Abstract
BackgroundHuman natural killer (NK) cells are the key contributors of innate immune response and the effector functions of these cells are enhanced by cytokines such as interleukine 2 (IL2). We utilized genome-wide transcriptional profiling to identify gene expression signatures and pathways in resting and IL2 activated NK cell isolated from peripheral blood of healthy donors.ResultsGene expression profiling of resting NK cells showed high expression of a number of cytotoxic factors, cytokines, chemokines and inhibitory and activating surface NK receptors. Resting NK cells expressed many genes associated with cellular quiescence and also appeared to have an active TGFβ (TGFB1) signaling pathway. IL2 stimulation induced rapid downregulation of quiescence associated genes and upregulation of genes associated with cell cycle progression and proliferation. Numerous genes that may enhance immune function and responsiveness including activating receptors (DNAM1, KLRC1 and KLRC3), death receptor ligand (TNFSF6 (FASL) and TRAIL), chemokine receptors (CX3CR1, CCR5 and CCR7), interleukin receptors (IL2RG, IL18RAB and IL27RA) and members of secretory pathways (DEGS1, FKBP11, SSR3, SEC61G and SLC3A2) were upregulated. The expression profile suggested PI3K/AKT activation and NF-κB activation through multiple pathways (TLR/IL1R, TNF receptor induced and TCR-like possibly involving BCL10). Activation of NFAT signaling was supported by increased expression of many pathway members and downstream target genes. The transcription factor GATA3 was expressed in resting cells while T-BET was upregulated on activation concurrent with the change in cytokine expression profile. The importance of NK cells in innate immune response was also reflected by late increased expression of inflammatory chemotactic factors and receptors and molecules involved in adhesion and lymphocyte trafficking or migration.ConclusionThis analysis allowed us to identify genes implicated in cellular quiescence and the cytokines and cytotoxic factors ready for immediate immune response. It also allowed us to observe the sequential immunostimulatory effects of IL2 on NK cells improving our understanding of the biology and molecular mediators behind NK cell activation.
Highlights
Human natural killer (NK) cells are the key contributors of innate immune response and the effector functions of these cells are enhanced by cytokines such as interleukine 2 (IL2)
The death receptor pathway is based on the interaction between NK surface-bound ligands such as TNFSF6 (FASL) and TRAIL or NK-secreted factors such as TNFα, LTA and LTB [11] with death receptors on the target cells thereby triggering a signaling cascade resulting in apoptosis of the targeted cells
NK cells with the CD56+/CD16+ and CD3- phenotype were negatively selected by immunomagnetic beads and re-examined by flow-cytometry to ensure greater than 90% purity (Figure 1)
Summary
Human natural killer (NK) cells are the key contributors of innate immune response and the effector functions of these cells are enhanced by cytokines such as interleukine 2 (IL2). The majority of NK cells (90%) are CD56dimCD16bright – and mediate cytolytic activity against tumor or pathogen-infected cells whereas the remaining (10%) are cytokine producing NK cells with a CD56brightCD16dim/negativephenotype[6]. These NK subsets express distinct chemokines that are important in their preferential localization within the lymphatic system [7]. Spontaneous cytotoxicity is initiated by ligand binding to activating NK receptors resulting in sequential recruitment and activation of SRC and SYK kinases, PI3K, RAC1, PAK1, MEK and ERK, leading to Perforin 1 and Granzyme B granule polarization and movement toward the ligated target cell [9]. The death receptor pathway is based on the interaction between NK surface-bound ligands such as TNFSF6 (FASL) and TRAIL or NK-secreted factors such as TNFα, LTA and LTB [11] with death receptors on the target cells thereby triggering a signaling cascade resulting in apoptosis of the targeted cells
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
