Association of Peripheral Markers of Oxidative Stress with Clinical Parameters and Inflammatory Factors in Alcoholic Patients

One of the fundamental problems in studying addiction is elucidation of mechanisms of alcohol dependence (AD) development. Disturbances of cellular redox balance and inflammation play an important role in AD pathogenesis. Deciphering associations between biological and clinical indicators can elucidate molecular mechanisms of disease pathogenesis. The aim of the work was to study peripheral markers of oxidative stress in patients with AD during early abstinence period and to identify their relationship with clinical parameters of the disease and inflammatory factors. In total, 84 patients with AD were studied (average age, 44.3 ± 8.2 years). The analyzed clinical parameters included patient's age, age of alcohol withdrawal syndrome (AWS) formation, disease duration, and AWS duration. The markers of oxidative stress determined in the blood plasma were oxidation products of proteins (protein carbonyls, PCs), lipids (thiobarbituric acid-reactive products, TBA-RPs), and DNA (8-hydroxy-2'-deoxyguanosine, 8-OH-dG). The content of inflammatory mediators, such as proinflammatory cytokines (IFNγ, IL-1β, IL-6, IL-8, IL-17A, TNFα) was determined in the blood serum. Blood samples of 80 conditionally healthy men (average age, 40.9 ± 9.6 years) were used as a control. Patients with AD demonstrated an increase in the content of PCs, TBA-RPs, and all analyzed cytokines (but not 8-OH-dG) compared to the control individuals. There was a direct correlation between the TBA-RP content and disease duration and inverse correlation of the PC content with the age of AWS formation and AWS duration. The content of PCs demonstrated an inverse correlation with the IL-6 concentration in the blood plasma. We also observed a positive correlation between 8-OH-dG and IL-6, TBA-RPs and IL-8, and TBA-RPs and TNFα. Therefore, the early abstinence period in patients with AD was characterized by a pronounced oxidative stress and inflammation. The obtained results expand the knowledge on the integrative contribution of oxidative stress and inflammatory factors to the AD pathogenesis and can be used in the development of new therapies.

Folic Acid Rescues Dopaminergic Neurons in MPTP-Induced Mice by Inhibiting the NLRP3 Inflammasome and Ameliorating Mitochondrial Impairment

Parkinson's disease (PD) is marked by the degeneration of dopaminergic neurons of the substantia nigra (SN), with neuroinflammation and mitochondrial dysfunction being key contributors. The neuroprotective potential of folic acid (FA) in the dopaminergic system of PD was assessed in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model. MPTP (20 mg/kg of body weight) was administered to C57BL/6J mice to simulate PD symptoms followed by FA treatment (5 mg/kg of body weight). Behavioral tests, pole, rotarod, and open-field tests, evaluated motor function, while immunohistochemistry, ELISA, RT-qPCR, and Western blotting quantified neuroinflammation, oxidative stress markers, and mitochondrial function. FA supplementation considerably improved motor performance, reduced homocysteine levels and mitigated oxidative damage in the SN. The FA-attenuated activation of the NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome lessened glial cell activity and reduced neuroinflammation. At the molecular level, FA reduced DNA damage, downregulated phosphorylated p53, and induced the expression of peroxisome proliferator-activated receptor α coactivator 1α (PGC-1α), enhancing mitochondrial function. Therefore, FA exerts neuroprotection in MPTP-induced PD by inhibiting neuroinflammation via NLRP3 inflammasome suppression and promoting mitochondrial integrity through the p53-PGC-1α pathway. Notable limitations of our study include its reliance on a single animal model and the incompletely elucidated mechanisms underlying the impact of FA on mitochondrial dynamics. Future investigations will explore the clinical utility of FA and its molecular mechanisms, further advancing it as a potential therapeutic for managing and delaying the progression of PD.

Addition of oh8dG to Cardioplegia Attenuated Myocardial Oxidative Injury through the Inhibition of Sodium Bicarbonate Cotransporter Activity

The biomarker 8-hydroxy-2′-deoxyguanosine (oh8dG) is derived from oxidized nucleic acids or products of oxidant-mediated DNA damage. Enhanced sodium bicarbonate cotransporter (NBC) activity is caused by reactive oxygen species (ROS) production in ventricular myocytes. Thus, we hypothesized that cardioplegia-solution-mediated ROS generation may be involved in the regulation of NBC activity in cardiomyocytes and that oh8dG treatment may modulate ROS and associated NBC activity. Langendorff-free cardioplegia-arrested cardiac strips and cardiomyocytes were isolated to determine the NBC activity and effects of oh8dG on oxidative-stress-mediated cardiac damage markers. We first determined the histidine-tryptophan-ketoglutarate (HTK) solution mediated NBC activity in cardiac strips and cells. The oh8dG treatment attenuated NBC activity in the electroneutral or electrogenic form of NBC. Additionally, exposure to HTK solution induced ROS, whereas co-administration of oh8dG attenuated ROS-mediated NBC activity, reduced ROS levels, and decreased the expression of apoptotic markers and fibrosis-associated proteins in cardiac cells. The oh8dG-administrated cardiac tissues were also protected from enhanced HTK-induced damage markers, heat shock protein 60 and polyADP-ribose. Our results show that oh8dG has a protective role against myocardial oxidative damage and provides a useful treatment strategy for restoring cardiac function.

Alleviating Oxidative Damage-Induced Telomere Attrition: a Potential Mechanism for Inhibition by Folic Acid of Apoptosis in Neural Stem Cells

DNA oxidative damage can cause telomere attrition or dysfunction that triggers cell senescence and apoptosis. The hypothesis of this study is that folic acid decreases apoptosis in neural stem cells (NSCs) by preventing oxidative stress-induced telomere attrition. Primary cultures of NSCs were incubated for 9 days with various concentrations of folic acid (0-40 µM) and then incubated for 24 h with a combination of folic acid and an oxidant (100-µM hydrogen peroxide, H₂O₂), antioxidant (10-mM N-acetyl-L-cysteine, NAC), or vehicle. Intracellular folate concentration, apoptosis rate, cell proliferative capacity, telomere length, telomeric DNA oxidative damage, telomerase activity, intracellular reactive oxygen species (ROS) levels, cellular oxidative damage, and intracellular antioxidant enzyme activities were determined. The results showed that folic acid deficiency in NSCs decreased intracellular folate concentration, cell proliferation, telomere length, and telomerase activity but increased apoptosis, telomeric DNA oxidative damage, and intracellular ROS levels. In contrast, folic acid supplementation dose-dependently increased intracellular folate concentration, cell proliferative capacity, telomere length, and telomerase activity but decreased apoptosis, telomeric DNA oxidative damage, and intracellular ROS levels. Exposure to H₂O₂ aggravated telomere attrition and oxidative damage, whereas NAC alleviated the latter. High doses of folic acid prevented telomere attrition and telomeric DNA oxidative damage by H₂O₂. In conclusion, inhibition of telomeric DNA oxidative damage and telomere attrition in NSCs may be potential mechanisms of inhibiting NSC apoptosis by folic acid.

Hydroperoxide-Reducing Enzymes in the Regulation of Free-Radical Processes

The review presents current concepts of the molecular mechanisms of oxidative stress development and describes main stages of the free-radical reactions in oxidative stress. Endogenous and exogenous factors of the oxidative stress development, including dysfunction of cell oxidoreductase systems, as well as the effects of various external physicochemical factors, are discussed. The review also describes the main components of the antioxidant defense system and stages of its evolution, with a special focus on peroxiredoxins, glutathione peroxidases, and glutathione S-transferases, which share some phylogenetic, structural, and catalytic properties. The substrate specificity, as well as the similarities and differences in the catalytic mechanisms of these enzymes, are discussed in detail. The role of peroxiredoxins, glutathione peroxidases, and glutathione S-transferases in the regulation of hydroperoxide-mediated intracellular and intercellular signaling and interactions of these enzymes with receptors and non-receptor proteins are described. An important contribution of hydroperoxide-reducing enzymes to the antioxidant protection and regulation of such cell processes as growth, differentiation, and apoptosis is demonstrated.

Association between clinicopathological features of breast cancer with adipocytokine levels and oxidative stress markers before and after chemotherapy

Adipocytokines and markers of oxidative stress have been shown to exhibit potential for detection of advanced stage, HER2/neu status and lymph node metastases in patients with breast cancer, as well as in determining the efficiency of anti-cancer treatments. In the present study, blood concentrations of apelin (APLN), retinol-binding protein 4 (RBP4), 8-hydroxydeoxyguanosine (8-oxo-dG) and total antioxidant capacity (TAC) in women with breast cancer with different clinicopathological features were measured prior to and following adjuvant chemotherapy. The study included 60 women with breast cancer stratified according to tumor grade and size, HER-2/neu expression, and lymph node and hormone receptor status. Blood samples were taken before and after two cycles of adjuvant chemotherapy. None of the clinicopathological features were associated with the baseline concentrations of RBP4, 8-oxo-dG or TAC. An increased baseline concentration of APLN was observed in HER-2/neu positive patients. Moreover, through multivariate logistical regression analysis, APLN was shown to be independently associated with a positive HER/neu status. Chemotherapy treatment did not affect the levels of RBP4 or APLN, or TAC values when assessing all the patients, and when assessing the stratified groups of patients. Only 8-oxo-dG was found to be significantly decreased following drug administration (P=0.0009). This preliminary study demonstrated that APLN is a significant and independent predictor of HER-2/neu positive breast cancer. A significant reduction in 8-oxo-dG levels following chemotherapy may indicate its potential clinical utility in monitoring the effects of chemotherapy in breast cancer patients.

Protective effect of exogenous 8-oxo-2'-deoxyguanosine on Drosophila melanogaster larval stages under heat shock

The influence of exogenous 8-oxo-2'-deoxyguanosine on the development of Drosophila melanogaster under normal conditions, and under the influence of short-term heat shock was studied. It was shown that 8-oxo-2'-deoxyguanosine was not toxic at concentrations of up to 1 μM. A tendency to accelerate larval development and fly emergence was observed under the influence of this compound in our experiments. Short-term heat shock causes a 50-80% decrease in the number of larvae that complete development. The addition of exogenous 8-oxo-2'-deoxyguanosine to the food before thermal influence negates this effect and brings the levels of the imago emergence indicators back to the basal level. The obtained results are further evidence of the possible bioregulatory and adaptogen functions of 8-oxo-2'-deoxyguanosine.

Folic acid delays age-related cognitive decline in senescence-accelerated mouse prone 8: alleviating telomere attrition as a potential mechanism

The occurrence of telomere attrition in brain may cause senescence and death of neurons, leading to cognitive decline. Folic acid (FA) has been reported to improve cognitive performance in mild cognitive impairment; however, its association with telomere remains unclear. The study aimed to investigate if alleviation of telomere attrition by FA supplementation could act as a potential mechanism to delay age-related cognitive decline in senescence-accelerated mouse prone 8 (SAMP8). Aged SAMP8 mice were assigned to four treatment groups: FAdeficient diet (FA-D) group, FA-normal diet (FA-N) group, low FA-supplemented diet (FA-L) group and high FAsupplemented diet (FA-H) group. There was also an age-matched senescence-accelerated mouse resistant 1 (SAMR1) control group (Con-R), and a young SAMP8 control group (Con-Y). The results demonstrated that FA supplementation delayed age-related cognitive decline and neurodegeneration in SAMP8 mice. Importantly, this effect could be attributed to the alleviated telomere attrition, which might be interpreted by the decreased levels of reactive oxygen species. Additionally, improved telomere integrity stimulated mitochondrial function via telomere-p53-mithondria pathway, consequently delayed neuronal degeneration. In conclusion, we demonstrate that FA supplementation delays age-related neurodegeneration and cognitive decline in SAMP8 mice, in which alleviated telomere attrition could serve as one influential factor in the process.

Oxidized Cell-Free DNA Role in the Antioxidant Defense Mechanisms under Stress

The present study focuses on the investigation of the oxidized cell-free DNA (cfDNA) properties in several experimental models, including cultured cerebellum cells, peripheral blood lymphocytes (PBL), plasma, and hippocampus under an acute and chronic unpredictable stress model in rats. Firstly, our study shows that Spectrum Green fluorescence-labeled oxidized cfDNA fragments were transferred into the cytoplasm of 80% of the cerebellum culture cells; meanwhile, the nonoxidized cfDNA fragments do not pass into the cells. Oxidized cfDNA stimulates the antioxidant mechanisms and induction of transcription factor NRF2 expression, followed by an activation of NRF2 signaling pathway genes-rise of Nrf2 and Hmox1 gene expression and consequently NRF2 protein synthesis. Secondly, we showed that stress increases plasma cfDNA concentration in rats corresponding with the duration of the stress exposure. At the same time, our study did not reveal any significant changes of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) level in PBL of rats under acute or chronic stress, probably due to the significantly increased Nrf2 expression, that we found in such conditions. 8-oxodG is one of the most reliable markers of DNA oxidation. We also found an increased level of 8-oxodG in the hippocampal homogenates and hippocampal dentate gyrus in rats subjected to acute and chronic stress. Taken together, our data shows that oxidized cfDNA may play a significant role in systemic and neuronal physiological mechanisms of stress and adaptation.

Effect of ionizing radiation on physiological and molecular processes in plants

The study of effects of ionizing radiation (IR) on plants is important in relation to several problems: (I) the existence of zones where background radiation - either natural or technogenic - is increased; (II) the problems of space biology; (III) the use of IR in agricultural selection; (IV) general biological problems related to the fundamental patterns and specifics of the effects of IR on various living organisms. By now, researchers have accumulated and systematized a large body of data on the effects of IR on the growth and reproduction of plants, as well as on the changes induced by IR at the genetic level. At the same time, there is a large gap in understanding the mechanisms of IR influence on the biochemical and physiological processes - despite the fact that these processes form the basis determining the manifestation of IR effects at the level of the whole organism. On the one hand, the activity of physiological processes determines the growth of plants; on the other, it is determined by changes at the genetic level. Thus, it is the study of IR effects at the physiological and biochemical levels that can give the most detailed and complex picture of IR action in plants. The review focuses on the effects of radiation on the essential physiological processes, including photosynthesis, respiration, long-distance transport, the functioning of the hormonal system, and various biosynthetic processes. On the basis of a large body of experimental data, we analyze dose and time dependences of the IR-induced effects - which are qualitatively similar - on various physiological and biochemical processes. We also consider the sequence of stages in the development of those effects and discuss their mechanisms, as well as the cause-effect relationships between them. The primary IR-induced physicochemical reactions include the formation of various forms of reactive oxygen species (ROS) and are the cause of the observed changes in the functional activity of plants. The review emphasizes the role of hydrogen peroxide, a long-lived ROS, not only as a damaging agent, but also as a mediator - a universal intracellular messenger, which provides for the mechanism of long-distance signaling. A supposition is made that IR affects physiological processes mainly by violating the regulation of their activity. The violation seems to become possible due to the fact that there exists a crosstalk between different signaling systems of plants, such as ROS, calcium, hormonal and electrical systems. As a result of both acute and chronic irradiation, an increase in the level of ROS can influence the activity of a wide range of physiological processes - by regulating them both at the genetic and physiological levels. To understand the ways, by which IR affects plant growth and development, one needs detailed knowledge about the mechanisms of the processes that occur at the (i) genetic and (ii) physiological levels, as well as their interplay and (iii) knowledge about regulation of these processes at different levels.

Radioprotective Role of Peroxiredoxin 6

Peroxiredoxin 6 (Prdx6) is a member of an evolutionary ancient family of peroxidase enzymes with diverse functions in the cell. Prdx6 is an important enzymatic antioxidant. It reduces a wide range of peroxide substrates in the cell, thus playing a leading role in the maintenance of the redox homeostasis in mammalian cells. Beside peroxidase activity, Prdx6 has been shown to possess an activity of phospholipase A2, an enzyme playing an important role in membrane phospholipid metabolism. Moreover, Prdx6 takes part in intercellular and intracellular signal transduction due to its peroxidase and phospholipase activity, thus facilitating the initiation of regenerative processes in the cell, suppression of apoptosis, and activation of cell proliferation. Being an effective and important antioxidant enzyme, Prdx6 plays an essential role in neutralizing oxidative stress caused by various factors, including action of ionizing radiation. Endogenous Prdx6 has been shown to possess a significant radioprotective potential in cellular and animal models. Moreover, intravenous infusion of recombinant Prdx6 to animals before irradiation at lethal or sublethal doses has shown its high radioprotective effect. Exogenous Prdx6 effectively alleviates the severeness of radiation lesions, providing normalization of the functional state of radiosensitive organs and tissues, and leads to a significant elevation of the survival rate of animals. Prdx6 can be considered as a potent and promising radioprotective agent for reducing the pathological effect of ionizing radiation on mammalian organisms. The radioprotective properties and mechanisms of radioprotective action of Prdx6 are discussed in the current review.