RESUMEN
BACKGROUND: Obesity is associated with the development of acute respiratory distress syndrome (ARDS) in at-risk patients. Low plasma levels of adiponectin, a circulating hormone-like molecule, have been implicated as a possible mechanism for this association. The objective of this study was to determine the association of plasma adiponectin level at ICU admission with ARDS and 30-day mortality in patients with severe sepsis and septic shock. METHODS: This is a prospective cohort study of patients admitted to the medical ICU at the Hospital of the University of Pennsylvania. Plasma adiponectin was measured at the time of ICU admission. ARDS was defined by Berlin criteria. Multivariable logistic regression was used to determine the association of plasma adiponectin with the development of ARDS and mortality at 30 days. RESULTS: The study included 164 patients. The incidence of ARDS within 5 days of admission was 45%. The median initial plasma adiponectin level was 7.62 mcg/ml (IQR: 3.87, 14.90) in those without ARDS compared to 8.93 mcg/ml (IQR: 4.60, 18.85) in those developing ARDS. The adjusted odds ratio for ARDS associated with each 5 mcg increase in adiponectin was 1.12 (95% CI 1.01, 1.25), p-value 0.025). A total of 82 patients (51%) of the cohort died within 30 days of ICU admission. There was a statistically significant association between adiponectin and mortality in the unadjusted model (OR 1.11, 95% CI 1.00, 1.23, p-value 0.04) that was no longer significant after adjusting for potential confounders. CONCLUSIONS: In this study, low levels of adiponectin were not associated with an increased risk of ARDS in patients with severe sepsis and septic shock. This argues against low levels of adiponectin as a mechanism explaining the association of obesity with ARDS. At present, it is unclear whether circulating adiponectin is involved in the pathogenesis of ARDS or simply represents an epiphenomenon of other unknown functions of adipose tissue or metabolic alterations in sepsis.
Asunto(s)
Adiponectina/análisis , Obesidad/complicaciones , Síndrome de Dificultad Respiratoria/etiología , Sepsis/diagnóstico , Adiponectina/sangre , Adiponectina/uso terapéutico , Anciano , Estudios de Cohortes , Femenino , Humanos , Unidades de Cuidados Intensivos , Modelos Logísticos , Masculino , Persona de Mediana Edad , Pennsylvania , Pronóstico , Estudios Prospectivos , Respiración Artificial/efectos adversos , Síndrome de Dificultad Respiratoria/mortalidad , Estudios Retrospectivos , Factores de Riesgo , Sepsis/mortalidad , Choque Séptico/diagnóstico , Choque Séptico/mortalidadRESUMEN
BACKGROUND: Immunocompromised patients who develop sepsis while neutropenic are at high risk for morbidity and mortality; however, it is unknown if neutropenic sepsis is associated with distinct clinical and biological characteristics. METHODS: We conducted a prospective cohort study of patients admitted to the medical intensive care unit of an academic medical center with severe sepsis. Patients were followed for the development of acute respiratory distress syndrome (ARDS), acute kidney injury (AKI), and mortality. Plasma proteins, representing the host inflammatory response, anti-inflammatory response, and endothelial leak were measured in 30 % of subjects. Clinical characteristics and plasma protein concentrations of patients with neutropenia at enrollment were compared to patients without neutropenia. RESULTS: Of 797 subjects enrolled, 103 (13 %) were neutropenic at ICU admission. The neutropenic subjects were more often in shock, admitted from the hospital ward, had higher APACHE III scores, and more likely bacteremic. Neutropenia was an independent risk factor for AKI (RR 1.28; 95 % CI 1.04, 1.57; p = 0.03), but not ARDS (RR 0.90; 95 % CI 0.70, 1.17; p = 0.42) or 30-day mortality (RR 1.05; 95 % CI 0.85, 1.31; p = 0.65). Neutropenic subjects had higher plasma interleukin (IL)-6 (457 vs. 249 pg/ml; p = 0.03), IL-8 (581 vs. 94 pg/ml; p <0.001), and granulocyte colony-stimulating factor (G-CSF) (3624 vs. 99 pg/ml; p <0.001). Angiopoietin-2 and IL-1 receptor antagonist concentrations did not differ between groups. CONCLUSIONS: Neutropenic sepsis is associated with a higher AKI risk and concentrations of inflammatory mediators IL-6, IL-8, and G-CSF relative to non-neutropenic patients. These differences may have implications for future therapies targeting neutropenic sepsis.
Asunto(s)
Neutropenia/clasificación , Sepsis/clasificación , Sepsis/mortalidad , APACHE , Lesión Renal Aguda/epidemiología , Lesión Renal Aguda/mortalidad , Adulto , Anciano , Angiopoyetina 2/análisis , Angiopoyetina 2/sangre , Biomarcadores/análisis , Biomarcadores/sangre , Distribución de Chi-Cuadrado , Estudios de Cohortes , Enfermedad Crítica/epidemiología , Femenino , Factor Estimulante de Colonias de Granulocitos/análisis , Factor Estimulante de Colonias de Granulocitos/sangre , Humanos , Unidades de Cuidados Intensivos/organización & administración , Unidades de Cuidados Intensivos/estadística & datos numéricos , Interleucina-6/análisis , Interleucina-6/sangre , Interleucina-8/análisis , Interleucina-8/sangre , Interleucinas/análisis , Interleucinas/sangre , Masculino , Persona de Mediana Edad , Neutropenia/epidemiología , Neutropenia/mortalidad , Pennsylvania/epidemiología , Estudios Prospectivos , Receptores de Interleucina-1/análisis , Receptores de Interleucina-1/sangre , Síndrome de Dificultad Respiratoria/epidemiología , Síndrome de Dificultad Respiratoria/mortalidad , Sepsis/epidemiologíaRESUMEN
RATIONALE: Biologic pathways with significant genetic conservation across human populations have been implicated in the pathogenesis of primary graft dysfunction (PGD). The evaluation of the role of recipient genetic variation in PGD has thus far been limited to single, candidate gene analyses. OBJECTIVES: We sought to identify genetic variants in lung transplant recipients that are responsible for increased risk of PGD using a two-phase large-scale genotyping approach. METHODS: Phase 1 was a large-scale candidate gene association study of the multicenter, prospective Lung Transplant Outcomes Group cohort. Phase 2 included functional evaluation of selected variants and a bioinformatics screening of variants identified in phase 1. MEASUREMENTS AND MAIN RESULTS: After genetic data quality control, 680 lung transplant recipients were included in the analysis. In phase 1, a total of 17 variants were significantly associated with PGD, four of which were in the prostaglandin E2 family of genes. Among these were a coding variant in the gene encoding prostaglandin E2 synthase (PTGES2; P = 9.3 × 10(-5)) resulting in an arginine to histidine substitution at amino acid position 298, and three variants in a block containing the 5' promoter and first intron of the PTGER4 gene (encoding prostaglandin E2 receptor subtype 4; all P < 5 × 10(-5)). Functional evaluation in regulatory T cells identified that rs4434423A in the PTGER4 gene was associated with differential suppressive function of regulatory T cells. CONCLUSIONS: Further research aimed at replication and additional functional insight into the role played by genetic variation in prostaglandin E2 synthetic and signaling pathways in PGD is warranted.
Asunto(s)
Oxidorreductasas Intramoleculares/genética , Trasplante de Pulmón , Polimorfismo de Nucleótido Simple , Disfunción Primaria del Injerto/genética , Subtipo EP4 de Receptores de Prostaglandina E/genética , Biomarcadores/sangre , Biología Computacional , Dinoprostona/sangre , Femenino , Estudios de Asociación Genética , Marcadores Genéticos , Genotipo , Técnicas de Genotipaje , Humanos , Masculino , Persona de Mediana Edad , Disfunción Primaria del Injerto/sangre , Disfunción Primaria del Injerto/inmunología , Estudios Prospectivos , Prostaglandina-E Sintasas , Linfocitos T Reguladores/metabolismoRESUMEN
Surfactant protein A (SP-A) plays an important role in the maintenance of lung lipid homeostasis. Previously, an SP-A receptor, P63 (CKAP4), on type II pneumocyte plasma membranes (PM) was identified by chemical cross-linking techniques. An antibody to P63 blocked the specific binding of SP-A to pneumocytes and the ability of SP-A to regulate surfactant secretion. The current report shows that another biological activity of SP-A, the stimulation of surfactant uptake by pneumocytes, is inhibited by P63 antibody. cAMP exposure resulted in enrichment of P63 on the cell surface as shown by stimulation of SP-A binding, enhanced association of labeled P63 antibody with type II cells, and promotion of SP-A-mediated liposome uptake, all of which were inhibited by competing P63 antibody. Incubation of A549 and type II cells with SP-A also increased P63 localization on the PM. The phosphatidylinositol 3-kinase (PI3-kinase) signaling pathway was explored as a mechanism for the transport of this endoplasmic reticulum (ER)-resident protein to the PM. Treatment with LY-294002, an inhibitor of the PI3-kinase pathway, prevented the SP-A-induced PM enrichment of P63. Exposure of pneumocytes to SP-A or cAMP activated Akt (PKB). Blocking either PI3-kinase or Akt altered SP-A-mediated lipid turnover. The data demonstrate an important role for the PI3-kinase-Akt pathway in intracellular transport of P63. The results add to the growing body of evidence that P63 is critical for SP-A receptor-mediated interactions with type II pneumocytes and the resultant regulation of surfactant turnover.
Asunto(s)
Células Epiteliales Alveolares/metabolismo , Proteínas de la Membrana/metabolismo , Fosfatidilinositol 3-Quinasa/metabolismo , Proteína A Asociada a Surfactante Pulmonar/metabolismo , Receptores de Superficie Celular/metabolismo , Transducción de Señal/fisiología , Células Epiteliales Alveolares/citología , Animales , Membrana Celular/metabolismo , Células Cultivadas , AMP Cíclico/metabolismo , Activación Enzimática , Inhibidores Enzimáticos/metabolismo , Humanos , Liposomas/química , Liposomas/metabolismo , Proteínas de la Membrana/genética , Proteínas Proto-Oncogénicas c-akt/metabolismo , Ratas , Receptores de Superficie Celular/genéticaRESUMEN
Receptor-mediated signaling is commonly associated with multiple functions, including the production of reactive oxygen species. However, whether mitochondrion-derived superoxide (mROS) contributes directly to physiological signaling is controversial. Here we demonstrate a previously unknown mechanism in which physiologic Ca(2+)-evoked mROS production plays a pivotal role in endothelial cell (EC) activation and leukocyte firm adhesion. G protein-coupled receptor (GPCR) and tyrosine kinase-mediated inositol 1,4,5-trisphosphate-dependent mitochondrial Ca(2+) uptake resulted in NADPH oxidase-independent mROS production. However, GPCR-linked mROS production did not alter mitochondrial function or trigger cell death but rather contributed to activation of NF-kappaB and leukocyte adhesion via the EC induction of intercellular adhesion molecule 1. Dismutation of mROS by manganese superoxide dismutase overexpression and a cell-permeative superoxide dismutase mimetic ablated NF-kappaB transcriptional activity and facilitated leukocyte detachment from the endothelium under simulated circulation following GPCR- but not cytokine-induced activation. These results demonstrate that mROS is the downstream effector molecule that translates receptor-mediated Ca(2+) signals into proinflammatory signaling and leukocyte/EC firm adhesion.
Asunto(s)
Calcio/metabolismo , Células Endoteliales/citología , Leucocitos/citología , Mitocondrias/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Animales , Señalización del Calcio/efectos de los fármacos , Adhesión Celular/efectos de los fármacos , Pollos , Células Endoteliales/efectos de los fármacos , Células Endoteliales/ultraestructura , Humanos , Inflamación , Receptores de Inositol 1,4,5-Trifosfato/metabolismo , Molécula 1 de Adhesión Intercelular/metabolismo , Leucocitos/efectos de los fármacos , Ratones , Mitocondrias/enzimología , Mitocondrias/patología , Mitocondrias/ultraestructura , NADPH Oxidasas/metabolismo , FN-kappa B/metabolismo , Receptor PAR-1/metabolismo , Superóxidos/metabolismo , Trombina/farmacologíaRESUMEN
Prdx6 (peroxiredoxin 6), a bifunctional protein with both GSH peroxidase and PLA(2) (phospholipase A(2)) [aiPLA(2) (acidic calcium-independent PLA(2))] activities, is responsible for the metabolism of lung surfactant phospholipids. We propose that the aiPLA(2) activity of the enzyme is regulated through phosphorylation. Incubation of isolated rat alveolar type II cells (AECII) with PMA, a PKC (protein kinase C) agonist, had no effect on Prdx6 expression but led to approximately 75% increase in aiPLA(2) activity that was abolished by pretreatment of cells with the MAPK (mitogen-activated protein kinase) inhibitors, SB202190 or PD98059. Prdx6 phosphorylation after incubation of AECII with PMA was demonstrated by autoradiography after immunoprecipitation with either anti-phosphothreonine o-phosphoserine antibodies. in vitro, several active isoforms of ERK (extracellular-signal-regulated kinase) and p38 phosphorylated Prdx6, resulting in an 11-fold increase in aiPLA(2) activity. The increased activity was calcium-independent and was abolished by the aiPLA(2) inhibitors, surfactant protein A and hexadecyl-3-trifluorethylglycero-sn-2-phospho-methanol (MJ33). The peroxidase activity of Prdx6 was unaffected by phosphorylation. Mass spectroscopic analysis of in vitro phosphorylated Prdx6 showed a unique phosphorylation site at Thr-177 and mutation of this residue abolished protein phosphorylation and the increase in MAPK-mediated activity. These results show that the MAPKs can mediate phosphorylation of Prdx6 at Thr-177 with a consequent marked increase in its aiPLA(2) activity.
Asunto(s)
Proteínas Quinasas Activadas por Mitógenos/metabolismo , Peroxiredoxina VI/metabolismo , Fosfolipasas A2/metabolismo , Animales , Extractos Celulares , Electroforesis en Gel Bidimensional , Endocitosis/efectos de los fármacos , Humanos , Inmunoprecipitación , Proteínas Quinasas Activadas por Mitógenos/antagonistas & inhibidores , Mutación/genética , Fosforilación/efectos de los fármacos , Proteína Quinasa C/antagonistas & inhibidores , Inhibidores de Proteínas Quinasas/farmacología , Procesamiento Proteico-Postraduccional/efectos de los fármacos , Alveolos Pulmonares/citología , Alveolos Pulmonares/efectos de los fármacos , Alveolos Pulmonares/enzimología , Ratas , Ratas Sprague-Dawley , Acetato de Tetradecanoilforbol/farmacología , Treonina/metabolismoRESUMEN
Peroxiredoxin 6 (Prdx6) differs from other mammalian peroxiredoxins both in its ability to reduce phospholipid hydroperoxides at neutral pH and in having phospholipase A(2) (PLA(2)) activity that is maximal at acidic pH. We previously showed an active site C47 for peroxidase activity and a catalytic triad S32-H26-D140 necessary for binding of phospholipid and PLA(2) activity. This study evaluated binding of reduced and oxidized phospholipid hydroperoxide to Prdx6 at cytosolic pH. Incubation of recombinant Prdx6 with 1-palmitoyl-2-linoleoyl-sn-glycero-3-phosphocholine hydroperoxide (PLPCOOH) resulted in peroxidase activity, cys47 oxidation as detected with Prdx6-SO2(3)) antibody, and a marked shift in the Prdx6 melting temperature by circular dichroism analysis indicating that PLPCOOH is a specific substrate for Prdx6. Preferential Prdx6 binding to oxidized liposomes was detected by changes in DNS-PE or bis-Pyr fluorescence and by ultrafiltration. Site-specific mutation of S32 or H26 in Prdx6 abolished binding while D140 mutation had no effect. Treatment of A549 cells with peroxides led to lipid peroxidation and translocation of Prdx6 from the cytosol to the cell membrane. Thus, the pH specificity for the two enzymatic activities of Prdx6 can be explained by the differential binding kinetics of the protein; Prdx6 binds to reduced phospholipid at acidic pH but at cytosolic pH binds only phospholipid that is oxidized compatible with a role for Prdx6 in the repair of peroxidized cell membranes.
Asunto(s)
Peroxidasas/metabolismo , Peroxiredoxina VI/metabolismo , Fosfolipasas A2/metabolismo , Animales , Línea Celular , Dicroismo Circular , Electroforesis en Gel de Poliacrilamida , Inhibidores Enzimáticos/farmacología , Humanos , Liposomas , Oxidación-Reducción , Unión Proteica , Ratas , Espectrometría de Fluorescencia , Especificidad por SustratoRESUMEN
PURPOSE: Neuron-specific enolase (NSE) concentrations are prognostic following traumatic and anoxic brain injury and may provide a method to quantify neuronal injury in other populations. We determined the association of admission plasma NSE concentrations with mortality and delirium in critically ill septic patients. METHODS: We performed a retrospective analysis of 124 patients from a larger sepsis cohort. Plasma NSE was measured in the earliest blood draw at intensive care unit admission. Primary outcomes were 30-day mortality and intensive care unit delirium determined by chart review. RESULTS: Sixty-one patients (49.2%) died within 30 days, and delirium developed in 34 (31.5%) of the 108 patients who survived at least 24 hours and were not persistently comatose. Each doubling of the NSE concentration was associated with a 7.3% (95% confidence interval [CI] 2.5-12.0, P= .003) increased risk of 30-day mortality and a 5.2% (95% CI 3.2-7.2, P< .001) increased risk of delirium. An NSE concentration >12.5 µg/L was independently associated with a 23.3% (95% CI 6.7-39.9, P= .006) increased risk of 30-day mortality and a 29.3% (95% CI 8.8-49.8, P= .005) increased risk of delirium. CONCLUSIONS: Higher plasma NSE concentrations were associated with mortality and delirium in critically ill septic patients, suggesting that NSE may have utility as a marker of neuronal injury in sepsis.
Asunto(s)
Biomarcadores/sangre , Delirio/mortalidad , Fosfopiruvato Hidratasa/sangre , Sepsis , Adulto , Anciano , Estudios de Cohortes , Cuidados Críticos , Enfermedad Crítica/mortalidad , Delirio/sangre , Femenino , Escala de Coma de Glasgow , Humanos , Unidades de Cuidados Intensivos , Masculino , Persona de Mediana Edad , Admisión del Paciente , Pennsylvania , Valor Predictivo de las Pruebas , Pronóstico , Estudios RetrospectivosRESUMEN
Peroxiredoxin 6 (Prdx6) is a unique antioxidant enzyme that can reduce phospholipid and other hydroperoxides. A549 cells, a human lung-derived cell line, express both Prdx6 and Nrf2, a transcription factor that binds to antioxidant-response elements (AREs) and promotes expression of antioxidant genes. Treatment of A549 cells with 500 microM H(2)O(2) increased Prdx6 mRNA levels 2.5-fold, whereas treatment with 400 microM H(2)O(2) or 200 microM tert-butylhydroquinone (t-BHQ) triggered a corresponding 2.5-fold increase in reporter gene activity in A549 cells transfected with the pSEAP2:Basic vector (BD Bioscience), containing 1524 nucleotides of the human Prdx6 promoter region. Deletion of a consensus ARE sequence present between positions 357 and 349 before the start of transcription led to a striking decrease in both basal and H(2)O(2)- or t-BHQ-induced activation in A549 cells and H(2)O(2)-induced activation in primary rat alveolar type II cells. Cotransfection with Nrf2 stimulated the Prdx6 promoter in an ARE-dependent manner, whereas it was negatively regulated by Nrf3. siRNA targeting Nrf2 down-regulated reporter gene expression, whereas siRNA targeting the Nrf2 repressor, Keap1, up-regulated it. Binding of Nrf2 to the ARE sequence in chromatin was confirmed by PCR after chromatin immunoprecipitation. These data demonstrate that the ARE within the Prdx6 promoter is a key regulator of basal transcription of the Prdx6 gene and of its inducibility under conditions of oxidative stress.
Asunto(s)
Antioxidantes/metabolismo , Células Epiteliales/fisiología , Estrés Oxidativo/fisiología , Peroxiredoxina VI/metabolismo , Activación Transcripcional/fisiología , Animales , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/genética , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/metabolismo , Línea Celular , Ensamble y Desensamble de Cromatina , Inducción Enzimática/efectos de los fármacos , Inducción Enzimática/genética , Células Epiteliales/citología , Retroalimentación Fisiológica , Humanos , Peróxido de Hidrógeno/farmacología , Hidroquinonas/farmacología , Péptidos y Proteínas de Señalización Intracelular/genética , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Proteína 1 Asociada A ECH Tipo Kelch , Pulmón/citología , Masculino , Factor 2 Relacionado con NF-E2/genética , Factor 2 Relacionado con NF-E2/metabolismo , Peroxiredoxina VI/genética , Regiones Promotoras Genéticas , Unión Proteica/efectos de los fármacos , Unión Proteica/genética , ARN Interferente Pequeño/genética , Ratas , Ratas Sprague-Dawley , Elementos de Respuesta/efectos de los fármacos , Elementos de Respuesta/genética , Eliminación de Secuencia , Activación Transcripcional/efectos de los fármacos , TransfecciónRESUMEN
We have recently described a putative receptor for lung surfactant protein-A (SP-A) on rat type II pneumocytes. The receptor, P63, is a 63-kDa type II transmembrane protein. Coincubation of type II cells with P63 antibody (Ab) reversed the inhibitory effect of SP-A on secretagogue-stimulated surfactant secretion from type II cells. To further characterize SP-A interactions with P63, we expressed recombinant P63 protein in Escherichia coli and generated antibodies to P63. Immunogold electron microscopy confirmed endoplasmic reticulum and plasma membrane localization of P63 in type II cells with prominent labeling of microvilli. Binding characteristics of iodinated SP-A to type II cells in the presence of P63 Ab were determined. Binding (4 degrees C, 1 h) of (125)I-SP-A to type II cells demonstrated both specific (calcium-dependent) and nonspecific (calcium-independent) components. Ab to P63 protein blocked the specific binding of (125)I-SP-A to type II cells and did not change the nonspecific SP-A association. A549 cells, a pneumocyte model cell line, expressed substantial levels of P63 and demonstrated specific binding of (125)I-SP-A that was inhibited by the P63 Ab. The secretagogue (cAMP)-stimulated increase in calcium-dependent binding of SP-A to type II cells was blocked by the presence of P63 Ab. Transfection of type II cells with small interfering RNA to P63 reduced P63 protein expression, attenuated P63-specific SP-A binding, and reversed the ability of SP-A to prevent surfactant secretion from the cells. Our results further substantiate the role of P63 as an SP-A receptor protein localized on the surface of lung type II cells.
Asunto(s)
Pulmón/fisiología , Proteínas de la Membrana/fisiología , Proteína A Asociada a Surfactante Pulmonar/metabolismo , Adenocarcinoma , Animales , Línea Celular Tumoral , Humanos , Neoplasias Pulmonares , Proteínas de la Membrana/genética , Microscopía Confocal , Microscopía Inmunoelectrónica , Plásmidos , ARN Interferente Pequeño/genética , Ratas , Proteínas Recombinantes/metabolismoRESUMEN
Surfactant protein A (SP-A) binds to alveolar type II cells through a specific high-affinity cell membrane receptor, although the molecular nature of this receptor is unclear. In the present study, we have identified and characterized an SP-A cell surface binding protein by utilizing two chemical cross-linkers: profound sulfo-SBED protein-protein interaction reagent and dithiobis(succinimidylpropionate) (DSP). Sulfo-SBED-biotinylated SP-A was cross-linked to the plasma membranes isolated from rat type II cells, and the biotin label was transferred from SP-A to its receptor by reduction. The biotinylated SP-A-binding protein was identified on blots by using streptavidin-labeled horseradish peroxidase. By using DSP, we cross-linked SP-A to intact mouse type II cells and immunoprecipitated the SP-A-receptor complex using anti-SP-A antibody. Both of the cross-linking approaches showed a major band of 63 kDa under reduced conditions that was identified as the rat homolog of the human type II transmembrane protein p63 (CKAP4/ERGIC-63/CLIMP-63) by matrix-assisted laser desorption ionization and nanoelectrospray tandem mass spectrometry of tryptic fragments. Thereafter, we confirmed the presence of p63 protein in the cross-linked SP-A-receptor complex by immunoprobing with p63 antibody. Coimmunoprecipitation experiments and functional assays confirmed specific interaction between SP-A and p63. Antibody to p63 could block SP-A-mediated inhibition of ATP-stimulated phospholipid secretion. Both intracellular and membrane localized pools of p63 were detected on type II cells by immunofluorescence and immunobloting. p63 colocalized with SP-A in early endosomes. Thus p63 closely interacts with SP-A and may play a role in the trafficking or the biological function of the surfactant protein.
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Proteínas de la Membrana/química , Proteínas de la Membrana/metabolismo , Alveolos Pulmonares/metabolismo , Receptores de Superficie Celular/química , Receptores de Superficie Celular/metabolismo , Secuencia de Aminoácidos , Animales , Células Cultivadas , Inmunoprecipitación , Pulmón/citología , Pulmón/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Datos de Secuencia Molecular , Unión Proteica , Proteína A Asociada a Surfactante Pulmonar/metabolismo , Ratas , Ratas Sprague-DawleyRESUMEN
In severe asthma, cytokines and growth factors contribute to the proliferation of smooth muscle cells and blood vessels, and to the increased extracellular matrix deposition that constitutes the process of airway remodeling. Vascular endothelial growth factor (VEGF), which regulates vascular permeability and angiogenesis, also modulates the function of nonendothelial cell types. In this study, we demonstrate that VEGF induces fibronectin secretion by human airway smooth muscle (ASM) cells. In addition, stimulation of ASM with VEGF activates ERK, but not p38MAPK, and fibronectin secretion is ERK dependent. Both ERK activation and fibronectin secretion appear to be mediated through the VEGF receptor flt-1, as evidenced by the effects of the flt-1-specific ligand placenta growth factor. Finally, we demonstrate that ASM cells constitutively secrete VEGF, which is increased in response to PDGF, transforming growth factor-beta, IL-1beta, and PGE(2). We conclude that ASM-derived VEGF, through modulation of the extracellular matrix, may play an important role in airway remodeling seen in asthma.