title: Interleukin-18 alters protein expressions of neurodegenerative diseases-linked proteins in human SH-SY5Y neuron-like cells.
abstract: Chronic inflammation and oxidative stress (OS) are present in Alzheimer's disease (AD) brains in addition to neuronal loss, Amyloid-β (Aβ) plaques and hyperphosphorylated tau-protein neurofibrillary tangles (NFTs). Previously we showed that levels of the pro-inflammatory cytokine, interleukin-18 (IL-18), are elevated in post-mortem AD brains. IL-18 can modulate the tau kinases, Cdk5 and GSK3β, as well as Aβ-production. IL-18 levels are also increased in AD risk diseases, including type-2 diabetes and obesity. Here, we explored other IL-18 regulated proteins in neuron-like SH-SY5Y cells. Differentiated SH-SY5Y cells, incubated with IL-18 for 24, 48, or 72 h, were analyzed by two-dimensional gel electrophoresis (2D-DIGE). Specific altered protein spots were chosen and identified with mass spectrometry (MS) and verified by western immunoblotting (WIB). IL-18 had time-dependent effects on the SH-SY5Y proteome, modulating numerous protein levels/modifications. We concentrated on those related to OS (DDAH2, peroxiredoxins 2, 3, and 6, DJ-1, BLVRA), Aβ-degradation (MMP14, TIMP2), Aβ-aggregation (Septin-2), and modifications of axon growth and guidance associated, collapsin response mediator protein 2 (CRMP2). IL-18 significantly increased antioxidative enzymes, indicative of OS, and altered levels of glycolytic α- and γ-enolase and multifunctional 14-3-3γ and -ε, commonly affected in neurodegenerative diseases. MMP14, TIMP2, α-enolase and 14-3-3ε, indirectly involved in Aβ metabolism, as well as Septin-2 showed changes that increase Aβ levels. Increased 14-3-3γ may contribute to GSK3β driven tau hyperphosphorylation and CRMP2 Thr514 and Ser522 phosphorylation with the Thr555-site, a target for Rho kinase, showing time-dependent changes. IL-18 also increased caspase-1 levels and vacuolization of the cells. Although our SH-SY5Y cells were not aged, as neurons in AD, our work suggests that heightened or prolonged IL-18 levels can drive protein changes of known relevance to AD pathogenesis.
authors.affiliation: Department of Neurology, Institute of Clinical Medicine, University of Eastern Finland Kuopio, Finland ; Brain Research Unit, Clinical Research Centre, University of Eastern Finland Kuopio, Finland.
authors.forename: Elina M
authors.initials: EM
authors.lastname: Sutinen
authors.affiliation: Institute of Biotechnology, University of Helsinki Helsinki, Finland.
authors.forename: Minna A
authors.initials: MA
authors.lastname: Korolainen
authors.affiliation: School of Medicine, Institute of Biomedicine, University of Eastern Finland Kuopio, Finland.
authors.forename: Jukka
authors.initials: J
authors.lastname: Häyrinen
authors.affiliation: Rudbecklaboratoriet, Department of Immunology, Genetics and Pathology, Molecular and Morphological Pathology, Uppsala University Uppsala, Sweden.
authors.forename: Irina
authors.initials: I
authors.lastname: Alafuzoff
authors.affiliation: Regenerative Neuroscience and Development Laboratory, Department of Medicine, Central Clinical School, Monash University Prahran, VIC, Australia.
authors.forename: Steven
authors.initials: S
authors.lastname: Petratos
authors.affiliation: Department of Neurology, Institute of Clinical Medicine, University of Eastern Finland Kuopio, Finland ; Department of Neurology, Kuopio University Hospital Kuopio, Finland.
authors.forename: Antero
authors.initials: A
authors.lastname: Salminen
authors.affiliation: Department of Neurology, Institute of Clinical Medicine, University of Eastern Finland Kuopio, Finland ; Brain Research Unit, Clinical Research Centre, University of Eastern Finland Kuopio, Finland ; Department of Neurology, Kuopio University Hospital Kuopio, Finland.
authors.forename: Hilkka
authors.initials: H
authors.lastname: Soininen
authors.affiliation: Department of Neurology, Institute of Clinical Medicine, University of Eastern Finland Kuopio, Finland ; Brain Research Unit, Clinical Research Centre, University of Eastern Finland Kuopio, Finland ; Department of Neurology, Kuopio University Hospital Kuopio, Finland.
authors.forename: Tuula
authors.initials: T
authors.lastname: Pirttilä
authors.affiliation: Department of Neurology, Institute of Clinical Medicine, University of Eastern Finland Kuopio, Finland ; Brain Research Unit, Clinical Research Centre, University of Eastern Finland Kuopio, Finland.
authors.forename: Johanna O
authors.initials: JO
authors.lastname: Ojala
keywords: CRMP2; DDAH; Interleukin-18; MMP14; inflammation; neurodegenerative diseases; oxidative stress related proteins; proteomics