Decreased Natural Killer Cell Activity Research Articles

Characteristic and prognosis of patients with non-EBV infection-associated hemophagocytic lymphohistiocytosis

目的探讨非EB病毒病原体所致感染相关噬血细胞综合征（IAHLH）患者的临床特征及预后。方法收集2015年1月至2021年3月首都医科大学附属北京友谊医院确诊的48例非EB病毒病原体所致IAHLH患者的临床资料，对患者的临床特征、治疗、疗效及预后进行回顾性分析。结果共纳入48例患者，男28例，女20例，中位年龄34.5（2.0～74.0）岁，导致IAHLH的病原体中，病毒16例（33.3％），细菌17例（35.4％），寄生虫13例（27.1％），真菌2例（4.2％），患者发病至确诊噬血细胞综合征（HLH）的中位时间为40（10～160）d，发病至确诊为IAHLH的中位时间为67（23～270）d。患者起病时临床表现如下：发热48例（100％），脾大34例（70.8％），血细胞减低38例（79.1％），铁蛋白升高45例（93.8％），甘油三酯升高7例（14.6％），纤维蛋白原降低17例（35.4％），NK细胞活性减低26例（59.1％），可溶性CD25升高35例（74.5％）。25例（52.1％）患者起病时伴淋巴结肿大。明确导致HLH的病原体后尽快减停细胞毒药物及激素并应用有效的抗感染治疗，36例（75.0％）患者获得完全缓解，93.3％（14/15）的寄生虫及真菌所致IAHLH患者获得了病情缓解，细菌及病毒相关IAHLH仅有66.7％（22/33）的缓解率。患者5年预期总生存（OS）率为72.3％（95％ CI 50.3％～69.8％），多因素分析显示，总胆红素大于2倍正常上限（OR＝20.0，95％ CI 1.1～378.3，P＝0.046）及诱发HLH的病原体感染未控制（OR＝19.9，95％ CI 2.9～134.5，P＝0.002）为预后不良因素。结论非EB病毒病原体所致IAHLH预后较好，诊断后应尽快减停细胞毒药物及激素，有效控制病原体感染为关键性治疗。

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

BACKGROUNDGut 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.AIMTo identify associations between gastrointestinal tract F. nucleatum levels and NK cell activity.METHODSIn 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 broad-spectrum 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). RESULTSThe 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-1β and tumor necrosis factor-α.CONCLUSIONHigh 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 pro-inflammatory cytokines after F. nucleatum treatment.

Natural killer cells efficiently target multiple myeloma clonogenic tumor cells

The multiple myeloma (MM) landscape has changed in the last few years, but most patients eventually relapse because current treatment modalities do not target clonogenic stem cells, which are drug-resistant and can self-renew. We hypothesized that side population (SP) cells represent myeloma clonogenic stem cells and, searching for new treatment strategies, analyzed the anti-myeloma activity of natural killer (NK) cells against clonogenic cells. Activated and expanded NK cells (NKAE) products were obtained by co-culturing NK cells from MM patients with K562-mb15-41BBL cell line and characterized by flow cytometry. Functional experiments against MM cells were performed by Eu-TDA release assays and methylcellulose clonogenic assays. Side population was detected by Dye Cycle Violet labeling and then characterized by flow cytometry and RNA-Seq. Self-renewal capacity was tested by clonogenic assays. Sorting of both kind of cells was performed for time-lapse microscopy experiments. SP cells exhibited self-renewal potential and overexpressed genes involved in stem cell metabolism. NK cells from MM patients exhibited dysregulation and had lower anti-tumor potential against clonogenic cells than healthy donors’ NK cells. Patients’ NK cells were activated and expanded. These cells recovered cytotoxic activity and could specifically destroy clonogenic myeloma cells. They also had a highly cytotoxic phenotype expressing NKG2D receptor. Blocking NKG2D receptor decreased NK cell activity against clonogenic myeloma cells, and activated NK cells were able to destroy SP cells, which expressed NKG2D ligands. SP cells could represent the stem cell compartment in MM. This is the first report describing NK cell activity against myeloma clonogenic cells.

Peripheral natural killer cell activity is associated with poor clinical outcomes in pancreatic ductal adenocarcinoma.

We aimed to measure the natural killer (NK) cell activity and pro-inflammatory cytokine levels in the peripheral blood of pancreatic cancer patients and investigate the correlation of NK cell activity and cytokines with cancer status and clinical outcomes. We prospectively enrolled patients who were pathologically diagnosed with pancreatic ductal adenocarcinoma (PDAC) between 2016 and 2017 at a tertiary hospital in Seoul, South Korea. As a control group, healthy participants were enrolled by mobile application recruitment. A total of 203 patients were enrolled for this study (PDAC, n=102; healthy participants, n=101). The peripheral blood NK cell activity of PDAC patients was significantly lower than that of healthy participants (median level, 95pg/mL vs 2000pg/mL, P<0.001), and decreased NK cell activity was correlated to poor clinical outcome in terms of response to chemotherapy, tumor progression, and survival. The pro-inflammatory cytokine interleukin-6 had a strong negative correlation with NK cell activity. In pancreatic cancer patients, NK cell activity decreased as cancer progressed, and decreased NK cell activity was associated with poor clinical outcomes.

Impact of Smoking on Human Natural Killer Cell Activity: A Large Cohort Study.

Some studies have reported a decrease in the natural killer (NK) cell activity in smokers. However, large-scale data on the relationship between NK cell activity and smoking are unavailable. A cross-sectional study was performed on 12,249 asymptomatic examinees who underwent an NK cell activity test, between January 2016 and May 2017. The test quantitated the amount of interferon-γ secreted into the plasma by NK cells, using a patented stimulatory cytokine. The mean age of the study population was 39.1 years, and the proportions of “never”, “former”, and “current” smokers were 65.5%, 20.9%, and 13.6%, respectively. Current smokers (1,422 pg/mL) had a lower median level of NK cell activity than never smokers (1,504 pg/mL, P = 0.039) and former smokers (1,791 pg/mL, P < 0.001). Among current smokers, NK cell activity decreased with increase in the number of cigarettes smoked among current smokers (median, 1,537, 1,429, and 1,175 pg/mL at <10, 10-19, and ≥ 20 pack-years, respectively; P < 0.001). Additionally, it decreased linearly with increasing quartiles of cotinine levels (median, 1,707, 1,636, 1,348, and 1,292 pg/mL at cotinine levels < 292, 292-879, 880-1,509, and ≥ 1,510 ng/mL, respectively; r = –0.122, P < 0.001). NK cell activity was lower in current smokers. It also decreased with an increase in the number of cigarettes smoked, and it was negatively correlated with cotinine levels among current smokers. Our findings indicate a clear relationship between smoking and decreased NK cell activity.

Anti-Leukemia Effects of NK Cell-Derived Exosomes

Introduction: Exosomes are 30-150 nm-sized extracellular vesicles originating from the endocytic compartment of parent cells. The exosome molecular cargo reflects the content of its cells of origin and is delivered to recipient cells in a protective glycol-lipid bilayer without degradation. Because of their small size, exosomes freely circulate within the body, can reach the bone marrow, and can cross biological barriers. Natural killer (NK) cells play a critical role in the innate immune response through their capacity to lyse malignant cells without prior antigen-specific priming. Importantly, NK cell activity is reduced in patients with acute myeloid leukemia (AML) relative to that in healthy donors. To overcome the decreased NK cell activity in AML, several therapeutic strategies have been evaluated for safety and efficacy, both in transplant and non-transplant settings, using autologous and allogeneic activated NK cells. Since NK cell-derived exosomes acquire tumor-killing abilities from the parent NK cells, we hypothesize that NK cell-derived exosomes by transferring exosome content to leukemia blasts can induce the death of these target cells. In the current study, we evaluated the in vitro anti-leukemia effects of NK cell-derived exosomes. Methods: Exosomes were isolated from the supernatants of NK cells obtained from healthy donors (n=12) using mini-size exclusion chromatography (mini-SEC). Protein levels, number and size (qNano), and exosome morphology using transmission electron microscopy were determined. The exosome cargo was studied by Western blots and on-bead flow cytometry for NK cell activating and inhibitory receptors, immune inhibitory molecules, and for perforin and granzyme B. Cytotoxicity of the NK cell-derived exosomes for AML cell lines (Kasumi, MLL-1) and primary leukemia blasts was measured using flow cytometry-based assays. Results: Activated human NK cells produced large quantities of exosomes. Transmission electron microscopy showed the presence of vesicles that were uniform in size (30-150nm in diameter) by NanoSight measurement. Confocal imaging of labeled NK cell-derived exosomes interacting with leukemia cells showed that they are rapidly internalized by leukemic targets. NK cell-derived exosomes carried activating NK cell receptor NKG2D, natural cytotoxicity receptors, perforin, granzyme B, transforming growth factor beta (TGF-β), killer-cell immunoglobulin-like receptors, and PD-1. NK cell-derived exosomes were co-incubated with target cells, AML cell lines and primary leukemia cells, at different exosome:target (E:T) ratios using escalating doses of exosomes (10-70 µg). NK cell-derived exosomes mediated strong anti-leukemic activity against AML cell lines and primary leukemic blasts. Importantly, with higher doses of exosomes, higher levels of cytotoxicity were observed, suggesting that exosome-mediated lysis is concentration dependent. NK cell-derived exosomes mediated leukemia killing via different cell death pathways including apoptosis and necroptosis. Conclusion: NK cell-derived exosomes mediating cytotoxicity against leukemic targets represents a novel therapeutic modality for patients with AML. Disclosures No relevant conflicts of interest to declare.

Analyses on the Clinical Usefulness of Natural Killer Cell Activity in Non-Small Cell Lung Cancer Patients

SESSION TITLE: Lung Cancer Diagnostics SESSION TYPE: Original Investigation Slide PRESENTED ON: Wednesday, November 1, 2017 at 02:45 PM - 04:15 PM PURPOSE: Natural killer (NK) cells have a potent cytolytic activity against malignant tumor cells. But in immune escape, the immunosuppressive tumor microenvironment impairs NK cell activity and then causes cancer progression. This study is aimed at investigating the alteration of NK cell activity in non small cell lung cancer (NSCLC) and the role of NK cell activity in advanced NSCLC after immune escape. METHODS: A prospective observational study evaluating NK cell activity and other clinical factors was conducted in a tertiary hospital between January 2016 and February 2017. NK cell activity was measured by NK vue® kit which detected ex vivo stimulated IFN-r levels of the peripheral blood by ELISA. NK cell subsets were measured by flow cytometry. The correlation of NK cell activity with other clinical factor including Age, smoking history, smoking quantity, NK cell subsets proportion (CD56bright/CD56dimcells ratio, Geometric mean of CD56brightcells), tumor marker (CEA, CYFRA 21-1) and CRP were analyzed by linear regression. All results are presented as mean ± SD. RESULTS: 48 patients of NSCLC (stage I: 13, stage II: 7, stage III: 8, stage IV: 20), 38 patients of benign lung disease and 33 healthy controls were recruited. There were 33 adenocarcinoma, 13 squamous cell carcinoma, 1 large cell carcinoma and 1 NOS patents. NK cell activity was significantly reduced in NSCLC patients compared to controls and benign lung disease patients (1660±878.7 vs 1516±1066 vs 958.7±1011 pg/mL for control vs benign lung disease vs NSCLC, respectively; p<0.05). NK cell activity tended to decrease according to cancer stage progression (1924±953.4 vs 890.0±971.8 vs 356.7±523.0 vs 596.1±791.4 for stage I vs stage II vs stage III vs stage IV, respectively) and significantly decreased in advanced stage compared to early stage (1562±1062 vs 527.7±723.7 pg/mL for stage I, II vs stage III, IV, respectively; p=0.0001). NK cell activity was significantly reduced in nodal positive NSCLC compared to nodal negative NSCLC (1494±1083 vs 637.2±827.9 pg/mL for NO vs N1, N2, N3, respectively; p=0.0025). CD56brightcells/CD56dimcells ratio (0.0326±0.0406 vs 0.0318±0.0180 vs 0.0311±0.0233 for control vs benign lung disease vs NSCLC, respectively; p=0.4496) and geometric mean of CD56brightcells (185.4±62.45 vs 203.8±75.49 vs 166.8±45.77 for control vs benign lung disease vs NSCLC, respectively; p=0.1507) were not different between the three groups. Other clinical factors including Age, smoking history, smoking quantity, NK cell subsets, tumor marker and CRP were not correlated with NK cell activity by univariate and multivariate analyses. CONCLUSIONS: NK cell activity decreased significantly in NSCLC patients and was further reduced in advanced stage and nodal positive NSCLC. CD56brightcells/CD56dimcells ratio and other clinical factors did not affect NK cell activity. CLINICAL IMPLICATIONS: Decreased NK cell activity may reflect immune escape in NSCLC progression and NK cell activity may have a role of biomarker of advanced lung cancer. DISCLOSURE: The following authors have nothing to disclose: Sue In Choi, Kwnag Ho In, Kyung Ho Kang, Jae Jeong Shim, Chol Shin, Sang Yeub Lee, Je Hyeong Kim, Sung Yong Lee, Seung Heon Lee, Gyu Young Hur, Kyung Hoon Min, Eun Joo Lee, Won Jai Jung No Product/Research Disclosure Information

Polychlorinated biphenyls (PCBs) modulate both phagocytosis and NK cell activity in vitro in juvenile loggerhead sea turtles (Caretta caretta)

ABSTRACTThreatened loggerhead sea turtles (Caretta caretta) face numerous environmental challenges, including exposure to anthropogenic chemicals such as polychlorinated biphenyls (PCBs). Despite being banned by the USA in the 1970s, PCBs persist in the environment and produce immunotoxic effects in a wide range of marine vertebrate species. This is of particular concern, as the modulation of the immune system may enhance the susceptibility to a variety of pathogens. Blood samples were collected from 19 immature, captive-reared loggerhead sea turtles. Functional immune assays phagocytosis and natural killer (NK) cell activity were used to quantify the direct effects of PCB congeners 105, 138, and 169 on innate immune functions upon in vitro exposure of sea turtle cells to increasing concentrations (control (0), 0.5, 1, 2.5, 5, 10, 15, or 20 ppm) of each PCB. PCB 105 significantly elevated eosinophil phagocytosis at 10 and 15 ppm and PCB 138 at 15 ppm compared to unexposed (0 ppm). The effects of PCB 169 on phagocytosis were not evaluated. PCB 138 and 105 significantly decreased NK cell activity at 15 and 20 ppm, compared to unexposed (0 ppm) controls. PCB 169 did not markedly modulate NK activity. This constitutes the first study to investigate the in vitro effects of these three PCBs on sea turtle innate immune functions. These results add to our understanding of PCB-induced immunotoxicity in sea turtles and may provide a framework for establishing the relationships between chemical levels and turtle immunity.

Decreased expression of NKG2D, NKp46, DNAM-1 receptors, and intracellular perforin and STAT-1 effector molecules in NK cells and their dim and bright subsets in metastatic melanoma patients.

Although natural killer (NK) cells play an important antitumor role, melanoma cells may affect their effector functions. In this study, we analyzed the expression of various receptors and effector molecules in NK cells and their subsets in metastatic melanoma (MM) patients compared with healthy controls (HCs). In HC and MM patients, we analyzed NK cell activity using a chromium release assay and the expression of CD107a degranulation marker, activating NKG2D, NKp46, DNAM-1, and inhibitory CD158a and CD158b receptors, IL-12R beta 1, IL-12R beta 2, intracellular interferon (IFN)-γ, perforin, and STAT-1 in CD3-CD56+ NK cells, and cytotoxic CD3-CD56 and immunoregulatory CD3-CD56 subsets by flow cytometry. MM patients compared with HC not only had significantly decreased NK cell activity, lower expression of CD107a, and impaired IFN-γ production but also had decreased expression of activating NKG2D, NKp46, and DNAM-1 receptors, which was followed by lower expression of perforin, STAT-1, and both IL-12R subunits in NK cells. In MM patients only, there was a positive correlation between NKG2D expression and degranulation capacity, as well as IFN-γ production in NK cells. Analysis of the expression of various parameters of NK cell effector functions between MM patients with different localization of distant metastases showed that patients in the unfavorable M1c subclass had decreased expression of NKG2D and NKp46 on NK cells compared with patients in the M1a+b group. Downregulated NKG2D, NKp46, and DNAM-1 receptors associated with impaired NK cell effector function are important biomarkers of advanced disease with a poor prognosis in melanoma patients.

HIV infection and depression

Major depression is highly prevalent among HIV-positive patients (HIVpp). The prevalence of depression ranges between 18% and 81%, depending on the population studied and the methodology of the study. The etiology of depression in HIVpp is likely determined by: (i) biological factors (alterations in the white matter structure, hypothalamic-pituitary-thyroid dysfunction, Tat-protein-induced depressive behavior); (ii) psychosocial factors (HIV stigma, occupational disability, body image changes, isolation and debilitation); (iii) history or comorbidity of psychiatric illness; and (iv) the perinatal period in HIVpp women. Symptomatology of depression differs between HIVpp and HIV-negative patients (HIVnp). Depression may also alter the function of lymphocytes in HIVpp and decrease natural killer cell activity, contributing to the increased mortality in these patients. Selective serotonin re-uptake inhibitors are considered the first-line treatment. Treatment of depression can improve quality of life and lead to a better prognosis of HIV infection.

Role of NK cells and HLA-G in endometriosis

Impaired natural killer (NK) activity in women with endometriosis is thought to promote implantation and progression of endometrial tissue, in accord with Sampson's hypothesis. However, the mechanisms responsible for decreased NK cell activity and the antigens recognized by NK cells are not clear.We focused on human leukocyte antigen (HLA)-G, a ligand of NK receptors, expression and its menstrual cycle changes by eutopic endometrium. Interestingly, HLA-G expression was identified on eutopic endometrium only in the menstrual phase but not in the proliferative or secretory phases. Furthermore, HLA-G expressing cells were also detected in peritoneal fluid during the menstrual period. During retrograde menstruation, HLA-G expressing endometrial tissue may enter the peritoneal cavity, and may be reduced by immunosurveillance system. Although peritoneal NK cells play an important role in this system, impairment of NK cytotoxicity via HLA-G may allow peritoneal endometrial cell survival and implantation. In this review, we discuss the pathogenesis of endometriosis from the viewpoint of intraperitoneal immune interaction between NK cell receptors and HLA-G that can enter into peritoneal cavity from eutopic endometrium through retrograde menstruation.

Chronic Inflammation and CD16+ Natural Killer Cell Zeta-Chain Downregulation in Hemodialysis Patients

Background: Natural killer (NK) cell activity is decreased in hemodialysis (HD) patients. Zeta-chain phosphorylation is an early event that follows the triggering of some NK cell-activating receptors. NK cell zeta-chain is downregulated in patients with cancer due to chronic inflammation. HD is also a chronic inflammatory state. NK cell zeta-chain expression in HD was evaluated. Patients and Methods: Thirty-three HD patients and 30 healthy volunteers were enrolled into the study. The CD3–CD16+ subpopulation was examined, since it corresponds to 90% of all NK cells and has the highest cytotoxicity.NK cell count and zeta-chain mean fluorescence intensity were evaluated with flow cytometry. The inflammatory markers C-reactive protein, IL-6 and tumor necrosis factor-α were measured with ELISA. Results: The inflammatory markers were increased in HD patients. NK cell count did not differ between HD patients and healthy volunteers. NK cell zeta-chain mean fluorescence intensity was decreased in the patient group. Conclusions: Chronic inflammation could be responsible for the NK cell zeta- chain downregulation in HD patients, contributing to the decreased NK cell activity.

Association of vitamin A deficiency with decrease in tumor necrosis factor-α expressing CD3−CD56+ natural killer cells in Ghanaians

Although low plasma vitamin A concentrations are associated with increased incidence or severity of infections such as respiratory tract infection and measles in children, there is a paucity of data on the effect of vitamin A deficiency on the distribution of, and cytokine production by, the different cellular immune subsets in humans. We conducted a cross-sectional study in a district in Ghana to characterize cellular subsets and functional capacity of peripheral blood mononuclear cells from vitamin A deficient and vitamin A sufficient (normal) individuals, and evaluated the relationships between vitamin A concentration in plasma and cellular immune status. We measured the percentages of selected cellular phenotypes and intracellular cytokine expression and describe the differential cellular subset distributions and alterations in cytokine expression in participants with normal and deficient vitamin A concentrations. The major change observed in the constitution of cellular subsets was a decrease in TNF-α expressing CD3-CD56+ NK cells in those with vitamin A deficiency compared with normal individuals. CD4+ T cell proliferation and production of IFN-γ and IL-4 were not statistically different between the two groups. These results support previous studies that demonstrated decreased NK cell activity in vitamin A deficient animals. The decrease in TNF-α expressing NK cells observed in vitamin A deficient individuals in this study could help to explain the decreased resistance to infections observed in those with vitamin A deficiency.

Modern management of children with haemophagocytic lymphohistiocytosis.

Modern management of children with haemophagocytic lymphohistiocytosis.

Long-term immune-endocrine effects of bereavement: relationships with anxiety levels and mood

Psychological, endocrine and immune parameters were measured over a 6-month period in 14 healthy subjects who underwent an unpredictable acute emotional stress (e.g. sudden death of a loved one) compared with 14 controls who did not. Probands were profoundly stressed as assessed 10 days after bereavement by their scores on the Hamilton Rating Scales of Anxiety and Depression, adrenocorticotropin and cortisol plasma concentrations, and non-suppression in response to dexamethasone. Functional alterations of immune parameters, such as responsiveness of peripheral blood lymphocytes to mitogens, were found 40 days after bereavement. Despite a normal number of circulating lymphocyte subsets, the functional activity of natural killer (NK) cells was markedly reduced at day 40. Changes in the intracellular concentration of β-endorphin in peripheral blood mononuclear cells correlated with anxiety and depression scores. Controls showed no changes in psychometric, endocrine and immune measures during the 6-month study. Cluster analysis revealed two groups of bereaved subjects with different patterns of immune and endocrine changes: (1) Five subjects, characterized by harm-avoidant temperament and long-lasting dysphoric mood, showed reduced responsiveness of peripheral blood lymphocytes to mitogens, decreased NK cell activity and non-suppression in response to dexamethasone that persisted for 6 months. (2) Nine subjects showed significant changes only during the early phase after bereavement. Our data suggest that the immunological consequences of stress do not simply overlap with psychological and endocrine alterations, and are particularly severe and long-lasting in a subgroup of subjects, indicating the importance of individual variability in the capacity to cope with stress.

Metallothioneins/PARP-1/IL-6 interplay on natural killer cell activity in elderly: parallelism with nonagenarians and old infected humans. Effect of zinc supply

Metallothioneins (MTs) play pivotal role in zinc-related cell homeostasis because of their high affinity for this trace element which is in turn relevant against oxidative stress and for the efficiency of the entire immune system, including natural killer (NK) cell activity. In order to accomplish this role, MTs sequester and/or dispense zinc during stress and inflammation to protect cells against reactive oxygen species. MTs gene expression is affected by IL-6 for a prompt immune response. Concomitantly, MTs release zinc for the activity of antioxidant zinc-dependent enzymes, including poly(ADP-ribose)polymerase-1(PARP-1), which is involved in base excision DNA-repair. This role of MTs is peculiar in young adult-age during transient stress and inflammation, but not in ageing because stress-like condition and inflammation are persistent. This may lead MTs to turn-off from role of protection in young age to deleterious one in ageing with subsequent appearance of age-related diseases (severe infections). The aim is to study the role played by MTs/IL-6/PARP-1 interplay on NK cell activity in elderly, in old infected patients (acute and remission phases by bronchopneumonia infection) and in health nonagenarian/centenarian subjects. MTmRNA is high in lymphocytes from elderly people coupled with high IL-6, low zinc ion bioavailability, decreased NK cell activity and impaired capacity of PARP-1 in base excision DNA-repair. The same trend in this altered physiological cascade during ageing also occurs in old infected patients (both acute and remission phases) with more marked immune damage, inflammatory condition and very impaired PARP-1 in base excision DNA-repair. By contrast, centenarian subjects display low MTmRNA, good zinc ion bioavailability, satisfactory NK cell activity and higher capacity of PARP-1 in base excision DNA-repair. These findings clearly demonstrate that the sequester of zinc by MTs in ageing is deleterious because leading to low zinc ion bioavailability with subsequent impairment of PARP-1 and NK cell activity and appearance of severe infections. Physiological zinc supply (12 mg Zn ++/day) for 1 month in elderly and in old infected patients (remission phase) restores NK cells activity with values observed in health centenarians. Therefore, the zinc ion bioavailability by zinc-bound MTs homeostasis is pivotal to reach health longevity and successful ageing.

Perioperative immunosuppression in cancer patients.

Cancer patients commonly undergo surgical procedures. The perioperative period is characterized by immunosuppression and may predispose already immunosupressed cancer patients to tumor spread. Cancer patients typically show depression of both cellular and humoral immune functions. Possible mediating factors for immunosuppression during the perioperative period include anesthetic agents, opioids, surgery, blood transfusions, temperature changes, pain, and psychological stress. A surgically mediated decrease in natural killer (NK) cell activity has been implicated as the major contributing factor associated with an increase in metastasis. The decreased NK cell activity during the perioperative period is associated with increased risk of mortality and cancer. Commonly used anesthetic agents and opioids are known to inhibit NK cell activity. Despite the in vivo evidence of anesthetic- and analgesic-agent-mediated immunosupression, surgery by itself results in a three- to four-fold increase in retention of metastasis when compared to the groups in which anesthesia and analgesia were combined. The negative consequences associated with perioperative immunosuppression may be decreased by several strategies, including aggressive pain control, selection of specific anesthetic and analgesic agents, avoidance of unnecessary transfusions, and delay of elective surgeries until the patient's nutritional and immune status is optimized. Recognizing and neutralizing its mediating factors, perioperative immunosuppression in cancer patients may be reduced.

Selective loss of viability of mouse NK cells in culture is associated with decreased NK cell lytic function.

Cell culture methods can allow investigation of the mechanisms responsible for immunotoxicity. Unfortunately, natural killer (NK) cells in rodent splenic cultures rapidly lose their cytolytic function. It is not known if death of NK cells or loss of function in viable NK cells is primarily responsible for this loss. Flow cytometry and an assay of NK cell lytic function were used to address this issue and to determine if NK cell viability could be maintained by adding selected cytokines or a caspase inhibitor to the cultures. Total cells and NK cells in untreated 18 h cultures were 79 +/- 1% and 25 +/- 2% viable, respectively, and these cultured splenocytes caused only 4 +/- 1% specific release of (51)Cr from YAC-1 target cells. Cultures including polyinosinic:polycytidylic acid (poly I:C) or IL-2 had increased NK cell viability (43 +/- 2%, 47 +/- 1%) and function (58 +/- 2 and 43 +/- 1% specific release). IL-15 significantly increased NK cell viability, but not function. Previous studies demonstrated that treatment of mice with immunotoxicants such as ethanol or corticosterone diminishes NK cell activation in vitro in response to poly I:C. To determine if alterations in viability are responsible for this decreased NK cell activity, lytic function and NK activity were measured in cultures of splenocytes treated in vivo or in vitro with ethanol and/or corticosterone. Some treatments reduced IL-2 or poly I:C-enhanced lytic activity in vitro, but there was no clear relationship between these changes in function and changes in the percentage of viable NK cells. Thus, immunotoxicants that suppress NK cell activation can be investigated in vitro because commonly used activating stimuli also permit NK cell survival. However, no agents were identified that could maintain NK cell viability and function in culture (without activation) to allow investigation of the direct effects of immunotoxicants on basal NK activity in vitro.

Dietary supplementation with eicosapentaenoic acid, but not with other long-chain n−3 or n−6 polyunsaturated fatty acids, decreases natural killer cell activity in healthy subjects aged >55 y

Animal studies showed that dietary flaxseed oil [rich in the n-3 polyunsaturated fatty acid alpha-linolenic acid (ALA)], evening primrose oil [rich in the n-6 polyunsaturated fatty acid gamma-linolenic acid (GLA)], and fish oil [rich in the long-chain n-3 polyunsaturated fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)] can decrease natural killer (NK) cell activity. There have been no studies of the effect on NK cell activity of adding these oils to the diet of humans. Our objective was to determine the effect of dietary supplementation with oil blends rich in ALA, GLA, arachidonic acid (AA), DHA, or EPA plus DHA (fish oil) on the NK cell activity of human peripheral blood mononuclear cells. A randomized, placebo-controlled, double-blind, parallel study was conducted. Healthy subjects aged 55-75 y consumed 9 capsules/d for 12 wk; the capsules contained placebo oil (an 80:20 mix of palm and sunflower seed oils) or blends of placebo oil and oils rich in ALA, GLA, AA, DHA, or EPA plus DHA. Subjects in these groups consumed 2 g ALA, 770 mg GLA, 680 mg AA, 720 mg DHA, or 1 g EPA plus DHA (720 mg EPA + 280 mg DHA) daily, respectively. Total fat intake from the capsules was 4 g/d. The fatty acid composition of plasma phospholipids changed significantly in the GLA, AA, DHA, and fish oil groups. NK cell activity was not significantly affected by the placebo, ALA, GLA, AA, or DHA treatment. Fish oil caused a significant reduction (mean decline: 48%) in NK cell activity that was fully reversed by 4 wk after supplementation had ceased. A moderate amount of EPA but not of other n-6 or n-3 polyunsaturated fatty acids can decrease NK cell activity in healthy subjects.

Reconstitution of NK Cell Activity in HIV-1 Infected Individuals Receiving Antiretroviral Therapy

We studied natural immunity mediated by natural killer (NK) cells in 62 HIV-1 infected individuals, 54 HIV-1 infected individuals receiving highly active antiretroviral therapy (HAART) for more than one year and 8 HIV-1 infected individuals without antiretroviral therapy. 22 individuals had a complete suppression of viral replication characterized by viral load values <50 copies/ml, whereas 32 individuals presented with persistent viral replication. The 8 untreated patients had an indication to start antiretroviral treatment. Lytic activity of NK cells was measured in a 51 chromium release assay. In patients with persistent viral replication under HAART NK cell activity was significantly decreased compared to patients with effective control of HIV viremia. Patients with complete suppression of HIV replication displayed a similar NK activity to healthy control persons. Differences in antibody-dependent cellular cytotoxicity (ADCC) were not observed. Further studies will investigate whether decreased NK cell activity is a reason for or the consequence of persistent viral replication.