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Miletić A, Krmpotić A, Jonjić S. The evolutionary arms race between NK cells and viruses: who gets the short end of the stick? Eur J Immunol 2013; 43:867-77. [PMID: 23440773 DOI: 10.1002/eji.201243101] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2012] [Revised: 02/11/2013] [Accepted: 02/21/2013] [Indexed: 01/17/2023]
Abstract
NK cells are innate lymphocytes that play a key role in the control of various viral infections. Recent studies indicate that NK cells may acquire some features of adaptive immune cells, including the formation of long-lived memory cells. A large and growing body of data indicates that NK cells regulate the adaptive immune response as well. The function and the activation status of NK cells are tightly regulated by signals induced by a broad range of inhibitory and activating cell surface receptors and cytokines released by other immune cells. Here, we review the function of mouse NK-cell receptors involved in virus control and in the regulation of the adaptive immune response. In addition, we discuss viral strategies used to evade NK-cell-mediated control during infection. Finally, the role of several activating Ly49 receptors specific for mouse cytomegalovirus (MCMV), as well as some controversial issues in the field, will be discussed.
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Affiliation(s)
- Antonija Miletić
- Department of Histology and Embryology, Faculty of Medicine, Rijeka, Croatia
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52
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Welsh RM, Waggoner SN. NK cells controlling virus-specific T cells: Rheostats for acute vs. persistent infections. Virology 2013; 435:37-45. [PMID: 23217614 DOI: 10.1016/j.virol.2012.10.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Accepted: 10/01/2012] [Indexed: 12/13/2022]
Abstract
Viral infections characteristically induce a cytokine-driven activated natural killer (NK) cell response that precedes an antigen-driven T cell response. These NK cells can restrain some but not all viral infections by attacking virus-infected cells and can thereby provide time for an effective T cell response to mobilize. Recent studies have revealed an additional immunoregulatory role for the NK cells, where they inhibit the size and functionality of the T cell response, regardless of whether the viruses are themselves sensitive to NK cells. This subsequent change in T cell dynamics can alter patterns of immunopathology and persistence and implicates NK cells as rheostat-like regulators of persistent infections.
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Affiliation(s)
- Raymond M Welsh
- Department of Pathology and Program for Immunology and Virology, University of Massachusetts Medical School, Worcester, MA 01655, USA.
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53
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van Helden MJG, Zaiss DMW, Sijts AJAM. CCR2 defines a distinct population of NK cells and mediates their migration during influenza virus infection in mice. PLoS One 2012; 7:e52027. [PMID: 23272202 PMCID: PMC3521727 DOI: 10.1371/journal.pone.0052027] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Accepted: 11/13/2012] [Indexed: 12/13/2022] Open
Abstract
Natural killer (NK) cells are innate lymphocytes that play an important role in control of viral infections. We recently showed that intranasal infection of mice with influenza virus induced the accumulation of NK cells in the airways. NK cells however did not proliferate in the airways or in the draining lymph node, but in the bone marrow mainly. As also monocyte-precursors undergo vigorous proliferation in the bone marrow (BM) during infections and then egress CCR2-dependently, we decided to determine the role of CCR2 in NK cell migration during intranasal influenza virus infection. We show that a unique population of NK cells in the BM expressed CCR2 and that monocyte chemotactic protein-1 (MCP-1), one of the CCR2 ligands, was produced in the airways of influenza virus infected mice. Analysis of BM chimeric mice reconstituted with a mix of wild-type (wt) and CCR2-deficient BM cells showed that upon influenza virus infection, a significantly lower proportion of CCR2-deficient than wt NK cells was recovered from the bronchoalveolar lavage (BAL). Taken together, our data demonstrate that during influenza virus infection a proportion of NK cells migrate in a CCR2-dependent fashion.
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Affiliation(s)
- Mary J. G. van Helden
- Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, University of Utrecht, Utrecht, The Netherlands
| | - Dietmar M. W. Zaiss
- Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, University of Utrecht, Utrecht, The Netherlands
- * E-mail: (DMWZ); (AJAMS)
| | - Alice J. A. M. Sijts
- Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, University of Utrecht, Utrecht, The Netherlands
- * E-mail: (DMWZ); (AJAMS)
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54
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Seidel E, Glasner A, Mandelboim O. Virus-mediated inhibition of natural cytotoxicity receptor recognition. Cell Mol Life Sci 2012; 69:3911-20. [PMID: 22547090 PMCID: PMC11115132 DOI: 10.1007/s00018-012-1001-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2012] [Revised: 04/16/2012] [Accepted: 04/17/2012] [Indexed: 12/29/2022]
Abstract
Natural killer (NK) cells are a part of the innate immune system that functions mainly to kill transformed and infected cells. Their activity is controlled by signals derived from a panel of activating and inhibitory receptors. The natural cytotoxicity receptors (NCRs): NKp30, NKp44, and NKp46 (NCR1 in mice) are prominent among the activating NK cell receptors and they are, notably, the only NK-activating receptors that are able to recognize pathogen-derived ligands. In addition, the NCRs also recognize cellular ligands, the identity of which remains largely unknown. In this review, we summarize the current knowledge regarding viruses that are recognized by the NCRs, focusing on the diverse immune-evasion mechanisms employed by viruses to escape this detection. We also discuss the unique role the NCRs have in regulating NK cell activity with particular emphasis on the in vivo function of NKp46/NCR1.
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Affiliation(s)
- Einat Seidel
- The Department of Immunology and Cancer Research, The Lautenberg Center for General and Tumor Immunology, IMRIC, Hadassah Medical School, The Hebrew University, 91120 Jerusalem, Israel
| | - Ariella Glasner
- The Department of Immunology and Cancer Research, The Lautenberg Center for General and Tumor Immunology, IMRIC, Hadassah Medical School, The Hebrew University, 91120 Jerusalem, Israel
| | - Ofer Mandelboim
- The Department of Immunology and Cancer Research, The Lautenberg Center for General and Tumor Immunology, IMRIC, Hadassah Medical School, The Hebrew University, 91120 Jerusalem, Israel
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55
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Vidal SM, Khakoo SI, Biron CA. Natural killer cell responses during viral infections: flexibility and conditioning of innate immunity by experience. Curr Opin Virol 2012; 1:497-512. [PMID: 22180766 DOI: 10.1016/j.coviro.2011.10.017] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Natural killer (NK) cells mediate innate defense against viral infections, but the mechanisms in place to access their functions as needed during diverse challenges while limiting collateral damage are poorly understood. Recent molecular characterization of effects mediated through infection-induced inhibitory/activating NK receptor-ligand pairs and cytokines are providing new insights into pathways regulating their responses and revealing unexpected consequences for NK cell subset effects, maintenance, proliferation and function through times overlapping with adaptive and long-lived immunity. The observations define flexible pathways for experience-induced 'conditioning' and challenge narrowly defined roles for NK cells and innate immunity as first responders with prescribed functions. They suggest that individual experiences as well as genes influence the innate immune resources available to fight off an infection.
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Affiliation(s)
- Silvia M Vidal
- Department of Human Genetics, McGill University, Montreal, Quebec, Canada.
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56
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Mitrović M, Arapović J, Traven L, Krmpotić A, Jonjić S. Innate immunity regulates adaptive immune response: lessons learned from studying the interplay between NK and CD8+ T cells during MCMV infection. Med Microbiol Immunol 2012; 201:487-95. [PMID: 22965169 DOI: 10.1007/s00430-012-0263-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 08/24/2012] [Indexed: 01/04/2023]
Abstract
Natural killer (NK) cells play a crucial role in early immune response against cytomegalovirus infection. A large and mounting body of data indicate that these cells are involved in the regulation of the adaptive immune response as well. By using mouse cytomegalovirus (MCMV) as a model, several groups provided novel insights into the role of NK cells in the development and kinetics of antiviral CD8(+) T cell response. Depending on infection conditions, virus strain and the genetic background of mice used, NK cells are either positive or negative regulators of the CD8(+) T cell response. At present, there is no unique explanation for the observed differences between various experimental systems used. In this review we discuss the mechanisms involved in the interplay between NK and CD8(+) T cells in the early control of MCMV infection.
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Affiliation(s)
- Maja Mitrović
- Department of Histology and Embryology, University of Rijeka, B. Branchetta 20, 51 000 Rijeka, Croatia
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57
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Mahmood S, Kanwar N, Tran J, Zhang ML, Kung SKP. SHP-1 phosphatase is a critical regulator in preventing natural killer cell self-killing. PLoS One 2012; 7:e44244. [PMID: 22952938 PMCID: PMC3432062 DOI: 10.1371/journal.pone.0044244] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Accepted: 07/31/2012] [Indexed: 12/31/2022] Open
Abstract
Balance of signals generated from the engaged activating and inhibitory surface receptors regulates mature NK cell activities. The inhibitory receptors signal through immunoreceptor tyrosine based inhibitory motifs (ITIM), and recruit phosphatases such as SHP-1 to inhibit NK cell activation. To directly examine the importance of SHP-1 in regulating activities and cell fate of mature NK cells, we used our established lentiviral-based engineering protocol to knock down the SHP-1 protein expression in primary C57BL/6NCrl cells. Gene silencing of the SHP-1 in primary NK cells abrogated the ability of ITIM-containing NK inhibitory receptors to suppress the activation signals induced by NK1.1 activating receptors. We followed the fates of stably transduced SHP-1 silenced primary NK cells over a longer period of time in IL-2 containing cultures. We observed an impaired IL-2 induced proliferation in the SHP-1 knockdown NK cells. More interestingly, these "de-regulated" SHP-1 knockdown NK cells mediated specific self-killing in a real-time live cell microscopic imaging system we developed to study NK cell cytotoxicity in vitro. Selective target recognition of the SHP-1 knockdown NK cells revealed also possible involvement of the SHP-1 phosphatase in regulating other NK functions in mature NK cells.
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MESH Headings
- Animals
- Cell Degranulation/drug effects
- Cell Proliferation/drug effects
- Cell Survival/drug effects
- Cells, Cultured
- Computer Systems
- Cytotoxicity, Immunologic/drug effects
- Cytotoxicity, Immunologic/immunology
- Gene Knockdown Techniques
- Gene Silencing/drug effects
- Imaging, Three-Dimensional
- Immunoassay
- Interleukin-2/pharmacology
- Killer Cells, Natural/cytology
- Killer Cells, Natural/drug effects
- Killer Cells, Natural/enzymology
- Killer Cells, Natural/physiology
- Lymphocyte Activation/drug effects
- Mice
- Mice, Inbred C57BL
- Protein Tyrosine Phosphatase, Non-Receptor Type 6/metabolism
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Affiliation(s)
- Sajid Mahmood
- Department of Immunology, University of Manitoba, Winnipeg, Manitoba, Canada
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58
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Absence of cross-presenting cells in the salivary gland and viral immune evasion confine cytomegalovirus immune control to effector CD4 T cells. PLoS Pathog 2011; 7:e1002214. [PMID: 21901102 PMCID: PMC3161985 DOI: 10.1371/journal.ppat.1002214] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Accepted: 06/27/2011] [Indexed: 12/24/2022] Open
Abstract
Horizontal transmission of cytomegaloviruses (CMV) occurs via prolonged excretion from mucosal surfaces. We used murine CMV (MCMV) infection to investigate the mechanisms of immune control in secretory organs. CD4 T cells were crucial to cease MCMV replication in the salivary gland (SG) via direct secretion of IFNγ that initiated antiviral signaling on non-hematopoietic cells. In contrast, CD4 T cell helper functions for CD8 T cells or B cells were dispensable. Despite SG-resident MCMV-specific CD8 T cells being able to produce IFNγ, the absence of MHC class I molecules on infected acinar glandular epithelial cells due to viral immune evasion, and the paucity of cross-presenting antigen presenting cells (APCs) prevented their local activation. Thus, local activation of MCMV-specific T cells is confined to the CD4 subset due to exclusive presentation of MCMV-derived antigens by MHC class II molecules on bystander APCs, resulting in IFNγ secretion interfering with viral replication in cells of non-hematopoietic origin. Cytomegaloviruses (CMVs) infect 50 to 90 % of the world's population and cause severe clinical complication in immunosuppressed individuals. An important tissue for horizontal transmission is the salivary gland (SG). CD4 T cells are crucial for viral control in this organ. However, how CD4 T cells control MCMV and why CD8 T cells, important effector cells in other organs, are inefficient in the SG, remains unclear. Here we show that CD4 T cells exert direct antiviral effector rather than helper functions by secretion of IFNγ acting on non-hematopoietic cells. Although SG-resident CD8 T cells were able to produce IFNγ and outnumbered CD4 T cells, absence of MHC class I expression on infected cells due to CMV-encoded immune evasion genes and concomitant absence of cross-presenting antigen presenting cells prohibited antigen recognition by CD8 T cells. Deletion of CMV-encoded immune evasion genes enabled CD8 T cells to control MCMV replication in the SG in absence of CD4 T cells. Hence, CMV control depends on direct antiviral functions of CD4 T cells because of exclusive MHC class II-restricted CMV antigen presentation by bystander APCs in the SG, exemplifying a strategy of effective immune evasion by which CMVs to promote their own transmission.
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59
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All is fair in virus-host interactions: NK cells and cytomegalovirus. Trends Mol Med 2011; 17:677-85. [PMID: 21852192 DOI: 10.1016/j.molmed.2011.07.003] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Revised: 07/11/2011] [Accepted: 07/12/2011] [Indexed: 12/12/2022]
Abstract
The infection of mice with mouse cytomegalovirus (MCMV) as a model of human cytomegalovirus (HCMV) infection has been particularly informative in elucidating the role of innate and adaptive immune response mechanisms during infection. Millions of years of co-evolution between cytomegaloviruses (CMV) and their hosts has resulted in numerous attempts to overwhelm each other. CMVs devote many genes to modulating the host natural killer (NK) cell response and NK cells employ many strategies to cope with CMV infection. While focusing on these attack-counterattack measures, this review will discuss several novel mechanisms of immune evasion by MCMV, the role of Ly49 receptors in mediating resistance to MCMV, and the impact of the initial NK cell response on the shaping of adaptive immunity.
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60
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Cook CH, Trgovcich J. Cytomegalovirus reactivation in critically ill immunocompetent hosts: a decade of progress and remaining challenges. Antiviral Res 2011; 90:151-9. [PMID: 21439328 PMCID: PMC3129598 DOI: 10.1016/j.antiviral.2011.03.179] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2011] [Revised: 03/14/2011] [Accepted: 03/15/2011] [Indexed: 01/05/2023]
Abstract
Human cytomegalovirus (HCMV) is an undisputed pathogen in humans with severe immune compromise, which has historically been thought to carry little consequence in immunocompetent hosts. During the past decade, however, accumulating data suggest that significant numbers of immunocompetent humans reactivate HCMV during critical illness, and that these reactivation episodes are associated with worsened outcomes. Because most people are infected with this ubiquitous virus by adulthood, confirming pathogenicity has now become a clinical priority. In this article, we will review the incidence and implications of reactivation, the relevant immune responses and reactivation triggers relevant to the immunocompetent host. We will summarize the progress made during the past ten years, outline the work ongoing in this field, and identify the major gaps remaining in our emerging understanding of this phenomenon.
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Affiliation(s)
- Charles H Cook
- Department of Surgery, The Ohio State University, Columbus, OH 43210, USA.
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61
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The impact of Ly49-NK cell-dependent recognition of MCMV infection on innate and adaptive immune responses. J Biomed Biotechnol 2011; 2011:641702. [PMID: 21660138 PMCID: PMC3110313 DOI: 10.1155/2011/641702] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2011] [Accepted: 03/15/2011] [Indexed: 12/19/2022] Open
Abstract
Clinical and experimental data indicate that a subset of innate lymphocytes, natural killer (NK) cells, plays a crucial role in the response against herpesviruses, especially cytomegaloviruses (CMV). Indeed, in mice, NK cells, due to the expression of germline encoded Ly49 receptors, possess multiple mechanisms to recognize CMV infection. Classically, this results in NK cell activation and the destruction of the infected cells. More recently, however, this unique host-pathogen interaction has permitted the discovery of novel aspects of NK cell biology, implicating them in the regulation of adaptive immune responses as well as in the development of immunological memory. Here, we will concisely review the newly acquired evidence pertaining to NK cell Ly49-dependent recognition of MCMV-infected cell and the ensuing NK cell regulatory responses.
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62
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Pyzik M, Charbonneau B, Gendron-Pontbriand EM, Babić M, Krmpotić A, Jonjić S, Vidal SM. Distinct MHC class I-dependent NK cell-activating receptors control cytomegalovirus infection in different mouse strains. ACTA ACUST UNITED AC 2011; 208:1105-17. [PMID: 21518798 PMCID: PMC3092355 DOI: 10.1084/jem.20101831] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
MCMV-infected cells are recognized by multiple MHC class I–restricted Ly49-activating receptors in genetically distinct mouse strains. Recognition of mouse cytomegalovirus (MCMV)–infected cells by activating NK cell receptors was first described in the context of Ly49H, which confers resistance to C57BL/6 mice. We investigated the ability of other activating Ly49 receptors to recognize MCMV-infected cells in mice from various H-2 backgrounds. We observed that Ly49P1 from NOD/Ltj mice, Ly49L from BALB mice, and Ly49D2 from PWK/Pas mice respond to MCMV-infected cells in the context of H-2Dk and the viral protein m04/gp34. Recognition was also seen in the H-2d and/or H-2f contexts, depending on the Ly49 receptor examined, but never in H-2b. Furthermore, BALB.K (H-2k) mice showed reduced viral loads compared with their H-2d or H-2b congenic partners, a reduction which was dependent on interferon γ secretion by Ly49L+ NK cells early after infection. Adoptive transfer of Ly49L+, but not Ly49L−, NK cells significantly increased resistance against MCMV infection in neonate BALB.K mice. These results suggest that multiple activating Ly49 receptors participate in H-2–dependent recognition of MCMV infection, providing a common mechanism of NK cell–mediated resistance against viral infection.
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Affiliation(s)
- Michał Pyzik
- Department of Human Genetics, McGill University, Montreal, Quebec H3A 2T5, Canada
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63
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Leishmania-infected macrophages are targets of NK cell-derived cytokines but not of NK cell cytotoxicity. Infect Immun 2011; 79:2699-708. [PMID: 21518784 DOI: 10.1128/iai.00079-11] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Natural killer (NK) cells are important components of a protective immune response against intracellular pathogens such as Leishmania parasites, which reside within myeloid cells. Previous in vivo studies in murine cutaneous or visceral leishmaniasis showed that NK cells are activated by conventional dendritic cells in a Toll-like receptor 9-, interleukin-12 (IL-12)-, and IL-18-dependent manner during the early phase of infection and help to restrict the tissue parasite burden by unknown mechanisms. Here, we tested whether NK cells contribute to the control of Leishmania infections by lysing or by activating infected host cells. Coculture experiments revealed that activated NK cells from poly(I:C)-treated mice readily killed tumor target cells, whereas Leishmania infantum- or L. major-infected macrophages or dendritic cells remained viable. Infection with Leishmania did not significantly alter the expression of NK cell-activating molecules (retinoic acid early transcript alpha [Rae-1α], mouse UL16-binding protein-like transcript 1 [MULT-1], CD48) or inhibitory molecules (major histocompatibility complex [MHC] class I, nonclassical MHC class 1b molecule Qa-1) on the surface of myeloid cells, which offers an explanation for their protection from NK cell cytotoxicity. Consistent with these in vitro data, in vivo cytotoxicity assays revealed poor cytolytic activity of NK cells against adoptively transferred infected wild-type macrophages, whereas MHC class I-deficient macrophages were efficiently eliminated. NK cells activated by IL-12 and IL-18 stimulated macrophages to kill intracellular Leishmania in a cell contact-independent but gamma interferon-, tumor necrosis factor-, and inducible nitric oxide synthase-dependent manner. We conclude that Leishmania parasites, unlike viruses, do not render infected myeloid cells susceptible to the cytotoxicity of NK cells. Instead, soluble products of NK cells trigger the leishmanicidal activity of macrophages.
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64
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Fodil-Cornu N, Loredo-Osti JC, Vidal SM. NK cell receptor/H2-Dk-dependent host resistance to viral infection is quantitatively modulated by H2q inhibitory signals. PLoS Genet 2011; 7:e1001368. [PMID: 21533075 PMCID: PMC3080855 DOI: 10.1371/journal.pgen.1001368] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Accepted: 03/08/2011] [Indexed: 02/06/2023] Open
Abstract
The cytomegalovirus resistance locus Cmv3 has been linked to an
epistatic interaction between two loci: a Natural Killer (NK) cell receptor gene
and the major histocompatibility complex class I (MHC-I) locus. To demonstrate
the interaction between Cmv3 and
H2k, we generated double congenic mice between
MA/My and BALB.K mice and an F2 cross between FVB/N
(H-2q) and BALB.K
(H2k) mice, two strains susceptible to mouse
cytomegalovirus (MCMV). Only mice expressing H2k in
conjunction with Cmv3MA/My or
Cmv3FVB were resistant to MCMV infection.
Subsequently, an F3 cross was carried out between transgenic
FVB/H2-Dk and MHC-I deficient mice in which
only the progeny expressing Cmv3FVB and a single
H2-Dk class-I molecule completely controlled
MCMV viral loads. This phenotype was shown to be NK cell–dependent and
associated with subsequent NK cell proliferation. Finally, we demonstrated that
a number of H2q alleles influence the expression
level of H2q molecules, but not intrinsic functional
properties of NK cells; viral loads, however, were quantitatively proportional
to the number of H2q alleles. Our results support a
model in which H-2q molecules convey Ly49-dependent
inhibitory signals that interfere with the action of
H2-Dk on NK cell activation against MCMV
infection. Thus, the integration of activating and inhibitory signals emanating
from various MHC-I/NK cell receptor interactions regulates NK
cell–mediated control of viral load. Effective natural killer (NK) cell responses against virally infected cells are
regulated by NK cell receptors that specifically recognize target cells. In the
current study, we validated the specific interaction taking place between NK
cell receptors and MHC class I molecules on the surface of infected cells,
resulting in resistance to cytomegalovirus. Genetic dissection of this mechanism
of interaction revealed that the NK cell response occurs exclusively through the
triggering of the activating Ly49P receptor by the MHC class I
H2-Dk molecule. We observed, in this context,
that NK cells were incapable of clearing the virus when target cells also
expressed MHC class I H2q molecules, which strongly
and quantitatively inhibit NK cells. Our findings reveal that the interplay
between inhibitory and activating NK cell receptors and their MHC class I
ligands generate signals that shape the outcome of infection.
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Affiliation(s)
- Nassima Fodil-Cornu
- Department of Human Genetics and Department of
Microbiology and Immunology, McGill University, Life Sciences Complex, Montreal,
Canada
- McGill Centre for the Study of Host
Resistance, McGill University, Montreal, Canada
| | | | - Silvia M. Vidal
- Department of Human Genetics and Department of
Microbiology and Immunology, McGill University, Life Sciences Complex, Montreal,
Canada
- McGill Centre for the Study of Host
Resistance, McGill University, Montreal, Canada
- * E-mail:
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65
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Abstract
MHC class I (MHC I) is essential to NK- and T-cell effector and surveillance functions. However, it is unknown whether MHC I polymorphism influences adaptive immunity through NK cells. Previously, we found that MHC I D(k), a cognate ligand for the Ly49G2 inhibitory receptor, was essential to NK control of murine (M)CMV infection. Here we assessed the significance of NK inhibitory receptor recognition of MCMV on CD8 T cells in genetically defined MHC I D(k) disparate mice. We observed that D(k)-licensed Ly49G2⁺ NK cells stabilized and then enhanced conventional dendritic cells (cDCs) recovery after infection. Furthermore, licensed NK support of cDC recovery was essential to enhance the tempo, magnitude, and effector activity of virus-specific CD8 T cells. Minimal cDC and CD8 T-cell number differences after low-dose MCMV in D(k) disparate animals further implied that licensed NK recognition of MCMV imparted qualitative cDC changes to enhance CD8 T-cell priming.
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66
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Corbett AJ, Coudert JD, Forbes CA, Scalzo AA. Functional consequences of natural sequence variation of murine cytomegalovirus m157 for Ly49 receptor specificity and NK cell activation. THE JOURNAL OF IMMUNOLOGY 2010; 186:1713-22. [PMID: 21187440 DOI: 10.4049/jimmunol.1003308] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The Ly49H activating receptor on C57BL/6 (B6) NK cells plays a key role in early resistance to murine cytomegalovirus (MCMV) infection through specific recognition of the MCMV-encoded MHC class I-like molecule m157 expressed on infected cells. The m157 molecule is also recognized by the Ly49I inhibitory receptor from the 129/J mouse strain. The m157 gene is highly sequence variable among MCMV isolates, with many m157 variants unable to bind Ly49H(B6). In this study, we have sought to define if m157 variability leads to a wider spectrum of interactions with other Ly49 molecules and if this modifies host susceptibility to MCMV. We have identified novel m157-Ly49 receptor interactions, involving Ly49C inhibitory receptors from B6, BALB/c, and NZB mice, as well as the Ly49H(NZB) activation receptor. Using an MCMV recombinant virus in which m157(K181) was replaced with m157(G1F), which interacts with both Ly49H(B6) and Ly49C(B6), we show that the m157(G1F)-Ly49C interactions cause no apparent attenuating effect on viral clearance in B6 mice. Hence, when m157 can bind both inhibitory and activation NK cell receptors, the outcome is still activation. Thus, these data indicate that whereas m157 variants predominately interact with inhibitory Ly49 receptors, these interactions do not profoundly interfere with early NK cell responses.
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Affiliation(s)
- Alexandra J Corbett
- Centre for Ophthalmology and Vision Science, University of Western Australia, Crawley, Western Australia 6009, Australia
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