Non-toxic engineered carbon nanodiamond concentrations induce oxidative/nitrosative stress, imbalance of energy metabolism, and mitochondrial dysfunction in microglial and alveolar basal epithelial cells

Abstract

Engineered nanoparticles are finding a wide spectrum of biomedical applications, including drug delivery and capacity to trigger cytotoxic phenomena, potentially useful against tumor cells. The full understanding of their biosafety and interactions with cell processes is mandatory. Using microglial (BV-2) and alveolar basal epithelial (A549) cells, in this study we determined the effects of engineered carbon nanodiamonds (ECNs) on cell viability, nitric oxide (NO) and reactive oxygen species (ROS) production, as well as on energy metabolism. Particularly, we initially measured decrease in cell viability as a function of increasing ECNs doses, finding similar cytotoxic ECN effects in the two cell lines. Subsequently, using apparently non-cytotoxic ECN concentrations (2 µg/mL causing decrease in cell number < 5%) we determined NO and ROS production, and measured the concentrations of compounds related to energy metabolism, mitochondrial functions, oxido-reductive reactions, and antioxidant defences. We found that in both cell lines non-cytotoxic ECN concentrations increased NO and ROS production with sustained oxidative/nitrosative stress, and caused energy metabolism imbalance (decrease in high energy phosphates and nicotinic coenzymes) and mitochondrial malfunctioning (decrease in ATP/ADP ratio).These results underline the importance to deeply investigate the molecular and biochemical changes occurring upon the interaction of ECNs (and nanoparticles in general) with living cells, even at apparently non-toxic concentration. Since the use of ECNs in biomedical field is attracting increasing attention the complete evaluation of their biosafety, toxicity and/or possible side effects both in vitro and in vivo is mandatory before these highly promising tools might find the correct application.

Modulation of Pro-Oxidant and Pro-Inflammatory Activities of M1 Macrophages by the Natural Dipeptide Carnosine

“…On the other hand, carnosine effects on Nrf2 might have led stimulated macrophages to have lower expressions of Nox-2 and Cox-2 and concomitant higher expressions in canonical scavenger enzymes (Gpx, Cat, and SOD-2; Figure 5). All the above-mentioned results, showing an antioxidant activity of carnosine on activated macrophages, are in accordance with other studies in which the presence of this dipeptide protected brain macrophages and/or endothelial cells against cell death oxidative stress-induced [63,64].…”

Antioxidant Therapies in Traumatic Brain Injury

“…For example, although increased NO synthesis occurs early after TBI, the amount generated by nNOS and eNOS [33,34] has a crucial role as a vasodilator in maintaining cerebral blood flow [35]. In contrast, NO formed intracellularly in cerebral cells by iNOS is deeply involved in the generation of reactive nitrogen species (RNS) and in the so-called nitrosative stress response [36]. The temporal coincidence of excess ROS and RNS production gives rise to the concomitant insurgence of oxidative/nitrosative stress [37].…”

Dynamic Modelling of Interactions between Microglia and Endogenous Neural Stem Cells in the Brain during a Stroke

“…In living systems, free radicals and oxidants have double functions as both toxic and beneficial complex since they can be either harmful or beneficial to the body [11][12][13]. The activation of microglia has both beneficial and deleterious effects.…”

“…The positive effects manifest through the prevention of damage extension by phagocytosis and the production of trophic molecules and anti-inflammatory cytokines, which can be conducive to tissue repair as well as neuroprotection. The harmful effects, which are toxic to tissues, occur primarily through the production of free radicals [12,13]. This reaction is important in removing damaged cells from the brain tissue; however, it can also increase the harm to brain cells by producing free radicals that are toxic to healthy cells [2,14,15].…”