Role of nitric oxide in the expression of hepatic vascular stress genes in response to sepsis

Endothelial cell dynamics in sepsis-induced acute lung injury and acute respiratory distress syndrome: pathogenesis and therapeutic implications

Sepsis, a prevalent critical condition in clinics, continues to be the leading cause of death from infections and a global healthcare issue. Among the organs susceptible to the harmful effects of sepsis, the lungs are notably the most frequently affected. Consequently, patients with sepsis are predisposed to developing acute lung injury (ALI), and in severe cases, acute respiratory distress syndrome (ARDS). Nevertheless, the precise mechanisms associated with the onset of ALI/ARDS remain elusive. In recent years, there has been a growing emphasis on the role of endothelial cells (ECs), a cell type integral to lung barrier function, and their interactions with various stromal cells in sepsis-induced ALI/ARDS. In this comprehensive review, we summarize the involvement of endothelial cells and their intricate interplay with immune cells and stromal cells, including pulmonary epithelial cells and fibroblasts, in the pathogenesis of sepsis-induced ALI/ARDS, with particular emphasis placed on discussing the several pivotal pathways implicated in this process. Furthermore, we discuss the potential therapeutic interventions for modulating the functions of endothelial cells, their interactions with immune cells and stromal cells, and relevant pathways associated with ALI/ARDS to present a potential therapeutic strategy for managing sepsis and sepsis-induced ALI/ARDS.

Selective gene expression profiling contributes to a better understanding of the molecular pathways underlying the histological changes observed after RHMVL

Background

In previous studies, five vasoactive drugs were investigated for their effect on the recovery process after extended liver resection without observing relevant improvements. We hypothesized that an analysis of gene expression could help to identify potentially druggable pathways and could support the selection of promising drug candidates.

Methods

Liver samples obtained from rats after combined 70% partial hepatectomy and right median hepatic vein ligation (n = 6/group) sacrificed at 0 h, 24 h, 48 h, and 7days were selected for this study. Liver samples were collected from differentially perfused regions of the median lobe (obstruction-zone, border-zone, normal-zone). Gene expression profiling of marker genes regulating hepatic hemodynamics, vascular remodeling, and liver regeneration was performed with microfluidic chips. We used 3 technical replicates from each sample. Raw data were normalized using LEMming and differentially expressed genes were identified using LIMMA.

Results

The strongest differences were found in obstruction-zone at 24 h and 48 h postoperatively compared to all other groups. mRNA expression of marker genes from hepatic hemodynamics pathways (iNOS,Ptgs2,Edn1) was most upregulated.

Conclusion

These upregulated genes suggest a strong vasoconstrictive effect promoting arterial hypoperfusion in the obstruction-zone. Reducing iNOS expression using selective iNOS inhibitors seems to be a promising approach to promote vasodilation and liver regeneration.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01364-z.

Oxidative Stress and Endothelial Dysfunction in Sepsis and Acute Inflammation

Significance: Under homeostatic conditions, the endothelium dynamically regulates vascular barrier function, coagulation pathways, leukocyte adhesion, and vasomotor tone. During sepsis and acute inflammation, endothelial cells (ECs) undergo multiple phenotypic and functional modifications that are initially adaptive but eventually become harmful, leading to microvascular dysfunction and multiorgan failure. Critical Issues and Recent Advances: Sepsis unbalances the redox homeostasis toward a pro-oxidant state, characterized by an excess production of reactive oxygen species and reactive nitrogen species, mitochondrial dysfunction, and a breakdown of antioxidant systems. In return, oxidative stress (OS) alters multiple EC functions and promotes a proinflammatory, procoagulant, and proadhesive phenotype. The OS also induces glycocalyx deterioration, cell death, increased permeability, and impaired vasoreactivity. Thus, during sepsis, the ECs are both a significant source and one of the main targets of OS. Future Directions: This review aims at covering the current understanding of the role of OS in the endothelial adaptive or maladaptive multifaceted response to sepsis and to outline the therapeutic potential and issues of targeting OS and endothelial dysfunction during sepsis and septic shock. One of the many challenges in the management of sepsis is now based on the detection and correction of these anomalies of endothelial function.

Effect of Curcumol on the Fenestrae of Liver Sinusoidal Endothelial Cells Based on NF-κB Signaling Pathway

Objective

To study the effect of curcumol on liver sinusoidal endothelial cells (LSECs) and to analyze the mechanism of antihepatic fibrosis.

Methods

The effects of drug intervention on cell proliferation rates were detected by MTT assay. The expression of NF-κB was detected by RT-PCR and WB. The NF-κB expression and entry into the nucleus were detected by immunofluorescence; scanning electron microscopy was used to observe the changes of LSECs fenestrae.

Results

MTT results showed that the interference of cell proliferation in each group was small. RT-PCR showed that the expression of NF-κB in the curcumol intervention group was significantly lower than that in the positive control group (P < 0.05). The WB detection found that, in the curcumol intervention group, the expression of pNF-κB in the NF-κB signaling pathway was significantly lower than that in the positive control group (P < 0.05). Scanning electron microscopy showed that the LSEC fenestrae were significantly improved compared with the positive control group.

Conclusion

Curcumol may be one of the mechanisms of antihepatic fibrosis by inhibiting the activity of the NF-κB signaling pathway and increasing the fenestrae of LSECs.

Serum ammonia levels on admission for predicting sepsis patient mortality at D28 in the emergency department: A 2-center retrospective study

We assessed the predictive value of serum ammonia level on admission for the 28-day mortality of patients with sepsis.We retrospectively included septic patients admitted to the emergency department of West China Hospital, Sichuan University and The Fourth People's Hospital of Zigong city from June 2017 to May 2018. Patients were divided into 2 groups according to 28-day survival. Comparisons of serum ammonia level and sequential organ failure assessment (SOFA) score were made between 2 groups. Multivariate logistic regression models were employed to determine independent risk factors affecting 28-day mortality rate, and receiver operating characteristic (ROC) curve was also used to evaluate the efficacy of risk factors.Total of 316 patients were included into the study, 221 survived to 28 days and 95 were died before 28 days. The 28-day mortality rate was 30.06%. Multivariate logistic regression analyses revealed that the ammonia level, C reactive protein, SOFA score, and the leukocyte were independent risk factors for the 28-day mortality rate. In predicting the 28-day mortality rate, the SOFA score presented an area under the ROC curve (AUC) of 0.815, and the ammonia levels presented the AUC of 0.813.The ammonia level, C reactive protein, SOFA score, and the leukocyte are independent risk factors for 28-day mortality rate in septic patients. Moreover, the serum ammonia and SOFA score have similar predictive values. The serum ammonia level is also a suitable early indicator for prognostic evaluation of patients with sepsis as well.

Effects of endothelin and nitric oxide on cardiac muscle functions in experimental septic shock model

We aimed to investigate the possible roles of nitric oxide (NO) and endothelin on the changes of cardiac muscle function in both hyper- and hypodynamic septic shock periods. Cecal ligation and puncture was performed in 50 Wistar albino rats to induce septic shock. Changes in atrium and right ventricle papillary muscle contractions, atrium beat rate, adrenergic and cholinergic responses in these tissues were evaluated in vitro. Atrium beat rate increased in hypodynamic period ( p < 0.001) that was reversed by bosentan ( p < 0.001) and NG-nitro-l-arginine methylester (l-NAME; p < 0.05). Atrium contractions decreased in both hyper- and hypodynamic periods ( p < 0.001) that were partially ameliorated by bosentan in both periods ( p < 0.01) and only in hypodynamic period by l-NAME ( p < 0.001). l-NAME increased papillary muscle contractions in both periods ( p < 0.01), but bosentan increased it only in hyperdynamic period ( p < 0.01). Bosentan and l-NAME increased potency of isoproterenol on atrium beat rate in both periods and increased carbachol potency on atrium beat rate and atrium contraction amplitude only in hypodynamic period. Bosentan increased atrium contraction response to isoproterenol in hypodynamic period ( p < 0.05). Papillary muscle contraction response to isoproterenol increased in hypodynamic period ( p < 0.05). l-NAME increased papillary muscle contraction response to carbachol in both periods ( p < 0.01, p < 0.05, respectively). These results show that NO and endothelin may play a role in positive inotropic and negative chronotropic effects for atrium in septic shock. Bosentan and l-NAME may change potency and efficacy of isoproterenol and carbachol via upregulation of adrenergic and cholinergic receptors and/or through post receptor factors.

Regulation of mitochondrial biogenesis and its intersection with inflammatory responses

SIGNIFICANCE

Mitochondria play a vital role in cellular homeostasis and are susceptible to damage from inflammatory mediators released by the host defense. Cellular recovery depends, in part, on mitochondrial quality control programs, including mitochondrial biogenesis.

RECENT ADVANCES

Early-phase inflammatory mediator proteins interact with PRRs to activate NF-κB-, MAPK-, and PKB/Akt-dependent pathways, resulting in increased expression or activity of coactivators and transcription factors (e.g., PGC-1α, NRF-1, NRF-2, and Nfe2l2) that regulate mitochondrial biogenesis. Inflammatory upregulation of NOS2-induced NO causes mitochondrial dysfunction, but NO is also a signaling molecule upregulating mitochondrial biogenesis via PGC-1α, participating in Nfe2l2-mediated antioxidant gene expression and modulating inflammation. NO and reactive oxygen species generated by the host inflammatory response induce the redox-sensitive HO-1/CO system, causing simultaneous induction of mitochondrial biogenesis and antioxidant gene expression.

CRITICAL ISSUES

Recent evidence suggests that mitochondrial biogenesis and mitophagy are coupled through redox pathways; for instance, parkin, which regulates mitophagy in chronic inflammation, may also modulate mitochondrial biogenesis and is upregulated through NF-κB. Further research on parkin in acute inflammation is ongoing. This highlights certain common features of the host response to acute and chronic inflammation, but caution is warranted in extrapolating findings across inflammatory conditions.

FUTURE DIRECTIONS

Inflammatory mitochondrial dysfunction and oxidative stress initiate further inflammatory responses through DAMP/PRR interactions and by inflammasome activation, stimulating mitophagy. A deeper understanding of mitochondrial quality control programs' impact on intracellular inflammatory signaling will improve our approach to the restoration of mitochondrial homeostasis in the resolution of acute inflammation.

Ameliorative effects of Tricholepis glaberrima in experimentally induced hepatic damage in rats: modulation of cytokines functions

ETHNOPHARMACOLOGICAL RELEVANCE

Tricholepis glaberrima belonging to family Asteraceae is popularly known as "Brahmadandi" in Indian system of medicine and is claimed to be effective in the treatment of various ailments such as neurological disorders, hepatic disorders, sexual dysfunction, skin disease etc. The present study was undertaken to investigate the possible role of Tricholepis glaberrima in rifampicin and Bacillus Calmette-Guerin/lipopolysaccharides (BCG/LPS) induced hepatotoxicity in rats and its possible mechanism of actions.

MATERIALS AND METHODS

Hepatotoxicity was induced in rats by administration of rifampicin for 30 days and in another experiment BCG on day 1 and LPS on day 11. In both the experiments, hepatotoxicity was assessed by alteration of serum marker enzymes (AST, ALT, and LDH), total proteins, MDA and NO formation, cytokines mainly IL-6 and TNF-α and histoarchitecture alterations. The IL-6 and TNF-α level in liver homogenates were determined by ELISA technique.

RESULTS

Administration of both rifampicin and BCG-LPS elicited hepatic damage reflected in significantly (p<0.01) increased serum marker enzymes AST, ALT, ALP, GGT, LDH and decreased total proteins, increased MDA and NO formation in liver homogenate. Furthermore, IL-6 and TNF-α increased significantly in both the experimental conditions. Pretreatment with METg and silymarin attenuated significantly (p<0.01) marker enzymes, TP, MDA and NO formation as well as IL-6 and TNF-α production in liver homogenates. Prophylactic treatment with METg exhibits significant improvement in liver damage as compared to therapeutic treatment.

CONCLUSION

The hepatoprotective activity of METg may be correlated with the amelioration of oxidative stress due to immunological insult, by improving antioxidant defense ability of hepatocytes and also by reducing the cytokines (TNF-α, IL-6 and NO) production.

Endothelin B receptor-mediated encephalopathic events in mouse sepsis model

AIMS

We evaluated whether pathophysiological events in the brain in sepsis are mediated by ET-1/ETB receptor axis.

MAIN METHODS

We prepared raw fecal fluid from soft stool of mice. Mice were randomly divided into three groups: pre-PBS+raw fecal fluid group (Sepsis, easy stool method (ESM) group); pre-BQ788+raw fecal fluid group (BQ group); and pre-BQ788+PBS group (PBS group). According to each experimental condition, PBS or BQ788 was intravenously injected into mice prior to intraperitoneal administration of fecal fluid or PBS. All groups of mice were sacrificed at 8h after administration, and then brain samples were prepared.

KEY FINDINGS

In the ESM group, an increase of apoptotic neuroblasts was demonstrated in the subgranular zone of the hippocampal dentate gyrus, enhanced expression of c-FOS was observed in arginine-vasopressin-containing neurons in the hypothalamic paraventricular nucleus, and various cytokines involving TNF-α were upregulated in the brain, compared with those in the PBS group. In the region corresponding to their findings, the number of reactive microglia and vascular leakage was markedly increased. BQ788 inhibited the induction of c-FOS expression, neuroblast apoptosis, cytokine upregulation and reactive microglia without affecting vascular leakage.

SIGNIFICANCE

We demonstrated that BQ788 could protect the brain from the following sepsis-associated pathophysiological output: neural cell death, inflammatory response and the Hans Selye's environmental stress reaction.

Advances in sepsis-associated liver dysfunction

Recent studies have revealed liver dysfunction as an early event in sepsis. Sepsis-associated liver dysfunction is mainly resulted from systemic or microcirculatory disturbances, spillovers of bacteria and endotoxin (lipopolysaccharide, LPS), and subsequent activation of inflammatory cytokines as well as mediators. Three main cell types of the liver which contribute to the hepatic response in sepsis are Kupffer cells (KCs), hepatocytes and liver sinusoidal endothelial cells (LSECs). In addition, activated neutrophils, which are also recruited to the liver and produce potentially destructive enzymes and oxygen-free radicals, may further enhance acute liver injury. The clinical manifestations of sepsis-associated liver dysfunction can roughly be divided into two categories: Hypoxic hepatitis and jaundice. The latter is much more frequent in the context of sepsis. Hepatic failure is traditionally considered as a late manifestation of sepsis-induced multiple organ dysfunction syndrome. To date, no specific therapeutics for sepsis-associated liver dysfunction are available. Treatment measure is mainly focused on eradication of the underlying infection and management for severe sepsis. A better understanding of the pathophysiology of liver response in sepsis may lead to further increase in survival rates.

Reactive oxygen and nitrogen species in sepsis-induced hepatic microvascular dysfunction

Objective and design

Hepatic microvascular dysfunction is a critical event in the development of liver failure during sepsis. Activated blood cells and reactive oxygen and nitrogen species (RONS) have been implicated in the pathogenesis of sepsis.

Methods

Intravital-videomicroscopy was used to determine whether RONS contribute to the recruitment of leukocytes/platelets in the hepatic microvasculature during sepsis. Six hours following cecal-ligation and puncture (CLP), disturbances of the hepatic microvasculature were assessed in WT-mice (C57Bl/6 J; n = 8), in mice lacking gp91^phox(n = 5), overexpressing superoxide-dismutase (SOD, n = 8), in WT-mice treated with a NOS-inhibitor (l-NAME, n = 5), lacking nNOS, eNOS or iNOS (n = 5 each), treated with the NO-donor DetaNO (n = 5), in WT-mice treated with gadolinium-chloride (GdCl₂, n = 5) and compared to a group of WT-mice following a sham operation (n = 8). Six hours post-CLP, the adhesion of leukocytes and platelets in terminal hepatic venules (THV) and sinusoids was quantified.

Results

In WT-mice, CLP elicited increases in the number of adherent leukocytes and platelets. Similar responses to CLP were noted in mice overexpressing SOD or lacking either eNOS or gp91^phox. The blood-cell recruitment was significantly blunted in septic iNOS-knockout mice and this response was reversed by pre-treatment with DetaNO.

Conclusion

These findings suggest that iNOS-derived NO is a determinant of the pro-inflammatory phenotype assumed by the hepatic microvasculature during sepsis.

HIV-1 coinfection and morphine coexposure severely dysregulate hepatitis C virus-induced hepatic proinflammatory cytokine release and free radical production: increased pathogenesis coincides with uncoordinated host defenses

Coinfection with human immunodeficiency virus type-1 (HIV-1) and hepatitis C virus (HCV) is a global problem that is more prevalent in injection drug users because they have a higher risk for acquiring both viruses. The roles of inflammatory cytokines and oxidative stress were examined in HIV-1- and HCV-coinfected human hepatic cells. Morphine (the bioactive product of heroin), HIV-1 Tat and the MN strain gp120 (gp120(MN)) proteins, and X4 HIV-1(LAI/IIIB) and R5 HIV-1(SF162) isolates were used to study the mechanisms of disease progression in HCV (JFH1)-infected Huh7.5.1 cell populations. HCV increased tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) release and augmented production of reactive oxygen species (ROS), nitric oxide (NO), and 3-nitrotyrosine (3-NT) in Huh7.5.1 cells. Morphine preferentially affected R5-tropic, but not X4-tropic, HIV-1 interactions with Huh7.5.1 cells. HIV-1 proteins or isolates increased cytokine release in HCV-infected cells, while adding morphine to coinfected cells caused complex imbalances, significantly disrupting cytokine secretion depending on the cytokine, morphine concentration, exposure duration, and particular pathogen involved. Production of ROS, NO, and 3-NT increased significantly in HCV- and HIV-1-coexposed cells while exposure to morphine further increased ROS. The proteasome inhibitor MG132 significantly decreased oxyradicals, cytokine levels, and HCV protein levels. Our findings indicate that hepatic inflammation is increased by combined exposure to HCV and HIV-1, that the ubiquitin-proteasome system and NF-κB contribute to key aspects of the response, and that morphine further exacerbates the disruption of host defenses. The results suggest that opioid abuse and HIV-1 coinfection each further accelerate HCV-mediated liver disease by dysregulating immune defenses.

Benznidazole treatment attenuates liver NF-κB activity and MAPK in a cecal ligation and puncture model of sepsis

Recent studies have shown that Benznidazole (BZL), known for its antiparasitic action on Trypanosoma cruzi, modulates pro-inflammatory cytokines and nitric oxide (NO) release in activated macrophages by blocking NF-κB through inhibition of IKK in vitro. As so far, little is known about the mechanism by which BZL provokes the inhibition of inflammatory response in sepsis in vivo, we aimed to delineate the possible role of BZL as a modulator in liver inflammation in mice with sepsis induced by cecal ligation and puncture (CLP). Specifically, we analyzed leukocytes, liver production of TNF-α and NO and the intracellular pathways modulated by these mediators, including NF-κB and MAPKs, in the liver of mice 24 h post-CLP. Our results show that BZL reduces leukocytes in peripheral blood accompanied by an increase in peritoneal macrophages 24h after CLP. In the liver of these septic mice, BZL decreased expression of mRNA and protein for TNF-α and NOS-2 by inhibition of NF-κB and MAPK (p-38 and ERK). The body of evidence suggests that the immunomodulatory effects of BZL could act selectively, as it is able to decrease the systemic inflammatory reaction and the hepatic response but it can increase the number of cells in the site of infection.

Innate immunity of the liver microcirculation

The liver is a complex organ with a unique microcirculation and both synthetic and immune functions. Innate immune responses have been studied in response to single inflammatory mediators and several clinically relevant models of infection and injury. While standard histological techniques have been used in many models, the liver microcirculation is also amenable to in vivo examination using epifluorescent, confocal and transillumination intravital microscopy. These techniques have begun to clarify not only the molecular mechanisms but also the specific cell populations involved in the liver inflammation. In this review, we discuss the cells and mediators involved in hepatic innate immunity in simple and complex models of injury and infection, and present the view that the liver microcirculation utilizes non-classical pathways for leukocyte recruitment.

Abnormal modulation of cell protective systems in response to ischemic/reperfusion injury is important in the development of mouse sickle cell hepatopathy

BACKGROUND

Sickle cell disease, a genetic red cell disorder inherited in an autosomal recessive manner, occurs throughout the world. Hepatic dysfunction and liver damage may be present in sickle cell disease, but the pathogenesis of these conditions is only partially understood.

DESIGN AND METHODS

Transgenic mice with sickle cell disease (SAD mice) and wild-type mice were exposed to an ischemic/reperfusion stress. The following parameters were evaluated: hematologic profile, transaminase and bilirubin levels, liver histopathology, and mRNA levels of nuclear factor-κB p65, endothelial nitric oxide synthase, inducible nitric oxide synthase, heme oxygenase-1 and phosphodiesterase-1, -2, -3, and -4 genes in hepatocytes obtained by laser-capture microdissection. Immunoblotting was used to analyze the expression of the following proteins: nuclear factor-κB p65 and phospho-nuclear factor-κB p65, heme oxygenase-1, biliverdin reductase, heat shock protein-70, heat shock protein-27 and peroxiredoxin-6. A subgroup of SAD mice was treated with the phosphodiesterase-4 inhibitor rolipram (30 mg/Kg/day by gavage) during the ischemic/reperfusion protocol.

RESULTS

In SAD mice the ischemic/reperfusion stress induced liver damage compatible with sickle cell disease hepatopathy, which was associated with: (i) lack of hypoxia-induced nuclear factor-κB p65 activation; (ii) imbalance in the endothelial/inducible nitric oxide synthase response to ischemic/reperfusion stress; (iii) lack of hypoxia-induced increased expression of heme oxygenase-1/biliverdin reductase paralleled by a compensatory increased expression of heat shock proteins 70 and 27 and peroxiredoxin-6; and (iv) up-regulation of the phosphodiesterase-1, -2, -3, and -4 genes. In SAD mice the phosphodiesterase-4 inhibitor rolipram attenuated the ischemic/reperfusion-related microcirculatory dysfunction, reduced the inflammatory cell infiltration and induced the heme oxygenase-1/biliverdin reductase cytoprotective systems.

CONCLUSIONS

In SAD mice, sickle cell hepatopathy is associated with perturbed nuclear factor-κB p65 signaling with an imbalance of endothelial/inducible nitric oxide synthase levels, lack of heme oxygenase-1/biliverdin reductase expression and up-regulation of two novel cytoprotective systems: heat shock protein-27 and peroxiredoxin-6.

The hepatic microcirculation: mechanistic contributions and therapeutic targets in liver injury and repair

The complex functions of the liver in biosynthesis, metabolism, clearance, and host defense are tightly dependent on an adequate microcirculation. To guarantee hepatic homeostasis, this requires not only a sufficient nutritive perfusion and oxygen supply, but also a balanced vasomotor control and an appropriate cell-cell communication. Deteriorations of the hepatic homeostasis, as observed in ischemia/reperfusion, cold preservation and transplantation, septic organ failure, and hepatic resection-induced hyperperfusion, are associated with a high morbidity and mortality. During the last two decades, experimental studies have demonstrated that microcirculatory disorders are determinants for organ failure in these disease states. Disorders include 1) a dysregulation of the vasomotor control with a deterioration of the endothelin-nitric oxide balance, an arterial and sinusoidal constriction, and a shutdown of the microcirculation as well as 2) an overwhelming inflammatory response with microvascular leukocyte accumulation, platelet adherence, and Kupffer cell activation. Within the sequelae of events, proinflammatory mediators, such as reactive oxygen species and tumor necrosis factor-alpha, are the key players, causing the microvascular dysfunction and perfusion failure. This review covers the morphological and functional characterization of the hepatic microcirculation, the mechanistic contributions in surgical disease states, and the therapeutic targets to attenuate tissue injury and organ dysfunction. It also indicates future directions to translate the knowledge achieved from experimental studies into clinical practice. By this, the use of the recently introduced techniques to monitor the hepatic microcirculation in humans, such as near-infrared spectroscopy or orthogonal polarized spectral imaging, may allow an early initiation of treatment, which should benefit the final outcome of these critically ill patients.

Pathophysiologic basis for the medical management of portal hypertension

BACKGROUND

Portal hypertension is a potentially life-threatening complication of cirrhosis, resulting from increased intrahepatic resistance and portal inflow.

OBJECTIVE

Given the complex nature of this disorder, a more complete understanding of the pathophysiology of portal hypertension is necessary to develop new therapies that target specific pathways that regulate portal pressure.

METHODS

This review is based on a literature search of published articles and abstracts on the pathophysiology of portal hypertension, its complications and its treatment.

RESULTS/CONCLUSION

A number of therapies have been developed or are under investigation for the treatment of portal hypertension and its complications. These agents may reduce mortality and improve quality of life for patients with advanced liver disease.

The involvement of nitric oxide in maneb- and paraquat-induced oxidative stress in rat polymorphonuclear leukocytes

Oxidative stress plays a crucial role in the manifestations of maneb (MB) and paraquat (PQ)-induced toxicity including MB+PQ-induced Parkinson's disease (PD). Polymorphonuclear leukocytes (PMNs) actively participate in the oxidative stress-mediated inflammation and organ toxicity. The present study was undertaken to investigate the MB- and/or PQ-induced alterations in the indices of oxidative stress in rat PMNs. Animals were treated with or without MB and/or PQ in an exposure time dependent manner. In some sets of experiments, the animals were pre-treated with NOS inhibitors N(G)-nitro-L-arginine methyl ester (L-NAME) and aminoguanidine (AG) along with respective controls. A significant increase in myeloperoxidase (MPO), superoxide dismutase (SOD), nitric oxide, iNOS expression and lipid peroxidation (LPO) was observed in PMNs of MB- and/or PQ-treated animals, while catalase and glutathione S-transferase (GST) activities were attenuated. L-NAME and AG significantly reduced the augmented nitrite content, iNOS expression and MPO activity to control level in MB and PQ exposed animals. Although the augmented LPO was also reduced significantly in L-NAME and AG treated rat PMNs, the level was still higher as compared with controls. Alterations induced in SOD and GST activities were not affected by NOS inhibitors. The results thus suggest that MB and/or PQ induce iNOS-mediated nitric oxide production, which in turn increases MPO activity and lipid peroxidation, thereby oxidative stress.

Antioxidant treatment reverses mitochondrial dysfunction in a sepsis animal model

Evidence from the literature has demonstrated that reactive oxygen species (ROS) play an important role in the development of multiple organ failure and septic shock. In addition, mitochondrial dysfunction has been implicated in the pathogenesis of multiple organ dysfunction syndrome (MODS). The hypothesis of cytopathic hypoxia postulates that impairment in mitochondrial oxidative phosphorylation reduces aerobic adenosine triphosphate (ATP) production and potentially induces MODS. In this work, our aim was to evaluate the effects of antioxidants on oxidative damage and energy metabolism parameters in liver of rats submitted to a cecal ligation puncture (CLP) model of sepsis. We speculate that CLP induces a sequence of events that culminate with liver cells death. We propose that mitochondrial superoxide production induces mitochondrial oxidative damage, leading to mitochondrial dysfunction, swelling and release of cytochrome c. These events occur in early sepsis development, as reported in the present work. Liver cells necrosis only occurs 24 h after CLP, but all other events occur earlier (6-12 h). Moreover, we showed that antioxidants may prevent oxidative damage and mitochondrial dysfunction in liver of rats after CLP. In another set of experiments, we verified that L-NAME administration did not reverse increase of superoxide anion production, TBARS formation, protein carbonylation, mitochondrial swelling, increased serum AST or inhibition on complex IV activity caused by CLP. Considering that this drug inhibits nitric oxide synthase and that no parameter was reversed by its administration, we suggest that all the events reported in this study are not mediated by nitric oxide. In conclusion, although it is difficult to extrapolate our findings to human, it is tempting to speculate that antioxidants may be used in the future in the treatment of this disease.