RESUMEN
Murine norovirus (MNV) is an RNA virus that can prove lethal in mice with impaired innate immunity. We found that MNV-4 infection of Stat1-/- mice was not lethal, but produced a 100% penetrant, previously undescribed lymphatic phenotype characterized by chronic-active lymphangitis with hepatitis, splenitis, and chronic cecal and colonic inflammation. Lesion pathogenesis progressed from early ileal enteritis and regional dilated lymphatics to lymphangitis, granulomatous changes in the liver and spleen, and, ultimately, typhlocolitis. Lesion development was neither affected by antibiotics nor reproduced by infection with another enteric RNA virus, rotavirus. MNV-4 infection in Stat1-/- mice decreased expression of vascular endothelial growth factor (Vegf) receptor 3, Vegf-c, and Vegf-d and increased interferon (Ifn)-γ, tumor necrosis factor-α, and inducible nitric oxide synthase. However, anti-IFN-γ and anti-tumor necrosis factor-α antibody treatment did not attenuate the histologic lesions. Studies in Ifnαßγr-/- mice suggested that canonical signaling via interferon receptors did not cause MNV-4-induced disease. Infected Stat1-/- mice had increased STAT3 phosphorylation and expressed many STAT3-regulated genes, consistent with our findings of increased myeloid cell subsets and serum granulocyte colony-stimulating factor, which are also associated with increased STAT3 activity. In conclusion, in Stat1-/- mice, MNV-4 induces lymphatic lesions similar to those seen in Crohn disease as well as hepatitis, splenitis, and typhlocolitis. MNV-4-infected Stat1-/- mice may be a useful model to study mechanistic associations between viral infections, lymphatic dysfunction, and intestinal inflammation in a genetically susceptible host.
Asunto(s)
Infecciones por Caliciviridae/complicaciones , Colitis/patología , Intestinos/patología , Hígado/patología , Linfangitis/patología , Factor de Transcripción STAT1/fisiología , Bazo/patología , Animales , Infecciones por Caliciviridae/virología , Colitis/metabolismo , Colitis/virología , Femenino , Interferones/metabolismo , Intestinos/virología , Hígado/metabolismo , Hígado/virología , Linfangitis/metabolismo , Linfangitis/virología , Ratones , Ratones Noqueados , Norovirus/aislamiento & purificación , Transducción de Señal , Bazo/metabolismo , Bazo/virologíaRESUMEN
Naive T cell activation involves at least two signals from an APC, one through the TCR via interaction with peptide-MHC complexes and a second through ligation of CD28 with B7 ligands. Following activation, T cells upregulate a host of other membrane-bound costimulatory molecules that can either promote or inhibit further T cell maturation and proliferation. In some cases, it is necessary to attenuate T cell activation to prevent deleterious inflammation, and inhibitory members of the B7/butyrophilin family of ligands have evolved to balance the strong stimuli the activating B7 ligands confer. Human genetic association and in vitro studies have implicated one such ligand, BTNL2, in controlling inflammation at mucosal surfaces. In this study, we show that recombinant mouse BTNL2 modifies B7/CD28 signaling to promote expression of Foxp3, a transcription factor necessary for regulatory T cell (Treg) development and function. BTNL2 blocks Akt-mediated inactivation of Foxo1, a transcription factor necessary for Foxp3 expression. Immunophenotyping and gene profiling reveal that BTNL2-induced Treg share many properties with natural Treg, and in vivo they suppress enteritis induced by mouse effector T cells. These findings describe a mechanism by which environmental Ag-specific Tregs may be induced by APC expressing specific modulators of costimulatory signals.
Asunto(s)
Antígenos B7/genética , Diferenciación Celular/efectos de los fármacos , Factores de Transcripción Forkhead/genética , Glicoproteínas de Membrana/farmacología , Linfocitos T Reguladores/efectos de los fármacos , Animales , Células Presentadoras de Antígenos/citología , Células Presentadoras de Antígenos/efectos de los fármacos , Células Presentadoras de Antígenos/inmunología , Antígenos B7/inmunología , Butirofilinas , Antígenos CD28/genética , Antígenos CD28/inmunología , Femenino , Proteína Forkhead Box O1 , Factores de Transcripción Forkhead/inmunología , Expresión Génica/efectos de los fármacos , Perfilación de la Expresión Génica , Inmunofenotipificación , Activación de Linfocitos , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/inmunología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Proteínas Proto-Oncogénicas c-akt/genética , Proteínas Proto-Oncogénicas c-akt/inmunología , Proteínas Recombinantes/genética , Proteínas Recombinantes/inmunología , Transducción de Señal/efectos de los fármacos , Linfocitos T Reguladores/citología , Linfocitos T Reguladores/inmunologíaRESUMEN
The butyrophilin and butyrophilin-like superfamily of molecules has garnered attention in the immunology world in the past few years as a result of the observation that the butyrophilin-like 2 molecule, BTNL2, can alter T cell responsiveness. Additional interest in this superfamily solidified following the discovery that genetic polymorphisms in BTNL2 are associated with predisposition to many human diseases. In this review, we will provide an overview of the members comprising the butyrophilin superfamily of molecules. We will then discuss BTNL2 immunomodulatory function, and BTNL2 structural associations with other costimulatory molecules. We will then draw your attention to some of the lesser-known butyrophilin superfamily members by describing the expression patterns of these molecules in human tissues and cells. And we will finish by hypothesizing on the potential influence on general immune homeostasis that might be mediated by this, thus-far little-studied, family of molecules.
Asunto(s)
Glicoproteínas de Membrana/inmunología , Isoformas de Proteínas/inmunología , Animales , Antígeno B7-1/genética , Antígeno B7-1/inmunología , Butirofilinas , Humanos , Sistema Inmunológico/fisiología , Glicoproteínas de Membrana/genética , Isoformas de Proteínas/genética , Linfocitos T/inmunología , Distribución TisularRESUMEN
Monocytes are a distinct subset of myeloid cells with diverse functions in early inflammatory immune modulation. While previous studies have surveyed the role of miRNA regulation on different myeloid cell lines and primary cultures, the time-dependent kinetics of inflammatory stimulation on miRNA expression and the relationship between miRNA-to-target RNA expression have not been comprehensively profiled in monocytes. In this study, we use next-generation sequencing and RT-PCR assays to analyze the non-coding small RNA transcriptome of unstimulated and lipopolysaccharide (LPS)-stimulated monocytes at 6 and 24 hours. We identified a miRNA signature consisting of five mature miRNAs (hsa-mir-146a, hsa-mir-155, hsa-mir-9, hsa-mir-147b, and hsa-mir-193a) upregulated by LPS-stimulated monocytes after 6 hours and found that most miRNAs were also upregulated after 24 hours of stimulation. Only one miRNA gene was down-regulated and no other small RNAs were found dysregulated in monocytes after LPS treatment. In addition, novel tRNA-derived fragments were also discovered in monocytes although none showed significant changes upon LPS stimulation. Interrogation of validated miRNA targets by transcriptomic analysis revealed that absolute expression of most miRNA targets implicating in innate immune response decreased over time in LPS-stimulated monocytes although their expression patterns along the treatment were heterogeneous. Our findings reveal a potential role by which selective miRNA upregulation and stable expression of other small RNAs enable monocytes to develop finely tuned cellular responses during acute inflammation.
Asunto(s)
Perfilación de la Expresión Génica/métodos , Lipopolisacáridos/farmacología , MicroARNs/genética , Monocitos/metabolismo , Regulación de la Expresión Génica/efectos de los fármacos , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Monocitos/efectos de los fármacos , Análisis de Secuencia de ARNRESUMEN
The basic helix-loop-helix transcription factor Olig1 promotes oligodendrocyte maturation and is required for myelin repair. We characterized an Olig1-regulated G protein-coupled receptor, GPR17, whose function is to oppose the action of Olig1. Gpr17 was restricted to oligodendrocyte lineage cells, but was downregulated during the peak period of myelination and in adulthood. Transgenic mice with sustained Gpr17 expression in oligodendrocytes exhibited stereotypic features of myelinating disorders in the CNS. Gpr17 overexpression inhibited oligodendrocyte differentiation and maturation both in vivo and in vitro. Conversely, Gpr17 knockout mice showed early onset of oligodendrocyte myelination. The opposing action of Gpr17 on oligodendrocyte maturation reflects, at least partially, upregulation and nuclear translocation of the potent oligodendrocyte differentiation inhibitors ID2/4. Collectively, these findings suggest that GPR17 orchestrates the transition between immature and myelinating oligodendrocytes via an ID protein-mediated negative regulation and may serve as a potential therapeutic target for CNS myelin repair.
Asunto(s)
Enfermedades Desmielinizantes/metabolismo , Enfermedades Desmielinizantes/fisiopatología , Proteínas del Tejido Nervioso/fisiología , Receptores Acoplados a Proteínas G/fisiología , Animales , Encéfalo/citología , Células Cultivadas , Inmunoprecipitación de Cromatina/métodos , Modelos Animales de Enfermedad , Embrión de Mamíferos , Encefalomielitis Autoinmune Experimental/patología , Encefalomielitis Autoinmune Experimental/fisiopatología , Femenino , Proteínas Fluorescentes Verdes/genética , Humanos , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Esclerosis Múltiple/genética , Esclerosis Múltiple/metabolismo , Esclerosis Múltiple/patología , Proteínas del Tejido Nervioso/deficiencia , Oligodendroglía , Nervio Óptico/citología , Ratas , Ratas Endogámicas F344 , Receptores Acoplados a Proteínas G/deficiencia , Médula Espinal/citología , Células Madre , Factores de Tiempo , Transfección/métodosRESUMEN
Butyrophilin-like 2 (BTNL2) is a butyrophilin family member with homology to the B7 costimulatory molecules, polymorphisms of which have been recently associated through genetic analyses to sporadic inclusion body myositis and sarcoidosis. We have characterized the full structure, expression, and function of BTNL2. Structural analysis of BTNL2 shows a molecule with an extracellular region containing two sets of two Ig domains, a transmembrane region, and a previously unreported cytoplasmic tail. Unlike most other butyrophilin members, BTNL2 lacks the prototypical B30.2 ring domain. TaqMan and Northern blot analysis indicate BTNL2 is predominantly expressed in digestive tract tissues, in particular small intestine and Peyer's patches. Immunohistochemistry with BTNL2-specific Abs further localizes BTNL2 to epithelial and dendritic cells within these tissues. Despite its homology to the B7 family, BTNL2 does not bind any of the known B7 family receptors such as CD28, CTLA-4, PD-1, ICOS, or B and T lymphocyte attenuator. Because of its localization in the gut and potential role in the immune system, BTNL2 expression was analyzed in a mouse model of inflammatory bowel disease. BTNL2 is overexpressed during both the asymptomatic and symptomatic phase of the Mdr1a knockout model of spontaneous colitis. In functional assays, soluble BTNL2-Fc protein inhibits the proliferation of murine CD4(+) T cells from the spleen, mesenteric lymph node, and Peyer's patch. In addition, BTNL2-Fc reduces proliferation and cytokine production from T cells activated by anti-CD3 and B7-related protein 1. These data suggest a role for BTNL2 as a negative costimulatory molecule with implications for inflammatory disease.