Toll-like receptor 3 agonist enhances IFN-γ and TNF-α production by murine uterine NK cells

2007 ◽  
Vol 7 (5) ◽  
pp. 588-596 ◽  
Author(s):  
Jianhong Zhang ◽  
Rui Sun ◽  
Haiming Wei ◽  
Dongmei Wu ◽  
Zhigang Tian
Keyword(s):  
Nk Cells ◽  
Toll Like Receptor ◽  
Tnf Α ◽  
Ifn Γ ◽  
Uterine Nk Cells

scholarly journals The Effectiveness of Rapamycin Combined with Eltrombopag in Murine Models of Immune-Mediated Bone Marrow Failure

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 10-11
Author(s):  
Rong Fu ◽  
Shaoxue Ding ◽  
Xiaowei Liang ◽  
Tian Zhang ◽  
Zonghong Shao
Keyword(s):  
Bone Marrow ◽  
Nk Cells ◽  
Standard Dose ◽  
Bone Marrow Failure ◽  
Statistical Significance ◽  
Murine Models ◽  
Immune Mediated ◽  
Tnf Α ◽  
Significant Difference ◽  
Ifn Γ

Recent research has found that Rapamycin (Rapa) was an effective therapy in mouse models of immune-mediated bone marrow failure. However, it has not achieved satisfactory effect in clinical application. At present, many studies have confirmed that Eltrombopag (ELT) combined with IST can improve the curative effect of AA patients. Then whether Rapa combined with Elt in the treatment of AA will be better than single drug application. In this study, we tested efficacy of Rapa combined with Elt as a new treatment in mouse models of immune-mediated bone marrow failure. Compared with AA group, the whole blood cell count of Rapa+Elt group increased significantly (Figure 1A) (P<0.05). Survival of mice of Rapa+Elt group was significantly higher than that in the Rapa group (p <0.01)(Figure 1B).There was no obvious difference in the numbers of NK cells and their subsets were noted in Rapa group,CsA group and Rapa+Elt group.The expression of NKG2D on peripheral functional NK cells was up-regulated in CsA group, Rapa group and Rapa+Elt group compared with AA group (P<0.05). But there was no significant difference between effect of Rapa and CsA on the function of NK cells (Figure 1C).When Rapa combined with Elt, the expression of CD80 and CD86 are down-regulated more compared to Rapa group, but there is no statistical significance. Although these results suggested that Rapa+Elt had no statistical significance effect on numbers of mDC and expression of its functional molecule CD80 and CD86, the combined therapy still indicated that there is a potential synergy with immunosuppressant on AA mice to improve its outcome (Figure 1D).The results showed that CD4+/CD8+ ratio in CsA group, Rapa group, Rapa + Elt group had an obvious elevation than AA group (all P<0.05). But there were no significant difference among the three groups on the CD4+/CD8+ ratio (Figure 1E,1F). As for INF-gamma, Rapa can reduce the secretion of IFN-γ from CD8+T cells with efficacy similar to that of the standard dose of CsA, and had a better outcome when combined with Elt in bone marrow failure mice (Figure 1E,1G).CsA group, Elt group, Rapa group, Rapa + Elt group showed notable increased ratio of Tregs compared with AA group, among which there were only Rapa group, Rapa + Elt group showed statistical significance(P<0.05). for IL-10/Tregs ratio, Rapa group and Rapa +Elt group were superior to than CsA group(P<0.05) (Figure 1H,1I).Rapa+Elt group and Rapa showed more lower level of IFN-γ compared with CsA group, and there was significant difference in Rapa+Elt group(P<0.05). As for IL-10, IL-12p70, IL-2, IL-6, KC/GRO and TNF-α, the Rapa+Elt group showed more significant effect than Rapa or Elt alone(Figure1J). Thus, Rapa+Elt significantly down-regulated cytokines related to Th1 immune responses, such as IFN-γ, and upregulated cytokines related to Th2 immune responses, such as IL-10. To some extent, Rapa combined with Elt has a synergistic effect with CsA and Rapa alone in AA treatment. Conclusions In this study, Although Rapa combined with Elt had no significant improvement effect on the number and function of NK cells and their subsets, mDCs, and CD4+/CD8+ ratio in AA mice compared with Rapa alone, the Rapa+Elt can increase the secretion of IL-10 of Tregs and the number of Tregs, but has no significant effect on the number of Treg cells compared to with Rapa alone. Compared with AA group, the level of plasma IFN-γ, IL-2 and TNF-α decreased significantly (P<0.05), but IL-10, IL-4, IL-5 and IL-1β increased significantly in Rapa group(P<0.05). As for IL-10, IL-12p70, IL-2, IL-6, KC/GRO and TNF-α, the Rapa+Elt group showed more significant effect than Rapa alone. intervention treatment with Rapa in combination Elt in the AA mouse model more obviously ameliorated pancytopenia, improved bone marrow cellularity, and extended animal survival in a manner comparable to the standard dose of CsA and Rapa alone. Combination therapy support potential clinical utility in aplastic anemia treatment, which may further improve the efficacy of AA patients. Keywords: Rapamycin, Eltrombopag, murine models, bone marrow failure Figure 1 Disclosures No relevant conflicts of interest to declare.

scholarly journals Continuing Effect of Cytokines and Toll-Like Receptor Agonists on Indoleamine-2,3-Dioxygenase-1 in Human Periodontal Ligament Stem/Stromal Cells

Cells ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 2696
Author(s):  
Christian Behm ◽  
Alice Blufstein ◽  
Johannes Gahn ◽  
Barbara Kubin ◽  
Andreas Moritz ◽  
...  
Keyword(s):  
Protein Expression ◽  
Enzymatic Activity ◽  
Stromal Cells ◽  
Periodontal Ligament ◽  
Dependent Manner ◽  
Toll Like Receptor ◽  
Indoleamine 2,3 Dioxygenase ◽  
Tnf Α ◽  
Inflammatory Stimuli ◽  
Ifn Γ

Transplanted mesenchymal stem/stromal cells (MSCs) are a promising and innovative approach in regenerative medicine. Their regenerative potential is partly based upon their immunomodulatory activities. One of the most investigated immunomediators in MSCs, such as in periodontal ligament-derived MSCs (hPDLSCs), is indoleamine-2,3-dioxygenase-1 (IDO-1) which is upregulated by inflammatory stimuli, like cytokines. However, there are no data concerning continuing IDO-1 expression in hPDLSCs after the removal of inflammatory stimuli, such as cytokines and toll-like receptor (TLR) agonist-2 and TLR-3. Hence, primary hPDLSCs were stimulated with interleukin (IL)-1β, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, TLR-2 agonist Pam3CSK4 or TLR-3 agonist Poly I/C. IDO-1 gene and protein expression and its enzymatic activity were measured up to five days after removing any stimuli. IL-1β- and TNF-α-induced IDO-1 expression and enzymatic activity decreased in a time-dependent manner after cessation of stimulation. IFN-γ caused a long-lasting effect on IDO-1 up to five days after removing IFN-γ. Both, TLR-2 and TLR-3 agonists induced a significant increase in IDO-1 gene expression, but only TLR-3 agonist induced significantly higher IDO-1 protein expression and enzymatic activity in conditioned media (CM). IDO-1 activity of Poly I/C- and Pam3CSK4-treated hPDLSCs was higher at one day after removal of stimuli than immediately after stimulation and declined to basal levels after five days. Among all tested stimuli, only IFN-γ was able to induce long-lasting IDO-1 expression and activity in hPDLSCs. The high plasticity of IDO-1 expression and its enzymatic activity in hPDLSCs due to the variable cytokine and virulence factor milieu and the temporal-dependent responsiveness of hPDLSCs may cause a highly dynamic potential of hPDLSCs to modulate immune responses in periodontal tissues.

scholarly journals Effect of interleukins (IL-2, IL-15, IL-18) on receptors activation and cytotoxic activity of natural killer cells in breast cancer cell

2020 ◽  
Vol 20 (2) ◽  
pp. 822-832 ◽  
Author(s):  
Wahyu Widowati ◽  
Diana K Jasaputra ◽  
Sutiman B Sumitro ◽  
Mochammad A Widodo ◽  
Tjandrawati Mozef ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cytotoxic Activity ◽  
Nk Cells ◽  
Natural Killer ◽  
Nk Cell ◽  
Cell Receptor ◽  
Mcf7 Cells ◽  
Activating Receptors ◽  
Tnf Α ◽  
Ifn Γ

Introduction: Breast cancer is one of the leading cause of cancer deaths in women. Metastasis in BC is caused by immuno- surveillance deficiency, such NK cell maturation, low NK activity and decreasing cytotoxicity. This study was performed to improve activating receptors and cytotoxicity of NK cells using interleukins (ILs). Methods: Human recombinant IL-2, -15, and -18 were used to induce NK cells. We measured the activating and inhibiting receptors, proliferation activity of NK cells, and the cytotoxicity of NK cells on BC cells (MCF7). The effects of ILs were tested on the NK cell receptors CD314, CD158a and CD107a with flowcytometry, proliferation at various incubation times with 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxy methoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay and concen- trations of TNF-α and IFN-γ by NK cells with ELISA. Results: ILs increased NK cell receptor levels (CD314, CD158a, and CD107a) at 24 hours of incubation. ILs increased NK cell viability, which increased with longer incubation. Moreover, ILs-induced NK cells inhibited proliferation in MCF7 cells, as well as increased TNF-α, IFN-γ, PRF1 and GzmB secretion. Conclusion: IL-2, IL-15, and IL-18 improved activating receptors and proliferation of NK cells. IL-induced NK cells in- creased TNF-α, IFN-γ, PRF1 and GzmB secretion and cytotoxic activity on BC cells. High NK cell numbers increased BC cell growth inhibition. Keywords: Activator; breast cancer; interleukins; natural killer; receptor.

A novel role for reciprocal CD30-CD30L signaling in the cross-talk between natural killer and dendritic cells

2012 ◽  
Vol 393 (1-2) ◽  
pp. 101-106 ◽  
Author(s):  
Vijaya Lakshmi Simhadri ◽  
Hinrich P. Hansen ◽  
Venkateswara R. Simhadri ◽  
Katrin S. Reiners ◽  
Martina Bessler ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
Immune Responses ◽  
Nk Cells ◽  
Natural Killer ◽  
Cross Talk ◽  
Mitogen Activated Protein Kinase ◽  
Tnf Α ◽  
Mitogen Activated Protein ◽  
Ifn Γ ◽  
The Cross

Abstract The interplay between dendritic cells (DCs) and natural killer (NK) cells directs adaptive immune responses. The molecular basis of the cross-talk is largely undefined. Here, we provide evidence for a contribution of CD30 (TNFRSF8) and its ligand CD30L (TNFSF8) expressed on NK cells and DCs, respectively. We demonstrate that CD30-mediated engagement of CD30L induced cytokine secretion from immature DCs via the mitogen-activated protein kinase pathway. Moreover, CD30L engagement promoted differentiation to mature DCs. On the contrary, the engagement of CD30 on NK cells resulted in an NF-κB-dependent release of TNF-α/IFN-γ. These data uncover a novel and unexpected role for CD30/CD30L that contributes to proinflammatory immune responses.

Early Disease Relapse after Tyrosine Kinase Inhibitor Treatment Discontinuation in CML Is Related Both to Low Number and Impaired Function of NK-Cells

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 812-812 ◽  
Author(s):  
Mette Matilda Ilander ◽  
Ulla Olsson-Strömberg ◽  
Hanna Lähteenmäki ◽  
Kasanen Tiina ◽  
Perttu Koskenvesa ◽  
...  
Keyword(s):  
T Cells ◽  
Nk Cells ◽  
Research Funding ◽  
Nk Cell ◽  
Treatment Discontinuation ◽  
Disease Relapse ◽  
Cell Counts ◽  
Tnf Α ◽  
Ifn Γ

Abstract Background: Recent reports suggest that approximately 40% of CML patients who have achieved sustained complete molecular remission are able to stop TKI treatment without disease relapse. However, there are no predictive markers for successful therapy discontinuation. Therefore, we set up an immunological sub-study in the ongoing pan-European EURO-SKI stopping study. Our aim was to identify predictive biomarkers for relapse/non-relapse and to understand more on the mechanisms of immune surveillance in CML. Methods: The EURO-SKI study started in 2012, and patients included were at least three years on TKI and at least one year in MR4 or deeper before the study entry. Basic lymphocyte immunophenotyping (the number of NK-, T- and B-cells) was performed at the time of therapy discontinuation and 1, 6, and 12 months after the TKI stop and in case of relapse (defined as loss of MMR, BCR-ABL1>0.1% IS). In addition, from a proportion of patients more detailed immunophenotypic and functional analyses (cytotoxicity of NK-cells and secretion of Th1 type of cytokines IFN-γ/TNF-α) were done at the same times. Results: Thus far 119 Nordic patients (imatinib n=105, dasatinib n=12, nilotinib n=2) who have discontinued TKI treatment within the EURO-SKI study have been included in the lymphocyte subclass analysis (results are presented from patients who have reached 6 months follow-up). Immunophenotyping analysis demonstrates that imatinib treated patients who were able to maintain remission for 6 months (n=36) had increased NK-cell counts (0.26 vs. 0.15x109cells/L, p=0.01, NK-cell proportion 18.9% vs. 11%, p=0.005) at the time of drug discontinuation compared to patients who relapsed early (before 5 months n=22). Furthermore, the phenotype of NK-cells was more cytotoxic (more CD57+ and CD16+cells and less CD62L+cells), and also their IFN-γ/TNF-α secretion was enhanced (19.2% vs. 13%, p=0.02). Surprisingly, patients who relapsed more slowly (after 5 months, n=16) had similar baseline NK-cell counts (0.37x109cells/L), NK-cell proportion (21.2%), and phenotype and function as patients, who were able to stay in remission. No differences in the NK-cell counts were observed between patients who had detectable or undetectable BCR-ABL1 transcripts at the baseline (0.22 x109cells/L vs. 0.31 x109cells/L, p=0.61). Interestingly, NK-cell count was higher in patients with low Sokal risk score than in patients with intermediate risk (0.33 x109cells/L vs. 0.20 x109cells/L, p=0.04). Furthermore, there was a trend that male patients had a higher proportion of NK-cells than females (21.6% vs. 15.7%, p=0.06). Pretreatment with IFN-α or the duration of imatinib treatment did not have an effect on NK-cell count or proportion. In comparison to the imatinib group, dasatinib treated patients had higher NK-cell counts at the baseline (median 0.52x109cells/L vs. 0.26x109cells/L, p=0.02), and also the proportion of CD27 (median 50% vs. 16%, p=0.01) and CD57 expressing (median 79% vs. 74%, p=0.05) NK-cells was higher. The follow-up time of dasatinib treated patients is not yet long enough to correlate the NK-cell counts with the success of the treatment discontinuation. The absolute number of T-cells or their function did not differ significantly between relapsing and non-relapsing patients at the time of treatment discontinuation. However, both CD4+ and CD8+ T-cells tended to be more mature in patients who stayed in remission compared to patients who relapsed early (CD4+CD57+CD62L- median 5.7% vs. 2.4%, p=0.06, CD8+CD62L+CD45RA+ 13% vs. 26.7%, p=0.05). The analysis of follow-up samples showed that in patients who stayed in remission the Th1 type cytokine (IFN-γ/TNF-α) secretion of CD8+T-cells increased at 6 months compared to baseline (23.6 vs. 18.5%, p=0.07). Same phenomenon was observed in the late relapsing group at relapse compared to baseline (37.9 vs. 13.5%, p=0.03). No similar increase was observed in the early relapsing group. Conclusions: Low NK-cell numbers and poor cytokine secretion may predict early disease relapse after TKI discontinuation. However, patients who relapse later have high numbers of normally functioning NK-cells. Further research (detailed phenotypic analysis of NK- and T-cells including activating and inhibitory receptors and immune checkpoint molecules) and correlation of biomarker data with clinical parameters are ongoing to understand the ultimate determining factors of relapse. Disclosures Själander: Novartis: Honoraria. Hjorth-Hansen:Novartis: Honoraria; Bristol-myers Squibb: Honoraria; Ariad: Honoraria; Pfizer: Honoraria. Porkka:BMS: Honoraria; BMS: Research Funding; Novartis: Honoraria; Novartis: Research Funding; Pfizer: Research Funding. Mustjoki:Bristol-Myers Squibb: Honoraria, Research Funding; Novartis: Honoraria, Research Funding.

scholarly journals Toll-Like Receptor 9 Is Required for Full Host Resistance toMycobacteriumaviumInfection but Plays No Role in Induction of Th1 Responses

2011 ◽  
Vol 79 (4) ◽  
pp. 1638-1646 ◽  
Author(s):  
Natália B. Carvalho ◽  
Fernanda S. Oliveira ◽  
Fernanda V. Durães ◽  
Leonardo A. de Almeida ◽  
Manuela Flórido ◽  
...  
Keyword(s):  
Interleukin 12 ◽  
Toll Like Receptor ◽  
Necrosis Factor Alpha ◽  
Histocompatibility Complex ◽  
Tnf Α ◽  
Factor Alpha ◽  
Ifn Γ ◽  
Myd88 Signaling ◽  
Necrosis Factor

ABSTRACTTo investigate the role of Toll-like receptor 9 (TLR9) in innate immunity toMycobacteriumavium, TLR9, TLR2, and MyD88 knockout (KO) mice were infected with this bacterium. Bacterial burdens were higher in the spleens, livers, and lungs of infected TLR9 KO mice than in those of C57BL/6 mice, indicating that TLR9 is required for efficient control ofM.aviuminfection. However, TLR9 KO or TLR2 KO spleen cells displayed normalM.avium-induced tumor necrosis factor alpha (TNF-α) and gamma interferon (IFN-γ) responses. This finding was confirmed by determining the number of splenic CD4+T cells producing IFN-γ by flow cytometry. Furthermore, TLR2 and MyD88, but not TLR9, played a major role in interleukin-12 and TNF-α production byM.avium-infected macrophages and dendritic cells (DCs). We also found that major histocompatibility complex class II molecule expression on DCs is regulated by TLR2 and MyD88 signaling but not by TLR9. Finally, lack of TLR9, TLR2, or MyD88 reduced the numbers of macrophages, epithelioid cells, and lymphocytes inM.avium-induced granulomas but only MyD88 deficiency affected the number of liver granulomas. In summary, our data demonstrated that the involvement of TLR9 in the control ofM.aviuminfection is not related to the induction of Th1 responses.

scholarly journals Combined Stimulation with Interleukin-18 and Interleukin-12 Potently Induces Interleukin-8 Production by Natural Killer Cells

2017 ◽  
Vol 9 (5) ◽  
pp. 511-525 ◽  
Author(s):  
Sophie M. Poznanski ◽  
Amanda J. Lee ◽  
Tina Nham ◽  
Evan Lusty ◽  
Margaret J. Larché ◽  
...  
Keyword(s):  
Immune Response ◽  
Nk Cells ◽  
Natural Killer ◽  
Peripheral Blood ◽  
Mononuclear Cells ◽  
Nk Cell ◽  
Critical Role ◽  
Interleukin 12 ◽  
Tnf Α ◽  
Ifn Γ

The combination of interleukin (IL)-18 and IL-12 (IL-18+IL-12) potently stimulates natural killer (NK) cells, triggering an innate immune response to infections and cancers. Strategies exploiting the effects of IL-18+IL-12 have shown promise for cancer immunotherapy. However, studies have primarily characterized the NK cell response to IL-18+IL-12 in terms of interferon (IFN)-γ production, with little focus on other cytokines produced. IL-8 plays a critical role in activating and recruiting immune cells, but it also has tumor-promoting functions. IL-8 is classically produced by regulatory NK cells; however, cytotoxic NK cells do not typically produce IL-8. In this study, we uncover that stimulation with IL-18+IL-12 induces high levels of IL-8 production by ex vivo expanded and freshly isolated NK cells and NK cells in peripheral blood mononuclear cells. We further report that tumor necrosis factor (TNF)-α, produced by NK cells following IL-18+IL-12 stimulation, regulates IL-8 production. The IL-8 produced is in turn required for maximal IFN-γ and TNF-α production. These findings may have important implications for the immune response to infections and cancer immunotherapies. This study broadens our understanding of NK cell function and IL-18+IL-12 synergy by uncovering an unprecedented ability of IL-18+IL-12-activated peripheral blood NK cells to produce elevated levels of IL-8 and identifying the requirement for intermediates induced by IL-18+IL-12 for maximal cytokine production following stimulation.

scholarly journals Regulation of human NK-cell cytokine and chemokine production by target cell recognition

Blood ◽  
2010 ◽  
Vol 115 (11) ◽  
pp. 2167-2176 ◽  
Author(s):  
Cyril Fauriat ◽  
Eric O. Long ◽  
Hans-Gustaf Ljunggren ◽  
Yenan T. Bryceson
Keyword(s):  
Nk Cells ◽  
Target Cell ◽  
Cell Activation ◽  
Nk Cell ◽  
Cell Recognition ◽  
Chemokine Production ◽  
Relative Contribution ◽  
Cytokines And Chemokines ◽  
Tnf Α ◽  
Ifn Γ

AbstractNatural killer (NK)–cell recognition of infected or neoplastic cells can induce cytotoxicity and cytokine secretion. So far, it has been difficult to assess the relative contribution of multiple NK-cell activation receptors to cytokine and chemokine production upon target cell recognition. Using Drosophila cells expressing ligands for the NK-cell receptors LFA-1, NKG2D, DNAM-1, 2B4, and CD16, we studied the minimal requirements for secretion by freshly isolated, human NK cells. Target cell stimulation induced secretion of predominately proinflammatory cytokines and chemokines. Release of chemokines MIP-1α, MIP-1β, and RANTES was induced within 1 hour of stimulation, whereas release of TNF-α and IFN-γ occurred later. Engagement of CD16, 2B4, or NKG2D sufficed for chemokine release, whereas induction of TNF-α and IFN-γ required engagement of additional receptors. Remarkably, our results revealed that, upon target cell recognition, CD56dim NK cells were more prominent cytokine and chemokine producers than CD56bright NK cells. The present data demonstrate how specific target cell ligands dictate qualitative and temporal aspects of NK-cell cytokine and chemokine responses. Conceptually, the results point to CD56dim NK cells as an important source of cytokines and chemokines upon recognition of aberrant cells, producing graded responses depending on the multiplicity of activating receptors engaged.

scholarly journals TIGIT Expression Positively Associates with NK Cell Function in AML Patients

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 5250-5250 ◽  
Author(s):  
Bei Jia ◽  
Chenchen Zhao ◽  
David F. Claxton ◽  
W. Christopher Ehmann ◽  
Witold B. Rybka ◽  
...  
Keyword(s):  
Nk Cells ◽  
Therapeutic Strategy ◽  
Cell Function ◽  
Nk Cell ◽  
Granzyme B ◽  
Healthy Controls ◽  
Functional Studies ◽  
Activating Receptors ◽  
Tnf Α ◽  
Ifn Γ

Abstract Natural killer (NK) cells are essential innate immune effectors with promising anti-leukemia activity in acute myeloid leukemia (AML). However, clinical success of applying NK cells in AML treatment has not been achieved. A better understanding of the regulatory mechanisms for NK cell function is important to optimize this therapeutic strategy. T cell immunoglobulin and ITIM domain (TIGIT) is a recently identified inhibitory receptor expressed on T cells and NK cells. Multiple studies including ours have demonstrated its suppressive effect in anti-tumor CD8 T cell response. However whether and how TIGIT impacts NK cells in AML is unknown. Here we performed phenotypic and functional studies on NK cells derived from patients with newly diagnosed AML (n=30). Cells collected from healthy individuals (n=18) were used as controls. TIGIT expression and their contributions to NK cell function in AML were assessed. Peripheral blood samples were first examined by flow cytometry for the frequency of NK cells (defined as CD56+CD3-). The percentage of NK cells among peripheral blood mononuclear cells (PBMCs) in AML patients is comparable with that of healthy controls. In contrast, when we performed functional analysis to assess NK cells for cytokine release upon in vitro stimulation with a human leukemia cell line K562, we observed significantly lower intracellular production of IFN-γ in cells from AML patients compared with that of healthy controls. Consistently NK cells from AML patients expressed less Perforin, indicating a compromised killing capacity. We next evaluated the expression of TIGIT on CD56+CD3- NK cells. As some AML blasts and monocytes also express CD56, we performed multichannel flow cytometry and carefully gated out other cell components when assessing TIGIT expression. To our surprise, we observed a significantly lower frequency of TIGIT-expressing NK cells in AML compared with that of healthy controls (36.82 ±4.543% vs. 48.9±3.818%, P=0.0463). This data indicated that low-TIGIT expression associates with impaired NK cell function and AML progression. We further examined the phenotype and functional status of TIGIT+ NK cells. Expression of activating receptors (CD16 and CD160) and inhibiting receptors (KIR and NKG2A) on TIGIT+ vs. TIGIT- NK cells were analyzed. We observed a significant higher expression of CD16 (51.27±9.009% vs. 20.63±5.334%, P=0.0001) and CD160 (39.84±6.447% vs. 21.24±4.287%, P=0.0103) on TIGIT+ NK cells compared with that of TIGIT- NK cells. By contrast, TIGIT+ NK cells expressed lower KIR (24.06±3.796% vs. 43.59±6.96%, P=0.0046) and NKG2A (7.658±1.717% vs. 18.68±4.256%, P=0.0167) than TIGIT- NK cells. Importantly, functional studies demonstrated an elevated expression of Granzyme B and increased cytokine (IFN-γ and TNF-α) production by TIGIT+ NK cells compared with TIGIT- NK cells (IFN-γ, P=0.0283; TNF-α P=0.0347; Granzyme B, P=0.0493). These data suggest that TIGIT expression on NK cells associated with activated and high functional status. Collectively, our study demonstrates that 1) in line with lower capacity to produce IFN-γ, NK cells from AML patients express less frequency of TIGIT compared with healthy individuals; 2) TIGIT+ NK cells from AML patients express high levels of activating receptors and are highly functional manifested by more cytokine production and enhanced expression of Granzyme B compared with TIGIT- NK cells. These results indicate that in AML patient, TIGIT may contribute to the upregulation of NK cell function. This is in contrast to the observations of CD8 T cells in which TIGIT plays a suppressive role. Targeting TIGIT for cancer treatment is currently under active development. Our findings bring a call for caution on the TIGIT-targeted therapeutic strategy in AML as TIGIT might be a double-edged sword in anti-leukemia immune regulation. Disclosures No relevant conflicts of interest to declare.

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