Natural killer cells regulate diverse T cell responses

Harnessing natural killer cells for refractory/relapsed non-Hodgkin lymphoma: biological roles, clinical trials, and future prospective

Non-Hodgkin lymphomas (NHLs) are heterogeneous and are among the most common hematological malignancies worldwide. Despite the advances in the treatment of patients with NHLs, relapse or resistance to treatment is anticipated in several patients. Therefore, novel therapeutic approaches are needed. Recently, natural killer (NK) cell-based immunotherapy alone or in combination with monoclonal antibodies, chimeric antigen receptors, or bispecific killer engagers have been applied in many investigations for NHL treatment. The functional defects of NK cells and the ability of cancerous cells to escape NK cell-mediated cytotoxicity within the tumor microenvironment of NHLs, as well as the beneficial results from previous studies in the context of NK cell-based immunotherapy in NHLs, direct our attention to this therapeutic strategy. This review aims to summarize clinical studies focusing on the applications of NK cells in the immunotherapy of patients with NHL.

NKp44/HLA-DP-dependent regulation of CD8 effector T cells by NK cells

Although natural killer (NK) cells are recognized for their modulation of immune responses, the mechanisms by which human NK cells mediate immune regulation are unclear. Here, we report that expression of human leukocyte antigen (HLA)-DP, a ligand for the activating NK cell receptor NKp44, is significantly upregulated on CD8+ effector T cells, in particular in human cytomegalovirus (HCMV)+ individuals. HLA-DP+ CD8+ T cells expressing NKp44-binding HLA-DP antigens activate NKp44+ NK cells, while HLA-DP+ CD8+ T cells not expressing NKp44-binding HLA-DP antigens do not. In line with this, frequencies of HLA-DP+ CD8+ T cells are increased in individuals not encoding for NKp44-binding HLA-DP haplotypes, and contain hyper-expanded CD8+ T cell clones, compared to individuals expressing NKp44-binding HLA-DP molecules. These findings identify a molecular interaction facilitating the HLA-DP haplotype-specific editing of HLA-DP+ CD8+ T cell effector populations by NKp44+ NK cells and preventing the generation of hyper-expanded T cell clones, which have been suggested to have increased potential for autoimmunity.

Single-cell transcriptome analysis of aging mouse liver

Aging has a great impact on the liver, which causes a loss of physiological integrity and an increase in susceptibility to injury, but many of the underlying molecular and cellular processes remain unclear. Here, we performed a comprehensive single-cell transcriptional profiling of the liver during aging. Our data showed that aging affected the cellular composition of the liver. The increase in inflammatory cells including neutrophils and monocyte-derived macrophages, as well as in inflammatory cytokines, could indicate an inflammatory tissue microenvironment in aged livers. Moreover, aging drove a distinct transcriptional course in each cell type. The commonly significant up-regulated genes were S100a8, S100a9, and RNA-binding motif protein 3 across all cell types. Aging-related pathways such as biosynthesis, metabolism, and oxidative stress were up-regulated in aged livers. Additionally, key ligand-receptor pairs for intercellular communication, primarily linked to macrophage migration inhibitory factor, transforming growth factor-β, and complement signaling, were also elevated. Furthermore, hepatic stellate cells (HSCs) serve as the prominent hub for intrahepatic signaling. HSCs acquired an "activated" phenotype, which may be involved in the increased intrahepatic vascular tone and fibrosis with aging. Liver sinusoidal endothelial cells derived from aged livers were pseudocapillarized and procontractile, and exhibited down-regulation of genes involved in vascular development and homeostasis. Moreover, the aging-related changes in cellular composition and gene expression were reversed by caloric restriction. Collectively, the present study suggests liver aging is linked to a significant liver sinusoidal deregulation and a moderate pro-inflammatory state, providing a potential concept for understanding the mechanism of liver aging.

Exploring the genetic factors behind the discrepancy in resistance to bovine tuberculosis between African zebu cattle and European taurine cattle

Caused by the pathogenic agent Mycobacterium bovis, bovine tuberculosis (bTB) is a major concern in cattle breeding due to both its zoonotic potential and economic impact. Greater resistance to this disease has been reported in certain African zebu breeds compared to European taurine breeds. However the genetic basis for the lower susceptibility to bTB infection observed in zebu cattle remains poorly explored. This study was conducted on whole genome sequencing data of three bTB infection-resistant African zebu breeds and two bTB infection-susceptible taurine breeds to decipher the genetic background. A set of four selection signature statistics based on linkage disequilibrium, site frequency spectrum, and population differentiation were used on SNPs whereas between population variance based VST and t-test were used on CNVs. As a complement, genes from previous literature reported as candidate genes for bTB resistance were also inspected to identify genetic variations. Interestingly, the resulting nine candidate genes had deleterious missense variants (SHC3, IFNGR1, TLR2, TLR6, IL1A, LRRK2, EP300 and IRAK4) or a CNV difference (CD48) segregating between the groups. The genes found in the study play a role in immune pathways activated during Mycobacterium infection, contributing to the proliferation of immune cells and the granuloma formation, ultimately modulating the outcome of the infectious event. In particular, a deleterious variant in the LRRK2 gene, whose deficiency has been linked to improved prognosis upon tuberculosis infection, was found in the bTB infection-resistant zebu breeds. Therefore, these genes constitute credible candidates in explaining the discrepancy in Mycobacterium bovis infection susceptibility among different breed.

Gut-microbiota prompt activation of natural killer cell on alcoholic liver disease

The liver is rich in innate immune cells, such as natural killer (NK) cells, natural killer T cells, and Kupffer cells associated with the gut microbiome. These immune cells are dysfunctional owing to alcohol consumption. However, there is insufficient data on the association between immune cells and gut microbiome in alcoholic liver disease (ALD). Therefore, the purpose of this study was to evaluate the effects of probiotic strains on NK cells in ALD patients. In total, 125 human blood samples [control (n = 22), alcoholic hepatitis (n = 43), and alcoholic cirrhosis (n = 60]) were collected for flow cytometric analysis. C57BL/6J mice were divided into four groups (normal, EtOH-fed, and 2 EtOH+strain groups [Phocaeicola dorei and Lactobacillus helveticus]). Lymphocytes isolated from mouse livers were analyzed using flow cytometry. The frequency of NK cells increased in patients with alcoholic hepatitis and decreased in patients with alcoholic cirrhosis. The expression of NKp46, an NK cell-activating receptor, was decreased in patients with alcoholic hepatitis and increased in patients with alcoholic cirrhosis compared to that in the control group. The number of cytotoxic CD56dimCD16+ NK cells was significantly reduced in patients with alcoholic cirrhosis. We tested the effect of oral administration P. dorei and L. helveticus in EtOH-fed mice. P. dorei and L. helveticus improved liver inflammation and intestinal barrier damage caused by EtOH supply and increased NK cell activity. Therefore, these observations suggest that the gut microbiome may ameliorate ALD by regulating immune cells.

Surface plasmon resonance and microscale thermophoresis approaches for determining the affinity of perforin for calcium ions

Perforin is a pore-forming protein that plays a crucial role in the immune system by clearing virus-infected or tumor cells. It is released from cytotoxic granules of immune cells and forms pores in targeted lipid membranes to deliver apoptosis-inducing granzymes. It is a very cytotoxic protein and is therefore adapted not to act in producing cells. Its activity is regulated by the requirement for calcium ions for optimal activity. However, the exact affinity of perforin for calcium ions has not yet been determined. We conducted a molecular dynamics simulation in the absence or presence of calcium ions that showed that binding of at least three calcium ions is required for stable perforin binding to the lipid membrane. Biophysical studies using surface plasmon resonance and microscale thermophoresis were then performed to estimate the binding affinities of native human and recombinant mouse perforin for calcium ions. Both approaches showed that mouse perforin has a several fold higher affinity for calcium ions than that of human perforin. This was attributed to a particular residue, tryptophan at position 488 in mouse perforin, which is replaced by arginine in human perforin. This represents an additional mechanism to control the activity of human perforin.

Murine cytomegalovirus downregulates ERAAP and induces an unconventional T cell response to self

The endoplasmic reticulum aminopeptidase associated with antigen processing (ERAAP) plays a crucial role in shaping the peptide-major histocompatibility complex (MHC) class I repertoire and maintaining immune surveillance. While murine cytomegalovirus (MCMV) has multiple strategies for manipulating the antigen processing pathway to evade immune responses, the host has also developed ways to counter viral immune evasion. In this study, we find that MCMV modulates ERAAP and induces an interferon γ (IFN-γ)-producing CD8+ T cell effector response that targets uninfected ERAAP-deficient cells. We observe that ERAAP downregulation during infection leads to the presentation of the self-peptide FL9 on non-classical Qa-1b, thereby eliciting Qa-1b-restricted QFL T cells to proliferate in the liver and spleen of infected mice. QFL T cells upregulate effector markers upon MCMV infection and are sufficient to reduce viral load after transfer to immunodeficient mice. Our study highlights the consequences of ERAAP dysfunction during viral infection and provides potential targets for anti-viral therapies.

Assessment of the risk of unexplained recurrent spontaneous abortion based on the proportion and correlation of NK cells and T cells in peripheral blood

BACKGROUND

Unexplained recurrent spontaneous abortion (URSA) is difficult to diagnose and treat clinically due to its unknown causeOBJECTIVE: Changes in natural killer (NK) cells, T lymphocytes, and Th1(IFNγ)/Th2(IL-4) cytokines were investigated in the peripheral blood of patients with URSA to examine the pathogenesis, clinical diagnosis, and inform potential treatment strategies for this condition.

METHODS

For this study, we selected patients with URSA as the case group and included normal women in the control group. Flow cytometry was performed to detect lymphocytes and cytokines in the peripheral blood of all subjects.

RESULTS

The proportion of NK cells, Th1 cells, and the Th1/Th2 ratio were significantly higher in the URSA group compared to the control group; whereas the proportion of CD3+T cells was lower. Pairwise correlation analysis revealed a positive correlation between the percentage of NK cells and CD3+T cells, as well as CD3+CD4+T cells. Canonical correlation analysis indicated a significant correlation between NK cells and T cells, including their subgroups.

CONCLUSION

Patients with URSA have immune balance disorders, characterised by an increased proportion of peripheral blood NK cells, Th1, and Th1/Th2 ratio along with a decreased proportion of CD3+T cells. The proportion of NK cells and CD3+T may serve as predictive factors for URSA, while NK cells are closely related to the regulation of CD3+T cells and their subsets. By regulating the level of IFN-γ, NK cells can influence the proportion of CD3+T cells and induce a Th1 (IFNγ)/Th2 (IL-4) imbalance.

Regulation of Cytotoxic Immune Effector Function by AJ3 Probiotic Bacteria in Amyotrophic Lateral Sclerosis (ALS)

Our recent studies indicated that amyotrophic lateral sclerosis (ALS) patients suffer from significantly elevated levels of interferon-gamma (IFN-γ) secretion by natural killer (NK) and CD8+ T cells, which may be responsible for the immune-pathologies seen in central nervous system and in peripheral organs of the patients. In order to counter such elevated induction of IFN-γ in patients we designed a treatment strategy to increase anti-inflammatory cytokine interleukin-10 (IL-10) by the use of probiotic strains which significantly increase the levels of IL-10. Therefore, in this paper we demonstrate disease specific functions of Al-Pro (AJ3) formulated for the adjunct treatment of auto-immune diseases including ALS, and compared the function with CA/I-Pro (AJ4) for the treatment of cancer and viral diseases, and NK-CLK (AJ2) for maintenance of immune balance and promotion of disease prevention. The three different formulations of probiotic bacteria have distinct profiles of activation of peripheral blood mononuclear cells (PBMCs), NK, and CD8+ T cells, and their induced activation is different from those mediated by either IL-2 or IL-2 + anti-CD16 monoclonal antibodies (mAbs) or IL-2 + anti-CD3/CD28 mAbs. IL-2 + anti-CD16 mAb activation of PBMCs and NK cells had the highest IFN-γ/IL-10 ratio, whereas IL-2 combination with sAJ4 had the next highest followed by IL-2 + sAJ2 and the lowest was seen with IL-2 + sAJ3. Accordingly, the highest secretion of IFN-γ was seen when the PBMCs and NK cells were treated with IL-2 + sAJ4, intermediate for IL-2 + sAJ2 and the lowest with IL-2 + sAJ3. The levels of IFN-γ induction and the ratio of IFN-γ to IL-10 induced by different probiotic bacteria formulation in the absence of IL-2 treatment remained much lower when compared to those treated in the presence of IL-2. Of note is the difference between NK cells and CD8+ T cells in which synergistic induction of IFN-y by IL-2 + sAJ4 was significantly higher in NK cells than those seen by CD8+ T cells. Based on these results, sAJ3 should be effective in alleviating auto-immunity seen in ALS since it will greatly regulate the levels and function of IFN-γ negatively, decreasing overactivation of cytotoxic immune effectors and prevention of death in motor neurons.

Anticancer traits of chimeric antigen receptors (CARs)-Natural Killer (NK) cells as novel approaches for melanoma treatment

Owing to non-responsiveness of a high number of patients to the common melanoma therapies, seeking novel approaches seem as an unmet requirement. Chimeric antigen receptor (CAR) T cells were initially employed against recurrent or refractory B cell malignancies. However, advanced stages or pretreated patients have insufficient T cells (lymphopenia) amount for collection and clinical application. Additionally, this process is time-consuming and logistically cumbersome. Another limitation of this approach is toxicity and cytokine release syndrome (CRS) progress and neurotoxicity syndrome (NS). Natural killer (NK) cells are a versatile component of the innate immunity and have several advantages over T cells in the application for therapies such as availability, unique biological features, safety profile, cost effectiveness and higher tissue residence. Additionally, CAR NK cells do not develop Graft-versus-host disease (GvHD) and are independent of host HLA genotype. Notably, the NK cells number and activity is affected in the tumor microenvironment (TME), paving the way for developing novel approaches by enhancing their maturation and functionality. The CAR NK cells short lifespan is a double edge sword declining toxicity and reducing their persistence. Bispecific and Trispecific Killer Cell Engagers (BiKE and Trike, respectively) are emerging and promising immunotherapies for efficient antibody dependent cell cytotoxicity (ADCC). CAR NK cells have some limitations in terms of expanding and transducing NK cells from donors to achieve clinical response. Clinical trials are in scarcity regarding the CAR NK cell-based cancer therapies. The CAR NK cells short life span following irradiation before infusion limits their efficiency inhibiting their in vivo expansion. The CAR NK cells efficacy enhancement in terms of lifespan TME preparation and stability is a goal for melanoma treatment. Combination therapies using CAR NK cells and chemotherapy can also overcome therapy limitations.

Natural Killer Cells Induce CD8+ T Cell Dysfunction via Galectin-9/TIM-3 in Chronic Hepatitis B Virus Infection

The antiviral response of natural killer (NK) cells and CD8⁺ T cells is weak in patients with chronic hepatitis B (CHB) infection. However, the specific characteristics of these cells and the association between NK cells and CD8⁺ T cell dysfunction is not well known. In this study, higher galectin-9 (Gal-9) expression was observed in circulating NK cells from CHB patients than from healthy controls and was found to contribute to NK cell dysfunction. In addition, circulating CD8⁺ T cells showed obvious dysfunction and overexpressed TIM-3, the natural receptor of Gal-9, during active CHB infection. Gal-9⁺ and Gal-9^- NK cells from active CHB patients were sorted and cocultured with autologous CD8⁺ T cells. The proportion of tetramer⁺CD8⁺ T cells and the cytokines production of CD8⁺ T cells were lower after cocultivation with Gal-9⁺ than with Gal-9^- NK cells. We showed that in vitro depletion of NK cells increased circulating hepatitis B virus (HBV)-specific CD8⁺ T cell responses in patients with active CHB infection. Because Gal-9 is increased in the serum of CHB patients, CD8⁺ T cells were sorted and cultured with exogenous Gal-9, resulting in lower IFN-γ, TNF-α, CD107a, and granzyme B levels, decreased expression of the activation receptor CD69, increased expression of TIM-3, and a high percentage of early apoptotic CD8⁺ T cells. Blocking Gal-9 or TIM-3 in vitro in a culture of peripheral blood mononuclear cells (PBMCs) stimulated with HBV peptide from active CHB patients restored CD8⁺ T cell function. However, blocking Gal-9 in vitro after removal of NK cells from PBMCs did not rescue CD8⁺ T cells exhaustion. Furthermore, NK and CD8⁺ T cells from active CHB patients were sorted and cocultured in vitro, and the exhaustion of CD8⁺ T cells were alleviated after blocking Gal-9 or TIM-3. In summary, overexpression of Gal-9 on NK cells, which interacts with TIM-3⁺CD8⁺ T cells and likely contributes to antiviral CD8⁺ T cell dysfunction, may be a potential target for the treatment of CHB patients.

In-Depth Immunological Typization of Children with Sickle Cell Disease: A Preliminary Insight into Its Plausible Correlation with Clinical Course and Hydroxyurea Therapy

Sickle cell disease (SCD) is a condition of functional hypo-/a-splenism in which predisposition to bacterial infections is only a facet of a wide spectrum of immune-dysregulation disorders forming the clinical expression of a peculiar immunophenotype. The objective of this study was to perform an in-depth immunophenotypical characterization of SCD pediatric patients, looking for plausible correlations between immunological biomarkers, the impact of hydroxyurea (HU) treatment and clinical course. This was an observational case−control study including 43 patients. The cohort was divided into two main groups, SCD subjects (19/43) and controls (24/43), differing in the presence/absence of an SCD diagnosis. The SCD group was split up into HU+ (12/19) and HU− (7/19) subgroups, respectively receiving or not a concomitant HU treatment. The principal outcomes measured were differences in the immunophenotyping between SCD patients and controls through chi-squared tests, t-tests, and Pearson’s correlation analysis between clinical and immunological parameters. Leukocyte and neutrophil increase, T-cell depletion with prevalence of memory T-cell compartment, NK and B-naïve subset elevation with memory and CD21low B subset reduction, and IgG expansion, significantly distinguished the SCD HU− subgroup from controls, with naïve T cells, switched-memory B cells and IgG maintaining differences between the SCD HU+ group and controls (p-value of <0.05). The mean CD4+ central-memory T-cell% count was the single independent variable showing a positive correlation with vaso-occlusive crisis score in the SCD group (Pearson’s R = 0.039). We report preliminary data assessing plausible clinical implications of baseline and HU-related SCD immunophenotypical alterations, which need to be validated in larger samples, but potentially affecting hypo-/a-splenism immuno-chemoprophylactic recommendations.

Immune Dysfunctions of CD56neg NK Cells Are Associated With HIV-1 Disease Progression

Background

Populations of natural killer cells lacking CD56 expression [CD56^neg natural killer (NK) cells] have been demonstrated to expand during human immunodeficiency virus (HIV)-1 infection. However, their phenotypic and functional characteristics have not been systematically analyzed, and their roles during disease progression remain poorly understood.

Methods

In this study, 84 donors, namely 34 treatment-naïve HIV-1-infected patients (TNs), 29 HIV-1-infected patients with successful antiretroviral therapy (ARTs), and 21 healthy controls (HCs), were enrolled. The phenotypic and functional characteristics of CD56^neg NK cells were analyzed using single-cell RNA-sequencing (scRNA-seq) and flow cytometry. A potential link between the characteristics of CD56^neg NK cells and the clinical parameters associated with HIV-1 disease progression was examined.

Results

The frequency of the CD56^neg NK cell population was significantly increased in TNs, which could be partially rescued by ART. Flow cytometry analyses revealed that CD56^neg NK cells were characterized by high expression of CD39, TIGIT, CD95, and Ki67 compared to CD56^dim NK cells. In vitro assays revealed reduced IFN-γ and TNF-α secretion, as well as decreased expression of granzyme B and perforin in CD56^neg NK cells. In line with the data obtained by flow cytometry, scRNA-seq analysis further demonstrated impaired cytotoxic activities of CD56^neg NK cells. Notably, a negative correlation was observed between CD39, CD95, and Ki67 expression levels in CD56^neg NK cells and CD4⁺ T cell counts.

Conclusions

The results presented in this study indicate that the CD56^neg NK cell population expanded in HIV-1-infected individuals is dysfunctional and closely correlates with HIV-1 disease progression.

Dimethyl Fumarate as the Peripheral Blood Inflammatory Mediators Inhibitor in Prevention of Streptozotocin-Induced Neuroinflammation in Aged Rats

Purpose

Intracerebroventricular-(ICV)-streptozotocin-(STZ)-induced neuroinflammation is a model of Alzheimer’s disease (AD) compatible with the inflammation hypothesis of ageing (“inflammaging” state). Previously, we observed age-dependent (young vs aged) dimethyl fumarate (DMF)-induced anti-inflammatory and neuroprotective effects in the brain along with improvement in cognitive functions in rats with the ICV-STZ-induced model of AD. To evaluate whether DMF reduces neuroinflammation based on the peripheral inflammatory response inhibition, we determined peripheral inflammatory mediators in young and aged rats with the ICV-STZ-induced AD pathology following DMF therapy.

Materials and Methods

Young (4-month-old) and aged (22-month-old) rats were fed with 0.4% DMF rat chow for 21 consecutive days after ICV-STZ (3 mg/ventricle) injections. After behavioral testing, blood and spleens were collected to determine the numbers of leukocytes (WBC), lymphocytes and their subpopulations, haematological parameters, the concanavalin (Con)-A-induced production and plasma concentration of interferon (IFN)-γ, interleukin (IL)-6, IL-10 and corticosterone (COR).

Results

Age-dependent anti-inflammatory effect of the DMF treatment in rats with ICV-STZ injections manifested as decreased peripheral WBC and lymphocyte numbers, including TCD3⁺CD4⁺CD8⁻, TCD3⁺CD4⁻CD8⁺, B (CD45RA⁺) and NK (161a⁺), in aged rats. Furthermore, DMF lowered the blood and spleen lymphocyte production of pro-inflammatory IFN-γ and IL-6 in young and aged rats, whereas it enhanced the plasma level of anti-inflammatory IL-10 and lymphocyte’s ability to produce it in aged rats only. In parallel to changes in peripheral WBC numbers in the model of AD, DMF decreased the red blood cell number, haemoglobin concentration, haematocrit and mean platelet volume in aged, but not young, rats. In contrast to controls, DMF did not influence the COR response in STZ groups.

Conclusion

Besides preventing neuroinflammation, DMF acts on the pro-/anti-inflammatory balance in the periphery and causes an anti-inflammatory shift in T lymphocytes which could contribute to DMF’s therapeutic effects in the ICV-STZ-induced model of AD, in particular, in aged rats.

Efficient In Vitro Generation of IL-22-Secreting ILC3 From CD34+ Hematopoietic Progenitors in a Human Mesenchymal Stem Cell Niche

Innate lymphoid cells (ILCs) and in particular ILC3s have been described to be vital for mucosal barrier functions and homeostasis within the gastrointestinal (GI) tract. Importantly, IL-22-secreting ILC3 have been implicated in the control of inflammatory bowel disease (IBD) and were shown to reduce the incidence of graft-versus-host disease (GvHD) as well as the risk of transplant rejection. Unfortunately, IL-22-secreting ILC3 are primarily located in mucosal tissues and are not found within the circulation, making access to them in humans challenging. On this account, there is a growing desire for clinically applicable protocols for in vitro generation of effector ILC3. Here, we present an approach for faithful generation of functionally competent human ILC3s from cord blood-derived CD34+ hematopoietic progenitors on layers of human mesenchymal stem cells (MSCs) generated in good manufacturing practice (GMP) quality. The in vitro-generated ILC3s phenotypically, functionally, and transcriptionally resemble bona fide tissue ILC3 with high expression of the transcription factors (TF) RorγT, AHR, and ID2, as well as the surface receptors CD117, CD56, and NKp44. Importantly, the majority of ILC3 belonged to the desired effector subtype with high IL-22 and low IL-17 production. The protocol thus combines the advantages of avoiding xenogeneic components, which were necessary in previous protocols, with a high propensity for generation of IL-22-producing ILC3. The present approach is suitable for the generation of large amounts of ILC3 in an all-human system, which could facilitate development of clinical strategies for ILC3-based therapy in inflammatory diseases and cancer.

Enzymatic bioconversion of ginseng powder increases the content of minor ginsenosides and potentiates immunostimulatory activity

Background

Ginsenosides are biologically active components of ginseng and have various functions. In this study, we investigated the immunomodulatory activity of a ginseng product generated from ginseng powder (GP) via enzymatic bioconversion. This product, General Bio compound K-10 mg solution (GBCK10S), exhibited increased levels of minor ginsenosides, including ginsenoside-F1, compound K, and compound Y.

Methods

The immunomodulatory properties of GBCK10S were confirmed using mice and a human natural killer (NK) cell line. We monitored the expression of molecules involved in immune responses via enzyme-linked immunosorbent assay, flow cytometry, NK cell-targeted cell destruction, quantitative reverse-transcription real-time polymerase chain reaction, and Western blot analyses.

Results

Oral administration of GBCK10S significantly increased serum immunoglobulin M levels and primed splenocytes to express pro-inflammatory cytokines such as interleukin-6, tumor necrosis factor-α, and interferon-γ. Oral administration of GBCK10S also activated NK cells in mice. Furthermore, GBCK10S treatment stimulated a human NK cell line in vitro, thereby increasing granzyme B gene expression and activating STAT5.

Conclusion

GBCK10S may have potent immunostimulatory properties and can activate immune responses mediated by B cells, Th1-type T cells, and NK cells.

A Hypothetical Model Suggesting Some Possible Ways That the Progesterone Receptor May Be Involved in Cancer Proliferation

Cancer and the fetal-placental semi-allograft share certain characteristics, e.g., rapid proliferation, the capacity to invade normal tissue, and, related to the presence of antigens foreign to the host, the need to evade immune surveillance. Many present-day methods to treat cancer use drugs that can block a key molecule that is important for one or more of these characteristics and thus reduce side effects. The ideal molecule would be one that is essential for both the survival of the fetus and malignant tumor, but not needed for normal cells. There is a potential suitable candidate, the progesterone induced blocking factor (PIBF). The parent 90 kilodalton (kDa) form seems to be required for cell-cycle regulation, required by both the fetal-placental unit and malignant tumors. The parent form may be converted to splice variants that help both the fetus and tumors escape immune surveillance, especially in the fetal and tumor microenvironment. Evidence suggests that membrane progesterone receptors are involved in PIBF production, and indeed there has been anecdotal evidence that progesterone receptor antagonists, e.g., mifepristone, can significantly improve longevity and quality of life, with few side effects.

FLT3L Release by Natural Killer Cells Enhances Response to Radioimmunotherapy in Preclinical Models of HNSCC

PURPOSE

Natural killer (NK) cells are type I innate lymphoid cells that are known for their role in killing virally infected cells or cancer cells through direct cytotoxicity. In addition to direct tumor cell killing, NK cells are known to play fundamental roles in the tumor microenvironment through secretion of key cytokines, such as FMS-like tyrosine kinase 3 ligand (FLT3L). Although radiotherapy is the mainstay treatment in most cancers, the role of radiotherapy on NK cells is not well characterized.

EXPERIMENTAL DESIGN

This study combines radiation, immunotherapies, genetic mouse models, and antibody depletion experiments to identify the role of NK cells in overcoming resistance to radiotherapy in orthotopic models of head and neck squamous cell carcinoma.

RESULTS

We have found that NK cells are a crucial component in the development of an antitumor response, as depleting them removes efficacy of the previously successful combination treatment of radiotherapy, anti-CD25, and anti-CD137. However, in the absence of NK cells, the effect can be rescued through treatment with FLT3L. But neither radiotherapy with FLT3L therapy alone nor radiotherapy with anti-NKG2A yields any meaningful tumor growth delay. We also identify a role for IL2 in activating NK cells to secrete FLT3L. This activity, we show, is mediated through CD122, the intermediate affinity IL2 receptor, and can be targeted with anti-CD25 therapy.

CONCLUSIONS

These findings highlight the complexity of using radio-immunotherapies to activate NK cells within the tumor microenvironment, and the importance of NK cells in activating dendritic cells for increased tumor surveillance.

Diabetes mellitus exacerbates experimental autoimmune myasthenia gravis via modulating both adaptive and innate immunity

BACKGROUND

Diabetes mellitus (DM) is a common concomitant disease of late-onset myasthenia gravis (MG). However, the impacts of DM on the progression of late-onset MG were unclear.

METHODS

In this study, we examined the immune response in experimental autoimmune myasthenia gravis (EAMG) rats with DM or not. The phenotype and function of the spleen and lymph nodes were determined by flow cytometry. The serum antibodies, Tfh cells, and germinal center B cells were determined by ELISA and flow cytometry. The roles of advanced glycation end products (AGEs) in regulating Tfh cells were further explored in vitro by co-culture assays.

RESULTS

Our results indicated clinical scores of EAMG rats were worse in diabetes rats compared to control, which was due to the increased production of anti-R97-116 antibody and antibody-secreting cells. Furthermore, diabetes induced a significant upregulation of Tfh cells and the subtypes of Tfh1 and Tfh17 cells to provide assistance for antibody production. The total percentages of B cells were increased with an activated statue of improved expression of costimulatory molecules CD80 and CD86. We found CD4⁺ T-cell differentiation was shifted from Treg cells towards Th1/Th17 in the DM+EAMG group compared to the EAMG group. In addition, in innate immunity, diabetic EAMG rats displayed more CXCR5 expression on NK cells. However, the expression of CXCR5 on NKT cells was down-regulated with the increased percentages of NKT cells in the DM+EAMG group. Ex vivo studies further indicated that Tfh cells were upregulated by AGEs instead of hyperglycemia. The upregulation was mediated by the existence of B cells, the mechanism of which might be attributed the elevated molecule CD40 on B cells.

CONCLUSIONS

Diabetes promoted both adaptive and innate immunity and exacerbated clinical symptoms in EAMG rats. Considering the effect of diabetes, therapy in reducing blood glucose levels in MG patients might improve clinical efficacy through suppressing the both innate and adaptive immune responses. Additional studies are needed to confirm the effect of glucose or AGEs reduction to seek treatment for MG.

Searching for the Elusive Regulatory Innate Lymphoid Cell

The complex nature of the innate lymphoid cell (ILC) family and wide range of ILC effector functions has been the focus of intense research. In addition to important roles in host defense, ILCs have central roles in maintaining tissue homeostasis and can promote immune tolerance. Alterations within the microenvironment can impart new functions on ILCs, and can even induce conversion to a distinct ILC family member. Complicating current definitions of ILCs are recent findings of distinct regulatory ILC populations that limit inflammatory responses or recruit other immunosuppressive cells such as regulatory T cells. Whether these populations are distinct ILC family members or rather canonical ILCs that exhibit immunoregulatory functions due to microenvironment signals has been the subject of much debate. In this review, we highlight studies identifying regulatory populations of ILCs that span regulatory NK-like cells, regulatory ILCs, and IL-10-producing ILC2s.

Crosstalk between Tumor-Infiltrating Immune Cells and Cancer-Associated Fibroblasts in Tumor Growth and Immunosuppression of Breast Cancer

Signals from the tumor microenvironment (TME) have a profound influence on the maintenance and progression of cancers. Chronic inflammation and the infiltration of immune cells in breast cancer (BC) have been strongly associated with early carcinogenic events and a switch to a more immunosuppressive response. Cancer-associated fibroblasts (CAFs) are the most abundant stromal component and can modulate tumor progression according to their secretomes. The immune cells including tumor-infiltrating lymphocytes (TILs) (cytotoxic T cells (CTLs), regulatory T cells (Tregs), and helper T cell (Th)), monocyte-infiltrating cells (MICs), myeloid-derived suppressor cells (MDSCs), mast cells (MCs), and natural killer cells (NKs) play an important part in the immunological balance, fluctuating TME between protumoral and antitumoral responses. In this review article, we have summarized the impact of these immunological players together with CAF secreted substances in driving BC progression. We explain the crosstalk of CAFs and tumor-infiltrating immune cells suppressing antitumor response in BC, proposing these cellular entities as predictive markers of poor prognosis. CAF-tumor-infiltrating immune cell interaction is suggested as an alternative therapeutic strategy to regulate the immunosuppressive microenvironment in BC.

Stem cells-derived natural killer cells for cancer immunotherapy: current protocols, feasibility, and benefits of ex vivo generated natural killer cells in treatment of advanced solid tumors

Nowadays, natural killer (NK) cell-based immunotherapy provides a practical therapeutic strategy for patients with advanced solid tumors (STs). This approach is adaptively conducted by the autologous and identical NK cells after in vitro expansion and overnight activation. However, the NK cell-based cancer immunotherapy has been faced with some fundamental and technical limitations. Moreover, the desirable outcomes of the NK cell therapy may not be achieved due to the complex tumor microenvironment by inhibition of intra-tumoral polarization and cytotoxicity of implanted NK cells. Currently, stem cells (SCs) technology provides a powerful opportunity to generate more effective and universal sources of the NK cells. Till now, several strategies have been developed to differentiate types of the pluripotent and adult SCs into the mature NK cells, with both feeder layer-dependent and/or feeder laye-free strategies. Higher cytokine production and intra-tumoral polarization capabilities as well as stronger anti-tumor properties are the main features of these SCs-derived NK cells. The present review article focuses on the principal barriers through the conventional NK cell immunotherapies for patients with advanced STs. It also provides a comprehensive resource of protocols regarding the generation of SCs-derived NK cells in an ex vivo condition.

Adoptive cell therapy using tumor-infiltrating lymphocytes for melanoma refractory to immune-checkpoint inhibitors

To evaluate the feasibility of adoptive cell therapy (ACT) using ex vivo‐expanded tumor‐infiltrating lymphocytes (TILs) in Japanese patients with melanoma who failed immune‐checkpoint inhibitor therapy, an open‐label, single‐arm, pilot study was conducted. We investigated the immunological and genetic factors of the pretreatment tumor and expanded TILs that may be associated with the clinical response. The treatment protocol comprised preparation of TIL culture, lympho‐depleting non‐myeloablative preconditioning with cyclophosphamide and fludarabine, TIL infusion, and intravenous administration of low‐dose IL‐2. Three patients of clinical subtypes mucosal, superficial spreading, and acral melanoma underwent TIL‐ACT. Most severe adverse events, including fever and leukopenia, were manageable with the supportive regimen specified in the protocol, suggesting that the TIL‐ACT regimen is suitable for Japanese patients with melanoma. One patient showed a short‐term partial response, one relatively long‐stable disease, and one experienced disease progression. Whole‐exome and transcriptional sequencing of isolated tumor cells and immunohistochemical analyses before TIL‐ACT revealed various immunostimulatory factors, including a high tumor mutation burden and immune cell‐recruiting chemokines, as well as various immunosuppressive factors including TGF‐β, VEGF, Wnt/β‐catenin, and MAPK signaling and epithelial‐to‐mesenchymal transition, which might influence the efficacy of TIL‐ACT. Our results imply mechanisms for the antitumor effect of and resistance to TIL‐ACT. Further studies of immune‐resistant mechanisms of TIL‐ACT are warranted. This study is registered with the UMIN Clinical Trial Registry (UMIN 000011431).

Unique adaptations in neonatal hepatic transcriptome, nutrient signaling, and one-carbon metabolism in response to feeding ethyl cellulose rumen-protected methionine during late-gestation in Holstein cows

BACKGROUND

Methionine (Met) supply during late-pregnancy enhances fetal development in utero and leads to greater rates of growth during the neonatal period. Due to its central role in coordinating nutrient and one-carbon metabolism along with immune responses of the newborn, the liver could be a key target of the programming effects induced by dietary methyl donors such as Met. To address this hypothesis, liver biopsies from 4-day old calves (n = 6/group) born to Holstein cows fed a control or the control plus ethyl-cellulose rumen-protected Met for the last 28 days prepartum were used for DNA methylation, transcriptome, metabolome, proteome, and one-carbon metabolism enzyme activities.

RESULTS

Although greater withers and hip height at birth in Met calves indicated better development in utero, there were no differences in plasma systemic physiological indicators. RNA-seq along with bioinformatics and transcription factor regulator analyses revealed broad alterations in 'Glucose metabolism', 'Lipid metabolism, 'Glutathione', and 'Immune System' metabolism due to enhanced maternal Met supply. Greater insulin sensitivity assessed via proteomics, and efficiency of transsulfuration pathway activity suggested beneficial effects on nutrient metabolism and metabolic-related stress. Maternal Met supply contributed to greater phosphatidylcholine synthesis in calf liver, with a role in very low density lipoprotein secretion as a mechanism to balance metabolic fates of fatty acids arising from the diet or adipose-depot lipolysis. Despite a lack of effect on hepatic amino acid (AA) transport, a reduction in metabolism of essential AA within the liver indicated an AA 'sparing effect' induced by maternal Met.

CONCLUSIONS

Despite greater global DNA methylation, maternal Met supply resulted in distinct alterations of hepatic transcriptome, proteome, and metabolome profiles after birth. Data underscored an effect on maintenance of calf hepatic Met homeostasis, glutathione, phosphatidylcholine and taurine synthesis along with greater efficiency of nutrient metabolism and immune responses. Transcription regulators such as FOXO1, PPARG, E2F1, and CREB1 appeared central in the coordination of effects induced by maternal Met. Overall, maternal Met supply induced better immunometabolic status of the newborn liver, conferring the calf a physiologic advantage during a period of metabolic stress and suboptimal immunocompetence.

Natural Killer Cells in Post-Transplant Lymphoproliferative Disorders

Post-transplant lymphoproliferative disorders (PTLDs) are life-threatening complications arising after solid organ or hematopoietic stem cell transplantations. Although the majority of these lymphoproliferations are of B cell origin, and are frequently associated with primary Epstein-Barr virus (EBV) infection or reactivation in the post-transplant period, rare cases of T cell and natural killer (NK) cell-originated PTLDs have also been described. A general assumption is that PTLDs result from the impairment of anti-viral and anti-tumoral immunosurveillance due to the long-term use of immunosuppressants in transplant recipients. T cell impairment is known to play a critical role in the immune-pathogenesis of post-transplant EBV-linked complications, while the role of NK cells has been less investigated, and is probably different between EBV-positive and EBV-negative PTLDs. As a part of the innate immune response, NK cells are critical for protecting hosts during the early response to virus-induced tumors. The complexity of their function is modulated by a myriad of activating and inhibitory receptors expressed on cell surfaces. This review outlines our current understanding of NK cells in the pathogenesis of PTLD, and discusses their potential implications for current PTLD therapies and novel NK cell-based therapies for the containment of these disorders.

Thioredoxin activity confers resistance against oxidative stress in tumor-infiltrating NK cells

To improve the clinical outcome of adoptive NK cell therapy in patients with solid tumors, NK cells need to persist within the tumor microenvironment (TME) in which the abundance of ROS could dampen antitumor immune responses. In the present study, we demonstrated that IL-15-primed NK cells acquired resistance against oxidative stress through the thioredoxin system activated by mTOR. Mechanistically, the activation of thioredoxin showed dependence on localization of thioredoxin-interacting protein. We show that NK cells residing in the tumor core expressed higher thiol densities that could aid in protecting other lymphocytes against ROS within the TME. Furthermore, the prognostic value of IL15 and the NK cell gene signature in tumors may be influenced by tobacco smoking history in patients with non-small-cell lung cancer (NSCLC). Collectively, the levels of reducing antioxidants in NK cells may not only predict better tumor penetrance but potentially even the immune therapy response.

Molecular Diversity of Clinically Stable Human Kidney Allografts

IMPORTANCE

Clinical decision and immunosuppression dosing in kidney transplantation rely on transplant biopsy tissue histology even though histology has low specificity, sensitivity, and reproducibility for rejection diagnosis. The inclusion of stable allografts in mechanistic and clinical studies is vital to provide a normal, noninjured comparative group for all interrogative studies on understanding allograft injury.

OBJECTIVE

To refine the definition of a stable allograft as one that is clinically, histologically, and molecularly quiescent using publicly available transcriptomics data.

DESIGN, SETTING, AND PARTICIPANTS

In this prognostic study, the National Center for Biotechnology Information Gene Expression Omnibus was used to search for microarray gene expression data from kidney transplant tissues, resulting in 38 studies from January 1, 2017, to December 31, 2018. The diagnostic annotations included 510 acute rejection (AR) samples, 1154 histologically stable (hSTA) samples, and 609 normal samples. Raw fluorescence intensity data were downloaded and preprocessed followed by data set merging and batch correction.

MAIN OUTCOMES AND MEASURES

The primary measure was area under the receiver operating characteristics curve from a set of feature selected genes and cell types for distinguishing AR from normal kidney tissue.

RESULTS

Within the 28 data sets, the feature selection procedure identified a set of 6 genes (KLF4, CENPJ, KLF2, PPP1R15A, FOSB, TNFAIP3) (area under the curve [AUC], 0.98) and 5 immune cell types (CD4+ T-cell central memory [Tcm], CD4+ T-cell effector memory [Tem], CD8+ Tem, natural killer [NK] cells, and Type 1 T helper [TH1] cells) (AUC, 0.92) that were combined into 1 composite Instability Score (InstaScore) (AUC, 0.99). The InstaScore was applied to the hSTA samples: 626 of 1154 (54%) were found to be immune quiescent and redefined as histologically and molecularly stable (hSTA/mSTA); 528 of 1154 (46%) were found to have molecular evidence of rejection (hSTA/mAR) and should not have been classified as stable allografts. The validation on an independent cohort of 6 months of protocol biopsy samples in December 2019 showed that hSTA/mAR samples had a significant change in graft function (r = 0.52, P < .001) and graft loss at 5-year follow-up (r = 0.17). A drop by 10 mL/min/1.73m2 in estimated glomerular filtration rate was estimated as a threshold in allograft transitioning from hSTA/mSTA to hSTA/mAR.

CONCLUSIONS AND RELEVANCE

The results of this prognostic study suggest that the InstaScore could provide an important adjunct for comprehensive and highly quantitative phenotyping of protocol kidney transplant biopsy samples and could be integrated into clinical care for accurate estimation of subsequent patient clinical outcomes.

Osteoclast-expanded super-charged NK-cells preferentially select and expand CD8+ T cells

Osteoclasts (OCs) and much less dendritic cells (DCs) induce significant expansion and functional activation of NK cells, and furthermore, the OC-expanded NK cells preferentially increase the expansion and activation of CD8+ T cells by targeting CD4+ T cells. When autologous OCs were used to expand patient NK cells much lower percentages of expanded CD8+ T cells, decreased numbers of expanded NK cells and decreased functions of NK cells could be observed, and the addition of allogeneic healthy OCs increased the patients' NK function. Mechanistically, OC-expanded NK cells were found to lyse CD4+ T cells but not CD8+ T cells suggesting potential selection of CD8+ T cells before their expansion by OC activated NK cells. In agreement, Increased IFN-γ secretion, and NK cell-mediated cytotoxicity and higher percentages of CD8+ T cells, in various tissue compartments of oral tumor-bearing hu-BLT mice in response to immunotherapy by OC-expanded NK cells were observed. Thus, our results indicate an important relationship between NK and CD8+ T cells.

Immunomodulatory effects of cytokine-induced expansion of cytotoxic lymphocytes in a mouse model of lupus-like disease

BACKGROUND AIMS

Certain therapies (e.g., daclizumab) that promote expansion of natural killer (NK) cells are associated with clinical amelioration of disease in the context of multiple sclerosis and associated mouse models. The clinical benefits are putatively attributable to an enhanced capacity of NK cells to kill activated pathogenic T cells. Whether a parallel approach will also be effective in systemic lupus erythematosus (lupus), a multi-organ autoimmune disease driven by aberrant responses of self-reactive T and B cells, is unclear.

METHODS

In the present study, the authors assess the therapeutic impact of IL-2- and IL-15-based strategies for expanding NK cells on measures of lupus-like disease in a mouse model.

RESULTS

Unexpectedly, cytokine-mediated expansion of cytotoxic lymphocytes aggravated immunological measures of lupus-like disease. Depletion studies revealed that the negative effects of these cytokine-based regimens can largely be attributed to expansion of CD8 T cells rather than NK cells.

CONCLUSIONS

These results provoke caution in the use of cytokine-based therapeutics to treat co-morbid cancers in patients with lupus and highlight the need for new methods to selectively expand NK cells to further assess their clinical value in autoimmune disease.

Targeting Inflammation and Immunosenescence to Improve Vaccine Responses in the Elderly

One of the most appreciated consequences of immunosenescence is an impaired response to vaccines with advanced age. While most studies report impaired antibody responses in older adults as a correlate of vaccine efficacy, it is now widely appreciated that this may fail to identify important changes occurring in the immune system with age that may affect vaccine efficacy. The impact of immunosenescence on vaccination goes beyond the defects on antibody responses as T cell-mediated responses are reshaped during aging and certainly affect vaccination. Likewise, age-related changes in the innate immune system may have important consequences on antigen presentation and priming of adaptive immune responses. Importantly, a low-level chronic inflammatory status known as inflammaging has been shown to inhibit immune responses to vaccination and pharmacological strategies aiming at blocking baseline inflammation can be potentially used to boost vaccine responses. Yet current strategies aiming at improving immunogenicity in the elderly have mainly focused on the use of adjuvants to promote local inflammation. More research is needed to understand the role of inflammation in vaccine responses and to reconcile these seemingly paradoxical observations. Alternative approaches to improve vaccine responses in the elderly include the use of higher vaccine doses or alternative routes of vaccination showing only limited benefits. This review will explore novel targets and potential new strategies for enhancing vaccine responses in older adults, including the use of anti-inflammatory drugs and immunomodulators.

Cytotoxicity of Donor Natural Killer Cells to Allo-Reactive T Cells Are Related With Acute Graft-vs.-Host-Disease Following Allogeneic Stem Cell Transplantation

Objectives: The mechanism and immunoregulatory role of human natural killer (NK) cells in acute graft-vs.-host-disease (aGVHD) remains unclear. This study quantitatively analyzed the cytotoxicity of donor NK cells toward allo-reactive T cells, and investigated their relationship with acute GVHD (aGVHD).

Methods: We evaluated NK dose, subgroup, and receptor expression in allografts from 98 patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT). A CD107a degranulating assay was used as a quantitative detection method for the cytotoxic function of donor NK cells to allo-reactive T cells. In antibody-blocking assay, NK cells were pre-treated with anti-DNAM-1(CD226), anti-NKG2D, anti-NKP46, or anti-NKG-2A monoclonal antibodies (mAbs) before the degranulating assay.

Results: NK cells in allografts effectively inhibited auto-T cell proliferation following alloantigen stimulation, selectively killing alloantigen activated T cells. NKG2A⁻ NK cell subgroups showed higher levels of CD107a degranulation toward activated T cells, when compared with NKG2A⁻ subgroups. Blocking NKG2D or CD226 (DNAM-1) led to significant reductions in degranulation, whereas NKG2A block resulted in increased NK degranulation. Donor NK cells in the aGVHD group expressed lower levels of NKG2D and CD226, higher levels of NKG2A, and showed higher CD107a degranulation levels when compared with NK cells in the non-aGVHD group. Using univariate analysis, higher NK degranulation activities in allografts (CD107a^high) were correlated with a decreased risk in grade I–IV aGVHD (hazard risk [HR] = 0.294; P < 0.0001), grade III–IV aGVHD (HR = 0.102; P < 0.0001), and relapse (HR = 0.157; P = 0.015), and improved overall survival (HR = 0.355; P = 0.028) after allo-HSCT. Multivariate analyses showed that higher NK degranulation activities (CD107a^high) in allografts were independent risk factors for grades, I–IV aGVHD (HR = 0.357; P = 0.002), and grades III–IV aGVHD (HR = 0.13; P = 0.009).

Conclusions: These findings reveal that the degranulation activity of NK in allografts toward allo-activated T cells was associated with the occurrence and the severity of aGVHD, after allogeneic stem cell transplantation. This suggested that cytotoxicity of donor NK cells to allo-reactive T cells have important roles in aGVHD regulation.

Toll-like receptor 2 activation induces C-C chemokine receptor 2-dependent natural killer cell recruitment to the peritoneum

Natural killer (NK) cells are innate effector cells with critical roles not only in tumor immunosurveillance and viral immunity, but also in bacterial and fungal infections. Toll‐like receptor 2 (TLR2) can be important in the early and sustained immune responses to pathogens and tumors through the induction of cytokines and chemokines that recruit and activate immune effector cells. We investigated the role of TLR2 activation in NK cell recruitment with a view to informing approaches to induce or regulate peritoneal NK cell responses therapeutically. Peritoneal injection of TLR2 activators, including peptidoglycan and the lipopeptides FSL‐1 and Pam₃CSK₄, resulted in NK cell recruitment after 16 h with increased NK cell numbers maintained for 48 h. TLR2 activators induced large amounts of CCR2 ligands, but much smaller amounts of CCR5 and CXCR3 ligands. Consistent with this observation, NK cell migration was abrogated in CCR2‐deficient mice after peritoneal FSL‐1 injection. Adoptive transfer of CCR2‐deficient NK cells prior to peritoneal FSL‐1 activation confirmed a cell‐intrinsic component of CCR2‐mediated NK cell migration. TLR2 activation did not induce an activated NK cell phenotype, but significant changes included an increase in the KLRG1⁺ subset and decreased NKG2D expression. Although not activated in vivo, peritoneal NK cells could be activated by interleukin (IL)‐12 and IL‐18 ex vivo to express CD69 and interferonγ. These data demonstrate that TLR2‐mediated immune activation is a potent inducer of NK cell recruitment via a CCR2‐dependent mechanism and that NK cells recruited by this mechanism can respond to additional signals to exert effector cell functions.

Chronic Lymphocytic Choriomeningitis Infection Causes Susceptibility to Mousepox and Impairs Natural Killer Cell Maturation and Function

Chronic viral infections. like those of humans with cytomegalovirus, human immunodeficiency virus (even when under antiretroviral therapy), and hepatitis C virus or those of mice with lymphocytic choriomeningitis virus (LCMV) clone 13 (CL13), result in immune dysfunction that predisposes the host to severe infections with unrelated pathogens. It is known that C57BL/6 (B6) mice are resistant to mousepox, a lethal disease caused by the orthopoxvirus ectromelia virus (ECTV), and that this resistance requires natural killer (NK) cells and other immune cells. We show that most B6 mice chronically infected with CL13 succumb to mousepox but that most of those that recovered from acute infection with the LCMV Armstrong (Arm) strain survive. We also show that B6 mice chronically infected with CL13 and those that recovered from Arm infection have a reduced frequency and a reduced number of NK cells. However, at steady state, NK cells in mice that have recovered from Arm infection mature normally and, in response to ECTV, get activated, become more mature, proliferate, and increase their cytotoxicity in vivo Conversely, in mice chronically infected with CL13, NK cells are immature and residually activated, and following ECTV infection, they do not mature, proliferate, or increase their cytotoxicity. Given the well-established importance of NK cells in resistance to mousepox, these data suggest that the NK cell dysfunction caused by CL13 persistence may contribute to the susceptibility of CL13-infected mice to mousepox. Whether chronic infections similarly affect NK cells in humans should be explored.IMPORTANCE Infection of adult mice with the clone 13 (CL13) strain of lymphocytic choriomeningitis virus (LCMV) is extensively used as a model of chronic infection. In this paper, we show that mice chronically infected with CL13 succumb to challenge with ectromelia virus (ECTV; the agent of mousepox) and that natural killer (NK) cells in CL13-infected mice are reduced in numbers and have an immature and partially activated phenotype but do respond to ECTV. These data may provide additional clues why humans chronically infected with certain pathogens are less resistant to viral diseases.

NK Cells Regulate CD8+ T Cell Mediated Autoimmunity

Elucidating key factors that regulate immune-mediated pathology in vivo is critical for developing improved strategies to treat autoimmune disease and cancer. NK cells can exhibit regulatory functions against CD8⁺ T cells following viral infection. Here we show that while low doses of lymphocytic choriomeningitis virus (LCMV-WE) can readily induce strong CD8⁺ T cell responses and diabetes in mice expressing the LCMV glycoprotein on β-islet cells (RIP-GP mice), hyperglycemia does not occur after infection with higher doses of LCMV. High-dose LCMV infection induced an impaired CD8⁺ T cell response, which coincided with increased NK cell activity during early time points following infection. Notably, we observed increased NKp46 expression on NK cells during infection with higher doses, which resulted in an NK cell dependent suppression of T cells. Accordingly, depletion with antibodies specific for NK1.1 as well as NKp46 deficiency (Ncr1^gfp/gfp mice) could restore CD8⁺ T cell immunity and permitted the induction of diabetes even following infection of RIP-GP mice with high-dose LCMV. Therefore, we identify conditions where innate lymphoid cells can play a regulatory role and interfere with CD8⁺ T cell mediated tissue specific pathology using an NKp46 dependent mechanism.

Immunological Drivers in Graves' Disease: NK Cells as a Master Switcher

Graves' disease (GD) is a common autoimmune cause of hyperthyroidism, which is eventually related to the generation of IgG antibodies stimulating the thyrotropin receptor. Clinical manifestations of the disease reflect hyperstimulation of the gland, causing thyrocyte hyperplasia (goiter) and excessive thyroid hormone synthesis (hyperthyroidism). The above clinical manifestations are preceded by still partially unraveled pathogenic actions governed by the induction of aberrant phenotype/functions of immune cells. In this review article we investigated the potential contribution of natural killer (NK) cells, based on literature analysis, to discuss the bidirectional interplay with thyroid hormones (TH) in GD progression. We analyzed cellular and molecular NK-cell associated mechanisms potentially impacting on GD, in a view of identification of the main NK-cell subset with highest immunoregulatory role.

CXCR5-negative natural killer cells ameliorate experimental autoimmune myasthenia gravis by suppressing follicular helper T cells

Background

Recent studies have demonstrated that natural killer (NK) cells can modulate other immune components and are involved in the development or progression of several autoimmune diseases. However, the roles and mechanisms of NK cells in regulating experimental autoimmune myasthenia gravis (EAMG) remained to be illustrated.

Methods

To address the function of NK cells in experimental autoimmune myasthenia gravis in vivo, EAMG rats were adoptively transferred with splenic NK cells. The serum antibodies, and splenic follicular helper T (Tfh) cells and germinal center B cells were determined by ELISA and flow cytometry. The roles of NK cells in regulating Tfh cells were further verified in vitro by co-culturing splenocytes or isolated T cells with NK cells. Moreover, the phenotype, localization, and function differences between different NK cell subtypes were determined by flow cytometry, immunofluorescence, and ex vivo co-culturation.

Results

In this study, we found that adoptive transfer of NK cells ameliorated EAMG symptoms by suppressing Tfh cells and germinal center B cells. Ex vivo studies indicated NK cells inhibited CD4⁺ T cells and Tfh cells by inducing the apoptosis of T cells. More importantly, NK cells could be divided into CXCR5^- and CXCR5⁺ NK subtypes according to the expression of CXCR5 molecular. Compared with CXCR5^- NK cells, which were mainly localized outside B cell zone, CXCR5⁺ NK were concentrated in the B cell zone and exhibited higher expression levels of IL-17 and ICOS, and lower expression level of CD27. Ex vivo studies indicated it was CXCR5^- NK cells not CXCR5⁺ NK cells that suppressed CD4⁺ T cells and Tfh cells. Further analysis revealed that, compared with CXCR5^- NK cells, CXCR5⁺ NK cells enhanced the ICOS expression of Tfh cells.

Conclusions

These findings highlight the different roles of CXCR5^- NK cells and CXCR5⁺ NK cells. It was CXCR5^- NK cells but not CXCR5⁺ NK cells that suppressed Tfh cells and inhibited the autoimmune response in EAMG models.

Dynamic Changes in Natural Killer Cell Subset Frequencies in the Absence of Cytomegalovirus Infection

Individuals lacking functional natural killer (NK) cells suffer severe, recurrent infections with cytomegalovirus (CMV), highlighting the critical role of NK cells in antiviral defense. Therefore, ongoing attempts to develop an efficacious vaccine to prevent CMV infection should potentially aim to elicit NK-cell antiviral responses as an accessory to conventional T- and B-cell based approaches. In this regard, CMV infection provokes marked phenotypic and functional differentiation of the NK-cell compartment, including development of adaptive NK cells that exhibit enhanced antiviral activity. We examined longitudinal blood samples collected from 40 CMV-seronegative adolescents to ascertain whether a CMV glycoprotein B (gB) vaccine in the absence of CMV infection can stimulate differentiation or expansion of CMV-associated subsets of NK cells. Study participants uniformly lacked the CMV-dependent NKG2C⁺ subset of NK cells, suggesting that an adjuvanted CMV gB vaccine alone is an inadequate stimulus for sustained expansion of these cells. In contrast, we observed unexpected dynamic fluctuations in the frequency of NK cells lacking FcRγ, EAT-2, and SYK, which were independent of vaccination or CMV infection. Whereas, FcRγ^neg NK cells in CMV infection are reported to express increased levels of the maturation marker CD57, the FcRγ^neg NK cells observed in our CMV-negative vaccine cohort express less CD57 than their FcRγ⁺ counterparts. The FcRγ^neg NK cells in CMV-negative individuals were also functionally distinct from this subset in CMV infection, exhibiting comparable IFN-γ production and degranulation as FcRγ⁺ NK cells in response to cytokine or antibody-dependent stimuli. These results suggest that frequencies of some NK cell subsets may increase in response to unknown environmental or inflammatory cues distinct from that which occurs after CMV infection. Greater understanding of the nature of the signals driving CMV-independent accumulation of these subsets should permit development of mechanisms to facilitate vaccine-driven expansion of CMV-reactive NK cells.

Clinical Implications of Tumor-Infiltrating Immune Cells in Breast Cancer

The immune infiltration of tumors is closely related to clinical outcomes. The composition of tumor-infiltrating immune cells (TIICs) can serve as biomarkers for predicting response to treatment and survival in different patient subgroups in terms of chemotherapy and immunotherapy. This study is focused on investigating the clinical implications of TIICs in breast cancer patients. We performed several in silico analyses of gene expression profiles in 2976 nonmetastatic tumor samples. CIBERSORT was used to estimate the proportion of 22 immune cell types to analyze their correlation with overall survival (OS) and disease-free survival (DFS) in different breast cancer subtypes and stages. Our results showed that a higher fraction of plasma cells in estrogen receptor (ER)-positive breast cancer patients indicated an increase in DFS (hazard ratio [HR]=0.66, 95% confidence interval [CI] 0.54~0.82, p<0.01), while a decreased OS was correlated with a greater number of M0 macrophages (HR=2.02, 95% CI 1.27~3.30, p=0.01) and regulatory T cells (HR=1.90, 95% CI 1.20~3.02, p=0.02). In ER-negative or progesterone receptor (PR)-negative subtypes or in a combined subtype, the increase in activated memory CD4⁺ T cells was correlated with increased DFS (HR=0.46, 95% CI 0.33~0.63, p<0.01). In all breast cancer patients, a higher proportion of M0 macrophages indicated a decreased DFS (HR=1.67, 95% CI 1.22~2.27, p<0.01), while increased OS was associated with relatively larger fractions of resting memory CD4⁺ T cells (HR=0.70, 95% CI 0.55~0.90, p=0.02) and γδ T cells (HR=0.66, 95% CI 0.51~0.85, p<0.01). Therefore, this study revealed that the composition of TIICs is different in patients with various subtypes of breast cancer and is directly related to prognosis, suggesting that TIICs are important participants in tumor progression and may, potentially be used for future diagnosis and treatment.

CD56- CD16+ NK cells from HIV-infected individuals negatively regulate IFN-γ production by autologous CD8+ T cells

The percentage of human CD56^- CD16⁺ NK cells increases during chronic infection with human HIV; however, the biologic role of CD56^- CD16⁺ NK cells in HIV infection is unclear. Our results demonstrate that the percentage of CD56^- CD16⁺ NK cells producing IL-10 and TGF-β was higher than CD56^dim CD16⁺ NK cells. CD56^- CD16⁺ NK cells could inhibit IFN-γ production by autologous CD8⁺ T cells, and this inhibition could be partially reversed by anti-IL-10, anti-TGF-β, or anti-PD-L1 mAbs. CD56^- CD16⁺ NK cells are potential targets for the development of novel immune therapies against HIV infection.

A Natural Impact: NK Cells at the Intersection of Cancer and HIV Disease

Despite efficient suppression of plasma viremia in people living with HIV (PLWH) on cART, evidence of HIV-induced immunosuppression remains, and normally benign and opportunistic pathogens become major sources of co-morbidities, including virus-induced cancers. In fact, cancer remains a primary cause of death even in virally suppressed PLWH. Natural killer (NK) cells provide rapid early responses to HIV infection, contribute substantially to disease modulation and vaccine protection, and are also major therapeutic targets for cancer immunotherapy. However, much like other lymphocyte populations, recent burgeoning evidence suggests that in chronic conditions like HIV, NK cells can become functionally exhausted with impaired cytotoxic function, altered cytokine production and impaired antibody-dependent cell-mediated cytotoxicity. Recent work suggests functional anergy is likely due to low-level ongoing virus replication, increased inflammatory cytokines, or increased presence of MHC^low target cells. Indeed, HIV-induced loss of NK cell-mediated control of lytic EBV infection has been specifically shown to cause lymphoma and also increases replication of CMV. In this review, we will discuss current understanding of NK cell modulation of HIV disease, reciprocal exhaustion of NK cells, and how this may impact increased cancer incidences and prospects for NK cell-targeted immunotherapies. Finally, we will review the most recent evidence supporting adaptive functions of NK cells and highlight the potential of adaptive NK cells for cancer immunotherapy.

Dose-Ranging and Cohort-Expansion Study of Monalizumab (IPH2201) in Patients with Advanced Gynecologic Malignancies: A Trial of the Canadian Cancer Trials Group (CCTG): IND221

PURPOSE

Monalizumab binds CD94/NKG2A, preventing HLA-E inhibition of tumor lymphocytes. A dose-ranging/cohort expansion trial of monalizumab for recurrent gynecologic malignancies was conducted to determine the recommended phase II dose (RP2D) and to explore clinical activity, pharmacokinetics, pharmacodynamics, safety, and immunogenicity.

PATIENTS AND METHODS

Participants (and part 2 expansion cohorts) included (i) platinum-sensitive ovarian, (ii) platinum-resistant ovarian, (iii) squamous cervical (CX), and (iv) epithelial endometrial (END) carcinomas. Part 1 assessed monalizumab at 1, 4, or 10 mg/kg every 2 weeks. In part 2, ≥4 patients/cohort underwent pre- and on-treatment tumor biopsies. Preset criteria determined cohort expansion.

RESULTS

A total of 58 participants were evaluable. The RP2D was 10 mg/kg i.v. every 2 weeks. Dose proportionality and 100% NKG2A saturation were observed. Related adverse events were mild: headache, abdominal pain, fatigue, nausea, and vomiting. Grade 3 related adverse events were nausea (1), vomiting (1), dehydration (1), fatigue (2), anorexia (1), dyspnea (1), and proctitis (1). Dose-limiting toxicities were not observed. Hematologic and biochemical changes were mild and not dose related. Best response was SD: part 1, 7 of 18 (39%) [3.4 months (1.4-5.5)], and part 2, 7 of 39 (18%) [1.7 months (CX) to 14.8 months (END)]. Neither a predictive biomarker for SD nor evidence of pharmacodynamic effects was identified. There was a trend to significance between a reduction in lymphocyte HLA-E total score and pharmacodynamics.

CONCLUSIONS

Monalizumab 10 mg/kg i.v. every 2 week is well tolerated in patients with pretreated gynecologic cancers. Short-term disease stabilization was observed. Future studies should assess combinations with other agents, including immunotherapeutics.

Roles of Type 1, 2, and 3 Innate Lymphoid Cells in Herpes Simplex Virus 1 Infection In Vitro and In Vivo

Innate lymphoid cells (ILCs) play important roles in host defense and inflammation. They are classified into three distinct groups based on their cytokine and chemokine secretion patterns and transcriptome profiles. Here, we show that ILCs isolated from mice can be infected with herpes simplex virus 1 (HSV-1) but that subsequent replication of the virus is compromised. After infection, type 2 ILCs expressed significantly higher levels of granulocyte colony-stimulating factor (G-CSF), interleukin 1α (IL-1α), IL-6, IL-9, RANTES, tumor necrosis factor alpha (TNF-α), CXCL1, CXCL2, CXCL10, CCL3, and CCL4 than infected type 1 or type 3 ILCs. Transcriptome-sequencing (RNA-seq) analysis of the ILCs 24 h after HSV-1 infection revealed that 77 herpesvirus genes were detected in the infected type 3 ILCs, whereas only 11 herpesvirus genes were detected in infected type 1 ILCs and 27 in infected type 2 ILCs. Compared with uninfected cells, significant upregulation of over 4,000 genes was seen in the HSV-1-infected type 3 ILCs, whereas 414 were upregulated in the infected type 1 ILCs and 128 in the infected type 2 ILCs. In contrast, in all three cell types, only a limited number of genes were significantly downregulated. Type 1, type 2, and type 3 ILC-deficient mice were used to gain insights into the effects of the ILCs on the outcome of ocular HSV-1 infection. No significant differences were found on comparison with similarly infected wild-type mice or on comparison of the three strains of deficient mice in terms of virus replication in the eyes, levels of corneal scarring, latency-reactivation in the trigeminal ganglia, or T-cell exhaustion. Although there were no significant differences in the survival rates of infected ILC-deficient mice and wild-type mice, there was significantly reduced survival of the infected type 1 or type 3 ILC-deficient mice compared with type 2 ILC-deficient mice. Adoptive transfer of wild-type T cells did not alter survival or any other parameters tested in the infected mice. Our results indicate that type 1, 2, and 3 ILCs respond differently to HSV-1 infection in vitro and that the absence of type 1 or type 3, but not type 2, ILCs affects the survival of ocularly infected mice.IMPORTANCE In this study, we investigated for the first time what roles, if any, innate lymphoid cells (ILCs) play in HSV-1 infection. Analysis of isolated ILCs in vitro revealed that all three subtypes could be infected with HSV-1 but that they were resistant to replication. The expression profiles of HSV-1-induced cytokines/chemokines and cellular and viral genes differed among the infected type 1, 2, and 3 ILCs in vitro While ILCs play no role or a redundant role in the outcomes of latency-reactivation in infected mice, absence of type 1 and type 3, but not type 2, ILCs affects the survival of infected mice.

Circulating CD56bright NK cells inversely correlate with survival of melanoma patients

The roles of NK cells in human melanoma remain only partially understood. We characterized NK cells from peripheral blood ex vivo by flow cytometry obtained from late stage (III/IV) melanoma patients. Interestingly, we found that the abundance of CD56bright NK cells negatively correlate with overall patient survival, together with distant metastases, in a multivariate cox regression analysis. The patients' CD56bright NK cells showed upregulation of CD11a, CD38 and CD95 as compared to healthy controls, pointing to an activated phenotype as well as a possible immune regulatory role in melanoma patients. After stimulation in vitro, CD56bright NK cells produced less TNFα and GMCSF in patients than controls. Furthermore, IFNγ production by the CD56bright NK cells correlated inversely with overall survival. Our results highlight that abundance and function of CD56bright NK cells are associated with melanoma patient survival, emphasizing the potential of NK cell subsets for biomarker discovery and future therapeutic targeting.

Mutually assured destruction: the cold war between viruses and natural killer cells

Natural killer (NK) cells play a multitude of antiviral roles that are significant enough to provoke viral counterefforts to subvert their activity. As innate lymphocytes, NK cells provide a rapid source of pro-inflammatory antiviral cytokines and bring to bear cytolytic activities that are collectively meant to constrain viral replication and dissemination. Additionally, NK cells participate in adaptive immunity both by shaping virus-specific T-cell responses and by developing adaptive features themselves, including enhanced antibody-dependent effector functions. The relative importance of different functional activities of NK cells are poorly understood, thereby obfuscating clinical use of these cells. Here we focus on opposing efforts of NK cells and viruses to gain tactical superiority during infection.

Insight into the mechanism of action of dimethyl fumarate in multiple sclerosis

Dimethyl fumarate (DMF) is an oral, disease-modifying agent for the treatment of relapsing-remitting multiple sclerosis (RRMS). However, details regarding its mode of action are still emerging. It is believed that the mode of action of DMF involves both nuclear factor erythroid-derived 2-related factor (Nrf2)-dependent and independent pathways, which lead to an anti-inflammatory immune response due to type II myeloid cell and Th2 cell differentiation and neuroprotection. In this review, we will focus on the molecular and signaling effects of DMF that lead to changes in peripheral immune cell composition and function, alteration in CNS cell-specific functions, and effect on the blood-brain barrier.

Sustained Type I Interferon Reinforces NK Cell-Mediated Cancer Immunosurveillance during Chronic Virus Infection

The importance of natural killer (NK) cells in the early immune response to viral or bacterial infection is well known. However, the phenotype, function, and physiologic role of NK cells during the late stage of persistent viral infection have not been extensively studied. Here, we characterized NK cells in mice persistently infected with lymphocytic choriomeningitis virus clone 13 and showed that in contrast to NK cells from acutely infected or uninfected mice, NK cells from chronically infected mice expressed a terminally differentiated phenotype, stronger cytotoxicity, and reduced inhibitory receptor expression. In an in vivo tumor model, chronically infected mice exhibited significantly delayed tumor progression in an NK cell-dependent manner. NK cells from chronically infected mice also expressed high STAT1, and blocking the type I interferon (IFN) receptor revealed that type I IFN signaling directly regulated NK cell cytotoxicity. Our findings indicate that sustained type I IFN signaling during chronic viral infection potentiates the cytolytic function of NK cells and contributes to NK cell-dependent host immune surveillance.

Stand by me(mory): Chronic infection diminishes memory pool via IL-6/STAT1

Despite great efforts to eradicate chronic viral infections, they still remain a global health problem. In this issue, Barnstorf et al. (2019. J. Exp. Med. https://doi.org/10.1084/jem.20181589) show that virus-unspecific bystander memory T cells are highly affected during chronic viral infection via IL-6/STAT1. Bystander memory T cells are strongly decimated in numbers and change in phenotype and function during chronic viral infection. These data provide new explanations for immune-mediated problems during chronic virus infections.

Immune Exhaustion: Past Lessons and New Insights from Lymphocytic Choriomeningitis Virus

Lymphocytic choriomeningitis virus (LCMV) is a paradigm-forming experimental system with a remarkable track record of contributing to the discovery of many of the fundamental concepts of modern immunology. The ability of LCMV to establish a chronic infection in immunocompetent adult mice was instrumental for identifying T cell exhaustion and this system has been invaluable for uncovering the complexity, regulators, and consequences of this state. These findings have been directly relevant for understanding why ineffective T cell responses commonly arise during many chronic infections including HIV and HCV, as well as during tumor outgrowth. The principal feature of exhausted T cells is the inability to elaborate the array of effector functions necessary to contain the underlying infection or tumor. Using LCMV to determine how to prevent and reverse T cell exhaustion has highlighted the potential of checkpoint blockade therapies, most notably PD-1 inhibition strategies, for improving cellular immunity under conditions of antigen persistence. Here, we discuss the discovery, properties, and regulators of exhausted T cells and highlight how LCMV has been at the forefront of advancing our understanding of these ineffective responses.