RESUMO
Suppressors of cytokine signaling (SOCS) are important regulators of lipopolysaccharide (LPS) and cytokine responses but their role in macrophage polarization is unknown. We have shown here that myeloid-restricted Socs3 deletion (Socs3(Lyz2cre)) resulted in resistance to LPS-induced endotoxic shock, whereas Socs2(-/-) mice were highly susceptible. We observed striking bias toward M2-like macrophages in Socs3(Lyz2cre) mice, whereas the M1-like population was enriched in Socs2(-/-) mice. Adoptive transfer experiments showed that responses to endotoxic shock and polymicrobial sepsis were transferable and macrophage dependent. Critically, this dichotomous response was associated with enhanced regulatory T (Treg) cell recruitment by Socs3(Lyz2cre) cells, whereas Treg cell recruitment was absent in the presence of Socs2(-/-) macrophages. In addition, altered polarization coincided with enhanced interferon-gamma (IFN-γ)-induced signal transducer and activator of transcription-1 (STAT1) activation in Socs2(-/-) macrophages and enhanced interleukin-4 (IL-4) plus IL-13-induced STAT6 phosphorylation in Socs3(Lyz2cre) macrophages. SOCS, therefore, are essential controllers of macrophage polarization, regulating inflammatory responses.
Assuntos
Polaridade Celular/genética , Macrófagos/imunologia , Macrófagos/metabolismo , Proteínas Supressoras da Sinalização de Citocina/genética , Transferência Adotiva , Animais , Regulação da Expressão Gênica , Interleucina-10/imunologia , Interleucina-10/metabolismo , Macrófagos/transplante , Camundongos , Fatores de Transcrição STAT/metabolismo , Sepse/genética , Sepse/imunologia , Sepse/prevenção & controle , Transdução de Sinais , Proteína 3 Supressora da Sinalização de Citocinas , Proteínas Supressoras da Sinalização de Citocina/imunologia , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/metabolismo , Transplante IsogênicoRESUMO
Although production of cytokines by TLR is essential for viral and bacterial clearance, overproduction can be detrimental, thus controlling these responses is essential. CD33-related sialic acid binding Ig-like lectin receptors (Siglecs) have been implicated in the control of leukocyte responses. In this study, we report that murine Siglec-E is induced by TLRs in a MyD88-specific manner, is tyrosine phosphorylated following LPS stimulation, and negatively regulates TLR responses. Specifically, we demonstrate the Siglec-E expression inhibits TLR-induced NF-kappaB and more importantly, the induction of the antiviral cytokines IFN-beta and RANTES. Siglec-E mediates its inhibitory effects on TIR domain containing adaptor inducing IFN-beta (TRIF)-dependent cytokine production via recruitment of the tyrosine [corrected] phosphatase SHP2 and subsequent inhibition of TBK1 activity as evidenced by enhanced TBK1 phosphorylation in cells following knockdown of Siglec-E expression. Taken together, our results demonstrate a novel role for Siglec-E in controlling the antiviral response to TLRs and thus helping to maintain a healthy cytokine balance following infection.
Assuntos
Antígenos CD/biossíntese , Antígenos de Diferenciação de Linfócitos B/biossíntese , Citocinas/antagonistas & inibidores , Citocinas/biossíntese , Regulação para Baixo/imunologia , Lipopolissacarídeos/farmacologia , Receptores Toll-Like/antagonistas & inibidores , Receptores Toll-Like/fisiologia , Regulação para Cima/imunologia , Proteínas Adaptadoras de Transporte Vesicular/antagonistas & inibidores , Proteínas Adaptadoras de Transporte Vesicular/genética , Proteínas Adaptadoras de Transporte Vesicular/fisiologia , Animais , Antígenos CD/metabolismo , Antígenos CD/fisiologia , Antígenos de Diferenciação de Linfócitos B/metabolismo , Antígenos de Diferenciação de Linfócitos B/fisiologia , Linhagem Celular , Linhagem Celular Transformada , Citocinas/genética , Regulação para Baixo/genética , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fator 88 de Diferenciação Mieloide/fisiologia , NF-kappa B/antagonistas & inibidores , NF-kappa B/metabolismo , Fosforilação/imunologia , Proteína Tirosina Fosfatase não Receptora Tipo 11/metabolismo , Proteína Tirosina Fosfatase não Receptora Tipo 11/fisiologia , Transdução de Sinais/genética , Transdução de Sinais/imunologiaRESUMO
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
Respiratory syncytial virus (RSV) infection causes bronchiolitis and pneumonia in infants. RSV has a linear single-stranded RNA genome encoding 11 proteins, 2 of which are nonstructural (NS1 and NS2). RSV specifically downregulates STAT2 protein expression, thus enabling the virus to evade the host type I interferon response. Degradation of STAT2 requires proteasomal activity and is dependent on the expression of RSV NS1 and NS2 (NS1/2). Here we investigate whether RSV NS proteins can assemble ubiquitin ligase (E3) enzymes to target STAT2 to the proteasome. We demonstrate that NS1 contains elongin C and cullin 2 binding consensus sequences and can interact with elongin C and cullin 2 in vitro; therefore, NS1 has the potential to act as an E3 ligase. By knocking down expression of specific endogenous E3 ligase components using small interfering RNA, NS1/2, or RSV-induced STAT2, degradation is prevented. These results indicate that E3 ligase activity is crucial for the ability of RSV to degrade STAT2. These data may provide the basis for therapeutic intervention against RSV and/or logically designed live attenuated RSV vaccines.
Assuntos
Proteínas Culina/metabolismo , Vírus Sinciciais Respiratórios/metabolismo , Fator de Transcrição STAT2/metabolismo , Fatores de Transcrição/metabolismo , Proteínas não Estruturais Virais/metabolismo , Sequência de Aminoácidos , Sítios de Ligação , Linhagem Celular , Proteínas Culina/genética , Elonguina , Humanos , Dados de Sequência Molecular , Complexo de Endopeptidases do Proteassoma/metabolismo , Ligação Proteica , RNA Interferente Pequeno/genética , Vírus Sinciciais Respiratórios/genética , Fator de Transcrição STAT1/metabolismo , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Fatores de Transcrição/genética , Ubiquitina/metabolismo , Proteínas não Estruturais Virais/química , Proteínas não Estruturais Virais/genéticaRESUMO
CD33-related Siglecs (sialic acid-binding immunoglobulin-like lectins) 5-11 are inhibitory receptors that contain a membrane proximal ITIM (immunoreceptor tyrosine-based inhibitory motif) (I/V/L/)XYXX(L/V), which can recruit SHP-1/2. However, little is known about the regulation of these receptors. SOCS3 (suppressor of cytokine signaling 3) is up-regulated during inflammation and competes with SHP-1/2 for binding to ITIM-like motifs on various cytokine receptors resulting in inhibition of signaling. We show that SOCS3 binds the phosphorylated ITIM of Siglec 7 and targets it for proteasomal-mediated degradation, suggesting that Siglec 7 is a novel SOCS target. Following ligation, the ECS E3 ligase is recruited by SOCS3 to target Siglec 7 for proteasomal degradation, and SOCS3 expression is decreased concomitantly. In addition, we found that SOCS3 expression blocks Siglec 7-mediated inhibition of cytokine-induced proliferation. This is the first time that a SOCS target has been reported to degrade simultaneously with the SOCS protein and that inhibitory receptors have been shown to be degraded in this way. This may be a mechanism by which the inflammatory response is potentiated during infection.