Mitochondrial dysfunction and loss of glutamate uptake in primary astrocytes exposed to titanium dioxide nanoparticles

Abstract

Titanium Dioxide (TiO2) nanoparticles is currently the second most produced engineered nanomaterial in the world with vast usage in consumer products leading to recurrent human exposure. Animal studies indicate significant nanoparticle accumulation in the brain while cellular toxicity studies demonstrate negative effects on neuronal cell viability and function. However, the toxicological effects of nanoparticles on astrocytes, the most abundant cells in the brain, have not been extensively investigated. Therefore, we determined the sub-toxic effect of three different TiO2 nanoparticles (rutile, anatase and commercially available P25 TiO2 nanoparticles) on primary rat cortical astrocytes. We evaluated some events related to astrocyte functions and mitochondrial dysregulation: (1) glutamate uptake; (2) redox signaling mechanisms by measuring ROS production; (3) the expression patterns of dynamin-related proteins (DRPs) and mitofusins 1 and 2, whose expression is central to mitochondrial dynamics; and (4) mitochondrial morphology by MitoTrackerR Red CMXRos staining. Anatase, rutile and P25 were found to have LC50 values of 88.22 ± 10.56 ppm, 136.0 ± 31.73 ppm and 62.37 ± 9.06 ppm respectively indicating nanoparticle specific toxicity. All three TiO2 nanoparticles induced a significant loss in glutamate uptake indicative of loss in vital astrocyte function. TiO2 nanoparticles also induced increase in reactive oxygen species generation, and decrease in mitochondrial membrane potential, suggesting mitochondria damage. TiO2 nanoparticle exposure altered expression patterns of DRPs at low concentrations (25 ppm) and apoptotic fission at high concentrations (100 ppm). TiO2 nanoparticles exposure also resulted in changes to mitochondrial morphology confirmed by mitochondrial staining. Collectively, our data provide compelling evidence that TiO2 nanoparticles exposure has potential implications in astrocytes-mediated neurological dysfunction.

Hyaluronic acid-conjugated liposome nanoparticles for targeted delivery to CD44 overexpressing glioblastoma cells

“…Primary cortical (Cort) and cerebellum (Cereb) astrocytes were prepared from 1–2 day-old Charles River (Wilmington, MA, USA) Sprague-Dawley rat pups from four donor rats yielding 12+ pups per litter in compliance with UNL's IACUC protocol 1046 as described previously [74]. Briefly, the Cort and Cereb brain regions were isolated, digested with trypsin and DNase, filtered through a 70 micron filter, centrifuged, and suspended in complete culture media prior to seeding.…”

“…To determine the effect of free DOX and HALNP-DOX on the cell viability of Cort Astro, MG and A172 cells, we utilized an MTT assay as previously reported to calculate the lethal concentration to kill 50% of the cells [57, 74, 75]. Following the 24 hour DOX incubation time, the medium of the cells was aspirated, and sterile 5 mg/ml MTT working solution was added and incubated for 2 hours at 37°C.…”

α‐synuclein oligomers enhance astrocyte‐induced synapse formation through TGF‐β1 signaling in a Parkinson's disease model

“…More recently, neurons and astrocytes have been shown to internalize αSO in vitro , which results in decreased mitochondrial function, cell degeneration and cell death (Wilson et al . ). Additionally, α‐Syn has been shown to be transferred from astrocytes to neurons and to induce inflammatory responses (Lee et al .…”

Nec-1 Attenuates Neurotoxicity Induced by Titanium Dioxide Nanomaterials on Sh-Sy5y Cells Through RIP1

“…Furthermore, the associations of RIP3/MLKL with the neurotoxicity of TNPs should also be evaluated. Thirdly, reactive oxygen species (ROS), as the main mechanisms underlying neurotoxicity of TNPs [35,36], were reported to be the upstream signal of RIP1 [37]. Therefore, whether ROS are the upstream of RIP1 in the neurotoxicity of TNPs should be discussed further.…”