RESUMEN
BACKGROUND: Recent studies have demonstrated high levels of vascular endothelial growth factor (VEGF) in exudative pleural effusions and a possible etiologic role. The factors regulating VEGF accumulation in the pleural space are unknown. Transforming growth factor (TGF)-beta is a potent stimulator of VEGF expression in vitro. We hypothesized that TGF-beta induces VEGF production in pleural tissues, and, hence, the pleural fluid VEGF levels should correlate with the levels of TGF-beta in pleural fluid of different etiologies. METHODS: Seventy pleural fluid samples were analyzed. These included 20 malignant, 13 post-coronary artery bypass grafting (CABG), 8 parapneumonic, 11 miscellaneous exudative, and 18 congestive heart failure (CHF) pleural effusions. RESULTS: Pleural fluid VEGF levels showed good correlation with those of TGF-beta(1) (r = 0.58; p < 0. 0001), TGF-beta(2) (r = 0.43; p < 0.001), and lactate dehydrogenase (r = 0.65; p < 0.001). The levels of TGF-beta(1) and TGF-beta(2) also were correlated (r = 0.60; p < 0.0001). The median levels of TGF-beta(1) (2,480 pg/mL) and TGF-beta(2) (266 pg/mL) in the CHF group were significantly lower than those in the malignant (TGF-beta(1), 4,902 pg/mL; TGF-beta(2), 428 pg/mL), post-CABG (TGF-beta(1), 5,456 pg/mL; TGF-beta(2), 377 pg/mL), parapneumonic (TGF-beta(1), 5,024 pg/mL; TGF-beta(2), 464 pg/mL), and miscellaneous exudate groups (TGF-beta(1), 7,690 pg/mL; TGF-beta(2), 369 pg/mL). There was no significant difference in TGF-beta(1) and TGF-beta(2) levels among the four exudate groups. CONCLUSIONS: VEGF levels in pleural effusions are significantly correlated with the levels of TGF-beta(1) and beta(2) isoforms. VEGF, TGF-beta(1), and TGF-beta(2) levels were all higher in exudative effusions than in effusions secondary to CHF.
Asunto(s)
Factores de Crecimiento Endotelial/análisis , Linfocinas/análisis , Derrame Pleural/química , Factor de Crecimiento Transformador beta/análisis , Humanos , L-Lactato Deshidrogenasa/análisis , Derrame Pleural Maligno/química , Isoformas de Proteínas , Factor A de Crecimiento Endotelial Vascular , Factores de Crecimiento Endotelial VascularRESUMEN
STUDY OBJECTIVES: The purpose of this study was to analyze the relationship of the pleural fluid vascular endothelial growth factor (VEGF) level with the diagnostic category and with the pleural fluid characteristics in a group of 70 patients. DESIGN: The VEGF levels of consecutive patients undergoing therapeutic thoracentesis were determined with an enzyme-linked immunosorbent assay. SETTING: University-affiliated tertiary care center. RESULTS: The median level of pleural fluid VEGF in the patients with congestive heart failure (150 pg/mL) was significantly (p < 0.05) lower than the median level in the patients with coronary artery bypass grafting (357 pg/mL), which in turn was significantly lower (p < 0.05) than the median levels in the patients with malignancy (1,097 pg/mL). The overlap between groups, however, limits the diagnostic usefulness of pleural fluid VEGF levels. The VEGF level was most closely correlated with the lactate dehydrogenase level (r = 0.42, p < 0.001) and was also significantly correlated with the total pleural fluid protein level. The median VEGF levels in the pleural fluid of patients with breast cancer were significantly lower (p = 0.017) than in those with lung cancer. The VEGF level was very high (3,294 pg/mL) in the one patient with pulmonary embolism. CONCLUSIONS: We conclude that the VEGF levels in pleural fluid differ significantly from one diagnostic category to another with the highest median levels occurring in patients with malignant pleural effusions. We speculate that VEGF may be responsible for the pleural fluid accumulation in at least some situations.
Asunto(s)
Factores de Crecimiento Endotelial/análisis , Linfocinas/análisis , Derrame Pleural/química , Neoplasias de la Mama/metabolismo , Puente de Arteria Coronaria , Ensayo de Inmunoadsorción Enzimática , Femenino , Insuficiencia Cardíaca/metabolismo , Humanos , L-Lactato Deshidrogenasa/análisis , Neoplasias Pulmonares/metabolismo , Derrame Pleural/etiología , Derrame Pleural Maligno/química , Proteínas/análisis , Embolia Pulmonar/metabolismo , Factor A de Crecimiento Endotelial Vascular , Factores de Crecimiento Endotelial VascularRESUMEN
Exposure to high levels of inspired oxygen leads to respiratory failure and death in many animal models. Endothelial cell death is an early finding, before the onset of respiratory failure. Vascular endothelial growth factor (VEGF) is highly expressed in the lungs of adult animals. In the present study, adult Sprague-Dawley rats were exposed to >95% FiO2 for 24 or 48 hours. Northern blot analysis revealed a marked reduction in VEGF mRNA abundance by 24 hours, which decreased to less than 50% of control by 48 hours. In situ hybridization revealed that VEGF was highly expressed in distal airway epithelial cells in controls but disappeared in the oxygen-exposed animals. Immunohistochemistry and Western blot analyses demonstrated that VEGF protein was decreased at 48 hours. TUNEL staining demonstrated the presence of apoptotic cells coincident with the decline in VEGF. Abundance of VEGF receptor mRNAs (Flt-1 and KDR/Flk) decreased in the late time points of the study (48 hours), possibly secondary to the loss of endothelial cells. We speculate that VEGF functions as a survival factor in the normal adult rat lung, and its loss during hyperoxia contributes to the pathophysiology of oxygen-induced lung damage.
Asunto(s)
Factores de Crecimiento Endotelial/metabolismo , Hiperoxia/metabolismo , Pulmón/metabolismo , Linfocinas/metabolismo , Proteínas Tirosina Quinasas Receptoras/metabolismo , Receptores de Factores de Crecimiento/metabolismo , Animales , Apoptosis/fisiología , Factores de Crecimiento Endotelial/genética , Pulmón/citología , Pulmón/fisiología , Linfocinas/genética , Masculino , Proteínas Proto-Oncogénicas/genética , ARN Mensajero/metabolismo , Ratas , Ratas Sprague-Dawley , Proteínas Tirosina Quinasas Receptoras/genética , Receptores de Factores de Crecimiento/genética , Receptores de Factores de Crecimiento Endotelial Vascular , Factor A de Crecimiento Endotelial Vascular , Receptor 1 de Factores de Crecimiento Endotelial Vascular , Factores de Crecimiento Endotelial VascularAsunto(s)
Factores de Crecimiento Endotelial/metabolismo , Hiperoxia/metabolismo , Pulmón/metabolismo , Linfocinas/metabolismo , Animales , Supervivencia Celular , Células Cultivadas , Endotelio Vascular/fisiología , ARN Mensajero/metabolismo , Ratas , Ratas Sprague-Dawley , Factores de Tiempo , Factor A de Crecimiento Endotelial Vascular , Factores de Crecimiento Endotelial VascularRESUMEN
Chronic lung disease in neonates results from both lung injury and inadequate repair processes. Little is known about the growth factors involved in lung injury and repair, but vascular endothelial growth factor (VEGF) has recently been reported in several animal models of lung injury. VEGF is an endothelial cell-specific mitogen, which is also known as vascular permeability factor because of its ability to induce vascular leak in some tissues. Chronic lung disease is complicated by increased vascular permeability, which can be improved by avoidance of hypoxia and in some cases by dexamethasone therapy. In many cells, hypoxia stimulates VEGF expression. Also, in some cases, dexamethasone blocks VEGF expression. This study examined the role of hypoxia and dexamethasone in regulating the expression of VEGF in pulmonary artery smooth muscle cells. An ovine VEGF cDNA fragment (453 bp) was cloned and found to be highly homologous to known human sequences for VEGF165. Sheep pulmonary artery smooth muscle cells were cultured and exposed to room air, hypoxia, and dexamethasone, alone or in combination for 6 h. At baseline these cells expressed VEGF mRNA at approximately 3.9 kb. The half-life of VEGF mRNA in the smooth muscle cells was 171 min, more than 3-fold longer than previous reports for epithelial cells. Exposure to hypoxia caused a 3-fold increase in mRNA abundance, primarily through transcriptional up-regulation. Dexamethasone blocked the hypoxia-induced increase in VEGF mRNA. The results demonstrate that hypoxia and dexamethasone are regulators of VEGF expression in ovine pulmonary artery smooth muscle cells. It is not known whether VEGF derived from these cells is involved in lung injury and/or normal homeostatsis.
Asunto(s)
Dexametasona/farmacología , Factores de Crecimiento Endotelial/genética , Pulmón/efectos de los fármacos , Linfocinas/genética , Músculo Liso Vascular/efectos de los fármacos , Secuencia de Aminoácidos , Animales , Hipoxia de la Célula/efectos de los fármacos , Células Cultivadas , Clonación Molecular , Factores de Crecimiento Endotelial/biosíntesis , Humanos , Concentración de Iones de Hidrógeno , Pulmón/irrigación sanguínea , Linfocinas/biosíntesis , Datos de Secuencia Molecular , Músculo Liso Vascular/citología , Músculo Liso Vascular/metabolismo , Reacción en Cadena de la Polimerasa/métodos , ARN Mensajero/biosíntesis , Ratas , Homología de Secuencia de Aminoácido , Ovinos , Transcripción Genética , Factor A de Crecimiento Endotelial Vascular , Factores de Crecimiento Endotelial VascularRESUMEN
While it is well known that chronic pulmonary hypertension is accompanied by characteristic structural changes in the pulmonary arteries, it is becoming increasingly apparent that the remodeling process also involves the venous side of the circulation. The present paper utilizes a sheep model of sustained pulmonary hypertension induced by continuous air embolization (CAE) into the pulmonary arterial circulation to examine the structure of the pulmonary veins and bronchial vasculature. Morphometric techniques were applied to the pulmonary veins and bronchial vessels following distension of the venous circulation with a barium-sulfate gelatin mixture; this route of filling also resulted in distension of the bronchial vessels. Four and 12 days of CAE resulted in a significant increase in the proportion of muscular pulmonary veins (e.g., percent muscular veins < 75 microns following 12 days CAE = 17.7 +/- 6.9; controls = 0), an approximate doubling in percent venous medial thickness, and a 50% reduction in number of barium-filled peripheral vessels. Examination of the bronchial circulation revealed a striking increase in volume due both to a 50% increase in vessel diameter and a threefold increase in number of small vessels (p < .05). The authors conclude that CAE-induced chronic pulmonary hypertension is associated with remodeling of both the pulmonary veins and bronchial circulation as well as the pulmonary arteries. The mechanisms for these structural alterations are not certain, but may include local release of vasoactive and inflammatory mediators and an increase in bronchopulmonary anastomoses.
Asunto(s)
Bronquios/irrigación sanguínea , Hipertensión Pulmonar/fisiopatología , Venas Pulmonares/anatomía & histología , Venas Pulmonares/fisiopatología , Animales , Bario , Modelos Animales de Enfermedad , Embolia Aérea , Hipertensión Pulmonar/etiología , Alveolos Pulmonares/citología , Circulación Pulmonar/fisiología , Ovinos , Túnica Íntima/anatomía & histología , Túnica Íntima/fisiopatologíaRESUMEN
In full-term newborns, permanent closure of the ductus arteriosus is associated with the formation of a neointima that is characterized by extracellular matrix deposition and smooth muscle cell migration. Transforming growth factor-beta (TGF-beta), a potent modulator of extracellular matrix deposition and smooth muscle cell migration, has been found to play a role in the remodeling associated with several forms of vascular disease. We examined the protein and mRNA expression of the three mammalian isoforms of TGF-beta (TGF-beta1, TGF-beta2, and TGF-beta3) during ductus arteriosus closure in full-term lambs. We found that the temporal changes and cellular localization of the proteins and mRNAs of all three TGF-beta isoforms were similar. TGF-beta proteins and mRNAs were present in very low levels in the late-gestation fetal ductus. Within 24 h of delivery, there was enhanced expression of TGF-beta in the newly forming neointima and outer muscle media; this continued to increase over the next 10 d. Increased expression of TGF-beta in the inner muscle media and adventitia lagged behind that of the neointima and outer muscle media. TGF-beta was not found in the luminal endothelial cells at any time. In contrast to the pattern described above, the appearance of TGF-beta protein differed from that of mRNA in the vasa vasorum of the ductus wall. After delivery, there was an increase in TGF-beta immunoreactivity in the smooth muscle cell layers of the vasa vasorum without any concurrent mRNA expression. The appearance of TGF-beta at the time of ductus closure suggests an important role for this growth factor in the reorganization of the ductus wall after birth.
Asunto(s)
Conducto Arterial/metabolismo , Factor de Crecimiento Transformador beta/metabolismo , Animales , Conducto Arterial/embriología , Conducto Arterial/ultraestructura , Expresión Génica , Técnicas para Inmunoenzimas , Hibridación in Situ , ARN Mensajero/metabolismo , Ovinos , Factor de Crecimiento Transformador beta/genéticaRESUMEN
Continuous air embolization (CAE) into the pulmonary arterial circulation of sheep results in functional and structural changes of chronic pulmonary hypertension. Release of elastin peptides into lung lymph during CAE and attenuation of CAE-induced pulmonary hypertension by neutrophil depletion suggest that neutrophil elastase may contribute to these changes. To investigate this notion, we treated awake sheep with a potent neutrophil elastase inhibitor, recombinant secretory leukoprotease inhibitor (SLPI) (100 mg/day by aerosol), during 12 days of CAE (CAE+SLPI; n = 7). Controls included sheep receiving CAE + vehicle (VEH) (n = 6), VEH alone (n = 3), and SLPI alone (n = 3). SLPI significantly attenuated the CAE-induced increases in lung lymph flow (day 8; 2.3 +/- 0.5 vs. 5.6 +/- 1.7 ml/15 min), protein clearance (day 8; 1.36 +/- 0.32 vs. 3.08 +/- 0.84 ml/15 min), and elastin peptide concentration (day 8; 243 +/- 41 vs. 398 +/- 44 ng/ml). SLPI delayed the onset of sustained pulmonary hypertension from day 8 to day 12. Both CAE groups showed similar structural changes in the pulmonary arteries. SLPI was well tolerated in control sheep and did not affect hemodynamics or structure. We conclude that serine proteases may contribute to the early initiation of chronic pulmonary hypertension but do not play a striking role in its eventual development.
Asunto(s)
Embolia Aérea/fisiopatología , Lesión Pulmonar , Proteínas/farmacología , Inhibidores de Serina Proteinasa/farmacología , Aerosoles , Animales , Permeabilidad Capilar/fisiología , Elastina/sangre , Elastina/metabolismo , Embolia Aérea/patología , Hemodinámica/efectos de los fármacos , Hemodinámica/fisiología , Humanos , Hipertensión Pulmonar/patología , Hipertensión Pulmonar/fisiopatología , Hipertrofia Ventricular Derecha/patología , Hipertrofia Ventricular Derecha/fisiopatología , Pulmón/patología , Pulmón/fisiopatología , Linfa/efectos de los fármacos , Linfa/metabolismo , Proteínas Inhibidoras de Proteinasas Secretoras , Proteínas/administración & dosificación , Circulación Pulmonar/fisiología , Intercambio Gaseoso Pulmonar/efectos de los fármacos , Intercambio Gaseoso Pulmonar/fisiología , Proteínas Recombinantes/farmacología , Inhibidor Secretorio de Peptidasas Leucocitarias , Inhibidores de Serina Proteinasa/administración & dosificación , Ovinos , Resistencia Vascular/efectos de los fármacosRESUMEN
A number of growth factors have been identified that participate in lung growth and repair. The early stages of the repair cascade are important in preventing the later development of fibrosis. Both transforming growth factor-beta and basic fibroblast growth factor can have beneficial effects when given early in some injury models. Keratinocyte growth factor stimulates type II cell hyperplasia in vitro but has not yet been studied in a lung injury model. Excessive production of growth factors such as transforming growth factor-alpha and transforming growth factor-beta can lead to fibrosis. Granulocyte-macrophage colony-stimulating factor is implicated in asthma, but now that knockout mice have been shown to have a histologic picture similar to pulmonary alveolar proteinosis, a new role for this factor in pulmonary disease has been suggested. Increasing our understanding of the diverse actions and interactions of growth factors in the lung will bring us closer to therapeutic interventions that can prevent some chronic lung diseases.
Asunto(s)
Sustancias de Crecimiento/fisiología , Enfermedades Pulmonares/prevención & control , Pulmón/patología , Factor de Crecimiento Epidérmico/fisiología , Factor 10 de Crecimiento de Fibroblastos , Factor 7 de Crecimiento de Fibroblastos , Factores de Crecimiento de Fibroblastos/fisiología , Factor Estimulante de Colonias de Granulocitos y Macrófagos/fisiología , Humanos , Pulmón/metabolismo , Factor de Crecimiento Derivado de Plaquetas/fisiología , Factor de Crecimiento Transformador alfa/fisiología , Factor de Crecimiento Transformador beta/fisiologíaRESUMEN
Transforming growth factor-beta (TGF-beta) has been suggested as one of the mediators of vascular remodeling in chronic pulmonary hypertension. We have previously shown a transient early increase in TGF-beta levels in lung lymph during the development of sustained pulmonary hypertension in a sheep model (12 days of air embolization). The present study examines expression and cellular localization of mRNA and protein of the three mammalian isoforms of TGF-beta in lung biopsy tissue taken during the development of pulmonary hypertension (0, 1, 4, 8, and 12 days of embolization). In control tissue, immunohistochemical techniques localized each of the TGF-beta proteins in an identical pattern in large preacinar airways--bronchial epithelium and subepithelial cells--and in the medial wall of muscular vessels; no protein was detected in intraacinar regions. Following air embolization, immunoreactivity appeared in peripheral lung. At day 1, immunoreactivity for TGF-beta 1 and TGF-beta 3 proteins was seen in edema fluid, in perivascular cells associated with nonmuscular intraacinar arteries, and in alveolar walls; no increased immunoreactivity was detected for TGF-beta 2. After 4, 8, and 12 days of embolization, immunoreactivity for all three TGF-beta proteins was associated with newly muscularized intraacinar arteries. With in situ hybridization, the three TGF-beta mRNAs co-localized in lung tissue from both control and air-embolized animals. In control tissue, hybridization was seen around preacinar airways and muscular vessels; no hybridization seen in intraacinar regions of the lung. After 1 day of embolization, the pattern of hybridization was similar to controls.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Embolia Aérea , Expresión Génica , Hipertensión Pulmonar/metabolismo , Pulmón/irrigación sanguínea , ARN Mensajero/metabolismo , Factor de Crecimiento Transformador beta/genética , Animales , Northern Blotting , Modelos Animales de Enfermedad , Hipertensión Pulmonar/etiología , Inmunohistoquímica , Hibridación in Situ , Pulmón/química , Pulmón/metabolismo , ARN Mensajero/análisis , Ovinos , Distribución Tisular , Factor de Crecimiento Transformador beta/análisis , Factor de Crecimiento Transformador beta/metabolismoRESUMEN
Chronic pulmonary hypertension is associated with arterial structural remodeling. Insulin-like growth factor I (IGF-I) has been proposed as one of the mediators of vascular change because of its ability to stimulate proliferation in, and elastin production by, cultured vascular smooth muscle cells. We have shown previously that 12 days of continuous air embolization into the pulmonary arterial circulation of sheep results in the functional and structural changes of chronic pulmonary hypertension. In the present study, measurements of IGF-I (by radioimmunoassay) and IGF-I binding protein activity in sheep lung lymph and plasma were made before and during the 12 days of air embolization in six sheep. Two untreated animals served as controls. Baseline lung lymph contained 23.5 +/- 3.6 ng/ml (mean +/- SEM) of IGF-I, and there was a slight increase to 36.7 +/- 9.8 on day 3, but by day 6 levels were back to baseline. The flux of IGF-I from the lung (concentration times lymph flow) increased significantly by day 2 embolization and remained elevated through day 12 (baseline = 37.2 +/- 11.1 ng/15 min; day 2 = 237.7 +/- 55.8; day 5 = 190.2 +/- 53.4; day 6 = 82.6 +/- 21.9; day 12 = 78.7 +/- 12.5). IGF-I binding protein activity was also present in lung lymph at baseline (29.6 +/- 3.0%) and was unchanged during air embolization. Plasma levels of IGF-I and plasma binding protein activity remained at baseline throughout the 12 days of embolization (71.51 +/- 34.48 ng/ml and 36.4 +/- 3.5%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Embolia Aérea/metabolismo , Hipertensión Pulmonar/etiología , Factor I del Crecimiento Similar a la Insulina/fisiología , Animales , Embolia Aérea/patología , Hipertensión Pulmonar/metabolismo , Hipertensión Pulmonar/patología , Factor I del Crecimiento Similar a la Insulina/química , Linfa/metabolismo , Unión Proteica , Proteínas/metabolismo , OvinosRESUMEN
The progression of structural changes in the pulmonary arterial bed were followed in a model of chronic pulmonary hypertension. Chronically instrumented awake sheep received continuous air embolization for 0 (controls), 1, 4, 8, or 12 days (n = 5-6/group). After the period of embolization, the lungs were removed, the pulmonary arteries were distended with barium-gelatin, and the lungs were fixed via the airways with formal-saline. Quantitative techniques were applied to sections from random blocks from the lungs of each animal. One day of embolization resulted in granulocyte sequestration in the lung interstitium and in small vessels; additionally, intraalveolar and perivascular edema was present. By 4 days, increased medial thickness, appearance of muscle in smaller arteries than normal (e.g., muscular arteries at alveolar duct level: control = 1.2 +/- 1.2%; day 4 = 22.7 +/- 7.7) and reduction in number of barium-filled intraacinar arteries was found. The arterial changes progressed in severity to day 8 and were similar at day 12. Since arterial remodelling involves increased elastin deposition, the concentration of elastin peptides was measured in lung lymph. Increased flux of elastin peptides was apparent from day 2 of embolization and continued to increase to a level 20 x baseline by day 12 (baseline 351 +/- 86 micrograms/15 min; day 12 = 6338 +/- 2999). Comparison of the onset of the structural changes with previous findings shows that the arterial remodelling parallels the onset of sustained pulmonary hypertension. The increase in lung-lymph elastin peptides by day 2 provides evidence that vascular remodelling is initiated before day 4 of embolization. The early sequestration of granulocytes and appearance of edema suggest that these may be part of the trigger to the development of the structural changes.
Asunto(s)
Vasos Sanguíneos/fisiopatología , Elastina/metabolismo , Embolia Aérea/complicaciones , Hipertensión Pulmonar/fisiopatología , Péptidos/metabolismo , Angiografía , Animales , Biopsia , Cardiomegalia/etiología , Cardiomegalia/fisiopatología , Enfermedad Crónica , Hipertensión Pulmonar/etiología , Hipertensión Pulmonar/patología , Pulmón/patología , Concentración Osmolar , Circulación Pulmonar , OvinosRESUMEN
Evidence has accumulated suggesting that the various isoforms of beta-type transforming growth factors (TGF-beta s) regulate important functions in the lung; however, the cellular source of these proteins is not well defined. Northern blot analysis of murine lung tissue demonstrates that mRNA transcripts for all three TGF-beta isoforms are found from birth through adulthood. Although the level of expression for each TGF-beta is variable during the first 2 wk post partum, all three isoforms are equal in the adult lung. Using in situ hybridization and immunohistochemical analysis, we have localized both mRNA and protein expression for all three isoforms of TGF-beta in the adult murine lung. At low magnification, immunohistochemical localization of TGF-beta proteins appears coincident in their pattern of expression with TGF-beta mRNAs in the large proximal conducting airways of the lung. However, on closer analysis, protein expression of all three TGF-beta isoforms is confined to the bronchiolar epithelium, while TGF-beta mRNA transcripts for each of the TGF-beta genes are found in smooth muscle cells and connective tissue fibroblasts lying subjacent to the epithelium. Although the levels of both TGF-beta mRNA and protein expression are high in the proximal bronchiolar tree, their signal intensities completely disappear as the terminal bronchioles progress to respiratory bronchioles. Additionally, in the lung vasculature, there is very high expression of all three TGF-beta mRNA transcripts in the smooth muscle cells of the large vessels. TGF-beta2 and TGF-beta but not TGF-beta1 proteins are expressed in these same smooth muscle cells.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Bronquios/metabolismo , Expresión Génica/fisiología , Pulmón/metabolismo , Factor de Crecimiento Transformador beta/genética , Animales , Northern Blotting , Bronquios/citología , Endotelio Vascular/citología , Endotelio Vascular/metabolismo , Femenino , Fibroblastos/metabolismo , Inmunohistoquímica , Pulmón/citología , Masculino , Ratones , Músculo Liso Vascular/metabolismo , Factor de Crecimiento Transformador beta/análisis , Factor de Crecimiento Transformador beta/biosíntesisRESUMEN
A serotonin-secreting human pancreatic carcinoid cell line (BON) is demonstrated to express transcripts for all three mammalian types of transforming growth factor beta (TGF beta 1, 2, and 3). Similarly, freshly excised carcinoid tumors from six patients were also found to express mRNA for all three of the type-beta TGFs. Medium conditioned by BON cells had detectable TGF beta activity, although most of the activity was latent as determined by radioreceptor assay with and without prior acid treatment. However, nonactivated BON-conditioned medium stimulated DNA synthesis, soft agar growth, and an increase in TGF beta 1 and fibronectin mRNA expression in AKR-2B fibroblasts. In addition, BON-conditioned medium had a potent endothelial cell growth-stimulatory activity. Since the TGF beta s inhibit growth of endothelial cells, the presence of other growth factors was suspected. TGF alpha, c-sis, and basic fibroblast growth factor transcripts were also found to be expressed by the BON carcinoid cells. These data indicate that multiple peptide growth factors may have a paracrine role in the desmoplastic reaction accompanying carcinoid tumors.
Asunto(s)
Tumor Carcinoide/metabolismo , Sustancias de Crecimiento/biosíntesis , Neoplasias Pancreáticas/metabolismo , Isomerasas de Aminoácido/biosíntesis , Northern Blotting , Proteínas Portadoras/biosíntesis , División Celular/fisiología , ADN/biosíntesis , Relación Dosis-Respuesta a Droga , Endotelio/parasitología , Fibroblastos/patología , Fibronectinas/biosíntesis , Humanos , Insulina/farmacología , Isomerasa de Peptidilprolil , Procolágeno/biosíntesis , ARN Mensajero/biosíntesis , Factores de Tiempo , Transcripción Genética , Factor de Crecimiento Transformador alfa/biosíntesis , Factor de Crecimiento Transformador beta/biosíntesisRESUMEN
Chronic pulmonary hypertension is associated with extensive structural remodeling of the pulmonary arterial bed. The structural changes in the arterial walls include increased production of extracellular matrix components and smooth muscle cell hypertrophy, changes that have been similarly induced by transforming growth factor-beta (TGF-beta) in culture. In the present study, experiments were performed to determine whether TGF-beta is present in sheep lung lymph, and whether TGF-beta levels were altered in an animal model of chronic pulmonary hypertension induced by continuous air embolization. Several standard biological assays for TGF-beta activity were used for these determinations including soft agar assays, inhibition of epithelial cell proliferation, and a TGF-beta-specific radioreceptor assay. In each case, control lung lymph contained high concentrations of TGF-beta (100 ng/ml) which required transient acidification for detection. Samples of lung lymph from hypertensive sheep showed a transient and early two- to threefold increase in concentrations of latent TGF-beta. This activity could be partially blocked by TGF-beta antibodies. These studies indicate that sheep lung lymph contains TGF-beta and that the level of TGF-beta increases early during the development of pulmonary hypertension. Thus, TGF-beta may contribute to the development of the structural changes in the pulmonary arteries that occur during the onset of chronic pulmonary hypertension.
Asunto(s)
Hipertensión Pulmonar/metabolismo , Pulmón/metabolismo , Linfa/metabolismo , Factor de Crecimiento Transformador beta/metabolismo , Animales , Bioensayo , División Celular/efectos de los fármacos , Embolia Pulmonar/metabolismo , Ensayo de Unión Radioligante , Ovinos , Timidina/metabolismo , Factor de Crecimiento Transformador beta/farmacologíaRESUMEN
Chronic pulmonary hypertension can develop in diseases associated with acute or repeated inflammation in the lungs, e.g., adult respiratory distress syndrome, chronic bronchitis. Inflammation has also been associated with some animal models of chronic pulmonary hypertension. We have previously shown that 12 days of continuous air embolization into sheep results in the functional and structural changes of chronic pulmonary hypertension. To determine whether granulocytes contribute to these changes, five sheep were granulocyte-depleted with hydroxyurea immediately before and during air embolization (AIR-PMN) and were compared with sheep receiving air embolization (AIR only). Air embolization was discontinued briefly every 4 days for monitoring of pulmonary vascular pressures and assessment of pulmonary vasoreactivity to a bolus injection of PGH2-A. After 12 days of air embolization, the lungs were removed for structural studies. AIR-PMN sheep did not develop the sustained increase in pulmonary artery pressure seen in the AIR sheep (Day 12, AIR-PMN = 20 +/- 3 cm H2O; AIR = 29 +/- 2; mean +/- SE). Similarly, the increased pulmonary pressor response to PGH2-A seen in AIR sheep was not found in the AIR-PMN group. Structural studies of the barium-injected lungs of AIR-PMN sheep revealed a twofold increase in medial thickness of normally muscular arteries and a significant increase in the percent of muscular intraacinar arteries (similar to findings in lungs from AIR sheep). The number of barium-filled arteries was increased in AIR-PMN sheep when compared with that in AIR sheep, but the number was still less than in the control sheep. We conclude that granulocytes may contribute to the functional changes of chronic pulmonary hypertension after continuous air embolization in sheep, but they do not play a role in structural changes involving pulmonary arterial smooth muscle cells and their precursors. The present data also suggest that the reduction in peripheral arterial filling is the structural alteration that contributes most to the sustained rise in pulmonary artery pressure. The data further suggest that pulmonary hypertension after air embolization may have a vasoconstrictive component that is granulocyte-dependent.
Asunto(s)
Embolia Aérea/complicaciones , Granulocitos/fisiología , Hipertensión Pulmonar/etiología , Prostaglandina H2 , Arteria Pulmonar/fisiopatología , Enfermedades de las Ovejas/etiología , Animales , Enfermedad Crónica , Embolia Aérea/sangre , Embolia Aérea/fisiopatología , Embolia Aérea/veterinaria , Granulocitos/efectos de los fármacos , Hidroxiurea/farmacología , Hipertensión Pulmonar/sangre , Hipertensión Pulmonar/fisiopatología , Hipertensión Pulmonar/veterinaria , Pulmón/patología , Linfa/fisiología , Endoperóxidos de Prostaglandinas Sintéticos/farmacología , Prostaglandinas H/farmacología , Arteria Pulmonar/efectos de los fármacos , Ovinos , Enfermedades de las Ovejas/sangre , Enfermedades de las Ovejas/fisiopatología , Factores de Tiempo , Vasoconstricción/efectos de los fármacos , Vasoconstricción/fisiologíaRESUMEN
It has been suggested that the lung has only a narrow range of structural responses to injury. For example, long-term injury results in emphysema, fibrosis, and pulmonary hypertension. Clinical and experimental models of chronic pulmonary hypertension suggest that this disease can be triggered by a number of interventions and that the structural changes in the pulmonary arterial circulation may vary depending on the stimulus. This report briefly reviews the structural changes that accompany the development of pulmonary hypertension in hypoxia- and Crotalaria-induced pulmonary hypertension in the rat and in repeated endotoxemia and continuous air embolization in the sheep. The studies indicate that of the structural changes considered characteristic of chronic pulmonary hypertension, the reduction in peripheral arterial volume as reflected by a loss in number of barium-filled arteries, extension of muscle into smaller intra-acinar arteries than normal, and reduction in external diameter of intra-acinar arteries are the changes that contribute to the sustained rise in pulmonary artery pressure. Increased medial and adventitial thickness of the normally muscular arteries seem to be secondary changes to this disease. Because the severity and range of structural changes differ between the experimental models of pulmonary hypertension, the data suggest that the lung, particularly the pulmonary arterial circulation, may have a more complex response to injury than originally suspected.
Asunto(s)
Hemodinámica , Hipertensión Pulmonar/etiología , Hipoxia/complicaciones , Animales , Enfermedad Crónica , Modelos Animales de Enfermedad , Embolia Aérea/complicaciones , Endotoxinas , Fabaceae/efectos adversos , Hipertensión Pulmonar/inducido químicamente , Hipertensión Pulmonar/fisiopatología , Plantas Medicinales , Ratas , OvinosRESUMEN
Baseline pulmonary arterial, left atrial and systemic artery pressures, cardiac output, and lung lymph flow were measured in seven chronically catheterized sheep before continuous air embolization into the pulmonary artery, which caused a two-to-threefold increase in pulmonary vascular resistance (PVR) for 12 days. Air embolization was discontinued on days 4, 8, and 12 and hemodynamic measurements were repeated. Thromboxane B2, 6-keto-PGF1 alpha, and protein were measured in lung lymph and blood plasma on days 0, 4, 8 and 12. Air embolization caused an acute, sustained rise in pulmonary artery pressure and PVR (baseline, 3.68 +/- 0.21; air, 8.32 +/- 0.62, mean +/- SE). By day 4, PVR was increased significantly even when air flow was interrupted (5.97 +/- 0.72) and by day 12, it was almost twice baseline; pulmonary artery pressure also remained elevated (baseline, 19 +/- 1 cm H2O; day 12, 31 +/- 3). Pulmonary vasoreactivity to PGH2-A was significantly increased on days 4, 8, and 12 (day 12, 285 +/- 41% of baseline response). Lung lymph flow, protein, and thromboxane clearance were increased throughout the study while clearance of 6-keto-PGF1 alpha was increased at day 4 and falling by day 8. At autopsy, morphometric analysis of the barium-injected pulmonary arterial bed revealed striking structural remodeling, extension of muscle into smaller arteries than normal: decreased peripheral arterial filling, increased medial thickness, and dilated large pulmonary arteries. Continuous air embolization into sheep causes the structural and functional changes of chronic pulmonary hypertension accompanied by increased pulmonary vasoreactivity to a bolus of PGH2-A. The abrupt onset of the sustained elevation in PVR induced by air embolization may account for the severity of the structural remodelling, particularly for the increased medial thickness.
Asunto(s)
Embolia Aérea , Hipertensión Pulmonar/patología , Arteria Pulmonar/patología , Animales , Análisis de los Gases de la Sangre , Presión Sanguínea , Modelos Animales de Enfermedad , Hemodinámica , Hipertensión Pulmonar/etiología , Hipertensión Pulmonar/fisiopatología , Pulmón/patología , Pulmón/fisiopatología , Ganglios Linfáticos/fisiopatología , Arteria Pulmonar/fisiopatología , Ovinos , Resistencia VascularRESUMEN
Using a large animal model of radiation lung injury--the sheep exposed to bilateral thoracic irradiation--we have recently shown the development of sustained pulmonary hypertension during the first 4 weeks following radiation. This is the period prior to the onset of pneumonitis and pulmonary fibrosis. In the present study, we have examined biopsy and autopsy lung tissue from these same sheep and assessed the sequential changes in lung morphology. Six unanesthetized sheep received bilateral thoracic irradiation (a total of 15 Gy); control sheep were sham irradiated. Lung biopsy tissue was taken prior to and at weekly or biweekly intervals during the 4 weeks immediately following radiation. The lungs were also removed at autopsy for light and electron microscopic examination. Our results show early (Week 1) interstitial and progressive intraalveolar edema accompanied by endothelial and epithelial injury. A gradual increase in number of interstitial mononuclear cells was evident from Week 1, both in the lung tissue and in perivascular cuffs. The number of peripheral lung interstitial mononuclear cells was twice baseline from Week 3 and included accumulation of lymphocytes, fibroblasts, and intravascular macrophages. The increased numbers of mononuclear cells paralleled the development of chronic pulmonary hypertension, perhaps suggesting their involvement in the pathogenesis of this disease. Alternatively, it may be that increased mononuclear cell number represents a stage of lung repair.