Tumor immunotherapy: New aspects of natural killer cells

A group of impressive immunotherapies for cancer treatment, including immune checkpoint-blocking antibodies,gene therapy and immune cell adoptive cellular immunotherapy, have been established, providing new weapons to fight cancer. Natural killer（NK） cells are a component of the first line of defense against tumors and virus infections. Studies have shown dysfunctional NK cells in patients with cancer. Thus, restoring NK cell antitumor functionality could be a promising therapeutic strategy. NK cells that are activated and expanded ex vivo can supplement malfunctional NK cells in tumor patients. Therapeutic antibodies, chimeric antigen receptor（CAR）, or bispecific proteins can all retarget NK cells precisely to tumor cells. Therapeutic antibody blockade of the immune checkpoints of NK cells has been suggested to overcome the immunosuppressive signals delivered to NK cells.Oncolytic virotherapy provokes antitumor activity of NK cells by triggering antiviral immune responses. Herein,we review the current immunotherapeutic approaches employed to restore NK cell antitumor functionality for the treatment of cancer.

Distribution of natural killer cells and T-lymphocyte subsets in peripheral blood,gallbladder cancer and surrounding tissue

BACKGROUND: The patient with malignant tumor always show immunologic function drawback and ingravescent with tumor development, especially in the aspect of cell-mediated immunity. This study was undertaken to define the relationship between the immune function of local cells and cancer development by investigating the distribution of natural killer (NK) cells and T-lymphocyte subsets in peripheral blood, the cancer tissue and the tissue surrounding gallbladder carcinoma. METHODS: The numbers of CD4(+) and CD8(+) T-lymphocytes and NK cells were measured by flow cytometry in samples taken from gallbladder cancer tissue, the surrounding tissues and peripheral blood of 38 patients, and compared with the numbers in the peripheral blood and gallbladder tissue of 30 patients with cholecystitis as controls. RESULTS: The numbers of CD4(+) and CD8(+) T-cells and NK cells in gallbladder cancer tissues were significantly higher than those in the surrounding tissue and gallbladder with gallstone. However, the ratio of CD4(+)/CD8(+) was lower in the cancer tissue than that in the surrounding tissue and tissue from gallbladders with gallstones. The distribution of CD4(+) and CD8(+) T-cells and NK cells in mucous membrane of cholecystitis gallbladder and that in the tissue surrounding gallbladder cancer were significantly different. CONCLUSIONS: Disproportionate and imbalanced distribution of NK cells and subsets of T-lymphocytes occurs in the mucous membrane proper of gallbladder cancer and surrounding tissue. Although gallbladder cancer tissue has higher expressions of CD4(+), CD8(+) and NK cells, the immune function is low or in an inhibited state. In gallbladder cancer immunization therapy, local cellular immunological function should be enhanced and the protective barrier improved.

Human natural killer cells for targeting delivery of gold nanostars and bimodal imaging directed photothermal/photodynamic therapy and immunotherapy

Objective:To construct a novel nanoplatform GNS@CaCO3/Ce6-NK by loading the CaCO3-coated gold nanostars(GNSs)with Chlorin e6 molecules(Ce6)into human peripheral blood mononuclear cells(PBMCs)-derived NK cells for tumor targeted therapy.Methods:GNS@CaCO3/Ce6 nanoparticles were prepared and characterized by TEM and UV-vis.The cell surface markers and cytokines secretion of NK cells before and after loading the GNS@CaCO3/Ce6 nanoparticles were detected by Flow Cytometry(FCM)and ELISA.Effects of the GNS@CaCO3/Ce6-NK cells on A549 cancer cells was determined by FCM and CCK-8.Intracellular fluorescent signals of GNS@CaCO3/Ce6-NK cells were detected via Confocal laser scanning microscopic(CLSM)and FCM at different time points.Intracellular ROS generation of GNS@CaCO3/Ce6-NK cells under laser irradiation were examined by FCM.The distribution of GNS@CaCO3/Ce6-NK in A549 tumor-bearing mice were observed by fluorescence imaging and PA imaging.The combination therapy of GNS@CaCO3/Ce6-NK under laser irradiation were investigated on tumor-bearing mice.Results:The coated CaC03 shell on the surface of GNSs exhibited prominent delivery and protection effect of Ce6 during the cellular uptake process.The as-prepared multifunctional GNS@CaCO3/Ce6-NK cells possessed bimodal functions of fluorescence imaging and photoacoustic imaging.The as-prepared multifunctional GNS@CaCO3/Ce6-NK cells could actively target tumor tissues with the enhanced photothermal/photodynamic therapy and immunotherapy.Conclusions:The GNS@CaCO3/Ce6-NK shows effective tumor-targeting ability and prominent therapeutic efficacy toward lung cancer A549 tumor-bearing mice.Through fully utilizing the features of GNSs and NK cells,this new nanoplatform provides a new synergistic strategy for enhanced photothermal/photodynamic therapy and immunotherapy in the field of anticancer development in the near future.

Natural killer cells in hepatitis C:Current progress

Patients infected with the hepatitis C virus(HCV) are characterized by a high incidence of chronic infection, which results in chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. The functional impairment of HCV-specific T cells is associated with the evolution of an acute infection to chronic hepatitis. While T cells are the important effector cells in adaptive immunity, natural killer(NK) cells are the critical effector cells in innate immunity to virus infections. The findings of recent studies on NK cells in hepatitis C suggest that NK cell responses are indeed important in each phase of HCV infection. In the early phase, NK cells are involved in protective immunity to HCV. The immune evasion strategies used by HCV may target NK cells and might contribute to the progression to chronic hepatitis C. NK cells may control HCV replication and modulate hepatic fibrosis in the chronic phase. Further investigations are, however, needed, because a considerable number of studies observed functional impairment of NK cells in chronic HCV infection. Interestingly, the enhanced NK cell responses during interferon-α-based therapy of chronic hepatitis C indicate successful treatment. In spite of the advances in research on NK cells in hepatitis C, establishment of more physiological HCV infection model systems is needed to settle unsolved controversies over the role and functional status of NK cells in HCV infection.

Functional distinction of rat liver natural killer cells from spleen natural killer cells under normal and acidic conditions in vitro

BACKGROUND: The microenvironment within solid tumors has often been shown to exhibit an acidic extracellular pH. Although the morphologic and functional differences in natural killer (NK) cells of the liver and spleen have been reported previously under physiological conditions, the difference under acidic conditions is still unclear. This study was to investigate the differences in the morphological and functional characteristics between rat liver and spleen NK cells under normal and acidic conditions in vitro. METHODS: Liver and spleen NK cells were isolated and purified from Sprague-Dawley rats by density gradient centrifugation and the Dynabeads FlowComp TM Flexi system, and stimulated for 4 days with or without IL-2 or treated with low pH or control for different times. Morphology was examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), cell death and proliferation assays were performed by flow cytometry, IFN-γ production was tested by ELISA, and cytotoxic activity was evaluated by lactate dehydrogenase (LDH) release assay. RESULTS: Liver NK cells had significantly higher levels of cytotoxic activity than spleen NK cells under normal and acidic conditions, and the maximum difference was observed at pH 5.6. Further analysis revealed that the cytotoxic activity of NK cells was correlated with morphology, cell death, proliferative activity and IFN-γ production. By TEM, liver NK cells contained a greater number of electron-dense granules per cell at pH 5.6.Moreover, a modest elevation of cell death and reduction of proliferation of liver NK cells occurred within a range of 5.6-7.2. Interestingly, an acidic extracellular pH only marginally, and not significantly, suppressed IFN-γ production by liver NK cells. CONCLUSION: The sharp morphological and functional differences shown by the two types of NK cells in vitro indicate that liver NK cells are unexpectedly resistant to pH shock.

Association of the frequency of peripheral natural killer T cells with nonalcoholic fatty liver disease

AIM: To investigate whether changes in the frequencyof peripheral natural killer T (NKT) cells were correlatedwith liver disease in patients who had metabolicpredispositions to nonalcoholic fatty liver disease(NAFLD).METHODS: Peripheral blood samples were obtainedfrom 60 Chinese NAFLD patients and 60 age and gendermatched healthy controls. The frequency of peripheralNKT cells was detected by flow cytometry. Clinical andlaboratory data were collected for further analysis. RESULTS: NAFLD patients had a lower frequencyof peripheral NKT cells than healthy controls (1.21%± 0.06% vs 1.62% ± 0.07%, P < 0.001). Furtheranalysis revealed that the frequency of peripheralNKT cells was negatively correlated with body massindex, waist circumference and serum levels of alanineaminotransferase. Logistic regression analysis revealedthat elevated body mass index [hazard ratio (HR):2.991], aspartate aminotransferase levels (HR: 1.148)and fasting blood sugar (HR: 3.133) increased the riskof NAFLD, whereas an elevated frequency of peripheralNKT cells (HR: 0.107) decreased the risk. CONCLUSION: Changes in the frequency of peripheralNKT cells were correlated with NAFLD and a decreasedfrequency of peripheral NKT cells was a risk factor forNAFLD.

Research on stress-induced apoptosis of natural killer cells and the alteration of their killing activity in mouse liver

AIM:To investigate the stress-induced apoptosis of natural killer(NK)cells and the changes in their killing activity in mouse livers.METHODS:A restraint stress model was established in mice.Flow cytometry was employed to measure the percentage of NK cells and the changes in their absolute number in mouse liver.The cytotoxicity of hepatic and splenic NK cells was assessed against YAC-1 target cells via a 4 h 51Cr-release assay.RESULTS:The restraint stress stimulation induced the apoptosis of NK cells in the liver and the spleen,which decreased the cell number.The number and percentage of NK cells in the spleen decreased.However,the number of NK cells in the liver decreased,whereas the percentage of NK cells was significantly increased.The apoptosis of NK cells increased gradually with prolonged stress time,and the macrophage-1(Mac-1)+NK cells were more susceptible to apoptosis than Mac-1-NK cells.Large numbers of Mac-1-NK cells in the liver,which are more resistant to stress-induced apoptosis,were observed than the Mac-1-NK cells in the spleen.The stress stimulation diminished the killing activity of NK cells in the spleen was significantly decreased,but the retention of numerous Mac-1-NK cells in the liver maintained the killing ability.CONCLUSION:Significant stress-induced apoptosis was observed among Mac-1+NK cells,but not Mac-1-NK cells in the mouse liver.Stress stimulation markedly decreased the killing activity of NK cells in the spleen but remained unchanged in the liver.

Tumor microenvironment in primary liver tumors: A challenging role of natural killer cells

In the last years,several studies have been focused on elucidate the role of tumor microenvironment(TME)in cancer development and progression.Within TME,cells from adaptive and innate immune system are one of the main abundant components.The dynamic interactions between immune and cancer cells lead to the activation of complex molecular mechanisms that sustain tumor growth.This important cross-talk has been elucidate for several kind of tumors and occurs also in patients with liver cancer,such as hepatocellular carcinoma(HCC)and intrahepatic cholangiocarcinoma(iCCA).Liver is well-known to be an important immunological organ with unique microenvironment.Here,in normal conditions,the rich immune-infiltrating cells cooperate with non-parenchymal cells,such as liver sinusoidal endothelial cells and Kupffer cells,favoring self-tolerance against gut antigens.The presence of underling liver immunosuppressive microenvironment highlights the importance to dissect the interaction between HCC and iCCA cells with immune infiltrating cells,in order to understand how this cross-talk promotes tumor growth.Deeper attention is,in fact,focused on immune-based therapy for these tumors,as promising approach to counteract the intrinsic anti-tumor activity of this microenvironment.In this review,we will examine the key pathways underlying TME cell-cell communications,with deeper focus on the role of natural killer cells in primary liver tumors,such as HCC and iCCA,as new opportunities for immune-based therapeutic strategies.

Impact of Fusobacterium nucleatum in the gastrointestinal tract on natural killer cells

BACKGROUND Gut microbial dysbiosis contributes to the development and progression of colorectal cancer(CRC).Natural killer(NK)cells are involved in early defense mechanisms to kill infective pathogens and tumor cells by releasing chemokines and cytokines.To better understand the relationship between the gut microbiome and CRC,it was hypothesized here that a high abundance of Fusobacterium nucleatum(F.nucleatum)in the gastrointestinal tract could cause reduced NK cell activity.AIM To identify associations between gastrointestinal tract F.nucleatum levels and NK cell activity.METHODS In vitro experiments were performed on NK cells treated with F.nucleatum,Peptostreptococcus anaerobius,and Parvimonas micra to identify the effects of gut microbiome species on NK cells.Following 24 and 48 h of treatment,NK cell counts were measured.In parallel studies,C57BL/6 mice were given broadspectrum antibiotics in their drinking water to reduce resident gut flora.After 3 wk,the mice received the various bacterial species or phosphate-buffered saline(PBS)via oral gavage every 2 d for 6 wk.At the study end,blood samples were acquired to perform NK cell activity assessment and cytokine analysis.Intestinal tissues were collected and analyzed via immunohistochemistry(IHC).RESULTS The data show that after 3 wk of broad-spectrum antibiotic treatment,levels of total bacteria and F.nucleatum were markedly decreased in mice.Gavage of F.nucleatum significantly decreased NK cell activity relative to the activities of cells from mice treated with antibiotics only and PBS.The administration of F.nucleatum decreased the proportion of NK46+cells based on IHC staining and increased the production of interleukin-1βand tumor necrosis factor-α.CONCLUSION High levels of F.nucleatum in the gastrointestinal tract reduced NK cell activity in mice,and the decrease in NK cell activity might be affected by increased proinflammatory cytokines after F.nucleatum treatment.

Effects of Intraoperative Administration of Dexmedetomidine on the Percentage of T-Lymphocyte Subsets and Natural Killer Cells in Patients with Colorectal Cancer

Study Objective: To observe the effect of dexmedetomidine (DEX) on T-lymphocyte subsets and natural killer (NK) cells in the peripheral blood of perioperative patients with colorectal cancer. Design: A random double-blind control clinical study. Setting: A university hospital. Patients: Forty patients with colorectal cancer, ASA I-П. Interventions: All patients were randomly divided into a DEX group (n = 20) and a control group (n = 20). Before induction of anesthesia, epidural catheters were placed in the L1-L2 or T12-L1 intervertebral spaces. The DEX group received 1 μg/kg of DEX (200 μg/50 ml) intravenously for 15 min prior to the surgery, which was then infused at a rate of 0.5 μg/kg/h until 30 min before the end of the surgery. The control group received an intravenous infusion of saline (50 ml) instead of DEX during the same periods as the DEX group. All patients received routine anesthesia and postoperative analgesia. Measurements: Blood samples from all patients were collected at the following time points: before anesthesia (T0), 24 h after surgery (T1), 48 h after surgery (T2) and 72 h after surgery (T3). Changes in T-lymphocyte subsets (CD3+, CD4+, CD8+, CD4+/CD8+) and NK cells were determined by flow cytometry. Main Results: Compared with the control group, the percentages of CD3+ and CD4+ cells and the CD4+/CD8+ ratio in the DEX group increased significantly from T1 to T3

Fasudil prevents liver fibrosis via activating natural killer cells and suppressing hepatic stellate cells

BACKGROUND Fasudil,as a Ras homology family member A(RhoA)kinase inhibitor,is used to improve brain microcirculation and promote nerve regeneration clinically.Increasing evidence shows that Rho-kinase inhibition could improve liver fibrosis.AIM To evaluate the anti-fibrotic effects of Fasudil in a mouse model of liver fibrosis induced by thioacetamide(TAA).METHODS C57BL/6 mice were administered TAA once every 3 d for 12 times.At 1 wk after induction with TAA,Fasudil was intraperitoneally injected once a day for 3 wk,followed by hematoxylin and eosin staining,sirius red staining,western blotting,and quantitative polymerase chain reaction(qPCR),and immune cell activation was assayed by fluorescence-activated cell sorting.Furthermore,the effects of Fasudil on hepatic stellate cells and natural killer(NK)cells were assayed in vitro.RESULTS First,we found that TAA-induced liver injury was protected,and the positive area of sirius red staining and type I collagen deposition were significantly decreased by Fasudil treatment.Furthermore,western blot and qPCR assays showed that the levels of alpha smooth muscle actin(α-SMA),matrix metalloproteinase 2(MMP-2),MMP-9,and transforming growth factor beta 1(TGF-β1)were inhibited by Fasudil.Moreover,flow cytometry analysis revealed that NK cells were activated by Fasudil treatment in vivo and in vitro.Furthermore,Fasudil directly promoted the apoptosis and inhibited the proliferation of hepatic stellate cells by decreasingα-SMA and TGF-β1.CONCLUSION Fasudil inhibits liver fibrosis by activating NK cells and blocking hepatic stellate cell activation,thereby providing a feasible solution for the clinical treatment of liver fibrosis.

Donor liver natural killer cells alleviate liver allograft acute rejection in rats

BACKGROUND:Liver enriched natural killer (NK) cells are of high immune activity.However,the function of donor liver NK cells in allogeneic liver transplantation (LTx) remains unclear.METHODS:Ten Gy of whole body gamma-irradiation (WBI) from a 60 Co source at 0.6 Gy/min was used for depleting donorderived leukocytes,and transfusion of purified liver NK cells isolated from the same type rat as donor (donor type liver NK cells,dtl NKs) through portal vein was performed immediately after grafting the irradiated liver.Post-transplant survival observation on recipients and histopathological detection of liver grafts were adoptive to evaluate the biological impact of donor liver NK cells on recipients’ survival in rat LTx.RESULTS:Transfusion of dtl NKs did not shorten the survival time among the recipients of spontaneous tolerance model (BN to LEW rat) after rat LTx,but prolonged the liver graft survival among the recipients depleted of donor-derived leukocytes in the acute rejection model (LEW to BN rat).Compared to the recipients in the groups which received the graft depleted of donor-derived leukocytes,better survival and less damage in the allografts were also found among the recipients in the two different strain combinations of liver allograft due to transfusion of dtl NKs.CONCLUSIONS:Donor liver NK cells alone do not exacerbate liver allograft acute rejection.Conversely,they can alleviate it,and improve the recipients’ survival.

Immune evasion and therapeutic opportunities based on natural killer cells

Natural killer(NK)cells can elicit an immune response against malignantly transformed cells without recognizing antigens,and they also exhibit cytotoxic effects and immune surveillance functions in tumor immunotherapy.Although several studies have shown the promising antitumor effects of NK cells in immunotherapy,their function is often limited in the tumor microenvironment because tumor cells can easily escape NK cell-induced death.Thus,for efficient tumor immunotherapy,the mechanism by which tumor cells escape NK cell-induced cytotoxicity must be fully understood.Various novel molecules and checkpoint receptors that mediate the disruption of NK cells in the tumor microenvironment have been discovered.In this review,we analyze and detail the major activating and inhibitory receptors on the surface of NK cells to delineate the mechanism by which tumor cells suppress NKG2D ligand expression and increase tumor receptor and inhibitory receptor expression[NKG2A,programmed cell death1(PD-1),and T-cell immunoglobulin and immunoreceptor tyrosine inhibitory motif(TIGIT)]on the NK cell surface,and thus inhibit NK cell activity.We also reviewed the current status of treatments based on these surface molecules.By comparing the therapeutic effects related to the treatment status and bypass mechanisms,we attempt to identify optimal single or combined treatments to suggest new treatment strategies for tumor immunotherapy.

CD4+ T cells and natural killer cells: Biomarkers for hepatic fibrosis in human immunodeficiency virus/hepatitis C virus-coinfected patients

AIM To characterize peripheral blood natural killer(NK) cells phenotypes by flow cytometry as potential biomarker of liver fibrosis in human immunodeficiency virus(HIV)/hepatitis C virus(HCV) coinfected patients.METHODS Peripheral mononuclear cells from 24 HIV/HCV(HBVnegative) coinfected and 5 HIV/HCV/HBV seronegative individuals were evaluated. HIV/HCV coinfected patients were divided in to groups: G1, patients with METAVIR F0-F2 and G2, patients with METAVIR F3-F4. NK surface cell staining was performed with: AntiCD3(APC/Cy7), anti-CD56(PE/Cy5), anti-CD57(APC), anti-CD25(PE), anti-CD69(FITC), anti-NKp30(PE), antiNKp46(PE/Cy7), anti-NKG2D(APC), anti-DNAM(FITC); anti-CD62L(PE/Cy7), anti-CCR7(PE), anti-TRAIL(PE), anti-Fas L(PE), anti CD94(FITC). Flow cytometry data acquisition was performed on BD FACSCanto, analyzed using Flow Jo software. Frequency of fluorescence was analyzed for all single markers. Clinical records were reviewed, and epidemiological and clinical data were obtained.RESULTS Samples from 11 patients were included in G1 and from 13 in G2. All patients were on ARV, with undetectable HIV viral load. Liver fibrosis was evaluated by transient elastography in 90% of the patients and with biopsy in 10% of the patients. Mean HCV viral load was(6.18 ± 0.7 log10). Even though, no major significant differences were observed between G1 and G2 regarding NK surface markers, it was found that patients with higher liver fibrosis presented statistically lower percentage of NK cells than individual with low to mild fibrosis and healthy controls(G2: 5.4% ± 2.3%, G1: 12.6% ± 8.2%, P = 0.002 and healthy controls 12.2% ± 2.7%, P = 0.008). It was also found that individuals with higher liver fibrosis presented lower CD4 LT count than those from G1(G2: 521 ± 312 cells/μL, G1: 770 ± 205 cells/μL; P = 0.035).CONCLUSION Higher levels of liver fibrosis were associated with lower percentage of NK cells and LTCD4+ count; and they may serve as noninvasive biomarkers of liver damage.

HBsAg stimulates NKG2D receptor expression on natural killer cellsand inhibits hepatitis C virus replication

Background： Higher hepatitis B surface antigen （HBsAg） facilitates hepatitis C virus （HCV） clearance inpatients with hepatitis B virus （HBV）/HCV co-infection. We investigated the effect of exogenous HBsAgon the inhibition of HCV replication mediated by natural killer （NK） cells.

Recovery of natural killer cells is mainly in post-treatment period in chronic hepatitis C patients treated with sofosbuvir plus ledipasvir

AIM To investigate how natural killer(NK) cells are affected in the elimination of hepatitis C virus(HCV) by sofosbuvir/ledipasvir, two highly effective direct-acting antivirals(DAAs). METHODS Thirteen treatment-na?ve and treatment-experienced chronic hepatitis C(CHC) patients were treated with sofosbuvir/ledipasvir, and NK cells were detected at baseline, weeks 2, 4, 8 and 12 during therapy, and week post of treatment(Pt)-12 and 24 after the end of therapy by multicolor flow cytometry and compared with those from 13 healthy controls. RESULTS All patients achieved sustained virological response. There was a significant decline in CD56^(bright) NK cell frequencies at week 8(P = 0.002) and week 12(P = 0.003), which were altered to the level comparable to healthy controls at week Pt-12, but no difference was observed in the frequency of CD56^(dim) NK cells. Compared with healthy controls, the expression levels of NKG2A, NKp30 and CD94 on NK cells from CHC patients at baseline were higher. NKG2A, NKp30 and CD94 started to recover at week 12 and reached the levels similar to those of healthy controls at week Pt-12 or Pt-24. Before treatment, patients have higher interferon(IFN)-γ and perforin levels than healthy controls, and IFN-γ started to recover at week 8 and reached the normalized level at week Pt-12. CONCLUSION NK cells of CHC patients can be affected by DAAs, and phenotypes and function of NK cells recover not at early stage but mainly after the end of sofosbuvir/ledipasvir treatment.

Inhibition effect of natural killer T cells on transplantation hepatocellular carcinoma in mice

Objective:The aim of this study was to investigate the inhibition effect of natural killer T(NKT) cells on transplantation hepatocellular carcinoma in mice.Methods:α-galactosylceramide(α-GalCer)-pulsed DC and Hep S were prepared as stimulus.Hepatoma xenograft model was established and mice were randomly divided into 4 groups(n=13 each group):(1) control group,intravenous injection of the same volume of saline.(2) mature DC group,intravenous injection of mature DC cells(4×106 cells).(3) α-GalCer-pulsed HepS group,intravenous injection of α-GalCer-pulsed HepS(4×106 cells).(4) α-GalCer-pulsed mature DC group,intravenous injection of α-GalCer-pulsed DC(4×106 cells).The changes of tumor volume in mice and survival period were measured every 2 days.Percentage of NKT cells in spleens and cytotoxicity of spleen cells were detected by flow cytometry.Tumor tissues were analyzed by histopathological examination.Results:In α-GalCer-pulsed Heps and DC groups,the average survival period was prolonged and tumor volume was markedly decreased,spleen cells and NKT cells were significantly increased,and tumor necrosis was evident,compared to the control group.Conclusion:α-GalCer-pulsed DC and HepS could activate NKT cells in vivo,also increase NKT cells cytotoxicity,inhibit the growth of hepatomas and prolong survival period.

Natural killer cells activity in a metastatic colorectal cancer patient with complete and long lasting response to therapy

Here we report a case of a 70-year-old man who received adjuvant chemotherapy with fluorouracile, folinic acid and oxaliplatin after a left hemicolectomy for a stage Ⅲb adenocarcinoma in May 2009. During followup he de-veloped abdominal lymphnodes metastases evidenced by positron emission tomography-computed tomography(PET-CT) scan and increase of carcinoembryonic antigen(CEA) level. Chemotherapy with capecitabine, oxaliplatin and bevacizumab was started in April 2012. Restaging showed a complete response and normalization of CEA. The patient received maintenance therapy with bevacizumab which was stopped in December 2013 for patient choice. In October 2014, a new increase in CEA was documented and PET-CT scan showed lung metastases. Analysis of RAS status revealed the absence of mutations, then the patient started a second-line chemotherapy with fluorouracile, folinic acid, irinotecan(folfiri) and panitumumab achieving, in January 2015, a complete response and normalization of CEA. Thereafter, folfiri was discontinued for toxicity; furthermore, upon the third occurrence of a grade 3 dermatologic toxicity, panitumumab was continued from June 2015 at 60% of the original dose and it was administered every three weeks. Until presentation of this case, the patient maintains a complete response, has no symptoms of disease and CEA is normal. Interestingly, this patient presented a high proportion of circulating natural killer(NK) cells(35.1%) with high cytotoxic activity against tumor cells. Study on the role of NK in patients with advanced colorectal cancer are ongoing.

Advancement of chimeric antigen receptor-natural killer cells targeting hepatocellular carcinoma

With the advance of genome engineering technology,chimeric antigen receptors(CARs)-based immunotherapy has become an emerging therapeutic strategy for tumors.Although initially designed for T cells in tumor immunotherapy,CARs have been exploited to modify the function of natural killer(NK)cells against a variety of tumors,including hepatocellular carcinoma(HCC).CAR-NK cells have the potential to sufficiently kill tumor antigen-expressing HCC cells,independent of major histocompatibility complex matching or prior priming.In this review,we summarize the recent advances in genetic engineering of CAR-NK cells against HCC and discuss the current challenges and prospects of CAR-NK cells as a revolutionary cellular immunotherapy against HCC.

EFFECTS OF PERIOPERATIVE CIMETIDINE ADMINISTRATIONON NATURAL KILLER CELLS IN PATIENTS WITHGASTROINTESTINAL CANCER

Objective: To study the effects of perioperative use of cimetidine on natural killer (NK) cells in gastrointestinal (GI) cancer patients. Methods: 49 GI cancer patients were randomized into treatment group which took cimetidine in the perioperative period, and control group which did not take the drug. NK cells were measured by immunocytochemical method, using mouse-anti-human CD57 monoclonal antibody as the primary antibody. Blood samples from 20 healthy volunteers were treated in the same way as normal control. Comparisons were made within and between groups. Results: The NK cell percentage of normal control was 18.50±2.31. Both groups of patients had significantly lower than normal NK percentages before treatment (P<0.05). NK cell percentages at admission, before operation, on the 2nd and the 10th postoperative days were 14.60±3.91, 15.64±3.61, 17.40±3.28, 20.68±4.13, respectively, for the treatment group, and 14.88±2.76, 13.17±2.93, 14.50±2.77, 15.67±2.55, respectively, for control group. The difference between the two groups was statistically significant. Conclusion: Perioperative cimetidine application can help restore NK cells. The drug may be useful to reverse postoperative immuno-depression in GI cancer patients.