RESUMEN
INTRODUCTION: Airway surface dehydration, caused by an imbalance between secretion and absorption of ions and fluid across the epithelium and/or increased epithelial mucin secretion, impairs mucociliary clearance. Recent evidence suggests that this mechanism may be implicated in chronic obstructive pulmonary disease (COPD). However, the role of airway surface dehydration in the pathogenesis of cigarette smoke (CS)-induced COPD remains unknown. OBJECTIVE: We aimed to investigate in vivo the effect of airway surface dehydration on several CS-induced hallmarks of COPD in mice with airway-specific overexpression of the ß-subunit of the epithelial Na⺠channel (ßENaC). METHODS: ßENaC-Tg mice and wild-type (WT) littermates were exposed to air or CS for 4 or 8 weeks. Pathological hallmarks of COPD, including goblet cell metaplasia, mucin expression, pulmonary inflammation, lymphoid follicles, emphysema and airway wall remodelling were determined and lung function was measured. RESULTS: Airway surface dehydration in ßENaC-Tg mice aggravated CS-induced airway inflammation, mucin expression and destruction of alveolar walls and accelerated the formation of pulmonary lymphoid follicles. Moreover, lung function measurements demonstrated an increased compliance and total lung capacity and a lower resistance and hysteresis in ßENaC-Tg mice, compared to WT mice. CS exposure further altered lung function measurements. CONCLUSIONS: We conclude that airway surface dehydration is a risk factor that aggravates CS-induced hallmarks of COPD.
Asunto(s)
Deshidratación/patología , Enfermedad Pulmonar Obstructiva Crónica/patología , Mucosa Respiratoria/metabolismo , Contaminación por Humo de Tabaco/efectos adversos , Animales , Células Cultivadas , Deshidratación/etiología , Deshidratación/metabolismo , Canales Epiteliales de Sodio/genética , Canales Epiteliales de Sodio/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Mucinas/metabolismo , Enfermedad Pulmonar Obstructiva Crónica/metabolismo , Mucosa Respiratoria/patología , Fumar/efectos adversosRESUMEN
Nitric oxide (NO) is a gaseotransmitter, which is involved in many signaling processes in health and disease. Three enzymes generate NO from l-arginine, with citrulline formed as a by-product: neuronal NO synthase (nNOS or NOS1), endothelial NOS (eNOS or NOS3) and inducible NOS (iNOS or NOS2). NO is a ligand of soluble guanylyl cyclase (sGC), an intracellular heterodimer enzyme that catalyzes the conversion of guanosine triphosphate (GTP) to cyclic GMP (cGMP). cGMP further activates protein kinase G that eventually reduces the smooth muscle tone in bronchi or vessels. Phosphodiesterase 5 (PDE5) degrades cGMP to GMP. However, NO reacts with superoxide anion (O2(-)), leading to formation of the pro-inflammatory molecule peroxynitrite. Under physiological conditions, NO plays a homeostatic bronchoprotective role in healthy subjects. In obstructive airway diseases, NO can be beneficial by its bronchodilating effect, but could also be detrimental by the formation of peroxynitrite. Since asthma and COPD are associated with increased levels of exhaled NO, chronic inflammation and increased airway smooth muscle tone, the NO/sGC/cGMP pathway could be involved in these highly prevalent obstructive airway diseases. Here we review the involvement of NO, NO synthases, guanylyl cyclases, cGMP and phophodiesterase-5 in asthma and COPD and potential therapeutic approaches to modulate this pathway.
Asunto(s)
Asma/fisiopatología , Óxido Nítrico/metabolismo , Enfermedad Pulmonar Obstructiva Crónica/fisiopatología , Animales , GMP Cíclico/metabolismo , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 5/metabolismo , Guanilato Ciclasa/metabolismo , Humanos , Óxido Nítrico Sintasa/metabolismo , Receptores Citoplasmáticos y Nucleares/metabolismo , Transducción de Señal/fisiología , Guanilil Ciclasa Soluble , Superóxidos/metabolismoRESUMEN
BACKGROUND: Chronic obstructive pulmonary disease (COPD) arises from an interaction between genetic host factors and environmental exposures (mainly cigarette smoke (CS)). Genome Wide Association studies have demonstrated that genetic variations in the gene encoding 5-hydroxytryptamine 4 receptors (5-HT(4)R), HTR4, were associated with measures of airway obstruction and with COPD. We hypothesised that 5-HT(4) receptors, in addition to 5-HT2AR and muscarinic receptors, contribute to the pathogenesis of COPD by facilitating cholinergic bronchoconstriction. METHODS: The levels of pulmonary 5-HT(4)R mRNA were measured in CS-exposed mice by qRT-PCR. We investigated the effect of CS exposure on bronchial hyperresponsiveness (BHR) to 5-HT and evaluated the contribution of 5-HT2AR, muscarinic receptors and 5-HT(4)R in the response to 5-HT by using the corresponding antagonists and 5-HT(4)R knockout (KO) mice. RESULTS: The 5-HT(4)R mRNA levels were significantly elevated upon acute (3 days), subacute (4 weeks) and chronic (24 weeks) CS exposure. Both acute and subacute CS exposure significantly increased BHR to 5-HT. Antagonism of 5-HT2AR abolished the CS-induced BHR to 5-HT, and antagonism of muscarinic receptors significantly reduced the response to 5-HT. However, pre-treatment with GR113808, a specific 5-HT(4)R antagonist, did not alter the response to 5-HT in CS-exposed mice. Accordingly, the CS-induced BHR to 5-HT was not different between wild-type and 5-HT(4)R KO mice. CONCLUSION: CS increased the levels of 5-HT(4)R mRNA in the lungs, concomitantly with bronchial responsiveness to 5-HT. Our in vivo data using pharmacologic and genetic approaches suggest that 5-HT(4) receptors are not involved in the BHR to 5-HT in CS-exposed mice.
Asunto(s)
Hiperreactividad Bronquial/fisiopatología , Enfermedad Pulmonar Obstructiva Crónica/fisiopatología , Receptores de Serotonina 5-HT4/genética , Contaminación por Humo de Tabaco/efectos adversos , Animales , Hiperreactividad Bronquial/genética , Broncoconstricción/genética , Modelos Animales de Enfermedad , Indoles/farmacología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Enfermedad Pulmonar Obstructiva Crónica/etiología , Enfermedad Pulmonar Obstructiva Crónica/genética , ARN Mensajero/metabolismo , Receptor de Serotonina 5-HT2A/metabolismo , Receptores Muscarínicos/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Sulfonamidas/farmacologíaRESUMEN
RATIONALE: Soluble guanylyl cyclase (sGC), a cyclic guanosine 5'-monophosphate-generating enzyme, regulates smooth muscle tone and exerts antiinflammatory effects in animal models of asthma and acute lung injury. In chronic obstructive pulmonary disease (COPD), primarily caused by cigarette smoke (CS), lung inflammation persists and smooth muscle tone remains elevated, despite ample amounts of nitric oxide that could activate sGC. OBJECTIVES: To determine the expression and function of sGC in patients with COPD and in a murine model of COPD. METHODS: Expression of sGCα1, α2, and ß1 subunits was examined in lungs of never-smokers, smokers without airflow limitation, and patients with COPD; and in C57BL/6 mice after 3 days, 4 weeks, and 24 weeks of CS exposure. The functional role of sGC was investigated in vivo by measuring bronchial responsiveness to serotonin in mice using genetic and pharmacologic approaches. MEASUREMENTS AND MAIN RESULTS: Pulmonary expression of sGC, both at mRNA and protein level, was decreased in smokers without airflow limitation and in patients with COPD, and correlated with disease severity (FEV1%). In mice, exposure to CS reduced sGC, cyclic guanosine 5'-monophosphate levels, and protein kinase G activity. sGCα1(-/-) mice exposed to CS exhibited bronchial hyperresponsiveness to serotonin. Activation of sGC by BAY 58-2667 restored the sGC signaling and attenuated bronchial hyperresponsiveness in CS-exposed mice. CONCLUSIONS: Down-regulation of sGC because of CS exposure might contribute to airflow limitation in COPD.
Asunto(s)
Guanilato Ciclasa/fisiología , Enfermedad Pulmonar Obstructiva Crónica/fisiopatología , Receptores Citoplasmáticos y Nucleares/fisiología , Serotonina/fisiología , Fumar/efectos adversos , Contaminación por Humo de Tabaco/efectos adversos , Anciano , Animales , Broncoconstricción/efectos de los fármacos , Broncoconstricción/fisiología , Modelos Animales de Enfermedad , Regulación hacia Abajo , Femenino , Guanilato Ciclasa/análisis , Guanilato Ciclasa/deficiencia , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Persona de Mediana Edad , Receptores Citoplasmáticos y Nucleares/análisis , Receptores Citoplasmáticos y Nucleares/deficiencia , Mucosa Respiratoria/química , Fumar/fisiopatología , Guanilil Ciclasa SolubleRESUMEN
Chronic obstructive pulmonary disease is mainly triggered by cigarette smoke (CS) and progresses even after smoking cessation. CS induces an exaggerated influx of inflammatory cells to the bronchoalveolar space and lung parenchyma, likely resulting from a complex interplay between chemoattractants and their respective receptors. In a murine CS model of chronic obstructive pulmonary disease, we studied the importance of chemokine-like receptor ChemR23 for the induction and resolution of inflammation in CS-exposed lungs. Subacute and chronic CS exposure increased protein levels of the ChemR23 ligand and chemoattractant, chemerin, in bronchoalveolar lavage (BAL) fluid of wild-type (WT) mice. Moreover, the proinflammatory chemokines CXCL1, CCL2, and CCL20 were increased in the airways of CS-exposed WT mice, accompanied by a massive accumulation of inflammatory neutrophils and monocytes, CD11b(hi)CD103(-) and CD11b(lo)CD103(+) dendritic cells (DCs), and CD4(+) and CD8(+) T cells. The lung parenchyma of WT mice was infiltrated with inflammatory neutrophils, CD11b(hi)CD103(-) DCs, and activated CD4(+) T cells after CS exposure. CS-induced inflammation was severely attenuated in BAL fluid and lungs of ChemR23 knockout mice with regard to the induction of inflammatory chemokines and the recruitment of inflammatory cells. Neutrophils and CD8(+) T cells persisted in the airways of WT mice, as did the airway-derived conventional DCs in the mediastinal lymph nodes, for at least 14 d after smoking cessation. In the BAL fluid of CS-exposed ChemR23 knockout mice, there was a remarkable delayed accumulation of T cells 14 d after the final exposure. Our data support a role for ChemR23 in directing innate and adaptive immune cells to CS-exposed lungs.
Asunto(s)
Enfermedad Pulmonar Obstructiva Crónica/inmunología , Receptores Acoplados a Proteínas G/inmunología , Humo/efectos adversos , Animales , Líquido del Lavado Bronquioalveolar/inmunología , Separación Celular , Quimiocinas/biosíntesis , Quimiocinas/inmunología , Factores Quimiotácticos/biosíntesis , Factores Quimiotácticos/inmunología , Células Dendríticas/inmunología , Modelos Animales de Enfermedad , Ensayo de Inmunoadsorción Enzimática , Citometría de Flujo , Inmunohistoquímica , Inflamación/inmunología , Inflamación/patología , Péptidos y Proteínas de Señalización Intercelular/biosíntesis , Péptidos y Proteínas de Señalización Intercelular/inmunología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Monocitos/inmunología , Enfermedad Pulmonar Obstructiva Crónica/patología , Receptores de Quimiocina , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , NicotianaRESUMEN
Peribronchial lymphoid follicles have recently been identified as one of the hallmark features of (severe) chronic obstructive pulmonary disease (COPD). However, little is known about the relative contribution of peribronchial lymphoid follicles vs mediastinal lymph nodes in inflammatory responses in COPD patients and animal models. In a murine model of COPD, we studied inflammatory responses in airways, lungs, and mediastinal lymph nodes of wild-type (WT) vs CCR7 knockout (CCR7(-/-)) mice upon subacute or chronic exposure to cigarette smoke (CS). Although crucial for the organization of the secondary lymphoid organs, CCR7 was not required for the development of chronic CS-induced pulmonary lymphoid follicles. Moreover, T cell numbers were significantly increased in airways and lungs of air-exposed CCR7(-/-) mice, and they continued to increase upon chronic CS exposure. Unexpectedly, subacute CS-induced inflammation in airways and lungs, including airway neutrophilia and the recruitment of inflammatory-type CD11b(+) dendritic cells, depended greatly on CCR7. In the draining lymph nodes, chronic CS exposure induced CCR7-dependent recruitment of airway-derived dendritic cells, accompanied by increases in CD4(+) and CD8(+) T cells. Correspondingly, CS exposure up-regulated mRNA expression of CCR7 ligands CCL19 and CCL21-Ser in lymph nodes of WT mice, but not CCR7(-/-) mice. In the lungs of WT mice, chronic CS exposure significantly increased CCL19 mRNA and protein. Furthermore, double staining for CCL19 and pro-surfactant protein C showed that alveolar type II cells express high levels of CCL19. These data unveil a so far unappreciated role for CCR7 in modulating inflammatory responses in airways and lungs.