RESUMEN
BACKGROUND: Tissue eosinophils express more membrane receptors and release more mediators than blood eosinophils, suggesting that migration from blood to tissue modulates eosinophil phenotype and functions. OBJECTIVE: We postulated that eosinophil passage through endothelial basement membrane, an important step of eosinophil migration into tissue, may be responsible for some of these changes. METHOD: We previously showed that 5-oxo-6, 8, 11, 14-eicosatetraenoic acid (5-oxo-ETE) in combination with IL-5 promotes eosinophil migration through Matrigel, a mouse tumour cell-derived basement membrane. Using this model, we evaluated the effect of trans-Matrigel migration on purified human blood eosinophil expressions of CD44, CD69 and HLA-DR that either increase or appear on activated eosinophils, and releases of peroxidase (EPO), leukotriene (LT) C(4) and granulocyte-monocyte colony stimulating factor (GM-CSF). RESULTS: IL-5, but not 5-oxo-ETE, increased eosinophil expression of CD44 and CD69. Migration of eosinophils through Matrigel significantly increased CD44 expression level over the one induced by IL-5 (P = 0.0001). Migration through Matrigel did not modify CD69 expression compared with the one obtained in the presence of IL-5 alone; however, incubation of eosinophils on Matrigel decreased IL-5-induced CD69 (P = 0.0001). Trans-Matrigel migration did not modify HLA-DR expression, nor EPO, LTC(4) and GM-CSF releases. CONCLUSION: These data show that in vitro trans-Matrigel migration and Matrigel contact modulate eosinophil membrane receptor expression. Consequently, they suggest that migration through basement membrane mediates changes in cell-surface phenotype observed on activated eosinophils and probably prepares them for interactions with tissue components and cells.
Asunto(s)
Membrana Basal/metabolismo , Movimiento Celular/fisiología , Eosinófilos/metabolismo , Receptores de Hialuranos/biosíntesis , Adolescente , Adulto , Ácidos Araquidónicos/farmacología , Asma/metabolismo , Asma/fisiopatología , Membrana Basal/citología , Membrana Basal/efectos de los fármacos , Materiales Biocompatibles/farmacología , Movimiento Celular/efectos de los fármacos , Colágeno/farmacología , Citocinas/efectos de los fármacos , Citocinas/metabolismo , Combinación de Medicamentos , Eosinófilos/efectos de los fármacos , Femenino , Volumen Espiratorio Forzado/fisiología , Factor Estimulante de Colonias de Granulocitos y Macrófagos/efectos de los fármacos , Factor Estimulante de Colonias de Granulocitos y Macrófagos/metabolismo , Humanos , Receptores de Hialuranos/efectos de los fármacos , Mediadores de Inflamación/metabolismo , Interleucina-5/farmacología , Laminina/farmacología , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Proteoglicanos/farmacología , Receptores de Superficie Celular/biosíntesis , Receptores de Superficie Celular/efectos de los fármacosRESUMEN
BACKGROUND: Since eosinophils are implicated in asthma pathogenesis, we investigated whether these cells were activated in severe asthma. METHODS: Twenty-six asthmatics with different clinical responses to oral corticosteroid (CS), i.e. sensitive [change in forced expiratory volume in 1 s (DeltaFEV(1)) >/= 25% after oral methylprednisolone, 40 mg daily, for 14 days, n = 7], resistant (DeltaFEV(1) = 15%, n = 9) and dependent (>/= 20 mg oral prednisone daily for acceptable asthma control, n = 10), were studied. RESULTS: Calcium ionophore-induced leukotriene (LT) C(4) release of purified blood eosinophils was similar in the three groups. Cell incubation with granulocyte-macrophage colony-stimulating factor (GM-CSF) enhanced ionophore-induced LTC(4) release, and this effect was higher in CS-sensitive (5-fold) than in CS-resistant subjects (1.7-fold) (p = 0.02). CS treatment decreased blood eosinophil counts in these two groups of subjects (p = 0.02) and decreased GM-CSF-enhanced LTC(4) release in CS-sensitive asthmatics only (p = 0.04). In contrast, despite a high mean daily dose of oral CS (35 +/- 8 mg), blood counts of eosinophils from CS-dependent subjects were higher (p = 0.03) and GM-CSF enhancement of LTC(4) release was greater (2.8-fold) than in CS-sensitive (2. 1-fold) and CS-resistant (1.7-fold) subjects (p = 0.04). Interestingly, serum from CS-resistant subjects reduced GM-CSF enhancement of LTC(4) release by eosinophils of CS-sensitive asthmatics (p = 0.001). CONCLUSIONS: Eosinophils from CS-dependent asthmatics have an impaired response to CS, whereas serum from CS-resistant subjects contains an inhibitor of eosinophil response to GM-CSF.
Asunto(s)
Corticoesteroides/uso terapéutico , Eosinófilos/inmunología , Estado Asmático/tratamiento farmacológico , Administración Oral , Corticoesteroides/administración & dosificación , Adulto , Células Cultivadas , Resistencia a Medicamentos , Eosinófilos/metabolismo , Femenino , Factor Estimulante de Colonias de Granulocitos y Macrófagos/metabolismo , Humanos , Leucotrieno C4/metabolismo , MasculinoRESUMEN
In asthma, activation and recruitment of eosinophils to the bronchial mucosa amplifies many cellular functions. The blood eosinophil count and the number of hypodense eosinophils increase with asthma severity. Eosinophils produce numerous proinflammatory mediators in response to a variety of agonists, notably the peptido-leukotriene (LT) C4, a potent bronchoconstrictor. In this study, we have evaluated blood eosinophil LTC4 release and its modulation by cytokines in normal individuals and in subjects with asthma of various severities: mild (beta 2-agonist on demand); moderate (inhaled steroids on a regular basis); and severe (inhaled and oral steroids on a regular basis). Eosinophils were isolated using a modified Percoll gradient technique, which recovers both hypodense and normodense eosinophils in a global cell population. Eosinophils released detectable amounts of LTC4 only in the presence of the stimulus (calcium ionophore A23187, 2 microM). The ionophore-induced LTC4 release was greater in moderate asthmatics (mean +/- SEM 5.7 +/- 1.3 pg x 10(3)/250,000 eosinophils) than in normal individuals (1.6 +/- 0.4 pg x 10(3)/250,000 eosinophils), mild asthmatics (1.8 +/- 0.3 pg x 10(3)/250,000 eosinophils) and severe asthmatics (2.0 +/- 0.3 pg x 10(3)/250,000 eosinophils). Granulocyte/macrophage colony-stimulating factor (GM-CSF) and interleukin-5 (IL-5) amplified the ionophore-induced LTC4 release in the four groups from 1.9 to 2.6 and 1.9 to 2.8 fold, respectively. Interleukin-3 (IL-3) did not increase LTC4 production except by the eosinophils of the severe asthmatics whose ionophore-induced LTC4 production was enhanced by 1.9 fold. These data demonstrate that the asthmatic bronchial inflammatory process may modify blood eosinophil LTC4 release and its modulation by cytokines according to asthma severity and treatment.