RESUMEN
Trehalose-6,6-dimycolate (TDM), the mycobacterial cord factor, and its synthetic analog Trehalose-6,6-dibehenate (TDB) bind to the C-type lectin receptors macrophage-inducible C-type lectin (Mincle) and Mcl to activate macrophages. Genetically, the transcriptional response to TDB/TDM has been defined to require FcRγ-Syk-Card9 signaling. However, TDB/TDM-triggered kinase activation has not been studied well, and it is largely unknown which transcriptional regulators bring about inflammatory gene expression. In this article, we report that TDB/TDM caused only weak Syk-phosphorylation in resting macrophages, consistent with low basal Mincle expression. However, LPS-priming caused MYD88-dependent upregulation of Mincle, resulting in enhanced TDB/TDM-induced kinase activation and more rapid inflammatory gene expression. TLR-induced Mincle expression partially circumvented the requirement for Mcl in the response to TDB/TDM. To dissect transcriptional responses to TDB/TDM, we mined microarray data and identified early growth response (Egr) family transcription factors as direct Mincle target genes, whereas upregulation of Cebpb and Hif1a required new protein synthesis. Macrophages and dendritic cells lacking C/EBPß showed nearly complete abrogation of TDB/TDM responsiveness, but also failed to upregulate Mincle. Retroviral rescue of Mincle expression in Cebpb-deficient cells restored induction of Egr1, but not of G-CSF. This pattern of C/EBPß dependence was also observed after stimulation with the Dectin-1 ligand Curdlan. Inducible expression of hypoxia-inducible factor 1α (HIF1α) also required C/EBPß. In turn, HIF1α was not required for Mincle expression, kinase activation, and Egr1 or Csf3 expression, but critically contributed to NO production. Taken together, we identify C/EBPß as central hub in Mincle expression and inflammatory gene induction, whereas HIF1α controls Nos2 expression. C/EBPß also connects TLR signals to cord factor responsiveness through MYD88-dependent upregulation of Mincle.
Asunto(s)
Proteína beta Potenciadora de Unión a CCAAT/inmunología , Factores Cordón/farmacología , Subunidad alfa del Factor 1 Inducible por Hipoxia/inmunología , Lectinas Tipo C/inmunología , Macrófagos/inmunología , Proteínas de la Membrana/inmunología , Mycobacterium tuberculosis/química , Regulación hacia Arriba/efectos de los fármacos , Animales , Proteína beta Potenciadora de Unión a CCAAT/genética , Factores Cordón/química , Células Dendríticas/citología , Células Dendríticas/inmunología , Proteína 1 de la Respuesta de Crecimiento Precoz/genética , Proteína 1 de la Respuesta de Crecimiento Precoz/inmunología , Activación Enzimática/efectos de los fármacos , Activación Enzimática/genética , Activación Enzimática/inmunología , Factor Estimulante de Colonias de Granulocitos/inmunología , Subunidad alfa del Factor 1 Inducible por Hipoxia/genética , Péptidos y Proteínas de Señalización Intracelular/genética , Péptidos y Proteínas de Señalización Intracelular/inmunología , Lectinas Tipo C/genética , Macrófagos/citología , Proteínas de la Membrana/genética , Ratones , Ratones Noqueados , Factor 88 de Diferenciación Mieloide/genética , Factor 88 de Diferenciación Mieloide/inmunología , Óxido Nítrico/genética , Óxido Nítrico/inmunología , Óxido Nítrico Sintasa de Tipo II/genética , Óxido Nítrico Sintasa de Tipo II/inmunología , Fosforilación/efectos de los fármacos , Fosforilación/genética , Fosforilación/inmunología , Biosíntesis de Proteínas/efectos de los fármacos , Biosíntesis de Proteínas/genética , Biosíntesis de Proteínas/inmunología , Proteínas Tirosina Quinasas/genética , Proteínas Tirosina Quinasas/inmunología , Quinasa Syk , Receptores Toll-Like/genética , Receptores Toll-Like/inmunología , Regulación hacia Arriba/genética , Regulación hacia Arriba/inmunología , beta-Glucanos/química , beta-Glucanos/farmacologíaRESUMEN
Tumor progression is accompanied by an altered myelopoiesis causing the accumulation of immunosuppressive cells. Here, we showed that miR-142-3p downregulation promoted macrophage differentiation and determined the acquisition of their immunosuppressive function in tumor. Tumor-released cytokines signaling through gp130, the common subunit of the interleukin-6 cytokine receptor family, induced the LAP∗ isoform of C/EBPß transcription factor, promoting macrophage generation. miR-142-3p downregulated gp130 by canonical binding to its messenger RNA (mRNA) 3' UTR and repressed C/EBPß LAP∗ by noncanonical binding to its 5' mRNA coding sequence. Enforced miR expression impaired macrophage differentiation both in vitro and in vivo. Mice constitutively expressing miR-142-3p in the bone marrow showed a marked increase in survival following immunotherapy with tumor-specific T lymphocytes. By modulating a specific miR in bone marrow precursors, we thus demonstrated the feasibility of altering tumor-induced macrophage differentiation as a potent tool to improve the efficacy of cancer immunotherapy.
Asunto(s)
Inmunoterapia/métodos , Macrófagos/inmunología , MicroARNs/metabolismo , Neoplasias Experimentales/genética , Neoplasias Experimentales/inmunología , ARN Mensajero/metabolismo , Animales , Antígenos de Neoplasias/inmunología , Proteínas Portadoras/genética , Proteínas Portadoras/metabolismo , Diferenciación Celular/genética , Línea Celular Tumoral , Receptor gp130 de Citocinas/metabolismo , Inmunoterapia/tendencias , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Transgénicos , MicroARNs/genética , Mielopoyesis/genética , Neoplasias Experimentales/terapia , ARN Mensajero/genética , Transducción de Señal , Esteroide Isomerasas/genética , Esteroide Isomerasas/metabolismo , Linfocitos T/inmunología , Linfocitos T/trasplante , Transgenes/genética , Escape del TumorRESUMEN
In normal hematopoiesis, differentiation and maturation of cell populations belonging to various lineages are tightly regulated by the interaction of many transcription factors. The relative numbers of different myeloid cells depends on their proliferative/apoptotic rate, while their identity relates to their recruitment to the sites of action and the expression of specific genes regulating their function. Under pathological conditions, as during chronic inflammation and cancer development, an aberrant hematopoiesis occurs, with the consequent expansion of myeloid-derived suppressor cells (MDSCs). These cells have distinctive properties that determine their ability to tune down the immune system by principally inactivating CD8(+) T cells. Understanding the molecular networks regulating the phenotypic and functional determination of MDSCs is essential to identify potential therapeutic targets to revert immune deregulation in cancer.
Asunto(s)
Células Mieloides/inmunología , Factores de Transcripción/inmunología , Animales , Linfocitos T CD8-positivos/inmunología , Diferenciación Celular , Humanos , Neoplasias/inmunologíaRESUMEN
Tumor growth is associated with a profound alteration in myelopoiesis, leading to recruitment of immunosuppressive cells known as myeloid-derived suppressor cells (MDSCs). We showed that among factors produced by various experimental tumors, the cytokines GM-CSF, G-CSF, and IL-6 allowed a rapid generation of MDSCs from precursors present in mouse and human bone marrow (BM). BM-MDSCs induced by GM-CSF+IL-6 possessed the highest tolerogenic activity, as revealed by the ability to impair the priming of CD8(+) T cells and allow long term acceptance of pancreatic islet allografts. Cytokines inducing MDSCs acted on a common molecular pathway and the immunoregulatory activity of both tumor-induced and BM-derived MDSCs was entirely dependent on the C/EBPbeta transcription factor. Adoptive transfer of tumor antigen-specific CD8(+) T lymphocytes resulted in therapy of established tumors only in mice lacking C/EBPbeta in the myeloid compartment, suggesting that C/EBPbeta is a critical regulator of the immunosuppressive environment created by growing cancers.
Asunto(s)
Células de la Médula Ósea/inmunología , Proteína beta Potenciadora de Unión a CCAAT/inmunología , Tolerancia Inmunológica/inmunología , Neoplasias/inmunología , Escape del Tumor/inmunología , Traslado Adoptivo , Animales , Proteína beta Potenciadora de Unión a CCAAT/genética , Separación Celular , Ensayo de Inmunoadsorción Enzimática , Citometría de Flujo , Factor Estimulante de Colonias de Granulocitos/biosíntesis , Factor Estimulante de Colonias de Granulocitos/inmunología , Factor Estimulante de Colonias de Granulocitos y Macrófagos/biosíntesis , Factor Estimulante de Colonias de Granulocitos y Macrófagos/inmunología , Humanos , Tolerancia Inmunológica/genética , Interleucina-6/biosíntesis , Interleucina-6/inmunología , Ratones , Neoplasias/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Escape del Tumor/genéticaRESUMEN
Myeloid-derived suppressor cells (MDSCs) represent a subset of myeloid cells that expand under pathological conditions, such as cancer development, acute and chronic infections, trauma, bone marrow transplantations, and some autoimmune diseases. MDSCs mediate a negative regulation of the immune response by affecting different T lymphocyte subsets. Potential mechanisms, which underlie this inhibitory activity range from those requiring direct cell-to-cell contact with others, more indirect, and mediated by the modification of the microenvironment. Pharmacological inhibition of MDSC suppressive pathways is a promising strategy to overcome disease-induced immune defects, which might be a key step in enhancing the effectiveness of immune-based therapies.
Asunto(s)
Sistemas de Liberación de Medicamentos , Factores Inmunológicos/fisiología , Células Mieloides/inmunología , Factores Supresores Inmunológicos/fisiología , Animales , Enfermedades Autoinmunes/tratamiento farmacológico , Enfermedades Autoinmunes/metabolismo , Enfermedades Autoinmunes/patología , Sistemas de Liberación de Medicamentos/métodos , Humanos , Inmunidad Celular/efectos de los fármacos , Inmunidad Celular/inmunología , Factores Inmunológicos/farmacología , Factores Inmunológicos/uso terapéutico , Células Mieloides/efectos de los fármacosRESUMEN
A heterogeneous set of cells that are commonly grouped as "myeloid cells", interacts in a complex landscape of physiological and pathological situations. In this review we attempt to trace a profile of the "myeloid connection" through different normal and pathological states, by analyzing common metabolic pathways of the amino acid l-arginine. Myeloid cells exert various, often divergent, actions on the immune response through mechanisms that exploit mediators of this peculiar metabolic pathway, ranging from l-arginine itself to its downstream metabolites, like nitric oxide and polyamines. Various pathological situations, including neoplastic and autoimmune diseases, as well as injury repair and infections are discussed here, showing how l-arginine metabolism is able to play a dual role, both as an active protector and a possible threat to the organism.