Determination of carbonyl groups in oxidized proteins

Neuroprotective mechanism of trans,trans-Farnesol in an ICV-STZ-induced rat model of Alzheimer's pathology

BACKGROUND

Alzheimer's disease (AD) is a prominent cause of dementia, resulting in neurodegeneration and memory impairment. This condition imposes a considerable public health burden on both patients and their families due to the patients' functional impairments as well as the psychological and financial constraints. It has been well demonstrated that its aetiology involves proteinopathy, mitochondriopathies, and enhanced reactive oxygen species (ROS) generation, which are some of the key features of AD brains that further result in oxidative stress, excitotoxicity, autophagy, and mitochondrial dysfunction.

OBJECTIVE

The current investigation was created with the aim of elucidating the neurological defence mechanism of trans,trans-Farnesol (TF) against intracerebroventricular-streptozotocin (ICV-STZ)-induced Alzheimer-like symptoms and related pathologies in rodents.

MATERIALS AND METHODS

The current investigation involved male SD rats receiving TF (25-100 mg/kg, per oral) consecutively for 21 days in ICV-STZ-treated animals. An in silico study was carried out to explore the possible interaction between TF and NADH dehydrogenase and succinate dehydrogenase. Further, various behavioural (Morris water maze and novel object recognition test), biochemical (oxidants and anti-oxidant markers), activities of mitochondrial enzyme complexes and acetylcholinesterase (AChE), pro-inflammatory (tumor necrosis factor-alpha; TNF-α) levels, and histopathological studies were evaluated in specific brain regions.

RESULTS

Rats administered ICV-STZ followed by treatment with TF (25, 50, and 100 mg/kg) for 21 days had significantly better mental performance (reduced escape latency to access platform, extended time spent in target quadrant, and improved differential index) in the Morris water maze test and new object recognition test models when compared to control (ICV-STZ)-treated groups. Further, TF treatment significantly restored redox proportion, anti-oxidant levels, regained mitochondrial capacities, attenuated altered AChE action, levels of TNF-α, and histopathological alterations in certain brain regions in comparison with control. In in silico analysis, TF caused greater interaction with NADH dehydrogenase and succinate dehydrogenase.

CONCLUSION

The current work demonstrates the neuroprotective ability of TF in an experimental model with AD-like pathologies. The study further suggests that the neuroprotective impacts of TF may be related to its effects on TNF-α levels, oxidative stress pathways, and mitochondrial complex capabilities.

The Protection of Quinoa Protein on the Quality of Pork Patties during Freeze-Thaw Cycles: Physicochemical Properties, Sensory Quality and Protein Oxidative

The present study investigated the impact of quinoa protein (QP) on the physicochemical properties, sensory quality, and oxidative stability of myofibrillar protein (MP) in pork patties during five freeze-thaw (F-T) cycles. It was observed that repeated F-T cycles resulted in a deterioration of pork patty quality; however, the incorporation of QP effectively mitigated these changes. Throughout the F-T cycles, the sensory quality of the QP-treated group consistently surpassed that of the control group. After five F-T cycles, the thiobarbituric acid reactive substance (TBARS) content in the control group was measured at 0.423 mg/kg, whereas it significantly decreased to 0.347 mg/kg in the QP-treated group (p < 0.05). Furthermore, QP inclusion led to a decrease in pH and an increase in water-holding capacity (WHC) within pork patties. Following five F-T cycles, Ca2+-ATPase activity exhibited a significant increase of 11.10% in the QP-treated group compared to controls (p < 0.05). Additionally, supplementation with QP resulted in elevated total sulfhydryl content and reduced carbonyl content, Schiff base content, and dityrosine content within myofibrillar proteins (MPs), indicating its inhibitory effect on MP oxidation. In particular, after five F-T cycles, total sulfhydryl content reached 58.66 nmol/mL for the QP-treated group significantly higher than that observed for controls at 43.65 nmol/mL (p < 0.05). While carbonyl content increased from 2.37 nmol/mL to 4.63 nmol/mL between the first and fifth F-T cycle for controls; it only rose from 2.15 nmol/mL to 3.47 nmol/mL in the QP-treated group. The endogenous fluorescence levels were significantly higher (p < 0.05) in the QP-treated group compared to controls. In conclusion, the addition of QP enhanced the quality of pork patties and effectively inhibited the oxidative denaturation of MP during F-T cycles.

Neuroprotective Profile of Triazole Grandisin Analogue against Amyloid-Beta Oligomer-Induced Cognitive Impairment

Alzheimer's disease (AD) is a neurodegenerative disorder caused by accumulation of amyloid-β oligomers (AβO) in the brain, neuroinflammation, oxidative stress, and cognitive decline. Grandisin, a tetrahydrofuran neolignan, exhibits relevant anti-inflammatory and antioxidant properties. Interestingly, grandisin-based compounds were shown to prevent AβO-induced neuronal death in vitro. However, no study has assessed the effect of these compounds on the AD animal model. This study focuses on a triazole grandisin analogue (TGA) synthesized using simplification and bioisosteric drug design, which resulted in improved potency and solubility compared with the parent compound. This study aimed to investigate the possible in vivo effects of TGA against AβO-induced AD. Male C57/Bl6 mice underwent stereotaxic intracerebroventricular AβO (90 μM) or vehicle injections. 24 h after surgery, animals received intraperitoneal treatment with TGA (1 mg/kg) or vehicle, administered on a 14 day schedule. One day after treatment completion, a novel object recognition task (NORT) was performed. Memantine (10 mg/kg) was administered as a positive control. NORT retention sessions were performed on days 8 and 16 after AβO injection. Immediately after retention sessions, animals were euthanized for cortex and hippocampus collection. Specimens were subjected to oxidative stress and cytokine analyses. TGA reduced the level of cortex/hippocampus lipoperoxidation and prevented cognitive impairment in AβO-injected mice. Additionally, TGA reduced tumor necrosis factor (TNF) and interferon-γ (IFN-γ) levels in the hippocampus. By contrast, memantine failed to prevent cortex/hippocampus lipid peroxidation, recognition memory decline, and AβO-induced increases in TNF and IFN-γ levels in the hippocampus. Thus, memantine was unable to avoid the AβO-induced persistent cognitive impairment. The results showed that TGA may prevent memory impairment by exerting antioxidant and anti-inflammatory effects in AβO-injected mice. Moreover, TGA exhibited a persistent neuroprotective effect compared to memantine, reflecting an innovative profile of this promising agent against neurodegenerative diseases, such as AD.

Cronassial Ameliorates Autoimmune Encephalomyelitis by Inhibiting Lipid Oxidation and Carbonyl Stress in the Brain and Spinal Cord of Rats

In recent years, the pathogenetic role of oxidative stress in damaging myelin cells, a precursor to the development of myelin-related diseases such as multiple sclerosis, has gained increasing significance. Experimental autoimmune encephalomyelitis (EAE) in rats serves as an experimental model for human multiple sclerosis. Our study elucidates and demonstrates the antioxidant properties of Cronassial, a drug containing gangliosides, on the processes of free radical lipid oxidation and oxidative modification of proteins in the brains and spinal cords of rats with EAE. Our research results reveal an elevated production of oxidative stress products, including peroxides, hydroperoxides, and oxidized proteins, in experimental animals. This phenomenon is one of the factors contributing to myelin damage. Administering a ganglioside-containing drug normalizes the consequences of oxidative stress and inhibits the formation of reactive oxygen species. Consequently, the data obtained highlight the neuroprotective and antioxidant effects of Cronassial when administered to animals with autoimmune encephalomyelitis.

Effect of Flammulina velutipes polysaccharides on the physicochemical properties of catfish surimi and myofibrillar protein oxidation during frozen storage

This study investigated the effect of Flammulina velutipes polysaccharides (FVPs) on the myofibrillar protein (MP) oxidation protein and physicochemical properties of catfish surimi during 75 days of frozen storage at -18°C. FVP was added to surimi at 1%, 1.5%, and 2%, respectively; the degree of MP oxidation and the physicochemical properties of the surimi were investigated, and the microstructure of the surimi was observed by scanning electron microscopy (SEM). The results showed that the carbonyl content and the thiobarbituric acid reactive substances (TBARS) in the FVP groups were lower than those in the CK group (the blank surimi). In comparison, the total sulfhydryl content, solubility, and Ca2+-ATPase activity were higher than those in the CK group after 75 days of storage. The addition of FVP significantly increased the water-holding capacity (WHC), gel strength, elastic modulus (G'), and loss modulus (G") of surimi, and made the gel of surimi have stronger continuity and a denser structure. Therefore, FVP has a better cryoprotective effect on surimi. It improves the quality of surimi, decreases MP oxidation, and reduces lipid and water loss during frozen storage. The anti-freezing effect of FVP added at 2% was similar to that of commercial protectants (4% sucrose and 4% sorbitol).

Assessment of the effects of non-phthalate plasticizer DEHT on the bivalve molluscs Mytilus galloprovincialis

Due to their uncontrolled use, plastics has become an environmental concern, not only for their varying dimension but also for the potential release of substances such as phthalates (PAEs) and non-phthalates (NPPs) into the water. Phthalates are the most common plasticizers of concern, but non-phthalate plasticizers such as di (2-ethylhexyl) terephthalate (DEHT) have also been lately found in the marine environment. Mytilus galloprovincialis is a well-known bioindicator of aquatic environments due to its ability to accumulate a wide variety of xenobiotics, including plasticizers. Hence, aim of this study was to evaluate the potential bioaccumulation and effects of the NPP DEHT on M. galloprovincialis. To this purpose, following exposure to DEHT at 1 mg/l (DEHT1) and 100 mg/l (DEHT100), its accumulation in tissues and its effects on total lipids and fatty acid (FA) composition, protein content, cell viability, ability to recover volume and changes in biomarkers of oxidative stress were assessed. Mussels were able to bioaccumulate DEHT in their tissues, with a statistically significant increase compared to the control organisms. Differences in FA composition were observed after exposure, since C16:0, C18:0, C20:5ω-3 and C22:6ω-3 were significantly decreased from control to exposed groups. As a result, total SFA, MUFA and PUFA were affected in DEHT-exposed groups. Also, total protein varied following DEHT exposure, and significantly decreased in the DEHT100-group. Considering the physiological responses, both DEHT-exposed groups lost their ability to return to the original volume of digestive gland (DG) cells. On the other hand, oxidative biomarkers in the gills and DG were not significantly affected by the DEHT exposure. Overall, this study showed for the first time that DEHT exposure differentially affect mussels, in their lipid and protein metabolism, as well as cellular parameters.

Specific plasticity of the anemone Anthopleura hermaphroditica to intertidal and subtidal environmental conditions of the Quempillén estuary

The cellular capacity of marine organisms to address rapid fluctuations in environmental conditions is decisive, especially when their bathymetric distribution encompasses intertidal and subtidal zones of estuarine systems. To understand how the bathymetric distribution determines the oxidative damage and antioxidant response of the estuarine anemone Anthopleura hermaphroditica, individuals were collected from upper intertidal and shallow subtidal zones of Quempillén River estuary (Chile), and their response analysed in a fully orthogonal, multifactorial laboratory experiment. The organisms were exposed to the effects of temperature (10°C and 30°C), salinity (10 ppt and 30 ppt) and radiation (PAR, > 400-700 nm; PAR+UV-A, > 320-700 nm; PAR+UV-A+UV-B, > 280-700 nm), and their levels of lipid peroxidation, protein carbonyl and total antioxidant capacity were determined. The results indicated that the intertidal individuals of A. hermaphroditica presented higher levels of tolerance to the stressful ranges of temperature, salinity, and radiation than individuals from the subtidal zone, which was evident from their lower levels of oxidative damage to lipids and proteins. These results were consistent with increased levels of total antioxidant capacity observed in subtidal organisms. Thus intertidal individuals could have greater plasticity to environmental variations than subtidal individuals. Future studies are needed to understand the mechanisms underlying stress adaptation in individuals from this estuarine anemone subjected to different environmental stressors during their life cycles.

Polyphenol-rich açaí seed extract exhibits reno-protective and anti-fibrotic activities in renal tubular cells and mice with kidney failure

The main goal of this study was to evaluate the reno-protective effects of a phenolic-rich Açaí seed extract (ASE) in mice with kidney failure. Kidney failure was induced chemically with an adenine-rich diet (0.25% w/w for 4 weeks) in male CD1 Swiss mice. Mice were then provided daily with ASE (at a dose of ~ 350 mg/kg/day) in drinking water for 4 weeks. Adenine mice exhibited renal dysfunction evidenced by increased proteinuria, increased uremia, extensive tubular atrophy and kidney fibrosis associated with overexpression of pro-fibrotic genes (collagen 1a1, transforming growth factor β1, TGF-β1) and markers of tubular injury (such as Kidney injury molecule-1, KIM-1). ASE was able to beneficially counteract all these effects. ASE improved oxidative damage and fibrosis by decreasing carbonylated protein and MDA concentrations, as well as collagen deposition in renal tissue. ASE decreased the expression of TGF-β1 gene and the abundance of protein TGF-β1 in kidneys. It further decreased both expression and urinary excretion of tubular injury biomarkers, e.g., KIM-1 and Neutrophil gelatinase-associated lipocalin. CKD ASE-treated mice exhibited higher polyphenol content and total antioxidant capacity compared to control mice. ASE further prevented the expression of profibrotic genes in HK2 human tubular cells exposed to uremic toxins. Taken together, these findings suggest that ASE exerted potent reno-protective and anti-fibrotic effects through its antioxidant activity and the modulation of the TGF-β1 pathway.

Recent Approaches to Determine Static and Dynamic Redox State-Related Parameters

Oxidative stress refers to an imbalance between oxidant and antioxidant molecules, which is usually associated with oxidative damage to biomolecules and mitochondrial malfunction. Redox state-related parameters include (1) the direct measurement of ROS, (2) the assessment of the antioxidant defense status, and (3) the analysis of the resulting oxidative damage to molecules. Directly measuring ROS appears to be the preferred method among scientists, but most ROS are extremely unstable and difficult to measure. The processes of determining both the oxidative damage to biomolecules and the antioxidant system status, although both are indirect approaches, provide a reliable method to measure oxidative stress on a given sample. Recently, the Seahorse XF and the Oroboros O2k systems have provided new insights into the redox state from a more dynamic point of view. These techniques assess mitochondrial oxidative phosphorylation function and bioenergetics on isolated mitochondria, cultured cells, or specific tissues such as permeabilized fibers. This review describes a range of methodologies to measure redox state-related parameters, their strengths, and their limitations. In conclusion, all these techniques are valid and none of them can be replaced by another. Indeed, they have the potential to complement each other for a complete evaluation of the redox state of a given sample.

Salinity-dependent impacts on the effects of antiepileptic and antihistaminic drugs in Ruditapes philippinarum

In coastal systems, pollutants as pharmaceutical drugs exert changes from the molecular to the organism level in marine bivalves. Besides pollutants, coastal systems are prone to changes in environmental parameters, as the alteration of salinity values because of Climate Change. Together, these stressors (pharmaceutical drugs and salinity changes) can exert different threats than each stressor acting individually; for example, salinity can change the physical-chemical properties of the drugs and/or the sensitivity of the organisms to them. However, limited information is available on this subject, with variable results, and for this reason, this study aimed to evaluate the impacts of salinity changes (15, 25 and 35) on the effects of the antiepileptic carbamazepine (CBZ, 1 μg/L) and the antihistamine cetirizine (CTZ, 0.6 μg/L), when acting individually and combined (CBZ + CTZ), in the edible clam Ruditapes philippinarum. After 28 days of exposure, drugs concentrations, bioconcentration factors and biochemical parameters, related to clam's metabolic capacity and oxidative stress were evaluated. The results showed that clams under low salinity suffered more changes in metabolic, antioxidant and biotransformation activities, in comparison with the remaining salinities under study. However, limited impacts were observed when comparing drug effects at low salinity. Indeed, it seemed that CTZ and CBZ + CTZ, under high salinity (salinity 35) were the worst exposure conditions for the clams, since they caused higher levels of cellular damage. It stands out that salinity changes altered the impact of pharmaceutical drugs on marine bivalves.

Lysyl oxidase regulation and protein aldehydes in the injured newborn lung

During newborn lung injury, excessive activity of lysyl oxidases (LOXs) disrupts extracellular matrix (ECM) formation. Previous studies indicate that TGFβ activation in the O₂-injured mouse pup lung increases lysyl oxidase (LOX) expression. But how TGFβ regulates this, and whether the LOXs generate excess pulmonary aldehydes are unknown. First, we determined that O₂-mediated lung injury increases LOX protein expression in TGFβ-stimulated pup lung interstitial fibroblasts. This regulation appeared to be direct; this is because TGFβ treatment also increased LOX protein expression in isolated pup lung fibroblasts. Then using a fibroblast cell line, we determined that TGFβ stimulates LOX expression at a transcriptional level via Smad2/3-dependent signaling. LOX is translated as a pro-protein that requires secretion and extracellular cleavage before assuming amine oxidase activity and, in some cells, reuptake with nuclear localization. We found that pro-LOX is processed in the newborn mouse pup lung. Also, O₂-mediated injury was determined to increase pro-LOX secretion and nuclear LOX immunoreactivity particularly in areas populated with interstitial fibroblasts and exhibiting malformed ECM. Then, using molecular probes, we detected increased aldehyde levels in vivo in O₂-injured pup lungs, which mapped to areas of increased pro-LOX secretion in lung sections. Increased activity of LOXs plays a critical role in the aldehyde generation; an inhibitor of LOXs prevented the elevation of aldehydes in the O₂-injured pup lung. These results reveal new mechanisms of TGFβ and LOX in newborn lung disease and suggest that aldehyde-reactive probes might have utility in sensing the activation of LOXs in vivo during lung injury.

NADPH Oxidase Regulates the Growth and Pathogenicity of Penicillium expansum

The occurrence of reactive oxygen species (ROS) during the colonization of necrotrophic pathogens attacking fruit is critical during the attack, but its importance in Penicillium expansum remains unclear. This study aimed to determine the regulatory effects of NADPH oxidase (Nox) genes on the growth and pathogenicity of P. expansum in apple fruits. Deletion mutants of ΔPeNoxA, ΔPeNoxR, and ΔPeRacA genes were constructed to determine the contribution to the colonization process. The ΔPeRacA strain had a significant effect on the reduction of growth and pathogenicity, the ΔPeNoxA strain negatively regulated the growth and development of P. expansum and did not show any significant effect on the pathogenicity, and the ΔPeNoxR strain showed no effect on the growth or pathogenicity of P. expansum in the apple fruits. However, analysis of the content of O₂ ^- and H₂O₂ in the mycelium of all the Nox mutants showed a significant reduction, confirming the functionality of Nox mutations. Growth under stress conditions in the presence of Congo red, sodium lauryl sulfate, and H₂O₂ showed a negative effect on the radial growth of ΔPeNoxA, but a positive effect on radial growth reduction by ΔPeNoxR and ΔPeRacA mutants was shown. Interestingly, the host antioxidant activity levels of superoxide dismutase (SOD) andcatalase (CAT) in the fruits after inoculation with ΔPeNoxA, ΔPeNoxR, and ΔPeRacA mutants declined, suggesting reduced ROS accumulation in the colonized region. These results suggest that PeNoxA, PeNoxR, and PeRacA differentially regulate the growth and pathogenicity of P. expansum by producing ROS, and that PeRacA showed the strongest regulatory effect.

Phaseolin, a Protein from the Seed of Phaseolus vulgaris, Has Antioxidant, Antigenotoxic, and Chemopreventive Properties

The present report was designed to determine the antioxidant and antigenotoxic effects of phaseolin (isolated from Phaseolus vulgaris) against mouse colon and liver damage induced by azoxymethane (AOM) and its colon chemopreventive effect. Eight groups with 12 mice each were utilized for an eight-week experiment: the control group was intragastrically (ig) administered 0.9% saline solution; the positive control group was intraperitoneally (ip) injected with 7.5 mg/kg AOM twice a week (weeks three and four of the experiment); three groups were ig administered each day with phaseolin (40, 200, and 400 mg/kg); and three groups were ig administered phaseolin daily (40, 200, and 400 mg/kg) plus 7.5 mg/kg AOM twice a week in weeks three and four of the experiment. The results showed that phaseolin did not produce oxidative stress, DNA damage, or aberrant crypts; in contrast, 100% inhibition of lipoperoxidation, protein oxidation, and nitrites induction generated by AOM was found in both organs, and DPPH radical capture occurred. The two highest phaseolin doses reduced DNA damage induced by AOM in both organs by more than 90% and reduced the AOM-induced aberrant crypts by 84%. Therefore, our study demonstrated the strong in vivo antioxidant, antigenotoxic, and chemopreventive potential of phaseolin.

Plasma Protein Carbonyls as Biomarkers of Oxidative Stress in Chronic Kidney Disease, Dialysis, and Transplantation

Accumulating evidence indicates that oxidative stress plays a role in the pathophysiology of chronic kidney disease (CKD) and its progression; during renal replacement therapy, oxidative stress-derived oxidative damage also contributes to the development of CKD systemic complications, such as cardiovascular disease, hypertension, atherosclerosis, inflammation, anaemia, and impaired host defence. The main mechanism underlying these events is the retention of uremic toxins, which act as a substrate for oxidative processes and elicit the activation of inflammatory pathways targeting endothelial and immune cells. Due to the growing worldwide spread of CKD, there is an overwhelming need to find oxidative damage biomarkers that are easy to measure in biological fluids of subjects with CKD and patients undergoing renal replacement therapy (haemodialysis, peritoneal dialysis, and kidney transplantation), in order to overcome limitations of invasive monitoring of CKD progression. Several studies investigated biomarkers of protein oxidative damage in CKD, including plasma protein carbonyls (PCO), the most frequently used biomarker of protein damage. This review provides an up-to-date overview on advances concerning the correlation between plasma protein carbonylation in CKD progression (from stage 1 to stage 5) and the possibility that haemodialysis, peritoneal dialysis, and kidney transplantation improve plasma PCO levels. Despite the fact that the role of plasma PCO in CKD is often underestimated in clinical practice, emerging evidence highlights that plasma PCO can serve as good biomarkers of oxidative stress in CKD and substitutive therapies. Whether plasma PCO levels merely serve as biomarkers of CKD-related oxidative stress or whether they are associated with the pathogenesis of CKD complications deserves further evaluation.

TIGAR reduces smooth muscle cell autophagy to prevent pulmonary hypertension

Yamanaka R, Hoshino A, Fukai K, Urata R, Minami Y, Honda S, Fushimura Y, Hato D, Iwai-Kanai E, Matoba S. TIGAR reduces smooth muscle cell autophagy to prevent pulmonary hypertension. Am J Physiol Heart Circ Physiol 319: H1087-H1096, 2020. First published September 18, 2020; doi:10.1152/ajpheart.00314.2020.-Pulmonary arterial hypertension (PAH) is a refractory disease. Its prognosis remains poor; hence, establishment of novel therapeutic targets is urgent. TP53-induced glycolysis and apoptosis regulator (TIGAR) is a downstream target of p53 and exhibits functions inhibiting autophagy and reactive oxygen species (ROS). Recently, p53 was shown to suppress PAH progression. Because inhibition of autophagy and ROS is known to improve PAH, we examined the effect of TIGAR on PAH progression. We compared pulmonary hypertension (PH) development between TIGAR-deficient knockout (KO) and wild-type (WT) mice using a hypoxia-induced PH model. Human pulmonary artery smooth muscle cells (PASMCs) were used for in vitro experiments with small interfering RNA (siRNA) to investigate the possible molecular mechanisms. From the analysis of right ventricular pressure, right ventricular weight, and mortality rate, we concluded that the hypoxia-induced PH development was remarkably higher in TIGAR KO than in WT mice. Pathological investigation revealed that medial thickening of the pulmonary arterioles and cell proliferation were increased in TIGAR KO mice. Autophagy and ROS activity were also increased in TIGAR KO mice. TIGAR knockdown by siRNA increased cell proliferation and migration, exacerbated autophagy, and increased ROS generation during hypoxia. Autophagy inhibition by chloroquine and ROS inhibition by N-acetylcysteine attenuated the proliferation and migration of PASMCs caused by TIGAR knockdown and hypoxia exposure. TIGAR suppressed the proliferation and migration of PASMCs via inhibiting autophagy and ROS and, therefore, improved hypoxia-induced PH. Thus, TIGAR might be a promising therapeutic target for PAH.NEW & NOTEWORTHY Pulmonary arterial hypertension is a refractory disease. TP53-induced glycolysis and apoptosis regulator (TIGAR) is a downstream target of p53 and exhibits functions inhibiting autophagy and reactive oxygen species (ROS). By using TIGAR-deficient knockout mice and human pulmonary artery smooth muscle cells, we found that TIGAR suppressed the proliferation and migration of PASMCs via inhibiting autophagy and ROS and, therefore, improved hypoxia-induced PH. TIGAR will be a promising therapeutic target for PAH.

The Imbalance among Oxidative Biomarkers and Antioxidant Defense Systems in Thromboangiitis Obliterans (Winiwarter-Buerger Disease)

(1) Background: Thromboangiitis obliterans or Winiwarter-Buerger disease (WBD), is an inflammatory, thrombotic occlusive, peripheral vascular disease, usually occurring in young smokers. The pathophysiological mechanisms underlying the disease are not clearly understood. The aim of this study is to investigate the imbalance between oxidants and antioxidants occurring in these patients. (2) Patients and Methods: In this cross-sectional study, 22 male patients with WBD and 20 healthy male smoking habit matched control group were included. To evaluate the possible sources of oxidative stress, the antioxidant biomarkers, and the markers of lipid peroxidation and protein oxidation, serum samples were analyzed for total oxidative status (TOS), total antioxidant capacity (TAC), myeloperoxidase (MPO), coenzyme Q10 (CoQ10), superoxide dismutase (SOD), glutathione reductase (GR), malondialdehyde (MDA), and protein carbonyl (PC) activity and/or content. (3) Results: The circulating levels of TOS, TAC, and CoQ10 were significantly higher in WBD patients, with respect to healthy smokers as controls. No significant difference was found among the serum level of PC, total cholesterol, MPO, and GR activity in WBD patients and healthy smoker controls. The activity of SOD and the mean serum level of MDA were significantly lower in WBD patients, with respect to healthy smoker controls. (4) Conclusion: Considerably high levels of oxidative stress were detected in WBD patients, which were greater than the antioxidant capacity. The low level of MDA may be associated with the enzymatic degradation of lipid peroxidation products. High levels of CoQ10 and low levels of SOD may be related to a harmful oxidative cooperation, leading to the vasoconstriction of WBD, representing a promising tool to discern possible different clinical risks of this poorly understood peripheral occlusive disease.

Regulation of Nrf2 and NF-κB during lead toxicity in bovine granulosa cells

Lead (Pb), one of the pervasive and protracted environmental heavy metals, is believed to affect the female reproductive system in many species. The Nrf2 and NF-κB are the two key transcriptional factors regulating cellular redox status and response against stress and inflammation respectively, showing an interaction between each other. The aim of this study is to investigate the effect of Pb on bovine granulosa cells (GCs) and its association with the regulation of Nrf2 and NF-κB pathways. For this, bovine GCs were cultured in vitro and exposed to different doses of Pb for 2 h. Cellular response to Pb insult was investigated 24 h post treatment. Results showed that exposure of GCs to Pb-induced ROS accumulation and protein carbonylation. Additionally, GCs exhibited reduction in cell viability and decrease in the expression of cell proliferation marker genes (CCND2 and PCNA). This was accompanied by cell cycle arrest at G0/G1 phase. Moreover, Pb downregulated both Nrf2 and NF-κB and their downstream genes. Lead increased the expression of endoplasmic reticulum (ER) stress marker genes (GRP78 and CHOP) and the proapoptotic gene (caspase-3) while the antiapoptotic gene (BCL-2) was reduced. Our findings suggest that Pb-driven oxidative stress affected GCs proliferation, enhances ER stress, induces cell cycle arrest and mediates apoptosis probably via disruption of Nrf2/NF-κB cross-talk. However, further functional analysis is required to explain different aspects of Nrf2 and NF-κB interactions under metal challenge.

Hydrogen sulfide alleviates cigarette smoke-induced COPD through inhibition of the TGF-1/smad pathway

Smoking has become a major cause of chronic obstructive pulmonary disease through weakening of the respiratory mucus-ciliary transport system, impairing cough reflex sensitivity, and inducing inflammation. Recent researches have indicated that hydrogen sulfide is essential in the development of various lung diseases. However, the effect and mechanism of hydrogen sulfide on cigarette smoke-induced chronic obstructive pulmonary disease have not been reported. In this study, rats were treated with cigarette smoke to create a chronic obstructive pulmonary disease model followed by treatment with a low concentration of hydrogen sulfide. Pulmonary function, histopathological appearance, lung edema, permeability, airway remodeling indicators, oxidative products/antioxidases levels, inflammatory factors in lung, cell classification in bronchoalveolar lavage fluid were measured to examine the effect of hydrogen sulfide on chronic obstructive pulmonary disease model. The results showed that hydrogen sulfide effectively improved pulmonary function and reduced histopathological changes, lung edema, and permeability. Airway remodeling, oxidative stress, and inflammation were also reduced by hydrogen sulfide treatment. To understand the mechanisms, we measured the expression of TGF-β1, TGF-βIand TGF-βII receptors and Smad7 and phosphorylation of Smad2/Smad3. The results indicated that the TGF-β1 and Smad were activated in cigarette smoke-induced chronic obstructive pulmonary disease model, but inhibited by hydrogen sulfide. In conclusion, this study showed that hydrogen sulfide treatment alleviated cigarette smoke-induced chronic obstructive pulmonary disease through inhibition of the TGF-β1/Smad pathway.

Impact statement

COPD has become a severe public health issue in the world and smoking has become a major cause of COPD. As a result, it is a demandingly needed to explore new potential therapy for cigarette smoke-associated COPD. The present study suggested that H2S treatment improved pulmonary function and reduced histopathological changes, lung edema, permeability, inflammation, airway remodeling and oxidative injury in a COPD model induced by cigarette smoke. Although additional studies are required to elucidate the pharmacodynamics, pharmacokinetics, and pharmacology of H2S in the cigarette smoke-associated COPD, our findings provide an experimental basis for the potential clinical application of H2S in COPD treatment.

Detection, identification, and quantification of oxidative protein modifications

Exposure of biological molecules to oxidants is inevitable and therefore commonplace. Oxidative stress in cells arises from both external agents and endogenous processes that generate reactive species, either purposely (e.g. during pathogen killing or enzymatic reactions) or accidentally (e.g. exposure to radiation, pollutants, drugs, or chemicals). As proteins are highly abundant and react rapidly with many oxidants, they are highly susceptible to, and major targets of, oxidative damage. This can result in changes to protein structure, function, and turnover and to loss or (occasional) gain of activity. Accumulation of oxidatively-modified proteins, due to either increased generation or decreased removal, has been associated with both aging and multiple diseases. Different oxidants generate a broad, and sometimes characteristic, spectrum of post-translational modifications. The kinetics (rates) of damage formation also vary dramatically. There is a pressing need for reliable and robust methods that can detect, identify, and quantify the products formed on amino acids, peptides, and proteins, especially in complex systems. This review summarizes several advances in our understanding of this complex chemistry and highlights methods that are available to detect oxidative modifications-at the amino acid, peptide, or protein level-and their nature, quantity, and position within a peptide sequence. Although considerable progress has been made in the development and application of new techniques, it is clear that further development is required to fully assess the relative importance of protein oxidation and to determine whether an oxidation is a cause, or merely a consequence, of injurious processes.

Redox Proteomes in Human Physiology and Disease Mechanisms

Redox proteomics is a field of proteomics that is concerned with the characterization of the oxidation state of proteins to gain information about their modulated structure, function, activity, and involvement in different physiological pathways. Oxidative modifications of proteins have been shown to be implicated in normal physiological processes of cells as well as in pathomechanisms leading to the development of cancer, diabetes, neurodegenerative diseases, and some rare hereditary metabolic diseases, like classic galactosemia. Reactive oxygen species generate a variety of reversible and irreversible modifications in amino acid residue side chains and within the protein backbone. These oxidative post-translational modifications (Ox-PTMs) can participate in the activation of signal transduction pathways and mediate the toxicity of harmful oxidants. Thus the application of advanced redox proteomics technologies is important for gaining insights into molecular mechanisms of diseases. Mass-spectrometry-based proteomics is one of the most powerful methods that can be used to give detailed qualitative and quantitative information on protein modifications and allows us to characterize redox proteomes associated with diseases. This Review illustrates the role and biological consequences of Ox-PTMs under basal and oxidative stress conditions by focusing on protein carbonylation and S-glutathionylation, two abundant modifications with an impact on cellular pathways that have been intensively studied during the past decade.

Malondialdehyde interferes with the formation and detection of primary carbonyls in oxidized proteins

Carbonylation is one of the most remarkable expressions of the oxidative damage to proteins and the DNPH method the most common procedure to assess protein oxidation in biological samples. The present study was elicited by two hypotheses: i) is malondialdehyde, as a reactive dicarbonyl, able to induce the formation of allysine through a Maillard-type reaction? and ii) to which extent does the attachment of MDA to proteins interfere in the assessment of protein carbonyls using the DNPH method? Human serum albumin (HSA), human hemoglobin (HEM) and β-lactoglobulin (LAC) (5 mg/mL) were incubated with MDA (0.25 mM) for 24 h at 37 °C (HSA and HEM) or 80 °C (LAC). Results showed that MDA was unable to induce oxidative deamination of lysine residues and instead, formed stable and fluorescent adducts with proteins. Such adducts were tagged by the DNPH method, accounting for most of the protein hydrazones quantified. This interfering effect was observed in a wide range of MDA concentrations (0.05-1 mM). Being aware of its limitations, protein scientists should accurately interpret results from the DNPH method, and apply, when required, other methodologies such as chromatographic methods to detect specific primary oxidation products such as allysine.

The Precursor to Glutathione (GSH), γ-Glutamylcysteine (GGC), Can Ameliorate Oxidative Damage and Neuroinflammation Induced by Aβ40 Oligomers in Human Astrocytes

Glutathione (GSH) is one of the most abundant thiol antioxidants in cells. Many chronic and age-related diseases are associated with a decline in cellular GSH levels or impairment in the catalytic activity of the GSH biosynthetic enzyme glutamate cysteine ligase (GCL). γ-glutamylcysteine (GGC), a precursor to glutathione (GSH), can replenish depleted GSH levels under oxidative stress conditions, by circumventing the regulation of GSH biosynthesis and providing the limiting substrate. Soluble amyloid-β (Aβ) oligomers have been shown to induce oxidative stress, synaptic dysfunction and memory deficits which have been reported in Alzheimer’s disease (AD). Calcium ions, which are increased with age and in AD, have been previously reported to enhance the formation of Aβ₄₀ oligomers, which have been casually associated with the pathogenesis of the underlying neurodegenerative condition. In this study, we examined the potential beneficial effects of GGC against exogenous Aβ₄₀ oligomers on biomarkers of apoptosis and cell death, oxidative stress, and neuroinflammation, in human astrocytes. Treatment with Aβ₄₀ oligomers significantly reduced the cell viability and apoptosis of astrocyte brain cultures and increased oxidative modifications of DNA, lipids, and protein, enhanced pro-inflammatory cytokine release and increased the activity of the proteolytic matrix metalloproteinase enzyme, matric metalloproteinase (MMP)-2 and reduced the activity of MMP-9 after 24 h. Co-treatment of Aβ₄₀ oligomers with GGC at 200 μM increased the activity of the antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx) and led to significant increases in the levels of the total antioxidant capacity (TAC) and GSH and reduced the GSSG/GSH ratio. GGC also upregulated the level of the anti-inflammatory cytokine IL-10 and reduced the levels of the pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β) and attenuated the changes in metalloproteinase activity in oligomeric Aβ₄₀-treated astrocytes. Our data provides renewed insight on the beneficial effects of increased GSH levels by GGC in human astrocytes, and identifies yet another potential therapeutic strategy to attenuate the cytotoxic effects of Aβ oligomers in AD.

Oxidative Stress in β-Thalassemia

Cell oxidative status, which represents the balance between oxidants and antioxidants, is involved in normal functions. Under pathological conditions, there is a shift toward the oxidants, leading to oxidative stress, which is cytotoxic, causing oxidation of cellular components that result in cell death and organ damage. Thalassemia is a hereditary hemolytic anemia caused by mutations in globin genes that cause reduced or complete absence of specific globin chains (commonly, α or β). Although oxidative stress is not the primary etiology of thalassemia, it mediates several of its pathologies. The main causes of oxidative stress in thalassemia are the degradation of the unstable hemoglobin and iron overload-both stimulate the production of excess free radicals. The symptoms aggravated by oxidative stress include increased hemolysis, ineffective erythropoiesis and functional failure of vital organs such as the heart and liver. The oxidative status of each patient is affected by multiple internal and external factors, including genetic makeup, health conditions, nutrition, physical activity, age, and the environment (e.g., air pollution, radiation). In addition, oxidative stress is influenced by the clinical manifestations of the disease (unpaired globin chains, iron overload, anemia, etc.). Application of personalized (theranostics) medicine principles, including diagnostic tests for selecting targeted therapy, is therefore important for optimal treatment of the oxidative stress of these patients. We summarize the role of oxidative stress and the current and potential antioxidative therapeutics in β-thalassemia and describe some methodologies, mostly cellular, that might be helpful for application of a theranostics approach to therapy.

Oxidative stress under low oxygen conditions triggers hyperflagellation and motility in the Antarctic bacterium Pseudomonas extremaustralis

Reactive oxygen species and nitrogen species (ROS and RNS), produced in a wide range of physiological process even under low oxygen availability, are among the main stressors found in the environment. Strategies developed to combat them constitute key features in bacterial adaptability and survival. Pseudomonas extremaustralis is a metabolic versatile and stress resistant Antarctic bacterium, able to grow under different oxygen conditions. The present work explores the effect of oxidative stress under low oxygen conditions in P. extremaustralis, by combining RNA deep sequencing analysis and physiological studies. Cells grown under microaerobiosis exhibited more oxidative damage in macromolecules and lower survival rates than under aerobiosis. RNA-seq analysis showed an up-regulation of genes related with oxidative stress response, flagella, chemotaxis and biofilm formation while chaperones and cytochromes were down-regulated. Microaerobic cultures exposed to H₂O₂ also displayed a hyper-flagellated phenotype coupled with a high motility behavior. Moreover, cells that were subjected to oxidative stress presented increased biofilm formation. Altogether, our results suggest that a higher motile behavior and augmented capacity to form biofilm structures could work in addition to well-known antioxidant enzymes and non-enzymatic ROS scavenging mechanisms to cope with oxidative stress at low oxygen tensions.

Protective Effect of the Hexanic Extract of Eryngium carlinae Inflorescences In Vitro, in Yeast, and in Streptozotocin-Induced Diabetic Male Rats

In the present study, we investigated the composition and antioxidant activity of the hexanic extract of Eryngium carlinae inflorescences by employing in vitro assays to measure antioxidant capacity and 2,2-diphenyl-1-picrylhydrazyl scavenging activity. We also applied the hexanic extract to Saccharomyces cerevisiae, under hydrogen peroxide-induced stress. Finally, we tested the extract in male Wistar rats with and without streptozotocin-induced diabetes. The compounds in the hexanic extract were analyzed by gas-chromatography-mass spectrometry, which revealed mainly terpenes and sesquiterpenes, including (Z)β-farnesene (38.79%), β-pinene (17.53%), calamene (13.3%), and α-farnesene (10.38%). In vitro and in S. cerevisiae, the extract possessed antioxidant activity at different concentrations, compared to ascorbic acid (positive control). In normoglycemic and hyperglycemic rats, oral administration of 30 mg/kg of the extract reduced blood glucose levels; lipid peroxidation in liver, kidney and brain; protein carbonylation; and reactive oxygen species (ROS) production. It also increased catalase activity in the brain, kidneys and liver. These findings show that this hexanic extract of E. carlinae inflorescences possessed antioxidant properties.

Heme oxygenase-1 induction by hemin prevents oxidative stress-induced acute cholestasis in the rat

We previously demonstrated in in vitro and ex vivo models that physiological concentrations of unconjugated bilirubin (BR) prevent oxidative stress (OS)-induced hepatocanalicular dysfunction and cholestasis. Here, we aimed to ascertain, in the whole rat, whether a similar cholestatic OS injury can be counteracted by heme oxygenase-1 (HO-1) induction that consequently elevates endogenous BR levels. This was achieved through the administration of hemin, an inducer of HO-1, the rate-limiting step in BR generation. We found that BR peaked between 6 and 8 h after hemin administration. During this time period, HO-1 induction fully prevented the pro-oxidant tert-butylhydroperoxide (tBuOOH)-induced drop in bile flow, and in the biliary excretion of bile salts and glutathione, the two main driving forces of bile flow; this was associated with preservation of the membrane localization of their respective canalicular transporters, bile salt export pump (Bsep) and multidrug resistance-associated protein 2 (Mrp2), which are otherwise endocytosed by OS. HO-1 induction counteracted the oxidation of intracellular proteins and membrane lipids induced by tBuOOH, and fully prevented the increase in the oxidized-to-total glutathione (GSHt) ratio, a sensitive parameter of hepatocellular OS. Compensatory elevations of the activity of the antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD) were also prevented. We conclude that in vivo HO-1 induction protects the liver from acute oxidative injury, thus preventing consequent cholestasis. This reveals an important role for the induction of HO-1 and the consequently elevated levels of BR in preserving biliary secretory function under OS conditions, thus representing a novel therapeutic tool to limit the cholestatic injury that bears an oxidative background.

Anti-allodynic Effect of Mangiferin in Rats With Chronic Post-ischemia Pain: A Model of Complex Regional Pain Syndrome Type I

The present study reproduces chronic post-ischemia pain (CPIP), a model of complex regional pain syndrome type I (CRPS-I), in rats to examine the possible transient and long-term anti-allodynic effect of mangiferin (MG); as well as its potential beneficial interactions with some standard analgesic drugs and sympathetic-mediated vasoconstriction and vasodilator agents during the earlier stage of the pathology. A single dose of MG (50 and 100 mg/kg, p.o.) decreased mechanical allodynia 72 h post-ischemia-reperfusion (I/R). MG 100 mg/kg, i.p. (pre- vs. post-drug) increased von Frey thresholds in a yohimbine and naloxone-sensitive manner. Sub-effective doses of morphine, amitriptyline, prazosin, clonidine and a NO donor, SIN-1, in the presence of MG were found to be significantly anti-allodynic. A long-term anti-allodynic effect at 7 and 13 days post-I/R after repeated oral doses of MG (50 and 100 mg/kg) was also observed. Further, MG decreased spinal and muscle interleukin-1β concentration and restored muscle redox status. These results indicate that MG has a transient and long-term anti-allodynic effect in CPIP rats that appears to be at least partially attributable to the opioid and α2 adrenergic receptors. Additionally, its anti-inflammatory and antioxidant mechanisms could also be implicated in this effect. The association of MG with sub-effective doses of these drugs enhances the anti-allodynic effect; however, an isobolographic analysis should be performed to define a functional interaction between them. These findings suggest the possible clinical use of MG in the treatment of CRPS-I in both early sympathetically maintained pain and long-term sympathetically independent pain.

The loss of hemoglobin and myoglobin does not minimize oxidative stress in Antarctic icefishes

The unusual pattern of expression of hemoglobin (Hb) and myoglobin (Mb) among Antarctic notothenioid fishes provides an exceptional model system for assessing the impact of these proteins on oxidative stress. We tested the hypothesis that the lack of oxygen-binding proteins may reduce oxidative stress. Levels and activity of pro-oxidants and small-molecule and enzymatic antioxidants, and levels of oxidized lipids and proteins in the liver, oxidative skeletal muscle and heart ventricle were quantified in five species of notothenioid fishes differing in the expression of Hb and Mb. Levels of ubiquitinated proteins and rates of protein degradation by the 20S proteasome were also quantified. Although levels of oxidized proteins and lipids, ubiquitinated proteins, and antioxidants were higher in red-blooded fishes than in Hb-less icefishes in some tissues, this pattern did not persist across all tissues. Expression of Mb was not associated with oxidative damage in the heart ventricle, whereas the activity of citrate synthase and the contents of heme were positively correlated with oxidative damage in most tissues. Despite some tissue differences in levels of protein carbonyls among species, rates of degradation by the 20S proteasome were not markedly different, suggesting either alternative pathways for eliminating oxidized proteins or that redox tone varies among species. Together, our data indicate that the loss of Hb and Mb does not correspond with a clear pattern of either reduced oxidative defense or oxidative damage.

Skeletal muscle insulin resistance is induced by 4-hydroxy-2-hexenal, a by-product of n-3 fatty acid peroxidation

AIMS/HYPOTHESIS

Oxidative stress is involved in the pathophysiology of insulin resistance and its progression towards type 2 diabetes. The peroxidation of n-3 polyunsaturated fatty acids produces 4-hydroxy-2-hexenal (4-HHE), a lipid aldehyde with potent electrophilic properties able to interfere with many pathophysiological processes. The aim of the present study was to investigate the role of 4-HHE in the development of insulin resistance.

METHODS

4-HHE concentration was measured in plasma from humans and rats by GC-MS. Insulin resistance was estimated in healthy rats after administration of 4-HHE using hyperinsulinaemic-euglycaemic clamps. In muscle cells, glucose uptake was measured using 2-deoxy-D-glucose and signalling pathways were investigated by western blotting. Intracellular glutathione was measured using a fluorimetric assay kit and boosted using 1,2-dithiole-3-thione (D3T).

RESULTS

Circulating levels of 4-HHE in type 2 diabetic humans and a rat model of diabetes (obese Zucker diabetic fatty rats), were twice those in their non-diabetic counterparts (33 vs 14 nmol/l, p < 0.001), and positively correlated with blood glucose levels. During hyperinsulinaemic-euglycaemic clamps in rats, acute intravenous injection of 4-HHE significantly altered whole-body insulin sensitivity and decreased glucose infusion rate (24.2 vs 9.9 mg kg^-1 min^-1, p < 0.001). In vitro, 4-HHE impaired insulin-stimulated glucose uptake and signalling (protein kinase B/Akt and IRS1) in L6 muscle cells. Insulin-induced glucose uptake was reduced from 186 to 141.9 pmol mg^-1 min^-1 (p < 0.05). 4-HHE induced carbonylation of cell proteins and reduced glutathione concentration from 6.3 to 4.5 nmol/mg protein. Increasing intracellular glutathione pools using D3T prevented 4-HHE-induced carbonyl stress and insulin resistance.

CONCLUSIONS/INTERPRETATION

4-HHE is produced in type 2 diabetic humans and Zucker diabetic fatty rats and blunts insulin action in skeletal muscle. 4-HHE therefore plays a causal role in the pathophysiology of type 2 diabetes and might constitute a potential therapeutic target to taper oxidative stress-induced insulin resistance.

Ecotoxicity of the antihistaminic drug cetirizine to Ruditapes philippinarum clams

Cetirizine (CTZ) is an antihistaminic drug present in the aquatic environment, with limited information on its toxicity to organisms inhabiting this system. This study intended to evaluate the effects of CTZ on oxidative stress and energy metabolism biomarkers in the edible clam Ruditapes philippinarum after a 28days exposure to environmentally relevant CTZ concentrations (0.0, 0.3, 3.0, 6.0 and 12.0μg/L). The results obtained showed that CTZ was accumulated by clams reaching maximum concentrations (up to ~22ng/g FW) at the highest CTZ exposure concentrations (6.0 and 12.0μg/L). The bioconcentration factor (average maximum values of ~5) decreased at 12.0μg/L reflecting a reduction in clams uptake or increase of excretion capacity at this condition. The present study revealed that, in general, clams decreased the metabolic potential after exposure to CTZ (decrease in electron transport system activity), a response that led to the maintenance of glycogen content in organisms exposed to CTZ in comparison to control values. Our findings also showed that, CTZ did not exert significant levels of oxidative injury to clams. However, comparing the control with the highest exposure concentrations (6.0 and 12.0μg/L) a significant increase of the antioxidant enzyme superoxide activity (~53 and ~44%) was observed in clams exposed to CTZ. Moreover, a tendency to increase lipid peroxidation (~14 and ~9%) and carbonyl groups on proteins (~11 and ~3%) was observed in clams exposed to CTZ (6.0 and 12.0μg/L) compared to control condition. Overall the present study suggests that toxic impacts may be induced in R. philippinarum if exposed for longer periods or higher CTZ concentrations.

Unrestricted Mass Spectrometric Data Analysis for Identification, Localization, and Quantification of Oxidative Protein Modifications

Oxidation generates multiple diverse post-translational modifications resulting in changes in protein structure and function associated with a wide range of diseases. Of these modifications, carbonylations have often been used as hallmarks of oxidative damage. However, accumulating evidence supports the hypothesis that other oxidation products may be quantitatively more important under physiological conditions. To address this issue, we have developed a holistic mass spectrometry-based approach for the simultaneous identification, localization, and quantification of a broad range of oxidative modifications based on so-called "dependent peptides". The strategy involves unrestricted database searches with rigorous filtering focusing on oxidative modifications. The approach was applied to bovine serum albumin and human serum proteins subjected to metal ion-catalyzed oxidation, resulting in the identification of a wide range of different oxidative modifications. The most common modification in the oxidized samples is hydroxylation, but carbonylation, decarboxylation, and dihydroxylation are also abundant, while carbonylation showed the largest increase in abundance relative to nonoxidized samples. Site-specific localization of modified residues reveals several "oxidation hotspots" showing high levels of modification occupancy, including specific histidine, tryptophan, methionine, glutamate, and aspartate residues. The majority of the modifications, however, occur at low occupancy levels on a diversity of side chains.

Involvement of oxidative modification of proteins related to ATP synthesis in the left ventricles of hamsters with cardiomyopathy

Inflammation enhanced by accumulation of reactive oxygen species plays an essential role in the progression of cardiovascular diseases. Using the 2D-oxyblot analysis and 2D-difference image gel electrophoresis (2D-DIGE), we compared the levels of ROS-induced carbonyl modification of myocardial proteins in the whole left ventricles between 6-week-old hamsters with dilated (TO-2) and hypertrophic cardiomyopathy (Bio14.6) and control hamsters (F1B). Then, 2D electrophoresis combined with MALDI-TOF/TOF tandem mass spectrometry detected 18 proteins with increased carbonyl level in cardiomyopathy hamsters compared with control hamster. Carbonyl modification of proteins related to ATP synthesis, including citric acid cycle and electron transport system, was observed in the hearts of hamsters with both types of cardiomyopathy. Further analysis indicated that left ventricular carbonyl production correlated negatively with succinyl-CoA:3-ketoacid-coenzyme A transferase 1 activity (r 2 = 0.60, P = 0.0007) and ATP concentration (r 2 = 0.29, P = 0.037), suggesting that protein carbonylation has negative effects on the levels of these biomolecules. Furthermore, carbonyl production significantly correlated with plasma Troponin T level (r 2 = 0.33, P = 0.026). Reduction of energy metabolism by oxidative damage may contribute to the development of left ventricular impairment in cardiomyopathy.

Effect of Chitosan Edible Coating on the Biochemical and Physical Characteristics of Carp Fillet (Cyprinus carpio) Stored at -18°C

The effect of an edible coating (EC) with 1.5% chitosan as an additive, on common carp (Cyprinus carpio) fillet, was determined evaluating the biochemical, physicochemical, textural, microbiological, and nutritional characteristics periodically during its storage in the freezer (−18°C), observing a decrease in the rate of biochemical reactions related to degradation (p < 0.05), hydroperoxides content (HPC) (0.8324 nM hydroperoxides/mg of protein versus 0.5540 nM/mg with regard to the EC sample), as well as protein carbonyl content (PCC) (0.5860 nM versus 0.4743 nM of reactive carbonyl groups/mg of protein of noncoated material), keeping properties for a longer period of time, and a lower protein solubility (7.8 mg of supernatant protein/mg of total protein versus 6.8 mg/mg) and less loss of moisture (8% less, with regard to EC); for the nutritional characteristics of the fillet, lysine is the limiting aminoacid in the sample without EC, while leucine is the limiting aminoacid for the EC sample. According to microbial growth, the count was 2.2 × 10⁵ CFU/g of sample in mesophiles versus 4.7 × 10⁴ in the EC sample. The results indicate that the use of EC added with chitosan maintains the quality of the product regarding lipid and protein oxidation until fourth month of storage, maintaining moisture content without variation for at least 3 months, and inhibits microbial growth up to 2 logarithmic units, during five months of frozen storage.

Increased oxidative stress alters nucleosides metabolite levels in sickle cell anemia

OBJECTIVES

This study was conducted to assess the markers of oxidative stress, myeloperoxidase (MPO), acetylcholinesterase (AChE) and xanthine oxidase (XO) activities as well as the levels of nucleotide metabolites in sickle cell anemia (SCA) patients.

METHODS

Fifteen SCA treated patients and 30 health subjects (control group) were selected. The markers of oxidative stress (levels of reactive oxygen species (ROS), plasma proteins, carbonyl content, lipid peroxidation (TBARS), total thiols (T-SH), glutathione and catalase activity), MPO, AChE and XO activities as well as the levels of nucleotide metabolites were measured in SCA patients.

RESULTS

ROS, thiobarbituric acid-reactive substances (TBARS) and T-SH levels as well as the activities of catalase and MPO were significantly increased while glutathione level was reduced in SCA patients. Furthermore, a significant (P < 0.001) increase in hypoxanthine level was demonstrated in SCA patients. However, the serum levels for xanthine (P < 0.01) and uric acid (P < 0.001) were decreased in SCA patients. A significant (P < 0.001) decrease in XO activity was detected in SCA patients.

DISCUSSION

The altered parameters in SCA patients suggest that the generation and impairment of oxidative stress in this disease as well as antioxidant markers are contributory factors towards cellular redox homeostasis and alteration of purine metabolites.

Brazilian Green Propolis Improves Antioxidant Function in Patients with Type 2 Diabetes Mellitus

Propolis contains a variety of bioactive components and possesses many biological properties. This study was designed to evaluate potential effects of Brazilian green propolis on glucose metabolism and antioxidant function in patients with type 2 diabetes mellitus (T2DM). In the 18-week randomized controlled study, enrolled patients with T2DM were randomly assigned to Brazilian green propolis group (900 mg/day) (n = 32) and control group (n = 33). At the end of the study, no significant difference was found in serum glucose, glycosylated hemoglobin, insulin, aldose reductase or adiponectin between the two groups. However, serum GSH and total polyphenols were significantly increased, and serum carbonyls and lactate dehydrogenase activity were significantly reduced in the Brazilian green propolis group. Serum TNF-α was significantly decreased, whereas serum IL-1β and IL-6 were significantly increased in the Brazilian green propolis group. It is concluded that Brazilian green propolis is effective in improving antioxidant function in T2DM patients.

Effects of intermittent hypoxia on oxidative stress and protein degradation in molluscan mitochondria

Oxygen fluctuations represent a common stressor in estuarine and intertidal environments and can compromise the mitochondrial integrity and function in marine organisms. We assessed the role of mitochondrial protection mechanisms (ATP-dependent and ATP-independent mitochondrial proteases, and antioxidants) in tolerance to intermittent hypoxia or anoxia in three species of marine bivalves: the hypoxia tolerant hard clams (Mercenaria mercenaria) and oysters (Crassostrea virginica), and a hypoxia-sensitive subtidal scallop (Argopecten irradians). In clams and oysters, mitochondrial tolerance to hypoxia (18 h at 5% O2), anoxia (18 h at 0.1% O2) and subsequent reoxygenation was associated with the ability to maintain the steady-state activity of ATP-dependent and ATP-independent mitochondrial proteases and an anticipatory upregulation of the total antioxidant capacity (TAOC) under the low oxygen conditions. No accumulation of end-products of lipid or protein peroxidation was found during intermittent hypoxia or anoxia in clams and oysters (except for an increase in protein carbonyl concentration after hypoxia-reoxygenation in oysters). In contrast, hypoxia/anoxia and reoxygenation strongly suppressed activity of the ATP-dependent mitochondrial proteases in hypoxia-sensitive scallops. This suppression was associated with accumulation of oxidatively damaged mitochondrial proteins (including carbonylated proteins and proteins conjugated with a lipid peroxidation product malondialdehyde) despite high TAOC levels in scallop mitochondria. These findings highlight a key role of mitochondrial proteases in protection against hypoxia-reoxygenation stress and adaptations to frequent oxygen fluctuations in intertidal mollusks.

Glutamine Synthetase Sensitivity to Oxidative Modification during Nutrient Starvation in Prochlorococcus marinus PCC 9511

Glutamine synthetase plays a key role in nitrogen metabolism, thus the fine regulation of this enzyme in Prochlorococcus, which is especially important in the oligotrophic oceans where this marine cyanobacterium thrives. In this work, we studied the metal-catalyzed oxidation of glutamine synthetase in cultures of Prochlorococcus marinus strain PCC 9511 subjected to nutrient limitation. Nitrogen deprivation caused glutamine synthetase to be more sensitive to metal-catalyzed oxidation (a 36% increase compared to control, non starved samples). Nutrient starvation induced also a clear increase (three-fold in the case of nitrogen) in the concentration of carbonyl derivatives in cell extracts, which was also higher (22%) upon addition of the inhibitor of electron transport, DCMU, to cultures. Our results indicate that nutrient limitations, representative of the natural conditions in the Prochlorococcus habitat, affect the response of glutamine synthetase to oxidative inactivating systems. Implications of these results on the regulation of glutamine synthetase by oxidative alteration prior to degradation of the enzyme in Prochlorococcus are discussed.

The cellular and molecular progression of mitochondrial dysfunction induced by 2,4-dinitrophenol in developing zebrafish embryos

The etiology of mitochondrial disease is poorly understood. Furthermore, treatment options are limited, and diagnostic methods often lack the sensitivity to detect disease in its early stages. Disrupted oxidative phosphorylation (OXPHOS) that inhibits ATP production is a common phenotype of mitochondrial disorders that can be induced in zebrafish by exposure to 2,4-dinitrophenol (DNP), a FDA-banned weight-loss agent and EPA-regulated environmental toxicant, traditionally used in research labs as an uncoupler of OXPHOS. Despite the DNP-induced OXPHOS inhibition we observed using in vivo respirometry, the development of the DNP-treated and control zebrafish were largely similar during the first half of embryogenesis. During this period, DNP-treated embryos induced gene expression of mitochondrial and nuclear genes that stimulated the production of new mitochondria and increased glycolysis to yield normal levels of ATP. DNP-treated embryos were incapable of sustaining this mitochondrial biogenic response past mid-embryogenesis, as shown by significantly lowered ATP production and ATP levels, decreased gene expression, and the onset of developmental defects. Examining neural tissues commonly affected by mitochondrial disease, we found that DNP exposure also inhibited motor neuron axon arbor outgrowth and the proper formation of the retina. We observed and quantified the molecular and physiological progression of mitochondrial dysfunction during development with this new model of OXPHOS dysfunction, which has great potential for use in diagnostics and therapies for mitochondrial disease.

Oxidation of survival factor MEF2D in neuronal death and Parkinson's disease

AIMS

Dysfunction of myocyte enhancer factor 2D (MEF2D), a key survival protein and transcription factor, underlies the pathogenic loss of dopaminergic (DA) neurons in Parkinson's disease (PD). Both genetic factors and neurotoxins associated with PD impair MEF2D function in vitro and in animal models of PD. We investigated whether distinct stress conditions target MEF2D via converging mechanisms.

RESULTS

We showed that exposure of a DA neuronal cell line to 6-hyroxydopamine (6-OHDA), which causes PD in animals models, led to direct oxidative modifications of MEF2D. Oxidized MEF2D bound to heat-shock cognate protein 70 kDa, the key regulator for chaperone-mediated autophagy (CMA), at a higher affinity. Oxidative stress also increased the level of lysosomal-associated membrane protein 2A (LAMP2A), the rate-limiting receptor for CMA substrate flux, and stimulated CMA activity. These changes resulted in accelerated degradation of MEF2D. Importantly, 6-OHDA induced MEF2D oxidation and increased LAMP2A in the substantia nigra pars compacta region of the mouse brain. Consistently, the levels of oxidized MEF2D were much higher in postmortem PD brains compared with the controls. Functionally, reducing the levels of either MEF2D or LAMP2A exacerbated 6-OHDA-induced death of the DA neuronal cell line. Expression of an MEF2D mutant that is resistant to oxidative modification protected cells from 6-OHDA-induced death.

INNOVATION

This study showed that oxidization of survival protein MEF2D is one of the pathogenic mechanisms involved in oxidative stress-induced DA neuronal death.

CONCLUSION

Oxidation of survival factor MEF2D inhibits its function, underlies oxidative stress-induced neurotoxicity, and may be a part of the PD pathogenic process.

Markers of oxidative stress in adipose tissue during Trypanosoma cruzi infection

The protozoan parasite Trypanosoma cruzi causes Chagas disease. Cardiac and adipose tissues are among the early targets of infection and are sites of persistent infection. In the heart and adipose tissue, T. cruzi infection results in an upregulation of pro-inflammatory mediators. In the heart, infection is associated with an increase in the markers of oxidative stress. To date, markers of oxidative stress have not been evaluated in adipose tissue in this infection. Brown and white adipose tissues were obtained from CD-1 mice infected with the Brazil strain of T. cruzi for 15, 30, and 130 days post infection. Protein carbonylation and lipid peroxidation assays were performed on these samples. There was an upregulation of these markers of oxidative stress at all time-points in both white and brown adipose tissue. Determinants of anti-oxidative stress were downregulated at similar time-points. This increase in oxidative stress during T. cruzi infection most likely has a deleterious effect on host metabolism and on the heart.

Neuromodulatory effects of hesperidin in mitigating oxidative stress in streptozotocin induced diabetes

Oxidative stress has been implicated in pathogenesis of streptozotocin- (STZ-) induced diabetes mellitus and its complication in central nervous system (CNS). Recent studies have provided insights on antioxidants and their emergence as potential therapeutic and nutraceutical. The present study examined the hypothesis that hesperidin (HP) ameliorates oxidative stress and may be a limiting factor in the extent of CNS complication following diabetes. To test this hypothesis rats were divided into four groups: control, diabetic, diabetic-HP treated, and vehicle for HP treatment group. Diabetes mellitus was induced by a single injection of STZ (65 mg/kg body weight). Three days after STZ injection, HP was given (50 mg/kg b.wt. orally) once daily for four weeks. The results of the present investigation suggest that the significant elevated levels of oxidative stress markers were observed in STZ-treated animals, whereas significant depletion in the activity of nonenzymatic antioxidants and enzymatic antioxidants was witnessed in diabetic rat brain. Neurotoxicity biomarker activity was also altered significantly. HP treatment significantly attenuated the altered levels of oxidative stress and neurotoxicity biomarkers. Our results demonstrate that HP exhibits potent antioxidant and neuroprotective effects on the brain tissue against the diabetic oxidative damage in STZ-induced rodent model.

Oxidative stress in muscular dystrophy: from generic evidence to specific sources and targets

Muscular dystrophies (MDs) are a heterogeneous group of diseases that share a common end-point represented by muscular wasting. MDs are caused by mutations in a variety of genes encoding for different molecules, including extracellular matrix, transmembrane and membrane-associated proteins, cytoplasmic enzymes and nuclear proteins. However, it is still to be elucidated how genetic mutations can affect the molecular mechanisms underlying the contractile impairment occurring in these complex pathologies. The intracellular accumulation of reactive oxygen species (ROS) is widely accepted to play a key role in contractile derangements occurring in the different forms of MDs. However, scarce information is available concerning both the most relevant sources of ROS and their major molecular targets. This review focuses on (i) the sources of ROS, with a special emphasis on monoamine oxidase, a mitochondrial enzyme, and (ii) the targets of ROS, highlighting the relevance of the oxidative modification of myofilament proteins.

Cardio-metabolic effectsof HIV protease inhibitors (lopinavir/ritonavir)

Although antiretroviral treatment decreases HIV-AIDS morbidity/mortality, long-term side effects may include the onset of insulin resistance and cardiovascular diseases. However, the underlying molecular mechanisms responsible for highly active antiretroviral therapy (HAART)-induced cardio-metabolic effects are poorly understood. In light of this, we hypothesized that HIV protease inhibitor (PI) treatment (Lopinavir/Ritonavir) elevates myocardial oxidative stress and concomitantly inhibits the ubiquitin proteasome system (UPS), thereby attenuating cardiac function. Lopinavir/Ritonavir was dissolved in 1% ethanol (vehicle) and injected into mini-osmotic pumps that were surgically implanted into Wistar rats for 8 weeks vs. vehicle and sham controls. We subsequently evaluated metabolic parameters, gene/protein markers and heart function (ex vivo Langendorff perfusions). PI-treated rats exhibited increased serum LDL-cholesterol, higher tissue triglycerides (heart, liver), but no evidence of insulin resistance. In parallel, there was upregulation of hepatic gene expression, i.e. acetyl-CoA carboxylase β and 3-hydroxy-3-methylglutaryl-CoA-reductase, key regulators of fatty acid oxidation and cholesterol synthesis, respectively. PI-treated hearts displayed impaired cardiac contractile function together with attenuated UPS activity. However, there was no significant remodeling of hearts exposed to PIs, i.e. lack of ultrastructural changes, fibrosis, cardiac hypertrophic response, and oxidative stress. Western blot analysis of PI-treated hearts revealed that perturbed calcium handling may contribute to the PI-mediated contractile dysfunction. Here chronic PI administration led to elevated myocardial calcineurin, nuclear factor of activated T-cells 3 (NFAT3), connexin 43, and phosphorylated phospholamban, together with decreased calmodulin expression levels. This study demonstrates that early changes triggered by PI treatment include increased serum LDL-cholesterol levels together with attenuated cardiac function. Furthermore, PI exposure inhibits the myocardial UPS and leads to elevated calcineurin and connexin 43 expression that may be associated with the future onset of cardiac contractile dysfunction.

Mito-tempol and dexrazoxane exhibit cardioprotective and chemotherapeutic effects through specific protein oxidation and autophagy in a syngeneic breast tumor preclinical model

Several front-line chemotherapeutics cause mitochondria-derived, oxidative stress-mediated cardiotoxicity. Iron chelators and other antioxidants have not completely succeeded in mitigating this effect. One hindrance to the development of cardioprotectants is the lack of physiologically-relevant animal models to simultaneously study antitumor activity and cardioprotection. Therefore, we optimized a syngeneic rat model and examined the mechanisms by which oxidative stress affects outcome. Immune-competent spontaneously hypertensive rats (SHRs) were implanted with passaged, SHR-derived, breast tumor cell line, SST-2. Tumor growth and cytokine responses (IL-1A, MCP-1, TNF-α) were observed for two weeks post-implantation. To demonstrate the utility of the SHR/SST-2 model for monitoring both anticancer efficacy and cardiotoxicity, we tested cardiotoxic doxorubicin alone and in combination with an established cardioprotectant, dexrazoxane, or a nitroxide conjugated to a triphenylphosphonium cation, Mito-Tempol (4) [Mito-T (4)]. As predicted, tumor reduction and cardiomyopathy were demonstrated by doxorubicin. We confirmed mitochondrial accumulation of Mito-T (4) in tumor and cardiac tissue. Dexrazoxane and Mito-T (4) ameliorated doxorubicin-induced cardiomyopathy without altering the antitumor activity. Both agents increased the pro-survival autophagy marker LC3-II and decreased the apoptosis marker caspase-3 in the heart, independently and in combination with doxorubicin. Histopathology and transmission electron microscopy demonstrated apoptosis, autophagy, and necrosis corresponding to cytotoxicity in the tumor and cardioprotection in the heart. Changes in serum levels of 8-oxo-dG-modified DNA and total protein carbonylation corresponded to cardioprotective activity. Finally, 2D-electrophoresis/mass spectrometry identified specific serum proteins oxidized under cardiotoxic conditions. Our results demonstrate the utility of the SHR/SST-2 model and the potential of mitochondrially-directed agents to mitigate oxidative stress-induced cardiotoxicity. Our findings also emphasize the novel role of specific protein oxidation markers and autophagic mechanisms for cardioprotection.

Iron chelators with topoisomerase-inhibitory activity and their anticancer applications

SIGNIFICANCE

Iron and topoisomerases are abundant and essential cellular components. Iron is required for several key processes such as DNA synthesis, mitochondrial electron transport, synthesis of heme, and as a co-factor for many redox enzymes. Topoisomerases serve as critical enzymes that resolve topological problems during DNA synthesis, transcription, and repair. Neoplastic cells have higher uptake and utilization of iron, as well as elevated levels of topoisomerase family members. Separately, the chelation of iron and the cytotoxic inhibition of topoisomerase have yielded potent anticancer agents.

RECENT ADVANCES

The chemotherapeutic drugs doxorubicin and dexrazoxane both chelate iron and target topoisomerase 2 alpha (top2α). Newer chelators such as di-2-pyridylketone-4,4,-dimethyl-3-thiosemicarbazone and thiosemicarbazone -24 have recently been identified as top2α inhibitors. The growing list of agents that appear to chelate iron and inhibit topoisomerases prompts the question of whether and how these two distinct mechanisms might interplay for a cytotoxic chemotherapeutic outcome.

CRITICAL ISSUES

While iron chelation and topoisomerase inhibition each represent mechanistically advantageous anticancer therapeutic strategies, dual targeting agents present an attractive multi-modal opportunity for enhanced anticancer tumor killing and overcoming drug resistance. The commonalities and caveats of dual inhibition are presented in this review.

FUTURE DIRECTIONS

Gaps in knowledge, relevant biomarkers, and strategies for future in vivo studies with dual inhibitors are discussed.

Redox proteomics in selected neurodegenerative disorders: from its infancy to future applications

Several studies demonstrated that oxidative damage is a characteristic feature of many neurodegenerative diseases. The accumulation of oxidatively modified proteins may disrupt cellular functions by affecting protein expression, protein turnover, cell signaling, and induction of apoptosis and necrosis, suggesting that protein oxidation could have both physiological and pathological significance. For nearly two decades, our laboratory focused particular attention on studying oxidative damage of proteins and how their chemical modifications induced by reactive oxygen species/reactive nitrogen species correlate with pathology, biochemical alterations, and clinical presentations of Alzheimer's disease. This comprehensive article outlines basic knowledge of oxidative modification of proteins and lipids, followed by the principles of redox proteomics analysis, which also involve recent advances of mass spectrometry technology, and its application to selected age-related neurodegenerative diseases. Redox proteomics results obtained in different diseases and animal models thereof may provide new insights into the main mechanisms involved in the pathogenesis and progression of oxidative-stress-related neurodegenerative disorders. Redox proteomics can be considered a multifaceted approach that has the potential to provide insights into the molecular mechanisms of a disease, to find disease markers, as well as to identify potential targets for drug therapy. Considering the importance of a better understanding of the cause/effect of protein dysfunction in the pathogenesis and progression of neurodegenerative disorders, this article provides an overview of the intrinsic power of the redox proteomics approach together with the most significant results obtained by our laboratory and others during almost 10 years of research on neurodegenerative disorders since we initiated the field of redox proteomics.

Iron chelation inhibits the development of pulmonary vascular remodeling

Reactive oxygen species (ROS) have been implicated in the pathogenesis of pulmonary hypertension. Because iron is an important regulator of ROS biology, this study examined the effects of iron chelation on the development of pulmonary vascular remodeling. The administration of an iron chelator, deferoxamine, to rats prevented chronic hypoxia-induced pulmonary hypertension and pulmonary vascular remodeling. Various iron chelators inhibited the growth of cultured pulmonary artery smooth muscle cells. Protein carbonylation, an important iron-dependent biological event, was promoted in association with pulmonary vascular remodeling and cell growth. A proteomic approach identified that Rho GDP-dissociation inhibitor (a negative regulator of RhoA) is carbonylated. In human plasma, the protein carbonyl content was significantly higher in patients with idiopathic pulmonary arterial hypertension than in healthy controls. These results suggest that iron plays an important role in the ROS-dependent mechanism underlying the development of pulmonary hypertension.