Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 28
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Mol Med ; 26(1): 16, 2020 02 03.
Artigo em Inglês | MEDLINE | ID: mdl-32013888

RESUMO

The Editors-in-Chief would like to alert readers that this article (Sitapara et al. 2014) is part of an investigation being conducted by the journal following the conclusions of an institutional enquiry at the University of Liverpool with respect to the quantitative mass spectrometry-generated results regarding acetylated and redox-modified HMGB1.

2.
Int J Mol Sci ; 21(3)2020 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-32024151

RESUMO

Mechanical ventilation with hyperoxia is the major supportive measure to treat patients with acute lung injury and acute respiratory distress syndrome (ARDS). However, prolonged exposure to hyperoxia can induce oxidative inflammatory lung injury. Previously, we have shown that high levels of airway high-mobility group box 1 protein (HMGB1) mediate hyperoxia-induced acute lung injury (HALI). Using both ascorbic acid (AA, also known as vitamin C) and sulforaphane (SFN), an inducer of nuclear factor (erythroid-derived 2)-like 2 (Nrf2), we tested the hypothesis that dietary antioxidants can mitigate HALI by ameliorating HMGB1-compromised macrophage function in phagocytosis by attenuating hyperoxia-induced extracellular HMGB1 accumulation. Our results indicated that SFN, which has been shown to attenute HALI in mice exposed to hyperoxia, dose-dependently restored hyperoxia-compromised macrophage function in phagocytosis (75.9 ± 3.5% in 0.33 µM SFN versus 50.7 ± 1.8% in dimethyl sulfoxide (DMSO) control, p < 0.05) by reducing oxidative stress and HMGB1 release from cultured macrophages (47.7 ± 14.7% in 0.33 µM SFN versus 93.1 ± 14.6% in DMSO control, p < 0.05). Previously, we have shown that AA enhances hyperoxic macrophage functions by reducing hyperoxia-induced HMGB1 release. Using a mouse model of HALI, we determined the effects of AA on hyperoxia-induced inflammatory lung injury. The i.p. administration of 50 mg/kg of AA to mice exposed to 72 h of ≥98% O2 significantly decreased hyperoxia-induced oxidative and nitrosative stress in mouse lungs. There was a significant decrease in the levels of airway HMGB1 (43.3 ± 12.2% in 50 mg/kg AA versus 96.7 ± 9.39% in hyperoxic control, p < 0.05), leukocyte infiltration (60.39 ± 4.137% leukocytes numbers in 50 mg/kg AA versus 100 ± 5.82% in hyperoxic control, p < 0.05) and improved lung integrity in mice treated with AA. Our study is the first to report that the dietary antioxidants, ascorbic acid and sulforaphane, ameliorate HALI and attenuate hyperoxia-induced macrophage dysfunction through an HMGB1-mediated pathway. Thus, dietary antioxidants could be used as potential treatments for oxidative-stress-induced acute inflammatory lung injury in patients receiving mechanical ventilation.

3.
Biochem Pharmacol ; : 113817, 2020 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-31972169

RESUMO

Mechanical ventilation (MV) with supraphysiological levels of oxygen (hyperoxia) is a life-saving therapy for the management of patients with respiratory distress. However, a significant number of patients on MV develop ventilator-associated pneumonia (VAP). Previously, we have reported that prolonged exposure to hyperoxia impairs the capacity of macrophages to phagocytize Pseudomonas aeruginosa (PA), which can contribute to the compromised innate immunity in VAP. In this study, we show that the high mortality rate in mice subjected to hyperoxia and PA infection was accompanied by a significant decrease in the airway levels of nitric oxide (NO). Decreased NO levels were found to be, in part, due to a significant reduction in NO release by macrophages upon exposure to PA lipopolysaccharide (LPS). Based on these findings, we postulated that NO supplementation should restore hyperoxia-compromised innate immunity and decrease mortality by increasing the clearance of PA under hyperoxic conditions. To test this hypothesis, cultured macrophages were exposed to hyperoxia (95% O2) in the presence or absence of the NO donor, (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (DETA-NONOate/D-NO). Interestingly, D-NO (up to 37.5 µM) significantly attenuated hyperoxia-compromised macrophage migratory, phagocytic, and bactericidal function. To determine whether the administration of exogenous NO enhances the host defense in bacteria clearance, C57BL/6 mice were exposed to hyperoxia (99% O2) and intranasally inoculated with PA in the presence or absence of D-NO. D-NO (300 µM-800 µM) significantly increased the survival of mice inoculated with PA under hyperoxic conditions, and significantly decreased bacterial loads in the lung and attenuated lung injury. These results suggest the NO donor, D-NO, can improve the clinical outcomes in VAP by augmenting the innate immunity in bacterial clearance. Thus, provided these results can be extrapolated to humans, NO supplementation may represent a potential therapeutic strategy for preventing and treating patients with VAP.

5.
Toxicol Sci ; 172(2): 398-410, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31504961

RESUMO

Carbon nanomaterials (CNMs) are widely used in industrial and medical sectors. The increasing exposure of CNMs necessitates the studies of their potential environmental and health effects. High-mobility group box-1 (HMGB1) is a nuclear DNA-binding protein, but when released from cells, may cause sustained inflammatory response and promote cell migration and invasion. In this work, we found that 7-day exposure of 2.5 mg/kg/day CNMs, including C60, single-walled carbon nanotubes, and graphene oxides significantly elevated the level of HMGB1 in blood and lung lavage fluids in C57BL/6 mice. Subsequently, cellular effects and underlying mechanism were explored by using Raw264.7. The results showed that noncytotoxic CNMs enhanced HMGB1 intracellular translocation and release via activating P2X7 receptor. Released HMGB1 further activated receptor for advanced glycation endproducts (RAGE) and downstream signaling pathway by upregulating RAGE and Rac1 expression. Simultaneously, CNMs prepared the cells for migration and invasion by modulating MMP2 and TIMP2 gene expression as well as cytoskeleton reorganization. Intriguingly, released HMGB1 from macrophages promoted the migration of nearby lung cancer cell, which can be efficiently inhibited by neutralizing antibodies against HMGB1 and RAGE. Taken together, our work demonstrated that CNMs stimulated HMGB1 release and cell migration/invasion through P2X7R-HMGB1-RAGE pathway. The revealed mechanisms might facilitate a better understanding on the inflammatory property and subsequent cell functional alteration of CNMs.

6.
Antioxid Redox Signal ; 31(13): 954-993, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31184204

RESUMO

Significance: High-mobility group protein box 1 (HMGB1), a ubiquitous nuclear protein, regulates chromatin structure and modulates the expression of many genes involved in the pathogenesis of lung cancer and many other lung diseases, including those that regulate cell cycle control, cell death, and DNA replication and repair. Extracellular HMGB1, whether passively released or actively secreted, is a danger signal that elicits proinflammatory responses, impairs macrophage phagocytosis and efferocytosis, and alters vascular remodeling. This can result in excessive pulmonary inflammation and compromised host defense against lung infections, causing a deleterious feedback cycle. Recent Advances: HMGB1 has been identified as a biomarker and mediator of the pathogenesis of numerous lung disorders. In addition, post-translational modifications of HMGB1, including acetylation, phosphorylation, and oxidation, have been postulated to affect its localization and physiological and pathophysiological effects, such as the initiation and progression of lung diseases. Critical Issues: The molecular mechanisms underlying how HMGB1 drives the pathogenesis of different lung diseases and novel therapeutic approaches targeting HMGB1 remain to be elucidated. Future Directions: Additional research is needed to identify the roles and functions of modified HMGB1 produced by different post-translational modifications and their significance in the pathogenesis of lung diseases. Such studies will provide information for novel approaches targeting HMGB1 as a treatment for lung diseases.

7.
Am J Respir Cell Mol Biol ; 55(4): 511-520, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27120084

RESUMO

Supraphysiological concentrations of oxygen (hyperoxia) can compromise host defense and increase susceptibility to bacterial infections, causing ventilator-associated pneumonia. The phagocytic activity of macrophages is impaired by hyperoxia-induced increases in the levels of reactive oxygen species (ROS) and extracellular high-mobility group box protein B1 (HMGB1). Ascorbic acid (AA), an essential nutrient and antioxidant, has been shown to be beneficial in various animal models of ROS-mediated diseases. The aim of this study was to determine whether AA could attenuate hyperoxia-compromised host defense and improve macrophage functions against bacterial infections. C57BL/6 male mice were exposed to hyperoxia (≥98% O2, 48 h), followed by intratracheal inoculation with Pseudomonas aeruginosa, and simultaneous intraperitoneal administration of AA. AA (50 mg/kg) significantly improved bacterial clearance in the lungs and airways, and significantly reduced HMGB1 accumulation in the airways. The incubation of RAW 264.7 cells (a macrophage-like cell line) with AA (0-1,000 µM) before hyperoxic exposure (95% O2) stabilized the phagocytic activity of macrophages in a concentration-dependent manner. The AA-enhanced macrophage function was associated with significantly decreased production of intracellular ROS and accumulation of extracellular HMGB1. These data suggest that AA supplementation can prevent or attenuate the development of ventilator-associated pneumonia in patients receiving oxygen support.

8.
Cancer Res ; 75(24): 5299-308, 2015 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-26542213

RESUMO

Altered nitric oxide (•NO) metabolism underlies cancer pathology, but mechanisms explaining many •NO-associated phenotypes remain unclear. We have found that cellular exposure to •NO changes histone posttranslational modifications (PTM) by directly inhibiting the catalytic activity of JmjC-domain containing histone demethylases. Herein, we describe how •NO exposure links modulation of histone PTMs to gene expression changes that promote oncogenesis. Through high-resolution mass spectrometry, we generated an extensive map of •NO-mediated histone PTM changes at 15 critical lysine residues on the core histones H3 and H4. Concomitant microarray analysis demonstrated that exposure to physiologic •NO resulted in the differential expression of over 6,500 genes in breast cancer cells. Measurements of the association of H3K9me2 and H3K9ac across genomic loci revealed that differential distribution of these particular PTMs correlated with changes in the level of expression of numerous oncogenes, consistent with epigenetic code. Our results establish that •NO functions as an epigenetic regulator of gene expression mediated by changes in histone PTMs.


Assuntos
Regulação Neoplásica da Expressão Gênica/fisiologia , Histonas/genética , Neoplasias/genética , Óxido Nítrico/metabolismo , Processamento de Proteína Pós-Traducional/genética , Linhagem Celular Tumoral , Epigênese Genética/fisiologia , Humanos , Espectrometria de Massas , Neoplasias/metabolismo , Análise de Sequência com Séries de Oligonucleotídeos
9.
Am J Respir Cell Mol Biol ; 52(2): 171-82, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24992505

RESUMO

The prolonged exposure to hyperoxia can compromise macrophage functions and contribute to the development of ventilator-associated pneumonia. High levels of extracellular high-mobility group box-1 (HMGB1) in the airways of mice exposed to hyperoxia can directly cause macrophage dysfunction. Hence, inhibition of the release of nuclear HMGB1 into the extracellular milieu may help to maintain macrophage functions under hyperoxic conditions. The present study investigates whether ethacrynic acid (EA) affects hyperoxia-induced HMGB1 release from macrophages and improves their functions. Macrophage-like RAW 264.7 cells and bone marrow-derived macrophages were exposed to different concentrations of EA for 24 hours in the presence of 95% O2. EA significantly decreased the accumulation of extracellular HMGB1 in cultured media. Importantly, the phagocytic activity and migration capability of macrophages were significantly enhanced in EA-treated cells. Interestingly, hyperoxia-induced NF-κB activation was also inhibited in these cells. To determine whether NF-κB plays a role in hyperoxia-induced HMGB1 release, BAY 11-7082, an inhibitor of NF-κB activation, was used. Similar to EA, BAY 11-7082 significantly inhibited the accumulation of extracellular HMGB1 and improved hyperoxia-compromised macrophage migration and phagocytic activity. Furthermore, 24-hour hyperoxic exposure of macrophages caused hyperacetylation of HMGB1 and its subsequent cytoplasmic translocation and release, which were inhibited by EA and BAY 11-7082. Together, these results suggest that EA enhances hyperoxia-compromised macrophage functions by inhibiting HMGB1 hyperacetylation and its release from macrophages, possibly through attenuation of the NF-κB activation. Therefore, the activation of NF-κB could be one of the underlying mechanisms that mediate hyperoxia-compromised macrophage functions.


Assuntos
Ácido Etacrínico/farmacologia , Proteína HMGB1/metabolismo , Hiperóxia/metabolismo , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , NF-kappa B/metabolismo , Transdução de Sinais/efeitos dos fármacos , Animais , Células Cultivadas , Lipopolissacarídeos/farmacologia , Camundongos , Fagocitose/efeitos dos fármacos , Fagocitose/fisiologia
10.
Methods Mol Biol ; 1172: 137-45, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24908301

RESUMO

Phagocytosis is the process by which phagocytes, including macrophages, neutrophils and monocytes, engulf and kill invading pathogens, remove foreign particles, and clear cell debris. Phagocytes and their ability to phagocytose are an important part of the innate immune system and are critical for homeostasis of the host. Impairment in phagocytosis has been associated with numerous diseases and disorders. Different cytokines have been shown to affect the phagocytic process. Cytokines including TNFα, IL-1ß, GM-CSF, and TGF-ß1 were found to promote phagocytosis, whereas high mobility group box-1 (HMGB1) inhibited the phagocytic function of macrophages. Here, we describe two commonly used methods to assess the phagocytic function of cultured macrophages, which can easily be applied to other phagocytes. Each method is based on the extent of engulfment of FITC-labeled latex minibeads by macrophages under different conditions. Phagocytic activity can be assessed either by counting individual cells using a fluorescence microscope or measuring fluorescence intensity using a flow cytometer.


Assuntos
Citometria de Fluxo/métodos , Macrófagos/efeitos dos fármacos , Microscopia de Fluorescência/métodos , Fagocitose/efeitos dos fármacos , Animais , Linhagem Celular , Fluoresceína-5-Isotiocianato , Corantes Fluorescentes , Expressão Gênica , Fator Estimulador de Colônias de Granulócitos e Macrófagos/farmacologia , Proteína HMGB1/genética , Proteína HMGB1/metabolismo , Interleucina-1beta/farmacologia , Macrófagos/citologia , Macrófagos/metabolismo , Camundongos , Microesferas , Fator de Crescimento Transformador beta1/farmacologia , Fator de Necrose Tumoral alfa/farmacologia
11.
Mol Med ; 20: 238-47, 2014 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-24664237

RESUMO

Mechanical ventilation with supraphysiological concentrations of oxygen (hyperoxia) is routinely used to treat patients with respiratory distress. However, prolonged exposure to hyperoxia compromises the ability of the macrophage to phagocytose and clear bacteria. Previously, we showed that the exposure of mice to hyperoxia elicits the release of the nuclear protein high mobility group box-1 (HMGB1) into the airways. Extracellular HMGB1 impairs macrophage phagocytosis and increases the mortality of mice infected with Pseudomonas aeruginosa (PA). The aim of this study was to determine whether GTS-21 [3-(2,4 dimethoxybenzylidene)-anabaseine dihydrochloride], an α7 nicotinic acetylcholine receptor (α7nAChR) agonist, could inhibit hyperoxia-induced HMGB1 release into the airways, enhance macrophage function and improve bacterial clearance from the lungs in a mouse model of ventilator-associated pneumonia. GTS-21 (0.04, 0.4 and 4 mg/kg) or saline was systemically administered via intraperitoneal injection to mice that were exposed to hyperoxia (≥99% O2) and subsequently challenged with PA. We found that systemic administration of 4 mg/kg GTS-21 significantly increased bacterial clearance, decreased acute lung injury and decreased accumulation of airway HMGB1. To investigate the cellular mechanism of these observations, RAW 264.7 cells, a macrophagelike cell line, were incubated with different concentrations of GTS-21 in the presence of 95% O2. The phagocytic activity of macrophages was significantly increased by GTS-21 in a dose-dependent manner. In addition, hyperoxia-induced hyperacetylation of HMGB1 was significantly reduced in macrophages incubated with GTS-21. Furthermore, GTS-21 significantly inhibited the cytoplasmic translocation and release of HMGB1 from these macrophages. Our results indicate that GTS-21 is effective in improving bacterial clearance and reducing acute lung injury by enhancing macrophage function via inhibiting the release of nuclear HMGB1. Therefore, the α7nAChR represents a possible pharmacological target to improve the clinical outcome of patients on ventilators by augmenting host defense against bacterial infections.


Assuntos
Compostos de Benzilideno/farmacologia , Hiperóxia/metabolismo , Macrófagos/efeitos dos fármacos , Agonistas Nicotínicos/farmacologia , Pneumonia Associada à Ventilação Mecânica/metabolismo , Piridinas/farmacologia , Receptor Nicotínico de Acetilcolina alfa7/agonistas , Animais , Carga Bacteriana , Líquido da Lavagem Broncoalveolar/química , Linhagem Celular , Proteína HMGB1/metabolismo , Pulmão/metabolismo , Pulmão/microbiologia , Macrófagos/metabolismo , Macrófagos/fisiologia , Masculino , Camundongos Endogâmicos C57BL , NF-kappa B/metabolismo , Fagocitose/efeitos dos fármacos , Pneumonia Associada à Ventilação Mecânica/microbiologia , Infecções por Pseudomonas/metabolismo , Infecções por Pseudomonas/microbiologia , Pseudomonas aeruginosa/isolamento & purificação , Receptor Nicotínico de Acetilcolina alfa7/metabolismo
12.
Redox Biol ; 2: 314-22, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24563849

RESUMO

Prolonged exposure to hyperoxia results in acute lung injury (ALI), accompanied by a significant elevation in the levels of proinflammatory cytokines and leukocyte infiltration in the lungs. However, the mechanisms underlying hyperoxia-induced proinflammatory ALI remain to be elucidated. In this study, we investigated the role of the proinflammatory cytokine high mobility group box protein 1 (HMGB1) in hyperoxic inflammatory lung injury, using an adult mouse model. The exposure of C57BL/6 mice to ≥99% O2 (hyperoxia) significantly increased the accumulation of HMGB1 in the bronchoalveolar lavage fluids (BALF) prior to the onset of severe inflammatory lung injury. In the airways of hyperoxic mice, HMGB1 was hyperacetylated and existed in various redox forms. Intratracheal administration of recombinant HMGB1 (rHMGB1) caused a significant increase in leukocyte infiltration into the lungs compared to animal treated with a non-specific peptide. Neutralizing anti-HMGB1 antibodies, administrated before hyperoxia significantly attenuated pulmonary edema and inflammatory responses, as indicated by decreased total protein content, wet/dry weight ratio, and numbers of leukocytes in the airways. This protection was also observed when HMGB1 inhibitors were administered after the onset of the hyperoxic exposure. The aliphatic antioxidant, ethyl pyruvate (EP), inhibited HMGB1 secretion from hyperoxic macrophages and attenuated hyperoxic lung injury. Overall, our data suggest that HMGB1 plays a critical role in mediating hyperoxic ALI through the recruitment of leukocytes into the lungs. If these results can be translated to humans, they suggest that HMGB1 inhibitors provide treatment regimens for oxidative inflammatory lung injury in patients receiving hyperoxia through mechanical ventilation.


Assuntos
Lesão Pulmonar Aguda/induzido quimicamente , Lesão Pulmonar Aguda/patologia , Anticorpos/administração & dosagem , Líquido da Lavagem Broncoalveolar/imunologia , Proteína HMGB1/metabolismo , Piruvatos/administração & dosagem , Acetilação , Lesão Pulmonar Aguda/imunologia , Lesão Pulmonar Aguda/terapia , Animais , Hipóxia Celular , Linhagem Celular , Modelos Animais de Doenças , Proteína HMGB1/antagonistas & inibidores , Injeções Espinhais , Pulmão/citologia , Pulmão/imunologia , Pulmão/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neutrófilos/metabolismo
13.
J Immunotoxicol ; 11(3): 260-7, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24099632

RESUMO

Nosocomial pneumonia (NP, or hospital-acquired pneumonia) is associated with infections originating from hospital-borne pathogens. Persistent microbial presence and acute lung injury are common features of these infections, contributing to the high mortality rates and excessive financial burden for these patients. Pseudomonas aeruginosa (PA), a gram-negative opportunistic pathogen, is one of the prominent pathogens associated with NP. PA pneumonia is characterized by excessive secretion of inflammatory cytokines, neutrophil infiltration, and subsequent lung damage. The persistent presence of PA along with overwhelming inflammatory response is suggestive of impairment in innate immunity. High mobility group box 1 (HMGB1), a recently discovered potent pro-inflammatory cytokine, plays an important role in PA lung infections by compromising innate immunity via impairing phagocyte function through toll-like receptors (TLR) TLR2 and TLR4. ODSH (2-O, 3-O-desulfated heparin), a heparin derivative with significant anti-inflammatory properties but minimal anti-coagulatory effects, has been shown to reduce neutrophilic lung injury in the absence of active microbial infections. This study examined the effects of ODSH on PA pneumonia. This study demonstrates that ODSH not only reduced PA-induced lung injury, but also significantly increased bacterial clearance. The ameliorated lung injury, together with the increased bacterial clearance, resulted in marked improvement in the survival of these animals. The resulting attenuation in lung injury and improvement in bacterial clearance were associated with decreased levels of airway HMGB1. Furthermore, binding of HMGB1 to its receptors TLR2 and TLR4 was blunted in the presence of ODSH. These data suggest that ODSH provides a potential novel approach in the adjunctive treatment of PA pneumonia.


Assuntos
Anti-Inflamatórios não Esteroides/administração & dosagem , Infecção Hospitalar/tratamento farmacológico , Heparina/análogos & derivados , Pulmão/efeitos dos fármacos , Pneumonia Pneumocócica/tratamento farmacológico , Infecções por Pseudomonas/tratamento farmacológico , Pseudomonas aeruginosa/fisiologia , Animais , Carga Bacteriana/efeitos dos fármacos , Infecção Hospitalar/imunologia , Modelos Animais de Doenças , Proteína HMGB1/genética , Proteína HMGB1/metabolismo , Heparina/administração & dosagem , Humanos , Imunidade Inata/efeitos dos fármacos , Pulmão/microbiologia , Pulmão/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Pneumonia Pneumocócica/imunologia , Infecções por Pseudomonas/imunologia , Regulação para Cima
14.
Am J Respir Cell Mol Biol ; 48(3): 280-7, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23087050

RESUMO

Mechanical ventilation with supraphysiological concentrations of oxygen (hyperoxia) is routinely used to treat patients with respiratory distress. However, a significant number of patients on ventilators exhibit enhanced susceptibility to infections and develop ventilator-associated pneumonia (VAP). Pseudomonas aeruginosa (PA) is one of the most common species of bacteria found in these patients. Previously, we demonstrated that prolonged exposure to hyperoxia can compromise the ability of alveolar macrophages (AMs), an essential part of the innate immunity, to phagocytose PA. This study sought to investigate the potential molecular mechanisms underlying hyperoxia-compromised innate immunity against bacterial infection in a murine model of PA pneumonia. Here, we show that exposure to hyperoxia (≥ 99% O2) led to a significant elevation in concentrations of airway high mobility group box-1 (HMGB1) and increased mortality in C57BL/6 mice infected with PA. Treatment of these mice with a neutralizing anti-HMGB1 monoclonal antibody (mAb) resulted in a reduction in bacterial counts, injury, and numbers of neutrophils in the lungs, and an increase in leukocyte phagocytic activity compared with mice receiving control mAb. This improved phagocytic function was associated with reduced concentrations of airway HMGB1. The correlation between phagocytic activity and concentrations of extracellular HMGB1 was also observed in cultured macrophages. These results indicate a pathogenic role for HMGB1 in hyperoxia-induced impairment with regard to a host's ability to clear bacteria and inflammatory lung injury. Thus, HMGB1 may provide a novel molecular target for improving hyperoxia-compromised innate immunity in patients with VAP.


Assuntos
Proteína HMGB1/metabolismo , Hiperóxia/metabolismo , Lesão Pulmonar/metabolismo , Lesão Pulmonar/microbiologia , Pneumonia Bacteriana/metabolismo , Infecções por Pseudomonas/metabolismo , Pseudomonas aeruginosa/metabolismo , Animais , Anticorpos Monoclonais/imunologia , Líquido da Lavagem Broncoalveolar/imunologia , Líquido da Lavagem Broncoalveolar/microbiologia , Proteína HMGB1/imunologia , Hiperóxia/imunologia , Hiperóxia/patologia , Imunidade Inata/imunologia , Leucócitos/imunologia , Leucócitos/metabolismo , Leucócitos/patologia , Pulmão/imunologia , Pulmão/metabolismo , Pulmão/patologia , Lesão Pulmonar/imunologia , Lesão Pulmonar/patologia , Macrófagos Alveolares/metabolismo , Macrófagos Alveolares/microbiologia , Macrófagos Alveolares/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neutrófilos/imunologia , Neutrófilos/metabolismo , Neutrófilos/patologia , Fagocitose/imunologia , Fagocitose/fisiologia , Pneumonia Bacteriana/imunologia , Pneumonia Bacteriana/microbiologia , Pneumonia Bacteriana/patologia , Pneumonia Associada à Ventilação Mecânica/imunologia , Pneumonia Associada à Ventilação Mecânica/metabolismo , Pneumonia Associada à Ventilação Mecânica/microbiologia , Pneumonia Associada à Ventilação Mecânica/patologia , Infecções por Pseudomonas/imunologia , Infecções por Pseudomonas/microbiologia , Infecções por Pseudomonas/patologia , Pseudomonas aeruginosa/imunologia , Respiração Artificial/efeitos adversos
15.
Mol Med ; 18: 477-85, 2012 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-22314397

RESUMO

Pulmonary infection with Pseudomonas aeruginosa and neutrophilic lung inflammation significantly contribute to morbidity and mortality in cystic fibrosis (CF). High-mobility group box 1 protein (HMGB1), a ubiquitous DNA binding protein that promotes inflammatory tissue injury, is significantly elevated in CF sputum. However, its mechanistic and potential therapeutic implications in CF were previously unknown. We found that HMGB1 levels were significantly elevated in bronchoalveolar lavage fluids (BALs) of CF patients and cystic fibrosis transmembrane conductance regulator (CFTR )(-/-) mice. Neutralizing anti-HMGB1 monoclonal antibody (mAb) conferred significant protection against P. aeruginosa-induced neutrophil recruitment, lung injury and bacterial infection in both CFTR(-/-) and wild-type mice. Alveolar macrophages isolated from mice treated with anti-HMGB1 mAb had improved phagocytic activity, which was suppressed by direct exposure to HMGB1. In addition, BAL from CF patients significantly impaired macrophage phagocytotic function, and this impairment was attenuated by HMGB1-neutralizing antibodies. The HMGB1-mediated suppression of bacterial phagocytosis was attenuated in macrophages lacking toll-like receptor (TLR)-4, suggesting a critical role for TLR4 in signaling HMGB1-mediated macrophage dysfunction. These studies demonstrate that the elevated levels of HMGB1 in CF airways are critical for neutrophil recruitment and persistent presence of P. aeruginosa in the lung. Thus, HMGB1 may provide a therapeutic target for reducing bacterial infection and lung inflammation in CF.


Assuntos
Fibrose Cística/imunologia , Proteína HMGB1/imunologia , Pneumonia Bacteriana/imunologia , Infecções por Pseudomonas/imunologia , Pseudomonas aeruginosa , Animais , Anticorpos Monoclonais/farmacologia , Anticorpos Monoclonais/uso terapêutico , Líquido da Lavagem Broncoalveolar/imunologia , Linhagem Celular , Fibrose Cística/tratamento farmacológico , Feminino , Humanos , Macrófagos/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos CFTR , Camundongos Knockout , Neutrófilos/imunologia , Fagocitose/imunologia , Pneumonia Bacteriana/tratamento farmacológico , Infecções por Pseudomonas/tratamento farmacológico , Receptor 2 Toll-Like/deficiência , Receptor 2 Toll-Like/genética , Receptor 4 Toll-Like/deficiência , Receptor 4 Toll-Like/genética
16.
J Immunotoxicol ; 8(1): 3-9, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21261440

RESUMO

Mechanical ventilation with hyperoxia is a necessary treatment for patients with respiratory distress. However, patients on mechanical ventilation have increased susceptibility to infection. Studies including ours have shown that reactive oxygen species (ROS), generated by exposure to prolonged hyperoxia, can cause a decrease in the phagocytic activity of alveolar macrophages. Hydrogen peroxide (H2O2) is a form of ROS generated under hyperoxic conditions. In this study, we examined whether treatment with H2O2 directly affects macrophage phagocytic ability in RAW 264.7 cells that were exposed to either 21% O2 (room air) or 95% O2 (hyperoxia). Moderate concentrations (ranging from 10 to 250 µM) of H2O2 significantly enhanced macrophage phagocytic activity and restored hyperoxia-suppressed phagocytosis through attenuation of hyperoxia-induced disorganization of actin cytoskeleton and actin oxidation. These results indicate that H2O2 at low-moderate concentrations can be beneficial to host immune responses by improving macrophage phagocytic activity.


Assuntos
Peróxido de Hidrogênio/farmacologia , Macrófagos Alveolares/efeitos dos fármacos , Oxigênio/farmacologia , Fagocitose/efeitos dos fármacos , Pseudomonas aeruginosa , Actinas/metabolismo , Aerobiose , Animais , Linhagem Celular , Macrófagos Alveolares/microbiologia , Macrófagos Alveolares/fisiologia , Camundongos , Estresse Oxidativo/efeitos dos fármacos , Pseudomonas aeruginosa/crescimento & desenvolvimento
17.
J Immunotoxicol ; 7(4): 239-54, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20586583

RESUMO

Oxygen therapy using mechanical ventilation with hyperoxia is necessary to treat patients with respiratory failure and distress. However, prolonged exposure to hyperoxia leads to the generation of excessive reactive oxygen species (ROS), causing cellular damage and multiple organ dysfunctions. As the lungs are directly exposed, hyperoxia can cause both acute and chronic inflammatory lung injury and compromise innate immunity. ROS may contribute to pulmonary oxygen toxicity by overwhelming redox homeostasis, altering signaling cascades that affect cell fate, ultimately leading to hyperoxia-induced acute lung injury (HALI). HALI is characterized by pronounced inflammatory responses with leukocyte infiltration, injury, and death of pulmonary cells, including epithelia, endothelia, and macrophages. Under hyperoxic conditions, ROS mediate both direct and indirect modulation of signaling molecules such as protein kinases, transcription factors, receptors, and pro- and anti-apoptotic factors. The focus of this review is to elaborate on hyperoxia-activated key sensing molecules and current understanding of their signaling mechanisms in HALI. A better understanding of the signaling pathways leading to HALI may provide valuable insights on its pathogenesis and may help in designing more effective therapeutic approaches.


Assuntos
Oxigenação Hiperbárica/efeitos adversos , Hiperóxia/etiologia , Hiperóxia/imunologia , Insuficiência Respiratória/terapia , Transdução de Sinais , Lesão Pulmonar Aguda , Animais , Apoptose , Humanos , Hiperóxia/fisiopatologia , Imunidade Inata , Estresse Oxidativo , Espécies Reativas de Oxigênio/toxicidade , Respiração Artificial , Insuficiência Respiratória/complicações , Insuficiência Respiratória/fisiopatologia
18.
Free Radic Biol Med ; 42(7): 897-908, 2007 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-17349918

RESUMO

Mechanical ventilation with hyperoxia is necessary to treat critically ill patients. However, prolonged exposure to hyperoxia leads to the generation of excessive reactive oxygen species (ROS), which can cause acute inflammatory lung injury. One of the major effects of hyperoxia is the injury and death of pulmonary epithelium, which is accompanied by increased levels of pulmonary proinflammatory cytokines and excessive leukocyte infiltration. A thorough understanding of the signaling pathways leading to pulmonary epithelial cell injury/death may provide some insights into the pathogenesis of hyperoxia-induced acute inflammatory lung injury. This review focuses on epithelial responses to hyperoxia and some of the major factors regulating pathways to epithelial cell injury/death, and proinflammatory responses on exposure to hyperoxia. We discuss in detail some of the most interesting players, such as NF-kappaB, that can modulate both proinflammatory responses and cell injury/death of lung epithelial cells. A better appreciation for the functions of these factors will no doubt help us to delineate the pathways to hyperoxic cell death and proinflammatory responses.


Assuntos
Hiperóxia/metabolismo , Pulmão/metabolismo , Transdução de Sinais , Animais , Morte Celular , Citocinas/metabolismo , Células Epiteliais/metabolismo , Expressão Gênica , Humanos , Pulmão/citologia , Espécies Reativas de Oxigênio/metabolismo , Fatores de Transcrição/metabolismo
19.
Free Radic Biol Med ; 42(9): 1338-49, 2007 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-17395007

RESUMO

Pseudomonas. aeruginosa (PA) is a leading cause of nosocomial pneumonia in patients receiving mechanical ventilation with hyperoxia. Exposure to supraphysiological concentrations of reactive oxygen species during hyperoxia may result in macrophage damage that reduces their ability to phagocytose PA. We tested this hypothesis in cultured macrophage-like RAW 264.7 cells and alveolar macrophages from mice exposed to hyperoxia. Exposure to hyperoxia induced a similarly impaired phagocytosis of both the mucoid and the nonmucoid forms of PA in alveolar macrophages and RAW cells. Compromised PA phagocytosis was associated with cytoskeleton disorganization and actin oxidation in hyperoxic macrophages. To test whether moderate concentrations of O(2) limit the loss of phagocytic function induced by > or =95% O(2), mice and RAW cells were exposed to 65% O(2). Interestingly, although the resulting lung injury/cell proliferation was not significant, exposure to 65% O(2) resulted in a marked reduction in PA phagocytosis that was comparable to that of > or =95% O(2). Treatment with antioxidants, even post hyperoxic exposure, preserved actin cytoskeleton organization and phagocytosis of PA. These data suggest that hyperoxia reduces macrophage phagocytosis through effects on actin functions which can be preserved by antioxidant treatment. In addition, administration of moderate rather than higher concentrations of O2 does not improve macrophage phagocytosis of PA.


Assuntos
Antioxidantes/farmacologia , Hiperóxia/fisiopatologia , Macrófagos Alveolares/fisiologia , Macrófagos/fisiologia , Fagocitose/efeitos dos fármacos , Pseudomonas aeruginosa/fisiologia , Animais , Linhagem Celular , Macrófagos/efeitos dos fármacos , Macrófagos Alveolares/efeitos dos fármacos , Camundongos , Pseudomonas aeruginosa/efeitos dos fármacos , Superóxido Dismutase/farmacologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA