Reactive Oxygen Species from Human Astrocytes Induced Functional Impairment and Oxidative Damage

Abstract

Reactive oxygen species (ROS) have been shown to be a contributor to aging and disease. ROS also serve as a trigger switch for signaling cascades leading to corresponding cellular and molecular events. In the central nervous system, microglial cells are likely the main source of ROS production. However, activated astrocytes also appear to be capable of generating ROS. In this study we investigated ROS production in human astrocytes stimulated with interleukin (IL)-1β and interferon (IFN)-γ and its potential harmful effects. Although IFN-γ alone had no effect, it potentiated IL-1β-induced ROS production in a time-dependent manner. One of the sources of ROS in IL-1β-activated astrocytes was from increased superoxide production in mitochondria accompanied by enhanced manganese superoxide dismutase and inhibited catalase expression. NADPH oxidase (NOX) may also contribute to ROS production as astrocytes express NOX isoforms. Glutamate uptake, which represents one of the most important methods of astrocytes to prevent excitotoxity, was down-regulated in IL-1β-activated astrocytes, and was further suppressed in the presence of IFN-γ; IFN-γ itself exerted minimal effect. Elevated levels of 8-isoprostane in IL-1β ± IFN-γ-activated human astrocytes indicate downstream lipid peroxidation. Pretreatment with DPI (diphenyleneiodonium) abolished the IL-1β ± IFN-γ-induced ROS production, restored glutamate uptake function and reduced 8-isoprostane to near control levels suggesting that ROS contributes to the dysfunction of activated astrocytes. These results support the notion that dampening activated human astrocytes to maintain the redox homeostasis is vital to preserve their neuroprotective potential in the CNS.

The Essential Oils of Rhaponticum carthamoides Hairy Roots and Roots of Soil‐Grown Plants: Chemical Composition and Antimicrobial, Anti‐Inflammatory, and Antioxidant Activities

“…ROS production is activated by the NADPH oxidase (NOX) [38] and by cyclooxygenase-2 (COX-2) as a side-product in the synthesis of prostanoids [35]. It is known from literature that ROS can activate various signaling molecules such as protein kinase C, MAPK, and NF- κ B which play an important role in regulating the gene expression of various proinflammatory factors [39].…”

Effects of fumarates on inflammatory human astrocyte responses and oligodendrocyte differentiation

“…Following pretreatment, cells were loaded with 10 μ mol/L Carboxy‐H 2 DCFDA (Molecular Probes), a cell permeable dye that becomes fluorescent after cleavage to dichloroflourescin (DCF) by reactive oxygen species (ROS). Following a 1 h incubation with dye, cells were cultured in the Cytation5 ® live cell imager/plate reader (BioTek) in the presence of IL‐1 β (10 ng/mL) and IFN γ (10 ng/mL) to promote inflammatory ROS production 27. Fluorescence intensity was read hourly over a 24‐h period.…”

Principles of inflammasome priming and inhibition: Implications for psychiatric disorders

“…In murine models, IL-1β facilitated the endocytosis of astrocytic glutamate transporters and decreased the reuptake of synaptic glutamate (Hu et al, 2000). The ensuing excitotoxicity caused by extracellular glutamate resulted in the production of mitochondrial ROS and neuronal atrophy (Sheng et al, 2013). IL-1β may also promote hyper excitability by phosphorylating post-synaptic GABA A receptors and decreasing their affinity for intracellular GABA (Yu and Shinnick-Gallagher, 1994).…”