples obtained from patients with tuberous sclerosis as well as acute inflammatory diseases. Moreover, quantitative analysis of IL-18 was performed in the sera and brain obtained from Reeler mice, an experimental model of autism.
Methods: Serum IL-18 levels were measured by ELISA. IL-18 was localized by immunohistochemical analysis in brain sections obtained from tuberous sclerosis and encephalitis patients, as well as from gender- and age-matched controls, and in the brain sections of both Reeler and wild-type mice. IL-18 was also quantified by Western blots in homogenates of Reeler and wild-type mice brains. IL-18 binding protein (IL-18BP) was evaluated in Reeler and wild-type mice plasma as well as in their brains (sections and homogenates).
Results: IL-18 content decreased in the sera of patients with autism compared to healthy subjects and in Reeler sera compared to wild-type controls. IL-18 was detected within glial cells and neurons in the brain of subjects affected by tuberous sclerosis and encephalitis whereas in healthy subjects, only a weak IL-18 positivity was detected at the level of glial cells. Western blot identified higher amounts of IL-18 in Reeler brain homogenates compared to wild-type littermates. IL-18BP was expressed in higher amounts in Reeler brain compared to the brain of wild-type mice, whereas no significant difference was detected comparing IL-18BP plasma levels.
Conclusions: IL-18 is dysregulated in ASD patients. Further studies seemed necessary to clarify the molecular details behind IL-18 increase in the brain and IL-18 decrease in the sera of patients. An increase in the size of the patient cohort seems necessary to ascertain whether decreased IL-18 content in the sera can become a predictive biomarker of ASD and whether its measure, in combination with other markers (e.g., increased levels of brain-derived neurotrophic factor (BDNF)), may be included in a diagnostic panel.
Authors: Malik A.R., Liszewska E., Skalecka A., Urbanska M., Iyer A.M., Swiech L.J., Perycz M., Parobczak K., Pietruszka P., Zarebska M.M., Macias M., Kotulska K., Borkowska J., Grajkowska W., Tyburczy M.E., Jozwiak S., Kwiatkowski D.J., Aronica E., Jaworski J.
Acta. Neuropathol. Commun. 2015 Jul 30;3(1):48. doi: 10.1186/s40478-015-0225-z
INTRODUCTION: Tuberous sclerosis complex (TSC) is a genetic disease resulting from mutation in TSC1 or TSC2 and subsequent hyperactivation of mammalian Target of Rapamycin (mTOR). Common TSC features include brain lesions, such as cortical tubers and subependymal giant cell astrocytomas (SEGAs). However, the current treatment with mTOR inhibitors has critical limitations. We aimed to identify new targets for TSC pharmacotherapy.
RESULTS: The results of our shRNA screen point to glutamate-cysteine ligase catalytic subunit (GCLC), a key enzyme in glutathione synthesis, as a contributor to TSC-related phenotype. GCLC inhibition increased cellular stress and reduced mTOR hyperactivity in TSC2-depleted neurons and SEGA-derived cells. Moreover, patients' brain tubers showed elevated GCLC and stress markers expression. Finally GCLC inhibition led to growth arrest and death of SEGA-derived cells.
CONCLUSIONS: We describe GCLC as a part of redox adaptation in TSC, needed for overgrowth and survival of mutant cells, and provide a potential novel target for SEGA treatment.