N-acetylcysteine abrogates acute lung injury induced by endotoxin

N-acetyl cysteine mitigates lung damage and inflammation after chlorine exposure in vivo and ex vivo

The objective of this study was to explore the effects of antioxidant treatments, specifically N-acetylcysteine (NAC) and N-acetylcysteine amide (NACA), in a mouse model of chlorine (Cl2)-induced lung injury. Additionally, the study aimed to investigate the utility of pig precision-cut lung slices (PCLS) as an ex vivo alternative for studying the short-term effects of Cl2 exposure and evaluating antioxidant treatments. The toxicological responses were analyzed in Cl2-exposed mice (inflammation, airway hyperresponsiveness (AHR)) and PCLS (viability, cytotoxicity, inflammatory mediators). Airways contractions were assessed using a small ventilator for mice and electric-field stimulation (EFS) for PCLS. Antioxidant treatments were administered to evaluate their effects. In Cl2-exposed mice, NAC treatment did not alleviate AHR, but it did reduce the number of neutrophils in bronchoalveolar lavage fluid and inflammatory mediators in lung tissue. In PCLS, exposure to Cl2 resulted in concentration-dependent toxicity, impairing the lung tissue's ability to respond to EFS-stimulation. NAC treatment increased viability, mitigated the toxic responses caused by Cl2 exposure, and maintained contractility comparable to unexposed controls. Interestingly, NACA did not provide any additional treatment effect beyond NAC in both models. In conclusion, the establishment of a pig model for Cl2-induced lung damage supports further investigation of NAC as a potential treatment. However, the lack of protective effects on AHR after NAC treatment in mice suggests that NAC alone may not be sufficient as a complete treatment for Cl2 injuries. Optimization of existing medications with a polypharmacy approach may be more successful in addressing the complex sequelae of Cl2-induced lung injury.

Can coenzyme Q10 alleviate the toxic effect of fenofibrate on skeletal muscle?

Fenofibrate (FEN) is an antilipidemic drug that increases the activity of the lipoprotein lipase enzyme, thus enhancing lipolysis; however, it may cause myopathy and rhabdomyolysis in humans. Coenzyme Q10 (CoQ10) is an endogenously synthesized compound that is found in most living cells and plays an important role in cellular metabolism. It acts as the electron carrier in the mitochondrial respiratory chain. This study aimed to elucidate FEN-induced skeletal muscle changes in rats and to evaluate CoQ10 efficacy in preventing or alleviating these changes. Forty adult male rats were divided equally into four groups: the negative control group that received saline, the positive control group that received CoQ10, the FEN-treated group that received FEN, and the FEN + CoQ10 group that received both FEN followed by CoQ10 daily for 4 weeks. Animals were sacrificed and blood samples were collected to assess creatine kinase (CK). Soleus muscle samples were taken and processed for light and electron microscopic studies. This study showed that FEN increased CK levels and induced inflammatory cellular infiltration and disorganization of muscular architecture with lost striations. FEN increased the percentage of degenerated collagen fibers and immune expression of caspase-3. Ultrastructurally, FEN caused degeneration of myofibrils with distorted cell organelles. Treatment with CoQ10 could markedly ameliorate these FEN-induced structural changes and mostly regain the normal architecture of muscle fibers due to its antifibrotic and antiapoptotic effects. In conclusion, treatment with CoQ10 improved muscular structure by suppressing oxidative stress, attenuating inflammation, and inhibiting apoptosis.

Crosstalk between Inflammation and Hemorrhage/Coagulation Disorders in Primary Blast Lung Injury

Primary blast lung injury (PBLI), caused by exposure to high-intensity pressure waves from explosions in war, terrorist attacks, industrial production, and life explosions, is associated with pulmonary parenchymal tissue injury and severe ventilation insufficiency. PBLI patients, characterized by diffused intra-alveolar destruction, including hemorrhage and inflammation, might deteriorate into acute respiratory distress syndrome (ARDS) with high mortality. However, due to the absence of guidelines about PBLI, emergency doctors and rescue teams treating PBLI patients rely on experience. The goal of this review is to summarize the mechanisms of PBLI and their cross-linkages, exploring potential diagnostic and therapeutic targets of PBLI. We summarize the pathophysiological performance and pharmacotherapy principles of PBLI. In particular, we emphasize the crosstalk between hemorrhage and inflammation, as well as coagulation, and we propose early control of hemorrhage as the main treatment of PBLI. We also summarize several available therapy methods, including some novel internal hemostatic nanoparticles to prevent the vicious circle of inflammation and coagulation disorders. We hope that this review can provide information about the mechanisms, diagnosis, and treatment of PBLI for all interested investigators.

Protective Effects of N-Acetylcysteine on Lipopolysaccharide-Induced Respiratory Inflammation and Oxidative Stress

As the leading cause of bovine respiratory disease (BRD), bacterial pneumonia can result in tremendous losses in the herd farming industry worldwide. N-acetylcysteine (NAC), an acetylated precursor of the amino acid L-cysteine, has been reported to have anti-inflammatory and antioxidant properties. To explore the protective effect and underlying mechanisms of NAC in ALI, we investigated its role in lipopolysaccharide (LPS)-induced bovine embryo tracheal cells (EBTr) and mouse lung injury models. We found that NAC pretreatment attenuated LPS-induced inflammation in EBTr and mouse models. Moreover, LPS suppressed the expression of oxidative-related factors in EBTr and promoted gene expression and the secretion of inflammatory cytokines. Conversely, the pretreatment of NAC alleviated the secretion of inflammatory cytokines and decreased their mRNA levels, maintaining stable levels of antioxidative gene expression. In vivo, NAC helped LPS-induced inflammatory responses and lung injury in ALI mice. The relative protein concentration, total cells, and percentage of neutrophils in BALF; the level of secretion of IL-6, IL-8, TNF-α, and IL-1β; MPO activity; lung injury score; and the expression level of inflammatory-related genes were decreased significantly in the NAC group compared with the LPS group. NAC also ameliorated LPS-induced mRNA level changes in antioxidative genes. In conclusion, our findings suggest that NAC affects the inflammatory and oxidative response, alleviating LPS-induced EBTr inflammation and mouse lung injury, which offers a natural therapeutic strategy for BRD.

Repurposing existing drugs for COVID-19: an endocrinology perspective

BACKGROUND

Coronavirus Disease 2019 (COVID-19) is a multi-systemic infection caused by the novel Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), that has become a pandemic. Although its prevailing symptoms include anosmia, ageusia, dry couch, fever, shortness of brief, arthralgia, myalgia, and fatigue, regional and methodological assessments vary, leading to heterogeneous clinical descriptions of COVID-19. Aging, uncontrolled diabetes, hypertension, obesity, and exposure to androgens have been correlated with worse prognosis in COVID-19. Abnormalities in the renin-angiotensin-aldosterone system (RAAS), angiotensin-converting enzyme-2 (ACE2) and the androgen-driven transmembrane serine protease 2 (TMPRSS2) have been elicited as key modulators of SARS-CoV-2.

MAIN TEXT

While safe and effective therapies for COVID-19 lack, the current moment of pandemic urges for therapeutic options. Existing drugs should be preferred over novel ones for clinical testing due to four inherent characteristics: 1. Well-established long-term safety profile, known risks and contraindications; 2. More accurate predictions of clinical effects; 3. Familiarity of clinical management; and 4. Affordable costs for public health systems. In the context of the key modulators of SARS-CoV-2 infectivity, endocrine targets have become central as candidates for COVID-19. The only endocrine or endocrine-related drug class with already existing emerging evidence for COVID-19 is the glucocorticoids, particularly for the use of dexamethasone for severely affected patients. Other drugs that are more likely to present clinical effects despite the lack of specific evidence for COVID-19 include anti-androgens (spironolactone, eplerenone, finasteride and dutasteride), statins, N-acetyl cysteine (NAC), ACE inhibitors (ACEi), angiotensin receptor blockers (ARB), and direct TMPRSS-2 inhibitors (nafamostat and camostat). Several other candidates show less consistent plausibility. In common, except for dexamethasone, all candidates have no evidence for COVID-19, and clinical trials are needed.

CONCLUSION

While dexamethasone may reduce mortality in severely ill patients with COVID-19, in the absence of evidence of any specific drug for mild-to-moderate COVID-19, researchers should consider testing existing drugs due to their favorable safety, familiarity, and cost profile. However, except for dexamethasone in severe COVID-19, drug treatments for COVID-19 patients must be restricted to clinical research studies until efficacy has been extensively proven, with favorable outcomes in terms of reduction in hospitalization, mechanical ventilation, and death.

Pretreatment of a matrix metalloproteases inhibitor and aprotinin attenuated the development of acute pancreatitis-induced lung injury in rat model

OBJECTIVE

Acute lung injury (ALI) is one of the most common extra-pancreatic complications of acute pancreatitis. In this study, we examined the protective effect of protease inhibitor aprotinin and a matrix metalloproteinase inhibitor (MMPi) on pulmonary inflammation in rats with severe pancreatitis-associated ALI.

METHOD

A rat model of acute pancreatitis (AP) was established by injecting sodium glycodeoxycholate (GDOC) into the pancreatic duct. Pharmacological interventions included pretreatment with a protease inhibitor aprotinin (10mg/kg) and a matrix metalloproteinase inhibitor (MMPi, 100g/kg). The extent of pancreatic and lung injury and systemic inflammation was assessed by examinations of blood, bronchoalveolar lavage (BAL), and lung tissue. Pancreatic or lung tissue edema was evaluated by tissue water content. Pulmonary arterial pressure and alveolar-capillary membrane permeability were evaluated post-injury via a catheter inserted into the pulmonary artery in an isolated, perfused lung model.

RESULTS

Pre-treatment with aprotinin or MMPi significantly decreased amylase and lactate dehydrogenase (LDH), and the wet/dry weight ratio of the lung and pancreas in AP rats. Compared to the GDOC alone group, administration of aprotinin or MMPi prevented pancreatitis-induced IL-6 increases in the lung. Similarly, treatment with aprotinin or MMPi significantly decreased the accumulation of white blood cells, oxygen radicals, nitrite/nitrates in both blood and BAL, and markedly reduced lung permeability.

CONCLUSION

Pretreatment with either aprotinin or MMPi attenuated the systemic inflammation and reduced the severity of lung and pancreas injuries. In short, our study demonstrated that inhibition of protease may be therapeutic to pulmonary inflammation in this GDOC-induced AP model.

Anti-TNFα therapy in inflammatory lung diseases

Increased levels of tumor necrosis factor (TNF) α have been linked to a number of pulmonary inflammatory diseases including asthma, chronic obstructive pulmonary disease (COPD), acute lung injury (ALI)/acute respiratory distress syndrome (ARDS), sarcoidosis, and interstitial pulmonary fibrosis (IPF). TNFα plays multiple roles in disease pathology by inducing an accumulation of inflammatory cells, stimulating the generation of inflammatory mediators, and causing oxidative and nitrosative stress, airway hyperresponsiveness and tissue remodeling. TNFα-targeting biologics, therefore, present a potentially highly efficacious treatment option. This review summarizes current knowledge on the role of TNFα in pulmonary disease pathologies, with a focus on the therapeutic potential of TNFα-targeting agents in treating inflammatory lung diseases.

Attenuation of Nitrogen Mustard-Induced Pulmonary Injury and Fibrosis by Anti-Tumor Necrosis Factor-α Antibody

Nitrogen mustard (NM) is a bifunctional alkylating agent that causes acute injury to the lung that progresses to fibrosis. This is accompanied by a prominent infiltration of macrophages into the lung and upregulation of proinflammatory/profibrotic cytokines including tumor necrosis factor (TNF)α. In these studies, we analyzed the ability of anti-TNFα antibody to mitigate NM-induced lung injury, inflammation, and fibrosis. Treatment of rats with anti-TNFα antibody (15 mg/kg, iv, every 9 days) beginning 30 min after intratracheal administration of NM (0.125 mg/kg) reduced progressive histopathologic alterations in the lung including perivascular and peribronchial edema, macrophage/monocyte infiltration, interstitial thickening, bronchiolization of alveolar walls, fibrin deposition, emphysema, and fibrosis. NM-induced damage to the alveolar-epithelial barrier, measured by bronchoalveolar lavage (BAL) protein and cell content, was also reduced by anti-TNFα antibody, along with expression of the oxidative stress marker, heme oxygenase-1. Whereas the accumulation of proinflammatory/cytotoxic M1 macrophages in the lung in response to NM was suppressed by anti-TNFα antibody, anti-inflammatory/profibrotic M2 macrophages were increased or unchanged. Treatment of rats with anti-TNFα antibody also reduced NM-induced increases in expression of the profibrotic mediator, transforming growth factor-β. This was associated with a reduction in NM-induced collagen deposition in the lung. These data suggest that inhibiting TNFα may represent an efficacious approach to mitigating lung injury induced by mustards.

Kallistatin protects against sepsis-related acute lung injury via inhibiting inflammation and apoptosis

Kallistatin, an endogenous plasma protein, exhibits pleiotropic properties in inhibiting inflammation, oxidative stress and apoptosis, as evidenced in various animal models and cultured cells. Here, we demonstrate that kallistatin levels were positively correlated with the concentration of total protein in bronchoalveolar lavage fluids (BALF) from patients with sepsis-related acute respiratory distress syndrome (ARDS), indicating a compensatory mechanism. Lower ratio of kallistatin to total protein in BALF showed a significant trend toward elevated neutrophil counts (P = 0.002) in BALF and increased mortality (P = 0.046). In lipopolysaccharide (LPS)-treated mice, expression of human kallistatin in lung by gene transfer with human kallistatin-encoding plasmid ameliorated acute lung injury (ALI) and reduced cytokine/chemokine levels in BALF. These mice exhibited attenuated lung epithelial apoptosis and decreased Fas/FasL expression compared to the control mice. Mouse survival was improved by kallistatin gene transfer or recombinant human kallistatin treatment after LPS challenge. In LPS-stimulated A549 human lung epithelial cells, kallistatin attenuated apoptosis, down-regulated Fas/FasL signaling, suppressed intracellular reactive oxygen species (ROS) and inhibited ROS-mediated NF-κB activation and inflammation. Furthermore, LPS-induced apoptosis was blocked by antioxidant N-acetylcysteine or NF-κB inhibitor via down-regulating Fas expression. These findings suggest the therapeutic potential of kallistatin for sepsis-related ALI/ARDS.

Modulating the Innate Immune Response to Influenza A Virus: Potential Therapeutic Use of Anti-Inflammatory Drugs

Infection by influenza A viruses (IAV) is frequently characterized by robust inflammation that is usually more pronounced in the case of avian influenza. It is becoming clearer that the morbidity and pathogenesis caused by IAV are consequences of this inflammatory response, with several components of the innate immune system acting as the main players. It has been postulated that using a therapeutic approach to limit the innate immune response in combination with antiviral drugs has the potential to diminish symptoms and tissue damage caused by IAV infection. Indeed, some anti-inflammatory agents have been shown to be effective in animal models in reducing IAV pathology as a proof of principle. The main challenge in developing such therapies is to selectively modulate signaling pathways that contribute to lung injury while maintaining the ability of the host cells to mount an antiviral response to control virus replication. However, the dissection of those pathways is very complex given the numerous components regulated by the same factors (i.e., NF kappa B transcription factors) and the large number of players involved in this regulation, some of which may be undescribed or unknown. This article provides a comprehensive review of the current knowledge regarding the innate immune responses associated with tissue damage by IAV infection, the understanding of which is essential for the development of effective immunomodulatory drugs. Furthermore, we summarize the recent advances on the development and evaluation of such drugs as well as the lessons learned from those studies.

Surface-active drug loaded lipopolymeric nanohybrid aerosol therapy: potential non-invasive way to mitigate lipopolysaccharide mediated inflammation in murine lungs

Non-invasive aerosol therapy of surface-active lipopolymeric nanohybrids co-delivers two drugs in inflamed lungs and also replenishes the depleted lung surfactant pool in inflamed alveoli following cellular uptake by the cells.

Measuring exhaled nitric oxide in animal models: methods and clinical implications

Animal models such as rats and mice are useful for studying the multiple roles of nitric oxide (NO) in various respiratory disorders. The production of NO is catalyzed by the three isoforms of the enzymes (NO synthases; NOS). Indirect assessment of NOS gene or protein expression only provides partial information on the role of NO in health and lung disease. NO can also be measured in exhaled air by invasive or non-invasive approaches as a direct and quantitative marker of NO production in animal models. Whilst addressing the different methods of exhaled NO analysis in small animals (rats and mice), this review also focuses on the possible clinical implications, and discusses the advantages and limitations of these methods.

Acute lung injury and acute respiratory distress syndrome: experimental and clinical investigations

Acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) can be associated with various disorders. Recent investigation has involved clinical studies in collaboration with clinical investigators and pathologists on the pathogenetic mechanisms of ALI or ARDS caused by various disorders. This literature review includes a brief historical retrospective of ALI/ARDS, the neurogenic pulmonary edema due to head injury, the long-term experimental studies and clinical investigations from our laboratory, the detrimental role of NO, the risk factors, and the possible pathogenetic mechanisms as well as therapeutic regimen for ALI/ARDS.

N-acetylcysteine attenuates ventilator-induced lung injury in an isolated and perfused rat lung model

N-acetylcysteine (NAC) suppresses the generation of reactive oxygen species (ROS) that are implicated in ventilator-induced lung injury (VILI). We thus hypothesised that NAC attenuates VILI. VILI was induced by mechanical ventilation with a tidal volume (Vt) of 15mlkg(-1) in isolated and perfused rat lung. NAC was administered in the perfusate prior to the onset of mechanical ventilation. A group ventilated with low Vt of 5mlkg(-1) served as control. Haemodynamics, lung injury indices, inflammatory responses and activation of apoptotic pathways were determined upon completion of the mechanical ventilation. There was an increase in lung permeability and lung weight gain after mechanical ventilation with high Vt, compared to low Vt. The levels of inflammatory cytokines including interleukin-1β (IL-1β), tumour necrosis factor-α (TNF-α) and macrophage inflammatory protein-2 (MIP-2) increased in lung lavage fluids; the concentrations of H(2)O(2) were higher in lung lavage fluids, and the expression of myeloperoxidase (MPO), JNK, P38, pAKT and caspase-3 in lung tissue was greater in the high Vt than in the low Vt group. The concentrations of glutathione (GSH) in lung tissue were higher in low Vt than those in high Vt. The administration of NAC increased GSH, attenuated ROS, cytokines, MPO, JNK, pAKT and caspase-3 and lung permeability associated with decreased activation of nuclear factor-κB. VILI is associated with inflammatory responses including the generation of ROS, cytokines and the activation of mitogen-activated protein kinase cascade. The administration of NAC attenuates the inflammatory responses, apoptosis and VILI in the isolated, perfused rat lung model.

The effect of post-treatment N-acetylcysteine in LPS-induced acute lung injury of rats

Background

Oxidation plays an important role in acute lung injury. This study was conducted in order to elucidate the effect of repetitive post-treatment of N-acetylcysteine (NAC) in lipopolysaccaride (LPS)-induced acute lung injury (ALI) of rats.

Methods

Six-week-old male Sprague-Dawley rats were divided into 4 groups. LPS (Escherichia coli 5 mg/kg) was administered intravenously via the tail vein. NAC (20 mg/kg) was injected intraperitoneally 3, 6, and 12 hours after LPS injection. Broncho-alveolar lavage fluid (BALF) and lung tissues were obtained to evaluate the ALI at 24 hours after LPS injection. The concentration of tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β) were measured in BALF. Nuclear factor κB (NF-κB), lipid peroxidation (LPO), and myeloperoxidase (MPO) were measured using lung tissues. Micro-computed tomography (micro-CT) images were examined in each group at 72 hours apart from the main experiments in order to observe the delayed effects of NAC.

Results

TNF-α and IL-1β concentration in BALF were not different between LPS and NAC treatment groups. The concentration of LPO in NAC treatment group was significantly lower than that of LPS group (5.5±2.8 nmol/mL vs. 16.5±1.6 nmol/mL) (p=0.001). The activity of MPO in NAC treatment group was significantly lower than that of LPS group (6.4±1.8 unit/g vs. 11.2±6.3 unit/g, tissue) (p<0.048). The concentration of NF-κB in NAC treatment group was significantly lower than that of LPS group (0.3±0.1 ng/µL vs. 0.4±0.2 ng/µL) (p=0.0001). Micro-CT showed less extent of lung injury in NAC treatment than LPS group.

Conclusion

After induction of ALI with lipopolysaccharide, the therapeutic administration of NAC partially attenuated the extent of ALI through the inhibition of NF-κB activation.

Effect of N-acetylcysteine (NAC) on acute lung injury and acute kidney injury in hemorrhagic shock

AIM OF THE STUDY

N-acetylcysteine (NAC) has been investigated to attenuate organ injury in various experimental and clinical studies. However, results in hemorrhagic shock (HS) were controversial. We determined the effects of continuous administration of NAC on acute lung injury (ALI) and acute kidney injury (AKI) in HS model.

METHODS

Twenty male Sprague-Dawley rats were used. Pressure controlled HS model defined by mean arterial pressure (MAP) 40±2 mmHg for 90 min followed by resuscitation and observation was used. Rats (n=10 per group) were randomized into 2 groups with NAC or dextrose. Intravenous NAC was given continuously from 15 min after induction of HS to the end of observation period (2 h). We measured serum IL-6, nitrite/nitrate concentration. NF-κB p65 DNA binding activity, expressions of cytoplasmic phosphorylated IκB-α (p-IκB-α) and IκB-α, malondialdehyde (MDA) and histopathological injury scores in lung and kidney were also evaluated.

RESULTS

MAP did not show any difference during the study period. NAC decreased histopathologic scores in both lung and kidney. Lung and kidney MDA levels were significantly lower in the NAC group compared to control group. Serum nitrite/nitrate and IL-6 were also significantly lower in the NAC group. The levels of lung cytoplasmic p-IκB-α expression was mitigated by NAC, and NF-κB p65 DNA binding activity was also significantly decreased in the NAC group.

CONCLUSIONS

Continuous infusion of NAC attenuated inflammatory response and acute lung and kidney injury after hemorrhagic shock in rats.

Acute respiratory distress syndrome and lung injury: Pathogenetic mechanism and therapeutic implication

To review possible mechanisms and therapeutics for acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). ALI/ARDS causes high mortality. The risk factors include head injury, intracranial disorders, sepsis, infections and others. Investigations have indicated the detrimental role of nitric oxide (NO) through the inducible NO synthase (iNOS). The possible therapeutic regimen includes extracorporeal membrane oxygenation, prone position, fluid and hemodynamic management and permissive hypercapnic acidosis etc. Other pharmacological treatments are anti-inflammatory and/or antimicrobial agents, inhalation of NO, glucocorticoids, surfactant therapy and agents facilitating lung water resolution and ion transports. β-adrenergic agonists are able to accelerate lung fluid and ion removal and to stimulate surfactant secretion. In conscious rats, regular exercise training alleviates the endotoxin-induced ALI. Propofol and N-acetylcysteine exert protective effect on the ALI induced by endotoxin. Insulin possesses anti-inflammatory effect. Pentobarbital is capable of reducing the endotoxin-induced ALI. In addition, nicotinamide or niacinamide abrogates the ALI caused by ischemia/reperfusion or endotoxemia. This review includes historical retrospective of ALI/ARDS, the neurogenic pulmonary edema due to head injury, the detrimental role of NO, the risk factors, and the possible pathogenetic mechanisms as well as therapeutic regimen for ALI/ARDS.

Niacinamide mitigated the acute lung injury induced by phorbol myristate acetate in isolated rat's lungs

BACKGROUND

Phorbol myristate acetate (PMA) is a strong neutrophil activator and has been used to induce acute lung injury (ALI). Niacinamide (NAC) is a compound of B complex. It exerts protective effects on the ALI caused by various challenges. The purpose was to evaluate the protective effects of niacinamide (NAC) on the PMA-induced ALI and associated changes.

METHODS

The rat's lungs were isolated in situ and perfused with constant flow. A total of 60 isolated lungs were randomized into 6 groups to received Vehicle (DMSO 100 μg/g), PMA 4 μg/g (lung weight), cotreated with NAC 0, 100, 200 and 400 mg/g (lung weight). There were 10 isolated lungs in each group. We measured the lung weight and parameters related to ALI. The pulmonary arterial pressure and capillary filtration coefficient (Kfc) were determined in isolated lungs. ATP (adenotriphosphate) and PARP [poly(adenosine diphophate-ribose) polymerase] contents in lung tissues were detected. Real-time PCR was employed to display the expression of inducible and endothelial NO synthases (iNOS and eNOS). The neutrophil-derived mediators in lung perfusate were determined.

RESULTS

PMA caused increases in lung weight parameters. This agent produced pulmonary hypertension and increased microvascular permeability. It resulted in decrease in ATP and increase in PARP. The expression of iNOS and eNOS was upregulated following PMA. PMA increased the neutrophil-derived mediators. Pathological examination revealed lung edema and hemorrhage with inflammatory cell infiltration. Immunohistochemical stain disclosed the presence of iNOS-positive cells in macrophages and endothelial cells. These pathophysiological and biochemical changes were diminished by NAC treatment. The NAC effects were dose-dependent.

CONCLUSIONS

Our results suggest that neutrophil activation and release of neutrophil-derived mediators by PMA cause ALI and associated changes. NO production through the iNOS-producing cells plays a detrimental role in the PMA-induced lung injury. ATP is beneficial, while PARP plays a deteriorative effect on the PMA-induced ALI. NAC exerts protective effects on the inflammatory cascade leading to pulmonary injury. This B complex compound may be applied for clinical usage and therapeutic regimen.

N-acetylcysteine prevents pulmonary edema and acute kidney injury in rats with sepsis submitted to mechanical ventilation

Sepsis is a common cause of acute kidney injury (AKI) and acute lung injury. Oxidative stress plays as important role in such injury. The aim of this study was to evaluate the effects that the potent antioxidant N-acetylcysteine (NAC) has on renal and pulmonary function in rats with sepsis. Rats, treated or not with NAC (4.8 g/l in drinking water), underwent cecal ligation and puncture (CLP) 2 days after the initiation of NAC treatment, which was maintained throughout the study. At 24 h post-CLP, renal and pulmonary function were studied in four groups: control, control + NAC, CLP, and CLP + NAC. All animals were submitted to low-tidal-volume mechanical ventilation. We evaluated respiratory mechanics, the sodium cotransporters Na-K-2Cl (NKCC1) and the α-subunit of the epithelial sodium channel (α-ENaC), polymorphonuclear neutrophils, the edema index, oxidative stress (plasma thiobarbituric acid reactive substances and lung tissue 8-isoprostane), and glomerular filtration rate. The CLP rats developed AKI, which was ameliorated in the CLP + NAC rats. Sepsis-induced alterations in respiratory mechanics were also ameliorated by NAC. Edema indexes were lower in the CLP + NAC group, as was the wet-to-dry lung weight ratio. In CLP + NAC rats, α-ENaC expression was upregulated, whereas that of NKCC1 was downregulated, although the difference was not significant. In the CLP + NAC group, oxidative stress was significantly lower and survival rates were significantly higher than in the CLP group. The protective effects of NAC (against kidney and lung injury) are likely attributable to the decrease in oxidative stress, suggesting that NAC can be useful in the treatment of sepsis.

N-Acetylcysteine modulates acute lung injury induced by Pseudomonas aeruginosa in rats

1. In critically ill patients, Pseudomonas aeruginosa-induced pneumonia and the lung injury associated with infection are major causes of mortality. The aim of the present study was to evaluate the protective properties of N-acetylcysteine (NAC) in rats infected with P. aeruginosa and the role of nitric oxide synthases (NOS) protein in this process. 2. Pneumonia was induced in rats by infecting them with P. aeruginosa intratracheally. One group of rats was treated with NAC (150 mg/kg per day, i.p., for 7 days). An untreated group served as the control. Samples were collected both before (0 h) and after infection (24 h). Bacterial loads in lung tissue, the lung wet : dry (W/D) ratio and pulmonary vascular permeability were assessed. Total cell and polymorphonuclear leucocyte cell counts in bronchoalveolar lavage fluid were determined. The expression of inducible (i) NOS and endothelial (e) NOS protein was analysed and correlated with indices of lung injury using Pearson's correlation analysis. 3. Bacterial load, lung injury indices and NOS expression increased after infection. Pretreatment with NAC mitigated lung injury although it did not significantly change bacterial loads. Furthermore, NAC treatment increased eNOS protein expression, but decreased iNOS expression, in lung tissues after infection. The expression of iNOS protein was positively correlated with indices of lung injury, whereas there was a negative correlation between eNOS expression and lung injury indices. 4. N-Acetylcysteine modulated P. aeruginosa-induced lung injury in rats. The results suggest that this effect maybe due to regulation of iNOS and eNOS protein expression by NAC.

N-acetylcysteine attenuates phosgene-induced acute lung injury via up-regulation of Nrf2 expression

Previous studies indicated that oxidative stress was involved in phosgene-induced acute lung injury (ALI) and many antioxidants had been used to prevent ALI. N-acetylcysteine (NAC) had been used to protect ALI induced by various types of oxidative stress. Considering the limited information of NAC on phosgene-induced ALI, the purpose of this study was to elucidate the molecular mechanisms of phosgene-induced ALI and the protective effects of NAC. This study discovered that intraperitoneal administration of NAC significantly alleviated phosgene-induced pulmonary edema, as confirmed by decreased lung wet to dry weight ratio and oxidative stress markers. The content of l-gamma-glutamyl-l-cysteinyl-glycine (glutathione; GSH) and the ratio of the reduced and disulfide forms (GSH/GSSG), significant indicators of the antioxidative ability, were apparently inhibited by phosgene exposure. However, both indicators could be reversed by NAC administration, indicating that dysregulation of redox status of glutathione might be the cause of phosgene-induced ALI. The nuclear factor (NF)-E2-related factor 2 (Nrf2), which has been proven to up-regulate the expression of glutathione reductase (GR), was obviously decreased by phosgene exposure. However, NAC administration elevated Nrf2 expression significantly. In conclusion, these data provided the first evidences showing that it was the transcriptional factor Nrf2 that connected phosgene-induced ALI with GSH metabolism. NAC protected against oxidative stress through acting on this newly disclosed Nrf2/GR/GSH pathway, by which NAC elevated the biosynthesis of protective GSH to repair and reconstitute the defense system destroyed by phosgene.

Beneficial effects of N-acetylcysteine in treatment resistant schizophrenia

Poor response to antipsychotics is still an important problem in the treatment of many schizophrenia patients. N-acetylcysteine (NAC) is a compound that exerts anti-oxidant and scavenging actions against reactive oxygen species. This paper reports a case of poorly responsive schizophrenia patient who improved considerably with add-on NAC 600 mg/day. The NAC might work through activating cysteine-glutamate antiporters or reducing in nitric oxide (NO) metabolites, free radicals and cytokines or through both of these mechanisms.

Nitro-oleic acid protects against endotoxin-induced endotoxemia and multiorgan injury in mice

Nitroalkene derivatives of nitro-oleic acid (OA-NO2) are endogenous lipid products with potent anti-inflammatory properties in vitro. The present study was undertaken to evaluate the in vivo anti-inflammatory effect of OA-NO2 in mice given LPS. Two days before LPS administration, C57BL/6J mice were chronically infused with vehicle (LPS vehicle) or OA-NO2 (LPS OA-NO2) at 200 microg x kg(-1) x day(-1) via osmotic minipumps; LPS was administered via a single intraperitoneal (ip) injection (10 mg/kg in saline). A third group received an ip injection of saline without LPS or OA-NO2 and served as controls. At 18 h of LPS administration, LPS vehicle mice displayed multiorgan dysfunction as evidenced by elevated plasma urea and creatinine (kidney), aspartate aminotransferase (AST) and alanine aminotransferase (ALT; liver), and lactate dehydrogenase (LDH) and reduced ejection fraction (heart). In contrast, the severity of multiorgan dysfunction was less in LPS OA-NO2 animals. The levels of circulating TNF-alpha and renal TNF-alpha mRNA expression, together with renal mRNA expression of monocyte chemoattractant protein-1, ICAM-1, and VCAM-1, and with renal mRNA and protein expression of inducible nitric oxide synthase and cyclooxygenase 2, and renal cGMP and PGE2 contents, were greater in LPS vehicle vs. control mice, but were attenuated in LPS OA-NO2 animals. Similar patterns of changes in the expression of inflammatory mediators were observed in the liver. Together, pretreatment with OA-NO2 ameliorated the inflammatory response and multiorgan injury in endotoxin-induced endotoxemia in mice.

Recombinant human thioredoxin-1 becomes oxidized in circulation and suppresses bleomycin-induced neutrophil recruitment in the rat airway

Thioredoxin-1 (TRX) is a redox-active protein with anti-inflammatory effects. This study investigated the optimal delivery method and the mechanisms of recombinant human TRX (rhTRX) to suppress neutrophil recruitment in a rat bleomycin (BLM)-induced sustained acute lung injury model. In male Wister rats intratracheally administered with 0.125 mg/kg BLM, 8 mg/kg/day rhTRX was intravenously administered on days 3-6 using one of three protocols: daily bolus injection, 3 h daily infusion or continuous infusion for 96 h. Only the continuous-infusion of rhTRX significantly reduced the neutrophil infiltration compared with the other two methods. The BLM-induced down-regulation of L-selectin expression on circulating neutrophils was inhibited by rhTRX. Oxidized rhTRX showed a comparable effect with reduced rhTRX and rhTRX incubated with plasma or circulating in plasma was more than 99% oxidized. These results suggest that rhTRX becomes oxidized in circulation and continuous infusion of rhTRX suppresses neutrophil recruitment in the airway.

Cysteine redox potential determines pro-inflammatory IL-1beta levels

BACKGROUND

Cysteine (Cys) and its disulfide, cystine (CySS) represent the major extracellular thiol/disulfide redox control system. The redox potential (E(h)) of Cys/CySS is centered at approximately -80 mV in the plasma of healthy adults, and oxidation of E(h) Cys/CySS is implicated in inflammation associated with various diseases.

METHODOLOGY/PRINCIPAL FINDINGS

The purpose of the present study was to determine whether oxidized E(h) Cys/CySS is a determinant of interleukin (IL)-1beta levels. Results showed a 1.7-fold increase in secreted pro-IL-1beta levels in U937 monocytes exposed to oxidized E(h) Cys/CySS (-46 mV), compared to controls exposed to a physiological E(h) of -80 mV (P<0.01). In LPS-challenged mice, preservation of plasma E(h) Cys/CySS from oxidation by dietary sulfur amino acid (SAA) supplementation, was associated with a 1.6-fold decrease in plasma IL-1beta compared to control mice fed an isonitrogenous SAA-adequate diet (P<0.01). Analysis of E(h) Cys/CySS and IL-1beta in human plasma revealed a significant positive association between oxidized E(h) Cys/CySS and IL-1beta after controlling for age, gender, and BMI (P<0.001).

CONCLUSIONS/SIGNIFICANCE

These data show that oxidized extracellular E(h) Cys/CySS is a determinant of IL-1beta levels, and suggest that strategies to preserve E(h) Cys/CySS may represent a means to control IL-1beta in inflammatory disease states.

Amifostine reduces lung vascular permeability via suppression of inflammatory signalling

Despite an encouraging outcome of antioxidant therapy in animal models of acute lung injury, effective antioxidant agents for clinical application remain to be developed. The present study investigated the effect of pre-treatment with amifostine, a thiol antioxidant compound, on lung endothelial barrier dysfunction induced by Gram-negative bacteria wall-lipopolysaccharide (LPS). Endothelial permeability was monitored by changes in transendothelial electrical resistance. Cytoskeletal remodelling and reactive oxygen species (ROS) production was examined by immunofluorescence. Cell signalling was assessed by Western blot. Measurements of Evans blue extravasation, cell count and protein content in bronchoalveolar lavage fluid were used as in vivo parameters of lung vascular permeability. Hydrogen peroxide, LPS and interleukin-6 caused cytoskeletal reorganisation and increased permeability in the pulmonary endothelial cells, reflecting endothelial barrier dysfunction. These disruptive effects were inhibited by pre-treatment with amifostine and linked to the amifostine-mediated abrogation of ROS production and redox-sensitive signalling cascades, including p38, extracellular signal regulated kinase 1/2, mitogen-activated protein kinases and the nuclear factor-kappaB pathway. In vivo, concurrent amifostine administration inhibited LPS-induced oxidative stress and p38 mitogen-activated protein kinase activation, which was associated with reduced vascular leak and neutrophil recruitment to the lungs. The present study demonstrates, for the first time, protective effects of amifostine against lipopolysaccharide-induced lung vascular leak in vitro and in animal models of lipopolysaccharide-induced acute lung injury.

Nitric oxide mediates acute lung injury caused by fat embolism in isolated rat's lungs

BACKGROUND

The involvement of nitric oxide (NO) in acute lung injury (ALI) induced by fat embolism (FE) has not been investigated. The present study elucidated the role of NO in ALI because of FE.

METHODS

FE was produced by introduction of fatty acid (corn oil micelles) into the isolated rat's lungs. Nonselective NO synthase (NOS) and selective inducible NOS (iNOS) inhibitors, N-nitro-l-arginine methyl ester (l-NAME) and l-N(1-iminoethyl)-lysine (l-Nil) as well as NO donors, sodium nitroprusside (SNP), and S-nitroso-N-acetylpenicillamine (SNAP) at a dose of 10 mol/L were given 60 minutes before FE. There were six groups of isolated lungs randomly assigned to receive vehicle (physiologic saline solution), FE, FE with pretreatment of l-NAME, l-Nil, SNP, or SNAP. Each group was observed for 4 hours.

RESULTS

FE significantly increased the lung weight changes, pulmonary arterial pressure, and microvascular permeability. The concentration of nitrate or nitrite, methyl guanidine, tumor necrosis factor-alpha, and interleukin-1beta was significantly elevated after FE. Hisotopathologic examination revealed lung edema with multiple fatty droplets in lung tissue. Pretreatment with l-NAME or l-Nil attenuated, whereas SNP or SNAP exacerbated most of the FE-induced changes. Addition of NO donors (SNP or SNAP) into the isolated lungs did not produce significant changes in the lungs, suggesting that NO donation alone without FE does not exerts harmful effect.

CONCLUSIONS

Our results suggest that NO production through the iNOS isoform plays a detrimental role in the FE-induced ALI. Free radical and proinflammatory cytokines may also be involved in the pathogenesis of ALI because of FE.

N-acetylcysteine attenuates acute lung injury induced by fat embolism

OBJECTIVES

Fat embolism syndrome is a clinical issue in subjects with long-bone fracture. It may lead to acute lung injury. The mechanisms and therapeutic regimen remain unclear. The present study was designed to investigate the pathologic and biochemical changes after fat embolization in isolated rat lungs, and to test the effects of posttreatment with N-acetylcysteine (NAC).

DESIGN

Prospective, randomized, controlled animal study.

SETTING

University research laboratory.

SUBJECTS

A total of 36 perfused lungs isolated from Sprague-Dawley rats.

INTERVENTIONS

The isolated lungs were randomly assigned to receive physiologic saline solution (vehicle group), fat embolism (FE group), or FE with NAC posttreatment (FE + NAC group). There were 12 isolated lungs in each group. FE was produced by introduction of corn oil micelles. NAC at a dose 150 mg/kg was given 10 mins after FE.

MEASUREMENTS AND MAIN RESULTS

The extent of acute lung injury was evaluated by lung weight change, protein concentration in bronchoalveolar lavage, and exhaled nitric oxide. We also measured the pulmonary arterial pressure and capillary filtration coefficient and determined the nitrate/nitrite, methylguanidine, tumor necrosis factor-alpha, and interleukin-1beta in lung perfusate. Histopathologic changes of the lung were examined and quantified. The levels of neutrophil elastase and myeloperoxidase were determined. The expression of inducible nitric oxide synthase was detected. FE caused acute lung injury as evidenced by the lung weight changes, increases in exhaled nitric oxide and protein concentration in bronchoalveolar lavage, pulmonary hypertension, increased capillary filtration coefficient, and lung pathology. The insult also increased nitrate/nitrite, methylguanidine, tumor necrosis factor-alpha, and interleukin-1beta in lung perfusate, increased neutrophil elastase and myeloperoxidase levels, and upregulated inducible nitric oxide synthase expression. Posttreatment with NAC abrogated these changes induced by FE.

CONCLUSION

FE caused acute lung injury and associated biochemical changes. Posttreatment with NAC was effective to alleviate the pathologic and biochemical changes caused by FE.

Niacinamide abrogates the organ dysfunction and acute lung injury caused by endotoxin

Poly (ADP-ribose) synthabse (PARS) or polymerase (PARP) is a cytotoxic enzyme causing cellular damage. Niacinamide inhibits PARS or PARP. The present experiment tests the effects of niacinamide (NCA) on organ dysfunction and acute lung injury (ALI) following lipopolysaccharide (LPS). LPS was administered to anesthetized rats and to isolated rat lungs. In anesthetized rats, LPS caused systemic hypotension and increased biochemical factors, nitrate/nitrite (NOx), methyl guanidine (MG), tumor necrosis factoralpha (TNFalpha), and interleukin-1beta (IL-1beta). In isolated lungs, LPS increased lung weight (LW) to body weight ratio, LW gain, protein and dye tracer leakage, and capillary permeability. The insult also increased NOx, MG, TNFalpha, and IL-1beta in lung perfusate, while decreased adenosine triphosphate (ATP) content with an increase in PARP activity in lung tissue. Pathological examination revealed pulmonary edema with inflammatory cell infiltration. These changes were abrogated by posttreatment (30 min after LPS) with NCA. Following LPS, the inducible NO synthase (iNOS) mRNA expression was increased. NCA reduced the iNOS expression. Niacinamide exerts protective effects on the organ dysfunction and ALI caused by endotoxin. The mechanisms may be mediated through the inhibition on the PARP activity, iNOS expression and the subsequent suppression of NO, free radicals, and proinflammatory cytokines with restoration of ATP.

The detrimental role of inducible nitric oxide synthase in the pulmonary edema caused by hypercalcemia in conscious rats and isolated lungs

We aim to test the hypothesis that hypercalcemia produces pulmonary edema (PE) and to elucidate the mechanism. Experimentations were carried out in conscious rats and isolated perfused rat lungs. We evaluated PE by lung weight changes, protein concentration in bronchoalveolar lavage, dye leakage, and microvascular permeability. Plasma nitrate/nitrite, methyl guanidine (MG), proinflammatory cytokines, procalcitonin levels, and histopathological examinations were evaluated. Immunochemical staining and reverse-transcriptase polymerase chain reaction (RT-PCR) were used to detect inducible nitric oxide synthase (iNOS) and endothelial NOS (eNOS) in the lungs. Hypercalcemia was produced in the conscious rat and isolated perfused lungs. Calcitonin and L-N(6) (1-iminoethyl)-lysine (L-Nil) were administered before hypercalcemia to observe their effects. Hypercalcemia caused severe PE in rats. Pathological and immunochemical examinations revealed hemorrhagic edema with iNOS activity in the alveolar macrophages and epithelial cells. RT-PCR showed an increase in iNOS mRNA expression. Hypercalcemia increased nitrate/nitrite, MG, proinflammatory cytokines and procalcitonin levels. Pretreatment with calcitonin or L-Nil prevented these changes. In conclusion, hypercalcemia caused PE in conscious rats and isolated perfused rat lungs. The increases in nitrate/nitrite, free radicals, proinflammatory cytokines, procalcitonin and iNOS activity suggest that hypercalcemia induces a sepsis-like syndrome. The effect of hypercalcemia on the lung may involve iNOS and NO.

Protective effect of N-acetylcysteine against radiation induced DNA damage and hepatic toxicity in rats

The present study was designed to evaluate the radioprotective effect of N- acetylcysteine (NAC) on gamma-radiation induced toxicity in hepatic tissue in rat. The cellular changes were estimated using malondialdehyde (MDA, an index of lipid peroxidation), superoxide dismutase (SOD), glutathione peroxidase (GSHPx), reduced glutathione (GSH), and total nitrate/nitrite (NO(x)) as markers of hepatic oxidative stress in rats following gamma-irradiation. The DNA damage was determined by agarose gel electrophoresis. To achieve the ultimate goal of this study, 40 adult rats were randomly divided into 4 groups of 10 animals each. Group I was injected intraperitoneally with saline solution for 7 consecutive days and served as control group. Group II was irradiated with a single dose of 6Gy gamma-radiation. Group III was daily injected with NAC (1g/kg, i.p.) for 7 consecutive days. Group IV received a daily i.p. injection of NAC (1g/kg, i.p.) for 7 consecutive days and 1h after the last dose, rats were irradiated with a single dose (6Gy) gamma-radiation. The animals were sacrificed after 24h. DNA damage was observed in tissue after total body irradiation with a single dose of 6Gy. Malondialdehyde and total nitrate/nitrite were increased significantly whereas the levels of GSH and antioxidant enzymes were significantly decreased in gamma-irradiated group. Pretreatment with NAC showed a significant decrease in the levels of MDA, NO(x) and DNA damage. The antioxidant enzymes increased significantly along with the levels of GSH. Moreover, histopathological examination of liver tissues confirmed the biochemical data. Thus, our results show that pretreatment with N-acetylcysteine offers protection against gamma-radiation induced cellular damage.

Endotoxin-induced acute lung injury and organ dysfunction are attenuated by pentobarbital anaesthesia

1. Acute lung injury (ALI) as a result of sepsis is a major cause of mortality. Certain anaesthetic agents have been reported to suppress pro-inflammatory cytokines and inducible nitric oxide (NO) synthase (iNOS) activities. We investigated the effects of pentobarbital on ALI and organ functions after the administration of endotoxin. 2. Intravenous (i.v.) pentobarbital (20 or 40 mg/kg) was administered 5 min after lipopolysaccharide (LPS; 10 or 30 mg/kg via i.v. infusion). To avoid hypoxia and/or hypercapnia following anaesthesia, we installed a special chamber connected to a rodent ventilator to provide ventilation with 95% oxygen content and 5% nitrogen. The animal was kept at eucapnic conditions (arterial PCO2 at an average of 38 +/- 2 mmHg). 3. We monitored the arterial pressure (AP) and heart rate (HR). Acute lung injury was evaluated by lung weight changes, protein concentration in bronchoalveolar lavage, and Evans blue leakage. Plasma nitrate/nitrite, methyl guanidine and biochemical factors were determined. Pathological and immunofluorescent examinations were performed to observe the lung changes and to determine the activities of pro-inflammatory cytokines, nitrotyrosine and iNOS. 4. Lipopolysaccharide caused dose-dependent systemic hypotension with an increase in the extent of ALI. The lung pathology included oedema and inflammatory cell infiltration. Accompanying the ALI, LPS elevated plasma nitrate/nitrite, methyl guanidine, blood urea nitrogen, lactic dehydrogenase, creatinine phosphokinase, glutamic transaminase and amylase. The lung tissue content of tumour necrosis factor-alpha, interleukin-lbeta, iNOS and nitrotyrosine was increased following LPS administration. These changes were abrogated by pentobarbital anaesthesia. 5. Our results indicated that pentobarbital anaesthesia significantly augmented the LPS-induced systemic hypotension. However, it attenuated the LPS-induced ALI and organ dysfunctions. This agent also improved the survival rate following LPS at high and low doses. This mechanism may be related to the inhibitory effects on the increases in the production or activity of NO, free radicals, pro-inflammatory cytokines, nitrotyrosine and iNOS.

Inhibition of inducible nitric oxide synthase attenuates acute endotoxin-induced lung injury in rats

1. In the present study, we investigated the effects of the inducible nitric oxide (iNOS) inhibitors S-methylisothiourea (SMT) and l-N(6)-(1-iminoethyl)-lysine (l-Nil) on endotoxin-induced acute lung injury (ALI), as well as the associated physiological, biomedical and pathological changes, in anaesthetized Sprague-Dawley rats and in rat isolated perfused lungs. 2. Endotoxaemia was induced by an intravenous (i.v.) infusion of lipopolysaccharide (LPS; Escherichia coli 10 mg/kg). Lipopolysaccharide produced systemic hypotension and tachycardia. It also increased the lung weight/bodyweight ratio, lung weight gain, exhaled nitric oxide (NO), the protein concentration in bronchoalveolar lavage and microvascular permeability. 3. Following infusion of LPS, plasma nitrate/nitrite, methyl guanidine, pro-inflammatory cytokines (tumour necrosis factor-alpha and interleukin-1beta) were markedly elevated. Pathological examination revealed severe pulmonary oedema and inflammatory cell infiltration. Pretreatment with SMT (3 mg/kg, i.v.) or l-Nil (3 mg/kg, i.v.) significantly attenuated the LPS-induced changes and ALI. 4. The results suggest that the inflammatory responses and ALI following infusion of LPS are due to the production of NO, free radicals and pro-inflammatory cytokines through the iNOS system. Inhibition of iNOS is effective in mitigating the endotoxaemic changes and lung pathology. Inhibitors of iNOS may be potential therapeutic agents for clinical application in patients with acute respiratory distress syndrome.

Exercise training attenuates septic responses in conscious rats

PURPOSE

To evaluate the effects of exercise training on the changes induced by endotoxin in arterial pressure, heart rate (HR), blood cells, biochemical factors, plasma nitrite/nitrate, methyl guanidine (MG), proinflammatory cytokines, and pathology of the heart, liver, and lung.

METHODS

Twenty-four 10-wk-old male Wistar-Kyoto rats weighing 320-350 g were randomly assigned into two groups. The exercise-trained group (Tr; N = 12) received exercise training for 4 wk. The control (Con) group was placed on the treadmill and remained sedentary for the same time period. Endotoxemia was induced by intravenous (i.v.) infusion of lipopolysaccharide (LPS; 10 mg.kg(-1)) for 20 min, after which the animals were observed for 72 h. The femoral artery was cannulated to monitor arterial pressure and HR. Blood samples were collected 1 h before and at various times after LPS infusion. We determined plasma nitrite/nitrate, MG, white blood cells, neutrophils, lymphocytes, red blood cells, blood urea nitrogen, creatinine (Cr), aspartate aminotransferase, alanine aminotransferase, lactic acid dehydrogenase, creatine phosphokinase, amylase, lipase, tumor necrosis factor(alpha), and interleukin-1(beta). The heart, liver, and lung were taken for pathological examination and assessment after the experiment.

RESULTS

The Tr group had lower basal levels of arterial pressure, HR, MG, neutrophils, and Cr than the Con group. Exercise training attenuated the LPS-induced decreases in blood cells. After LPS administration, plasma levels of nitrate/nitrite, MG, biochemical factors, and proinflammatory cytokines in the Con group were higher than in the Tr group. Pathological examination and assessment revealed that cardiac, hepatic, and pulmonary injury were more severe in the Con group than in the Tr group.

CONCLUSIONS

Exercise training attenuates septic responses and protects organs from damage in sepsis.

N-acetylcysteine attenuates the acute lung injury caused by phorbol myristate acetate in isolated rat lungs

Acute lung injury (ALI) caused by phorbol myristate acetate (PMA) is characterized by pulmonary edema and inflammatory cells infiltration. PMA-activated neutrophils in vivo and in vitro to release free radicals, pro-inflammatory cytokines, nitric oxide (NO) and other mediators. These mediators may be the causes of pulmonary hypertension and increased microvascular permeability. In the present study, we used isolated perfused rat lungs from Sprague-Dawley (SD) rats. The purpose was to evaluate the effects of pretreatment of N-acetylcysteine (NAC) on the PMA-induced ALI and associated changes. PMA (2 microg kg(-1)) was introduced into the lung perfusate. NAC (150 mg kg(-1)) was administered 10 min before PMA. Thirty isolated lungs were randomly assigned to receive vehicle (dimethyl sulfoxide, DMSO, the solvent for PMA, 100 microg g(-1)), PMA alone and PMA with NAC pretreatment. There were 10 lungs in each group. We measured the lung weight (LW) to body weight (BW) ratio (LW/BW), LW gain (LWG), exhaled nitric oxide (NO) and protein concentration in bronchoalveolar lavage (PCBAL). The pulmonary arterial pressure (PAP) and microvascular permeability (K(fc)) were assessed. The concentration of nitrate/nitrite, methyl guanidine (MG), tumor necrosis factor(alpha) (TNF(alpha)) and interleukin-1(beta) (IL-1(beta)) in lung perfusate were determined. In addition, we also evaluate the lung injury by histopathological examination and by grading system for the lung injury score (LIS). PMA caused severe ALI as evidenced by the marked increases in LW changes, exhaled NO, PCBAL, histopathological changes, and LIS. It also increased the nitrate/nitrite, MG, TNF(alpha), and IL-1(beta) in lung perfusate. Pretreatment with NAC significantly attenuated these changes and abrogated the extent of ALI. Our results suggest that NAC exerts strong protective effects on the PMA-induced ALI and associated alterations. The mechanisms are possibly attributable to its antioxidant actions, inhibition of pro-inflammatory cytokines, and restoration of glutathione enzymes.

Progress in Discovery and Evaluation of Treatments to Prevent Bronchopulmonary Dysplasia

BACKGROUND

Recent improvements in the survival of extremely preterm infants have been accompanied by evolution in the pathogenesis and histopathology of bronchopulmonary dysplasia (BPD). Although oxygen and barotrauma-induced injury remain important contributing factors, pulmonary developmental arrest appears to play an equally important causal role in prolonged respiratory illness, especially among the most immature surviving preterm newborns. To date, clinical trials have failed to demonstrate a substantial benefit of a single treatment or preventive strategy for BPD.

OBJECTIVES

To evaluate the current evidence in favor of treatments that might prevent BPD.

METHODS

Review of clinical studies of preventive treatment strategies for BPD.

RESULTS

High frequency oscillatory ventilation, permissive hypercapnea, and inhaled nitric oxide might offer benefit to infants at risk of BPD. These and other potential preventive therapies for BPD, such as superoxide dismutase, inositol, and alpha(1)-proteinase inhibitor, deserve further study.

CONCLUSIONS

Although some current treatments offer promise, no preventive therapy for BPD has proven safe and effective, except for intramuscular vitamin A. Additional studies of respiratory technologies, management strategies, and protective molecules are needed.