RESUMO
The chemokine eotaxin/CCL11 is an important mediator of leukocyte migration, but its effect on inflammatory cytokine signaling has not been explored. In this study, we find that CCL11 induces suppressor of cytokine signaling (SOCS)1 and SOCS3 expression in murine macrophages, human monocytes, and dendritic cells (DCs). We also discover that CCL11 inhibits GM-CSF-mediated STAT5 activation and IL-4-induced STAT6 activation in a range of hematopoietic cells. This blockade of cytokine signaling by CCL11 results in reduced differentiation and endocytic ability of DCs, implicating CCL11-induced SOCS as mediators of chemotactic inflammatory control. These findings demonstrate cross-talk between chemokine and cytokine responses, suggesting that myeloid cells tracking to the inflammatory site do not differentiate in the presence of this chemokine, revealing another role for SOCS in inflammatory regulation.
Assuntos
Diferenciação Celular/efeitos dos fármacos , Quimiocina CCL11/farmacologia , Células Dendríticas/citologia , Fator Estimulador de Colônias de Granulócitos e Macrófagos/farmacologia , Sistema Hematopoético/citologia , Interleucina-4/farmacologia , Proteínas Supressoras da Sinalização de Citocina/metabolismo , Animais , Linhagem Celular , Citocinas/metabolismo , Células Dendríticas/efeitos dos fármacos , Células Dendríticas/metabolismo , Endocitose/efeitos dos fármacos , Subunidades alfa Gi-Go de Proteínas de Ligação ao GTP/metabolismo , Sistema Hematopoético/efeitos dos fármacos , Sistema Hematopoético/metabolismo , Humanos , Mediadores da Inflamação/metabolismo , Macrófagos/citologia , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Receptores Acoplados a Proteínas G/metabolismo , Transdução de Sinais/efeitos dos fármacos , Proteína 1 Supressora da Sinalização de Citocina , Proteína 3 Supressora da Sinalização de Citocinas , Proteínas Supressoras da Sinalização de Citocina/genéticaRESUMO
Treatment of cells with cytokines and growth factors leads to the synthesis of Suppressor of Cytokine Signalling (SOCS) proteins that act as potent negative regulators of signalling via the Jak/STAT pathway. We used immunohistochemistry to identify cells and pathologies where SOCS3 expression might influence acute and chronic inflammatory responses in human tissues. Epitope and GFP tagged SOCS3 fusion proteins were localised predominantly in the nucleus of transfected cells and a validated anti SOCS3 antiserum revealed the expression of SOCS3 in the nucleus and cytoplasm of macrophages, endothelial and epithelial cells in a wide range of normal tissues in tissue microarrays (n = 31 different tissues). Nuclear SOCS3 was only seen in cells expressing a high level of the protein. Comparative immunostaining of acute, chronically and granulomatously inflamed human tissues revealed higher levels of nuclear and cytoplasmic SOCS3 expression in inflamed than in corresponding normal tissues, particularly in recruited leukocyte populations, but also in epithelia. The staining appeared more intense, suggesting higher expression levels, in areas where inflammation was more acute, consistent with the time course of SOCS3 induction described in vitro. Expression of SOCS3 protein by leucocytes and other cell types in tissue sections could be a useful marker of cells undergoing acute or chronic stimulation by cytokines in vivo.
Assuntos
Apendicite/patologia , Expressão Gênica , Arterite de Células Gigantes/patologia , Doenças Inflamatórias Intestinais/patologia , Sarcoidose/patologia , Proteínas Supressoras da Sinalização de Citocina/metabolismo , Reação de Fase Aguda/metabolismo , Animais , Apendicite/metabolismo , Biomarcadores/metabolismo , Células CHO , Cricetinae , Cricetulus , Feminino , Genes Reporter , Arterite de Células Gigantes/metabolismo , Células HEK293 , Humanos , Doenças Inflamatórias Intestinais/metabolismo , Luciferases/biossíntese , Luciferases/genética , Masculino , Especificidade de Órgãos , Transporte Proteico , Sarcoidose/metabolismo , Proteína 3 Supressora da Sinalização de Citocinas , Proteínas Supressoras da Sinalização de Citocina/genética , Regulação para Cima , beta-Galactosidase/biossíntese , beta-Galactosidase/genéticaRESUMO
Suppressors of cytokine signalling (SOCS) proteins regulate signal transduction, but their role in responses to chemokines remains poorly understood. We report that cells expressing SOCS1 and 3 exhibit enhanced adhesion and reduced migration towards the chemokine CCL11. Focal adhesion kinase (FAK) and the GTPase RhoA, control cell adhesion and migration and we show the presence of SOCS1 or 3 regulates expression and tyrosine phosphorylation of FAK, while also enhancing activation of RhoA. Our novel findings suggest that SOCS1 and 3 may control chemotaxis and adhesion by significantly enhancing both FAK and RhoA activity, thus localizing immune cells to the site of allergic inflammation.