Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 5 de 5
Filtrar
Más filtros












Base de datos
Intervalo de año de publicación
1.
J Interferon Cytokine Res ; 32(6): 254-68, 2012 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-22540943

RESUMEN

Ten Toll-like receptor (TLR) family members have been reported in humans. Here, the endoplasmatic receptors TLR9, TLR8, TLR7, and TLR3 respond to nucleic acids and derivatives or to small molecules (TLR7 and 8). Another cytoplasmic RNA receptor, retinoic acid inducible gene I (RIG-I), is stimulated by 5' triphosphate double-stranded RNA. We discovered that TLR7 small-molecule agonists inhibit nucleic acid-mediated TLR3, TLR7, TLR9, or RIG-I-dependent interferon-α (IFN-α) immune response. Other cytokines and chemokines stimulated by nucleic acid agonists remained unaffected. The observed blockage of TLR3, TLR7, TLR9, and RIG-I-mediated IFN-α response appears to be driven by a competitive mechanism at the type I IFN pathway. Besides type I IFN, IFN response genes such as IFIT-1, Mx1, OAS1, or IRF7 were affected, which indicates that the key element driving the inhibition is located in the type I IFN pathway. Indeed, the heterotrimeric complex formation of phosphor-signal transducer and activator of transcription factor 1 (STAT1), phosphor-STAT2, and IRF9 (called ISGF3, IFN-stimulated gene factor 3) is inhibited through the TLR7 small-molecule agonists by phosphor-STAT2 blockage. These findings provide novel insights into the use of synthetic TLR7 or TLR7/8 small molecules as ligands for immune activation and suppression.


Asunto(s)
Interferón Tipo I/antagonistas & inhibidores , Interferón Tipo I/inmunología , Transducción de Señal/efectos de los fármacos , Receptor Toll-Like 7/agonistas , Receptor Toll-Like 7/inmunología , Animales , Regulación hacia Abajo/efectos de los fármacos , Regulación hacia Abajo/inmunología , Humanos , Ligandos , Ratones , Ratones Endogámicos , Ratones Noqueados , Fosforilación , Factor de Transcripción STAT2/antagonistas & inhibidores , Factor de Transcripción STAT2/inmunología , Transducción de Señal/inmunología
2.
Immunology ; 136(1): 64-77, 2012 May.
Artículo en Inglés | MEDLINE | ID: mdl-22260507

RESUMEN

The Toll-like receptors (TLRs) 3, 7, 8 and 9 stimulate innate immune responses upon recognizing pathogen-derived nucleic acids. TLR3 is located on the cell surface and in cellular endosomes and recognizes double-stranded viral RNA or the synthetic mimic poly rI:rC. Recently, unformulated small interfering RNA (siRNA) has been reported as ligand for surface-expressed murine TLR3. Blockage of TLR3 is achieved by single-stranded DNA. We confirm and expand the observation that poly rI:rC-mediated TLR3 immune activation is blocked in a sequence-, length-, backbone- and CpG-dependent manner. However, human TLR3 is not activated by siRNA, which may be the result of differences in the amino acid composition of the TLR3 loop 1 of mice and humans. Although CD14 was previously described as a co-receptor for murine TLR3 and other nucleic acid-recognizing TLRs, human CD14 acts only as co-receptor to human TLR9, but not TLR3, TLR7 or TLR8. We show that CD14 up-regulates the TLR9 immune response of A, B and C-class oligodeoxynucleotides but down-regulates the phosphoro-diester version of B-class oligodeoxynucleotides.


Asunto(s)
ADN de Cadena Simple/genética , Receptores de Lipopolisacáridos/inmunología , ARN Interferente Pequeño/genética , Receptor Toll-Like 3/inmunología , Animales , Línea Celular , Humanos , Ratones , Receptor Toll-Like 3/genética , Receptor Toll-Like 9/inmunología
3.
Immunol Lett ; 141(2): 169-80, 2012 Jan 30.
Artículo en Inglés | MEDLINE | ID: mdl-22001011

RESUMEN

Small interfering RNAs (siRNAs) induce robust degradation of homologous mRNAs. Highly specific silencing of target genes makes siRNA an interesting tool in drug development. However, several non-specific effects complicate the use of RNA interference (RNAi). One of the most prevalent unspecific effects is triggering the innate immune system in mammals. In parallel, activating the immune system may open the possibility to develop dual siRNAs for treatment of a variety of diseases including cancer. Here, we show that the best use of unmodified siRNAs for RNAi and immune activation depends on the delivery system, formulation condition, sequence and siRNA design concerning ORN motifs. Testing several commercial delivery systems identified that the optimal siRNAs for dual functions should contain TLR7/8 ORN motifs at least in the antisense strand and be delivered by either Dharmafect or HiPerfect. Superfect delivery system only activates TLR7 and opens new capabilities in RNAi and immune activation.


Asunto(s)
Leucocitos Mononucleares/metabolismo , Motivos de Nucleótidos , ARN Interferente Pequeño/genética , Receptor Toll-Like 7/genética , Receptor Toll-Like 8/genética , Secuencia de Bases , Línea Celular , Citocinas/metabolismo , Vectores Genéticos , Humanos , Inmunidad Innata/genética , Inmunización/métodos , Leucocitos Mononucleares/inmunología , Leucocitos Mononucleares/patología , Datos de Secuencia Molecular , FN-kappa B/genética , FN-kappa B/metabolismo , Motivos de Nucleótidos/genética , Interferencia de ARN
4.
J Immunol ; 180(6): 3729-38, 2008 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-18322178

RESUMEN

The TLRs 7, 8, and 9 stimulate innate immune responses upon recognizing pathogen nucleic acids. U-rich RNA sequences were recently discovered that stimulate human TLR7/8-mediated or murine TLR7-mediated immune effects. In this study we identified single-stranded RNA sequences containing defined sequence motifs that either preferentially activate human TLR8-mediated as opposed to TLR7- or TLR7/8-mediated immune responses. The identified TLR8 RNA motifs signal via TLR8 and fail to induce IFN-alpha from TLR7-expressing plasmacytoid dendritic cells but induce the secretion of Th1-like and proinflammatory cytokines from TLR8-expressing immune cells such as monocytes or myeloid dendritic cells. In contrast, RNA sequences containing the TLR7/8 motif signal via TLR7 and TLR8 and stimulate cytokine secretion from both TLR7- and TLR8-positive immunocytes. The TLR8-specific RNA sequences are able to trigger cytokine responses from human and bovine but not from mouse, rat, and porcine immune cells, suggesting that these species lack the capability to respond properly to TLR8 RNA ligands. In summary, we describe two classes of single-stranded TLR7/8 and TLR8 RNA agonists with diverse target cell and species specificities and immune response profiles.


Asunto(s)
Secuencia de Bases , Oligorribonucleótidos/inmunología , Análisis de Secuencia de ARN , Receptor Toll-Like 8/genética , Animales , Bovinos , Línea Celular , Fosfatos de Dinucleósidos/inmunología , Fosfatos de Dinucleósidos/metabolismo , Fosfatos de Dinucleósidos/farmacología , Femenino , Humanos , Interferón-alfa/biosíntesis , Interferón-alfa/metabolismo , Leucocitos Mononucleares/inmunología , Leucocitos Mononucleares/metabolismo , Ligandos , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Oligorribonucleótidos/metabolismo , Oligorribonucleótidos/farmacología , Ratas , Ratas Sprague-Dawley , Porcinos , Receptor Toll-Like 8/biosíntesis , Receptor Toll-Like 8/metabolismo , Factor de Necrosis Tumoral alfa/biosíntesis , Factor de Necrosis Tumoral alfa/metabolismo
5.
Oligonucleotides ; 17(4): 405-17, 2007.
Artículo en Inglés | MEDLINE | ID: mdl-18072859

RESUMEN

Viruses of the order Mononegavirales encompass life-threatening pathogens with single-stranded segmented or nonsegmented negative-strand RNA genomes. The RNA genomes are characterized by highly conserved sequences at the extreme untranslated 3' and 5' termini that are most important for virus infection and viral RNA synthetic processes. The 3' terminal genome regions of negative-strand viruses such as vesicular stomatitis virus, Sendai virus, or influenza virus contain a high number of conserved U and G nucleotides, and synthetic oligoribonucleotides encoding such sequences stimulate sequence-dependent cytokine responses via TLR7 and TLR8. Immune cells responding to such sequences include NK cells, NK/T cells, plasmacytoid, and myeloid dendritic cells, as well as monocytes and B cells. Strong Th1 and pro-inflammatory cytokine responses are also induced upon in vivo application of oligoribonucleotides. It appears possible that the presence of highly conserved untranslated terminal regions in the viral genome fulfilling fundamental functions for the viral replication may enable the host to induce directed innate immune defense mechanisms, by allowing pathogen detection through essential RNA regions that the virus cannot readily mutate.


Asunto(s)
Inmunidad Innata , Mononegavirales/inmunología , Oligodesoxirribonucleótidos/inmunología , Oligorribonucleótidos/inmunología , ARN Viral/inmunología , Receptor Toll-Like 7/metabolismo , Receptor Toll-Like 8/metabolismo , Animales , Línea Celular , Secuencia Conservada , Citocinas/biosíntesis , Citocinas/inmunología , Células Dendríticas/efectos de los fármacos , Células Dendríticas/inmunología , Femenino , Genoma Viral , Humanos , Interferón gamma/biosíntesis , Interferón gamma/inmunología , Células Asesinas Naturales/efectos de los fármacos , Células Asesinas Naturales/inmunología , Ratones , Ratones Endogámicos BALB C , Monocitos/efectos de los fármacos , Monocitos/inmunología , Mononegavirales/metabolismo , Oligodesoxirribonucleótidos/farmacología , Oligorribonucleótidos/farmacología , Receptor Toll-Like 7/inmunología , Receptor Toll-Like 8/inmunología
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...