Peroxynitrite-mediated DNA strand breakage activates poly (ADP-ribose) synthetase and causes cellular energy depletion in carrageenan-induced pleurisy

Role of Gasotransmitters in Inflammatory Edema

Significance: Nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S) are, to date, the identified members of the gasotransmitter family, which consists of gaseous signaling molecules that play central roles in the regulation of a wide variety of physiological and pathophysiological processes, including inflammatory edema. Recent Advances: Recent studies show the potential anti-inflammatory and antiedematogenic effects of NO-, CO-, and H2S-donors in vivo. In general, it has been observed that the therapeutical effects of NO-donors are more relevant when administered at low doses at the onset of the inflammatory process. Regarding CO-donors, their antiedematogenic effects are mainly associated with inhibition of proinflammatory mediators (such as inducible NO synthase [iNOS]-derived NO), and the observed protective effects of H2S-donors seem to be mediated by reducing some proinflammatory enzyme activities. Critical Issues: The most recent investigations focus on the interactions among the gasotransmitters under different pathophysiological conditions. However, the biochemical/pharmacological nature of these interactions is neither general nor fully understood, although specifically dependent on the site where the inflammatory edema occurs. Future Directions: Considering the nature of the involved mechanisms, a deeper knowledge of the interactions among the gasotransmitters is mandatory. In addition, the development of new pharmacological tools, either donors or synthesis inhibitors of the three gasotransmitters, will certainly aid the basic investigations and open new strategies for the therapeutic treatment of inflammatory edema. Antioxid. Redox Signal. 40, 272-291.

gRASping the redox lever to modulate cancer cell fate signaling

RAS proteins are critical regulators of signaling networks controlling diverse cellular functions such as cell proliferation and survival and its mutation are among the most powerful oncogenic drivers in human cancers. Despite intense efforts, direct RAS-targeting strategies remain elusive due to its "undruggable" nature. To that end, bulk of the research efforts has been directed towards targeting upstream and/or downstream of RAS signaling. However, the therapeutic efficacies of these treatments are limited in the long run due to the acquired drug resistance in RAS-driven cancers. Interestingly, recent studies have uncovered a potential role of RAS in redox-regulation as well as the interplay between ROS and RAS-associated signaling networks during process of cancer initiation and progression. More specifically, these studies provide ample evidence to implicate RAS as a redox-rheostat, manipulating ROS levels to provide a redox-milieu conducive for carcinogenesis. Importantly, the understanding of RAS-ROS interplay could provide us with novel targetable vulnerabilities for designing therapeutic strategies. In this review, we provide a brief summary of the advances in the field to illustrate the dual role of RAS in redox-regulation and its implications in RAS signaling outcomes and also emerging redox-based strategies to target RAS-driven cancers.

Redox inhibition of protein phosphatase PP2A: Potential implications in oncogenesis and its progression

Cellular processes are dictated by the active signaling of proteins relaying messages to regulate cell proliferation, apoptosis, signal transduction and cell communications. An intricate web of protein kinases and phosphatases are critical to the proper transmission of signals across such cascades. By governing 30–50% of all protein dephosphorylation in the cell, with prominent substrate proteins being key regulators of signaling cascades, the phosphatase PP2A has emerged as a celebrated player in various developmental and tumorigenic pathways, thereby posing as an attractive target for therapeutic intervention in various pathologies wherein its activity is deregulated. This review is mainly focused on refreshing our understanding of the structural and functional complexity that cocoons the PP2A phosphatase, and its expression in cancers. Additionally, we focus on its physiological regulation as well as into recent advents and strategies that have shown promise in countering the deregulation of the phosphatase through its targeted reactivation. Finally, we dwell upon one of the key regulators of PP2A in cancer cells-cellular redox status-its multifarious nature, and its integration into the reactome of PP2A, highlighting some of the significant impacts that ROS can inflict on the structural modifications and functional aspect of PP2A.

Identifying the Long-Term Role of Inducible Nitric Oxide Synthase after Contusive Spinal Cord Injury Using a Transgenic Mouse Model

Inducible nitric oxide synthase (iNOS) is a potent mediator of oxidative stress during neuroinflammation triggered by neurotrauma or neurodegeneration. We previously demonstrated that acute iNOS inhibition attenuated iNOS levels and promoted neuroprotection and functional recovery after spinal cord injury (SCI). The present study investigated the effects of chronic iNOS ablation after SCI using inos-null mice. iNOS^-/- knockout and wild-type (WT) control mice underwent a moderate thoracic (T8) contusive SCI. Locomotor function was assessed weekly, using the Basso Mouse Scale (BMS), and at the endpoint (six weeks), by footprint analysis. At the endpoint, the volume of preserved white and gray matter, as well as the number of dorsal column axons and perilesional blood vessels rostral to the injury, were quantified. At weeks two and three after SCI, iNOS^-/- mice exhibited a significant locomotor improvement compared to WT controls, although a sustained improvement was not observed during later weeks. At the endpoint, iNOS^-/- mice showed significantly less preserved white and gray matter, as well as fewer dorsal column axons and perilesional blood vessels, compared to WT controls. While short-term antagonism of iNOS provides histological and functional benefits, its long-term ablation after SCI may be deleterious, blocking protective or reparative processes important for angiogenesis and tissue preservation.

The assessment of an in-vitro model for evaluating the role of PARP in ethanol-mediated hepatotoxicity

This investigation aims to assess whether the hepatocellular carcinoma cell line, HepG2, is an appropriate model to assess the role of poly (ADP-ribose) polymerase (PARP) during acute ethanol toxicosis. HepG2 cells were dosed with graded concentrations of ethanol, ranging from 100 mM to 800 mM, for 6 hours to assess PARP activity induction, while another parallel experiment examined cellular damage via medium aspartate aminotransferase activity and cellular viability via MTT reduction. Aspartate aminotransferase activity was significantly elevated at 600 mM ethanol (FOLD; P < 0.01), with further increases at the 800 mM dose (1.43 fold; P < 0.001), compared to controls. Cellular viability was not significantly decreased compared to controls among all dose groups. PARP activity measured in total cell lysates showed a significant decreasing trend with respect to ethanol dose, reaching statistical significance at the 100 mM dose group (P < 0.05). Paradoxically, exposure to 50 μM etoposide (Positive apoptosis-inducing control) did not demonstrate significant PARP activity ablation. When analyzing PARP activity observation temporally, a significant correlation (R(2) =0.5314) was observed between activity and assay sequence. Overall, a clear HepG2 insensitivity to ethanol was observed.

The protective role of MnTBAP in oxidant-mediated injury and inflammation in a rat model of lung contusion

BACKGROUND

Lung contusion (LC) is a unique direct and focal insult that is considered a major risk factor for the initiation of acute lung injury and acute respiratory distress syndrome. We have shown recently that consumption of nitric oxide (due to excess superoxide) resulting in peroxynitrite formation leads to decreased vascular reactivity after LC. In this study, we set out to determine whether the superoxide scavenger Mn (III) tetrakis (4-benzoic acid) porphyrin chloride (MnTBAP) plays a protective role in alleviating acute inflammatory response and injury in LC.

METHODS

Nonlethal, closed-chest, bilateral LC was induced in a rodent model. Administration of the superoxide dismutase mimetic MnTBAP concurrently in LC in rats was performed, and bronchoalveolar lavage (BAL) and lung samples were analyzed for degree of injury and inflammation at 5 and 24 h after the insult. The extent of injury was assessed by the measurement of cells and albumin with cytokine levels in the BAL and lungs. Lung samples were subjected to H&E and superoxide staining with dihydro-ethidium. Protein-bound dityrosine and nitrotyrosine levels were quantified in lung tissue by tandem mass spectrometry.

RESULTS

The degrees of lung injury after LC as determined by BAL albumin levels were significantly decreased in the MnTBAP-administered rats at all the time points when compared to the corresponding controls. The release of proinflammatory cytokines and BAL neutrophils was significantly less in the rats administered MnTBAP after LC. Administration of MnTBAP decreased tissue damage and decreased necrosis and neutrophil-rich exudate at the 24-h time point. Staining for superoxide anions showed significantly greater intensity in the lung samples from the LC group compared to the LC+ MnTBAP group. High-performance liquid chromatography/tandem mass spectrometry revealed that MnTBAP treatment significantly attenuated dityrosine and nitrotyrosine levels, consistent with decreased oxidant injury.

CONCLUSION

Superoxide dismutase mimetic-MnTBAP reduced permeability and oxidative injury in LC and may have a therapeutic role in diminishing inflammation in LC.

Selenocysteine confers resistance to inactivation by oxidation in thioredoxin reductase: comparison of selenium and sulfur enzymes

Mammalian thioredoxin reductase (TR) is a selenocysteine (Sec)-containing homodimeric pyridine nucleotide oxidoreductase which catalyzes the reduction of oxidized thioredoxin. We have previously demonstrated the full-length mitochondrial mammalian TR (mTR3) enzyme to be resistant to inactivation from exposure to 50 mM H2O2. Because a Sec residue oxidizes more rapidly than a cysteine (Cys) residue, it has been previously thought that Sec-containing enzymes are "sensitive to oxidation" compared to Cys-orthologues. Here we show for the first time a direct comparison of the abilities of Sec-containing mTR3 and the Cys-orthologue from D. melanogaster (DmTR) to resist inactivation by oxidation from a variety of oxidants including H2O2, hydroxyl radical, peroxynitrite, hypochlorous acid, hypobromous acid, and hypothiocyanous acid. The results show that the Sec-containing TR is far superior to the Cys-orthologue TR in resisting inactivation by oxidation. To further test our hypothesis that the use of Sec confers strong resistance to inactivation by oxidation, we constructed a chimeric enzyme in which we replaced the active site Cys nucleophile of DmTR with a Sec residue using semisynthesis. The chimeric Sec-containing enzyme has similar ability to resist inactivation by oxidation as the wild type Sec-containing TR from mouse mitochondria. The use of Sec in the chimeric enzyme "rescued" the enzyme from oxidant-induced inactivation for all of the oxidants tested in this study, in direct contrast to previous understanding. We discuss two possibilities for this rescue effect from inactivation under identical conditions of oxidative stress: (i) Sec resists overoxidation and inactivation, whereas a Cys residue can be permanently overoxidized to the sulfinic acid form, and (ii) Sec protects the body of the enzyme from harmful oxidation by allowing the enzyme to metabolize (turnover) various oxidants much better than a Cys-containing TR.

The molecular mechanisms of offspring effects from obese pregnancy

The incidence of obesity, increased weight gain and the popularity of high-fat / high-sugar diets are seriously impacting upon the global population. Billions of individuals are affected, and although diet and lifestyle are of paramount importance to the development of adult obesity, compelling evidence is emerging which suggests that maternal obesity and related disorders may be passed on to the next generation by non-genetic means. The processes acting within the uteri of obese mothers may permanently predispose offspring to a diverse plethora of diseases ranging from obesity and diabetes to psychiatric disorders. This review aims to summarise some of the molecular mechanisms and active processes currently known about maternal obesity and its effect on foetal and neonatal physiology and metabolism. Complex and multifactorial networks of molecules are intertwined and culminate in a pathologically synergistic manner to cause disruption and disorganisation of foetal physiology. This altered phenotype may potentiate the cycle of intergenerational transmission of obesity and related disorders.

Cellular stress responses, hormetic phytochemicals and vitagenes in aging and longevity

Modulation of endogenous cellular defense mechanisms represents an innovative approach to therapeutic intervention in diseases causing chronic tissue damage, such as in neurodegeneration. This paper introduces the emerging role of exogenous molecules in hormetic-based neuroprotection and the mitochondrial redox signaling concept of hormesis and its applications to the field of neuroprotection and longevity. Maintenance of optimal long-term health conditions is accomplished by a complex network of longevity assurance processes that are controlled by vitagenes, a group of genes involved in preserving cellular homeostasis during stressful conditions. Vitagenes encode for heat shock proteins (Hsp) Hsp32, Hsp70, the thioredoxin and the sirtuin protein systems. Dietary antioxidants, such as polyphenols and L-carnitine/acetyl-L-carnitine, have recently been demonstrated to be neuroprotective through the activation of hormetic pathways, including vitagenes. Hormesis provides the central underpinning of neuroprotective responses, providing a framework for explaining the common quantitative features of their dose response relationships, their mechanistic foundations, their relationship to the concept of biological plasticity as well as providing a key insight for improving the accuracy of the therapeutic dose of pharmaceutical agents within the highly heterogeneous human population. This paper describes in mechanistic detail how hormetic dose responses are mediated for endogenous cellular defense pathways including sirtuin, Nrfs and related pathways that integrate adaptive stress responses in the prevention of neurodegenerative diseases. This article is part of a Special Issue entitled: Antioxidants and Antioxidant Treatment in Disease.

Hormesis, cellular stress response and vitagenes as critical determinants in aging and longevity

Understanding mechanisms of aging and determinants of life span will help to reduce age-related morbidity and facilitate healthy aging. Average lifespan has increased over the last centuries, as a consequence of medical and environmental factors, but maximal life span remains unchanged. Extension of maximal life span is currently possible in animal models with measures such as genetic manipulations and caloric restriction (CR). CR appears to prolong life by reducing reactive oxygen species (ROS)-mediated oxidative damage. But ROS formation, which is positively implicated in cellular stress response mechanisms, is a highly regulated process controlled by a complex network of intracellular signaling pathways. By sensing the intracellular nutrient and energy status, the functional state of mitochondria, and the concentration of ROS produced in mitochondria, the longevity network regulates life span across species by co-ordinating information flow along its convergent, divergent and multiply branched signaling pathways, including vitagenes which are genes involved in preserving cellular homeostasis during stressful conditions. Vitagenes encode for heat shock proteins (Hsp) Hsp32, Hsp70, the thioredoxin and the sirtuin protein systems. Dietary antioxidants, such as carnosine, carnitines or polyphenols, have recently been demonstrated to be neuroprotective through the activation of hormetic pathways, including vitagenes. The hormetic dose-response, challenges long-standing beliefs about the nature of the dose-response in a lowdose zone, having the potential to affect significantly the design of pre-clinical studies and clinical trials as well as strategies for optimal patient dosing in the treatment of numerous diseases. Given the broad cytoprotective properties of the heat shock response there is now strong interest in discovering and developing pharmacological agents capable of inducing stress responses. In this review we discuss the most current and up to date understanding of the possible signaling mechanisms by which caloric restriction, as well hormetic caloric restriction-mimetics compounds by activating vitagenes can enhance defensive systems involved in bioenergetic and stress resistance homeostasis with consequent impact on longevity processes.

In-vivo effects of nociceptin and its structural analogue [Orn9] nociceptin on the antioxidant status of rat blood and liver after carrageenan-induced paw inflammation

The production of reactive oxygen species (ROS) in cells is well balanced with their elimination by the antioxidant defence system. This balance is essential for maintenance of physiological conditions, and its disturbance (oxidative stress) has been suggested as a potential pathogenic mechanism in a variety of diseases, accompanied by inflammation. In this study, the in-vivo effects of nociceptin (N/OFQ(1–13)NH2) and its structure analogue [Orn9]N/OFQ(1–13)NH2 were studied on markers of oxidative stress in erythrocytes and liver of rats 4 hours after subplantar administration of carrageenan (CG) (1%, 100 µl) in the right hind paw. A considerable inflammatory oedema of the paw was observed. CG did not change blood haemoglobin content, hematocrit value, glutathione level and antioxidant enzyme activities in the erythrocytes, but there was an increase in lipid peroxidation. In liver, CG-induced imbalance was manifested by an increase in lipid peroxidation and a decrease in glutathione level. Both peptides (20 µg, i.p.), when administered alone, had no effect on all parameters tested. When either [Orn9]N/OFQ(1–13)NH2 or N/OFQ(1–13)NH2 was injected simultaneously with CG or 15 minutes before it, they did not affect the CG-induced changes in the antioxidant status of the erythrocytes and liver. Our results suggest that the peptides tested did not play a role in the free radical processes that accompany CG-induced paw inflammation.

Pure MnTBAP selectively scavenges peroxynitrite over superoxide: comparison of pure and commercial MnTBAP samples to MnTE-2-PyP in two models of oxidative stress injury, an SOD-specific Escherichia coli model and carrageenan-induced pleurisy

MnTBAP is often referred to as an SOD mimic in numerous models of oxidative stress. We have recently reported that pure MnTBAP does not dismute superoxide, but commercial or poorly purified samples are able to perform O2.- dismutation with low-to-moderate efficacy via non-innocent Mn-containing impurities. Herein, we show that neither commercial nor pure MnTBAP could substitute for SOD enzyme in a SOD-deficient Escherichia coli model, whereas MnTE-2-PyP-treated SOD-deficient E. coli grew as well as a wild-type strain. This SOD-specific system indicates that MnTBAP does not act as an SOD mimic in vivo. In another model, carrageenan-induced pleurisy in mice, inflammation was evidenced by increased pleural fluid exudate and neutrophil infiltration and activation: these events were blocked by 0.3 mg/kg MnTE-2-PyP and, to a slightly lesser extent, by 10 mg/kg of either MnTBAP. Also, 3-nitrotyrosine formation, an indication of peroxynitrite existence in vivo, was blocked by both compounds; again MnTE-2-PyP was 33-fold more effective. Pleurisy model data indicate that MnTBAP exerts some protective actions in common with MnTE-2-PyP, which are not O2.- related and can be fully rationalized if one considers that the common biological role shared by MnTBAP and MnTE-2-PyP is related to their reduction of peroxynitrite and carbonate radical, the latter arising from ONOOCO2 adduct. The log kcat (O2.-) value for MnTBAP is estimated to be about 3.16, which is approximately 5 and approximately 6 orders of magnitude smaller than the SOD activities of the potent SOD mimic MnTE-2-PyP and Cu,Zn-SOD, respectively. This very low value indicates that MnTBAP is too inefficient at dismuting superoxide to be of any biological impact, which was confirmed in the SOD-deficient E. coli model. The peroxynitrite scavenging ability of MnTBAP, however, is only approximately 2.5 orders of magnitude smaller than that of MnTE-2-PyP and is not significantly affected by the presence of the SOD-active impurities in the commercial MnTBAP sample (log k red (ONOO-) = 5.06 for pure and 4.97 for commercial sample). The reduction of carbonate radical is equally fast with MnTBAP and MnTE-2-PyP. The dose of MnTBAP required to yield oxidative stress protection and block nitrotyrosine formation in the pleurisy model is > 1.5 orders of magnitude higher than that of MnTE-2-PyP, which could be related to the lower ability of MnTBAP to scavenge peroxynitrite. The slightly better protection observed with the commercial MnTBAP sample (relative to the pure MnTBAP) could arise from its impurities, which, by scavenging O2.-, reduce consequently the overall peroxynitrite and secondary ROS/RNS levels. These observations have profound biological repercussions as they may suggest that the effect of MnTBAP observed in numerous studies may conceivably relate to peroxynitrite scavenging. Moreover, provided that pure MnTBAP is unable to dismute superoxide at any significant extent, but is able to partially scavenge peroxynitrite and carbonate radical, this compound may prove valuable in distinguishing ONOO-/CO3.- from O2.- pathways.

Effect of tumour necrosis factor-alpha receptor 1 genetic deletion on carrageenan-induced acute inflammation: a comparison with etanercept

In the present study, we used tumour necrosis factor-alpha receptor 1 knock-out mice (TNF-alphaR1KO) to evaluate an in vivo role of TNF-alphaR1 on the pathogenesis of inflammatory diseases. We used a murine model of carrageenan-induced acute inflammation (pleurisy), a preclinical model of airway inflammation. The data proved that TNF-alphaR1KO were resistant to carrageenan-induced acute inflammation compared with TNF-alpha wild-type mice. TNF-alphaR1KO showed a significant reduction in accumulation of pleural exudate and in the number of inflammatory cells, in lung infiltration of polymorphonuclear leucocytes and lipid peroxidation and showed a decreased production of nitrite/nitrate in pleural exudates. Furthermore, the intensity and degree of the adhesion molecule intercellular adhesion molecule-1 and P-selectin, Fas ligand (FasL), inducible nitric oxide sythase and nitrotyrosine determined by immunohistochemical analysis were reduced markedly in lung tissues from TNF-alphaR1KO at 4 h and 24 h after carrageenan injection. Moreover, TNF-alpha and interleukin-1beta concentrations were reduced in inflamed areas and in pleural exudates from TNF-alphaR1KO. To support the results generated using pleural inflammation, carrageenan-induced paw oedema models were also performed. In order to elucidate whether the observed anti-inflammatory effects were related to the inhibition of TNF-alpha, we also investigated the effect of etanercept, a TNF-alpha soluble receptor construct, on carrageenan-induced pleurisy. The treatment with etanercept (5 mg/kg subcutaneously 2 h before the carrageenan injection) reduces markedly both laboratory and histological signs of carrageenan-induced pleurisy. Our results showed that administration of etanercept resulted in the same outcome as that of deletion of the TNF-alphaR1 receptor, adding a new insight to TNF-alpha as an excellent target by therapeutic applications.

Role of TNF-alpha in lung tight junction alteration in mouse model of acute lung inflammation

In the present study, we used tumor necrosis factor-R1 knock out mice (TNF-αR1KO) to understand the roles of TNF-α on epithelial function in models of carrageenan-induced acute lung inflammation. In order to elucidate whether the observed anti-inflammatory status is related to the inhibition of TNF-α, we also investigated the effect of etanercept, a TNF-α soluble receptor construct, on lung TJ function. Pharmacological and genetic TNF-α inhibition significantly reduced the degree of (1) TNF-α production in pleural exudates and in the lung tissues, (2) the inflammatory cell infiltration in the pleural cavity as well as in the lung tissues (evaluated by MPO activity), (3) the alteration of ZO-1, Claudin-2, Claudin-4, Claudin-5 and β-catenin (immunohistochemistry) and (4) apoptosis (TUNEL staining, Bax, Bcl-2 expression). Taken together, our results demonstrate that inhibition of TNF-α reduces the tight junction permeability in the lung tissues associated with acute lung inflammation, suggesting a possible role of TNF-α on lung barrier dysfunction.

Nitric oxide in the injured spinal cord: synthases cross-talk, oxidative stress and inflammation

Nitric oxide (NO) is a unique informational molecule involved in a variety of physiological processes in the central nervous system (SNS). It has been demonstrated that it can exert both protective and detrimental effects in several diseases states of the CNS, including spinal cord injury (SCI). The effects of NO on the spinal cord depend on several factors such as: concentration of produced NO, activity of different synthase isoforms, cellular source of production and time of release. Basically, it has been shown that low NO concentrations may play a role in physiologic processes, whereas large amounts of NO may be detrimental by increasing oxidative stress. However, this does not explain all the discrepancies evidenced studying the effects of NO in SCI models. The analysis of the different synthase isoforms, of their temporal profile of activation and cellular source has shed light on this topic. Two post-injury time intervals can be defined with reference to the NO production: immediately after injury and several hours-to-days later. The initial immediate peak of NO production after injury is due to the up-regulation of the neuronal NO synthase (nNOS) in resident spinal cord cells. The late peak is due primarily to the activity of inducible NOS (nNOS) produced by inflammatory infiltrating cells. High NO levels produced by up-regulated nNOS and iNOS are neurotoxic; the down-regulation of nNOS corresponds temporally to the expression of iNOS. On the bases of the evidence, therapeutic approaches should be aimed: (1) to reduce the NO-elicited damage by inhibition of specific synthases according to the temporal profile of activation; (2) by maintaining physiologic amount of NO to keep the induction of iNOS.

Poly (ADP-ribose) polymerase activation and circulatory shock

Sepsis is associated with increased production of reactive oxidant species. Oxidative and nitrosative stress can lead to activation of the nuclear enzyme poly (ADP-ribose) polymerase (PARP), with subsequent loss of cellular functions. Activation of PARP may dramatically lower the intracellular concentration of its substrate, NAD thus slowing the rate of glycolysis, electron transport and subsequently ATP formation. This process can result in cell dysfunction and cell death. In addition, PARP enhances the expression of various pro-inflammatory mediators, via activation of NF-kappaB, MAP kinase and AP-1 and other signal transduction pathways. Preclinical studies in various rodent and large animal models demonstrate that PARP inhibition or PAR deficiency exerts beneficial effects on the haemodynamic and metabolic alterations associated with septic and haemorrhagic shock. Recent human data also support the role of PARP in septic shock: In a retrospective study in 25 septic patients, an increase in plasma troponin level was related to increased mortality risk. In patients who died, significant myocardial damage was detected, and histological analysis of heart showed inflammatory infiltration, increased collagen deposition, and derangement of mitochondrial criptae. Immunohistochemical staining for poly(ADP-ribose) (PAR), the product of activated PARP was demonstrated in septic hearts. There was a positive correlation between PAR staining and troponin I; and a correlation of PAR staining and LVSSW. Thus, there is significant PARP activation in animal models subjected to circulatory shock, as well as in the hearts of septic patients. Based on the interventional studies in animals and the correlations observed in patients we propose that PARP activation may be, in part responsible for the cardiac depression and haemodynamic failure seen in humans with severe sepsis. Interestingly, recent studies reveal that the protective effects of PARP inhibitors are predominant in male animals, and are not apparent in female animals. Oestrogen, by providing a baseline inhibitory effect on PARP activation, may be partially responsible for this gender difference.

Antioxidant and anti-inflammatory effects of products from Croton celtidifolius Bailon on carrageenan-induced pleurisy in rats

Croton celtidifolius Bailon, commonly known as Sangue-de-Adáve or Pau-Andrade, is a tree found in the Atlantic forest of southern Brazil. It has been popularly used for the treatment of inflammatory and ulcerative disorders. Phytochemical analysis demonstrated the presence of flavonoids and proanthocyanidins in an ethyl acetate fraction (EAF) from C. celtidifolius Bailon. In this study, we have evaluated the effects of EAF and its sub-fractions (35 and 63, catechin) on inflammatory (cell migration and plasma extravasation) and oxidative (lipid peroxidation, superoxide dismutase (SOD) activity and superoxide anion production) parameters in carrageenan-induced pleurisy in rats. NO production was also measured by nitrite/nitrate levels. EAF and sub-fraction 63 (63SF) showed anti-inflammatory activity, as indicated by a reduction in plasma extravasation and cell migration (mainly polymorphonuclear leukocytes) to the pleural cavity. Furthermore, EAF treatment decreased the production of superoxide radical anion by cells isolated from the pleural cavity, while it did not affect the nitrite/nitrate levels in exudates. The results show that C. celtidifolius contains substances with antioxidant and anti-inflammatory activity that, at least in part, act by a modulation of oxidative stress by phenolic compounds.

Poly(ADP-Ribose) Glycohydrolase Activity Mediates Post-Traumatic Inflammatory Reaction after Experimental Spinal Cord Trauma

The aim of the present study was to examine the role of poly-(ADP-ribose) glycohydrolase (PARG) on the modulation of the inflammatory response and tissue injury associated with neurotrauma. Spinal cord trauma was induced in wild-type (WT) mice by the application of vascular clips (force of 24 g) to the dura via a two-level T(6) to T(7) laminectomy. Spinal cord injury in WT mice resulted in severe trauma characterized by edema, neutrophil infiltration, and cytokine production followed by recruitment of other inflammatory cells, production of a range of inflammation mediators, tissue damage, apoptosis, and disease. The genetic disruption of the PARG gene in mice or the pharmacological inhibition of PARG with GPI 16552 [N-bis-(3-phenyl-propyl)9-oxo-fluorene-2,7-diamide] (40 mg/kg i.p. bolus), a novel and potent PARG inhibitor, significantly reduced the degree of spinal cord inflammation and tissue injury (histological score), neutrophil infiltration, cytokine production (tumor necrosis factor-alpha and interleukin-1beta), and apoptosis. In a separate experiment, we have clearly demonstrated that PARG inhibition significantly ameliorated the recovery of limb function. Taken together, our results indicate that PARG activity modulates the inflammatory response and tissue injury events associated with spinal cord trauma and participate in target organ damage under these conditions.

Inhibition of tyrosine-kinase-mediated cellular signaling by tyrphostins AG 126 and AG556 modulates murine experimental acute pancreatitis

BACKGROUND

The effects of the tyrosine kinase inhibitors, tyrphostin AG126 and AG556 in a murine model of acute pancreatitis are investigated.

METHODS

Intraperitoneal injection of cerulein in mice resulted in a severe, acute pancreatitis, which was characterized by edema, neutrophil infiltration, tissue hemorrhage, and cell necrosis as well as elevation in the serum activities of amylase or lipase.

RESULTS

Infiltration of the pancreatic tissue of these animals with neutrophils (measured as increase in myeloperoxidase activity) was associated with signs of enhanced lipid peroxidation (increased tissue levels of malondialdehyde). Immunohistochemical examination showed a marked increase in immunoreactivity for nitrotyrosine and poly (ADP-ribose) polymerase (PARP) in the pancreas of cerulein-treated mice. Pretreatment or posttreatment with tyrphostin AG126 and AG556, 2 different tyrosine kinase inhibitors, significantly reduced the degree of pancreatic inflammation and tissue injury (histologic score). In particular, the treatment with the 2 tyrosine kinase inhibitors reduced the cerulein-induced nitrotyrosine formation and PARP activation in the pancreas as well as the systemic release of tumor necrosis factor alpha.

CONCLUSIONS

This study provides the first evidence that (1) prevention of the activation of protein tyrosine kinases reduces the development of acute pancreatitis, and (2) inhibition of the activity of certain tyrosine kinases may represent a novel approach for the therapy of acute pancreatitis.

Reactive oxygen species and human inflammatory periodontal diseases

Reactive oxygen species (ROS) have emerged as important signaling molecules in the regulation of various cellular processes. They can be generated by the mitochondrial electron transport chain in mitochondria and activation of polymorphonuclear leukocytes (PMN) during inflammatory conditions. Excessive generation of ROS may result in attack of and damage to most intracellular and extracellular components in a living organism. Moreover, ROS can directly induce and/or regulate apoptotic and necrotic cell death. Periodontal pathologies are inflammatory and degenerative diseases. Several forms of periodontal diseases are associated with activated PMN. Damage of tissues in inflammatory periodontal pathologies can be mediated by ROS resulting from the physiological activity of PMN during the phagocytosis of periodontopathic bacteria.

Melatonin limits lung injury in bleomycin treated mice

Melatonin is the principal secretory product of the pineal gland and its role as an immuno-modulator is well established. Recent evidence shows that melatonin is a scavenger of oxyradicals and peroxynitrite and exerts protective effects in septic shock, hemorrhagic shock and inflammation. The aim of this study was to investigate the effect of melatonin on the lung injury caused by bleomycin (BLM) administration. Mice subjected to intratracheal administration of BLM developed significant lung injury characterized by a marked neutrophil infiltration [assessed by myeloperoxidase (MPO) activity] and by tissue edema. In addition, an increase of immunoreactivity to nitrotyrosine, poly-ADP-ribose (PAR) was also observed in the lung of BLM-treated mice. Also, lung injury induced by BLM administration was correlated with a significant loss of body weight and with a significant mortality. Administration of melatonin (10 mg/kg i.p.) daily significantly reduced the (i) loss of body weight, (ii) mortality rate, (iii) infiltration of the lung with polymorphonuclear neutrophils (MPO activity), (iv) edema formation and (v) histological evidence of lung injury. Administration of melatonin also markedly reduced the nitrotyrosine and PAR formation. Taken together, our results demonstrate that treatment with melatonin significantly reduces lung injury induced by BLM in the mice.

M40403 prevents myocardial injury induced by acute hyperglycaemia in perfused rat heart

M40403 is a low-molecular-weight, synthetic manganese-containing biscyclohexylpyridine superoxide dismutase mimetic (SODm) that removes superoxide anions (O(2)(-)) without interfering with other reactive species known to be involved in cardiovascular alterations (e.g. nitric oxide [NO] and peroxynitrite [ONOO(-)]). As such, M40403 represents an important pharmacological tool to dissect the roles of O(2)(-) in functional and biochemical cardiovascular alterations induced by perfusion of high glucose concentrations into the heart. Perfusion of a high glucose concentration of glucose into the heart elicited important cardiovascular alterations characterized by QT interval prolongation, increase in coronary perfusion pressure (CPP), lipid peroxidation, decrease in MnSOD activity and DNA damage. All parameters of cardiovascular alteration were attenuated by M40403 (1-10 mg/l). Furthermore, perfusion of a high of glucose concentration induced a significant formation of nitrotyrosine as well as an activation of poly(adenosine diphosphate [ADP]-ribose) synthetase (PARS), as determined by immunohistochemical analysis of heart tissue. The extent of staining for nitrotyrosine and PARS was reduced by M40403. These results clearly indicate that O(2)(-) plays a critical role in the development of the functional and biochemical cardiovascular alterations induced by perfusion of a high concentration of glucose into the heart. Therefore, synthetic enzymes of SOD, such as M40403, offer a novel therapeutic approach for the management of various cardiovascular diseases where these radicals have been postulated to play a role.

Green tea polyphenol extract attenuates lung injury in experimental model of carrageenan-induced pleurisy in mice

Here we investigate the effects of the green tea extract in an animal model of acute inflammation, carrageenan-induced pleurisy. We report here that green tea extract (given at 25 mg/kg i.p. bolus 1 h prior to carrageenan), exerts potent anti-inflammatory effects in an animal model of acute inflammation in vivo.

Injection of carrageenan (2%) into the pleural cavity of mice elicited an acute inflammatory response characterized by fluid accumulation in the pleural cavity that contained many neutrophils (PMNs), an infiltration of PMNs in lung tissues and increased production of nitrite/nitrate, tumour necrosis factor alpha. All parameters of inflammation were attenuated by green tea extract treatment. Furthermore, carrageenan induced an up-regulation of the adhesion molecule ICAM-1, as well as nitrotyrosine and poly (ADP-ribose) synthetase (PARS) formation, as determined by immunohistochemical analysis of lung tissues. Staining for the ICAM-1, nitrotyrosine, and PARS was reduced by green tea extract.

Our results clearly demonstrate that treatment with green tea extract exerts a protective effect and offers a novel therapeutic approach for the management of lung injury.

Attenuation in the evolution of experimental spinal cord trauma by treatment with melatonin

Melatonin is the principal secretory product of the pineal gland and its role as an immuno-modulator is well established. Recent evidence shows that melatonin is a scavenger of oxyradicals and peroxynitrite and exerts protective effects in septic shock, hemorrhagic shock and inflammation. In the present study, we evaluated the effect of melatonin treatment, in a model of spinal cord injury (SCI). SCI was induced by the application of vascular clips (force of 50 g) to the dura via a four-level T5-T8 laminectomy. SCI in rats resulted in severe trauma characterized by edema, neutrophil infiltration and apoptosis (measured by terminal deoxynucleotidyl transferase-mediated dUTP nick-end-labeling staining). Infiltration of spinal cord tissue with neutrophils (measured as increase in myeloperoxidase activity) was associated with enhanced lipid peroxidation (increased tissue levels of malondialdehyde). Immunohistochemical examination demonstrated a marked increase in immunoreactivity for nitrotyrosine and Poly(ADP-ribose) (PAR) in the spinal cord tissue. In contrast, the degree of (a) spinal cord inflammation and tissue injury (histological score), (b) nitrotyrosine and PAR formation, (c) neutrophils infiltration and (d) apoptosis was markedly reduced in spinal cord tissue obtained from rats treated with melatonin (50 mg/kg i.p., 30 min before SCI, 30 min, 6 hr, 12 hr and 24 hr after SCI). In a separate set of experiment we have clearly demonstrated that melatonin treatment significantly ameliorated the recovery of limb function (evaluated by motor recovery score). Taken together, our results demonstrate that treatment with melatonin reduces the development of inflammation and tissue injury events associated with spinal cord trauma.

Antinociceptive and Anti-Inflammatory Effects of the Saponin and Sapogenins Obtained from the Stem of Akebia quinata

The stem of Akebia quinata Decasisne (Lardizabalaceae) has been used to treat urinary tract inflammatory disease. It has been reported that saponins in medicinal plants may act as bioactive components after biodegradation to sapogenins in the gastrointestinal tract. To find the active components, we obtained the methanol (MeOH) extract from A. quinata stems and fractionated this extract into CHCl(3), butanol (BuOH), and H(2)O fractions. A saponin-containing BuOH fraction was refluxed in an acidic solution to yield the hydrolyzed fraction. Silica gel column chromatography separated kalopanaxsaponin A (1) from the BuOH fraction, and oleanolic acid (2) and hederagenin (3) were obtained from the hydrolyzed fraction. The antinociceptive effect was tested by hot plate-writhing and tail-flicks methods using mice, and the anti-inflammatory effect was assayed using carrageenan-induced rat edema against the following samples: the MeOH extract of A. quinata stems, its fractions, the isolated saponin, kalopanaxsaponin A, and the sapogenins hederagenin and oleanolic acid. The MeOH extract exhibited antinociceptive/anti-inflammatory effects by oral administration of 100 and 250 mg/kg doses, indicating that the MeOH extract has an antinociceptive/anti-inflammatory activity. The BuOH fraction (crude saponin) also significantly exhibited those bioactivities. Treatments with 10 and 30 mg/kg perorally of these two sapogenins produced significant antinociceptive/ anti-inflammatory effects in the rat, suggesting that the sapogenins may act as resultant active compounds. Compounds 2 and 3 inhibited dye leakage into the peritoneal cavity induced by acetic acid, and the latter was more active than the former. The anti-inflammtory effects were further supported by the reduction of carrageenan-induced lipid peroxidation and hydroxy radical content in serum. These results suggest that the antinociceptive/anti-inflammatory properties of the stem of A. quinata can be attributed to the sapogenins oleanolic acid and hederagenin.

Dual effect of melatonin as proinflammatory and antioxidant in collagen-induced arthritis in rats

The aim of this study was to determine the effects of melatonin on proinflammatory status of rats with collagen-induced arthritis (CIA). CIA was induced in male Wistar rats with an emulsion of type II collagen in Freund's Incomplete Adjuvant (C-II/FIA). For 14 days, control and pinealectomized rats received a subcutaneous injection of 100 microL melatonin (30 microg) or vehicle (saline on 1% ethanol). Levels of cytokines interleukin (IL)-1beta and IL-6 were determined in the serum, peripheral blood mononuclear cells, and joints. Levels of anti-type II collagen antibody, nitrite/nitrate, and lipid peroxidation (LPO) were determined in the serum, joints, and brain. Treatment with melatonin significantly increased the levels of IL-1beta, IL-6, nitrite/nitrate and LPO in joints. However, melatonin significantly reduced the levels of nitrite/nitrate and LPO in serum and brain. Moreover, CIA in pinealectomized rats presented significantly reduced levels of IL-1beta and IL-6, titers of anti-type II collagen antibodies, levels of nitrite/nitrate, and LPO in joints but elevated levels in serum and brain. Melatonin has been described as a proinflammatory and antioxidant agent. In a process of inflammation as CIA, melatonin acts with a markedly proinflammatory effect at local and peripheral levels maintaining its antioxidant effect only at peripheral level.

Antiinflammatory effects of chiisanoside and chiisanogenin obtained from the leaves of Acanthopanax chiisanensis in the carrageenan- and Freund's complete adjuvant-induced rats

To find the antiinflammtory constituents of Acanthopanax chiisanensis (Araliaceae) leaves, phytochemical isolation procedures were performed by activity-guided fractionation in carrageenan- and Freund's complete adjuvant (FCA) reagent-induced rat models, respectively. In the two assay system, the MeOH extract (100 and 250 mg/kg, p.o.) showed significant antiinflammtory effects. Since BuOH extract among the fractionated extracts exhibited the most potent effect, it was subjected to column chromatography to yield a main triterpene glycoside, chiisanoside (1). This compound was hydrolyzed in alkaline solution to find the biological activity of produced aglycone, chiisanogenin (1a). Oral treatment with compounds 1 and 1a produced significant antiinflammtory effects at 10 and 30 mg/kg dose, and 1a was more potent than 1. The antiiflammtory effects of the two compounds were supported by the reduction of carrageenan-induced lipid peroxidation and hydroxy radical in serum. Furthermore, treatment with 1 and 1a significantly reduced rheumatoid arthritis (RA) and C-reactive protein (CRP) factors in the rat induced by Freund's complete adjuvant reagent. Compounds, 1 and 1a, inhibited xanthine oxidase activity and increased superoxide dismutase (SOD), glutathione peroxidase and catalase indicating that both compounds scavenged reactive oxygen species (ROS).

Inhibition of the nuclear factor-kappaB activation with pyrrolidine dithiocarbamate attenuating inflammation and oxidative stress after experimental spinal cord trauma in rats

OBJECT

The nuclear factor-kappaB (NF-kappaB) is a transcription factor that plays a pivotal role in the induction of genes involved in physiological processes and in the response to inflammation. The authors of recent studies have demonstrated that NF-kappaB and oxidative stress contribute to secondary injury after impact-induced spinal cord injury (SCI) in the rat. Dithiocarbamates are antioxidants that are potent inhibitors of NF-kappaB. The authors postulated that pyrrolidine dithiocarbamate (PDTC) would attenuate NF-kappaB-related inflammatory and oxidative events that occur after SCI.

METHODS

Spinal cord injury was induced by the application of vascular clips (force of 50 g) to the dura mater after a four-level T5-8 laminectomy. The authors investigated the effects of PDTC (30 mg/kg administered 30 minutes before SCI and 6 hours after SCI) on the development of the inflammatory response associated with SCI in rats. Levels of myeloperoxidase activity were measured as an indicator of polymorphonuclear infiltration; malondialdehyde levels in the spinal cord tissue were determined as an indicator of lipid peroxidation. The following studies were performed: immunohistochemical analysis to assess levels of inducible nitric oxide synthase (iNOS), nitrotyrosine formation, poly([adenosine diphosphate]-ribose) polymerase (PARP) activity; Western blot analysis to determine cytoplasmic levels of inhibitory-kappaB-alpha (IkappaB-alpha); and electrophoretic mobility-shift assay to measure the level of DNA/NF-kappaB binding. The PDTC treatment exerted potent antiinflammatory effects with significant reduction of polymorphonuclear cell infiltration, lipid peroxidation, and iNOS activity. Furthermore, administration of PDTC reduced immunohistochemical evidence of formation of nitrotyrosine and PARP activation in the spinal cord section obtained in the SCI-treated rats. Additionally, PDTC treatment significantly prevented the activation of NF-kappaB (electrophoretic mobility-shift assay and immunoblot analysis).

CONCLUSIONS

Overall, the results clearly demonstrate that PDTC-related prevention of the activation of NF-kappaB reduces the development of some secondary injury events after SCI. Therefore, inhibition of NF-kappaB may represent a novel approach in the treatment of SCIs.

Effect of methylguanidine in carrageenan-induced acute inflammation in the rats

In vitro and in vivo studies have demonstrated that methylguanidine, an inhibitor of nitric oxide synthase (NOS), is also able to reduce tumour necrosis factor-alpha (TNF-alpha) release. In the present study, we evaluated the anti-inflammatory potential of methylguanidine treatment in two models of acute inflammation (carrageenan-induced paw edema and pleurisy) where oxyradical, nitric oxide (NO) and prostaglandins play a crucial role in the inflammatory processes. Our data show that methylguanidine, given intraperitoneally at the dose of 30 mg/kg, inhibits the inflammatory response reducing significantly (P<0.05) paw swelling, pleural exudates formation, mononuclear cell infiltration and histological injury. Furthermore, our data suggests that there is a significant (P<0.05) reduction in the activity and expression both of the inducible NOS (iNOS) and of cyclooxygenase-2 in lung tissue of pleurisy model. Methylguanidine is also able to reduce the appearance of nitrotyrosine and of the nuclear enzyme poly(adenosine diphosphate [ADP]-ribose) synthase immunoreactivity in the inflamed lung tissues. Treatment with aminoguanidine, the reference drug, significantly reduced all the evaluated pro-inflammatory parameters in carrageenan-treated rats. Taken together, the present results demonstrate that methylguanidine exerts potent anti-inflammatory effects that could be, in part, related to an inhibition of the expression/activity of the iNOS and cyclooxygenase-2 and, another part, may be related to a reduction of TNF-alpha release.

Effects of GW274150, a novel and selective inhibitor of iNOS activity, in acute lung inflammation

1. The aim of this study was to investigate the effect of GW274150, a novel, potent and selective inhibitor of inducible nitric oxide synthase (iNOS) activity in a model of lung injury induced by carrageenan administration in the rats. 2. Injection of carrageenan into the pleural cavity of rats elicited an acute inflammatory response characterized by: fluid accumulation in the pleural cavity which contained a large number of polymorphonuclear cells (PMNs) as well as an infiltration of PMNs in lung tissues and subsequent lipid peroxidation, and increased production of nitrite/nitrate (NO(x)), tumour necrosis factor alpha (TNF-alpha) and interleukin-1beta (IL-1beta). 3. All parameters of inflammation were attenuated in a dose-dependent manner by GW274150 (2.5, 5 and 10 mg x kg(-1) injected i.p. 5 min before carrageenan). 4. Carrageenan induced an upregulation of the intracellular adhesion molecules-1 (ICAM-1), as well as nitrotyrosine and poly (ADP-ribose) (PAR) as determined by immunohistochemical analysis of lung tissues. 5. The degree of staining for the ICAM-1, nitrotyrosine and PAR was reduced by GW274150. These results clearly confirm that NO from iNOS plays a role in the development of the inflammatory response by altering key components of the inflammatory cascade. 6. GW274150 may offer a novel therapeutic approach for the management of various inflammatory diseases where NO and related radicals have been postulated to play a role.

The cyclopentenone prostaglandin 15-deoxy-delta(12,14)- PGJ2 attenuates the development of colon injury caused by dinitrobenzene sulphonic acid in the rat

1. Inflammatory bowel disease (IBD) is characterized by oxidative and nitrosative stress, leukocyte infiltration, and increased expression of the adhesion molecules intercellular adhesion molecule 1 (ICAM-1) in the colon. Recent evidence also suggests that the cyclopentenone prostaglandin (PG) 15-deoxy-delta(12,14)-PGJ(2) (15d- PGJ(2)) functions as an early anti-inflammatory signal. 2. The aim of the present paper is to investigate the effects of 15d-PGJ(2) in rats subjected to experimental colitis. 3. Colitis was induced in rats by intra-colonic instillation of dinitrobenzene sulphonic acid (DNBS). 15d-PGJ(2) was administered daily as intraperitoneal injection (20 or 40 microg kg(-1)). On day 4, animals were sacrificed and tissues were taken for histological and biochemical analysis. 4. 15d-PGJ(2) significantly reduced the degree of haemorrhagic diarrhoea and weight loss caused by administration of DNBS. 15d-PGJ(2) also caused a substantial reduction of (i) the degree of colonic injury, (ii) the rise in myeloperoxidase (MPO) activity (mucosa), (iii) the increase in the tissue levels of malondialdehyde (MDA) and (iv) of the pro-inflammatory cytokines tumour necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta). 5. Furthermore, 15d-PGJ(2) reduced the increase in immunohistochemical staining for (i) inducible nitric oxide synthase (iNOS), (ii) nitrotyrosine and (iii) poly (ADP-ribose) polymerase (PARP), as well as (iv) the increased expression of ICAM-1 caused by DNBS in the colon. 6. Electrophoresis mobility shift assay (EMSA) of inflamed colon revealed that 15d- PGJ(2) also caused a substantial reduction of the activation of nuclear factor-kappaB (NF-kappaB). Furthermore, 15d-PGJ(2) stimulates the activation of heat shock protein 72 (hsp72) in the inflamed colon, as assessed by Western blot analysis. 7. In conclusion, 15d-PGJ(2) reduces the development of experimental colitis.

Antinociceptive and Antiinflammatory Effects of Niga-ichigoside F1 and 23-Hydroxytormentic Acid Obtained from Rubus coreanus

As an attempt to search for bioactive natural constituents exerting antinociceptive and antiinflammatory activities, we examined the potency of the extract of Rubus coreanus fruits by the activity-guided fractionation. The EtOAc- and BuOH fraction and those alkaline hydrolysates showed significant antinociceptive effects as assessed by writhing-, hot plate- and tail flicks tests in mice and rats as well as antiinflammatory effect in rats with carrageenan-induced edema. BuOH extract was subjected to column chromatography to obtain a large amount of niga-ichigoside F(1) (1,23-hydroxytormentic acid 28-O-glc), which was again hydrolyzed in NaOH solution to yield an aglycone 23-hydroxytormentic acid (1a). The aglycone, 23-hydroxytormentic acid, was much more potent in both antinociceptive and antiinflammatory tests than the glycoside, niga-ichigoside F(1). The antiinflammatory effects of these compounds were further supported by the reduction of carrageenan-induced lipid peroxidation and hydroxyl radical in serum. These results suggested that 23-hydroxytormentic acid might be an active moiety of niga-ichigoside F(1) present in R. coreanus.

Review article: oxidative stress as a pathogenic factor in inflammatory bowel disease--radicals or ridiculous?

Virtually all inflammatory mediators investigated to date seem to be dysregulated in the inflamed intestinal mucosa of patients with inflammatory bowel disease. However, which of these are actually involved in the initiation and perpetuation of intestinal tissue damage is still not fully understood. Amongst these mediators are the reactive oxygen metabolites, produced in large amounts by the massively infiltrating leucocytes. These reactive oxygen metabolites are believed to constitute a major tissue-destructive force and may contribute significantly to the pathogenesis of inflammatory bowel disease. This paper provides a concise overview of reactive oxygen metabolite biochemistry, the types of cell and tissue damage potentially inflicted by them, and the endogenous antioxidants which should prevent these harmful effects. An up-to-date summary of the available human experimental data suggests that reactive oxygen metabolite-mediated injury is important in both the primary and downstream secondary pathophysiological mechanisms underlying intestinal inflammation. Nonetheless, how the individual components of the mucosal antioxidant enzymatic cascade respond to inflammatory conditions is a neglected area of research. This particular aspect of intestinal mucosal oxidative stress therefore merits further study, in order to provide a sound, scientific basis for the design of antioxidant-directed treatment strategies for inflammatory bowel disease patients.

Beneficial effects of GW274150, a novel, potent and selective inhibitor of iNOS activity, in a rodent model of collagen-induced arthritis

The aim of this study was to investigate the role of inducible nitric oxide synthase (iNOS) on the modulation of the inflammatory response in mice subjected to collagen-induced arthritis. Collagen-induced arthritis was induced in wild-type mice (iNOS-WT) treated with GW274150, a novel, potent and selective inhibitor of iNOS activity, and in mice lacking the gene for iNOS (iNOS 'knock-out', iNOS-KO), by an intradermal injection of 100 microl of emulsion containing 100 microg of bovine type II collagen and complete Freund's adjuvant at the base of the tail. After 21 days, a second injection of type II collagen in complete Freund's adjuvant was administered. iNOS-WT mice developed erosive hind paw arthritis when immunised with type II collagen in complete Freund's adjuvant. Over a 35-day period, macroscopic clinical evidence of collagen-induced arthritis first appeared as periarticular erythema and oedema in the hind paws. By day 28, the incidence of collagen-induced arthritis was 100% in type II collagen-challenged iNOS-WT mice and the severity of collagen-induced arthritis progressed with radiographic evaluation revealing resorption of bone. Histopathology of collagen-induced arthritis mice demonstrated erosion of the cartilage at the joint margins. iNOS-WT mice treated with GW274150 (5 mg/kg, i.p. daily) starting at the onset of arthritis (day 23), and iNOS-KO mice showed a delay of the development of the clinical signs at days 24-35 and an improvement of the histological status in the knee and paw. Immunohistochemical analysis for nitrotyrosine and for poly(ADP-ribose) polymerase revealed positive staining in inflamed joints from type II collagen-treated iNOS-WT mice. The degree of staining for nitrotyrosine and poly(ADP-ribose) polymerase were markedly reduced in tissue sections obtained from type II collagen-treated iNOS-WT mice, who had received GW274150 and from iNOS-KO mice. Furthermore, radiographic signs of protection against bone resorption were present in the joints of iNOS-WT mice treated with GW274150 as well as in the joint from iNOS-KO mice. This study provides the first evidence that GW274150, a novel, potent and selective inhibitor of iNOS activity, attenuates the degree of chronic inflammation and tissue damage associated with collagen-induced arthritis in mice. Furthermore, these results suggest that the induction of iNOS and NO production are essential for the up-regulation of the inflammatory response during experimental collagen-induced arthritis.

Role of induced nitric oxide in the initiation of the inflammatory response after postischemic injury

The aim of this study was to investigate the role of inducible nitric oxide (NO) synthase (iNOS) and NO on the modulation of the inflammatory response caused by splanchnic ischemia and reperfusion. A severe model of mesenteric ischemia and reperfusion was produced by subjecting mice to 45 min occlusion followed by reperfusion of the superior mesenteric artery and celiac trunk. In this experimental protocol, wild-type mice treated with GW274150 (5 mg/kg i.p.), a novel, potent, and selective inhibitor of iNOS activity, and mice lacking of the gene for iNOS (iNOS 'knock-out', iNOS-KO) exhibited no difference in the rate of mortality in comparison with wild-type control mice. In a second study, using a less severe model of mesenteric injury obtained by occlusion of the superior mesenteric artery only for 45 min, we evaluated the survival rate. Under these conditions, wild-type mice treated with GW274150 and iNOS-KO mice showed a significant difference in the rate of mortality in comparison with wild-type. Therefore, wild-type mice treated with GW274150 and iNOS-KO mice when compared with wild-type littermates showed a significant reduction of the mesenteric injury, upregulation of P-selectin and intercellular adhesion molecule-1, and neutrophil infiltration, as well as a significant inhibition of the degree of oxidative and nitrosative damage, indicated by malondialdehyde levels, formation of nitrotyrosine and poly(ADP-ribose)polymerase (PARP), respectively. Plasma levels of the proinflammatory cytokines tumour necrosis factor-alpha, interleukin (IL) 6, and IL-1beta were also significantly reduced in iNOS-KO mice in comparison with control wild-type mice. Wild-type mice treated with GW274150 and iNOS-KO mice were also found to have reduced activation of the transcriptional factor nuclear factor-kappaB in the ileum. These results suggest that the induction of iNOS and NO production are essential for the upregulation of the inflammatory response in splanchnic ischemia/reperfusion and participate in end organ damage under these conditions.

GPI 6150, a PARP inhibitor, reduces the colon injury caused by dinitrobenzene sulfonic acid in the rat

Poly (ADP-ribose) polymerase, a nuclear enzyme activated by DNA strand breaks, has been shown to play an important role in the pathogenesis of inflammatory bowel disease. Here we investigate the effects of 1,11b-dihydro-[2H]benzopyrano [4,3,2-de]isoquinolin-3-one (GPI 6150), a new poly (ADP-ribose) polymerase inhibitor, in animal models of experimental colitis. Colitis was induced in rats by intra-colonic instillation of dinitrobenzene sulfonic acid. Rats experienced hemorrhagic diarrhea and weight loss. At 4 days after administration of dinitrobenzensulfonic acid, the mucosa of the colon exhibited large areas of necrosis. Neutrophil infiltration (determined by histology and an increase in myeloperoxidase activity in the mucosa) was associated with up-regulation of ICAM-1. Immunohistochemistry for poly (ADP-ribose) showed an intense staining in the inflamed colon. GPI 6150 (20 or 40 mg/kg daily, i.p.) significantly reduced the degree of hemorrhagic diarrhea and weight loss caused by administration of dinitrobenzensulfonic acid. GPI 6150 also caused a substantial reduction of (i) the degree of colon injury, (ii) the rise in myeloperoxidase activity (mucosa), (iii) the increase in the tissue levels of malondialdehyde, (iv) the increase in staining (immunohistochemistry) for poly (ADP-ribose), as well as (v) the upregulation of ICAM-1 and P-selectin caused by dinitrobenzensulfonic acid in the colon. Thus, GPI 6150 reduces the degree of colitis caused by dinitrobenzensulfonic acid. We propose that GPI 6150 may be useful in the treatment of inflammatory bowel disease.

The cyclopentenone prostaglandin 15-deoxy-Delta(12,14)-prostaglandin J(2) attenuates the development of acute and chronic inflammation

Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily of ligand-activated transcription factors that are related to retinoid, steroid, and thyroid hormone receptors. The PPAR-gamma receptor subtype seems to play a pivotal role in the regulation of cellular proliferation and inflammation. Recent evidence also suggests that the cyclopentenone prostaglandin (PG) 15-deoxyDelta(12,14)-PGJ(2) (15d-PGJ(2)), which is a metabolite of prostaglandin D(2), functions as an endogenous ligand for PPAR-gamma. We postulated that 15d-PGJ(2) would attenuate inflammation. In the present study, we have investigated the effects of 15d-PGJ(2) of acute and chronic inflammation (carrageenan-induced pleurisy and collagen-induced arthritis, respectively) in animal models. We report for the first time, to our knowledge, that 15d-PGJ(2) (given at 10, 30, or 100 microg/kg i.p. in the pleurisy model or at 30 microg/kg i.p every 48 h in the arthritis model) exerts potent anti-inflammatory effects (e.g., inhibition of pleural exudate formation, mononuclear cell infiltration, delayed development of clinical indicators, and histological injury) in vivo. Furthermore, 15d-PGJ(2) reduced the increase in the staining (immunohistochemistry) for nitrotyrosine and poly (ADP-ribose) polymerase and the expression of inducible nitric-oxide synthase and cyclooxygenase-2 in the lungs of carrageenan-treated mice and in the joints from collagen-treated mice. Thus, 15d-PGJ(2) reduces the development of acute and chronic inflammation. Therefore, the cyclopentenone prostaglandin 15d-PGJ(2) may be useful in the therapy of acute and chronic inflammation.

Protective effects of Celecoxib on lung injury and red blood cells modification induced by carrageenan in the rat

In the present study, we evaluated the effect of Celecoxib, a selective COX-2 inhibitor, in an acute model of lung injury induced by carrageenan administration in the rats. Injection of carrageenan into the pleural cavity of rats elicited an acute inflammatory response characterized by: fluid accumulation in the pleural cavity which contained a large number of polymorphonuclear neutrophils (PMNs) as well as an infiltration of PMNs in lung tissues and subsequent lipid peroxidation, and increased production of prostaglandin E(2) (PGE(2)), tumor necrosis factor alpha (TNFalpha), and interleukin-1beta. All parameters of inflammation were attenuated by Celecoxib. Furthermore, carrageenan induced an upregulation of the adhesion molecules ICAM-1 and P-selectin, as well as nitrotyrosine and poly(ADP-ribose) synthetase (PARS) as determined by immunohistochemical analysis of lung tissues. The degree of staining for the ICAM-1, P-selectin, nitrotyrosine and PARS was reduced by Celecoxib. These results clearly confirmed that COX-2 plays a critical role in the development of the inflammatory response by altering key components of the inflammatory cascade. Therefore, selective inhibitor of COX-2 such as Celecoxib, offers a therapeutic approach for the management of various inflammatory diseases.

Effects of 5-aminoisoquinolinone, a water-soluble, potent inhibitor of the activity of poly (ADP-ribose) polymerase, in a rodent model of lung injury

Poly (ADP-ribose) polymerase (PARP), a nuclear enzyme activated by strand breaks in DNA, plays an important role in the tissue injury associated with ischaemia--reperfusion injury and inflammation. The aim of the present study was to evaluate the effects of a novel and potent inhibitor of PARP activity on neutrophil recruitment in the acute inflammation induced by zymosan-activated plasma. Intra-thoracic administration of zymosan-activated plasma leads to an increase in neutrophil infiltration of the lung at 24hr. The potent PARP inhibitor 5-aminoisoquinolinone (5-AIQ) reduced the degree of lung injury and attenuated the expression of P-selectin and ICAM-1 as well as the recruitment of neutrophils into the injured lung. The up-regulation/expression of P-selectin and ICAM-1 in human endothelial cells exposed to oxidative stress (peroxynitrite) or to a pro-inflammatory cytokine (tumor necrosis factor alpha, TNFalpha) was also attenuated by 5-AIQ. These findings provide the first evidence that the activation of PARS participates in neutrophil-mediated lung injury by regulating the expression of P-selectin and ICAM-1.

Pyrrolidine dithiocarbamate attenuates the development of acute and chronic inflammation

The nuclear factor-kappaB (NF-kappaB) is a transcription factor which plays a pivotal role in the induction of genes involved in physiological processes as well as in the response to injury and inflammation. Dithiocarbamates are antioxidants which are potent inhibitors of NF-kappaB. We postulated that pyrrolidine dithiocarbamate (PDTC) would attenuate inflammation. In the present study we investigate the effects of PDTC in animal models of acute and chronic inflammation (carrageenan-induced pleurisy and collagen-induced arthritis). We report here for the first time that PDTC (given at 100, 30 or 10 mg kg(-1) i.p. in the pleurisy model or at 10 mg kg(-1) i.p. every 48 h in the arthritis model) exerts potent anti-inflammatory effects (e.g. significant reduction of (A) pleural exudate formation, (B) polymorphonuclear cell infiltration, (C) lipid peroxidation, (D) inducible nitric oxide synthase (iNOS) activity and nitric oxide production (E) plasma and pleural exudates levels of interleukin-1beta and tumour necrosis factor-alpha, (F) histological injury and (G) delayed development of clinical indicators). Furthermore, PDTC reduced immunohistochemical evidence of (A) formation of nitrotyrosine, (B) activation of poly (ADP-ribose) polymerase (PARP), (C) expression of iNOS and (D) expression of cyclo-oxygenase-2 (COX-2) in the lungs of carrageenan-treated mice and in the joints from collagen-treated mice. Additionally, Western blotting and immunohistochemical analysis of lung tissue revealed that PDTC prevented degradation of IKB-alpha and translocation of NF-kappaB from the cytoplasm into the nucleus. Taken together, our results clearly demonstrate that prevention of the activation of NF-kappaB by PDTC reduces the development of acute and chronic inflammation. Therefore, inhibition of NF-kappaB may represent a novel approach for the therapy of inflammation.

Pharmacological action of melatonin in shock, inflammation and ischemia/reperfusion injury

A vast amount of circumstantial evidence implicates oxygen-derived free radicals (especially, superoxide and hydroxyl radical) and high-energy oxidants (such as peroxynitrite) as mediators of inflammation, shock and ischemia/reperfusion injury. The aim of this review is to describe recent developments in the field of oxidative stress research. The first part of the review focuses on the roles of reactive oxygen species in shock, inflammation and ischemia/reperfusion injury. The second part of the review described the pharmacological action of melatonin in shock, ischemia/reperfusion, and inflammation. The role of reactive oxygen species: Immunohistochemical and biochemical evidence demonstrate the production of reactive oxygen species in shock, inflammation and ischemia/reperfusion injury. Reactive oxygen species can initiate a wide range of toxic oxidative reactions. These include the initiation of lipid peroxidation, direct inhibition of mitochondrial respiratory chain enzymes, inactivation of glyceraldehyde-3 phosphate dehydrogenase, inhibition of membrane sodium/potassium ATP-ase activity, inactivation of membrane sodium channels, and other oxidative modifications of proteins. All these toxicities are likely to play a role in the pathophysiology of shock, inflammation and ischemia and reperfusion. Treatment with melatonin has been shown to prevent in vivo the delayed vascular decompensation and the cellular energetic failure associated with shock, inflammation and ischemia/reperfusion injury. Reactive oxygen species (e.g., superoxide, peroxynitrite, hydroxyl radical and hydrogen peroxide) are all potential reactants capable of initiating DNA single-strand breakage, with subsequent activation of the nuclear enzyme poly (ADP-ribose) synthetase (PARS), leading to eventual severe energy depletion of the cells, and necrotic-type cell death. Recently, it has been demonstrated that melatonin inhibits the activation of poly (ADP-ribose) synthetase, and prevents the organ injury associated with shock, inflammation and ischemia and reperfusion.

Activation of poly(ADP-ribose) polymerase in severe hemorrhagic shock and resuscitation

This study examines activation of poly(ADP-ribose) polymerase (PARP) in the ileum during hemorrhage and resuscitation and determines if inhibition of PARP reduces organ dysfunction and metabolic acidosis. Awake, nonheparinized rats were hemorrhaged (40 mmHg, 60 min). Resuscitation used Ringer's solution (2 1/3 x shed volume) and packed red blood cells (2/3 shed volume). Ileal PARP activity was elevated at the end of hemorrhage (3.6-fold) and 10 min of resuscitation (5-fold). The subsequent decline in PARP activity observed after 60 min of resuscitation was not due to cleavage by caspase-3. Ileum permeability increased 10-fold and circulating liver enzymes increased 4- to 6-fold following 60 min of resuscitation in animals pretreated with 3-aminobenzoic acid, a structural analog that does not inhibit PARP. Pretreatment with 3-aminobenzamide (3-AB), a PARP inhibitor, reduced these changes, whereas posttreatment with a bolus of 3-AB was ineffective. Metabolic acidosis, accumulation of lactate, and base deficit was reduced by pretreatment with 3-AB. PARP is activated in the ileum by hemorrhage and by resuscitation. Activation of PARP contributes to organ dysfunction in the ileum and liver and appears to be central to the development of metabolic acidosis.

Tyrosine nitration: localisation, quantification, consequences for protein function and signal transduction

The nitration of free tyrosine or protein tyrosine residues generates 3-nitrotyrosine the detection of which has been utilised as a footprint for the in vivo formation of peroxynitrite and other reactive nitrogen species. The detection of 3-nitrotyrosine by analytical and immunological techniques has established that tyrosine nitration occurs under physiological conditions and levels increase in most disease states. This review provides an updated, comprehensive and detailed summary of the tissue, cellular and specific protein localisation of 3-nitrotyrosine and its quantification. The potential consequences of nitration to protein function and the pathogenesis of disease are also examined together with the possible effects of protein nitration on signal transduction pathways and on the metabolism of proteins.

Protective effects of n-acetylcysteine on lung injury and red blood cell modification induced by carrageenan in the rat

Oxidative stress has been suggested as a potential mechanism in the pathogenesis of lung inflammation. The pharmacological profile of n-acetylcysteine (NAC), a free radical scavenger, was evaluated in an experimental model of lung injury (carrageenan-induced pleurisy). Injection of carrageenan into the pleural cavity of rats elicited an acute inflammatory response characterized by fluid accumulation in the pleural cavity that contained many neutrophils (PMNs), an infiltration of PMNs in lung tissues and subsequent lipid peroxidation, and increased production of nitrite/nitrate, tumor necrosis factor alpha, and interleukin 1beta. All parameters of inflammation were attenuated by NAC treatment. Furthermore, carrageenan induced an up-regulation of the adhesion molecules ICAM-1 and P-selectin, as well as nitrotyrosine and poly (ADP-ribose) synthetase (PARS), as determined by immunohistochemical analysis of lung tissues. The degree of staining for the ICAM-1, P-selectin, nitrotyrosine, and PARS was reduced by NAC. In vivo NAC treatment significantly reduced peroxynitrite formation as measured by the oxidation of the fluorescent dihydrorhodamine-123, prevented the appearance of DNA damage, an decrease in mitochondrial respiration, and partially restored the cellular level of NAD+ in ex vivo macrophages harvested from the pleural cavity of rats subjected to carrageenan-induced pleurisy. A significant alteration in the morphology of red blood cells was observed 24 h after carrageenan administration. NAC treatment has the ability to significantly diminish the red blood cell alteration. Our results clearly demonstrate that NAC treatment exerts a protective effect and clearly indicate that NAC offers a novel therapeutic approach for the management of lung injury where radicals have been postulated to play a role.

Calpain inhibitor I reduces colon injury caused by dinitrobenzene sulphonic acid in the rat

BACKGROUND AND AIMS

Inflammatory bowel disease is characterised by oxidative and nitrosative stress, leucocyte infiltration, upregulation of expression of intercellular adhesion molecule 1 (ICAM-1), and upregulation of P-selectin in the colon. The aim of the present study was to examine the effects of calpain inhibitor I in rats subjected to experimental colitis.

METHODS

Colitis was induced in rats by intracolonic instillation of dinitrobenzene sulphonic acid (DNBS).

RESULTS

Rats experienced haemorrhagic diarrhoea and weight loss. Four days after administration of DNAB, the mucosa of the colon exhibited large areas of necrosis. Neutrophil infiltration (determined by histology as well as by an increase in myeloperoxidase activity in the mucosa) was associated with upregulation of ICAM-1 and P-selectin as well as high tissue levels of malondialdehyde. Immunohistochemistry for nitrotyrosine and poly (ADP-ribose) polymerase (PARP) showed intense staining in the inflamed colon. Staining of sections of colon obtained from DNBS treated rats with an anti-cyclooxygenase 2 antibody showed diffuse staining of the inflamed tissue. Furthermore, expression of inducible nitric oxide synthase was found mainly in macrophages located within the inflamed colon of DNBS treated rats. Calpain inhibitor I (5 mg/kg daily intraperitoneally) significantly reduced the degree of haemorrhagic diarrhoea and weight loss caused by administration of DNBS. Calpain inhibitor I also caused a substantial reduction in (i) degree of colon injury, (ii) rise in myeloperoxidase activity (mucosa), (iii) increase in tissue levels of malondialdehyde, (iv) increase in staining (immunohistochemistry) for nitrotyrosine and PARP, as well as (v) upregulation of ICAM-1 and P-selectin caused by DNBS in the colon.

CONCLUSION

Calpain inhibitor I reduces the degree of colitis caused by DNBS. We propose that calpain inhibitor I may be useful in the treatment of inflammatory bowel disease.

IL-4 plays a crucial role in regulating oxidative damage in the liver during schistosomiasis

Liver enlargement and hepatocyte proliferation, normal responses in wild-type (WT) mice infected with the parasitic helminth Schistosoma mansoni, were found to be severely impaired in infected IL-4(-/-) mice. Compared with WT mice, increased levels of O(2)(-), NO, and the more highly reactive ONOO(-) were detected in the liver and produced by lesional cells isolated from liver granulomas of infected IL-4(-/-) mice. Concurrently, antioxidant defenses in the liver, specifically catalase levels, diminished dramatically during the course of infection in these animals. This contrasted to the situation in infected WT mice, where catalase levels remained as high as those in normal mice. Actual levels of reactive oxygen and nitrogen intermediates in the livers of infected IL-4(-/-) animals are thus likely to be considerably higher than those in the livers of infected WT mice. To determine whether these changes contributed to the development of the more severe disease that characterizes infection in the IL-4(-/-) animals, we treated infected IL-4(-/-) mice with uric acid, a potent scavenger of ONOO(-). This resulted in significantly increased hepatocyte proliferation, decreased morbidity, and prolonged survival. Taken together, these data indicate that IL-4 is playing a protective role during schistosomiasis by controlling the tight regulation of the generation of reactive oxygen and nitrogen intermediates in the liver.