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Stimulator-of-interferon genes (STING) is vital for sensing cytosolic DNA and initiating innate immune responses against microbial infection and tumors. Redox homeostasis is the balance of oxidative and reducing reactions present in all living systems. Yet, how the intracellular redox state controls STING activation is unclear. Here, we show that cellular redox homeostasis maintained by glutathione peroxidase 4 (GPX4) is required for STING activation. GPX4 deficiency enhanced cellular lipid peroxidation and thus specifically inhibited the cGAS-STING pathway. Concordantly, GPX4 deficiency inhibited herpes simplex virus-1 (HSV-1)-induced innate antiviral immune responses and promoted HSV-1 replication in vivo. Mechanistically, GPX4 inactivation increased production of lipid peroxidation, which led to STING carbonylation at C88 and inhibited its trafficking from the endoplasmic reticulum (ER) to the Golgi complex. Thus, cellular stress-induced lipid peroxidation specifically attenuates the STING DNA-sensing pathway, suggesting that GPX4 facilitates STING activation by maintaining redox homeostasis of lipids.

Chronic obstructive pulmonary disease (COPD) is a major cause of mortality that has been associated with inflammation and oxidative stress. The purpose of the present case-control study was to determine the relationships between oxidative stress-related genetic variants and the risk and severity of COPD, as well as, the influence of these variants on inflammatory and oxidative stress parameters. Genotyping of superoxide dismutase 1 (SOD1) + 35 A/C (rs2234694), catalase [A-21T (rs7943316), C-262T (rs1001179)] and glutathione peroxidase 1 (reduced glutathione (GSH)-Px1) 198Pro/Leu (rs1050450) was carried out in 143 patients with COPD and 216 healthy controls using PCR-RFLP. Serum levels of IL-6 and TNF-α were determined by enzyme-linked immunosorbent assays (ELISA), while the levels of reduced GSH, total antioxidant status (TAS), H 2 O 2 , lipid peroxides (TBARS) and protein carbonyls (PCs) were determined using spectrophotometric methods. We also evaluated the activities of GSH-Px, catalase, and superoxide dismutase (SOD) in both plasma and erythrocytes. We did not observe significant differences in the genotype and allele frequencies of chosen variants between COPD patients and healthy controls. A significant correlation was retrieved between the SOD1 + 35A/C variant and disease severity (odds ratios (OR) = 0.15, p = 0.04). In addition, patients having the +35AC genotype presented increased plasma levels of GSH and a reduced level of PCs (p = 0.03, p = 0.04, respectively). The present data highlighted the important role of antioxidant enzymes and their genetic variants in the oxidative stress-mediated pathogenesis and progression of COPD.

Background: Multiple sclerosis is widely accepted as an inflammatory disease. However, studies indicate that degenerative processes in the CNS occur prior to inflammation. In the widely used animal model experimental autoimmune encephalomyelitis (EAE), we investigated the significance of degenerative processes from mitochondrial membrane potentials, reactive oxidative species, cell death markers, chemokines, and inflammatory cell types in brain, spinal cord, and optic nerve tissue during the effector phase of the disease, before clinical disease was evident., Methods: Sixty-two rats were placed in eight groups, n = 6 to 10. Four groups were immunized with spinal cord homogenate emulsified in complete Freund's adjuvant (one served as EAE group), three groups were immunized with complete Freund's adjuvant only, and a control group was injected with phosphate buffered saline only. Groups were sacrificed 3, 5, 7, or 12-13 days after the intervention and analyzed for early signs of CNS degeneration., Results: Loss of mitochondrial membrane potential and oxidative changes was observed days before clinical disease debut at day 9.75 ± 0.89. The early mitochondrial changes were not associated with cytochrome C release, cleavage of caspases 9 (38/40 kDa) and 3 (17/19 kDa), and cleavage of PARP (89 kDa) or spectrin (120/150 kDa), and apoptosis was not initiated. Axonal degeneration was only present at disease onset. Increases in a range of cytokines and chemokines were observed systemically as a consequence of immunization with complete Freund's adjuvant, whereas the encephalitogenic emulsion induced an upregulation of the chemokines Ccl2, Ccl20, and Cxcl1, specifically in brain tissue, 7 days after immunization., Conclusion: Five to seven days after immunization, subtle decreases in the mitochondrial membrane potential and an increased reactive oxygen species burden in brain tissue were observed. No cell death was detected at these time-points, but a specific expression pattern of chemokines indicates activity in the CNS, several days before clinical disease debut.

Objective: This study aimed to assess the changes induced in HSA upon fructose-modification and to use the modified protein as an antigen for studying the presence of antibodies in diabetic patients. Further, magnitude of oxidative stress was also assessed., Methods: HSA was modified with fructose, changes induced were studied by DSC measurements and near-UV CD. The binding characteristics of antibodies in the sera of diabetes patients to native and modified-HSA was assessed by ELISA and band shift assay. The oxidative stress in these patients was studied by carbonyl content estimation, FRAP assay and TBARS determination, Results: DSC revealed that fructose modified-HSA was more thermostable than its native form. Changes in tertiary structure of fructose-modified HSA were seen in near-UV CD. Patient studies showed that fructose-modified HSA acts as a potent immunogen compared to its native form and the levels of antibodies against fructose-modified HSA served as a parameter for tracking the glycemic control and oxidative stress parameters (carbonyl content, FRAP value and MDA level) in diabetic patients., Conclusions: Fructose-modification of HSA causes perturbations in its structure and function, thereby, making the protein antigenic besides decreasing its antioxidant capacity. This study suggests that fructose-modified-HSA is an important contributor in diabetic pathophysiology., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The present study aimed to investigate the relationship between protein carbonylation and changes of the IgE reactivity of turbot parvalbumin (PV) following electron beam (EB) irradiation. The concentration of protein carbonyls, specific IgE binding, and IgE binding inhibition between irradiated and oxidized PV were assessed. Irradiation resulted in a 3-fold enhancement in the protein carbonyl content. In purified PV irradiated with a 10-kGy dose, specific IgE binding was reduced by 91.2±6.2%. When raw PV was treated with reactive oxygen species (ROS), the protein carbonyl content increased 17.6-fold, with the specific IgE binding being reduced by 87.9±6.5% at an ROS concentration of 10 nmol/mL. The IgE binding inhibition between irradiated and oxidized PV was investigated using an inhibition ELISA. Results showed that oxidized PV can inhibit the binding between irradiated PV and specific IgE with an IC50 of 8.2-58 ng according to different doses of irradiation. These findings suggest that EB irradiation reduces specific IgE binding, probably by the induction of protein carbonylation., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Systemic inflammation in patients with chronic obstructive pulmonary disease (COPD) has been related to the development of comorbidities. The level of systemic inflammatory mediators is aggravated as a response to exercise in these patients. The aim of this study was to investigate whether unloading of the respiratory muscles attenuates the inflammatory response to exercise in COPD patients. In a cross-over design, eight muscle-wasted stable COPD patients performed 40 W constant work-rate cycle exercise with and without non-invasive ventilation support (NIV vs control). Patients exercised until symptom limitation for maximally 20 min. Blood samples were taken at rest and at isotime or immediately after exercise. Duration of control and NIV-supported exercise was similar, both 12.9 ± 2.8 min. Interleukin- 6 (IL-6) plasma levels increased significantly by 25 ± 9% in response to control exercise, but not in response to NIV-supported exercise. Leukocyte concentrations increased similarly after control and NIV-supported exercise by ∼15%. Plasma concentrations of C-reactive protein, carbonylated proteins, and production of reactive oxygen species by blood cells were not affected by both exercise modes. This study demonstrates that NIV abolishes the IL-6 response to exercise in muscle-wasted patients with COPD. These data suggest that the respiratory muscles contribute to exercise-induced IL-6 release in these patients., (© 2012 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Rationale: There is increasing evidence for the presence of autoantibodies in chronic obstructive pulmonary disease (COPD). Chronic oxidative stress is an essential component in COPD pathogenesis and can lead to increased levels of highly reactive carbonyls in the lung, which could result in the formation of highly immunogenic carbonyl adducts on "self" proteins., Objectives: To determine the presence of autoantibodies to carbonyl-modified protein in patients with COPD and in a murine model of chronic ozone exposure. To assess the extent of activated immune responses toward carbonyl-modified proteins., Methods: Blood and peripheral lung were taken from patients with COPD, age-matched smokers, and nonsmokers with normal lung function, as well as patients with severe persistent asthma. Mice were exposed to ambient air or ozone for 6 weeks. Antibody titers were measured by ELISA, activated compliment deposition by immunohistochemistry, and cellular activation by ELISA and fluorescence-activated cell sorter., Measurements and Main Results: Antibody titer against carbonyl-modified self-protein was significantly increased in patients with Global Initiative for Chronic Obstructive Lung Disease stage III COPD compared with control subjects. Antibody levels inversely correlated with disease severity and showed a prevalence toward an IgG1 isotype. Deposition of activated complement in the vessels of COPD lung as well as autoantibodies against endothelial cells were also observed. Ozone-exposed mice similarly exhibited increased antibody titers to carbonyl-modified protein, as well as activated antigen-presenting cells in lung tissue and splenocytes sensitized to activation by carbonyl-modified protein., Conclusions: Carbonyl-modified proteins, arising as a result of oxidative stress, promote antibody production, providing a link by which oxidative stress could drive an autoimmune response in COPD.

Changes in the level of oxidative damage to proteins in CD1 outbred mice gamma irradiated with a dose of 3 Gy have been studied. The changes were estimated from the amount of carbonyl groups (CG) in the proteins. It was found that two hours after exposure to gamma radiation, the amount of CG in the cytoplasmic and nuclear fractions of the liver, heart, brain, and spleen sharply increased. Two months after irradiation, the level of CG in the cytoplasmic and nuclear subcellular fractions of the liver and brain decreased to the level of CG in the control animals, which were not exposed to radiation. In the subcellular fractions of the heart and spleen, the increase in the degree of damage was more significant and a high level of damage was observed even two months after irradiation. An enhancement of the antigenic properties of proteins from the liver, heart, and spleen in the postirradiation period was found. Spleen proteins were most immunogenic. A comparison of the antigenic properties of proteins isolated from the tissues 60 days after irradiation revealed a correlation between the level of oxidative damage and the immunogenicity of the total protein fraction.

Resveratrol (RSV), a naturally occurring phytoalexin that can be found in red wine, berries, and peanuts, has been shown to extend both mean and maximum life span in model organisms. RSV has also been reported to shift the physiology of middle-aged mice on a high-calorie diet toward that of mice on a standard diet. These beneficial effects of RSV have been suggested to resemble caloric restriction. Our study in F2 four-way cross-hybrid mice was the first to evaluate the effects of aging and long-term RSV treatment (14.09+/-3.4 mg/L in drinking water for 6 or 12 months) on biomarkers of oxidative damage to DNA, 8-hydroxy-2'-deoxyguanosine (8OHdG); lipid, 8-iso-prostaglandin(2 alpha) (8-iso-PGF(2 alpha)); and protein, protein carbonyl content (PCC). There was a significant age-dependent accumulation of oxidative damage to DNA, lipid, and protein as well as a clear increase in urine 8-iso-PGF(2 alpha) levels in the majority of mouse tissues. Rates of age-dependent increases in damage biomarkers varied between tissues. Chronic RSV treatment elevated total RSV plasma levels and reduced the observed age-dependent accumulation of (1) 8OHdG in liver and heart, (2) 8-iso-PGF(2 alpha) in heart and urine, and (3) PCC in liver and kidney. However, a 12-month RSV intake resulted in significant elevation of 8-iso-PGF(2 alpha) and PCC in kidney. Our studies demonstrate that RSV treatment consistently attenuated oxidative damage in tissues where age-related oxidative damage accumulation was prominent, but also suggested that chronic RSV treatment may induce nephrotoxicity.