RESUMO
Background: The mechanisms by which moderate tidal volume ventilation (MTV) exacerbates preexisting lung injury are unclear. We hypothesized that systemic endotoxemia via the gut-lung axis would lead to non-canonical and canonical inflammasome activation and pyroptosis in a two-hit model involving polyinosinic-polycytidylic acid (Poly(I:C)), a synthetic analog of dsRNA and MTV and that this would associate with acute lung injury (ALI). Methods: Anesthetized mice were administered Poly(I:C) intratracheally and then 6 h later, they were mechanically ventilated for 4 h with otherwise non-injurious MTV (10ml/kg). Changes in intestinal and alveolar capillary permeability were measured. Further documentation of ALI was assessed by evans blue albumin permeability, protein and IL-1 family concentration in bronchoalveolar lavage fluid (BALF) or plasma, and histopathology in cohorts of wildtype (WT), whole body genetically ablated caspase-11 (caspase-11-/-), caspase-1/caspase-11 double knockout (caspase-1/11-/-), gasdermin D (GSDMD)-/-, nucleotide-binding domain leucine-rich repeat-containing protein 3 (NLRP3)-/- and advanced glycosylation end product-specific receptor (RAGE) -/- mice. Results: Non-injurious MTV exacerbated the mild lung injury associated with Poly(I:C) administration. This included the disruption of alveolar-capillary barrier and increased levels of interleukin (IL)-6, high mobility group proteins 1 (HMGB-1), IL-1ß in BALF and IL-18 in plasma. Combined (Poly(I:C)-MTV) injury was associated with increase in gastrointestinal permeability and endotoxin in plasma and BALF. Poly(I:C)-MTV injury was sensitive to caspase-11 deletion with no further contribution of caspase-1 except for maturation and release of IL-18 (that itself was sensitive to deletion of NLRP3). Combined injury led to large increases in caspase-1 and caspase-11. Genetic ablation of GSDMD attenuated alveolar-capillary disruption and release of cytokines in combined injury model. Conclusions: The previously noted exacerbation of mild Poly(I:C)-induced ALI by otherwise non-injurious MTV is associated with an increase in gut permeability resulting in systemic endotoxemia. The gut-lung axis resulted in activation of pulmonary non-canonical (cytosolic mediated caspase-11 activation) and canonical (caspase-1) inflammasome (NLRP3) mediated ALI in this two-hit model resulting in GSDMD sensitive alveolar capillary barrier disruption, pyroptosis (alveolar macrophages) and cytokine maturation and release (IL-1ß; IL-18). Pharmacologic strategies aimed at disrupting communication between gut and lung, inhibition of inflammasomes or GSDMD in pyroptosis may be useful in ALI.
Assuntos
Lesão Pulmonar Aguda/induzido quimicamente , Caspases Iniciadoras/metabolismo , Microbioma Gastrointestinal , Intestinos/microbiologia , Pulmão/enzimologia , Poli I-C , Respiração Artificial , Lesão Pulmonar Induzida por Ventilação Mecânica/etiologia , Lesão Pulmonar Aguda/enzimologia , Lesão Pulmonar Aguda/microbiologia , Lesão Pulmonar Aguda/patologia , Animais , Bactérias/metabolismo , Caspases Iniciadoras/genética , Modelos Animais de Doenças , Peptídeos e Proteínas de Sinalização Intracelular/genética , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Lipopolissacarídeos/metabolismo , Pulmão/patologia , Macrófagos Alveolares/enzimologia , Macrófagos Alveolares/patologia , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteína 3 que Contém Domínio de Pirina da Família NLR/genética , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Proteínas de Ligação a Fosfato/genética , Proteínas de Ligação a Fosfato/metabolismo , Piroptose , Receptor para Produtos Finais de Glicação Avançada/genética , Receptor para Produtos Finais de Glicação Avançada/metabolismo , Transdução de Sinais , Lesão Pulmonar Induzida por Ventilação Mecânica/enzimologia , Lesão Pulmonar Induzida por Ventilação Mecânica/microbiologia , Lesão Pulmonar Induzida por Ventilação Mecânica/patologiaRESUMO
BACKGROUND: Patients in intensive care units (ICUs) often received broad-spectrum antibiotic treatment and Acinetobacter baumannii (A.b.) and Pseudomonas aeruginosa (P.a.) were the most common pathogens causing ventilator-associated pneumonia (VAP). This study aimed to examine the effects and mechanism of mechanical ventilation (MV) on A.b.-induced lung injury and the involvement of alveolar macrophages (AMs). METHODS: C57BL/6 wild-type (WT) and c-Jun N-terminal kinase knockout (JNK1-/-) mice received MV for 3 h at 2 days after nasal instillation of A.b., P.a. (1 × 106 colony-forming unit, CFU), or normal saline. RESULTS: Intranasal instillation of 106 CFU A.b. in C57BL/6 mice induced a significant increase in total cells and protein levels in the bronchoalveolar lavage fluid (BALF) and neutrophil infiltration in the lungs. MV after A.b. instillation increases neutrophil infiltration, interleukin (IL)-6 and vascular cell adhesion molecule (VCAM) mRNA expression in the lungs and total cells, IL-6 levels, and nitrite levels in the BALF. The killing activity of AMs against A.b. was lower than against P.a. The diminished killing activity was parallel with decreased tumor necrosis factor-α production by AMs compared with A.b. Inducible nitric oxide synthase inhibitor, S-methylisothiourea, decreased the total cell number in BALF on mice receiving A.b. instillation and ventilation. Moreover, MV decreased the A.b. and P.a. killing activity of AMs. MV after A.b. instillation induced less total cells in the BALF and nitrite production in the serum of JNK1-/- mice than those of WT mice. CONCLUSION: A.b. is potent in inducing neutrophil infiltration in the lungs and total protein in the BALF. MV enhances A.b.-induced lung injury through an increase in the expression of VCAM and IL-6 levels in the BALF and a decrease in the bacteria-killing activity of AMs. A lower inflammation level in JNK1-/- mice indicates that A.b.-induced VAP causes lung injury through JNK signaling pathway in the lungs.
Assuntos
Infecções por Acinetobacter/enzimologia , Acinetobacter baumannii/patogenicidade , Pulmão/enzimologia , Proteína Quinase 8 Ativada por Mitógeno/metabolismo , Pneumonia Associada à Ventilação Mecânica/enzimologia , Respiração Artificial/efeitos adversos , Lesão Pulmonar Induzida por Ventilação Mecânica/enzimologia , Infecções por Acinetobacter/microbiologia , Infecções por Acinetobacter/patologia , Animais , Células Cultivadas , Modelos Animais de Doenças , Interleucina-6/genética , Interleucina-6/metabolismo , Pulmão/microbiologia , Pulmão/patologia , Macrófagos Alveolares/enzimologia , Macrófagos Alveolares/microbiologia , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteína Quinase 8 Ativada por Mitógeno/genética , Infiltração de Neutrófilos , Óxido Nítrico Sintase Tipo II/metabolismo , Pneumonia Associada à Ventilação Mecânica/microbiologia , Pneumonia Associada à Ventilação Mecânica/patologia , Transdução de Sinais , Fator de Necrose Tumoral alfa/metabolismo , Molécula 1 de Adesão de Célula Vascular/genética , Molécula 1 de Adesão de Célula Vascular/metabolismo , Lesão Pulmonar Induzida por Ventilação Mecânica/microbiologia , Lesão Pulmonar Induzida por Ventilação Mecânica/patologiaRESUMO
Ventilatorinduced lung injury (VILI) is a lifethreatening condition caused by the inappropriate use of mechanical ventilation (MV). However, the precise molecular mechanism inducing the development of VILI remains to be elucidated. In the present study, it was revealed that the calcineurin/NFATc4 signaling pathway mediates the expression of adhesion molecules and proinflammatory cytokines essential for the development of VILI. The present results revealed that a high tidal volume ventilation (HV) caused lung inflammation and edema in the alveolar walls and the infiltration of inflammatory cells. The calcineurin activity and protein expression in the lungs were increased in animals with VILI, and NFATc4 translocated into the nucleus following calcineurin activation. Furthermore, the translocation of NFATc4 and lung injury were prevented by a calcineurin inhibitor (CsA). Thus, the present results highlighted the critical role of the calcineurin/NFATc4 signaling pathway in VILI and suggest that this pathway coincides with the release of ICAM1, VCAM1, TNFα and IL1ß.
Assuntos
Calcineurina/metabolismo , Fatores de Transcrição NFATC/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Lesão Pulmonar Induzida por Ventilação Mecânica/metabolismo , Animais , Calcineurina/genética , Inibidores de Calcineurina/farmacologia , Núcleo Celular/metabolismo , Edema/complicações , Edema/metabolismo , Inflamação/complicações , Inflamação/metabolismo , Molécula 1 de Adesão Intercelular/genética , Molécula 1 de Adesão Intercelular/metabolismo , Interleucina-1beta/genética , Interleucina-1beta/metabolismo , Masculino , Fatores de Transcrição NFATC/antagonistas & inibidores , Fatores de Transcrição NFATC/genética , Proteínas do Tecido Nervoso/antagonistas & inibidores , Proteínas do Tecido Nervoso/genética , Peroxidase/metabolismo , Ratos , Ratos Wistar , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/metabolismo , Molécula 1 de Adesão de Célula Vascular/genética , Molécula 1 de Adesão de Célula Vascular/metabolismo , Lesão Pulmonar Induzida por Ventilação Mecânica/enzimologia , Lesão Pulmonar Induzida por Ventilação Mecânica/genética , Lesão Pulmonar Induzida por Ventilação Mecânica/patologiaRESUMO
Profound lung vascular permeability is a cardinal feature of acute respiratory distress syndrome (ARDS) and ventilator-induced lung injury (VILI), two syndromes known to centrally involve the nonmuscle isoform of myosin light chain kinase (nmMLCK) in vascular barrier dysregulation. Two main splice variants, nmMLCK1 and nmMLCK2, are well represented in human lung endothelial cells and encoded by MYLK, and they differ only in the presence of exon 11 in nmMLCK1, which contains critical phosphorylation sites (Y464 and Y471) that influence nmMLCK enzymatic activity, cellular translocation, and localization in response to vascular agonists. We recently demonstrated the functional role of SNPs in altering MYLK splicing, and in the present study we sought to identify the role of splicing factors in the generation of nmMLCK1 and nmMLCK2 spliced variants. Using bioinformatic in silico approaches, we identified a putative binding site for heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1), a recognized splicing factor. We verified hnRNPA1 binding to MYLK by gel shift analyses and that hnRNPA1 gene and protein expression is upregulated in mouse lungs obtained from preclinical models of ARDS and VILI and in human endothelial cells exposed to 18% cyclic stretch, a model that reproduces the excessive mechanical stress observed in VILI. Using an MYLK minigene approach, we established a direct role of hnRNPA1 in MYLK splicing and in the context of 18% cyclic stretch. In summary, these data indicate an important regulatory role for hnRNPA1 in MYLK splicing, and they increase understanding of MYLK splicing in the regulation of lung vascular integrity during acute lung inflammation and excessive mechanical stress, such as that observed in ARDS and VILI.
Assuntos
Processamento Alternativo , Proteínas de Ligação ao Cálcio/metabolismo , Células Endoteliais/enzimologia , Ribonucleoproteína Nuclear Heterogênea A1/metabolismo , Pulmão/irrigação sanguínea , Quinase de Cadeia Leve de Miosina/metabolismo , Síndrome do Desconforto Respiratório/enzimologia , Lesão Pulmonar Induzida por Ventilação Mecânica/enzimologia , Animais , Sítios de Ligação , Proteínas de Ligação ao Cálcio/genética , Permeabilidade Capilar , Modelos Animais de Doenças , Impedância Elétrica , Éxons , Células HEK293 , Ribonucleoproteína Nuclear Heterogênea A1/genética , Humanos , Íntrons , Mecanotransdução Celular , Camundongos , Quinase de Cadeia Leve de Miosina/genética , Ligação Proteica , Receptores Pulmonares de Alongamento/metabolismo , Síndrome do Desconforto Respiratório/genética , Síndrome do Desconforto Respiratório/fisiopatologia , Lesão Pulmonar Induzida por Ventilação Mecânica/genética , Lesão Pulmonar Induzida por Ventilação Mecânica/fisiopatologiaRESUMO
The erythropoietin-producing hepatoma (Eph) receptor tyrosine kinase A2 (EphA2) and its ligand, ephrinA1, play a pivotal role in inflammation and tissue injury by modulating the epithelial and endothelial barrier integrity. Therefore, EphA2 receptor may be a potential therapeutic target for modulating ventilator-induced lung injury (VILI). To support this hypothesis, here, we analyzed EphA2/ephrinA1 signaling in the process of VILI and determined the role of EphA2/ephrinA1 signaling in the protective mechanism of prone positioning in a VILI model. Wild-type mice were ventilated with high (24 ml/kg; positive end-expiratory pressure, 0 cm; 5 h) tidal volume in a supine or prone position. Anti-EphA2 receptor antibody or IgG was administered to the supine position group. Injury was assessed by analyzing the BAL fluid, lung injury scoring, and transmission electron microscopy. Lung lysates were evaluated using cytokine/chemokine ELISA and Western blotting of EphA2, ephrinA1, PI3Kγ, Akt, NF-κB, and P70S6 kinase. EphA2/ephrinA1 expression was higher in the supine high tidal volume group than in the control group, but it did not increase upon prone positioning or anti-EphA2 receptor antibody treatment. EphA2 antagonism reduced the extent of VILI and downregulated the expression of PI3Kγ, Akt, NF-κB, and P70S6 kinase. These findings demonstrate that EphA2/ephrinA1 signaling is involved in the molecular mechanism of VILI and that modulation of EphA2/ehprinA1 signaling by prone position or EphA2 antagonism may be associated with the lung-protective effect. Our data provide evidence for EphA2/ehprinA1 as a promising therapeutic target for modulating VILI.
Assuntos
Pulmão/enzimologia , Decúbito Ventral , Receptor EphA2/metabolismo , Lesão Pulmonar Induzida por Ventilação Mecânica/prevenção & controle , Animais , Anticorpos/farmacologia , Classe Ib de Fosfatidilinositol 3-Quinase/metabolismo , Modelos Animais de Doenças , Efrina-A1/metabolismo , Pulmão/efeitos dos fármacos , Pulmão/ultraestrutura , Masculino , Camundongos Endogâmicos C57BL , NF-kappa B/metabolismo , Inibidores de Proteínas Quinases/farmacologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , Receptor EphA2/antagonistas & inibidores , Proteínas Quinases S6 Ribossômicas 70-kDa/metabolismo , Transdução de Sinais , Lesão Pulmonar Induzida por Ventilação Mecânica/enzimologia , Lesão Pulmonar Induzida por Ventilação Mecânica/patologiaRESUMO
BACKGROUND: Neutrophils may cause tissue disruption during migration and by releasing cytotoxic molecules. However, the benefits of neutrophil depletion observed in experimental models of lung injury do not correspond with the poor outcome of neutropenic patients. METHODS: To clarify the role of neutrophils during repair, mice with ventilator induced lung injury (VILI) were rendered neutropenic after damage, and followed for 48 hours of spontaneous breathing. Lungs were harvested and inflammatory mediators and matrix metalloproteinases measured. Bronchoalveolar lavage fluid (BALF) from ventilated patients with acute respiratory distress syndrome, with or without neutropenia, was collected, the same mediators measured and their effects in an ex vivo model of alveolar repair studied. Finally, neutropenic mice were treated after VILI with exogenous matrix metalloproteinase-9 (MMP-9). RESULTS: Lungs from neutropenic animals showed delayed repair and displayed higher levels of tumour necrosis factor α, interferon γ and macrophage inflammatory protein 2, and absence of MMP-9. BALF from ventilated neutropenic patients with acute respiratory distress syndrome showed similar results. BALFs from neutropenic patients yielded a delayed closure rate of epithelial wounds ex vivo, which was improved by removal of collagen or addition of exogenous MMP-9. Lastly, treatment of neutropenic mice with exogenous MMP-9 after VILI reduced tissue damage without modifying cytokine concentrations. CONCLUSION: Release of MMP-9 from neutrophils is required for adequate matrix processing and lung repair.
Assuntos
Metaloproteinase 9 da Matriz/biossíntese , Neutropenia/metabolismo , Neutrófilos/metabolismo , Síndrome do Desconforto Respiratório/metabolismo , Lesão Pulmonar Induzida por Ventilação Mecânica/metabolismo , Animais , Biomarcadores/sangue , Líquido da Lavagem Broncoalveolar/citologia , Quimiocina CXCL2/metabolismo , Modelos Animais de Doenças , Humanos , Interferon gama/metabolismo , Camundongos , Neutropenia/patologia , Síndrome do Desconforto Respiratório/enzimologia , Síndrome do Desconforto Respiratório/patologia , Fator de Necrose Tumoral alfa/metabolismo , Lesão Pulmonar Induzida por Ventilação Mecânica/enzimologia , Lesão Pulmonar Induzida por Ventilação Mecânica/patologia , Lesão Pulmonar Induzida por Ventilação Mecânica/prevenção & controleRESUMO
Although it is essential in critical care medicine, mechanical ventilation often results in ventilatorinduced lung injury (VILI). Treating mice with lipopolysaccharide has been reported to upregulate the expression of miR127, which has been implicated in the modulation of immune responses. However, the putative roles of miR127 during the development of VILI have yet to be elucidated. The present study demonstrated that challenging mice with mechanical ventilation for 6 h significantly upregulated the expression of miR127 in bronchoalveolar lavage fluid, serum and lung tissue samples. Conversely, following the downregulation of miR127 expression in vivo using an adenovirus delivery system, VILIassociated pathologies, including alterations in the pulmonary wet/dry ratio, pulmonary permeability, lung neutrophil infiltration and levels of proinflammatory cytokines, were significantly attenuated. In addition, miR127 knockdown inhibited the ventilationinduced activation of nuclear factor (NF)κB and p38 mitogenactivated protein kinase (MAPK). These findings suggested that the upregulation of miR127 expression may contribute to the development of VILI, through the modulation of pulmonary permeability, the induction of histopathological alterations, and the potentiation of inflammatory responses involving NFκB and p38 MAPKassociated signaling pathways.
Assuntos
MicroRNAs/genética , Lesão Pulmonar Induzida por Ventilação Mecânica/genética , Animais , Feminino , Inativação Gênica , Inflamação/genética , Inflamação/patologia , Camundongos Endogâmicos C57BL , MicroRNAs/metabolismo , Proteínas Quinases/metabolismo , Alvéolos Pulmonares/patologia , Transdução de Sinais , Regulação para Cima/genética , Lesão Pulmonar Induzida por Ventilação Mecânica/enzimologia , Lesão Pulmonar Induzida por Ventilação Mecânica/patologiaRESUMO
BACKGROUND: Mechanical ventilation and concomitant administration of hyperoxia in patients with acute respiratory distress syndrome can damage the alveolar epithelial and capillary endothelial barrier by producing inflammatory cytokines and reactive oxygen species. The Src tyrosine kinase and Smad3 are crucial inflammatory regulators used for ventilator-induced lung injury (VILI). The mechanisms regulating interactions between high-tidal-volume mechanical ventilation, hyperoxia, and acute lung injury (ALI) are unclear. We hypothesized that high-tidal-volume mechanical stretches and hyperoxia augment lung inflammation through upregulation of the Src and Smad3 pathways. METHODS: Wild-type or Src-deficient C57BL/6 mice, aged between 6 and 8 weeks, were exposed to high-tidal-volume (30 mL/kg) ventilation with room air or hyperoxia for 1-4 h after 2-mg/kg Smad3 inhibitor (SIS3) administration. Nonventilated mice were used as control subjects. RESULTS: We observed that the addition of hyperoxia to high-tidal-volume mechanical ventilation further induced microvascular permeability, neutrophil infiltration, macrophage inflammatory protein-2 and matrix metalloproteinase-9 (MMP-9) production, malondialdehyde, nicotinamide adenine dinucleotide phosphate oxidase activity, MMP-9 mRNA expression, hypoxemia, and Src and Smad3 activation (P < 0.05). Hyperoxia-induced augmentation of VILI was attenuated in Src-deficient mice and mice with pharmacological inhibition of Smad3 activity by SIS3 (P < 0.05). Mechanical ventilation of Src-deficient mice with hyperoxia further reduced the activation of Smad3. CONCLUSIONS: Our data suggest that hyperoxia-increased high-tidal-volume ventilation-induced ALI partially depends on the Src and Smad3 pathways.
Assuntos
Hiperóxia/complicações , Pulmão/enzimologia , Neutrófilos/enzimologia , Estresse Oxidativo , Pneumonia/etiologia , Respiração Artificial/efeitos adversos , Transdução de Sinais , Proteína Smad3/metabolismo , Lesão Pulmonar Induzida por Ventilação Mecânica/etiologia , Quinases da Família src/metabolismo , Animais , Permeabilidade Capilar , Quimiocina CXCL2/metabolismo , Modelos Animais de Doenças , Predisposição Genética para Doença , Isoquinolinas/farmacologia , Pulmão/irrigação sanguínea , Pulmão/efeitos dos fármacos , Pulmão/imunologia , Pulmão/patologia , Metaloproteinase 9 da Matriz/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , NADPH Oxidases/metabolismo , Infiltração de Neutrófilos , Neutrófilos/efeitos dos fármacos , Neutrófilos/imunologia , Estresse Oxidativo/efeitos dos fármacos , Fenótipo , Pneumonia/enzimologia , Pneumonia/genética , Pneumonia/imunologia , Pneumonia/patologia , Pneumonia/prevenção & controle , Piridinas/farmacologia , Pirróis/farmacologia , Transdução de Sinais/efeitos dos fármacos , Proteína Smad3/antagonistas & inibidores , Volume de Ventilação Pulmonar , Lesão Pulmonar Induzida por Ventilação Mecânica/enzimologia , Lesão Pulmonar Induzida por Ventilação Mecânica/genética , Lesão Pulmonar Induzida por Ventilação Mecânica/imunologia , Lesão Pulmonar Induzida por Ventilação Mecânica/patologia , Lesão Pulmonar Induzida por Ventilação Mecânica/prevenção & controle , Quinases da Família src/deficiência , Quinases da Família src/genéticaRESUMO
BACKGROUND: Simvastatin reduces ventilator-induced lung injury and is regularly used in clinical practice. This study aimed to test the hypotheses that long-term use of simvastatin could affect the incidence and severity of ventilator-induced lung injury after mechanical ventilation, and the process may involve heme oxygenase-1 (HO-1). MATERIALS AND METHODS: Forty healthy adult Sprague-Dawley rats were randomly divided into four groups, namely control, ventilation, simvastatin, and simvastatin + ventilation groups. Saline (control and ventilation groups) or 10 mg kg(-1) d(-1) simvastatin (simvastatin and simvastatin + ventilation groups) was administered by gavage to the animals for 4 wk. Mechanical ventilation (tidal volume 50 mL/kg) was then applied for 4 h to the ventilation and simvastatin + ventilation groups. Lung tissues were harvested for hematoxylin-eosin staining and pathologic examination, and HO-1 contents were measured by immunoblotting and polymerase chain reaction. RESULTS: A severe pathologic damage was observed in rats that underwent mechanical ventilation. Interestingly, protein concentration, wet/dry weight ratio, myeloperoxidase activity, and malondialdehyde level were increased, and superoxide dismutase activity decreased, in lung tissues after mechanical ventilation. The pathologic damage was substantially alleviated in rats treated with simvastatin before mechanical ventilation: reduced protein concentration, wet/dry weight ratio, myeloperoxidase activity, and malondialdehyde level, and increased superoxide dismutase activity in lung tissues, compared with the ventilation group. Both mechanical ventilation and simvastatin administration induced HO-1 messenger RNA and protein expression in lung tissues. CONCLUSIONS: Long-term administration of simvastatin significantly reduces the inflammatory response and pulmonary injury induced by mechanical ventilation, potentially by upregulating HO-1 in lung tissues.
Assuntos
Heme Oxigenase (Desciclizante)/metabolismo , Inibidores de Hidroximetilglutaril-CoA Redutases/administração & dosagem , Respiração Artificial/efeitos adversos , Sinvastatina/administração & dosagem , Lesão Pulmonar Induzida por Ventilação Mecânica/prevenção & controle , Animais , Modelos Animais de Doenças , Pulmão/enzimologia , Pulmão/patologia , Malondialdeído/metabolismo , Peroxidase/metabolismo , Distribuição Aleatória , Ratos Sprague-Dawley , Superóxido Dismutase/metabolismo , Regulação para Cima/efeitos dos fármacos , Lesão Pulmonar Induzida por Ventilação Mecânica/enzimologia , Lesão Pulmonar Induzida por Ventilação Mecânica/patologiaRESUMO
BACKGROUND: Mortality from severe acute respiratory distress syndrome exceeds 40% and there is no available pharmacologic treatment. Mechanical ventilation contributes to lung dysfunction and mortality by causing ventilator-induced lung injury. We explored the utility of simvastatin in a mouse model of severe ventilator-induced lung injury. METHODS: Male C57BL6 mice (n = 7/group) were pretreated with simvastatin or saline and received protective (8 mL/kg) or injurious (25 mL/kg) ventilation for four hours. Three doses of simvastatin (20 mg/kg) or saline were injected intraperitoneally on days -2, -1 and 0 of the experiment. Lung mechanics, (respiratory system elastance, tissue damping and airway resistance), were evaluated by forced oscillation technique, while respiratory system compliance was measured with quasi-static pressure-volume curves. A pathologist blinded to treatment allocation scored hematoxylin-eosin-stained lung sections for the presence of lung injury. Pulmonary endothelial dysfunction was ascertained by bronchoalveolar lavage protein content and lung tissue expression of endothelial junctional protein Vascular Endothelial cadherin by immunoblotting. To assess the inflammatory response in the lung, we determined bronchoalveolar lavage fluid total cell content and neutrophil fraction by microscopy and staining in addition to Matrix-Metalloprotease-9 by ELISA. For the systemic response, we obtained plasma levels of Tumor Necrosis Factor-α, Interleukin-6 and Matrix-Metalloprotease-9 by ELISA. Statistical hypothesis testing was undertaken using one-way analysis of variance and Tukey's post hoc tests. RESULTS: Ventilation with high tidal volume (HVt) resulted in significantly increased lung elastance by 3-fold and decreased lung compliance by 45% compared to low tidal volume (LVt) but simvastatin abrogated lung mechanical alterations of HVt. Histologic lung injury score increased four-fold by HVt but not in simvastatin-pretreated mice. Lavage pleocytosis and neutrophilia were induced by HVt but were significantly attenuated by simvastatin. Microvascular protein permeability increase 20-fold by injurious ventilation but only 4-fold with simvastatin. There was a 3-fold increase in plasma Tumor Necrosis Factor-α, a 7-fold increase in plasma Interleukin-6 and a 20-fold increase in lavage fluid Matrix-Metalloprotease-9 by HVt but simvastatin reduced these levels to control. Lung tissue vascular endothelial cadherin expression was significantly reduced by injurious ventilation but remained preserved by simvastatin. CONCLUSION: High-dose simvastatin prevents experimental hyperinflation lung injury by angioprotective and anti-inflammatory effects.
Assuntos
Anti-Inflamatórios/farmacologia , Inibidores de Hidroximetilglutaril-CoA Redutases/farmacologia , Pulmão/efeitos dos fármacos , Sinvastatina/farmacologia , Lesão Pulmonar Induzida por Ventilação Mecânica/prevenção & controle , Resistência das Vias Respiratórias/efeitos dos fármacos , Animais , Líquido da Lavagem Broncoalveolar/química , Líquido da Lavagem Broncoalveolar/citologia , Permeabilidade Capilar/efeitos dos fármacos , Modelos Animais de Doenças , Elasticidade , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/metabolismo , Mediadores da Inflamação/sangue , Pulmão/enzimologia , Pulmão/patologia , Pulmão/fisiopatologia , Complacência Pulmonar/efeitos dos fármacos , Masculino , Camundongos Endogâmicos C57BL , Infiltração de Neutrófilos/efeitos dos fármacos , Neutrófilos/efeitos dos fármacos , Neutrófilos/metabolismo , Pneumonia/enzimologia , Pneumonia/patologia , Pneumonia/fisiopatologia , Pneumonia/prevenção & controle , Edema Pulmonar/enzimologia , Edema Pulmonar/patologia , Edema Pulmonar/fisiopatologia , Edema Pulmonar/prevenção & controle , Fatores de Tempo , Lesão Pulmonar Induzida por Ventilação Mecânica/enzimologia , Lesão Pulmonar Induzida por Ventilação Mecânica/patologia , Lesão Pulmonar Induzida por Ventilação Mecânica/fisiopatologiaRESUMO
BACKGROUND: Ventilator-induced lung injury (VILI) is characterized by increased alveolar permeability, pulmonary edema. The tyrosine kinase, c-Src, is involved in VILI but its role has not been fully elucidated. This study examined the relationship between c-Src activation and occludin levels in VILI both in vitro and in vivo. METHODS: For the in vivo study, Wistar rats were randomly divided into five groups: control (group C); normal tidal volume (group M); normal tidal volume + c-Src inhibitor (PP2) (group M + P); high tidal volume (group H); and high tidal volume + c-Src inhibitor (PP2) (group H + P). Rats in all groups but group C underwent mechanical ventilation for 4 h. For the in vitro study, MLE-12 cells pretreated with PP2 and siRNA underwent cyclic stretching at 8% or 20% for 0, 1, 2 and 4 h. The expressions of occludin, c-Src, and p-c-Src were analyzed by western blotting, hematoxylin and eosin (HE) staining, and immunofluorescence. RESULTS: For the in vivo study, rats in group H showed decreased occludin expression and activated c-Src compared with group C. HE staining and lung injury score showed more severe lung injury and alveolar edema in group H compared with group M and group C. Group H + P had less pulmonary edema induced by the high tidal volume ventilation. For the in vitro study, occludin expression decreased and c-Src activation increased as indicated by the phosphorylation of c-Src over time. Consistently, PP2 could restore occludin levels. CONCLUSIONS: Mechanical ventilation can activate c-Src by phosphorylation and increase the degradation of occludin. c-Src inhibitor can ameliorate barrier function and lung injury by up-regulating occludin.
Assuntos
Pulmão/enzimologia , Ocludina/metabolismo , Lesão Pulmonar Induzida por Ventilação Mecânica/enzimologia , Quinases da Família src/metabolismo , Animais , Proteína Tirosina Quinase CSK , Linhagem Celular , Modelos Animais de Doenças , Ativação Enzimática , Pulmão/efeitos dos fármacos , Pulmão/fisiopatologia , Mecanotransdução Celular , Camundongos , Fosforilação , Inibidores de Proteínas Quinases/farmacologia , Proteólise , Edema Pulmonar/enzimologia , Interferência de RNA , Ratos Wistar , Fatores de Tempo , Transfecção , Lesão Pulmonar Induzida por Ventilação Mecânica/fisiopatologia , Quinases da Família src/antagonistas & inibidores , Quinases da Família src/genéticaRESUMO
BACKGROUND: Ventilator-induced lung injury-(VILI-) induced endothelial permeability is regulated through the Rho-dependent signaling pathway. Ibuprofen inhibits Rho activation in animal models of spinal-cord injury and Alzheimer's disease. The study aims to investigate ibuprofen effects on high tidal volume associated VILI. METHODS: Twenty-eight adult male Sprague-Dawley rats were randomized to receive a ventilation strategy with three different interventions for 2 h: (1) a high-volume zero-positive end-expiratory pressure (PEEP) (HVZP) group; (2) an HVZP + ibuprofen 15 mg/kg group; and (3) an HVZP + ibuprofen 30 mg/kg group. A fourth group without ventilation served as the control group. Rho-kinase activity was determined by ratio of phosphorylated ezrin, radixin, and moesin (p-ERM), substrates of Rho-kinase, to total ERM. VILI was characterized by increased pulmonary protein leak, wet-to-dry weight ratio, cytokines level, and Rho guanine nucleotide exchange factor (GEF-H1), RhoA activity, p-ERM/total ERM, and p-myosin light chain (MLC) protein expression. RESULTS: Ibuprofen pretreatment significantly reduced the HVZP ventilation-induced increase in pulmonary protein leak, wet-to-dry weight ratio, bronchoalveolar lavage fluid interleukin-6 and RANTES levels, and lung GEF-H1, RhoA activity, p-ERM/total ERM, and p-MLC protein expression. CONCLUSION: Ibuprofen attenuated high tidal volume induced pulmonary endothelial hyperpermeability. This protective effect was associated with a reduced Rho-kinase activity.
Assuntos
Ibuprofeno/administração & dosagem , Pulmão/metabolismo , Lesão Pulmonar Induzida por Ventilação Mecânica/enzimologia , Lesão Pulmonar Induzida por Ventilação Mecânica/prevenção & controle , Quinases Associadas a rho/metabolismo , Animais , Anti-Inflamatórios não Esteroides/administração & dosagem , Regulação para Baixo/efeitos dos fármacos , Ativação Enzimática , Pulmão/efeitos dos fármacos , Masculino , Ratos , Ratos Sprague-Dawley , Resultado do TratamentoRESUMO
This study was performed to examine the role of transglutaminase 2 (TG2) in ventilator-induced lung injury (VILI). C57BL/6 mice were divided into six experimental groups: 1) control group; 2) lipopolysaccharide (LPS) group; 3) lung protective ventilation (LPV) group; 4) VILI group; 5) VILI with cystamine, a TG2 inhibitor, pretreatment (Cyst+VILI) group; and 6) LPV with cystamine pretreatment (Cyst+LPV) group. Acute lung injury (ALI) score, TG2 activity and gene expression, inflammatory cytokines, and nuclear factor-κB (NF-κB) activity were measured. TG2 activity and gene expression were significantly increased in the VILI group (P < 0.05). Cystamine pretreatment significantly decreased TG2 activity and gene expression in the Cyst+VILI group (P < 0.05). Inflammatory cytokines were higher in the VILI group than in the LPS and LPV groups (P < 0.05), and significantly lower in the Cyst+VILI group than the VILI group (P < 0.05). NF-κB activity was increased in the VILI group compared with the LPS and LPV groups (P < 0.05), and significantly decreased in the Cyst+VILI group compared to the VILI group (P = 0.029). The ALI score of the Cyst+VILI group was lower than the VILI group, but the difference was not statistically significant (P = 0.105). These results suggest potential roles of TG2 in the pathogenesis of VILI.
Assuntos
Proteínas de Ligação ao GTP/antagonistas & inibidores , Transglutaminases/antagonistas & inibidores , Lesão Pulmonar Induzida por Ventilação Mecânica/enzimologia , Lesão Pulmonar Aguda/patologia , Animais , Cistamina/uso terapêutico , Citocinas/análise , Inibidores Enzimáticos/uso terapêutico , Ensaio de Imunoadsorção Enzimática , Proteínas de Ligação ao GTP/genética , Proteínas de Ligação ao GTP/metabolismo , Expressão Gênica , Lipopolissacarídeos/toxicidade , Masculino , Camundongos , Camundongos Endogâmicos C57BL , NF-kappa B/metabolismo , Proteína 2 Glutamina gama-Glutamiltransferase , Respiração Artificial , Transglutaminases/genética , Transglutaminases/metabolismo , Lesão Pulmonar Induzida por Ventilação Mecânica/patologia , Lesão Pulmonar Induzida por Ventilação Mecânica/prevenção & controleRESUMO
We previously identified the intracellular nicotinamide phosphoribosyltransferase (iNAMPT, aka pre-B-cell colony enhancing factor) as a candidate gene promoting acute respiratory distress syndrome (ARDS) and ventilator-induced lung injury (VILI) with circulating nicotinamide phosphoribosyltransferase potently inducing NF-κB signaling in lung endothelium. iNAMPT also synthesizes intracellular nicotinamide adenine dinucleotide (iNAD) in response to extracellular oxidative stress, contributing to the inhibition of apoptosis via ill-defined mechanisms. We now further define the role of iNAMPT activity in the pathogenesis of ARDS/VILI using the selective iNAMPT inhibitor FK-866. C57/B6 mice were exposed to VILI (40 ml/kg, 4 h) or LPS (1.5 mg/kg, 18 h) after osmotic pump delivery of FK-866 (100 mg/kg/d, intraperitoneally). Assessment of total bronchoalveolar lavage (BAL) protein, polymorphonuclear neutrophil (PMN) levels, cytokine levels (TNF-α, IL-6, IL-1α), lung iNAD levels, and injury scores revealed that FK-866-mediated iNAMPT inhibition successfully reduced lung tissue iNAD levels, BAL injury indices, inflammatory cell infiltration, and lung injury scores in LPS- and VILI-exposed mice. FK-866 further increased lung PMN apoptosis, as reflected by caspase-3 activation in BAL PMNs. These findings support iNAMPT inhibition via FK-866 as a novel therapeutic agent for ARDS via enhanced apoptosis in inflammatory PMNs.
Assuntos
Acrilamidas/farmacologia , Anti-Inflamatórios/farmacologia , Citocinas/antagonistas & inibidores , Inibidores Enzimáticos/farmacologia , Pulmão/efeitos dos fármacos , Nicotinamida Fosforribosiltransferase/antagonistas & inibidores , Piperidinas/farmacologia , Pneumonia/tratamento farmacológico , Síndrome do Desconforto Respiratório/tratamento farmacológico , Lesão Pulmonar Induzida por Ventilação Mecânica/tratamento farmacológico , Animais , Apoptose/efeitos dos fármacos , Líquido da Lavagem Broncoalveolar/imunologia , Caspase 3/metabolismo , Citocinas/metabolismo , Modelos Animais de Doenças , Mediadores da Inflamação/metabolismo , Pulmão/enzimologia , Pulmão/imunologia , Pulmão/patologia , Camundongos , Camundongos Endogâmicos C57BL , NAD/metabolismo , Neutrófilos/efeitos dos fármacos , Neutrófilos/enzimologia , Neutrófilos/imunologia , Nicotinamida Fosforribosiltransferase/metabolismo , Pneumonia/enzimologia , Pneumonia/imunologia , Pneumonia/patologia , Síndrome do Desconforto Respiratório/enzimologia , Síndrome do Desconforto Respiratório/imunologia , Síndrome do Desconforto Respiratório/patologia , Lesão Pulmonar Induzida por Ventilação Mecânica/enzimologia , Lesão Pulmonar Induzida por Ventilação Mecânica/imunologia , Lesão Pulmonar Induzida por Ventilação Mecânica/patologiaRESUMO
Ventilation at high tidal volume may cause lung inflammation and barrier dysfunction that culminates in ventilator-induced lung injury (VILI). However, the mechanisms by which mechanical stimulation triggers the inflammatory response have not been fully elucidated. This study tested the hypothesis that onset of VILI is triggered by activation of secretory group V phospholipase A(2) (gVPLA2) in pulmonary vascular endothelium exposed to excessive mechanical stretch. High-magnitude cyclic stretch (18% CS) increased expression and surface exposure of gVPLA2 in human pulmonary endothelial cells (EC). CS-induced gVPLA2 activation was required for activation of ICAM-1 expression and polymorphonuclear neutrophil (PMN) adhesion to CS-preconditioned EC. By contrast, physiological CS (5% CS) had no effect on gVPLA2 activation or EC-PMN adhesion. CS-induced ICAM-1 expression and EC-PMN adhesion were attenuated by the gVPLA2-blocking antibody (MCL-3G1), general inhibitor of soluble PLA2, LY311727, or siRNA-induced EC gVPLA2 knockdown. In vivo, ventilator-induced lung leukocyte recruitment, cell and protein accumulation in the alveolar space, and total lung myeloperoxidase activity were strongly suppressed in gVPLA2 mouse knockout model or upon administration of MCL-3G1. These results demonstrate a novel role for gVPLA2 as the downstream effector of pathological mechanical stretch leading to an inflammatory response associated with VILI.
Assuntos
Lesão Pulmonar Aguda/enzimologia , Fosfolipases A2/biossíntese , Pneumonia/enzimologia , Lesão Pulmonar Aguda/metabolismo , Lesão Pulmonar Aguda/patologia , Animais , Células Cultivadas , Células Endoteliais/enzimologia , Células Endoteliais/metabolismo , Células Endoteliais/patologia , Endotélio Vascular/enzimologia , Endotélio Vascular/metabolismo , Endotélio Vascular/patologia , Indução Enzimática , Humanos , Molécula 1 de Adesão Intercelular/metabolismo , Leucócitos/enzimologia , Leucócitos/metabolismo , Leucócitos/patologia , Pulmão/enzimologia , Pulmão/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neutrófilos/enzimologia , Neutrófilos/metabolismo , Neutrófilos/patologia , Pneumonia/metabolismo , Pneumonia/patologia , Estresse Mecânico , Volume de Ventilação Pulmonar/fisiologia , Lesão Pulmonar Induzida por Ventilação Mecânica/enzimologia , Lesão Pulmonar Induzida por Ventilação Mecânica/metabolismo , Lesão Pulmonar Induzida por Ventilação Mecânica/patologiaRESUMO
Mechanical ventilation in patients may increase the risk of an acute lung injury (ALI), termed ventilator-induced lung injury (VILI). Induced pluripotent stem cells (iPSCs) have previously been shown to improve tissue repair in different disease models, including ALI. However, the therapeutic efficacy of iPSCs-derived conditioned medium (iPSC-CM) on ALI or VILI remains unknown. Here, we demonstrated that both iPSCs and iPSC-CM effectively decrease high-tidal-volume-induced VILI-related inflammatory processes and HMGB1 and PAI-1 production, predominantly through suppressing PI3K/Akt signaling. Notably, iPSC-CM suppressed production of macrophage inflammatory protein-2, malondialdehyde, and increased total glutathione content. Transmission electron microscopy revealed that iPSC-CM potentially restored the bronchial microstructure. This iPSC-CM efficacy could be mimicked by PI3K inhibitor LY294002 or Akt heterozygous knockout, and either treatment showed no further improvement on VILI in iPSC-CM recipients. Furthermore, iPSC-CM increased interferon gamma-induced protein 10 (IP-10) production in injured lungs. Administration of IP-10-neutralizing antibodies increased neutrophil infiltration, impaired lung oxygenation and deteriorated the protective effects mediated by iPSC-CM. Our data provide a preclinical indication regarding the therapeutic potential of iPSC-CM in VILI and suggest that inhibiting PI3K/Akt pathway or increasing IP-10 is a prospective diagnostic and therapeutic target for VILI patients.
Assuntos
Quimiocina CXCL9/metabolismo , Meios de Cultivo Condicionados/farmacologia , Células-Tronco Pluripotentes Induzidas/metabolismo , Comunicação Parácrina/efeitos dos fármacos , Inibidores de Fosfoinositídeo-3 Quinase , Proteínas Proto-Oncogênicas c-akt/antagonistas & inibidores , Lesão Pulmonar Induzida por Ventilação Mecânica/terapia , Animais , Heterozigoto , Células-Tronco Pluripotentes Induzidas/efeitos dos fármacos , Inflamação/patologia , Inflamação/fisiopatologia , Pulmão/efeitos dos fármacos , Pulmão/patologia , Pulmão/ultraestrutura , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Infiltração de Neutrófilos/efeitos dos fármacos , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais/efeitos dos fármacos , Transplante de Células-Tronco , Volume de Ventilação Pulmonar/efeitos dos fármacos , Resultado do Tratamento , Lesão Pulmonar Induzida por Ventilação Mecânica/enzimologia , Lesão Pulmonar Induzida por Ventilação Mecânica/patologia , Lesão Pulmonar Induzida por Ventilação Mecânica/fisiopatologiaRESUMO
Mechanical ventilation (MV) has the potential to induce lung damage in healthy lungs or aggravate existing lung injury. Polymorphonuclear neutrophil (PMN) recruitment plays an important role in driving the inflammatory response in ventilator-induced lung injury (VILI). The cyclin-dependent kinase inhibitor r-roscovitine has been shown to induce apoptosis in PMNs. In this study, we investigated the potential of r-roscovitine treatment in reducing lung damage in a mouse model of VILI. Mice were tracheotomized and subjected to lung-protective MV with lower (â¼7.5 mL/kg) or lung-injurious MV with higher (â¼15 mL/kg) tidal volume (VT). R-roscovitine treatment enhanced apoptosis in PMNs in vitro. Ventilator-induced lung injury was associated with pulmonary PMN influx in low and high VT MV. During lung-injurious MV, r-roscovitine treatment reduced the number of PMNs and lowered levels of the lung damage markers RAGE (receptor for advanced glycation end products) and total immunoglobulin M in bronchoalveolar lavage fluid. R-roscovitine did not affect cytokine or chemokine levels in the bronchoalveolar space, neither during lung-protective nor lung-injurious MV. Thus, r-roscovitine treatment reduces lung damage in VILI, possibly dependent on increased apoptosis of PMNs.
Assuntos
Quinases Ciclina-Dependentes/antagonistas & inibidores , Pulmão/enzimologia , Inibidores de Proteínas Quinases/farmacologia , Purinas/farmacologia , Lesão Pulmonar Induzida por Ventilação Mecânica/tratamento farmacológico , Animais , Apoptose/efeitos dos fármacos , Biomarcadores/metabolismo , Células Cultivadas , Quinases Ciclina-Dependentes/metabolismo , Modelos Animais de Doenças , Feminino , Humanos , Pulmão/patologia , Masculino , Camundongos , Neutrófilos/enzimologia , Neutrófilos/patologia , Receptor para Produtos Finais de Glicação Avançada , Receptores Imunológicos/metabolismo , Roscovitina , Lesão Pulmonar Induzida por Ventilação Mecânica/enzimologia , Lesão Pulmonar Induzida por Ventilação Mecânica/patologia , Ventiladores Mecânicos/efeitos adversosRESUMO
Sepsis, a systemic inflammatory response to infection, commonly progresses to acute lung injury (ALI), an inflammatory lung disease with high morbidity. We postulated that sepsis-associated ALI is initiated by degradation of the pulmonary endothelial glycocalyx, leading to neutrophil adherence and inflammation. Using intravital microscopy, we found that endotoxemia in mice rapidly induced pulmonary microvascular glycocalyx degradation via tumor necrosis factor-α (TNF-α)-dependent mechanisms. Glycocalyx degradation involved the specific loss of heparan sulfate and coincided with activation of endothelial heparanase, a TNF-α-responsive, heparan sulfate-specific glucuronidase. Glycocalyx degradation increased the availability of endothelial surface adhesion molecules to circulating microspheres and contributed to neutrophil adhesion. Heparanase inhibition prevented endotoxemia-associated glycocalyx loss and neutrophil adhesion and, accordingly, attenuated sepsis-induced ALI and mortality in mice. These findings are potentially relevant to human disease, as sepsis-associated respiratory failure in humans was associated with higher plasma heparan sulfate degradation activity; moreover, heparanase content was higher in human lung biopsies showing diffuse alveolar damage than in normal human lung tissue.
Assuntos
Lesão Pulmonar Aguda/fisiopatologia , Endotoxemia/complicações , Glicocálix/fisiologia , Pulmão/fisiopatologia , Neutrófilos/fisiologia , Lesão Pulmonar Aguda/etiologia , Lesão Pulmonar Aguda/prevenção & controle , Transferência Adotiva , Animais , Adesão Celular/fisiologia , Modelos Animais de Doenças , Endotélio/enzimologia , Endotélio/fisiologia , Endotoxemia/fisiopatologia , Ativação Enzimática , Regulação da Expressão Gênica/efeitos dos fármacos , Glucuronidase/análise , Glucuronidase/deficiência , Glucuronidase/fisiologia , Heparitina Sulfato/antagonistas & inibidores , Heparitina Sulfato/metabolismo , Humanos , Molécula 1 de Adesão Intercelular/biossíntese , Molécula 1 de Adesão Intercelular/genética , Perfuração Intestinal/complicações , Perfuração Intestinal/microbiologia , Lipopolissacarídeos/toxicidade , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Alvéolos Pulmonares/enzimologia , Alvéolos Pulmonares/patologia , Receptores Tipo I de Fatores de Necrose Tumoral/deficiência , Receptores Tipo I de Fatores de Necrose Tumoral/fisiologia , Insuficiência Respiratória/enzimologia , Insuficiência Respiratória/patologia , Fator de Necrose Tumoral alfa/fisiologia , Lesão Pulmonar Induzida por Ventilação Mecânica/enzimologia , Lesão Pulmonar Induzida por Ventilação Mecânica/patologiaRESUMO
Both hyperoxia and mechanical ventilation can independently cause lung injury. In combination, these insults produce accelerated and severe lung injury. We recently reported that pre-exposure to hyperoxia for 12 hours, followed by ventilation with large tidal volumes, induced significant lung injury and epithelial cell apoptosis compared with either stimulus alone. We also reported that such injury and apoptosis are inhibited by antioxidant treatment. In this study, we hypothesized that apoptosis signal-regulating kinase-1 (ASK-1), a redox-sensitive, mitogen-activated protein kinase kinase kinase, plays a role in lung injury and apoptosis in this model. To determine the role of ASK-1 in lung injury, the release of inflammatory mediators and apoptosis, attributable to 12 hours of hyperoxia, were followed by large tidal volume mechanical ventilation with hyperoxia. Wild-type and ASK-1 knockout mice were subjected to hyperoxia (Fi(O(2)) = 0.9) for 12 hours before 4 hours of large tidal mechanical ventilation (tidal volume = 25 µl/g) with hyperoxia, and were compared with nonventilated control mice. Lung injury, apoptosis, and cytokine release were measured. The deletion of ASK-1 significantly inhibited lung injury and apoptosis, but did not affect the release of inflammatory mediators, compared with the wild-type mice. ASK-1 is an important regulator of lung injury and apoptosis in this model. Further study is needed to determine the mechanism of lung injury and apoptosis by ASK-1 and its downstream mediators in the lung.
Assuntos
MAP Quinase Quinase Quinase 5/genética , MAP Quinase Quinase Quinase 5/metabolismo , Lesão Pulmonar Induzida por Ventilação Mecânica/enzimologia , Lesão Pulmonar Induzida por Ventilação Mecânica/prevenção & controle , Animais , Apoptose/genética , Citocinas/metabolismo , Modelos Animais de Doenças , Ativação Enzimática , Células Epiteliais/patologia , Feminino , Hiperóxia/enzimologia , Mediadores da Inflamação/metabolismo , Masculino , Camundongos , Camundongos Knockout , Alvéolos Pulmonares/patologia , Lesão Pulmonar Induzida por Ventilação Mecânica/patologiaRESUMO
Mechanical ventilation is an indispensable supportive intervention for acute respiratory failure. However, mechanical ventilation can provoke ventilator-induced lung injury, which remains one of the major causes of morbidity and mortality in critically ill patients. Excessive inflammatory response characterized by infiltration of inflammatory cells and overproduction of inflammatory mediators contributes to the pathogenesis of ventilator-induced lung injury. At present, apart from the protective ventilation strategy, no other pharmacological intervention is available to attenuate ventilator-induced lung injury. Heme oxygenase-1 (HO-1) is the inducible isoform of the first and rate-limiting enzyme which degrades heme into carbon monoxide, ferritin and bilirubin. Accumulating evidence suggests that HO-1 system may function as a crucial negative regulator in the modulation of inflammatory process. This anti-inflammatory action of HO-1 is mediated essentially by the regulation of the key cells involved in inflammation and restoration of the balance between pro-inflammatory and anti-inflammatory mediators. Therefore, HO-1 system represents a promising therapeutic target for intervention of ventilator-induced lung injury.