Natural Killer Cell Expression Research Articles

Circulating Immune Cell Profile and Changes in Intravenous Immunoglobulin Responsiveness Over the Disease Course in Children With Kawasaki Disease.

Kawasaki disease (KD) is an acute, self-limited febrile illness of young children. The etiology of KD remains to be poorly understood. There has been limited research on longitudinal examination of peripheral blood leukocytes for immune profiling particularly in relation to treatment response with intravenous immunoglobulin (IVIG). This study profiles immune cells at the time of diagnosis and over the disease course. In addition, we identified the characteristics of the immune cells in IVIG-responsive patients with KD. We enrolled patients diagnosed with KD between May 1, 2017, and January 1, 2020. Blood was taken at least three times from all enrolled patients: at diagnosis (before IVIG infusion) and immediately and 2 weeks after IVIG infusion. We evaluated the laboratory findings and results of flow cytometry analysis of immune cells at all stages, focusing on CD4+ T lymphocytes, CD8+ T lymphocytes, CD19+ B lymphocytes, granulocytes, classical monocytes, and natural killer (NK) cells. Non-febrile healthy controls (NFCs) and other febrile controls (OFCs) were also enrolled. A total of 68 patients were enrolled and divided into two groups according to IVIG resistance status: IVIG-responsive (n = 55) and IVIG-resistant (n = 13). The total fever duration was significantly longer in the IVIG-resistant group (9.7 ± 5.3 days) than in the IVIG-responsive group (6.7 ± 3.0 days; P = 0.02). There was a significant difference in intermediate CD14+CD16+ monocytes between KD patients and both NFC and OFCs; they were significantly higher and lower in KD patients than NFC and OFCs, respectively (P < 0.001). The levels of all three subtypes of NK cells were significantly lower in KD patients than in both NFC and OFCs (P < 0.001). Regarding IVIG responsiveness, CD14+CD16+ intermediate monocyte levels were significantly lower in the IVIG-resistant group (P < 0.001). In addition, CD56−CD16+ NK cell expression was significantly lower in the IVIG-resistant group than in the IVIG-responsive group (P = 0.002). In conclusion, our results suggest CD56−CD16+N NK cells and CD14+CD16+ intermediate monocytes might play an essential role in immunopathogenesis of KD. Further studies are warranted to explore the role of these subpopulations particularly for the observed association with coronary artery lesions (CAL) and treatment response.

The Expression and Function of NK Cells in Patients with Acute Myeloid Leukemia

To explore the expression characteristics of antigens and functional markers of natural killer (NK) cells in patients with acute myeloid leukemia (AML). Multi-parameter flow cytometry was used to detect NK cell surface markers and their functional indicators in 56 newly diagnosed AML patients and 24 healthy controls, including activating receptors NKG2D, NKP46, DNAM-1, and killing indicators granzyme B, perforin. Referring to the WHO hematopoiesis and lymph tissue tumor classification criteria, 56 cases were roughly divided into three types: AML M1, M2, and M4/M5. However, there was no differences about NK cells among the three types, so it was no longer subdivided. NK cells were divided into two groups: CD3-CD56hiCD16- (CD56hiNK) and CD3-CD56dimCD16+ (CD56dimNK). Compared with CD56dimNK cell population, except for NKP46, the positive expression levels of NKG2D and other receptors of CD56hiNK cells in AML patients decreased (P<0.001). Compared with healthy controls, the proportion of CD56hiNK cells in AML patients increased, while the number and proportion of NK cells and proportion of CD56dimNK cells significantly decreased (P<0.05). The proportion of perforin in CD56hiNK cells significantly increased (P<0.05). The expression of DNAM-1 in CD56hiNK cells, NKG2D, DNAM-1, and perforin in CD56dimNK cells decreased significantly (P<0.05). There was no statistically significant difference in expression of other functional indexes in AML patients compared with corresponding indexes of healthy controls. In addition, the proportion of CD56hiNK cells was positively correlated with the expression of CD34+ in AML (r=0.303). Compared with CD56dimNK, the ratio of CD56hiNK and the expression of functional markers in AML patients are lower. Compared with healthy controls, the number and expression ratio of NK cells in AML patients decrease and the expression of functional markers is abnormal, indicating that its function is impaired.

Innate Immune Responses of Vaccinees Determine Early Neutralizing Antibody Production After ChAdOx1nCoV-19 Vaccination.

BackgroundInnate immunity, armed with pattern recognition receptors including Toll-like receptors (TLR), is critical for immune cell activation and the connection to anti-microbial adaptive immunity. However, information regarding the impact of age on the innate immunity in response to SARS-CoV2 adenovirus vector vaccines and its association with specific immune responses remains scarce.MethodsFifteen subjects between 25-35 years (the young group) and five subjects between 60-70 years (the older adult group) were enrolled before ChAdOx1 nCoV-19 (AZD1222) vaccination. We determined activation markers and cytokine production of monocyte, natural killer (NK) cells and B cells ex vivo stimulated with TLR agonist (poly (I:C) for TLR3; LPS for TLR4; imiquimod for TLR7; CpG for TLR9) before vaccination and 3-5 days after each jab with flow cytometry. Anti-SARS-CoV2 neutralization antibody titers (surrogate virus neutralization tests, sVNTs) were measured using serum collected 2 months after the first jab and one month after full vaccination.ResultsThe older adult vaccinees had weaker vaccine-induced sVNTs than young vaccinees after 1st jab (47.2±19.3% vs. 21.2±22.2%, p value<0.05), but this difference became insignificant after the 2nd jab. Imiquimod, LPS and CpG strongly induced CD86 expression in IgD+CD27- naïve and IgD-CD27+ memory B cells in the young group. In contrast, only the IgD+ CD27- naïve B cells responded to these TLR agonists in the older adult group. Imiquimode strongly induced the CD86 expression in CD14+ monocytes in the young group but not in the older adult group. After vaccination, the young group had significantly higher IFN-γ expression in CD3- CD56dim NK cells after the 1st jab, whilst the older adult group had significantly higher IFN-γ and granzyme B expression in CD56bright NK cells after the 2nd jab (all p value <0.05). The IFN-γ expression in CD56dim and CD56bright NK cells after the first vaccination and CD86 expression in CD14+ monocyte and IgD-CD27-double-negative B cells after LPS and imiquimod stimulation correlated with vaccine-induced antibody responses.ConclusionsThe innate immune responses after the first vaccination correlated with the neutralizing antibody production. Older people may have defective innate immune responses by TLR stimulation and weak or delayed innate immune activation profile after vaccination compared with young people.

Eomes and T-bet, a dynamic duo regulating NK cell differentiation.

T-bet and Eomes are two related transcription factors (TFs) that regulate the differentiation of cytotoxic lymphocytes such as Natural Killer (NK) cells and CD8 T cells. Recent genome-wide analyses suggest they have complementary roles in instructing the transcriptional program of NK cells, although their DNA binding sites appear to be very similar. In this essay, we discuss the mechanisms that could specify their action, addressing their expression profile, the cofactors they interact with, as well as their roles in the epigenetic regulation of chromatin accessibility. Based on the recent literature on these TFs, we propose different models to describe how they regulate gene expression in NK cells at steady state, or in the context of activation or exhaustion. We also discuss recent findings in the field of CD8 T cell differentiation and residency, where Eomes and T-bet appear to be major regulators, and the parallels that can be drawn between mechanisms of NK and CD8 T cell differentiation and trafficking.

Toll-like receptor 8 agonists improve NK-cell function primarily targeting CD56brightCD16− subset

BackgroundToll-like receptors (TLRs) are pattern-recognition sensors mainly expressed in innate immune cells that directly recognize conserved pathogen structures (pathogen-associated molecular patterns-PAMPs). Natural killer (NK) cells have been described to express...

Korean Red Ginseng Enhances Immunotherapeutic Effects of NK Cells via Eosinophils in Metastatic Liver Cancer Model.

Metastasis decreases the survival rate of patients with liver cancer. Therefore, novel anti-metastatic strategies are needed. Korean Red Ginseng (KRG) is often ingested as a functional food with an immune-boosting effect. We investigated a combination of KRG and natural killer (NK) cells as a novel immunotherapy approach. SK-Hep1 cells were injected into the tail vein of NRGA mice to establish an experimental metastasis model. KRG, NK cells, or a combination of KRG and NK cells were administered. Tumor growth was observed using an in vivo imaging system, and metastatic lesions were evaluated by histological analysis and immunohistochemistry. Bioluminescence intensity was lower in the KRG and NK cell combination group than in the other groups, indicating that the combination treatment suppressed the progression of metastasis. CD56 expression was used as a NK cell marker and hematological analysis was performed. The combination treatment also decreased the expression of matrix metalloproteinases and the area of metastatic lesions in liver and bone tissues, as well as increased the eosinophil count. Expression of cytokines-related eosinophils and NK cells was determined by Western blotting analysis. The expression of interleukin 33 (IL33) was induced by the combination of KRG and NK cells. High IL33 expression was associated with prolonged overall survival in the Kaplan–Meier plotter. Our results suggest that KRG enhances the immune activity of NK cells by IL-33 through eosinophils and suppresses metastatic liver cancer progression.

Microvascular Inflammation: An Incremental Path to Refining the Diagnosis of Antibody-mediated Rejection in Heart Transplantation

Microvascular Inflammation: An Incremental Path to Refining the Diagnosis of Antibody-mediated Rejection in Heart Transplantation

Effects of yoga in men with prostate cancer on quality of life and immune response: a pilot randomized controlled trial

BackgroundDiagnosis and treatment of prostate cancer is associated with anxiety, fear, and depression in up to one-third of men. Yoga improves health-related quality of life (QoL) in patients with several types of cancer, but evidence of its efficacy in enhancing QoL is lacking in prostate cancer.MethodsIn this randomized controlled study, 29 men newly diagnosed with localized prostate cancer were randomized to yoga for 6 weeks (n = 14) or standard-of-care (n = 15) before radical prostatectomy. The primary outcome was self-reported QoL, assessed by the Expanded Prostate Index Composite (EPIC), Functional Assessment of Cancer Therapy-Prostate (FACT-P), Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT–F), Functional Assessment of Cancer Therapy-General (FACT-G) at baseline, preoperatively, and 6 weeks postoperatively. Secondary outcomes were changes in immune cell status and cytokine levels with yoga.ResultsThe greatest benefit of yoga on QoL was seen in EPIC-sexual (mean difference, 8.5 points), FACIT-F (6.3 points), FACT-Functional wellbeing (8.6 points), FACT-physical wellbeing (5.5 points), and FACT-Social wellbeing (14.6 points). The yoga group showed increased numbers of circulating CD4+ and CD8+ T-cells, more production of interferon-gamma by natural killer cells, and increased Fc receptor III expression in natural killer cells. The yoga group also showed decreased numbers of regulatory T-cells, myeloid-derived suppressor cells, indicating antitumor activity, and reduction in inflammatory cytokine levels (granulocyte colony-stimulating factor [0.55 (0.05–1.05), p = 0.03], monocyte chemoattractant protein [0.22 (0.01–0.43), p = 0.04], and FMS-like tyrosine kinase-3 ligand [0.91 (−0.01, 1.82), p = 0.053].ConclusionsPerioperative yoga exercise improved QoL, promoted an immune response, and attenuated inflammation in men with prostate cancer. Yoga is feasible in this setting and has benefits that require further investigation.Trial registrationclinicaltrials.org (NCT02620033).

Targeted integration of EpCAM-specific CAR in human induced pluripotent stem cells and their differentiation into NK cells

BackgroundRedirection of natural killer (NK) cells with chimeric antigen receptors (CAR) is attractive in developing off-the-shelf CAR therapeutics for cancer treatment. However, the site-specific integration of a CAR gene into NK cells remains challenging.MethodsIn the present study, we genetically modified human induced pluripotent stem cells (iPSCs) with a zinc finger nuclease (ZFN) technology to introduce a cDNA encoding an anti-EpCAM CAR into the adeno-associated virus integration site 1, a “safe harbour” for transgene insertion into human genome, and next differentiated the modified iPSCs into CAR-expressing iNK cells.ResultsWe detected the targeted integration in 4 out of 5 selected iPSC clones, 3 of which were biallelically modified. Southern blotting analysis revealed no random integration events. iNK cells were successfully derived from the modified iPSCs with a 47-day protocol, which were morphologically similar to peripheral blood NK cells, displayed NK phenotype (CD56+CD3-), and expressed NK receptors. The CAR expression of the iPSC-derived NK cells was confirmed with RT-PCR and flow cytometry analysis. In vitro cytotoxicity assay further confirmed their lytic activity against NK cell-resistant, EpCAM-positive cancer cells, but not to EpCAM-positive normal cells, demonstrating the retained tolerability of the CAR-iNK cells towards normal cells.ConclusionLooking ahead, the modified iPSCs generated in the current study hold a great potential as a practically unlimited source to generate anti-EpCAM CAR iNK cells.

Enhancement of NK Cell Antitumor Effector Functions Using a Bispecific Single Domain Antibody Targeting CD16 and the Epidermal Growth Factor Receptor.

Simple SummaryStrategies to enhance the preferential accumulation and activation of Natural Killer (NK) cells in the tumor microenvironment can be expected to increase the efficacy of NK cell-based cancer immunotherapy. In this study, we report that a bispecific single domain antibody (VHH) that targets CD16 (FcRγIII) on NK cells and the epidermal growth factor receptor (EGFR) on tumor cells can be used to target and enhance cytolysis of cancer cells. The bispecific VHH enhanced NK cell activation and cytotoxicity in an EGFR- and CD16-dependent and KRAS-independent manner. Moreover, the bispecific VHH induced stronger activity of cancer patient-derived NK cells and resulted in tumor control in a co-culture of metastatic colorectal cancer cells and either autologous peripheral blood mononuclear cells or allogeneic CD16+ NK cells. We believe that this novel approach could represent a valid therapeutic strategy either alone or in combination with other NK cell-based therapies.The ability to kill tumor cells while maintaining an acceptable safety profile makes Natural Killer (NK) cells promising assets for cancer therapy. Strategies to enhance the preferential accumulation and activation of NK cells in the tumor microenvironment can be expected to increase the efficacy of NK cell-based therapies. In this study, we show binding of a novel bispecific single domain antibody (VHH) to both CD16 (FcRγIII) on NK cells and the epidermal growth factor receptor (EGFR) on tumor cells of epithelial origin. The bispecific VHH triggered CD16- and EGFR-dependent activation of NK cells and subsequent lysis of tumor cells, regardless of the KRAS mutational status of the tumor. Enhancement of NK cell activation by the bispecific VHH was also observed when NK cells of colorectal cancer (CRC) patients were co-cultured with EGFR expressing tumor cells. Finally, higher levels of cytotoxicity were found against patient-derived metastatic CRC cells in the presence of the bispecific VHH and autologous peripheral blood mononuclear cells or allogeneic CD16 expressing NK cells. The anticancer activity of CD16-EGFR bispecific VHHs reported here merits further exploration to assess its potential therapeutic activity either alone or in combination with adoptive NK cell-based therapeutic approaches.

PROMOTER CHOICE: THE IDEAL PROMOTER TO DRIVE CHIMERIC ANTIGEN RECEPTOR (CAR) EXPRESSION IN NK CELLS

Aims Natural Killer (NK) cells have gained much recent attention as a promising alternative platform for CAR engineering owing to their unique biological attributes, their specialized cytotoxicity against tumors, their safety profile, and their potential use as an off-the-shelf cellular therapy. However, NK transgene expression level is a major technical obstacle to the development of NK cell immunotherapy. Promoters, present in vectors, are responsible for maintaining the expression of CAR in host cells. Furthermore, promoters may differ in their ability to produce lentiviral particles and in their transduction efficiency. The present study aimed to evaluate whether different internal promoters result in a different percentage of transduced cells and transgene expression level in NK cells and thus to be able to choose an ideal promoter to drive the expression of CAR.CD19 increasing the antitumor potency of NK cells. Methods Lentiviral particles with EF1a and SFFV promoters driving GFP gene expression or CAR.CD19 were produced, and the virus titer was measured by flow cytometry. Lentiviral particles were used for transduction of NK-92, NK from peripheral blood and NK from cord blood. CAR positive cells were detected by flow cytometry using anti F(ab)2 antibody. CAR-NK cell cytotoxic potential and specificity were assessed using established human Raji and NALM-6 lymphoblastoid cell lines (CD19+) as targets, which express varying antigen levels and MDA-MB-453 (CD19-) cells were used as negative control. Results and discussion First, we explored the potential EF1a and SFFV promoters to drive GFP gene expression. SFFV promoter produced high lentiviral titers and achieved the best transduction efficacy in NK cells. The major difference between the promoters was the ability of SFFV to maintain longer and more robust GFP expression in NK cells. Therefore, we chose this promoter to drive CAR.CD19 expression and interleukin (IL)-15 co-expression in NK cells. There was a transduction efficiency of 13% (+/- 13.7) for NK-92 cells, assessed 48h after transduction. NK cells from Peripheral Blood (NK-PB) and Cord Blood (NK-CB) were also transduced with an efficiency of 27% and 49%, respectively. After 3 weeks in culture, the percentage of CAR-NK cells progressively decreased in primary cells. Cell growth of transduced cells from both sources was not statistically different; despite wild type NK-CB cells had a higher fold-change expansion than wild type NK-PB. CAR-NK-92 cells modified with SFFV were enriched with magnetic beads to 98% of NK cells positive for CAR expression and showed efficient and stable transgene expression during ex vivo expansion. The enriched CAR.CD19-NK-92 cells showed a higher killing potential against Raji CD19+ cells, compared with non-transduced NK-92 cells. Further, we evaluated the CAR-NK primary cells in vitro cytotoxic potential. CAR-NKs both from PB and CB had a higher killing potential against Raji and NALM-6 CD19+ cell lines than non-transduced NK cells. Conclusions Taken together, these results indicate that the developed vector is functional and able to transduce NK cells from different sources, enhancing their anti-tumoral activity against tumoral CD19+ cells. Our results highlight that the promoter choice is essential to generate CAR-NK cells suitable for therapeutic applications. Funding Supported by FAPESP 2019/25309-0, 2013/08135-2, 2008/578773; CNPq 573754-2008-0; Capes (88887.140966/2017-00 and 88881.199630/2018-01).

TIMP1 and TIMP2 Downregulate TGFβ Induced Decidual-like Phenotype in Natural Killer Cells.

Simple SummaryCancer patients are characterized by NK cells with altered surface markers, such as CD56 brightness, CD9, CD49a (pro-angiogenic) and PD-1, and TIM-3 (exhaustion), that favor immune escape. Transforming growth factor-beta (TGFβ) is a major tumor-derived cytokine that favors cancer growth and supports pro-angiogenic activities in NK cells by inducing pro-angiogenic molecules. TIMP-1 and TIMP-2 play a crucial role in extracellular matrix (ECM) regulation, wound healing, pregnancy and cancer, and there is increasing evidence that they are immune-modulatory. We found that recombinant TIMP-1 and -2 can partially contrast the induction of pro-tumor/pro-angiogenic decidual-like polarization of NK cells by TGFβ.Natural Killer (NK) cells have been found to be anergic, exhausted and pro-angiogenic in cancers. NK cell from healthy donors, exposed to TGFβ, acquire the CD56brightCD9+CD49a+ decidual-like-phenotype, together with decreased levels of NKG2D activation marker, increased levels of TIM-3 exhaustion marker, similar to cancer-associated NK cells. Tissue inhibitors of metalloproteases (TIMPs) exert dual roles in cancer. The role of TIMPs in modulating immune cells is a very novel concept, and the present is the first report studying their ability to contrast TGFβ action on NK cells. Here, we investigated the effects of TIMP1 and TIMP2 recombinant proteins in hindering decidual-like markers in NK cells, generated by polarizing cytolytic NK cells with TGFβ. The effects of TIMP1 or TIMP2 on NK cell surface antigens were determined by multicolor flow cytometry. We found that TIMP1 and TIMP2 were effective in interfering with TGFβ induced NK cell polarization towards a decidual-like-phenotype. TIMP1 and TIMP2 counteracted the effect of TGFβ in increasing the percentage of CD56bright, CD16−, CD9+ and CD49a+, and restoring normal levels for TIMP 1 and 2 also inhibited decrease levels of the activation marker NKG2D induced by TGFβ and decreased the TGFβ upregulated exhaustion marker TIM-3. NK cell degranulation capabilities against K562 cells were also decreased by TGFβ and not by TIMP1 or TIMP2. TIMP1 treatment could partially restore degranulation marker CD107a expression. Treatment with recombinant TIMP-1 or TIMP-2 showed a trend, although not statistically significant, to decrease CD49a+ and TIM-3+ expression and increase NKG2D in peripheral blood NK cells exposed to conditioned media from colon cancer cell lines. Our results suggest a potential role of TIMPs in controlling the tumor-associated cytokine TGFβ-induced NK cell polarization. Given the heterogeneity of released factors within the TME, it is clear that TGFβ stimulation represents a model to prove TIMP’s new properties, but it cannot be envisaged as a soloist NK cell polarizing agent. Therefore, further studies from the scientific community will help defining TIMPs immunomodulatory activities of NK cells in cancer, and their possible future diagnostic–therapeutic roles.

Early IFN-α signatures and persistent dysfunction are distinguishing features of NK cells in severe COVID-19

Longitudinal analyses of the innate immune system, including the earliest time points, are essential to understand the immunopathogenesis and clinical course of coronavirus disease (COVID-19). Here, we performed a detailed characterization of natural killer (NK) cells in 205 patients (403 samples; days 2 to 41 after symptom onset) from four independent cohorts using single-cell transcriptomics and proteomics together with functional studies. We found elevated interferon (IFN)-α plasma levels in early severe COVD-19 alongside increased NK cell expression of IFN-stimulated genes (ISGs) and genes involved in IFN-α signaling, while upregulation of tumor necrosis factor (TNF)-induced genes was observed in moderate diseases. NK cells exert anti-SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) activity but are functionally impaired in severe COVID-19. Further, NK cell dysfunction may be relevant for the development of fibrotic lung disease in severe COVID-19, as NK cells exhibited impaired anti-fibrotic activity. Our study indicates preferential IFN-α and TNF responses in severe and moderate COVID-19, respectively, and associates a prolonged IFN-α-induced NK cell response with poorer disease outcome.

The Putative Role of Natural Killer Cells in Patients with Hepatitis C Virus-Related Hepatocellular Carcinoma.

Background:Natural Killer (NK) cells have crucial roles in immune responses against malignant transformation including hepatocellular carcinoma (HCC). The NKG2D receptor has a critical role in the NK recognition of target cells. Aim:We assessed NKG2D receptor expression as a diagnostic biomarker for HCC detection and progression in Egyptian patients with hepatitis C virus (HCV)-related HCC. Methods:We classified 81 patients into three groups: chronic hepatitis (21), cirrhotic (30) and HCC (30) patients, with 36 individuals enrolled to the control group. We analyzed NK levels in peripheral blood and NKG2D receptor expression in NK cells using flow cytometry. Results: We observed a significant decrease in NKG2D (CD314) expression on circulating NK cells and frequency of NK cells expressing NKG2D (CD314) in HCC patients. Also, in patients, larger foci lesions significantly correlated with decreased NK cell numbers. Multiple foci numbers and patients with a Child score C significantly correlated with decreased circulating NK cells expressing NKG2D and decreased NKG2D expression. Conclusion:The percentage of NK cells in peripheral blood and NKG2D receptor expression could function as potential biomarkers for HCC detection and progression.

Metabotropic Glutamate Receptor 5 in Natural Killer Cells Attenuates Liver Fibrosis by Exerting Cytotoxicity to Activated Stellate Cells.

The important roles of glutamate and metabotropic glutamate receptor 5 (mGluR5) in HSCs have recently been reported in various liver diseases; however, the mechanism linking the glutamine/glutamate metabolism and mGluR5 in liver fibrosis remains unclear. Here, we report that mGluR5 activation in natural killer (NK) cells attenuates liver fibrosis through increased cytotoxicity and interferon-γ (IFN-γ) production in both mice and humans. Following 2-week injection of carbon tetrachloride (CCl4 ) or 5-week methionine-deficient and choline-deficient diet, liver fibrosis was more aggravated in mGluR5 knockout mice with significantly decreased frequency of NK cells compared with wild-type mice. Consistently, NK cell-specific mGluR5 knockout mice had aggravated CCl4 -induced liver fibrosis with decreased production of IFN-γ. Conversely, in vitro activation of mGluR5 in NK cells significantly increased the expression of anti-fibrosis-related genes including Ifng, Prf1 (perforin), and Klrk1 (killer cell lectin like receptor K1) and the production of IFN-γ through the mitogen-activated extracellular signal-regulated kinase/extracellular signal-related kinase pathway, contributing to the increased cytotoxicity against activated HSCs. However, we found that the uptake of glutamate was increased in activated HSCs, resulting in shortage of extracellular glutamate and reduced stimulation of mGluR5 in NK cells. Consequently, this could enable HSCs to evade NK cell cytotoxicity in advanced liver fibrosis. In vivo, pharmacologic activation of mGluR5 accelerated CCl4 -induced liver fibrosis regression by restoring NK cell cytotoxicity. In humans, mGluR5 activation enhanced the cytotoxicity of NK cells isolated from healthy donors, but not from patients with cirrhosis with significantly reduced mGluR5 expression in NK cells. mGluR5 plays important roles in attenuating liver fibrosis by augmenting NK cell cytotoxicity, which could be used as a potential therapeutic target for liver fibrosis.

Fidarestat induces glycolysis of NK cells through decreasing AKR1B10 expression to inhibit hepatocellular carcinoma

The aldose reductase inhibitor Fidarestat has been noted to have efficacy in treating a variety of tumors. To define its role in hepatocellular carcinoma (HCC), we induced a HCC xenograft model in mice, which were treated with different doses of Fidarestat. The amounts of natural killer (NK) cells and related inflammatory factors were detected in the serum of the mice. Fidarestat inhibited HCC tumor growth and lung metastasis in vivo and increased NK cell number as well as levels of NK cell-related inflammatory factors in mouse serum. NK cells were then co-cultured with the HCC cell line in vitro to detect effects on HCC cell progression after Fidarestat administration. The glycolysis activity of the NK cells was evaluated by extracellular acidification rate, while aldo-keto reductase family 1 member B10 (AKR1B10) expression was detected by western blot analysis. Administration of Fidarestat downregulated the expression of AKR1B10 in NK cells and promoted NK cell glycolysis to enhance their killing activity against HCC cells. However, depletion of NK cells or upregulation of AKR1B10 attenuated the anticancer activity of Fidarestat. Taken together, Fidarestat downregulated AKR1B10 expression in NK cells to promote NK cell glycolysis, thereby alleviating HCC progression.

Synovial fibroblasts regulate the cytotoxicity and osteoclastogenic activity of synovial natural killer cells through the RANKL‐RANK axis in osteoarthritis

AbstractChronic inflammation plays an important role in the progression of osteoarthritis (OA). Cumulative evidence suggests that natural killer (NK) cells potentially participate in OA inflammation. To investigate the regulation of NK cell reactivity in OA synovium, we characterized the phenotypic and functional properties of infiltrating NK cells in the synovial tissue in a rat collagenase‐induced OA model. Our data indicated that in comparison with splenic NK cells, OA synovial NK cells were poorly responsive to the stimulation of IL‐12 plus IL‐15 and IL‐18, as evidenced by lower production of IFN‐γ, perforin and granzyme B. Consistently, synovial NK cells showed lower cytotoxicity to target cells than splenic NK cells. Further investigations revealed that synovial NK cells highly expressed receptor activator of nuclear factor‐κB (RANK), while OA synovial fibroblasts (SFs) upregulated the expression of RANK ligand (RANKL). Co‐culture of OA SFs with RANK‐expressing NK cells inhibited cytokine‐induced production of above cytotoxic mediators in NK cells and subsequently impaired NK cell cytotoxicity. Gene silencing of RANKL expression in SFs partially recovered the cytotoxicity of NK cells after co‐culture. Furthermore, through the RANKL‐RANK axis, OA SFs induced RANKL expression in NK cells and subsequently promoted the osteoclastogenic activity of NK cells in vitro. Taken together, our study showed that OA SF inhibited the cytotoxicity while augmenting the osteoclastogenic activity of NK cells through the RANKL‐RANK axis. This study reveals a novel mechanism by which SFs modulate the reactivity of synovial NK cells in OA.

NF-κB c-Rel Is Dispensable for the Development but Is Required for the Cytotoxic Function of NK Cells.

Natural Killer (NK) cells are cytotoxic lymphocytes critical to the innate immune system. We found that germline deficiency of NF-κB c-Rel results in a marked decrease in cytotoxic function of NK cells, both in vitro and in vivo, with no significant differences in the stages of NK cell development. We found that c-Rel binds to the promoters of perforin and granzyme B, two key proteins required for NK cytotoxicity, and controls their expression. We generated a NK cell specific c-Rel conditional knockout to study NK cell intrinsic role of c- Rel and found that both global and conditional c-Rel deficiency leads to decreased perforin and granzyme B expression and thereby cytotoxic function. We also confirmed the role of c-Rel in perforin and granzyme B expression in human NK cells. c-Rel reconstitution rescued perforin and granzyme B expressions in c-Rel deficient NK cells and restored their cytotoxic function. Our results show a previously unknown role of c-Rel in transcriptional regulation of perforin and granzyme B expressions and control of NK cell cytotoxic function.

Inflammatory status might direct ILC and NK cells to IL-17 expressing ILC3 and NK subsets in Behcet's disease

Innate lymphoid cells (ILCs) are lymphoid cells that have important effector and regulatory functions in innate immunity and tissue remodeling. Uncontrolled activation and proliferation of ILCs can contribute to inflammatory autoimmune diseases. Behcet's disease (BD) is a complex systemic inflammatory disorder of unknown etiology. It has been shown that natural killer (NK) cells may play an immunoregulatory role in BD, however the role of ILCs is unknown. In this study, the levels and functions of ILCs and NK cell subsets in BD patients were investigated. Cell surface and cytotoxic granules (perforin and granzyme) expression of NK cells and ILCs were evaluated and labeled according to whole blood lysing protocol in peripheral blood samples obtained from the patients and healthy subjects. Cytokine levels of NK cells were investigated in stimulated peripheral blood mononuclear cells. All data were analyzed by flow cytometry. Total ILC and ILC3+ cells were increased in active BD patients compared to inactive BD patients and healthy subjects. There was no significant difference between the patients and healthy subjects regarding NK cell surface and intracellular molecule expression. Although, an increase in IFN-γ and IL-17, and a decrease in IL-4 levels were observed in CD56dim NK cell subset of BD patients. Recent studies showed increased neutrophilic infiltration and IL-17 secreting Th17 cells in BD patients. It is known that ILC3+cells are similar to Th17 subset regarding their cytokine profile and transcription factor expression patterns. Results of current study may suggest that inflammatory microenvironment in BD patients might direct ILC cells to differentiate into ILC3+ subset, and IL-17 released by NK cells might have a role in neutrophilic infiltration.

The transcriptional repressor ID2 supports natural killer cell maturation by controlling TCF1 amplitude.

Gaining a mechanistic understanding of the expansion and maturation program of natural killer (NK) cells will provide opportunities for harnessing their inflammation-inducing and oncolytic capacity for therapeutic purposes. Here, we demonstrated that ID2, a transcriptional regulatory protein constitutively expressed in NK cells, supports NK cell effector maturation by controlling the amplitude and temporal dynamics of the transcription factor TCF1. TCF1 promotes immature NK cell expansion and restrains differentiation. The increased TCF1 expression in ID2-deficient NK cells arrests their maturation and alters cell surface receptor expression. Moreover, TCF1 limits NK cell functions, such as cytokine-induced IFN-γ production and the ability to clear metastatic melanoma in ID2-deficient NK cells. Our data demonstrate that ID2 sets a threshold for TCF1 during NK cell development, thus controlling the balance of immature and terminally differentiated cells that support future NK cell responses.