Depletion of liver glutathione potentiates the oxidative stress and decreases nitric oxide synthesis in a rat endotoxin shock model

Vitexin along with verapamil downregulates efflux pump P-glycoprotein in macrophages and potentiate M1 to M2 switching via TLR4-NF-κB-TNFR2 pathway in lipopolysaccharide treated mice

The lipopolysaccharide, a microbial toxin, is one of the major causative agents of sepsis. P-gp expression and its functions are altered during inflammation. LPS has been known to impair the functions of P-gp, an efflux transporter. But the effect of LPS on P-gp expression in murine peritoneal macrophages is poorly understood. Molecular docking studies reveal that vitexin is a potent substrate and verapamil a potent inhibitor of P-gp. In the present experimental study, the curative potential of vitexin as a fruit component and verapamil treated as a control inhibitor of P-gp was examined in a murine LPS sepsis model. The effects of vitexin and verapamil on P-gp expression in macrophages correlating with changes in macrophage polarization and associated functional responses during LPS induced sepsis were studied. Peritoneal macrophages of LPS (10 mg/kg body weight) challenged mice exhibited elevated levels of H2O2, superoxide, and NO in parallel with lower antioxidant activity. LPS treatment increased P-gp expression through increased TLR4/expression. However, LPS challenged mice treated with vitexin (5 mg/kg body weight) + verapamil (5 mg/kg body weight) showed higher anti-oxidant enzyme activity (SOD, CAT and GRx) resulting in reduced oxidative stress. This combination treatment also elevated TNFR2, concomitant with down-regulation of TLR4, NF-κB and P-gp expression in murine peritoneal macrophages, resulting in a switch from M1 to M2 polarisation of macrophages and reduced inflammatory responses. In conclusion, combined vitexin and verapamil treatment could be used as a promising therapy to regulate P-gp expression and protection against LPS mediated sepsis and inflammatory damages.

Potential therapeutic effect of Carica papaya leaves extract on immune response, biochemical and hematological mechanisms on cecal ligation and puncture model of sepsis in rats: an in vivo study

Antibiotics and immunotherapies possess unavoidable adverse effects that hinder sepsis management. Herbal drugs have demonstrated potential immunomodulatory properties vital for sepsis treatment. We hypothesized in the present study that the use of Carica papaya leaves extract had the potential to improve survival and modulate immune cytokine release during sepsis. Animals were subjected to cecal ligation and puncture (CLP) to induce sepsis. Septic rats divided into 10 groups received ethanol extract of C. papaya leaves (50 and 100 mg/kg), imipenem (120 mg/kg) and cyclophosphamide (CP, 10 mg/kg). To investigate the immunomodulatory potentials of EE, cytokine levels like interleukin (IL-6), tumor necrosis factor (TNF-α), and IL-10 along with hematological and biochemical parameters were analyzed. Our results exhibited improved survival rates concerning ethanol extract treatment alone and in combination with imipenem and CP (100%) as compared to the CLP group (33.3%) on day 7 post-surgery. The combination treatment of ethanol extract with imipenem and CP significantly (P < 0.001) ameliorated cytokine levels and hematological and biochemical parameters in septic rats. A histopathological examination suggested improved liver and kidney tissue condition after combination treatment as compared to the CLP group. Therefore, it was concluded that combination therapy of extract with imipenem and CP improved survival rates and marked immunomodulatory potential in septic rats compared to monotherapy. The findings suggested the use of a mixture of these drugs in clinical settings to treat sepsis.

Evaluation of Dynamic Thiol-Disulfide Balance and Ischemia Modified Albumin Levels in Patients with Chronic Kidney Disease

Objective: We aimed to measure the dynamic thiol-disulfide balance and ischemia modified albumin (IMA) levels in patients with chronic kidney disease (CKD). Materials and methods: Thirty hemodialysis (HD), 30 CKD patients (stage3-5) and 30 controls were included in the study. The dynamic thiol-disulfide balance was determined by the colorimetric method developed by Erel et al. IMA levels were determined by using cobalt binding test developed by Bar- Or et al. Results: Native and total thiol levels of CKD and HD patients were significantly lower than that of the control group (p=0.001for both). However, disulfide levels were significantly higher in the HD group (p=0.001), but there was no significant difference between control and CKD groups(p=0.547). A notable negative correlation was found between the native and total thiol levels and IMA(r=-0.628;-0.631),BUN (r=-0.747;-0.747),and creatinine(r=-0.732;-0.721). There was a significant positive correlation between GFR and the thiol levels (r=0.835;0.824). TrxR levels were significantly higher in the patient groups compared to the controls (p=0.001). CRP levels of the patient groups were significantly higher compared to the controls (p=0.001). Conclusions: We have demonstrated that measurement of dynamic thiol-disulfide levels by using colorimetric method can contribute to the diagnosis and follow-up of the disease as a marker, because, it is easily applicable in routine clinical biochemistry laboratories and related with disease severity in CKD patients. Also, we showed that albumin correction due to dialysis process should be consider in studies dealing with plasma thiol values and the final results should be given after the correction process.

Glutathione Reductase Is Associated with the Clinical Outcome of Septic Shock in the Patients Treated Using Continuous Veno-Venous Haemofiltration

Background and objectives: At present, there is insufficient evidence to support the use of continuous veno-venous haemofiltration (CVVH) in the early treatment of septic shock. This study focuses on the association between survival and different parameters of oxidative stress (RedOx). Thereby, we evaluated whether RedOx markers are associated with the outcome of septic shock in patients under early-initiated CVVH treatment. Materials and Methods: We conducted a prospective observational study of 65 patients with septic shock who started CVVH within 12 h after hospital admission. Blood samples were taken from each patient prior to the start of CVVH. The following RedOx markers were measured: glutathione peroxidase, glutathione reductase (GR), total antioxidant capacity, superoxide dismutase, nitric oxide, malondialdehyde and 4-hydroxynonenal. The odds ratio (OR) was calculated using binary logistic regression and stepwise multivariable regression. Results: The 65 patients had a median age of 66 years and 39 were male. Based on the outcome, the patients were divided into two groups—non-survivors (n = 29) and survivors (n = 36)—and the levels of RedOx markers were compared between them. Of all the markers, only higher GR activity was found to be significantly associated with the fatal outcome; 100.3 U/L versus 60.5 U/L, OR = 1.027 (95% CI, 1.010–1.044). Following adjustment for the sequential organ failure assessment score and other parameters, GR activity still presented a significant association with the fatal outcome, OR = 1.020 (95% CI, 1.002–1.038). Conclusions: GR activity is associated with in-hospital fatal outcomes among septic shock patients under early-initiated CVVH treatment. Septic shock patients who have a lower GR activity at hospital admission may have a favourable outcome of the early initiation of CVVH.

The effects of chrysin on lipopolysaccharide-induced sepsis in rats

Chrysin (CR) is a flavone found in propolis and many plants. Lipopolysaccharide (LPS) is a component of the cell wall of gram-negative bacteria that causes sepsis. The purpose of this study was to investigate the effects of CR on LPS-induced sepsis in rats. LPS intraperitoneal and a single dose and CR were given orally for 10 days. Rats were sacrificed, blood samples were taken, liver, lung, and kidney tissues were dissected, homogenized, and histopathological analysis was carried out. When CR groups compared to sepsis group, CR significantly decreased the serum levels of aspartate transaminase (AST) and alanine aminotransferase (ALT), interleukin-1 beta (IL-1β), interleukin-10 (IL-10), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and levels of malondialdehyde (MDA) in tissues. CR also increased the levels of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) in tissues. Histopathological findings were consistent with biochemical findings. Conclusion, CR could reduce the oxidative stress markers and cytokines in sepsis. PRACTICAL APPLICATIONS: Our approach is to determine the antioxidant and anti-inflammatory effects of chrysin, known as a flavolonoid, which are found in many plants and foods such as honey and propolis. In this study, experimental sepsis model was created using LPS. According to the results of the study, CR can attribute to the ameliorating of oxidative damage in tissues (lung, liver, and kidney) and it can suppress the sepsis-associated acute tissue injury via reduction of inflammation in rats. Even, CR can be used as a pharmacological agent in inflammatory diseases caused by other sources and in many cases causing oxidation.

Identification of potential biomarkers in cholestasis and the therapeutic effect of melatonin by metabolomics, multivariate data and pathway analyses

The present study investigated the anti‑cholestatic effect of melatonin (MT) against α‑naphthyl isothiocyanate (ANIT)‑induced liver injury in rats and screened for potential biomarkers of cholestasis. Rats were administered ANIT by intraperitoneal injection and then sacrificed 36 h later. Serum biochemical parameters were measured and liver tissue samples were subjected to histological analysis. Active components in the serum were identified by gas chromatography‑mass spectrometry, while biomarkers and biochemical pathways were identified by multivariate data analysis. The results revealed that the serum levels of alanine aminotransferase, aspartate aminotransferase, total bilirubin, direct bilirubin, γ‑glutamyl transpeptidase, and alkaline phosphatase were reduced in rats with ANIT‑induced cholestasis that were treated with MT. The histological observations indicated that MT had a protective effect against ANIT‑induced hepatic tissue damage. Metabolomics analysis revealed that this effect was likely to be associated with the regulation of compounds related to MT synthesis and catabolism, and amino acid metabolism, including 5‑aminopentanoate, 5‑methoxytryptamine, L‑tryptophan, threonine, glutathione, L‑methionine, and indolelactate. In addition, principal component analysis demonstrated that the levels of these metabolites differed significantly between the MT and control groups, providing further evidence that they may be responsible for the effects induced by MT. These results provide an insight into the mechanisms underlying cholestasis development and highlight potential biomarkers for disease diagnosis.

Protective effects of geniposide against Tripterygium glycosides (TG)-induced liver injury and its mechanisms

Tripterygium glycosides (TG) are commonly used for basic medicine in curing rheumatoid arthritis but with a high incidence of liver injury. Geniposide (GP) has broad and diverse bioactivities, but until now it is still unknown whether GP can protect against TG-induced liver injury. This study, for the first time, observed the possible protection of GP against TG-induced liver injury in mice and its mechanisms underlying. Oral administration of TG (270 mg/kg) induced significant elevation in the levels of serum alanine / aspartate transaminase (ALT/AST), hepatic malondialdehyde (MDA) and pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-α) (all P < 0.01). On the other hand, remarkably decreased biomarkers, including hepatic glutathione (GSH) level, activities of glutathione transferase (GST), glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase (CAT), and anti-inflammatory cytokine interleukin (IL)-10, were observed following TG exposure (all P < 0.01). Nevertheless, all of these phenotypes were evidently reversed by pre-administration of GP for 7 continuous days. Further analysis showed that the mRNA expression of hepatic growth factor-beta1 (TGF-β1), one of tissue repair and regeneration cytokines, was enhanced by GP. Taken together, the current research suggests that GP protects against TG-induced liver injury in mice probably involved during attenuating oxidative stress and inflammation, and promoting tissue repair and regeneration.

Plasma glutathione reductase activity and prognosis of septic shock

BACKGROUND

Our aim was to investigate whether plasma glutathione reductase (GR) activity is well correlated with the erythrocyte-reduced glutathione (GSH)/glutathione disulfide (GSSG) ratio and is associated with the mortality of septic shock.

MATERIALS AND METHODS

This study was conducted on male Sprague-Dawley rats and patients admitted to the intensive care unit with septic shock. To induce endotoxemia in rats, vehicle or lipopolysaccharide (LPS) at dosages of 5 or 10 mg/kg were injected into a tail vein. Animals were then euthanized 6 h post-LPS. Based on the 28-d mortality, the enrolled patients were divided into the survivors and nonsurvivors. We obtained blood samples from patients at admission (0 h) and 24 h after admission to the intensive care unit.

RESULTS

In endotoxemic rats, the erythrocyte GSH/GSSG ratio, erythrocyte GR activity, and plasma GR activity in the 10 mg/kg of LPS group were lower than those in the sham and 5 mg/kg of LPS groups. In patients with septic shock, decrease in plasma GR activity at 24 h was independently associated with an increase in 28-d mortality (odds ratio, 0.828; 95% confidence interval, 0.690-0.992, P = 0.041). Plasma GR activity was correlated with erythrocyte GR activity (Spearman ρ = 0.549, P < 0.001) and the erythrocyte GSH/GSSG ratio (rho = 0.367, P = 0.009) at 24 h.

CONCLUSIONS

Plasma GR activity was well correlated with erythrocyte GR activity and the erythrocyte GSH/GSSG ratio, and a decrease in plasma GR activity was associated with an increase in the mortality of septic shock patients.

Geniposide protects against acute alcohol-induced liver injury in mice via up-regulating the expression of the main antioxidant enzymes

Geniposide (GP) is one of main compounds in Gardenia jasminoides Ellis, with both medicinal and nutritional value. This study was designed to determine, for the first time, how GP from G. jasminoides protects against acute alcohol-induced liver injury, and the underlying mechanisms. Mice were orally administered alcohol (6.0 g/kg body mass) 2 h after intragastric administration of GP and bifendate, every day for 7 continuous days. Six hours after the alcohol was administered, levels of serum alanine/aspartate transaminase (ALT/AST), hepatic lipid peroxidation (LPO), glutathione (GSH), glutathione-S-transferase (GST), glutathione peroxidase (GPx), copper- and zinc-containing superoxide dismutase (CuZn-SOD), and catalase (CAT), and mRNA expression of CuZn-SOD and CAT were assayed. The results demonstrated that GP (20.0, 40.0, or 80 mg/kg) significantly reversed the excessive, alcohol-induced elevation in both serum ALT/AST and hepatic LPO levels. Moreover, hepatic GSH, GST, GPx, CuZn-SOD, and CAT levels were all decreased in the alcohol-treated mice, whereas treatment with GP reversed these decreases. Further analysis indicated that hepatic mRNA expression of CuZn-SOD and CAT in the alcohol-treated mice was significantly down-regulated, whereas GP up-regulated such decreases. Taken together, this study shows that GP protects against acute alcohol-induced liver injury via up-regulating the expression of the main antioxidant enzymes, and thus ameliorates alcohol-induced oxidative stress injury in the liver.

Biomarkers of oxidative stress study VI. Endogenous plasma antioxidants fail as useful biomarkers of endotoxin-induced oxidative stress

This is the newest report in a series of publications aiming to identify a blood-based antioxidant biomarker that could serve as an in vivo indicator of oxidative stress. The goal of the study was to test whether acutely exposing Göttingen mini pigs to the endotoxin lipopolysaccharide (LPS) results in a loss of antioxidants from plasma. We set as a criterion that a significant effect should be measured in plasma and seen at both doses and at more than one time point. Animals were injected with two doses of LPS at 2.5 and 5 µg/kg iv. Control plasma was collected from each animal before the LPS injection. After the LPS injection, plasma samples were collected at 2, 16, 48, and 72 h. Compared with the controls at the same time point, statistically significant losses were not found for either dose at multiple time points in any of the following potential markers: ascorbic acid, tocopherols (α, δ, γ), ratios of GSH/GSSG and cysteine/cystine, mixed disulfides, and total antioxidant capacity. However, uric acid, total GSH, and total Cys were significantly increased, probably because LPS had a harmful effect on the liver. The leakage of substances from damaged cells into the plasma may have increased plasma antioxidant concentrations, making changes difficult to interpret. Although this study used a mini-pig animal model of LPS-induced oxidative stress, it confirmed our previous findings in different rat models that measurement of antioxidants in plasma is not useful for the assessment of oxidative damage in vivo.

Sildenafil treatment attenuates lung and kidney injury due to overproduction of oxidant activity in a rat model of sepsis: a biochemical and histopathological study

Sepsis is a systemic inflammatory response to infection and a major cause of morbidity and mortality. Sildenafil (SLD) is a selective and potent inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase PDE5. We aimed to investigate the protective effects of sildenafil on caecal ligation and puncture (CLP)-induced sepsis in rats. Four groups of rats were used, each composed of 10 rats: (i) 10 mg/kg SLD-treated CLP group; (ii) 20 mg/kg SLD-treated CLP group; (iii) CLP group; and (iv) sham-operated control group. A CLP polymicrobial sepsis model was applied to the rats. All groups were killed 16 h later, and lung, kidney and blood samples were analysed histopathologically and biochemically. Sildenafil increased glutathione (GSH) and decreased the activation of myeloperoxidase (MPO) and of lipid peroxidase (LPO) and levels of superoxide dismutase (SOD) in the septic rats. We observed a significant decrease in LPO and MPO and a decrease in SOD activity in the sildenafil-treated CLP rats compared with the sham group. In addition, 20 mg/kg sildenafil treatment in the sham-operated rats improved the biochemical status of lungs and kidneys. Histopathological analysis revealed significant differences in inflammation scores between the sepsis group and the other groups, except the CLP + sildenafil 10 mg/kg group. The CLP + sildenafil 20 mg/kg group had the lowest inflammation score. Sildenafil treatment decreased the serum tumour necrosis factor (TNF)-α level when compared to the CLP group. Our results indicate that sildenafil is a highly protective agent in preventing lung and kidney damage caused by CLP-induced sepsis via maintenance of the oxidant-anti-oxidant status and decrease in the level of TNF-α.

Effect of butylated hydroxytoluene (E321) pretreatment versus L-arginine on liver injury after sub-lethal dose of endotoxin administration

Aim of this study was to compare the effects of L-arginine (L-arg) and food-antioxidant butylated hydroxytoluene (BHT) against oxidative stress of Escherichia coli endotoxin (LPS) in liver. Ninety Wistar albino rats were assigned in three groups. Rats received one of the following pre-treatment previous to 5mg/kg LPS intraperitoneally: saline, L-arg (NO donor, 100mg/kg) or BHT (250 mg/kg/day), for 3 days. At second, fourth and sixth hours, plasma nitrite-plus-nitrate, circulating liver enzymes, glutathione levels, superoxide dismutase, glutathione peroxidase activities were measured. The most remarkable liver injury was evident in BHT pre-treated animals at all time points compared to L-arg pre-treated rats. While BHT enhanced superoxide dismutase activities following LPS, glutathione decreased simultaneously compared to L-arg group. Although the risk associated with the use of BHT alone in subthreshold doses appeared to be low, higher risk of liver toxicity should be considered when over-consuming this food additive in endotoxemic settings.

A short overview of vitamin C and selected cells of the immune system

Vitamin C (ascorbic acid) is an essential water-soluble nutrient that primarily exerts its effect on a host defense mechanisms and immune homeostasis and is the most important physiological antioxidant. Stable intake of vitamin C is essential for life in humans because the body does not synthesize it. Even the numerous studies have demonstrated that vitamin C supplementation stimulates the immune system, prevents DNA damage and significantly decreases the risk of a wide range of pathologies; the potential protective mechanisms are still largely unknown. This review summarizes the recently known facts about the role of vitamin C on the selected cells of the immune system and potential molecular mechanisms involved. Further, in this review, many new data about the positive effects of vitamin C on the immune system, potential toxicological effects, vitamin C supplementation in disease development, as well as some proposed mechanisms of vitamin C activity, are discussed.

Gender-related difference in liver injury induced by Dioscorea bulbifera L. rhizome in mice

The present study was undertaken to investigate the gender-related liver injury induced by Dioscorea bulbifera L. (DB), a traditional medicinal plant, in mice, and further explored its hepatotoxic chemical compound. Serum and liver tissue samples were collected at 0, 4, 8, 12 h, after mice were administrated orally with 640 mg/kg ethyl acetate extracts (EF) isolated from DB. After treatments, serum alanine transaminase (ALT) and aspartate transaminase (AST) activities were both significantly elevated. Liver lipid peroxidation (LPO) level increased, while glutathione amounts, glutathione- S-transferase (GST), superoxide dismutase (SOD) and catalase (CAT) activities all decreased in the time-dependent manner. Further analysis demonstrated that ALT and AST activities in female mice were significantly lower than those in male. Meanwhile, liver glutathione amounts and CAT activity in female mice after giving EF for 12 h were both higher than those in male. Further, comparing the liver injury induced by Diosbulbin B isolated from DB with that induced by EF on the basis of chemical analysis for the amounts of Diosbulbin B in EF of DB, we found that Diosbulbin B could be the main hepatotoxic chemical compound in DB. Taken together, our results show that DB can induce gender-related liver oxidative stress injury in mice, and its main hepatotoxic chemical compound is Diosbulbin B, for the first time.

N-acetylcysteine Protects Mice from Lethal Endotoxemia by Regulating the Redox State of Immune Cells

The excessive production of reactive oxygen species (ROS) associated with inflammation leads to oxidative stress, which is involved with the high mortality from several diseases such as endotoxic shock and can be controlled to a certain degree by antioxidants. The immune cells use ROS in order to support their functions and, therefore, need adequate levels of antioxidant defenses in order to avoid the harmful effect of an excessive ROS production. In the present work, the effect of the administration of the antioxidant N-acetylcysteine (NAC) on the redox state of peritoneal macrophages and lymphocytes from mice with lethal endotoxic shock (100 mg/kg i.p. of lipopolysaccharide, LPS), was studied. In both types of immune cells at 0, 2, 4, 12 and 24 h after LPS injection, an increase of ROS, of the proinflammatory cytokine tumor necrosis factor alpha (TNFalpha), the lipid peroxidation (malonaldehyde levels, MDA), inducible nitric oxide synthase (iNOS) expression and the oxidized/reduced glutathione (GSSG/GSH) ratio, as well as a decrease of enzymatic antioxidant defenses, such as superoxide dismutase (SOD) and catalase (CAT) activity, was observed. The injection of NAC (150 mg/kg i.p. at 30 min after LPS injection) decreased the ROS, the TNFalpha the MDA levels, iNOS expression and the GSSG/GSH ratio, and increased the antioxidant defenses in both macrophages and lymphocytes. Moreover, the NAC treatment prevented the activation of nuclear translocation of the nuclear factor kappaB (NF-kappaB), which regulates ROS, inflammatory cytokines and antioxidant levels. Our present results provide evidence that both cell types have a relevant role in the pathogenesis of endotoxic shock, and that NAC, by improving the redox state of these immune cells, could increase mouse survival. Thus, antioxidants could offer an alternative treatment of human endotoxic shock.

Mice with heterozygous deficiency of lipoic acid synthase have an increased sensitivity to lipopolysaccharide-induced tissue injury

Alpha-lipoic acid (1, 2-dithiolane-3-pentanoic acid; LA), synthesized in mitochondria by LA synthase (Lias), is a potent antioxidant and a cofactor for metabolic enzyme complexes. In this study, we examined the effect of genetic reduction of LA synthesis on its antioxidant and anti-inflammatory properties using a model of LPS-induced inflammation in Lias+/- mice. The increase of plasma proinflammatory cytokine, TNF-alpha, and NF-kappaB at an early phase following LPS injection was greater in Lias+/- mice compared with Lias+/+ mice. The circulating blood white blood cell (WBC) and platelet counts dropped continuously during the initial 4 h. The counts subsequently recovered partially in Lias+/+ mice, but the recovery was impaired totally in Lias+/- mice. Administration of exogenous LA normalized the recovery of WBC counts in Lias+/- mice but not platelets. Enhanced neutrophil sequestration in the livers of Lias+/- mice was associated with increased hepatocyte injury and increased gene expression of growth-related oncogene, E-selectin, and VCAM-1 in the liver and/or lung. Lias gene expression in tissues was 50% of normal expression in Lias+/- mice and reduced further by LPS treatment. Decreased Lias expression was associated with diminished hepatic LA and tissue oxidative stress. Finally, Lias+/- mice displayed enhanced mortality when exposed to LPS-induced sepsis. These data demonstrate the importance of endogenously produced LA for preventing leukocyte accumulation and tissue injury that result from LPS-induced inflammation.

Mechanisms of sepsis-induced organ dysfunction

BACKGROUND

The past several years have seen remarkable advances in understanding the basic cellular and physiologic mechanisms underlying organ dysfunction and recovery relating to sepsis. Although several new therapeutic approaches have improved outcome in septic patients, the far-reaching potential of these new insights into sepsis-associated mechanisms is only beginning to be realized.

AIM

The Brussels Round Table Conference in 2006 convened >30 experts in the field of inflammation and sepsis to review recent advances involving sepsis and to discuss directions that the field is likely to take in the near future.

FINDINGS

Current understanding of the pathophysiology underlying sepsis-induced multiple organ dysfunction highlights the multiple cell populations and cell-signaling pathways involved in this complex condition. There is an increasing appreciation of interactions existing between different cells and organs affected by the septic process. The intricate cross-talk provided by temporal changes in mediators, hormones, metabolites, neural signaling, alterations in oxygen delivery and utilization, and by modifications in cell phenotypes underlines the adaptive and even coordinated processes beyond the dysregulated chaos in which sepsis was once perceived. Many pathologic processes previously considered to be detrimental are now viewed as potentially protective. Applying systems approaches to these complex processes will permit better appreciation of the effectiveness or harm of treatments, both present and future, and also will allow development not only of better directed, but also of more appropriately timed, strategies to improve outcomes from this still highly lethal condition.

Heme oxygenase-1 induction improves ischemic renal failure: role of nitric oxide and peroxynitrite

The present study evaluated the effects of heme oxygenase-1 (HO-1) induction on the changes in renal outer medullary nitric oxide (NO) and peroxynitrite levels during 45-min renal ischemia and 30-min reperfusion in anesthetized rats. Glomerular filtration rate (GFR), outer medullary blood flow (OMBF), HO and nitric oxide synthase (NOS) isoform expression, and renal low-molecular-weight thiols (-SH) were also determined. During ischemia significant increases in NO levels and peroxynitrite signal were observed (from 832.1 +/- 129.3 to 2,928.6 +/- 502.0 nM and from 3.8 +/- 0.7 to 9.0 +/- 1.6 nA before and during ischemia, respectively) that dropped to preischemic levels during reperfusion. OMBF and -SH significantly decreased after 30 min of reperfusion. Twenty-four hours later, an acute renal failure was observed (GFR 923.0 +/- 66.0 and 253.6 +/- 55.3 microl.min(-1).g kidney wt(-1) in sham-operated and ischemic kidneys, respectively; P < 0.05). The induction of HO-1 (CoCl(2) 60 mg/kg sc, 24 h before ischemia) decreased basal NO concentration (99.7 +/- 41.0 nM), although endothelial and neuronal NOS expression were slightly increased. CoCl(2) administration also blunted the ischemic increase in NO and peroxynitrite (maximum values of 1,315.6 +/- 445.6 nM and 6.3 +/- 0.5 nA, respectively; P < 0.05), preserving postischemic OMBF and GFR (686.4 +/- 45.2 microl.min(-1).g kidney wt(-1)). These beneficial effects of CoCl(2) on ischemic acute renal failure seem to be due to HO-1 induction, because they were abolished by stannous mesoporphyrin, a HO inhibitor. In conclusion, HO-1 induction has a protective effect on ischemic renal failure that seems to be partially mediated by decreasing the excessive production of NO with the subsequent reduction in peroxynitrite formation observed during ischemia.

Pharmacological utility of melatonin in the treatment of septic shock: experimental and clinical evidence

Sepsis is a major cause of mortality in critically ill patients and develops as a result of the host response to infection. In recent years, important advances have been made in understanding the pathophysiology and treatment of sepsis. Mitochondria play a central role in the intracellular events associated with inflammation and septic shock. One of the current hypotheses for the molecular mechanisms of sepsis is that the enhanced nitric oxide (NO) production by mitochondrial nitric oxide synthase (mtNOS) leads to excessive peroxynitrite (ONOO-) production and protein nitration, impairing mitochondrial function. Despite the advances in understanding of its pathophysiology, therapy for septic shock remains largely symptomatic and supportive. Melatonin has well documented protective effects against the symptoms of severe sepsis/shock in both animals and in humans; its use for this condition significantly improves survival. Melatonin administration counteracts mtNOS induction and respiratory chain failure, restores cellular and mitochondrial redox status, and reduces proinflammatory cytokines. Melatonin clearly prevents multiple organ failure, circulatory failure, and mitochondrial damage in experimental sepsis, and reduces lipid peroxidation, indices of inflammation and mortality in septic human newborns. Considering these effects of melatonin and its virtual absence of toxicity, the use of melatonin (along with conventional therapy) to preserve mitochondrial bioenergetics as well as to limit inflammatory responses and oxidative damage should be seriously considered as a treatment option in both septic newborn and adult patients. This review summarizes the data that provides a rationale for using melatonin in septic shock patients.

Role of oxidative stress in experimental sepsis and multisystem organ dysfunction

Massive increase in radical species can lead to oxidative stress, promoting cell injury and death. This review focuses on experimental evidence of oxidative stress in critical illnesses, sepsis and multisystem organ dysfunction. Oxidative stress could negatively affect organ injury and thus overall survival of experimental models. Based on this experimental evidence, we could improve the rationale of supplementation of antioxidants alone or in combination with standard therapies aimed to reduce oxidative stress as novel adjunct treatment in critical care.

Endotoxin induces luteal cell apoptosis through the mitochondrial pathway

The effect of endotoxin (lipopolysacharide, LPS) exposure on luteal cells was studied using an in vitro cell culture system. Buffalo luteal cells were isolated from corpora lutea of the late luteal phase (days 14-16 post estrus) and exposed to various LPS doses (5, 10 and 100 microg/ml) for different time periods (6, 12, 18 or 24 h). The cultured cells were subsequently evaluated for oxidative stress (super oxide, nitric oxide, inducible nitric oxide synthase activity, reduced glutathione depletion and lipid peroxidation) and apoptotic markers (mitochondrial membrane potential, DNA fragmentation, apoptotic cells and cell viability). LPS exposure significantly increased the production of super oxide (P<0.05) and nitric oxide (P<0.01) and increased inducible nitric oxide synthase activity (P<0.01). LPS exposure further depleted reduced glutathione (P<0.05) levels and induced lipid peroxidation (P<0.05). LPS exposure also induced the loss of mitochondrial membrane potential (P<0.05), increased DNA fragmentation (P<0.01) and apoptosis (P<0.01) and decreased cell viability (P<0.01). LPS mediated apoptotic pathway in luteal cells was further characterized using a selected LPS dose (10 microg/ml). It was observed that LPS exposure induced mitochondrial translocation of proapoptotic protein Bax, increased the total Bad expression and down regulated the expression of antiapoptotic proteins Bcl2 and BclXL. LPS exposure further induced cytochrome c release and increased Caspase-9 (P<0.01) and Caspase-3 (P<0.01) activities. LPS exposure also inhibited luteal progesterone secretion (P<0.01). It was evident that the LPS mediated apoptotic effects could be prevented by the coincubation of luteal cells with mitochondrial permeability transition pore blocker Cyclosporine A, inducible nitric oxide synthase inhibitor N-[3-(aminomethyl)benzyl]acetamidine and oxidative stress scavenger N-acetyl cysteine. Our study clearly indicates that LPS induces oxidative stress mediated apoptosis in luteal cells through the mitochondrial pathway.

EFFECT OF NITRIC OXIDE ON THE HYPOGLYCAEMIC PHASE OF ENDOTOXAEMIA

BACKGROUND

Depletion of liver glycogen stores and subsequent hypoglycaemia is one of the unresolved features in endotoxaemia. The aim of this study was to elucidate the effect of L-arginine treatment on the glucose requirement and impending liver damage during the hypoglycaemic period of endotoxaemia.

METHODS

Sixty-three of 98 male Wistar rats were assigned equally to one of three groups and received saline as control, L-arginine as selective nitric oxide donor or N(G)-nitro-L-arginine methyl ester for non-selective inhibition of nitric oxide production 1 h before endotoxin injection. At 2, 4 and 6 h following endotoxin, blood and liver samples were collected. Plasma nitrite plus nitrate, glucose, insulin and glucagon concentrations and total liver-reduced glutathione were measured. Hepatocellular glycogen content and liver damage were assessed simultaneously by histological quantification. An additional seven rats were allocated to each group and subjected to i.v. glucose tolerance test during the hypoglycaemic period.

RESULTS

Increased levels of endogenousglutathione (P = 0.003) and excess nitric oxide (P = 0.002) apparently protected the liver from endotoxin-induced injury by preserving the optimum glucose consumption rate, insulin/glucagon ratio and liver glycogen in L-arginine-plus-endotoxin-treated group. Furthermore, expected hypoglycaemic period was not observed in these animals.

CONCLUSION

Exogenous L-arginine prevented the excessive liver glycogen release without inhibiting glucose consumption while decreasing hepatic injury during the expected hypoglycaemic phase of endotoxaemia.

Eplerenone reduces oxidative stress and enhances eNOS in SHR: vascular functional and structural consequences

The aim of the present study was to evaluate the effect of the aldosterone receptor antagonist eplerenone on endothelial function, oxidative stress, and structural alterations present in spontaneously hypertensive rats (SHR). To carry out the study, male SHR (18 weeks old) were treated with two doses of eplerenone (30 and 100 mg/kg/day) for 10 weeks. A group of n = 8 untreated SHR was used as a control-vehicle group, and a group of Wistar Kyoto rats (n = 8) was used as a reference of normotensive conditions. Systolic arterial pressure (SAP) was measured by the tail-cuff method. Endothelium-dependent and -independent relaxations, as well as endothelial nitric oxide synthase (eNOS) and the subunit p22phox of NAD(P)H oxidase mRNA expressions, were studied in aorta from SHR untreated or treated with eplerenone. Media/lumen ratio was also calculated in aortic preparations. In addition, levels of reduced glutathione (GSH), oxidized glutathione (GSSG), and malonyl dialdehyde (MDA) were evaluated in liver homogenates. Treatment with eplerenone reduced (p < 0.05) SAP and normalized aortic media/lumen ratio and acetylcholine relaxations. Both doses of the drug enhanced (p < 0.05) eNOS and reduced p22phox mRNA expressions. Similarly, eplerenone increased (p < 0.05) hepatic GSH/GSSG ratio, and reduced (p < 0.05) hepatic MDA levels in a comparable manner. Consequently, it could be concluded that aldosterone participates in the functional and structural vascular alterations of SHR through the diminution of nitric oxide availability and an enhancement of vascular and systemic oxidative stress.

Renal ischemia induces an increase in nitric oxide levels from tissue stores

Tissue nitric oxide (NO) levels increase dramatically during ischemia, an effect that has been shown to be partially independent from NO synthases. Because NO is stored in tissues as S-nitrosothiols and because these compounds could release NO during ischemia, we evaluated the effects of buthionine sulfoximine (BSO; an intracellular glutathione depletor), light stimulation (which releases NO, decomposing S-nitrosothiols), and N-acetyl-L-cysteine (a sulfhydryl group donor that repletes S-nitrosothiols stores) on the changes in outer medullary NO concentration produced during 45 min of renal artery occlusion in anesthetized rats. Renal ischemia increased renal tissue NO concentration (+223%), and this effect was maintained along 45 min of renal arterial blockade. After reperfusion, NO concentration fell below preischemic values and remained stable for the remainder of the experiment. Pretreatment with 10 mg/kg nitro-L-arginine methyl ester (L-NAME) decreased significantly basal NO concentration before ischemia, but it did not modify the rise in NO levels observed during ischemia. In rats pretreated with 4 mmol/kg BSO and L-NAME, ischemia was followed by a transient increase in renal NO concentration that fell to preischemic values 20 min before reperfusion. A similar response was observed when the kidney was illuminated 40 min before the ischemia. The coadministration of 10 mg/kg iv N-acetyl-L-cysteine with BSO + L-NAME restored the increase in NO levels observed during renal ischemia and prevented the depletion of renal thiol groups. These results demonstrate that the increase in renal NO concentration observed during ischemia originates from thiol-dependent tissue stores.

Correlation of plasma and tissue oxidative stresses in intra-abdominal sepsis

BACKGROUND

The aim of this study was to investigate the correlation between plasma and tissue oxidative stress and the antioxidative response, by measuring malon dialdehyde (MDA) and glutathione (GSH) in late sepsis induced by cecal ligation and perforation.

MATERIALS AND METHODS

A prospective, randomized, controlled experimental study in rats was done. Forty rats, weighing 200-250 g, were randomly divided into two groups (n = 20). In group 1, laparotomy was performed under aseptic conditions, and the cecum ligated and perforated. The abdomen was closed. In group 2, sham control, there was only laparotomy. Twenty-four hours later, blood samples were taken by cardiac puncture for plasma MDA and GSH, followed by harvesting of samples from lung, liver, kidney, and heart in both groups.

RESULTS

In the liver, lung, plasma, heart, and kidney, MDA concentrations were increased in the sepsis group after 24 h (P < 0.001 for all organ samples). In the same organs, GSH concentrations were decreased by sepsis (P < 0.001 for all organ samples). In both groups, plasma MDA was positively correlated to MDA in heart (r = 0.82, P < 0.001), liver (r = 0.76, P < 0.001), lung (r = 0.78, P < 0.001), and kidney (r = 0.73, P < 0.001). Similarly, plasma GSH was positively correlated to GSH in liver (r = 0.93, P < 0.001), heart (r = 0.86, P < 0.001), lung (r = 0.91, P < 0.001), and kidney (r = 0.79, P < 0.001).

CONCLUSIONS

Plasma MDA and GSH were positively correlated with tissue MDA and GSH in intra-abdominal sepsis in a rat model.

Resuscitation with 100% oxygen causes intestinal glutathione oxidation and reoxygenation injury in asphyxiated newborn piglets

OBJECTIVE

To compare mesenteric blood flow, oxidative stress, and mucosal injury in piglet small intestine during hypoxemia and reoxygenation with 21%, 50%, or 100% oxygen.

SUMMARY BACKGROUND DATA

Necrotizing enterocolitis is a disease whose pathogenesis likely involves hypoxia-reoxygenation and the generation of oxygen-free radicals, which are known to cause intestinal injury. Resuscitation of asphyxiated newborns with 100% oxygen has been shown to increase oxidative stress, as measured by the glutathione redox ratio, and thus may predispose to free radical-mediated tissue injury.

METHODS

Newborn piglets subjected to severe hypoxemia for 2 hours were resuscitated with 21%, 50%, or 100% oxygen while superior mesenteric artery (SMA) flow and hemodynamic parameters were continuously measured. Small intestinal tissue samples were analyzed for histologic injury and levels of oxidized and reduced glutathione.

RESULTS

SMA blood flow decreased to 34% and mesenteric oxygen delivery decreased to 9% in hypoxemic piglets compared with sham-operated controls. With reoxygenation, SMA blood flow increased to 177%, 157%, and 145% of baseline values in piglets resuscitated with 21%, 50%, and 100% oxygen, respectively. Mesenteric oxygen delivery increased to more than 150% of baseline values in piglets resuscitated with 50% or 100% oxygen, and this correlated significantly with the degree of oxidative stress, as measured by the oxidized-to-reduced glutathione ratio. Two of eight piglets resuscitated with 100% oxygen developed gross and microscopic evidence of pneumatosis intestinalis and severe mucosal injury, while all other piglets were grossly normal.

CONCLUSIONS

Resuscitation of hypoxemic newborn piglets with 100% oxygen is associated with an increase in oxygen delivery and oxidative stress, and may be associated with the development of small intestinal hypoxia-reoxygenation injury. Resuscitation of asphyxiated newborns with lower oxygen concentrations may help to decrease the risk of necrotizing enterocolitis.

Sequential changes in redox status and nitric oxide synthases expression in the liver after bile duct ligation

Bile duct ligation (BDL) in rats induces portal fibrosis. This process has been linked to changes in the oxidative state of the hepatic cells and in the production of nitric oxide. Our objective was to find possible temporal connections between hepatic redox state, NO synthesis and liver injury. In this work we have characterized hepatic lesions 17 and 31 days after BDL and determined changes in hepatic function, oxidative state, and NO production. We have also analyzed the expression and localization of inducible NO synthase (NOS2) and constitutive NO synthase (NOS3). After 17 and 31 days from ligature, lipid peroxidation is increased and both plasma concentration and biliary excretion of nitrite+nitrate are rised. 17 days after BDL both NOS2 and NOS3 are expressed intensely and in the same regions. 31 days after BDL, the expression of NOS2 remains elevated and is localized mostly in preserved hepatocytes in portal areas and in neighborhoods of centrolobulillar vein. NOS3 is localized in vascular regions of portal spaces and centrolobulillar veins and in preserved sinusoids and although its expression is greater than in control animals (34%), it is clearly lower (50%) than 17 days after BDL. The time after BDL is crucial in the study of NO production, intrahepatic localization of NOS isoforms expression, and cell type involved, since all these parameters change with time. BDL-induced, peroxidation and fibrosis are not ligated by a cause-effect relationship, but rather they both seem to be the consequence of common inductors.

Systemic, pulmonary, and hepatosplanchnic effects of N-acetylcysteine during long-term porcine endotoxemia

OBJECTIVE

Controversial data have been reported on the effects of N-acetylcysteine in patients with septic shock. We therefore investigated the systemic, pulmonary, and hepatosplanchnic hemodynamic, gas exchange, and metabolic effects of N-acetylcysteine during long-term, volume-resuscitated, hyperdynamic porcine endotoxemia, which mimics the features of hyperdynamic human sepsis.

DESIGN

Prospective, randomized, controlled experimental study.

SETTING

Investigational animal laboratory.

SUBJECTS

Eighteen pigs were randomized to receive endotoxin alone (controls, n = 9) or endotoxin plus N-acetylcysteine (n = 9).

INTERVENTIONS

Anesthetized, mechanically ventilated, and instrumented animals received continuous intravenous endotoxin and were resuscitated with hydroxyethylstarch to keep mean arterial pressure >60 mm Hg. After 12 hrs of endotoxemia, they were randomized to receive either placebo or N-acetylcysteine (150 mg/kg loading dose over 1 hr followed by 20 mg.kg-1.hr-1 for 11 hrs).

MEASUREMENTS AND MAIN RESULTS

Before as well as 12, 18, and 24 hrs after starting the endotoxin infusion, systemic, pulmonary, and hepatosplanchnic hemodynamics, oxygen exchange, and metabolism as well as nitric oxide, glutathione, and 8-isoprostane concentrations were assessed. N-acetylcysteine failed to improve any of the variables of the systemic, pulmonary, or hepatosplanchnic hemodynamics, gas exchange, and metabolism. Although N-acetylcysteine significantly elevated glutathione concentration, it did not influence the 8-isoprostane concentrations and even further reduced hepatic venous pH.

CONCLUSIONS

Despite the increased glutathione concentration, N-acetylcysteine did not improve systemic, pulmonary, and hepatosplanchnic hemodynamics, oxygen exchange, and metabolism. When compared with previous reports in the literature, a different timing of N-acetylcysteine administration and/or an ongoing or even N-acetylcysteine-induced aggravation of oxidative stress may account for this result.

Immune cells: free radicals and antioxidants in sepsis

The excessive production of reactive oxygen species (ROS), associated with inflammation, leads to a condition of oxidative stress. Oxidative stress is a major contributing factor to the high mortality rates associated with several diseases such as endotoxic shock. This condition can be controlled to a certain degree by antioxidant therapies. Immune cells use ROS in order to support their functions and therefore need adequate levels of antioxidant defenses in order to avoid the harmful effect of an excessive production of ROS. This review discusses the toxic effects of endotoxin, paying particular attention to immune function. It continues by analyzing the mechanism to which specific cells of the immune system recognize endotoxin, and the resulting pathways leading to nuclear factor-kappaB activation and proinflammatory gene transcription. We also focus on the involvement of reactive oxygen and nitric oxide (NO) and the protective role of antioxidants. The potential clinical use of antioxidants in the treatment of sepsis and the effects on the redox state of the immune cells are discussed.

Enhancement of endotoxin-induced vascular hyporeactivity to phenylephrine in the thoracic aortas of Mg-deficient rats ex vivo

Since endotoxin lethality is enhanced by Mg deficiency in animals, we determined whether endotoxin-induced vascular hyporeactivity to phenylephrine (PE) is enhanced in Mg-deficient rats. Normal and Mg-deficient adult male Wistar rats were injected with Escherichia coli 011: B4 lipopolysaccharide (1 or 5 mg/kg, i.p.). Six h later, rings prepared from their thoracic aortas showed severe hyporeactivity to PE. This was more pronounced in the Mg-deficient rats, and was reversed by in vitro treatment with a highly selective inducible nitric oxide (NO) synthase inhibitor, 1400 W, or a highly selective soluble guanylyl cyclase inhibitor, ODQ. However, reversal required high doses of both inhibitors in Mg-deficient rats. Endotoxemia for 6 h was associated with elevated serum interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha levels, and strong TNF receptor mRNA expression in the abdominal aortas, which were significantly greater in the Mg-deficient rats. Treatment of the thoracic aortas, isolated from control and Mg-deficient rats before endotoxic challenge, with IL-1beta or TNF-alpha for 6 h in vitro caused hyporeactivity to PE, but its severity did not differ significantly between the two groups. These results suggest that high serum IL-1beta and TNF-alpha levels, and increased TNF receptor production in the vascular tissue, contribute to vascular hyporeactivity to PE in endotoxemia, and to its enhancement in Mg-deficient rats, via NO/cGMP signaling.

Effect of AT1 receptor blockade on hepatic redox status in SHR: possible relevance for endothelial function?

The study investigated whether the amelioration of endothelial dysfunction by candesartan (2 mg.kg-1.day-1; 10 wk) in spontaneously hypertensive rats (SHR) was associated with modification of hepatic redox system. Systolic arterial pressure (SAP) was higher (P < 0.05) in SHR than in Wistar-Kyoto rats (WKY) and was reduced (P < 0.05) by candesartan in both strains. Acetylcholine (ACh) relaxations were smaller (P < 0.05) and contractions induced by ACh + NG-nitro-l-arginine methyl ester (l-NAME) were greater (P < 0.05) in SHR than in WKY. Treatment with candesartan enhanced (P < 0.05) ACh relaxations in SHR and reduced (P < 0.05) ACh + l-NAME contractions in both strains. Expression of aortic endothelial nitric oxide synthase (eNOS) mRNA was similar in WKY and SHR, and candesartan increased (P < 0.05) it in both strains. Aortic mRNA expression of the subunit p22phox of NAD(P)H oxidase was higher (P < 0.05) in SHR than in WKY. Treatment with candesartan reduced (P < 0.05) p22phox expression only in SHR. Malonyl dialdehyde (MDA) levels were higher (P < 0.05), and the ratio reduced/oxidized glutathione (GSH/GSSG) as well as glutathione peroxidase activity (GPx) were lower (P < 0.05) in liver homogenates from SHR than from WKY. Candesartan reduced (P < 0.05) MDA and increased (P < 0.05) GSH/GSSG ratio without affecting GPx. Vessel, lumen, and media areas were bigger (P < 0.05) in SHR than in WKY. Candesartan treatment reduced (P < 0.05) media area in SHR without affecting vessel or lumen area. The results suggest that hypertension is not only associated with elevation of vascular superoxide anions but with alterations of the hepatic redox system, where ANG II is clearly involved. The results further support the key role of ANG II via AT1 receptors for the functional and structural vascular alterations produced by hypertension.

Hyperglycemia induced by glucose infusion causes hepatic oxidative stress and systemic inflammation, but not STAT3 or MAP kinase activation in liver in rats

The purpose of this study was to determine the effects of acute hyperglycemia induced by glucose infusion on oxidative stress, systemic inflammation, and several key signal intermediates in liver for the systemic inflammatory response in nonstressed rats. Rats received saline or glucose infusion (hyperglycemic clamp) for 3 hours. Rats without catheter insertion were included as an additional control for observing the effects of surgical stress. Levels of malondialdehyde (MDA) and total glutathione to assess oxidative stress were determined in liver and muscle. Proinflammatory cytokines including tumor necrosis factor (TNF), interleukin (IL)-1 and IL-6, and alpha 1 acid glycoprotein (alpha1-AG) were determined in serum. The protein content and phosphorylation of extracellular signal-regulated kinase (ERK)1/2, p38 stress-activated protein kinase (p38), and signal transducer and activator of transcription-3 (STAT-3) were examined in the liver tissue with or without IL-6 stimulation. The results showed that acute hyperglycemia significantly increased MDA release and depleted total glutathione in liver but not in muscle. Hyperglycemia also significantly elevated the production of TNF, IL-1, and alpha1-AG, but not IL-6 in serum. However, hyperglycemia for 3 hours in vivo did not activate ERK1/2, p38 and STAT3 in liver, and also did not alter the response of these signal proteins to IL-6 stimulation. These data suggest that acute (3 hours) hyperglycemia causes hepatic oxidative stress and activates a low-grade systemic inflammation but does not affect key components of the IL-6 signaling pathway in liver.

Glutathione depletion increases nitric oxide-induced oxidative stress in primary rat hepatocyte cultures: involvement of low-molecular-weight iron

Various drugs and chemicals can cause a glutathione (GSH) depletion in the liver. Moreover, nitric oxide (NO) can be generated in response to physiological and pathological situations such as inflammation. The aim of this study was to estimate oxidative stress when primary rat hepatocytes were exposed to GSH depletion after NO production. For this purpose, cells were preincubated with lipopolysaccharide (LPS) and gamma-interferon (IFN) for 18 h in order to induce NO production by NO synthase and then L-buthionine sulfoximine (BSO), an inhibitor of GSH synthesis, was added for 5 h. In hepatocyte cultures preincubated with LPS and IFN before BSO addition, an increase in lipid peroxidation was noted. In those cells, an elevation of iron-bound NO and a decrease in free NO led us to suggest the involvement of low-molecular-weight iron (LMW iron) in the enhancement of oxidative stress. Indeed, addition of deferiprone, a chelator of LMW iron, reduced iron-bound NO levels and the extent of oxidative stress. Moreover, an important elevation of LMW iron levels was also observed. As both, N-acetylcysteine, a GSH precursor, and N(G)-monomethyl-L-arginine, a NO synthase inhibitor, totally inhibited the elevation of LMW iron and oxidative stress, a cooperative role could be attributed to NO production and GSH depletion.

Oxidative stress and gene expression in sepsis

Dysregulation of the immuno-inflammatory response, as seen in sepsis, may culminate in host cell and organ damage. Lipopolysaccharide from Gram-negative bacterial cell walls induces gene activation and subsequent inflammatory mediator expression. Gene activation is regulated by a number of transcription factors at the nuclear level, of which nuclear factor kappaB appears to have a central role. The redox (reduction-oxidation) cellular balance is important for normal cellular function, including transcription factor regulation. In sepsis, a state of severe oxidative stress is encountered, with host endogenous antioxidant defences overcome. This has implications for cellular function and the regulation of gene expression. This review gives an overview of the mechanisms by which transcription factor activation and inflammatory mediator overexpression occur in sepsis, together with the events surrounding the state of oxidative stress encountered and the effects on the host's antioxidant defences. The effect of oxidative stress on transcription factor regulation is considered, together with the role of antioxidant repletion in transcription factor activation and in sepsis in general. Other interventions that may modulate transcription factor activation are also highlighted.

Oxidative stress in critically ill patients with systemic inflammatory response syndrome

OBJECTIVE

To evaluate whether critically ill patients with systemic inflammatory response syndrome, on admission to an intensive care unit, had more severe oxidative stress than those without this syndrome.

DESIGN

A prospective, cohort study.

SETTING

A mixed medical and surgical adult intensive care unit with 12 beds.

PATIENTS

A total of 68 consecutive patients admitted to the intensive care unit.

INTERVENTIONS

Venous blood samples were routinely obtained within 24 hrs of admission.

MEASUREMENTS AND MAIN RESULTS

Patients' plasma total antioxidant capacity, the lipid peroxidation products malondialdehyde and 4-hydroxynonenal, reduced sulfhydryl groups, and nitrites/nitrates were measured by spectrophotometric technique at admission to the intensive care unit. Myeloperoxidase (enzyme-linked immunosorbent assay) and polymorphonuclear elastase (immuno-activation assay) were also measured on admission to the intensive care unit. The patients with criteria of systemic inflammatory response syndrome (n = 20) had higher Acute Physiology and Chronic health Evaluation III scores (determined by collecting the worst value within 24 hrs after admission to the intensive care unit) and plasma concentrations of lipid peroxidation products and nitrites/nitrates and lower plasma concentration of reduced sulfhydryl groups and plasma total antioxidant capacity than patients without the syndrome (n = 48). Moreover, the markers for leukocyte activation, myeloperoxidase and polymorphonuclear elastase, presented higher concentrations in the plasma of patients with systemic inflammatory response syndrome.

CONCLUSIONS

Patients admitted to the intensive care unit with criteria of systemic inflammatory response syndrome had a more severe oxidative stress than patients without this syndrome.

Changes in the antioxidant content of mononuclear leukocytes from mice with endotoxin-induced oxidative stress

Oxidative stress, associated with a high production of reactive oxygen species (ROS) by immune cells, is involved in the endotoxic shock caused by endotoxin. This oxidative stress is linked to the inability of the immune cells to maintain adequate levels of antioxidants with free radical-scavenging action. Glutathione (GSH) and ascorbic acid (AA) are intracellular and extracellular antioxidants (ROS scavengers) that improve the leukocyte functions. Therefore, in the present work we have determined the reduced GSH and AA content in axillary nodes, spleen, thymus and peritoneal mononuclear leukocytes from BALB/c mice subjected to lethal endotoxic shock produced by intraperitoneal injection of E. coli lipopolysaccharide (LPS, 100 mg/kg), at several times (0, 2, 4, 12 and 24 h) after LPS injection. Endotoxic shock decreased the levels of AA in the leukocytes from the three organs as well as the levels of GSH in axillary nodes and spleen cells while it increased the GSH levels in thymus and peritoneum. These results are in agreement with the oxidative stress and the altered function previously observed in those leukocytes, and they suggest that antioxidant administration may be useful for the treatment of endotoxic shock and other oxidative stress situations with altered immunological responses.