title: NADPH oxidase activation and 4-hydroxy-2-nonenal/aquaporin-4 adducts as possible new players in oxidative neuronal damage presents in drug-resistant epilepsy.
abstract: A correlation between epilepsy and cellular redox imbalance has been suggested, although the mechanism by which oxidative stress (OS) can be implicated in this disorder is not clear. In the present study several oxidative stress markers and enzymes involved in OS have been determined. In particular, we examined the levels of 4-hydroxy-2-nonenal protein adducts (HNE-PA), a by-product of lipid peroxidation, and the activation of NADPH oxidase 2 (NOX2), as cellular source of superoxide (O(2)(-)), in surgically resected epileptic tissue from drug-resistant patients (N=50). In addition, we investigated whether oxidative-mediated protein damage can affect aquaporin-4 (AQP4), a water channel implicated in brain excitability and epilepsy. Results showed high levels of HNE-PA in epileptic hippocampus, in both neurons and glial cells and cytoplasmic positivity for p47(phox) and p67(phox) suggesting NOX2 activation. Interestingly, in epileptic tissue immunohistochemical localization of AQP4 was identified not only in perivascular astrocytic endfeet, but also in neurons. Nevertheless, negativity for AQP4 was observed in neurons in degeneration. Of note, HNE-mediated post-translational modifications of AQP4 were increased in epileptic tissues and double immunofluorescence clearly demonstrated co-localization of AQP4 and HNE-PA in epileptic hippocampal structures. The idea is that sudden, disorderly, and excessive neuronal discharges activates NOX2 with O(2)(-) production, leading to lipid peroxidation. The resulting generation of HNE targets AQP4, affecting water and ion balance. Therefore, we suggest that seizure induces oxidative damage as well as neuronal loss, thereby promoting neuronal hyperexcitability, also affecting water and ion balance by AQP4 modulation, and thus generating a vicious cycle.
authors.affiliation: Department of Molecular and Developmental Medicine, University of Siena, Via A. Moro 2, 53100 Siena, Italy; Child Neuropsychiatry Unit, University Hospital, Azienda Ospedaliera Universitaria Senese (AOUS), Viale M. Bracci 16, 53100 Siena, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Pecorelli
authors.affiliation: Department of Medicine, Surgery and Neuroscience, University of Siena, Viale M. Bracci 16, 53100 Siena, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Natrella
authors.affiliation: Department of Medicine, Surgery and Neuroscience, University of Siena, Viale M. Bracci 16, 53100 Siena, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Belmonte
authors.affiliation: Department of Medicine, Surgery and Neuroscience, University of Siena, Viale M. Bracci 16, 53100 Siena, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Miracco
authors.affiliation: Department of Life Science and Biotechnologies, University of Ferrara, Via L. Borsari 46, 44121 Ferrara, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Cervellati
authors.affiliation: Department of Molecular and Developmental Medicine, University of Siena, Via A. Moro 2, 53100 Siena, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Ciccoli
authors.affiliation: Department of Medicine, Surgery and Neuroscience, University of Siena, Viale M. Bracci 16, 53100 Siena, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Mariottini
authors.affiliation: Department of Medicine, Surgery and Neuroscience, University of Siena, Viale M. Bracci 16, 53100 Siena, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Rocchi
authors.affiliation: Department of Medicine, Surgery and Neuroscience, University of Siena, Viale M. Bracci 16, 53100 Siena, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Vatti
authors.affiliation: Department of Medicine, Surgery and Neuroscience, University of Siena, Viale M. Bracci 16, 53100 Siena, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Bua
authors.affiliation: Child Neuropsychiatry Unit, University Hospital, Azienda Ospedaliera Universitaria Senese (AOUS), Viale M. Bracci 16, 53100 Siena, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Canitano
authors.affiliation: Child Neuropsychiatry Unit, University Hospital, Azienda Ospedaliera Universitaria Senese (AOUS), Viale M. Bracci 16, 53100 Siena, Italy.
authors.forename: J
authors.initials: J
authors.lastname: Hayek
authors.affiliation: Life and Environmental Sciences Unit, University of California, 5200 North Lake Road, Merced, CA 95344, USA; Andrus Gerontology Center of the Davis School of Gerontology, University of Southern, 3715 McClintock Ave., Los Angeles, CA 90089-0191, USA.
authors.forename: H J
authors.initials: HJ
authors.lastname: Forman
authors.affiliation: Department of Life Science and Biotechnologies, University of Ferrara, Via L. Borsari 46, 44121 Ferrara, Italy. Electronic address: giuseppe.valacchi@unife.it.
authors.forename: G
authors.initials: G
authors.lastname: Valacchi
mesh_terms: D000293:Adolescent; D000328:Adult; D000447:Aldehydes / Q000378:metabolism*; D051401:Aquaporin 4 / Q000378:metabolism*; D001253:Astrocytes / Q000378:metabolism / Q000473:pathology; D002675:Child, Preschool; D004351:Drug Resistance; D004789:Enzyme Activation; D004827:Epilepsy / Q000401:mortality* / Q000473:pathology; D005260:Female; D006624:Hippocampus / Q000378:metabolism / Q000473:pathology; D006801:Humans; D015227:Lipid Peroxidation; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism*; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000378:metabolism*; D019636:Neurodegenerative Diseases / Q000378:metabolism* / Q000473:pathology; D009474:Neurons / Q000378:metabolism / Q000473:pathology; D013481:Superoxides / Q000378:metabolism; D014882:Water-Electrolyte Balance
chemical_list: C496030:AQP4 protein, human; D000447:Aldehydes; D051401:Aquaporin 4; D008562:Membrane Glycoproteins; D013481:Superoxides; C056558:CYBB protein, human; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; C027576:4-hydroxy-2-nonenal
keywords: 4-Hydroxy-2-nonenal; Aquaporin-4; Drug-resistant epilepsy; Matrix metalloproteinase; NADPH oxidase