Partial Mitigation of Oxidized Phospholipid-Mediated Mitochondrial Dysfunction in Neuronal Cells by Oxocarotenoids

Abstract

Mitochondria are important (patho)physiological sources of reactive oxygen species (ROS) that mediate mitochondrial dysfunction and phospholipid oxidation; an increase in mitochondrial content of oxidised phospholipid (OxPL) associates with cell death. Previously we showed that the circulating OxPL 1-palmitoyl-2-(5'-oxo-valeroyl)-sn-glycero-3phosphocholine (POVPC) increases in patients with Alzheimer's disease (AD), and associates with lower plasma antioxidant oxocarotenoids, zeaxanthin and lutein. Since oxocarotenoids are metabolised in mitochondria, we propose that during AD, lower concentrations of mitochondrial zeaxanthin and lutein may result in greater phospholipid oxidation and predispose to neurodegeneration. Here, we have investigated whether non-toxic POVPC concentrations impair mitochondrial metabolism in differentiated (d)SH-SY5Y neuronal cells and whether there is any protective role for oxocarotenoids against mitochondrial dysfunction. After 24 hours, glutathione (GSH) concentration was lower in neuronal cells exposed to POVPC (1-20µM) compared with vehicle control without loss of viability compared to control. However, mitochondrial ROS production (determined by MitoSOX oxidation) was increased by 50% only after 20µM POVPC. Following delivery of lutein (0.1-1µM) and zeaxanthin (0.5-5µM) over 24 hours in vitro, oxocarotenoid recovery from dSH-SY5Y cells was >50%. Coincubation with oxocarotenoids prevented loss of GSH after 1µM but not 20µM POVPC, whereas the increase in ROS production induced by 20µM POVPC was prevented by lutein and zeaxanthin. Mitochondrial uncoupling increases and ATP production is inhibited by 20µM but not 1 µM POVPC; carotenoids protected against uncoupling although did not restore ATP production. In summary, 20µM POVPC induced loss of GSH and a mitochondrial bioenergetic deficit in neuronal cells that was not mitigated by oxocarotenoids.

Sodium Thiosulphate-Loaded Liposomes Control Hydrogen Sulphide Release and Retain Its Biological Properties in Hypoxia-like Environment

“…Following, to evaluate mitochondrial and glycolytic function, a set of drugs/inhibitors: oligomycin (O) (1 mM) (Sigma-Aldrich, Dorset, UK), carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP) (0.5 mM) (Sigma-Aldrich, Dorset, UK), 2 deoxy glucose (2-DG) (Sigma-Aldrich, Dorset, UK) and a mixture of rotenone and antimycin A (Rot/AntA) (1 mM) (Cayman Chemicals, Michigan, USA) were injected sequentially, using available ports to: inhibit the ATP synthase, uncouple oxidative phosphorylation, inhibit glycolysis and estimate non-mitochondrial respiration, respectively. From OCR readings, this experiment measures six parameters of the mitochondrial function: basal oxygen consumption, ATP-linked oxygen consumption, proton leak, maximal oxygen consumption, reserve capacity, and non-mitochondrial oxygen consumption as we have previously optimised [ 37 , 38 , 39 ] ( Supplementary Figure S1A ). From ECAR readings, the experiment allowed to calculate three glycolysis related parameters: basal glycolysis, glycolytic capacity and glycolytic dependence ( Supplementary Figure S1B ).…”

Oxidized phospholipid POVPC contributes to vascular calcification by triggering ferroptosis of vascular smooth muscle cells

“…Accumulated evidence suggests that oxidative stress plays a crucial part in the pathological process of vascular calcification, 31,32 and POVPC activates oxidative stress. 33 To determine whether oxidative stress participates in the progression of POVPC-induced vascular calcification, we treated RVSMCs with POVPC in the presence of CM and examined cytosolic ROS levels. As reported in our previous study, CM treatment significantly increased the cytosolic ROS levels of VSMCs.…”

Merging the Multi-Target Effects of Phytochemicals in Neurodegeneration: From Oxidative Stress to Protein Aggregation and Inflammation

“…In the last decades, the search for an effective and potentially safe strategy to combat oxidative stress-mediated neuronal damage has increasingly prompted the investigation of naturally occurring compounds as antioxidant agents. The attenuation of oxidative stress by bioactive compounds belonging to different classes of phytochemicals including (i) flavonoids (quercetin, kaempferol and myricetin, scutellarin, baicalin, apigenin, catechins, epigallocatechin, and genistein) [ 52 , 61 , 81 , 82 , 83 , 88 , 94 , 130 , 131 , 132 , 133 , 134 , 135 , 136 , 137 ]; (ii) phenolic acids (syringic, gallic, caffeic, chlorogenic and salvianolic acids, and curcumin) [ 70 , 103 , 104 , 105 , 138 , 139 , 140 , 141 , 142 , 143 ]; (iii) flavonolignans (silymarin) [ 96 ]; (iv) stilbenes (resveratrol) [ 59 , 65 , 97 , 98 , 144 ]; (v) terpenes (bacosides/bacopasides, withanolides, and the carotenoids lutein and zeaxanthin) [ 7 , 110 , 113 , 115 , 145 , 146 , 147 ]; (vi) alkaloids (berberine and caffeine) [ 148 , 149 ]; (vii) glucosinolates (sulforaphane) and polyamines (spermine/spermidine) [ 123 , 124 ,…”

“…In line with this, neuroprotective, antioxidant, and anti-apoptotic effects of most phytochemicals go along with mitochondrial protection. The latter is associated with preserved mitochondrial membrane potential and ATP production, reduced mitochondrial fragmentation, increased SOD activity, reduction of ROS and ROS-induced damage, up-regulation of Bcl-2, as well as down-regulation of Bax, p53, and caspase-3 [ 52 , 82 , 83 , 137 , 144 , 145 , 147 , 172 ]. The beneficial effects of phytochemicals against mitochondrial damage in models of neurodegeneration/neurotoxicity are also evident at the ultrastructural level, whereby a reduction in mitochondrial swelling, loss of cristae, and chromatin condensation are observed [ 83 ].…”