scholarly journals Subdiffraction-resolution fluorescence imaging of immunological synapse formation between NK cells and A. fumigatus by expansion microscopy

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Nora Trinks ◽  
Sebastian Reinhard ◽  
Matthias Drobny ◽  
Linda Heilig ◽  
Jürgen Löffler ◽  
...  
Keyword(s):  
Nk Cells ◽  
Fluorescence Imaging ◽  
Synapse Formation ◽  
Immunological Synapse ◽  
Nk Cell ◽  
Super Resolution ◽  
Cell Types ◽  
Lytic Granules ◽  
Isotropic Expansion ◽  
Confocal Fluorescence Imaging

AbstractExpansion microscopy (ExM) enables super-resolution fluorescence imaging on standard microscopes by physical expansion of the sample. However, the investigation of interactions between different organisms such as mammalian and fungal cells by ExM remains challenging because different cell types require different expansion protocols to ensure identical, ideally isotropic expansion of both partners. Here, we introduce an ExM method that enables super-resolved visualization of the interaction between NK cells and Aspergillus fumigatus hyphae. 4-fold expansion in combination with confocal fluorescence imaging allows us to resolve details of cytoskeleton rearrangement as well as NK cells’ lytic granules triggered by contact with an RFP-expressing A. fumigatus strain. In particular, subdiffraction-resolution images show polarized degranulation upon contact formation and the presence of LAMP1 surrounding perforin at the NK cell-surface post degranulation. Our data demonstrate that optimized ExM protocols enable the investigation of immunological synapse formation between two different species with so far unmatched spatial resolution.

scholarly journals Natural killer cell immune synapse formation and cytotoxicity are controlled by tension of the target interface

2021 ◽  
pp. jcs.258570
Author(s):  
Daniel Friedman ◽  
Poppy Simmonds ◽  
Alexander Hale ◽  
Leoma Bere ◽  
Nigel W. Hodson ◽  
...  
Keyword(s):  
Nk Cells ◽  
Natural Killer ◽  
Synapse Formation ◽  
Nk Cell ◽  
Killer Cell ◽  
Blind Spot ◽  
Immune Synapse ◽  
Lytic Granules ◽  
Planar Substrates ◽  
Soft Targets

Natural Killer (NK) cells can kill infected or transformed cells via a lytic immune synapse. Diseased cells may exhibit altered mechanical properties but how this impacts NK cell responsiveness is unknown. We report that human NK cells were stimulated more effectively to secrete granzymes A and B, FasL, granulysin and IFNγ, by stiff (142 kPa) compared to soft (1 kPa) planar substrates. To create surrogate spherical targets of defined stiffness, sodium alginate was used to synthesise soft (9 kPa), medium (34 kPa), or stiff (254 kPa) cell-sized beads, coated with antibodies against activating receptor NKp30 and the integrin LFA-1. Against stiff beads, NK cells showed increased degranulation. Polarisation of the microtubule-organising centre (MTOC) and lytic granules were impaired against soft targets, which instead resulted in the formation of unstable kinapses. Thus, by varying target stiffness to characterise the mechanosensitivity of immune synapses, we identify soft targets as a blind spot in NK cell recognition.

Ex Vivo IL-2 Expansion of CB-NK Cells Promotes Synergistic LFA-1 and CD2 Engagement at the NK Cell Lytic Immune Synapse; Implications for Adoptive CB-NK Cell Therapy in Acute Myeloid Leukemia.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3029-3029
Author(s):  
Dongxia Xing ◽  
Alan G. Ramsay ◽  
William Decker ◽  
Sufang Li ◽  
Simon Robinson ◽  
...  
Keyword(s):  
Cord Blood ◽  
Nk Cells ◽  
Synapse Formation ◽  
Immunological Synapse ◽  
Nk Cell ◽  
Ex Vivo ◽  
Immune Therapy ◽  
Cytolytic Activity ◽  
Lymphocyte Function ◽  
Immune Synapse

Abstract Abstract 3029 Poster Board II-1005 Donor peripheral blood (PB) natural killer (NK) cell have shown clinical promise in cancer immunotherapy. Tightly regulated receptor signaling between NK cells and susceptible tumor cells is essential for NK cell-mediated cytotoxicity. Umbilical cord blood (CB) represents an important alternative source of NK cells for adoptive immune therapy. We first demonstrated that cord blood (CB) derived NK cells have poor cytolytic activity and deficiency in the formation of the F-actin immunological synapse with HLA class I deficient target K562 cells and primary AML blasts compared to PB-NK cells. In this study, we explored the cellular mechanism of these dysfunctions. We hypothesized that adhesion and signaling molecules may be defective in unmanipulated CB NK cells. Activating receptor Both CD2 and the integrin lymphocyte function-associated antigen (LFA-1) play important roles in both T lymphocyte and NK cell immune synapse formation and their trafficking to the immune synapse regulates both T and NK cell function. We now show that unmanipulated CB NK cells exhibit reduced LFA-1 mediated adhesion to mobilized ICAM-1 compared to IL-2 expanded CB NK cells (CB NK 29.7+/- 3.2 %, vs expanded CB NK 78.5+/- 6.1%, n=6). Moreover, unmanipulated CB-NK cells demonstrated reduced surface expression of CD2, and high affintyLFA-1 detected by the specific antibody (MHM24). There was decreased recruitment of CD2 and LFA-1 to the NK cell immune synapse site as quantified by confocal microscope analysis (RRI CD2 CB NK 2.02 vs PB NK 4.98, n=3). Furthermore, defective LFA-1 trafficking lead to a decrease in downstream cytotoxic granules that traffic to the immunological synapse as demonstrated by decreased perforin trafficking to the CB-NK synapse site (> 60% reduction).We next wanted to confirm that CD2 or LFA-1 play a role in restoring the immune synapseformation for IL-2 expanded CB NK cells. We incubated expanded CB NK cells with blocking antibodies specific for LFA-1 or CD2 prior to conjugation to the K562 target cells. After CD2 or LFA-1 blocking there was decreased synapse formation, with a resultant decrease in cytotoxic function. When monoclonal antibodies against both CD2 and LFA-1 were used there was significant blockade of the formation of the immune synapse, and a marked reduction of CB NK cell cytolytic activity (Mean specific lysis of K562 targets at E:T ratio 20:1 was 81% IgG control vs 22% with anti-CD2; and 29% with anti-LFA-1, n=6, P<0.001). This data shows that CD2 and LFA-1 are defective in unmanipulated CB NK cells resulting in impaired immune synapse formation. In contrast, ex vivo IL-2 expansion of CB-NK cells enhanced lytic synapse formation with the synergistic repair of CD2 and LFA-1 localization and activity. We believe our results provide important mechanistic insights for the potential use of IL-2 expanded CB-derived NK cells for adoptive immune therapy in leukemia. Disclosures No relevant conflicts of interest to declare.

scholarly journals Super-resolution imaging of remodeled synaptic actin reveals different synergies between NK cell receptors and integrins

Blood ◽  
2012 ◽  
Vol 120 (18) ◽  
pp. 3729-3740 ◽  
Author(s):  
Alice C. N. Brown ◽  
Ian M. Dobbie ◽  
Juha-Matti Alakoskela ◽  
Ilan Davis ◽  
Daniel M. Davis
Keyword(s):  
Nk Cells ◽  
Nk Cell ◽  
Three Dimensional ◽  
Super Resolution ◽  
Cortical Actin ◽  
Cell Receptors ◽  
Lytic Granules ◽  
Nk Cell Receptors ◽  
Activating Receptors ◽  
Ifn Γ

Abstract Natural killer (NK) cells secrete lytic granules to directly kill virus-infected or transformed cells and secrete cytokines to communicate with other cells. Three-dimensional super-resolved images of F-actin, lytic granules, and IFN-γ in primary human NK cells stimulated through different activating receptors reveal that both IFN-γ and lytic granules accumulated in domains where the periodicity of the cortical actin mesh at the synapse opened up to be penetrable. Ligation of some activating receptors alone (eg, CD16 or NKG2D) was sufficient to increase the periodicity of the actin mesh, but surprisingly, ligation of others (eg, NKp46 or CD2) was not sufficient to induce cortical actin remodeling unless LFA-1 was coligated. Importantly, influenza virus particles that can be recognized by NK cells similarly did not open the actin mesh but could if LFA-1 was coligated. This leads us to propose that immune cells using germline-encoded receptors to directly recognize foreign proteins can use integrin recognition to differentiate between free pathogens and pathogen-infected cells that will both be present in blood. This distinction would not be required for NK cell receptors, such as NKG2D, which recognize host cell–encoded proteins that can only be found on diseased cells and not pathogens.

Lenalidomide Treatment Enhances Immunological Synapse Formation of Cord Blood Natural Killer Cells with B Cells Derived From Chronic Lymphocytic Leukemia

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1794-1794 ◽  
Author(s):  
Dongxia Xing ◽  
Alan G. Ramsay ◽  
Simon Robinson ◽  
Catherine M. Bollard ◽  
Nina Shah ◽  
...  
Keyword(s):  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
Nk Cells ◽  
Actin Polymerization ◽  
Synapse Formation ◽  
Immunological Synapse ◽  
Nk Cell ◽  
Immune Dysfunction ◽  
Lymphocytic Leukemia ◽  
Immune Synapse

Abstract Abstract 1794 Immune dysfunction is a hallmark of chronic lymphocytic leukemia (CLL) including suppressed humoral and cell-mediated immune responses. The immunomodulatory agent lenalidomide has shown effective clinical activity against CLL, but its mechanism of action is poorly understood. Previous work has demonstrated that the T cell immunological synapse and functional defects in CLL can be reversed following lenalidomide treatment (J Clin Invest. 2008; 118). Polymerization of F-actin at the NK cell immunological synapse with tumor cells is required for signaling molecules to assemble and regulate NK cell activation and effector function. Confocal microscopy was used to visualize and analyze F-actin polymerization at the immune synapse between NK cells and CLL cells. The impaired immune synapse defect identified in CLL could result from not only the defects of CLL B cells but also defects in the CLL NK cells or a combination of both factors. To investigate the contribution of each factor, we examined synapse formation in experiments using CLL B cells with autologous CLL NK cells or healthy allogeneic NK cells. Conjugates formed with healthy NK cells and CLL B cells exhibited a strong band of F-actin at the immune synapse. In contrast, significantly less actin polymerization at the synapse was observed in autologous CLL NK cells and CLL B cells (P < 0.01). These results indicate CLL B cells, together with CLL NK cells contributed to the immune dysfunction in CLL. As autologous NK cell function in CLL is suppressed, we investigated the utility of CB as a potential functional source of NK cells for CLL immunotherapy. We examined the effect of lenalidomide on NK cell immune synapse function with CLL B cells acting as APCs. We demonstrated that ex vivo treatment of CLL cells with lenalidomide (500 ng/ml) for 48 hours caused a significant increase in the ability of autologous CLL NK cells to form F-actin immune synapses with CLL B cells. The same treatment of CLL B cells also significantly increased the ability of CB-NK cells to form F-actin immunological synapses with these treated CLL B cells compared to untreated CLL B cells (33.6% to 67.3%, P < 0.01, n=6). Our results also show that lenalidomide treatment of autologous NK cells from CLL patients enhanced synapse formation with treated CLL cells compared to experiments using untreated NK cells, but with reduced function compared to CB NK cells. Of note, lenalidomide treatment was shown to increase the recruitment of the signaling molecule Lck to NK cell:CLL cell synapse site, that is known to regulate lytic synapse function. Importantly, lenalidomide treatment significantly increased CB-NK killing of CLL B cells compared to untreated CLL B cells (20.5% versus 48.2%, E:T ratio of 10:1, n = 6, p < 0.001). These results provide insight into the potential mechanism of action of lenalidomide's anti-leukemic function – priming CLL tumor cells for enhanced NK cell lytic synapse formation and effector function. In addition, the data suggests that immunotherapeutic strategies utilizing a combination of CB-NK cells and lenalidomide has an enhanced clinical efficacy in CLL. Disclosures: Gribben: Roche: Honoraria; Celgene: Honoraria; GSK: Honoraria; Mundipharma: Honoraria; Gilead: Honoraria; Pharmacyclics: Honoraria.

scholarly journals CD56 regulates human NK cell cytotoxicity through Pyk2

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Justin T Gunesch ◽  
Amera L Dixon ◽  
Tasneem AM Ebrahim ◽  
Melissa M Berrien-Elliott ◽  
Swetha Tatineni ◽  
...  
Keyword(s):  
Nk Cells ◽  
Immune Cells ◽  
Immunological Synapse ◽  
Nk Cell ◽  
Functional Link ◽  
Lytic Granules ◽  
Nk Cell Cytotoxicity ◽  
Lytic Granule ◽  
Cytotoxic Function

Human natural killer (NK) cells are defined as CD56+CD3−. Despite its ubiquitous expression on human NK cells the role of CD56 (NCAM) in human NK cell cytotoxic function has not been defined. In non-immune cells, NCAM can induce signaling, mediate adhesion, and promote exocytosis through interactions with focal adhesion kinase (FAK). Here we demonstrate that deletion of CD56 on the NK92 cell line leads to impaired cytotoxic function. CD56-knockout (KO) cells fail to polarize during immunological synapse (IS) formation and have severely impaired exocytosis of lytic granules. Phosphorylation of the FAK family member Pyk2 at tyrosine 402 is decreased in NK92 CD56-KO cells, demonstrating a functional link between CD56 and signaling in human NK cells. Cytotoxicity, lytic granule exocytosis, and the phosphorylation of Pyk2 are rescued by the reintroduction of CD56. These data highlight a novel functional role for CD56 in stimulating exocytosis and promoting cytotoxicity in human NK cells.

scholarly journals Cdc42-interacting protein–4 functionally links actin and microtubule networks at the cytolytic NK cell immunological synapse

2007 ◽  
Vol 204 (10) ◽  
pp. 2305-2320 ◽  
Author(s):  
Pinaki P. Banerjee ◽  
Rahul Pandey ◽  
Rena Zheng ◽  
Megan M. Suhoski ◽  
Linda Monaco-Shawver ◽  
...  
Keyword(s):  
Actin Filament ◽  
Cell Activation ◽  
Immunological Synapse ◽  
Nk Cell ◽  
Filamentous Actin ◽  
Microtubule Organizing Center ◽  
Interacting Protein ◽  
Lytic Granules ◽  
Organizing Center ◽  
Microtubule Networks

An essential function of the immunological synapse (IS) is directed secretion. NK cells are especially adept at this activity, as they direct lytic granules to the synapse for secretion, which enables cytotoxicity and facilitates host defense. This initially requires rearrangement of the actin cytoskeleton and, subsequently, microtubule-dependent trafficking of the lytic granules. As these two steps are sequential, specific linkages between them are likely to serve as critical regulators of cytotoxicity. We studied Cdc42-interacting protein–4 (CIP4), which constitutively interacts with tubulin and microtubules but focuses to the microtubule organizing center (MTOC) after NK cell activation, when it is able to associate with Wiskott-Aldrich syndrome protein (WASp) and the actin filament–rich IS. WASp deficiency, overexpression of CIP4, or parts of CIP4 interfere with this union and block normal CIP4 localization, MTOC polarization to the IS, and cytotoxicity. Reduction of endogenous CIP4 expression using small interfering RNA similarly inhibits MTOC polarization and cytotoxic activity but does not impair actin filament accumulation at the IS, or Cdc42 activation. Thus, CIP4 is an important cytoskeletal adaptor that functions after filamentous actin accumulation and Cdc42 activation to enable MTOC polarization and NK cell cytotoxicity.

Mechanisms of IL-21 Enhancement of Rituximab Efficacy in a Lymphoma Xenograft Model.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1404-1404
Author(s):  
Steve D. Hughes ◽  
Ken Bannink ◽  
Cecile Krejsa ◽  
Mark Heipel ◽  
Becky Johnson ◽  
...  
Keyword(s):  
T Cells ◽  
Nk Cells ◽  
Nk Cell ◽  
Antibody Therapy ◽  
Xenograft Model ◽  
Tumor Model ◽  
Cell Types ◽  
Current Evidence

Abstract Interleukin 21 (IL-21) is an IL-2 family cytokine produced by activated CD4+ T cells. Potent effects of IL-21 have been observed on the growth, survival, and functional activation of T cells, B cells, and natural killer (NK) cells. A Phase I clinical trial of IL-21 in metastatic melanoma and renal cell carcinoma is currently in progress. We recently reported that IL-21 significantly enhanced rituximab mediated clearance of CD20+ lymphoma cell lines both in vitro and in vivo, and that these effects were potentially mediated through IL-21 enhancement of NK cell capacity to effect antibody dependent cellular cytotoxicity (ADCC). Specifically, NK cells treated with IL-21 showed increased cytotoxicity, granzyme B and IFNg production. Current studies aim to further evaluate the mechanisms by which IL-21 enhances ADCC. A number of observations suggest a multi-factorial basis for IL-21 synergy with rituximab. In a xenograft tumor model, SCID mice were injected IV with HS Sultan cells on day 0. Treatment with recombinant murine IL-21 (mIL-21; starting day 1) combined with rituximab (starting day 3) resulted in significantly increased survival (70% vs. 20% on day 100), compared to rituximab alone. In separate studies, the spleens of mice treated with mIL-21 showed increased numbers of activated macrophages and granulocytes. As macrophages and granulocytes can participate in ADCC, IL-21 synergy with rituximab in vivo may be partly dependent on its activation of these cell types. We have also evaluated whether direct effects of IL-21 on lymphoma cells contribute to enhancement of rituximab efficacy. The xenogeneic B lymphoma models in which IL-21 plus rituximab exhibited enhanced survival are highly aggressive and these models were not shown to respond to treatment with mIL-21 alone. In vitro studies were performed to determine if IL-21 could potentiate the growth inhibitory and pro-apoptotic effects of rituximab. In the absence of effector cells synergistic interaction was not observed. In addition, we tested the ability of IL-21 to enhance cytotoxicity when combined with antibodies targeting non-hematopoietic tumor cells (e.g. trastuzumab). Human NK cells treated with IL-21 displayed significantly increased cytotoxicity in ADCC assays using trastuzumab to target breast cancer cells expressing varying levels of HER-2 antigen. In summary, the current evidence suggests that IL-21 can enhance antibody-mediated tumor cell lysis through activation of multiple effectors of ADCC. Thus IL-21 may prove to be broadly applicable to monoclonal antibody therapy of cancer.

CD137L Reverse the Immunological Synapse Defects of Natural Killer Cells in Acute Myeloid Leukemia

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 246-246
Author(s):  
Dongxia Xing ◽  
Alan G. Ramsay ◽  
William Decker ◽  
Dean A. Lee ◽  
Simon Robinson ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Nk Cells ◽  
Natural Killer ◽  
Myeloid Leukemia ◽  
Synapse Formation ◽  
Immunological Synapse ◽  
Leukemic Cells ◽  
Cytolytic Function ◽  
Immunological Synapses ◽  
Acute Myeloid

Abstract Abstract 246 Natural killer (NK) cells are an innate component of immune system that can produce a graft vs. leukemia (GVL) effect after stem cell transplantation. NK cells derived from acute myeloid leukemia (AML) patients are defective in their cytolytic function against leukemic cells. In order to better understand the mechanism of this defect, we performed functional assays examining immunological synapse formation of AML patient NK cells with autologous and allogeneic primary AML cells acting as antigen-presenting cells (APCs). Confocal microscopy was used to image and score F-actin polymerization at the immunological synapse between patient NK cells and leukemic cells. Accumulation of F-actin beneath the area of the NK: APC contact site is a hallmark of NK lytic synapses and allows signaling molecules to regulate appropriate activation and effector function. AML patient derived NK cells (AML-NK cells) formed significantly fewer synapses with autologous leukemia cells than healthy donor NK cells (12% versus 30%, n = 16. p > 0.001). Moreover, AML-NK cells were defective in their ability to recruit the key receptor NKG2D and the signaling molecule phosphotyrosine to immunological synapse contact sites. Signaling through the costimulatory ligand4-1BB-L (CD137L) has been shown to activate T cells, enhance antitumor responses and has multiple immunomodulatory effects on dendritic cells and NK cells. We postulated that AML-NK cells could be activated for enhanced cytolytic activity using artificial APCs generated to express CD137L. To test this, we setup co-culture assays using AML-NK cells and artificial CD137L-APCs before subsequent examination of immunological synapse function with AML blasts. Stimulated AML-NK cells that formed cell conjugate interactions with AML blasts, showed a significant increase in formation of immunological synapses compared to unstimulated AML-NK cells. The number of AML-NK/AML blast immunological synapses increased 16 hours after stimulation and peaked at approximately 72 hours. CD137L stimulation of AML-NK cells was also associated with increased cytotoxic function against primary AML cells (n = 6, p <0.01). Furthermore, CD137L stimulation increased recruitment of tyrosine-phosphorylated proteins at AML-NK immunological synapses compared with unstimulated control experiments (RRI 4.1 versus 2.3, n = 3, p < 0.01). Taken together, our data suggests that immune functional suppression of AML-NK cells in leukemia patients can be reversed by CD137L activation signaling, resulting in enhanced F-actin synapse formation, phosphotyrosine signaling, and cytolytic function. Thus, enhanced recruitment of signaling molecules to the NKIS may represent a novel immunomodulatory function of CD137L in the NK cell–mediated killing of AML cells. These findings should aid development of new immune based therapies for leukemia. Disclosures: Gribben: Roche: Honoraria; Celgene: Honoraria; GSK: Honoraria; Mundipharma: Honoraria; Gilead: Honoraria; Pharmacyclics: Honoraria.

scholarly journals Strong adhesion by regulatory T cells induces dendritic cell cytoskeletal polarization and contact-dependent lethargy

2017 ◽  
Vol 214 (2) ◽  
pp. 327-338 ◽  
Author(s):  
Jiahuan Chen ◽  
Anutosh Ganguly ◽  
Ashley D. Mucsi ◽  
Junchen Meng ◽  
Jiacong Yan ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
T Cell ◽  
Synapse Formation ◽  
Immunological Synapse ◽  
Super Resolution ◽  
Dependent Manner ◽  
Structured Illumination ◽  
Structured Illumination Microscopy ◽  
Cytoskeletal Component ◽  
Strong Adhesion

Dendritic cells are targeted by regulatory T (T reg) cells, in a manner that operates as an indirect mode of T cell suppression. In this study, using a combination of single-cell force spectroscopy and structured illumination microscopy, we analyze individual T reg cell–DC interaction events and show that T reg cells exhibit strong intrinsic adhesiveness to DCs. This increased DC adhesion reduces the ability of contacted DCs to engage other antigen-specific cells. We show that this unusually strong LFA-1–dependent adhesiveness of T reg cells is caused in part by their low calpain activities, which normally release integrin–cytoskeleton linkage, and thereby reduce adhesion. Super resolution imaging reveals that such T reg cell adhesion causes sequestration of Fascin-1, an actin-bundling protein essential for immunological synapse formation, and skews Fascin-1–dependent actin polarization in DCs toward the T reg cell adhesion zone. Although it is reversible upon T reg cell disengagement, this sequestration of essential cytoskeletal components causes a lethargic state of DCs, leading to reduced T cell priming. Our results reveal a dynamic cytoskeletal component underlying T reg cell–mediated DC suppression in a contact-dependent manner.

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