RESUMEN
Expression of the signaling lymphocytic activation molecule (SLAM)-associated protein (SAP) is critical for the germinal center (GC) reaction and T cell-dependent antibody production. However, when SAP is expressed normally, the role of the associated SLAM family receptors (SFRs) in these processes is nebulous. Herein, we established that in the presence of SAP, SFRs suppressed the expansion of the GC reaction but facilitated the generation of antigen-specific B cells and antibodies. SFRs favored the generation of antigen-reactive B cells and antibodies by boosting expression of pro-survival effectors, such as the B cell antigen receptor (BCR) and Bcl-2, in activated GC B cells. The effects of SFRs on the GC reaction and T cell-dependent antibody production necessitated expression of multiple SFRs, both in T cells and in B cells. Hence, while in the presence of SAP, SFRs inhibit the GC reaction, they are critical for the induction of T cell-mediated humoral immunity by enhancing expression of pro-survival effectors in GC B cells.
Asunto(s)
Linfocitos B/citología , Linfocitos B/inmunología , Centro Germinal/citología , Inmunidad Humoral , Familia de Moléculas Señalizadoras de la Activación Linfocitaria/metabolismo , Animales , Anticuerpos/metabolismo , Formación de Anticuerpos/inmunología , Antígenos Helmínticos/metabolismo , Apoptosis , Médula Ósea/metabolismo , Recuento de Células , Ciclo Celular , Proliferación Celular , Supervivencia Celular , Relación Dosis-Respuesta Inmunológica , Inmunización , Cambio de Clase de Inmunoglobulina , Memoria Inmunológica , Ratones Noqueados , Nematospiroides dubius/fisiología , Células Plasmáticas/metabolismo , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Transducción de Señal , Familia de Moléculas Señalizadoras de la Activación Linfocitaria/deficiencia , Hipermutación Somática de Inmunoglobulina , Linfocitos T/citología , Linfocitos T/inmunología , Linfocitos T Colaboradores-Inductores/metabolismo , VacunaciónRESUMEN
Signalling lymphocyte activation molecule family member 9 (SLAMF9) is an orphan receptor of the CD2/SLAM family of leucocyte surface proteins. Examination of SLAMF9 expression and function indicates that SLAMF9 promotes inflammation by specialized subsets of antigen-presenting cells. Within healthy liver and circulating mouse peripheral blood mononuclear cells, SLAMF9 is expressed on CD11b+ , Ly6C- , CD11clow , F4/80low , MHC-II+ , CX3 CR1+ mononuclear phagocytes as well as plasmacytoid dendritic cells. In addition, SLAMF9 can be found on peritoneal B1 cells and small (F4/80low ), but not large (F4/80high ), peritoneal macrophages. Upon systemic challenge with Salmonella enterica Typhimurium, Slamf9-/- mice were impaired in their ability to clear the infection from the liver. In humans, SLAMF9 is up-regulated upon differentiation of monocytes into macrophages, and lipopolysaccharide stimulation of PMA-differentiated, SLAMF9 knockdown THP-1 cells showed an essential role of SLAMF9 in production of granulocyte-macrophage colony-stimulating factor, tumour necrosis factor-α, and interleukin-1ß. Taken together, these data implicate SLAMF9 in the initiation of inflammation and clearance of bacterial infection.
Asunto(s)
Células Dendríticas/inmunología , Interacciones Huésped-Patógeno/inmunología , Hígado/inmunología , Infecciones por Salmonella/inmunología , Salmonella typhimurium/inmunología , Familia de Moléculas Señalizadoras de la Activación Linfocitaria/inmunología , Animales , Linfocitos B/inmunología , Linfocitos B/microbiología , Diferenciación Celular , Células Dendríticas/efectos de los fármacos , Células Dendríticas/microbiología , Regulación de la Expresión Génica , Factor Estimulante de Colonias de Granulocitos y Macrófagos/genética , Factor Estimulante de Colonias de Granulocitos y Macrófagos/inmunología , Interacciones Huésped-Patógeno/genética , Humanos , Interleucina-1beta/genética , Interleucina-1beta/inmunología , Lipopolisacáridos/farmacología , Hígado/microbiología , Macrófagos/efectos de los fármacos , Macrófagos/inmunología , Macrófagos/microbiología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Monocitos/efectos de los fármacos , Monocitos/inmunología , Monocitos/microbiología , Infecciones por Salmonella/genética , Infecciones por Salmonella/microbiología , Salmonella typhimurium/patogenicidad , Transducción de Señal , Familia de Moléculas Señalizadoras de la Activación Linfocitaria/deficiencia , Familia de Moléculas Señalizadoras de la Activación Linfocitaria/genética , Células THP-1 , Factor de Necrosis Tumoral alfa/genética , Factor de Necrosis Tumoral alfa/inmunologíaRESUMEN
Classical signaling lymphocyte activating molecule (SLAM) family receptors are abundant within many types of immune cells, whereas the nonclassical SLAM family receptors SLAMF8 and SLAMF9, which uniquely lack cytoplasmic signaling motifs, are highly expressed by myeloid cells. Due to the potential redundancy, whether these two receptors regulate macrophage function remains largely unknown. Here, we show that SLAMF8 and SLAMF9 co-regulate macrophage-mediated liver inflammation. To overcome the redundancy, we generated mice that simultaneously lacked SLAMF8 and SLAMF9 using CRISPR-Cas9 technology. Although macrophage differentiation was not altered by the combined deficiency of SLAMF8 and SLAMF9, the loss of these two receptors significantly protected against lipopolysaccharide (LPS)-induced liver injury. SLAMF8 and SLAMF9 double-deficient mice had a prolonged survival rate and less infiltration of inflammatory cells. The depletion of macrophages using clodronate liposomes abolished the effects of SLAMF8 and SLAMF9 deficiencies on LPS-induced liver injury, which demonstrates that these receptors are required for macrophage activation following LPS challenge. Moreover, the deficiency of SLAMF8 and SLAMF9 suppressed the secretion of inflammatory cytokines by downregulating the expression of Toll-like receptor-4 (TLR4), a receptor that specifically binds LPS, which led to decreased mitogen-activated protein kinases (MAPK) signaling activation. Notably, combined injections of truncated extracellular SLAMF8 and SLAMF9 proteins significantly alleviated LPS-induced liver injury. Thus, our findings provide insights into the role of SLAMF8 and SLAMF9 in endotoxin-induced liver injury and suggest that SLAMF8 and SLAMF9 are potential therapeutic targets for acute hepatic injury.
Asunto(s)
Regulación hacia Abajo/genética , Hepatitis/etiología , Hepatitis/inmunología , Lipopolisacáridos/efectos adversos , Sistema de Señalización de MAP Quinasas/genética , Macrófagos/inmunología , Proteínas de la Membrana/deficiencia , Familia de Moléculas Señalizadoras de la Activación Linfocitaria/deficiencia , Receptor Toll-Like 4/metabolismo , Animales , Sistemas CRISPR-Cas , Diferenciación Celular/genética , Citocinas/metabolismo , Hepatitis/metabolismo , Hepatitis/mortalidad , Activación de Macrófagos/genética , Macrófagos/metabolismo , Proteínas de la Membrana/genética , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Células RAW 264.7 , Familia de Moléculas Señalizadoras de la Activación Linfocitaria/genética , Tasa de Supervivencia , TransfecciónRESUMEN
SLAMF9 belongs to the conserved lymphocytic activation molecule family (SLAMF). Unlike other SLAMs, which have been extensively studied, the role of SLAMF9 in the immune system remained mostly unexplored. By generating CRISPR/Cas9 SLAMF9 knockout mice, we analyzed the role of this receptor in plasmacytoid dendritic cells (pDCs), which preferentially express the SLAMF9 transcript and protein. These cells display a unique capacity to produce type I IFN and bridge between innate and adaptive immune response. Analysis of pDCs in SLAMF9-/- mice revealed an increase of immature pDCs in the bone marrow and enhanced accumulation of pDCs in the lymph nodes. In the periphery, SLAMF9 deficiency resulted in lower levels of the transcription factor SpiB, elevation of pDC survival, and attenuated IFN-α and TNF-α production. To define the role of SLAMF9 during inflammation, pDCs lacking SLAMF9 were followed during induced experimental autoimmune encephalomyelitis. SLAMF9-/- mice demonstrated attenuated disease and delayed onset, accompanied by a prominent increase of immature pDCs in the lymph node, with a reduced costimulatory potential and enhanced infiltration of pDCs into the central nervous system. These results suggest the crucial role of SLAMF9 in pDC differentiation, homeostasis, and function in the steady state and during experimental autoimmune encephalomyelitis.
Asunto(s)
Células Dendríticas/metabolismo , Enfermedad , Salud , Homeostasis , Familia de Moléculas Señalizadoras de la Activación Linfocitaria/metabolismo , Animales , Médula Ósea/metabolismo , Diferenciación Celular , Regulación de la Expresión Génica , Ganglios Linfáticos/metabolismo , Activación de Linfocitos/inmunología , Ratones Endogámicos C57BL , Ratones Noqueados , Receptores CCR5/metabolismo , Familia de Moléculas Señalizadoras de la Activación Linfocitaria/deficiencia , Transcriptoma/genéticaRESUMEN
Epstein-Barr virus (EBV) reactivation commonly occurs following sepsis, but the mechanisms underlying this are unknown. We utilized a murine EBV homolog (gHV) and the cecal ligation and puncture model of polymicrobial sepsis to study the impact of sepsis on gHV reactivation and CD8+ T cell immune surveillance following a septic insult. We observed a significant increase in the frequency of gHV-infected germinal center B cells on day 7 following sepsis. This increase in viral load was associated with a concomitant significant decrease in the frequencies of gHV-specific CD8+ T cells, as measured by class I MHC tetramers corresponding to the immunodominant viral epitopes. Phenotypic analysis revealed an increased frequency of gHV-specific CD8+ T cells expressing the 2B4 coinhibitory receptor in septic animals compared with sham controls. We sought to interrogate the role of 2B4 in modulating the gHV-specific CD8+ T cell response during sepsis. Results indicated that in the absence of 2B4, gHV-specific CD8+ T cell populations were maintained during sepsis, and gHV viral load was unchanged in 2B4-/- septic animals relative to 2B4-/- sham controls. WT CD8+ T cells upregulated PD-1 during sepsis, whereas 2B4-/- CD8+ T cells did not. Finally, adoptive transfer studies revealed a T cell-intrinsic effect of 2B4 coinhibition on virus-specific CD8+ T cells and gHV viral load during sepsis. These data demonstrate that sepsis-induced immune dysregulation erodes antigen-specific CD8+ responses against a latent viral infection and suggest that blockade of 2B4 may better maintain protective immunity against EBV in the context of sepsis.
Asunto(s)
Linfocitos T CD8-positivos/inmunología , Inmunidad , Memoria Inmunológica , Sepsis/inmunología , Familia de Moléculas Señalizadoras de la Activación Linfocitaria/metabolismo , Animales , Antígenos/metabolismo , Herpesvirus Humano 4 , Interferón gamma/metabolismo , Activación de Linfocitos/inmunología , Recuento de Linfocitos , Ratones Endogámicos C57BL , Receptor de Muerte Celular Programada 1/metabolismo , Transducción de Señal , Familia de Moléculas Señalizadoras de la Activación Linfocitaria/deficiencia , Regulación hacia Arriba , Carga ViralRESUMEN
Invariant NKT (iNKT) cells are innate lymphocytes that respond to glycolipids presented by the MHC class Ib molecule CD1d and are rapidly activated to produce large quantities of cytokines and chemokines. iNKT cell development uniquely depends on interactions between double-positive thymocytes that provide key homotypic interactions between signaling lymphocyte activation molecule (SLAM) family members. However, the role of SLAM receptors in the differentiation of iNKT cell effector subsets and activation has not been explored. In this article, we show that C57BL/6 mice containing the New Zealand Black Slam locus have profound alterations in Ly108, CD150, and Ly9 expression that is associated with iNKT cell hyporesponsiveness. This loss of function was only apparent when dendritic cells and iNKT cells had a loss of SLAM receptor expression. Using small interfering RNA knockdowns and peptide-blocking strategies, we demonstrated that trans-Ly108 interactions between dendritic cells and iNKT cells are critical for robust activation. LY108 costimulation similarly increased human iNKT cell activation. Thus, in addition to its established role in iNKT cell ontogeny, Ly108 regulates iNKT cell function in mice and humans.
Asunto(s)
Antígenos Ly/metabolismo , Células Dendríticas/metabolismo , Activación de Linfocitos , Células T Asesinas Naturales/inmunología , Miembro 1 de la Familia de Moléculas Señalizadoras de la Activación Linfocitaria/metabolismo , Familia de Moléculas Señalizadoras de la Activación Linfocitaria/metabolismo , Animales , Antígenos CD1d/inmunología , Antígenos Ly/genética , Antígenos Ly/inmunología , Diferenciación Celular , Citocinas/biosíntesis , Citocinas/inmunología , Células Dendríticas/inmunología , Regulación de la Expresión Génica , Humanos , Ratones , Ratones Endogámicos C57BL , Células T Asesinas Naturales/metabolismo , ARN Interferente Pequeño , Familia de Moléculas Señalizadoras de la Activación Linfocitaria/deficiencia , Familia de Moléculas Señalizadoras de la Activación Linfocitaria/genética , Familia de Moléculas Señalizadoras de la Activación Linfocitaria/inmunología , Miembro 1 de la Familia de Moléculas Señalizadoras de la Activación Linfocitaria/genética , Miembro 1 de la Familia de Moléculas Señalizadoras de la Activación Linfocitaria/inmunologíaRESUMEN
Cancer cells elude anti-tumour immunity through multiple mechanisms, including upregulated expression of ligands for inhibitory immune checkpoint receptors. Phagocytosis by macrophages plays a critical role in cancer control. Therapeutic blockade of signal regulatory protein (SIRP)-α, an inhibitory receptor on macrophages, or of its ligand CD47 expressed on tumour cells, improves tumour cell elimination in vitro and in vivo, suggesting that blockade of the SIRPα-CD47 checkpoint could be useful in treating human cancer. However, the pro-phagocytic receptor(s) responsible for tumour cell phagocytosis is(are) largely unknown. Here we find that macrophages are much more efficient at phagocytosis of haematopoietic tumour cells, compared with non-haematopoietic tumour cells, in response to SIRPα-CD47 blockade. Using a mouse lacking the signalling lymphocytic activation molecule (SLAM) family of homotypic haematopoietic cell-specific receptors, we determined that phagocytosis of haematopoietic tumour cells during SIRPα-CD47 blockade was strictly dependent on SLAM family receptors in vitro and in vivo. In both mouse and human cells, this function required a single SLAM family member, SLAMF7 (also known as CRACC, CS1, CD319), expressed on macrophages and tumour cell targets. In contrast to most SLAM receptor functions, SLAMF7-mediated phagocytosis was independent of signalling lymphocyte activation molecule-associated protein (SAP) adaptors. Instead, it depended on the ability of SLAMF7 to interact with integrin Mac-1 (refs 18, 19, 20) and utilize signals involving immunoreceptor tyrosine-based activation motifs. These findings elucidate the mechanism by which macrophages engulf and destroy haematopoietic tumour cells. They also reveal a novel SAP adaptor-independent function for a SLAM receptor. Lastly, they suggest that patients with tumours expressing SLAMF7 are more likely to respond to SIRPα-CD47 blockade therapy.