RESUMEN
Cytokines related to tumor necrosis factor (TNF) provide a communication network essential for coordinating multiple cell types into an effective host defense system against pathogens and malignant cells. The pathways controlled by the TNF superfamily differentiate both innate and adaptive immune cells and modulate stromal cells into microenvironments conducive to host defenses. Members of the TNF receptor superfamily activate diverse cellular functions from the production of type 1 interferons to the modulation of survival of antigen-activated T cells. Here, we focus attention on the subset of TNF superfamily receptors encoded in the immune response locus in chromosomal region 1p36. Recent studies have revealed that these receptors use diverse mechanisms to either co-stimulate or restrict immune responses. Translation of the fundamental mechanisms of TNF superfamily is leading to the design of therapeutics that can alter pathogenic processes in several autoimmune diseases or promote immunity to tumors.
Asunto(s)
Enfermedades Autoinmunes/inmunología , Trastornos de los Cromosomas/genética , Inmunoterapia/métodos , Neoplasias/inmunología , Receptor Cross-Talk , Receptores del Factor de Necrosis Tumoral/metabolismo , Linfocitos T/inmunología , Inmunidad Adaptativa , Animales , Deleción Cromosómica , Cromosomas Humanos Par 1/genética , Humanos , Inmunidad Innata , Inmunoterapia/tendencias , Activación de Linfocitos , Neurogénesis/genética , Transducción de SeñalRESUMEN
γδ T cells rapidly secrete inflammatory cytokines at barrier sites that aid in protection from pathogens, but mechanisms limiting inflammatory damage remain unclear. We found that retinoid-related orphan receptor gamma-t (RORγt) and interleukin-7 (IL-7) influence γδ T cell homeostasis and function by regulating expression of the inhibitory receptor, B and T lymphocyte attenuator (BTLA). The transcription factor RORγt, via its activating function-2 domain, repressed Btla transcription, whereas IL-7 increased BTLA levels on the cell surface. BTLA expression limited γδ T cell numbers and sustained normal γδ T cell subset frequencies by restricting IL-7 responsiveness and expansion of the CD27(-)RORγt(+) population. BTLA also negatively regulated IL-17 and TNF production in CD27(-) γδ T cells. Consequently, BTLA-deficient mice exhibit enhanced disease in a γδ T cell-dependent model of dermatitis, whereas BTLA agonism reduced inflammation. Therefore, by coordinating expression of BTLA, RORγt and IL-7 balance suppressive and activation stimuli to regulate γδ T cell homeostasis and inflammatory responses.
Asunto(s)
Homeostasis , Inflamación , Receptores Inmunológicos/metabolismo , Linfocitos T/metabolismo , Animales , Células Cultivadas , Modelos Animales de Enfermedad , Citometría de Flujo , Eliminación de Gen , Humanos , Ratones , Ratones Endogámicos C57BL , Receptores de Antígenos de Linfocitos T gamma-delta/inmunología , Receptores Inmunológicos/genética , Linfocitos T/inmunologíaRESUMEN
The human cytomegalovirus opening reading frame UL144 is an ortholog of the TNF receptor superfamily member, herpesvirus entry mediator (HVEM; TNFRSF14). HVEM binds the TNF ligands, LIGHT and LTa; the immunoglobulin inhibitory receptor, B and T lymphocyte attenuator (BTLA); and the natural killer cell-activating receptor CD160. However, UL144 selectively binds BTLA, avoiding activation of inflammatory signaling initiated by CD160 in natural killer cells. BTLA and CD160 cross-compete for binding HVEM, but the structural basis for the ligand selectivity by UL144 and how it acts as an anti-inflammatory agonist remains unclear. Here, we modeled the UL144 structure and characterized its binding with BTLA. The UL144 structure was predicted to closely mimic the surface of HVEM, and we also found that both HVEM and UL144 bind a common epitope of BTLA, whether engaged in trans or in cis, that is shared with a BTLA antibody agonist. On the basis of the UL144 selectivity, we engineered a BTLA-selective HVEM protein to understand the basis for ligand selectivity and BTLA agonism to develop novel anti-inflammatory agonists. This HVEM mutein did not bind CD160 or TNF ligands but did bind BTLA with 10-fold stronger affinity than wild-type HVEM and retained potent inhibitory activity that reduced T-cell receptor, B-cell receptor, and interferon signaling in B cells. In conclusion, using a viral immune evasion strategy that shows broad immune-ablating activity, we have identified a novel anti-inflammatory BTLA-selective agonist.
Asunto(s)
Linfocitos B/metabolismo , Células Asesinas Naturales/metabolismo , Glicoproteínas de Membrana/metabolismo , Modelos Moleculares , Receptores Inmunológicos/agonistas , Miembro 14 de Receptores del Factor de Necrosis Tumoral/metabolismo , Linfocitos T/metabolismo , Proteínas Virales/metabolismo , Sustitución de Aminoácidos , Antiinflamatorios no Esteroideos/química , Antiinflamatorios no Esteroideos/metabolismo , Antiinflamatorios no Esteroideos/farmacología , Antígenos CD/química , Antígenos CD/genética , Antígenos CD/metabolismo , Linfocitos B/citología , Linfocitos B/efectos de los fármacos , Linfocitos B/inmunología , Sitios de Unión , Línea Celular Tumoral , Diseño de Fármacos , Proteínas Ligadas a GPI/química , Proteínas Ligadas a GPI/genética , Proteínas Ligadas a GPI/metabolismo , Células HEK293 , Humanos , Células Asesinas Naturales/citología , Células Asesinas Naturales/efectos de los fármacos , Células Asesinas Naturales/inmunología , Cinética , Ligandos , Glicoproteínas de Membrana/química , Glicoproteínas de Membrana/genética , Mutación , Conformación Proteica , Ingeniería de Proteínas , Dominios y Motivos de Interacción de Proteínas , Receptores Inmunológicos/química , Receptores Inmunológicos/genética , Receptores Inmunológicos/metabolismo , Miembro 14 de Receptores del Factor de Necrosis Tumoral/química , Miembro 14 de Receptores del Factor de Necrosis Tumoral/genética , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/metabolismo , Proteínas Recombinantes de Fusión/farmacología , Linfocitos T/citología , Linfocitos T/efectos de los fármacos , Linfocitos T/inmunología , Proteínas Virales/química , Proteínas Virales/genéticaRESUMEN
The interaction between B- and T-lymphocyte attenuator (BTLA), an inhibitory receptor whose extracellular domain belongs to the immunoglobulin superfamily, and herpesvirus-entry mediator (HVEM), a co-stimulatory tumour-necrosis factor receptor, is unique in that it is the only receptor-ligand interaction that directly bridges these two families of receptors. This interaction has raised many questions about how receptors from two different families could interact and what downstream signalling events might occur as a result of receptor ligation. As we discuss, recent studies show that engagement of HVEM with its endogenous ligand (LIGHT) from the tumour-necrosis factor family induces a powerful immune response, whereas HVEM interactions with BTLA negatively regulate T-cell responses.
Asunto(s)
Receptores Inmunológicos/inmunología , Receptores del Factor de Necrosis Tumoral/inmunología , Receptores Virales/inmunología , Animales , Enfermedad , Humanos , Ligandos , Unión Proteica , Receptores Inmunológicos/antagonistas & inhibidores , Receptores Inmunológicos/química , Receptores del Factor de Necrosis Tumoral/antagonistas & inhibidores , Receptores del Factor de Necrosis Tumoral/química , Receptores del Factor de Necrosis Tumoral/clasificación , Miembro 14 de Receptores del Factor de Necrosis Tumoral , Receptores Virales/antagonistas & inhibidores , Receptores Virales/química , Receptores Virales/clasificación , Transducción de SeñalRESUMEN
Lymphocyte activation is regulated by costimulatory and inhibitory receptors, of which both B and T lymphocyte attenuator (BTLA) and CD160 engage herpesvirus entry mediator (HVEM). Notably, it remains unclear how HVEM functions with each of its ligands during immune responses. In this study, we show that HVEM specifically activates CD160 on effector NK cells challenged with virus-infected cells. Human CD56(dim) NK cells were costimulated specifically by HVEM but not by other receptors that share the HVEM ligands LIGHT, Lymphotoxin-α, or BTLA. HVEM enhanced human NK cell activation by type I IFN and IL-2, resulting in increased IFN-γ and TNF-α secretion, and tumor cell-expressed HVEM activated CD160 in a human NK cell line, causing rapid hyperphosphorylation of serine kinases ERK1/2 and AKT and enhanced cytolysis of target cells. In contrast, HVEM activation of BTLA reduced cytolysis of target cells. Together, our results demonstrate that HVEM functions as a regulator of immune function that activates NK cells via CD160 and limits lymphocyte-induced inflammation via association with BTLA.
Asunto(s)
Antígenos CD/metabolismo , Células Asesinas Naturales/inmunología , Receptores Inmunológicos/metabolismo , Miembro 14 de Receptores del Factor de Necrosis Tumoral/metabolismo , Antígeno CD56/metabolismo , Línea Celular , Activación Enzimática , Proteínas Ligadas a GPI/metabolismo , Células HEK293 , Humanos , Inflamación , Interferón Tipo I/metabolismo , Interferón gamma/metabolismo , Interleucina-2/metabolismo , Células Asesinas Naturales/metabolismo , Activación de Linfocitos , Linfotoxina-alfa/metabolismo , Proteína Quinasa 1 Activada por Mitógenos/metabolismo , Proteína Quinasa 3 Activada por Mitógenos/metabolismo , Fosforilación , Proteínas Proto-Oncogénicas c-akt/metabolismo , Miembro 14 de Receptores del Factor de Necrosis Tumoral/inmunología , Transducción de Señal , Linfocitos T/inmunología , Miembro 14 de la Superfamilia de Ligandos de Factores de Necrosis Tumoral/metabolismo , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
Innate lymphoid cells encompass a diverse array of lymphocyte subsets with unique phenotype that initiate inflammation and provide host defenses in specific microenvironments. In this study, we identify a rare human CD4(+)CD3(-) innate-like lymphoid population with high TNF expression that is enriched in blood from patients with rheumatoid arthritis. These CD4(+)CD3(-) cells belong to the T cell lineage, but the lack of AgR at the cell surface renders them nonresponsive to TCR-directed stimuli. By developing a culture system that sustains survival, we show that CD4(+)CD3(-) innate-like T cells display IL-7-dependent induction of surface lymphotoxin-αß, demonstrating their potential to modify tissue microenvironments. Furthermore, expression of CCR6 on the CD4(+)CD3(-) population defines a CD127(high) subset that is highly responsive to IL-7. This CD4(+)CD3(-) population is enriched in the peripheral blood from rheumatoid arthritis patients, suggesting a link to their involvement in chronic inflammatory disease.
Asunto(s)
Artritis Reumatoide/metabolismo , Complejo CD3/metabolismo , Linfocitos T CD4-Positivos/metabolismo , Heterotrímero de Linfotoxina alfa1 y beta2/metabolismo , Factores de Necrosis Tumoral/metabolismo , Adulto , Anciano , Animales , Artritis Reumatoide/inmunología , Linfocitos T CD4-Positivos/inmunología , Línea Celular , Femenino , Células HEK293 , Proteínas de Homeodominio/genética , Humanos , Inflamación , Interleucina-7/metabolismo , Subunidad alfa del Receptor de Interleucina-7/metabolismo , Activación de Linfocitos/inmunología , Recuento de Linfocitos , Heterotrímero de Linfotoxina alfa1 y beta2/inmunología , Masculino , Ratones , Ratones Noqueados , Persona de Mediana Edad , Receptores CCR6/metabolismoRESUMEN
The Btla inhibitory receptor limits innate and adaptive immune responses, both preventing the development of autoimmune disease and restraining anti-viral and anti-tumor responses. It remains unclear how the functions of Btla in diverse lymphocytes contribute to immunoregulation. Here, we show that Btla inhibits activation of genes regulating metabolism and cytokine signaling, including Il6 and Hif1a, indicating a regulatory role in humoral immunity. Within mucosal Peyer's patches, we find T-cell-expressed Btla-regulated Tfh cells, while Btla in T or B cells regulates GC B cell numbers. Treg-expressed Btla is required for cell-intrinsic Treg homeostasis that subsequently controls GC B cells. Loss of Btla in lymphocytes results in increased IgA bound to intestinal bacteria, correlating with altered microbial homeostasis and elevations in commensal and pathogenic bacteria. Together our studies provide important insights into how Btla functions as a checkpoint in diverse conventional and regulatory lymphocyte subsets to influence systemic immune responses.
Asunto(s)
Inmunidad Humoral , Linfocitos T Reguladores , Linfocitos B , Mucosa Intestinal , Transducción de SeñalRESUMEN
Neuronal regulation of diverse physiological functions requires complex molecular interactions in innervated tissues to maintain proper organ function. Here we show that loss of the neuronal cell surface adhesion/recognition molecule Contactin-1 (Cntn1) directly impairs intestinal function causing wasting that subsequently results in global immune defects. Loss of Cntn1 results in hematologic alterations and changes in blood metabolites associated with malnourishment. We found thymus and spleen of Cntn1-deficient animals atrophied with severe reductions in lymphocyte populations. Elevated thymic Gilz expression indicated ongoing glucocorticoid signaling in Cntn1-deficient animals, consistent with the malnourishment phenotype. Intestinal Contactin-1 was localized to neurons in the villi and the submucosal/myenteric plexus that innervates smooth muscle. Loss of Cntn1 was associated with reduced intestinal Bdnf and Adrb2, indicating reduced neuromuscular crosstalk. Additionally, loss of Cntn1 resulted in reduced recruitment of CD3+ T cells to villi within the small intestine. Together, these data illustrate the critical role of Contactin-1 function within the gut, and how this is required for normal systemic immune functions.
Asunto(s)
Contactina 1/genética , Mucosa Intestinal/inmunología , Mucosa Intestinal/inervación , Animales , Biomarcadores , Recuento de Células Sanguíneas , Análisis Químico de la Sangre , Citometría de Flujo , Perfilación de la Expresión Génica , Glucocorticoides/metabolismo , Homeostasis , Mucosa Intestinal/metabolismo , Mucosa Intestinal/patología , Ratones , Ratones Noqueados , Fenotipo , Transducción de Señal , Bazo/inmunología , Bazo/metabolismo , Bazo/patología , Timo/inmunología , Timo/metabolismo , Timo/patologíaRESUMEN
Somatic mutations in cancer cells may influence tumor growth, survival, or immune interactions in their microenvironment. The tumor necrosis factor receptor family member HVEM (TNFRSF14) is frequently mutated in cancers and has been attributed a tumor suppressive role in some cancer contexts. HVEM functions both as a ligand for the lymphocyte checkpoint proteins BTLA and CD160, and as a receptor that activates NF-κB signaling pathways in response to BTLA and CD160 and the TNF ligands LIGHT and LTα. BTLA functions to inhibit lymphocyte activation, but has also been ascribed a role in stimulating cell survival. CD160 functions to co-stimulate lymphocyte function, but has also been shown to activate inhibitory signaling in CD4+ T cells. Thus, the role of HVEM within diverse cancers and in regulating the immune responses to these tumors is likely context specific. Additionally, development of therapeutics that target proteins within this network of interacting proteins will require a deeper understanding of how these proteins function in a cancer-specific manner. However, the prominent role of the HVEM network in anti-cancer immune responses indicates a promising area for drug development.
Asunto(s)
Neoplasias/genética , Neoplasias/inmunología , Miembro 14 de Receptores del Factor de Necrosis Tumoral/genética , Miembro 14 de Receptores del Factor de Necrosis Tumoral/inmunología , Linfocitos T/inmunología , Genes Supresores de Tumor , Humanos , Activación de Linfocitos , Mutación , Subunidad p50 de NF-kappa B/inmunología , Subunidad p50 de NF-kappa B/metabolismo , Neoplasias/metabolismo , Neoplasias/patología , Miembro 14 de Receptores del Factor de Necrosis Tumoral/metabolismo , Transducción de Señal/genética , Transducción de Señal/inmunología , Microambiente TumoralRESUMEN
Lymphocytes of the gamma delta (γδ) T-cell lineage are evolutionary conserved and although they express rearranged antigen-specific receptors, a large proportion respond as innate effectors. γδ T-cells are poised to combat infection by responding rapidly to cytokine stimuli similar to innate lymphoid cells. This potential to initiate strong inflammatory responses necessitates that inhibitory signals are balanced with activation signals. Here, we discuss some of the key mechanisms that regulate the development, activation, and inhibition of innate γδ T-cells in light of recent evidence that the inhibitory immunoglobulin-superfamily member B and T lymphocyte attenuator restricts their differentiation and effector function.
RESUMEN
The herpesvirus entry mediator (HVEM; TNFRSF14) can activate either proinflammatory or inhibitory signaling pathways. HVEM engages two distinct types of ligands, the canonical TNF-related cytokines, LIGHT and Lymphotoxin-α, and the Ig-related membrane proteins, BTLA (B and T lymphocyte attenuator) and CD160. Recent evidence indicates that the signal generated by HVEM depends on the context of its ligands expressed in trans or in cis. HVEM engagement by all of its ligands in trans initiates bidirectional signaling. In contrast, naïve T cells coexpress BTLA and HVEM forming a cis-complex that interferes with the activation of HVEM by extraneous ligands in the surrounding microenvironment. The HVEM Network is emerging as a key survival system for effector and memory T cells in mucosal tissues.
Asunto(s)
Herpes Simple/inmunología , Inmunidad Innata , Membrana Mucosa/inmunología , Receptores Inmunológicos/inmunología , Miembro 14 de Receptores del Factor de Necrosis Tumoral/inmunología , Transducción de Señal/inmunología , Simplexvirus/inmunología , Linfocitos T/inmunología , Animales , Antígenos CD/inmunología , Antígenos CD/metabolismo , Microambiente Celular , Proteínas Ligadas a GPI/inmunología , Proteínas Ligadas a GPI/metabolismo , Herpes Simple/virología , Humanos , Evasión Inmune , Ligandos , Activación de Linfocitos/inmunología , Linfotoxina-alfa/inmunología , Linfotoxina-alfa/metabolismo , Ratones , Ratones Noqueados , Membrana Mucosa/citología , Membrana Mucosa/metabolismo , Membrana Mucosa/virología , Receptores Inmunológicos/metabolismo , Miembro 14 de Receptores del Factor de Necrosis Tumoral/metabolismo , Linfocitos T/citología , Linfocitos T/metabolismo , Linfocitos T/virologíaRESUMEN
Recent reports suggested that Delta1, 4 and Jagged1, 2 possessed the ability to instruct CD4(+) T cell into selection of Th1 or Th2 fates, respectively, although the underlying mechanism endowing the cleaved Notch receptor with memory of ligand involved in its activation remains elusive. To examine this, we prepared artificial antigen-presenting cells expressing either DLL1 or Jag1. Although both ligands were efficient in inducing Notch2 cleavage and activation in CD4(+) T or reporter cells, the presence of Lunatic Fringe in CD4(+) T cells inhibited Jag1 activation of Notch1 receptor. Neither ligand could induce Th1 or Th2 fate choice independently of cytokines or redirect cytokine-driven Th1 or Th2 development. Instead, we find that Notch ligands only augment cytokine production during T cell differentiation in the presence of polarizing IL-12 and IL-4. Moreover, the differentiation choices of naïve CD4(+) T cells lacking gamma-secretase, RBP-J, or both in response to polarizing cytokines revealed that neither presenilin proteins nor RBP-J were required for cytokine-induced Th1/Th2 fate selection. However, presenilins facilitate cellular proliferation and cytokine secretion in an RBP-J (and thus, Notch) independent manner. The controversies surrounding the role of Notch and presenilins in Th1/Th2 polarization may reflect their role as genetic modifiers of T-helper cells differentiation.
Asunto(s)
Citocinas/metabolismo , Presenilinas/metabolismo , Receptores Notch/metabolismo , Células TH1/metabolismo , Células Th2/metabolismo , Animales , Células CHO , Diferenciación Celular , Linaje de la Célula , Cricetinae , Cricetulus , Interleucina-12/metabolismo , Interleucina-4/metabolismo , Ratones , Ratones Endogámicos C57BLRESUMEN
Herpesviruses have evolved numerous strategies to subvert host immune responses so they can coexist with their host species. These viruses 'co-opt' host genes for entry into host cells and then express immunomodulatory genes, including mimics of members of the tumour-necrosis factor (TNF) superfamily, that initiate and alter host-cell signalling pathways. TNF superfamily members have crucial roles in controlling herpesvirus infection by mediating the direct killing of infected cells and by enhancing immune responses. Despite these strong immune responses, herpesviruses persist in a latent form, which suggests a dynamic relationship between the host immune system and the virus that results in a balance between host survival and viral control.
Asunto(s)
Infecciones por Herpesviridae/inmunología , Herpesviridae/inmunología , Receptores del Factor de Necrosis Tumoral/inmunología , Factores de Necrosis Tumoral/inmunología , Animales , Infecciones por Herpesviridae/virología , HumanosRESUMEN
The B and T lymphocyte attenuator (BTLA) appears to act as a negative regulator of T cell activation and growth. BTLA specifically interacts with herpesvirus entry mediator (HVEM), a member of the TNFR family. Herein, we have undertaken surface plasmon resonance studies to quantitatively assess BTLA and HVEM ectodomain interactions. We find that soluble BALB/cJ BTLA engages HVEM with an equilibrium affinity of 0.97+/-0.19 microM while the C57BL/6 BTLA binds slightly better with an equilibrium affinity of 0.42+/-0.06 microM. Despite its lower affinity for HVEM, the kinetic half-life of BALB/cJ BTLA complexes are twice as long as observed for C57BL/6 BTLA (4 vs 2 s). To further explore these interactions, we solved the crystal structure of a murine BTLA (BALB/cJ) ectodomain at 1.8-A resolution, revealing a beta sandwich fold with strong similarity to I-set members of the Ig superfamily. Using a structure-based mutagenesis strategy, we then examined the individual contributions of 26 BTLA surface-exposed residues toward HVEM binding. Four single-site substitutions were identified that decrease HVEM binding below detectable levels and two that decrease binding by more than half. All six of these cluster at the edge of the beta sandwich in a membrane distal patch formed primarily from the A and G strands. This patch falls within the contacting surface recently revealed in the crystal structure of the human BTLA-HVEM cocomplex. The critical binding residues identified here are highly conserved across species, suggesting that BTLA employs a conserved binding mode for HVEM recognition.
Asunto(s)
Receptores Inmunológicos/química , Miembro 14 de Receptores del Factor de Necrosis Tumoral/química , Secuencia de Aminoácidos , Sustitución de Aminoácidos , Animales , Secuencia Conservada , Cristalografía por Rayos X , Análisis Mutacional de ADN , Perros , Humanos , Ratones , Datos de Secuencia Molecular , Conformación Proteica , Mapeo de Interacción de Proteínas , Ratas , Receptores Inmunológicos/genética , Resonancia por Plasmón de SuperficieRESUMEN
B and T lymphocyte attenuator (BTLA; CD272) can deliver inhibitory signals to B and T cells upon binding its ligand herpesvirus entry mediator. Because CD28, CTLA-4, programmed death-1, and ICOS regulate the development of acute graft-vs-host disease (GVHD), we wished to assess if BTLA also played a role in this T cell-mediated response. In the nonirradiated parental-into-F1 model of acute GVHD, BTLA+/+ and BTLA-/- donor lymphocytes showed equivalent engraftment and expansion during the first week of the alloresponse. Unexpectedly, BTLA-/- donor T cells failed to sustain GVHD, showing a decline in surviving donor cell numbers beginning at day 9 and greatly reduced by day 11. Similarly, inhibition of BTLA-herpesvirus entry mediator engagement by in vivo administration of a blocking anti-BTLA Ab also caused reduced survival of donor cells. Microarray analysis revealed several genes that were differentially expressed by BTLA-/- and BTLA+/+ donor CD4+ T cells preceding the decline in BTLA-/- donor T cells. Several genes influencing Th cell polarization were differentially expressed by BTLA+/+ and BTLA-/- donor cells. Additionally, the re-expression of the IL-7Ralpha subunit that occurs in BTLA+/+ donor cells after 1 wk of in vivo allostimulation was not observed in BTLA-/- donor CD4+ cells. The striking loss of BTLA-/- T cells in this model indicates a role for BTLA activity in sustaining CD4+ T cell survival under the conditions of chronic stimulation in the nonirradiated parental-into-F1 GVHD.
Asunto(s)
Subgrupos de Linfocitos B/citología , Subgrupos de Linfocitos B/inmunología , Isoantígenos/inmunología , Activación de Linfocitos/inmunología , Receptores Inmunológicos/fisiología , Subgrupos de Linfocitos T/citología , Subgrupos de Linfocitos T/inmunología , Animales , Anticuerpos Monoclonales/administración & dosificación , Supervivencia Celular/inmunología , Enfermedad Crónica , Modelos Animales de Enfermedad , Supervivencia de Injerto/inmunología , Enfermedad Injerto contra Huésped/inmunología , Enfermedad Injerto contra Huésped/metabolismo , Enfermedad Injerto contra Huésped/patología , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Endogámicos MRL lpr , Ratones Noqueados , Receptores Inmunológicos/deficiencia , Receptores Inmunológicos/genética , Receptores Inmunológicos/inmunologíaRESUMEN
The T cell Ig domain and mucin domain (TIM) proteins form a conserved family of transmembrane cell-surface glycoproteins expressed by a variety of tissues. Each TIM protein contains a single V-type Ig domain, a glycosylated mucin-like domain, a transmembrane domain and a cytoplasmic domain. TIM proteins recognize a diverse array of ligands, including H-ferritin, galectin-9 as well as other TIM family members. In this study, we demonstrate that the Ig domains of murine TIM-1, -3 and -4 display calcium-dependent binding to ligands expressed by murine splenocytes and several non-murine cell lines, indicating non-species-specific ligand recognition. Further, the intrafamilial interaction of various TIM family Ig domains with surface-expressed TIM-1 and TIM-4 requires an intact TIM-1 and TIM-4 glycosylated mucin stalk. Importantly, we also uncovered the previously unrecognized potential for homotypic TIM interactions in forming ligand-receptor pairs. Using a glycan array screen, we identified the novel capacity of the TIM-3 Ig domain to recognize specific carbohydrate moieties, suggesting a role for carbohydrate modification along with protein epitopes in TIM ligand recognition. Identification of the carbohydrate-binding capacity of TIM proteins helps explain the diversity of ligands recognized by this family and adds to our understanding of homotypic and heterotypic interactions between TIM family members.
Asunto(s)
Proteínas de la Membrana/metabolismo , Polisacáridos/metabolismo , Receptores Virales/metabolismo , Animales , Células CHO , Calcio/metabolismo , Calcio/farmacología , Línea Celular , Sulfatos de Condroitina/metabolismo , Cricetinae , Cricetulus , Ácido Egtácico/farmacología , Heparitina Sulfato/metabolismo , Receptor Celular 1 del Virus de la Hepatitis A , Receptor 2 Celular del Virus de la Hepatitis A , Leucocitos Mononucleares/metabolismo , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/metabolismo , Proteínas de la Membrana/genética , Ratones , Ratones Endogámicos BALB C , Fragmentos de Péptidos/genética , Fragmentos de Péptidos/metabolismo , Polisacáridos/química , Unión Proteica/efectos de los fármacos , Receptores Virales/genética , Proteínas Recombinantes de Fusión/metabolismo , Bazo/citología , Spodoptera , TransfecciónRESUMEN
B and T lymphocyte attenuator (BTLA) was initially identified as expressed on Th1 cells and B cells, but recently reported to be expressed by macrophages, dendritic cells, and NK cells as well. To address this discrepancy we generated a panel of BTLA-specific mAbs and characterized BTLA expression under various activation conditions. We report the existence of three distinct BTLA alleles among 23 murine strains, differing both in Ig domain structure and cellular distribution of expression on lymphoid subsets. The BALB/c and MRL/lpr alleles differ at one amino acid residue, but C57BL/6 has nine additional differences and alters the predicted cysteine bonding pattern. The BALB/c BTLA allele is also expressed by B cells, T cells, and dendritic cells, but not macrophages or NK cells. However, C57BL/6 BTLA is expressed on CD11b+ macrophages and NK cells. Finally, in CD4+ T cells, BTLA is expressed most highly following Ag-specific induction of anergy in vivo, and unlike programmed death-1 and CTLA-4, not expressed by CD25+ regulatory T cells. These results clarify discrepancies regarding BTLA expression, suggest that structural and expression polymorphisms be considered when analyzing BTLA in various murine backgrounds, and indicate a possible role in anergic CD4+ T cells.
Asunto(s)
Linfocitos T CD4-Positivos/inmunología , Receptores Inmunológicos/química , Receptores Inmunológicos/genética , Alelos , Secuencia de Aminoácidos , Animales , Anticuerpos Monoclonales , Linfocitos B/inmunología , Secuencia de Bases , Anergia Clonal , Cricetinae , ADN Complementario/genética , Expresión Génica , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Endogámicos MRL lpr , Ratones Noqueados , Datos de Secuencia Molecular , Estructura Molecular , Polimorfismo Genético , Receptores Inmunológicos/biosíntesis , Receptores Inmunológicos/deficiencia , Homología de Secuencia de Aminoácido , Especificidad de la EspecieRESUMEN
B and T lymphocyte attenuator (BTLA) provides an inhibitory signal to B and T cells. Previously, indirect observations suggested that B7x was a ligand for BTLA. Here we show that BTLA does not bind B7x; instead, we identify herpesvirus entry mediator (HVEM) as the unique BTLA ligand. BTLA bound the most membrane-distal cysteine-rich domain of HVEM, distinct from regions where the ligands LIGHT and lymphotoxin-alpha bound HVEM. HVEM induced BTLA tyrosine phosphorylation and association of the tyrosine phosphatase SHP-2 and repressed antigen-driven T cell proliferation, providing an example of reverse signaling to a non-tumor necrosis factor family ligand. The conservation of the BTLA-HVEM interaction between mouse and human suggests that this system is an important pathway regulating lymphocyte activation and/or homeostasis in the immune response.
Asunto(s)
Activación de Linfocitos , Receptores Inmunológicos/metabolismo , Receptores del Factor de Necrosis Tumoral/metabolismo , Receptores Virales/metabolismo , Animales , Línea Celular , Humanos , Ligandos , Ratones , Ratones Endogámicos BALB C , Receptores Inmunológicos/fisiología , Miembro 14 de Receptores del Factor de Necrosis Tumoral , Proteínas Recombinantes de Fusión/metabolismo , Proteínas Recombinantes de Fusión/farmacologíaRESUMEN
T helper type 1 (T(H)1) cell development involves interferon-gamma (IFN-gamma) signaling through signal transducer and activator of transcription 1 (STAT1) and interleukin-12 (IL-12) signaling through STAT4 activation. We examined here T-bet regulation and evaluated the actions of T-bet in STAT1- and STAT4-dependent T(H)1 development processes. We found that T-bet expression during T cell activation was strongly dependent on IFN-gamma signaling and STAT1 activation, but was independent of STAT4. Ectopic T-bet expression strongly increased IFN-gamma production in T(H)2 cells activated by PMA-ionomycin, but weakly increased IFN-gamma production in T(H)2 cells stimulated by IL-12 IL-18 or OVA peptide antigen-presenting cell stimulation. In contrast, IL-12 IL-18 induced IFN-gamma production remained STAT4-dependent despite ectopic T-bet expression. Ectopic T-bet expression selectively induced expression of IL-12Rbeta2, but not IL-18Ralpha, in wild-type and STAT1(-/-) T(H)2 cells, but did not extinguish expression of GATA-3 and T(H)2 cytokines. Finally, ectopic T-bet did not directly induce expression of endogenous T- bet independently of IFN-gamma or STAT1. Thus, T-bet is induced by IFN-gamma and STAT1 signaling during T cell activation. In addition, T-bet mediates STAT1-dependent processes of T(H)1 development, including the induction of IL-12Rbeta2.
Asunto(s)
Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD4-Positivos/metabolismo , Proteínas de Unión al ADN/metabolismo , Receptores de Interleucina/metabolismo , Transactivadores/metabolismo , Factores de Transcripción/metabolismo , Animales , Linfocitos T CD4-Positivos/citología , Diferenciación Celular , Proteínas de Unión al ADN/deficiencia , Proteínas de Unión al ADN/genética , Interferón gamma/metabolismo , Interleucina-12/farmacología , Interleucina-18/farmacología , Activación de Linfocitos , Ratones , Ratones Noqueados , Ratones Transgénicos , Receptores de Interleucina-12 , Factor de Transcripción STAT1 , Factor de Transcripción STAT4 , Transducción de Señal , Proteínas de Dominio T Box , Células Th2/citología , Células Th2/inmunología , Células Th2/metabolismo , Transactivadores/deficiencia , Transactivadores/genética , Factores de Transcripción/genéticaRESUMEN
The third complementarity-determining region (CDR) of the TCR alpha and beta chains forms loops that engage amino acid residues of peptides complexed with MHC. This interaction is central to the specific discrimination of antigenic-peptide-MHC complexes by the TCR. The TCRbeta chain CDR3 loop is encoded by the Dbeta gene segment and flanking portions of the Vbeta and Jbeta gene segments. The joining of these gene segments is imprecise, leading to significant variability in the TCRbeta chain CDR3 loop length and amino acid composition. In marked contrast to other pairing antigen-receptor chains, the TCR beta and alpha chain CDR3 loop size distributions are relatively narrow and closely matched. Thus, pairing of TCR alpha and beta chains with relatively similar CDR3 loop sizes may be important for generating a functional repertoire of alpha beta TCR. Here we show that the TCRbeta chain CDR3 loop size distribution is minimally impacted by TCRbeta chain or alpha beta TCR selection during thymocyte development. Rather, this distribution is determined primarily at the level of variable-region gene assembly, and is critically dependent on unique features of the V(D)J recombination reaction that ensure Dbeta gene segment utilization.