Low levels of interferon-alpha induce CD86 (B7.2) expression and accelerates dendritic cell maturation from human peripheral blood mononuclear cells

A modified HSV-1 oncolytic virus reconciles antiviral and antitumor immunity via promoting IFNβ expression and inhibiting PKR

Type I interferon (IFN-I) is a potent immune modulator intricately involved in regulating tumor immunity. Meanwhile, the integrity of the IFN-I signaling pathway is essential for radiotherapy, chemotherapy, targeted therapy, and immunotherapy. However, the clinical application of IFN-I remains challenging due to its non-specific cytotoxicity and limited half-life. To overcome these limitations, we developed a gene delivery platform, CRISPR-V, enabling the rapid creation of novel HSV-1 oncolytic viruses. Utilizing this platform, we created an oncolytic virus, OVH-IFNβ, in which the IFNβ gene was incorporated into the HSV-1 genome. However, exogenous IFNβ expression significantly inhibited OVH-IFNβ replication. Through transcriptome data analyses, we identified several ISG genes inhibiting OVH-IFNβ replication. By gene knockout and functional studies of the downstream effectors, we confirmed the prominent antiviral activities of protein kinase R (PKR). To balance the antitumor and antiviral immunity of IFNβ, we developed a novel HSV-1 oncolytic virus, OVH-IFNβ-iPKR, which can express IFNβ while inhibiting PKR, leading to a potent antitumor immunity while reducing the antiviral capacity of IFNβ. OVH-IFNβ-iPKR shows a strong ability to induce immunogenic cell death and activate tumor-specific CD8+ T cells, leading to de novo immune responses and providing a novel strategy for tumor immunotherapy.

cGAS-STING pathway mediates activation of dendritic cell sensing of immunogenic tumors

Type I interferons (IFN-I) play pivotal roles in tumor therapy for three decades, underscoring the critical importance of maintaining the integrity of the IFN-1 signaling pathway in radiotherapy, chemotherapy, targeted therapy, and immunotherapy. However, the specific mechanism by which IFN-I contributes to these therapies, particularly in terms of activating dendritic cells (DCs), remains unclear. Based on recent studies, aberrant DNA in the cytoplasm activates the cyclic GMP-AMP synthase (cGAS)- stimulator of interferon genes (STING) signaling pathway, which in turn produces IFN-I, which is essential for antiviral and anticancer immunity. Notably, STING can also enhance anticancer immunity by promoting autophagy, inflammation, and glycolysis in an IFN-I-independent manner. These research advancements contribute to our comprehension of the distinctions between IFN-I drugs and STING agonists in the context of oncology therapy and shed light on the challenges involved in developing STING agonist drugs. Thus, we aimed to summarize the novel mechanisms underlying cGAS-STING-IFN-I signal activation in DC-mediated antigen presentation and its role in the cancer immune cycle in this review.

IUPHAR ECR review: The cGAS-STING pathway: Novel functions beyond innate immune and emerging therapeutic opportunities

Stimulator of interferon genes (STING) is a crucial innate immune sensor responsible for distinguishing pathogens and cytosolic DNA, mediating innate immune signaling pathways to defend the host. Recent studies have revealed additional regulatory functions of STING beyond its innate immune-related activities, including the regulation of cellular metabolism, DNA repair, cellular senescence, autophagy and various cell deaths. These findings highlight the broader implications of STING in cellular physiology beyond its role in innate immunity. Currently, approximately 10 STING agonists have entered the clinical stage. Unlike inhibitors, which have a maximum inhibition limit, agonists have the potential for infinite amplification. STING signaling is a complex process that requires precise regulation of STING to ensure balanced immune responses and prevent detrimental autoinflammation. Recent research on the structural mechanism of STING autoinhibition and its negative regulation by adaptor protein complex 1 (AP-1) provides valuable insights into its different effects under physiological and pathological conditions, offering a new perspective for developing immune regulatory drugs. Herein, we present a comprehensive overview of the regulatory functions and molecular mechanisms of STING beyond innate immune regulation, along with updated details of its structural mechanisms. We discuss the implications of these complex regulations in various diseases, emphasizing the importance and feasibility of targeting the immunity-dependent or immunity-independent functions of STING. Moreover, we highlight the current trend in drug development and key points for clinical research, basic research, and translational research related to STING.

Conventional DNA-Damaging Cancer Therapies and Emerging cGAS-STING Activation: A Review and Perspectives Regarding Immunotherapeutic Potential

Many traditional cancer treatments such as radiation and chemotherapy are known to induce cellular DNA damage as part of their cytotoxic activity. The cGAS-STING signaling axis, a key member of the DNA damage response that acts as a sensor of foreign or aberrant cytosolic DNA, is helping to rationalize the DNA-damaging activity of these treatments and their emerging immunostimulatory capacity. Moreover, cGAS-STING, which is attracting considerable attention for its ability to promote antitumor immune responses, may fundamentally be able to address many of the barriers limiting the success of cancer immunotherapy strategies, including the immunosuppressive tumor microenvironment. Herein, we review the traditional cancer therapies that have been linked with cGAS-STING activation, highlighting their targets with respect to their role and function in the DNA damage response. As part of the review, an emerging "chemoimmunotherapy" concept whereby DNA-damaging agents are used for the indirect activation of STING is discussed as an alternative to the direct molecular agonism strategies that are in development, but have yet to achieve clinical approval. The potential of this approach to address some of the inherent and emerging limitations of cGAS-STING signaling in cancer immunotherapy is also discussed. Ultimately, it is becoming clear that in order to successfully employ the immunotherapeutic potential of the cGAS-STING axis, a balance between its contrasting antitumor and protumor/inflammatory activities will need to be achieved.

Chemical and Biomolecular Strategies for STING Pathway Activation in Cancer Immunotherapy

The stimulator of interferon genes (STING) cellular signaling pathway is a promising target for cancer immunotherapy. Activation of the intracellular STING protein triggers the production of a multifaceted array of immunostimulatory molecules, which, in the proper context, can drive dendritic cell maturation, antitumor macrophage polarization, T cell priming and activation, natural killer cell activation, vascular reprogramming, and/or cancer cell death, resulting in immune-mediated tumor elimination and generation of antitumor immune memory. Accordingly, there is a significant amount of ongoing preclinical and clinical research toward further understanding the role of the STING pathway in cancer immune surveillance as well as the development of modulators of the pathway as a strategy to stimulate antitumor immunity. Yet, the efficacy of STING pathway agonists is limited by many drug delivery and pharmacological challenges. Depending on the class of STING agonist and the desired administration route, these may include poor drug stability, immunocellular toxicity, immune-related adverse events, limited tumor or lymph node targeting and/or retention, low cellular uptake and intracellular delivery, and a complex dependence on the magnitude and kinetics of STING signaling. This review provides a concise summary of the STING pathway, highlighting recent biological developments, immunological consequences, and implications for drug delivery. This review also offers a critical analysis of an expanding arsenal of chemical strategies that are being employed to enhance the efficacy, safety, and/or clinical utility of STING pathway agonists and lastly draws attention to several opportunities for therapeutic advancements.

Double-edged effects of interferons on the regulation of cancer-immunity cycle

Interferons (IFNs) are a large family of pleiotropic cytokines that regulate both innate and adaptive immunity and show anti-cancer effects in various cancer types. Moreover, it was revealed that IFN signaling plays critical roles in the success of cancer therapy strategies, thereby enhancing their therapeutic effects. However, IFNs have minimal or even adverse effects on cancer eradication, and mediate cancer immune escape in some instances. Thus, IFNs have a double-edged effect on the cancer immune response. Recent studies suggest that IFNs regulate each step of the cancer immunity-cycle, consisting of cancer antigen release, presentation of antigens and activation of T cells, trafficking and infiltration of effector T cells into the tumor microenvironment, and recognition and killing of cancer cells, which contributes to our understanding of the mechanisms of IFNs in regulating cancer immunity. In this review, we focus on IFNs and cancer immunity and elaborate on the roles of IFNs in regulating the cancer-immunity cycle.

Interfering With Inflammation: Heterogeneous Effects of Interferons in Graft-Versus-Host Disease of the Gastrointestinal Tract and Inflammatory Bowel Disease

The intestine can be the target of several immunologically mediated diseases, including graft-versus-host disease (GVHD) and inflammatory bowel disease (IBD). GVHD is a life-threatening complication that occurs after allogeneic hematopoietic stem cell transplantation. Involvement of the gastrointestinal tract is associated with a particularly high mortality. GVHD development starts with the recognition of allo-antigens in the recipient by the donor immune system, which elicits immune-mediated damage of otherwise healthy tissues. IBD describes a group of immunologically mediated chronic inflammatory diseases of the intestine. Several aspects, including genetic predisposition and immune dysregulation, are responsible for the development of IBD, with Crohn’s disease and ulcerative colitis being the two most common variants. GVHD and IBD share multiple key features of their onset and development, including intestinal tissue damage and loss of intestinal barrier function. A further common feature in the pathophysiology of both diseases is the involvement of cytokines such as type I and II interferons (IFNs), amongst others. IFNs are a family of protein mediators produced as a part of the inflammatory response, typically to pathogens or malignant cells. Diverse, and partially paradoxical, effects have been described for IFNs in GVHD and IBD. This review summarizes current knowledge on the role of type I, II and III IFNs, including basic concepts and controversies about their functions in the context of GVHD and IBD. In addition, therapeutic options, research developments and remaining open questions are addressed.

IFNα Augments Clinical Efficacy of Regulatory T-cell Depletion with Denileukin Diftitox in Ovarian Cancer

PURPOSE

Immunotherapy treats some cancers, but not ovarian cancer. Regulatory T cells (Tregs) impede anti-ovarian cancer immunity but effective human Treg-directed treatments are lacking. We tested Treg depletion with denileukin diftitox (DD) ± IFNα as ovarian cancer immunotherapy.

PATIENTS AND METHODS

Mice with syngeneic ID8 ovarian cancer challenge were treated with DD, IFNα, or both. The phase 0/I trial tested one dose-escalated DD infusion for functional Treg reduction, safety, and tolerability. The phase II trial added IFNα2a to DD if DD alone failed clinically.

RESULTS

DD depleted Tregs, and improved antitumor immunity and survival in mice. IFNα significantly improved antitumor immunity and survival with DD. IFNα did not alter Treg numbers or function but boosted tumor-specific immunity and reduced tumor Treg function with DD by inducing dendritic cell IL6. DD alone was well tolerated, depleted functional blood Tregs and improved immunity in patients with various malignancies in phase 0/I. A patient with ovarian cancer in phase 0/I experienced partial clinical response prompting a phase II ovarian cancer trial, but DD alone failed phase II. Another phase II trial added pegylated IFNα2a to failed DD, producing immunologic and clinical benefit in two of two patients before a DD shortage halt. DD alone was well tolerated. Adding IFNα increased toxicities but was tolerable, and reduced human Treg numbers in blood, and function through dendritic cell-induced IL6 in vitro.

CONCLUSIONS

Treg depletion is clinically useful but unlikely alone to cure ovarian cancer. Rational treatment agent combinations can salvage clinical failure of Treg depletion alone, even when neither single agent provides meaningful clinical benefit.

Glycan-Modified Virus-like Particles Evoke T Helper Type 1-like Immune Responses

Dendritic cells (DCs) are highly effective antigen-presenting cells that shape immune responses. Vaccines that deliver antigen to the DCs can harness their power. DC surface lectins recognize glycans not typically present on host tissue to facilitate antigen uptake and presentation. Vaccines that target these surface lectins should offer improved antigen delivery, but their efficacy will depend on how lectin targeting influences the T cell subtypes that result. We examined how antigen structure influences uptake and signaling from the C-type lectin DC-SIGN (dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin or CD209). Virus-like particles (VLPs) were engineered from bacteriophage Qβ to present an array of mannoside ligands. The VLPs were taken up by DCs and efficiently trafficked to endosomes. The signaling that ensued depended on the ligand displayed on the VLP: only those particles densely functionalized with an aryl mannoside, Qβ-Man₅₄₀, elicited DC maturation and induced the expression of the proinflammatory cytokines characteristic of a T helper type 1 (T_H1)-like immune response. This effect was traced to differential binding to DC-SIGN at the acidic pH of the endosome. Mice immunized with a VLP bearing the aryl mannoside, and a peptide antigen (Qβ-Ova-Man₅₄₀) had antigen-specific responses, including the production of CD4⁺ T cells producing the activating cytokines interferon-γ and tumor necrosis factor-α. A T_H1 response is critical for intracellular pathogens (e.g., viruses) and cancer; thus, our data highlight the value of targeting DC lectins for antigen delivery and validate the utility of DC-targeted VLPs as vaccine vehicles that induce cellular immunity.

Type I interferons in pancreatic cancer and development of new therapeutic approaches

Immunotherapy has emerged as a new treatment strategy for cancer. However, its promise in pancreatic cancer has not yet been realized. Understanding the immunosuppressive tumor microenvironment of pancreatic cancer, and identifying new therapeutic targets to increase tumor-specific immune responses, is necessary in order to improve clinical outcomes. Type I interferons, e.g. IFN-α and -β, are considered as an important bridge between the innate and adaptive immune system. Thereby, type I IFNs induce a broad spectrum of anti-tumor effects, including immunologic, vascular, as well as direct anti-tumor effects. While IFN therapies have been around for a while, new insights into exogenous and endogenous activation of the IFN pathway have resulted in new IFN-related cancer treatment strategies. Here, we focus on the pre-clinical and clinical evidence of novel ways to take advantage of the type I IFN pathway, such as IFN based conjugates and activation of the STING and RIG-I pathways.

Use of human peripheral blood mononuclear cells to define immunological properties of nucleic acid nanoparticles

This protocol assesses proinflammatory properties of nucleic acid nanoparticles (NANPs) using a validated preclinical model, peripheral blood mononuclear cells (PBMCs), that is highly predictive of cytokine responses. The experimental procedure details the preparation of pyrogen-free NANPs, isolation of PBMCs from freshly collected human blood, and analysis of characteristic biomarkers (type I and III interferons) produced by PBMCs transfected with NANPs. Although representative NANPs with high and low immunostimulatory potential are used as standards throughout the procedure, this protocol can be adapted to any NANPs or therapeutic nucleic acids, irrespective of whether they are carrier based or carrier free; additional cytokine biomarkers can also be included. We test several commercial platforms and controls broadly accessible to the research community to quantify all biomarkers in either single- or multiplex format. The continuous execution of this protocol takes <48 h; when immediate analysis is not feasible, single-use aliquots of the supernatants can be frozen and stored (-20 °C; 12 months).

Opportunities, Barriers, and a Strategy for Overcoming Translational Challenges to Therapeutic Nucleic Acid Nanotechnology

Recent clinical successes using therapeutic nucleic acids (TNAs) have accelerated the transition of nucleic acid nanotechnology toward therapeutic applications. Significant progress in the development, production, and characterization of nucleic acid nanomaterials and nucleic acid nanoparticles (NANPs), as well as abundant proof-of-concept data, are paving the way toward biomedical applications of these materials. This recent progress has catalyzed the development of new strategies for biosensing, imaging, drug delivery, and immunotherapies with previously unrecognized opportunities and identified some barriers that may impede the broader clinical translation of NANP technologies. A recent workshop sponsored by the Kavli Foundation and the Materials Research Society discussed the future directions and current challenges for the development of therapeutic nucleic acid nanotechnology. Herein, we communicate discussions on the opportunities, barriers, and strategies for realizing the clinical grand challenge of TNA nanotechnology, with a focus on ways to overcome barriers to advance NANPs to the clinic.

CCR7, CD80/86 and CD83 in yellow catfish (Pelteobagrus fulvidraco): Molecular characteristics and expression patterns with bacterial infection

Dendritic cells (DCs) have a strong ability to stimulate naive T lymphocyte proliferation, so DCs play an important regulatory role in the initiation of the specific immune response. DCs cannot play the role of antigen presentation without the expression of surface molecules. The chemokine receptor CCR7 and the costimulatory molecules CD80/86 and CD83 are not only markers of DC maturation but also important functional molecules in the immune response of DC-T cells. In this study, partial cDNA sequences of CCR7, CD80/86 and CD83 were obtained by rapid amplification of cDNA ends (RACE) technology from yellow catfish. Bioinformatics analysis of deduced amino acid sequences of these three genes showed that CCR7, CD80/86 and CD83 genes in yellow catfish have similar functional domains to the homologs in other vertebrates, which indicated that the functions of these genes may be somewhat conserved during the evolution process. Afterward, the expression characteristics of these three genes in different tissues were detected by q-PCR. This result indicated that CCR7, CD80/86 and CD83 were expressed in all examined tissues, and the highest expression levels of CCR7 and CD80/86 and CD83 were detected in the trunk kidney, muscle and midgut, respectively. Meanwhile, the expression levels of CCR7 and CD80/86 were lowest in the gill, and the expression of CD83 was lowest in the stomach. Finally, healthy yellow catfish were infected with A.hydrophila (1.0 × 10⁷ CFU/mL) or E.ictaluri (1.0 × 10⁶ CFU/mL), q-PCR results indicated that both pathogenic bacteria can induce significant upregulation of CCR7, CD80/86 and CD83 in immune organs, and the expression levels of these genes in the intestine were higher than those in the skin and gill. Our results in this study provide a molecular basis for exploring the role of CCR7, CD80/86 and CD83 in the immune responses induced by bacteria, and can help us to understand the difference of immune responses induced by extracellular and intracellular bacteria.

Nucleic Acid Nanoparticles at a Crossroads of Vaccines and Immunotherapies

Vaccines and immunotherapies involve a variety of technologies and act through different mechanisms to achieve a common goal, which is to optimize the immune response against an antigen. The antigen could be a molecule expressed on a pathogen (e.g., a disease-causing bacterium, a virus or another microorganism), abnormal or damaged host cells (e.g., cancer cells), environmental agent (e.g., nicotine from a tobacco smoke), or an allergen (e.g., pollen or food protein). Immunogenic vaccines and therapies optimize the immune response to improve the eradication of the pathogen or damaged cells. In contrast, tolerogenic vaccines and therapies retrain or blunt the immune response to antigens, which are recognized by the immune system as harmful to the host. To optimize the immune response to either improve the immunogenicity or induce tolerance, researchers employ different routes of administration, antigen-delivery systems, and adjuvants. Nanocarriers and adjuvants are of particular interest to the fields of vaccines and immunotherapy as they allow for targeted delivery of the antigens and direct the immune response against these antigens in desirable direction (i.e., to either enhance immunogenicity or induce tolerance). Recently, nanoparticles gained particular attention as antigen carriers and adjuvants. This review focuses on a particular subclass of nanoparticles, which are made of nucleic acids, so-called nucleic acid nanoparticles or NANPs. Immunological properties of these novel materials and considerations for their clinical translation are discussed.

STING: a master regulator in the cancer-immunity cycle

The aberrant appearance of DNA in the cytoplasm triggers the activation of cGAS-cGAMP-STING signaling and induces the production of type I interferons, which play critical roles in activating both innate and adaptive immune responses. Recently, numerous studies have shown that the activation of STING and the stimulation of type I IFN production are critical for the anticancer immune response. However, emerging evidence suggests that STING also regulates anticancer immunity in a type I IFN-independent manner. For instance, STING has been shown to induce cell death and facilitate the release of cancer cell antigens. Moreover, STING activation has been demonstrated to enhance cancer antigen presentation, contribute to the priming and activation of T cells, facilitate the trafficking and infiltration of T cells into tumors and promote the recognition and killing of cancer cells by T cells. In this review, we focus on STING and the cancer immune response, with particular attention to the roles of STING activation in the cancer-immunity cycle. Additionally, the negative effects of STING activation on the cancer immune response and non-immune roles of STING in cancer have also been discussed.

Transcriptome Analysis Shows That IFN-I Treatment and Concurrent SAV3 Infection Enriches MHC-I Antigen Processing and Presentation Pathways in Atlantic Salmon-Derived Macrophage/Dendritic Cells

Type I interferons (IFNs) have been shown to play an important role in shaping adaptive immune responses in addition to their antiviral properties in immune cells. To gain insight into the impact of IFN-I-induced pathways involved in early adaptive immune responses, i.e., antigen-presenting pathways, in an Atlantic salmon-derived (Salmo salar L.) macrophage cell line (TO-cells), we used a comparative de novo transcriptome analysis where cells were treated with IFN-I or kept untreated and concurrently infected with salmonid alphavirus subtype 3 (SAV3). We found that concurrent treatment of TO-cells with IFN-I and SAV3 infection (SAV3/IFN⁺) significantly enriched the major histocompatibility complex class I (MHC-I) pathway unlike the non-IFN-I treated TO-cells (SAV3/IFN⁻) that had lower expression levels of MHC-I pathway-related genes. Genes such as the proteasomal activator (PA28) and β-2 microglobulin (β2M) were only differentially expressed in the SAV3/IFN⁺ cells and not in the SAV3/IFN⁻ cells. MHC-I pathway genes like heat shock protein 90 (Hsp90), transporter of antigen associated proteins (TAPs) and tapasin had higher expression levels in the SAV3/IFN⁺ cells than in the SAV3/IFN⁻ cells. There were no MHC-II pathway-related genes upregulated in SAV3/IFN⁺-treated cells, and cathepsin S linked to the degradation of endosomal antigens in the MHC-II pathway was downregulated in the SAV3/IFN⁻ cells. Overall, our findings show that concurrent IFN-I treatment of TO-cells and SAV3 infection enriched gene expression linked to the MHC-I antigen presentation pathway. Data presented indicate a role of type I IFNs in strengthening antigen processing and presentation that may facilitate activation particularly of CD8+ T-cell responses following SAV3 infection, while SAV3 infection alone downplayed MHC-II pathways.

Interferon as a Mucosal Adjuvant for an Influenza Vaccine in Pigs

Interferon, a natural protein that is produced by a variety of cells during viral infection, activates the transcription of multiple functional genes in cells, regulates synergy among various signaling pathways, and mediates many biological functions such as antiviral activity, immune regulation, and cell growth. However, clinical research on interferon in livestock is lacking. In this study, recombinant porcine interferon (PoIFNα) was used as an adjuvant, in combination with inactivated influenza virus, to vaccinate 6-week-old pigs via nasal infusion. The transcription of target genes was then monitored and the functions of PoIFNα were determined with respect to the activation of mucosal immunity. We found that a combination of low-dose PoIFNα and inactivated influenza virus could significantly up-regulate the expression of immunoregulatory cytokines such as IL-2, IL-18, IFN-γ, IL-6, and IL-10 by real-time PCR, suggesting the induction of a strong mucosal innate immune response after administration. In addition, low-dose PoIFNα can significant enhancing the transcription of genes encoding homing factors including CCR9 and CCR10 (P < 0.001), thereby resulting in the induction of higher levels of HA-specific antibodies (P < 0.05), which can be determined by ELISA and IFA. Post-immunization challenges with H1N1 virus demonstrated that PoIFNα, combined with inactivated influenza virus, could alleviate clinical signs in pigs during the early stages of viral infection. These studies reveal low-dose PoIFNα as a potential mucosal adjuvant for influenza virus in pigs.

Clearance of HBeAg and HBsAg of HBV in mice model by a recombinant HBV vaccine combined with GM-CSF and IFN-α as an effective therapeutic vaccine adjuvant

Chronic hepatitis B virus (CHB) infection is a significant public threat. Current interferon-α (IFN-α) based therapies and anti-viral drugs have failed to clear the infection in the majority of CHB patients and animal models. In our previous study, we established a combined protocol that employed a 3-day pretreatment with granulocyte-macrophage colony stimulating factor (GM-CSF) prior to a standard HBV vaccine. It achieved a 90% reduction of HBsAg level in the HBsAg transgenic mouse model. This protocol, while effective, remains too complex for clinical use. In this study, we formulated a new regimen by combining GM-CSF, IFN-α and a recombinant HBV vaccine (GM-CSF/IFN-α/VACCINE) into a single preparation and tested its efficacy in a HBV infection model. After four vaccinations, both serum HBeAg and HBsAg were cleared, accompanied by a 95% reduction of HBV⁺ hepatocytes and the presence of a large number of infiltrating CD8⁺ T cells in the liver. Mechanistically these robust responses were initiated by a vaccine-induced conversion of CCR2-dependent CD11b⁺Ly6C^hi monocytes into CD11b⁺CD11c⁺ DCs. This finding sheds light on the potential mechanism of action of the GM-CSF-based vaccine adjuvant and provides definable markers for clinical assessment during future testing of such highly potent vaccine protocols in HBV patients.

Type I IFN Signaling Is Dispensable during Secondary Viral Infection

Innate immune responses in general, and type I interferons (T1IFNs) in particular, play an important and often essential role during primary viral infections, by directly combatting the virus and by maximizing the primary adaptive immune response. Several studies have suggested that T1IFNs also contribute very substantially to the secondary (recall) response; they are thought (i) to be required to drive the early attrition of memory T cells, (ii) to support the subsequent expansion of surviving virus-specific memory cells, and (iii) to assist in the suppression and clearance of the infectious agent. However, many of these observations were predicated upon models in which T1IFN signaling was interrupted prior to a primary immune response, raising the possibility that the resulting memory cells might be intrinsically abnormal. We have directly addressed this by using an inducible-Cre model system in which the host remains genetically-intact during the primary response to infection, and in which T1IFN signaling can be effectively ablated prior to secondary viral challenge. We report that, in stark contrast to primary infection, T1IFN signaling is not required during the recall response. IFNαβR-deficient memory CD8+ and CD4+ memory T cells undergo attrition and expansion with kinetics that are indistinguishable from those of receptor-sufficient cells. Moreover, even in the absence of functional T1IFN signaling, the host's immune capacity to rapidly suppress, and then to eradicate, a secondary infection remains intact. Thus, this study shows that T1IFN signaling is dispensable during the recall response to a virus infection. Moreover, two broader implications may be drawn. First, a T cell's requirement for a cytokine is highly dependent on the cell's maturation / differentiation status. Consequently, second, these data underscore the importance of evaluating a gene's impact by modulating its expression or function in a temporally-controllable manner.

Type I and III IFNs Produced by Plasmacytoid Dendritic Cells in Response to a Member of the Flaviviridae Suppress Cellular Immune Responses

The pestivirus noncytopathic bovine viral diarrhea virus (BVDV) can suppress IFN production in the majority of cell types in vitro. However, IFN is detectable in serum during acute infection in vivo for ∼5-7 d, which correlates with a period of leucopoenia and immunosuppression. In this study, we demonstrate that a highly enriched population of bovine plasmacytoid dendritic cells (DCs) produced IFN in response to BVDV in vitro. We further show that the majority of the IFN produced in response to infection both in vitro and in vivo is type III IFN and acid labile. Further, we show IL-28B (IFN-λ3) mRNA is induced in this cell population in vitro. Supernatant from plasmacytoid DCs harvested postinfection with BVDV or recombinant bovine IFN-α or human IL-28B significantly reduced CD4(+) T cell proliferation induced by tubercle bacillus Ag 85-stimulated monocyte-derived DCs. Furthermore, these IFNs induced IFN-stimulated gene expression predominantly in monocyte-derived DCs. IFN-treated immature DCs derived from murine bone marrow also had a reduced capacity to stimulate T cell proliferative responses to tubercle bacillus Ag 85. Immature DCs derived from either source had a reduced capacity for Ag uptake following IFN treatment that is dose dependent. Immunosuppression is a feature of a number of pestivirus infections; our studies suggest type III IFN production plays a key role in the pathogenesis of this family of viruses. Overall, in a natural host, we have demonstrated a link between the induction of type I and III IFN after acute viral infection and transient immunosuppression.

Type I interferons as regulators of human antigen presenting cell functions

Type I interferons (IFNs) are pleiotropic cytokines, initially described for their antiviral activity. These cytokines exhibit a long record of clinical use in patients with some types of cancer, viral infections and chronic inflammatory diseases. It is now well established that IFN action mostly relies on their ability to modulate host innate and adaptive immune responses. Work in recent years has begun to elucidate the mechanisms by which type I IFNs modify the immune response, and this is now recognized to be due to effects on multiple cell types, including monocytes, dendritic cells (DCs), NK cells, T and B lymphocytes. An ensemble of results from both animal models and in vitro studies emphasized the key role of type I IFNs in the development and function of DCs, suggesting the existence of a natural alliance between these cytokines and DCs in linking innate to adaptive immunity. The identification of IFN signatures in DCs and their dysregulation under pathological conditions will therefore be pivotal to decipher the complexity of this DC-IFN interaction and to better exploit the therapeutic potential of these cells.

Interferons and their stimulated genes in the tumor microenvironment

Constitutive expression of interferons (IFNs) and activation of their signaling pathways have pivotal roles in host responses to malignant cells in the tumor microenvironment. IFNs are induced by the innate immune system and in tumors through stimulation of Toll-like receptors (TLRs) and through other signaling pathways in response to specific cytokines. Although in the oncologic context IFNs have been thought of more as exogenous pharmaceuticals, the autocrine and paracrine actions of endogenous IFNs probably have even more critical effects on neoplastic disease outcomes. Through high-affinity cell surface receptors, IFNs modulate transcriptional signaling, leading to regulation of more than 2,000 genes with varying patterns of temporal expression. Induction of the gene products by both unphosphorylated and phosphorylated STAT1 after ligand binding results in alterations in tumor cell survival, inhibition of angiogenesis, and augmentation of actions of T, natural killer (NK), and dendritic cells. The interferon-stimulated gene (ISG) signature can be a favorable biomarker of immune response but, in a seemingly paradoxical finding, a specific subset of the full ISG signature indicates an unfavorable response to DNA-damaging interventions such as radiation. IFNs in the tumor microenvironment thus can alter the emergence, progression, and regression of malignancies.

Oral delivery of oligomeric procyanidins in Apple Poly® enhances type I IFN responses in vivo

Type I IFN signaling is a central pathway that provides critical innate protection from viral and bacterial infection and can have regulatory outcomes in inflammatory settings. We determined previously that OPCs contained in the dietary supplement APP enhanced responses to type I IFN in vitro. Here, we confirm that OPCs from two different sources significantly increased pSTAT1, whereas a monomeric form of procyanidin did not. We hypothesized that similar responses could be induced in vivo following ingestion of APP. Ingestion of APP before injection of polyI:C enhanced in vivo responses to type I IFNs in mice. When human subjects ingested APP, enhanced responses to type I IFN and enhanced pSTAT1 ex vivo were detected, whereas ingestion of RES, a monomeric polyphenol, induced minimal such changes. Polyphenols are best known for induction of anti-inflammatory and antioxidant responses; however, our findings suggest a unique, nonantioxidant aspect of OPCs that is broadly applicable to many disease settings. The capacity of oral OPCs to enhance type I IFN signaling in vivo can augment innate protection and may, in part, contribute to the noted anti-inflammatory outcome of ingestion of OPCs from many sources.

Type I IFN drives a distinctive dendritic cell maturation phenotype that allows continued class II MHC synthesis and antigen processing

Microbial molecules or cytokines can stimulate dendritic cell (DC) maturation, which involves DC migration to lymph nodes and enhanced presentation of Ag to launch T cell responses. Microbial TLR agonists are the most studied inducers of DC maturation, but type I IFN (IFN-I) also promotes DC maturation. In response to TLR stimulation, DC maturation involves a burst of Ag processing with enhanced expression of peptide-class II MHC complexes and costimulator molecules. Subsequently, class II MHC (MHC-II) synthesis and expression in intracellular vacuolar compartments is inhibited, decreasing Ag processing function. This limits presentation to a cohort of Ags kinetically associated with the maturation stimulus and excludes presentation of Ags subsequently experienced by the DC. In contrast, our studies show that IFN-I enhances DC expression of MHC-II and costimulatory molecules without a concomitant inhibition of subsequent MHC-II synthesis and Ag processing. Expression of mRNA for MHC-II and the transcription factor CIITA is inhibited in DCs treated with TLR agonists but maintained in cells treated with IFN-I. After stimulation with IFN-I, MHC-II expression is increased on the plasma membrane but is also maintained in intracellular vacuolar compartments, consistent with sustained Ag processing function. These findings suggest that IFN-I drives a distinctive DC maturation program that enhances Ag presentation to T cells without a shutdown of Ag processing, allowing continued sampling of Ags for presentation.

Defective dendritic cell generation from monocytes is a potential reason for poor therapeutic efficacy of interferon α2b (IFNα2b) in cervical cancer

Despite being a pleiotropic cytokine, the therapeutic potential of interferon α2b (IFNα2b) is debatable. Thus, the need for identifying predictive marker(s) for patients who are most likely to benefit from the treatment is pivotal for avoiding the exposure of nonresponsive patients to the toxicity of the treatment. To account for the attenuated efficacy of the drug, we have verified its dendritic cell (DC) maturating ability from monocytes of cervical cancer stage IIIB (CaCx-IIIB) patients. First, we evaluated the status of monocytes from CaCx-IIIB and healthy women by conducting flow cytometric studies of various activation markers and a cytokine analysis by enzyme-linked immunosorbent assay (ELISA) and flow cytometry. Immature DCs were then generated from these monocytes and matured with low-dose IFNα2b (1500 units/mL). A functional and phenotypic comparative analysis of these matured DCs was performed by flow cytometric, proliferative, cytotoxic, and enzyme-linked immunosorbent assays. Our study shows that monocytes isolated from CaCx-IIIB are impaired, and in vitro maturation with IFNα2b did not significantly improve the functional repertoire of DCs generated from these monocytes in comparison with healthy controls. This impairment of monocytes might be a plausible reason for the attenuated efficacy of this drug alone in treating CaCx-IIIB patients, and this imbalance of immune parameters associated with the stage of malignancy might be considered an effective marker to design a proper therapeutic regimen.

Interferon-α in the generation of monocyte-derived dendritic cells: recent advances and implications for dermatology

Dendritic cells (DCs) have a critical role in antiviral responses, in autoimmune disease pathogenesis and in initiating and maintaining inflammatory skin disorders, and are candidates for cell-based immunotherapeutic approaches for tumours. Recent studies have shown the important role of type I interferons (IFNs) in DC differentiation and activation. In the presence of IFN-α and granulocyte/macrophage colony-stimulating factor monocytes differentiate into DCs referred to as IFN-DCs. In vitro generated IFN-DCs show a partially mature phenotype, are effective in taking up antigens, share features of myeloid DCs, plasmacytoid DCs and natural killer cells, exhibit an enhanced chemotactic response and are capable of migrating to the lymph nodes. IFN-DCs produce several chemokines and cytokines, including T-helper 1 (Th1) mediators belonging to the interleukin-12 family. IFN-DCs stimulate T- and B-cell responses and the production of IFN-γ in mixed lymphocyte reactions and have a capacity to produce IFN-γ themselves. IFN-DCs express several toll-like receptor (TLR) subtypes and TLR ligand stimulation improves their costimulatory molecule expression, increases their Th1 cytokine production and enhances their capacity to stimulate naive T-cell proliferation. Here we review the interaction of IFN-α and monocytes and the role of IFN-DCs in infections, in autoimmunity, in inflammation and in cancer immunotherapy focusing on dermatological conditions.

Exogenous control of the expression of Group I CD1 molecules competent for presentation of microbial nonpeptide antigens to human T lymphocytes

Group I CD1 (CD1a, CD1b, and CD1c) glycoproteins expressed on immature and mature dendritic cells present nonpeptide antigens (i.e., lipid or glycolipid molecules mainly of microbial origin) to T cells. Cytotoxic CD1-restricted T lymphocytes recognizing mycobacterial lipid antigens were found in tuberculosis patients. However, thanks to a complex interplay between mycobacteria and CD1 system, M. tuberculosis possesses a successful tactic based, at least in part, on CD1 downregulation to evade CD1-dependent immunity. On the ground of these findings, it is reasonable to hypothesize that modulation of CD1 protein expression by chemical, biological, or infectious agents could influence host's immune reactivity against M. tuberculosis-associated lipids, possibly affecting antitubercular resistance. This scenario prompted us to perform a detailed analysis of the literature concerning the effect of external agents on Group I CD1 expression in order to obtain valuable information on the possible strategies to be adopted for driving properly CD1-dependent immune functions in human pathology and in particular, in human tuberculosis.

Impaired interferon signaling in dendritic cells from older donors infected in vitro with West Nile virus

West Nile virus (WNV), a mosquito-borne, single-stranded RNA flavivirus, causes significant human morbidity and mortality in the older population; thus, we investigated the effects of aging on infection with WNV in dendritic cells (DCs). We infected DCs with WNV in vitro and quantified cytokines and chemokines (type I IFN and CXCL10), pathogen recognition receptors RIG-I, and Toll-like receptors 3 and 7. The production of type I IFN was significantly lower in DCs from older donors, compared with younger donors. Although we observed no significant age-related difference in expression or nuclear translocation of signaling molecules in initial antiviral responses, DCs from older donors have diminished induction of late-phase responses (eg, STAT1, IRF7, and IRF1), suggesting defective regulation of type I IFN. Our results identify deficits in critical regulatory pathways in the antiviral response that may contribute to the enhanced susceptibility to viral infections observed in aging.

Simian immunodeficiency virus infection in the brain and lung leads to differential type I IFN signaling during acute infection

Using an accelerated and consistent SIV pigtailed macaque model of HIV-associated neurologic disorders, we have demonstrated that virus enters the brain during acute infection. However, neurologic symptoms do not manifest until late stages of infection, suggesting that immunological mechanisms exist within the CNS that control viral replication and associated inflammation. We have shown that IFN-β, a type I IFN central to viral innate immunity, is a major cytokine present in the brain during acute infection and is responsible for limiting virus infection and inflammatory cytokine expression. However, the induction and role of IFN-α in the CNS during acute SIV infection has never been examined in this model. In the classical model of IFN signaling, IFN-β signals through the IFN-α/β receptor, leading to expression of IFN-α. Surprisingly, although IFN-β is upregulated during acute SIV infection, we found that IFN-α is downregulated. We demonstrate that this downregulation is coupled with a suppression of signaling molecules downstream of the IFN receptor, namely tyrosine kinase 2, STAT1, and IFN regulatory factor 7, as indicated by either lack of protein phosphorylation, lack of nuclear accumulation, or transcriptional and/or translational repression. In contrast to brain, IFN-α is upregulated in lung and accompanied by activation of tyrosine kinase 2 and STAT1. These data provide a novel observation that during acute SIV infection in the brain, there is differential signaling through the IFN-α/β receptor that fails to activate expression of IFN-α in the brain.

Altered decamer and nonamer from an HLA-A0201-restricted epitope of Survivin differentially stimulate T-cell responses in different individuals

Survivin is a universal tumor antigen that is being currently targeted in vaccine approaches against cancer. Our study here examined the immunogenicity of a novel variant of an HLA-A0201-binding decamer peptide from region 95 to 104 of Survivin (ELMLGEFLKL) with a T→M modification at position 3 in the peptide. We found that this new modified 10-mer peptide had enhanced HLA-A0201 binding and induced a stronger T-cell response over its wild type counterpart peptide (ELTLGEFLKL) in select HLA-A0201(+) normal donors. In addition, when compared to the previously characterized altered 96-104 peptide (LMLGEFLKL) from the same region of Survivin currently used in vaccine trials, we found that both peptides had similar immunogenicity, but donor T cells preferentially reacted strongly to either one or the other, but not strongly to both. These results suggest that these two closely related Survivin peptides yield distinct T-cell responses and that most individuals dominantly respond to one or the other altered peptide. We also found a novel association between positive reactivity to the new altered decamer Survivin peptide in some individuals and their expression of the HLA-C0701 allele along with HLA-A0201. Thus, vaccinating with both the 10-mer and 9-mer peptides would be required to immunize a maximum number of individuals in the HLA-A0201(+) population and could lead to more consistent T-cell responses against this region of Survivin.

Innate immune stimuli modulate bone marrow-derived dendritic cell production in vitro by toll-like receptor-dependent and -independent mechanisms

Haematopoiesis is crucial for immunity because it results in the production of leucocytes. Bacterial and viral infections alter leucocyte production by promoting granulopoiesis or lymphopoiesis. Recent studies suggest that changes in leucocyte production may be caused by the effects of inflammatory responses on the differentiation of haematopoietic progenitors in the bone marrow. We investigated the mechanisms through which infection regulates the formation of bone marrow-derived dendritic cells (BMDCs) in vitro. We mimicked infection by stimulating developing cells with molecules associated with bacteria and viruses and with inactivated influenza viruses. We showed that toll-like receptor (TLR) ligands act as modulators of haematopoiesis, and that signalling through different TLRs results in differing effects on the production of BMDCs. We demonstrated that ligands for TLR3 and influenza viruses reduce the production of BMDCs, resulting in increased neutrophil numbers, and that ligands for TLR4 and TLR9 drive the production of plasmacytoid dendritic cells. Furthermore, there are distinct signalling mechanisms involved in these effects. Signalling pathways triggered by TLR4 and TLR9 involve MyD88 and are partially mediated by the cytokine tumour necrosis factor-α (TNF-α). Mechanisms activated by TLR3 were Tir-domain-containing adaptor-inducing interferon dependent. Haematopoietic modulation induced by inactivated influenza viruses was associated with the activation of an antiviral pathway mediated by type-1 interferons.

Interferon-alpha differentially affects homeostasis of human plasmacytoid and myeloid dendritic cells

Interferon-alpha (IFN-alpha) is widely used for the treatment of malignant and viral diseases. Conflicting results of IFN-alpha-mediated effects on dendritic cell (DC) homeostasis have been reported and its impact on human blood DC is largely unknown. We investigated the phenotypic, migratory, and allostimulatory activities of plasmacytoid DCs (PDCs) and myeloid DCs (MDCs) upon in vitro exposure to IFN-alpha without the addition of exogenous DC growth factors. IFN-alpha-exposed PDCs exhibited an increase in viability but showed an immature phenotype and a diminished allostimulatory potential. Furthermore, IFN-alpha-treated PDCs displayed a dramatically augmented expression of CD54 and CD62L as well as an increased migratory response to CC chemokine ligand (CCL)19, CXC chemokine ligand (CXCL)11, and CXCL12, suggesting an enhanced ability to migrate into peripheral lymph nodes through high endothelial venules. Myeloid DCs exposed to IFN-alpha exhibited a matured phenotype with an increased propensity to migrate toward lymph node chemokines, yet without gaining an enhanced allostimulatory capacity. Our results provide new insights into the differential immunomodulatory action of IFN-alpha on distinct human blood DC subsets and thus, may present translational significance.

Recent advances on the immunomodulatory effects of IFN-alpha: implications for cancer immunotherapy and autoimmunity

Interferons alpha (IFNs-alpha) are pleiotropic cytokines belonging to the type I IFN family, originally described for their antiviral activity. These cytokines exhibit a long record of clinical use in patients with some types of cancer and viral diseases. Notably, certain autoimmune disorders have been postulated to be mediated by endogenous IFN-alpha and are often observed in some IFN-treated patients. IFN-alpha can induce multiple biological effects, including induction/promotion of apoptosis and inhibition of cell growth. In addition, these cytokines promote the differentiation and activity of host immune cells. Early studies in mouse tumor models showed the importance of host immune mechanisms in the generation of a long-lasting antitumor response after injection of the animals with either IFN or tumor cells genetically modified for IFN-alpha production. Several studies have shown that IFN-alpha can induce the rapid differentiation of monocytes into highly activated dendritic cells (DCs). Of note, these DCs (IFN-DCs) are particularly effective in taking up complex antigens and inducing T- and B-cell immunity. The ensemble of these results suggests that IFN-DCs can play a role in the generation of antitumor T-cell immunity, pointing out that these cells could be successfully used in strategies of cancer immunotherapy. Likewise, IFN-alpha-DC interactions could also play a role in the pathogenesis of some autoimmune disorders, often associated with IFN-alpha treatment. All this reveals the complexity of the IFN-alpha-DC interactions under normal and pathological conditions and stimulates further studies for identifying optimal modalities in either using these cytokines or controlling their production/action in patients.

A type I interferon signature in monocytes is associated with poor response to interferon-beta in multiple sclerosis

The effect of interferon-beta in multiple sclerosis is modest and many patients do not respond to treatment. To date, no single biomarker reliably correlates with responsiveness to interferon-beta in multiple sclerosis. In the present study, genome-wide expression profiling was performed in peripheral blood mononuclear cells from 47 multiple sclerosis patients treated with interferon-beta for a minimum of 2 years and classified as responders and non-responders based on clinical criteria. A validation cohort of 30 multiple sclerosis patients was included in the study to replicate gene-expression findings. Before treatment, interferon-beta responders and non-responders were characterized by differential expression of type I interferon-induced genes with overexpression of the type interferon-induced genes in non-responders. Upon treatment the expression of these genes remained unaltered in non-responders, but was strongly upregulated in responders. Functional experiments showed a selective increase in phosphorylated STAT1 levels and interferon receptor 1 expression in monocytes of non-responders at baseline. When dissecting this type I interferon signature further, interferon-beta non-responders were characterized by increased monocyte type I interferon secretion upon innate immune stimuli via toll-like receptor 4, by increased endogenous production of type I interferon, and by an elevated activation status of myeloid dendritic cells. These findings indicate that perturbations of the type I interferon signalling pathway in monocytes are related to lack of response to interferon-beta, and type I interferon-regulated genes may be used as response markers in interferon-beta treatment.

Clinical and immunologic effects of intranodal autologous tumor lysate-dendritic cell vaccine with Aldesleukin (Interleukin 2) and IFN-{alpha}2a therapy in metastatic renal cell carcinoma patients

PURPOSE

To evaluate the clinical and immunologic outcomes of DC (dendritic cell) vaccine with interleukin (IL)-2 and IFN-alpha 2a in metastatic renal cell carcinoma patients.

EXPERIMENTAL DESIGN

Eighteen consented and eligible patients were treated. Peripheral blood monocytes were cultured ex vivo into mature DCs and loaded with autologous tumor lysate. Treatment consisted of five cycles of intranodal vaccination of DCs (1 x 10(7) cells/1 mL Lactated Ringer's solution), 5-day continuous i.v. infusion of IL-2 (18MiU/m2), and three s.c. injections of IFN-alpha 2a (6MiU) every other day. Response Evaluation Criteria in Solid Tumors criteria were used for disease assessment. Correlative immunologic end points included peripheral blood lymphocyte cell phenotype and function as well as peripheral blood anti-renal cell carcinoma antibody and cytokine levels.

RESULTS

All patients received between two and five treatment cycles. Toxicities consisted of known and expected cytokine side effects. Overall objective clinical response rate was 50% with three complete responses. Median time to progression for all patients was 8 months, and median survival has not been reached (median follow up of 37+ months). Treatment-related changes in correlative immunologic end points were noted and the level of circulating CD4(+) T regulatory cells had a strong association with outcome. Pre-IP-10 serum levels approached significance for predicting outcome.

CONCLUSIONS

The clinical and immunologic responses observed in this trial suggest an interaction between DC vaccination and cytokine therapy. Our data support the hypothesis that modulation of inflammatory, regulatory, and angiogenic pathways are necessary to optimize therapeutic benefit in renal cell carcinoma patients. Further exploration of this approach is warranted.

Generation in vivo of peptide-specific cytotoxic T cells and presence of regulatory T cells during vaccination with hTERT (class I and II) peptide-pulsed DCs

Background

Optimal techniques for DC generation for immunotherapy in cancer are yet to be established. Study aims were to evaluate: (i) DC activation/maturation milieu (TNF-α +/- IFN-α) and its effects on CD8+ hTERT-specific T cell responses to class I epitopes (p540 or p865), (ii) CD8+ hTERT-specific T cell responses elicited by vaccination with class I alone or both class I and II epitope (p766 and p672)-pulsed DCs, prepared without IFN-α, (iii) association between circulating T regulatory cells (Tregs) and clinical responses.

Methods

Autologous DCs were generated from 10 patients (HLA-0201) with advanced cancer by culturing CD14+ blood monocytes in the presence of GM-CSF and IL-4 supplemented with TNF-α [DCT] or TNF-α and IFN-α [DCTI]. The capacity of the DCs to induce functional CD8+ T cell responses to hTERT HLA-0201 restricted nonapeptides was assessed by MHC tetramer binding and peptide-specific cytotoxicity. Each DC preparation (DCT or DCTI) was pulsed with only one type of hTERT peptide (p540 or p865) and both preparations were injected into separate lymph node draining regions every 2–3 weeks. This vaccination design enabled comparison of efficacy between DCT and DCTI in generating hTERT peptide specific CD8+ T cells and comparison of class I hTERT peptide (p540 or p865)-loaded DCT with or without class II cognate help (p766 and p672) in 6 patients. T regulatory cells were evaluated in 8 patients.

Results

(i) DCTIs and DCTs, pulsed with hTERT peptides, were comparable (p = 0.45, t-test) in inducing peptide-specific CD8+ T cell responses. (ii) Class II cognate help, significantly enhanced (p < 0.05, t-test) peptide-specific CD8+T cell responses, compared with class I pulsed DCs alone. (iii) Clinical responders had significantly lower (p < 0.05, Mann-Whitney U test) T regs, compared with non-responders. 4/16 patients experienced partial but transient clinical responses during vaccination. Vaccination was well tolerated with minimal toxicity.

Conclusion

Addition of IFN-α to ex vivo monocyte-derived DCs, did not significantly enhance peptide-specific T cell responses in vivo, compared with TNF-α alone. Class II cognate help significantly augments peptide-specific T cell responses. Clinically favourable responses were seen in patients with low levels of circulating T regs.

IFN-alpha in the generation of dendritic cells for cancer immunotherapy

Dendritic cells (DCs) play a crucial role in linking innate and adaptive immunity, by virtue of their unique ability to take up and process antigens in the peripheral blood and tissues and, upon migration to draining lymph nodes, to present antigen to resting lymphocytes. Notably, these DC functions are modulated by cytokines and chemokines controlling the activation and maturation of these cells, thus shaping the response towards either immunity or tolerance.An ensemble of recent studies have emphasized an important role of type I IFNs in the DC differentiation/activation, suggesting the existence of a natural alliance between these cytokines and DCs in linking innate and adaptive immunity. Herein, we will review how type I IFNs can promote the ex vivo differentiation of human DCs and orient DC functions towards the priming and expansion of protective antitumor immune responses. We will also discuss how the knowledge on type I IFN-DC interactions could be exploited for the design of more selective and effective strategies of cancer immunotherapy.

Induction of CD83+CD14+ nondendritic antigen-presenting cells by exposure of monocytes to IFN-alpha

IFN-alpha is a well-known agent for treatment of viral and malignant diseases. It has several modes of actions, including direct influence on the immune system. We investigated IFN-alpha effects on PBMC in terms of dendritic cell (DC) differentiation, as PBMC are exposed to high IFN-alpha levels during treatment of infections and cancers. We show that in vitro IFN-alpha exposure induced rapid and strong up-regulation of the DC-maturation markers CD80, CD86, and CD83 in bulk PBMC. Consistently, IFN-alpha induced up-regulation of these molecules on purified monocytes within 24 h. Up-regulation of CD80 and CD83 expression was IFN-alpha concentration-dependent. In contrast to GM-CSF + IL-4-generated DCs, most of the IFN-alpha-challenged CD83(+) cells coexpressed the monocyte marker CD14. Despite a typical mature DC immunophenotype, IFN-alpha-treated monocytes conserved phagocytic activity and never acquired a dendritic morphology. In mixed lymphocyte reactions IFN-alpha-treated monocytes were less potent than GM-CSF + IL-4-generated DCs but significantly more potent than untreated monocytes to induce T cell proliferation in bulk PBMC. However, only GM-CSF + IL-4-generated DCs were able to induce a significant proliferation of naive CD4(+) T cells. Notably, autologous memory CD4(+) T cells proliferated when exposed to tetanus toxoid-pulsed IFN-alpha-treated monocytes. At variance with untreated or GM-CSF + IL-4-exposed monocytes, those challenged with IFN-alpha showed long-lasting STAT-1 phosphorylation. Remarkably, CD83(+)CD14(+) cells were present in varicella skin lesions in close contact with IFN-alpha-producing cells. The present findings suggest that IFN-alpha alone promptly generates nondendritic APCs able to stimulate memory immune responses. This may represent an additional mode of action of IFN-alpha in vivo.

Ex vivo recovery and activation of dysfunctional, anergic, monocyte-derived dendritic cells from patients with operable breast cancer: critical role of IFN-alpha

BACKGROUND

Dendritic cells (DCs) play a crucial role in initiating effective cell-mediated immune responses, but are dysfunctional and anergic in breast cancer. Reversal of this dysfunction and establishment of optimal DC function is a key prerequisite for the induction of effective anti-cancer immune responses.

RESULTS

Peripheral blood DCs (PBDCs) and lymph node DCs (LNDCs) generated in vitro from adherent cultures of peripheral blood monocytes (PBMs) and lymph node monocytes (LNMs), respectively, using the 4 cytokine conditioned medium (CCM) (GM-CSF+IL-4+TNF-alpha+IFN-alpha) or 3 CCM (GM-CSF+IL-4+TNF-alpha) demonstrated a significantly higher degree of recovery and functional capacity in a mixed lymphocyte DC reaction (MLDCR, p < 0.001), expressed significantly higher levels of HLA-DR, CD86, compared with 2 CCM (GM-CSF+IL-4) or medium alone generated DCs from PBMs and LNMs (p < 0.001). The PBDCs generated with 3 CCM or 4 CCM showed a significantly (p < 0.001) enhanced macropinocytotic capability (dextran particles) and induced increased production and secretion of interleukin-12p40 (IL-12p40) in vitro (p < 0.001), compared with PBDCs generated from monocytes using 2 CCM or medium alone. Lipopolysaccharide (LPS) stimulation of PBDCs generated with 4 CCM demonstrated enhanced secretion of IL-6 but not IL-12p70, compared with control DCs unstimulated with LPS (p < 0.001).

CONCLUSION

Dysfunctional and anergic PBDCs and LNDCs from patients with operable breast cancer can be optimally reversed by ex vivo culturing of precursor adherent monocytes using a 4 CCM containing IFN-alpha. Maximal immunophenotypic recovery and functional reactivation of DCs is seen in the presence of IFN-alpha. However, 4 CCM containing IFN-alpha generated-PBDCs, do not produce and secrete IL-12p70 in vitro.

Human monocytes represent a competitive source of interferon-alpha in peripheral blood

Interferon-alpha (IFN-alpha) has a critical role in antiviral immunity and plasmacytoid dendritic cells (pDCs) have been demonstrated as the principal IFN-alpha source after Toll-like receptor (TLR) 7 and 9 stimulation. Little is known about the contribution of pDC-independent IFN-alpha sources to total IFN-alpha production capacity of human peripheral blood. Using an array of pathogen associated molecular patterns (PAMPs), Poly(I:C)/Dotap represented the second strongest IFN-alpha stimulus in total PBMC. Poly(I:C)/Dotap induced three times more IFN-alpha, when compared to TLR7-stimulation (R848) and four times less, when compared to TLR9-stimulation. Dotap (mediator of cellular uptake) dramatically increased Poly(I:C)-induced IFN-alpha production. Sorting experiments and ELISpot assays revealed that monocytes and not myeloid DCs are the main IFN-alpha source after Poly(I:C)/Dotap stimulation. ELISpot analyses demonstrated the highest IFN-alpha spot numbers after Poly(I:C)/Dotap stimulation. Although pDCs produced highest IFN-alpha levels per cell, monocytes represent a competing IFN-alpha source in total PBMC due to their high frequency.

Current approaches in dendritic cell generation and future implications for cancer immunotherapy

The discovery of tumor-associated antigens, which are either selectively or preferentially expressed by tumors, together with an improved insight in dendritic cell biology illustrating their key function in the immune system, have provided a rationale to initiate dendritic cell-based cancer immunotherapy trials. Nevertheless, dendritic cell vaccination is in an early stage, as methods for preparing tumor antigen presenting dendritic cells and improving their immunostimulatory function are continuously being optimized. In addition, recent improvements in immunomonitoring have emphasized the need for careful design of this part of the trials. Still, valuable proofs-of-principle have been obtained, which favor the use of dendritic cells in subsequent, more standardized clinical trials. Here, we review the recent developments in clinical DC generation, antigen loading methods and immunomonitoring approaches for DC-based trials.

Innate immunity modulates autoimmunity: type 1 interferon-beta treatment in multiple sclerosis promotes growth and function of regulatory invariant natural killer T cells through dendritic cell maturation

Type 1 interferon-beta (T1IFN-beta) is an innate cytokine and the first-choice therapy for multiple sclerosis (MS). It is still unclear how T1IFN-beta, whose main function is to promote innate immunity during infections, plays a beneficial role in autoimmune disease. Here we show that T1IFN-beta promoted the expansion and function of invariant natural killer (iNKT) cells, an innate T-cell subset with strong immune regulatory properties that is able to prevent autoimmune disease in pre-clinical models of MS and type 1 diabetes. Specifically, we observed that T1IFN-beta treatment significantly increased the percentages of Valpha24(+) NKT cells in peripheral blood mononuclear cells of MS patients. Furthermore, iNKT cells of T1IFN-beta-treated individuals showed a dramatically improved secretion of cytokines (interleukins 4 and 5 and interferon-gamma) in response to antigenic stimulation compared to iNKT cells isolated from the same patients before T1IFN-beta treatment. The effect of T1IFN-beta on iNKT cells was mediated through the modulation of myeloid dendritic cells (DCs). In fact, DCs modulated in vivo or in vitro by T1IFN-beta were more efficient antigen-presenting cells for iNKT cells. Such a modulatory effect of T1IFN-beta was associated with up-regulation on DCs of key costimulatory molecules for iNKT (i.e. CD80, CD40 and CD1d). Our data identified the iNKT cell/DC pathway as a new target for the immune regulatory effect of T1IFNs in autoimmune diseases and provide a possible mechanism to explain the clinical efficacy of T1IFN-beta in MS.

Interferon-alpha and cancer: mechanisms of action and new perspectives of clinical use

Interferons-alpha (IFN-alpha) are pleiotropic cytokines belonging to type I IFNs, extensively used in the treatment of patients with some types of cancer and viral disease. IFN-alpha can affect tumor cell functions by multiple mechanisms. In addition, these cytokines can promote the differentiation and activity of host immune cells. Early studies in mouse tumor models showed the importance of host immune mechanisms in the generation of a long-lasting antitumor response after treatment of the animals with IFN-alpha/beta. Subsequently, an ensemble of studies based on the use of genetically modified tumor cells expressing specific IFN molecules provided important information on the host-mediated antitumor mechanisms induced by the local production of IFN-alpha. Of note, several studies have then underscored new immunomodulatory effects of IFN-alpha, including activities on T cells and dendritic cells, which may lead to IFN-induced antitumor immunity. In addition, recent reports on new immune correlates in cancer patients responding to IFN-alpha represent additional evidence on the importance of the interactions of IFN-alpha with the immune system for the generation of a durable antitumor response. On the whole, this knowledge suggests the advantage of using these cytokines as adjuvants of cancer vaccines and for the in vitro generation of highly active dendritic cells to be utilized for therapeutic vaccination of cancer patients.

Clinical results of vaccine therapy for cancer: learning from history for improving the future

Active, specific immunotherapy for cancer holds the potential of providing an approach for treating cancers, which have not been controlled by conventional therapy, with very little or no associated toxicity. Despite advances in the understanding of the immunological basis of cancer vaccine therapy as well as technological progress, clinical effectiveness of this therapy has often been frustratingly unpredictable. Hundreds of preclinical and clinical studies have been performed addressing issues related to the generation of a therapeutic immune response against tumors and exploring a diverse array of antigens, immunological adjuvants, and delivery systems for vaccinating patients against cancer. In this chapter, we have summarized a number of clinical trials performed in various cancers with focus on the clinical outcome of vaccination therapy. We have also attempted to draw objective inferences from the published data that may influence the clinical effectiveness of vaccination approaches against cancer. Collectively the data indicate that vaccine therapy is safe, and no significant autoimmune reactions are observed even on long term follow-up. The design of clinical trials have not yet been optimized, but meaningful clinical effects have been seen in B-cell malignancies, lung, prostate, colorectal cancer, and melanoma. It is also obvious that patients with limited disease or in the adjuvant settings have benefited most from this targeted therapy approach. It is imperative that future studies focus on exploring the relationship between immune and clinical responses to establish whether immune monitoring could be a reliable surrogate marker for evaluating the clinical efficacy of cancer vaccines.

TLR7 ligands induce higher IFN-alpha production in females

IFN-alpha exercises multiple immune modulatory and antiviral activities and has been suggested to play a critical role in the pathogenesis of systemic lupus erythematosus (SLE). Plasmacytoid dendritic cells (pDCs) release IFN-alpha upon TLR7 and TLR9 ligation. With respect to the nine times higher incidence of SLE in women and the clinical use of synthetic TLR ligands as novel immune adjuvants, we analyzed IFN-alpha and TNF-alpha production in healthy human individuals. Blood samples were incubated with synthetic TLR7 and TLR9 ligands. In three independent groups (n(1) = 120, n(2) = 101, and n(3) = 123), analysis revealed a capacity of female PBLs to produce significantly higher IFN-alpha levels after TLR7 stimulation (p(1) < 0.0000001, p(2) < 0.0000001, and p(3) < 0.0001) compared with male PBLs. In contrast, no sex differences were evident after TLR9 stimulation. TNF-alpha production after TLR7 stimulation and also total pDC numbers were not different between females and males. X-inactivation escape of the TLR7 gene was investigated in monoclonal B cell lines and, independently, in pDCs after cell sorting and single-cell picking, indicating regular silencing of one TLR7 allele in females. Additionally, exogenous 17beta-estrogen and estrogen receptor antagonism did not indicate a significant role on TLR7-induced IFN-alpha production. Our data reveal for the first time a profound sex-dependent pathway of TLR7-induced IFN-alpha with higher production in females. These findings may explain the higher prevalence of SLE in females and the reported decreased therapeutic efficacy of synthetic TLR7 ligands in male individuals.

Dendritic cells interacting mainly with B cells in the lymphoepithelial symbiosis of the human palatine tonsil

The lymphoepithelial symbiosis (LES) of the human palatine tonsil is composed of spindle- or star-shaped epithelial cells forming a loose meshwork, containing numerous lymphocytes and dendritic cells (DCs). In the present study, we immunohistochemically characterized DCs in the LES (LES-DCs). LES-DCs were phenotypically immature DCs that were S100beta+, fascin-, HLA-DR+, CD1a-, CD80-, CD83-, CD86-, and CD123-. The most characteristic feature of LES-DCs was that they contacted many B cells, which were mostly IgM+ IgD+ resting naive B cells. Langerhans cells (LCs) located in the nonsymbiotic squamous epithelium were immature DCs that were S100beta+, fascin-, and CD1a+ and did not contact lymphocytes. In contrast to LES-DCs, interdigitating dendritic cells (IDCs) in the T zone were mature DCs that were HLA-DR+, CD1a-, fascin+, CD80+, CD83+, and CD86+ and contacted numerous CD4+ T cells. Two subsets of IDC, S100beta+ fascin+ IDC (IDC-1) and S100beta- fascin+ IDC (IDC-2), were identified, and the majority of IDCs are IDC-2. In contrast to IDCs, which were distributed in the T-cell area in groups, LES-DCs were distributed along the crypt as if forming a barrier. These findings suggest that LES-DCs are a novel type of DC playing an important role in the induction of humoral immune response against incoming air- or food-borne pathogenic antigens.

Review: Milstein Award lecture: interferons and cancer: where from here?

Interferons (IFNs) remain the most broadly active cytokines for cancer treatment, yet ones for which the full potential is not reached. IFNs have impacted positively on both quality and quantity of life for hundreds of thousands of cancer patients with chronic leukemia, lymphoma, bladder carcinoma, melanoma, and renal carcinoma. The role of the IFN system in malignant pathogenesis continues to enhance understanding of how the IFN system may be modulated for therapeutic advantage. Reaching the full potential of IFNs as therapeutics for cancer will also result from additional understanding of the genes underlying apoptosis induction, angiogenesis inhibition, and influence on immunologic function. Food and Drug Administration (FDA) approval of IFNs occurred less than 20 years ago; after 40 years, third-generation products of early cytotoxics, such as 5- fluorouracil (5FU), are beginning to reach clinical approval. Thus, substantial potential exists for additional application of IFNs and IFN inducers as anticancer therapeutics, particularly when one considers that their pleiotropic cellular and molecular effects have yet to be fully defined.