IFN type I and type II independent enhancement of B cell TLR7 expression by natural killer cells.
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ABSTRACT:
SUBMITTER: Sinha S
PROVIDER: S-EPMC3441313 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The TLR7 agonist imiquimod has been used successfully as adjuvant for skin treatment of virus-associated warts and basal cell carcinoma. The effects of skin TLR7 triggering on respiratory leukocyte populations are unknown. In a placebo-controlled experimental animal study we have used multicolour flow cytometry to systematically analyze the modulation of respiratory leukocyte subsets after skin administration of imiquimod. Compared to placebo, skin administration of imiquimod significantly increased respiratory dendritic cells (DC) and natural killer cells, whereas total respiratory leukocyte, alveolar macrophages, classical CD4+ T helper and CD8+ T killer cell numbers were not or only moderately affected. DC subpopulation analyses revealed that elevation of respiratory DC was caused by an increase of respiratory monocytic DC and CD11b(hi) DC subsets. Lymphocyte subpopulation analyses indicated a marked elevation of respiratory natural killer cells and a significant reduction of B lymphocytes. Analysis of cytokine responses of respiratory leukocytes after stimulation with Klebsiella pneumonia indicated reduced IFN-? and TNF-? expression and increased IL-10 and IL-12p70 production after 7 day low dose skin TLR7 triggering. Additionally, respiratory NK cytotoxic activity was increased after 7d skin TLR7 triggering. In contrast, lung histology and bronchoalveolar cell counts were not affected suggesting that skin TLR7 stimulation modulated respiratory leukocyte composition without inducing overt pulmonary inflammation. These data suggest the possibility to modulate respiratory leukocyte composition and respiratory cytokine responses against pathogens like Klebsiella pneumonia through skin administration of a clinically approved TLR7 ligand. Skin administration of synthetic TLR7 ligands may represent a novel, noninvasive means to modulate respiratory immunity.
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Project description:Natural killer T (NKT) cells are αβ T cell receptor (TCR) expressing innate-like T cells that display natural killer (NK) cell markers. Based on TCR characteristics, they are divided into two groups restricted to the MHC class I-like molecule CD1d. Type I NKT cells, most extensively studied, are identified by a semi-invariant Vα14-Jα18 (mouse, Vα24-Jα18 in humans) TCR reactive to the prototypic ligand α-galactosylceramide presented on CD1d. In contrast, type II NKT cells display diverse TCR reacting to different CD1d-presented ligands. There are no reagents that identify all type II NKT cells, limiting their exploration. Here, we searched for novel type II NKT cells by comparing Jα18-/- MHCII-/- mice that harbour type II but not type I NKT cells, and CD1d-/- MHCII-/- mice, lacking all NKT cells. We identified significantly larger populations of CD4+ and CD4- CD8- (double negative, DN) TCRβ+ cells expressing NKG2D or NKG2A/C/E in Jα18-/- MHCII-/- mice compared with CD1d-/- MHCII-/- mice, suggesting that 30%-50% of these cells were type II NKT cells. They expressed CD122, NK1.1, CXCR3 and intermediate/low levels of CD45RB. Further, the CD4+ subset was CD69+ , while the DN cells were CD49b+ and CD62L+ . Both subsets expressed the NKT cell-associated promyelocytic leukaemia zinc finger (PLZF) transcription factor and Tbet, while fewer cells expressed RORγt. NKG2D+ CD4+ and DN populations were producers of IFN-γ, but rarely IL-4 and IL-17. Taken together, we identify a novel subset of primary CD4+ and DN type II NKT cells that expresses NKG2 receptors have typical NKT cell phenotypes and a TH1-like cytokine production.
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Project description:Natural killer (NK) cells are important antiviral effector cells and also involved in tumor clearance. NK cells express IFNAR, rendering them responsive to Type I IFNs. To evaluate Type I IFN-mediated modulation of NK cell functions, individual Type I IFNs subtypes were assessed for their ability to activate NK cells. Different Type I IFN subtypes displayed a broad range in the capacity to induce and modulate NK cell activation and degranulation, measured by CD69 and CD107a expression in response to leukemia cell line K562. When including biological sex as a variable in the analysis, transwell co-cultures of NK cells with either male- or female-derived PBMCs or pDCs stimulated with the TLR7/8 agonist CL097 showed that NK cells were more activated by CL097-stimulated cells derived from females. These sex-specific differences were linked to higher CL097-induced IFNα production by pDCs derived from females, indicating an extrinsic sex-specific effect of Type I IFNs on NK cell function. Interestingly, in addition to the extrinsic effect, we also observed NK cell-intrinsic sex differences, as female NK cells displayed higher activation levels after IFNα-stimulation and after co-culture with CL097-stimulated pDCs, suggesting higher activation of IFNα-signaling transduction in female NK cells. Taken together, the results from these studies identify both extrinsic and intrinsic sex-specific differences in Type I IFN-dependent NK cell functions, contributing to a better understanding of sex-specific differences in innate immunity.
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Project description:UNLABELLED:Ribavirin (RBV) is an important component of interferon (IFN)-based and direct antiviral treatment regimens for hepatitis C virus (HCV) infection. Immunomodulation, in particular improvement of the host IFN response, has been proposed as RBV's mechanism of action. Natural killer (NK) cells are sensitive biomarkers for IFN-?/? receptor signaling, as NK cell cytotoxicity and IFN-? production are regulated by signal transducer and activator of transcription (STAT)1- and STAT4-phosphorylation, respectively. Specifically, pSTAT1-dependent NK cell cytotoxicity increases and pSTAT4-dependent IFN-? production decreases in response to endogenous, virus-induced IFN-? and during IFN-?-based therapy. To assess whether RBV has a direct effect on NK cells and/or improves the IFN-? response of NK cells in the presence of IFN-?, we prospectively studied 22 HCV patients with and 32 patients without 4 weeks of RBV pretreatment, who all received subsequent pegylated (Peg)IFN/ribavirin combination therapy. During RBV pretreatment, both the frequency of CD56(dim) NK cells with cytotoxic effector functions and the frequency of CD56(bright) NK cells with the capacity to produce IFN-? decreased (P?=?0.049 and P?=?0.001, respectively). In vitro or in vivo exposure of NK cells to RBV improved the pSTAT4 (P?<?0.01) but not pSTAT1 response of NK cells to subsequent stimulation with IFN-?. This was associated with an increase in IFN-? production but not cytotoxicity of NK cells during subsequent IFN-?-based therapy. The frequency of IFN-?-producing NK cells was greater in fast second-phase virological responders than in slow responders. CONCLUSION:RBV enhances the pSTAT4 and IFN-? response of NK cells to IFN-?-stimulation.
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