RESUMO
Cytokines and chemokines are responsible for the attraction and activation of eosinophils in allergic and inflammatory diseases. Whereas cytokines such as IL-3, IL-5, and GM-CSF activate eosinophils via heterodimeric receptors containing a distinct alpha-chain (binding domain) and a common beta-chain (signaling domain), chemokines such as eotaxin activate eosinophils via seven-transmembrane G(i) protein-coupled CCRs. Recent studies have demonstrated the importance of CCR3 on human eosinophils that undergo receptor recycling after chemokine activation, but the modulation of this receptor by cytokines has not yet been addressed. In this study, we demonstrate that IL-3 induces a dose- and time-dependent down-regulation of CCR3 from the surface of human eosinophils comparable to the CCR3-specific ligand eotaxin, whereas IL-5, GM-CSF, IL-4, IL-10, IL-13, IFN-gamma, and TNF-alpha had no effect. Maximal down-regulation of CCR3 in response to IL-3 was reached at 24 h. Reduction of CCR3 surface protein in response to IL-3 could be prevented by an anti-IL-3 mAb and was neither due to the release of CC chemokines nor to nonspecific binding of IL-3 to CCR3. Moreover, down-regulation was prevented by phenylarsine oxide, a nonspecific inhibitor of receptor internalization. After 24 h, IL-3-induced decrease of CCR3 surface expression correlated with diminished mRNA expression, suggesting a transcriptional regulation mechanism. Since wortmannin partially inhibited IL-3- but not eotaxin-induced CCR3 down-regulation, receptor down-modulation seems to underlie different signaling events. Therefore, these data suggest a novel role for the cytokine IL-3 in the activation process of eosinophils and its predominant chemokine receptor CCR3.
Assuntos
Quimiocinas CC , Regulação para Baixo/efeitos dos fármacos , Eosinófilos/efeitos dos fármacos , Interleucina-3/farmacologia , RNA Mensageiro/biossíntese , Receptores de Quimiocinas/biossíntese , Androstadienos/farmacologia , Animais , Arsenicais/farmacologia , Sinalização do Cálcio/efeitos dos fármacos , Células Cultivadas , Quimiocina CCL11 , Citocinas/farmacologia , Relação Dose-Resposta a Droga , Endocitose/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Eosinófilos/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Fator Estimulador de Colônias de Granulócitos e Macrófagos/farmacologia , Humanos , Interferon gama/farmacologia , Interleucinas/farmacologia , Medições Luminescentes , Camundongos , RNA Mensageiro/genética , Receptores CCR3 , Receptores de Quimiocinas/genética , Proteínas Recombinantes de Fusão/biossíntese , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fatores de Tempo , Transcrição Gênica/efeitos dos fármacos , Fator de Necrose Tumoral alfa/farmacologia , WortmaninaRESUMO
The possibility of differential diagnosis of ischemic heart disease and cardialgia at a polyclinic is analyzed. A total of 1110 patients with a preliminary diagnosis of ischemic heart disease were examined. In 214 of them the data gathered during many years of observations have cast doubt on the validity of this diagnosis. The patients of this group were made to undergo tests with potassium chloride and obsidan. Subject to appraisal were the ECG reaction and an analysis of angular variations of the vectors in the terminal portion of the ventricular complex. The described tests were shown to help determine the significance of "functional" or "organic" changes of the myocardium in the genesis of repolarizational ECG perturbances.
