Elevated protein carbonyls as plasma markers of oxidative stress in acute pancreatitis

Tephrosia purpurea, with (-)-Pseudosemiglabrin as the Major Constituent, Alleviates Severe Acute Pancreatitis-Mediated Acute Lung Injury by Modulating HMGB1 and IL-22

Ischemia-reperfusion (IR) injury is a major cause of multiple organ failure. The purpose of this study was to look into the role of Tephrosia purpurea (TEP) and its active constituent pseudosemiglabrin (PS) in alleviating severe acute pancreatitis and its associated acute lung injury. We established a rat pancreatic IR model, and the rats were treated with TEP (200 mg/kg and 400 mg/kg) and PS (20 and 40 mg/kg), in addition to the IR control and sham groups. The results showed that the respiratory parameters, including inspiratory time (Ti), expiratory time (Te), duration (Dr), and respiratory rate (RR), were comparable among all groups, while peak inspiratory flow (PIF), forced vital capacity (FVC), and forced expiratory volume at 0.1 s (FEV0.1) were significantly impaired. Notably, PS at 40 mg/kg showed normal PIF, FVC, and FEV0.1/FVC compared to the IR group, indicating an improved lung function. Additionally, TEP and PS showed protective effects on pancreatic and lung tissues compared to the IR control group, with the following effects: alleviating pathological damage; reducing serum levels of trypsinogen activation peptide (TAP), lipase, and amylase; decreasing oxidative stress markers such as MDA and MPO; restoring antioxidant enzyme activity (GPx); suppressing inflammatory markers TNF-α, IL-6, and NF-κB; downregulating HMGB1 gene in pancreatic tissue; and upregulating the IL-22 gene in lung tissues. In conclusion, the obtained findings demonstrate that oral supplementation of TEP and PS to rats with pancreatic IR alleviates pancreatic and lung injuries by reducing oxidative stress and modulating inflammatory processes, which offers an attractive therapeutic option for severe acute pancreatitis and its associated acute lung injury.

The role of ischaemia-modified albumin in the prognosis of acute pancreatitis and its correlation with the NF-B-mediated inflammatory response

OBJECTIVE

To investigate the correlation between the serum levels of ischaemia-modified albumin (IMA) and disease severity in rats with acute pancreatitis (AP).

METHODS

A rat AP model was established and blood samples from each group were analysed at different time points. After the experiment, the pancreatic tissues of the rats were collected for pathological examination and the measurement of protein levels of NF-κB and NF-κB p65. Serum levels of amylase (α-AMY), tumour necrosis factor-α (TNF-α), interleukin (IL)-6 and IL-8 were also compared between groups of rats.

RESULTS

The serum IMA concentration in the severe acute pancreatitis (SAP) group was greater than that in the mild acute pancreatitis (MAP) group. The levels of the NF-κB and NF-κB p65 proteins were increased in the MAP and SAP groups in a time-dependent manner. α-AMY, TNF-α and IL-6 were increased at all time points in the MAP and SAP groups. The increases were greatest at 24 h in the SAP group. In terms of pathological changes in the pancreas, renal and lung tissues, the damage in the SAP group was more obvious than that in the MAP group.

CONCLUSIONS

Serum IMA level was associated with inflammatory markers and NF-κB p65 in rats with AP.

Oleuropein Relieves Pancreatic Ischemia Reperfusion Injury in Rats by Suppressing Inflammation and Oxidative Stress through HMGB1/NF-κB Pathway

Oleuropein (OLP) is a naturally occurring phenolic compound in olive plant with antioxidant and anti-inflammatory potential and can possibly be used in treating pancreatic injuries. This investigation aimed to follow the molecular mechanism behind the potential therapeutic effect of OLP against pancreatic injury persuaded by ischemia-reperfusion (I/R). Pancreatic I/R injury was induced by splenic artery occlusion for 60 min followed by reperfusion. Oral administration of OLP (10 and 20 mg/kg) for 2 days significantly alleviated I/R-persuaded oxidative damage and inflammatory responses in pancreatic tissue as indicated by the decreased malondialdehyde (MDA) content and increased glutathione peroxidase (GPx) activity, accompanied by the suppression of myeloperoxidase (MPO) activity and reduced levels of interleukin-1beta (IL-1β), nuclear factor kappa B (NF-κB), and tumor necrosis factor alpha (TNF-α) in pancreatic tissues. Furthermore, OLP treatment markedly restored the serum levels of amylase, trypsinogen-activated peptide (TAP), and lipase, with concurrent improvement in pancreatic histopathological alterations. Moreover, treatment with OLP regulated the pancreatic expression of inducible nitric oxide synthase (iNOS) and high-mobility group box 1 (HMGB1) relative to rats of the pancreatic IR group. Thus, OLP treatment significantly alleviates the I/R-induced pancreatic injury by inhibiting oxidative stress and inflammation in rats through downregulation of HMGB1 and its downstream NF-κB signaling pathway.

Oxime blot: A novel method for reliable and sensitive detection of carbonylated proteins in diverse biological systems

Oxidative stress and oxidative protein damage occur in various biological processes and diseases. The carbonyl group on amino acid side chains is the most widely used protein oxidation biomarker. Carbonyl groups are commonly detected indirectly through their reaction with 2,4-dinitrophenylhydrazine (DNPH) and subsequent labeling with an anti-DNP antibody. However, the DNPH immunoblotting method lacks protocol standardization, exhibits technical bias, and has low reliability. To overcome these shortcomings, we have developed a new blotting method in which the carbonyl group reacts with the biotin-aminooxy probe to form a chemically stable oxime bond. The reaction speed and the extent of the carbonyl group derivatization are increased by adding a p-phenylenediamine (pPDA) catalyst under neutral pH conditions. These improvements are crucial since they ensure that the carbonyl derivatization reaction reaches a plateau within hours and increases the sensitivity and robustness of protein carbonyl detection. Furthermore, derivatization under pH-neutral conditions facilitates a good SDS-PAGE protein migration pattern, avoids protein loss by acidic precipitation, and is directly compatible with protein immunoprecipitation. This work describes the new Oxime blot method and demonstrates its use in detecting protein carbonylation in complex matrices from diverse biological samples.

OGG1 Inhibition Reduces Acinar Cell Injury in a Mouse Model of Acute Pancreatitis

Acute pancreatitis (AP) is a potentially life-threatening gastrointestinal disease with a complex pathology including oxidative stress. Oxidative stress triggers oxidative DNA lesions such as formation of 7,8-dihydro-8-oxo-2′-oxoguanine (8-oxoG) and also causes DNA strand breaks. DNA breaks can activate the nuclear enzyme poly(ADP-ribose) polymerase 1 (PARP1) which contributes to AP pathology. 8-oxoG is recognized by 8-oxoG glycosylase 1 (OGG1) resulting in the removal of 8-oxoG from DNA as an initial step of base excision repair. Since OGG1 also possesses a DNA nicking activity, OGG1 activation may also trigger PARP1 activation. In the present study we investigated the role played by OGG1 in AP. We found that the OGG1 inhibitor compound TH5487 reduced edema formation, inflammatory cell migration and necrosis in a cerulein-induced AP model in mice. Moreover, TH5487 caused 8-oxoG accumulation and reduced tissue poly(ADP-ribose) levels. Consistent with the indirect PARP inhibitory effect, TH5487 shifted necrotic cell death (LDH release and Sytox green uptake) towards apoptosis (caspase activity) in isolated pancreatic acinar cells. In the in vivo AP model, TH5487 treatment suppressed the expression of various cytokine and chemokine mRNAs such as those of TNF, IL-1β, IL1ra, IL6, IL16, IL23, CSF, CCL2, CCL4, CCL12, IL10 and TREM as measured with a cytokine array and verified by RT-qPCR. As a potential mechanism underlying the transcriptional inhibitory effect of the OGG1 inhibitor we showed that while 8-oxoG accumulation in the DNA facilitates NF-κB binding to its consensus sequence, when OGG1 is inhibited, target site occupancy of NF-κB is impaired. In summary, OGG1 inhibition provides protection from tissue injury in AP and these effects are likely due to interference with the PARP1 and NF-κB activation pathways.

Sulfiredoxin-1 attenuates injury and inflammation in acute pancreatitis through the ROS/ER stress/Cathepsin B axis

Acinar cell injury and the inflammatory response are critical bioprocesses of acute pancreatitis (AP). We investigated the role and underlying mechanism of sulfiredoxin-1 (Srxn1) in AP. Mild AP was induced by intraperitoneal injection of cerulein and severe AP was induced by partial duct ligation with cerulein stimulation or intraperitoneal injection of L-arginine in mice. Acinar cells, neutrophils, and macrophages were isolated. The pancreas was analyzed by histology, immunochemistry staining, and TUNEL assays, and the expression of certain proteins and RNAs, cytokine levels, trypsin activity, and reactive oxygen species (ROS) levels were determined. Srxn1 was inhibited by J14 or silenced by siRNA, and overexpression was introduced by a lentiviral vector. Transcriptomic analysis was used to explore the mechanism of Srxn1-mediated effects. We also evaluated the effect of adeno-associated virus (AAV)-mediated overexpression of Srxn1 by intraductal administration and the protection of AP. We found that Srxn1 expression was upregulated in mild AP but decreased in severe AP. Inhibition of Srxn1 increased ROS, histological score, the release of trypsin, and inflammatory responses in mice. Inhibition of Srxn1 expression promoted the production of ROS and induced apoptosis, while overexpression of Srxn1 led to the opposite results in acinar cells. Furthermore, inhibition of Srxn1 expression promoted the inflammatory response by accumulating and activating M1 phenotype macrophages and neutrophils in AP. Mechanistically, ROS-induced ER stress and activation of Cathepsin B, which converts trypsinogen to trypsin, were responsible for the Srxn1 inhibition-mediated effects on AP. Importantly, we demonstrated that AAV-mediated overexpression of Srxn1 attenuated AP in mice. Taken together, these results showed that Srxn1 is a protective target for AP by attenuating acinar injury and inflammation through the ROS/ER stress/Cathepsin B axis.

Resveratrol supplementation and acute pancreatitis: A comprehensive review

Resveratrol, a natural polyphenolic ingredient extracted from herbs, suppresses oxidative stress and inflammation. We performed a comprehensive review to find any evidence about the effects of Resveratrol on acute pancreatitis (AP). Resveratrol has been found to directly impact cytokine generation. As these factors play a crucial role in the pathophysiology of AP, resveratrol might attenuate AP and its complications. Mechanistically, resveratrol exerts its pharmacological effects through anti-inflammatory and antioxidant mechanisms via interaction with different signaling molecules and transcription factors. Indeed, resveratrol might prove to be an effective therapeutic component for AP treatment in the future. In this review, we shed light on potential most recent pathways through which resveratrol might impact the management and control of AP.

A Comprehensive Review on Source, Types, Effects, Nanotechnology, Detection, and Therapeutic Management of Reactive Carbonyl Species Associated with Various Chronic Diseases

Continuous oxidation of carbohydrates, lipids, and amino acids generate extremely reactive carbonyl species (RCS). Human body comprises some important RCS namely hexanal, acrolein, 4-hydroxy-2-nonenal, methylglyoxal, malondialdehyde, isolevuglandins, and 4-oxo-2- nonenal etc. These RCS damage important cellular components including proteins, nucleic acids, and lipids, which manifests cytotoxicity, mutagenicity, multitude of adducts and crosslinks that are connected to ageing and various chronic diseases like inflammatory disease, atherosclerosis, cerebral ischemia, diabetes, cancer, neurodegenerative diseases and cardiovascular disease. The constant prevalence of RCS in living cells suggests their importance in signal transduction and gene expression. Extensive knowledge of RCS properties, metabolism and relation with metabolic diseases would assist in development of effective approach to prevent numerous chronic diseases. Treatment approaches for RCS associated diseases involve endogenous RCS metabolizers, carbonyl metabolizing enzyme inducers, and RCS scavengers. Limited bioavailability and bio efficacy of RCS sequesters suggest importance of nanoparticles and nanocarriers. Identification of RCS and screening of compounds ability to sequester RCS employ several bioassays and analytical techniques. Present review describes in-depth study of RCS sources, types, properties, identification techniques, therapeutic approaches, nanocarriers, and their role in various diseases. This study will give an idea for therapeutic development to combat the RCS associated chronic diseases.

High levels of reactive oxygen species in pancreatic necrotic fluid of patients with walled-off pancreatic necrosis

INTRODUCTION

Walled-off pancreatic necrosis (WOPN) is a life-threatening, late complication of acute pancreatitis, in which a fluid collection containing necrotic material is formed. Infection of the fluid collection significantly increases the mortality of patients with WOPN.

AIM

To examine the levels of oxidative stress markers in the pancreatic necrotic fluid (PNF) and serum of patients with sterile and infected WOPN.

MATERIAL AND METHODS

Thirty-three adult patients with sterile WOPN and 14 with infected WOPN, as well as 31 patients with mild AP, were included in this study. Concentrations of oxidative stress markers (8-isoprostane, protein carbonyl groups, and 8-hydroxyguanine) were measured in the PNF and serum of patients with sterile and infected WOPN.

RESULTS

High concentrations of all measured oxidative stress markers in PNF, but not in serum, were detected in patients with WOPN. Additionally, oxidative stress markers in PNF were significantly increased in patients with infected as compared to sterile WOPN. The serum high sensitive C-reactive protein (hsCRP) concentrations showed the highest correlation with PNF oxidative stress marker levels. Receiver operating characteristics (ROC) curve analysis confirmed that serum hsCRP could be a good predictor of WOPN infection.

CONCLUSIONS

Oxidative stress is associated with WOPN development; infection of PNF worsens the course of WOPN, possibly via increased production of reactive oxygen species; and serum hsCRP concentrations seem to be a good, noninvasive indicator of PNF infection.

Higher plasma oxidative damage and lower plasma antioxidant defences in an Arctic seabird exposed to longer perfluoroalkyl acids

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) may cause detrimental effects on physiological function and reproduction of Arctic animals. However, there is a paucity of information on the link between PFASs and oxidative stress, which can have potential detrimental effects on key fitness traits, such as cellular homeostasis or reproduction. We have examined the correlations between multiple blood-based markers of oxidative status and several perfluoroalkyl acids (i.e., with 8 or more carbons) in male Arctic black-legged kittiwakes (Rissa tridactyla) during the pre-laying period. Higher protein oxidative damage was found in those birds having higher concentrations of perfluorododecanoic acid (PFDoA), perfluorotridecanoic acid (PFTriA) and perfluorotetradecanoic acid (PFTeA). Lower plasmatic non-enzymatic micro-molecular antioxidants were found in those birds having higher concentrations of perfluoroundecanoic acid (PFUnA), PFDoA and PFTeA. Effect size estimates showed that the significant correlations between PFASs and oxidative status markers were intermediate to strong. The non-enzymatic antioxidant capacity (including antioxidants of protein origin) was significantly lower in those birds having higher plasma concentration of linear perfluorooctanesulfonic acid (PFOSlin). In contrast, the activity of the antioxidant enzyme glutathione peroxidase in erythrocytes was not associated with any PFAS compounds. Our results suggest that increased oxidative stress might be one consequence of long-chain PFAS exposure. Experimental work will be needed to demonstrate whether PFASs cause toxic effects on free-living vertebrates through increased oxidative stress.

Dynamic thiol/disulphide homeostasis in acute pancreatitis

BACKGROUND/AIMS

The dynamic thiol/disulfide homeostasis plays pivotal roles in many physiological mechanisms in an organism. We aimed to investigate whether dynamic thiol/disulfide homeostasis changes among patients with acute pancreatitis.

MATERIALS AND METHODS

This prospective trial contained 45 patients with acute pancreatitis and 45 sex-and age-matched healthy volunteers as control group. Thiol/disulfide homeostasis parameters were measured by a novel and automated assay, and detected results were compared between the two groups.

RESULTS

Disulfide/total thiol percent ratio and disulfide/native thiol percent ratios were significantly higher in acute pancreatitis group; besides the native thiol, total thiol levels and native thiol/total thiol percent ratios were significantly lower (for all p < 0.001).

CONCLUSION

The thiol/disulfide homeostasis is impaired in acute pancreatitis with a shift toward the oxidative status, and this deficiency might be a pathogenic factor in acute pancreatitis. The correction of this thiol/disulfide imbalance may be a new target in the management of acute pancreatitis.

Resistin as a Prooxidant Factor and Predictor of Endothelium Damage in Patients with Mild Acute Pancreatitis Exposed to Tobacco Smoke Xenobiotics

Objectives

The study was aimed to assess the influence of tobacco smoke exposure on the intensity of inflammation measured by IL-6, α₁-antitripsin (AAT) and α₁-acid glycoprotein (AGP) concentrations, and Cd level and oxidative stress intensity measured by advanced oxidation protein product (AOPP) concentration in the blood of healthy subjects and AP patients during hospitalization. Endothelin-1 (ET-1) and resistin concentrations, markers of endothelium injury, were determined.

Results

An increased IL-6 concentration in healthy smokers compared to nonsmokers and AP patients compared to controls was shown. An increased AAT and AGP concentrations during hospitalization of AP patients were noted, in both smokers (AAT, AGP) and nonsmokers (AAT). In comparison to control groups, in AP patients, a 2-fold increased resistin concentration correlating with ET-1 concentration and decreased albumin concentration accompanied by increased AOPP concentration were demonstrated. AOPP concentration was higher in smokers with AP compared to nonsmokers and gradually enhanced during their hospitalization.

Conclusions

Tobacco smoke exposure can have a proinflammatory effect in both healthy subjects and AP patients. Increased resistin concentration in AP patients negatively correlating with albumin concentration has prooxidative effect on this protein resulting in enhanced AOPP level. Increased resistin concentration can intensify AAT and AGP production during AP.

Reactive oxygen species, Ca(2+) stores and acute pancreatitis; a step closer to therapy?

Disruption of Ca(2+) homeostasis can lead to severe damage of the pancreas, resulting in premature activation of digestive enzymes, vacuolisation and necrotic cell death, features typical of acute pancreatitis (AP). Therefore a fine balance between Ca(2+) release from internal stores, Ca(2+) entry and extrusion mechanisms is necessary to avoid injury. Precipitants of AP induce Ca(2+) overload of the pancreatic acinar cell that causes mitochondrial dysfunction, via formation of the mitochondrial permeability transition pore (MPTP), loss of ATP production and consequent necrosis. Oxidative stress has been shown to occur in the development of AP and may modify Ca(2+) signalling events in the acinar cell. However, the precise pathophysiological involvement is currently unclear and antioxidant therapy in the clinic has largely proved ineffective. Possible reasons for this are discussed, including evidence that ROS generation may determine cell death patterns. In contrast, recent evidence has indicated the potential for AP therapy via the prevention of Ca(2+)-dependent mitochondrial damage. Multiple approaches are indicated from preclinical findings; 1) inhibition of Ca(2+) release by IP3R blockade, 2) inhibition of Ca(2+) entry through Orai1 blockade and 3) prevention of MPTP formation. Clinical trials of drugs which prevent mitochondrial dysfunction induced by Ca(2+) overload of pancreatic acinar cells are imminent and may provide patient benefit for a disease that currently lacks specific therapy.

Protein oxidation and peroxidation

Proteins are major targets for radicals and two-electron oxidants in biological systems due to their abundance and high rate constants for reaction. With highly reactive radicals damage occurs at multiple side-chain and backbone sites. Less reactive species show greater selectivity with regard to the residues targeted and their spatial location. Modification can result in increased side-chain hydrophilicity, side-chain and backbone fragmentation, aggregation via covalent cross-linking or hydrophobic interactions, protein unfolding and altered conformation, altered interactions with biological partners and modified turnover. In the presence of O2, high yields of peroxyl radicals and peroxides (protein peroxidation) are formed; the latter account for up to 70% of the initial oxidant flux. Protein peroxides can oxidize both proteins and other targets. One-electron reduction results in additional radicals and chain reactions with alcohols and carbonyls as major products; the latter are commonly used markers of protein damage. Direct oxidation of cysteine (and less commonly) methionine residues is a major reaction; this is typically faster than with H2O2, and results in altered protein activity and function. Unlike H2O2, which is rapidly removed by protective enzymes, protein peroxides are only slowly removed, and catabolism is a major fate. Although turnover of modified proteins by proteasomal and lysosomal enzymes, and other proteases (e.g. mitochondrial Lon), can be efficient, protein hydroperoxides inhibit these pathways and this may contribute to the accumulation of modified proteins in cells. Available evidence supports an association between protein oxidation and multiple human pathologies, but whether this link is causal remains to be established.

Ameliorative Effects of Curcumin on Fibrinogen-Like Protein-2 Gene Expression, Some Oxido-Inflammatory and Apoptotic Markers in a Rat Model of l-Arginine-Induced Acute Pancreatitis

The aim of the study was to investigate the ameliorative effects of curcumin on fibrinogen like protein-2 (fgl-2), some oxido-inflammatory and apoptotic markers in rat-induced acute pancreatitis (AP). Seventy-five albino rats were divided into control group, l-arginine (l-Arg)-induced AP group, curcumin pre-treated group before AP induction, curcumin post-treated group after AP induction, and curcumin injected group only. AP group showed severe necrotizing pancreatitis confirmed by histopathological changes and elevations in serum amylase and lipase activities, levels of epithelial neutrophil-activating peptide 78, tissue content of protein carbonyls, levels of tumor necrosis factor α, and caspase-3 as well as myeloperoxidase activity. Significant elevation in pancreatic fgl-2 mRNA expression was detected in AP group. Improvement of all parameters was detected with increase of caspase-3 in both curcumin-treated groups that confirmed curcumin ameliorative effects against AP through induction of apoptosis and inhibition of micro-thrombosis, inflammation, and oxidative stress.

Role of Biomarkers in Diagnosis and Prognostic Evaluation of Acute Pancreatitis

Acute pancreatitis is a potentially life threatening disease. The spectrum of severity of the illness ranges from mild self-limiting disease to a highly fatal severe necrotizing pancreatitis. Despite intensive research and improved patient care, overall mortality still remains high, reaching up to 30–40% in cases with infected pancreatic necrosis. Although little is known about the exact pathogenesis, it has been widely accepted that premature activation of digestive enzymes within the pancreatic acinar cell is the trigger that leads to autodigestion of pancreatic tissue which is followed by infiltration and activation of leukocytes. Extensive research has been done over the past few decades regarding their role in diagnosis and prognostic evaluation of severe acute pancreatitis. Although many standalone biochemical markers have been studied for early assessment of severity, C-reactive protein still remains the most frequently used along with Interleukin-6. In this review we have discussed briefly the pathogenesis and the role of different biochemical markers in the diagnosis and severity evaluation in acute pancreatitis.

Antioxidants as a treatment for acute pancreatitis: A meta-analysis

OBJECTIVE

To assess the efficacy of antioxidants in acute (AP) pancreatitis.

METHODS

We searched PubMed, Embase and the Cochrane library for all randomized controlled trials (RCT) involving administration of antioxidants in the therapy of AP until February 2012. AP studies were pooled to analyze the effect of antioxidants on hospital stay, mortality, and complications. Subgroup analyses were performed on the use of the antioxidant glutamine.

RESULTS

In total, eleven RCTs were included. Among patients with AP, antioxidant therapy resulted in a borderline significant reduction in hospital stay (mean difference -1.74; 95%CI -3.56 to 0.08), a significant decrease in complications (RR 0.66; 95%CI 0.46-0.95) and a non-significant decrease in mortality rate (RR 0.66; 95%CI 0.30-1.46). Subgroup analyses showed that glutamine significantly reduced complications (RR 0.51; 95%CI 0.34-0.78) and mortality rate (RR 0.33; 95%CI 0.13-0.85).

CONCLUSION

The present meta-analysis shows a possible benefit of glutamine supplementation in patients with acute pancreatitis. However, large randomized trials are needed to confirm these observations.

Redox signaling in acute pancreatitis

Acute pancreatitis is an inflammatory process of the pancreatic gland that eventually may lead to a severe systemic inflammatory response. A key event in pancreatic damage is the intracellular activation of NF-κB and zymogens, involving also calcium, cathepsins, pH disorders, autophagy, and cell death, particularly necrosis. This review focuses on the new role of redox signaling in acute pancreatitis. Oxidative stress and redox status are involved in the onset of acute pancreatitis and also in the development of the systemic inflammatory response, being glutathione depletion, xanthine oxidase activation, and thiol oxidation in proteins critical features of the disease in the pancreas. On the other hand, the release of extracellular hemoglobin into the circulation from the ascitic fluid in severe necrotizing pancreatitis enhances lipid peroxidation in plasma and the inflammatory infiltrate into the lung and up-regulates the HIF-VEGF pathway, contributing to the systemic inflammatory response. Therefore, redox signaling and oxidative stress contribute to the local and systemic inflammatory response during acute pancreatitis.

Oxidative modification of proteins in pediatric cystic fibrosis with bacterial infections

Pseudomonas aeruginosa and Staphylococcus aureus cause chronic lung infection in cystic fibrosis (CF) patients, inducing chronic oxidative stress. Several markers of plasma protein oxidative damage and glycoxidation and activities of erythrocyte antioxidant enzymes have been compared in stable CF patients chronically infected with Pseudomonas aeruginosa (n = 12) and Staphylococcus aureus (n = 10) in relation to healthy subjects (n = 11). Concentration of nitric oxide was also measured in the exhaled air from the lower respiratory tract of patients with CF. Elevated glycophore (4.22 ± 0.91 and 4.19 ± 1.04 versus control 3.18 ± 0.53 fluorescence units (FU)/mg protein; P < 0.05) and carbonyl group levels (1.9 ± 0.64, 1.87 ± 0.45 versus control 0.94 ± 0.19 nmol/mg protein; P < 0.05) as well as increased glutathione S-transferase activity (2.51 ± 0.88 and 2.57 ± 0.79 U/g Hb versus 0.77 ± 0.16 U/g Hb; P < 0.05) were noted in Pseudomonas aeruginosa and Staphylococcus aureus infected CF. Kynurenine level (4.91 ± 1.22 versus 3.89 ± 0.54 FU/mg protein; P < 0.05) was elevated only in Staphylococcus aureus infected CF. These results confirm oxidative stress in CF and demonstrate the usefulness of the glycophore level and protein carbonyl groups as markers of oxidative modifications of plasma proteins in this disease.

Oxidative stress in acute pancreatitis: lost in translation?

Oxidative stress has been implicated in the pathogenesis of acute pancreatitis, a severe and debilitating inflammation of the pancreas that carries a significant mortality, and which imposes a considerable financial burden on the health system due to patient care. Although extensive efforts have been directed towards the elucidation of critical underlying mechanisms and the identification of novel therapeutic targets, the disease remains without a specific therapy. In experimental animal models of acute pancreatitis, increased oxidative stress and decreased antioxidant defences have been observed, changes also detected in patients clinically. However, despite the promise of studies evaluating the effects of antioxidants in these model systems, translation to the clinic has thus far been disappointing. This may reflect many factors involved in the design of both preclinical and clinical evaluations of antioxidant therapy, not least the fact that most experimental studies have focussed on pre-treatment rather than post-injury assessment. This review has examined evidence relating to the involvement of oxidative stress in the pathophysiology of acute pancreatitis, focussing on experimental models and the clinical experience, including the experimental techniques employed and potential of antioxidant therapy.

Reduced blood nrf-2 mRNA in local overweight boys at risk of metabolic complications: a study in San Luis City, San Luis, Argentina

BACKGROUND

Childhood overweight (OW) is a matter of public health concern because of its long-term impact on adulthood health. NF-E2-related factor 2 (Nrf-2) regulates the antioxidant/lipogenic response to a sustained positive energy balance that prevails during weight gain. Here we aimed at studying a possible link between OW and Nrf-2-dependent antioxidant/lipogenic response in a local population of boys at risk of metabolic complications.

METHODS

We measured clinical and biochemical parameters related to lipid metabolism, oxidative stress, and metabolic syndrome in a population of OW boys [body mass index (BMI) percentile ≥85(th) and <95(th), n=22] and normal weight boys (NW; BMI percentile<85(th), n=27) from San Luis City, San Luis, Argentina.

RESULTS

Compared to NW, OW boys had lower insulin sensitivity, an altered plasma lipid profile, and increased markers of oxidative stress and inflammatory fatty acids. OW boys also had a higher atherogenic index and peripheral insulin resistance than NW boys. We also found that glutathione peroxidase activity and the reduced glutathione to oxidized glutathione ratio were lower in OW boys than NW boys, suggesting that OW boys may have an altered antioxidant response to oxidative stress. Finally, Nrf-2 expression negatively correlated with metabolic syndrome parameters in OW boys.

CONCLUSIONS

Our data suggest that OW boys have a reduced antioxidant and lipogenic response to a positive energy balance, resulting in oxidative stress, insulin resistance, and risk of developing metabolic complications. Our data also provide a rationale for nutritional interventions aimed at restoring Nrf-2 expression to reduce the risk of metabolic complications in OW boys.

Antioxidants in patients receiving total parenteral nutrition after gastrointestinal cancer surgery

Total parenteral nutrition (TPN) is essential for patients with postoperative impairing gastrointestinal function who are unable to receive and absorb oral/enteral feeding for at least 7 days. Oxidative stress plays a major role in the ethiopathogenesis of cancers. In this study, total antioxidant status (TAS), glutathione peroxidase (GPx), superoxide dismutase, malondialdehyde and ascorbic acid were studied in patients operated because of small intestine, colorectal or pancreatic cancer and subsequently receiving TPN in comparison with patients receiving standard nutrition after the operation. TAS level and GPx activity were decreased in patients with small intestine cancer but did not differ in patients with colorectal and pancreatic cancer before and after surgery. In all patient groups receiving TPN, superoxide dismutase activity after the surgery was kept at the same level as before. On the fifth day after the surgery, malondialdehyde concentration in each group was restored to the value observed before surgery. On the fifth day of TPN treatment, ascorbic acid concentration was increased in every group of patients. TPN applied during the postoperative period alleviates oxidative stress resulting from surgery. In the case of small intestine cancer, the addition of vitamins and antioxidants to the nutrition mixture seems to result in depletion of antioxidant enzymes' activities.

Antioxidant therapy in acute pancreatitis: experimental and clinical evidence

SIGNIFICANCE

Oxidative stress plays an important role in the pathogenesis of both acute and chronic pancreatitis. Although its impact is well investigated and has been studied clinically in chronic pancreatitis, it is less well defined for acute pancreatitis.

RECENT ADVANCES

Pathophysiological aspects of oxidative stress in acute pancreatitis have shown that reactive oxidative species (ROS) participate in the inflammatory cascade, and mediate inflammatory cell adhesion and consecutive tissue damage. Furthermore, ROS are involved in the generation of pain as another important clinical feature of patients suffering from acute pancreatitis.

CRITICAL ISSUES

Despite sufficient basic and experimental knowledge and evidence, the step from bench to bedside has not been successfully performed. Only a limited number of clinical studies are available that can give convincing evidence for the use of antioxidants in the clinical setting of acute pancreatitis.

FUTURE DIRECTIONS

Future studies are required to evaluate potential benefits of antioxidative substances to attenuate the severity of acute pancreatitis. Special focus should be put on the aspect of pain generation and the progression from mild to severe acute pancreatitis in the clinical setting.

The redox status of experimental hemorrhagic shock as measured by cyclic voltammetry

Hemorrhagic shock (HS) leads to reactive oxygen species production. However, clinicians do not have access to bedside measurements of the redox status during HS. Cyclic voltammetry (CyV) is a simple electrochemical method of measuring redox status. The aims of this study were to 1) report the first application of cyclic voltammetry to measure the acute changes in serum redox status after HS, 2) to contrast it with another severe systemic disease with a different redox pathology (acute pancreatitis [AP]), and 3) to describe the response of CyV over time in a resolving model of AP. In the acute study, 24 male Wistar rats were randomized into three groups: groups 1 (control), 2 (AP), and 3 (HS). In the time-course study, 28 rats were randomized to a sham-control as well as 6 and 24 h post-AP cohorts, respectively.Cyclic voltammetry was performed using a three-electrode system. In the acute study, the first and second voltammetric peaks increased significantly in HS. In contrast, within the AP group, only the first voltammetric peak showed a significant increase. The first voltammetric peak correlated with plasma protein carbonyls (PCs) and with thiobarbituric acid-reactive substances, whereas the second voltammetric peak correlated positively with plasma protein carbonyls. In the second study, the first voltammetric peak correlated with physiological improvements. Here, we showed that serum CyV could respond to the serum redox change in HS and AP. Cyclic voltammetry warrants evaluation as a potential real-time beside measure of a patient's redox status during shock.

Therapeutic implications of oxidative stress in acute and chronic pancreatitis

PURPOSE OF REVIEW

This review presents new evidence on the role of oxidative stress and antioxidant status in acute and chronic pancreatitis published in the last year.

RECENT FINDINGS

In-vitro studies showed that protein phosphatases may play an important role in the interaction between reactive oxygen species and proinflammatory cytokines in acute pancreatitis. In-vivo studies found that several natural compounds ameliorate oxidative stress and, therefore, have therapeutic potential. In the domain of clinical studies, the major development is the first double-blind placebo-controlled randomized trial that showed effectiveness of oral antioxidant supplementation (organic selenium, ascorbic acid, alpha-tocopherol, beta-carotene, and methionine) in relieving pain in patients with chronic pancreatitis. The developments in clinical studies on acute pancreatitis are less spectacular and mainly limited to evaluation of different markers of oxidative stress and antioxidant status in the course of disease.

SUMMARY

A significant advance has been made in the arena of research in chronic, but not acute, pancreatitis. There is now solid evidence to justify the use of oral antioxidants in the treatment of patients with chronic pancreatitis. The progress in clinical research on antioxidants in acute pancreatitis is hampered by several factors, including suboptimal classification of acute pancreatitis and route of administration used in previous studies.

Relationships among iron, protein oxidation and lipid peroxidation levels in rats with alcohol-induced acute pancreatitis

It has been previously shown that alcohol induces the damage of pancreatic parenchyma tissue, but the mechanism of this damage is still poorly understood. Assuming that oxygen radical damage may be the involved, we measured markers of oxidative damage in pancreatic tissue, blood serum, plasma, and whole blood of rats with early-stage alcohol-induced acute pancreatitis. Thirty-eight male Wistar rats were divided into three groups: the control group (group 1), the acute pancreatitis group 1 day (group 2), and 3 days (group 3) after the injection of ethyl alcohol into the common biliary duct, respectively. The levels of Fe in tissue and serum, whole blood viscosity, plasma viscosity, fibrinogen and homocysteine (Hcy) levels, erythrocyte and plasma malondialdehyde (MDA), and tissue and plasma protein carbonyl levels were found to be significantly higher in groups 2 and 3 than in group 1. However, the levels of reduced glutathione (GSH) in tissue and erythrocytes were significantly lower in groups 2 and 3 than in group 1. These results suggest that elevated Fe levels in serum and pancreatic tissue in rats with early-stage alcohol-induced acute pancreatitis is associated with various hemorheological changes and with oxidative damage of the pancreas.

Oxidative stress induced changes in plasma protein can be a predictor of imminent severe dengue infection

OBJECTIVES

Oxidative stress in dengue viral infection has been suggested and severity of it was found to be associated with progress of illness. Hence assessing oxidative stress mediated changes in plasma proteins can be an early biomarker for prediction of severe dengue infection.

DESIGN AND METHODS

Thirty two dengue hemorrhagic fever (DHF), 21 dengue shock syndrome (DSS), 27 dengue fever (DF) and 63 age and sex matched controls, were included in this study. Blood samples were collected on the 3rd day of fever. Protein carbonylation (PCOs) and protein-bound sulphydryl (PBSH) group levels were determined by spectrophotometric method and analyzed as predictor of dengue hemorrhagic fever and dengue shock syndrome.

RESULTS

About 80-84% of cases presented with no signs of DHF/DSS at the time of sampling. Dengue infected individuals had significantly elevated PCOs and low PBSH group levels than the controls. Using one-way ANOVA we found a significant difference with high PCOs and low PBSH group levels between DHF and DSS when compared with DF (P<0.001). However, no difference was observed in PBSH group levels between DHF and DSS. A significant difference in PCOs to PBSH ratio was observed among DF, DHF and DSS (P<0.001). Linear regression analysis revealed that duration of hospitalization is dependent on PCOs and PBSH group levels. Receiver operator curve (ROC) analysis indicated that 5.22nmol/mg protein PCOs; 1.08 PCOs to PBSH group levels ratio were optimal cutoff value for predicting DHF with sensitivity and specificity of 87.5% and 74.1%; 96.9% and 81.5%, respectively. For DSS prediction, 6.13 nmol/mg protein PCOs; 1.16 PCOs to PBSH group levels ratio were found as effective cutoff with sensitivity and specificity of 81% and 71.9%; 95.2% and 56.2%, respectively.

CONCLUSION

Oxidative stress has been observed to develop since early days of onset of dengue infection. Plasma PCOs, PCOs to PBSH group ratio were found to very well predict DHF/DSS.

Redox status of acute pancreatitis as measured by cyclic voltammetry: initial rodent studies to assess disease severity

OBJECTIVE

To determine whether serum antioxidant capacity as measured by the electrochemical technique cyclic voltammetry could be used to resolve differences in the severity of an inflammatory disease such as acute pancreatitis.

DESIGN

Experimental animal study.

SETTING

Animal laboratory, Department of Surgery, Faculty of Medical and Health Sciences, University of Auckland, New Zealand.

SUBJECTS

Male Wistar rats.

INTERVENTIONS

A total of 48 inbred male Wistar rats were studied in five experimental groups. Group 1 (baseline reference, immediate euthanasia, n = 14) had no surgical intervention. Group 2 (sham, n = 9) had identical surgical procedures to the pancreatitis groups except for the intraductal infusion. Groups 3-5 (n = 9, n = 10, and n = 6, respectively) had acute pancreatitis induced by the pancreatic intraductal infusion of 3%, 4%, or 5% sodium taurocholate, respectively. Groups 2-5 were killed after 12 hrs.

MEASUREMENTS AND MAIN RESULTS

Cyclic voltammetry involves scanning the voltage of a working electrode while recording the anodic current produced as the low molecular weight antioxidants in the solution are oxidized on the surface of the working electrode. The current produced is proportional to the combined concentration of the antioxidants. There was a significant positive correlation of the first cyclic voltammetric peak maximum with pancreatic histologic severity (Spearman's r = .51, p = .007) and with a number of other markers of systemic severity, notably bicarbonate (r = -.57, p = .002), base excess (r = -.65, p < .001), urea (r = .68, p < .001), and calcium (r = -.60, p = .008). The first cyclic voltammetric peak maximum was superior at indicating the severity of the disease state compared with a standard method of total antioxidant capacity measurement.

CONCLUSIONS

In experimental pancreatitis, the first cyclic voltammetric peak maximum showed significant correlations with histologic and systemic indices of severity. Further clinical studies are now needed to define the role of cyclic voltammetry in monitoring the progression of this and other severe illness in the critical care setting.

Oxidative stress biomarkers responses to physical overtraining: implications for diagnosis

Overtraining syndrome is characterized by declining performance and transient inflammation following periods of severe training with major health implications for the athletes. Currently, there is no single diagnostic marker for overtraining. The present investigation examined the responses of oxidative stress biomarkers to a resistance training protocol of progressively increased and decreased volume/intensity. Twelve males (21.3+/-2.3 years) participated in a 12-week resistance training consisting of five 3-week periods (T1, 2 tones/week; T2, 8 tones/week; T3, 14 tones/week; T4, 2 tones/week), followed by a 3-week period of complete rest. Blood/urine samples were collected at baseline and 96 h following the last training session of each period. Performance (strength, power, jumping ability) increased after T2 and declined thereafter, indicating an overtraining response. Overtraining (T3) induced sustained leukocytosis, an increase of urinary isoprostanes (7-fold), TBARS (56%), protein carbonyls (73%), catalase (96%), glutathione peroxidase, and oxidized glutathione (GSSG) (25%) and a decline of reduced glutathione (GSH) (31%), GSH/GSSG (56%), and total antioxidant capacity. Isoprostanes and GSH/GSSG were highly (r=0.764-0.911) correlated with performance drop and training volume increase. In conclusion, overtraining induces a marked response of oxidative stress biomarkers which, in some cases, was proportional to training load, suggesting that they may serve as a tool for overtraining diagnosis.

4-Hydroxynonenal, an endogenous aldehyde, causes pain and neurogenic inflammation through activation of the irritant receptor TRPA1

TRPA1 is an excitatory ion channel expressed by a subpopulation of primary afferent somatosensory neurons that contain substance P and calcitonin gene-related peptide. Environmental irritants such as mustard oil, allicin, and acrolein activate TRPA1, causing acute pain, neuropeptide release, and neurogenic inflammation. Genetic studies indicate that TRPA1 is also activated downstream of one or more proalgesic agents that stimulate phospholipase C signaling pathways, thereby implicating this channel in peripheral mechanisms controlling pain hypersensitivity. However, it is not known whether tissue injury also produces endogenous proalgesic factors that activate TRPA1 directly to augment inflammatory pain. Here, we report that recombinant or native TRPA1 channels are activated by 4-hydroxy-2-nonenal (HNE), an endogenous alpha,beta-unsaturated aldehyde that is produced when reactive oxygen species peroxidate membrane phospholipids in response to tissue injury, inflammation, and oxidative stress. HNE provokes release of substance P and calcitonin gene-related peptide from central (spinal cord) and peripheral (esophagus) nerve endings, resulting in neurogenic plasma protein extravasation in peripheral tissues. Moreover, injection of HNE into the rodent hind paw elicits pain-related behaviors that are inhibited by TRPA1 antagonists and absent in animals lacking functional TRPA1 channels. These findings demonstrate that HNE activates TRPA1 on nociceptive neurons to promote acute pain, neuropeptide release, and neurogenic inflammation. Our results also provide a mechanism-based rationale for developing novel analgesic or anti-inflammatory agents that target HNE production or TRPA1 activation.

Assessment of oxidative stress in chronic pancreatitis patients

AIM: To assess the levels of antioxidant capacity and oxidative damage in blood of chronic pancreatitis (CP) patients in comparison with those in healthy control subjects, by using several different analytical techniques.

METHODS: Thirty-five CP patients and 35 healthy control subjects were investigated prospectively with respect to plasma levels of thiols, ferric reducing ability of plasma (FRAP, i.e. antioxidant capacity), levels of protein carbonyls and thiobarbituric acid reactive substances (TBARS). Additionally, we evaluated the production of reactive oxygen species (ROS) in whole blood.

RESULTS: The antioxidative thiols including cysteine, cysteinylglycine and glutathione were significantly lower in CP patients. In addition, the non-enzymatic antioxidant capacity was significantly lower in CP patients, which correlated with the amount of oxidative protein (protein carbonyls) and the extent of lipid damage (TBARS), both were significantly higher in CP patients. The ROS production in whole blood after stimulation with phorbol 12-myritate 13-acetaat, demonstrated a strong tendency to produce more ROS in CP patients.

CONCLUSION: Oxidative stress may contribute to the pathogenesis of chronic pancreatitis by decreasing antioxidant capacity and increasing oxidative damage in CP patients may be a rationale for intervention with antioxidant therapy.

Protein carbonylation, cellular dysfunction, and disease progression

Carbonylation of proteins is an irreversible oxidative damage, often leading to a loss of protein function, which is considered a widespread indicator of severe oxidative damage and disease-derived protein dysfunction. Whereas moderately carbonylated proteins are degraded by the proteasomal system, heavily carbonylated proteins tend to form high-molecular-weight aggregates that are resistant to degradation and accumulate as damaged or unfolded proteins. Such aggregates of carbonylated proteins can inhibit proteasome activity. Alarge number of neurodegenerative diseases are directly associated with the accumulation of proteolysis-resistant aggregates of carbonylated proteins in tissues. Identification of specific carbonylated protein(s) functionally impaired and development of selective carbonyl blockers should lead to the definitive assessment of the causative, correlative or consequential role of protein carbonylation in disease onset and/or progression, possibly providing new therapeutic approaches.

Biomarkers of oxidative damage in human disease

Oxidative/nitrosative stress, a pervasive condition of increased amounts of reactive oxygen/nitrogen species, is now recognized to be a prominent feature of many acute and chronic diseases and even of the normal aging process. However, definitive evidence for this association has often been lacking because of recognized shortcomings with biomarkers and/or methods available to assess oxidative stress status in humans. Emphasis is now being placed on biomarkers of oxidative stress, which are objectively measured and evaluated as indicators of normal biological processes, pathogenic processes, or pharmacologic responses to therapeutic intervention. To be a predictor of disease, a biomarker must be validated. Validation criteria include intrinsic qualities such as specificity, sensitivity, degree of inter- and intraindividual variability, and knowledge of the confounding and modifying factors. In addition, characteristics of the sampling and analytical procedures are of relevance, including constraints and noninvasiveness of sampling, stability of potential biomarkers, and the simplicity, sensitivity, specificity, and speed of the analytical method. Here we discuss some of the more commonly used biomarkers of oxidative/nitrosative damage and include selected examples of human studies.

Especies reactivas de oxígeno en las enfermedades inflamatorias del páncreas: ¿una posible diana terapéutica?

Chronic and acute pancreatitis can be understood as distinct stages of an inflammatory spectrum in the pancreas. Although its pathogenesis is not well defined, oxidative stress seems to be clearly involved in its development. During acute pancreatitis, there is an extraordinary and rapid formation of reactive oxygen species that leads to the extinction of pancreatic antioxidant reserves, causes direct tissue damage and activates oxidative cellular mediators, giving rise to the lesion. However, classical antioxidants have not been shown to have clear benefits in patients with acute pancreatitis. Chronic pancreatitis seems to be the result of a recurrent lesion and defective repair, leading to pancreatic atrophy and fibrosis. In this process, oxidative stress is an efficient stimulus to maintain pancreatic stellar cells active, the fibrogenic motor of chronic pancreatitis. Although antioxidant supplements relieve abdominal pain in these patients, the direction of future antioxidant therapies lies in identifying oxidative mechanisms with the potential for intervention.

Oxygen: from the benefits of inducing VEGF expression to managing the risk of hyperbaric stress

Hypoxia limits wound healing. Both normobaric (1 atm) and hyperbaric oxygen (HBO) approaches have been used clinically to oxygenate wound tissue. Recently, we reported that HBO ameliorates stress-induced impairment of dermal healing. We examined the effect of pressure on oxygen-induced vascular endothelial growth factor (VEGF) expression by human HaCaT keratinocytes. Next, we investigated the effect of HBO on whole-body redox and on the ratio of oxidized to reduced glutathione (GSSG/GSH) in the liver, heart, lung, and brain of rats. Superoxygenation (90% O2) of keratinocytes partially arrested cell growth. G2-M growth arrest was substantially augmented by HBO. HBO also caused apoptosis in a small subpopulation. Normobaric oxygen, but not HBO (2 atm), potently induced the expression of VEGF165 and 189. In vivo electron paramagnetic resonance spectroscopy imaging revealed a clear shift of the whole-body redox status toward oxidation in response to HBO. The standard diet of laboratory rats contains excessive (17x human recommended dietary allowance) alpha-tocopherol (E++), which confers exceptional resistance to oxidant insults. People with chronic wounds commonly suffer from under- or malnutrition. We generated vitamin E-deficient (E-) rats by long-term dietary vitamin E restriction. HBO did not raise GSSG/GSH in E++ rats, but post-HBO GSSG/GSH was significantly higher in E- compared with E++. Thus, rats on antioxidant-enriched diet were well protected against HBO. The risk of oxidative stress may negatively impact the net benefits of HBO. This is of special concern for people with inadequate intake of dietary antioxidants. Nutritional antioxidant supplementation may offset HBO-induced oxidative stress.

Proteins as biomarkers of oxidative/nitrosative stress in diseases: the contribution of redox proteomics

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) contribute to the pathogenesis and/or progression of several human diseases. Proteins are important molecular signposts of oxidative/nitrosative damage. However, it is generally unresolved whether the presence of oxidatively/nitrosatively modified proteins has a causal role or simply reflects secondary epiphenomena. Only direct identification and characterization of the modified protein(s) in a given pathophysiological condition can decipher the potential roles played by ROS/RNS-induced protein modifications. During the last few years, mass spectrometry (MS)-based technologies have contributed in a significant way to foster a better understanding of disease processes. The study of oxidative/nitrosative modifications, investigated by redox proteomics, is contributing to establish a relationship between pathological hallmarks of disease and protein structural and functional abnormalities. MS-based technologies promise a contribution in a new era of molecular medicine, especially in the discovery of diagnostic biomarkers of oxidative/nitrosative stress, enabling early detection of diseases. Indeed, identification and characterization of oxidatively/nitrosatively modified proteins in human diseases has just begun.