RESUMEN
Comparative genomics has revealed the rapid expansion of multiple gene families involved in immunity. Members within each gene family often evolved distinct roles in immunity. However, less is known about the evolution of their epigenome and cis-regulation. Here we systematically profile the epigenome of the recently expanded murine Ly49 gene family that mainly encode either inhibitory or activating surface receptors on natural killer cells. We identify a set of cis-regulatory elements (CREs) for activating Ly49 genes. In addition, we show that in mice, inhibitory and activating Ly49 genes are regulated by two separate sets of proximal CREs, likely resulting from lineage-specific losses of CRE activity. Furthermore, we find that some Ly49 genes are cross-regulated by the CREs of other Ly49 genes, suggesting that the Ly49 family has begun to evolve a concerted cis-regulatory mechanism. Collectively, we demonstrate the different modes of cis-regulatory evolution for a rapidly expanding gene family.
Asunto(s)
Evolución Molecular , Familia de Multigenes , Subfamilia A de Receptores Similares a Lectina de Células NK , Animales , Ratones , Subfamilia A de Receptores Similares a Lectina de Células NK/genética , Subfamilia A de Receptores Similares a Lectina de Células NK/metabolismo , Secuencias Reguladoras de Ácidos Nucleicos/genética , Regulación de la Expresión Génica , Células Asesinas Naturales/inmunología , Ratones Endogámicos C57BLRESUMEN
Inhibitory natural killer (NK) cell receptors recognize MHC class I (MHC-I) in trans on target cells and suppress cytotoxicity. Some NK cell receptors recognize MHC-I in cis, but the role of this interaction is uncertain. Ly49Q, an atypical Ly49 receptor expressed in non-NK cells, binds MHC-I in cis and mediates chemotaxis of neutrophils and type I interferon production by plasmacytoid dendritic cells. We identified a lipid-binding motif in the juxtamembrane region of Ly49Q and found that Ly49Q organized functional membrane domains comprising sphingolipids via sulfatide binding. Ly49Q recruited actin-remodeling molecules to an immunoreceptor tyrosine-based inhibitory motif, which enabled the sphingolipid-enriched membrane domain to mediate complicated actin remodeling at the lamellipodia and phagosome membranes during phagocytosis. Thus, Ly49Q facilitates integrative regulation of proteins and lipid species to construct a cell type-specific membrane platform. Other Ly49 members possess lipid binding motifs; therefore, membrane platform organization may be a primary role of some NK cell receptors.
Asunto(s)
Esfingolípidos , Animales , Humanos , Esfingolípidos/metabolismo , Células Asesinas Naturales/inmunología , Células Asesinas Naturales/metabolismo , Fagocitosis , Fagocitos/inmunología , Fagocitos/metabolismo , Subfamilia A de Receptores Similares a Lectina de Células NK/metabolismo , Membrana Celular/metabolismo , Unión ProteicaRESUMEN
NK cells are a key focus in immuno-oncology, based on their ability to eliminate malignant cells without prior sensitization. Dogs are valuable models for translational immunotherapy studies, especially for NK cells, where critical species differences exist between mice and humans. Given that the mechanism for recognition of "self" by canine NK cells is currently unknown, we sought to evaluate expression of Ly49 in canine NK cells using in silico and high-throughput techniques. We interrogated the identified polymorphism/mutation in canine Ly49 and assessed the potential impact on structure using computational modeling of three-dimensional protein structure and protein-protein docking of canine Ly49 with MHC class I (MHC-I). Bulk and single-cell RNA-sequencing analysis was performed to detect gene expression of Ly49/KLRA1 in resting and activated NK cells. Tertiary protein structure demonstrated significant structural similarity to the known murine system. Molecular docking of canine Ly49 with MHC-I was favorable, converging at a single low-energy conformation. RNA sequencing revealed expression of Ly49/KLRA1 in both resting and activated NK cells and demonstrated almost exclusive expression of the gene in the NK cluster at the single-cell level. Despite prior reports of a mutated, nonfunctional canine Ly49, our data support that the protein product is predicted to bind to MHC-I in a comparable conformation to the murine system and is expressed in canine NK cells with upregulation following activation. Taken together, these data suggest that Ly49 is capable of recognizing MHC-I and therefore regulating NK cell function in dogs.
Asunto(s)
Antígenos de Histocompatibilidad Clase I , Neoplasias , Animales , Ratones , Perros , Humanos , Antígenos de Histocompatibilidad Clase I/genética , Antígenos de Histocompatibilidad Clase I/metabolismo , Subfamilia A de Receptores Similares a Lectina de Células NK/genética , Subfamilia A de Receptores Similares a Lectina de Células NK/metabolismo , Simulación del Acoplamiento Molecular , Células Asesinas Naturales , Neoplasias/genéticaRESUMEN
The murine CMV (MCMV) immunoevasin m04/gp34 escorts MHC class I (MHC I) molecules to the surface of infected cells where these complexes bind Ly49 inhibitory receptors (IRs) and prevent NK cell attack. Nonetheless, certain self-MHC I-binding Ly49 activating and inhibitory receptors are able to promote robust NK cell expansion and antiviral immunity during MCMV infection. A basis for MHC I-dependent NK cell sensing of MCMV-infected targets and control of MCMV infection however remains unclear. In this study, we discovered that the Ly49R activation receptor is selectively triggered during MCMV infection on antiviral NK cells licensed by the Ly49G2 IR. Ly49R activating receptor recognition of MCMV-infected targets is dependent on MHC I Dk and MCMV gp34 expression. Remarkably, although Ly49R is critical for Ly49G2-dependent antiviral immunity, blockade of the activation receptor in Ly49G2-deficient mice has no impact on virus control, suggesting that paired Ly49G2 MCMV sensing might enable Ly49R+ NK cells to better engage viral targets. Indeed, MCMV gp34 facilitates Ly49G2 binding to infected cells, and the IR is required to counter gp34-mediated immune evasion. A specific requirement for Ly49G2 in antiviral immunity is further explained by its capacity to license cytokine receptor signaling pathways and enhance Ly49R+ NK cell proliferation during infection. These findings advance our understanding of the molecular basis for functionally disparate self-receptor enhancement of antiviral NK cell immunity.
Asunto(s)
Muromegalovirus , Animales , Antivirales/metabolismo , Proteínas Portadoras/metabolismo , Antígenos de Histocompatibilidad Clase I , Evasión Inmune , Ratones , Ratones Endogámicos C57BL , Subfamilia A de Receptores Similares a Lectina de Células NK/metabolismo , Receptores de Citocinas/metabolismo , Receptores de Células Asesinas Naturales/metabolismoRESUMEN
Natural killer (NK) cells are important effectors of the innate immune system and participate in the first line of defense against infections and tumors. Prior to being functional, these lymphocytes must be educated or licensed through interactions of their major histocompatibility complex class I molecules with self-specific inhibitory receptors that recognize them. In the absence of such contacts, caused by either the lack of expression of the inhibitory receptors or a very low level of major histocompatibility complex class I (MHC class I) proteins, NK cells are hypo-reactive at baseline (ex vivo). After stimulation (assessed through plate-bound antibodies against activating receptors or culture in the presence of cytokines such as interleukin (IL)-2 or IL-15) however, they can become cytotoxic and produce cytokines. This is particularly the case in transporter associated with antigen processing (TAP)-deficient mice, which we investigated in the present study. Transporter associated with antigen processing transports endogenous peptides from the cytosol to the endoplasmic reticulum, where they are loaded on nascent MHC class I molecules, which then become stable and expressed at the cell surface. Consequently, TAP-KO mice have very low levels of MHC class I expression. We present a study about phenotypic and functional aspects of NK cells in two mouse strains, C57BL/6 wildtype and TAP1-KO in spleen and lung. We observed that in both types of mice, on the same genetic background, the initial pattern of education, conferred to the cells via the inhibitory receptors Ly49C/I and NKG2A, was maintained even after a strong stimulation by the cytokines interleukin-2, interleukin-12, interleukin-15 and interleukin-18. Furthermore, the percentages of activated NK cells expressing Ly49C/I and Ly49I were strongly down-modulated under these conditions. We completed our investigations with phenotypic studies of NK cells from these mice.
Asunto(s)
Presentación de Antígeno , Antígenos de Histocompatibilidad Clase I , Células Asesinas Naturales , Transportador de Casetes de Unión a ATP, Subfamilia B, Miembro 2/genética , Animales , Proteínas de Transporte de Membrana/metabolismo , Ratones , Ratones Endogámicos C57BL , Subfamilia A de Receptores Similares a Lectina de Células NK/inmunología , Subfamilia A de Receptores Similares a Lectina de Células NK/metabolismoRESUMEN
MHC class I (MHC I) expression in the host influences NK cells in a process termed education. The result of this education is reflected in the responsiveness of NK cells at the level of individual cells as well as in the repertoire of inhibitory MHC I-specific receptors at the NK cell system level. The presence of MHC I molecules in the host environment gives rise to a skewed receptor repertoire in spleen NK cells where subsets expressing few (one or two) inhibitory receptors are expanded whereas subsets with many (three or more) receptors are contracted. It is not known whether this MHC I-dependent skewing is imposed during development or after maturation of NK cells. In this study, we tested the hypothesis that the NK cell receptor repertoire is shaped already early during NK cell development in the bone marrow. We used mice with a repertoire imposed by a single MHC I allele, as well as a C57BL/6 mutant strain with exaggerated repertoire skewing, to investigate Ly49 receptor repertoires at different stages of NK cell differentiation. Our results show that NK cell inhibitory receptor repertoire skewing can indeed be observed in the bone marrow, even during the earliest developmental steps where Ly49 receptors are expressed. This may partly be accounted for by selective proliferation of certain NK cell subsets, but other mechanisms must also be involved. We propose a model for how repertoire skewing is established during a developmental phase in the bone marrow, based on sequential receptor expression as well as selective proliferation.
Asunto(s)
Médula Ósea , Subfamilia A de Receptores Similares a Lectina de Células NK , Animales , Antígenos Ly/metabolismo , Médula Ósea/metabolismo , Antígenos de Histocompatibilidad Clase I/genética , Antígenos de Histocompatibilidad Clase I/metabolismo , Células Asesinas Naturales , Lectinas Tipo C/metabolismo , Glicoproteínas de Membrana/metabolismo , Ratones , Ratones Endogámicos C57BL , Subfamilia A de Receptores Similares a Lectina de Células NK/genética , Subfamilia A de Receptores Similares a Lectina de Células NK/metabolismo , Receptores Similares a Lectina de Células NK/metabolismo , Receptores de Células Asesinas Naturales/metabolismoRESUMEN
Natural killer (NK) cell responses depend on the balance of signals from inhibitory and activating receptors. However, how the integration of antagonistic signals occurs upon NK cell-target cell interaction is not fully understood. Here we provide evidence that NK cell inhibition via the inhibitory receptor Ly49A is dependent on its relative colocalization at the nanometer scale with the activating receptor NKG2D upon immune synapse (IS) formation. NKG2D and Ly49A signal integration and colocalization were studied using NKG2D-GFP and Ly49A-RFP-expressing primary NK cells, forming ISs with NIH3T3 target cells, with or without the expression of single-chain trimer (SCT) H2-Dd and an extended form of SCT H2-Dd-CD4 MHC-I molecules. Nanoscale colocalization was assessed by Förster resonance energy transfer between NKG2D-GFP and Ly49A-RFP and measured for each synapse. In the presence of their respective cognate ligands, NKG2D and Ly49A colocalize at the nanometer scale, leading to NK cell inhibition. However, increasing the size of the Ly49A ligand reduced the nanoscale colocalization with NKG2D, consequently impairing Ly49A-mediated inhibition. Thus, our data shows that NK cell signal integration is critically dependent on the dimensions of NK cell ligand-receptor pairs by affecting their relative nanometer-scale colocalization at the IS. Our results together suggest that the balance of NK cell signals and NK cell responses is determined by the relative nanoscale colocalization of activating and inhibitory receptors in the immune synapse.
Asunto(s)
Subfamilia A de Receptores Similares a Lectina de Células NK , Subfamilia K de Receptores Similares a Lectina de Células NK , Animales , Proteínas Portadoras/metabolismo , Antígenos H-2 , Antígeno de Histocompatibilidad H-2D/metabolismo , Células Asesinas Naturales , Lectinas Tipo C/metabolismo , Ligandos , Ratones , Células 3T3 NIH , Subfamilia A de Receptores Similares a Lectina de Células NK/metabolismo , Subfamilia K de Receptores Similares a Lectina de Células NK/metabolismo , Receptores Similares a Lectina de Células NK/metabolismo , Receptores de Células Asesinas Naturales/metabolismoRESUMEN
Cytochrome P450 26A1 (CYP26A1) plays a vital role in early pregnancy in mice. Our previous studies have found that CYP26A1 affects embryo implantation by modulating natural killer (NK) cells, and that there is a novel population of CYP26A1+ NK cells in the uteri of pregnant mice. The aim of this study was to investigate the effects of CYP26A1 on the subsets and killing activity of NK cells. Through single-cell RNA sequencing (scRNA-seq), we identified four NK cell subsets in the uterus, namely, conventional NK (cNK), tissue-resident NK (trNK) 1 and 2, and proliferating trNK (trNKp). The two most variable subpopulations after uterine knockdown of CYP26A1 were trNKp and trNK2 cells. CYP26A1 knockdown significantly downregulated the expression of the NK cell function-related genes Cd44, Cd160, Vegfc, and Slamf6 in trNK2 cells, and Klra17 and Ogn in trNKp cells. Both RNA-seq and cytotoxicity assays confirmed that CYP26A1+ NK cells had low cytotoxicity. These results indicate that CYP26A1 may affect the immune microenvironment at the maternal-foetal interface by regulating the activity of NK cells.
Asunto(s)
Implantación del Embrión , Células Asesinas Naturales , Animales , Implantación del Embrión/fisiología , Femenino , Ratones , Subfamilia A de Receptores Similares a Lectina de Células NK/metabolismo , Embarazo , Ácido Retinoico 4-Hidroxilasa/metabolismo , Útero/metabolismoRESUMEN
Although interactions between inhibitory Ly49 receptors and their self-MHC class I ligands in C57BL/6 mice are known to limit NK cell proliferation during mouse CMV (MCMV) infection, we created a 36-marker mass cytometry (CyTOF) panel to investigate how these inhibitory receptors impact the NK cell response to MCMV in other phenotypically measurable ways. More than two thirds of licensed NK cells (i.e., those expressing Ly49C, Ly49I, or both) in uninfected mice had already differentiated into NK cells with phenotypes indicative of Ag encounter (KLRG1+Ly6C-) or memory-like status (KLRG1+Ly6C+). These pre-existing KLRG1+Ly6C+ NK cells resembled known Ag-specific memory NK cell populations in being less responsive to IL-18 and IFN-α stimulation in vitro and by selecting for NK cell clones with elevated expression of a Ly49 receptor. During MCMV infection, the significant differences between licensed and unlicensed (Ly49C-Ly49I-) NK cells disappeared within both CMV-specific (Ly49H+) and nonspecific (Ly49H-) responses. This lack of heterogeneity carried into the memory phase, with only a difference in CD16 expression manifesting between licensed and unlicensed MCMV-specific memory NK cell populations. Our results suggest that restricting proliferation is the predominant effect licensing has on the NK cell population during MCMV infection, but the inhibitory Ly49-MHC interactions that take place ahead of infection contribute to their limited expansion by shrinking the pool of licensed NK cells capable of robustly responding to new challenges.
Asunto(s)
Infecciones por Citomegalovirus , Muromegalovirus , Animales , Células Asesinas Naturales/metabolismo , Ratones , Ratones Endogámicos C57BL , Muromegalovirus/fisiología , Subfamilia A de Receptores Similares a Lectina de Células NK/metabolismoRESUMEN
Regulatory T cells (Treg) are essential to maintain immune homeostasis and prevent autoimmune disorders. While the function and molecular regulation of Foxp3+CD4+ Tregs are well established, much of CD8+ Treg biology remains to be revealed. Here, we will review the heterogenous subsets of CD8+ T cells have been named "CD8+ Treg" and mainly focus on CD122hiLy49+CD8+ Tregs present in naïve mice. CD122hiLy49+CD8+ Tregs, which depends on transcription factor Helios and homeostatic cytokine IL-15, have been established as a non-redundant regulator of germinal center (GC) reaction. Recently, we have demonstrated that TGF-ß (Transforming growth factor-ß) and transcription factor Eomes (Eomesodermin) are essential for the function and homeostasis of CD8+ Tregs. In addition, we will discuss several open questions regarding the differentiation, function and true identity of CD8+ Tregs as well as a brief comparison between two regulatory T cell subsets critical to control GC reaction, namely CD4+ TFR (follicular regulatory T cells) and CD8+ Tregs.
Asunto(s)
Linfocitos T CD8-positivos/inmunología , Linfocitos T Reguladores/inmunología , Animales , Linfocitos T CD8-positivos/clasificación , Centro Germinal/inmunología , Humanos , Subunidad beta del Receptor de Interleucina-2/análisis , Ratones , Subfamilia A de Receptores Similares a Lectina de Células NK/análisis , Linfocitos T Reguladores/clasificación , Factor de Crecimiento Transformador beta/fisiologíaRESUMEN
Ly49Q is an ITIM-bearing MHC class I receptor that is highly expressed in plasmacytoid dendritic cells (pDCs). Ly49Q is required for the TLR9-mediated IFN-I production in pDCs, although the mechanism is not fully understood. We here demonstrate that Ly49Q protects pDCs from pyroptotic cell death induced by CpG oligodeoxynucleotides (CpG). In the Ly49Q-deficient (Klra17-/-) mouse spleen, the number of ssDNA-positive pDCs increased significantly after CpG treatment, strongly suggesting that Klra17-/- pDCs were susceptible to CpG-induced cell death. In Klra17-/- bone-marrow-derived dendritic cells (BMDCs), CpG-induced cell death was accompanied by increased cathepsin B leakage from the vesicular compartments into the cytoplasm. Concurrently, IL-1ß secretion increased in the CpG-treated Klra17-/- BMDCs, strongly suggesting that the CpG-induced cell death in these cells is pyroptotic in nature. Consistent with these observations, inhibiting cathepsin B or caspase 1 in CpG-stimulated Klra17-/- BMDCs reversed the increase in cell death. Pyroptotic cell death and IL-1ß secretion were also observed in BMDCs derived from transgenic mice expressing an ITIM-less Ly49Q (Ly49Q-YF Tg). CpG also increased the IL-1ß production and cell death in B2m-/- BMDCs. These results suggest that Ly49Q and MHC class I play important roles for protecting pyroptosis-like cell death of DCs by influencing lysosome state.
Asunto(s)
Células Dendríticas/inmunología , Lisosomas/metabolismo , Subfamilia A de Receptores Similares a Lectina de Células NK/metabolismo , Oligodesoxirribonucleótidos/farmacología , Piroptosis/inmunología , Animales , Caspasa 1/metabolismo , Catepsina B/metabolismo , Membrana Celular/fisiología , Células Cultivadas , Islas de CpG/genética , Interleucina-1beta/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Subfamilia A de Receptores Similares a Lectina de Células NK/genética , Oligodesoxirribonucleótidos/genéticaRESUMEN
Using a variety of activating and inhibitory receptors, natural killer (NK) cells protect against disease by eliminating cells that have downregulated class I major histocompatibility complex (MHC) proteins, such as in response to cell transformation or viral infection. The inhibitory murine NK receptor Ly49C specifically recognizes the class I MHC protein H-2Kb. Unusual among NK receptors, Ly49C exhibits a peptide-dependent sensitivity to H-2Kb recognition, which has not been explained despite detailed structural studies. To gain further insight into Ly49C peptide sensitivity, we examined Ly49C recognition biochemically and through the lens of dynamic allostery. We found that the peptide sensitivity of Ly49C arises through small differences in H-2Kb-binding affinity. Although molecular dynamics simulations supported a role for peptide-dependent protein dynamics in producing these differences in binding affinity, calorimetric measurements indicated an enthalpically as opposed to entropically driven process. A quantitative linkage analysis showed that this emerges from peptide-dependent dynamic tuning of electrostatic interactions across the Ly49C-H-2Kb interface. We propose a model whereby different peptides alter the flexibility of H-2Kb, which in turn changes the strength of electrostatic interactions across the protein-protein interface. Our results provide a quantitative assessment of how peptides alter Ly49C-binding affinity, suggest the underlying mechanism, and demonstrate peptide-driven allostery at work in class I MHC proteins. Lastly, our model provides a solution for how dynamic allostery could impact binding of some, but not all, class I MHC partners depending on the structural and chemical composition of the interfaces.
Asunto(s)
Células Asesinas Naturales/metabolismo , Subfamilia A de Receptores Similares a Lectina de Células NK/metabolismo , Regulación Alostérica , Animales , Cinética , Ratones , Modelos Moleculares , Simulación de Dinámica Molecular , Subfamilia A de Receptores Similares a Lectina de Células NK/química , Unión Proteica , Dominios Proteicos , Especificidad por SustratoRESUMEN
Previous studies of NK cell inhibitory Ly-49 genes showed their expression is stochastic. However, relatively few studies have examined the mechanisms governing acquisition of inhibitory receptors in conjunction with activating Ly-49 receptors and NK cell development. We hypothesized that the surface expression of activating Ly-49 receptors is nonrandom and is influenced by inhibitory Ly-49 receptors. We analyzed NK cell "clusters" defined by combinatorial expression of activating (Ly-49H and Ly-49D) and inhibitory (Ly-49I and Ly-49G2) receptors in C57BL/6 mice. Using the product rule to evaluate the interdependencies of the Ly-49 receptors, we found evidence for a tightly regulated expression at the immature NK cell stage, with the highest interdependencies between clusters that express at least one activating receptor. Further analysis demonstrated that certain NK clusters predominated at the immature (CD27+CD11b-), transitional (CD27+CD11b+), and mature (CD27-CD11b-) NK cell stages. Using parallel in vitro culture and in vivo transplantation of sorted NK clusters, we discovered nonrandom expression of Ly-49 receptors, suggesting that prescribed pathways of NK cluster differentiation exist. Our data infer that surface expression of Ly-49I is an important step in NK cell maturation. Ki-67 expression and cell counts confirmed that immature NK cells proliferate more than mature NK cells. We found that MHC class I is particularly important for regulation of Ly-49D and Ly-49G2, even though no known MHC class I ligand for these receptors is present in B6 mice. Our data indicate that surface expression of both activating and inhibitory Ly-49 receptors on NK cell clusters occurs in a nonrandom process correlated to their maturation stage.
Asunto(s)
Diferenciación Celular/genética , Células Asesinas Naturales/inmunología , Subfamilia A de Receptores Similares a Lectina de Células NK/genética , Traslado Adoptivo , Animales , Diferenciación Celular/inmunología , Proliferación Celular/genética , Femenino , Regulación de la Expresión Génica/inmunología , Células Asesinas Naturales/metabolismo , Células Asesinas Naturales/trasplante , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Subfamilia A de Receptores Similares a Lectina de Células NK/metabolismoRESUMEN
Domestic animal populations are often characterised by high rates of inbreeding and low effective population sizes due to selective breeding practices. These practices can result in otherwise rare recessive deleterious alleles drifting to high frequencies, resulting in reduced fertility rates. This study aimed to identify potential recessive lethal haplotypes in the Thoroughbred horse breed, a closed population that has been selectively bred for racing performance. In this study, we identified a haplotype in the LY49B gene that shows strong evidence of being homozygous lethal, despite having high frequencies of heterozygotes in Thoroughbreds and other domestic horse breeds. Variant analysis of whole-genome sequence data identified two SNPs in the 3'UTR of the LY49B gene that may result in loss of function. Analysis of transcriptomic data from equine embryonic tissue revealed that LY49B is expressed in the trophoblast during placentation stage of development. These findings suggest that LY49B may have an essential, but as yet unknown function in the implantation stage of equine development. Further investigation of this region may allow for the development of a genetic test to improve fertility rates in horse populations. Identification of other lethal variants could assist in improving natural levels of fertility in horse populations.
Asunto(s)
Regiones no Traducidas 3' , Cruzamiento , Haplotipos , Caballos/genética , Subfamilia A de Receptores Similares a Lectina de Células NK/genética , Polimorfismo de Nucleótido Simple , Animales , Femenino , Fertilidad/genética , Estudio de Asociación del Genoma Completo , MasculinoRESUMEN
Major histocompatibility complex class I (MHC-I)-restricted immune responses are largely attributed to cytotoxic T lymphocytes (CTLs). However, natural killer (NK) cells, as predicted by the missing-self hypothesis, have opposing requirements for MHC-I, suggesting that they may also demonstrate MHC-I-restricted effects. In mice, the Ly49 inhibitory receptors prevent NK cell killing of missing-self targets in effector responses, and they have a proposed second function in licensing or educating NK cells via self-MHC-I in vivo. Here we show MHC-I-restricted control of murine cytomegalovirus (MCMV) infection in vivo that is NK cell dependent. Using mice lacking specific Ly49 receptors, we show that control of MCMV requires inhibitory Ly49 receptors and an inhibitory signaling motif and the capacity for MCMV to downregulate MHC-I. Taken together, these data provide definitive evidence that the inhibitory receptors are required for missing-self rejection and are relevant to MHC-I-restricted NK cell control of a viral infection in vivo.
Asunto(s)
Antígenos de Histocompatibilidad Clase I/metabolismo , Células Asesinas Naturales/metabolismo , Subfamilia A de Receptores Similares a Lectina de Células NK/metabolismo , Animales , Antígenos Ly , Infecciones por Citomegalovirus/inmunología , Antígenos de Histocompatibilidad Clase I/inmunología , Células Asesinas Naturales/inmunología , Ratones , Ratones Endogámicos C57BL , Muromegalovirus/inmunología , Muromegalovirus/patogenicidad , Subfamilia A de Receptores Similares a Lectina de Células NK/inmunología , Receptores de Células Asesinas Naturales , VirosisRESUMEN
In the past decade, the study of NK cells was transformed by the discovery of three ways these "innate" immune cells display adaptive immune behavior, including the ability to form long-lasting, Ag-specific memories of a wide variety of immunogens. In this review, we examine these types of NK cell memory, highlighting their unique features and underlying similarities. We explore those similarities in depth, focusing on the role that Ly49 receptors play in various types of NK cell memory. From this Ly49 dependency, we will build a model by which we understand the three types of NK cell memory as aspects of what is ultimately the same adaptive immune process, rather than separate facets of NK cell biology. We hope that a defined model for NK cell memory will empower collaboration between researchers of these three fields to further our understanding of this surprising and clinically promising immune response.
Asunto(s)
Células Asesinas Naturales/inmunología , Subfamilia A de Receptores Similares a Lectina de Células NK/metabolismo , Animales , Antígenos de Histocompatibilidad Clase I/metabolismo , Humanos , Inmunidad Innata , Memoria InmunológicaRESUMEN
Cattle possess the most diverse repertoire of NK cell receptor genes among all mammals studied to date. Killer cell receptor genes encoded within the NK complex and killer cell Ig-like receptor genes encoded within the leukocyte receptor complex have both been expanded and diversified. Our previous studies identified two divergent and polymorphic KLRA alleles within the NK complex in the Holstein-Friesian breed of dairy cattle. By examining a much larger cohort and other ruminant species, we demonstrate the emergence and fixation of two KLRA allele lineages (KLRA*01 and -*02) at a single locus during ruminant speciation. Subsequent recombination events between these allele lineages have increased the frequency of KLRA*02 extracellular domains. KLRA*01 and KLRA*02 transcription levels contrasted in response to cytokine stimulation, whereas homozygous animals consistently transcribed higher levels of KLRA, regardless of the allele lineage. KLRA*02 mRNA levels were also generally higher than KLRA*01 Collectively, these data point toward alternative functional roles governed by KLRA genotype and allele lineage. On a background of high genetic diversity of NK cell receptor genes, this KLRA allele fixation points to fundamental and potentially differential function roles.
Asunto(s)
Subfamilia A de Receptores Similares a Lectina de Células NK/genética , Rumiantes/genética , Transcripción Genética/genética , Alelos , Animales , Bovinos , Frecuencia de los Genes/genética , Frecuencia de los Genes/inmunología , Genotipo , Células Asesinas Naturales/inmunología , Subfamilia A de Receptores Similares a Lectina de Células NK/inmunología , ARN Mensajero/genética , ARN Mensajero/inmunología , Rumiantes/inmunología , Transcripción Genética/inmunologíaRESUMEN
The role of Ly49+CD8 T-cells in the immune system is not clear. Previously, several papers suggested Ly49+CD8 T-cells as immunosuppressors, while multiple studies also suggested their role as potent participants of the immune response. The mechanism of Ly49 expression on CD8 T-cells is also not clear. We investigated phenotype, functions, and regulation of Ly49 expression on murine CD8 T-cells in both normal state and during LCMV infection. CD8 T-cells express different Ly49 receptors compared with NK-cells. In intact mice, Ly49+CD8 T-cells have a phenotype similar to resting central memory CD8 T-cells and do not show impaired proliferation and cytokine production. Conventional CD8 T-cells upregulate Ly49 receptors during TCR-induced stimulation, and IL-2, as well as IL-15, affect it. At the same time, Ly49+CD8 T-cells change the Ly49 expression profile dramatically upon re-stimulation downregulating inhibitory and upregulating activating Ly49 receptors. We observed the expression of Ly49 receptors on the virus-specific CD8 T-cells during LCMV infection, especially marked in the early stages, and participation of Ly49+CD8 T-cells in the anti-viral response. Thus, CD8 T-cells acquire Ly49 receptors during the T-cell activation and show dynamic regulation of Ly49 receptors during stimulation.
Asunto(s)
Linfocitos T CD8-positivos/virología , Activación de Linfocitos , Coriomeningitis Linfocítica/virología , Virus de la Coriomeningitis Linfocítica/patogenicidad , Subfamilia A de Receptores Similares a Lectina de Células NK/metabolismo , Traslado Adoptivo , Animales , Linfocitos T CD8-positivos/inmunología , Linfocitos T CD8-positivos/metabolismo , Linfocitos T CD8-positivos/trasplante , Proliferación Celular , Chlorocebus aethiops , Citocinas/metabolismo , Modelos Animales de Enfermedad , Interacciones Huésped-Patógeno , Memoria Inmunológica , Coriomeningitis Linfocítica/genética , Coriomeningitis Linfocítica/inmunología , Coriomeningitis Linfocítica/metabolismo , Virus de la Coriomeningitis Linfocítica/inmunología , Ratones Endogámicos C57BL , Ratones Noqueados , Subfamilia A de Receptores Similares a Lectina de Células NK/genética , Fenotipo , Transducción de Señal , Células VeroRESUMEN
Mice lacking MHC class-I (MHC-I) display severe defects in natural killer (NK) cell functional maturation, a process designated as "education". Whether self-MHC-I specific Ly49 family receptors and NKG2A, which are closely linked within the NK gene complex (NKC) locus, are essential for NK cell education is still unclear. Here we show, using CRISPR/Cas9-mediated gene deletion, that mice lacking all members of the Ly49 family exhibit a moderate defect in NK cell activity, while mice lacking only two inhibitory Ly49 members, Ly49C and Ly49I, have comparable phenotypes. Furthermore, the deficiency of NKG2A, which recognizes non-classical MHC-Ib molecules, mildly impairs NK cell function. Notably, the combined deletion of NKG2A and the Ly49 family severely compromises the ability of NK cells to mediate "missing-self" and "induced-self" recognition. Therefore, our data provide genetic evidence supporting that NKG2A and the inhibitory members of Ly49 family receptors synergize to regulate NK cell education.