RESUMEN
Complement-mediated tissue injury in humans occurs upon deposition of immune complexes, such as in autoimmune diseases and acute respiratory distress syndrome. Acute lung inflammatory injury in wild-type and C3-/- mice after deposition of IgG immune complexes was of equivalent intensity and was C5a dependent, but injury was greatly attenuated in Hc-/- mice (Hc encodes C5). Injury in lungs of C3-/- mice and C5a levels in bronchoalveolar lavage (BAL) fluids from these mice were greatly reduced in the presence of antithrombin III (ATIII) or hirudin but were not reduced in similarly treated C3+/+ mice. Plasma from C3-/- mice contained threefold higher levels of thrombin activity compared to plasma from C3+/+ mice. There were higher levels of F2 mRNA (encoding prothrombin) as well as prothrombin and thrombin protein in liver of C3-/- mice compared to C3+/+ mice. A potent solid-phase C5 convertase was generated using plasma from either C3+/+ or C3-/- mice. Human C5 incubated with thrombin generated C5a that was biologically active. These data suggest that, in the genetic absence of C3, thrombin substitutes for the C3-dependent C5 convertase. This linkage between the complement and coagulation pathways may represent a new pathway of complement activation.
Asunto(s)
Activación de Complemento/fisiología , Complemento C3/inmunología , Complemento C5a/inmunología , Animales , Complejo Antígeno-Anticuerpo , Líquido del Lavado Bronquioalveolar/química , Líquido del Lavado Bronquioalveolar/citología , Complemento C3/genética , Complemento C5a/genética , Humanos , Inmunoglobulina G/inmunología , Hígado/citología , Hígado/metabolismo , Pulmón/inmunología , Pulmón/patología , Lesión Pulmonar , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Protrombina/genética , Protrombina/metabolismo , Trombina/metabolismoRESUMEN
Defective cardiac function during sepsis has been referred to as "cardiomyopathy of sepsis." It is known that sepsis leads to intensive activation of the complement system. In the current study, cardiac function and cardiomyocyte contractility have been evaluated in rats after cecal ligation and puncture (CLP). Significant reductions in left ventricular pressures occurred in vivo and in cardiomyocyte contractility in vitro. These defects were prevented in CLP rats given blocking antibody to C5a. Both mRNA and protein for the C5a receptor (C5aR) were constitutively expressed on cardiomyocytes; both increased as a function of time after CLP. In vitro addition of recombinant rat C5a induced dramatic contractile dysfunction in both sham and CLP cardiomyocytes, but to a consistently greater degree in cells from CLP animals. These data suggest that CLP induces C5aR on cardiomyocytes and that in vivo generation of C5a causes C5a-C5aR interaction, causing dysfunction of cardiomyocytes, resulting in compromise of cardiac performance.
Asunto(s)
Cardiomiopatías/etiología , Complemento C5a/metabolismo , Receptor de Anafilatoxina C5a/metabolismo , Sepsis/complicaciones , Animales , Anticuerpos/farmacología , Cardiomiopatías/metabolismo , Cardiomiopatías/fisiopatología , Células Cultivadas , Modelos Animales de Enfermedad , Expresión Génica , Técnicas In Vitro , Contracción Miocárdica/efectos de los fármacos , Miocitos Cardíacos/efectos de los fármacos , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/fisiología , ARN Mensajero/metabolismo , Ratas , Receptor de Anafilatoxina C5a/genética , Sarcómeros/fisiología , Sepsis/metabolismo , Sepsis/fisiopatología , Disfunción Ventricular Izquierda/etiología , Disfunción Ventricular Izquierda/metabolismo , Disfunción Ventricular Izquierda/fisiopatologíaRESUMEN
BACKGROUND: Burn injury is frequently complicated by bacterial infection. Following burn injury, exposure to endotoxin produces a measurable decrease in cardiomyocyte sarcomere contractile function. Lipopolysaccharide-binding protein (LBP) is an acute phase protein that potentiates the recognition of lipopolysaccharide (LPS) by binding to the lipid A moiety of LPS. In this study, we sought to determine the effect of recombinant rat LBP (rLBP) on cardiomyocyte sarcomere function after burn or sham injury in the presence or absence of bacterial endotoxin. METHODS: Rats underwent a full-thickness 30% total body surface area scald or sham burn. At 24 h post-injury, cardiomyocytes were isolated, plated at 50,000 cells/well, and incubated with 50 µg/mL LPS and rLBP or chloramphenicol acetyltransferase (BVCat, an irrelevant control protein produced using the same expression system as rLBP) at concentrations by volume of 1%, 5%, 10%, and 30%. Subsets of cardiomyocytes were incubated with 5% rat serum or 30% rLBP and blocking experiments were conducted using an LBP-like synthetic peptide (LBPK95A). In vitro sarcomere function was measured using a variable rate video camera system with length detection software. RESULTS: Co-culture of burn and sham injury derived cardiomyocytes with high-dose rLBP in the presence of LPS resulted in a significant reduction to the functional impairment observed in peak sarcomere shortening following exposure to LPS alone. LBP-like peptide LBPK95A at a concentration of 20 µg/mL, in the presence of LPS, abolished the ability of 30% rLBP and 5% rat serum to restore peak sarcomere shortening of cardiomyocytes isolated following burn injury to levels of function exhibited in the absence of endotoxin exposure. CONCLUSIONS: In the setting of LPS challenge following burn injury, rLBP at high concentrations restores cardiomyocyte sarcomere contractile function in vitro. Rather than potentiating the recognition of LPS by the cellular LPS receptor complex, rLBP at high concentrations likely results in an inhibitory binding effect that minimizes the impact of endotoxin exposure on cardiomyocyte function following thermal injury.
Asunto(s)
Proteínas de Fase Aguda/farmacología , Quemaduras/complicaciones , Proteínas Portadoras/farmacología , Insuficiencia Cardíaca/etiología , Glicoproteínas de Membrana/farmacología , Contracción Miocárdica/efectos de los fármacos , Animales , Apoptosis , Secuencia de Bases , Quemaduras/fisiopatología , Relación Dosis-Respuesta a Droga , Etiquetado Corte-Fin in Situ , Lipopolisacáridos/farmacología , Masculino , Datos de Secuencia Molecular , Miocitos Cardíacos/patología , Ratas , Ratas Sprague-Dawley , Proteínas Recombinantes/farmacología , Sarcómeros/efectos de los fármacos , Sarcómeros/fisiologíaRESUMEN
IL-17A is a proinflammatory cytokine produced by a variety of cells. In the current study, we examined the role of IL-17A in sepsis induced in mice by cecal ligation and puncture (CLP). IL-17A levels, which rose time-dependently in plasma after CLP, were not affected in the absence of alphabeta T cells or neutrophils. In sharp contrast, gammadelta T cell-knockout or gammadelta T cell-depleted mice displayed baseline IL-17A plasma levels after CLP. Neutralization of IL-17A by two different antibodies improved sepsis (survival from approximately 10% to nearly 60%). Unexpectedly, antibody treatment was protective, even when administration of anti-IL-17A was delayed for up to 12 h after CLP. These protective effects of IL-17A blockade were associated with substantially reduced levels of bacteremia together with significant reductions of systemic proinflammatory cytokines and chemokines in plasma. In vitro incubation of mouse peritoneal macrophages with lipopolysaccharide (LPS) in the copresence of IL-17A substantially increased the production of TNF-alpha, IL-1beta, and IL-6 by these cells. These data suggest that, during experimental sepsis, gammadelta T cell-derived IL-17A promotes high levels of proinflammatory mediators and bacteremia, resulting in enhanced lethality. IL-17A may be a potential therapeutic target in sepsis.
Asunto(s)
Interleucina-17/toxicidad , Sepsis/fisiopatología , Animales , Bacteriemia , Ciego/patología , Quimiocinas/sangre , Citocinas/sangre , Modelos Animales de Enfermedad , Inflamación , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Punciones , Sepsis/etiología , Linfocitos T/patologíaRESUMEN
We recently showed that acute oxidant-related lung injury (ALI) in rats after application of 2-chloroethyl ethyl sulfide (CEES) is attenuated by the airway instillation of antioxidants. We investigated whether intratracheal administration of antioxidant-containing liposomes immediately after instillation of CEES would attenuate short-term as well as long-term (fibrotic) effects of CEES-induced lung injury. In the acute injury model (4 h after injury), N-acetylcysteine (NAC)-containing liposomes were protective and reduced to baseline levels both the lung permeability index and the appearance of proinflammatory mediators in bronchoalveolar lavage fluids from CEES-exposed lungs. Similar results were obtained when rat alveolar macrophages were incubated in vitro with either CEES or lipopolysaccharide in the presence of NAC-liposomes. When lung fibrosis 3 weeks after CEES was quantitated by using hydroxyproline content, liposomes containing NAC or NAC + glutathione had no effects, but liposomes containing alpha/gamma-tocopherol alone or with NAC significantly suppressed the increase in lung hydroxyproline. The data demonstrate that delivery of antioxidants via liposomes to CEES-injured lungs is, depending on liposomal content, protective against ALI, prevents the appearance of proinflammatory mediators in bronchoalveolar fluids, and suppresses progressive fibrosis. Accordingly, the liposomal strategy may be therapeutically useful in CEES-induced lung injury in humans.
Asunto(s)
Antioxidantes , Liposomas , Síndrome de Dificultad Respiratoria/tratamiento farmacológico , Síndrome de Dificultad Respiratoria/prevención & control , Acetilcisteína/administración & dosificación , Acetilcisteína/metabolismo , Acetilcisteína/uso terapéutico , Animales , Antioxidantes/química , Antioxidantes/metabolismo , Antioxidantes/uso terapéutico , Líquido del Lavado Bronquioalveolar/química , Quimiocinas/metabolismo , Citocinas/metabolismo , Depuradores de Radicales Libres/administración & dosificación , Depuradores de Radicales Libres/metabolismo , Depuradores de Radicales Libres/uso terapéutico , Humanos , Liposomas/administración & dosificación , Liposomas/química , Liposomas/metabolismo , Liposomas/uso terapéutico , Pulmón/citología , Pulmón/efectos de los fármacos , Pulmón/metabolismo , Pulmón/patología , Macrófagos Alveolares/metabolismo , Masculino , Gas Mostaza/análogos & derivados , Gas Mostaza/farmacología , Ratas , Ratas Long-Evans , Síndrome de Dificultad Respiratoria/inducido químicamente , Síndrome de Dificultad Respiratoria/patología , Tocoferoles/administración & dosificación , Tocoferoles/metabolismo , Tocoferoles/uso terapéuticoRESUMEN
Despite intensive ongoing research efforts, the mortality of patients with sepsis remains unacceptably high. A significant number of clinical trials have failed to produce sufficient therapeutic strategies despite showing promising results in animal models. So far, many studies have focused on deterioration of the humoral and cellular components of the immune system, the main cause of death in septic patients being multi-organ failure. However, not much is known about the effects of the complement system on parenchymal cells of organs such as the heart. Recently, septic cardiomyopathy has been recognized as one of the major complications during sepsis, often determining the clinical outcome. In this review, we describe molecular events which are thought to be related to cardiac dysfunction during sepsis. A special emphasis will be placed on the complement system, which generates powerful anaphylatoxins (such as C5a) and which has recently been associated with septic cardiomyopathy. Together with the impact on cardiac function of various cytokines we will provide a synopsis of the current knowledge regarding the pathophysiology underlying cardiac failure during sepsis with a special emphasis on C5a and C5aR.
Asunto(s)
Proteínas del Sistema Complemento/fisiología , Insuficiencia Cardíaca/etiología , Sepsis/complicaciones , Animales , Citocinas/fisiología , Proteína HMGB1/fisiología , Corazón/fisiopatología , Humanos , Inflamación/fisiopatología , Factores Inhibidores de la Migración de Macrófagos/fisiología , Proteínas de la Membrana/fisiología , Óxido Nítrico/fisiología , Receptor de Anafilatoxina C5a , Receptores de Complemento/fisiologíaRESUMEN
BACKGROUND: Although the inflammatory response is a prerequisite for wound healing, excessive activation of the innate immune system can induce epithelial cell damage and apoptosis, which may further compromise dermal integrity. In a noninfectious burn wound model, we previously demonstrated that topical inhibition of p38 MAPK, an important inflammatory signaling pathway, attenuated epithelial cell damage and apoptosis. We now question whether attenuating local inflammation would weaken bacterial wound resistance and compromise host defense. METHODS: Rats received 30% total body surface area burn, and the wound was treated with topical application of a p38 MAPK inhibitor or vehicle. At 24 hours after injury, burn wounds were inoculated with Pseudomonas aeruginosa. At 48 hours postinjury, animals were sacrificed, and the burn wound was analyzed. RESULTS: Inoculating burn wounds induced significant bacterial growth. Dermal inflammatory changes were markedly accentuated in the inoculated animals. Topical p38 MAPK inhibition reduced the proinflammatory cytokine expression in the burn wounds and neutrophil sequestration with or without bacterial inoculation. Interestingly, the bacterial wound growth was significantly attenuated in animals treated with topical p38 MAPK inhibitor. CONCLUSIONS: Topical p38 MAPK inhibition attenuated wound inflammation without interfering with bacterial host defense. Attenuation of excessive burn wound inflammatory signaling may prevent secondary damage of the dermal barrier and reduce the growth of opportunistic pathogens.
Asunto(s)
Quemaduras/microbiología , Inhibidores Enzimáticos/administración & dosificación , Imidazoles/administración & dosificación , Pseudomonas aeruginosa/efectos de los fármacos , Pseudomonas aeruginosa/crecimiento & desarrollo , Piridinas/administración & dosificación , Proteínas Quinasas p38 Activadas por Mitógenos/antagonistas & inhibidores , Administración Tópica , Animales , Quemaduras/complicaciones , Quemaduras/metabolismo , Quemaduras/patología , Quimiocina CXCL2 , Quimiocinas CXC/antagonistas & inhibidores , Quimiocinas CXC/metabolismo , Ensayo de Unidades Formadoras de Colonias , Citocinas/antagonistas & inhibidores , Dermatitis/etiología , Dermatitis/microbiología , Dermatitis/patología , Inhibidores Enzimáticos/farmacología , Imidazoles/farmacología , Mediadores de Inflamación/antagonistas & inhibidores , Masculino , Infiltración Neutrófila/efectos de los fármacos , Óxido Nítrico/antagonistas & inhibidores , Infecciones por Pseudomonas , Piridinas/farmacología , Ratas , Ratas Sprague-Dawley , Piel/metabolismoRESUMEN
Despite intensive ongoing research efforts, the mortality of patients with sepsis remains unacceptably high. Clinical trials emerging from promising results in animal models have mostly failed to deliver sufficient treatment strategies so far. Many studies investigating the underlying mechanisms of sepsis have focused on deterioration of the humoral and cellular components of the immune system. However, in addition to septic shock, the main cause of death in septic patients is multiorgan failure. So far, not much is known about the effects of a dysregulated immune system as seen in sepsis on parenchymal cells of end organs. Studies on the interaction of the complement system and kidney as well as liver cells resulted in interesting yet still inconclusive data. In this review, we provide new insights into mechanisms during sepsis based on recent findings.
Asunto(s)
Sepsis/inmunología , Sepsis/metabolismo , Animales , Proteínas del Sistema Complemento/metabolismo , Corazón/fisiopatología , Humanos , Miocitos Cardíacos/inmunología , Neutrófilos/inmunología , Neutrófilos/metabolismo , Receptor de Anafilatoxina C5a/metabolismo , Sepsis/fisiopatología , Síndrome de Respuesta Inflamatoria Sistémica/inmunología , Síndrome de Respuesta Inflamatoria Sistémica/metabolismo , Síndrome de Respuesta Inflamatoria Sistémica/fisiopatologíaRESUMEN
Thermal injury induces dermal inflammatory and proapoptotic signaling. These phenomena extend burn wound size and trigger a systemic inflammatory response, factors known to adversely affect outcomes. p38MAPK is known to trigger inflammatory responses and induce epithelial proapoptotic genes. We hypothesize that topical p38MAPK inhibition will attenuate excessive inflammatory and apoptotic signaling and reduce dermal tissue loss. Rats were given a 30% total body surface area partial thickness burn or sham injury. Some of the animals were treated with a p38MAPK inhibitor or vehicle, which was applied directly to the wound. Dermal inflammation was investigated with enzyme-linked immunosorbent assay, reverse transcriptase polymerase chain reaction, myeloperoxidase assay, and Evans blue extravasation. Apoptotic changes were detected using terminal deoxynucleotidyl transferase dUTP nick-end labeling assay and Caspase-3 in situ staining. Burn injury activated dermal p38MAPK and induced a significant rise in dermal IL-6, TNF-alpha, and IL-1beta expression. Neutrophil sequestration, microvascular damage, and hair follicle apoptosis were significantly elevated after injury. Topical p38MAPK inhibition significantly attenuated downstream dermal p38MAPK targets, proinflammatory cytokine expression, neutrophil sequestration, and microvascular injury. A significant reduction in hair follicle apoptosis was seen. This study demonstrates the attenuation of burn-induced cellular stress by topical application of p38MAPK inhibitors. Blunting early excessive inflammatory signaling may be an efficient strategy to improve patient outcomes after burn injury.
Asunto(s)
Apoptosis/efectos de los fármacos , Quemaduras/tratamiento farmacológico , Dermatitis/tratamiento farmacológico , Inhibidores Enzimáticos/farmacología , Imidazoles/farmacología , Piridinas/farmacología , Proteínas Quinasas p38 Activadas por Mitógenos/antagonistas & inhibidores , Administración Tópica , Animales , Quemaduras/complicaciones , Quemaduras/patología , Quimiocinas CXC/metabolismo , Citocinas/efectos de los fármacos , Citocinas/genética , Citocinas/metabolismo , Dermatitis/patología , Relación Dosis-Respuesta a Droga , Inhibidores Enzimáticos/administración & dosificación , Células Epiteliales/efectos de los fármacos , Células Epiteliales/patología , Imidazoles/administración & dosificación , Interleucina-6/genética , Masculino , Neutrófilos/efectos de los fármacos , Piridinas/administración & dosificación , Ratas , Ratas Sprague-Dawley , Transducción de Señal , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismoRESUMEN
The majority of blunt trauma is secondary to motor vehicle crashes,especially in those wearing seatbelts or sitting in the front or passenger seat location.Hollow viscus gastrointestinal injuries occur more frequently in small bowel, followed by colorectal, duodenum, stomach and appendix. A 25-year-old male presents after being involved in a motor vehicle accident. Initialworkup was significant for moderate amount of pelvic free fluid and curvilinear,cysticlike structures in the pelvis. He subsequently developed peritonitis and underwentdiagnostic laparoscopy, which revealed multiple cystic nodules arising from theperitoneum. Pathology demonstrated benign cystic mesothelioma (BCM). BCM is a very rarecondition of mesotheliallined, variably sized, fluidfilled cysts that arises from theserous, pericardial or peritoneal lining. Due to the scarcity of cases, its management and prognosis are not fully established. This singular case highlights the necessity for a clinician to have a widedifferential forunusual causes of free pelvic fluid after blunt abdominaltrauma.
RESUMEN
The current studies demonstrate protective and harmful effects of neutrophils (PMN) during experimental sepsis after cecal ligation and puncture (CLP). It is known that CLP induces signaling defects in blood PMN. When PMN were depleted 12 h after CLP, there were dramatic reductions in levels of bacteremia, evidence for reduced liver and renal dysfunction, sharp reductions in serum levels of cytokines (IL-1beta, IL-6, IL-10, TNF-alpha, and IL-2), and improved survival. In contrast, PMN depletion before CLP resulted in substantial increases in bacteremia and no evidence for attenuation of liver and renal failure dysfunction. These data suggest that at the onset of sepsis, PMN are important in regulating the levels of bacteremia, whereas after the onset of sepsis, as they lose innate immune functions, their presence is associated with higher levels of bacteremia and intensified organ dysfunction.
Asunto(s)
Neutrófilos/inmunología , Neutrófilos/fisiología , Sepsis/inmunología , Sepsis/fisiopatología , Animales , Inmunoglobulina G/farmacología , Riñón/inmunología , Hígado/inmunología , Ratones , Insuficiencia Multiorgánica/sangre , Neutropenia , Especificidad de Órganos , Peroxidasa/análisis , Ratas , Sepsis/sangre , Factores de TiempoRESUMEN
BACKGROUND: Topical inhibition of activated p38 MAPK within burn wounds attenuates the local and systemic inflammatory response. In this study, we investigated the effects of local activated p38 MAPK inhibition on burn-induced cardiac dysfunction. METHODS: Using a standardized rat model of scald burn injury, rats were given a 30% total body surface area partial thickness burn or sham injury, and the wounds were treated with an activated p38 MAPK inhibitor (SB) or vehicle. Systemic blood pressure measurements were recorded in vivo followed by in vitro assessment of sarcomere contraction in single-cell suspensions of isolated cardiomyocytes. RESULTS: Systolic blood pressure or maximum left ventricular pressures in vivo and peak cardiomyocyte sarcomere contractility in vitro were significantly reduced after burn injury. These functional deficits were abolished 24 h after burn injury following local p38 MAPK inhibition. In vitro incubation of normal cardiomyocytes with homogenate from burned skin or burn serum resulted in a similar pattern of impaired cardiomyocyte contractility. These effects were reversed in normal cardiomyocytes exposed to burn skin homogenates treated topically with a p38 MAPK inhibitor. A Western blot analysis showed that cardiac p38 MAPK activation was not affected by dermal blockade of activated p38 MAPK, arguing against systemic absorption of the inhibitor and indicating the involvement of systemic cytokine signaling. CONCLUSION: Topical activated p38 MAPK inhibition within burned skin attenuates the release of proinflammatory mediators and prevents burn-induced cardiac dysfunction after thermal injury. These results support the inhibition of burn-wound inflammatory signaling as a new therapeutic approach to prevent potential postthermal injury multiorgan dysfunction syndrome.
Asunto(s)
Quemaduras/fisiopatología , Imidazoles/farmacología , Contracción Miocárdica/efectos de los fármacos , Inhibidores de Proteínas Quinasas/farmacología , Piridinas/farmacología , Función Ventricular Izquierda/efectos de los fármacos , Proteínas Quinasas p38 Activadas por Mitógenos/antagonistas & inhibidores , Animales , Masculino , Ratas , Ratas Sprague-Dawley , Sarcómeros/efectos de los fármacosRESUMEN
BACKGROUND: Previous studies demonstrated a correlation between bone density, stability of fracture fixation, and outcome. Because current fracture classifications do not take osteoporosis into account, a prospective radiological analysis was conducted of patients with hip and wrist fracture to evaluate the impact of osteoporosis on fracture classification. MATERIAL/METHODS: Altogether, 77 consecutive patients with either hip or wrist fracture were prospectively recruited within 24 hours of sustaining the fracture. The patients were assigned to subgroups according to gender, fracture site, fracture type, and bone mineral density (BMD). Using widely accepted classification systems for hip and wrist fractures, the impact of osteoporosis on fracture classification was assessed. RESULTS: Osteoporosis dominated in both fracture types and bone mineral density showed a significant negative correlation with age. Pertrochanteric fractures were more frequent, showing an equal distribution among severity grades, while less frequent femoral neck fractures were mainly unstable fractures. Postmenopausal patients sustained more severe intraarticular comminuted wrist fractures, which were not found using the Fernandez classification. CONCLUSIONS: The contradiction between the higher incidence but lower severity of pertrochanteric fractures compared with femoral neck fractures in osteoporotic bone and inconsistencies between the classifications of wrist fractures may indicate incomplete fracture classification in osteoporosis. Given the high incidence of osteoporotic fractures, incorporating bone mineral status into fracture classification systems may improve preoperative assessment, implant stability, and outcome.
Asunto(s)
Fracturas de Cadera/clasificación , Osteoporosis , Traumatismos de la Muñeca/clasificación , Adulto , Anciano , Anciano de 80 o más Años , Densidad Ósea , Femenino , Humanos , Masculino , Persona de Mediana Edad , Osteoporosis Posmenopáusica , Estudios ProspectivosRESUMEN
Although acute lung injury (ALI) is an important problem in humans, its pathogenesis is poorly understood. Airway instillation of bacterial LPS, a known complement activator, represents a frequently used model of ALI. In the present study, pathways in the immunopathogenesis of ALI were evaluated. ALI was induced in wild-type, C3(-/-), and C5(-/-) mice by airway deposition of LPS. To assess the relevant inflammatory mediators, bronchoalveolar lavage fluids were evaluated by ELISA analyses and various neutralizing Abs and receptor antagonists were administered in vivo. LPS-induced ALI was neutrophil-dependent, but it was not associated with generation of C5a in the lung and was independent of C3, C5, or C5a. Instead, LPS injury was associated with robust generation of macrophage migration inhibitory factor (MIF), leukotriene B(4) (LTB4), and high mobility group box 1 protein (HMGB1) and required engagement of receptors for both MIF and LTB4. Neutralization of MIF or blockade of the MIF receptor and/or LTB4 receptor resulted in protection from LPS-induced ALI. These findings indicate that the MIF and LTB4 mediator pathways are involved in the immunopathogenesis of LPS-induced experimental ALI. Most strikingly, complement activation does not contribute to the development of ALI in the LPS model.
Asunto(s)
Activación de Complemento , Proteínas del Sistema Complemento/metabolismo , Proteína HMGB1/metabolismo , Leucotrieno B4/metabolismo , Lipopolisacáridos/inmunología , Factores Inhibidores de la Migración de Macrófagos/metabolismo , Síndrome de Dificultad Respiratoria/inmunología , Animales , Líquido del Lavado Bronquioalveolar/inmunología , Proteínas del Sistema Complemento/inmunología , Modelos Animales de Enfermedad , Proteína HMGB1/inmunología , Mediadores de Inflamación/metabolismo , Leucotrieno B4/inmunología , Pulmón/inmunología , Pulmón/metabolismo , Factores Inhibidores de la Migración de Macrófagos/inmunología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Mutantes , Síndrome de Dificultad Respiratoria/metabolismoRESUMEN
OBJECTIVE: We previously showed that topical inhibition of inflammatory signaling in burn wounds reduced systemic inflammatory response and burn-induced pulmonary inflammation. We hypothesized that this topical intervention would attenuate burn-induced lung injury, improve pulmonary function, protect lungs from bacterial invasion, and reduce mortality. DESIGN: Controlled, in vivo, laboratory study. SETTING: University laboratory. SUBJECTS: Female mice, 8-10 wks old. INTERVENTIONS: Animals received 30% total body surface area burn followed by topical application of a specific inhibitor of p38 mitogen-activated protein kinase, a key inflammatory signaling pathway, or vehicle to the wound. Twenty-four hours after injury, pulmonary collagen deposition and pulmonary function were assessed. One day postburn, some of the animals received intratracheal instillation of Klebsiella pneumoniae and were subsequently monitored for 7 days. MEASUREMENTS AND MAIN RESULTS: Topical inhibition of p38 mitogen-activated protein kinase significantly decreased pulmonary collagen deposition and prevented a decline in pulmonary function at 1 day after burn injury. Compared with sham controls, animals with burn injury had a significantly higher mortality in response to intratracheal bacterial challenge. Application of p38 mitogen-activated protein kinase inhibitor to the burn wound attenuated pulmonary neutrophil infiltration and reduced the mortality rate to a level experienced by sham controls. CONCLUSIONS: Inflammatory source control in burn wounds with topical p38 mitogen-activated protein kinase inhibition attenuates acute lung injury, avoids pulmonary dysfunction, protects lungs from bacterial challenge, and improves survival.
Asunto(s)
Quemaduras/tratamiento farmacológico , Quemaduras/fisiopatología , Neumonía/prevención & control , Proteínas Quinasas p38 Activadas por Mitógenos/antagonistas & inhibidores , Animales , Colágeno/metabolismo , Modelos Animales de Enfermedad , Femenino , Infecciones por Klebsiella/prevención & control , Klebsiella pneumoniae , Pulmón/metabolismo , Ratones , Transducción de Señal/efectos de los fármacosRESUMEN
We previously reported that generation of the anaphylatoxin C5a is linked to the development of cardiac dysfunction in sepsis due to C5a interaction with its receptor (C5aR) on cardiomyocytes. Burn injury involves inflammatory mechanisms that can lead to C5a generation as well. In this study, we investigated the effects of C5a blockade on burn-induced cardiac dysfunction. Using a standardized rat model of full thickness scald injury, left ventricular pressures were recorded in vivo followed by in vitro assessment of sarcomere contraction of single cardiomyocytes. Left ventricular pressures in vivo and cardiomyocyte sarcomere contractility in vitro were significantly reduced following burn injury. In the presence of anti-C5a Ab, these defects were greatly attenuated 1, 6, and 12 h after burn injury and completely abolished 24 h after burn. In vitro incubation of cardiomyocytes with bacterial LPS accentuated the impaired contractility, which was partially prevented in cardiomyocytes from burned rats that had received an anti-C5a Ab. Based on Western blot analyses, real-time PCR, and immunostaining of left ventricular heart tissue, there was a significant increase in cardiomyocyte expression of C5aR after burn injury. In conclusion, an in vivo blockade of C5a attenuates burn-induced cardiac dysfunction. Further deterioration of contractility due to the exposure of cardiomyocytes to LPS was partially prevented by C5a-blockade. These results suggest a linkage between C5a and burn-induced cardiac dysfunction and a possible contribution of LPS to these events.
Asunto(s)
Quemaduras/complicaciones , Complemento C5a/antagonistas & inhibidores , Receptor de Anafilatoxina C5a/metabolismo , Disfunción Ventricular Izquierda/inmunología , Disfunción Ventricular Izquierda/fisiopatología , Animales , Anticuerpos/farmacología , Western Blotting , Lipopolisacáridos/inmunología , Masculino , Contracción Miocárdica/efectos de los fármacos , Miocitos Cardíacos/química , Miocitos Cardíacos/inmunología , Reacción en Cadena de la Polimerasa , Presión , Ratas , Ratas Sprague-Dawley , Receptor de Anafilatoxina C5a/análisis , Receptor de Anafilatoxina C5a/genética , Sarcómeros/fisiologíaRESUMEN
The relationship between local inflammation and the subsequent systemic inflammatory response is poorly described. In a burn injury model, the dermal inflammatory response may act as an ongoing trigger for the systemic inflammatory response syndrome (SIRS) and subsequent systemic complications. We hypothesized that topical attenuation of burn wound inflammatory signaling will control the dermal inflammatory source, attenuate SIRS, and reduce acute lung injury. Mice received a 30% total body surface area burn. Subgroups were treated with specific p38 MAPK inhibitor or vehicle, which was topically applied to wounds. Topical p38 MAPK inhibition significantly reduced burn wound inflammatory signaling and subsequent systemic expression of proinflammatory cytokines and chemokines. In vitro macrophage functional assays demonstrated a significant attenuation in serum inflammatory mediators from animals receiving the topical inhibitor. Topical p38 MAPK inhibition resulted in significantly less pulmonary inflammatory response via reduction of pulmonary neutrophil sequestration, pulmonary cytokine expression, and a significant reduction in pulmonary microvascular injury and edema formation. Although dermal activating transcription factor-2, a downstream p38 MAPK target, was significantly reduced, there was no reduction in pulmonary activating transcription factor-2 expression, arguing against significant systemic absorption of the topical inhibitor. These experiments demonstrate a strong interaction between dermal inflammation and systemic inflammatory response. Attenuating local inflammatory signaling appears effective in reducing SIRS and subsequent systemic complications after burn injury.
Asunto(s)
Quemaduras/complicaciones , Síndrome de Dificultad Respiratoria/etiología , Transducción de Señal/inmunología , Síndrome de Respuesta Inflamatoria Sistémica/etiología , Proteínas Quinasas p38 Activadas por Mitógenos/antagonistas & inhibidores , Animales , Quemaduras/inmunología , Citocinas/biosíntesis , Inhibidores Enzimáticos/farmacología , Ensayo de Inmunoadsorción Enzimática , Expresión Génica , Inflamación/inmunología , Ratones , Ratones Endogámicos C57BL , Síndrome de Dificultad Respiratoria/inmunología , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Transducción de Señal/efectos de los fármacos , Piel/inmunología , Piel/patología , Síndrome de Respuesta Inflamatoria Sistémica/prevención & control , Proteínas Quinasas p38 Activadas por Mitógenos/efectos de los fármacosRESUMEN
Airway instillation into rats of 2-chloroethyl ethyl sulfide (CEES), the half molecule of sulfur mustard compound, results in acute lung injury, as measured by the leak of plasma albumin into the lung. Morphologically, early changes in the lung include alveolar hemorrhage and fibrin deposition and the influx of neutrophils. Following lung contact with CEES, progressive accumulation of collagen occurred in the lung, followed by parenchymal collapse. The co-instillation with CEES of liposomes containing pegylated (PEG)-catalase (CAT), PEG-superoxide dismutase (SOD), or the combination, greatly attenuated the development of lung injury. Likewise, the co-instillation of liposomes containing the reducing agents, N-acetylcysteine (NAC), glutathione (GSH), or resveratrol (RES), significantly reduced acute lung injury. The combination of complement depletion and airway instillation of liposomes containing anti-oxidant compounds maximally attenuated CEES-induced lung injury by nearly 80%. Delayed airway instillation of anti-oxidant-containing liposomes (containing NAC or GSH, or the combination) significantly diminished lung injury even when instillation was delayed as long as 1 h after lung exposure to CEES. These data indicate that CEES-induced injury of rat lungs can be substantially diminished by the presence of reducing agents or anti-oxidant enzymes delivered via liposomes.