Interferon-producing killer dendritic cells provide a link between innate and adaptive immunity

Predictive biomarkers and initial analysis of maternal immune alterations in postpartum preeclampsia reveal an immune-driven pathology

Introduction

Postpartum preeclampsia (PPPE) is an under-diagnosed condition, developing within 48 hours to 6 weeks following an uncomplicated pregnancy. The etiology of PPPE is still unknown, leaving patients vulnerable and making the identification and treatment of patients requiring postpartum care an unmet need. We aimed to understand the immune contribution to PPPE at the time of diagnosis, as well as uncover the predictive potential of perinatal biomarkers for the early postnatal identification of high-risk patients.

Methods

Placentas were collected at delivery from uncomplicated pregnancies (CTL) and PPPE patients for immunohistochemistry analysis. In this initial study, blood samples in PPPE patients were collected at the time of PPPE diagnosis (48h-25 days postpartum; mean 7.4 days) and compared to CTL blood samples taken 24h after delivery. Single-cell transcriptomics, flow cytometry, intracellular cytokine staining, and the circulating levels of inflammatory mediators were evaluated in the blood.

Results

Placental CD163+ cells and 1st trimester blood pressures can be valuable non-invasive and predictive biomarkers of PPPE with strong clinical application prospects. Furthermore, changes in immune cell populations, as well as cytokine production by CD14+, CD4+, and CD8+ cells, suggested a dampened response with an exhausted phenotype including decreased IL1β, IL12, and IFNγ as well as elevated IL10.

Discussion

Understanding maternal immune changes at the time of diagnosis and prenatally within the placenta in our sizable cohort will serve as groundwork for pre-clinical and clinical research, as well as guiding clinical practice for example in the development of immune-targeted therapies, and early postnatal identification of patients who would benefit from more thorough follow-ups and risk education in the weeks following an uncomplicated pregnancy.

Characterization of tumoricidal activities mediated by a novel immune cell regimen composing interferon-producing killer dendritic cells and tumor-specific cytotoxic T lymphocytes

BACKGROUND

Although immune cell therapy has long been used for treating solid cancer, its efficacy remains limited. Interferon (IFN)-producing killer dendritic cells (IKDCs) exhibit cytotoxicity and present antigens to relevant cells; thus, they can selectively induce tumor-associated antigen (TAA)-specific CD8 T cells and may be useful in cancer treatment. Various protocols have been used to amplify human IKDCs from peripheral sources, but the complexity of the process has prevented their widespread clinical application. Additionally, the induction of TAA-specific CD8 T cells through the adoptive transfer of IKDCs to immunocompromised patients with cancer may be insufficient. Therefore, we developed a method for generating an immune cell-based regimen, Phyduxon-T, comprising a human IKDC counterpart (Phyduxon) and expanded TAA-specific CD8 T cells.

METHODS

Peripheral blood mononuclear cells from ovarian cancer patients were cultured with human interleukin (hIL)-15, hIL-12, and hIL-18 to generate Phyduxon-T. Then, its phenotype, cytotoxicity, and antigen-presenting function were evaluated through flow cytometry using specific monoclonal antibodies.

RESULTS

Phyduxon exhibited the characteristics of both natural killer and dendritic cells. This regimen also exhibited cytotoxicity against primary ovarian cancer cells and presented TAAs, thereby inducing TAA-specific CD8 T cells, as evidenced by the expression of 4-1BB and IFN-γ. Notably, the Phyduxon-T manufacturing protocol effectively expanded IFN-γ-producing 4-1BB+ TAA-specific CD8 T cells from peripheral sources; these cells exhibited cytotoxic activities against ovarian cancer cells.

CONCLUSIONS

Phyduxon-T, which is a combination of natural killer cells, dendritic cells, and TAA-specific CD8 T cells, may enhance the efficacy of cancer immunotherapy.

OMIP-095: 40-Color spectral flow cytometry delineates all major leukocyte populations in murine lymphoid tissues

High-dimensional immunoprofiling is essential for studying host response to immunotherapy, infection, and disease in murine model systems. However, the difficulty of multiparameter panel design combined with a lack of existing murine tools has prevented the comprehensive study of all major leukocyte phenotypes in a single assay. Herein, we present a 40-color flow cytometry panel for deep immunophenotyping of murine lymphoid tissues, including the spleen, blood, Peyer's patches, inguinal lymph nodes, bone marrow, and thymus. This panel uses a robust set of surface markers capable of differentiating leukocyte subsets without the use of intracellular staining, thus allowing for the use of cells in downstream functional experiments or multiomic analyses. Our panel classifies T cells, B cells, natural killer cells, innate lymphoid cells, monocytes, macrophages, dendritic cells, basophils, neutrophils, eosinophils, progenitors, and their functional subsets by using a series of co-stimulatory, checkpoint, activation, migration, and maturation markers. This tool has a multitude of systems immunology applications ranging from serial monitoring of circulating blood signatures to complex endpoint analysis, especially in pre-clinical settings where treatments can modulate leukocyte abundance and/or function. Ultimately, this 40-color panel resolves a diverse array of immune cells on the axes of time, tissue, and treatment, filling the niche for a modern tool dedicated to murine immunophenotyping.

Single-cell RNA sequencing reveals in vivo osteoimmunology interactions between the immune and skeletal systems

BACKGROUND

While osteoimmunology interactions between the immune and skeletal systems are known to play an important role in osteoblast development, differentiation and bone metabolism related disease like osteoporosis, such interactions in either bone microenvironment or peripheral circulation in vivo at the single-cell resolution have not yet been characterized.

METHODS

We explored the osteoimmunology communications between immune cells and osteoblastic lineage cells (OBCs) by performing CellphoneDB and CellChat analyses with single-cell RNA sequencing (scRNA-seq) data from human femoral head. We also explored the osteoimmunology effects of immune cells in peripheral circulation on skeletal phenotypes. We used a scRNA-seq dataset of peripheral blood monocytes (PBMs) to perform deconvolution analysis. Then weighted gene co-expression network analysis (WGCNA) was used to identify monocyte subtype-specific subnetworks. We next used cell-specific network (CSN) and the least absolute shrinkage and selection operator (LASSO) to analyze the correlation of a gene subnetwork identified by WGCNA with bone mineral density (BMD).

RESULTS

We constructed immune cell and OBC communication networks and further identified L-R genes, such as JAG1 and NOTCH1/2, with ossification related functions. We also found a Mono4 related subnetwork that may relate to BMD variation in both older males and postmenopausal female subjects.

CONCLUSIONS

This is the first study to identify numerous ligand-receptor pairs that likely mediate signals between immune cells and osteoblastic lineage cells. This establishes a foundation to reveal advanced and in-depth osteoimmunology interactions to better understand the relationship between local bone microenvironment and immune cells in peripheral blood and the impact on bone phenotypes.

Screening gene signatures for clinical response subtypes of lung transplantation

Lung is the most important organ in the human respiratory system, whose normal functions are quite essential for human beings. Under certain pathological conditions, the normal lung functions could no longer be maintained in patients, and lung transplantation is generally applied to ease patients' breathing and prolong their lives. However, several risk factors exist during and after lung transplantation, including bleeding, infection, and transplant rejections. In particular, transplant rejections are difficult to predict or prevent, leading to the most dangerous complications and severe status in patients undergoing lung transplantation. Given that most common monitoring and validation methods for lung transplantation rejections may take quite a long time and have low reproducibility, new technologies and methods are required to improve the efficacy and accuracy of rejection monitoring after lung transplantation. Recently, one previous study set up the gene expression profiles of patients who underwent lung transplantation. However, it did not provide a tool to predict lung transplantation responses. Here, a further deep investigation was conducted on such profiling data. A computational framework, incorporating several machine learning algorithms, such as feature selection methods and classification algorithms, was built to establish an effective prediction model distinguishing patient into different clinical subgroups, corresponding to different rejection responses after lung transplantation. Furthermore, the framework also screened essential genes with functional enrichments and create quantitative rules for the distinction of patients with different rejection responses to lung transplantation. The outcome of this contribution could provide guidelines for clinical treatment of each rejection subtype and contribute to the revealing of complicated rejection mechanisms of lung transplantation.

Porcine Plasmacytoid Dendritic Cells Are Unique in Their Expression of a Functional NKp46 Receptor

The activating receptor NKp46 shows a unique expression pattern on porcine leukocytes. We showed already that in swine not all NK cells express NKp46 and that CD3⁺NKp46⁺ lymphocytes form a T-cell subset with unique functional properties. Here we demonstrate the expression of NKp46 on CD4^highCD14^-CD172a⁺ porcine plasmacytoid dendritic cells (pDCs). Multicolor flow cytometry analyses revealed that the vast majority of porcine pDCs (94.2% ± 4) express NKp46 ex vivo and have an increased expression on the single-cell level compared to NK cells. FSC/SSC^highCD4^highNKp46⁺ cells produced high levels of IFN-α after CpG ODN 2216 stimulation, a hallmark of pDC function. Following receptor triggering with plate-bound monoclonal antibodies against NKp46, phosphorylation of signaling molecules downstream of NKp46 was analyzed in pDCs and NK cells. Comparable to NK cells, NKp46 triggering led to an upregulation of the phosphorylated ribosomal protein S6 (pS6) in pDCs, indicating an active signaling pathway of NKp46 in porcine pDCs. Nevertheless, a defined effector function of the NK-associated receptor on porcine pDCs could not be demonstrated yet. NKp46-mediated cytotoxicity, as shown for NK cells, does not seem to occur, as NKp46⁺ pDCs did not express perforin. Yet, NKp46 triggering seems to contribute to cytokine production in porcine pDCs, as induction of TNF-α was observed in a small pDC subset after NKp46 cross-linking. To our knowledge, this is the first report on NKp46 expression on pDCs in a mammalian species, showing that this receptor contributes to pDC activation and function.

Interaction of long non-coding RNAs and circular RNAs with microRNAs for the regulation of immunological responses in human cancers

Advancements in single-cell RNA sequencing technologies have enabled us to deconvolve immune system heterogeneity by identification of functionally distinct immune cell subsets in disease and health. Discovery of non-coding RNAs has opened new horizons for re-interpretation of regulatory roles of myriad of cell signaling pathways in immunology and oncology. Role of miRNAs, circular RNAs and long non-coding RNAs (lncRNAs) in the context of immunomodulation has just begun to be uncovered and future studies may further expand the repertoire of non-coding RNAs implicated in the regulatory circuits. One of the most recent and exciting aspect in molecular immunology is the delivery of non-coding RNAs through exosomes to the recipient cells which results in the re-wiring of different pathways and protein networks in recipient cells. Broader understanding of all of the layers of regulation in this system can provide useful information that could be harnessed to rationally translate laboratory findings into clinically effective therapeutics.

Delivery of nanoparticle antigens to antigen-presenting cells: from extracellular specific targeting to intracellular responsive presentation

An appropriate delivery system can improve the immune effects of antigens against various infections or tumors. Antigen-presenting cells (APCs) are specialized to capture and process antigens in vivo, which link the innate and adaptive immune responses. Functionalization of vaccine delivery systems with targeting moieties to APCs is a promising strategy for provoking potent immune responses. Additionally, the internalization and intracellular distribution of antigens are closely related to the initiation of downstream immune responses. With a deeper understanding of the intracellular microenvironment and the mechanisms of antigen presentation, vehicles designed to respond to endogenous and external stimuli can modulate antigen processing and presentation pathways, which are critical to the types of immune response. Here, an overview of extracellular targeting delivery of antigens to APCs and intracellular stimulus-responsiveness strategies is provided, which might be helpful for the rational design of vaccine delivery systems.

Phenotypical Diversification of Early IFNα-Producing Human Plasmacytoid Dendritic Cells Using Droplet-Based Microfluidics

Plasmacytoid dendritic cells (pDCs) are a rare type of highly versatile immune cells that besides their specialized function of massive type I interferon (IFN-I) production are able to exert cytotoxic effector functions. However, diversification upon toll like receptor (TLR)-induced activation leads to highly heterogeneous responses that have not been fully characterized yet. Using droplet-based microfluidics, we showed that upon TLR7/8 and TLR9-induced single-cell activation only 1-3% secretes IFNα, and only small fractions upregulate cytotoxicity markers. Interestingly, this 1-3% of early IFN-producing pDCs, also known as first responders, express high levels of programmed death-ligand 1 (PD-L1) and TNF-related apoptosis-inducing ligand (TRAIL), which makes these hybrid cells similar to earlier described IFN-I producing killer pDCs (IKpDCs). IFN-I priming increases the numbers of IFNα producing cells up to 40%, but does not significantly upregulate the cytotoxicity markers. Besides, these so-called second responders do not show a cytotoxic phenotype as potent as observed for the first responders. Overall, our results indicate that the first responders are the key drivers orchestrating population wide IFN-I responses and possess high cytotoxic potential.

Nanomaterials-Mediated Immunomodulation for Cancer Therapeutics

Immunotherapy holds great promise in overcoming the limitations of conventional regimens for cancer therapeutics. There is growing interest among researchers and clinicians to develop novel immune-strategies for cancer diagnosis and treatment with better specificity and lesser adversity. Immunomodulation-based cancer therapies are rapidly emerging as an alternative approach that employs the host's own defense mechanisms to recognize and selectively eliminate cancerous cells. Recent advances in nanotechnology have pioneered a revolution in the field of cancer therapy. Several nanomaterials (NMs) have been utilized to surmount the challenges of conventional anti-cancer treatments like cytotoxic chemotherapy, radiation, and surgery. NMs offer a plethora of exceptional features such as a large surface area to volume ratio, effective loading, and controlled release of active drugs, tunable dimensions, and high stability. Moreover, they also possess the inherent property of interacting with living cells and altering the immune responses. However, the interaction between NMs and the immune system can give rise to unanticipated adverse reactions such as inflammation, necrosis, and hypersensitivity. Therefore, to ensure a successful and safe clinical application of immunomodulatory nanomaterials, it is imperative to acquire in-depth knowledge and a clear understanding of the complex nature of the interactions between NMs and the immune system. This review is aimed at providing an overview of the recent developments, achievements, and challenges in the application of immunomodulatory nanomaterials (iNMs) for cancer therapeutics with a focus on elucidating the mechanisms involved in the interplay between NMs and the host's immune system.

Cytotoxic and antigen presenting functions of T helper-1-activated dendritic cells

Although primarily defined by their cardinal antigen-presenting function, dendritic cells (DCs) are also equipped with cytotoxic properties. We have recently reported that DCs activated by IFNγ-secreting Th-1 lymphocytes can kill cancer cells and subsequently present the acquired tumor-derived antigens to T lymphocytes both in vitro and in vivo.

Why do human B cells secrete granzyme B? Insights into a novel B-cell differentiation pathway

B cells are generally believed to operate as producers of high affinity antibodies to defend the body against microorganisms, whereas cellular cytotoxicity is considered as an exclusive prerogative of natural killer (NK) cells and cytotoxic T lymphocytes (CTLs). In conflict with this dogma, recent studies have demonstrated that the combination of interleukin-21 (IL-21) and B-cell receptor (BCR) stimulation enables B cells to produce and secrete the active form of the cytotoxic serine protease granzyme B (GrB). Although the production of GrB by B cells is not accompanied by that of perforin as in the case of many other GrB-secreting cells, recent findings suggest GrB secretion by B cells may play a significant role in early antiviral immune responses, in the regulation of autoimmune responses, and in cancer immunosurveillance. Here, we discuss in detail how GrB-secreting B cells may influence a variety of immune processes. A better understanding of the role that GrB-secreting B cells are playing in the immune system may allow for the development and improvement of novel immunotherapeutic approaches against infectious, autoimmune and malignant diseases.

T-bet transduction enhances anti-tumor efficacy of IFN-producing dendritic cell (IKDC) against hepatocellular carcinoma via apoptosis induction

Hepatocellular carcinoma (HCC) remains a public health challenge that requires dedication to develop new treatment options due to its high recurrence rate and poor prognosis. Interferon-producing killer dendritic cell (IKDC) is a subset of INF-γ secreting immune cells that modulates acquired immunity and possesses cytolytic ability. We modified IKDC isolated from the murine spleen with T-bet lentiviral transduction to enhance its cytotoxicity against HCC, and acquired IKDC overexpressing T-bet (T-bet-IKDC) for the first time. T-bet-IKDC has increased INF-γ secretion and surface expression of NKG2D and TRAIL. In vitro study by MTS assay and flow cytometry showed enhanced anti-tumor effect against H22 cells via apoptosis induction in a dose- and time-dependent manner. In vivo study on H22-bearing mice confirmed increased INF-γ secretion, reduced tumor size, increased caspase 3 cleavage, and up-regulation of cytotoxic molecules after T-bet-IKDC administration. The study suggested prospective application of T-bet-IKDC in future immunotherapy for HCC treatment.

Single-Dose Anti-PD-L1/IL-15 Fusion Protein KD033 Generates Synergistic Antitumor Immunity with Robust Tumor-Immune Gene Signatures and Memory Responses

Immunocytokines hold great potential as anticancer agents, as they use a specific antitumor antibody to deliver an immune-activating cytokine directly to the immunosuppressive tumor microenvironment (TME). We have developed a novel immunocytokine (KD033) composed of a fully human, high-affinity antiprogrammed death-ligand 1 (PD-L1) linked to the sushi-domain of the human IL-15/IL-15 receptor alpha (IL-15/IL-15Rα) complex. A murine PD-L1 cross-reactive KD033 surrogate (srKD033) and a nontargeting antibody (ntKD033) were also developed to investigate mechanism of action in murine tumor models. Efficacy analyses showed a robust antitumor effect of single-dose srKD033 in several diverse syngeneic murine tumor models. In a CT26 murine colon tumor model, single-dose srKD033 produced durable antitumor immunity as evidenced by resistance to subsequent tumor rechallenges. Mice responding to srKD033 treatment showed increased retention of PD-L1/IL-15 in the TME which likely facilitated prolonged IL-15-induced expansion of cytotoxic cells. Importantly, target-based PD-L1/IL-15 delivery via srKD033 was well-tolerated and induced significant antitumor activity in murine carcinoma models that are non- or minimally responsive to IL-15 or anti-PD-L1/PD-1 monotherapy.

Production of IFN-γ by splenic dendritic cells during innate immune responses against Francisella tularensis LVS depends on MyD88, but not TLR2, TLR4, or TLR9

Production of IFN-γ is a key innate immune mechanism that limits replication of intracellular bacteria such as Francisella tularensis (Ft) until adaptive immune responses develop. Previously, we demonstrated that the host cell types responsible for IFN-γ production in response to murine Francisella infection include not only natural killer (NK) and T cells, but also a variety of myeloid cells. However, production of IFN-γ by mouse dendritic cells (DC) is controversial. Here, we directly demonstrated substantial production of IFN-γ by DC, as well as hybrid NK-DC, from LVS-infected wild type C57BL/6 or Rag1 knockout mice. We demonstrated that the numbers of conventional DC producing IFN-γ increased progressively over the course of 8 days of LVS infection. In contrast, the numbers of conventional NK cells producing IFN-γ, which represented about 40% of non-B/T IFN-γ-producing cells, peaked at day 4 after LVS infection and declined thereafter. This pattern was similar to that of hybrid NK-DC. To further confirm IFN-γ production by infected cells, DC and neutrophils were sorted from naïve and LVS-infected mice and analyzed for gene expression. Quantification of LVS by PCR revealed the presence of Ft DNA not only in macrophages, but also in highly purified, IFN-γ producing DC and neutrophils. Finally, production of IFN-γ by infected DC was confirmed by immunohistochemistry and confocal microscopy. Notably, IFN-γ production patterns similar to those in wild type mice were observed in cells derived from LVS-infected TLR2, TLR4, and TLR2xTLR9 knockout (KO) mice, but not from MyD88 KO mice. Taken together, these studies demonstrate the pivotal roles of DC and MyD88 in IFN-γ production and in initiating innate immune responses to this intracellular bacterium.

IL-12 regulates the expansion, phenotype, and function of murine NK cells activated by IL-15 and IL-18

NK cells, which are composed of phenotypically and functionally heterogeneous subpopulations, play critical roles in immunity against cancer. The mechanism of generation of distinct subsets such as the effector and regulatory subtypes is unclear. Here, we show that this process comprises several steps, including generation of proliferating, highly cytotoxic cells activated by IL-15/IL-18 and differentiation into distinct cell populations induced with IL-12. Freshly prepared murine splenic NK cells expressed IL-15Rs and IL-18Rs and rapidly began to proliferate following stimulation with IL-15/IL-18. The proliferating NK cells highly expressed various activation markers such as B220, CD49b (DX5), lysosome-associated membrane glycoprotein 1 (LAMP-1), DNAX accessory molecule 1, perforin, and granzyme B and showed reduced expression of natural killer cell p46-related protein (NKp46) and IL-18Rα. These cells exerted strong cytotoxicity against YAC-1 cells, but did not secrete cytokines. IL-12 rapidly activated STAT4 in these cells, induced IFN-γ production, and then upregulated p21 and p27, leading to withdrawal from the cell cycle. In parallel, IL-12-stimulated cells gradually reduced cytotoxicity, decreased expression of activation markers, and instead increased expression of Sca-1, CD25, CD49a, and NKp46. Some IL-15/IL-18-induced cells strongly expressed PD-1, whereas NK cells induced with IL-15/IL-18 and IL-12 expressed high levels of T cell immunoglobulin mucin-3, LAG-3, and natural killer group 2 A. Furthermore, these cells spontaneously secreted IL-10 and TGF-β following prolonged incubation. Thus, IL-12 regulates expansion of NK cells activated with IL-15/IL-18, influences the population size of highly cytotoxic cells, and induces differentiation to unique cells sharing some phenotypes of ILCs.

Single-Cell Transcriptomes Reveal a Complex Cellular Landscape in the Middle Ear and Differential Capacities for Acute Response to Infection

Single-cell transcriptomics was used to profile cells of the normal murine middle ear. Clustering analysis of 6770 transcriptomes identified 17 cell clusters corresponding to distinct cell types: five epithelial, three stromal, three lymphocyte, two monocyte, two endothelial, one pericyte and one melanocyte cluster. Within some clusters, cell subtypes were identified. While many corresponded to those cell types known from prior studies, several novel types or subtypes were noted. The results indicate unexpected cellular diversity within the resting middle ear mucosa. The resolution of uncomplicated, acute, otitis media is too rapid for cognate immunity to play a major role. Thus innate immunity is likely responsible for normal recovery from middle ear infection. The need for rapid response to pathogens suggests that innate immune genes may be constitutively expressed by middle ear cells. We therefore assessed expression of innate immune genes across all cell types, to evaluate potential for rapid responses to middle ear infection. Resident monocytes/macrophages expressed the most such genes, including pathogen receptors, cytokines, chemokines and chemokine receptors. Other cell types displayed distinct innate immune gene profiles. Epithelial cells preferentially expressed pathogen receptors, bactericidal peptides and mucins. Stromal and endothelial cells expressed pathogen receptors. Pericytes expressed pro-inflammatory cytokines. Lymphocytes expressed chemokine receptors and antimicrobials. The results suggest that tissue monocytes, including macrophages, are the master regulators of the immediate middle ear response to infection, but that virtually all cell types act in concert to mount a defense against pathogens.

Glycolipid Stimulation of Invariant NKT Cells Expands a Unique Tissue-Resident Population of Precursors to Mature NK Cells Endowed with Oncolytic and Antimetastatic Properties

Invariant NKT (iNKT) cells are innate-like T lymphocytes that recognize and respond to glycolipid Ags such as α-galactosylceramide (α-GalCer). This unique property has been exploited in clinical trials for multiple malignancies. While investigating mouse iNKT cell responses to α-GalCer in vivo, we found a dramatically enlarged tissue-resident population surprisingly coexpressing select dendritic cell, NK cell, and B cell markers. Further phenotypic and functional analyses revealed the identity of this B220⁺CD11c⁺MHC class II⁺NK1.1⁺ population as precursors to mature NK (pre-mNK) cells, which also expressed high levels of proliferation and tissue retention markers but diminished sphingosine-1-phosphate receptor 1, a receptor that facilitates tissue trafficking. Accordingly, FTY720, a sphingosine-1-phosphate receptor 1 antagonist, failed to prevent pre-mNK cells' intrahepatic accumulation. We found iNKT cell-driven expansion of pre-mNK cells to be dependent on IL-12 and IL-18. Although α-GalCer-transactivated pre-mNK cells lost their capacity to process a model tumor Ag, they selectively expressed granzyme A and directly lysed YAC-1 thymoma cells through granule exocytosis. They also contributed to β2 microglobulin-deficient target cell destruction in vivo. Therefore, α-GalCer treatment skewed pre-mNK cell responses away from an APC-like phenotype and toward killer cell-like functions. Finally, the ability of α-GalCer to reduce the pulmonary metastatic burden of B16-F10 mouse melanoma was partially reversed by in vivo depletion of pre-mNK cells. To our knowledge, our findings shed new light on iNKT cells' mechanism of action and glycolipid-based immunotherapies. Therefore, we introduce pre-mNK cells as a novel downstream effector cell type whose anticancer properties may have been overlooked in previous investigations.

Natural killer cells limit the clearance of senescent lung adenocarcinoma cells

Senescence is an important p53-controlled tumor suppressor program that not only opposes the proliferation of cancer cells but also promotes their immune-mediated clearance in certain contexts. In hepatocellular cancer, p53 induction promotes an innate immune cell-mediated clearance of senescent cells wherein natural killer (NK) cells seem to play the primary sentinel role. Whether NK cells also surveil cancer cells in other tumor types when p53 is activated to promote a senescence response is unknown. To identify the role that NK and other innate immune cell types have on the surveillance and destruction of lung adenocarcinoma cells, we developed an orthotopic transplantation model where p53 gene function could be restored to induce senescence after successful engraftment of tumor cells in the mouse lung. Contrary to precedent, we found that NK cells actually limited the efficient clearance of tumor cells from the mouse lung after p53 restoration. Instead, activation of p53 induced the infiltration of monocytes, neutrophils, and interstitial macrophages. Loss of NK cells further promoted expansion of these inflammatory cell types and tumor clearance after p53 restoration. These observations suggest that NK cell responses to p53 activation in lung adenocarcinoma is distinct from those found in other tumor types and that diverse innate immune cell populations may play context-dependent roles during tumor immune surveillance. Further, our data provide an impetus to understand the broader mechanisms that regulate cancer cell destruction by multiple cell types of the innate immune system and distinct cancer contexts.

Importance of TRAIL Molecular Anatomy in Receptor Oligomerization and Signaling. Implications for Cancer Therapy

(TNF)-related apoptosis-inducing ligand (TRAIL) is able to activate the extrinsic apoptotic pathway upon binding to DR4/TRAIL-R1 and/or DR5/TRAIL-R2 receptors. Structural data indicate that TRAIL functions as a trimer that can engage three receptor molecules simultaneously, resulting in receptor trimerization and leading to conformational changes in TRAIL receptors. However, receptor conformational changes induced by the binding of TRAIL depend on the molecular form of this death ligand, and not always properly trigger the apoptotic cascade. In fact, TRAIL exhibits a much stronger pro-apoptotic activity when is found as a transmembrane protein than when it occurs as a soluble form and this enhanced biological activity is directly linked to its ability to cluster TRAIL receptors in supra-molecular structures. In this regard, cells involved in tumor immunosurveillance, such as activated human T cells, secrete endogenous TRAIL as a transmembrane protein associated with lipid microvesicles called exosomes upon T-cell reactivation. Consequently, it seems clear that a proper oligomerization of TRAIL receptors, which leads to a strong apoptotic signaling, is crucial for inducing apoptosis in cancer cells upon TRAIL treatment. In this review, the current knowledge of oligomerization status of TRAIL receptors is discussed as well as the implications for cancer treatment when using TRAIL-based therapies.

Effect of Multiple Vaccinations with Tumor Cell-Based Vaccine with Codon-Modified GM-CSF on Tumor Growth in a Mouse Model

Ectopic expression of codon-modified granulocyte-macrophage colony-stimulating factor (cGM-CSF) in TC-1 cells (TC-1/cGM-CSF), a model cell line for human papillomavirus (HPV)-infected cervical cancer cells, increased the expression level of GM-CSF and improved the efficacy of tumor cell-based vaccines in a cervical cancer mouse model. The number of vaccine doses required to induce a long-term immune response in a cervical cancer mouse model is poorly understood. Here, we investigated one, three, and five doses of the irradiated TC-1/cGM-CSF vaccine to determine which dose was effective in inducing a greater immune response and the suppression of tumors. Our findings showed that three doses of irradiated TC-1/cGM-CSF vaccine elicited slower tumor growth rates and enhanced survival rates compared with one dose or five doses of irradiated TC-1/cGM-CSF vaccine. Consistently, mice vaccinated with three doses of irradiated TC-1/cGM-CSF vaccine exhibited stronger interferon gamma (IFN-γ) production in HPV E7-specific CD8⁺ T cells and CD4⁺ T cells. A higher percentage of natural killer cells and interferon-producing killer dendritic cells (IKDCs) appeared in the splenocytes of the mice vaccinated with three doses of irradiated TC-1/cGM-CSF vaccine compared with those of the mice vaccinated with one dose or five doses of irradiated TC-1/cGM-CSF vaccine. Our findings demonstrate that single or multiple vaccinations, such as five doses, with irradiated TC-1/cGM-CSF vaccine suppressed the immune response, whereas three doses of irradiated TC-1/cGM-CSF vaccine elicited a greater immune response and subsequent tumor suppression.

CRTAM+ NK cells endowed with suppressor properties arise in leukemic bone marrow

Due to their increasing rates of morbidity and mortality, childhood malignancies are considered a global health priority, with acute lymphoblastic leukemias (ALLs) showing the highest incidence worldwide. Control of malignant clone emergence and the subsequent normal-leukemic hematopoietic cell out-competition require antitumor monitoring mechanisms. Investigation of cancer surveillance innate cells may be critical to understand the mechanisms contributing in either disease progression or relapse, and to promote displacement of leukemic hematopoiesis by the normal counterpart. We report here that NK cell production is less and low hematopoietic progenitor numbers contribute to this defect. By investigating the expression of the activation molecule class I restricted T-cell associated molecule (CRTAM) along the hematopoietic lineage differentiation pathway, we have identified lymphoid precursor populations coexpressing CD34, CD56/CD3/CD19, and CRTAM as the earliest developmental stage where activation may take place in specialized niches that display the ligand nectin-like-2. Of note, bone marrow (BM) from patients with ALL revealed high contents of preactivated CD56^high NK cells expressing CRTAM and endowed with an exhaustion-like phenotype and the functional capability of producing IL-10 and TGF-β in vitro. Our findings suggest, for the first time, that the tumor microenvironment in ALL directly contribute to exhaustion of NK cell functions by the CRTAM/Necl-2 interaction, and that the potential regulatory role of exhausted-like NK cells may favor malignant progression at the expense of anti-tumor responses. Phenotypic and functional identity of this unique suppressor-like NK cell population within the leukemic BM would be of special interest for the pathobiology of ALL and development of targeting strategies.

IL-15 Generates IFN-γ-producing Cells Reciprocally Expressing Lymphoid-Myeloid Markers during Dendritic Cell Differentiation

Recently, interest in IL-15-differentiated cells has increased; however, the phenotypic definition of IL-15-differentiated bone marrow-derived cells (IL-15-DBMCs) is still under debate, particularly the generation of IFN-γ-producing innate cells such as premature NK (pre-mNK) cells, natural killer dendritic cells (NKDCs), interferon-producing killer dendritic cells (IKDCs), and type 1 innate lymphoid cells (ILC1s), all of which are IL-15-dependent. Here, we revisited the immunophenotypic characteristics of IFN-γ-producing IL-15-DBMCs and their functional role in the control of intracellular Mycobacterium tuberculosis (Mtb) infection. When comparing the cytokine levels between bone marrow-derived dendritic cells (BMDCs) and IL-15-DBMCs upon stimulation with various TLR agonists, only the CD11c^int population of IL-15-DBMCs produced significant levels of IFN-γ, decreased levels of MHC-II, and increased levels of B220. Neither BMDCs nor IL-15-DBMCs were found to express DX5 or NK1.1, which are representative markers for the NK cell lineage and IKDCs. When the CD11c^intB220⁺ population of IL-15-DBMCs was enriched, the Thy1.2⁺Sca-1⁺ population showed a marked increase in IFN-γ production. In addition, while depletion of the B220⁺ and Thy1.2⁺ populations of IL-15-DBMCs, but not the CD19⁺ population, inhibited IFN-γ production, enrichment of these cell populations increased IFN-γ. Ultimately, co-culture of sorted IFN-γ-producing B220⁺Thy1.2⁺ IL-15-DBMCs with Mtb-infected macrophages resulted in control of the intracellular growth of Mtb via the IFN-γ-nitric oxide axis in a donor cell number-dependent manner. Taken together, the results indicate that IFN-γ-producing IL-15-DBMCs could be redefined as CD11c^intB220⁺Thy1.2⁺Sca-1⁺ cells, which phenotypically resemble both IKDCs and ILC1s, and may have therapeutic potential for controlling infectious intracellular bacteria such as Mtb.

Regulatory IFN-γ-producing killer dendritic cells are enhanced in B6.MLR-Faslpr /J lupus-prone mice

A novel cell population denominated IFN-γ-producing killer dendritic cells (IKDCs) have been recently described. These cells are lymphocytes lacking B- or T- receptors, but they can be identified by the presence of B220⁺ CD38⁺ CD49b⁺ and low CD11c, among other cell surface markers. The main characteristics of IKDCs are the production of IFN-γ and the ability to spontaneously kill tumor cells. We found that this population increases in B6.MLR-Fas^lpr /J mice. Interestingly, IKDCs increase with age and are more abundant in mice older than 6 months onward. To analyze whether these cells have any role in the induction of the lupus-like phenotype in the B6.MLR-Fas^lpr /J mice, IKDCs were purified and transferred into 6-month-old B6.MRL-Fas^lpr /J mice, then the presence of anti-nuclear antibodies (ANAS) and anti-dsDNA antibodies were analyzed 2 and 4 months after the transfer. The results showed a reduction in the levels of these autoantibodies and increased survival of these mice, indicating that these cells may have a regulatory function. In vitro assays demonstrated that IKDCs reduced the proliferation of both autoreactive B and T cells, suggesting that these may be the mechanisms used by these cells to ameliorate the lupus-like phenotype in the B6.MRL-Fas^lpr /J mice.

Future of Muse Cells

Discovered nearly 10 years ago by Professor Mari Dezawa and her colleagues, Muse cells are entering clinical trials faster than any other stem cell for three reasons. First, Muse cells have multiple fail-safe mechanisms to keep themselves from growing out of control and do not form tumors. In contrast, embryonic stem cells and induced pluripotent stem cells form tumors and must be differentiated before transplantation. Second, Muse cells possess potent anti-immune mechanisms, including human leukocyte antigen G and indoleamine 2,3-dioxygenase that prevent both cellular and humoral immunity. Muse cells engraft even though they do not match HLA antigens with the host. Third, Muse cells are able to determine what kind and how many cells they need to make for tissue repair. While the mechanisms responsible for these traits are not well understood, Muse cells are able to enter severely injured tissues of all kinds and repair them. Study of mechanisms underlying these traits of Muse cells is likely to yield new therapies for cancer prevention, autoimmune diseases, and repair of injured tissues. The future is bright for Muse cells.

Beyond the vicious cycle: The role of innate osteoimmunity, automimicry and tumor-inherent changes in dictating bone metastasis

Bone metastasis is a fatal consequence of a subset of solid malignancies that fail to respond to conventional therapies. While a myriad of factors contribute to osteotropism and disseminated cell survival and outgrowth in bone, efforts to inhibit tumor cell growth in the bone-metastatic niche have largely relied on measures that disrupt the bi-directional interactions between bone resident and tumor cells. However, the targeting of isolated stromal interactions has proven ineffective to date in inhibiting bone-metastatic progression and patient mortality. Osteoimmune regulation is now emerging as a critical determinant of metastatic growth in the bone microenvironment. While this has highlighted the importance of innate immune populations in dictating the temporal development of overt bone metastases, the osteoimmunological processes that underpin tumor cell progression in bone remain severely underexplored. Along with tumor-intrinsic alterations that occur specifically within the bone microenvironment, innate osteoimmunological crosstalk poses an exciting area of future discovery and therapeutic development. Here we review current knowledge of the unique exchange that occurs between bone resident cells, innate immune populations and tumor cells that leads to the establishment of a tumor-permissive milieu.

Analysis of the regulatory function of natural killer cells from patients with systemic lupus erythematosus

Natural killer (NK) cells participate in the regulation of the immune response. However, the immunomodulatory function of NK cells in systemic lupus erythematosus (SLE) is not well understood. The aim of this study was to evaluate the regulatory function of NK cells in SLE patients and to identify the NK cells involved in the pathogenesis of this complex disease. We analysed the expression of NK receptors and co-stimulatory molecules in peripheral NK cells (CD3^- CD56⁺ ) from SLE patients, as well as the numbers of human leucocyte antigen D-related (HLA-DR)/CD11c⁺ NK cells. In addition, NK cell regulatory function was assessed by the detection of NK cell-mediated dendritic cell (DC) lysis. We found that SLE patients showed increased numbers of immunoglobulin-like transcript 2 (ILT2)⁺ , CD86⁺ and CD134⁺ NK cells. Furthermore, NK cells from SLE patients induced higher levels of DC lysis. We were able to identify a new subset of NK cells co-expressing CD11c and HLA-DR. These atypical NK cells were increased in SLE patients when compared with controls. We have identified an expanded new subset of NK cells in SLE patients. This is the first study, to our knowledge, which demonstrates that NK cells in SLE patients have an altered phenotype with a high expression of receptors characteristic of dendritic cells. Our results suggest that the impairment in the regulatory function of NK cells, together with the increased number of DC-like NK cells, could play an important role in the development of SLE and highlight the importance of NK cells as a future therapeutic target.

Dendritic cell targeted vaccines: Recent progresses and challenges

Dendritic cells (DCs) are known to be a set of morphology, structure and function of heterogeneous professional antigen presenting cells (APCs), as well as the strongest functional antigen presenting cells, which can absorb, process and present antigens. As the key regulators of innate and adaptive immune responses, DCs are at the center of the immune system and capable of interacting with both B cells and T cells, thereby manipulating the humoral and cellular immune responses. DCs provide an essential link between the innate and adaptive immunity, and the strong immune activation function of DCs and their properties of natural adjuvants, make them a valuable target for antigen delivery. Targeting antigens to DC-specific endocytic receptors in combination with the relevant antibodies or ligands along with immunostimulatory adjuvants has been recently recognized as a promising strategy for designing an effective vaccine that elicits a strong and durable T cell response against intracellular pathogens and cancer. This opinion article provides a brief summary of the rationales, superiorities and challenges of existing DC-targeting approaches.

Single-cell RNA-seq reveals new types of human blood dendritic cells, monocytes, and progenitors

Dendritic cells (DCs) and monocytes play a central role in pathogen sensing, phagocytosis, and antigen presentation and consist of multiple specialized subtypes. However, their identities and interrelationships are not fully understood. Using unbiased single-cell RNA sequencing (RNA-seq) of ~2400 cells, we identified six human DCs and four monocyte subtypes in human blood. Our study reveals a new DC subset that shares properties with plasmacytoid DCs (pDCs) but potently activates T cells, thus redefining pDCs; a new subdivision within the CD1C+ subset of DCs; the relationship between blastic plasmacytoid DC neoplasia cells and healthy DCs; and circulating progenitor of conventional DCs (cDCs). Our revised taxonomy will enable more accurate functional and developmental analyses as well as immune monitoring in health and disease.

The Impact of the Interferon/TNF-Related Apoptosis-Inducing Ligand Signaling Axis on Disease Progression in Respiratory Viral Infection and Beyond

Interferons (IFNs) are well described to be rapidly induced upon pathogen-associated pattern recognition. After binding to their respective IFN receptors and activation of the cellular JAK/signal transducer and activator of transcription signaling cascade, they stimulate the transcription of a plethora of IFN-stimulated genes (ISGs) in infected as well as bystander cells such as the non-infected epithelium and cells of the immune system. ISGs may directly act on the invading pathogen or can either positively or negatively regulate the innate and adaptive immune response. However, IFNs and ISGs do not only play a key role in the limitation of pathogen spread but have also been recently found to provoke an unbalanced, overshooting inflammatory response causing tissue injury and hampering repair processes. A prominent regulator of disease outcome, especially in-but not limited to-respiratory viral infection, is the IFN-dependent mediator TRAIL (TNF-related apoptosis-inducing ligand) produced by several cell types including immune cells such as macrophages or T cells. First described as an apoptosis-inducing agent in transformed cells, it is now also well established to rapidly evoke cellular stress pathways in epithelial cells, finally leading to caspase-dependent or -independent cell death. Hereby, pathogen spread is limited; however in some cases, also the surrounding tissue is severely harmed, thus augmenting disease severity. Interestingly, the lack of a strictly controlled and well balanced IFN/TRAIL signaling response has not only been implicated in viral infection but might furthermore be an important determinant of disease progression in bacterial superinfections and in chronic respiratory illness. Conclusively, the IFN/TRAIL signaling axis is subjected to a complex modulation and might be exploited for the evaluation of new therapeutic concepts aiming at attenuation of tissue injury.

Prostaglandin E2 As a Modulator of Viral Infections

Viral infections are a major cause of infectious diseases worldwide. Inflammation and the immune system are the major host defenses against these viral infection. Prostaglandin E2 (PGE2), an eicosanoid generated by cyclooxygenases, has been shown to modulate inflammation and the immune system by regulating the expression/concentration of cytokines. The effect of PGE2 on viral infection and replication is cell type- and virus-family-dependent. The host immune system can be modulated by PGE2, with regards to immunosuppression, inhibition of nitrogen oxide (NO) production, inhibition of interferon (IFN) and apoptotic pathways, and inhibition of viral receptor expression. Furthermore, PGE2 can play a role in viral infection directly by increasing the production and release of virions, inhibiting viral binding and replication, and/or stimulating viral gene expression. PGE2 may also have a regulatory role in the induction of autoimmunity and in signaling via Toll-like receptors. In this review the known effects of PGE2 on the pathogenesis of various infections caused by herpes simplex virus, rotavirus, influenza A virus and human immunodeficiency virus as well the therapeutic potential of PGE2 are discussed.

Interferon-α-inducible Dendritic Cells Matured with OK-432 Exhibit TRAIL and Fas Ligand Pathway-mediated Killer Activity

Active human dendritic cells (DCs), which efficiently induce immune responses through their functions as antigen-presenting cells, exhibit direct anti-tumour killing activity in response to some pathogens and cytokines. These antigen-presenting and tumour killing abilities may provide a breakthrough in cancer immunotherapy. However, the mechanisms underlying this killer DC activity have not been fully proven, despite the establishment of interferon-α (IFN-α)-generated killer DCs (IFN-DCs). Here mature IFN-DCs (mIFN-DCs), generated from IFN-DCs primed with OK-432 (streptococcal preparation), exhibited elevated expression of CD86 and human leukocyte antigen-DR (minimum criteria for DC vaccine clinical trials) as well as antigen-presenting abilities comparable with those of mature IL-4-DCs (mIL-4-DCs). Interestingly, the killing activity of mIFN-DCs, which correlated with the expression of CD56 (natural killer cell marker) and was activated via the tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) and Fas ligand pathway, was stronger than that of IFN-DCs and remarkably stronger than that of mIL-4-DCs. Therefore, mIFN-DCs exhibit great potential as an anti-cancer vaccine that would promote both acquired immunity and direct tumour killing.

Novel oncolytic viral therapies in patients with thoracic malignancies

Oncolytic virotherapy is the use of replication-competent viruses to treat malignancies. The potential of oncolytic virotherapy as an approach to cancer therapy is based on historical evidence that certain viral infections can cause spontaneous remission of both hematologic and solid tumor malignancies. Oncolytic virotherapy may eliminate cancer cells through either direct oncolysis of infected tumor cells or indirect immune-mediated oncolysis of uninfected tumor cells. Recent advances in oncolytic virotherapy include the development of a wide variety of genetically attenuated RNA viruses with precise cellular tropism and the identification of cell-surface receptors that facilitate viral transfer to the tissue of interest. Current research is also focused on targeting metastatic disease by sustaining the release of progeny viruses from infected tumor cells and understanding indirect tumor cell killing through immune-mediated mechanisms of virotherapy. The purpose of this review is to critically evaluate recent evidence on the clinical development of tissue-specific viruses capable of targeting tumor cells and eliciting secondary immune responses in lung cancers and mesothelioma.

CD8αα+MHC Class II+ Cell with the Capacity To Terminate Autoimmune Inflammation Is a Novel Antigen-Presenting NK-like Cell in Rats

Discovery of immune tolerance mechanisms, which inhibit pre-existing autoimmune inflammation, may provide us with new strategies for treating autoimmune diseases. We have identified a CD8αα⁺MHC class II⁺ cell with professional APC capacity during our investigation on spontaneous recovery from autoimmune glomerulonephritis in a rat model. This cell actively invades inflamed target tissue and further terminates an ongoing autoimmune inflammation by selective killing of effector autoreactive T cells. In this study, we show that this cell used a cytotoxic machinery of Ly49s⁺ NK cells in killing of target T cells. Thus, this CD8αα⁺MHC class II⁺ cell was a dually functional Ag-presenting NK-like (AP-NK) cell. Following its coupling with target T cells through Ag presentation, killing stimulatory receptor Ly49s6 and coreceptor CD8αα on this cell used rat nonclassic MHC class I C/E16 on the target T cells as a ligand to initiate killing. Thus, activated effector T cells with elevated expression of rat nonclassic MHC class I C/E16 were highly susceptible to the killing by the CD8αα⁺ AP-NK cell. Granule cytolytic perforin/granzyme C from this cell subsequently mediated cytotoxicity. Thus, inhibition of granzyme C effectively attenuated the killing. As it can recognize and eliminate effector autoreactive T cells in the inflamed target tissue, the CD8αα⁺ AP-NK cell not only represents a new type of immune cell involved in immune tolerance, but it also is a potential candidate for developing a cell-based therapy for pre-existing autoimmune diseases.

Early Differentiation of Human CD11c+NK Cells with γδ T Cell Activation Properties Is Promoted by Dialyzable Leukocyte Extracts

Reconstitution of the hematopoietic system during immune responses and immunological and neoplastic diseases or upon transplantation depends on the emergent differentiation of hematopoietic stem/progenitor cells within the bone marrow. Although in the last decade the use of dialyzable leukocyte extracts (DLE) as supportive therapy in both infectious and malignant settings has increased, its activity on the earliest stages of human hematopoietic development remains poorly understood. Here, we have examined the ability of DLE to promote replenishment of functional lymphoid lineages from CD34⁺ cells. Our findings suggest that DLE increases their differentiation toward a conspicuous CD56⁺CD16⁺CD11c⁺ NK-like cell population endowed with properties such as IFNy production, tumor cell cytotoxicity, and the capability of inducing γδ T lymphocyte proliferation. Of note, long-term coculture controlled systems showed the bystander effect of DLE-stromal cells by providing NK progenitors with signals to overproduce this cell subset. Thus, by direct effect on progenitor cells and through activation and remodeling of the supporting hematopoietic microenvironment, DLE may contribute a robust innate immune response by promoting the emerging lymphopoiesis of functional CD11c⁺ NK cells in a partially TLR-related manner. Unraveling the identity and mechanisms of the involved DLE components may be fundamental to advance the NK cell-based therapy field.

Myeloid leukemia with transdifferentiation plasticity developing from T-cell progenitors

Unfavorable patient survival coincides with lineage plasticity observed in human acute leukemias. These cases are assumed to arise from hematopoietic stem cells, which have stable multipotent differentiation potential. However, here we report that plasticity in leukemia can result from instable lineage identity states inherited from differentiating progenitor cells. Using mice with enhanced c-Myc expression, we show, at the single-cell level, that T-lymphoid progenitors retain broad malignant lineage potential with a high capacity to differentiate into myeloid leukemia. These T-cell-derived myeloid blasts retain expression of a defined set of T-cell transcription factors, creating a lymphoid epigenetic memory that confers growth and propagates myeloid/T-lymphoid plasticity. Based on these characteristics, we identified a correlating human leukemia cohort and revealed targeting of Jak2/Stat3 signaling as a therapeutic possibility. Collectively, our study suggests the thymus as a source for myeloid leukemia and proposes leukemic plasticity as a driving mechanism. Moreover, our results reveal a pathway-directed therapy option against thymus-derived myeloid leukemogenesis and propose a model in which dynamic progenitor differentiation states shape unique neoplastic identities and therapy responses.

Different morphology, stage and treatment affect immune cell infiltration and long-term outcome in patients with non-small-cell lung carcinoma

AIMS

Development of effective immune-based therapies for patients with non-small-cell lung carcinoma (NSCLC) depends on an accurate characterization of complex interactions that occur between immune cells and the tumour environment.

METHODS AND RESULTS

Innate and adaptive immune responses were evaluated in relation to prognosis in 65 patients with surgically excised NSCLC. Immunohistochemistry and morphometry were used to determine the abundance and distribution of immune cells. We found low numbers of immune cells and levels of cytokines in the tumour environment when compared with surrounding parenchyma. Smoking was associated inversely with the adaptive immune response and directly with innate immunity. We observed a prominent adaptive immune response in squamous cell carcinomas (SCC) but greater innate immune responses in adenocarcinomas and large cell carcinomas. Cox model analysis showed a low risk of death for smoking <41 packs/year, N0 tambour stage, squamous carcinoma, CD4(+)  > 16.81% and macrophages/monocytes >4.5%. Collectively, the data indicate that in NSCLC there is not a substantive local immune cell infiltrate within the tumour.

CONCLUSION

Although immune cell infiltration is limited in NSCLC it appears to have an impact on prognosis and this may be of relevance for new immunotherapeutic approaches.

Understanding Interferon Subtype Therapy for Viral Infections: Harnessing the Power of the Innate Immune System

Type I and III interferons (IFNs) of the innate immune system belong to a polygenic family, however the individual subtype mediators of the antiviral response in viral infections have been hindered by a lack of reagents. Evaluation studies using different IFN subtypes have distinguished distinct protein properties with different efficacies towards different viruses, opening promising avenues for immunotherapy. This review largely focuses on the application of IFN-α/β and IFN-λ therapies for viral infections, influenza, herpes, HIV and hepatitis. Such IFN subtype therapies may help to cure patients with virus infections where no vaccine exists. The ability of cell types to secrete a number of IFN subtypes from a multi-gene family may be an intuitive counterattack on viruses that evade IFN subtype responses. Hence, clinical use of virus-targeted IFN subtypes may restore antiviral immunity in viral infections. Accumulating evidence suggests that individual IFN subtypes have differential efficacies in selectively activating immune cell subsets to enhance antiviral immune responses leading to production of sustained B and T cell memory. Cytokine therapy can augment innate immunity leading to clearance of acute virus infections but such treatments may have limited effects on chronic virus infections that establish lifelong latency. Therefore, exploiting individual IFN subtypes to select those with the ability to sculpt protective responses as well as reinstating those targeted by viral evasion mechanisms may inform development of improved antiviral therapy.

Resistance of novel mouse strains different in MHC class I and the NKC domain to the development of experimental tumors

To elucidate the immunological mechanisms critical for tumor progression, we bred novel mouse strains, different in the NKC and H-2D domains. We used inbreeding to generate hybrids of Balb/c and C57BL/6 of stable H-2Db+d-NK1.1neg and H-2Db-d+NK1.1high phenotypes. We analyzed the growth of three established MHC class I-deficient tumor cell lines: TC-1/A9 tumor (HPV-associated) and B16F10 melanoma, both syngeneic to C57BL/6, and the MCB8 (3-methycholanthrene-induced tumor) syngeneic to Balb/c. Furthermore, we induced colorectal carcinoma by azoxymethane-DSS treatment to test the susceptibility to chemically-induced primary cancer. We found that the novel strains spontaneously regressed the tumor transplants syngeneic to both Balb/c (MCB8) and C57BL/6 (B16F10 and TC-1/A9) mice. The H2-Db+d-NK1.1neg, but not the H2-Db-d+NK1.1high strain was also highly resistant to chemically-induced colorectal cancer in comparison to the parental mice. The immune changes during TC-1/A9 cancer development involved an increase of the NK cell distribution in the peripheral blood and spleen along with higher expression of NKG2D activation antigen; this was in correlation with the time-dependent rise of cytotoxic activity in comparison to C57BL/6 mice. The TC-1/A9 cancer regression was accompanied by higher proportion of B cells in the spleen and B220+/CD86+ activated antigen-presenting B cells distributed in the lymphoid organs, as well as in the periphery. The changes in the T-cell population were represented mainly by the prevalence of T helper cells reflected by grown CD4/CD8 ratio, most prominent in the b+d-NK1.1neg strain. The results of the present study imply usefulness of the two novel mouse strains as an experimental model for further studies of tumor resistance mechanisms.

A role for pre-mNK cells in tumor progression

The innate and adaptive immune systems have evolved together to fight infection and cancerous tissues. The innate immune system emerges first with the adaptive immune system following, both ostensibly being bridged by dendritic cells (DC). Recently cells have emerged that possess characteristics of both innate and adaptive immune cell qualities, termed interferon-producing killer dendritic cells (IKDCs). These cells have an indistinct origin that is not well understood. They appear to have more NK cell attributes than DC but purportedly can regulate the immune system similar to immunoregulatory NK cells. Because of this, they have been renamed pre-mNK cells (pre-mature NK cells). We argue in this commentary that pre-mNK cells may contribute to cancer recurrence.

Lipid-enveloped zinc phosphate hybrid nanoparticles for codelivery of H-2K(b) and H-2D(b)-restricted antigenic peptides and monophosphoryl lipid A to induce antitumor immunity against melanoma

Nanoimmunotherapy, the application of nanotechnology for sustained and targeted delivery of antigens to dendritic cells (DCs), has attracted much attention in stimulating antigen-specific immune response for antitumor therapy. In order to in situ deliver antigens to DCs for efficient antigen presentation and subsequent induction of strong cytotoxic T lymphocytes (CTL) response, here we developed a multi-peptide (TRP2180-188 and HGP10025-33) and toll-like receptor 4 agonist (monophosphoryl lipid A) codelivery system based on lipid-coated zinc phosphate hybrid nanoparticles (LZnP NPs). This delivery system equips with the chelating property of zinc to realize the high encapsulation efficiency with antigenic peptides and the influence on immune system with adjuvant-like feature. The combination of H-2K(b) and H-2D(b)-restricted peptides could provide multiple epitopes as the target of specific MHC alleles, making tumor more difficult to escape from the surveillance of immune system. The formulated LZnP nano-vaccine with the size of 30nm and outer leaflet lipid exhibited antitumor immunity as the secretion of cytokines in vitro and increased CD8(+) T cell response from IFN-γ ELISPOT analysis ex vivo. The antitumor effects were further evidenced from the prophylactic, therapeutic and metastatic melanoma tumor models compared with free antigens and single peptide-loaded nano-vaccines. These results validate the benefit of LZnP-based vaccine for antitumor immunity and indicate that co-delivery of tumor antigens along with adjuvant may be an optimized strategy for tumor immunotherapy.

Characterization of Human CD8(+)TCR(-) Facilitating Cells In Vitro and In Vivo in a NOD/SCID/IL2rγ(null) Mouse Model

CD8(+)/TCR(-) facilitating cells (FCs) in mouse bone marrow (BM) significantly enhance engraftment of hematopoietic stem/progenitor cells (HSPCs). Human FC phenotype and mechanism of action remain to be defined. We report, for the first time, the phenotypic characterization of human FCs and correlation of phenotype with function. Approximately half of human FCs are CD8(+)/TCR(-)/CD56 negative (CD56(neg)); the remainder are CD8(+)/TCR(-)/CD56 bright (CD56(bright)). The CD56(neg) FC subpopulation significantly promotes homing of HSPCs to BM in nonobese diabetic/severe combined immunodeficiency/IL-2 receptor γ-chain knockout mouse recipients and enhances hematopoietic colony formation in vitro. The CD56(neg) FC subpopulation promotes rapid reconstitution of donor HSPCs without graft-versus-host disease (GVHD); recipients of CD56(bright) FCs plus HSPCs exhibit low donor chimerism early after transplantation, but the level of chimerism significantly increases with time. Recipients of HSPCs plus CD56(neg) or CD56(bright) FCs showed durable donor chimerism at significantly higher levels in BM. The majority of both FC subpopulations express CXCR4. Coculture of CD56(bright) FCs with HSPCs upregulates cathelicidin and β-defensin 2, factors that prime responsiveness of HSPCs to stromal cell-derived factor 1. Both FC subpopulations significantly upregulated mRNA expression of the HSPC growth factors and Flt3 ligand. These results indicate that human FCs exert a direct effect on HSPCs to enhance engraftment. Human FCs offer a potential regulatory cell-based therapy for enhancement of engraftment and prevention of GVHD.

Role of Mitochondrial DNA in Septic AKI via Toll-Like Receptor 9

Toll-like receptor 9 (TLR9) contributes to the development of polymicrobial septic AKI. However, the mechanisms that activate the TLR9 pathway and cause kidney injury during sepsis remain unknown. To determine the role of mitochondrial DNA (mtDNA) in TLR9-associated septic AKI, we established a cecal ligation and puncture (CLP) model of sepsis in wild-type (WT) and Tlr9-knockout (Tlr9KO) mice. We evaluated systemic circulation and peritoneal cavity dynamics and immune response and tubular mitochondrial dysfunction to determine upstream and downstream effects on the TLR9 pathway, respectively. CLP increased mtDNA levels in the plasma and peritoneal cavity of WT and Tlr9KO mice in the early phase, but the increase in the peritoneal cavity was significantly higher in Tlr9KO mice than in WT mice. Concomitantly, leukocyte migration to the peritoneal cavity increased, and plasma cytokine production and splenic apoptosis decreased in Tlr9KO mice compared with WT mice. Furthermore, CLP-generated renal mitochondrial oxidative stress and mitochondrial vacuolization in the proximal tubules in the early phase were reversed in Tlr9KO mice. To elucidate the effects of mtDNA on immune response and kidney injury, we intravenously injected mice with mitochondrial debris (MTD), including substantial amounts of mtDNA. MTD caused an immune response similar to that induced by CLP, including upregulated levels of plasma IL-12, splenic apoptosis, and mitochondrial injury, but this effect was attenuated by Tlr9KO. Moreover, MTD-induced renal mitochondrial injury was abolished by DNase pretreatment. These findings suggest that mtDNA activates TLR9 and contributes to cytokine production, splenic apoptosis, and kidney injury during polymicrobial sepsis.

Agonist antibody that induces human malignant cells to kill one another

An attractive, but as yet generally unrealized, approach to cancer therapy concerns discovering agents that change the state of differentiation of the cancer cells. Recently, we discovered a phenomenon that we call "receptor pleiotropism" in which agonist antibodies against known receptors induce cell fates that are very different from those induced by the natural agonist to the same receptor. Here, we show that one can take advantage of this phenomenon to convert acute myeloblastic leukemic cells into natural killer cells. Upon induction with the antibody, these leukemic cells enter into a differentiation cascade in which as many as 80% of the starting leukemic cells can be differentiated. The antibody-induced killer cells make large amounts of perforin, IFN-γ, and granzyme B and attack and kill other members of the leukemic cell population. Importantly, induction of killer cells is confined to transformed cells, in that normal bone marrow cells are not induced to form killer cells. Thus, it seems possible to use agonist antibodies to change the differentiation state of cancer cells into those that attack and kill other members of the malignant clone from which they originate.

Perforin-Positive Dendritic Cells Exhibit an Immuno-regulatory Role in Metabolic Syndrome and Autoimmunity

Emerging evidence suggests that immunological mechanisms underlie metabolic control of adipose tissue. Here, we have shown the regulatory impact of a rare subpopulation of dendritic cells, rich in perforin-containing granules (perf-DCs). Using bone marrow transplantation to generate animals selectively lacking perf-DCs, we found that these chimeras progressively gained weight and exhibited features of metabolic syndrome. This phenotype was associated with an altered repertoire of T cells residing in adipose tissue and could be completely prevented by T cell depletion in vivo. A similar impact of perf-DCs on inflammatory T cells was also found in a well-defined model of multiple sclerosis, experimental autoimmune encephlalomyelitis (EAE). Thus, perf-DCs probably represent a regulatory cell subpopulation critical for protection from metabolic syndrome and autoimmunity.

Death ligands and granulysin: mechanisms of tumor cell death induction and therapeutic opportunities

The immune system plays a key role in cancer immune surveillance to control tumor development. The final goal is recognizing and killing transformed cells and consequently the elimination of the tumor. The main effector cell types exerting cytotoxicity against tumors are natural killer (NK) cells and cytotoxic T lymphocytes (CTLs). Although the mechanism of activation of NK cells and CTLs are quite different, both cell types share common antitumor effector mechanisms of cytotoxicity which lead to induction of cell death of tumor cells by apoptosis. Among these mechanisms are the death ligand- and granulysin-mediated cell deaths. In this review, we summarize the main concepts of these effector cytotoxic mechanisms against cancer cells, how NK cells and CTLs use them to control tumor development and the therapeutic approaches currently developed based on these molecules.

Advances in the design and development of oncolytic measles viruses

A successful oncolytic virus is one that selectively propagates and destroys cancerous tissue without causing excessive damage to the normal surrounding tissue. Oncolytic measles virus (MV) is one such virus that exhibits this characteristic and thus has rapidly emerged as a potentially useful anticancer modality. Derivatives of the Edmonston MV vaccine strain possess a remarkable safety record in humans. Promising results in preclinical animal models and evidence of biological activity in early phase trials contribute to the enthusiasm. Genetic modifications have enabled MV to evolve from a vaccine agent to a potential anticancer therapy. Specifically, alterations of the MV genome have led to improved tumor selectivity and delivery, therapeutic potency, and immune system modulation. In this article, we will review the advancements that have been made in the design and development of MV that have led to its use as a cancer therapy. In addition, we will discuss the evidence supporting its use, as well as the challenges associated with MV as a potential cancer therapeutic.