Oxidative stress in septic shock and disseminated intravascular coagulation

Free Radical Biology & Medicine, Vol. 33, No. 9, pp. 1173–1185, 2002 Copyright © 2002 Elsevier Science Inc. Printed in the USA. All rights reserved 0891-5849/02/$–see front matter

PII S0891-5849(02)00961-9

Serial Review: Vascular Dysfunction and Free Radicals Guest Editor: Toshikazu Yoshikawa OXIDATIVE STRESS IN SEPTIC SHOCK AND DISSEMINATED INTRAVASCULAR COAGULATION DANIELA SALVEMINI*

and

SALVATORE CUZZOCREA†

†

*Metaphore Pharmaceuticals, St. Louis, MO, USA; and Institute of Pharmacology, University of Messina, Messina, Italy (Received 6 March 2002; Accepted 16 May 2002)

Abstract—Oxidative stress results from an oxidant/antioxidant imbalance, an excess of oxidants and/or a depletion of antioxidants. A considerable body of recent evidence suggests that oxidant stress plays a major role in several aspects of septic shock and disseminated intravascular coagulation (DIC), and it is the subject of this review. Immunohistochemical and biochemical evidence demonstrate the significant role of reactive oxygen species (ROS) in endotoxic and hemorrhagic shock, and in endothelial injury associated with DIC syndrome. Initiation of lipid peroxidation, direct inhibition of mitochondrial respiratory chain enzymes, inactivation of glyceraldehyde-3-phosphate dehydrogenase, inhibition of membrane Na⫹/K⫹ ATP-ase activity, inactivation of membrane sodium channels, and other oxidative protein modifications contribute to the cytotoxic effect of ROS. In addition, reactive oxygen species are potent triggers of DNA strand breakage, with subsequent activation of the nuclear enzyme poly-ADP ribosyl synthetase, with eventual severe energy depletion of the cells. Pharmacological evidence suggests that the peroxynitrite-poly-ADP ribosyl synthetase pathway contributes to the cellular injury in shock and endothelial injury. Treatment with superoxide dismutase mimetics (SODms), which selectively mimic the catalytic activity of the human superoxide dismutase enzymes, have been shown to prevent in vivo shock and the cellular energetic failure associated with shock. © 2002 Elsevier Science Inc. Keywords—Free radicals, Superoxide, Superoxide dismutase mimetics, Catecholamines, Adrenochromes

INTRODUCTION

contrast to SOD1 [4] and SOD3 [5], the SOD2 knockout is lethal to mice [6,7]. Thus, endogenous SOD enzymes keep superoxide under very tight control. However, in many disease states there is an imbalance between the amount of superoxide formed and the ability of SOD enzyme to remove them: this leads to superoxide-driven damage (see later). While hydrogen peroxide does not possess an unpaired electron and, therefore, is not a free radical per se, it is usually classified as a reactive oxygen intermediate or species. Hydrogen peroxide can diffuse through membranes and has a half-life much longer than that of superoxide. Hydrogen peroxide has several fates intracellularly. It can be metabolized by one or two antioxidative enzymes, i.e., glutathione peroxidase or catalase, and, in the worst case scenario, in the presence of the transition metals Fe2⫹ or Cu1⫹, it is decomposed to hydroxyl radicals via the Fenton reaction [4]. Although hydroxyl radicals are reactive and highly toxic, their role(s) in disease states is not known. In some cases, these newly formed radicals can be

Free radicals are molecules or portions thereof, which possess one or more unpaired electrons in their outer orbital, a state that greatly increases their reactivity [1,2]. The best-known reactive species generated from oxygen include superoxide anion, hydroxyl radical, and peroxynitrite. Superoxide is enzymatically reduced to hydrogen peroxide in the presence of a ubiquitously distributed enzyme, superoxide dismutase (SOD) [3]. There are two forms of SOD: the Mn enzyme present in mitochondria (SOD2) and the Cu/Zn enzyme present in the cytosol (SOD1) and extracellular surfaces (SOD3). The importance of SOD2 is highlighted by the findings that in This article is part of a series of reviews on “Vascular Dysfunction and Free Radicals.” The full list of papers may be found on the homepage of the journal. Address correspondence to: Dr. Daniela Salvemini, Metaphore Pharmaceuticals, 1910 Innerbelt Business Center Drive, St. Louis, MO 63114, USA; Tel: (314) 426-4803; Fax: (314) 426-7491; E-Mail: [email protected]. 1173

1174

D. SALVEMINI and S. CUZZOCREA

toxic and, in fact, may initiate other damaging free radical reactions. An example of this type of chain reaction is lipid peroxidation, where the lipid peroxyl radical, once produced, abstracts a hydrogen atom from a neighboring polyunsaturated fatty acid to continue the process, converting itself into a lipid peroxide. The end result of extensive lipid peroxidation is cell death. A radical can also interact with another radical to form a stable molecule. This is what happens when superoxide reacts with nitric oxide to form peroxynitrite [8]. While the biological activity and decomposition of peroxynitrite is very much dependent on the cellular or chemical environment (presence of proteins, thiols, glucose, the ratio of nitric oxide and superoxide, carbon dioxide levels, and other factors) it is becoming clear that in most cases peroxynitrite is proinflammatory (for reviews see [8 –11]). PRODUCTION AND ROLE OF FREE RADICALS IN SEPTIC SHOCK

The incidence of severe microbial sepsis associated with shock has progressively increased over the last decade, with approximately 500,000 new cases of sepsis now occurring annually in the United States, accounting for an estimated 5 to 10 billion dollars in annual health care expenditures [12]. The mechanisms involved in shock and organ injury induced in septic shock are multifactorial. Diverse molecular mechanisms of inflammation and cellular damage have been implicated in the pathogenesis of septic shock and multiple organ failure [13–15], including those related to overt generation of cytokines, eicosanoids, and reactive oxygen species such as nitric oxide, superoxide anions, and peroxynitrite. To date, inhibitors of the synthesis/release or actions of cytokines, eicosanoids, and nitric oxide have not been shown to have beneficial effects on shock or mortality in randomized controlled clinical trials [16]. These results are not surprising in light of the fact that these mediators possess both proinflammatory and anti-inflammatory properties. Thus, although individual mediators of each of these structural classes have been causally implicated in septic shock, each plays important homeostatic functions in the complex host response to a septic challenge. Accordingly, their utility as appropriate therapeutic targets for immunopharmacologic suppression has been questioned [16]. Recently, we have identified a potential role of superoxide in septic shock [17]. Septic shock is characterized by severe hypotension and decreased perfusion to critical organ systems despite increased circulating levels of endogenous catecholamines. A secondary characteristic of this condition is the loss of vascular responses (hyporeactivity) that develops to both endogenous and, presumably, exog-

enously administered catecholamines. Indeed, the clinical treatment of this life-threatening condition consisting of fluid resuscitation therapy coupled with intravenous (i.v.) infusions of the catecholamines dopamine and norepinephrine, is limited as a result of this hyporeactivity [18 –24]. In addition, sepsis, like other inflammatory conditions, results in a large increase in the production of nitric oxide and superoxide anions [25,26] within the body. Overt production of nitric oxide accounts at least in part for endotoxin-induced hyporeactivity and hypotension [27]. However, whereas inhibitors of the inducible form of nitric oxide synthase such as aminoguanidine and N-iminoethyl-L-lysine attenuate hypotension, they do not improve mortality [28 –30]. In addition, results from iNOS knockout mice have been controversial, with some reporting reduced hypotension in shock models and others reporting no effects or detrimental ones [31]. Over the last few years our work has led us to propose that the overt production of superoxide plays a role in the pathological sequelae of septic shock. Firstly superoxide is a proinflammatory mediator. Some of the proinflammatory properties of superoxide pertinent to septic shock include recruitment of neutrophils at sites of inflammation [12,32], formation of chemotactic factors [12,32], DNA damage [12,32], initiation of lipid peroxidation [12,32], and release of proinflammatory cytokines such as tumor necrosis factor-␣ and interleukin 1␤ [12,32] via activation of nuclear factor-␬B [33]. The proinflammatory effects of superoxide are then perpetuated by the formation of peroxynitrite, which also deactivates (upon nitration) superoxide dismutase [34]. Peroxynitrite possesses a number of independent proinflammatory/cytotoxic mechanisms including (i) the initiation of lipid peroxidation, (ii) the inactivation of a variety of enzymes, and (iii) depletion of glutathione. Moreover, peroxynitrite can also cause DNA damage resulting in the activation of the nuclear enzyme poly (ADP-ribose) synthetase (PARS), depletion of nicotinamide adenine dinucleotide (NAD), and adenosine triphosphate (ATP), which lead to irreversible cellular damage as evidenced in septic shock [35]. In in vitro studies, it has been established that antioxidants such as cysteine, glutathione, ascorbic acid, and ␣-tocopherol are scavengers of peroxynitrite and inhibitors of its oxidant capacity [36 – 39]. There is a marked depletion of cellular glutathione in endothelial cells and smooth muscle cells after exposure of endogenously produced or exogenously applied peroxynitrite [40,41] and depletion of all of the above antioxidants in the plasma after exposure to peroxynitrite [42]. Recent studies demonstrate that endogenous glutathione plays an important role in reducing vascular hyporeactivity and endothelial dysfunction in response to peroxynitrite and endotoxic shock. In fact, some data

Oxidative stress in septic shock and DIC

1175

Fig. 1. Deactivation . of catecholamines by superoxide.

support that depletion of endogenous glutathione enhances the cytotoxic effects of hydrogen peroxide and oxyradicals; we have also observed an enhancement of the hydrogen peroxide toxicity in endothelial cells and smooth muscle cells [43]. These findings are in agreement with previous suggestions that glutathione plays an important role in blocking the oxidant-induced injury and, specifically, against the peroxynitrite-induced injury [37,43]. These results point out the importance of intact glutathione pools, as protective mechanisms against the vascular failure under conditions of oxidant stress and shock. There are several ways to improve glutathione status and/or replenish cellular glutathione stores. For instance, cell-permeable glutathione analogues have been described [44]. These strategies may represent alternative or additional approaches to other approaches directed towards the prevention of the loss of vascular patency in shock. As a central element of the network of inflammatory shock mediators, superoxide and/or peroxynitrite contribute significantly to organ dysfunction through multiple mechanisms, as described above. Even so, the most important feature of the shock state that ultimately determines survival is the reversibility of inadequate organ perfusion secondary to loss of vasomotor tone, which in turn leads to reduced venous return, cardiac output, and severe arterial hypotension [14]. In order to overcome such hemodynamic derangements, standard treatment consists of prompt initiation of antibiotics even as hemodynamic abnormalities are addressed by i.v. fluid

resuscitation and exogenously administered catecholamines (dopamine and especially norepinephrine) to preserve or augment blood flow to vital organs (e.g., brain, heart, liver, and kidney). Despite such aggressive therapy, successful outcomes are limited because of the development of vascular hyporeactivity (i.e., the loss of normal vasoconstrictor responses) to exogenously administered dopamine and norepinephrine. This hyporeactivity hampers the ability of the clinician to sustain blood pressure as exhibited in nonsurvivors of septic shock, in which blood pressure continues to drop despite administering progressively larger doses of dopamine and norepinephrine. Such inability to successfully restore and maintain an appropriate blood pressure leads to severe hypoperfusion of critical organs and eventually death. Therefore, if development of sepsis-related vascular hyporeactivity to norepinephrine could be overcome, then the therapeutic administration of norepinephrine would effectively maintain blood pressure, which in turn would attenuate the severity of hypotension. We have recently published experimental evidence suggesting that hyporeactivity to exogenous norepinephrine results from its deactivation by superoxide [45] (Fig. 1). Deactivated norepinephrine will no longer be able to increase blood pressure. Therefore, we have proposed that the use of norepinephrine in septic shock results in a therapeutic paradox: it is one of the most commonly used vasopressors but its vasoconstrictor activity is broken down and deactivated by superoxide as soon as it is infused. Furthermore, we have shown that endotoxin-induced hypo-

1176

D. SALVEMINI and S. CUZZOCREA

Fig. 2. Structure and function of the superoxide dismutase mimetic, M40403.

tension is completely abolished by the administration of M40403, a synthetic and selective (for superoxide) low molecular weight enzyme of superoxide dismutase [46, 47]. Properties of M40403 are shown in Fig. 2. Inhibition of hypotension was attributed to preservation of endogenously released norepinephrine and epinephrine [45]. It has been known since the mid-1970s that superoxide interacts with catecholamines (these are in fact considered antioxidants), converting them to adrenochromes [48,49]. Some evidence exists to support a role of adrenochromes as specific mediators of cytotoxicity and cell damage, although their mechanism(s) of actions at this stage are not known [48,50 –53]. More pertinent to the cardiovascular abnormalities of septic shock is the fact that adrenochromes have been shown to be cardiotoxic and to cause myocardial necrosis [51–53]. If true, such adrenochrome-mediated cardiotoxicity would have adverse consequences for subjects with preexisting compromise of ventricular function and systemic oxygen delivery owing to coronary artery disease, hypertension, and other conditions. Moreover, the possibility exists that adrenochromes may have similarly toxic effects on other organ systems, which may well contribute to the morbidity and mortality of septic shock. Inhibition of endotoxin-induced hypotension by M40403 is associated with a reduction in the plasma levels of adrenochromes [45] (Fig. 1). Based on these results, we have put forward the concept that the use of a superoxide dismutase mimetic represents a new paradigm for the treatment of septic shock; namely, enhancement of host vasopressor responses by attenuation of superoxide-induced auto-oxidation of endogenous and exogenous catecholamines. At this stage the relative contribution of peroxynitrite in septic shock is not known with certainty because

selective inhibitors of this reactive oxygen species have not been used. Nevertheless, peroxynitrite does deactivate catecholamines [54,55], is present in endotoxin shock [47,56,57], and has been implicated in the pathophysiology of shock [58]. Although chemical considerations favor the production in vivo of peroxynitrite, the actual demonstration of the presence or production of peroxynitrite in pathophysiological conditions is far from straightforward. Peroxynitrite rapidly oxidizes the fluorescent probe dihydrorhodamine 123 to rhodamine 123 in vitro [59]. The production of peroxynitrite can be evidenced as increased oxidation of dihydrorhodamine 123 to rhodamine 123 in plasma [56]. Caution should be exercised with this method: oxidation of dihydrorhodamine can be triggered by oxidants other than peroxynitrite (hydroxyl radical, for example). However, a NOS inhibitor inhibitable component of an increased oxidation of dihydrorhodamine can be taken as relatively specific evidence of an effect of peroxynitrite [56,60]. Using this method of detection, a marked, and NOS inhibitor inhibitable increase in the peroxynitrite-dependent conversion of dihydrorhodamine 123 to rhodamine has been demonstrated in zymosan-induced multiple organ failure [61]. The finding that peroxynitrite is produced during zymosan or LPS shock is not surprising in light of the previous evidence for the overproduction of oxygenderived free radicals. Nitrotyrosine formation, and its detection by immunostaining, was initially proposed as a relatively specific means for detecting the “footprint” of peroxynitrite [62]. Recent evidence, however, indicates that certain other reactions can also induce tyrosine nitration; for example, the reaction of nitrite with hypochlorous acid, and the reaction of myeloperoxidase (and certain other peroxidases) with hydrogen peroxide can lead to the formation of nitrotyrosine [63,64]. The phys-

Oxidative stress in septic shock and DIC

1177

Fig. 3. Reactive oxygen species and arterial injury.

iological or pathophysiological relevance of this reaction remains to be further clarified. More recent reviews take an increased nitrotyrosine staining as an indication of “increased nitrosative stress,” rather than a specific marker of peroxynitrite [65]. The formation of nitrotyrosine has recently been demonstrated in various organs of rats subjected to experimental shock; the staining was abolished by treatment of the animals with an iNOS inhibitor and peroxynitrite scavenger [66]. Thus, multiple lines of evidence strongly suggest that peroxynitrite is produced in shock. The exact contribution of peroxynitrite in septic shock awaits preclinical evaluation of agents that remove peroxynitrite, such as the peroxynitrite decomposition catalysts [67]. Some of these are anti-inflammatory [67] and cytoprotective [68] and do protect against endotoxin-induced intestinal damage [69]. Therefore, the evidence implicating the role of peroxynitrite in a given pathophysiological condition can only be indirect. A simultaneous protective effect of superoxide neutralizing strategies and NO synthesis inhibition, coupled with the demonstration of peroxynitrite in the particular pathophysiological condition, can be taken as a strong indication for the role of peroxynitrite. However, it is likely that additional interactions of oxygen- and nitrogen-derived free radicals also contribute to the inflammatory cell injury. ROLE OF FREE RADICALS IN DISSEMINATED INTRAVASCULAR COAGULATION SYNDROME

Disseminated intravascular coagulation (DIC) is a systemic syndrome characterized by enhanced activation

of coagulation with some intravascular fibrin formation and deposition, depending on the degree of activity [70]. First, pathologic studies have repeatedly demonstrated the presence of intravascular fibrin in tissues of patients who had died from an illness associated with evidence of DIC, suggesting causal relationships. Second, cohort studies have indicated an increased mortality in patients with DIC compared with those who have the same underlying disease but no evidence of DIC. And third, experimental studies of DIC associated with sepsis or low-grade activation of coagulation have repeatedly demonstrated that effective inhibition of DIC can indeed reduce mortality. In contrast, many investigators currently believe that it is not DIC, and particularly not fibrin formation itself that is harmful, but rather it is the generation of serine proteases and their potential interactions with proinflammatory mediators that contribute to organ failure and death. The microvasculature is the critical interface for oxygen and energy delivery to the tissues. Thus, any damage to or obstruction of the microvasculature may have potentially harmful consequences. One of the major injuries to arteries in DIC is an impairment of Ca2⫹-regulating mechanisms. Recently, reactive oxygen species formation during shock and ischemia and reperfusion have been linked to multiple effects on Ca2⫹ signaling in both the endothelium and smooth muscle. Therefore, it is likely that the signals affected by reactive oxygen species are important mediators of arterial injury (Fig. 3). The evidence supporting a role in arterial dysfunction is complicated by differences in the type of species examined and variations in experimental protocols. Different sources of reactive ox-

1178

D. SALVEMINI and S. CUZZOCREA

Fig. 4. The inflammatory response to disseminated intravascular coagulation.

ygen species are considered, as well as their physiological impact on the vasculature. Overproduction of superoxide in vascular cells creates both an imbalance in nitric oxide signaling and changes in several intracellular signaling pathways (Fig 3). Superoxide is generated by vascular cells through multiple mechanisms. An important source of extracellular superoxide is the oxidation of xanthine by xanthine oxidase, which binds to glycosaminoglycan sites in the arterial wall [71]. Another source of superoxide in the vasculature is specific NAD(P)H oxidase, which is the primary source for smooth muscle-derived reactive oxygen species [72]. Evidence also exists for the formation of superoxide by nitric oxide synthase and cyclooxygenase in vascular cells when their normal substrate is deficient. Arachidonic acid metabolism mediated by Ca2⫹ and cyclooxygenase has been shown to produce superoxidedependent effects on arterial contractions, suggesting an additional role for cyclooxygenase in superoxide production [73]. Thus, oxidants appear to play a major role in the pathogenesis of the endothelial dysfunction [74]. Disseminated intravascular coagulation, diffuse microvascular injury and obstruction, increased vascular permeability, perfusion failure, and organ dysfunction in sepsis and the associated syndromes may be related in part to widespread endothelial apoptosis. In diseases complicated by DIC, a systemic inflammatory response syndrome is a standard finding (Fig. 4). The generation of proinflammatory cytokines has several consequences for the microvasculature with relation to blood coagulation and DIC. Vascular endothelial cells may be per-

turbed by the action of cytokines such as interleukins (IL) 1, 6, and 8, as well as tumor necrosis factor-␣ [75]. These cytokines change the general anticoagulant phenotype of the endothelium into a procoagulant phenotype, at least under in vitro conditions, resulting in, among other features, reduced expression of thrombomodulin [76] and heparin sulfates [77] as well as potentially upregulating tissue factor [78]. The expression of tissue factor may be the result of nuclear factor-␬B activation induced by binding of activated platelets to neutrophils and mononuclear cells. Increased endothelial permeability facilitates the interaction of transmigrating leukocytes with the subendothelial space, such that extravascular inflammation and coagulation may occur. From studies in human volunteers and in baboons challenged with lethal Escherichia coli, it is known that DIC can be distinguished in various stages, in relation to the degree of procoagulant derangement [79,80]. Recent research has revealed a number of links between inflammation and coagulation. The protein C anticoagulant pathway appears to be the major pathway involved in the cross talk between inflammation and coagulation. Studies indicate that inflammatory mediators can downregulate key components of the pathway through transcriptional control, proteolytic inactivation, and oxidant damage [81,82]. From the initial studies of the protein C pathway, it was apparent that such pathways exhibited both anticoagulant and anti-inflammatory properties [83]. In fact, in vivo and in vitro studies have revealed mechanisms by which the components of the pathway may inhibit inflammatory responses. These in-

Oxidative stress in septic shock and DIC

clude inhibition of cytokine responses to endotoxin, inhibition of leukocyte attachment to the activated endothelium, and inhibition of thrombin and factor Xa generation in the microcirculation where both enzymes can lead to endothelial cell activation, further potentiating the inflammatory response [84 – 88]. Therefore, two separate and likely mechanisms have been proposed to account for the ability of activated protein C to modulate the inflammatory response. In particular: (i) a binding site on mononuclear cells that appeared to be responsible for decreasing the calcium flux in response to endotoxin and for blocking TNF-␣ elaboration has been identified [88], (ii) Activated protein C blocks nuclear factor-␬B nuclear translocation leading to inhibition of the release of proinflammatory cytokines [89]. Taken together, these results provide a variety of mechanisms by which the protein C pathway can protect against the septic or shock response. Activated protein C has also been shown to prevent organ damage in both primate [84] and rodent models of septic shock [87,88]. These results are consistent with phase 2 reports of activated protein C therapy in human sepsis, suggesting a clinical benefit and demonstrating anti-inflammatory activity [85], with several reports of apparent protein C effectiveness in severe sepsis [90]. Activated protein C (Xigris, Eli Lilly, Indianapolis, IN, USA) is now approved for the treatment of severe septic shock. In addition, because the endothelium is in contact with circulating blood, synthesis and expression of one important component of the coagulation pathway, tissue factor (TF), is normally suppressed in these cells [91]. The result of these regulatory mechanisms is a tight control of the coagulation system, such that unwanted intravascular thrombus formation is normally inhibited. Tissue factor forms a complex with coagulation factors VII and VIIa, allowing enzymatic activation of factor X and IX, the substrates for factor VIIa [92] ultimately leading to the generation of thrombin. The importance of tissue factor in triggering intravascular thrombus formation in vivo has been directly shown in a recent study in which endothelial disruption at the site of arterial stenosis, with its attendant exposure of tissue factor present in the subendothelium, resulted in intravascular thrombus formation via direct activation of the extrinsic coagulation pathway [93]. To protect against this unwanted intravascular activation of the coagulation system, normal endothelium lacks tissue factor activity [91,94]. However, several stimuli can affect anticoagulant properties of the endothelium by inducing tissue factor expression on the membrane of endothelial cells [95,96]. Endothelial cells represent both a source and a possible target of oxidants released in the vasculature [97]. At the same time, oxidants are known to activate nuclear transcription factors [98]. Thus, it has been demonstrated

1179

using endothelial cells that a brief period of exposure to oxygen radicals resulted in a significant increase in tissue factor mRNA levels, accompanied by appearance of large tissue factor procoagulant activity [99]. Similarly, in rabbits subjected to coronary artery occlusion and reperfusion, a condition associated with endogenous production of large amounts of oxygen radicals, a marked increase in tissue factor activity in the coronary circulation was observed [99]. In addition to inducing tissue factor expression in endothelial cells, active oxygen species might promote intravascular thrombus formation also by interfering with mechanisms that normally inhibit activation of the coagulation pathway. Earlier studies have shown that lipid peroxides can increase the amount of thrombin produced and can slow down the rate of thrombin decay [100]. Both effects are consequent to inhibition of plasma antithrombin by lipid peroxides formed as a consequence of oxygen radical attack to circulating lipoproteins [101]. Similar susceptibility to oxidant-mediated inactivation has been reported for other key antithrombotic factors, such as alpha-2-antiplasmin [102], plasminogen activator [103], and thrombomodulin [104]. More recently, in a preliminary study it has been shown that endothelial cells exposed to oxygen radicals exhibit, in addition to the induction of tissue factor procoagulant activity, a concomitant marked decrease of tissue factor-pathway inhibitor TFPI activity to almost undetectable levels [105]. TFPI is a protein synthesized by endothelial cells that inhibits the extrinsic coagulation pathway. Theoretically, when the trigger of DIC is stronger or more prolonged than anticoagulation, or when the anticoagulant or fibrinolytic mechanisms fail to protect, fibrin formation may persist and lead to prolonged vascular occlusion. The resulting hypoxia may contribute to organ ischemia and cell death. Systemic hypoxia is known to cause fibrin formation as well. Several studies have indicated that, in the presence of either a defect in an anticoagulant pathway such as thrombomodulin [106], or a defect in the fibrinolytic system [107], hypoxia induced by keeping mice at 8% or less oxygen causes fibrin formation in the lungs. Although, at lower oxygen pressure (6%), fibrin may also accumulate in normal mice [108], these very low oxygen levels are not well tolerated in normal or other mice. Furthermore, it is unknown to what extent fibrin formation occurs in tissues other than the lung. The proposed procoagulant mechanism is enhanced expression of tissue factor by monocytes as a result of enhanced activity of transcription factors such as EGR-1 [109], but it may be possible that endothelial cell-induced tissue factor also plays a role in this process. Nevertheless, it remains to be seen how the presence of fibrin influences the adjacent tissue

1180

D. SALVEMINI and S. CUZZOCREA

and whether inflammation and clotting may facilitate local apoptosis and tissue damage. In addition to intravascular fibrin formation, fibrin may be generated in or transferred to extravascular areas, where it may, in turn, be deposited [110]. For example, adult respiratory distress syndrome (ARDS) is frequently associated with intraalveolar and intravascular fibrin formation [111, 112], most likely a result of both systemic and local mediators of procoagulant reactions. Several studies suggest a direct effect of fibrin on inflammatory activity: fibrinogen interacts with bacteria and modulates their activity, fibrin serves to encapsulate bacteria, or fibrin cleavage peptides may trigger the release of proinflammatory cytokines [113]. Thus, in extravascular spaces such as the intraperitoneal cavity or pulmonary tissue, fibrin may be involved in the regulation of inflammatory activity and tissue damage. It remains unknown whether fibrin plays an important role in this regard, and it is entirely unknown whether fibrin has “good” or “bad” properties in localized inflammatory processes. Supranormal oxygen delivery is a controversial form of treatment, based on an equally controversial assumption of abnormal oxygen consumption in sepsis. It has shown some benefit when applied prophylactically, before the onset of septic shock or organ dysfunction [114]. Its beneficial effect could be related to an antiapoptotic effect of increased shear stress [115,116] and to the prevention of adhesion of leukocytes to the endothelium [117]. Both mechanisms may not work if applied too late in the course of disease, when diffuse endothelial injury has already occurred. The administration of an angiotensin-converting enzyme inhibitor as a low-dose-continuous infusion over 5 d to patients with sepsis led to a reduction of soluble markers of endothelial activation and injury, improved oxygenation, reduced neutrophil counts and lactate levels, and decreased incidence of septic shock, and showed a trend toward reduced mortality in a relatively small number of patients [118]. These benefits may be related to the documented reduction of the proapoptotic angiotensin II. Prostacyclin is an endothelial-derived antiapoptotic agent, the normal functions of which include vasodilatation and platelet inhibition [119,120]. Its secretion is reduced in endothelial apoptosis [121]. When administered by inhalation, it has effects similar to those of inhaled nitric oxide: lowering pulmonary arterial pressures and improving oxygenation, but leading additionally to enhanced splanchnic perfusion [122,123]. A recent multicenter trial evaluated the use of ibuprofen in patients with sepsis. This compound led to a reduction in prostacyclin production, and showed no significant effects on outcome [124]. The beneficial effect of cyclooxygenase inhibition may have been outweighed by the negative effects of inhibited prostacyclin production. Several other therapies deserve to be men-

tioned in this context. (i) Antiapoptotic antioxidants have shown some success in ameliorating the inflammatory processes in sepsis [125]. (ii) An experimental model demonstrated an impressive success of the antiapoptotic fibroblast growth factor in reducing mortality associated with lethal endotoxemia [126]. Fibroblast growth factor has been given to humans for other indications, and has not demonstrated prohibitive side effects [127]. (iii) Reduced levels of the antiapoptotic vascular endothelial growth factor have been found in association with severe complications like sepsis or adult respiratory distress syndrome in patients with burns and trauma [128]. Reduced secretion of this endothelial survival factor may have contributed to the severity of disease, and its administration in such circumstances could perhaps lead to enhanced endothelial stability and a reduction in tissue injury. Minor side effects have been encountered during vascular endothelial growth factor use in human atherosclerosis [129]. The large number of proapoptotic factors present in sepsis and the associated syndromes will probably require a combined blockade of several apoptotic pathways, as well as the use of antiapoptotic endothelial growth factors in order to show a benefit in a process as rapid and currently irreversible as fulminant septic shock. The role of free radicals in the no-reflow phenomenon is suggested by several observations in animals and humans. In rat mesenteric venules, free radical scavengers decrease leukocyte-endothelial cell adhesion and albumin leakage after arterial occlusion and reperfusion [130]. In addition, superoxide dismutase enhances survival of ischemic tissue in an ischemic hindlimb model [131]; and transgenic mice overexpressing copper/zinc superoxide dismutase (CuZn-SOD) exhibit less accumulation of leukocytes and less no-reflow than wild-type mice after superior mesenteric artery occlusion and reperfusion [132]. In patients who sustain an acute myocardial infarction, plasma superoxide dismutase activity increases after successful reperfusion of the infarcted vessel and predicts improvement in left-ventricular function [133]. Oxidant stress has also been implicated in the pathogenesis of atherosclerosis. Oxidation of low-density lipoprotein cholesterol facilitates its uptake into the vascular wall [134] and promotes the recruitment of circulating monocytes. Observational studies suggest that individuals who take antioxidant supplements have a lower risk of developing coronary artery disease than those who do not [135,136]; and plasma levels of the antioxidant vitamin E have been shown to be inversely correlated with mortality from coronary artery disease [137]. However, other studies show minimal or even detrimental effects of vitamin E on cardiovascular outcomes [138,139].

Oxidative stress in septic shock and DIC CONCLUSIONS AND FUTURE DIRECTIONS

A growing body of data has emerged supporting a fundamental role of reactive oxygen species and in particular superoxide and/or peroxynitrite in septic shock and disseminated intravascular coagulation. Understanding the signal transduction mechanisms used by these species to modify the course of disease will undoubtedly elucidate important molecular targets for future pharmacological intervention. The development of low molecular weight SOD synzymes such as M40403 might provide the tool necessary to achieve this. These SODm are manganese(II)-containing, nonpeptidic molecules that possess the function and catalytic rate of native SOD enzymes, but with the advantage of being a much smaller molecule (MW 483 vs. MW 30,000 for the mimetic and native enzyme, respectively) [47]. One important property is that they catalytically remove superoxide at a high rate without interacting with other reactive species including nitric oxide, peroxynitrite, hydrogen peroxide, oxygen, or hydroxyl radicals [47,141,142]. This (selectivity) is a feature that is important because it will allow in future studies understanding of the relative roles of superoxide in septic shock and DIC. We have in fact already demonstrated using such agents that deactivation of exogenous and endogenous catecholamines accounts for the hyporeactivity and hypotension (respectively) seen in septic shock. Furthermore, this property (that is the selectivity of the SODm for superoxide) is not shared by other classes of SOD mimetics or scavengers including several metalloporphyrins such as tetrakis-(N-ethyl2-pyridyl) porphyrin and tetrakis-(benzoic acid)porphyrin, that interact with other reactive species such as nitric oxide and peroxinitrite [142]. Superoxide dismutase mimetics may thus offer an important and future line of therapy against septic shock and DIC. Their efficacy in models of septic shock and disseminated intavascular coagulation continues to be evaluated in our laboratories. Of particular interest would be the potential synergistic interaction (s) with drugs such as Xigris, which are now approved for the management of severe septic shock: this will remain to be tested. REFERENCES [1] de Groot, H. Reactive oxygen species in tissue injury. Hepatogastroenterology 41:328 –333; 1994. [2] Kehrer, J. P. Free radicals as mediators of tissue injury and disease. Crit. Rev. Toxicol. 23:21– 43; 1993. [3] McCord, J. M.; Fridovich, I. Superoxide dismutase. An enzymic function for erythrocuprein (hemocuprein). J. Biol. Chem. 244: 6049 – 6055; 1969. [4] Reaume, A. G.; Elliott, J. T.; Hoffman, E. K.; Kowall, N. W.; Ferrante, R. J.; Siwek, D. F.; Wilcox, H. M.; Flood, D. G.; Beal, M. F.; Brown, R. H. Jr.; Scott, R. W.; Snider, W. D. Motor neurons in cu/zn superoxide dismutase-deficient mice develop normally but exhibit enhanced cell death after axonal injury. Nat. Genet. 13:43– 47; 1996.

1181

[5] Carlsson, L. M.; Jonsson, J.; Edlundand, T.; Marklund, S. L. Mice lacking extracellular superoxide dismutase are more sensitive to hyperoxia. Proc. Natl. Acad. Sci. USA 92:6264 – 6268; 1995. [6] Li, Y.; Huang, T. T.; Carlson, E. J.; Melov, S.; Ursell, P. C.; Olson, J. L.; Noble, L. J.; Yoshimura, M. P.; Berger, C.; Chan, P. H. Dilated cardiomyopathy and neonatal lethality in mutant mice lacking manganese superoxide dismutase. Nat. Gent. 11: 376 –381; 1995. [7] Melov, S.; Coskun, P.; Patel, M.; Tuinstra, R.; Cottrell, B.; Jun, A. S.; Zastawny, T. H.; Dizdaroglu, M.; Goodman, S. I.; Huang, T. T.; Miziorko, H.; Epstein, C. J.; Wallace, D. C. Mitochondrial disease in superoxide dismutase 2 mutant mice. Proc. Natl. Acad. Sci. USA 96:846 – 851; 1999. [8] Beckman, J. S.; Beckman, T. W.; Chen, J.; Marshall, P. A.; Freman, B. A. Apparent hydroxyl radical production by peroxynitrite: implication for endothelial injury from nitric oxide and superoxide. Proc. Natl. Acad. Sci. USA 87:1620 –1624; 1990. [9] Rubbo, H.; Radi, R.; Trujillo, M.; Telleri, R.; Kalyanaraman, B.; Barnes, S.; Kirk, M.; Freeman, B. A. Nitric oxide regulation of superoxide and peroxynitrite-dependent lipid peroxidation. Formation of novel nitrogen-containing oxidized lipid derivatives. J. Biol. Chem. 269:26066 –26075; 1994. [10] Villa, L. M.; Salas, E.; Darley-Usmar, M.; Radomski, M. W.; Moncada, S. Peroxynitrite induces both vasodilatation and impaired vascular relaxation in the isolated perfused rat heart. Proc. Natl. Acad. Sci. USA 91:12383–12387; 1994. [11] Salvemini, D.; Jensen, M. P.; Riley, D. P.; Misko, T. P. Therapeutic manipulation of peroxynitrite. Drug News Perspect. 11: 204 –214; 1998. [12] Centers for Disease Control and Prevention, National Center for Health Statistics. Mortality patterns—United States, 1990. Mon. Vital Stat. Rep. 41:45; 1993. [13] Matuschak, G. M. Multiple organ system failure: clinical expression, pathogenesis, and therapy. In: Hall, J. B.; Schmidt, G. A.; Wood, L. D. H., eds. Principles of critical care, 2nd ed. New York: McGraw-Hill; 1998:221–248. [14] American College of Chest Physicians/Society of Critical Care Medicine Consensus Conference. Definitions for sepsis and organ failure and guidelines for the use of innovative therapies in sepsis. Crit. Care Med. 20:864 – 874; 1992. [15] de Warra, I.; Jaccard, C.; Corradin, S. B.; Chiolero, R.; Yersin, B.; Gallati, H.; Assicot, M.; Bohoun, C.; Baumgartner, J. D.; Glauser, M. P.; Heumann, D. Cytokines, nitrite/nitrate, soluble tumor necrosis factor receptors and procalcitonin concentrations: comparisons in patients with septic shock, cardiogenic shock and bacterial pneumonia. Crit. Care Med. 25:607– 613; 1997. [16] Zeni, F.; Freeman, B.; Natanson, C. Anti-inflamamtory therapies to treat sepsis and septic shock. Crit. Care Med. 25:1095–1100; 1997. [17] Salvemini, D.; Riley, D. P.; Lennon, P. J.; Wang, Z. Q.; Currie, M. G.; Macarthur, H.; Misko, T. P. Protective effects of a superoxide dismutase mimetic and peroxynitrite decomposition catalysts in endotoxin-induced intestinal damage. Br. J. Pharmacol. 127:685– 692; 1999. [18] Siegel, J. H.; Greenspan, M.; Del Guercio, L. R. M. Abnormal vascular tone, defective oxygen transport and myocardial failure in human septic shock. Ann. Surg. 165:504 –551; 1967. [19] Parker, M. M.; Shelhamer, J. H.; Bacharach, S. L. Profound but reversible myocardial depression in patients with septic shock. Ann. Intern. Med. 100:483– 490; 1984. [20] Groeneveld, A. B. J.; Bronsveld, W.; Thijs, L. G. Hemodynamic determinants of mortality in human septic shock. Surgery 99: 140 –152; 1986. [21] Thiemermann, C. The role of the L-arginine: nitric oxide pathway in circulatory shock. Adv. Pharmacol. 28:45–79; 1994. [22] Klabunde, R. E.; Ritger, R. C. NG-monomethyl-L-arginine (NMA) restores arterial blood pressure but reduces cardiac output in a canine model of endotoxic shock. Biochem. Biophys. Res. Commun. 178:1135–1140; 1991.

1182

D. SALVEMINI and S. CUZZOCREA

[23] Nava, E.; Palmer, R. M. J.; Moncada, S. Inhibition of nitric oxide synthesis in septic shock: how much is beneficial? Lancet 338:1555–1557; 1991. [24] Wright, C. E.; Rees, D. D.; Moncada, S. Protective and pathological role of nitric oxide in endotoxin shock. Cardiovasc. Res. 26:48 –57; 1992. [25] Ischiropoulos, H.; Zhu, L.; Beckman, J. S. Peroxynitrite formation from macrophage-derived nitric oxide. Arch. Biochem. Biophys. 298:446 – 451; 1992. [26] Taylor, D. E.; Ghio, A. J.; Piantadosi, C. A. Reactive oxygen species produced by liver mitochondria of rats in sepsis. Arch. Biochem. Biophys. 316:70 –76; 1995. [27] Thiemermann, C.; Vane, J. Inhibition of nitric oxide synthesis reduces the hypotension induced by bacterial lipopolysaccharides in the rat in vivo. Eur. J. Pharmacol. 182:591–595; 1990. [28] Parratt, J. R. Nitric oxide. A key mediator in sepsis and endotoxaemia. J. Physiol. Pharmacol. 48:493–506; 1997. [29] Wray, G. M.; Millar, C. G.; Hinds, C. J.; Thiemermann, C. Selective inhibition of the activity of inducible nitric oxide synthase prevents the circulatory failure, but not the organ injury/dysfunction, caused by endotoxin. Shock 9:329 –335; 1998. [30] Thiemermann, C.; Ruetten, H.; Wu, C. C.; Vane, J. R. The multiple organ dysfunction syndrome caused by endotoxin in the rat: attenuation of liver dysfunction by inhibitors of nitric oxide synthase. Br. J. Pharmacol. 116:2845–2851; 1995. [31] Nicholson, S. C.; Grobmyer, S. R.; Shiloh, M. U.; Brause, J. E.; Potter, S.; MacMicking, J. D.; Dinauer, M. C.; Nathan, C. F. Lethality of endotoxin in mice genetically deficient in the respiratory burst oxidase, inducible nitric oxide synthase, or both. Shock 11:253–258; 1999. [32] Cuzzocrea, S.; Riley, D. P.; Caputi, A. P.; Salvemini, D. Antioxidant therapy: a new pharmacological approach in shock, inflammation, and ischemia/reperfusion injury. Pharmacol Rev. 53:135–159; 2001. [33] Liao, J. K.; Libby, P. Nitric oxide and gene transcription. In: Rubanyi, G. M., ed. Pathophysiology and clinical application of nitric oxide. Harwood, NJ: Academic Publishers; 1999:99 –121. [34] Yamakura, F.; Taka, H.; Fujimura, T.; Murayama, K. Inactivation of human manganese-superoxide dismutase by peroxynitrite is caused by exclusive nitration of tyrosine 34 to 3-nitrotyrosine. J. Biol. Chem. 273:14085–14089; 1998. [35] Szabo, C. Nitric oxide, peroxynitrite and poly (ADP-Ribose) synthase: biochemistry and pathophysiological implications. In: Rubanyi, G. M., ed. Pathophysiology and clinical application of nitric oxide. Harwood, NJ: Academic Publishers; 1999:69 –98. [36] Radi, R.; Beckman, J. S.; Bush, K. M.; Freeman, B. A. Peroxynitrite oxidation of sulfhydryls. The cytotoxic potential of superoxide and nitric oxide. J. Biol. Chem. 266:4244 – 4250; 1991. [37] Karoui, H.; Hogg, N.; Frejaville, C.; Tordo, P.; Kalyanaraman, B. Characterization of sulfur-centered radical intermediates formed during the oxidation of thiols and sulfite by peroxynitrite. ESR-spin trapping and oxygen uptake studies. J. Biol. Chem. 271:6000 – 6009; 1996. [38] Vatassery, G. T. Oxidation of vitamin E, vitamin C, and thiols in rat brain synaptosomes by peroxynitrite. Biochem. Pharmacol. 52:579 –586; 1996. [39] Pryor, W. A.; Squadrito, G. L. The chemistry of peroxynitrite: a product from the reaction of nitric oxide with superoxide. Am. J. Physiol. 268:L699 –L722; 1995. [40] Szabo, C.; Zingarelli, B.; Salzman, A. L. Role of poly-ADP ribosyltransferase activation in the nitric oxide- and peroxynitrite-induced vascular failure. Circ Res. 78:1051–1063; 1996. [41] van der Vliet, A.; Smith, D.; O’Neill, C. A.; Kaur, H.; DarleyUsmar, V.; Cross, C. E.; Halliwell, B. Interactions of peroxynitrite with human plasma and its constituents: oxidative damage and antioxidant depletion. Biochem. J. 303:295–301; 1994. [42] Phelps, D. T.; Ferro, T. J.; Higgins, P. J.; Shankar, R.; Parker, D. M.; Johnson, A. TNF-alpha induces peroxynitrite-mediated depletion of lung endothelial glutathione via protein kinase C. Am. J. Physiol. 269:L551–L559; 1995.

[43] Cuzzocrea, S.; Zingarelli, B.; O’Connor, M.; Salzman, A. L.; Szabo, C. Effect of L-buthionine-(S,R)-sulphoximine, an inhibitor of gamma-glutamylcysteine synthetase on peroxynitrite- and endotoxic shock-induced vascular failure. Br. J. Pharmacol. 123:525–537;1998. [44] Morris, P. E.; Wheeler, A. P.; Meyrick, B. O.; Bernard G. R. Escherichia coli endotoxin-mediated endothelial injury is modulated by glutathione ethyl ester. J. Infect. Dis. 172:1119 –1122; 1995. [45] Macarthur, H.; Westfall, T. C.; Riley, D. P.; Misko, T. P.; Salvemini, D. Inactivation of catecholamines by superoxide gives new insights on the pathogenesis of septic shock. Proc. Natl. Acad. Sci. USA 97:9753–9758; 2000. [46] Riley, D. P.; Henke, S. L.; Lennon, P. J.; Weiss, R. H.; Neumann, W. L.; Rivers, W. J.; Aston, K. W.; Sample, K. R.; Ling, C. S.; Shieh, J. J.; Busch, D. H.; Szulbinski, W. Synthesis, characterization and stability of manganese (ii) c-substituted 1,4,7,10,13-pentaazacyclopentadecane complexes exhibiting superoxide dismutase activity. Inorg. Chem. 35:5213–5231; 1996. [47] Salvemini, D.; Wang, Z. Q.; Zweier, J. L.; Samouilov, A.; Macarthur, H.; Misko, T. P.; Currie, M. G.; Cuzzocrea, S.; Riley, D. Synzymes: potent non-peptidic agents against superoxidedriven tissue injury. Science 286:304 –306; 1999. [48] Graham, D. G. Oxidative pathways for catecholamines in the genesis of neuromelanin and cytotoxic quinones. Mol. Pharmacol. 14:633– 643; 1978. [49] Bindoli, A.; Deeble, D. J.; Rigobello, M. P.; Galzigna, L. Direct and respiratory chain-mediated redox cycling of adrenochrome. Biochim. Biophys. Acta 1016:349 –356; 1990. [50] Bindolini, A.; Rigobello, M. P.; Delbli, D. J. Biochemical and toxicological properties of the oxidation products of catecholamines. Free Radic. Biol. Med. 13:391–395; 1992. [51] Yates, J. C.; Beamish, R. E.; Dhalla, N. S. Ventricular dysfunction and necrosis produced by adrenochrome metabolite of epinephrine: relation to pathogenesis of catecholamine cardiomyopathy. Am. Heart. J. 102:210 –221; 1981. [52] Singal, P. K.; Dhillon, R. E.; Beamish, R. E.; Kapur, N.; Dhalla, N. S. Myocardial cell damage and cardiovascular changes due to i.v. infusion of adrenochrome in rats. Br. J. Exp. Pathol. 63: 167–175; 1982. [53] Matthews; S. B.; Hallett, M. B.; Henderson, A. H.; Campbell, A. K. The adrenochrome pathway. A potential catabolic route for adrenaline metabolism in inflammatory disease. Adv. Myocardiol. 6:367–381; 1985. [54] Macarthur, H.; Salvemini, D.; Westfall, T. C. Peroxynitrite is involved in the development of hyporeactivity to norepinephrine in endotoxemia. FASEB J. 13:A757-48; 1999. [55] Daveu, C.; Servy, C.; Dendane, M.; Marin, P.; Ducrocq, C. Oxidation and nitration of catecholamines by nitrogen oxides derived from nitric oxide. Nitric Oxide 1:234 –243; 1997. [56] Szabo, C.; Salzman, A. L.; Ischiropoulos, H. Peroxynitritemediated oxidation of dihydrorodamine 123 occurs in early stages of endotoxic and hemorrhagic shock and ischemia reperfusion injury. FEBS Lett. 372:229 –232; 1995. [57] Szabo, C.; Salzman, A. L.; Ischiropoulos, H. Endotoxin triggers the expression of an inducible isoform of NO synthase and the formation of peroxynitrite in the rat aorta in vivo. FEBS Lett. 363:235–238; 1995. [58] Szabo, C. The pathophysiological role of peroxynitrite in shock, inflammation, and ischemia-reperfusion injury. Shock 6:79 – 88; 1996. [59] Kooy, N.; Royall, J.; Ischiropoulos, H.; Beckman, J. Peroxynitrite-mediated oxidation of dihydrorhodamine 123. Free Radic. Biol. Med. 16:149 –155; 1994. [60] Cuzzocrea, S.; Zingarelli, B.; Costantino, G.; Szabo, A.; Salzman, A. L.; Caputi, A. P.; Szabo, C. Beneficial effects of 3-aminobenzamide, an inhibiltoor of poly (ADP-ribose) synthetase in a rat model of splanchnic artery occlusion and reperfusion. Br. J. Pharmacol. 121:1065–1074; 1997. [61] Cuzzocrea, S.; de Sarro, G.; Costantino, G.; Mazzon, E.; Laura, R.; Ciriaco, E.; de Sarro, A.; Caputi, A. P. Role of interleukin-6

Oxidative stress in septic shock and DIC

[62]

[63]

[64]

[65]

[66]

[67]

[68]

[69]

[70]

[71]

[72]

[73]

[74]

[75] [76]

[77]

[78]

in a non-septic shock model induced by zymosan. Eur. Cytokine Netw. 10:191–203; 1999. Ischiropoulos, H.; Zhu, L.; Chen, J.; Tsai, M.; Martin, J. C.; Smith, C. D.; Beckman, J. S. Peroxynitrite-mediated tyrosine nitration catalyzed by superoxide dismutase. Arch. Biochem. Biophys. 298:431– 437; 1992. Eiserich, J. P.; Cross, C. E.; Jones, A. D.; Halliwell, B.; van der Vliet, A. Formation of nitrating and chlorinating species by reaction of nitrite with hypochlorous acid. A novel mechanism for nitric oxide-mediated protein modification. J. Biol. Chem. 271:19199 –19208; 1996. Eiserich, J. P.; Hristova, M.; Cross, C. E.; Jones, A. D.; Freeman, B. A.; Halliwell, B.; van der Vliet, A. Formation of nitric oxide derivatives catalysed by myeloperoxidase in neutrophils. Nature 391:393–397; 1997. Halliwell, B. What nitrates tyrosine? Is nitrotyrosine specific as a biomarker of peroxynitrite formation in vivo? FEBS Lett. 411:157–160; 1997. Cuzzocrea, S.; Costantino, G.; Mazzon, E.; de Sarro, A.; Caputi, A. P. Beneficial effects of Mn(III)tetrakis (4-benzoic acid) porphyrin (MnTBAP), a superoxide dismutase mimetic, in zymosan-induced shock. Br. J. Pharmacol. 128:1241–1251; 1999. Salvemini, D.; Wang, Z. Q.; Stern, M. K.; Currie, M. G.; Misko, T. B. Peroxynitrite decomposition catalysts: therapeutics for peroxynitrite-mediated pathology. Proc. Natl. Acad. Sci. USA 95:2659 –2663; 1998. Misko, T. P.; Highkin, M. K.; Veenhuizen, A. W.; Manning, P. T.; Stern, M. K.; Currie, M. G.; Salvemini, D. Characterization of the cytoprotective action of peroxynitrite decomposition catalysts. J. Biol. Chem. 273:15646 –15653; 1998. Salvemini, D.; Riley, D. P.; Lennon, P. J.; Wang, Z. Q.; Currie, M. G.; Macarthur, H.; Misko, T. P. Protective effects of a superoxide dismutase mimetic and peroxynitrite decomposition catalysts in endotoxin-induced intestinal damage. Br. J. Pharmacol. 127:685– 692; 1999. Ito, H.; Maruyama, A.; Iwakura, K.; Takiuchi, S.; Masuyama, T.; Hori, M.; Higashino, Y.; Fujii, K.; Minamino, T. Clinical implications of the “no reflow” phenomenon. A predictor of complications and left ventricular remodeling in reperfused anterior wall myocardial infarction. Circulation 93:223–228; 1996. Moncada, S.; Palmer, R. M.; Higgs, E. A. Nitric oxide: physiology, pathophysiology and pharmacology. Pharmacol. Rev. 43:109 –142; 1991. White, C. R.; Darley Usmar, V.; Berrington, W. R.; McAdams, M.; Gore, J. Z.; Thompson, J. A.; Parks, D. A.; Tarpey, M. M.; Freeman, B. A. Circulating plasma xantine oxidase contributes to vascular dysfunction in hypercholesterolemic rabbits. Proc. Natl. Acad. Sci. USA 93:8745– 8749; 1996. Kerr, S.; Brosnan, M. J.; McIntre, M.; Reid, J. L.; Dominiczak, A. F.; Hamilton, C. A. Superoxide anion production is increased in a model of genetic hypertension: role of the endothelium. Hypertension 33:1353–1358; 1999. Kayal, S.; Jais, J. P.; Aguini, N.; Chaudiere, J.; Labrousse, J. Elevated circulating E-selectin, intracellular adhesion molecule 1, von Willebrand factor in pationts with severe infection. Am. J. Respir. Crit. Care Med. 157:776 –784; 1998. Levi, M.; Ten Cate, H. Disseminated intravascular coagulation. N. Engl. J. Med. 341:586 –592; 1999. Cines, D. B.; Pollak, E. S.; Buck, C. A.; Loscalzo, J.; Zimmerman, G. A.; McEver, R. P.; Pober, J. S.; Wick, T. M.; Konkle, B. A.; Schwartz, B. S.; Barnathan, E. S.; McCrae, K. R.; Hug, B. A.; Schmidt, A. M.; Stern, D. M. Endothelial cells in physiology and in the pathophysiology of vascular disorders. Blood 91:3527–3561; 1998. Moore, K. L.; Esmon, C. T.; Esmon, N. L. Tumour necrosis factor leads to the internalization and degradation of thrombomodulin from the surface of bovine aortic endothelial cells in culture. Blood 73:159 –165; 1989. Kobayashi, M.; Ozawa, T.; Shimada, K. Human recombinant interleukin 1b and tumour necrosis factor a mediated suppres-

[79]

[80]

[81]

[82]

[83]

[84]

[85]

[86]

[87]

[88]

[89]

[90]

[91]

[92]

[93]

[94]

[95]

1183

sion of heparin like compounds on cultured porcine aortic endothelial cells. J. Cell Physiol. 144:383–390; 1990. Aiura, K.; Clark, B. D.; Dinarello, C. A.; Margolis, N. H.; Kaplanski, G.; Burke, J. F.; Tompkins, R. G.; Gelfand, J. A. Interaction with autologous platelets multiplies interleukin-1 and tumor necrosis factor production in mononuclear cells. J. Infect. Dis. 175:123–129; 1997. Taylor, F. B. Jr.; Wada, H.; Kinasewitz, G. Description of compensated and uncompensated disseminated intravascular coagulation (DIC) in baloon models of intravevous and intraperitoneal Escherichia coli sepsis and in the human model of endotoxemia: toward a better definition of DIC. Crit. Care Med. 28:S12–S19; 2000. Esmon, C. T. Protein C anticoagulant pathway and its role in controlling microvascular thrombosis and inflammation. Crit. Care Med. 29:S48 –S51; 2001. Faust, S. N.; Heyderman, R. S.; Levin, M. Coagulation in severe sepsis: a central role for thrombomodulin and activated protein C. Crit. Care Med. 29:S62–S67; 2001. Govers-Riemslag, J. W.; Janssen, M. P.; Zwaal, R. F.; Rosing, J. Effect of membrane fluidity and fatty acid composition on the prothrombin-converting activity of phospholipid vesicles. Biochemistry 31:10000 –10008; 1992. Taylor, F. B. Jr.; Chang, A.; Esmon, C. T.; D’Angelo, A.; Vigano-D’Angelo, S.; Blick, K. E. Protein C prevents the coagulopathic and lethal effects of Escherichia coli infusion in the baboon. J. Clin. Invest. 79:918 –925; 1987. Taylor, F.; Chang, A.; Ferrell, G.; Mather, T.; Catlett, R.; Blick, K.; Esmon, C. T. C4b-binding protein exacerbates the host response to Escherichia coli. Blood 78:357–363; 1991. Taylor, F. B. Jr.; Stearns-Kurosawa, D. J.; Kurosawa, S.; Ferrell, G.; Chang, A. C.; Laszik, Z.; Kosanke, S.; Peer, G.; Esmon, C. T. The endothelial cell protein C receptor aids in host defense against Escherichia coli sepsis. Blood 95:1680 –1686; 2000. White, B.; Schmidt, M.; Murphy, C.; Livingstone, W.; O’Toole, D.; Lawler, M.; O’Neill, L.; Kelleher, D.; Schwarz, H. P.; Smith, O. P. Activated protein C inhibits lipopolysaccharide-induced nuclear translocation of nuclear factor kappaB (NF-kappaB) and tumour necrosis factor alpha (TNF-alpha) production in the THP-1 monocytic cell line. Br. J. Haematol. 110:130 –134; 2000. Hancock, W. W.; Tsuchida, A.; Hau, H.; Thomson, N. M.; Salem, H. H. The anticoagulants protein C and protein S display potent anti-inflammatory and immunosuppressive effects relevant to transplant biology and therapy. Transplant Proc. 24: 2302–2303; 1992. Murakami, K.; Okajima, K.; Uchiba, M.; Johno, M.; Nakagaki, T.; Okabe, H.; Takatsuki, K. Activated protein C prevents LPSinduced pulmonary vascular injury by inhibiting cytokine production. Am. J. Physiol. 272:L197–L202; 1997. Smith, O. P.; White, B. Infectious purpura fulminans: caution needed in the use of protein c. Br. J. Haematol. 106:253–254; 1999. Jaffe, E. A. Endothelial cell structure and function. In: Hoffman, R.; Benj, E. J.; Shattil, S. J.; Furie, B.; Cohen, H. J., eds. Hematology: basic principles and practice. New York: Churchill Livingstone; 1991:1198 –1215. Rapaport, S. I.; Rao, L. V. Initiation and regulation of tissue factor-dependent blood coagulation. Arterioscler. Thromb. 12: 1111–1121; 1992. Pawashe, A. B.; Golino, P.; Ambrosio, G.; Migliaccio, F.; Ragni, M.; Pascucci, I.; Chiariello, M.; Bach, R.; Garen, A.; Konigsberg, W. K. A monoclonal antibody against rabbit tissue factor inhibits thrombus formation in stenotic injured rabbit carotid arteries. Circ Res. 74:56 – 63; 1994. Wilcox, J. N.; Smith, K. M.; Schwartz, S. M.; Gordon, D. Localization of tissue factor in the normal vessel wall and in the atherosclerotic plaque. Proc. Natl. Acad. Sci. USA 86:2839 – 2843; 1989. Crossman, D. C.; Carr, D. P.; Tuddenham, E. G.; Pearson, J. D.; McVey, J. H. The regulation of tissue factor mRNA in human

1184

[96]

[97]

[98]

[99]

[100]

[101] [102]

[103]

[104]

[105]

[106] [107]

[108]

[109]

[110]

[111] [112] [113]

D. SALVEMINI and S. CUZZOCREA endothelial cells in response to endotoxin or phorbol ester. J. Biol. Chem. 265:9782–9787; 1990. Kao, J.; Ryan, J.; Brett, G.; Chen, J.; Shen, H.; Fan, Y. G.; Godman, G.; Familletti, P. C.; Wang, F.; Pan, Y. C. Endothelial monocyte-activating polypeptide II. A novel tumor-derived polypeptide that activates host-response mechanisms. J. Biol. Chem. 267:20239 –20247; 1992. Zweier, J. L.; Broderick, R.; Kuppusamy, P.; Thompson-Gorman, S.; Lutty, G. A. Determination of the mechanism of free radical generation in human aortic endothelial cells exposed to anoxia and reoxygenation. J. Biol. Chem. 269:24156 –24162; 1994. Rao, G. N.; Berk, B. C. Active oxygen species stimulate vascular smooth muscle cell growth and proto-oncogene expression. Circ. Res. 70:593–599; 1992. Golino, P.; Ragni, M.; Cirillo, P.; Avvedimento, V. E.; Feliciello, A.; Esposito, N.; Scognamiglio, A.; Trimarco, B.; Iaccarino, G.; Condorelli, M.; Chiariello, M.; Ambrosio, G. Effects of tissue factor induced by oxygen free radicals on coronary flow during reperfusion. Nat. Med. 2:35– 40; 1996. Barrowcliffe, T. W.; Gutteridge, J. M.; Dormandy, T. L. The effect of fatty-acid autoxidation products on blood coagulation. Thromb. Diath. Haemorrh. 33:271–277; 1975. Gray, E.; Barrowcliffe, T. W. Inhibition of antithrombin III by lipid peroxides. Thromb. Res. Suppl. 37:241; 1985. Stief, T. W.; Aab, A.; Heimburger, N. Oxidative inactivation of purified human alpha-2-antiplasmin, antithrombin III, and C1inhibitor. Thromb. Res. Suppl. 49:581–589; 1988. Lawrence, D. A.; Loskutoff, D. J. Inactivation of plasminogen activator inhibitor by oxidants. Biochemistry 25:6351– 6355; 1986. Glaser, C. B.; Morser, J.; Clarke, J. H.; Blasko, E.; McLean, K.; Kuhn, I.; Chang, R. J.; Lin, J. H.; Vilander, L.; Andrews, W. H. Oxidation of a specific methionine in thrombomodulin by activated neutrophil products blocks cofactor activity. A potential rapid mechanism for modulation of coagulation. J. Clin. Invest. 90:2565–2573; 1992. Golino, P.; Ambrosio, G.; Ragni, M.; Cirillo, P.; Scognamiglio, A.; Condorelli, M.; Chiariello, M. Oxygen radicals induce a proacoagulant state in cultured coronary endothelial cells by inducing tissue factor synthesis and by inhibiting tissue-factor pathway inibitor [abstract]. Circulation 92:1354; 1995. Ten Cate, H. Pathophysiology of disseminated intravascular coagualtion in sepsis. Crit. Care Med. 28:S9 –S11; 2000. Healy, A. M.; Hancock, W. W.; Christie, P. D.; Rayburn, H. B.; Rosenberg, R. D. Intravascular coagulation in a murine model of thrombomoduline deficiency: effects of lesion size, age, and hypoxia on fibrin deposition. Blood 92:4188 – 4197; 1998. Pinsky, D. J.; Liao, H.; Lawson, C. A.; Yan, S. F.; Chen, J.; Carmeliet, P.; Loskutoff, D. J.; Stern, D. M. Coordinated induction of plasminogen activator gene expression by hypoxia promotes pulmonary vascular fibrin deposition. J. Clin. Invest. 102:919 –928; 1998. Lawson, C. A.; Yan, S. D.; Yan, S. F.; Liao, H.; Zhou, Y. S.; Sobel, J.; Kisiel, W.; Stern, D. M.; Pinsky, D. J. Monocytes and tissue factor promote thrombosis in a murine model of oxygen deprivation. J. Clin. Invest. 99:1729 –1738; 1997. Yan, S. F.; Zou, Y. S.; Gao, Y.; Zhai, C.; Mackman, N.; Lee, S. L.; Milbrandt, J.; Pinsky, D.; Kisiel, W.; Stern, D. Tissue factor transcription driven by Egr-1 is a critical mechanism of pulmonary fibrin deposition in hypoxia. Proc. Natl. Acad. Sci. USA 95:8298 – 8303; 1998. Abram, E. Coagulation abnormalities in acute lung injury and sepsis. Am. J. Respir. Cell Mol. Biol. 22:401– 404; 2000. McDonald, J. A. The yin and yang of fibrin in the airways. N. Engl. J. Med. 322:929 –931; 1990. Uchiba, M.; Okajima, K.; Murakami, K.; Okabe, H.; Okamoto, S.; Okada, Y. Effects of plasma kallikrein specific inhibitor and active site blocked factor VIIa on the pulmonary vascular injury induced by endotoxin in rats. Thromb. Haemost. 78:1209 –1214; 1997.

[114] Tapper, H.; Herwald, H. Modulation of hemostatic mechanism in bacterial infectious diseases. Blood 96:2329 –2337; 2000. [115] Heyland, D. K.; Cook, D. J.; King, D.; Kernerman, P.; BrunBuisson, C. Maximizing oxygen delivery in critically ill patients: a methodologic appraisal of the evidence. Crit. Care Med. 24: 517–524; 1996. [116] Dimmeler, S.; Haendeler, J.; Nehls, M.; Zeiher, A. M. Suppression of apoptosis by nitric oxide via inhibition of interleukin1b-converting enzyme (ICE)-like and cysteine protease protein (CPP)-32-like proteases. J. Exp. Med. 185:601– 607; 1997. [117] Dimmeler, S.; Haendeler, J.; Rippmann, V.; Nehls, M.; Zeiher, A. M. Shear stress inhibits apoptosis of human endothelial cells. FEBS Lett. 399:71–74; 1996. [118] Neelamegham, S.; Taylor, A. D.; Burns, A. R.; Smith, C. W.; Simon, S. I. Hydrodynamic shear shows distinct roles for LFA-1 and Mac-1 in neutrophil adhesion to intercellular adhesion molecule-1. Blood 92:1626 –1638; 1998. [119] Osterud, B. Tissue factor expression by monocytes: regulation and pathophysiological roles. Blood Coagul. Fibrinolysis 9:S9 – S14; 1998. [120] Boldt, J.; Papsdorf, M.; Kumle, B.; Piper, S.; Hempelmann, G. Influence of angiotensin-converting enzyme inhibitor enaprilat on endothelial-derived substances in the critically ill. Crit. Care Med. 26:1663–1670; 1998. [121] Griedling, K. K.; Alexander, R. W. Cellular biology of blood vessels. In: Alexander, R. W.; Schlant, R. C.; Fuster, V.; O’Rourke, R. A.; Roberts, R.; Sonnenbuck, E. H., eds. Hurst’s the heart, arteries and veins, 9th ed. New York: McGraw Hill; 1998:125–141. [122] Hawrylowicz, C. M.; Howells, G. L.; Feldmann, M. Platelet derived interleukin 1 induces human endothelial adhesion molecule expression and cytokine production. J. Exp. Med. 174: 785–790; 1991. [123] Zwissler, B.; Kemming, G.; Habler, O.; Kleen, M.; Merkel, M.; Haller, M.; Briegel, J.; Welte, M.; Peter, K. Inhaled prostacyclin (PGI2) versus inhaled nitric oxide in adult respiratory distress syndrome. Am. J. Respir. Crit. Care Med. 154:1671–1677; 1996. [124] Eichelbronner, O.; Reinelt, H.; Wiedeck, H.; Mezody, M.; Rossaint, R.; Georgieff, M.; Radermacher, P. Aerosolized prostacyclin and inhaled nitric oxide in septic shock: different effects on splanchnic oxygenation? Intensive Care Med. 22:880 – 887; 1996. [125] Bernard, G. R.; Wheeler, A. P.; Russell, J. A.; Schein, R.; Summer, W. R.; Steinberg, K. P.; Fulkerson, W. J.; Wright, P. E.; Christman, B. W.; Dupont, W. D.; Higgins, S. B.; Swindell, B. B. The effect of ibuprofen on the physiology and survival of patients with sepsis. The Ibuprofen in Sepsis Study Group. N. Engl. J. Med. 336:912–918; 1997. [126] Galley, H. F.; Howdle, P. D.; Walker, B. E.; Webster, N. R. The effects of intravenous antioxidants in patients with septic shock. Free Radic. Biol. Med. 23:768 –774; 1997. [127] Haimovitz-Friedman, A.; Cordon-Cardo, C.; Bayoumy, S.; Garzotto, M.; McLoughlin, M.; Gallily, R.; Edwards, C. K. 3rd; Schuchman, E. H.; Fuks, Z.; Kolesnick, R. Lipopolysaccharide induces disseminated endothelial apoptosis requiring ceramide generation. J. Exp. Med. 186:1831–1841; 1997. [128] Sellke, F. W.; Laham, R. J.; Edelman, E. R.; Pearlman, J. D.; Simons, M. Therapeutic angiogenesis with basic fibroblast growth factor: technique and early results. Ann. Thorac. Surg. 65:1540 –1544; 1998. [129] Grad, S.; Ertel, W.; Keel, M.; Infanger, M.; Vonderschmitt, D. J.; Maly, F. E. Strongly enhanced serum levels of vascular endothelial growth factor (VEGF) after polytrauma and burn. Clin. Chem. Lab. Med. 36:379 –383; 1998. [130] Baumgartner, I.; Pieczek, A.; Manor, O.; Blair, R.; Kearney, M.; Walsh, K.; Isner, J. M. Constitutive expression of phVEGF165 after intramuscular gene transfer promotes collateral vessel development in patients with critical limb ischemia. Circulation 97:1114 –1123; 1998. [131] Kurose, I.; Argenbright, L. W.; Wolf, R.; Lianxi, L.; Granger,

Oxidative stress in septic shock and DIC

[132]

[133]

[134] [135]

[136]

[137]

D. N. Ischemia/reperfusion-induced microvascular dysfuncion: role of antioxidants and lipid mediators. Am. J. Physiol. 272: H2976 –H2982; 1997. Ablove, R. H.; Moy, O. J.; Peimer, C. A.; Severin, C. M.; Sherwin, F. M. Effect of high energy phosphates and free radical scavengers on replant survival in an ischemic extremity model. Microsurgery 17:481– 486; 1996. Horie, Y.; Wolf, R.; Flores, S. C.; McCord, J. M.; Epstein, C. J.; Granger, D. N. Transgenic mice with increased copper/zinc superoxide dismutase activity are resistant to hepatic leukostatis and capillary no-reflow after gut ischemia/reperfusion. Circ. Res. 83:691– 696; 1998. Tomoda, H.; Morimoto, K.; Aoki, N. Superoxide dismutase activity as a predictor of myocardial reperfusion and salvage in acute myocardial infarction. Am. Heart J. 131:849 – 856; 1996. Steinberg, D.; Parthasarathy, S.; Carew, T. E.; Khoo, J. C.; Witztum, J. L. Beyond cholesterol. Modifications of low-density lipoprotein that increase its atherogenecity. N. Engl. J. Med. 320:915–924; 1989. Stampfer, M. J.; Hennekens, C. H.; Manson, J. E.; Colditz, G. A.; Rosner, B.; Willett, W. C. Vitamin E consumption and the risk of coronary disease in women. N. Engl. J. Med. 328:1444 – 1449; 1993. Rimm, E. B.; Stampfer, M. J.; Ascherio, A.; Giovannucci, E.; Colditz, G. A.; Willett, W. C. Vitamin E consumption and the

[138]

[139]

[140]

[141]

[142]

1185

risk of coronary disease in men. N. Engl. J. Med. 328:1450 – 1456; 1993. Guy, K. F.; Puska, P. Plasma vitamins E and A inversely correlated to mortality from ischemic heart disease in crosscultural epidemiology. Ann. N.Y. Acad. Sci. 570:268 –282; 1989. Rapola, J. M.; Virtamo, J.; Ripatti, S.; Huttunen, J. K.; Albanes, D.; Taylor, P. R.; Heinonen, O. P. Randomised trial of alpha tocopherol and beta-carotene supplements on incidence of major coronary events in men with previous myocardial infarction. Lancet 349:1715–1720; 1997. Riley, D. P.; Henke, S. L.; Lennon, P. J.; Weiss, R. H.; Neumann, W. L.; Rivers, W. J.; Aston, K. W.; Sample, K. R.; Ling, C. S.; Shieh, J. J.; Busch, D. H.; Szulbinski, W. Synthesis, characterization and stability of manganese (II) C-substituted 1,4,7,10,13-Pentaazacyclopentadecane complexes exhibiting superoxide dismutase activity. Inorg. Chem. 35:5213–5231; 1996. Riley, D. P.; Lennon, P. J.; Neumann, W. L.; Weiss, R. H. Toward the rational design of superoxide dismutase mimics: mechanistic studies for the elucidation of substituent effects on the catalysis activity of macrocyclic manganese (II) complexes. J. Am. Chem. Soc. 119:6522; 1996. Patel, M.; Day, B. J. Metalloporphyrin class of therapeutic catalyic antioxidants. Trends Pharmacol. Sci. 20:359 –364; 1999.