AOPP-induced activation of human neutrophil and monocyte oxidative metabolism: a potential target for N-acetylcysteine treatment in dialysis patients

Evaluation of beneficial effects of dexpanthenol on hypoxic-ischemic encephalopathy

Hypoxic-ischemic encephalopathy (HIE) is a cause of serious morbidity and mortality in newborns. Dexpanthenol, which is metabolized into D-pantothenic acid, has antioxidant and other potentially therapeutic properties. We examined some effects of dexpanthenol on the brains of week-old rat pups with HIE induced by obstruction of the right carotid artery followed by keeping in 8% O2 for 2 hours. Dexpanthenol (500 mg/kg) was administered intraperitoneally to 16 of 32 pups with HIE. Protein, DNA, and lipid oxidation degradation products were assayed and hippocampal and cortical cell apoptosis and neuronal cell numbers were evaluated in stained sections. Dexpanthenol application reduced oxidative stress and inflammation. TNF-α and IL-6 cytokine levels in HIE also decreased with dexpanthenol treatment. The numbers of caspase-3 positive cells in the dentate gyrus and CA1/CA2/CA3 regions of the hippocampus was lower, and apoptosis was decreased in the dexpanthenol-treated animals. These findings suggest possible clinical applications of dexpanthenol in human HIE.

Association of Free Radical Product and Polycystic Ovary Syndrome: A Systematic Review and Meta-analysis

PURPOSE

Polycystic ovary syndrome (PCOS) is an endocrine disorder that primarily affects women of reproductive age. It is recognized as the leading cause of infertility due to anovulation. This research aims to evaluate the diagnostic potential of oxidative stress biomarkers, including advanced oxidation protein products (AOPP), malondialdehyde (MDA), uric acid (UA), and nitric oxide (NO), in identifying PCOS.

METHODS

A literature search was conducted in the EMBASE, PubMed, Cochrane Library, and Scopus databases. The standardized mean difference (SMD) and 95% confidence interval (CI) were employed to assess the correlation between free radical product and PCOS. Moreover, the presence of heterogeneity among the studies was assessed utilizing the I2 statistic and Cochran Q test. The methodological rigor of the incorporated studies was assessed through the application of the Newcastle-Ottawa Scale. Furthermore, the presence of publication bias was determined via Begg and Egger tests.

RESULTS

This meta-analysis reviewed 38 observational studies, including 17,845 women. The results revealed a significant association between PCOS in women and alterations in free radical levels. The study revealed that the PCOS group had significantly higher levels of AOPP (SMD = 3.193; 95% CI, 2.86 to 3.25), UA (SMD = 0.68; 95% CI, 0.24 to 1.13), and MDA (SMD = 1.16; 95% CI, 0.77 to 1.56) compared to the healthy control group. Furthermore, the analysis found a significantly lower level of NO (SMD = (- 0.59); 95% CI, - 1.15 to - 0.03) in the PCOS patient.

CONCLUSION

Screening of specific biomarkers associated with free radical products could provide valuable benefits in the prognosis and diagnosis of PCOS.

De Novo Design of a Highly Stable Ratiometric Probe for Long-Term Continuous Imaging of Endogenous HClO Burst

Long-term continuous imaging of endogenous HClO burst is of great importance for the elucidation of various physiological or pathological processes. However, most of the currently reported HClO probes have failed to achieve this goal due to their insufficient photobleaching resistance under a laser source. Herein, a highly stable ratiometric probe, HFTC-HClO 1, which is capable of continuously monitoring endogenous HClO burst over a long period of time, has been judiciously developed. Briefly, the de novo development of HFTC-HClO 1 mainly involved three main steps: (1) novel coumarins (HFTC 1-5) were designed and synthesized; (2) the most stable scaffold, HFTC 3, was selected through dye screening and cell imaging validation; and (3) based on HFTC 3, three candidate HClO probes were constructed, and HFTC-HClO 1 was finally selected due to its superior sensing properties toward HClO. Furthermore, HFTC-HClO 1 can quantitatively measure HClO levels in various real samples with excellent recovery (>90.4%), and the use of HFTC-HClO 1-coated test strips for qualitative analysis of HClO in real samples was also achieved. In addition, the application of HFTC-HClO 1 for long-term continuous monitoring of intracellular HClO burst was successfully demonstrated. Significantly, HFTC-HClO 1 was able to visualize HClO generated in the rheumatoid arthritis mouse model.

Petroselinum crispum Extract Prevents Scopolamine-Induced Lens Damage in Rats

Alzheimer's disease (AD) is a neurodegenerative disease that occurs especially in advanced ages. It reduces the quality of life of both the patient and their relatives. In addition to its primary effects, AD causes metabolic defects and tissues are damaged due to these effects. Oxidative stress damages cells by disrupting antioxidant/oxidant balance in many tissues, especially due to AD. In individuals with AD and the elderly, lens tissue is damaged due to oxidative stress and may cause vision loss. Therefore, it is very important to investigate herbal products that both prevent/cure AD and reduce AD-related oxidative stress, as they may have fewer side effects. In this study, the protective effects of parsley (Petroselinum crispum) extract on lens tissues of an experimental AD model induced by scopolamine were examined and evaluated through biochemical parameters. The result of biochemical experiments and principal component analysis, was observed that parsley extract had a therapeutic effect by reducing oxidative stress in lens tissues of experimentally induced AD rats. It can be suggested that the phenolic and flavonoid-rich content of parsley extract may have caused the reduction of oxidative damage in lens tissues and can be used to protect lens tissue against oxidative stress due to AD disease.

The usefulness of a complete blood count in the prediction of the first episode of schizophrenia diagnosis and its relationship with oxidative stress

A complete blood count (CBC) is a routinely performed blood examination. Only a few studies assess the relationship between CBC and oxidative stress (OS) in schizophrenia (SZ). The aim of the study was to assess the utility of CBC in the prediction of SZ diagnosis, and the relationship between CBC and OS. The study included: 47 individuals with the first episode of psychosis (26 drug-naive: FEP-nt; 21 patients under antipsychotic treatment: FEP-t) and 30 healthy persons (control group, HC). CBC and oxidative stress-related parameters were assessed in blood samples. The FEP group had higher levels of WBC, MCHC, NEU, MONO, EOZ, BASO, and %EOZ compared to HC (p<0.05). Various relationships between OS and CBC were found, and this connection was significantly different between healthy individuals and patients. The most promising C&RT model for discriminating FEP from HC was combining monocytes, eosinophils, and neutrophils (accuracy: 77%, 95%CI = 0.67-0.87). The analysis singled out WBC and HT (accuracy: 74%, 95%CI = 0.64-0.90) as the most promising to distinguish FEP-nt from HC; WBC and %Neu to allocate to FEP-t or HC group (accuracy: 87%, 95%CI = 0.64-0.90); RDW-SD and LYMPH (accuracy: 86%, 95% CI = 0.75-97) for distinguishing FEP-nt from FEP-t. CBC could be a promising, cheap tool to determine abnormalities related to schizophrenia. However, more studies with larger sample sizes are required.

Engineering of a novel D-A type fluorophore with hydrogen bond-induced enhanced emission property for sensitively detecting endogenous HOCl in living cells and tissues

Fluorescence imaging has been widely employed for biomedical research and clinical diagnostics. With ease of synthesis and excellent photophysical properties, D-A type fluorophores are widely designed for fluorescence imaging. However, traditional D-A type fluorophores are solvatochromic which reduces the fluorescence brightness in the biological system. To solve this problem and build on our previous work, we devised a novel HIEE fluorophore MTC with typical anti-solvatochromic fluorescence. Furthermore, the activated fluorescent probe designed based on MTC showed excellent imaging performance. We believe that the strategy based on the fluorophores with typical anti-solvatohromic fluorescence can be a useful platform for designing fluorescent probes for high-brightness imaging in the biological system.

The Combined Administration of Vitamin C and Copper Induces a Systemic Oxidative Stress and Kidney Injury

Vitamin C (ascorbic acid; AA) and copper (Cu²⁺) are well used supplements with many health-promoting actions. However, when they are used in combination, the Fenton reaction occurs, leading to the formation of highly reactive hydroxyl radicals. Given that kidney is vulnerable to many toxicants including free radicals, we speculated that the in vivo administration of AA plus Cu²⁺ may cause oxidative kidney injury. The purpose of this study was to address this possibility. Mice were administered with AA and Cu²⁺, alone or in combination, via oral gavage once a day for various periods. Changes in the systemic oxidative status, as well renal structure and functions, were examined. The administration of AA plus Cu²⁺ elevated protein oxidation in serum, intestine, bladder, and kidney, as evidenced by the increased sulfenic acid formation and decreased level of free sulfhydryl groups (-SH). The systemic oxidative stress induced by AA plus Cu²⁺ was associated with a significant loss of renal function and structure, as indicated by the increased blood urea nitrogen (BUN), creatinine and urinary proteins, as well as glomerular and tubular cell injury. These effects of AA and Cu²⁺ were only observed when used in combination, and could be entirely prevented by thiol antioxidant NAC. Further analysis using cultured renal tubular epithelial cells revealed that AA plus Cu²⁺ caused cellular protein oxidation and cell death, which could be abolished by NAC and catalase. Moreover, coincubation of AA and Cu²⁺ led to H₂O₂ production. Collectively, our study revealed that a combined administration of AA and Cu²⁺ resulted in systemic oxidative stress and renal cell injury. As health-promoting supplements, AA and Cu²⁺ should not be used together.

N-Acetylcysteine: more than preventing contrast-induced nephropathy in uremic patients-focus on the antioxidant and anti-inflammatory properties

Oxidative stress (OS) has been recognized as a pathophysiologic mechanism underlying the development and progression of chronic kidney disease (CKD). OS, which results from the disturbance of balance among pro-oxidants and antioxidants favoring the pro-oxidants, is present even in early CKD and increases progressively along with deterioration of kidney function to end-stage kidney disease (ESKD). In ESKD, OS is further exacerbated mainly due to dialysis procedures per se and predisposes to increased cardiovascular morbidity and mortality. Therefore, since OS plays a pivotal role in the pathogenesis and progression of atherosclerosis in uremic patients, several strategies aiming to ameliorate OS in these patients have been proposed. Among those, N-acetylcysteine (NAC), a thiol-containing antioxidant agent, has attracted special attention due to its pleiotropic functions and beneficial effect in various OS-related entities including paracetamol overdose and prevention of contrast-induced nephropathy. In this review, we present the currently available literature on the antioxidant and anti-inflammatory properties of NAC in CKD, including hemodialysis and peritoneal dialysis.

Astaxanthin Reduces the Severity of Intestinal Damage in a Neonatal Rat Model of Necrotizing Enterocolitis

OBJECTIVE

This study aimed to ascertain the effects of astaxanthin (ASX) in an experimental necrotizing enterocolitis (NEC) model using rat pups.

STUDY DESIGN

Forty-two pups born from five Wistar albino rats were randomly divided into three groups as the control group, NEC + placebo (saline), and NEC + ASX. Pups in the NEC + ASX group were given 100 mg/kg/day oral ASX from day 1 to day 4 of the study. Saline of 2 mL/kg was given to the NEC + placebo group. Histopathological, immunohistochemical (caspase-3), and biochemical evaluations including the total antioxidant status (TAS), total oxidant status (TOS), superoxide dismutase (SOD), glutathione (GSH), lipid hydroperoxide (LPO), 8-hydroxydeoxyguanosine (8-OHdG), advanced oxidation protein products (AOPP), myeloperoxidase (MPO), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and nuclear factor erythroid 2-related factor 2 (Nfr-2) activities were all performed.

RESULTS

A better survival rate and weight gain were demonstrated in the NEC + ASX group (p < 0.05). In the histopathological evaluation, the severity of intestinal damage was significantly reduced in the NEC + ASX group, as well as decreased apoptosis (enzyme-linked immunosorbent assay [ELISA] for caspase-3; p = 0.001). The biochemical analyses of intestinal tissue TOS, oxidative stress index (OSI; TOS/TAS), IL-1β, LPO, 8-OHdG, AOPP, caspase-3 (p < 0.001 for all), and TNF-α and MPO (p = 0.001 for both parameters) levels were lower in the NEC + ASX group than in the NEC + placebo group. Nrf-2, TAS, GSH, and SOD levels were higher in the NEC + ASX group than in the NEC + placebo group (p = 0.001, 0.001, <0.001, and 0.01, respectively).

CONCLUSION

ASX treatment has been shown to effectively reduce the severity of intestinal damage in NEC due to its antioxidant, anti-inflammatory, and antiapoptotic properties.

KEY POINTS

· NEC causes extremely high morbidity and mortality, as well as many complications.. · We investigated the effectiveness of ASX in the experimental NEC model created in rat pups.. · First study examining the effect of ASX on the experimental NEC rat model..

The neutrophil: A key resourceful agent in immune‐mediated vasculitis

The term "vasculitis" refers to a group of rare immune-mediated diseases characterized by the dysregulated immune system attacking blood vessels located in any organ of the body, including the skin, lungs, and kidneys. Vasculitides are classified according to the size of the vessel that is affected. Although this observation is not specific to small-, medium-, or large-vessel vasculitides, patients show a high circulating neutrophil-to-lymphocyte ratio, suggesting the direct or indirect involvement of neutrophils in these diseases. As first responders to infection or inflammation, neutrophils release cytotoxic mediators, including reactive oxygen species, proteases, and neutrophil extracellular traps. If not controlled, this dangerous arsenal can injure the vascular system, which acts as the main transport route for neutrophils, thereby amplifying the initial inflammatory stimulus and the recruitment of immune cells. This review highlights the ability of neutrophils to "set the tone" for immune cells and other cells in the vessel wall. Considering both their long-established and newly described roles, we extend their functions far beyond their direct host-damaging potential. We also review the roles of neutrophils in various types of primary vasculitis, including immune complex vasculitis, anti-neutrophil cytoplasmic antibody-associated vasculitis, polyarteritis nodosa, Kawasaki disease, giant cell arteritis, Takayasu arteritis, and Behçet's disease.

Relationship between Oxidative Stress and Endometritis: Exploiting Knowledge Gained in Mares and Cows

Simple Summary

Endometritis is a widespread pathology in mares and cows and one of the leading causes of reproductive efficiency decline. Although localized in the innermost layer of the uterus, this inflammation involves the release of bioactive molecules and by-products related to molecular damage. Among the bioactive substances, a primary role is played by the reactive oxygen and nitrogen species, which, while exerting an antimicrobial effect, can amplify the inflammation, sometimes causing unwanted and self-aggravating effects. Part of these substances enters the bloodstream, with implications that range from sustaining distant effects on organs and tissues to being used as diagnostic biomarkers. The research carried out on this matter in cows and mares has maintained certain independence due to its species specificity. This review aims to collect and analyze the information available in these species to enhance diagnostics and provide new insights to prevent and treat this pathology.

Abstract

The etiopathogenesis of endometritis in mares and cows differs significantly; this could depend on a different sensitivity and reactivity of the uterus but also on endocrine and rearing factors and different stress sources. In both species, microorganisms and the immune system play a primary role in the generation of this pathology. Microbiological and cytological tests support clinical examination and significantly improve diagnostic accuracy. For both species, during the inflammation, immune cells invade the endometrium and release bioactive substances to contrast primary or secondary pathogen contamination. These molecules are traceable to cytokines, chemokines, and prostaglandins as well as reactive oxygen and nitrogen species (ROS and RNS), collectively known as RONS. The RONS-mediated oxidation causes morphological and functional alterations of macromolecules, such as proteins, lipids, and nucleic acids, with the consequent production of derivative compounds capable of playing harmful effects. These bioactive molecules and by-products, which have recently become increasingly popular as diagnostic biomarkers, enter the bloodstream, influencing the functionality of organs and tissues. This review has collected and compared information obtained in cows and mares related to the diagnostic potential of these biomarkers that are assessed by using different methods in samples from either blood plasma or uterine fluid.

Glucocorticoids in a Neonatal Hyperoxic Lung Injury Model: Pulmonary and Neurotoxic effects

BACKGROUND

We aimed to compare the effect of dexamethasone (Dex), hydrocortisone (Hc), and methylprednisolone (Mpz) at equivalent doses on somatic growth, lung healing, and neurotoxicity in a hyperoxic rat model. We hypothesized that Mpz and Hc would be superior to Dex with less neurotoxicity by exerting similar therapeutic efficacy on the injured lung.

METHODS

Neonatal rats were randomized to control, bronchopulmonary dysplasia (BPD), Dex, Hc, and Mpz groups. All drugs were administered daily following day 15 over 7 days. Histopathological and immunohistochemical analyses of the lung and brain were performed on day 22.

RESULTS

All types had much the same impact on lung repair. Oxidative markers in the lung were similar in the steroid groups. While nuclear factor erythroid 2-related factor and heat-shock protein 70 dropped following steroid treatment, no difference was noted in other biochemical markers in the brain between the study groups. Apoptotic activity and neuron loss in the parietal cortex and hippocampus were noted utmost in Dex, but alike in other BPD groups.

CONCLUSIONS

Mpz does not appear to be superior to Dex or Hc in terms of pulmonary outcomes and oxidative damage in the brain, but safer than Dex regarding apoptotic neuron loss.

IMPACT

This is the first study that compared the pulmonary efficacy and neurotoxic effects of Dex, Hc, and Mpz simultaneously in an established BPD model. This study adds to the literature on the importance of possible antioxidant and protective effects of glucocorticoid therapy in an oxidative stress-exposed brain. Mpz ended up with no more additional neuron loss or apoptosis risk by having interchangeable effects with others for the treatment of established BPD. Mpz and Hc seem safe as a rescue therapy in terms of adverse outcomes for established BPD in which lung and brain tissue is already impaired.

The Examination of the Influence of Caffeinated Coffee Consumption on the Concentrations of Serum Prolactin and Selected Parameters of the Oxidative-Antioxidant Balance in Young Adults: A Preliminary Report

We verified whether caffeinated coffee consumption influenced the concentrations of prolactin (PRL) and oxidative stress parameters: total antioxidant status (TAS), ferric reducing antioxidant power (FRAP), total oxidant status (TOS), oxidative stress index (OSI), advanced oxidation protein products (AOPP), uric acid (UA), total bilirubin (T-Bil), albumin (ALB), iron (Fe), calcium (Ca), magnesium (Mg), and inflammatory marker C-reactive protein (CRP)—in blood sera obtained at 15, 60, and 120 minutes after caffeinated coffee intake, in relation to the fasting point. The study participants were 33 young, healthy, nonsmoking volunteers (15 men, 18 women) aged 19-29 years. PRL concentrations significantly decreased ( $p<0.05$ ) after consumption, except at time point 15’ in men ( $p>0.05$ ). In women, FRAP levels significantly increased over time, and significant changes were also observed for UA at 120’ and ALB at 15’. In men, significant changes were found for levels of AOPP at 15’, T-Bil and ALB at 15’, iron at 60’ and 120’, and calcium at 120’. There were no significant differences in the levels of other examined parameters between the defined time points. In conclusion, the substances contained in caffeinated coffee decrease the level of prolactin and may also have an impact on selected parameters of oxidative stress, which could be the basis of future research focused on the identification of new therapeutic targets.

Kidney injury and oxidative damage alleviation by Zingiber officinale: pharmacokinetics and protective approach in a combined murine model of osteoporosis

Ginger (Zingiber officinale) is considered as a nutraceutical spice, which possesses several health promotion and benefits. This study was carried out to investigate the phyto-chemical composition, the antioxidant capacities, the drug-likeness, and pharmacokinetic properties of ginger extract on kidney injury-associated osteoporosis in rats. Phenolic and flavonoid contents were assessed by standard chemical analysis methods and HPLC. In vivo protective effect was based on the use of female rats to evaluate the effect on renal injury as a result of combined osteoporosis using biochemical markers, oxidative status, and histological analyses. Results showed that ZO contained appreciable amounts of phenolics and flavonoids and it exhibited high scavenging activity. Ovariectomy-associated corticotherapy induced severe renal injury marked by altered biochemical markers (creatinine, urea, and uric acid), reduced GFR, significative oxidative damage signs, and disrupted antioxidant status in the combined osteoporotic rats. The histopathological examination revealed structural modifications of kidney tissues. However, all these changes were reversed following the use of ZO. These results confirm the renoprotective and antioxidant potential of ginger against renal injuries in osteoporotic rats.

Interaction between the Effects of Sustained Swimming Activity and Dietary Macronutrient Proportions on the Redox Status of Gilthead Sea Bream Juveniles (Sparus aurata L.)

The combination of physical exercise and a balanced diet presents substantial health benefits and could improve fish production. However, the redox balance can be affected by training regimen, dietary macronutrient ratio and their interaction. In this study, we conjointly evaluated the effects of physical activity (by voluntary swimming (VS) or sustained swimming as exercise (Ex)) and diet composition (by high-protein (HP) or high-lipid (HE) commercial diets) after 6 weeks on oxidative stress status in liver, white muscle and red muscle of gilthead sea bream juveniles. The HE diet increased the biochemical redox markers’ thiobarbituric acid reactive substances (TBARS), advanced oxidation protein products (AOPP) and reduced thiols (-SH) in the different tissues. Exercise increased AOPP and -SH levels in liver but reduced TBARS levels in white muscle. Regarding the expression of oxidative stress, chaperones and apoptosis-related genes, the VSHE group showed the highest values and the VSHP the lowest, whereas the application of sustained swimming partially equalized those differences. Diet composition modulated the enzyme activity, prioritizing the superoxide dismutase and catalase in the HE-fed groups and the glutathione-related enzymes in the HP groups. Exercise also altered enzyme activity, but in a tissue-dependent manner. Overall, the redox balance in gilthead sea bream juveniles can be affected by diet composition and sustained swimming. However, the response will partly depend on the interaction between these factors and the tissue studied. Therefore, the combination of an adequate diet and sustained exercise could be used in fish production to improve the physiological redox status.

PEG35 and Glutathione Improve Mitochondrial Function and Reduce Oxidative Stress in Cold Fatty Liver Graft Preservation

The need to meet the demand for transplants entails the use of steatotic livers, more vulnerable to ischemia-reperfusion (IR) injury. Therefore, finding the optimal composition of static cold storage (SCS) preservation solutions is crucial. Given that ROS regulation is a therapeutic strategy for liver IR injury, we have added increasing concentrations of PEG35 and glutathione (GSH) to the preservation solutions (IGL-1 and IGL-2) and evaluated the possible protection against energy depletion and oxidative stress. Fatty livers from obese Zücker rats were isolated and randomly distributed in the control (Sham) preserved (24 h at 4 °C) in IGL-0 (without PEG35 and 3 mmol/L GSH), IGL-1 (1 g/L PEG35, and 3 mmol/L GSH), and IGL-2 (5 g/L PEG35 and 9 mmol/L GSH). Energy metabolites (ATP and succinate) and the expression of mitochondrial oxidative phosphorylation complexes (OXPHOS) were determined. Mitochondrial carrier uncoupling protein 2 (UCP2), PTEN-induced kinase 1 (PINK1), nuclear factor-erythroid 2 related factor 2 (Nrf2), heme oxygenase-1 (HO-1), and the inflammasome (NLRP3) expressions were analyzed. As biomarkers of oxidative stress, protein oxidation (AOPP) and carbonylation (DNP derivatives), and lipid peroxidation (malondialdehyde (MDA)–thiobarbituric acid (TBA) adducts) were measured. In addition, the reduced and oxidized glutathione (GSH and GSSG) and enzymatic (Cu–Zn superoxide dismutase (SOD), CAT, GSH S-T, GSH-Px, and GSH-R) antioxidant capacities were determined. Our results showed that the cold preservation of fatty liver graft depleted ATP, accumulated succinate and increased oxidative stress. In contrast, the preservation with IGL-2 solution maintained ATP production, decreased succinate levels and increased OXPHOS complexes I and II, UCP2, and PINK-1 expression, therefore maintaining mitochondrial integrity. IGL-2 also protected against oxidative stress by increasing Nrf2 and HO-1 expression and GSH levels. Therefore, the presence of PEG35 in storage solutions may be a valuable option as an antioxidant agent for organ preservation in clinical transplantation.

The therapeutic effect of Apocynin against hyperoxy and Inflammation-Induced lung injury

Lung damage due to hyperoxia and inflammation are important causes of bronchopulmonary dysplasia (BPD). We aimed to investigate the beneficial effects of Apocynin (Apo) on rat pups exposed to hyperoxia and inflammation. Forty-eight rat pups were randomly divided into 3 groups as hyperoxia (95% O₂) + lipopolysaccharide (LPS), hyperoxia + LPS + Apo treated and control (21% O₂). Rat pups in the Apo group received Apo at a daily dose of 40 mg/kg. Histopathological (Hematoxylin-Eosin, Masson trichrome), immunochemical (surfactant B and C protein staining) evaluations and biochemical studies incluiding, total antioxidant status (TAS), total oxidant status (TOS), OSI (oxidant stress index), AOPP (advanced protein degradation product), Lipid hydroperoxide (LPO), 8-OHdG, NADPH oxidase activity (NOX), superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), myeloperoxidase (MPO), tumor necrosis factor-alpha (TNF- α), interleukin-1 beta (IL-1β), IL-18, IL-6, caspase-1 and 3, nuclear factor erythroid 2-related factor 2 (NFR2), Nod-like receptor pyrin domain-containing 3 (NLRP3) activities were studied. After Apo treatment, AOPP, LPO, 8-OHdG, NOX, TOS, OSI levels decreased; SOD, CAT, GSH and TAS levels increased (P < 0.05). Apo reduced inflammatory cell infiltration and proinflammatory cytokines with reduction in NLRP3 inflammasome in addition to increased Nrf2 levels. Moreover, caspase-1 and 3 levels decreased with Apo (P < 0.05). Apo was found to provide preventive and therapeutic effects by reducing oxidant stress, blocking inflammation and increasing antioxidant status. Beyond anti-oxidative effects, Apo also have anti-inflammatory effects by suppressing NLRP3 inflammasome activation and inducing Nrf2 as well. Therefore, Apo might be a potential option in the treatment of BPD.

Is There a Balance in Oxidative-Antioxidant Status in Blood Serum of Patients with Advanced Endometriosis?

Can redox homeostasis indicators be potential non-invasive markers, crucial in the diagnosis and treatment of endometriosis? We checked if the differences in levels of serum oxidative-antioxidant balance parameters (TAS, FRAP, albumin, total bilirubin, uric acid, iron, SIRT3, SIRT5, SIRT6, telomerase, AOPP) are significant between patients with advanced endometriosis (E), healthy women (control group, C) and non-endometriosis women, but with other gynecological disorders (NE). The FRAP concentrations were significantly higher in E and NE group than in the control group (p = 0.015 and p = 0.017, respectively). The telomerase concentrations were significantly higher in the endometriosis group than in the control group (p = 0.004). Significantly higher concentrations of AOPP were observed in E (p < 0.001) and NE groups (p = 0.028) in comparison to the control subjects. Between stages III and IV of endometriosis, a significant difference existed only in concentration of iron (p = 0.013). There were no significant differences between the studied groups in the values of the remaining parameters. Based on the results of ROC curve analysis, we can conclude that the levels of serum FRAP, telomerase and AOPP may be taken into account as promising diagnostics markers that reflect the degree of oxidative stress accompanying advanced endometriosis.

Advanced oxidation protein products trigger apoptosis and block epithelial-to-mesenchymal transition in crypt epithelial cells

Advanced oxidation protein products (AOPPs) are uremic toxins. The present study aimed to investigate the effects of AOPPs on the epithelial mesenchymal transition (EMT) and apoptosis of rat crypt epithelial cells, and to assess the signaling pathways involved. The oxidized rat serum albumin was obtained by sodium hypochlorite modification as AOPPs, and the rat serum albumin (RSA) without sodium hypochlorite modification was set as the control. Different concentrations of AOPPs or RSA were incubated with rat crypt epithelial cells (IEC-6 cells). After culturing for 48 and 72 h, apoptosis was detected by flow cytometry. IEC-6 cells were divided into three groups: A normal group, an AOPPs group and an RSA group. Three groups of cells were collected following treatment for 2 h, and the phosphorylation levels of Akt and p65 NF-κB were detected by western blotting. After 72 h of treatment, the cells were collected and the apoptotic rate was detected by flow cytometry. The expression of EMT-related proteins was detected by reverse transcription-quantitative polymerase chain reaction and western blotting. The apoptotic rate of IEC-6 cells increased with the concentration of AOPPs, and the apoptotic rate of the AOPPs group was higher than that of the RSA group. The expression of fibronectin, snail, slug and collagen I in the AOPPs group was lower than that in the RSA group, while the expression of E-cadherin was not significantly different between the two groups. In addition, the expression of fibronectin, snail, slug and collagen I genes in the AOPPs-treated group was equal to or lower than that in the normal group. Compared with the normal group, the Akt phosphorylation level was decreased and the p65 phosphorylation level was increased in the AOPPs- or RSA-treated groups. Compared with the AOPPs-treated group, Akt and p65 phosphorylation levels in RSA-treated group were slightly higher. In conclusion, AOPPs trigger apoptosis and inhibit the EMT of rat crypt epithelial cells, which may be associated with the inhibition of Akt phosphorylation and the promotion of p65 phosphorylation.

Could Antioxidant Supplementation Delay Progression of Cardiovascular Disease in End-Stage Renal Disease Patients?

In end-stage renal disease patients, the leading causes of mortality are of cardiovascular (CV) origin. The underlying mechanisms are complex, given that sudden heart failure is more common than acute myocardial infarction. A contributing role of oxidative stress is postulated, which is increased even at early stages of chronic kidney disease, is gradually augmented in parallel to progression to endstage renal disease and is further accelerated by renal replacement therapy. Oxidative stress ensues when there is an imbalance between reactive pro-oxidants and physiologically occurring electron donating antioxidant defence systems. During the last decade, a close association of oxidative stress with accelerated atherosclerosis and increased risk for CV and all-cause mortality has been established. Lipid peroxidation has been identified as a trigger for endothelial dysfunction, the first step towards atherogenesis. In order to counteract the deleterious effects of free radicals and thereby ameliorate, or delay, CV disease, exogenous administration of antioxidants has been proposed. Here, we attempt to summarize existing data from studies that test antioxidants for CV protection, such as vitamins E and C, statins, omega-3 fatty acids and N-acetylcysteine.

Role of PEG35, Mitochondrial ALDH2, and Glutathione in Cold Fatty Liver Graft Preservation: An IGL-2 Approach

The total damage inflicted on the liver before transplantation is associated with several surgical manipulations, such as organ recovery, washout of the graft, cold conservation in organ preservation solutions (UW, Celsior, HTK, IGL-1), and rinsing of the organ before implantation. Polyethylene glycol 35 (PEG35) is the oncotic agent present in the IGL-1 solution, which is an alternative to UW and Celsior solutions in liver clinical transplantation. In a model of cold preservation in rats (4 °C; 24 h), we evaluated the effects induced by PEG35 on detoxifying enzymes and nitric oxide, comparing IGL-1 to IGL-0 (which is the same as IGL-1 without PEG). The benefits were also assessed in a new IGL-2 solution characterized by increased concentrations of PEG35 (from 1 g/L to 5 g/L) and glutathione (from 3 mmol/L to 9 mmol/L) compared to IGL-1. We demonstrated that PEG35 promoted the mitochondrial enzyme ALDH2, and in combination with glutathione, prevented the formation of toxic aldehyde adducts (measured as 4-hydroxynonenal) and oxidized proteins (AOPP). In addition, PEG35 promoted the vasodilator factor nitric oxide, which may improve the microcirculatory disturbances in steatotic grafts during preservation and revascularization. All of these results lead to a reduction in damage inflicted on the fatty liver graft during the cold storage preservation. In this communication, we report on the benefits of IGL-2 in hypothermic static preservation, which has already been proved to confer benefits in hypothermic oxygenated dynamic preservation. Hence, the data reported here reinforce the fact that IGL-2 is a suitable alternative to be used as a unique solution/perfusate when hypothermic static and preservation strategies are used, either separately or combined, easing the logistics and avoiding the mixture of different solutions/perfusates, especially when fatty liver grafts are used. Further research regarding new therapeutic and pharmacological insights is needed to explore the underlying mitochondrial mechanisms exerted by PEG35 in static and dynamic graft preservation strategies for clinical liver transplantation purposes.

Hypochlorous acid-modified human serum albumin suppresses MHC class II - dependent antigen presentation in pro-inflammatory macrophages

Macrophages are innate immune cells that internalize and present exogenous antigens to T cells via MHC class II proteins. They operate at sites of infection in a highly inflammatory environment, generated in part by reactive oxygen species, in particular the strong oxidant hypochlorous acid (HOCl) produced in the neutrophil respiratory burst. HOCl effectively kills a broad range of pathogens but can also contribute to host tissue damage at sites of inflammation. To prevent tissue injury, HOCl is scavenged by human serum albumin (HSA) and other plasma proteins in interstitial fluids, leading to the formation of variously modified advanced oxidation products (AOPPs) with pro-inflammatory properties. Previously, we showed that HOCl-mediated N-chlorination converts HSA and other plasma proteins into efficient activators of the phagocyte respiratory burst, but the role of these AOPPs in antigen presentation by macrophages remained unclear. Here, we show that physiologically relevant amounts of N-chlorinated HSA can strongly impair the capacity of THP-1-derived macrophages to present antigens to antigen-specific T cells via MHC class II proteins at multiple stages. Initially, N-chlorinated HSA inhibits antigen internalization by converting antigens into scavenger receptor (SR) ligands and competing with the modified antigens for binding to SR CD36. Later steps of antigen presentation, such as intracellular antigen processing and MHC class II expression are negatively affected, as well. We propose that impaired processing of pathogens or exogenous antigens by immune cells at an initial stage of infection prevents antigen presentation in an environment potentially hostile to cells of the adaptive immune response, possibly shifting it towards locations removed from the actual insult, like the lymph nodes. On the flip side, excessive retardation or complete inhibition of antigen presentation by N-chlorinated plasma proteins could contribute to chronic infection and inflammation.

Advanced oxidation protein products induce inflammatory responses and invasive behaviour in fibroblast-like synoviocytes via the RAGE-NF-κB pathway

Aims

Rheumatoid arthritis (RA), which mainly results from fibroblast-like synoviocyte (FLS) dysfunction, is related to oxidative stress. Advanced oxidation protein products (AOPPs), which are proinflammatory mediators and a novel biomarker of oxidative stress, have been observed to accumulate significantly in the serum of RA patients. Here, we present the first investigation of the effects of AOPPs on RA-FLSs and the signalling pathway involved in AOPP-induced inflammatory responses and invasive behaviour.

Methods

We used different concentrations of AOPPs (50 to 200 µg/ml) to treat RA-FLSs. Cell migration and invasion and the expression levels of tumour necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), matrix metalloproteinase-3 (MMP-3), and MMP-13 were investigated. Western blot and immunofluorescence were used to analyze nuclear factor-κB (NF-κB) activation.

Results

AOPPs promoted RA-FLS migration and invasion in vitro and significantly induced the messenger RNA (mRNA) and protein expression of TNF-α, IL-6, MMP-3, and MMP-13 in dose- and time-dependent manners. Moreover, AOPPs markedly activated the phosphorylation of nuclear factor-κB (NF-κB) p65 protein, which triggered inhibitory kappa B-alpha (IκBα) degradation, NF-κB p65 protein phosphorylation, and NF-κB p65 translocation into the nucleus. Furthermore, treatment with a neutralizing antibody specific to receptor for advanced glycation end products (RAGE) significantly suppressed aggressive behaviour and inflammation, decreased TNF-α, IL-6, MMP-3, and MMP-13 expression, and blocked AOPP-induced NF-κB pathway activation.

Conclusion

The results indicate that AOPPs can enhance aggressive behaviour and the inflammatory response in RA-FLSs via the RAGE–NF-κB pathway. These results present AOPPs as a new class of potentially important mediators of progressive disease in RA patients.

Cite this article: Bone Joint Res 2021;10(4):259–268.

Favorable Effects of Astaxanthin on Brain Damage due to Ischemia- Reperfusion Injury

BACKGROUND

Activated inflammation and oxidant stress during cerebral ischemia reperfusion injury (IRI) lead to brain damage. Astaxanthin (ASX) is a type of carotenoid with a strong antioxidant effect.

OBJECTIVE

The aim of this study was to investigate the role of ASX on brain IRI.

METHODS

A total of 42 adult male Sprague-Dawley rats were divided into 3 groups as control (n=14) group, IRI (n=14) group and IRI + ASX (n=14) group. Cerebral ischemia was instituted by occluding middle cerebral artery for 120 minutes and subsequently, reperfusion was performed for 48 hours. Oxidant parameter levels and protein degradation products were evaluated. Hippocampal and cortex cell apoptosis, neuronal cell count, neurological deficit score were evaluated.

RESULTS

In the IRI group, oxidant parameter levels and protein degradation products in the tissue were increased compared to control group. However, these values were significantly decreased in the IRI + ASX group (p<0.05). There was a significant decrease in hippocampal and cortex cell apoptosis and a significant increase in the number of neuronal cells in the IRI + ASX group compared to the IRI group alone (p<0.05). The neurological deficit score which was significantly lower in the IRI group compared to the control group was found to be significantly improved in the IRI + ASX group (p<0.05).

CONCLUSION

Astaxanthin protects the brain from oxidative damage and reduces neuronal deficits due to IRI injury.

Cerebrospinal fluid lactoperoxidase level is enhanced in idiopathic Parkinson's disease, and correlates with levodopa equivalent daily dose

Lactoperoxidase (LPO) is proposed to play a role in the pathogenesis of Parkinson's disease (PD). This enzyme has been reported to be enhanced in the cerebrospinal fluid (CSF) in parkinsonian patients. The objective was to look at the relationship of LPO in the CSF and serum with clinical features of idiopathic PD. LPO concentration was analyzed through ELISA techniques. Correlation of CSF or serum LPO and MDS-UPDRS, dopaminergic medication, and other clinical parameters was examined. The findings revealed that LPO concentration in the CSF, not serum, was found to be elevated in patients with PD relative to controls (p < 0.001). CSF LPO concentration negatively correlated with MDS-UPDRS part-IV score (p < .0001), a rating scale that allows evaluating motor complications. CSF LPO level inversely correlated with the dose intensity of the dopaminergic medication regimen, as evaluated with levodopa equivalent dose or LED (mg/day; p < .0001). LED value positively correlated with MDS-UPDRS part-IV score (p < .0001). To sum up, the findings indicate that CSF LPO is found to be elevated in the CSF of PD patients, and this enzyme holds promise as potential biomarker for diagnosis of PD. Increasing the dose intensity of the dopaminergic medication regimen attenuates the elevation in LPO levels in the CSF, and it facilitates the development of motor complications in patients. The pathophysiological mechanisms that seem to be responsible for LPO increase would include dopamine deficiency, oxidative stress, and less likely, microbial infection.

The effects of neutrophil-generated hypochlorous acid and other hypohalous acids on host and pathogens

Neutrophils are predominant immune cells that protect the human body against infections by deploying sophisticated antimicrobial strategies including phagocytosis of bacteria and neutrophil extracellular trap (NET) formation. Here, we provide an overview of the mechanisms by which neutrophils kill exogenous pathogens before we focus on one particular weapon in their arsenal: the generation of the oxidizing hypohalous acids HOCl, HOBr and HOSCN during the so-called oxidative burst by the enzyme myeloperoxidase. We look at the effects of these hypohalous acids on biological systems in general and proteins in particular and turn our attention to bacterial strategies to survive HOCl stress. HOCl is a strong inducer of protein aggregation, which bacteria can counteract by chaperone-like holdases that bind unfolding proteins without the need for energy in the form of ATP. These chaperones are activated by HOCl through thiol oxidation (Hsp33) or N-chlorination of basic amino acid side-chains (RidA and CnoX) and contribute to bacterial survival during HOCl stress. However, neutrophil-generated hypohalous acids also affect the host system. Recent studies have shown that plasma proteins act not only as sinks for HOCl, but get actively transformed into modulators of the cellular immune response through N-chlorination. N-chlorinated serum albumin can prevent aggregation of proteins, stimulate immune cells, and act as a pro-survival factor for immune cells in the presence of cytotoxic antigens. Finally, we take a look at the emerging role of HOCl as a potential signaling molecule, particularly its role in neutrophil extracellular trap formation.

Hypochlorite-induced aggregation of fibrinogen underlies a novel antioxidant role in blood plasma

Fibrinogen, a major constituent of blood plasma, is highly susceptible to reaction with biological oxidants. It has been proposed that fibrinogen plays a role in antioxidant defence, but oxidation of fibrinogen is also known to disrupt normal blood clotting and is implicated in the pathology of atherosclerosis. In the present study, we show that the biological oxidant hypochlorite promotes the formation of soluble high molecular weight fibrinogen assemblies ≥40 × 10⁶ Da, that do not accumulate when fibrinogen is induced to aggregate by other stresses such as heating or hydroxyl-mediated damage in vitro. Hypochlorite-modified fibrinogen is stable at 37 °C as assessed by precipitation assays, and has reduced susceptibility to iron-induced (hydroxyl-mediated) precipitation compared to native fibrinogen. In contrast to hypochlorite-modified albumin, which is known to be immunostimulatory, hypochlorite-modified fibrinogen does not induce RAW 264.7 (macrophage-like) cells or EOC 13.31 (microglia-like) cells to produce reactive oxygen species or induce cell death. Furthermore, depletion of fibrinogen from human blood plasma increases the immunostimulatory property of blood plasma after it is supplemented with hypochlorite in situ. We propose that reaction of hypochlorite with fibrinogen in blood plasma potentially reduces the accumulation of other hypochlorite-modified species such as immunostimulatory hypochlorite-modified albumin. The latter represent a novel role for fibrinogen in blood plasma antioxidant defence.

Oxidative Stress in ESRD Patients on Dialysis and the Risk of Cardiovascular Diseases

Chronic kidney disease is highly prevalent worldwide. The decline of renal function is associated with inadequate removal of a variety of uremic toxins that exert detrimental effects on cells functioning, thus affecting the cardiovascular system. The occurrence of cardiovascular aberrations in CKD is related to the impact of traditional risk factors and non-traditional CKD-associated risk factors, including anemia; inflammation; oxidative stress; the presence of some uremic toxins; and factors related to the type, frequency of dialysis and the composition of dialysis fluid. Cardiovascular diseases are the most frequent cause for the deaths of patients with all stages of renal failure. The kidney is one of the vital sources of antioxidant enzymes, therefore, the impairment of this organ is associated with decreased levels of these enzymes as well as increased levels of pro-oxidants. Uremic toxins have been shown to play a vital role in the onset of oxidative stress. Hemodialysis itself also enhances oxidative stress. Elevated oxidative stress has been demonstrated to be strictly related to kidney and cardiac damage as it aggravates kidney dysfunction and induces cardiac hypertrophy. Antioxidant therapies may prove to be beneficial since they can decrease oxidative stress, reduce uremic cardiovascular toxicity and improve survival.

Using advanced oxidation protein products and ischaemia-modified albumin to monitor oxidative stress levels in patients with drug-induced liver injury

Increased oxidative stress levels play a key role in idiosyncratic drug-induced liver injury (DILI) pathogenesis. To investigated whether advanced oxidation protein products (AOPPs) and ischaemia-modified albumin (IMA) can be used to monitor oxidative stress in DILI patients and to assess disease severity. We performed spectrophotometric assays to assess AOPPs and IMA in 68 DILI patients with severity grade 0-2 (non-severe group), 60 with severity grade 3-5 (severe group), and 38 healthy controls. The results showed that baseline AOPPs and IMA serum levels and AOPPs/albumin and IMA/albumin ratios were significantly higher in DILI patients than in healthy controls. Besides, in comparison to the non-severe group, the severe group showed higher baseline AOPPs and IMA serum levels and AOPPs/albumin and IMA/albumin ratios. AOPPs and IMA serum levels and AOPPs/albumin and IMA/albumin ratios decreased after treatment in both patient groups. Combining the correlation analysis and areas under the receiver operating curve (AUROCs) analysis results, that IMA outperformed to be one is the most reliable marker to assess disease severity of DILI. Our findings indicated that AOPPs and IMA can serve as key biomarkers for monitoring oxidative stress levels in DILI patients and can indicate disease severity. The IMA outperformed to be one of the most reliable oxidative stress biomarkers to assess disease severity of DILI.

Redox regulation in host-pathogen interactions: thiol switches and beyond

Our organism is exposed to pathogens on a daily basis. Owing to this age-old interaction, both pathogen and host evolved strategies to cope with these encounters. Here, we focus on the consequences of the direct encounter of cells of the innate immune system with bacteria. First, we will discuss the bacterial strategies to counteract powerful reactive species. Our emphasis lies on the effects of hypochlorous acid (HOCl), arguably the most powerful oxidant produced inside the phagolysosome of professional phagocytes. We will highlight individual examples of proteins in gram-negative bacteria activated by HOCl via thiol-disulfide switches, methionine sulfoxidation, and N-chlorination of basic amino acid side chains. Second, we will discuss the effects of HOCl on proteins of the host. Recent studies have shown that both host and bacteria address failing protein homeostasis by activation of chaperone-like holdases through N-chlorination. After discussing the role of individual proteins in the HOCl-defense, we will turn our attention to the examination of effects on host and pathogen on a systemic level. Recent studies using genetically encoded redox probes and redox proteomics highlight differences in redox homeostasis in host and pathogen and give first hints at potential cellular HOCl signaling beyond thiol-disulfide switch mechanisms.

Local and Systemic Oxidative Stress in Balkan Endemic Nephropathy Is Not Associated with Xanthine Oxidase Activity

Balkan endemic nephropathy (BEN) represents a chronic tubulointerstitial nephropathy which is followed by the progression of kidney fibrosis to end-stage kidney failure. The critical involvement of poisons in food (aristolochic acid (AA), ochratoxin, and heavy metals) and selenium deficiency are among nutritive factors which contribute to the pathogenesis of BEN, due to reactive oxygen species (ROS) liberation and/or decreased antioxidative defence system. The aim of the study is to distinguish a possible systemic and local origin of ROS through the measurement of xanthine oxidase (XO) activity in urine and plasma, along with the determination of the oxidative changes in lipids and proteins. The study included 50 patients with BEN and 38 control healthy subjects. We noted increased levels of both thiobarbituric acid-reactive substances (TBARS) and advanced oxidation protein products (AOPPs) in the plasma of patients with BEN, compared to the control group (p < 0.001). The urinary levels of AOPPs were higher in patients with BEN in comparison to the control (p < 0.001). The specific activity of XO was significantly lower in plasma and urine in BEN samples, compared to controls (p < 0.005). Based on these results, we hypothesize that XO might not be considered a direct systemic or local contributor to ROS production in BEN, most probably because of the diminished kidney functional tissue mass and/or AA-induced changes in purine nucleotide conformation. The increased AOPP and TBARS level in both plasma and urine in BEN may predict ROS systemic liberation with toxic local effects.

Behaviour of carbonyl groups in several clinical conditions: Analysis of our survey

Protein carbonylation is a marker of oxidative protein damage, that is likely involved in the pathogenesis of several diseases. The aim of this study was to evaluate the protein carbonyl (PC) groups in different clinical conditions. It included different groups of subjects: 81 trained subjects; 23 subjects with mild essential hypertension; 31 middle-aged subjects with metabolic syndrome (MS); 106 subjects with MS not selected for age (subdivided into two subgroups, with and without diabetes mellitus); 91 obese adults subdivided in two subgroups (BMI 30-35 Kg/m2 and BMI > 35 kg/m2); 48 subjects with obstructive sleep apnea syndrome (OSAS) subdivided in accordance with the apnea/hypopnea index (AHI); 27 subjects with chronic kidney disease (CKD) on conservative therapy; 31 subjects with CKD on haemodialysis treatment; and 50 subjects with juvenile myocardial infarction. PC groups were reduced in trained subjects in comparison with sedentary controls, while no variation was observed in mild essential hypertension. PC groups were increased in MS subjects and in adult obese subjects. In MS subjects the PC groups were not influenced by the presence of diabetes mellitus and in adult obese subjects were not influenced by the obesity degree. In OSAS subjects only those with AHI > 30 showed an increase of PC groups. PC groups increased in CKD subjects undergoing conservative treatment and haemodialysis therapy. In dialyzed subjects, after a standard dialysis session, there was a marked increase in PC groups. In juvenile myocardial infarction PC groups were higher than in controls; there was no difference between STEMI and NSTEMI and their concentration was unaffected by the number of cardiovascular risk factors or stenosed coronary vessels.

The Oak-wood Extract Robuvit® Improves Recovery and Oxidative Stress after Hysterectomy: A Randomized, Double-blind, Placebo-controlled Pilot Study

Hysterectomy has a variety of medical indications and improves pre-operative symptoms but might compromise the quality of life during recovery due to symptoms such as fatigue, headache, nausea, depression, or pain. The aim of the present study was to determine the effect of a standardized extract from French oak wood (Quercus robur) containing at least 40% polyphenols of the ellagitannins class, Robuvit^®, on convalescence and oxidative stress of women after hysterectomy. Recovery status was monitored with the SF-36 questionnaire. The supplementation with Robuvit^® (300 mg/day) during 4 weeks significantly improved general and mental health, while under placebo some items significantly deteriorated. Oxidative stress and enhancement of MMP–9 activity was significantly reduced by Robuvit^® versus placebo. After 8 weeks of intervention, the patients’ condition improved independently of the intervention. Our results suggest that the use of Robuvit^® as a natural supplement relieves post-operative symptoms of patients after hysterectomy and reduces oxidative stress. The study was registered with ID ISRCTN 11457040 (13/09/2019).

Aggregation-enhanced emission enables phenothiazine coumarin as a robust ratiometric fluorescent for rapid and selective detection of HClO

By taking advantage of phenothiazine moiety as an electron-donating group, a novel donor-acceptor (D-A) type coumarin dye, PTZ-Et, was developed. The introduction of phenothiazine moiety not only caused emission red-shifting and Stokes shift enlarging, but also endowed PTZ-Et with significant aggregation-enhanced emission (AEE) features, thereby enabled PTZ-Et as a robust ratiometric fluorescent probe for HClO detection. Upon oxidation of the sulfur atom on phenothiazine into sulfoxide, PTZ-Et displayed remarkable ratiometric fluorescence response (over 150 folds variations of F₅₃₄/F₆₂₆) toward HClO with rapid response time (<30 s) and ultra-sensitivity (LOD = 15 nM). Additionally, the corresponding sensing mechanism of PTZ-Et for HClO was fully elucidated through the successful purification and well characterization (¹H NMR, ¹³C NMR, HRMS, and single crystal data) of the corresponding reaction product between PTZ-Et and HClO. Significantly, PTZ-Et was capable of monitoring both exogenous and endogenous HClO in living RAW 264.7 cells by ratiometric fluorescence imaging.

Advanced oxidation protein products in nondiabetic end stage renal disease patients on maintenance haemodialysis

In chronic kidney disease (CKD), the impairment of the excretory function leads to elevation in the blood concentrations of urea, creatinine, and various protein metabolic products. Advanced oxidation protein products (AOPP), along with protein carbonyls, protein-bound di-tyrosines and S-thiolated proteins, are considered biomarkers of oxidative stress in end-stage renal disease (ESRD) patients on maintenance haemodialysis (HD). In this study, we evaluated the correlations between plasma levels of AOPP (measured by size exclusion/gel filtration high performance liquid chromatography) and those of protein-bound di-tyrosines, protein carbonyls, albumin and fibrinogen in 50 nondiabetic ESRD patients on maintenance HD. Considering that AOPP could represent the bridge between oxidative stress and inflammation, having been identified as proinflammatory mediators, we also evaluated the association between AOPP levels, C-reactive protein concentration and white blood cells count. Finally, we assessed the associations between plasma level of AOPP and serum concentrations of creatinine and urea, both of which showed a strong dependence on the chronological age of haemodialysed patients. Taken together, our results confirm the robust relationship between uraemia and oxidative stress, especially when measured as biomarkers of severe protein oxidative damage (e.g. plasma AOPP).

Sumac (Rhus coriaria) for the prevention and treatment of necrotizing enterocolitis

Leukotrienes, free oxygen radicals, tumor necrosis factor-alpha, and inflammatory mediators play major roles in the development of necrotizing enterocolitis (NEC). Rhus coriaria (RC: sumac) extracts may enhance cell viability by reinforcing defenses against free radical species in several progressive diseases as well as inflammatory diseases. The aim of the present study was to evaluate the effects of RC in a rat NEC model in terms of intestinal damage. Newborn pups were separated into three groups: control, NEC, and NEC treated with RC. Mortality and clinical sickness scores were evaluated. At the end of the study, ileum and proximal colon were obtained from all rats and histopathological and immunohistochemical studies were performed. In this study, the anti-inflammatory, antioxidant, immunomodulatory, and anti-apoptotic activities of RC were demonstrated in a rat NEC model, which suggests RC as a promising treatment option for preventing intestinal tissue damage. PRACTICAL APPLICATIONS: Free oxygen radicals, tumor necrosis factor-alpha, and inflammatory mediators play major roles in the development of NEC. Intestinal tissue damage is caused by necrosis and apoptosis as a result of intestinal inflammation and release of pro-inflammatory cytokines. Anti-inflammatory, antioxidant, immunomodulatory, and anti-apoptotic activities of RC are especially due to its phenolic compounds. In this study, the anti-inflammatory, antioxidant, immunomodulatory, and anti-apoptotic activities of RC were demonstrated in a rat NEC model. RC can suggest as a new treatment option for preventing intestinal injury.

N-chlorination mediates protective and immunomodulatory effects of oxidized human plasma proteins

Hypochlorous acid (HOCl), a powerful antimicrobial oxidant, is produced by neutrophils to fight infections. Here, we show that N-chlorination, induced by HOCl concentrations encountered at sites of inflammation, converts blood plasma proteins into chaperone-like holdases that protect other proteins from aggregation. This chaperone-like conversion was reversible by antioxidants and was abrogated by prior methylation of basic amino acids. Furthermore, reversible N-chlorination of basic amino acid side chains is the major factor that converts plasma proteins into efficient activators of immune cells. Finally, HOCl-modified serum albumin was found to act as a pro-survival molecule that protects neutrophils from cell death induced by highly immunogenic foreign antigens. We propose that activation and enhanced persistence of neutrophils mediated by HOCl-modified plasma proteins, resulting in the increased and prolonged generation of ROS, including HOCl, constitutes a potentially detrimental positive feedback loop that can only be attenuated through the reversible nature of the modification involved.

Oxidative attack during temperature fluctuation challenge compromises liver protein homeostasis of a temperate fish model

Seasonal variations in water temperature are a natural stressor of temperate fish that affect growth performance and metabolism globally. Gilthead sea bream is one of the most economically interesting species in the Mediterranean; but its liver metabolism is affected by the cold season. However, the effects of cold on protein turnover mechanisms have hardly been studied. Here, we study the relationship between liver oxidative status and protein homeostasis pathways during a 50-day low temperature period at 14 °C, and subsequent recovery at two times: 7 days (early recovery) and 30 days (late recovery). Liver redox status was determined by measuring oxidised lipids and proteins, the glutathione redox cycle and major antioxidant enzymes activities. Protein turnover was analysed via liver protein expression of HSP70 and HSP90; proteasome 26S subunits and polyubiquitination, as markers of the ubiquitin-proteasome system (UPS); and cathepsin D, as a lysosomal protease. Low temperature exposure depressed antioxidant enzyme activities, affecting the glutathione redox cycle and reducing total glutathione levels. Both the UPS and lysosomal pathways were also depressed and consequently, oxidised protein accumulated in liver. Interestingly, both protein oxidation and polyubiquitination tagging depended on protein molecular weight. Despite all these alterations, temperature recovery reverted most consequences of the cold at different rates: with delayed recovery of total glutathione levels and oxidised protein degradation with respect to enzyme activities recovery. All these findings demonstrate that protein liver homeostasis is compromised after chronic cold exposure and could be the cause of liver affectations reported in aquaculture of temperate fish.

Advanced oxidation protein products play critical roles in liver diseases

There is a complex oxidant and antioxidant system that maintains the redox homoeostasis in the liver. While suffering from exogenous or endogenous risk factors, the balance between oxidants and antioxidants is disturbed and excessive reactive oxygen species are generated, resulting in oxidative stress. Oxidative stress is prevalent in various liver diseases and is thought to be involved in their pathophysiology. Advanced oxidation protein products are generated under conditions of oxidative damage and are newly described protein markers of oxidative stress. Previous studies have underscored the universal pathogenic roles of oxidation protein products in various diseases. However, investigations into how these products participate in the development of liver diseases have been superficial and insufficient. In this review, we highlight the current understanding of the roles of advanced oxidation protein products in liver disease pathogenesis and the underlying mechanisms. Moreover, we summarize the current studies on advanced oxidation protein products in infectious and noninfectious, acute and chronic liver diseases. Different strategies for targeting these advanced oxidation protein products and future perspectives, which may pave the way for developing new therapeutic strategies, will also be discussed here.

Antioxidant Supplementation in Renal Replacement Therapy Patients: Is There Evidence?

The disruption of balance between production of reactive oxygen species and antioxidant systems in favor of the oxidants is termed oxidative stress (OS). To counteract the damaging effects of prooxidant free radicals, all aerobic organisms have antioxidant defense mechanisms that are aimed at neutralizing the circulating oxidants and repair the resulting injuries. Antioxidants are either endogenous (the natural defense mechanisms produced by the human body) or exogenous, found in supplements and foods. OS is present at the early stages of chronic kidney disease, augments progressively with renal function deterioration, and is further exacerbated by renal replacement therapy. End-stage renal disease patients, on hemodialysis (HD) or peritoneal dialysis (PD), suffer from accelerated OS, which has been associated with increased risk for mortality and cardiovascular disease. During HD sessions, the bioincompatibility of dialyzers and dialysate trigger activation of white blood cells and formation of free radicals, while a significant loss of antioxidants is also present. In PD, the bioincompatibility of solutions, including high osmolality, elevated lactate levels, low pH, and accumulation of advanced glycation end-products trigger formation of prooxidants, while there is significant loss of vitamins in the ultrafiltrate. A number of exogenous antioxidants have been suggested to ameliorate OS in dialysis patients. Vitamins B, C, D, and E, coenzyme Q10, L-carnitine, a-lipoic acid, curcumin, green tea, flavonoids, polyphenols, omega-3 polyunsaturated fatty acids, statins, trace elements, and N-acetylcysteine have been studied as exogenous antioxidant supplements in both PD and HD patients.

Relationship between Protein Oxidation Biomarkers and Uterine Health in Dairy Cows during the Postpartum Period

High neutrophil (PMN, Polymorphonuclear neutrophil) counts in the endometrium of cows affected by endometritis, suggests the involvement of oxidative stress (OS) among the causes of impaired fertility. Protein oxidation, in particular, advanced oxidation protein products (AOPP), are OS biomarkers linked to PMN activity. To test this hypothesis, the relationship between protein oxidation and uterus health was studied in thirty-eight dairy cows during the puerperium. The animals were found to be cycling, without any signs of disease and pharmacological treatments. PMN count was performed either through a cytobrush or a uterine horn lavage (UHL). Cows were classified into four groups, based on the uterine ultrasonographic characteristics and the PMN percentage in the uterine horns with a higher percentage of high neutrophil horn (HNH). They were classified as: Healthy (H); Subclinical Endometritis (SCE); Grade 1 Endometritis (EM1); and Grade 2 Endometritis (EM2). AOPP and carbonyls were measured in plasma and UHL. UHL samples underwent Western blot analysis to visualize the carbonyl and dityrosine formation. Plasma AOPP were higher (p < 0.05) in EM2. AOPP and carbonyl group concentrations were higher in the HNH samples (p < 0.05). Protein concentration in the UHL was higher in the EM2 (p < 0.05). Carbonyl and dityrosine formation was more intense in EM1 and EM2. Protein oxidation observed in the EM2 suggests the presence of an inflammatory status in the uterus which, if not adequately hindered, could result in low fertility.

Therapeutic and preventative effects of ankaferd blood stopper in an experimental necrotizing enterocolitis model

Necrotizing enterocolitis (NEC) is a major neonatal health problem that especially affects preterm infants and causes severe morbidity and mortality. Although its pathogenesis is not fully understood, important risk factors include prematurity, oxidative stress, inflammation, and apoptosis. Ankaferd Blood Stopper® (ABS) has antioxidant, antiinflammatory, antimicrobial, antiapoptotic, and wound healing accelerant properties. In this study, we aimed to investigate whether treatment with ABS reduced the severity of NEC in rat pups in an experimental NEC model. Thirty-six newborn Wistar albino rat pups were randomly assigned to the control, NEC + saline, or NEC + ABS groups. NEC was induced by intraperitoneal injection of lipopolysaccharide, feeding with hyperosmolar enteral formula, and exposure to hypoxia/hyperoxia and cold stress. ABS was administered intraperitoneally to the pups in the NEC + ABS group daily starting on day 1 of the study at a dose of 2 ml/kg by diluting 2 ml with saline at a ratio of 1:3. All pups were sacrificed on day 4. The terminal ileum including the proximal colon was removed for histopathological and immunohistochemical examination and biochemical analysis. Macroscopic assessment and intestinal injury scores were lower in NEC + ABS group compared to the NEC + saline group (p < 0.05). Immunohistochemical evaluations of caspase-3, -8, and -9 revealed significantly reduced apoptosis in the NEC + ABS group compared to the NEC + saline group (p = 0.001). Total oxidant status, oxidative stress index, tumor necrosis factor α and interleukin-1β levels, and lipid, protein, and deoxyribonucleic acid oxidation products were significantly lower in the NEC + ABS group compared to NEC + saline group (p < 0.001 for all), while total antioxidant status, glutathione, and superoxide dismutase levels were higher in the NEC + ABS group (p < 0.001, p < 0.001, p = 0.01, respectively). ABS treatment has the potential to effectively reduce the severity of intestinal damage in NEC due to its antioxidant, antiinflammatory, and antiapoptotic properties. Therefore, NEC may be an alternative option for treatment.

A Fluorescent Cy7-Mercaptopyridine for the Selective Detection of Glutathione over Homocysteine and Cysteine

We describe a near-infrared (NIR) fluorescent probe 1 for the selective detection of GSH over Hcy and Cys under physiological conditions. Probe 1 was composed of Cy7 as a NIR dye and 2-mercaptopyridine as a GSH-reactive site and fluorescence quencher. In the presence of GSH, the 2-mercaptopyridine functionality of probe 1 was replaced by the thiolate group of GSH through a nucleophilic substitution reaction with a fluorescence increase at 818 nm. The probe was found to be highly selective for GSH over Hcy, Cys, and other tested potential interferants, including ROS and metal ions. In addition, probe 1 successfully displayed fluorescence changes in response to changing the GSH concentrations in MDA-MB-231 cells in the presence of external agents i.e., N-acetyl-l-cysteine (NAC; as GSH inducer) or buthionine sulfoximine (BSO; as GSH inhibitor). We envision that probe 1 will serve as a promising sensing tool for monitoring the changes of the GSH level and the understanding of the roles of GSH under physiological and pathological conditions.

Redox Challenge in a Cultured Temperate Marine Species During Low Temperature and Temperature Recovery

Aquaculture is a growing industry that is increasingly providing a sizable proportion of fishery products for human consumption. Dietary energy and temperature fluctuations affect fish health and may even trigger mortality, causing great losses in fish production during winter. To better understand this unproductive winter period in aquaculture, the redox status in a cultured marine species, the gilthead sea bream, was analyzed for the first time by inducing controlled temperature fluctuations and reducing dietary lipid content. Two groups of fish (by triplicate), differing in their dietary lipid content (18% vs. 14%), were subjected to 30 days at 22°C (Pre-Cold), 50 days at 14°C (Cold) and then 35 days at 22°C (Recovery). Plasma and liver redox metabolites (oxidized lipid, oxidized protein and thiol groups), liver glutathione forms (total, oxidized and reduced) and liver antioxidant enzyme activities were measured. Reducing dietary lipid content did not affect gilthead sea bream growth, glutathione levels or enzyme activities, but did reduce the amount of oxidized lipids. A sustained low temperature of 14°C showed a lack of adaptation of antioxidant enzyme activities, mainly catalase and glutathione reductase, which subsequently affected the glutathione redox cycle and caused an acute reduction in total hepatic glutathione levels, irrespective of diet. Antioxidant enzyme activities were gradually restored to their pre-cold levels, but the glutathione redox cycle was not restored to its pre-cold values during the recovery period used. Moreover, the lower lipid diet was associated with transiently increased liver oxidized protein levels. Thus, we propose that fish should be fed a low lipid diet during pre-cold and cold periods, which would reduce oxidized lipid levels without affecting fish growth, and a higher energy diet during the recovery period. Moreover, diets supplemented with antioxidants should be considered, especially during temperature recovery.

Preconditioning-Like Properties of Short-Term Hypothermia in Isolated Perfused Rat Liver (IPRL) System

Hypothermia may attenuate the progression of ischemia-induced damage in liver. Here, we determined the effects of a brief cycle of hypothermic preconditioning applied before an ischemic/reperfusion (I/R) episode in isolated perfused rat liver (IPRL) on tissue damage and oxidative stress. Rats (male, 200–250 g) were anaesthetised with sodium pentobarbital (60 mg·kg⁻¹ i.p) and underwent laparatomy. The liver was removed and perfused in a temperature-regulated non-recirculating system. Livers were randomly divided into two groups (n = 6 each group). In the hypothermia-preconditioned group, livers were perfused with hypothermic buffer (cycle of 10 min at 22 °C plus 10 min at 37 °C) and the other group was perfused at 37 °C. Both groups were then submitted to 40 min of warm ischemia and 20 min of warm reperfusion. The level of tissue-damage indicators (alanine amino transferase, ALT; lactate dehydrogenase, LDH; and proteins), oxidative stress markers (thiobarbituric acid-reactive substances, TBARS; advanced oxidation protein products, AOPP; and glutathione, GSH) were measured in aliquots of perfusate sampled at different time intervals. Histological determinations and oxidative stress biomarkers in homogenized liver (AOPP; TBARS; nitric oxide derivatives, NO_x; GSH and glutathione disulphide, GSSG) were also made in the tissue at the end. Results showed that both damage and oxidant indicators significantly decreased while antioxidant increased in hypothermic preconditioned livers. In addition, homogenized liver determinations and histological observations at the end of the protocol corroborate the results in the perfusate, confirming the utility of the perfusate as a non-invasive method. In conclusion, hypothermic preconditioning attenuates oxidative damage and appears to be a promising strategy to protect the liver against IR injury.

Advanced oxidation protein products induce chondrocyte death through a redox-dependent, poly (ADP-ribose) polymerase-1-mediated pathway

This study aimed to investigate the effect of AOPPs on apoptosis in human chondrocytes. Chondrocytes were treated with AOPPs. Cell death, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity, reactive oxygen species (ROS) generation, and the expression of apoptotic proteins were detected in vitro. AOPPs levels were detected by colorimetric method. The results in vitro demonstrated that AOPPs induced cell death in human chondrocyte through a redox-dependent pathway, including RAGE-mediated, NADPH oxidase-dependent ROS generation, and poly (ADP-ribose) polymerase-1 (PARP-1) activation. Targeting AOPPs-induced cellular mechanisms might emerge as a promising therapeutic option for patients with RA.

Oxidation of factor VIII increases its immunogenicity in mice with severe hemophilia A

The development of antibodies against therapeutic factor VIII (FVIII) represents the major complication of replacement therapy in patients with severe hemophilia A. Amongst the environmental risk factors that influence the anti-FVIII immune response, the presence of active bleeding or hemarthrosis has been evoked. Endothelium damage is typically associated with the release of oxidative compounds. Here, we addressed whether oxidation contributes to FVIII immunogenicity. The control with N-acetyl cysteine of the oxidative status in FVIII-deficient mice, a model of severe hemophilia A, reduced the immune response to exogenous FVIII. Ex vivo exposure of therapeutic FVIII to HOCl induced a mild oxidation of the molecule as evidenced by the loss of free amines and resulted in increased FVIII immunogenicity in vivo when compared to native FVIII. The increased immunogenicity of oxidized FVIII was not reverted by treatment of mice with N-acetyl cysteine, and did not implicate an increased maturation of professional antigen-presenting cells. Our data document that oxidation influences the immunogenicity of therapeutic FVIII.

Evaluation of Neuropathological Effects of a High-Fat Diet in a Presymptomatic Alzheimer's Disease Stage in APP/PS1 Mice

Alzheimer's disease (AD) is currently an incurable aging-related neurodegenerative disorder. Recent studies give support to the hypotheses that AD should be considered as a metabolic disease. The present study aimed to explore the relationship between hippocampal neuropathological amyloid-β (Aβ) plaque formation and obesity at an early presymptomatic disease stage (3 months of age). For this purpose, we used APPswe/PS1dE9 (APP/PS1) transgenic mice, fed with a high-fat diet (HFD) in order to investigate the potential molecular mechanisms involved in both disorders. The results showed that the hippocampus from APP/PS1 mice fed with a HFD had an early significant decrease in Aβ signaling pathway specifically in the insulin degrading enzyme protein levels, an enzyme involved in (Aβ) metabolism, and α-secretase. These changes were accompanied by a significant increase in the occurrence of plaques in the hippocampus of these mice. Furthermore, APP/PS1 mice showed a significant hippocampal decrease in PGC-1α levels, a cofactor involved in mitochondrial biogenesis. However, HFD does not provoke changes in neither insulin receptors gene expression nor enzymes involved in the signaling pathway. Moreover, there are no changes in any enzymes (kinases) involved in tau phosphorylation, such as CDK5, and neither in brain oxidative stress production. These results suggest that early changes in brains of APP/PS1 mice fed with a HFD are mediated by an increase in Aβ1 ‒ 42, which induces a decrease in PKA levels and alterations in the p-CREB/ NMDA2B /PGC1-α pathway, favoring early AD neuropathology in mice.

Biochemical and Clinical Impact of Organic Uremic Retention Solutes: A Comprehensive Update

In this narrative review, the biological/biochemical impact (toxicity) of a large array of known individual uremic retention solutes and groups of solutes is summarized. We classified these compounds along their physico-chemical characteristics as small water-soluble compounds or groups, protein bound compounds and middle molecules. All but one solute (glomerulopressin) affected at least one mechanism with the potential to contribute to the uremic syndrome. In general, several mechanisms were influenced for each individual solute or group of solutes, with some impacting up to 7 different biological systems of the 11 considered. The inflammatory, cardio-vascular and fibrogenic systems were those most frequently affected and they are one by one major actors in the high morbidity and mortality of CKD but also the mechanisms that have most frequently been studied. A scoring system was built with the intention to classify the reviewed compounds according to the experimental evidence of their toxicity (number of systems affected) and overall experimental and clinical evidence. Among the highest globally scoring solutes were 3 small water-soluble compounds [asymmetric dimethylarginine (ADMA); trimethylamine-N-oxide (TMAO); uric acid], 6 protein bound compounds or groups of protein bound compounds [advanced glycation end products (AGEs); p-cresyl sulfate; indoxyl sulfate; indole acetic acid; the kynurenines; phenyl acetic acid;] and 3 middle molecules [β₂-microglobulin; ghrelin; parathyroid hormone). In general, more experimental data were provided for the protein bound molecules but for almost half of them clinical evidence was missing in spite of robust experimental data. The picture emanating is one of a complex disorder, where multiple factors contribute to a multisystem complication profile, so that it seems of not much use to pursue a decrease of concentration of a single compound.