NK cells use a variety of receptors to detect abnormal cells, including tumors and their metastases. However, in the case of melanoma, it remains to be determined what specific molecular interactions ...are involved and whether NK cells control metastatic progression and/or the route of dissemination. Here we show that human melanoma cell lines derived from LN metastases express ligands for natural cytotoxicity receptors (NCRs) and DNAX accessory molecule-1 (DNAM-1), two emerging NK cell receptors key for cancer cell recognition, but not NK group 2 member D (NKG2D). Compared with cell lines derived from metastases taken from other anatomical sites, LN metastases were more susceptible to NK cell lysis and preferentially targeted by adoptively transferred NK cells in a xenogeneic model of cell therapy. In mice, DNAM-1 and NCR ligands were also found on spontaneous melanomas and melanoma cell lines. Interference with DNAM-1 and NCRs by antibody blockade or genetic disruption reduced killing of melanoma cells. Taken together, these results show that DNAM-1 and NCRs are critical for NK cell-mediated innate immunity to melanoma cells and provide a background to design NK cell-based immunotherapeutic strategies against melanoma and possibly other tumors.
Natural killer cells can discriminate between normal cells and cells that do
not express adequate amounts of major histocompatibility complex (MHC) class I
molecules. The discovery, both in mouse and ...in human, of MHC-specific
inhibitory receptors clarified the molecular basis of this important NK cell
function. However, the triggering receptors responsible for positive NK cell
stimulation remained elusive until recently. Some of these receptors have now
been identified in humans, thus shedding some light on the molecular mechanisms
involved in NK cell activation during the process of natural cytotoxicity.
Three novel, NK-specific, triggering surface molecules (NKp46, NKp30, and
NKp44) have been identified. They represent the first members of a novel
emerging group of receptors collectively termed natural cytotoxicity receptors
(NCR). Monoclonal antibodies (mAbs) to NCR block to differing extents the
NK-mediated lysis of various tumors. Moreover, lysis of certain tumors can be
virtually abrogated by the simultaneous masking of the three NCRs. There is a
coordinated surface expression of the three NCRs, their surface density varying
in different individuals and also in the NK cells isolated from a given
individual. A direct correlation exists between the surface density of NCR and
the ability of NK cells to kill various tumors. NKp46 is the only NCR involved
in human NK-mediated killing of murine target cells. Accordingly, a homologue
of NKp46 has been detected in mouse. Molecular cloning of NCR revealed novel
members of the Ig superfamily displaying a low degree of similarity to each
other and to known human molecules. NCRs are coupled to different signal
transducing adaptor proteins, including CD3ζ, Fc∍RIγ, and
KARAP/DAP12. Another triggering NK receptor is NKG2D. It appears to play either
a complementary or a synergistic role with NCRs. Thus, the triggering of NK
cells in the process of tumor cell lysis may often depend on the concerted
action of NCR and NKG2D. In some instances, however, it may uniquely depend
upon the activity of NCR or NKG2D only. Strict NKG2D-dependency can be
appreciated using clones that, in spite of their NCR
dull
phenotype,
efficiently lyse certain epithelial tumors or leukemic cell lines. Other
triggering surface molecules including 2B4 and the novel NKp80 appear to
function as coreceptors rather than as true receptors. Indeed, they can induce
natural cytotoxicity only when co-engaged with a triggering receptor. While an
altered expression or function of NCR or NKG2D is being explored as a possible
cause of immunological disorders, 2B4 dysfunction has already been associated
with a severe form of immunodeficiency. Indeed, in patients with the X-linked
lymphoproliferative disease, the inability to control Epstein-Barr virus
infections may be consequent to a major dysfunction of 2B4 that exerts
inhibitory instead of activating functions.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Control of HIV replication in elite controller (EC) and long-term nonprogressor (LTNP) patients has been associated with efficient CD8 ⁺cytotoxic T-lymphocyte function. However, innate immunity may ...play a role in HIV control. We studied the expression of natural cytotoxicity receptors (NKp46, NKp30, and NKp44) and their induction over a short time frame (2–4 d) on activation of natural killer (NK) cells in 31 HIV controller patients (15 ECs, 16 LTNPs). In EC/LTNP, induction of NKp46 expression was normal but short (2 d), and NKp30 was induced to lower levels vs. healthy donors. Notably, in antiretroviral-treated aviremic progressor patients (TAPPs), no induction of NKp46 or NKp30 expression occurred. More importantly, EC/LTNP failed to induce expression of NKp44, a receptor efficiently induced in activated NK cells in TAPPs. The specific lack of NKp44 expression resulted in sharply decreased capability of killing target cells by NKp44, whereas TAPPs had conserved NKp44-mediated lysis. Importantly, conserved NK cell responses, accompanied by a selective defect in the NKp44-activating pathway, may result in lack of killing of uninfected CD4 ⁺NKp44Ligand ⁺ cells when induced by HIVgp41 peptide-S3, representing a relevant mechanism of CD4 ⁺ depletion. In addition, peripheral NK cells from EC/LTNP had increased NKG2D expression, significant HLA-DR up-regulation, and a mature (NKG2A−CD57 ⁺killer cell Ig-like receptor ⁺CD85j ⁺) phenotype, with cytolytic function also against immature dendritic cells. Thus, NK cells in EC/LTNP can maintain substantially unchanged functional capabilities, whereas the lack of NKp44 induction may be related to CD4 maintenance, representing a hallmark of these patients.
The surface density of the triggering receptors responsible for the natural killer (NK)-mediated cytotoxicity is crucial for the ability of NK cells to kill susceptible target cells. In this study, ...we show that transforming growth factor β1 (TGFβ1) down-regulates the surface expression of NKp30 and in part of NKG2D but not that of other triggering receptors such as NKp46. The TGFβ1-mediated inhibition of NKp30 surface expression reflects gene regulation at the transcriptional level. NKp30 has been shown to represent the major receptor involved in the NK-mediated killing of dendritic cells. Accordingly, the TGFβ1-dependent down-regulation of NKp30 expression profoundly inhibited the NK-mediated killing of dendritic cells. On the contrary, killing of different NK-susceptible tumor cell lines was variably affected, reflecting the differential usage of NKp30 and/or NKG2D in the lysis of such tumors. Our present data suggest a possible mechanism by which TGFβ1-producing dendritic cells may acquire resistance to the NK-mediated attack.
Little is known about epidemiology of carbapenemase-producing Enterobacteriaceae (CPE) in children. Aim of this study was to describe CPE epidemiology in a tertiary care pediatric hospital in Italy ...that admits patients coming from geographic areas with high diffusion of CPE.
Prospective evaluation of the proportion and rates per 100,000 hospital discharges (D) or hospitalization-days (HD) of invasive infections due to CPE from 2013 to 2017 and of CPE infections and colonizations from 2014 to 2017. Disease-preventing strategies comprised patients’ screening at admission, pre-emptive contact isolation precautions pending cultures results, and bundles for prevention of healthcare associated infections.
From 2013 to 2017 CPE represented 3.5% of all invasive infections due to Enterobacteriaceae, with rates ranging 7.30–14.33 for D and 1.03–2.06 for HD, without major changes over time. On the contrary, overall rates of isolates increased from 83.03 to 191.34 for D and from 12.21 to 28.35 for HD. The intra-hospital diffusion consisted of 2 small outbreaks without invasive diseases in 2014–2015, and sporadic, not epidemiologically-related cases in 2016–2017. Globally, Escherichia coli and Klebsiella pneumoniae represented 64% of identified CPE, while 70% of carbapenemases identified were metallo-beta-lactamases (VIM or NDM), with changes over time.
In our center metallo-beta lactamases were the most frequently identified carbapenemases in Enterobacteriaceae and E. coli and K. pneumoniae the most frequently isolated pathogens carrying these enzymes. A proactive management strategy was effective in containing in-hospital spreading.
Background
Hirschsprung disease (HSCR) is a congenital anomaly of the enteric nervous system. Abnormal microbiome composition was reported in HSCR patients. In this study, we addressed and analyzed ...microbiome modifications with relation tosurgery and HSCR associated enterocolitis (HAEC).
Methods
The faecal microbiome of 31 HSCR patients (overall 64 samples) was analyzed. HAEC was diagnosed and classified according to a combination of Pastor’s and Elhalabi’s criteria. Stool samples were analyzed by 16S sequencing (7 out of 9 polymorphic regions). Compositional and relative abundance profiles, as well as the functional potentials of the microbial community, were analyzed with the marker gene sequencing profiles using PICRUSt.
Results
The relative abundance of
Bacteroidetes
showed a severe decrease with slow recovery after surgery. Conversely,
Proteobacteria transiently
increased their abundance. Noteworthy, a strong linkage has been found between
Proteobacteria
descendants and HAEC occurrences. The inferred functional analysis indicated that virulence factors and fimbriae or pili might be associated with HAEC.
Conclusions
Our study, addressing microbiome dynamics, demonstrated relevant changes after surgical manipulation. Alpha-diversity analyses indicated that surgery deeply affects microbiome composition.
Proteobacteria
and
Enterobacteriaceae
seem to play a pivotal role in HAEC occurrences. Several virulence factors, such as fimbriae or pili, might explain the HAEC-predisposing potential of selected microbiomes. These results suggest some innovative therapeutic approaches that deserve to be tested in appropriate clinical trials.
Two major receptors involved in human natural cytotoxicity, NKp46 and NKp44, have recently been identified. However, experimental evidence suggested the existence of additional such receptor(s). In ...this study, by the generation of monoclonal antibodies (mAbs), we identified NKp30, a novel 30-kD triggering receptor selectively expressed by all resting and activated human natural killer (NK) cells. Although mAb-mediated cross-linking of NKp30 induces strong NK cell activation, mAb-mediated masking inhibits the NK cytotoxicity against normal or tumor target cells. NKp30 cooperates with NKp46 and/or NKp44 in the induction of NK-mediated cytotoxicity against the majority of target cells, whereas it represents the major triggering receptor in the killing of certain tumors. This novel receptor is associated with CD3zeta chains that become tyrosine phosphorylated upon sodium pervanadate treatment of NK cells. Molecular cloning of NKp30 cDNA revealed a member of the immunoglobulin superfamily, characterized by a single V-type domain and a charged residue in the transmembrane portion. Moreover, we show that NKp30 is encoded by the previously identified 1C7 gene, for which the function and the cellular distribution of the putative product were not identified in previous studies.
Several studies demonstrated a relevant role of polymorphisms located within the HLA-B and -C loci and the Killer Immunoglobulin Receptors (KIRs) 3DL1 and 3DS1 in controlling HIV-1 replication. KIRs ...are regulatory receptors expressed at the surface of NK and CD8+ T-cells that specifically bind HLA-A and -B alleles belonging to the Bw4 supratype and all the -C alleles expressing the C1 or C2 supratype. We here disclose a novel signature associated with the Elite Controller but not with the long-term nonprogressor status concerning 2DS activating KIRs and HLA-C2 alleles insensitive to miRNA148a regulation. Overall, our findings support a crucial role of NK cells in the control of HIV-1 viremia.
In humans, natural killer (NK) cell function is regulated by a series of receptors and coreceptors with either triggering or inhibitory activity. Here we describe a novel 60-kD glycoprotein, termed ...NTB-A, that is expressed by all human NK, T, and B lymphocytes. Monoclonal antibody (mAb)-mediated cross-linking of NTB-A results in the induction of NK-mediated cytotoxicity. Similar to 2B4 (CD244) functioning as a coreceptor in the NK cell activation, NTB-A also triggers cytolytic activity only in NK cells expressing high surface densities of natural cytotoxicity receptors. This suggests that also NTB-A may function as a coreceptor in the process of NK cell activation. Molecular cloning of the cDNA coding for NTB-A molecule revealed a novel member of the immunoglobulin superfamily belonging to the CD2 subfamily. NTB-A is characterized, in its extracellular portion, by a distal V-type and a proximal C2-type domain and by a cytoplasmic portion containing three tyrosine-based motifs. NTB-A undergoes tyrosine phosphorylation and associates with the Src homology 2 domain–containing protein (SH2D1A) as well as with SH2 domain–containing phosphatases (SHPs). Importantly, analysis of NK cells derived from patients with X-linked lymphoproliferative disease (XLP) showed that the lack of SH2D1A protein profoundly affects the function not only of 2B4 but also of NTB-A. Thus, in XLP-NK cells, NTB-A mediates inhibitory rather than activating signals. These inhibitory signals are induced by the interaction of NTB-A with still undefined ligands expressed on Epstein-Barr virus (EBV)-infected target cells. Moreover, mAb-mediated masking of NTB-A can partially revert this inhibitory effect while a maximal recovery of target cell lysis can be obtained when both 2B4 and NTB-A are simultaneously masked. Thus, the altered function of NTB-A appears to play an important role in the inability of XLP-NK cells to kill EBV-infected target cells.
In the absence of sufficient signaling by their HLA class I‐specific inhibitory receptors, human natural killer (NK) cells become activated and display potent cytotoxicity against cells that are ...either HLA class I negative or deficient. This indicates that the NK receptors responsible for the induction of cytotoxicity recognize ligands on target cells different from HLA class I molecules. On this basis, the process of NK‐cell triggering can be considered as a mainly non‐MHC‐restricted mechanism. The recent identification of a group of NK‐specific triggering surface molecules has allowed a first series of pioneering studies on the functional/molecular characteristics of such receptors. The first three members of a receptor family that has been termed natural cytotoxicity receptors (NCR) are represented by NKp46, NKp44 and NKp30. These receptors are strictly confined to NK cells, and their engagement induces a strong activation of NK‐mediated cytolysis. A direct correlation exists between the surface density of NCR and the ability of NK cells to kill various target cells. Importantly, mAb‐mediated blocking of these receptors has been shown to suppress cytotoxicity against most NK‐susceptible target cells. However, the process of NK‐cell triggering during target cell lysis may also depend on the concerted action of NCR and other triggering receptors, such as NKG2D, or surface molecules, including 2B4 and NKp80, that appear to function as co‐receptors rather than as true receptors. Notably, a dysfunction of 2B4 has been associated with a severe form of immunodeficiency termed X‐linked lymphoproliferative disease. Future studies will clarify whether also the altered expression and/or function of other NK‐triggering molecules may represent a possible cause of immunological disorders.
This work was supported by grants awarded by Associazione Italiana per la Ricerca sul Cancro (A.I.R.C.), Istituto Superiore di Sanità (I.S.S.), Ministero della Sanità, and Ministero dell’Università e della Ricerca Scientifica e Tecnologica (M.U.R.S.T.) and Consiglio Nazionale delle Ricerche, Progetto Finalizzato Biotecnologie. The financial support of Telethon‐Italy (grant no. E.0892) is gratefully acknowledged.
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