Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 41
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Int J Mol Sci ; 22(6)2021 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-33804806

RESUMO

Peritoneal resident macrophages play a key role in combating sepsis in the peritoneal cavity. We sought to determine if peritoneal transplantation of embryonic Myb- "peritoneal-like" macrophages attenuate abdominal fecal sepsis. Directed differentiation of rodent pluripotent stem cells (PSCs) was used in factor-defined media to produce embryonic-derived large "peritoneal-like" macrophages (Ed-LPM) that expressed peritoneal macrophage markers and demonstrated phagocytic capacity. Preclinical in vivo studies determined Ed-LPM efficacy in rodent abdominal fecal sepsis with or without Meropenem. Ex vivo studies explored the mechanism and effects of Ed-LPM on host immune cell number and function, including phagocytosis, reactive oxygen species (ROS) production, efferocytosis and apoptosis. Ed-LPM reduced sepsis severity by decreasing bacterial load in the liver, spleen and lungs. Ed-LPM therapy significantly improved animal survival by ~30% and reduced systemic bacterial burden to levels comparable to Meropenem therapy. Ed-LPM therapy decreased peritoneal TNFα while increasing IL-10 concentrations. Ed-LPMs enhanced peritoneal macrophage phagocytosis of bacteria, increased macrophage production of ROS and restored homeostasis via apoptosis and efferocytosis-induced clearance of neutrophils. In conclusion, Ed-LPM reduced systemic sepsis severity, improved survival and reduced bacterial load by enhancing peritoneal macrophage bacterial phagocytosis and killing and clearance of intra-peritoneal neutrophils. Macrophage therapy may be a potential strategy to address sepsis.


Assuntos
Carga Bacteriana , Macrófagos/imunologia , Macrófagos/metabolismo , Proteínas Proto-Oncogênicas c-myb/deficiência , Sepse/etiologia , Sepse/metabolismo , Animais , Citocinas/metabolismo , Modelos Animais de Doenças , Contagem de Leucócitos , Macrófagos Peritoneais/imunologia , Macrófagos Peritoneais/metabolismo , Neutrófilos/imunologia , Neutrófilos/metabolismo , Fagocitose/imunologia , Prognóstico , Ratos , Sepse/diagnóstico , Sepse/mortalidade , Índice de Gravidade de Doença
3.
Anesthesiology ; 132(1): 140-154, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31764154

RESUMO

BACKGROUND: Mesenchymal stromal cells have therapeutic potential in sepsis, but the mechanism of action is unclear. We tested the effects, dose-response, and mechanisms of action of cryopreserved, xenogeneic-free human umbilical cord mesenchymal stromal cells in a rat model of fecal peritonitis, and examined the role of heme oxygenase-1 in protection. METHODS: Separate in vivo experiments evaluated mesenchymal stromal cells in fecal sepsis, established dose response (2, 5, and 10 million cells/kg), and the role of heme oxygenase-1 in mediating human umbilical cord-derived mesenchymal stromal/stem cell effects. Ex vivo studies utilized pharmacologic blockers and small inhibitory RNAs to evaluate mechanisms of mesenchymal stromal cell enhanced function in (rodent, healthy and septic human) macrophages. RESULTS: Human umbilical cord mesenchymal stromal cells reduced injury and increased survival (from 48%, 12 of 25 to 88%, 14 of 16, P = 0.0033) in fecal sepsis, with dose response studies demonstrating that 10 million cells/kg was the most effective dose. Mesenchymal stromal cells reduced bacterial load and peritoneal leukocyte infiltration (from 9.9 ± 3.1 × 10/ml to 6.2 ± 1.8 × 10/ml, N = 8 to 10 per group, P < 0.0001), and increased heme oxygenase-1 expression in peritoneal macrophages, liver, and spleen. Heme oxygenase-1 blockade abolished the effects of mesenchymal stromal cells (N = 7 or 8 per group). Mesenchymal stromal cells also increased heme oxygenase-1 expression in macrophages from healthy donors and septic patients. Direct ex vivo upregulation of macrophage heme oxygenase-1 enhanced macrophage function (phagocytosis, reactive oxygen species production, bacterial killing). Blockade of lipoxin A4 production in mesenchymal stromal cells, and of prostaglandin E2 synthesis in mesenchymal stromal cell/macrophage cocultures, prevented upregulation of heme oxygenase-1 in macrophages (from 9.6 ± 5.5-fold to 2.3 ± 1.3 and 2.4 ± 2.3 respectively, P = 0.004). Knockdown of heme oxygenase-1 production in macrophages ablated mesenchymal stromal cell enhancement of macrophage phagocytosis. CONCLUSIONS: Human umbilical cord mesenchymal stromal cells attenuate systemic sepsis by enhancing peritoneal macrophage bacterial killing, mediated partly via upregulation of peritoneal macrophage heme oxygenase-1. Lipoxin A4 and prostaglandin E2 play key roles in the mesenchymal stromal cell and macrophage interaction.


Assuntos
Heme Oxigenase-1/metabolismo , Macrófagos Peritoneais/metabolismo , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais/metabolismo , Sepse/terapia , Cordão Umbilical , Animais , Humanos , Masculino , Ratos , Ratos Sprague-Dawley
4.
J Clin Med ; 8(6)2019 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-31200579

RESUMO

Enhancing the immunomodulatory effects of mesenchymal stromal cells (MSCs) may increase their effects in sepsis. We tested the potential for overexpression of Interleukin-10 (IL-10) in human umbilical cord (UC) MSCs to increase MSC efficacy in Escherichia coli (E. coli) pneumosepsis and to enhance human macrophage function. Pneumonia was induced in rats by intratracheal instillation of E. coli ((2.0-3.0) × 109 Colony forming units (CFU)/kg). One hour later, animals were randomized to receive (a) vehicle; (b) naïve UC-MSCs; or (c) IL-10 overexpressing UC-MSCs (1 × 107 cells/kg). Lung injury severity, cellular infiltration, and E. coli colony counts were assessed after 48 h. The effects and mechanisms of action of IL-10 UC-MSCs on macrophage function in septic rodents and in humans were subsequently assessed. Survival increased with IL-10 (9/11 (82%)) and naïve (11/12 (91%)) UC-MSCs compared to vehicle (9/15 (60%, p = 0.03). IL-10 UC-MSCs-but not naïve UC-MSCs-significantly decreased the alveolar arterial gradient (455 93 and 520 81, mmHg, respectively) compared to that of vehicle animals (544 52, p = 0.02). Lung tissue bacterial counts were significantly increased in vehicle- and naïve-UC-MSC-treated animals but were not different from sham animals in those treated with IL-10 overexpressing UC-MSCs. IL-10 (but not naïve) UC-MSCs decreased alveolar neutrophils and increased alveolar macrophage percentages compared to vehicle. IL-10 UC-MSCs decreased structural lung injury compared to naïve UC-MSC or vehicle therapy. Alveolar macrophages from IL-10-UC-MSC-treated rats and from human volunteers demonstrated enhanced phagocytic capacity. This was mediated via increased macrophage hemeoxygenase-1, an effect blocked by prostaglandin E2 and lipoxygenase A4 blockade. IL-10 overexpression in UC-MSCs enhanced their effects in E. coli pneumosepsis and increased macrophage function. IL-10 UC-MSCs similarly enhanced human macrophage function, illustrating their therapeutic potential for infection-induced acute respiratory distress syndrome (ARDS).

5.
Am J Physiol Lung Cell Mol Physiol ; 316(1): L1-L5, 2019 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-30407864

RESUMO

Vitamin E (VitE) has important antioxidant and anti-inflammatory effects and is necessary for normal physiological function. α-Tocopherol (α-T), the predominant form of VitE in human tissues, has been extensively studied. Other VitE forms, particularly γ-tocopherol (γ-T), are also potent bioactive molecules. The effects are complex, involving both reactive oxygen and nitrogen species, but trials of VitE have been generally negative. We propose that a nanoparticle approach to delivery of VitE might provide effective delivery and therapeutic effect.


Assuntos
Sistemas de Liberação de Medicamentos , Nanopartículas/uso terapêutico , Nanotecnologia , Vitamina E/uso terapêutico , Animais , Humanos , Vitamina E/farmacocinética
6.
Am J Respir Crit Care Med ; 198(9): 1165-1176, 2018 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-29902384

RESUMO

RATIONALE: Ventilator management in acute respiratory distress syndrome usually focuses on setting parameters, but events occurring at ventilator disconnection are not well understood. OBJECTIVES: To determine if abrupt deflation after sustained inflation causes lung injury. METHODS: Male Sprague-Dawley rats were ventilated (low Vt, 6 ml/kg) and randomized to control (n = 6; positive end-expiratory pressure [PEEP], 3 cm H2O; 100 min) or intervention (n = 6; PEEP, 3-11 cm H2O over 70 min; abrupt deflation to zero PEEP; ventilation for 30 min). Lung function and injury was assessed, scanning electron microscopy performed, and microvascular leak timed by Evans blue dye (n = 4/group at 0, 2, 5, 10, and 20 min after deflation). Hemodynamic assessment included systemic arterial pressure (n = 6), echocardiography (n = 4), and right (n = 6) and left ventricular pressures (n = 6). MEASUREMENTS AND MAIN RESULTS: Abrupt deflation after sustained inflation (vs. control) caused acute lung dysfunction (compliance 0.48 ± 1.0 vs. 0.82 ± 0.2 m/cm H2O, oxygen saturation as measured by pulse oximetry 67 ± 23.5 vs. 91 ± 4.4%; P < 0.05) and injury (wet/dry ratio 6.1 ± 0.6 vs. 4.6 ± 0.4; P < 0.01). Vascular leak was absent before deflation and maximal 5-10 minutes thereafter; injury was predominantly endothelial. At deflation, left ventricular preload, systemic blood pressure, and left ventricular end-diastolic pressure increased precipitously in proportion to the degree of injury. Injury caused later right ventricular failure. Sodium nitroprusside prevented the increase in systemic blood pressure and left ventricular end-diastolic pressure associated with deflation, and prevented injury. Injury did not occur with gradual deflation. CONCLUSIONS: Abrupt deflation after sustained inflation can cause acute lung injury. It seems to be mediated by acute left ventricular decompensation (caused by increased left ventricular preload and afterload) that elevates pulmonary microvascular pressure; this directly injures the endothelium and causes edema, which is potentiated by the surge in pulmonary perfusion.


Assuntos
Lesão Pulmonar/etiologia , Lesão Pulmonar/fisiopatologia , Respiração com Pressão Positiva , Suspensão de Tratamento , Animais , Modelos Animais de Doenças , Pulmão/fisiopatologia , Masculino , Oximetria , Ratos , Ratos Sprague-Dawley , Mecânica Respiratória
7.
Anesthesiology ; 129(1): 163-172, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29708892

RESUMO

BACKGROUND: In supine patients with acute respiratory distress syndrome, the lung typically partitions into regions of dorsal atelectasis and ventral aeration ("baby lung"). Positive airway pressure is often used to recruit atelectasis, but often overinflates ventral (already aerated) regions. A novel approach to selective recruitment of dorsal atelectasis is by "continuous negative abdominal pressure." METHODS: A randomized laboratory study was performed in anesthetized pigs. Lung injury was induced by surfactant lavage followed by 1 h of injurious mechanical ventilation. Randomization (five pigs in each group) was to positive end-expiratory pressure (PEEP) alone or PEEP with continuous negative abdominal pressure (-5 cm H2O via a plexiglass chamber enclosing hindlimbs, pelvis, and abdomen), followed by 4 h of injurious ventilation (high tidal volume, 20 ml/kg; low expiratory transpulmonary pressure, -3 cm H2O). The level of PEEP at the start was ≈7 (vs. ≈3) cm H2O in the PEEP (vs. PEEP plus continuous negative abdominal pressure) groups. Esophageal pressure, hemodynamics, and electrical impedance tomography were recorded, and injury determined by lung wet/dry weight ratio and interleukin-6 expression. RESULTS: All animals survived, but cardiac output was decreased in the PEEP group. Addition of continuous negative abdominal pressure to PEEP resulted in greater oxygenation (PaO2/fractional inspired oxygen 316 ± 134 vs. 80 ± 24 mmHg at 4 h, P = 0.005), compliance (14.2 ± 3.0 vs. 10.3 ± 2.2 ml/cm H2O, P = 0.049), and homogeneity of ventilation, with less pulmonary edema (≈10% less) and interleukin-6 expression (≈30% less). CONCLUSIONS: Continuous negative abdominal pressure added to PEEP reduces ventilator-induced lung injury in a pig model compared with PEEP alone, despite targeting identical expiratory transpulmonary pressure.


Assuntos
Músculos Abdominais/fisiologia , Modelos Animais de Doenças , Impedância Elétrica , Pressão , Lesão Pulmonar Induzida por Ventilação Mecânica/prevenção & controle , Lesão Pulmonar Induzida por Ventilação Mecânica/fisiopatologia , Animais , Impedância Elétrica/uso terapêutico , Suínos , Volume de Ventilação Pulmonar/fisiologia
8.
J Appl Physiol (1985) ; 125(1): 107-116, 2018 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-29596015

RESUMO

We recently reported that continuous negative abdominal pressure (CNAP) could recruit dorsal atelectasis in experimental lung injury and that oxygenation improved at different transpulmonary pressure values compared with increases in airway pressure (Yoshida T, Engelberts D, Otulakowski G, Katira BH, Post M, Ferguson ND, Brochard L, Amato MBP, Kavanagh BP. Am J Respir Crit Care Med 197: 534-537, 2018). The mechanism of recruitment with CNAP is uncertain, and its impact compared with a commonly proposed alternative approach to recruitment, prone positioning, is not known. We hypothesized that CNAP recruits lung by decreasing the vertical pleural pressure (Ppl) gradient (i.e., difference between dependent and nondependent Ppl), thought to be one mechanism of action of prone positioning. An established porcine model of lung injury (surfactant depletion followed by ventilator-induced lung injury) was used. CNAP was applied using a plexiglass chamber that completely enclosed the abdomen at a constant negative pressure (-5 cmH2O). Lungs were recruited to maximal positive end-expiratory pressure (PEEP; 25 cmH2O) and deflated in steps of PEEP (2 cmH2O, 10 min each). CNAP lowered the Ppl in dependent but not in nondependent lung, and therefore, in contrast to PEEP, it narrowed the vertical Ppl gradient. CNAP increased respiratory system compliance and oxygenation and appeared to selectively displace the posterior diaphragm caudad (computerized tomography images). Compared with prone position without CNAP, CNAP in the supine position was associated with higher arterial partial pressure of oxygen and compliance, as well as greater homogeneity of ventilation. The mechanism of action of CNAP appears to be via selective narrowing of the vertical gradient of Ppl. CNAP appears to offer physiological advantages over prone positioning. NEW & NOTEWORTHY Continuous negative abdominal pressure reduces the vertical gradient in (dependent vs. nondependent) pleural pressure and increases oxygenation and lung compliance; it is more effective than prone positioning at comparable levels of positive end-expiratory pressure.


Assuntos
Pulmão/fisiologia , Decúbito Ventral/fisiologia , Animais , Pulmão/metabolismo , Complacência Pulmonar/fisiologia , Oxigênio/metabolismo , Posicionamento do Paciente/métodos , Respiração com Pressão Positiva/métodos , Pressão , Síndrome do Desconforto Respiratório/metabolismo , Síndrome do Desconforto Respiratório/fisiopatologia , Mecânica Respiratória/fisiologia , Fenômenos Fisiológicos Respiratórios , Suínos , Lesão Pulmonar Induzida por Ventilação Mecânica/metabolismo , Lesão Pulmonar Induzida por Ventilação Mecânica/fisiopatologia
9.
Anesthesiology ; 129(1): 143-153, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29474201

RESUMO

BACKGROUND: Lower tidal volumes are increasingly used in acute respiratory distress syndrome, but mortality has changed little in the last 20 yr. Therefore, in addition to ventilator settings, it is important to target molecular mediators of injury. Sepsis and other inflammatory states increase circulating concentrations of Gas6, a ligand for the antiinflammatory receptor Axl, and of a soluble decoy form of Axl. We investigated the effects of lung stretch on Axl signaling. METHODS: We used a mouse model of early injury from high tidal volume and assessed the effects of inhibiting Axl on in vivo lung injury (using an antagonist R428, n = 4/group). We further determined the effects of stretch on Axl activation using in vitro lung endothelial cells. RESULTS: High tidal volume caused mild injury (compliance decreased 6%) as intended, and shedding of the Axl receptor (soluble Axl in bronchoalveolar fluid increased 77%). The Axl antagonist R428 blocked the principal downstream Axl target (suppressor of cytokine signaling 3 [SOCS3]) but did not worsen lung physiology or inflammation. Cyclic stretch in vitro caused Axl to become insensitive to activation by its agonist, Gas6. Finally, in vitro Axl responses were rescued by blocking stretch-activated calcium channels (using guanidinium chloride [GdCl3]), and the calcium ionophore ionomycin replicated the effect of stretch. CONCLUSIONS: These data suggest that lung endothelial cell overdistention activates ion channels, and the resultant influx of Ca inactivates Axl. Downstream inactivation of Axl by stretch was not anticipated; preventing this would be required to exploit Axl receptors in reducing lung injury.


Assuntos
Lesão Pulmonar Aguda/etiologia , Lesão Pulmonar Aguda/metabolismo , Proteínas Proto-Oncogênicas/antagonistas & inibidores , Proteínas Proto-Oncogênicas/metabolismo , Receptores Proteína Tirosina Quinases/antagonistas & inibidores , Receptores Proteína Tirosina Quinases/metabolismo , Respiração Artificial/efeitos adversos , Lesão Pulmonar Aguda/patologia , Animais , Benzocicloeptenos/farmacologia , Células Cultivadas , Pulmão , Camundongos , Camundongos Endogâmicos C57BL , Distribuição Aleatória , Ratos , Respiração Artificial/tendências , Volume de Ventilação Pulmonar/efeitos dos fármacos , Volume de Ventilação Pulmonar/fisiologia , Triazóis/farmacologia
12.
Am J Respir Crit Care Med ; 196(11): 1411-1421, 2017 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-28795839

RESUMO

RATIONALE: In the original 1974 in vivo study of ventilator-induced lung injury, Webb and Tierney reported that high Vt with zero positive end-expiratory pressure caused overwhelming lung injury, subsequently shown by others to be due to lung shear stress. OBJECTIVES: To reproduce the lung injury and edema examined in the Webb and Tierney study and to investigate the underlying mechanism thereof. METHODS: Sprague-Dawley rats weighing approximately 400 g received mechanical ventilation for 60 minutes according to the protocol of Webb and Tierney (airway pressures of 14/0, 30/0, 45/10, 45/0 cm H2O). Additional series of experiments (20 min in duration to ensure all animals survived) were studied to assess permeability (n = 4 per group), echocardiography (n = 4 per group), and right and left ventricular pressure (n = 5 and n = 4 per group, respectively). MEASUREMENTS AND MAIN RESULTS: The original Webb and Tierney results were replicated in terms of lung/body weight ratio (45/0 > 45/10 ≈ 30/0 ≈ 14/0; P < 0.05) and histology. In 45/0, pulmonary edema was overt and rapid, with survival less than 30 minutes. In 45/0 (but not 45/10), there was an increase in microvascular permeability, cyclical abolition of preload, and progressive dilation of the right ventricle. Although left ventricular end-diastolic pressure decreased in 45/10, it increased in 45/0. CONCLUSIONS: In a classic model of ventilator-induced lung injury, high peak pressure (and zero positive end-expiratory pressure) causes respiratory swings (obliteration during inspiration) in right ventricular filling and pulmonary perfusion, ultimately resulting in right ventricular failure and dilation. Pulmonary edema was due to increased permeability, which was augmented by a modest (approximately 40%) increase in hydrostatic pressure. The lung injury and acute cor pulmonale is likely due to pulmonary microvascular injury, the mechanism of which is uncertain, but which may be due to cyclic interruption and exaggeration of pulmonary blood flow.


Assuntos
Edema Pulmonar/complicações , Lesão Pulmonar Induzida por Ventilação Mecânica/complicações , Disfunção Ventricular Direita/complicações , Animais , Modelos Animais de Doenças , Ecocardiografia , Coração/fisiopatologia , Pulmão/fisiopatologia , Masculino , Ratos , Ratos Sprague-Dawley , Lesão Pulmonar Induzida por Ventilação Mecânica/fisiopatologia
13.
Thorax ; 72(6): 538-549, 2017 06.
Artigo em Inglês | MEDLINE | ID: mdl-28159772

RESUMO

RATIONALE: Hypercapnia is common in mechanically ventilated patients. Experimentally, 'therapeutic hypercapnia' can protect, but it can also cause harm, depending on the mechanism of injury. Hypercapnia suppresses multiple signalling pathways. Previous investigations have examined mechanisms that were known a priori, but only a limited number of pathways, each suppressed by CO2, have been reported. OBJECTIVE: Because of the complexity and interdependence of processes in acute lung injury, this study sought to fill in knowledge gaps using an unbiased screen, aiming to identify a specifically upregulated pathway. METHODS AND RESULTS: Using genome-wide gene expression analysis in a mouse model of ventilator-induced lung injury, we discovered a previously unsuspected mechanism by which CO2 can protect against injury: induction of the transporter protein for α-tocopherol, α-tocopherol transfer protein (αTTP). Pulmonary αTTP was induced by inspired CO2 in two in vivo murine models of ventilator-induced lung injury; the level of αTTP expression correlated with degree of lung protection; and, absence of the αTTP gene significantly reduced the protective effects of CO2. α-Tocopherol is a potent antioxidant and hypercapnia increased lung α-tocopherol in wild-type mice, but this did not alter superoxide generation or expression of NRF2-dependent antioxidant response genes in wild-type or in αTTP-/- mice. In concordance with a regulatory role for α-tocopherol in lipid mediator synthesis, hypercapnia attenuated 5-lipoxygenase activity and this was dependent on the presence of αTTP. CONCLUSIONS: Inspired CO2 upregulates αTTP which increases lung α-tocopherol levels and inhibits synthesis of a pathogenic chemoattractant.


Assuntos
Proteínas de Transporte/fisiologia , Hipercapnia/metabolismo , Lesão Pulmonar Induzida por Ventilação Mecânica/prevenção & controle , Animais , Proteínas de Transporte/genética , Modelos Animais de Doenças , Deleção de Genes , Perfilação da Expressão Gênica/métodos , Regulação da Expressão Gênica/fisiologia , Estudo de Associação Genômica Ampla , Leucotrieno B4/metabolismo , Pulmão/metabolismo , Masculino , Camundongos Endogâmicos C57BL , Estresse Oxidativo/fisiologia , RNA Mensageiro/genética , Transdução de Sinais/fisiologia , Regulação para Cima/fisiologia , Lesão Pulmonar Induzida por Ventilação Mecânica/genética , Lesão Pulmonar Induzida por Ventilação Mecânica/metabolismo , alfa-Tocoferol/metabolismo
15.
Anesthesiology ; 122(4): 864-75, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25665049

RESUMO

BACKGROUND: Mechanical ventilation can injure the lung and induce a proinflammatory state; such ventilator-induced lung injury (VILI) is associated with neutrophil influx. Neutrophils release DNA and granular proteins as cytotoxic neutrophil extracellular traps (NETs). The authors hypothesized that NETs were produced in a VILI model and may contribute to injury. METHODS: In a two-hit lipopolysaccharide/VILI mouse model with and without intratracheal deoxyribonuclease (DNase) treatment or blockade of known inducers of NET formation (NETosis), the authors assessed compliance, bronchoalveolar lavage fluid protein, markers of NETs (citrullinated histone-3 and DNA), and markers of inflammation. RESULTS: Although lipopolysaccharide recruited neutrophils to airways, the addition of high tidal mechanical ventilation was required for significant induction of NETs markers (e.g., bronchoalveolar lavage fluid DNA: 0.4 ± 0.07 µg/ml [mean ± SEM], P < 0.05 vs. all others, n = 10 per group). High tidal volume mechanical ventilation increased airway high-mobility group box 1 protein (0.91 ± 0.138 vs. 0.60 ± 0.095) and interleukin-1ß in lipopolysaccharide-treated mice (22.4 ± 0.87 vs. 17.0 ± 0.50 pg/ml, P < 0.001) and tended to increase monocyte chemoattractant protein-1 and interleukin-6. Intratracheal DNase treatment reduced NET markers (bronchoalveolar lavage fluid DNA: 0.23 ± 0.038 vs. 0.88 ± 0.135 µg/ml, P < 0.001; citrullinated histone-3: 443 ± 170 vs. 1,824 ± 403, P < 0.01, n = 8 to 10) and attenuated the loss of static compliance (0.9 ± 0.14 vs. 1.58 ± 0.17 ml/mmHg, P < 0.01, n = 19 to 20) without significantly impacting other measures of injury. Blockade of high-mobility group box 1 (with glycyrrhizin) or interleukin-1ß (with anakinra) did not prevent NETosis or protect against injury. CONCLUSIONS: NETosis was induced in VILI, and DNase treatment eliminated NETs. In contrast to experimental transfusion-related acute lung injury, NETs do not play a major pathogenic role in the current model of VILI.


Assuntos
Armadilhas Extracelulares/metabolismo , Neutrófilos/metabolismo , Respiração Artificial/efeitos adversos , Lesão Pulmonar Aguda/etiologia , Lesão Pulmonar Aguda/metabolismo , Animais , Camundongos , Camundongos Endogâmicos C57BL , Infiltração de Neutrófilos/fisiologia , Distribuição Aleatória , Volume de Ventilação Pulmonar/fisiologia
16.
Curr Opin Crit Care ; 21(1): 7-12, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25546531

RESUMO

PURPOSE OF REVIEW: Multiple clinical and laboratory studies have been conducted to illustrate the effects of hypercapnia in a range of injuries, and to understand the mechanisms underlying these effects. The aim of this review is to highlight and interpret information obtained from these recent reports and discuss how they may inform the clinical context. RECENT FINDINGS: In the last decade, several important articles have addressed key elements of how carbon dioxide interacts in critical illness states. Among them the most important insights relate to how hypercapnia affects critical illness and include the effects and mechanisms of carbon dioxide in pulmonary hypertension, infection, inflammation, diaphragm dysfunction, and cerebral ischemia. In addition, we discuss molecular insights that apply to multiple aspects of critical illness. SUMMARY: Experiments involving hypercapnia have covered a wide range of illness models with varying degrees of success. It is becoming evident that deliberate hypercapnia in the clinical setting should seldom be used, except wherever necessitated to avoid ventilator-associated lung injury. A more complete understanding of the molecular mechanisms must be established.


Assuntos
Dióxido de Carbono/fisiologia , Hipercapnia/fisiopatologia , Animais , Estado Terminal , Modelos Animais de Doenças , Humanos , Camundongos , Ratos , Respiração Artificial , Síndrome do Desconforto Respiratório/fisiopatologia , Lesão Pulmonar Induzida por Ventilação Mecânica/prevenção & controle
17.
J Physiol ; 592(20): 4507-21, 2014 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-25085885

RESUMO

Hypercapnic acidosis, common in mechanically ventilated patients, has been reported to exert both beneficial and harmful effects in models of lung injury. Understanding its effects at the molecular level may provide insight into mechanisms of injury and protection. The aim of this study was to establish the effects of hypercapnic acidosis on mitogen­activated protein kinase (MAPK) activation, and determine the relevant signalling pathways. p44/42 MAPK activation in a murine model of ventilator­induced lung injury (VILI) correlated with injury and was reduced in hypercapnia. When cultured rat alveolar epithelial cells were subjected to cyclic stretch, activation of p44/42 MAPK was dependent on epidermal growth factor receptor (EGFR) activity and on shedding of EGFR ligands; exposure to 12% CO2 without additional buffering blocked ligand shedding, as well as EGFR and p44/42 MAPK activation. The EGFR ligands are known substrates of the matrix metalloprotease ADAM17, suggesting stretch activates and hypercapnic acidosis blocks stretch­mediated activation of ADAM17. This was corroborated in the isolated perfused mouse lung, where elevated CO2 also inhibited stretch­activated shedding of the ADAM17 substrate TNFR1 from airway epithelial cells. Finally, in vivo confirmation was obtained in a two­hit murine model of VILI where pharmacological inhibition of ADAM17 reduced both injury and p44/42 MAPK activation. Thus, ADAM17 is an important proximal mediator of VILI; its inhibition is one mechanism of hypercapnic protection and may be a target for clinical therapy.


Assuntos
Proteínas ADAM/metabolismo , Hipercapnia/metabolismo , Lesão Pulmonar Induzida por Ventilação Mecânica/metabolismo , Proteínas ADAM/genética , Proteína ADAM17 , Acidose/metabolismo , Acidose/fisiopatologia , Animais , Células Cultivadas , Células Epiteliais/metabolismo , Receptores ErbB/metabolismo , Hipercapnia/fisiopatologia , Sistema de Sinalização das MAP Quinases , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Ratos , Ratos Sprague-Dawley , Receptores Tipo I de Fatores de Necrose Tumoral/metabolismo , Lesão Pulmonar Induzida por Ventilação Mecânica/fisiopatologia
18.
Crit Care Med ; 41(1): 151-8, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23128385

RESUMO

BACKGROUND: Sepsis is a common indication for mechanical ventilation, which, with higher tidal volume, can cause ventilator-associated lung injury. Inflammatory mediators in the plasma or bronchoalveolar fluid are sometimes proposed as biomarkers in ICU patients. OBJECTIVE: To test the hypothesis that "priming" with subthreshold sepsis in a clinically relevant model would worsen lung function, increase ventilator-induced mediator production, and differentially impact systemic vs. pulmonary mediator levels. The model used was cecal ligation and perforation modified so that alone it caused lung inflammatory responses but not injury. METHODS AND MAIN RESULTS: Anesthetized mice were randomized to cecal ligation and perforation (vs. sham) with or without dexamethasone and 6 hrs later further randomized to: 1) sham, nonventilated, saline; 2) cecal ligation and perforation, nonventilated, saline; 3) cecal ligation and perforation, nonventilated, dexamethasone; 4) sham, high tidal volume, saline; 5) sham, high tidal volume, dexamethasone; 6) cecal ligation and perforation, high tidal volume, saline; or 7) cecal ligation and perforation, high tidal volume, dexamethasone. Mediators associated with sepsis and lung injury (cytokines: interleukin-6, tumor necrosis factor-α; chemokine: keratinocyte stimulating factor) were measured in the plasma and the bronchoalveolar lavage, and lung function (compliance, oxygenation, alveolar protein leak) assessed. High tidal volume and cecal ligation and perforation increased individual bronchoalveolar lavage and plasma mediators; high tidal volume but not cecal ligation and perforation impaired lung function. Priming of high tidal volume by cecal ligation and perforation intensified plasma and bronchoalveolar lavage mediators; the plasma (but not the bronchoalveolar lavage) mediators were inhibited by dexamethasone pretreatment. CONCLUSIONS: Mediator-but not functional-responses to high tidal volume are augmented by subthreshold sepsis priming. There is important discordance among systemic and pulmonary mediators, physiologic function, and response to corticosteroids; thus, mediator levels may be incomplete surrogates for measures of lung injury or response to therapy in the context of systemic sepsis.


Assuntos
Mediadores da Inflamação/metabolismo , Respiração Artificial/efeitos adversos , Sepse/imunologia , Sepse/terapia , Lesão Pulmonar Induzida por Ventilação Mecânica/imunologia , Animais , Biomarcadores/metabolismo , Líquido da Lavagem Broncoalveolar/imunologia , Quimiocinas/metabolismo , Mediadores da Inflamação/sangue , Interleucina-6/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Distribuição Aleatória , Volume de Ventilação Pulmonar , Fator de Necrose Tumoral alfa/metabolismo
20.
Am J Physiol Lung Cell Mol Physiol ; 300(4): L648-58, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21239530

RESUMO

Ventilator-induced lung injury (VILI) due to high tidal volume (V(T)) is associated with increased levels of circulating factors that may contribute to, or be markers of, injury. This study investigated if exclusively lung-derived circulating factors produced during high V(T) ventilation can cause or worsen VILI. In isolated perfused mouse lungs, recirculation of perfusate worsened injury (compliance impairment, microvascular permeability, edema) induced by high V(T). Perfusate collected from lungs ventilated with high V(T) and used to perfuse lungs ventilated with low V(T) caused similar compliance impairment and permeability and caused a dose-dependent decrease in transepithelial electrical resistance (TER) across rat distal lung epithelial monolayers. Circulating soluble factors derived from the isolated lung thus contributed to VILI and had deleterious effects on the lung epithelial barrier. These data demonstrate transferability of an injury initially caused exclusively by mechanical ventilation and provides novel evidence for the biotrauma hypothesis in VILI. Mediators of the TER decrease were heat-sensitive, transferable via Folch extraction, and (following ultrafiltration, 3 kDa) comprised both smaller and larger molecules. Although several classes of candidate mediators, including protein cytokines (e.g., tumor necrosis factor-α, interleukin-6, macrophage inflammation protein-1α) and lipids (e.g., eicosanoids, ceramides, sphingolipids), have been implicated in VILI, only prostanoids accumulated in the perfusate in a pattern consistent with a pathogenic role, yet cyclooxygenase inhibition did not protect against injury. Although no single class of factor appears solely responsible for the decrease in barrier function, the current data implicate lipid-soluble protein-bound molecules as not just markers but pathogenic mediators in VILI.


Assuntos
Pulmão/metabolismo , Pulmão/patologia , Lesão Pulmonar Induzida por Ventilação Mecânica/patologia , Animais , Citocinas/metabolismo , Impedância Elétrica , Epitélio/patologia , Técnicas In Vitro , Lipídeos/isolamento & purificação , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Perfusão , Prostaglandina-Endoperóxido Sintases/metabolismo , Prostaglandinas/metabolismo , Desnaturação Proteica , Ratos , Solubilidade , Temperatura , Ultrafiltração
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...