Biomedical subjects

Lewis L Lanier

Publications and source records attributed to Lewis L Lanier.

At least 55 records · Page 3Linked to original sources

PubMed2005

Role of ITAM-containing adapter proteins and their receptors in the immune system and bone.

The immunoreceptor tyrosine-based activation motif (ITAM) is a highly conserved region in the cytoplasmic domain of signaling chains and receptors and is a critical mediator of intracellular signals. ITAM-mediated signals depend on the Syk or zeta-associated protein of 70 kDa tyrosine kinases, and ITAM signaling is required for the differentiation and function of B and T cells in adaptive immunity. ITAM-dependent receptors also regulate the function of innate immune cells, including natural killer cells, and myeloid-derived cells such as macrophages, neutrophils, dendritic cells, and mast cells. Myeloid lineage cells also include osteoclasts (OCLs), the cells required for bone resorption, and recent studies show a critical role for the ITAM-containing adapter proteins DAP12 and the FcRgamma chain (Fcepsilon receptor I gamma chain) in OCL differentiation. Mice deficient in both the DAP12 and FcRgamma ITAM-bearing adapters are significantly osteopetrotic with a severe defect in OCL differentiation, demonstrating the requirement for ITAM signals in bone and further implicating this pathway in the development of highly specialized cell functions in hematopoietic cells. Regulation of osteoclastogenesis by ITAM-dependent receptors suggests that OCLs, similar to related myeloid cells, are tightly controlled by arrays of receptors that allow them to sense and respond to their local microenvironment like other innate immune cells.

Adaptor Proteins, Signal Transducing↗

PubMed2005

NK cell recognition.

The integrated processing of signals transduced by activating and inhibitory cell surface receptors regulates NK cell effector functions. Here, I review the structure, function, and ligand specificity of the receptors responsible for NK cell recognition.

Animals↗

PubMed2004

The role of innate immunity in autoimmunity.

During the 2004 International Congress of Immunology in Montreal, a panel of experts gathered for an "Ideashop" discussion on the potential role of innate immunity in autoimmunity and the ways in which this might be targeted in future therapies.

Animals↗

PubMed2004

The cytomegalovirus m155 gene product subverts natural killer cell antiviral protection by disruption of H60-NKG2D interactions.

Natural killer (NK) cells are an important early mediator of host immunity to murine cytomegalovirus (MCMV) infection. However, MCMV has evolved mechanisms to elude recognition and clearance by NK cells. We have identified an MCMV immune evasion protein that impairs NKG2D-mediated NK cell antiviral activity. Infection of BALB/c 3T3 cells with the Smith strain of MCMV resulted in strong down-regulation of H60, a high affinity ligand for NKG2D, from the surface of virus-infected cells. The MCMV m155 protein specifically down-regulated H60 without affecting expression of the other known NKG2D ligands, RAE-1 and MULT-1. Treatment with the proteasome inhibitors lactacystin or epoxomicin reversed m155 down-regulation of H60. An MCMV mutant virus lacking m155 was severely attenuated in BALB/c mice; however, treatment with neutralizing anti-NKG2D monoclonal antibody or with NK-depleting anti-asialo GM1 antisera restored virulence of the mutant virus. Thus, down-regulation of H60 by m155 is a powerful mechanism of inhibiting NKG2D-mediated antiviral function.

Animals↗

PubMed2004

CD200 receptor family members represent novel DAP12-associated activating receptors on basophils and mast cells.

Modulation by balancing activating and inhibitory receptors constitutes an important mechanism for regulating lymphocyte and myeloid cell effector responses. Using a microarray screen during parasitic helminth infection, we identified CD200 receptor-like 3 as a transcript highly expressed in basophils. Novel splice variants were present that generated proteins that differed in surface expression. The second immunoglobulin-like domain, encoded by exon 4, was required for cell surface expression and recruitment of DAP12 to the cell surface. Splice variants also generated unique cytoplasmic domains, which contributed to efficient pairing with DAP12. Despite expression on basophils and mast cells, which are integral components of allergic immunity, the absence of DAP12 did not alter effector cell recruitment or the host response elicited by helminth infection with Nippostrongylus brasiliensis.

Adaptor Proteins, Signal Transducing↗

PubMed2004

Cross-talk between activated human NK cells and CD4+ T cells via OX40-OX40 ligand interactions.

It is important to understand which molecules are relevant for linking innate and adaptive immune cells. In this study, we show that OX40 ligand is selectively induced on IL-2, IL-12, or IL-15-activated human NK cells following stimulation through NKG2D, the low affinity receptor for IgG (CD16) or killer cell Ig-like receptor 2DS2. CD16-activated NK cells costimulate TCR-induced proliferation, and IFN-gamma produced by autologous CD4+ T cells and this process is dependent upon expression of OX40 ligand and B7 by the activated NK cells. These findings suggest a novel and unexpected link between the natural and specific immune responses, providing direct evidence for cross-talk between human CD4+ T cells and NK receptor-activated NK cells.

Antigens, CD↗

PubMed2004

A Structural basis for the association of DAP12 with mouse, but not human, NKG2D.

Prior studies have revealed that alternative mRNA splicing of the mouse NKG2D gene generates receptors that associate with either the DAP10 or DAP12 transmembrane adapter signaling proteins. We report that NKG2D function is normal in human patients lacking functional DAP12, indicating that DAP10 is sufficient for human NKG2D signal transduction. Further, we show that human NKG2D is incapable of associating with DAP12 and provide evidence that structural differences in the transmembrane of mouse and human NKG2D account for the species-specific difference for this immune receptor.

Adaptor Proteins, Signal Transducing↗

PubMed2004

The immunomodulatory adapter proteins DAP12 and Fc receptor gamma-chain (FcRgamma) regulate development of functional osteoclasts through the Syk tyrosine kinase.

Osteoclasts, the only bone-resorbing cells, are central to the pathogenesis of osteoporosis, yet their development and regulation are incompletely understood. Multiple receptors of the immune system use a common signaling paradigm whereby phosphorylated immunoreceptor tyrosine-based activation motifs (ITAMs) within receptor-associated adapter proteins recruit the Syk tyrosine kinase. Here we demonstrate that a similar mechanism is required for development of functional osteoclasts. Mice lacking two ITAM-bearing adapters, DAP12 and the Fc receptor gamma-chain (FcRgamma), are severely osteopetrotic. DAP12(-/-)FcRgamma(-/-) bone marrow cells fail to differentiate into multinucleated osteoclasts or resorb bone in vitro and show impaired phosphorylation of the Syk tyrosine kinase. syk(-/-) progenitors are similarly defective in osteoclast development and bone resorption. Intact SH2-domains of Syk, introduced by retroviral transduction, are required for functional reconstitution of syk(-/-) osteoclasts, whereas intact ITAM-domains on DAP12 are required for reconstitution of DAP12(-/-) FcRgamma(-/-) cells. These data indicate that recruitment of Syk to phosphorylated ITAMs is critical for osteoclastogenesis. Although DAP12 appears to be primarily responsible for osteoclast differentiation in cultures directly stimulated with macrophage-colony stimulating factor and receptor activator of NF-kappaB ligand cytokines, DAP12 and FcRgamma have overlapping roles in supporting osteoclast development in osteoblast-osteoclast cocultures, which mirrors their overlapping functions in vivo. These results provide new insight into the biology of osteoclasts and suggest novel therapeutic targets in diseases of bony remodeling.

Adaptor Proteins, Signal Transducing↗

PubMed2004

Activation of natural killer cells and dendritic cells upon recognition of a novel CD99-like ligand by paired immunoglobulin-like type 2 receptor.

Paired receptors that consist of highly related activating and inhibitory receptors are widely involved in the regulation of the immune system. Here, we report a mouse orthologue of the human activating paired immunoglobulin-like type 2 receptor (PILR) beta, which was cloned from a cDNA library of natural killer (NK) cells based on its ability to associate with the DAP12 signaling adaptor protein. The activating PILRbeta was expressed not only on NK cells but also on dendritic cells and macrophages. Furthermore, we have identified a novel CD99-like molecule as a ligand for the activating PILRbeta and inhibitory PILRalpha receptors. Transcripts of PILR ligand are present in many tissues, including some T cell lines. Cells expressing the PILR ligand specifically activated NK cells and dendritic cells that express the activating PILRbeta. Our findings reveal a new regulatory mechanism of innate immunity by PILR and its CD99-like ligand.

12E7 Antigen↗

PubMed2004

Cutting edge: Toll-like receptor signaling in macrophages induces ligands for the NKG2D receptor.

Macrophages recognize the presence of infection by using the Toll-like receptor (TLR) family of proteins that detect ligands on bacterial, viral, and fungal pathogens. We show that murine macrophages stimulated with pathogen products known to signal through TLRs express ligands for the NKG2D receptor, found on NK cells, activated CD8(+) T cells and activated macrophages. TLR signaling, through the MyD88 adaptor, up-regulates transcription of the retinoic acid early inducible-1 (RAE-1) family of NKG2D ligands, but not H-60 or murine UL16-binding protein-like transcript-1. RAE-1 proteins are found on the surface of activated, but not resting, macrophages and can be detected by NKG2D on NK cells resulting in down-regulation of this receptor both in vitro and in vivo. RAE-1-NKG2D interactions provide a mechanism by which NK cells and infected macrophages communicate directly during an innate immune response to infection.

Adaptor Proteins, Signal Transducing↗

PubMed2004

NKG2D blockade prevents autoimmune diabetes in NOD mice.

NKG2D is an activating receptor on CD8(+) T cells and NK cells that has been implicated in immunity against tumors and microbial pathogens. Here we show that RAE-1 is present in prediabetic pancreas islets of NOD mice and that autoreactive CD8(+) T cells infiltrating the pancreas express NKG2D. Treatment with a nondepleting anti-NKG2D monoclonal antibody (mAb) during the prediabetic stage completely prevented disease by impairing the expansion and function of autoreactive CD8(+) T cells. These findings demonstrate that NKG2D is essential for disease progression and suggest a new therapeutic target for autoimmune type I diabetes.

Adoptive Transfer↗

PubMed2004

Coordinated induction by IL15 of a TCR-independent NKG2D signaling pathway converts CTL into lymphokine-activated killer cells in celiac disease.

A major function of NKG2D linking innate and adaptive immunity is to upregulate antigen-specific CTL-mediated cytotoxicity in tissues expressing stress-induced NKG2D ligands, such as MIC, by coactivating TCR signaling. Here, we show that, under conditions of dysregulated IL15 expression in vivo in patients with celiac disease and in vitro in healthy individuals, multiple steps of the NKG2D/DAP10 signaling pathway leading to ERK and JNK activation are coordinately primed to activate direct cytolytic function independent of TCR specificity in effector CD8 T cells. These findings may not only explain previous reports of transformation of CTL into NK-like "lymphokine-activated killers" (LAK cells) under high doses of IL2 (a substitute for IL15) but may also have significant implications for understanding and treating immunopathological diseases.

Adolescent↗

PubMed2004

Functional characterization of DNAM-1 (CD226) interaction with its ligands PVR (CD155) and nectin-2 (PRR-2/CD112).

CD226 (DNAM-1) is an adhesion molecule involved in NK and T cell-mediated cytotoxicity against certain tumors. Here, we have identified the human poliovirus receptor-related (PRR) family members CD155 [poliovirus receptor (PVR)] and CD112 (nectin-2/PRR-2) as the ligands for human CD226. Ectopic expression of human CD155 and/or CD112 rendered mouse BW5147 T cells more susceptible to IL-2-activated T and NK cell-mediated cytotoxicity, and killing was specifically inhibited by anti-CD226 mAb, demonstrating functional interactions of CD226 with CD155 and CD112. Although the binding affinities between soluble CD226 and CD155 or CD112 were comparable, the homophilic interaction of cell-surface CD112 may adversely affect CD226 binding to CD112. We also demonstrate that ligation of CD226 and LFA-1 with their respective ligands cooperates in triggering cytotoxicity and cytokine secretion by T and NK cells.

Animals↗

PubMed2003

The signaling adapter protein DAP12 regulates multinucleation during osteoclast development.

UNLABELLED: Deficiency of the signaling adapter protein DAP12 is associated with bony abnormalities in both mice and humans. We identify specific DAP12-associated receptors expressed by osteoclasts and examine function of DAP12 in murine osteoclasts in vivo and in vitro. These data show a new role for DAP12 signaling in regulating formation of multinucleated osteoclasts. INTRODUCTION: Osteoclasts are bone-resorbing cells derived from hematopoietic precursors in the myeloid lineage. In other myeloid cell types, the signaling adapter protein DAP12 transmits activating signals on ligation of a DAP12-associated receptor (DAR). The aim of this study was to clarify the role of DAP12 signaling during osteoclast development. MATERIALS AND METHODS: Osteoclasts from DAP12 -/- or control mice were analyzed in vitro for morphology, function, and for osteoclast markers. DARs were identified in osteoclast cultures through reverse transcriptase-polymerase chain reaction (RT-PCR). Bone density of DAP12 -/- and control mice were analyzed by microcomputed tomography. DAP12 -/- osteoclasts were retrovirally reconstituted with DAP12. RAW264.7 cells were transfected with FLAG-tagged DAP12 or TREM2 and stimulated by anti-FLAG antibody during in vitro osteoclastogenesis. RESULTS: C57BL/6 DAP12-deficient mice have higher bone mass than C57BL/6 wildtype controls. We verified the presence of DAP12 in pre-osteoclasts and osteoclasts derived from C57BL/6 or the pre-osteoclast line RAW 264.7 and identified the DARs expressed. DAP12 -/- osteoclasts developed in vitro with macrophage colony-stimulating factor (M-CSF) and RANKL formed only intensely TRACP+ mononuclear cells and failed to generate multinuclear osteoclasts. These mononuclear cells are functional osteoclast-like cells because, by RT-PCR, they express other osteoclast markers and generate resorption pits on dentine slices, although quantitative assessment of bone resorption shows decreased resorption by DAP12 -/- osteoclasts compared with C57BL/6 osteoclasts. Restoration of DAP12 expression by retroviral transduction of DAP12 -/- osteoclast precursors rescued in vitro osteoclast multinucleation. Direct stimulation of DAP12 expressed in RAW264.7 during in vitro osteoclastogenesis led to a marked increase in the number of TRACP+ multinucleated osteoclast-like cells formed. CONCLUSION: Our studies indicate that stimulation of the DAP12 adapter protein plays a significant role in formation of multinuclear osteoclasts and that DAP12 and DARs likely participate in the regulation of bony remodeling.

Adaptor Proteins, Signal Transducing↗

PubMed2003

The lectin-like receptor KLRE1 inhibits natural killer cell cytotoxicity.

We report the cloning and functional characterization in the mouse and the rat of a novel natural killer (NK) cell receptor termed KLRE1. The receptor is a type II transmembrane protein with a COOH-terminal lectin-like domain, and constitutes a novel KLR family. Rat Klre1 was mapped to the NK gene complex. By Northern blot and flow cytometry using newly generated monoclonal antibodies, KLRE1 was shown to be expressed by NK cells and a subpopulation of CD3+ cells, with pronounced interstrain variation. Western blot analysis indicated that KLRE1 can be expressed on the NK cell surface as a disulphide-linked dimer. The predicted proteins do not contain immunoreceptor tyrosine-based inhibitory motifs (ITIMs) or a positively charged amino acid in the transmembrane domain. However, in a redirected lysis assay, the presence of whole IgG, but not of F(ab')2 fragments of a monoclonal anti-KLRE1 antibody inhibited lysis of Fc-receptor bearing tumor target cells. Moreover, the tyrosine phosphatase SHP-1 was coimmunoprecipitated with KLRE1 from pervanadate-treated interleukin 2-activated NK cells. Together, our results indicate that KLRE1 may form a functional heterodimer with an as yet unidentified ITIM-bearing partner that recruits SHP-1 to generate an inhibitory receptor complex.

Amino Acid Sequence↗

PubMed2003

NKG2D-mediated natural killer cell protection against cytomegalovirus is impaired by viral gp40 modulation of retinoic acid early inducible 1 gene molecules.

Natural killer (NK) cells play a critical role in the innate immune response against cytomegalovirus (CMV) infections. Although CMV encodes several gene products committed to evasion of adaptive immunity, viral modulation of NK cell activity is only beginning to be appreciated. A previous study demonstrated that the mouse CMV m152-encoded gp40 glycoprotein diminished expression of ligands for the activating NK cell receptor NKG2D on the surface of virus-infected cells. Here we have defined the precise ligands that are affected and have directly implicated NKG2D in immune responses to CMV infection in vitro and in vivo. Murine CMV (MCMV) infection potently induced transcription of all five known retinoic acid early inducible 1 (RAE-1) genes (RAE-1alpha, RAE-1beta, RAE-1delta, RAE-1 epsilon, and RAE-1gamma), but not H-60. gp40 specifically down-regulated the cell surface expression of all RAE-1 proteins, but not H-60, and diminished NK cell interferon gamma production against CMV-infected cells. Consistent with previous findings, a m152 deletion mutant virus (Deltam152) was less virulent in vivo than the wild-type Smith strain of MCMV. Treatment of BALB/c mice with a neutralizing anti-NKG2D antibody before infection increased titers of Deltam152 virus in the spleen and liver to levels seen with wild-type virus. These experiments demonstrate that gp40 impairs NK cell recognition of virus-infected cells through disrupting the RAE-1-NKG2D interaction.

3T3 Cells↗

PubMed2003

NKG2D triggers cytotoxicity in mouse NK cells lacking DAP12 or Syk family kinases.

In activated mouse natural killer (NK) cells, the NKG2D receptor associates with two intracellular adaptors, DAP10 and DAP12, which trigger phosphatidyl inositol 3 kinase (PI3K) and Syk family protein tyrosine kinases, respectively. Here we show that cytotoxicity, but not cytokine production, is triggered by NKG2D in activated NK cells lacking either DAP12 or the Syk family members Syk and ZAP70. Inhibition of PI3K blocks this cytotoxicity, suggesting that the DAP10-PI3K pathway is sufficient to initiate NKG2D-mediated killing of target cells. Our results highlight signaling divergence in the effector functions of NKG2D and indicate that alternative associations between a receptor and its adaptors may provide a single receptor with a dual 'on-switch', giving mouse NK cells more choices through which to trigger cytotoxicity.

Animals↗

PubMed2003

Natural killer cells and cancer.

Natural killer (NK) cells are lymphocytes that were first identified for their ability to kill tumor cells without deliberate immunization or activation. Subsequently, they were also found to be able to kill cells that are infected with certain viruses and to attack preferentially cells that lack expression of major histocompatibility complex (MHC) class I antigens. The recent discovery of novel NK receptors and their ligands has uncovered the molecular mechanisms that regulate NK activation and function. Several activating NK cell receptors and costimulatory molecules have been identified that permit these cells to recognize tumors and virus-infected cells. These are modulated by inhibitory receptors that sense the levels of MHC class I on prospective target cells to prevent unwanted destruction of healthy tissues. In vitro and in vivo, their cytotoxic ability can be enhanced by cytokines, such as interleukin (IL)-2, IL-12, IL-15 and interferon alpha/beta (IFN-alpha/beta). In animal studies, they have been shown to play a critical role in the control of tumor growth and metastasis and to provide innate immunity against infection with certain viruses. Following activation, NK cells release cytokines and chemokines that induce inflammatory responses; modulate monocyte, dendritic cells, and granulocyte growth and differentiation; and influence subsequent adaptive immune responses. The underlining mechanism of discriminating tumor cells and normal cells by NK cells has provided new insights into tumor immunosurveillance and has suggested new strategies for the treatment of human cancer.

Animals↗