Cellular and Molecular Mechanisms in Oxidative Stress-Related Diseases 2.0/3.0

Oxidative stress is frequently described as the balance between the production of reactive species (including oxygen and nitrogen) in biological systems and the ability of the latter to defend itself through the sophisticated antioxidant machinery. At physiological levels, some oxidants, in controlled amounts, possess important signaling functions within the cell [1,2]. Specifically, cells can generate reactive species with the function of second messengers, using them for intracellular signaling and for stimulating the redox-sensitive signaling pathways to modify the cellular content of the cytoprotective regulatory proteins [3]. In fact, the redox state of the cell is normally regulated by a complex endogenous antioxidant system, composed of proteins with enzymatic activity and non-enzymatic proteins able to quickly neutralize, or ensure a low production of, reactive species [4]. Nevertheless, when oxidants are produced in excess, or when the antioxidant defenses that regulate them are ineffective, this balance can be perturbed, thus resulting in an oxidative condition. Oxidative products are highly reactive, and can directly or indirectly modulate the functions of many enzymes and transcription factors through complex signaling cascades. In particular, some of the pathways are preferentially linked to enhanced survival, while others are more frequently associated with cell death, and constitute important avenues for therapeutic interventions aimed at limiting oxidative damage or, alternatively, attenuating its consequences [5,6,7,8,9,10,11]. Furthermore, the magnitude and exposure of the insult, as well as the cell type involved, are key elements in defining which pathways are activated, as well as the final cell outcome. This Special Issue has been conceived to collect and contribute to the dissemination of novel findings unraveling the impact of oxidative stress on cells, their subcellular components, and biological macromolecules. Here, we offer an overview of the content of this Special Issue, which collects 13 original articles and seven reviews.