Abstract
γδ T cells play a pivotal role in protection against various types of infections and tumours, from early childhood on and throughout life. They consist of several subsets characterised by ...adaptive and innate-like functions, with Vγ9Vδ2 being the largest subset in human peripheral blood. Although these cells show signs of cytotoxicity, their
modus operandi
remains poorly understood. Here we explore, using live single-cell imaging, the cytotoxic functions of γδ T cells upon interactions with tumour target cells with high temporal and spatial resolution. While γδ T cell killing is dominated by degranulation, the availability of lytic molecules appears tightly regulated in time and space. In particular, the limited co-occurrence of granzyme B and perforin restrains serial killing of tumour cells by γδ T cells. Thus, our data provide new insights into the cytotoxic arsenal and functions of γδ T cells, which may guide the development of more efficient γδ T cell based adoptive immunotherapies.
DNAX accessory molecule-1 (DNAM-1, also known as CD226) is an activating receptor expressed on subsets of natural killer (NK) and T cells, interacts with its ligands CD155 or CD112, and has co-varied ...expression with inhibitory receptors. Since inhibitory receptors control NK-cell activation and are necessary for MHC-I-dependent education, we investigated whether DNAM-1 expression is also involved in NK-cell education. Here we show an MHC-I-dependent correlation between DNAM-1 expression and NK-cell education, and an association between DNAM-1 and NKG2A that occurs even in MHC class I deficient mice. DNAM-1 is expressed early during NK-cell development, precedes the expression of MHC-I-specific inhibitory receptors, and is modulated in an education-dependent fashion. Cd226
mice have missing self-responses and NK cells with a normal receptor repertoire. We propose a model in which NK-cell education prevents or delays downregulation of DNAM-1. This molecule endows educated NK cells with enhanced effector functions but is dispensable for education.
Peptide-loaded exosomes are promising cancer treatment vehicles; however, moderate T cell responses in human clinical trials indicate a need to further understand exosome-induced immunity. We ...previously demonstrated that antigen-loaded exosomes carry whole protein antigens and require B cells for inducing antigen-specific T cells. Therefore, we investigated the relative importance of exosomal major histocompatibility complex (MHC) class I for the induction of antigen-specific T cell responses and tumour protection. We show that ovalbumin-loaded dendritic cell-derived exosomes from MHCI-/- mice induce antigen-specific T cells at the same magnitude as wild type exosomes. Furthermore, exosomes lacking MHC class I, as well as exosomes with both MHC class I and II mismatch, induced tumour infiltrating T cells and increased overall survival to the same extent as syngeneic exosomes in B16 melanoma. In conclusion, T cell responses are independent of exosomal MHC/peptide complexes if whole antigen is present. This establishes the prospective of using impersonalised exosomes, and will greatly increase the feasibility of designing exosome-based vaccines or therapeutic approaches in humans.
Inflammation in the eye is often associated with aggravated ocular diseases such as uveal melanoma (UM). Poor prognosis of UM is generally associated with high potential of metastatic liver ...dissemination. A strong driver of metastatic dissemination is the activation of the epithelial-mesenchymal transition (EMT) regulating transcription factor ZEB1, and high expression of ZEB1 is associated with aggressiveness of UM. While ZEB1 expression can be also associated with immune tolerance, the underlying drivers of ZEB1 activation remain unclear.
Transcriptomic, in vitro, ex vivo, and in vivo analyses were used to investigate the impact on clinical prognosis of immune infiltration in the ocular tumor microenvironment. A metastatic liver dissemination model of was developed to address the role of natural killer (NK) cells in driving the migration of UM.
In a pan-cancer TCGA analysis, natural killer (NK) cells were associated with worse overall survival in uveal melanoma and more abundant in high-risk monosomy 3 tumors. Furthermore, uveal melanoma expressed high levels of the tumor necrosis factor superfamily member 4-1BB ligand, particularly in tumors with monosomy 3 and BAP1 mutations. Tumors expressing 4-1BB ligand induced CD73 expression on NK cells accompanied with the ability to promote tumor dissemination. Through ligation of 4-1BB, NK cells induced the expression of the ZEB1 transcription factor, leading to the formation of liver metastasis of uveal melanoma.
Taken together, the present study demonstrates a role of NK cells in the aggravation of uveal melanoma towards metastatic disease.
Abstract
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.
Protective cytotoxic and proinflammatory cytokine responses by NK cells impact the outcome of infections by Toxoplasma gondii, a common parasite in humans and other vertebrates. However, T. gondii ...can also sequester within NK cells and downmodulate their effector functions. Recently, the implication of GABA signaling in infection and inflammation‐related responses of mononuclear phagocytes and T cells has become evident. Yet, the role of GABAergic signaling in NK cells has remained unknown. Here, we report that human and murine NK cells synthesize and secrete GABA in response to infection challenge. Parasitized NK cells secreted GABA, whereas activation stimuli, such as IL‐12/IL‐18 or parasite lysates, failed to induce GABA secretion. GABA secretion by NK cells was associated to a transcriptional up‐regulation of GABA synthesis enzymes (glutamate decarboxylases GAD65/67) and was abrogated by GAD inhibition. Further, NK cells expressed GABA‐A receptor subunits and GABA signaling regulators, with transcriptional modulations taking place upon challenge with T. gondii. Exogenous GABA and GABA‐containing supernatants from parasitized dendritic cells (DCs) impacted NK cell function by reducing the degranulation and cytotoxicity of NK cells. Conversely, GABA‐containing supernatants from NK cells enhanced the migratory responses of parasitized DCs. This enhanced DC migration was abolished by GABA‐A receptor antagonism or GAD inhibition and was reconstituted by exogenous GABA. Jointly, the data show that NK cells are GABAergic cells and that GABA hampers NK cell cytotoxicity in vitro. We hypothesize that GABA secreted by parasitized immune cells modulates the immune responses to T. gondii infection.
Graphical
In response to infection challenge, NK cells synthesize and secrete gamma‐aminobutyric acid (GABA), which impacts NK cell and dendritic cell functions via GABA‐A receptors.
Among the polypeptides that comprise the T cell receptor (TCR), only CD3ζ is found in Natural Killer (NK) cells, where it transmits signals from activating receptors such as CD16 and NKp46. NK cells ...are potent immune cells that recognize target cells through germline-encoded activating and inhibitory receptors. Genetic engineering of NK cells enables tumor-specific antigen recognition and, thus, has a significant promise in adoptive cell therapy. Ectopic expression of engineered TCR components in T cells leads to mispairing with the endogenous components, making a knockout of the endogenous TCR necessary. To circumvent the mispairing of TCRs or the need for knockout technologies, TCR complex expression has been studied in NK cells. In the current study, we explored the cellular processing of the TCR complex in NK cells. We observed that in the absence of CD3 subunits, the TCR was not expressed on the surface of NK cells and vice versa. Moreover, a progressive increase in surface expression of TCR between day three and day seven was observed after transduction. Interestingly, the TCR complex expression in NK92 cells was enhanced with a proteasome inhibitor (bortezomib) but not a lysosomal inhibitor (chloroquine). Additionally, we observed that the TCR complex was functional in NK92 cells as measured by estimating CD107a as a degranulation marker, IFNγ cytokine production, and killing assays. NK92 cells strongly degranulated when CD3ε was engaged in the presence of TCR, but not when only CD3 was overexpressed. Therefore, our findings encourage further investigation to unravel the mechanisms that prevent the surface expression of the TCR complex.
The growth and recurrence of a number of cancers is driven by a scarce population of cancer stem cells (CSCs), which are resistant to most current therapies. It has been shown previously that natural ...killer (NK) cells recognize human glioma, melanoma, colon and prostate CSCs
. We herein show that human and mouse breast CSCs are also susceptible to NK cytotoxic activity
. Moreover, CSC induced autologous NK cell activation and expansion
, which correlate with the inhibition of CSC metastatic spread. These data suggest that NK cells control CSC metastatic spread
and that their use in breast cancer therapy may well be fruitful.
We present a three-stage analysis of genome-wide SNP data in 1,222 German individuals with myocardial infarction and 1,298 controls, in silico replication in three additional genome-wide datasets of ...coronary artery disease (CAD) and subsequent replication in ∼25,000 subjects. We identified one new CAD risk locus on 3q22.3 in MRAS (P = 7.44 × 10−13; OR = 1.15, 95% CI = 1.11-1.19), and suggestive association with a locus on 12q24.31 near HNF1A-C12orf43 (P = 4.81 × 10−7; OR = 1.08, 95% CI = 1.05-1.11).
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Multiple myeloma (MM) is an incurable hematological cancer, in which immune checkpoint inhibition (ICI) with monoclonal antibodies (mAbs) has failed due to uncontrollable immune responses in ...combination therapies and lack of efficacy in monotherapies. Although NK cell-specific checkpoint targets such as NKG2A and KIRs are currently being evaluated in clinical trials, the clinical impact of NK cells on the PD1 cascade is less well understood compared to T cells. Furthermore, while NK cells have effector activity within the TME, under continuous ligand exposure, NK cell dysfunctionality may occur due to interaction of PD1 and its ligand PD-L1. Due to above-mentioned factors, we designed novel NK cell specific PD1-based chimeric switch receptors (PD1-CSR) by employing signaling domains of DAP10, DAP12 and CD3ζ to revert NK cell inhibition and retarget ICI. PD1-CSR modified NK cells showed increased degranulation, cytokine secretion and cytotoxicity upon recognition of PD-L1
+
target cells. Additionally, PD1-CSR
+
NK cells infiltrated and killed tumor spheroids. While primary NK cells (pNK), expressing native PD1, showed decreased degranulation and cytokine production against PD-L1
+
target cells by twofold, PD1-CSR
+
pNK cells demonstrated increased activity upon PD-L1
+
target cell recognition and enhanced antibody-dependent cellular cytotoxicity. PD1-CSR
+
pNK cells from patients with MM increased degranulation and cytokine expression against autologous CD138
+
PD-L1
+
malignant plasma cells. Taken together, the present results demonstrate that PD1-CSR
+
NK cells enhance and sustain potent anti-tumor activity in a PD-L1
+
microenvironment and thus represent a promising strategy to advance adoptive NK cell-based immunotherapies toward PD-L1
+
cancers.
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