Redox pioneer: professor Irwin Fridovich

Clinical and Molecular-Genetic Insights into the Role of Oxidative Stress in Diabetic Retinopathy: Antioxidant Strategies and Future Avenues

Reactive oxygen species (ROS) overproduction and ROS-signaling pathways activation attack the eyes. We evaluated the oxidative stress (OS) and the effects of a daily, core nutritional supplement regimen containing antioxidants and omega 3 fatty acids (A/ω3) in type 2 diabetics (T2DM). A case-control study was carried out in 480 participants [287 T2DM patients with (+)/without (-) diabetic retinopathy (DR) and 193 healthy controls (CG)], randomly assigned to a daily pill of A/ω3. Periodic evaluation through 38 months allowed to outline patient characteristics, DR features, and classic/OS blood parameters. Statistics were performed by the SPSS 24.0 program. Diabetics displayed significantly higher circulating pro-oxidants (p = 0.001) and lower antioxidants (p = 0.0001) than the controls. Significantly higher plasma malondialdehyde/thiobarbituric acid reactive substances (MDA/TBARS; p = 0.006) and lower plasma total antioxidant capacity (TAC; p = 0.042) and vitamin C (0.020) was found in T2DM + DR versus T2DM-DR. The differential expression profile of solute carrier family 23 member 2 (SLC23A2) gene was seen in diabetics versus the CG (p = 0.001), and in T2DM + DR versus T2DM - DR (p < 0.05). The A/ω3 regime significantly reduced the pro-oxidants (p < 0.05) and augmented the antioxidants (p < 0.05). This follow-up study supports that a regular A/ω3 supplementation reduces the oxidative load and may serve as a dietary prophylaxis/adjunctive intervention for patients at risk of diabetic blindness.

Mitochondria-Accessing Ratiometric Fluorescent Probe for Imaging Endogenous Superoxide Anion in Live Cells and Daphnia magna

Superoxide anion (O₂^•-), as the precursor of other reactive oxygen species (ROS), is significantly important in the maintenance of redox homeostasis and various cellular signaling pathways. Here we present a ratiometric mitochondria-accessing fluorescent probe (NA-T) based on nucleophilic substitution mechanism for real-time measuring O₂^•-. By regulating the intramolecular charge of 1,8-naphthalimide, a ratiometric response model was obtained, which evinced 18-fold enhancement of fluorescence ratio ( I_540 nm/ I_475 nm) in the presence of O₂^•- over other ROS with rapid response (132 s), high sensitivity (DL = 0.370 μM) and selectivity. Confocal fluorescence images demonstrated that the probe could well permeate through plasma membrane for visualizing endogenous O₂^•- changes in mitochondria of living cells and in inflammatory Daphnia magna, indicating NA-T a potential tool for the diagnosis and research of corresponding diseases.

ROS Generation in Peroxisomes and its Role in Cell Signaling

In plant cells, as in most eukaryotic organisms, peroxisomes are probably the major sites of intracellular H₂O₂ production, as a result of their essentially oxidative type of metabolism. In recent years, it has become increasingly clear that peroxisomes carry out essential functions in eukaryotic cells. The generation of the important messenger molecule hydrogen peroxide (H₂O₂) by animal and plant peroxisomes and the presence of catalase in these organelles has been known for many years, but the generation of superoxide radicals (O₂^·- ) and the occurrence of the metalloenzyme superoxide dismutase was reported for the first time in peroxisomes from plant origin. Further research showed the presence in plant peroxisomes of a complex battery of antioxidant systems apart from catalase. The evidence available of reactive oxygen species (ROS) production in peroxisomes is presented, and the different antioxidant systems characterized in these organelles and their possible functions are described. Peroxisomes appear to have a ROS-mediated role in abiotic stress situations induced by the heavy metal cadmium (Cd) and the xenobiotic 2,4-D, and also in the oxidative reactions of leaf senescence. The toxicity of Cd and 2,4-D has an effect on the ROS metabolism and speed of movement (dynamics) of peroxisomes. The regulation of ROS production in peroxisomes can take place by post-translational modifications of those proteins involved in their production and/or scavenging. In recent years, different studies have been carried out on the proteome of ROS metabolism in peroxisomes. Diverse evidence obtained indicates that peroxisomes are an important cellular source of different signaling molecules, including ROS, involved in distinct processes of high physiological importance, and might play an important role in the maintenance of cellular redox homeostasis.

The role of reactive oxygen species and nitric oxide in programmed cell death associated with self-incompatibility

Successful sexual reproduction often relies on the ability of plants to recognize self- or genetically-related pollen and prevent pollen tube growth soon after germination in order to avoid self-fertilization. Angiosperms have developed different reproductive barriers, one of the most extended being self-incompatibility (SI). With SI, pistils are able to reject self or genetically-related pollen thus promoting genetic variability. There are basically two distinct systems of SI: gametophytic (GSI) and sporophytic (SSI) based on their different molecular and genetic control mechanisms. In both types of SI, programmed cell death (PCD) has been found to play an important role in the rejection of self-incompatible pollen. Although reactive oxygen species (ROS) were initially recognized as toxic metabolic products, in recent years, a new role for ROS has become apparent: the control and regulation of biological processes such as growth, development, response to biotic and abiotic environmental stimuli, and PCD. Together with ROS, nitric oxide (NO) has become recognized as a key regulator of PCD. PCD is an important mechanism for the controlled elimination of targeted cells in both animals and plants. The major focus of this review is to discuss how ROS and NO control male-female cross-talk during fertilization in order to trigger PCD in self-incompatible pollen, providing a highly effective way to prevent self-fertilization.

Oxidative stress in apoptosis and cancer: an update

The oxygen paradox tells us that oxygen is both necessary for aerobic life and toxic to all life forms. Reactive oxygen species (ROS) touch every biological and medical discipline, especially those involving proliferative status, supporting the idea that active oxygen may be increased in tumor cells. In fact, metabolism of oxygen and the resulting toxic byproducts can cause cancer and death. Efforts to counteract the damage caused by ROS are gaining acceptance as a basis for novel therapeutic approaches, and the field of prevention of cancer is experiencing an upsurge of interest in medically useful antioxidants. Apoptosis is an important means of regulating cell numbers in the developing cell system, but it is so important that it must be controlled. Normal cell death in homeostasis of multicellular organisms is mediated through tightly regulated apoptotic pathways that involve oxidative stress regulation. Defective signaling through these pathways can contribute to both unbalance in apoptosis and development of cancer. Finally, in this review, we discuss new knowledge about recent tools that provide powerful antioxidant strategies, and designing methods to deliver to target cells, in the prevention and treatment of cancer.