RESUMEN
RATIONALE: Airway hyperresponsiveness is a critical feature of asthma. Substantial epidemiologic evidence supports a role for female sex hormones in modulating lung function and airway hyperresponsiveness in humans. OBJECTIVES: To examine the role of estrogen receptors in modulating lung function and airway responsiveness using estrogen receptor-deficient mice. METHODS: Lung function was assessed by a combination of whole-body barometric plethysmography, invasive measurement of airway resistance, and isometric force measurements in isolated bronchial rings. M2 muscarinic receptor expression was assessed by Western blotting, and function was assessed by electrical field stimulation of tracheas in the presence/absence of gallamine. Allergic airway disease was examined after ovalbumin sensitization and exposure. MEASUREMENTS AND MAIN RESULTS: Estrogen receptor-alpha knockout mice exhibit a variety of lung function abnormalities and have enhanced airway responsiveness to inhaled methacholine and serotonin under basal conditions. This is associated with reduced M2 muscarinic receptor expression and function in the lungs. Absence of estrogen receptor-alpha also leads to increased airway responsiveness without increased inflammation after allergen sensitization and challenge. CONCLUSIONS: These data suggest that estrogen receptor-alpha is a critical regulator of airway hyperresponsiveness in mice.
Asunto(s)
Hiperreactividad Bronquial/etiología , Receptor alfa de Estrógeno/fisiología , Pulmón/fisiopatología , Receptor Muscarínico M2/metabolismo , Hipersensibilidad Respiratoria/etiología , Acetilcolina/metabolismo , Alérgenos/inmunología , Animales , Hiperreactividad Bronquial/sangre , Hiperreactividad Bronquial/fisiopatología , Citocinas/metabolismo , Electrofisiología , Receptor alfa de Estrógeno/genética , Estrógenos/sangre , Femenino , Inflamación/inmunología , Pulmón/efectos de los fármacos , Pulmón/inervación , Cloruro de Metacolina/farmacología , Ratones , Ratones Noqueados , Ovalbúmina/inmunología , Nervios Periféricos/fisiología , Pletismografía , Receptor Muscarínico M2/análisis , Hipersensibilidad Respiratoria/inmunología , Hipersensibilidad Respiratoria/fisiopatología , Serotonina/farmacología , Tráquea/efectos de los fármacos , Tráquea/inervación , Tráquea/fisiopatologíaRESUMEN
Pharmacological inhibition or genetic disruption of cyclooxygenase (COX)-1 or COX-2 exacerbates the inflammatory and functional responses of the lung to environmentally relevant stimuli. To further examine the contribution of COX-derived eicosanoids to basal lung function and to allergic lung inflammation, transgenic (Tr) mice were generated in which overexpression of human COX-1 was targeted to airway epithelium. Although no differences in basal respiratory or lung mechanical parameters were observed, COX-1 Tr mice had increased bronchoalveolar lavage fluid PGE(2) content compared with wild-type littermates (23.0 +/- 3.6 vs 8.4 +/- 1.4 pg/ml; p < 0.05) and exhibited decreased airway responsiveness to inhaled methacholine. In an OVA-induced allergic airway inflammation model, comparable up-regulation of COX-2 protein was observed in the lungs of allergic wild-type and COX-1 Tr mice. Furthermore, no genotype differences were observed in allergic mice in total cell number, eosinophil content (70 vs 76% of total cells, respectively), and inflammatory cytokine content of bronchoalveolar lavage fluid, or in airway responsiveness to inhaled methacholine (p > 0.05). To eliminate the presumed confounding effects of COX-2 up-regulation, COX-1 Tr mice were bred into a COX-2 null background. In these mice, the presence of the COX-1 transgene did not alter allergen-induced inflammation but significantly attenuated allergen-induced airway hyperresponsiveness, coincident with reduced airway leukotriene levels. Collectively, these data indicate that COX-1 overexpression attenuates airway responsiveness under basal conditions but does not influence allergic airway inflammation.
Asunto(s)
Hiperreactividad Bronquial/enzimología , Ciclooxigenasa 1/metabolismo , Hipersensibilidad/enzimología , Inflamación/enzimología , Pulmón/inmunología , Animales , Hiperreactividad Bronquial/inmunología , Hiperreactividad Bronquial/patología , Pruebas de Provocación Bronquial , Líquido del Lavado Bronquioalveolar/química , Ciclooxigenasa 1/genética , Ciclooxigenasa 1/inmunología , Ciclooxigenasa 2/deficiencia , Dinoprostona/metabolismo , Humanos , Hipersensibilidad/inmunología , Hipersensibilidad/patología , Inflamación/inmunología , Inflamación/patología , Pulmón/metabolismo , Pulmón/patología , Cloruro de Metacolina/farmacología , Ratones , Ratones Transgénicos , Ovalbúmina/inmunología , Pletismografía Total , Pruebas de Función Respiratoria , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , TransgenesRESUMEN
The roles of gender and sex hormones in lung function and disease are complex and not completely understood. The present study examined the influence of gender on lung function and respiratory mechanics in naive mice and on acute airway inflammation and hyperresponsiveness induced by intratracheal LPS administration. Basal lung function characteristics did not differ between naive males and females, but males demonstrated significantly greater airway responsiveness than females following aerosolized methacholine challenge as evidenced by increased respiratory system resistance and elastance (p < 0.05). Following LPS administration, males developed more severe hypothermia and greater airway hyperresponsiveness than females (p < 0.05). Inflammatory indices including bronchoalveolar lavage fluid total cells, neutrophils, and TNF-alpha content were greater in males than in females 6 h following LPS administration (p < 0.05), whereas whole-lung TLR-4 protein levels did not differ among treatment groups, suggesting that differential expression of TLR-4 before or after LPS exposure did not underlie the observed inflammatory outcomes. Gonadectomy decreased airway inflammation in males but did not alter inflammation in females, whereas administration of exogenous testosterone to intact females increased their inflammatory responses to levels observed in intact males. LPS-induced airway hyperresponsiveness was also decreased in castrated males and was increased in females administered exogenous testosterone. Collectively, these data indicate that airway responsiveness in naive mice is influenced by gender, and that male mice have exaggerated airway inflammatory and functional responses to LPS compared with females. These gender differences are mediated, at least in part, by effects of androgens.
Asunto(s)
Hiperreactividad Bronquial/patología , Hiperreactividad Bronquial/fisiopatología , Lipopolisacáridos/administración & dosificación , Caracteres Sexuales , Animales , Hiperreactividad Bronquial/inmunología , Ciclooxigenasa 2/biosíntesis , Femenino , Hipotermia/inmunología , Inflamación/inmunología , Inflamación/fisiopatología , Pulmón/enzimología , Pulmón/inmunología , Pulmón/patología , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Pletismografía , Pruebas de Función Respiratoria , Mecánica Respiratoria/inmunología , Receptor Toll-Like 4/biosíntesisRESUMEN
The retinoid-related orphan receptor alpha (RORalpha), a member of the ROR subfamily of nuclear receptors, has been implicated in the control of a number of physiological processes, including the regulation of several immune functions. To study the potential role of RORalpha in the regulation of innate immune responses in vivo, we analyzed the induction of airway inflammation in response to lipopolysaccharide (LPS) challenge in wild-type and staggerer (RORalpha(sg/sg)) mice, a natural mutant strain lacking RORalpha expression. Examination of hematoxylin and eosin-stained lung sections showed that RORalpha(sg/sg) mice displayed a higher degree of LPS-induced inflammation than wild-type mice. Bronchoalveolar lavage (BAL) was performed at 3, 16, and 24 h after LPS exposure to monitor the increase in inflammatory cells and the level of several cytokines/chemokines. The increased susceptibility of RORalpha(sg/sg) mice to LPS-induced airway inflammation correlated with a higher number of total cells and neutrophils in BAL fluids from LPS-treated RORalpha(sg/sg) mice compared with those from LPS-treated wild-type mice. In addition, IL-1beta, IL-6, and macrophage inflammatory protein-2 were appreciably more elevated in BAL fluids from LPS-treated RORalpha(sg/sg) mice compared with those from LPS-treated wild-type mice. The enhanced susceptibility of RORalpha(sg/sg) mice appeared not to be due to a repression of IkappaBalpha expression. Our observations indicate that RORalpha(sg/sg) mice are more susceptible to LPS-induced airway inflammation and are in agreement with the hypothesis that RORalpha functions as a negative regulator of LPS-induced inflammatory responses.
Asunto(s)
Lipopolisacáridos/toxicidad , Neumonía/metabolismo , Receptores Citoplasmáticos y Nucleares , Transactivadores , Animales , Líquido del Lavado Bronquioalveolar/citología , Citocinas/biosíntesis , Femenino , Proteínas I-kappa B/metabolismo , Inflamación/genética , Inflamación/metabolismo , Inflamación/patología , Masculino , Ratones , Ratones Noqueados , Ratones Mutantes Neurológicos , Infiltración Neutrófila , Miembro 1 del Grupo F de la Subfamilia 1 de Receptores Nucleares , Neumonía/inducido químicamente , Neumonía/patología , Receptores Citoplasmáticos y Nucleares/genética , Receptores Citoplasmáticos y Nucleares/metabolismo , Transactivadores/genética , Transactivadores/metabolismoRESUMEN
Acute pharmacologic inhibition of cyclooxygenase (COX)-1 or -2 during allergen sensitization and exposure leads to enhanced T helper type 2 (Th2) airway responses. COX-1 and -2 play functionally distinct roles in lymphocyte development, and consequently, genetic deficiency of either enzyme, as opposed to acute pharmacologic inhibition, may modulate Th2-mediated allergic airway disease differently. An ovalbumin-induced mouse model of allergic airway disease was used. The immunophenotype of bronchoalveolar lavage lymphocytes was assessed by flow cytometry, bronchoalveolar lavage cytokines, and chemokines were measured by enzyme-linked immunosorbent assay, adhesion molecule expression was assessed by immunoblotting in combination with immunohistochemistry, and bronchoconstriction was assessed by whole body plethysmography. The airways of COX-1-/- mice contained increased numbers of CD4+ and CD8+ T cells, exaggerated levels of the Th2 cytokines interleukin-4, -5, and -13, and increased levels of eotaxin and thymus- and activation-regulated chemokine. Allergen-induced bronchoconstriction was also increased in COX-1-/- mice. Vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 levels were increased in lungs of both COX-1-/- and COX-2-/- mice relative to wild type. These data suggest that genetic deficiency of COX-1 but not COX-2 modulates T cell recruitment, Th2 cytokine secretion, and lung function in the allergic airway.