Staphylococcus aureus β-Hemolysin Up-Regulates the Expression of IFN-γ by Human CD56bright NK Cells.
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ABSTRACT:
SUBMITTER: Guan Z
PROVIDER: S-EPMC8039520 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:ObjectiveThe aim of this study was to characterize the subsets of circulating CD56+ NK cells in pSS patients and their potential value in the diagnosis and/or prediction of prognosis in patients with pSS.MethodsWe included 52 pSS patients fulfilling the 2002 AECG criteria or 2012 ACR criteria and 20 age- and gender-matched healthy volunteers. The frequency and absolute number of NK cells and CD56 NK cell subsets in peripheral blood samples were detected by flow cytometry. Other laboratory parameters such as the IgG level and complement protein levels were extracted from the clinical system.ResultsBoth the frequency and the absolute number of peripheral blood NK cells were reduced in pSS patients compared to healthy controls. The proportion of CD56bright NK cell subset was increased, and the proportion of CD56dim NK cell subset was decreased among NK cells, resulting in the ratio of CD56bright NK to CD56dim NK which was significantly elevated in pSS patients. ROC analysis indicated that the AUC of CD56bright NK/CD56dim NK ratio was 0.838, and the best diagnostic cut-off point was 0.0487 for pSS patients. Furthermore, this CD56bright NK/CD56dim NK ratio was positively correlated with the IgG level and negatively correlated with the complement protein C3 and C4 levels. More importantly, the CD56bright/CD56dim NK ratio was either slightly increased or not changed in other autoimmune diseases such as SLE and IgG4-related disease.ConclusionOur findings suggest that the ratio of blood CD56bright NK to CD56dim NK might have a diagnostic value relatively specific for pSS.
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Project description:The roles of NK cells in human melanoma remain only partially understood. We characterized NK cells from peripheral blood ex vivo by flow cytometry obtained from late stage (III/IV) melanoma patients. Interestingly, we found that the abundance of CD56bright NK cells negatively correlate with overall patient survival, together with distant metastases, in a multivariate cox regression analysis. The patients' CD56bright NK cells showed upregulation of CD11a, CD38 and CD95 as compared to healthy controls, pointing to an activated phenotype as well as a possible immune regulatory role in melanoma patients. After stimulation in vitro, CD56bright NK cells produced less TNFα and GMCSF in patients than controls. Furthermore, IFNγ production by the CD56bright NK cells correlated inversely with overall survival. Our results highlight that abundance and function of CD56bright NK cells are associated with melanoma patient survival, emphasizing the potential of NK cell subsets for biomarker discovery and future therapeutic targeting.
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Project description:Multiple sclerosis (MS) is a chronic demyelinating disease characterised by immune cell infiltration resulting in lesions that preferentially affect periventricular areas of the brain. Despite research efforts to define the role of various immune cells in MS pathogenesis, the focus has been on a few immune cell populations while full-spectrum analysis, encompassing others such as natural killer (NK) cells, has not been performed. Here, we used single-cell mass cytometry (CyTOF) to profile the immune landscape of brain periventricular areas - septum and choroid plexus - and of the circulation from donors with MS, dementia and controls without neurological disease. Using a 37-marker panel, we revealed the infiltration of T cells and antibody-secreting cells in periventricular brain regions and identified a novel NK cell signature specific to MS. CD56bright NK cells were accumulated in the septum of MS donors and displayed an activated and migratory phenotype, similar to that of CD56bright NK cells in the circulation. We validated this signature by multiplex immunohistochemistry and found that the number of NK cells with high expression of granzyme K, typical of the CD56bright subset, was increased in both periventricular lesions and the choroid plexus of donors with MS. Together, our multi-tissue single-cell data shows that CD56bright NK cells accumulate in the periventricular brain regions of MS patients, bringing NK cells back to the spotlight of MS pathology.
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Project description:Human natural killer (NK) cells are divided into two subsets: CD56bright and CD56dim NK cells, which differ in maturation, function and distribution. Mechanisms regulating NK cell functions are not completely understood. Aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor, that binds to a variety of endogenous and exogenous molecules, and that has recently been shown to modulate the function and differentiation of immune cells. Here, we studied the expression of AhR and its involvement in the regulation of NK cell functions. We found that AhR mRNA is highly expressed in peripheral CD56bright NK cells and that AhR mRNA expression gradually decreases as NK cells display a more mature phenotype. CD56bright NK cells were highly sensitive to AhR ligands. Specifically, AhR ligands modulated their activation and their expression of NK cell receptors, as well as cytokine secretion which is the major function of these cells. As CD56bright NK cells are highly enriched in tissues and in tumors, our observations point to a possible effect of local AhR ligands in the regulation of the function of CD56bright tissue-resident or intratumoral NK cells.
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Project description:Staphylococcus aureus gamma-hemolysin CB (HlgCB) is a core-genome-encoded pore-forming toxin that targets the C5a receptor, similar to the phage-encoded Panton-Valentine leucocidin (PVL). Absolute quantification by mass spectrometry of HlgCB in 39 community-acquired pneumonia (CAP) isolates showed considerable variations in the HlgC and HlgB yields between isolates. Moreover, although HlgC and HlgB are encoded on a single operon, their levels were dissociated in 10% of the clinical strains studied. To decipher the molecular basis for the variation in hlgCB expression and protein production among strains, different regulation levels were analyzed in representative clinical isolates and reference strains. Both the HlgCB level and the HlgC/HlgB ratio were found to depend on hlgC promoter activity and mRNA processing and translation. Strikingly, only one single nucleotide polymorphism (SNP) in the 5' untranslated region (UTR) of hlgCB mRNA strongly impaired hlgC translation in the USA300 strain, leading to a strong decrease in the level of HlgC but not in HlgB. Finally, we found that high levels of HlgCB synthesis led to mortality in a rabbit model of pneumonia, correlated with the implication of the role of HlgCB in severe S. aureus CAP. Taken together, this work illustrates the complexity of virulence factor expression in clinical strains and demonstrates a butterfly effect where subtle genomic variations have a major impact on phenotype and virulence. IMPORTANCE S. aureus virulence in pneumonia results in its ability to produce several virulence factors, including the leucocidin PVL. Here, we demonstrate that HlgCB, another leucocidin, which targets the same receptors as PVL, highly contributes to S. aureus virulence in pvl-negative strains. In addition, considerable variations in HlgCB quantities are observed among clinical isolates from patients with CAP. Biomolecular analyses have revealed that a few SNPs in the promoter sequences and only one SNP in the 5' UTR of hlgCB mRNA induce the differential expression of hlgCB, drastically impacting hlgC mRNA translation. This work illustrates the subtlety of regulatory mechanisms in bacteria, especially the sometimes major effects on phenotypes of single nucleotide variation in noncoding regions.
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Project description:The crosstalk between NK cells and their surrounding environment is enabled through activating and inhibitory receptors, which tightly control NK cell activity. The co-inhibitory receptor TIGIT decreases NK cell cytotoxicity and is involved in NK cell exhaustion, but has also been associated with liver regeneration, highlighting that the contribution of human intrahepatic CD56bright NK cells in regulating tissue homeostasis remains incompletely understood. A targeted single-cell mRNA analysis revealed distinct transcriptional differences between matched human peripheral blood and intrahepatic CD56bright NK cells. Multiparameter flow cytometry identified a cluster of intrahepatic NK cells with overlapping high expression of CD56, CD69, CXCR6, TIGIT and CD96. Intrahepatic CD56bright NK cells also expressed significantly higher protein surface levels of TIGIT, and significantly lower levels of DNAM-1 compared to matched peripheral blood CD56bright NK cells. TIGIT+ CD56bright NK cells showed diminished degranulation and TNF-α production following stimulation. Co-incubation of peripheral blood CD56bright NK cells with human hepatoma cells or primary human hepatocyte organoids resulted in migration of NK cells into hepatocyte organoids and upregulation of TIGIT and downregulation of DNAM-1 expression, in line with the phenotype of intrahepatic CD56bright NK cells. Intrahepatic CD56bright NK cells represent a transcriptionally, phenotypically, and functionally distinct population of NK cells that expresses higher levels of TIGIT and lower levels of DNAM-1 than matched peripheral blood CD56bright NK cells. Increased expression of inhibitory receptors by NK cells within the liver environment can contribute to tissue homeostasis and reduction of liver inflammation.
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Project description:Natural killer (NK) cells preferentially accumulate at maternal-foetal interface and are believed to play vital immune-modulatory roles during early pregnancy and related immunological dysfunction may result in pregnant failure such as recurrent miscarriage (RM). However, the mechanisms underlying the establishment of maternal-foetal immunotolerance are complex but clarifying the roles of decidual NK (dNK) cells offers the potential to design immunotherapeutic strategies to assist RM patients. In this report, we analysed RNA sequencing on peripheral NK (pNK) and decidual NK cells during early pregnancy; we identified an immunomodulatory dNK subset CXCR4+ CD56bright dNK and investigated its origin and phenotypic and functional characteristics. CXCR4+ CD56bright dNK displayed a less activated and cytotoxic phenotype but an enhanced immunomodulatory potential relative to the CXCR4 negative subset. CXCR4+ CD56bright dNK promote Th2 shift in an IL-4-dependent manner and can be recruited from peripheral blood and reprogramed by trophoblasts, as an active participant in the establishment of immune-tolerance during early pregnancy. Diminished CXCR4+ dNK cells and their impaired ability to induce Th2 differentiation were found in RM patients and mouse models of spontaneous abortion. Moreover, adoptive transfer of CXCR4+ dNK cells to NK-deficient (Nfil3-/-) mice showed great therapeutic potential of CXCR4+ dNK via recovering the Th2/Th1 bias and reducing embryo resorption rates. The identification of this new dNK cell subset may lay the foundation for understanding NK cell mechanisms in early pregnancy and provide potential prognostic factors for the diagnosis and therapy of RM.
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Project description:Major surgery increases the risk for infectious complications due to the development of immunosuppression. CD56 bright NK cells play a key role in the defense against bacterial infections through the release of Interferon (IFN) γ upon stimulation with monocyte-derived Interleukin (IL) 12. We investigated whether invasive visceral surgery interferes with the IFN-γ synthesis of human NK cells in response to Staphylococcus aureus. In a prospective pilot study, peripheral blood mononuclear cells (PBMC) were isolated from 53 patients before and 1 to 7 d after elective visceral surgery. The release of IL-12 and IFN-γ from PBMC upon exposure to S. aureus in vitro was quantified. The expression of the IL-12 receptor β1 chain on the surface, the phosphorylation of signal transducer and activator of transcription (STAT) 4, and the synthesis of IFN-γ on/in individual CD56 bright NK cells were investigated using flow cytometry. The modulatory effect of IL-12 on the S. aureus-induced IFN-γ production in CD56 bright NK cells was analyzed. The IFN-γ secretion from purified CD56 bright NK cells was quantified after stimulation with IL-12 and IL-18. After surgery, CD56 bright NK cells among total PBMC were impaired in the release of IFN-γ for at least 5 d. Likewise, the IL-12-induced release of IFN-γ from purified CD56 bright NK cells was abolished. Upon stimulation with S. aureus, PBMC secreted less IL-12 but supplementation with recombinant IL-12 did not restore the capacity of CD56 bright NK cells to produce IFN-γ. CD56 bright NK cells displayed reduced levels of the IL-12Rβ1 chain whereas the phosphorylation of STAT4, the key transcription factor for the Ifng gene was not diminished. In summary, after invasive visceral surgery, CD56 bright NK cells are impaired in S. aureus-induced IFN-γ production and might contribute to the enhanced susceptibility to opportunistic infections.
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Project description:The cytokine IL15 is required for survival and activation of natural killer (NK) cells as well as expansion of NK-cell populations. Here, we compare the effects of continuous IL15 infusions on NK-cell subpopulations in cancer patients. Infusions affected the CD56bright NK-cell subpopulation in that the expansion rates exceeded those of CD56dim NK-cell populations with a 350-fold increase in their total cell numbers compared with 20-fold expansion for the CD56dim subset. CD56bright NK cells responded with increased cytokine release to various stimuli, as expected given their immunoregulatory functions. Moreover, CD56bright NK cells gained the ability to kill various target cells at levels that are typical for CD56dim NK cells. Some increased cytotoxic activities were also observed for CD56dim NK cells. IL15 infusions induced expression changes on the surface of both NK-cell subsets, resulting in a previously undescribed and similar phenotype. These data suggest that IL15 infusions expand and arm CD56bright NK cells that alone or in combination with tumor-targeting antibodies may be useful in the treatment of cancer. Cancer Immunol Res; 5(10); 929-38. ©2017 AACR.
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Project description:Several lines of evidence support the concept that NK cells play an important role in control of hepatitis C virus (HCV) infection via cytokine secretion and cytotoxicity. IL-7 is a homeostatic cytokine with a role in T cell development, activation, proliferation, and cytokine secretion. The IL-7R? chain [cluster of differentiation (CD)127] is expressed on NK cells, with greatest abundance on the CD56brightCD16dim/- (CD56bright) subset. Here, we measured CD127 expression on CD56bright, CD56dimCD16+ (CD56dim), or CD56negCD16+ (CD56neg) NK cell subsets of 25 uninfected donors (UD); 34 chronic HCV-infected, treatment-naïve; 25 HIV-infected, virally suppressed on antiretroviral therapy (ART); and 42 HCV-HIV-coinfected subjects on ART. Interestingly, CD127 expression on CD56bright NK cells negatively correlated with HCV plasma levels in HCV monoinfection and HCV-HIV coinfection. IL-7 induced CD69 expression, as well as IFN-? production, in CD56bright NK cells and also enhanced the IFN-?-induced CD69 expression on these cells. The latter was impaired in HIV infection. Furthermore, IL-7 induced B cell lymphoma 2 (BCL-2) expression and cell cycling of CD56bright NK cells, and this effect was impaired in HCV- and HIV-infected subjects. Whereas IL-7-stimulated CD56bright NK cell degranulation appeared intact in all cohorts, we observed impaired IL-7-activated NK cell cytolytic function in HCV- and HIV-infected subjects. Finally, IL-7-induced phosphorylation of STAT-5 (pSTAT-5) signaling was impaired in NK cells of subjects with chronic viral infection, and this was reversible upon 6 mo of viral suppression with IFN-free HCV therapy. These results implicate that IL-7-dependent NK cell activation and effector function may be other host immune surveillance mechanisms that are impaired in viral infections.
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