ASO Author Reflections: Characteristics of Immune Evasion from Natural Killer Cells in Hepatoma Cancer Stem-Like Cells

Annals of Surgical Oncology -     

Natural Killer Cells and the Immune Response in Solid Organ Transplantation

Natural killer (NK) cells have been characterized classically for their cytotoxicity against pathogen infected or stressed cells as well as for their role in monitoring the expression of self MHC I. However, the participation of NK cells in solid organ transplantation (SOT) is poorly defined due to conflicting clinical and animal model data. Preclinical models have shown that NK cells exacerbate T‐cell allogeneic responses during rejection, but can also promote tolerance induction under immunosuppressive conditions. Further, while protocols such as costimulatory blockade effectively induce tolerance by blocking T‐cell activation and promoting Treg generation, how such regimens regulate other innate and adaptive immune cells, including NK cells, is incomplete. This review examines NK cells and the regulation of their effector functions in SOT.     

Breast Cancer Stem Cells and the Immune System: Promotion,Evasion and Therapy

Cancer stem cells are believed to be a subset of heterogeneous tumour cells responsible for tumour initiation, growth, local invasion, and metastasis. In breast cancer, numerous factors have been implicated in regulation of cancer stem cells, but there is still a paucity of information regarding precise molecular and cellular mechanisms guiding their pathobiology. Components of both the adaptive and the innate immune system have been shown to play a crucial role in supporting breast cancer growth and spread, and recently some immune mediators, both molecules and cells, have been reported to influence breast cancer stem cell biology. This review summarises a small, pioneering body of evidence for the potentially important function of the “immuniche” in maintaining and supporting breast cancer stem cells.     

Role of Natural Killer Cells in the Innate Immune System After Intraportal Islet Transplantation in Mice

Background

Both liver natural killer (NK) and NK T cells of the innate immune system play a crucial role in islet graft loss after intraportal islet transplantation, although a relationship between NK and NK T cells in islet loss has not been proven. In this study, we investigated the role of NK cells in the innate immune system in islet graft loss after intraportal islet transplantation.

Induction of Apoptosis by Canine Natural Killer Cells

Besides a secretory pathway of canine natural killer (NK) cells, which results in necrosis of the target cell, a second pathway was demonstrated, which results in apoptosis of the target cell. Comparing the Chromium Release Assay (CRA) and the Rose Bengal Assay (RBA) for quantification of in vitro canine NK cell activity, a constant 10% higher NK cell activity was found in the RBA compared with the CRA. To find out the mechanism responsible for the different results of both tests, morphological studies of in vitro canine NK cell activity against epithelial and mesenchymal allogenic target cell lines were performed. Most target cells were undergoing necrosis as a result of NK cell killing, which was evidenced by transmission electron microscopy. However, besides necrotic target cells, shrunken target cells with dense cytoplasm, fragmented nuclei and disruption into membrane‐bound bodies were detected, which are known as signs of apoptosis. Additionally, using the terminal deoxynucleotidyl transferase‐mediated dUTP nick end labelling (TUNEL) method, 13–23% of target cells presented a positive staining, indicative of apoptosis. These findings give evidence for the ability of canine NK cells to kill their target cells via two different pathways, which results either in apoptosis or necrosis.     

Significance of mTOR Signaling and Its Inhibitor Against Cancer Stem-Like Cells in Colorectal Cancer

Purpose

To determine the role of the mammalian target of rapamycin (mTOR) signaling in sustaining cancer stem-like cells and its clinical values in colorectal cancer (CRC).

Methods

mTOR expression in CRC patients was analyzed by immunohistochemistry and survival analysis was used to confirm the clinical value of mTOR. Colorectal cell lines were treated by mTOR inhibitors rapamycin and PP242, and sphere formation assay and aldehyde dehydrogenase (ALDH) assay were utilized to determine the impact of mTOR inhibition in CRC stem-like cells, combined or not combined with chemotherapeutic drug (fluorouracil and oxaliplatin).

Results

mTOR expression was associated with outcomes of CRC patients and predicted poor prognosis in stage II CRC patients. mTOR signaling was activated in stem-like colorectal cancer cells, and mTOR inhibitors (rapamycin and PP242) decreased the capacity of sphere formation as well as ALDH activity. Furthermore, mTOR inhibitors also were demonstrated to suppress the stimulation of stem-like cells by chemotherapy.

Conclusions

mTOR shared predictive significance in stage II CRC patients’ outcomes and played a vital role in the maintenance of colorectal cancer stem-like cells. mTOR inhibitors might hold the potential to become a therapeutic target against CRC stem cells.     

MELD and Child-Pugh Scores Are Related to Immune Status of Intrahepatic Natural Killer Cells in Liver Transplant Candidates

Background

The role and phenotypic alterations of intrahepatic natural killer (NK) cells in liver disease were investigated. Although intrahepatic NK cells reportedly functionally deteriorate in the fibrotic liver, it remains unclear how the clinical severity of liver disease affects intrahepatic NK cells in patients with advanced liver failure.

Tolerant T Cells Inhibit Natural Killer Cells Function in Antigen-Presenting Cells in an Independent Fashion

Understanding the relationships among immune cells in the setting of immunologic tolerance is imperative to maintain organ and tissue transplants. T cells and natural killer (NK) cells are responsible for both immune tolerance and immune rejection; however, there is only limited knowledge about the relevance of T and NK cells in tolerance. To address this issue, we explored the possible actions of tolerant T cells on NK cells by the means of mixed lymphocyte co-cultures and NK cytotoxicity assays. We showed that tolerant T cell-induced blockade of the co-stimulatory pathway significantly inhibited NK cell function in vitro regarding antigen-presenting cells. This action was cell-cell-contact dependent. We argue that tolerant T cells and NK cells impart synergistic cooperation to maintain transplant tolerance.     

Tumor-associated Macrophage-derived Interleukin-23 Interlinks Kidney Cancer Glutamine Addiction with Immune Evasion

Background

Glutamine addiction is a hallmark of clear cell renal cell carcinoma (ccRCC); yet whether glutamine metabolism impacts local immune surveillance is unclear. This knowledge may yield novel immunotherapeutic opportunities.

Activation of Natural Killer Cells and Macrophages by Porcine Endothelial Cells Augments Specific T-Cell Xenoresponse

The rejection of xenografts is characterized by infiltration of monocytes and natural killer (NK) cells into the graft, suggesting an important role for the innate immune system in xenorecognition. In this study, purified human NK or T cells were cocultured with porcine endothelial cells, and cytokines were analyzed by ELISA and intracellular FACS. We demonstrated a vigorous human anti-porcine xenoresponse that was associated with a strong T-cell proliferation against porcine endothelial cells. Limiting dilution cloning and T-cell receptor (TCR) Vbeta gene usage revealed a low number of xenoreactive T-cell precursors. We demonstrated that xenogeneic porcine but not allogeneic human endothelial cells induced the early production of interferon (IFN)-gamma by human NK cells but not by CD3+ T cells. Porcine xenoantigen-induced IFN-gamma production was only partially dependent on IL-12. Blocking IL-12 with neutralizing antibodies or by depletion of human macrophages partially decreased IFN-gamma production by CD56+ NK cells. Three-color flow cytometry revealed that IL-12 was produced through a species-specific activation of human macrophages by porcine endothelial cells. Our results indicate that the direct activation of NK cells and macrophages by porcine endothelial cells provides a unique pathway of xenorecognition that augments downstream specific T-cell immunity and represents a powerful effector mechanism in xenograft rejection.     

Monocytic Suppressor Cells Derived From Peripheral Blood Suppress Xenogenic Natural Killer Cell Lysis

Background

Myeloid-derived suppressor cells (MDSCs) were initially found to contribute to immunosuppression in tumor patients and have recently been recognized as a subset of innate immune cells that are capable of regulating adaptive immunity. A variety of innate immune stimuli, such as lipopolysaccharide, act as a double-edged sword, inducing both the maturation of dendritic cells and the expansion of MDSCs.

Methods

We isolated MDSCs from peripheral blood mononuclear cells (PBMCs) and examined the suppressive effect of MDSCs against xenocytotoxicity mediated by YT cells, a natural killer–like cell line, with the use of the lactate dehydrogenase assay method.

Results

Although primed MDSCs induced no significant suppression in YT cell–mediated cytotoxicity, activated MDSCs significantly suppressed the xenogenic cytotoxicity.

Conclusions

These findings indicate that MDSCs have a great deal of potential as a therapeutic strategy for dealing with xenograft rejection. Further investigations of the underlying mechanisms will facilitate the development of this therapeutic strategy.     

Non-Major Histocompatibility Complex Antigen Class I-Regulatory Molecule for Cytotoxicity by Natural Killer Cells

Abstract: The mechanism of the cytotoxicity by natural killer (NK) cells is not known. It is speculated that there exist several positively regulated and negatively regulated target molecules expressed on the target cell surface. Although one of the latter is considered to be major histocompatibility complex antigen (MHC) class I, in this study we described a novel non-MHC class 1 molecule that may negatively regulate the NK cytotoxicity. This antigen is defined by monoclonal antibody Cho-1 and is composed of noncovalently associated antigens that are 40 and 200 kilodaltons in molecular size. The expression of this antigen is reduced along with the cell growth induced by growth factors and/or oncogenes. Thus, Cho-1-defined antigen appears to be involved as one of the resistant molecules in the cytotoxic mechanism of NK cells.     

Differential Function of Natural Killer Cells in the Liver Graft Perfusate of Korean Population

Background

Liver perfusate (LP) lymphocytes show unique subsets compared with peripheral blood (PB) lymphocytes. LP natural killer (NK) and NKT cells may display unique cytotoxicity and cytokine production, thus leading to distinct roles in liver transplantation. In this study, we sought to evaluate the functions of graft perfusate NK and NKT cells in clinical liver transplantation.

Methods

The living donor right lobe graft was initially washed with 1 L of histidine-tryptophan-ketoglutarate solution to collect the perfusate. We also collected donor PB. Lymphocytes separated by the Ficoll-Hypaque density gradient method underwent immunophenotyping using multicolor flow cytometry. To assess cytokine secretion, we performed the enzyme-linked immunosorbent assay.

Results

There were more NK and NKT cells in LP confirming previous reports. In particular, CD56^brightCD16^low NK cells accounted for approximately 50% of total NK cells compared with 5% to 10% among PB NK cells. In response to cytokine stimulation LP NK cells produce tumor necrosis factor–α at different levels and less interleukin-10 compared with PB NK cells. The major source of interferon-γ production upon stimulation with liver caner cells were CD56^dim NK cells and CD56⁻CD3⁻ cells rather than NKT or T cells. Unlike PB NK cells, LP CD56^brightCD16^low NK cells along with CD56^dimCD16^high NK cells and NKT cells were efficient killers against Korean liver cancer cells.

Conclusion

LP NK and NKT cells showed unique functions in cytotoxicity and cytokine production.     

Impact of Steroids on Natural Killer Cells Against Cytotoxicity and Hepatitis C Virus Replication

Background

Natural killer (NK) cells play important roles in killing tumor and virus-infected cells. Immunosuppression used after organ transplantation is thought to increase the risk of tumor recurrence and viral infections. However, the effect of immunosuppressive drugs on NK cells has not yet been clearly established. Therefore, we examined the effect of immunosuppression on NK cells.

Immature Renal Dendritic Cells Recruit Regulatory CXCR6+ Invariant Natural Killer T Cells to Attenuate Crescentic GN

Immature renal dendritic cells (DCs) are protective early in murine crescentic GN, but the mechanisms underlying this protection are unknown. Here, depletion of DCs reduced the recruitment of invariant natural killer T (iNKT) cells, which attenuate GN, into the kidney in the early stage of experimental crescentic GN. More than 90% of renal iNKT cells expressed the chemokine receptor CXCR6, and renal DCs produced high amounts of the cognate ligand CXCL16 early after induction of nephritis, suggesting that renal DC-derived CXCL16 might attract protective CXCR6⁺ iNKT cells. Consistent with this finding, CXCR6-deficient mice exhibited less iNKT cell recruitment and developed nephritis that was more severe, similar to the aggravated nephritis observed in mice depleted of immature DCs. Finally, adoptive transfer of CXCR6-competent NKT cells ameliorated nephritis. Taken together, these results suggest an immunoprotective mechanism involving immature DCs, CXCL16, CXCR6, and regulatory iNKT cells, which might stimulate the development of new therapeutic strategies for GN.GN, as a disease category, is one of the leading causes of progressive renal failure leading to ESRD.¹ Among the different types of GN, crescentic GN is the most aggressive form with the worst prognosis. Crescentic GN represents a heterogeneous collection of disease entities, such as ANCA-associated GN and antiglomerular basement membrane (anti-GBM) nephritis.² Cell-mediated renal damage is, however, a fundamental characteristic of each form of crescentic GN.^3,4Nephrotoxic nephritis (NTN) is a well established murine model of crescentic GN.⁵ In this model, a sheep antiserum raised against kidney cortical components is injected into mice, resulting in activation of Th1 and Th17 cells in lymphatic organs. Because of their specificity, sheep Igs are preferentially deposited in the kidney, inducing tissue destruction by infiltrating activated Th1 and Th17 cells.^6–8 These cells subsequently activate intrarenal macrophages and drive neutrophil recruitment, causing renal tissue injury.⁹Dendritic cells (DCs) are professional antigen-presenting cells that play a pivotal role in the priming and activation of effector T cells, but under certain circumstances, they might also protect against an overwhelming inflammatory response by less well characterized mechanisms. Renal DCs form an extensive parenchymal network that spans the entire tubulointerstitium, ensuring complete surveillance of the kidney to protect it, for example, against infections ascending through the tubular system. Despite their absence from glomeruli, renal DCs are also involved in GN by capturing glomerular antigens or antigens filtered in glomeruli and presenting them to T effector cells, thereby triggering an inflammatory mononuclear infiltrate in the tubulointerstitium that drives renal disease.^10,11 It is important to note that renal DCs only exert this pathogenic effect when nephritis becomes chronic (DC maturation).¹² At steady state and in acute GN, they can also mediate anti-inflammatory and disease-attenuating effects.¹³ Generally, immature DCs are thought to induce immune tolerance, and this finding is thought to result from the absence of costimulatory signals.^14,15 It is unclear whether this tolerance causes the protective function of immature kidney DCs.Recent studies showed that renal DCs significantly contribute to the early production of chemokines and other inflammatory mediators, which regulates the recruitment of leukocytes into the inflamed kidney.¹⁶ We were, therefore, interested in studying whether renal DCs promote the infiltration of potentially anti-inflammatory leukocyte subsets in the early course of experimental GN (NTN) and characterizing the underlying mechanisms.     

Change in Mitochondrial Membrane Potential in Peripheral Blood Lymphocytes,Especially in Natural Killer Cells,Is a Possible Marker for Surgical Stress on the Immune System

There is accumulating evidence that surgical stresses cause impairment of systemic immune responses, which may promote susceptibility to infection as well as growth of remnant cancer cells in cancer patients. Although alterations in numbers, populations, and functions of lymphocytes have been extensively studied to assess modulation of the immune system, the precise mechanisms of immunosuppression caused by surgical stresses have not been identified, nor have methods been developed to estimate the magnitude of surgical stresses on the immune system. In the present study, to evaluate the effects of surgical procedures on the immune system, the mitochondrial membrane potential (_m) of peripheral blood lymphocytes (PBL) from 25 patients who underwent various types of operation was measured by flow cytometry using 3,3-dihexiloxacarbocyanine iodide (DiOC₆(3)) on the day before operation and on postoperative day (POD) 1, POD 3, and POD 7. The _m in PBL, especially in natural killer (NK) cell population, was reduced after major surgery. In particular, the reduction of _m in NK cells appeared to be proportional to the severity of the surgical procedures and reflected the impairment of cellular function. Interestingly, the _m in NK cells was also negatively correlated with the level of plasma noradrenaline after major surgery, suggesting that the reduction of _m in NK cells induced by surgical stresses may bemediated, at least in part, by the accompanying increase in plasma noradrenaline. Monitoring of _m in PBL after operation may be one of the useful markers for estimating the magnitude of surgical stresses on the immune system.     

细胞因子诱导的杀伤细胞免疫治疗对非小细胞肺癌患者术后免疫功能的影响

目的 探讨细胞因子诱导的杀伤(CIK)细胞免疫治疗对术后非小细胞肺癌(NSCLC)患者免疫功能的影响. 方法 选取Ⅰ期、Ⅱ期和Ⅲa期NSCLC患者50例,经手术治疗后随机分为两组,常规治疗组和CIK细胞治疗组,每组25例;分别于治疗前、治疗后2周、4周和8周动态监测患者免疫功能指标,包括外周血CD3 、CD4 、CD4 /CD8 比值、NK细胞比率以及Th1/Th2细胞因子水平. 结果 CIK细胞治疗组于CIK细胞治疗后2周,外周血CD3 、CD4 T细胞、NK细胞和CD4 /cD8 的比值、白细胞介素-2(IL-2)、干扰素Y(INF-γ)水平较治疗前升高(P＜0.01),于治疗后4周达高峰,此后逐渐回落;而Th2细胞因子于CIK细胞治疗后2周下降,治疗后4周降至低谷.CIK细胞治疗组于CIK细胞治疗后2、4、8周CD3 、CD4 、CD4 /CD8 、NK细胞、IL-2、INF-7、白细胞介素4(IL-4)和白细胞介素10(IL-10)与常规治疗组各时点比较差异有统计学意义[(P＜0.05),治疗后4周CD3 70.2%±9.1% vs.46.3%±5.8%;CD4 40.2%±7.1% vs.22.9%±4.5%;CD4 /CD8 1.82±0.43 vs.1.09±0.34;NK 15.7%±5.4% vs.10.5%±2.5%;IL-2 34.8±11.7 ng/L vs.19.8±12.1 ng/L;INF-γ 63.7±23.3 ng/L vs.30.8±10.6ng/L;IL-4 10.2±8.6 ng/L vs.25.8±6.3 ng/L;IL-10 10.6±3.4 ng/L vs.21.4±8.6 ng/L]. 结论 CIK细胞免疫治疗能增强NSCLC患者术后的免疫功能.