Measurement of NK activity in whole blood by the CD69 up-regulation after co-incubation with K562, comparison with NK cytotoxicity assays and CD107a degranulation assay

GlcNac produced by the gut microbiome enhances host influenza resistance by modulating NK cells

Microbiota are known to modulate the host response to influenza infection, but the mechanisms remain largely unknown. Gut metabolites are the key mediators through which gut microbes play anti-influenza effect. Transferring fecal metabolites from mice with high influenza resistance into antibiotic-treated recipient mice conferred resistance to influenza infections. By comparing the metabolites of different individuals with high or low influenza resistance, we identified and validated N-acetyl-D-glucosamine (GlcNAc) and adenosine showed strong positive correlations with influenza resistance and exerted anti-influenza effects in vivo or in vitro, respectively. Especially, GlcNAc mediated the anti-influenza effect by increasing the proportion and activity of NK cells. Several gut microbes, including Clostridium sp., Phocaeicola sartorii, and Akkermansia muciniphila, were positively correlated with influenza resistance, and can upregulate the level of GlcNAc in the mouse gut by exogenous supplementation. Subsequent studies confirmed that administering a combination of the three bacteria to mice via gavage resulted in similar modulation of NK cell responses as observed with GlcNAc. This study demonstrates that gut microbe-produced GlcNAc protects the host against influenza by regulating NK cells, facilitating the elucidation of the action mechanism of gut microbes mediating host influenza resistance.

Differential Immune-Modulating Activities of Cell Walls and Secreted Metabolites from Probiotic Bacillus coagulans JBI-YZ6.3 under Normal versus Inflamed Culture Conditions

Spore-forming probiotic bacteria, including Bacillus coagulans, are resilient and produce a variety of beneficial metabolites. We evaluated the immune-modulating effects of the novel probiotic strain Bacillus coagulans JBI-YZ6.3, where the germinated spores, metabolite fraction, and cell wall fraction were tested in parallel using human peripheral blood mononuclear cell cultures under both normal and lipopolysaccharide-induced inflamed culture conditions. The expression of CD25 and CD69 activation markers was evaluated via flow cytometry. Supernatants were tested for cytokines, interferons, chemokines, and growth factors using Luminex arrays. The germinated spores were highly immunogenic; both the cell wall and metabolite fractions contributed significantly. Under normal culture conditions, increased levels of immune activation were observed as increased expressions of CD25 and CD69 relative to natural killer cells, suggesting an increased ability to attack virus-infected target cells. On monocytes, a complex effect was observed, where the expression of CD25 increased under normal conditions but decreased under inflamed conditions. This, in combination with increased interleukin-10 (IL-10) and decreased monocyte chemoattractant protein-1 (MCP-1) production under inflamed conditions, points to anti-inflammatory effects. The production of the stem cell-related growth factor granulocyte colony-stimulating Factor (G-CSF) was enhanced. Further research is warranted to characterize the composition of the postbiotic metabolite fraction and document the characteristics of immunomodulating agents secreted by this probiotic strain.

The pro-tumorigenic responses in metastatic niches: an immunological perspective

Metastasis is the leading cause of mortality related to cancer. In the course of metastasis, cancer cells detach from the primary tumor, enter the circulation, extravasate at secondary sites, and colonize there. All of these steps are rate limiting and decrease the efficiency of metastasis. Prior to their arrival, tumor cells can modify the secondary sites. These favorable microenvironments increase the probability of successful dissemination and are referred to as pre-metastatic niches. Cancer cells use different mechanisms to induce and maintain these niches, among which immune cells play prominent roles. The immune system, including innate and adaptive, enhances recruitment, extravasation, and colonization of tumor cells at distant sites. In addition to immune cells, stromal cells can also contribute to forming pre-metastatic niches. This review summarizes the pro-metastatic responses conducted by immune cells and the assistance of stromal cells and endothelial cells in the induction of pre-metastatic niches.

CD4 and IL-2 mediated NK cell responses after COVID-19 infection and mRNA vaccination in adults

A detailed understanding of protective immunity against SARS-CoV-2 is incredibly important in fighting the pandemic. Central to protective immunity is the ability of the immune system to recall previous exposures. Although antibody and T cell immunity have gained considerable attention, the contribution of the NK cell compartment to immune recall and protection from SARS-CoV-2 has not been explored. In this study, we investigate the NK cell responses to stimulation with SARS-CoV-2 in previously exposed and non-exposed individuals. We show that NK cells demonstrate an enhanced CD4+ T cell dependent response when re-exposed to SARS-CoV-2 antigen. The enhanced response is dependent on T cells and correlates with the number of SARS-CoV-2 specific CD4 T cells. We find that IL-2 is a critical mediator of NK cell function. These findings suggest that NK cells contribute to the protective responses against SARS-CoV-2 through a cooperation with antigen-specific CD4 T cells and have significant implications on our understanding of protective immunity in SARS-CoV-2.

Nucleotide-Binding Oligomerization Domain 1/Toll-Like Receptor 4 Co-Engagement Promotes Non-Specific Immune Response Against K562 Cancer Cells

Nucleotide-binding oligomerization domain 1 (NOD1) receptor and Toll-like receptor 4 (TLR4) belong to the family of pattern recognition receptors. Interactions between these receptors profoundly shape the innate immune responses. We previously demonstrated that co-stimulation of peripheral blood mononuclear cells (PBMCs) with D-glutamyl-meso-diaminopimelic acid (iE-DAP)-based NOD1 agonists and lipopolysaccharide (LPS), a TLR4 agonist, synergistically increased the cytokine production. Herein, we postulate that stimulation of NOD1 alone or a combined stimulation of NOD1 and TLR4 could also strengthen PBMC-mediated cytotoxicity against cancer cells. Initially, an in-house library of iE-DAP analogs was screened for NOD1 agonist activity to establish their potency in HEK-Blue NOD1 cells. Next, we showed that our most potent NOD1 agonist SZZ-38 markedly enhanced the LPS-induced cytokine secretion from PBMCs, in addition to PBMC- and natural killer (NK) cell-mediated killing of K562 cancer cells. Activation marker analysis revealed that the frequencies of CD69⁺, CD107a⁺, and IFN-γ⁺ NK cells are significantly upregulated following NOD1/TLR4 co-stimulation. Of note, SZZ-38 also enhanced the IFN-γ-induced PBMC cytotoxicity. Overall, our findings provide further insight into how co-engagement of two pathways boosts the non-specific immune response and attest to the importance of such interplay between NOD1 and TLR4.

A Case-Control Study on the Changes in Natural Killer Cell Activity following Administration of Polyvalent Mechanical Bacterial Lysate in Korean Adults with Recurrent Respiratory Tract Infection

Polyvalent mechanical bacterial lysate (PMBL) is used for the treatment and prevention of recurrent respiratory tract infections. Although PMBL is an immunostimulant, it remains unknown whether treatment with PMBL influences natural killer cell activity (NKA). Hence, this case-control study compared the changes in IFN-γ levels (surrogate index for NKA) following PMBL treatment or time passing between the PMBL-treated group and controls. The treatment group included adults who had a PMBL prescription for three months against recurrent respiratory tract infection from an outpatient clinic, while the control group had healthy adults visiting the health promotion center for periodic health check-ups. The control group (N = 506) showed no change in IFN-γ levels, while the treatment group (N = 301) showed a significant increase in mean from 462.8 to 749.3 pg/mL after PMBL treatment. In the subgroup with IFN-γ <500 pg/mL, IFN-γ levels significantly increased in both groups. However, the change in the treatment group (287 ± 822 pg/mL) was greater than that in the control group (58 ± 809 pg/mL), and the interaction between the visit and case/control was significant (p = 0.030) in a generalized estimating equation model. In conclusion, NKA increased in the subjects with recurrent respiratory tract infections with PMBL treatment.

Analysis of the Characteristics of TIGIT-Expressing CD3-CD56+NK Cells in Controlling Different Stages of HIV-1 Infection

TIGIT expression on natural killer (NK) cells is associated with dysfunction during chronic HIV infection, but the phenotype and biological functions of these cells in the context of acute HIV-1 infection remain poorly understood. Here, 19 acutely infected HIV-1 patients traced at first, third and twelfth month, and age-matched patients with chronic HIV-1 infection were enrolled to investigate the phenotype and functions of TIGIT expression on NK cells. We found that TIGIT-expressing NK cells did not increase in frequency in the first, third and twelfth month of infection until chronic HIV-1 infection lasted over 2 years. The number of TIGIT⁺NK cells in acute infection was positively associated with HIV-1 viral load (r = 0.53, P = 0.0009). CD96 was significantly upregulated on NK cells after acute infection for 1 month and in chronic infection over 2 years, while CD226 was downregulated in chronic infection over 2 years. Further, at different stages of infection, CD96⁻CD226⁺ cells diminished among total NK cells, TIGIT⁺NK and TIGIT⁻NK cells, while CD96⁺CD226⁻ cells expanded. Reduced CD96⁻CD226⁺ cells and elevated CD96⁺CD226⁻ cells among NK cells especially TIGIT⁻NK cells, had opposite associations with viral load in the first month of infection, as well as CD4 T-cell counts in including the twelfth month and more than 2 years of chronic infection. In both HIV-1-infected individuals and healthy donors, TIGIT was predominantly expressed in NKG2A⁻NKG2C⁺NK cells, with a significantly higher proportion than in NKG2A⁺NKG2C⁻NK cells. Moreover, the frequencies of TIGIT⁺NK cells were positively associated with the frequencies of NKG2A⁻NKG2C⁺NK cells in acute infection (r = 0.62, P < 0.0001), chronic infection (r = 0.37, P = 0.023) and healthy donors (r = 0.36, P = 0.020). Enhanced early activation and coexpression of CD38 and HLA-DR in TIGIT⁺NK cells were detected compared to TIGIT⁻NK cells, both of which were inversely associated with the decrease in CD4 T-cell counts in both acute and chronic HIV-1 infection. The ability of TIGIT⁺NK cells to produce TNF-α, IFN-γ and CD107a degranulation substance were consistently weaker than that of TIGIT⁻NK cells in both acute and chronic infection. Moreover, the functionalities of TIGIT⁺NK cells were lower than those of TIGIT⁻NK cells, except for TNF-α⁻CD107a⁺IFN-γ⁻NK cells. These findings highlight the phenotype and functional characteristics of TIGIT-expressing NK cells which have poor capabilities in inhibiting HIV-1 replication and maintaining CD4 T-cell counts.

Oxidative Stress Compromises Lymphocyte Function in Neonatal Dairy Calves

Dairy calves are unable to mount an effective immune response during their first weeks of life, which contributes to increased disease susceptibility during this period. Oxidative stress (OS) diminishes the immune cell capabilities of humans and adult cows, and dairy calves also experience OS during their first month of life. However, the impact that OS may have on neonatal calf immunity remains unexplored. Thus, we aimed to evaluate the impact of OS on newborn calf lymphocyte functions. For this, we conducted two experiments. First, we assessed the association of OS status throughout the first month of age and the circulating concentrations of the cytokines interferon-gamma (IFN-γ) and interleukin (IL) 4, as well as the expression of cytokine-encoding genes IFNG, IL2, IL4, and IL10 in peripheral mononuclear blood cells (PBMCs) of 12 calves. Subsequently, we isolated PBMCs from another 6 neonatal calves to investigate in vitro the effect of OS on immune responses in terms of activation of lymphocytes, cytokine expression, and antibody production following stimulation with phorbol 12-myristate 13-acetate or bovine herpesvirus-1. The results were compared statistically through mixed models. Calves exposed to high OS status in their first month of age showed higher concentrations of IL-4 and expression of IL4 and IL10 and lower concentrations of IFN-γ and expression of IFNG and IL2 than calves exposed to lower OS. In vitro, OS reduced lymphocyte activation, production of antibodies, and protein and gene expression of key cytokines. Collectively, our results demonstrate that OS can compromise some immune responses of newborn calves. Hence, further studies are needed to explore the mechanisms of how OS affects the different lymphocyte subsets and the potential of ameliorating OS in newborn calves as a strategy to augment the functional capacity of calf immune cells, as well as enhance calves’ resistance to infections.

[Significance of evaluation of CD69 expression by peripheral blood lymphocytes for predicting pregnancy outcome in women with recurrent pregnancy loss]

The aim of this work was to characterize phenotypically peripheral blood T- and NK lymphocytes expressing an early marker of activation, CD69, and assess the significance of CD69 expression for predicting pregnancy outcome in women with idiopathic reccurent pregnancy loss (IRP) before and after immunocytotherapy (ICT). The study group consisted of 36 patients with IRP who became pregnant after pre-gestational allimmunization, in 30 patients the pregnancy was prolonged to the full term and ended with the birth of a viable baby, in 6 - it was terminated before 12 weeks of gestation. In the control group, 15 fertile women outside pregnancy and 11 women at 12 weeks of physiological pregnancy were examined. Assessment of the CD69 expression in women with prolonged pregnancy revealed the absence of significant differences with the control group in the content and proportion of activated lymphocytes (CD69+). In women with aborted pregnancy after pre-gestational ICT, an increase in the number of almost all analyzed lymphocyte subpopulations responding to the activation stimulus, with a clear tendency to increase the proportion of activated T- but not NK-lymphocytes was found. At 5-6 weeks, the proportion of activated lymphocytes among a subpopulation of cytotoxic T-lymphocytes (CD3+CD8+/CD3+CD8+CD69+) in these women was significantly higher than in women with prolonged pregnancy, which confirms the leading role of effector cytotoxic T-lymphocytes in rejection reactions. Thus, the studies showed the promise of evaluating the expression of the early activation marker CD69 as an additional laboratory criterion for the personable appointment of immunocytotherapy to women with a common reccurent pregnancy loss.

Natural killer frequency determines natural killer cytotoxicity directly in accentuated zones and indirectly in "moderate-to-normal frequency" segment

Natural killer (NK) frequency and NK cytotoxicity (NKc) are key determining factors of a clinical outcome. In our previous study, we showed the prognostic clinical significance of immune parameters when they are beyond the optimal range (accentuated). In this study, we attempted to explain the disparity of accentuated but physiologically and immunologically normal NK parameters that might serve as negative clinical prognostics indications of failed pregnancies. We have analyzed NK%, NKc levels, and their reciprocal correlation in 2,804 patients with reproductive failures. In the entire clinical population, NK% correlates with NKc. Interestingly, we found this relationship to be strongly dependent on NK level's status. NK%-NKc correlation was the strongest (r = 0.2021, p < 0.0001) in a patient group with high NK% (> 17.5%). Patients with NK% between 15-17.5% manifested lower but still significant correlation NK%-NKc (r = 0.1213, p = 0.0155). Additionally, significant correlation (r = 0.2689, p < < 0.0001) between NK% and NKc was observed in a group of patients with NK levels < 7% (1.7-7%). While patients' groups with NK% (7-15%) did not reveal NK%-NKc association. This led us to hypothesize that the qualitative-quantitative status of NK population is responsible for their cytotoxic activity. Consistent with our hypothesis, the "balanced zone" NK% is tightly controlled, and thus does not correlate directly with NKc. In contrast, the "accentuated zones" of NK% escape this control and directly affecting NKc. Demonstrated phenomena supports our idea about the clinical significance of immune accentuation and explains its novel physiological role.

Metastasis-associated macrophages constrain antitumor capability of natural killer cells in the metastatic site at least partially by membrane bound transforming growth factor β

BACKGROUND

Metastatic breast cancer is a leading cause of cancer-related death in women worldwide. Infusion of natural killer (NK) cells is an emerging immunotherapy for such malignant tumors, although elimination of the immunosuppressive tumor environment is required to improve its efficacy. The effects of this "metastatic" tumor environment on NK cells, however, remain largely unknown. Previous studies, including our own, have demonstrated that metastasis-associated macrophages (MAMs) are one of the most abundant immune cell types in the metastatic tumor niche in mouse models of metastatic breast cancer. We thus investigated the effects of MAMs on antitumor functions of NK cells in the metastatic tumor microenvironment.

METHODS

MAMs were isolated from the tumor-bearing lung of C57BL/6 mice intravenously injected with E0771-LG mouse mammary tumor cells. The effects of MAMs on NK cell cytotoxicity towards E0771-LG cells were evaluated in vitro by real-time fluorescence microscopy. The effects of MAM depletion on NK cell activation, maturation, and accumulation in the metastatic lung were evaluated by flow cytometry (CD69, CD11b, CD27) and in situ hybridization (Ncr1) using colony-stimulating factor 1 (CSF-1) receptor conditional knockout (Csf1r-cKO) mice. Finally, metastatic tumor loads in the chest region of mice were determined by bioluminescence imaging in order to evaluate the effect of MAM depletion on therapeutic efficacy of endogenous and adoptively transferred NK cells in suppressing metastatic tumor growth.

RESULTS

MAMs isolated from the metastatic lung suppressed NK cell-induced tumor cell apoptosis in vitro via membrane-bound transforming growth factor β (TGF-β) dependent mechanisms. In the tumor-challenged mice, depletion of MAMs increased the percentage of activated (CD69+) and mature (CD11b+CD27-) NK cells and the number of Ncr1+ NK cells as well as NK cell-mediated tumor rejection in the metastatic site. Moreover, MAM depletion or TGF-β receptor antagonist treatment significantly enhanced the therapeutic efficacy of NK cell infusion in suppressing early metastatic tumor outgrowth.

CONCLUSION

This study demonstrates that MAMs are a main negative regulator of NK cell function within the metastatic tumor niche, and MAM targeting is an attractive strategy to improve NK cell-based immunotherapy for metastatic breast cancer.

Vogt-Koyanagi-Harada patients show higher frequencies of circulating NKG2Dpos NK and NK T cells

Vogt-Koyanagi-Harada (VKH) is an autoimmune disease characterized by inflammation in tissues that contain melanocytes. We aimed to increase the knowledge regarding immunological pathways deregulated in VKH disease. We compared the percentages of circulating natural killer (NK), NK T and T cells expressing the activatory markers: CD16, CD69, NK group 2D (NKG2D), natural cytotoxicity triggering receptor 3 (Nkp30), natural cytotoxicity triggering receptor 1 (Nkp46) and the inhibitory marker: NK group 2 member A (NKG2A) in 10 active VKH patients, 20 control subjects (CTR) and seven patients with Behçet disease (BD) by flow cytometry. Cytotoxic potential of NK cells was determined through the degranulation marker CD107a expression after contact with K562 cells by flow cytometry. Moreover, plasmatic levels of 27 cytokines were determined with a multiplex bead-based assay. VKH patients showed higher percentages of NKG2D^pos NK and NK T cells versus CTR. The cytotoxic potential of NK cells induced by K562 cells was comparable between VKH patients and CTR. Finally, higher concentrations of interleukin (IL)-4, IL-5, IL-7, IL-17 and platelet-derived growth factor-subunits B (PDGF-bb) were detected in plasma of VKH patients versus CTR. The immune profile of VKH patients was similar to that of BD patients.

Assessment of NK Cell Activity Based on NK Cell-Specific Receptor Synergy in Peripheral Blood Mononuclear Cells and Whole Blood

Natural killer (NK) cells are cytotoxic innate lymphocytes endowed with a unique ability to kill a broad spectrum of cancer and virus-infected cells. Given their key contribution to diverse diseases, the measurement of NK cell activity (NKA) has been used to estimate disease prognosis or the effect of therapeutic treatment. Currently, NKA assays are primarily based on cumbersome procedures related to careful labeling and handling of target cells and/or NK cells, and they require a rapid isolation of peripheral blood mononuclear cells (PBMCs) which often necessitates a large amount of blood. Here, we developed an ELISA-based whole blood (WB) NKA assay involving engineered target cells (P815-ULBP1+CD48) providing defined and synergistic stimulation for NK cells via NKG2D and 2B4. WB collected from healthy donors (HDs) and patients with multiple myeloma (MM) was stimulated with P815-ULBP1+CD48 cells combined with IL-2. Thereafter, it utilized the serum concentrations of granzyme B and IFN-γ originating in NK cells as independent and complementary indicators of NKA. This WB NKA assay demonstrated that MM patients exhibit a significantly lower NKA than HDs following stimulation with P815-ULBP1+CD48 cells and had a good correlation with the commonly used flow cytometry-based PBMC NKA assay. Moreover, the use of P815-ULBP1+CD48 cells in relation to assessing the levels of NKG2D and 2B4 receptors on NK cells facilitated the mechanistic study and led to the identification of TGF-β1 as a potential mediator of compromised NKA in MM. Thus, our proposed WB NKA assay facilitates the reliable measurement of NKA and holds promise for further development as both a clinical and research tool.

The potential markers of NK-92 associated to cytotoxicity against K562 cells

Markers associated to NK cytolytic activity are in a great need to regulate NK cell immunotherapy products. We assume that biomarkers which response to cytolysis will change their transcription, expression or secretion. To find NK-92 indicator to cytolytic activity, we have evaluated the potential markers by quantifying the expression of well-known cytotoxicity functional molecules (cytokine IFN-γ, Granzyme B, perforin, CD69 and CD107a), and explored candidate markers by a sweeping transcription picture of NK-92 using a direct cytolysis model (incubation with K562). We found that IFN-γ secretion was highly correlated to cytotoxicity of NK-92, neither Granzyme B, perforin secretion, nor CD69, CD107a positive population were upregulated by K562 stimulation. RNAseq revealed 432 genes expression changed during cytolysis, several genes (BIRC3, CSF2, VCAM1 and TNFRSF9) mRNA expression were validated by real time RT-PCR under K562 being killed or protected from being killed conditions. Results suggested IFN-γ secretion, BIRC3 and TNFRSF9 transcription in NK-92 were responsive to K562 cytolysis. In a word, our results confirmed one marker and reveal an array of novel candidate markers associated with NK-92 cytotoxicity. Further studies are greatly needed to determine the roles these new makers play in NK-92 cytolysis process.

Depletion of NK cells attenuates paraquat-induced acute lung injury by manipulating macrophage polarization

Acute lung injury is the main causative factor in paraquat dichloride (PQ)-induced mortality. The innate immune system-triggered detrimental inflammatory cascade plays a vital role in PQ-induced acute lung injury. However, the role of natural killer (NK) cells, which are essential for innate response, in PQ-induced acute lung injury remains largely unknown. Here, we found that in an acute PQ poisoning model, depletion of NK cells attenuated PQ-induced lung injury by inhibiting macrophage polarization towards the M1 type. Specifically, the percentages of NK cells were reduced in the lung, spleen, and peripheral blood in a murine model of acute PQ poisoning. NK cells were aberrantly activated, evidenced by upregulation of the activating markers CD69, CD107a, and NKG2D and downregulation of the inhibitive marker KLRG1. Further, NK-specific depletion in mice greatly prolonged the survival time and ameliorated reactive oxygen species-induced damage following PQ treatment compared with the control group. Importantly, NK cell depletion alleviated macrophage and neutrophil infiltration in the lung and reversed PQ induced-macrophage polarization towards the pro-inflammatory M1 type. Our study demonstrates a crucial role of NK cells and NK cell-to-macrophage interaction in PQ-induced acute lung injury.

A Flow Cytometry-Based Whole Blood Natural Killer Cell Cytotoxicity Assay Using Overnight Cytokine Activation

Background: Measurement of natural killer (NK) cell function has important clinical utility in several diseases. Although the flow cytometry (FC)-based 4-h NK cytotoxicity assay using peripheral blood mononuclear cells (PBMCs) in the clinical laboratory has been used for this purpose, this assay requires large amounts of blood and a rapid PBMC isolation step. Here, we developed an FC-based overnight NK cytotoxicity assay using whole blood (WB), and applied it to patients with liver diseases.

Methods: Peripheral blood of healthy volunteers (n = 28) and patients with liver diseases, including hepatocellular carcinoma (n = 19) and liver cirrhosis (n = 7), was analyzed for complete blood count, absolute NK cell count, and NK cell activity (NKA). NKA was evaluated in three assay types: an FC-based overnight WB NK cytotoxicity assay using carboxyfluorescein diacetate succinimidyl ester-labeled K562 cells in the presence of various cytokine combinations [including interleukin (IL)-2, IL-18, and IL-21], an FC-based 4-h PBMC NK cytotoxicity assay, and an FC-based CD107a degranulation assay using WB and PBMCs.

Results: Optimal cytokine combinations for NK cell activation in WB were determined (IL-2/IL-18, IL-2/IL-21, and IL-2/IL-18/IL-21). A good correlation was observed between WB and PBMC NK cytotoxicity assays; absolute NK cell counts were better correlated with the WB NK cytotoxicity assay than with the PBMC NK cytotoxicity assay. This WB NK cytotoxicity assay showed that patients with liver diseases had significantly lower NK cytotoxicity than healthy volunteers, under stimulation with various cytokines (p < 0.001).

Conclusion: The proposed FC-based overnight WB NK cytotoxicity assay correlates well with the conventional 4-h PBMC NK cytotoxicity assay, demonstrating future potential as a supportive assay for clinical laboratory research and observational studies.

Establishing immune scoring model based on combination of the number, function, and phenotype of lymphocytes

Background: Quantitatively assessing host immunity remains a challenge in clinical practice.

Results: Most parameters in lymphocyte number, function and phenotype were correlated with age. The reference ranges of these parameters were established in four age groups (children, adolescents, adults, and elders). The numbers of CD4⁺ T cells, CD8⁺ T cells, B cells, but not NK cells, were negatively correlated with age. However, the function of CD4⁺ T cells, CD8⁺ T cells and NK cells was positively correlated with age. The expression of CD28 on T cells gradually decreased with increasing age and was negatively correlated with their function. An opposite phenomenon was observed in the expressions of HLA-DR and CD45RO on T cells. An immune scoring model was established by using 8 parameters (CD4⁺ T cell number × function, CD28⁺CD4⁺ T cell number, HLA-DR⁺CD4⁺ T cell number, CD45RO⁺CD4⁺ T cell number, CD8⁺ T cell number × function, CD28⁺CD8⁺ T cell number, HLA-DR⁺CD8⁺ T cell number, NK cell number × function) from the results of lymphocyte number, function, and phenotype. This immune scoring model showed sensitivities of 70% and 71.4% in determining hyper-immune and hypo-immune status, respectively.

Conclusions: An immune scoring model based on combination of lymphocyte number, function, and phenotype shows potential value in quantitatively assessing host immunity.

Methods: 261 healthy individuals aged 1 to 82 years were recruited from Tongji Hospital. The number, function, and phenotype of CD4⁺ T cells, CD8⁺ T cells and NK cells were simultaneously determined.

Phenotypic and Functional Changes in Peripheral Blood Natural Killer Cells in Crohn Disease Patients

We investigated activation status, cytotoxic potential, and gut homing ability of the peripheral blood Natural Killer (NK) cells in Crohn disease (CD) patients. For this purpose, we compared the expression of different activating and inhibitory receptors (KIR and non-KIR) and integrins on NK cells as well as their recent degranulation history between the patients and age-matched healthy controls. The study was conducted using freshly obtained peripheral blood samples from the study participants. Multiple color flow cytometry was used for these determinations. Our results show that NK cells from treatment-naïve CD patients expressed higher levels of activating KIR as well as other non-KIR activating receptors vis-à-vis healthy controls. They also showed increased frequencies of the cells expressing these receptors. The expression of several KIR and non-KIR inhibitory receptors tended to decrease compared with the cells from healthy donors. NK cells from the patients also expressed increased levels of different gut-homing integrin molecules and showed a history of increased recent degranulation events both constitutively and in response to their in vitro stimulation. Furthermore, treatment of the patients tended to reverse these NK cell changes. Our results demonstrate unequivocally, for the first time, that peripheral blood NK cells in treatment-naïve CD patients are more activated and are more poised to migrate to the gut compared to their counterpart cells from healthy individuals. Moreover, they show that treatment of the patients tends to normalize their NK cells. The results suggest that NK cells are very likely to play a role in the immunopathogenesis of Crohn disease.

The mycelium of the Trametes versicolor (Turkey tail) mushroom and its fermented substrate each show potent and complementary immune activating properties in vitro

BACKGROUND

The medicinal mushroom Trametes versicolor (Tv, Turkey Tail) is often prepared for consumption as a powder from the fungal mycelium and the fermented substrate on which it grew. The goal for this study was to evaluate the immune-modulating properties of the mycelium versus the fermented substrate, to document whether an important part of the immune-activating effects resides in the metabolically fermented substrate.

METHODS

Tv mycelium was cultured on rice flour. The mycelium and the fermented substrate were mechanically separated, dried, and milled. The initial substrate served as a control. Aqueous fractions were extracted and passed through 0.22-μm filters. The remaining solids were passed through homogenization spin columns without filtration. The aqueous and solid fractions of the initial substrate (IS), the fermented substrate (FS), and the Trametes versicolor mycelium (TvM) were tested for immune-activating and modulating activities on human peripheral blood mononuclear cell cultures, to examine expression of the CD69 activation marker on lymphocytes versus monocytes, and on the T, NKT, and NK lymphocyte subsets. Culture supernatants were tested for cytokines using Luminex arrays.

RESULTS

Both aqueous and solid fractions of TvM triggered robust induction of CD69 on lymphocytes and monocytes, whereas FS only triggered minor induction of CD69, and IS had no activating effect. The aqueous extract of TvM had stronger activating effects than the solid fraction. In contrast, the solid fraction of IS triggered a reduction in CD69, below levels on untreated cells. Both aqueous and solid fractions of FS triggered large and dose-dependent increases in immune-activating pro-inflammatory cytokines (IL-2, IL-6), anti-inflammatory cytokines Interleukin-1 receptor antagonist (IL-1ra) and Interleukin-10 (IL-10), anti-viral cytokines interferon-gamma (IFN-γ) and Macrophage Inflammatory Protein-alpha (MIP-1α), as well as Granulocyte-Colony Stimulating Factor (G-CSF) and Interleukin-8 (IL-8). TvM triggered more modest cytokine increases. The aqueous extract of IS showed no effects, whereas the solid fraction showed modest effects on induction of cytokines and growth factors.

CONCLUSION

The results demonstrated that the immune-activating bioactivity of a mycelial-based medicinal mushroom preparation is a combination of the mycelium itself (including insoluble beta-glucans, and also water-soluble components), and the highly bioactive, metabolically fermented substrate, not present in the initial substrate.

Enumeration of peripheral blood NKp46 positive NK lymphocytes reflects NK cytotoxic activity in vitro

Natural killer (NK) cells are the predominant innate lymphocyte subsets that mediate anti-tumor and anti-viral responses. The monitoring of NK cells function is important in various physiological and pathological conditions. Different approaches have been used to directly or indirectly evaluate NK cells activities. The purpose of this study was to investigate the correlation between the number of NK cells and cytotoxic activity of NK cells and to determine whether NKp46⁺NK cells reflect NK cytotoxicity status. In our study, we retrospectively analyzed laboratory data on NK cytotoxicity and NK lymphocyte levels of 4896 infertile women which underwent routine immunology investigation after IVF failures. In healthy women, NKp46 expression was assessed on NK cells (n = 214) and cytotoxicity activity was evaluated with regard to NKp46 expression. We found that despite a significant correlation coefficient (n = 4689, r = 0.447), the correlation with cytotoxicity is maintained only within the zones with a low or high NK cells frequency. NK cells frequency has no significant prognostic value for their cytotoxicity - within the medium NK frequency zone the samples may have any cytotoxicity, both reduced and elevated. However, our data demonstrate that NKp46⁺NK cells frequency correlates with cytotoxicity activity even more significantly than the NK cells frequency (n = 214, r = 0.67 and r = 0.62, respectively) and has significant prognostic value for the abnormal NK cytotoxicity status indications, both low and increased. Our results further support an important role of NKp46 in NK cells killing and afford grounds for using the measurement of the NKp46⁺NK cells frequency as an alternative method for abnormal NK cytotoxicity status indication, which is responsive, simple and reliable.

Delivery of oncolytic vaccinia virus by matched allogeneic stem cells overcomes critical innate and adaptive immune barriers

Background

Previous studies have identified IFNγ as an important early barrier to oncolytic viruses including vaccinia. The existing innate and adaptive immune barriers restricting oncolytic virotherapy, however, can be overcome using autologous or allogeneic mesenchymal stem cells as carrier cells with unique immunosuppressive properties.

Methods

To test the ability of mesenchymal stem cells to overcome innate and adaptive immune barriers and to successfully deliver oncolytic vaccinia virus to tumor cells, we performed flow cytometry and virus plaque assay analysis of ex vivo co-cultures of stem cells infected with vaccinia virus in the presence of peripheral blood mononuclear cells from healthy donors. Comparative analysis was performed to establish statistically significant correlations and to evaluate the effect of stem cells on the activity of key immune cell populations.

Results

Here, we demonstrate that adipose-derived stem cells (ADSCs) have the potential to eradicate resistant tumor cells through a combination of potent virus amplification and sensitization of the tumor cells to virus infection. Moreover, the ADSCs demonstrate ability to function as a virus-amplifying Trojan horse in the presence of both autologous and allogeneic human PBMCs, which can be linked to the intrinsic immunosuppressive properties of stem cells and their unique potential to overcome innate and adaptive immune barriers. The clinical application of ready-to-use ex vivo expanded allogeneic stem cell lines, however, appears significantly restricted by patient-specific allogeneic differences associated with the induction of potent anti-stem cell cytotoxic and IFNγ responses. These allogeneic responses originate from both innate (NK)- and adaptive (T)- immune cells and might compromise therapeutic efficacy through direct elimination of the stem cells or the induction of an anti-viral state, which can block the potential of the Trojan horse to amplify and deliver vaccinia virus to the tumor.

Conclusions

Overall, our findings and data indicate the feasibility to establish simple and informative assays that capture critically important patient-specific differences in the immune responses to the virus and stem cells, which allows for proper patient-stem cell matching and enables the effective use of off-the-shelf allogeneic cell-based delivery platforms, thus providing a more practical and commercially viable alternative to the autologous stem cell approach.

Electronic supplementary material

The online version of this article (10.1186/s12967-019-1829-z) contains supplementary material, which is available to authorized users.

Natural killer cell monitoring in cutaneous melanoma - new dynamic biomarker

Melanoma is responsible for most skin cancer deaths in humans. The immune system plays a major role in regulating tumor cell proliferation by initiating defence responses against tumor aggression. Research on murine cancer models allow for a better understanding of immune response in malignancies, revealing specific changes of the immune status in the presence of tumors. Melanoma resistance to conventional therapies and its high immunogenicity justify the development of new therapies. These features reinforce melanoma as a suitable model for studying antitumor immunity. Recent findings on NK cell activation in cancer patients indicate that several important parameters, such as tumor capacity to modulate the function and phenotype of NK cells, require consideration for the choice of an NK-based therapy. In this study, we investigated T-CD4⁺ and T-CD8⁺ lymphocytes, B lymphocytes and NK cells in peripheral blood and spleen cells suspension from melanoma-bearing mice compared to healthy controls in order to assess the potential for tumor growth-promoting immunosuppression. Our results indicate that in a melanoma-bearing mouse model the percentage of NK cells in spleen is reduced and that their phenotype is different compared to control mouse NK cells.

Ferulated Arabinoxylans and Their Gels: Functional Properties and Potential Application as Antioxidant and Anticancer Agent

In the last years, biomedical research has focused its efforts in the development of new oral delivery systems for the treatment of different diseases. Ferulated arabinoxylans are polysaccharides from cereals that have been gaining attention in the pharmaceutical field due to their prebiotic, antioxidant, and anticancer properties. The antioxidant and anticancer properties of these polysaccharides make them attractive compounds for the treatment of cancer, particularly colon cancer. In addition, ferulated arabinoxylans can form covalent gels through the cross-linking of their ferulic acids. Due to their particular characteristics, ferulated arabinoxylan gels represent an excellent alternative as colon-targeted drug delivery systems. The aim of the present work is to review the physicochemical and functional properties of ferulated arabinoxylans and their gels and to present the future perspectives for potential application as antioxidant and anticancer agents.

Natural Killer Cells from Malignant Pleural Effusion Are Endowed with a Decidual-Like Proangiogenic Polarization

Natural killer (NK) cells are crucial in tumor recognition and eradication, but their activity is impaired in cancer patients, becoming poorly cytotoxic. A particular type of NK cells, from the decidua, has low cytotoxicity and shows proangiogenic functions. We investigated whether NK cells from peripheral blood (PB) and pleural effusions of patients develop decidual-like NK phenotype and whether exposure to IL-2 can restore their killing ability in the presence of pleural fluids. NK cells from pleural effusion of patients with inflammatory conditions (iPE, n = 18), primary tumor (ptPE, n = 18), and metastatic tumor (tmPE, n = 27) acquired the CD56^brightCD16⁻ phenotype. NK cells from both ptPE and tmPE showed increased expression for the CD49a and CD69 decidual-like (dNK) markers and decreased levels of the CD57 maturation marker. NK from all the PE analyzed showed impaired degranulation capability and reduced perforin release. PE-NK cells efficiently responded to IL-2 stimulation in vitro. Addition of TGFβ or cell-free pleural fluid to IL-2 in the culture medium abrogated NK cell CD107a and IFNγ expression even in healthy donors (n = 14) NK. We found that tmPE-NK cells produce VEGF and support the formation of capillary-like structures in endothelial cells. Our results suggest that the PE tumor microenvironment can shape NK cell polarization towards a low cytotoxic, decidual-like, highly proangiogenic phenotype and that IL-2 treatment is not sufficient to limit this process.

Cytotoxic activity and subset populations of peripheral blood natural killer cells in patients with chronic pain

Background

Chronic pain reportedly exerts complex effects on immune function. Natural killer (NK) cells are lymphocytes that play a critical role in cellular and innate immunity. This study examined changes in the subset populations and cytotoxic activity of peripheral blood NK cells in patients with chronic pain.

Methods

Thirty patients with chronic moderate-to-severe pain (group P) and age-matched pain-free subjects (group NoP) were enrolled. Peripheral whole blood was analyzed for the percentage and expression of NK cell surface markers (CD56 and CD16) by flow cytometry. Cytotoxic activity was assayed by evaluating CD69 expression on CD3⁻/CD56⁺NK cells.

Results

The percentage of NK cells among total lymphocytes was not significantly different between groups P and NoP (16.3 ± 9.3 vs. 20.2 ± 10.5%). Likewise, the percentages of two major NK cell subsets, CD56^bright and CD56^dim, were also not significantly different between the two groups. However, the percentage of CD56^bright/CD16⁺ subset, was slightly but significantly increased in group P (1.0 ± 0.9%; P < 0.01) compared with group NoP (0.5 ± 0.6%). The cytotoxicity of NK cells was not different between the two groups, showing similar CD69 expression (P vs. NoP = 29.2 ± 15.2 vs. 32.0 ± 15.0%). These findings were not influenced by pain intensity, opioid use, or disease causing pain in group P.

Conclusions

NK cell cytotoxic activity and major subset populations, with the exception of an increased percentage of the CD56^bright/CD16⁺ subset, are not significantly altered in patients with chronic severe pain.

Inactivated probiotic Bacillus coagulans GBI-30 induces complex immune activating, anti-inflammatory, and regenerative markers in vitro

Objective

The aim of this study was to document the immune activating and anti-inflammatory effects of inactivated probiotic Bacillus coagulans GBI-30, 6086 (Staimune™) cells on human immune cells in vitro.

Methods

In vitro cultures of human peripheral blood mononuclear cells (PBMC) from healthy blood donors were treated with inactivated B. coagulans GBI-30, 6086 cells for 24 hours. After incubation, the PBMC were stained with fluorochrome-labeled monoclonal antibodies for CD3, CD56, and CD69 to monitor cellular activation by flow cytometry. The culture supernatants were tested for cytokine profile using a 27-plex Luminex array, including pro- and anti-inflammatory cytokines, chemokines, and growth factors.

Results

Inactivated B. coagulans GBI-30, 6086 cells induced the CD69 early activation marker on CD3⁺ CD56⁻ T lymphocytes, CD3⁺ CD56⁺ NKT cells, CD3⁻CD56⁺ NK cells, and also some cells within the CD3⁻CD56⁻ non-T non-NK cell subset. Culture supernatants showed robust increases in the immune-activating cytokines IL-1β, IL-6, IL-17A, and TNF-α. IFN-γ levels were increased, along with three chemokines, MCP-1, MIP-1α, and MIP-1β. The two anti-inflammatory cytokines IL-1ra and IL-10 showed increases, as well as the G-CSF growth factor involved in repair and stem cell biology. In contrast, GM-CSF levels showed a mild decrease, showing a highly selective growth factor response.

Conclusion

The inactivated B. coagulans GBI-30, 6086 cells activated human immune cells and altered the production of both immune activating and anti-inflammatory cytokines and chemokines. Of special importance is the novel demonstration of a selective upregulation of the G-CSF growth factor involved in postinjury and postinflammation repair and regeneration. This suggests that important immunogenic cell wall components, such as lipoteichoic acid, are undamaged after the inactivation and retain the complex beneficial biological activities previously demonstrated for the cell walls from live B. coagulans GBI-30, 6086 (GanedenBC30) probiotic bacteria.

PD-1 blockade restores impaired function of ex vivo expanded CD8+ T cells and enhances apoptosis in mismatch repair deficient EpCAM+PD-L1+ cancer cells

BACKGROUND

Adoptive T cell therapy has been proven to be a promising modality for the treatment of cancer patients in recent years. However, the increased expression of inhibitory receptors could negatively regulate the function and persistence of transferred T cells which mediates T cell anergy, exhaustion, and tumor regression. In this study, we investigated increased cytotoxic activity after the blockade of PD-1 for effective immunotherapy.

METHODS

The cytotoxic function of expanded CD8⁺ CTLs and interactions with tumor cells investigated after blocking of PD-1. Ex vivo expanded CD8⁺ CTLs were co-cultured with mismatch repair (MMR) stable or deficient (high microsatellite instability [MSI-H]) EpCAM⁺ tumor cells. The levels of IFN-γ and GrB were detected by enzyme-linked immunosorbent spot assay. Flow cytometry and confocal microscopy were used to assess CD107a mobilization, cytosolic uptake, and cell migration.

RESULTS

A dramatic increase in PD-1 expression on the surface of CD8⁺ CTLs during ex vivo expansion was observed. PD-1 level was downregulated by approximately 40% after incubation of the CD8⁺ CTLs with monoclonal antibody which enhanced the secretion of IFN-γ, GrB, and CD107a. Additionally, PD-1 blockade enhanced cell migration and cytosolic exchange between CD8⁺ CTLs and MMR deficient (MSI-H) EpCAM⁺PD-L1⁺ tumor cells.

CONCLUSION

The blockade of PD-1 enhanced the cytotoxic efficacy of CD8⁺ CTLs toward MMR deficient tumor cells. In conclusion, we propose that blocking of PD-1 during the expansion of CD8⁺ CTLs may improve the clinical efficacy of cell-based adoptive immunotherapy.

UV-inactivated HSV-1 potently activates NK cell killing of leukemic cells

Herein we demonstrate that oncolytic herpes simplex virus-1 (HSV-1) potently activates human peripheral blood mononuclear cells (PBMCs) to lyse leukemic cell lines and primary acute myeloid leukemia samples, but not healthy allogeneic lymphocytes. Intriguingly, we found that UV light-inactivated HSV-1 (UV-HSV-1) is equally effective in promoting PBMC cytolysis of leukemic cells and is 1000- to 10 000-fold more potent at stimulating innate antileukemic responses than UV-inactivated cytomegalovirus, vesicular stomatitis virus, reovirus, or adenovirus. Mechanistically, UV-HSV-1 stimulates PBMC cytolysis of leukemic cells, partly via Toll-like receptor-2/protein kinase C/nuclear factor-κB signaling, and potently stimulates expression of CD69, degranulation, migration, and cytokine production in natural killer (NK) cells, suggesting that surface components of UV-HSV-1 directly activate NK cells. Importantly, UV-HSV-1 synergizes with interleukin-15 (IL-15) and IL-2 in inducing activation and cytolytic activity of NK cells. Additionally, UV-HSV-1 stimulates glycolysis and fatty acid oxidation-dependent oxygen consumption in NK cells, but only glycolysis is required for their enhanced antileukemic activity. Last, we demonstrate that T cell-depleted human PBMCs exposed to UV-HSV-1 provide a survival benefit in a murine xenograft model of human acute myeloid leukemia (AML). Taken together, our results support the preclinical development of UV-HSV-1 as an adjuvant, alone or in combination with IL-15, for allogeneic donor mononuclear cell infusions to treat AML.

1,25-Dihydroxy-vitamin D3 regulates NK-cell cytotoxicity, cytokine secretion, and degranulation in women with recurrent pregnancy losses

Vitamin D has a pivotal role in regulating immune responses by promoting Th2 immune responses and suppressing Th1 responses. Propensities to a Th1 immune response and increased NK-cell levels and cytotoxicity have been reported in women with recurrent pregnancy losses (RPL). In women with RPL, vitamin D deficiency is prevalent; however, the effect of vitamin D on NK cells is largely unknown. In this study, we demonstrated that CD69(+) activating receptor expression on NK cells was significantly decreased by incubation with 1,25(OH)2 D3 in a dose-dependent manner, while CD158a and CD158b inhibitory receptor expression was upregulated. The degranulation marker CD107a was significantly downregulated on NK cells following incubation with 1,25(OH)2 D3 . NK-cell conjugation with K562 target cells was not affected by 1,25(OH)2 D3 ; however, depolarization of perforin granules in conjugated NK cells was significantly increased. TLR4 expression on NK cells was significantly decreased and TNF-α and IFN-γ production was significantly reduced by 1,25(OH)2 D3 through interference with NF-κB. Our results suggest 1,25(OH)2 D3 has immune regulatory effects on NK cell cytotoxicity, cytokine secretion and degranulation process as well as TLR4 expression. Potential therapeutic application of 1,25(OH)2 D3 for dysregulated NK-cell immunity should be explored in the future.

In Vivo Activation of Human NK Cells by Treatment with an Interleukin-15 Superagonist Potently Inhibits Acute In Vivo HIV-1 Infection in Humanized Mice

Natural killer (NK) cells with anti-HIV-1 activity may inhibit HIV-1 replication and dissemination during acute HIV-1 infection. We hypothesized that the capacity of NK cells to suppress acute in vivo HIV-1 infection would be augmented by activating them via treatment with an interleukin-15 (IL-15) superagonist, IL-15 bound to soluble IL-15Rα, an approach that potentiates human NK cell-mediated killing of tumor cells. In vitro stimulation of human NK cells with a recombinant IL-15 superagonist significantly induced their expression of the cytotoxic effector molecules granzyme B and perforin; their degranulation upon exposure to K562 cells, as indicated by cell surface expression of CD107a; and their capacity to lyse K562 cells and HIV-1-infected T cells. The impact of IL-15 superagonist-induced activation of human NK cells on acute in vivo HIV-1 infection was investigated by using hu-spl-PBMC-NSG mice, NOD-SCID-IL2rγ(-/-) (NSG) mice intrasplenically injected with human peripheral blood mononuclear cells (PBMCs) which develop productive in vivo infection after intrasplenic inoculation with HIV-1. IL-15 superagonist treatment potently inhibited acute HIV-1 infection in hu-spl-PBMC-NSG mice even when delayed until 3 days after intrasplenic HIV-1 inoculation. Removal of NK cells from human PBMCs prior to intrasplenic injection into NSG mice completely abrogated IL-15 superagonist-mediated suppression of in vivo HIV-1 infection. Thus, the in vivo activation of NK cells, integral mediators of the innate immune response, by treatment with an IL-15 superagonist increases their anti-HIV activity and enables them to potently suppress acute in vivo HIV-1 infection. These results indicate that in vivo activation of NK cells may represent a new immunotherapeutic approach to suppress acute HIV-1 infection.

IMPORTANCE

Epidemiological studies have indicated that NK cells contribute to the control of HIV-1 infection, and in vitro studies have demonstrated that NK cells can selectively kill HIV-1-infected cells. We demonstrated that in vivo activation of NK cells by treatment with an IL-15 superagonist that potently stimulates the antitumor activity of NK cells markedly inhibited acute HIV-1 infection in humanized mice, even when activation of NK cells by IL-15 superagonist treatment is delayed until 3 days after HIV-1 inoculation. NK cell depletion from PBMCs prior to their intrasplenic injection abrogated the suppression of in vivo HIV-1 infection observed in humanized mice treated with the IL-15 superagonist, demonstrating that activated human NK cells were mediating IL-15 superagonist-induced inhibition of acute HIV-1 infection. Thus, in vivo immunostimulation of NK cells, a promising therapeutic approach for cancer therapy, may represent a new treatment modality for HIV-1-infected individuals, particularly in the earliest stages of infection.

CD107a as a marker of activation in chicken cytotoxic T cells

The study aimed to evaluate cell surface mobilisation of CD107a as a general activation marker on chicken cytotoxic T cells (CTL). Experiments comprised establishment of an in vitro model for activation-induced CD107a mobilisation and design of a marker panel for the detection of CD107a mobilisation on chicken CTL isolated from different tissues. Moreover, CD107a mobilisation was analysed on CTL isolated from airways of infectious bronchitis virus (IBV)-infected birds direct ex vivo and upon in vitro stimulation. Results showed that phorbol 12-myristate 13-acetate (PMA) in combination with ionomycin was a consistent inducer of CD107a cell surface mobilisation on chicken CTL in a 4h cell culture model. In chickens experimentally infected with IBV, higher frequencies of CTL isolated from respiratory tissues were positive for CD107a on the cell surface compared to those from uninfected control chickens indicating in vivo activation. Moreover, upon in vitro PMA+ ionomycin stimulation, higher proportions of CTL isolated from the airways of IBV-infected chickens showed CD107a mobilisation compared to those from uninfected control chickens. Monitoring of CD107a cell surface mobilisation may thus be a useful tool for studies of chicken CTL cytolytic potential both in vivo and in vitro.

Human Amnion-Derived Stem Cells Have Immunosuppressive Properties on NK Cells and Monocytes

Human amnion-derived cells are considered to be a promising alternative cell source for their potential clinical use in tissue engineering and regenerative medicine because of their proliferation and differentiation ability. The cells can easily be obtained from human amnion, offering a potential source without medical intervention. It has been proven that human amnion-derived cells express immunosuppressive factors CD59 and HLA-G, implying that they may have an immunosuppressive function. To assess the immunosuppressive activity, we investigated the effect of human amnion-derived cells on NK cell and monocyte function. Amnion-derived cells inhibited the cytotoxicity of NK cells to K562 cells. The inhibition depended on the NK/amnion-derived cell ratio. The inhibition of NK cytotoxicity was recovered by continuous culturing without amnion-derived cells. The inhibition of NK cytotoxicity was related to the downregulation of the expression of the activated NK receptors and the production of IFN-γ, as well as the upregulation of the expression of IL-10 and PGE2 in human amnion-derived cells. The addition of antibody to IL-10 or PGE2 inhibitor tended to increase NK cytotoxicity. IL-10 and PGE2 might be involved in the immunosuppressive activity of amniotic cells toward NK cells. Amniotic cells also suppressed the activity of cytokine production in monocytes analyzed with TNF-α and IL-6. These data suggested that amniotic cells have immunosuppressive activity.

N6-isopentenyladenosine affects cytotoxic activity and cytokines production by IL-2 activated NK cells and exerts topical anti-inflammatory activity in mice

N6-isopentenyladenosine (iPA) is a modified adenosine with an isopentenyl moiety derived from the mevalonate pathway which displays pleiotropic biological effects, including anti-tumor and anti-angiogenic activity. Previous evidence revealed a biphasic effect of iPA on phytohemagglutinin-stimulated lymphocytes, being pro-proliferative at low doses and anti-proliferative at high doses. Analogously, we have recently shown that low iPA concentrations (<1μM) increased the immune response of natural killer (NK) cells against cancer targets. In the present study, we evaluated the effect of iPA at high concentration (10μM) on IL-2-activated NK cells. iPA, inhibited NK cell proliferation and cytotoxicity against their conventional tumor target, human K562 cells. This inhibition was associated with decreased expression and functionality of NK cell activating receptors NKp44 and NKG2D as well as impaired cyto/chemokines secretion (RANTES, MIP-1α, TNF-α and IFN-γ). ERK/MAPK and STAT5 activation in IL-2-activated NK cells were inhibited by iPA. The results obtained in vitro were validated in vivo in the inflammatory murine model of croton oil-induced ear dermatitis. The topical application of iPA significantly reduced mouse ear oedema, thus suggesting anti-inflammatory properties of this molecule. These results show the ability of iPA to exert anti-inflammatory effects both in vitro and in vivo directly targeting NK cells, providing a novel pharmacological tool in those diseases characterized by a deregulated immune-response, such as cancer or inflammatory conditions.

Frequent participation in high volume exercise throughout life is associated with a more differentiated adaptive immune response

Exercise induces changes in the immune system depending on its intensity and duration. For example, transient states of immunodepression can be induced after acute intense physical activity whereas beneficial anti-inflammatory effects of moderate chronic exercise on many diseases and longevity have been described. To study the impact of high volume exercise over a lifetime on aspects of immunity we compared immunological features of 27 young and 12 elderly athletes with 30 young and 26 elderly non-athletes stratified by their CMV serostatus. We characterized blood leukocyte and lymphocyte subpopulations by flow cytometry, quantified TREC content, and measured activation and proliferation ability of T-lymphocytes in the presence of anti-CD3. NK-cells functionality was determined in response to K-562, 721.221 and 721.221-AEH cell-lines. High volume physical activity reduced the total number of circulating leukocytes, neutrophils, and lymphocytes. In the lymphocyte compartment, athletes had higher frequencies of NK-cells and CD8+ T-lymphocytes, whereas CD4+ T-lymphocytes were present at significantly lower levels in CMV-seropositive athletes. We found, in the high volume physical activity individuals, a higher degree of differentiation in CD4+ T-lymphocytes. CD8+ T-lymphocytes from young athletes had reduced TREC content and lower frequencies of recent thymic emigrants. Furthermore, the functional ability of CD4+ and CD8+ T-lymphocytes was significantly impaired in young but not in elderly athletes, and may be compensated for significantly higher activation and degranulation of NK-cells. In conclusion, high volume exercise throughout life appears to be associated with increased levels of biomarkers that are associated with an aging immune system, which are partially reduced with physiological aging.

Cord blood CD4(+)CD25(+) regulatory T cells fail to inhibit cord blood NK cell functions due to insufficient production and expression of TGF-beta1

Although CD4(+)CD25(+) Treg (Treg) cells are known to modulate NK cell functions, the modulation mechanism of these cells in cord blood has not been fully clarified. The purpose of this study was to clarify the mechanism whereby cord blood Treg cells modulate cord NK cells. By performing various cultures of purified NK cells with or without autologous Treg cells, diminished inhibitory effects of cord Treg cells towards cord NK cell functions, including activation, cytokine production, and cytotoxicity, were observed. We also observed lower secretion of sTGF-beta1 and lower expression of mTGF-beta1 by cord Treg cells than by adult Treg cells. These data revealed the capability of adult Treg cells to suppress rhIL-2-stimulated NK cell function by TGF-beta1, both membrane-bound and soluble types. The reduced inhibitory capabilities of cord Treg cells compared with adult Treg cells is thought to be due to insufficient expression of TGF-beta1.

Differential expression of natural killer activating and inhibitory receptors in patients with newly diagnosed systemic lupus erythematosus

AIM

Systemic lupus erythematosus (SLE) presents as the abnormal activation and over-proliferation of immune competent cells. Few studies have characterized the role of natural killer (NK) and NK T (NKT) cells in the pathogenesis of SLE, and therefore a consensus has not been reached as yet.

METHOD

Thirty-two patients with new-onset SLE and 15 healthy controls were recruited. Activated and inhibitory NK and NKT cells in peripheral blood were quantified by flow cytometry. The proportions of spontaneous and stimulated interferon (IFN)-γ(+) NK and NKT cells and CD107a(+) NK cells was examined. Finally, the potential relationship between the cell subsets and clinical indexes was analyzed.

RESULTS

The proportions of NK and NKT cells (P = 0.002 and 0.004, respectively) as well as the proportions of NKG2C(+) NK cells, inhibitory NK and NKT cell subsets (P = 0.016, P = 0.019, P = 0.049, and P = 0.028, respectively) in SLE patients were significantly lower than those in controls. In contrast, the proportions of activated NK cells and NKT cell subsets were significantly higher (P = 0.036, P = 0.034, P = 0.005, and P = 0.007, respectively). Moreover, the proportions of stimulated IFN-γ(+) NKT cells were significantly higher than in the controls, and the proportions of stimulated CD107a(+) NKT cells in SLE patients were significantly lower than in the controls (P = 0.032 and P = 0.02, respectively).

CONCLUSION

Lower proportions of NK and NKT cells, higher proportions of activated NK cells and activated NKT cells, lower proportions of inhibitory NK and NKT cells, higher NKT cell activity, and lower NKT cell degranulation may induce the autoimmune reaction involved in the pathogenesis of SLE.

Evaluation of NK cell function by flowcytometric measurement and impedance based assay using real-time cell electronic sensing system

Although real-time cell electronic sensing (RT-CES) system-based natural killer (NK) cytotoxicity has been introduced, it has not been evaluated using human blood samples. In present study, we measured flowcytometry based assay (FCA) and RT-CES based NK cytotoxicity and analyzed degranulation activity (CD107a) and cytokine production. In 98 healthy individuals, FCA with peripheral blood mononuclear cells (PBMCs) at effector to target (E/T) ratio of 32 revealed 46.5 ± 2.6% cytolysis of K562 cells, and 23.5 ± 1.1% of NK cells showed increased degranulation. In RT-CES system, adherent NIH3T3 target cells were resistant to basal killing by PBMC or NK cells. NK cell activation by adding IL-2 demonstrated real-time dynamic killing activity, and lymphokine-activated PBMC (E/T ratio of 32) from 15 individuals showed 59.1 ± 6.2% cytotoxicity results after 4 hours incubation in RT-CES system. However, there was no significant correlation between FCA and RT-CES cytotoxicity. After K562 target cell stimulation, PBMC produced profound proinflammatory and immunoregulatory cytokines/chemokines including IL-2, IL-8, IL-10, MIP-1 α β , IFN- γ , and TNF- α , and cytokine/chemokine secretion was related to flowcytometry-based NK cytotoxicity. These data suggest that RT-CES and FCA differ in sensitivity, applicability and providing information, and further investigations are necessary in variable clinical conditions.

CD69+NK cells contribute to the murine hepatitis virus strain 3-induced murine hepatitis

The role of hepatic CD69+ natural killer (NK) cells in virus-induced severe liver injury and subsequent hepatic failure is not well defined. In this study, a mouse model of fulminant liver failure (FHF) induced by murine hepatitis virus strain 3 (MHV-3) was used to study the role of hepatic CD69+NK cells in the development of FHF. The CD69 expression in NK cells in the liver, spleen, bone marrow and peripheral blood was detected by using flow cytometry. The correlation between the CD69 level in hepatic NK cells and liver injury was studied. The functional marker (CD107a), and activating and inhibitory receptor (NKG2D and NKG2A) expressed on CD69+NK cells and CD69-NK cells were detected by using flow cytometry. Pro-inflammatory cytokines (IL-9, IFN-γ and TNF-α) were also examined by using intracellular staining. After MHV-3 infection, the number of CD69+NK cells in the liver of BALB/cJ mice was increased markedly and peaked at 72 h post-infection. Similar changes were also observed in the spleen, bone marrow and peripheral blood. Meanwhile, the CD69 expression in hepatic NK cells was highly correlated with the serum level of ALT and AST. The expression of CD107a and NKG2D, as well as the production of TNF-α, IFN-γ and IL-9 in hepatic CD69+NK cells was all significantly up-regulated during 48-72 h post-infection. In contrast, the NKG2A expression was increased in hepatic CD69-NK cells but not in CD69+NK cells. These results suggested that hepatic CD69+NK cells play a pivotal role in the pathogenesis of FHF by enhancing degranulation and cytotoxic ability of NK cells and increasing the production of pro-inflammatory cytokines.

NK cells exacerbate the pathology of influenza virus infection in mice

NK cells offer a first line of defense against viruses and are considered beneficial to the host during infection. Nevertheless, little is understood regarding the phenotype and function of NK cells in the lung during influenza virus infection. We found that the frequency of NK cells in mouse lung increased during influenza infection, with the majority of a mature phenotype. Cell surface CD107a and intracellular IFN-γ were detected in cells expressing multiple NK-cell receptors in infected lung, suggesting that NK cells were activated during infection. The activating receptor NKp46 was predominantly negative on such cells, possibly as a result of encountering influenza HA. Depletion of NK cells in vivo with anti-asialo GM1 or anti-NK1.1 reduced mortality from influenza infection and surviving mice recovered their body weight. Pathology induced by NK cells was only observed with high, not medium or low-dose influenza infection, indicating that the severity of infection influences NK-cell-mediated pathology. Furthermore, adoptive transfer of NK cells from influenza-infected lung, but not uninfected lung, resulted in more rapid weight loss and increased mortality of influenza-infected mice. Our results indicate that during severe influenza infection of the lung, NK cells have a deleterious impact on the host, promoting mortality.