Advanced oxidation protein products attenuate the autophagy-lysosome pathway in ovarian granulosa cells by modulating the ROS-dependent mTOR-TFEB pathway.

Oxidative stress dysfunction has recently been found to be involved in the pathogenesis of premature ovarian insufficiency (POI). Previously, we found that advanced oxidation protein products (AOPPs) in plasma were elevated in women with POI and had an adverse effect on granulosa cell proliferation. However, the mechanism underlying the effects of AOPPs on autophagy-lysosome pathway regulation in granulosa cells remains unclear. In this study, the effect of AOPPs on autophagy and lysosomal biogenesis and the underlying mechanisms were explored by a series of in vitro experiments in KGN and COV434 cell lines. AOPP-treated rat models were employed to determine the negative effect of AOPPs on the autophagy-lysosome systems in vivo. We found that increased AOPP levels activated the mammalian target of rapamycin (mTOR) pathway, and inhibited the autophagic response and lysosomal biogenesis in KGN and COV434 cells. Furthermore, scavenging of reactive oxygen species (ROS) with N-acetylcysteine and blockade of the mTOR pathway with rapamycin or via starvation alleviated the AOPP-induced inhibitory effects on autophagy and lysosomal biogenesis, suggesting that these effects of AOPPs are ROS-mTOR dependent. The protein expression and nuclear translocation of transcription factor EB (TFEB), the key regulator of lysosomal and autophagic function, were also impaired by the AOPP-activated ROS-mTOR pathway. In addition, TFEB overexpression attenuated the AOPP-induced impairment of autophagic flux and lysosomal biogenesis in KGN and COV434 cells. Chronic AOPP stimulation in vivo also impaired autophagy and lysosomal biogenesis in granulosa cells of rat ovaries. The results highlight that AOPPs lead to impairment of autophagic flux and lysosomal biogenesis via ROS-mTOR-TFEB signaling in granulosa cells and participate in the pathogenesis of POI.

CGAs-Rich Conilon Coffee Consumption Improves Cognition and Reduces Oxidative Stress in Elderly with Alzheimer's Disease: A Pilot Study.

BACKGROUND: The consumption of coffee has been associated with beneficial effects when it comes to Alzheimer's disease (AD). However, to the best of our knowledge, there are no studies on Conilon coffee consumption in elderly people with AD. OBJECTIVE: Evaluate the effects of Conilon coffee consumption in elderly with AD. METHODS: The study was carried out with 9 participants who consumed a minimum of 2 cups (200 mL cup) of Conilon coffee per day for 90 days. Cognitive assessment was done before (T0) and after 90 days (T90). Blood analysis was conducted at T0 and T90, as well as the assessment of advanced oxidation protein products (AOPP) and thiobarbituric acid reactive species (TBARS). The levels of chlorogenic acids and caffeine in the coffee beverage were quantified by liquid chromatography. RESULTS: During the treatment, the participants consumed at least 550 mg and 540 mg of CGAs and caffeine, respectively. A significant improvement in cognition between T0 and T90 was observed as per MMSE, CTP, and clock drawing tests. Furthermore, there was a significant reduction in AOPP (37%) and TBARS (60%), indicating a reduction in oxidative stress. The consumption of the coffee did not significantly alter any blood parameter, which confirms the safety of the coffee treatment during the 90 days. CONCLUSIONS: Our study demonstrated for the first time that regular consumption of coffee with high amounts of CGAs and caffeine improves cognitive functions and reduces oxidative stress, without altering blood parameters that indicate possible signs of toxicity in classical target organs.

The effect of aerobic exercise on oxidative stress in patients with chronic kidney disease: a systematic review and meta-analysis with trial sequential analysis.

PURPOSE: The purpose of this study was to investigate how aerobic exercise affects oxidative stress (OS) in patients with chronic kidney disease (CKD). METHODS: Retrieval dates range from the date the database was established to 19 July 2023, without languages being restricted. A meta-analysis and sensitivity analysis were conducted using RevMan 5.3 and Stata 16.0. RESULTS: The meta-analysis showed that, compared to usual activity or no exercise, aerobic exercise significantly reduced the oxidative markers malondialdehyde (MDA) (mean differences (MD) - 0.96 (95% CI -1.33, - 0.59); p < 0.00001), advanced oxidation protein product (AOPP) (MD - 3.49 (95% CI - 5.05, - 1.93); p < 0.00001), F2-isoprostanes (F2-iso) (MD - 11.02 (95% CI - 17.79, - 4.25); p = 0.001). Aerobic exercise also increased the antioxidant marker superoxide dismutase (SOD) in CKD patients (standardized mean differences (SMD) 1.30 (95% CI 0.56, 2.04); p = 0.0005). Subgroup analysis showed a significant increase in glutathione peroxidase (GPX) in patients aged ≥60 years (SMD 2.11 (95% CI 1.69, 2.54); p < 0.00001). The change in total antioxidant capacity (TAC) after aerobic exercise was insignificant in patients with CKD. The trial sequential analysis supported aerobic exercise's effectiveness in improving MDA, SOD, AOPP, and F2-iso in patients with CKD. CONCLUSION: The results of this review suggest that aerobic exercise improves OS indicators (MDA, SOD, AOPP, and F2-iso) in CKD patients compared to conventional treatment or no exercise and that the effects on GPX and TAC indicators need further confirmation. For better validation of benefits and exploration of the best aerobic exercise regimen to improve OS status with CKD, further studies with high methodological quality and large sample sizes are needed.

Oxidative stress status assessment of rats' brains injury following subacute exposure to K-oximes.

Oxidative stress status and morphological injuries in the brain of Wistar rats induced by repeated application of selected acetylcholinesterase reactivators - asoxime, obidoxime, K027, K048, K074, and K075 were evaluated. Each oxime in a dose of 0.1 of LD50/kg im was given 2x/week for 4 weeks. Markers of lipid peroxidation (malondialdehyde, MDA), and protein oxidation (advanced oxidation protein products, AOPP), as well as the activity of antioxidant enzymes (catalase, CAT, superoxide dismutase, SOD, glutathione reductase, GR, and glutathione peroxidase, GPx), were estimated in the brain tissue homogenates on day 35 of the study. Brain alterations were carefully quantified by semiquantitative grading scales - brain damage score (BDS). Oxidative stress parameters, MDA and AOPP were significantly highest in the asoxime-, obidoxime- and K075-treated groups (p < 0.001). The activity of SOD and CAT was significantly elevated in the obidoxime-, K048-, and K075-treated groups (p < 0.001). Besides, GR was markedly decreased in the obidoxime- and K074-treated groups (p < 0.01), while treatment with K048, K074 and K075 induced extremely high elevation in GPx levels (p < 0.001). In the same groups of rats, brain alterations associated with polymorphonuclear cell infiltrate were significantly more severe than those observed in animals receiving only asoxime or K027 (p < 0.001). The presented results confirmed that treatment with different oximes significantly improved the oxidative status and attenuated signs of inflammation in rats' brains. Presented results, together with our previously published data can help to predict likely adverse systemic toxic effects, and target organ systems, which are crucial for establishing risk categories, as well as in dose selection of K-oximes as drug candidates.

Increased levels of lipid and protein oxidation in rat prefrontal cortex after treatment by lithium, valproic acid, and olanzapine.

Oxidative stress is widely accepted to contribute to the pathogenesis of several psychiatric diseases. Many antipsychotic drugs and mood stabilizers act through restoration of the dysregulated oxidative homeostasis in the brain. However, the long-term effect of these drugs per se in terms of their potential to interfere with the oxidative status in the brain remains largely controversial. The present study aimed to investigate the sole effect of three commonly used psychoactive drugs, lithium, valproic acid, and olanzapine, on lipid and protein oxidation status in the prefrontal cortex of healthy rats. A total of 80 adult male albino Wistar rats were used, and groups were treated with saline (control), lithium, valproic acid, or olanzapine daily for 30 days. Following sacrification, right prefrontal cortexes were dissected and homogenized. Lipid peroxidation (LPO) and protein oxidation (AOPP) assays were performed by ELISA. LPO levels were significantly higher in lithium and valproic acid-treated rats by 45% and 40%, respectively. Olanzapine treatment caused a mild 26% increase in LPO levels, but the effect was non-significant. Lithium, valproic acid, and olanzapine treatments significantly increased AOPP levels by 58%, 54%, and 36.5%, respectively. There was a strong positive correlation between the lipid peroxidation and protein oxidation levels. Our results call attention to the need to consider the pro-oxidative capacity of antipsychotic drugs per se and their potential to disturb the oxidative homeostasis in the brain during long-term medication for psychiatric diseases.

Impact of Vitamin D3 on Carbonyl-Oxidative Stress and Matrix Metalloproteinases after Acute Intracerebral Hemorrhage in Rats with Type 2 Diabetes Mellitus.

INTRODUCTION: Diabetes mellitus is associated with the development of carbonyl-oxidative stress (COS) and an increased risk of a cerebral hemorrhage. Vitamin D3 is considered an additional drug to have an impact on COS and proteolysis in the extracellular matrix. OBJECTIVE: The study aimed to evaluate the impact of D3 on the COS-markers and matrix metalloproteinases MMP2/MMP9 activity after acute intracerebral hemorrhage (ICH) in rats with experimental type 2 diabetes mellitus (Т2DM) compared to metformin (Met). METHODS: T2DM was induced in rats via the intraperitoneal injection of streptozotocin (STZ) and nicotinamide (NA), ICH - by microinjection of bacterial collagenase into the striatum. Rats were randomized into five groups: 1 - intact animals (n = 8), 2 - T2DM (n = 9); 3 - T2DM+ICH (n = 7); 4 - T2DM+ICH+Met (n = 7); 5 - T2DM+ICH+D3 (n = 7). Blood glucose, glycated hemoglobin, and oral glucose tolerance test (OGTT) were assessed using commercial kits. Advanced oxidation protein products (AOPP), protein carbonyls (PC370/430), and ischemia-modified albumin (IMA) were measured by spectrophotometry, advanced glycation end products (AGEs) by quantitative fluorescence, and matrix metalloproteinases MMP2/9 by gelatin zymography. RESULTS: D3 does not significantly affect the glucose level and OGTT in rats with T2DM+ICH. However, it reduces AOPP, PC, and AGEs, thus reducing the COS index. In contrast, the activity of proMMP9 increases after D3 administration. These effects of D3 have been reported to be stronger and sometimes opposite to those of metformin. CONCLUSION: D3 supplementation may decrease the negative consequences of a cerebral hemorrhage in T2DM by reducing COS and preventing the accumulation of COS-modified proteins in the brain by regulating the expression and activity of MMP9.

Investigation Covering the Effect of Boron plus Taurine Application on Protein Carbonyl and Advanced Oxidation Protein Products Levels in Experimental Alzheimer Model.

Alzheimer's disease (AD) is the most common form of dementia that occurs in the brain. This is a chronic neurodegenerative disease which is valid in 60-70% of all dementia patients. Boron, regarded as a potential antioxidant, has the effect of reducing oxidative stress. Taurine, as one of the thiol-containing amino acids, exists at different concentrations in both the neurons and glial cells of the central nervous system. It plays an important role in the protective and adjuvant therapies as an antioxidant due to its characteristics of maintaining the oxidant-antioxidant balance of the body as well as cell integrity and increasing body resistance. Based on this information, our objective was to reveal the effect of boron alone, taurine alone plus co-administration of taurine and boron application on brain tissue protein carbonyls (PC) and serum advanced oxidation protein products (AOPP) levels in the experimental Alzheimer's model. For this purpose, 5 groups were formed in our study which consisted of 30 Wistar albino male rats. The rats were given a single dose of STZ stereotaxically. At the end of this period, the rats were decapitated, plus their brain tissues and blood were removed. Our findings suggested that taurine alone and co-administration of boron and taurine had a decreasing effect on AOPP and PC levels of the experimental Alzheimer model of the rats.

Abscisic Acid Mediates Salicylic Acid Induced Chilling Tolerance of Grafted Cucumber by Activating H2O2 Biosynthesis and Accumulation.

Grafting is widely applied to enhance the tolerance of some vegetables to biotic and abiotic stress. Salicylic acid (SA) is known to be involved in grafting-induced chilling tolerance in cucumber. Here, we revealed that grafting with pumpkin (Cucurbita moschata, Cm) as a rootstock improved chilling tolerance and increased the accumulation of SA, abscisic acid (ABA) and hydrogen peroxide (H2O2) in grafted cucumber (Cucumis sativus/Cucurbita moschata, Cs/Cm) leaves. Exogenous SA improved the chilling tolerance and increased the accumulation of ABA and H2O2 and the mRNA abundances of CBF1, COR47, NCED, and RBOH1. However, 2-aminoindan-2-phosphonic acid (AIP) and L-a-aminooxy-b-phenylpropionic acid (AOPP) (biosynthesis inhibitors of SA) reduced grafting-induced chilling tolerance, as well as the synthesis of ABA and H2O2, in cucumber leaves. ABA significantly increased endogenous H2O2 production and the resistance to chilling stress, as proven by the lower electrolyte leakage (EL) and chilling injury index (CI). However, application of the ABA biosynthesis inhibitors sodium tungstate (Na2WO4) and fluridone (Flu) abolished grafting or SA-induced H2O2 accumulation and chilling tolerance. SA-induced plant response to chilling stress was also eliminated by N,N'-dimethylthiourea (DMTU, an H2O2 scavenger). In addition, ABA-induced chilling tolerance was attenuated by DMTU and diphenyleneiodonium (DPI, an H2O2 inhibitor) chloride, but AIP and AOPP had little effect on the ABA-induced mitigation of chilling stress. Na2WO4 and Flu diminished grafting- or SA-induced H2O2 biosynthesis, but DMTU and DPI did not affect ABA production induced by SA under chilling stress. These results suggest that SA participated in grafting-induced chilling tolerance by stimulating the biosynthesis of ABA and H2O2. H2O2, as a downstream signaler of ABA, mediates SA-induced chilling tolerance in grafted cucumber plants.

Assessment of Mancozeb Exposure, Absorbed Dose, and Oxidative Damage in Greenhouse Farmers.

Mancozeb (MNZ) is a fungicide commonly employed in many countries worldwide. This study assesses MNZ absorption dynamics in 19 greenhouse farmers, specifically following dermal exposure, aiming to verify the efficacy of both preventive actions and protective equipment. For data collection, a multi-assessment approach was used, which included a survey to record study population features. MNZ exposure was assessed through the indirect measurement of ethylene thiourea (ETU), widely employed as an MNZ biomarker. The ETU concentration was measured with the patch method, detecting environmental ETU trapped in filter paper pads, applied both on skin and working clothes, during the 8 h work shift. Urine and serum end-of-shift samples were also collected to measure ETU concentrations and well-known oxidative stress biomarkers, respectively, namely reactive oxygen metabolites (ROMs), advanced oxidation protein products (AOPPs), and biological antioxidant potential (BAP). It was observed that levels of ETU absorbed and ETU excreted were positively correlated. Additionally, working clothes effectively protected workers from MNZ exposure. Moreover, following stratification of the samples based on the specific working duty (i.e., preparation and spreading of MNZ and manipulation of MNZ-treated seedlings), it was found that the spreading group had higher ETU-related risk, despite lower chronic exposure levels. AOPP and ROM serum levels were higher in MNZ-exposed subjects compared with non-exposed controls, whereas BAP levels were significantly lower. Such results support an increase in the oxidative stress upon 8 h MNZ exposure at work. In particular, AOPP levels demonstrated a potential predictive role, as suggested by the contingency analysis results. Overall, this study, although conducted in a small group, confirms that ETU detection in pads, as well as in urine, might enable assessment of the risk associated with MNZ exposure in greenhouse workers. Additionally, the measurement of circulating oxidative stress biomarkers might help to stratify exposed workers based on their sensitivity to MNZ. Pivotally, the combination of both ETU measurement and biological monitoring might represent a novel valuable combined approach for risk assessment in farmhouse workers exposed to pesticides. In the future, these observations will help to implement effective preventive strategies in the workplace for workers at higher risk, including greenhouse farmers who are exposed to pesticides daily, as well as to clarify the occupational exposure levels to ETU.

Impacts of engineered iron nanoparticles on oxidative stress, fatty acid composition, and histo-architecture of the smooth scallop Flexopecten glaber.

Engineered iron nanoparticles are widely used in environmental remediation, yet their potential toxic effects on marine biota remain poorly elucidated. This study aimed to gain insight into the nanoscale zero-valent iron (NZVI) toxicity mechanisms for marine invertebrates. Aside from the effect on oxidative status and histopathology, the effect of NZVI on lipid metabolism in bivalves was studied for the first time. To this end, specimens of Flexopecten glaber were exposed to ascending concentrations (0.5, 1, and 1.5 mg/L) of NZVI for 96 h. Results illustrate differential patterns of iron accumulation in the gills and the digestive gland. By increasing NZVI concentrations, the total iron level tended to markedly increase in the gills and decrease in the digestive gland, reaching 132 and 37.6 µg/g DW, respectively, in the specimens exposed to 1.5 mg/L. Biochemical and cellular biomarkers highlighted that NZVI caused oxidative stress (measured as hydrogen peroxide, malondialdehyde, and advanced oxidation protein product levels) and alterations of antioxidant defense systems, including reduced glutathione, non-protein thiol, glutathione peroxidase, superoxide dismutase, and catalase. Modulation of lipid metabolism with changed fatty acid compositions (mainly an increase in the saturation and a decrease in unsaturation levels) was also observed in both gills and digestive gland. Moreover, several histological damages, including lipofuscin accumulation, infiltrative inflammations, and digestive tubule alterations, were observed in the two studied organs, providing supplementary evidence regarding the toxic effect of NZVI. This study adds to the growing body of evidence pointing to the hazardous impacts of iron NPs on aquatic ecosystems.

The Comparative Effects of Inulin and Bacillus clausii on LPS-Induced Endotoxemic Rat Liver.

BACKGROUND: This paper sought to investigate the modifies of inulin and Bacillus clausii on the lipopolysaccharides (LPS) inducing oxidative stress signaling pathway in the endotoxemic rat model. METHODS: Wistar albino male rats (n = 36), divided into six groups, were formed randomly in the following stages: the control group; the prebiotic group (Inulin; 500 mg/kg); the probiotic group (Bacillus clausii; 1x109 CFU); the LPS group (1.5 mg/kg) as the endotoxemic model; the prebiotic group + LPS; and the probiotic group + LPS as treatment groups. RESULTS: The reactive oxygen species (ROS), advanced oxidation products of protein (AOPP), thiobarbituric acid reactive substances (TBARS), total oxidant status (TOS), oxidative stress index (OSI), and myeloperoxidase activity (MPO) levels increased in LPS-induced toxicity. Prebiotic treatment decreased LPS-induced hepatotoxicity on rat liver as observed in the decrease in the levels of oxidative stress parameters, such as ROS, TBARS, TOS, and OSI. The effect of the probiotic treatment on the ROS, AOPP, TOS, OSI levels was not statistically significant. However, it was determined that probiotic application was effective in the TBARS, TAS, and GSH levels. When the biochemical results of the prebiotic and probiotic treatment applications were compared, it was found that the prebiotic treatment was more effective on oxidative stress parameters (ROS, TBARS, TOS, and OSI). In addition, the histological damage score and MPO-staining results of the prebiotic treatment group were found to be more effective than the probiotic group. CONCLUSION: In this first study, where inulin and Bacillus clausii spores are used against liver damage caused by LPS, inulin provides much more effective protection than Bacillus clausii spores.

Examination of the effect of curcumin in experimental liver damage created by diethylnitrosamine in Swiss albino mice to superoxide dismutase and catalase activities and glutathione, malondialdehyde, and advanced oxidation protein products levels.

In this study, the effects of curcumin, glutathione (GSH), malondialdehyde (MDA) levels, advanced protein oxidation products (AOPP), superoxide dismutase (SOD), and catalase (CAT) activities in experimental liver damage with diethylnitrosamine (DEN) in Swiss albino mice were investigated. The subjects (n = 9) used in the study were divided into 5 groups as tumor control 1, tumor control 2, curcumin protective, curcumin treatment and healthy control groups Curcumin oral gavage (in 150 mg/kg of ethylalcohol) was given to the protecting group for 19 days, 5 days before the administration of DEN, and 24 h after the administration of DEN. Hundred microliters of ethylalcohol oral gavage was given to the healthy group for 19 days. While MDA levels decreased significantly in the curcumin preservative group (p < 0.05), (p = 0.002), the decrease was not significant in the treatment groups (p > 0.05), (p = 0.128). AOPP levels decreased significantly in the curcumin protective group (p < 0.05), (p = 0.009) but the decrease in the treatment group was not found significant (p > 0.05), (p = 0.073). SOD activities increased significantly in both groups. It was found as (p < 0.05), (p = 0.001) and (p < 0.05), (p = 0.002), respectively. GSH levels decreased but these reductions were not found statistically significant. CAT activities increased significantly in both groups. It was determined as (p < 0.05), (p = 0.001) for both groups.

Age-related accumulation of advanced oxidation protein products promotes osteoclastogenesis through disruption of redox homeostasis.

Enhanced osteoclastogenesis is one of the major causes of age-related bone loss. Aging is accompanied by accumulation of advanced oxidation protein products (AOPPs). However, whether AOPPs accumulation contributing to the osteoclastogenesis with aging remains unclear. Here, we showed that AOPPs accumulation was associated with the enhanced osteoclastogenesis and deterioration of bone microstructure in aged mice. In vitro, AOPPs directly induced osteoclastogenesis by interaction with receptor activator of nuclear factor κ B (RANK) and the receptor for advanced glycation end products (RAGE) in the primary bone marrow monocytes. Bindings of AOPPs to RANK and RAGE were able to activate nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, trigger generation of reactive oxygen species, then induce phosphorylation of mitogen-activated protein kinases and c-fos, upregulation of the nuclear factor of activated T cell c1, eventually induce bone marrow monocytes to differentiate into mature osteoclasts. Chronic exposure to AOPPs enhanced osteoclastogenesis and bone loss in mice, which could be alleviated by NADPH oxidase inhibitor apocynin. Local injection of AOPPs into subperiosteal area induced bone resorption at the site of administration, which was similar to the effect of RANK ligand. Together, these results suggested that AOPPs could serve as a novel regulator of osteoclastogenesis and AOPPs accumulation might play an important role in the development of age-related bone loss.

Advanced oxidation protein products downregulate CYP1A2 and CYP3A4 expression and activity via the NF-κB-mediated signaling pathway in vitro and in vivo.

Uremic toxin accumulation is one possible reason for alterations in hepatic drug metabolism in patients with chronic kidney disease (CKD). However, the types of uremic toxins and underlying mechanisms are poorly understood. In this study, we report the role of advanced oxidation protein products (AOPPs), a modified protein uremic toxin, in the downregulation of cytochromes P450 1A2 (CYP1A2) and P450 3A4 (CYP3A4) expression levels and activities. We found that AOPP accumulation in plasma in a rat CKD model was associated with decreased protein levels of CYP1A2 and CYP3A4. CYP1A2 and CYP3A4 metabolites (acetaminophen and 6ß-hydroxytestosterone, respectively,) in liver microsomes were also significantly decreased. In human hepatocytes, AOPPs significantly decreased CYP1A2 and CYP3A4 protein levels in a dose- and time-dependent manner and downregulated their activities; however, bovine serum albumin (BSA), a synthetic precursor of AOPPs, had no effect on these parameters. The effect of AOPPs was associated with upregulation of p-IKKα/ß, p-IκBα, p-NF-κB, and inflammatory cytokines protein levels and increases in p-IKKα/ß/IKKα, p-IκBα/IκBα, and p-NF-κB/NF-κB phosphorylation ratios. Further, NF-kB pathway inhibitors BAY-117082 and PDTC abolished the downregulatory effects of AOPPs. These findings suggest that AOPPs downregulate CYP1A2 and CYP3A4 expression and activities by increasing inflammatory cytokine production and stimulating NF-κB-mediated signaling. Protein uremic toxins, such as AOPPs, may modify the nonrenal clearance of drugs in patients with CKD by influencing metabolic enzymes.

Advanced oxidation protein products induce microglia-mediated neuroinflammation via MAPKs-NF-κB signaling pathway and pyroptosis after secondary spinal cord injury.

BACKGROUND: Inflammatory response mediated by oxidative stress is considered as an important pathogenesis of spinal cord injury (SCI). Advanced oxidation protein products (AOPPs) are novel markers of oxidative stress and their role in inflammatory response after SCI remained unclear. This study aimed to investigate the role of AOPPs in SCI pathogenesis and explore the possible underlying mechanisms. METHODS: A C5 hemi-contusion injury was induced in Sprague-Dawley rats to confirm the involvement of AOPPs after SCI. For in vivo study, apocynin, the NADPH oxidase inhibitor was used to study the neuroprotective effects after SCI. For in vitro study, the BV2 microglia cell lines were pretreated with or without the inhibitor or transfected with or without small interference RNA (siRNA) and then stimulated with AOPPs. A combination of molecular and histological methods was used to clarify the mechanism and explore the signaling pathway both in vivo and in vitro. One-way analysis of variance (ANOVA) was conducted with Bonferroni post hoc tests to examine the differences between groups. RESULTS: The levels of AOPPs in plasma and cerebrospinal fluid as well as the contents in the spinal cord showed significant increase after SCI. Meanwhile, apocynin ameliorated tissue damage in the spinal cord after SCI, improving the functional recovery. Immunofluorescence staining and western blot analysis showed activation of microglia after SCI, which was in turn inhibited by apocynin. Pretreated BV2 cells with AOPPs triggered excessive generation of reactive oxygen species (ROS) by activating NADPH oxidase. Increased ROS induced p38 MAPK and JNK phosphorylation, subsequently triggering nuclear translocation of NF-κB p65 to express pro-inflammatory cytokines. Also, treatment of BV2 cells with AOPPs induced NLRP3 inflammasome activation and cleavage of Gasdermin-d (GSDMD), causing pyroptosis. This was confirmed by cleavage of caspase-1, production of downstream mature interleukin (IL)-1ß and IL-18 as well as rupture of rapid cell membrane. CONCLUSIONS: Collectively, these data indicated AOPPs as biomarkers of oxidative stress, modulating inflammatory response in SCI by multiple signaling pathways, which also included the induction of NADPH oxidase dependent ROS, and NLRP3-mediated pyroptosis, and activation of MAPKs and NF-κB.

Hydroxytyrosol promotes autophagy by regulating SIRT1 against advanced oxidation protein product­induced NADPH oxidase and inflammatory response.

Advanced oxidation protein products (AOPPs) can trigger NADPH oxidase (NOX) and lead to the production of reactive oxygen species (ROS) in the pathophysiology of rheumatoid arthritis (RA). Hydroxytyrosol (HT) is a phenolic composite in olive oil that has antioxidant and anti­inflammatory effects and enhances autophagy. Early research has revealed that HT can activate the silent information regulator 1 (SIRT1) pathway to induce autophagy and alleviate the cartilage inflammatory response caused by H2O2. However, whether HT can attenuate AOPP­induced NOX and inflammatory responses remains to be elucidated. The present study aimed to investigate how HT can alleviate the damage caused by AOPPs. In cell experiments, chondrocytes were pre­stimulated with HT and then exposed to AOPPs. First, it was found that HT promoted autophagy through the SIRT1 pathway, increased the expression of autophagy­related proteins including microtubule­associated protein 1 light chain 3, autophagy related (ATG)5 and ATG7, and decreased the expression of P62. Furthermore, HT reduced the expression of NOX, which was affected by AOPPs in chondrocytes through the SIRT1 pathway. Finally, the expression of inflammatory cytokines caused by AOPPs was downregulated following HT treatment. In conclusion, it was found that HT reduced the expression of NOX and inhibited the inflammatory response caused by AOPPs in chondrocytes through the SIRT1 pathway.

The Antiglycoxidative Ability of Selected Phenolic Compounds-An In Vitro Study.

Hyperglycemia and oxidative stress may be observed in different diseases as important factors connected with their development. They often occur simultaneously and are considered together as one process: Glycoxidation. This can influence the function or structure of many macromolecules, for example albumin, by changing their physiological properties. This disturbs the homeostasis of the organism, so the search for natural compounds able to inhibit the glycoxidation process is a current and important issue. The aim of this study was the examination of the antiglycoxidative capacity of 16 selected phenolic compounds, belonging to three phenolic groups, as potential therapeutic agents. Their antiglycoxidative ability, in two concentrations (2 and 20 µM), were examined by in vitro study. The inhibition of the formation of both glycoxidative products (advanced glycation end products (AGEs) and advanced oxidation protein products (AOPPs)) were assayed. Stronger antiglycoxidative action toward the formation of both AOPPs and AGEs was observed for homoprotocatechuic and ferulic acids in lower concentrations, as well as catechin, quercetin, and 8-O-methylurolithin A in higher concentrations. Homoprotocatechuic acid demonstrated the highest antiglycoxidative capacity in both examined concentrations and amongst all of them. A strong, significant correlation between the percentage of AOPPs and AGEs inhibition by compounds from all phenolic groups, in both examined concentrations, was observed. The obtained results give an insight into the antiglycoxidative potential of phenolic compounds and indicate homoprotocatechuic acid to be the most promising antiglycoxidative agent, but further biological and pharmacological studies are needed.

Advanced oxidation protein products promote NADPH oxidase-dependent ß-cell destruction and dysfunction through the Bcl-2/Bax apoptotic pathway.

The accumulation of plasma advanced oxidation protein products (AOPPs) has been linked with diverse disorders, including diabetes, chronic kidney disease, obesity, and metabolic syndrome. The aim of the present study was to evaluate the pathophysiological relevance of AOPPs in ß-cell destruction and dysfunction. Exposure of cultured rat ß-cells (INS-1) to AOPPs induced an increase in Bax expression, caspase-3 activity, and apoptosis as well as a decrease in Bcl-2 expression in a dose- and time-dependent manner. AOPP challenge rapidly increased the production of intracellular superoxide by activation of NADPH oxidases, demonstrated by p47phox translocation and interaction with p22phox and gp91phox, and this in turn led to apoptosis. AOPPs treatment resulted in ß-cell apoptosis, AOPPs accumulation, and decreased insulin content in pancreas and plasma in unilateral nephrectomized rats. Chronic inhibition of NADPH oxidase by apocynin prevented ß-cell apoptosis and ameliorated insulin deficiency in AOPP-challenged rats. This study demonstrates for the first time that accumulation of AOPPs promotes NADPH oxidase-dependent ß-cell destruction and dysfunction by the Bcl-2/Bax-caspase apoptotic pathway. This finding may provide a mechanistic explanation for ß-cell destruction and dysfunction in patients with diverse disorders.

Advanced Oxidation Protein Products-Modified Albumin Induces Differentiation of RAW264.7 Macrophages into Dendritic-Like Cells Which Is Modulated by Cell Surface Thiols.

Local accumulation of Advanced Oxidation Protein Products (AOPP) induces pro-inflammatory and pro-fibrotic processes in kidneys and is an independent predictor of renal fibrosis and of rapid decline of eGFR in patients with chronic kidney disease (CKD). In addition to kidney damage, circulating AOPP may be regarded as mediators of systemic oxidative stress and, in this capacity, they might play a role in the progression of atherosclerotic damage of arterial walls. Atherosclerosis is a chronic inflammatory disease that involves activation of innate and adaptive immunity. Dendritic cells (DCs) are key cells in this process, due to their role in antigen presentation, inflammation resolution and T cell activation. AOPP consist in oxidative modifications of proteins (such as albumin and fibrinogen) that mainly occur through myeloperoxidase (MPO)-derived hypochlorite (HOCl). HOCl modified proteins have been found in atherosclerotic lesions. The oxidizing environment and the shifts in cellular redox equilibrium trigger inflammation, activate immune cells and induce immune responses. Thus, surface thiol groups contribute to the regulation of immune functions. The aims of this work are: (1) to evaluate whether AOPP-proteins induce activation and differentiation of mature macrophages into dendritic cells in vitro; and (2) to define the role of cell surface thiol groups and of free radicals in this process. AOPP-proteins were prepared by in vitro incubation of human serum albumin (HSA) with HOCl. Mouse macrophage-like RAW264.7 were treated with various concentrations of AOPP-HSA with or without the antioxidant N-acetyl cysteine (NAC). Following 48 h of HSA-AOPP treatment, RAW264.7 morphological changes were evaluated by microscopic observation, while markers of dendritic lineage and activation (CD40, CD86, and MHC class II) and allogeneic T cell proliferation were evaluated by flow cytometry. Cell surface thiols were measured by AlexaFluor-maleimide binding, and ROS production was assessed as DCF fluorescence by flow cytometry. HSA-AOPP induced the differentiation of RAW264.7 cells into a dendritic-like phenotype, as shown by morphological changes, by increased CD40, CD86 and MHC class II surface expression and by induction of T cell proliferation. The cell surface thiols dose dependently decreased following HSA-AOPP treatment, while ROS production increased. NAC pre-treatment enhanced the amount of cell surface thiols and prevented their reduction due to treatment with AOPP. Both ROS production and RAW264.7 differentiation into DC-like cells induced by HSA-AOPP were reduced by NAC. Our results highlight that oxidized plasma proteins modulate specific immune responses of macrophages through a process involving changes in the thiol redox equilibrium. We suggest that this mechanism may play a role in determining the rapid progression of the atherosclerotic process observed in CKD patients.

Advanced Oxidation Protein Products Induce Epithelial-Mesenchymal Transition of Intestinal Epithelial Cells via a PKC δ-Mediated, Redox-Dependent Signaling Pathway.

AIMS: Epithelial-mesenchymal transition (EMT) has been considered a fundamental mechanism in complications of Crohn's disease (CD), especially intestinal fibrosis. However, the mechanism underlying EMT regulation in intestinal fibrosis remains unclear. This study aimed to investigate the role of advanced oxidation protein products (AOPPs) in the occurrence of intestinal EMT. RESULTS: AOPPs accumulated in CD tissues and were associated with EMT marker expression in fibrotic lesions from CD patients. Challenge with AOPPs induced intestinal epithelial cell (IEC) phenotype transdifferentiation, fibroblast-like phenotype acquisition, and production of extracellular matrix, both in vitro and in vivo. The effect of AOPPs was mainly mediated by a protein kinase C (PKC) δ-mediated redox-dependent pathway, including phosphorylation of PKC δ, recruitment of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, production of reactive oxygen species, and NF-κB p65 activation. Inhibition of AOPP-redox signaling activation effectively blocked AOPP-induced EMT in vitro. Studies performed in normal rats showed that chronic administration of AOPPs triggered the occurrence of EMT in rat intestinal epithelia, accompanied by disruption of intestinal integrity, and by promotion of collagen deposition. These effects could be reversed by inhibition of NADPH oxidase. Innovation and Conclusion: This is the first study to demonstrate that AOPPs triggered the occurrence of EMT in IECs in vitro and in vivo through PKC δ-mediated redox-dependent signaling. Our study identifies the role of AOPPs and, in turn, EMT in intestinal fibrosis and provides novel potential targets for the treatment of intestinal fibrotic diseases. Antioxid. Redox Signal. 27, 37-56.